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SERVICEMANUALREVWON 1 SEPT. 1995

CanonFY8-13DW010

COPtiGHT 1995 CANON INC.CANOh NP6012/NP6012F/NP60212 REV, 1 SEPT. 1995 PRI NTED IN J APAN

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GENERAL DESCRlPTlONl

,I-. , I.J 1.

2.

3.

4.,/*--,~

_I 5.

,.-,

FEATURESFixed copyboard with zooming.In addition to the default reproduction ratios, a ratio between 70% and 141% may be

selected.Designed with considerations for the environment.

The use of a charging roller helps to limit the generation of ozone; average of 0.01 ppm orless, maximum of 0.02 ppm or less. (i/100 to l/O00 of existing machines)

Uses a SURF fixing assembly.The use of the SURF fixing mechanism enables a 0-set wait time.In addition, the maximum power consumption is 0.98 kW or less.Cassette accommodating various types of paper and 2-way pick-up.

The universal cassette (about 250 sheets) accommodates paper of sizes betweenAULTR and A5lSTMT.In addition, sheets as large as AWLTR to business card may be used (manual).

Separate top unit.The copiers top unit may be opened to make jam removal easy.

COPYRGHT 0 1335CANONI NC. CANON NP6012~NPW2F/NP6212 REV.1 SEPT.1995 PAWED IN JAPAN IMPRIB~ AU JAPONJ l-l

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II. SPECIFICATIOMSA. Copier1. Type&. )dy' ~/ ' Deskt op IGe~*uir& Fi xed.Lightsowcf? Fluorescentamp (17 Wl . en$ Fi xed ensarrayPhutow&l vf 9m~dbm OPC (24 di a. )

2. System

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GENERAL DESCRlPTlONl

3. Performance

postcard*, transparencies*, business card (ZOOg/m2 or less, 51X88 mm or

Copy Wiy 100 sheets (approx.; A4, 80 g/m* paper)Elan&qe k&il@%ddge 2.Ok1.5 mm /0.08kO.O6 in. (two-sided/overlay/one-sided)@MI LefRighf 0.0+2.0-0.0 (A4), 0.0+4.0-0.0 (LGULTR) (two-sided/overlay/one-sided)Aitk f3ower oii Available (about 5 min; fixed)As recommended bv Canon.Single feeding only.

_-

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4. Others

810.60 to 101325hPaSerial number

NP6012NUB xxxxx, NUC xxxxx

NP6012FNUE xxxxx

wwk ; Serial number2&Q&@+ NP6012 NP6212: ..r*onlr.. PTF xxxxx, UTG xxxxx, RTG xxxxx, PTH xxxxx,. ,, TFA xxxxx

0.9 kW or lessabout 20 W with scanning lamp heater ONabout 17 W with scanning lamp heater OFF(approx.; about 5 min; reference only)cwhi, 0.4 kWh (approx.; reference only)

N&e ti%&m&y ___.capyh?g ,/66 dB or less (sound power level under ISO)

OXme 0.01 ppm or less (average), 6.02 ppm or less (max.)478 mm /I 8.8 in (approx.)453 mm D7.8 in (approx.)290 mm 01.4 in (approx.),20.0 kg /44.0lb (approx.; including cassette)

~ Copy paper Keep wrapped to protect against humidity.T#r-@r. Avoid direct sunshine; keep at 4OC/85% or less.

l-4 MPYRIGHT1895 ANONNC. CANONPBOiZNP60i2E/NP6212EV.1EPT.995RINTEDN APANIMPRIMEU APON)

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DIRECT

Table l-101B. ADF

COPVAl Gt i l 1995 ANONI NC. CANON NP6012/ NP6012F/ NP6212EV. 1EPT. 1995Al NTEDI NJ APAN( I MPRI M~AUJ APON) l -5

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III. NAMES OF PARTSA. External View1. NP6012

Static eliminator cleaner @ Right doorSlide guide @ CassetteMultifeeder @ Copyboard glass

Figure 1.,301

0 Copyboard cover@I Scanning lamp heaterswitch

Figure l-302

Copy density correctiondial

l-6 COPYRI GHT 1995 ANONI NC. CANON NP60121NP6012FI NP6212EV. 1 EPT. 1995RlNTEOI NJ APAN(I MPRI M AUJ APON)

Static eliminatorDelivety guide plate

Figure l-303

@ Copy tray@ Power cord connector8 Open/close lever

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GENERALDESCAI PTI ONI

2. NP6012F I NP6212

0 ADF0 Slide guide@ Multifeeder@I Right door0 Cassette8 Copyboard glass

Figure l-304 Figure l-305

0 Scanning lamp heaterswitch

0 Copy density correction @ Delivery guide plate @ Open/close leverY? dial @ Copy tray 0 Static eliminator cleanerII @I Static eliminator @ Power cord connector

.,.- Figure l-306

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B. Cross Section1. Copier

0 No. 3 mirror0 No. 2 mirror@ No. 1 mirror@ Scanning lamp@ Heat exhaust fan@ Drum unit0 Lens array@ Pre-exposure lamp@ No. 1 charging rollercleaning pad@ Side blank exposure lamp@ No. 6 mirror

Reflecting plateNo. 4 mirrorNo. 5 mirrorCopyboard glassCopyboard coverMultifeeder trayCassette pick-up rollerMuttifeeder pick-up rollerDeveloping assemblyRegistration rollerDeveloping cylinderTransfer roller

Figure l-3072.ADF

?

Static eliminatorPhotosensitive drumFeeding assemblyPrimary charging rollerCassetteFixing film tension rollerFixing filmLower fixing rollerFixing film drive rollerDelivery rollerDelivery tray

@ Delivery roller@ Delivery tray@ Pick-up roller@ Original tray

l-8 COPYRI GKT 1995 ANONI NC. CANON NP6012/ NP6012F/ NP6212EV. 1 EPT. 1995Rl NTEDI NJ APAN( I MPRI M AUJ APDN)

Auxiliary trayGuide plateSeparation padRegistration roller

Figure l-308

@ Feeding belt drive roller@ Feeding beltQjJFeeding belt roll@ Feeding belt link roller

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GENERALDESCRIPTI ONI

_~./ /\ IV. OPERATIONSA. Control Panel1. NP6012

Ad I0 @l 000 OBFigure l-401a (Inch-configuration)

6Figure l-401 b (ABllnch-configuration)

Figure 1-401~

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2. NP601ZNP6212

Figure 1-40ld (NP6012F)

Figure l-401e (NP6212)

Figure l-40if ,

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B. Basic Copying Operations1) Turn on the power switch.

The wait time is 0 sec.The auto power-off mechanismbecomes activated to automaticallyturn off the power if no key is operatedin about 5 min.2) If you are not using the ADF, lift the

copyboard cover, and place an originalface down along the size index.a. Place the original so that its center

is aligned against the arrow (+);then, bring down the copyboardcover.

Figure l-402

i Load paper up to here

Figure l-403

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, _\\,

, in

/-.

,Y-, i

3)

4)

5)6)

7)

If you need to manually adjust the copydensity, deselect AE and use the CopyDensity Adjust lever.As necessary, press the Default Ratiokey or Zoom key.When you press the Zoom key, %appears on the Copy Count/Ratioindicator so that you may set theratio between 70% and 141% in 1%increments.

% disappears if the Copy Count/Ratio key is not operated in about 3sec.When you press the Default Ratiokey, the ratio changes as follows foreach press:

MAX. 141 +

(Inch- configuration)

BSbAS/STMT

1

(AB/lnch- configuration)If you are using the multifeeder, pressthe Paper Select key.Check that the % notation on the CopyCount/Ratio indicator has turned off;then, set the number of copies to makeusing the Copy Count/Zoom Set key.(The count should appear on the CopyCount indicator.) ress the Copy Start key.a. As may copies as you have speci-fied will be made automatically.b. No other keys than the Clear/Stop

key or Copy Density adjustmentlever/AE OFF will be accepted until

C

d.

e.

the last copy has been made.You may switch from automatic den-sity adjustment mode to manualdensity adjustment mode betweencopying has started and the lastcopy is made; however, you cannotswitch from manual density adjust-ment mode to automatic densityadjustment.When copying is finished, the CopyCount indicator indicates the initialcopy count. If copying stopped as aresult of the absence of paper, apress on the Copy Start key aftersupplying paper will automaticallymake the remaining number ofcopies.To stop copying operation duringcontinuous copying, press theClear/Stop key; the ongoing copyrun is finished before the operationstops. (At this time, the Copy Countindicator indicates the initial count.)If paper jams, the JAM indicator willflash and copying operation stops;open the top unit. (The power turnsoff when the top unit is opened forremoval of the jam.)After copying operation is over, theauto power-off mechanism becomesactivated if the copier is left alone forabout 5 min without further keyoperation, automatically turning offthe power.

1. Using Transparencies1) Shift the delivery guide plate on the copy

tray upright.

Figure l-404

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2)3)

4)

5)

6)7)

6)

Place an original on the copyboard, andclose the copyboard cover.If you want to manually adjust the copydensity, deselect AE, and operate theCopy Density Adjust lever.Press the Default Ratio key or ZoomMode key to suit the reproduction ratioyou want.a. When you press the Zoom key, youmay set the ratio between 70% and

141% in 1% increments.b. When you press the Default Ratiokey, the ratio changes as follows for

each press:r MAX. 141 7

MARGIN 86LGL b LTR 8

(Inch- configuration)

LBSbAS/STMTA4 b A5(ANInch- configuration)

2)

3)

Place a single transparency on the sin-glefeeder.

You must not set more than one trans-parency on the singlefeeder.Select the multifeeder using the PaperSelect key.Set the copy count you want using theCopy Count/Zoom Set key; then, checkthe Copy Count indicator.Press the Copy Start key.

Be sure to remove each transparencydelivered to the copy tray before thenext one is delivered.

Figure l-406

1-14 COPYRI GHT 1995 ANONI NC. CANON NP6012/ NP6012F/ NP6212EV. 1 EPT. 1995Rl NTEDI NJ APAN( I MPRI M~AUJ APON)

If the Transparency Is Not Picked UpSmootlilyUnder certain environmental conditions,

transparencies may fail to move into themachine in response to a press on theCopy Start key. If this is the case, gothrough the following:1) Place copy paper underneath the trans-

parency with a displacement of about 1cm.8

Transparency

VCopypaperFigure l-405

Set the transparency together with thecopy paper on the multifeeder whileholding the trailing edge of the copypaper.Press the Copy Start key while still hold-ing the trailing edge of the copy paper;hang on to the copy paper, and removeit when the transparency has disap-peared into the machine.

N I

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/-.-

_-- \/

_,--

C

2. Making Two-Sided Copies 0You can make two-sided copies usingthe multifeeder; however, you must keep the gfollowing in mind:0 After the first copy run, turn over the @

copy paper and set it as shown in Figurel-406 8

Figure l-407

Make sure the paper is not moist.Make sure that the paper is not curled.Make sure that the paper is of 64 to 126g/m2 (business card, 200 g/m* or less).In the case of a two-sided copy, eachside may not be used more than once.After the first copy run, cool the papersufficiently and remove the curl beforefeeding it for the second copy run.

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C. User Mode1. OutlineThe copier offers user mode which may be used by the user to change various settings.-Ear

2

3

4

5

-

Ul Primary charging rollercleaning mode

Executes cleaning of theprimary charging roller.The cleaning lasts about3 set, and stopsautomatically.

u2 Copy count indicationmode

Indicates the number of Only in model with drcopies made by the unit replacement timeinstalled drum unit. automatic indication

function.Only in model with drunit replacement timfautomatic indication

u3 Drum unit replacementindicator off mode

Turns off the flashingReplace Drum Unitindicator.

U6 ADF cleaning mode Clean the ADFs originalfeeding path.

u7 Installation/drum unitreplacement mode

Used to enter data Only in model withounecessary when installing drum unit replacemelthe machine or replacing time automatic indicathe drum unit. function.Further, execute it afterexecuting 34 or 37 inservice mode.

urn

urn

)nly.

tIttion

Table l-402

l-16 CGPYRIGHT1995 ANONNC.

-

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GENERALDESCAIPTI ONI

2. Using User Mode1) Turn on the copier, and hold down theAE key for 4 set or more.

Ul appears on the count/ratio indica-tor.

Figure l-4082) Press the +/- key so that the appropriatefunction number (Ul through U7)

appears.3) To end user mode, press the AE key.

3.1)

Primary Charging Roller CleaningMode (Ul)Operate so that Ul appears on thecount/ratio indicator; then, press theCopy Start key.Ui starts to flash to indicate the exe-

cution of cleaning; cleaning takesabout 3 sec.Ul stops flashing and remains onwhen cleaning is finished.

Figure l-4092) To end user mode, press the AE key.

The AE key remains disabled whileuser mode is being executed.

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4. Copy Count Indication Mode* (U2)*Only for a model with the drum unit

replacement time automatic indication func-tion1) Operate so that U2 appears on thecount/ratio indicator; then, press the

Copy Start key.

Figure l-410The count/ratio indicator alternatelyindicates the 1000s and the 100s; forexample, in the case of 12345, it indi-cates 1 and 23 alternately.

2) To end user mode, press the Copy Startkey and then the AE key.The AE key remains disabled while a

copy count is being indicated.

7

5. Drum Unit Replacement Off Mode*(U3)Only for a model with the drum unit

replacement time automatic indication func-tion.1) Operate so that U3 appears on thecount/ratio indicator; then, press theCopy Start key.

U3 remains; however, the ReplaceDrum Unit indicator stops flashing andgoes out.

Figure 1-411

2) To end user mode, press the AE key.

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6.1)

2)

ADF Cleaning Mode (NP6012/NP6212only)Place about 10 sheets of white copypaper on the original tray of the ADF.Operate so that U6 appears on thecount/ratio indicator; then, press theCopy Start key.The sheets of copy paper on the origi-

nal tray of the ADF will be picked up in

Figurel-4123) To end user mode, press the AE key.7. Installation/Drum Unit Replacement

Mode (U7)*Only for a model with the drum unitreplacement time automatic indication func-tion.1) Operate so that U7 appears on thecount/ratio indicator; then, press the

Copy Start key.The indication changes to 71.

2) Using the +I- key, enter the value ofPRIMARY recorded on the drum unit.Appears in the top left of the

count/ratio indicator while a value isbeing entered.

Figure 1-4143) After entering the value of PRIMRY,

press the Copy Start key to store thevalue.A press on the Copy Start key

changes the indication to 72.

Figure l-415

Figure 1-413

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4) Using the +I- key, enter the value underIP_OFST recorded on the drum unit.Appears in the top left of thecount/ratio indicator while a value isbeing entered. I

Figure 1-4165) After entering the value of IP_OFST,

press the Copy Start key to store thevalue.A press on the Copy Start keychanges the indication to 73.

Figure 1-417

6) Press the Copy Start key to executedrum sensitivity automatic adjustmentand toner stirring.The main motor will rotate, and drumsensitivity automatic adjustment andtoner stirring will start.After the execution, the copier endsuser mode automatically and stopsoperation in about 1 min.A press on the AE key while the aboveexecution is taking place ends usermode; however, the AE key will not beaccepted while a setting is displayedor the main motor is rotating.

I I

Figure 1-416

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F. Replace Toner Cartrid elndlcator (m) and Action 1oTakeThe replace toner cartridge indicator (m)

starts to flash when toner runs out; performthe following to replenish the cartridge:1) Lift the body open/close lever to open

the body.

3) Hold the toner cartridge level. and shake Yit left and right several times.

>

Figure 1-4212) Turn the toner cartridge clockwise until itstops, and pull out the cartridge.

Figure l-4234) Insert the toner cartridge carefully until it

stops.

Figure l-424

Figure l-422

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,,--.

,--

5) While holding the toner cartridge inplace, pull the OPEN seal straight to thefront to peel it.

Figure l-425

6) Turn the toner cartridge counterclock-wise until it stops.

Figure l-4267) Press on the 6 mark on the body toclose it firmly.

G. Using the DensityCorrection DialIf the copy density is too,high, i.e., the

image is too dark, in density adjustmentmode (AE or manual), you may adjust thecopy density using the Density Correctiondial.1) Shift up the open/close lever to open thebody.2) Adjust the position of the density correc-tion dial.

Figure l-427

ACaution:Do NOT throw the toner cartridge into fire;it can burst or explode.

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H. Using the Scanning LampHeater SwitchIf the site of installation is subject to lowtemperature or the first time copy is subjectto a delay, make use of the scanning lampheater to prevent problems.

heater switchFigure l-428

l-24 COPYRI GHT 199. 5ANONI NC. CANON NP6012/ NP6012Ff NP6212EV1 SEPT. 1995Al NTEDI NJ APAN( I YPRI M AUJ APON)

I. CleaningIf the images tend to be soiled or copy

paper tends to jam frequently, advise theuser to clean the following parts:

I - I.

1. If Images are Soileda. Copyboard Glass/Copyboard CoverWipe it with a moist cloth; then, dry wipe

it. If the dirt cannot be removed, wipe it witha cloth moistened with mild detergent solu-tion, and dry wipe it.b.1)2)3)

Cassette Pick-Up RollerRemove the cassette.Open the right cover.Keep the separation pad down, wipe thecassette pick-up roller with a cloth moist-ened with alcohol or water* while rotat-ing the roller in the direction of pick-up.*Be sure to wring it well.

Cassette pick-up roller

,--_

Separationpad

Figure l-429

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C1)2)3)8

Multi Pick-Up RollerLift the open/close lever to open thebody.Place one sheet of copy paper (A4) inthe feeding path.Keep the separation pad down, andwipe the multi pick-up roller with a clothmoistened with alcohol or water* whilerotating the multi pick-up roller in thedirection of pick-up.*Be sure to wring it well.

Separation pad\Multi pick-up roller

/

CopypaperFigure l-430

d.1)

e.1)

2)

Feeding Belt (NP6012F/NP6212 only) IWipe the feeding belt while moving It rnthe direction of the arrow with a clothmoistened with water; be sure to wringthe cloth well.

Figure 1-431Separation Pad(NP6012F/NP6212 only)Remove the ADF from the copier. (SeeIX. of CHAPTER 4 for the steps to fol-low.)Detach the separation pad cover using acoin or the like.

\ Separation pad

Figure l-432

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3) Remove the separation pad unit.

Figure l-433Dry-wipe the surface of the separationpad.

Surface of the

Figure l-434Install the separation pad unit while ori-enting it as indicated.

Figure l-435

l-26 COPYRIGHT 1995 ANONI NC CANON NP6012l NP6012FI NP6212EV. l EPT.1995RlNTEOI NJ APAN( I MPRI M~AUJ APON)

f. Pick-Up RollerYou must clean the pick-up roller when-ever vou have reolaced the seoaration Dad.1)2)

demove the separation pad unit.Wipe the pick-up roller while moving it inpick-up direction with a cloth moistenedwith alcohol or water; be sure to wringthe cloth well before bringing it into con-tact with the roller.

Pi ck-uprol l er

Figure l-436

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2. Frequent Jamsa. Static Eliminator1) Open the copyboard cover, and removethe static eliminator cleaner.

1

Figure l-437(NP6012)

2)3)

Shift up the open/close lever to open thebody.Clean the static eliminator with the staticeliminator cleaner.0 Brush out any dirt (paper lint, for

example) from the groove in thestatic eliminator.

Figure l-4394) Close the body as soon as you have fin-ished cleaning.

Figure l-438(NP6012F/NP6212)

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I GENERALDESCRI PTI ON

J. Points to Note WhenClosing the Top UnitMake sure of the following three points

before closing the top unit.1. The drum unit has been installed, andthe drum unit lever is at the LOCK posi-

tion.

Drum unit leverFigure l-440

2. The toner cartridge has been turned andpositioned as specified.

3. The fixing lever is at the LOCK position.

/Fixing leverFigure l-442

Unless the above three points are satis-fied, the lock mechanism will activate, pre-ventingthe top unit from closing.

Figure 1-441

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, 1\ I. IMAGE FORMATIONA. Outline

The copier uses a direct charging/transfer system with each component block arranged asshown in Figure 2-101.

,,-.

Copyboard glass

W Transfer charging rollerStatic eliminatorLower fixing roller

Figure 2-101

Latent static Image FormationI----- _~_________--------~-_

4. Development

- : Flow of copy paper Casselteimanual feedt-_ : Rotation of photosensitive drum

Figure 2-102

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The copiers image formation block con-sists of the following steps; see the descrip-tions for each step given under its respectiveheading:Step 1: pre-exposureStep 2: primary charging (-)Step 3: image exposureStep 4: development (AC + DC bias)Step 5: transfer (-)Step 6: separation (+)Step 7: fixingStep 8: drum cleaning

The photosensitive drum consists of twolayers: the outer layer being a photoconduc-tive layer made of organic photoconductor(OPC) and inner layer, a substrate made ofaluminum (conductor).

onductingate

Figure 2-103

B. Static Latent ImageFormation BlockThe static latent image formation block

consists #of tow steps: primary charging andimage exposure. At the end of, this block, theareas on the photosensitive drum corre-sponding to the black areas of the originalare left with negative charges and those cor-responding to the white areas of the originalare rid of negative charges.These images created by negativecharges are not visible to the human eyeand, therefore, are called static latentimages.

Time (t) -----)~ 0

13 -500Edx8 1Ecz - 1000Lightarea,,...._......~...

,

Primary1harging(step 1) Dark areaImage exposure(step 2)Figure 2-1042-2 COPYRI GHT 19%CANONI NC. CANON NP6012l NP6012F/ NP6212EV. 1EPT. 1995Rl NTEDI NJ APAN( I MPRI M~AUJ APON)

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,- ~\, C. Pre-Exposure (step 1)

43re-exposure

Figure 2-105Prior to primary charging, the light of the

pre-exposure lamp is directed to the surfaceof the photosensitive drum for pre-exposure,thereby removing the residual charges fromthe surface of the photoseneitive drum toprevent uneven copy density.

A

D. Primary Charging (step 2)

imary corona roller

Figure 2-106The surface of the photosensitive drumis charged to a uniform negative potential inpreparation for the formation of static latent

images.The copier uses its primary chargingroller to directly charge the photosensitive

drum (primary charging).The primary charging roller is made ofconducting rubber, and a DC bias is applied

to the roller.Reference:

A direct charging system provides suchadvantages as low application voltageand aenerates little. if anv. ozone.

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E. Image Exposure (step 3) F. Development (step 4)Optical image

Figure 2-107In this step, the optical image of the orig-inal is projected to the photosensitive drum

to neutralize the charges in the light area.

, Blade

1kfFigure 2-108As shown in Figure 2-108, the develop-

ing assembly consists of a rubber blade anda developing cylinder constructed of a fixedmagnet and a cylinder that rotates around it.The coprers toner is a one-component tonermade mostly of magnetite and resins. Thetoner has insulating characteristics andbecomes positively charged by the frictionbetween the rotating cylinder and the blade.

The toner is moved between the rotatingdeveloping cylinder and a blade, where it ischarged to a positive potential and depositedon the developing cylinder in a thin, uniformlayer.

The developing cylinder receives bothAC bias and DC bias (negative component)at the same time; the resulting bias is calleddeveloping bias For this reason, the nega-tive component of the developing bias isgreater than the positive component.

Figure 2-l 09

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,.--., During copying, the toner is attracted to, \ the photosensitive drum by the photosensi-tive drum surface potential and the develop-ment bias (positive component), thus turningthe static latent image into a visible image.Any excess toner is repelled by the photo-sensitive drum by the photosensitive drumsurface potential and the developing bias(negative component).

A DC bias affects copy density and thedegree of fogging; the higher, i.e., closer to 0V, it is, the darker the images will be-how-ever, with an increased tendency toward fog-ging.

G. Transfer (step 5)

er

sfer charging roller

Figure 2-110A negative voltage is applied to the backof copy paper to transfer toner from the sur-face of the transfer drum to the copy paper.The copier uses a roller transfer system,which has the following advantages when

compared with the conventional coronatransfer system:Generates virtually no ozone.Provides good feeding, since copypaper is retained by both the transfercharging roller and the photosensitivedrum.

Reference:Toner may collect on the transfer roller ifthe image on the photosensitive drumfails to transfer to the copy paperbecause of a jam or the like.The copier turns the transfer voltage topositive during initial rotation, while thescanner is moving in reverse, and duringpost rotation to return the positivelycharged toner adhering to the transferroller to the photosensitive drum.

Figure 2-111

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H. Separation (step 6)

\tatic eliminatorPressure roller dleaning roller

Figure 2-112 Figure 2-113Copy paper is separated from the photo-

sensitive drum using the rigidity of the paper.Thin paper, however, has low rigidity andcan wrap around the photosensitive drum.To prevent such a problem, the copierapplies a positive voltage to the separationstatic eliminator to weaken the static attrac-tion between the photosensitive drum andcopy paper, thereby facilitating separation.

After transfer, the toner image is fixed tothe paper while the copy paper movesthrough the fixing film and the pressureroller.

The fixing film has a seamless construc-tion and is made of special material so thatmelting toner will not stick to the film-fur-ther, the surface of the pressure roller iscleaned by a cleaning roller.

I. Fixing (step 7)Theryistor

The fixing heater is a flat heater andheats only the area where the fixing filmcomes into contact; this design eliminatesthe need for warm-up time.The temperature of the fixing heater ismonitored by the thermistor (THl) locatedmore or less at the center of the fixing heaterand serves to make sure that the heater iscontrolled to a specific temperature.

_

-

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II. AUXILIARY PROCESS1. Side Blank ExposureSide blank exposure is used to preventadhesion of excess toner to the drum byremoving the residual potential in the non-image areas (front, rear) of the drum. See p.3-35 for details.2. Nip ExposureIn nip exposure, part of the light from thepre-exposure lamp is directed to the areawhere the photosensitive drum is in contactwith the primary charging roller, therebyensuring the stability of primary charging.

Preexposurelamp Primary charging roller

_ : path of light (nip exposure)------ : path of light (pre-exposure)Figure 2-115

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.A--_, \ I. BASIC OPERATIONA. Functional Construction

The copier c&n roughly be divided into four functional blocks: namely, pick-up/feeding,exposure, image formation, and control.

I Iontrol panel

fontrolcircuitry,...........................................,~Exposure block

Optical path_...................

Figure 3-101

,,--

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B. Electrical CircuitryThe copiers major electrical control mechanisms are driven by the microprocessor on the

DC controller PCB. The microprocessor reads input signals from the sensors and the operationkeys in response to the instructions of the program stored in advance and generates signalsused to drive such loads as motors, solenoids, and lamps. ~

DC controller PCB Composite powersupply PCB

Scanner home positiondetectionLens home position detectionPreregistration roller paperdetectionDelivery paper detectionFilm displacement detectionWaste toner detectionCassette detection

(model with drum unitreplacement time automaticindicator function only)

I QIOI II CPU1+5+24V

t

ij

Primary chargingrollerDeveloping cylinder. Transfer chargingI. rollerf Static eliminator

Pick-up solenoidRegistration clutch solenoid

jyi solenoidScanner/lens drive switchingCassette/multifeeder pick-upswitching solenoid (PC750/770)Primary charging roller cleaningsolenoid. Transfer roller escape solenoid \

ISide blank exposure lamp

t

Scanner/lens drive motor

Pre-exposure lamp

-I ounterFigure 3-l 02

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,,- .IiC. Inputs to and Outputs from the DC Controller1. Inputs to the DC Controller (l/2)

DC controller PCB

Scanner home positionsensor

Lens home positionsensor

Mjlogl:j

Delivery sensor MT

Fixing filmdisplacement sensor

Waste toner sensor ME

Pre;registrationroller paper sensor

Cassette papersensorMain thermistor(thermal control)Sub thermistor(overheating)

+-I

A +5vSCHP

7,j +5v

LHP2DIG3DPD

: +5vFFD

-;I,3 +5v

when scanner is at home position, 0.(when light-blocking plate is at PSI, 0)

when lens is at home position, 1.(when light-blocking plate is at PSZ, 1)when PS3 detects paper, 1:(when light-blocking plate is at PS3, 0)

when PS4 detects fixing film, 0.(when light-blocking plate is at PS4, 0)

TNFULL when toner reaches specific level, 1.2 (when light-blocking plate is at PS5, 0)

2 +5vRPD when Q751 detects paper, 1.(when light-blocking plate is at Q751, 0)DIG2CPD

2THI

X TH2-;I,

when paper is present in cassette, 0.(when light-blocking plate is at Q752, 0)when surface temperature of fixing heaterrises, voltage lowers.when temperature of the rear end of fixingheater rises, voltage lowers.

Figure 3-103

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IOPERATIONS AND TIMING

2. Inputs to the DC Controller (2/2) /*yDC controller PCB /

AE sensor IntensityPCB sensor

PCBControlpanel

Jiir\I/I 1J301I I0 SW409

,-

Main switch

J I OZ- :p

Drum cartridge :

I:PGPPCB

(model with drum unitreplacement automaticindicator function only)

Toner level Compositedetection power supplyPCB PCB

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rNMONl

when reflected light increases, voltage lowers.when light from fluorescent lamp increases,voltage lowers.

Keys and LEDs are wired in a matrix on the controlpanel PCB; the DC controller reads the key inputsand turns on or flashes the LEDs.

Combinations of 3-bit signals are used to correctthe variations in the resistance of the fixing heaterin 7 settings.

-

when toner level drops, 0.

Figure 3-l 04

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D. Outputs from the DC Controller1. Outputs from the DC Controller(V2)

Composite power suppl y PCB DC contro ller PCBMain motor/ m J901- J205-$ +24V

Scanning lamp

J206-1 1

I,---\ \

Fixing heater Him J207-1

-2 ACdriverJ204-7 J104-.

Fluo-rescent _~ Micro.

lamp txocessor

Primary charging rollerDeveloping cylinderTransfer charging rollerStatic eliminator

driver 1 11 I

High-voltagecircuit

1-i + a t24V

Door switch

Figure 3-105

dt TRD

1MDtLOC~ See p. 3-7.

rFixing heater drivesignal; used to controlthe temperature of thefixing heater.

1Micro-processor

ICommunication withcomposite power supplyPC0

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2. Outputs from the DC Controller (2/2) . \DC controller PCB

Pick-up clutch solenoid when o, pick-up clutchsolenoid turns on.

Registration clutch solenoid when I, registration clutchsolenoid turns on.

Lens drive solenoid when 9, lens drive solenoidturns on.

Cassette/Multifeeder pick-upswitching solenoid

Scanner/lens drive motor

Jl IO-I f SC-COMB-2 SC-B*-3 SC-B during operation,-4 alternates between+ SC-COMAsoandml\,

(See p. 3-16 for details.)

Side blank exposure lamp (rear)KII=F61 sB-Lp*

Side blank exposure lamp (front)

Primary charging rollercleaning solenoid

Transfer charging rollerescape solenoid

J121-1 PEXP*Pre-exposure lamp PCB -2 +24VJ119-1 TCNTD*Total copy counter MCI -2 +24V

~..............

when O, primary chargingroller cleaning solenoid turnson.when 0, transfer chargingroller escape solenoid turnson.when 0, pre-exposure lampturns on.

when O, total counter turns on

~..............iDrum unit(model with drum unit replacement

time automatic indication function only) *Negative logic.Figure 3-106

when O, blank exposurelamp on.

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,r.- > E. Main Motor Control CircuitI1. Outline

1Figure 3-107 shows the circuit that con-trols the main motor (Ml); the circuit has thefollowing functions:0 turns on and off the main motor.@ controls the rotation of the main motor toa specific revolution.The main motor (Ml) is a DC motor witha built-in clock pulse generator. When themotor rotates, clock pulse signals (MMCLK)

are generated according to the revolution ofthe motor. The speed control circuit matchesthe phases of the frequency of these clockpulses and the frequency of the referencesignal to control the rotation of the mainI motor (Ml) to a specific revolution.

2. ODerationWhen the main motor drive signal(MMD) from the DC controller circuit goesl, the drive circuit of the motor driver turnson, thereby rotating the main motor (Ml) at aspecific revolution.

While the main motor is rotating at aspecific revolution, the main motor driverPCB sends the speed state signal(MLOCK=O) to the DC controller PCB. If, forsome reason, fluctuations occur in the rota-tion of the main motor, the MLOCK signalgoes I.

If MLOCK=l continues about 1 setwhile the main motor drive signal (MMD) isl, the DC controller identifies an error in themain motor, stops the main motor and, at thesame time, indicates EOIO on the display.

,,-.\I\

DC1rOlE

J 20103-6 -7

104- 6 J 204-

r

icII

31+($III

II,_

:ompositepowerSUPPlY

1iJ:+I1I

7IiIIIIIIj

05 J 90', - 6 24V - '

- 2 ov - :

- 2 MMD -

- 1 MLOCK - t

1PLL controldrive circuit I

57ntClock pulse

MMCLKI

Reference signal Main motor driver PCEFigure 3-107

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F. Basic Sequence of Operations (DIRECT, 2 copies, continuous) -.1. Copy Start Key On 3.2 Set (approx.) After Power-On ,.

Power switch Copy Start keyON ON

L?ZZEl: everseI : scanner home position detectionII : ens home position detection

Figure 3-108

,-I

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2. Copy Start Key On Immediately After Power-On (less than 3.2 set)

@Z: reverseI : scanner home posi t i on detecti onI I : l ens home posi t i on detecti on

Figure 3-109

I--

/---Y

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iTBYstandby)

\lTRnitial rotation)

CFWscanner forward)

SCRV(scanner reverse)

FWMBetween when the powerswitch is turned on andwhen the Copy Start key ispressed.Between when LSTR isover and when the CopyStart key is pressed.

or about 3.5 set after the:opy Start key is pressed.

while the scanner is movingorward.The distance traveledforward varies dependingon the copy paper size antreproduction ratio.The speed of forwardtravel varies depending onthe reproduction ratio.rVhile the scanner is movingn reverse.The speed of reversetravel is about 3.4 times asfast as forward travel inDIRECT.

-or about 1 set after SCRVor the last copy is over.

Waits until the Copy Start keybecomes valid.

. Removes the residualcharges from the photo-sensitive drum and stabilizesthe sensitivity of the photo-sensitive drum in preparatiorfor cpying operation.Pre-heats the scanning lampand makes preparations untithe drive intensity becomesstabilized.

The scanning lamp illuminatesthe original, and the reflectedoptical image is projected onthe photosensitive drum byway of mirrors and lenses.

The scanner is returned to thehome position in preparationfor the next copy run.

The last copy paper isdischarged.

Table 3-101

1EEFI

,I

I 11:cti

ItgF

Remarks /

-he pick-up signal islenerated, and the firssheet of copy paper isxcked up.

-he registration signals generated, and the:opy paper is movedo the transferassembly.

f in continuous mode,he pick-up signal isgenerated, and copyjaper is picked up.

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., -- II. EXPOSURE SYSTEMA. Varying the Reproduction

RatioThe reproduction ratio in the direction of

the drum axis is varied by the lens drive sys-tem and that around the drum, by the scan-ner drive system.

The lens drive system holds a lens arrayand changes the location of the lens and theoptical path length as shown in Figure 3-201to vary the reproduction ratio in the directionof the drum axis; the length of the opticalpath is changed by moving the No. 4 andNo. 5 mirror units as shown in Figure 3-202.The scanner drive system changes thereproduction ratio around the drum by mov-ing the No. 1 mirror faster (reduction) orslower (enlargement) relative to the periph-eral speed of the drum.Reference:

1. In DIRECT, the speed at which theNo. 1 mirror is moved is the same asthe peripheral speed of the drum.

2. The length of the optical path is longerin both REDUCE and ENLARGE thanin DIRECT.

p&h I*length

Opticalpath I4length

Opticalpath I*lengthOptical path: Li< L2, Li< L3

Figure 3-201

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Copyboard glass /-~ .,N N NENLARGE REDUCE ~ Movement in

-0 ENLARGE. REDUCE

1

L No. 45 mirror unit

Figure 3-202

/-

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/- - 8. Lens Drive System1. OutlineThe lens drive system is driven by the scanner motor (M2). When the lens solenoid (SL3)turns on, the switching gear is pushed in the direction of the arrow 0. When the scanner motorrotates in reverse (3) in this condition, the lens unit moves in REDUCE direction by the workof gears and lens cable.At the same time, the No. 4/5 mirror unit moves according to the travel (reproduction ratio)of the lens unit, changing the length of the optical path.At this time, the side blank exposure lamp also moves in relation to the lens to performblack erasure at the front and the rear.

0.4/5 mirror unit

Lens travel detecting shaft forside blank exposure lampDC controller PCB

Figure 3-203

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C. Scanner Drive System1. OutlineThe scanner drive system is driven by the scanner motor (M2), which changes its directionof rotation so that the scanner moves forward or in reverse. The revolution at which the scanneris moved forward changes continuously according to the selected reproduction ratio, and therevolution at which the scanner is moved in reverse remains constant regardless of the select-ed reproduction ratio (about 3.4 times as fast as in forward in DIRECT).The distance over which the scanner travels varies according to the length of copy paperand the selected reproduction ratio.The scanner motor drives the lens drive system in addition to the scanner system.

Scanner homeposition sensor (PSI)

Figure 3-204

Mot or dr i ver ci rcui t

DC cont r ol l er PC6

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2. Relationship between the Scanner Sensor and Signals

I II 1Referenceusedo determine the f orwardScannerhome It I travel distance.posi t i onensor SCHP I I

PSI) II IThe scanner stops traveling i nreverse n1 L I O. 1 ec.Table 3-201

3. Basic Sequence of Scanner OperationsPower switch Copy Start keyON ON

@Vj : reverse0 : detects scanner home position(3 : detects lens home posi t i onFigure 3-205

The microprocessor on the DC controller PCB controls the forward travel distance of thescanner with reference to the rising edge of the scanner home position signal. The forward trav-el distance varies depending on the length of copy paper* and the selected reproduction ratio inENLARGE: if the ratio is less than 130%, the scanner is moved forward for A4 (297 mm); if theratio is 130% or more, the scanner is moved for LTR (279 mm).*For a discussion of how the length of copy paper is checked, see p. 3-49.

_-

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4. Driving the Scanner/Lens Drive Motora. OutlineThe scanner/lens drive motor (M2) is a4-phase stepping motor. It is turned on or offand its direction and speed of rotation ischanged by controlling the output timing ofthe drive power supply SC-COMA and SC-COMB and pulse signals A, A*, 8, and B*.b. OperationThe microprocessor (QlOl) on the DCcontroller PCB receives such instructions as

_- ._The scanner/lens drive motor is a 4-

phase stepping motor, and controls thedirection and speed of scanning by changingthe frequency and the sequence of drivepulses (SC-A through SC-B*).The: motor drive voltage on/off switchingcircuit supplies power to drive the motor andremoves power to stop it. The currentswitching circuit sets the current flowing tothe motor according to the speed of rotation;the motor driver circuit is used to control the

copying modes and reproduction ratios from rated current according to the setting.the control panel circuit; and, in response, itsends drive pulses to the scanner motor(M2) through the motor drive circuit.

DC controller PCBI*

Li.i 1I

,Ii _+/i -*IIi _+Ii -i

,I

Figure 3-206

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OPERATIONS AND TIMING-

III. IMAGE FORMATION SYSTEMA. OutlineThe copiers image formation system performs the following functions:controls the pre-exposure lamp.controls the scanning lamp.

controls the primary/transfer corona current.controls the developing bias.measures the density of the original.controls side blank exposure.

Copyboard glassI ;P%( Scanning lamp I1, I\ I , Light adjustment sensor

Developingcylinder

3

Preexposu re lamp *Primary charging roller

Static Transfereliminator roller

Fluorescentlamp driverII Q501 I

High-voltagecircuit

DC controller PCB /IMicroprocessor Composite power supply PCB

Figure 3-301

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B. Sequence of Operations (image form&ion system)DIRECT, 2 Copies, ContinuousPower switch

ONCopy Start keyON

@ZZ : reverse Figure 3-302DIRECT, 2 Copies, Continuous; Copy Start key pressed immediately after power-on

,-.BZ2 : reverse Figure 3-303

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OPERATIONS AND TIMING-

\ \ C. Controlling the Pre-Exposure Lamp1. Outline

The intensity of the pre-exposure lampmust remain constant at all times duringAPVC measurement and to ensure stableimage reproduction (primary charging). Toensure stable intensity, the copier correctsvariations among individual pre-exposurelamps and fluctuations in the drive voltage.

2. OperationThe PWM reference value used to deter-mine, the intensity of the pre-exposure lamp

is stored in the CPU on the DC controllerPCB.The CPU on the DC controller PCB

detects the voltage used to drive the pre-exposure lamp and corrects the PWM refer-ence value so that the pre-exposure lampmay be driven at a specific intensity.Reference:

You must enter the PWM reference value(PREX_LP) in service mode wheneveryou have replaced the pre-exposurelamp.

+t

COPVRIGHl 0 1995CANONINC

4GiziFfG~Pre-exposure lamp (LAZ)JDC controller PCB

Figure 3-304

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D. Controlling the ScanningLamp1. Outline

Figure 3-305 shows the circuit that con-trols the scanning lamp (fluorescent lamp:FLl); the circuit has the following functions:controls pre-heating of the scanning

lamp.turns on and off the scanning lamp.controls the intensity of the scanninglamp.automatically corrects the intensity ofthe scanning lamp.

The copiers scanning lamp is a fluores-cent lamp.

_,--

When not controlled. the fluorescentlamp tends to be dark immediately after it isturned on, glowing brighter only gradually;moreover, its intensity does not stabilize forsome time if its ambient temperature is low.In consideration of these, characteristicsof the fluorescent lamp, the copier isequipped with an intensity sensor so that theoriginals may be illuminated only after theintensity of the fluorescent lamp has stabi-lized.The copier does not start copying opera-tion until the intensity of the fluorescent lamphas been checked and verified that it hasreached a specific value.

Scanning lampIntensity sensor PC

P

/ /Maintransformer(Ti Ol ) Fluorescentlamp driver

Intensity signal1 FLPRHT

DC controller PCS 1 1 Composite power supply PCBFigure 3-305

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2. Controlling the Scanning Lamp forPre-HeatingPreheating is controlled for the follow-

ing:before the scanning lamp turns on.while the scanning lamp remains on.

a. Controlling Pre-Heating before theScanning Lamp Turns OnWhen the Copy Start key is pressed, themicroprocessor (QlOl) on the DC controller

PCB sends the pre-heating voltage controlsignal (FLPRHT) to the pre-heating voltagecontrol circuit on the composite power sup-ply PCB. In response, the pre-heating volt-age control circuit supplies 4 Vrms (effectivevalue) to the filament of the scanning lamp.About 3 set later, the microprocessor onthe DC controller causes the pre-heatingvoltage control signal (FLPRHT) to go O, toend the pre-heating operation executedbefore the scanning lamp turns on.b. Controlling Pre-Heating While the

-\

Scanning Lamp Remains OnWhile the scanning lamp remains on, themicroprocessor (Q501) on the compositepower supply PCB sends the duty ratio ofthe on control signal to the microprocessor(QlOl) on the DC controller PCB. Inresponse, the microprocessor (QlOl) on theDC controller sends the pre-heating controlsignal (FLPRHT) to the pre-heating voltagecontrol circuit to execute pre-heating controlsuited to the duty ratio of the on control sig-nal for pre-heating control.

Reference:Activation of the Fluorescent LampThe fluorescent lamp repeats turning onand off in specific cycles. While it is off,voltage is applied to its filament so that itwill turn on smoothly, and the period dur-ing which such a voltage is being appliedis called pre-heating period.

. .3 Off (pre-heating)Figure 3-306

The intensity of the fluorescent lampchanges within a single cycle depending onhow long the lamp remains on:

longer on time I) higher intensityshorter on time w lower intensity

The ratio of on time within a single cycleis called duty ratio, and may be expressedby the following formula:

ON timeDuty ratio= ~ 1 cyclehigher duty ratio w increased intensitylower duty ratio I) decreased intensity

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3. Turning On and Off the ScanningLampa. OutlineWhen pre-activation pre-heating is over,

the microprocessor (QlOl) on the DC con-troller PCB instructs the microprocessor(Q501) on the composite power supply PCBto generate the scanning lamp on signal(FLAON*). At this time, the fluorescent lampdriver circuit operates to apply the output ofthe primary side of the main transformer(T102) to both ends of the scanning lamp soas to turn on the scanning lamp at a high fre-quency.

5. Controlling (automatic) the FluorescentLamp Intensity (ALVC control)The ,copier executes ALVC control in which

the ON voltage of the scanning lamp is automati-tally corrected to prevent changes in the copyimages caused by deterioration of the photosen-sitive drum.

4. Controlling the Intensity of theScanning Lampa. OutlineThe intensity of the scanning lamp is

controlled by the microprocessor (Q501) onthe composite power supply PCB.The intensity sensor checks the intensityof the scanning lamp and generates activa-tion power to suit the intensity. The micropro-

cessor, on the other hand, finds out theintensity of the scanning lamp based on theactivation power to send the scanning lampon signal (FLON*) to the on control circuit.b. Intensity Lower Than the SpecifiedValueThe microprocessor increases the dutyratio of the scanning lamp on signal (FLON*)sent to the fluorescent lamp driver. The fluo-rescent lamp driver, in turn, increases thecurrent flowing to the scanning lamp, there-by increasing the intensity of the scanninglamp.

c. Intensity Higher Than the SpecifiedValueThe microprocessor decreases the dutyratio of the scanning lamp on signal (FLON*)sent to the fluorescent lamp driver. The fluo-rescent lamp driver, in turn, decreases thecurrent flowing to the scanning lamp, there-by decreasing the intensity of the scanninglamp.

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E. Controlling the PrimaryCharging Roller Bias

1. OutlineFigure 3-307 shows the circuit that con-trols the application voltage of the primarycharging roller, and the circuit has the follow-

ing functions:turns on and off the DC bias.controls the AC bias to a constant volt-age.switches the DC bias voltage level.controls the scanning lamp ON voltagelevel.

The primary charging roller is given aDC bias so as to maintain the surface poten-tial of the photosensitive drum to a specificvalue. The DC bias is switched according towhether or not a copy image is beingformed.Reference:DC component: -9OO/-1376V

MicroprocessorCompositeower upplyPCE

DC controller PCBFigure 3-307

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2. Operationa. Turning On and Off the DC BiasWhen the Copy Start key is pressed, themicroprocessor on the DC controller PCBinstructs the microprocessor on the compos-ite power supply PCB to turn on the DC bias.The microprocessor on the compositepower supply PCB drives the main trans-former (T102).The DC bias is generated by rectifyingthe voltage from the main transformer(T102) and is sent to the primary chargingroller.

c. Switching the DC Bias Voltage LevelThe copier switches the level of the DCbias voltage according to whether or notcopy images are being formed.

The DC bias voltage is switched by themicroprocessor on the composite powersupply PCB by varying the DC bias controlsignal (PDCPWM) according to the DC biasswitching timing signal sent by the micropro-cessor on the DC controller PCB.during copying: -900 Vother: -1376 V

b. Controlling the DC Bias to a SpecificVoltageThe DC bias is controlled to a specificvoltage by the microprocessor on the com-posite power supply PCB. The microproces-

sor on the composite power supply PCBconstantly monitors the DC voltage. Themicroprocessor serves to maintain the DCbias voltage to a constant value by varyingthe DC bias control signal (PDCPWM)based on measurements of voltage taken.

Copy Stan keyo_N

/--

Figure 3-308

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OPERATIONS AND TlMlNGl

d. Controlling (automatic) the PrimaryCharging roller Bias Application VoltageLevel and the Scanning Lamp ONVoltage Level (APVC, ALVC control)Copy images wil l suffer changes if

changes occur in their static latent images,which in turn are caused by thefollowing:changes in drum sensitivity; andchanges in the degree of charge bythe primary charging roller.

These symptoms are brought about bychanges in the site environment (tempera-ture, humidity) deterioration, wear, or dirt onparts.

The copiers light area potential (VL) anddark area potential (VD) have a tendency toincrease; to compensate for this tendency,the copier corrects the primary chargingroller bias application voltage level (APVCcontrol) and the scanning lamp ON voltagelevel (ALVC control), thereby ensuring a spe-cific light area potential (VL) and dark areapotential (VD) at all times.

Study the following for an idea of howthe mechanism is activated (after power-on,during initial rotation for 1st copy):. Flow

A specific voltage of about -1.376 kV isapplied to the primary charging roller for aboutI .3 sec.

1The current value at this time is detected bythe current detection circuit, &d sent to themicroprocessor (Q501).

IThe microprocessor (Q501) in turn sends thecurrent value to the microprocessor (QIOI) onthe DC controller so that the applicationvoltage for the primary charging roller biasmay be determined based on the Ivalue.

I

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F. Controlling the Developing/Separation StaticEliminator Bias

1. OutlineFigure 3-309 shows the circuit that con-trols the developing/separation static elimi-nator bias, and the circuit has the followingfunctions:turns on and off the DC component.

turns on and off the AC component.controls the voltage level of the DCbias according to type of developingassembly.

AC powerSUPPlY

controls the voltage level of the DCbias according to the copy density set-tings.

The:developing cylinder is given AC andDC biases during copying operation.While the photosensitive drum is rotat-

ing, except during development, about -500V is applied to the developing cylinderregardless of the position of the densityadjusting lever, thereby preventing adhesionof excess toner to the surface of the photo-sensitive drum.

r ansf ormerT102 L

Transf ormer_

Microprocessor

Microprocessor

Figure 3-309

Stat i cel i mnato r

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-\ 2. Turning On and Off the DCComponentAs soon as the Copy Start key is

pressed, the microprocessor on the DC con-troller PCB sends the developing DC bias onsignal (DVDCON) to the microprocessor onthe composite power supply PCB.

In response, the microprocessor on thecomposite power supply PCB drives themain transformer (T102) to generate a DCbias for the developing cylinder.

When the developing DC bias on signal(DVDCON) from the microprocessor on theDC controller is cut, the microprocessor onthe composite power supply PCB stops the

,--, drive to the main transformer (T102), there-, \\ by cutting off the DC bias.

3. Turning the AC Component On andOffAbout 3.5 set after the Copy Start key is

pressed, the microprocessor on the DC con-troller PCB sends the developing AC bias onsignal (DVACON) to the microprocessor onthe composite power supply PCB.

The microprocessor on the compositepower supply sends the AC bias oscillationsignal (ACBIAS) to the amplifier, which inturn drives the transformer (T301) and gen-erates an AC bias for the developing cylin-der. The AC output of the transformer (T301)is transformed/rectified and then supplied tothe static eliminator.

When the developing AC bias on signal(DVACON) from the microprocessor on theDC controller PCB is cut off, the micropro-cessor on the composite power supply PCBstops the AC bias oscillation signal(ACBIAS) to cut off the AC bias supply.

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4. Controlling the Voltage Level of theDC Bias to Suit the Copy DensitySettingThe copier varies the DC bias control

signal DCBPWM) ac cording to the settingsshown below to vary the DC component volt-age, thereby c ontrolling the copy density.

setting, of the density adjusting levermanual control mode)

output of the AE sensor automaticcontrol mode)setting of density correc tion dialVR107)

type of developing assemblyDC bias: -50V to -550V

The density correction dial (VRl07) onthe DC controller PCB may be used toadjust the DC bias voltage, there by correct-ing foggy images caused by changes in thesensitivity of the photosensitive drum. Thedensity correction dia l functions when thedensity is adjusted in manual mode or duringautomatic density adjustment mode.

Figure 3-310See Figures 3-311 and 312 for changes

in the DC bias according to the setting of thedensity adjusting lever in manual mode andto the changes in the AE sensor output inautomatic mode.

Density of .0 / Test Chart Newspaper original/ 3 i.I

-100 -~

-200 --

-300

-400 --

-500 --

VDevelopingbiasDCcomponentV)

AE mode ONFigure 3-311

Copy density lever1 5 9

Manual Density adjustmentFigure 3-312

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G. DevelopingAssembly/CleaningAssembly

1. OutlineThe developing assembly is locked orreleased manually by operating the lockinglever.The primary charging roller is cleaned by

the cleaning pad operated by the cleaningsolenoid.

The developing assembly and the wastetoner feeding blade are driven by the drive ofthe main motor (Ml) transmitted by the drivegear. The waste toner scraped by the clean-ing blade is forwarded inside the drum unitby the toner feeding blade for collection,

The level of toner inside the developingassembly is monitored by the toner antenna.

TDC controller PCB

Composite power supply PCB

detection PCB

Drum unit

COPYRIGHT1995 ANONNC.

1dleaning blade Toner antennaassembly

Waste toner feeding bladeFigure 3-313

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2. Monitoring the Level of Tonera. OutlineThe level of toner inside the developingassembly is monitored by the toner levelantenna and the toner level detecting circuit.The toner level antenna is found insidethe developing assembly, and an AC bias isapplied to the developing cylinder so that thetoner level antenna and the developing cylin-der are bonded by static electricity whosesize varies according to the level of toner.

The copier uses the changes in the sizeof this static electricity to monitor the level oftoner.

b. MechanismThe toner level detecting ,PCB receivesan AC b/as equal to the AC bias applied tothe developing cylinder and an AC bias thatrepresents the level of toner by the tonerlevel antenna. The AC bias applied to thedeveloping cylinder is used as a referencesignal, and the AC bias from the toner levelantenna is used as the toner level signal.The toner level detection PCB comparesthese two types of signals and sends theresults of comparison to the DC controllerPCB as the toner level signal (TNMONI).

Developing biasReference signal

z I I I I3 Toner l evel etection PCB

Toner level antenna

DC controller PCB

ADDTONERindication

eveloping cylinderWYeveloping

Figure 3-314

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OPERATlONSANDTl M NGl

\ The DC controller PCB measures thetoner level signal (TNMONI) which arrivescontinuously at specific intervals, and takesmultiple samplings for comparison againstthe toner level value stored in advance. Ifthe results of comparison show that 90% ormore samplings are under the toner levelvalue, it will immediately flashes the ADDTONER indicator on the control panel and,at the same time, it will stop copying opera-tion upon delivery of the copy; in the case ofcontinuous copying, it stops operation aftermaking five copies after the absence oftoner has been detected.

The ADD TONER indicator turns offwhen you turn off and then on the powerswitch after the indicator has come on,1 enabling copying operation. However, theindicator will flash once again after a singlecopying operation. You can make as manyas 100 copies while the ADD TONER indica-tor is flashing by turning off and then on thepower; when 100 copies have been made,the operation will stop and remain disableduntil toner is added.

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3. Cleaning the Primary Charging Rollera. OutlineThe primary charging roller remains incontact with the photosensitive drum at alltimes; for this reason, it can collect dirt fromthe photosensitive drum, possibly causingunstable primary charging.To prevent such a problem, the copier isequipped with a cleaning mechanism for theprimary charging roller, thereby ensuring sta-ble primary charging at all times.

Cleaning is executed depending on thefollowing two conditions:9 Condition 1Copies made since power-on are count-ed (cumulative), and cleaning is executedwhen 10 or more copies have been deliv-ered. If the number of copies is less than 10,the copy count is stored when the power isturned dff, and the new count is added to itwhen the power is returned.

Condition 2Copies made since power-on are count-. OperationWhen the cleaning solenoid (SL5) turns on, ed, and icleaning is executed when the 20ththe cleaning pad is butted against the copy hag been discharged. The copy countprimary charging roller to stat-l cleaning. is cleared when the power is turned off, and

Cleaning is executed during post rotation the copy count starts newly when the powerand lasts about 1.5 set, making post is returned next time. When the count reach-rotation longer than rotation without es 20 or higher, cleaning will be executedcleaning. once again.

DC controller PCB

Photosensitive drum

Figure 3-315

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c. Cleaning Operation Timing ChartCondition 1

Jower-offm*

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4. Checking the Waste TonerWhen the photosensitive drum rotates,its drive is transmitted through the drumgear, coupling gear, and toner feeding bladedrive gear in order. The toner feeding bladeserves to forward waste toner collected bythe cleaning blade to the inside of the drumunit.The coupling gear transmits drive bykeeping two gears in contact by the work ofa spring.

When the inside of the drum unitbecomes full of waste toner, the load againstrotating1 the toner feeding blade increases.Further, when torque is imposed on thetoner feeding blade, the coupling gearbecomes disengaged, cutting the drive tothe toner feeding blade, thereby causing theflag to move away from the waste toner sen-sor (PS5). When the flag leaves the wastetoner sensor, the Replace Drum Cartridgeindicator (a) on the control panel starts toflash; in the case of a model with the drumunit replacement automatic indication func-tion, the indicator turns on.

DC controller PCB

Toner feeding blade Photosensitive drumCoupling gear

Figure 3-318

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5. Drum Unit Replacement TimeAutomatic Indication Mechanism**Only for a model with the drum unitreplacement time automatic indication func-tion.

a. OutlineThis mechanism is used to indicatewhen the drum unit must be replaced based

on the number of copies made. A PGP PCBis provided inside the drum unit to inform theDC controller when the drum unit must bereplaced.When the time for the replacement ofthe drum unit approaches, the DC controllerPCB flashes the Replace Drum Unit indica-tor on the control panel; when the time forthe replacement comes, the DC controllerturns on the Replace Drum Unit indicator onthe control panel, and indicates CC(Change Cartridge) on the copy/count indi-cator after making 100 copies.

The copy may have a drum unit whichaccommodates this function or one which isnot designed so. In addition, if you install adrum unit which does not accommodate thefunction in a copier model which is designedfor the function, copying operation will besuspended while CC (Change Cartridge) isindicated on the count/ratio indicator.

Control panel

DC controllerPCB

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b. OperationDrum Unit InstalledWhen the drum unit is installed and thepower is turned on, the DC controller readsthe following four types of data from thePGP PCB and stores them:1 serial number of drum unit (recorded onPGP PCB)2 copy count3 primary charging voltage (DC) correctionvalue4 drum sensitivity current correction valueIf #the DC controller PCB cannot find aserial number or finds a serial number whichdoes not belong to the copier, it turns on theReplace Drum Unit on the control panel andsuspends copying operation while indicatingCC on the count/ratio indicator.

I with automaticion of drum unit

Figure 3-319 PGP PCB

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During Copying OperationThe DC controller advances the copycounter on the PGP PCB each time a copyis delivered. When the count reaches29,000, it flashes the Replace Drum Unitindicator on the control panel to inform theuser that the time for replacement isapproaching.

When the count reaches 30,000, the DCcontroller turns on the Replace Drum Unit onthe control panel to inform the user that thetime for replacement is approaching. Youmay make a further 100 copies after the indi-cation has turned on, and you can check thecurrent count in service mode.When the copy count reaches 30,100,the DC controller turns on the Replace DrumUnit on the control panel and suspendscopying operation while indicating CC onthe count/ratio indicator. (In continuouscopying, the operation is suspended aftermaking all the copies.)To reset the copier when its operationhas been suspended, replace the drum unitwith a new one.

29,000 Flashing Indicates Yes Indicates that the drum You may turn off the

30,00010,100 ON count/ratio unit must soon be indication in userreplaced. mode.Indicates Yes Indicates that the copier You can check thecount/ratio will soon stop operating. current copy count inIt will stop operating user mode.after making anadditional 100 copies.ON Indicates NoCC Indicates that the drum You cannot makeunit must be replaced. copies unless youreplace the drum unit. ,-Table 3-301

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,,_~.~..,, / H. Controlling the TransferRoller Bias1. Outline

The copier uses a direct transfer methodwith a roller. For this reason, it controls thebias differently from the conventional copiersthat employ corona charging.

The transfer roller bias may be either ofthe following three types; see the descrip-tions for the function and output t iming ofeach:a. Transfer, BiasThis bias corresponds to the transferbias of a conventional copier, and is a nega-tive voltage.b. Cleaning Bias

The copier uses a direct chargingmethod, and could allow adhesion of tonerto the transfer roller moving from the photo-sensitive drum because of a jam.

To remove such toner, the copier appliesa positive voltage at a specific timing toreturn the toner from the transfer roller to thephotosensitive drum.

during initial rotation after the CopyStart key is pressed.while the scanner is moving in reverse.during last rotation.

c. Reference Bias (ATVC)Changes in the environment or deterio-ration of the transfer roller can change theresistance of the transfer roller, ultimatelyaffecting the transfer efficiency.

To suppress the changes in the copyimages caused by changes in the transferefficiency, the copier corrects the level oftransfer bias application.

The transfer ATVC bias is a bias appliedeach time the Copy Start key is pressed todetermine the correction value.

rPower switch ONrCopyStart key ON

Figure 3-320

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Figure 3-321 shows the circuit that controls the foregoing three types of bias, and the circuithas the following functions:turns on and off the transfer roller bias.controls the transfer bias to a constant voltage.corrects the voltage level of the transfer bias (ATVC),

; switches the polarity of the DC bias (cleaning).

Photosensi t i veransfer

c)rum chargingroller

Microprocessor

MicroprocessorDC control PCB

Figure 3-321

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2. Turning On and Off the TransferRoller BiasThe microprocessor on the DC controller

PCB sends the transfer bias on signal to themicroprocessor on the composite powersupply PCB. In response, the microproces-sbr on the composite power supply gener-ates the transfer bias on signal to drive thetransformer (T401), thereby supplying thetransfer charging roller with transfer bias.3. Controlling the Transfer Bias to a

Specific VoltageThe transfer bias is controlled to a spe-cific voltage by the microprocessor on thecomposite power supply PCB. The micropro-cessor on the composite power supply PCBmonitors the voltage of the transfer bias atall times. The microprocessor on the com-posite power supply PCB sends the transferbias control signal through the pulse/DCconversion circuit according to the detectedvoltage to the voltage control circuit to main-tain the transfer bias to a specific voltage.4. Correcting the Voltage Level of the

Transfer BiasThe copier corrects the voltage level ofthe transfer bias in any of the following two

ways: before starting copying (ATVC)after starting copying

a. Before Starting Copying (ATVC)To correct changes in the transfer effi-ciency caused by changes in the environ-ment or deterioration of the transfer roller,

the copier automatically corrects the applica-tion voltage level of the transfer bias.During initial rotation after the Copy Startkey is pressed, the copier feeds a specificcurrent to the transfer roller. The current

detection circuit on the composite powersupply PCB sends measurements of the cur-rent to the microprocessor in the form of thecurrent detection signal. The microprocessordetermines the voltage to be applied to thetransfer roller based on such data.This control is executed once during ini-tial rotation after a press on the Copy Startkey.

OPERATI ONSANDTI M NGI I

b. After Starting CopyingThe copier automatically corrects theapplication voltage during copying operation

to compensate for the changes in the trans-fer efficiency caused by different types ofcopy paper.The current detection circuit detects thecurrent flowing through the transfer chargingroller and sends the data to the microproces-sor on the composite power supply PCB.Using the data, the microprocessor deter-mines the voltage to be applied to the trans-fer charging roller and controls the DC biasvoltage by generating the transfer DC biascontrol signal so that the voltage will be opti-mum.5. Switching the Polarity of the, DC Bias

(cleaning)The microprocessor on the DC controllerPCB sends the transfer bias switching timing

signal to the microprocessor on the compos-ite power supply PCB.The microprocessor on the compositepower supply PCB, on the other hand, turnsoff the transfer DC bias on signal and, at thesame time, sends the transfer positive DCbias on signal to the positive bias control cir-cuit. The voltage from the positive bias con-trol circuit is sent to the transfer chargingroller through the transformer/rectifier circ&t.

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I. Measuring the Density ofthe Original (AE)

1. OutlineThe copier is equipped with an automat-ic density adjustment (AE) mechanism whichadjusts the DC component of the developingbias. As long as the original has an even

overall density, the AE mechanism ensuresthe generation of copies without fogging byvarying the DC component of the developingbias to suit the density of the original.

The copiers AE mechanism does notexecute an AE scan; rather, it measures thedensity pf the original during initial rotation atthe scanner home position; for this reason,the copying speed remains the same in bothAE and non-AE modes,

Figure 3-322 shows the circuit that con-trols the measurement of the density of origi-nals.

AE sensor

-

I+

Copyboard glass

Amplifier circuitDC controller PCB

developing DC biasDeveloping DC bias)n signal (DVDCON)

Composite power supply PCE

Figure 3-322

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2. OperationTo measure the density of an original, the scanning lamp is turned on at a specific intensityto expose the original during initial rotation with the scanner at the home position.The light reflected by the area shown in Figure 3-323 is checked by the AE sensor (photodi-

ode), whose output is amplified and sent to the microprocessor on the DC controller PCB as theAE signal.The microprocessor on the DC controller PCB checks the AE signal four times, and aver-ages the measurements to compute the developing DC bias which best matches the averageddensity of the original; it then sends the developing DC bias signal and the developing DC biason signal to the microprocessor on the composite power supply PCB.The microprocessor on the composite power supply PCB generates the developing DCbias control signal (DCBPWM) based on the value of the DC bias.

' ~: AE sensor reading areaFigure 3-323

,-, 3. Basic Sequent; of Operations (AE measurement)

Copy Start key

Figure 3-324

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4. AE Adjustment (VR102, VR103)Make the following adjustments whenev-er you have replaced the scanning lamp orthe intensity/AE sensor PCB:Preparing for Adjustment

1)2)

Obtain a newspaper whose print is aseven as possible; avoid one with pho-tos or with large headings.Make sure you have adjusted theintensity of the scanning lamp.

Turn on the copier.Short the two jumper wires (JP3, JP4)on the DC controller PCB using a screw-driver.

F appears on the ratio/count indicator.JP4

Screwdriver

Figure 3-325Stop shorting the jumper wires; pressthe +/- key so that 40 appears on theratio/count indicater; than, press thestart key.The scanning lamp should turn on, andthemain motor (Ml) should rotate.

Turn VR103 on the DC controller PCBfully clockwise.

Figure 3-326Place a newspaper on the copyboard,and close the copyboard cover.Turn VR102 so that the reading in thedisplay is between b2 and bc.

Figure 3-327Remove the newspaper from the copy-board, and place a stack of five sheetsof copy paper on the copyboard glassinstead; then, close the copyboardcover.

_,-..

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,-,

8) Turn VR103 on the DC controller PCBso that the reading in the display of thecontrol panel is between 53 and 5d.

Figure 3-3289) Make one copy, and check if it is free of

fogging but the print is dark enough.If fogging is noted or the charac tersare too light, repeat, the steps startingwith step 1) once aga in.If the problem cannot be correctedafter going through the steps onceagain, use the density correc tion dialVR107).

WI07

Figure 3-329

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J. Controlling the Side BlankExposure1. Outline

The copier is equipped with a side blankexposure lamp at the front and the rear toprevent adhesion of toner to the drum whenreduced copies are made.

2. OperationThe side blank exposure lamp movesbased on the travel distance of the lens asmeasured by the lens travel detecting shaft

for reduced copies for blanking out the non-image areas.

Rear side blank exposure lampLens travel detecting shaftReflecting plate /

Front side blank exposure lamp

Reflecting plate(front)

Figure 3-330

A + B B + A

Photosensitive drumL Non-image area (REDUCE) i

A : position of the side blank exposure lamp at time of DIRECT/ENLARGE., B : position of the side blank exposure lamp at time of REDUCE

Figure 3-331

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, .-\_1 IV. PICK-UP/FEEDINGSYSTEMA. Outline

The comer uses center reference feed- The copier is equipped with two sensorsing. in which copy paper is moved while cen-te;ed along the-pick:up/feeding path; thepick-up system consists of a single-cassettepath or a multifeeder path.

Cow paper from the cassette or the

to monitor the movement of copy paper.

:f&t?o, ; f&& f , ,, I ,I: ,:#+@&PS3 Delivery paper sensor

\

multifeeder is controlled by the registration I 1roller so that it matches the leading edge of Q751 Pre-registrationollerpaper ensorthe image on the photosensitive drum; it isthen moved to the transfer, separation, feed- Table 3-401ing, and fixing assemblies before it is dis-charged to the copy tray.

DC contr oller PCB

gg Mul$,Photosensitive z d pick,drum ii : /

nCassette

/ LCassetter- -rroller

Holdingplate

Figure 3-401

,r.I

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B. Controlling the Pick-UpRoller1. Outline

The copier has two pick-up rollers;namely, the cassette pick-up roller and themultifeeder pick-up roller. The drive to therollers is switched by a gear u&that shiftsthe drive path; for this reason, the drive istransmitted to only one of the two rollers at atime.

2. Controlling the Cassette Pick-UpRollerThe cassette pick-up roller is controlled

by the spring clutch,control ring, and pick-upsolenoid (SLl).When the solenoid turns on, the pawl

moves away from the control ring, therebyallowing the drive of the main motor (Ml) tobe transmitted to the pick-up roller.When the pick-up roller starts to rotate,copy paper is picked up and sent as far asthe registration roller. The registration roller,in turn, serves to control the copy paper sothat it matches the leading edge of theimage on the photosensitive drum.

DC controller PC6

Cassette pick-up roller

Figure 3-402

3 - 46 COPYRI GHT 1995 ANONI NC. CANON NP6012/ NP60i 2F/ NP6212EV. 1 EPT. 1995Rl NTEDI NJ APAN(l MPRI MkAUJ APON)

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3. Controlling the Multifeeder Pick-UpI RollerThe multifeeder pick-up roller is con-trolled by the spring clutch, control ring, pick-up solenoid (SLl), gear unit, lift arm, andmultifeeder pick-up solenoid (SL4).When the multifeeder pick-up solenoid(SL4) turns on, the drive of the main motor(Ml) is transmitted to the cam gear. Whenthe cam gear starts to rotate, the lifter whichisl in contact with the cam gear starts to lifttiie gear unit and, at the same tirrie, lowersthe paper guide plate. The cam gear isdesigned to stop at a specific location.

When the solenoid (SLl) turns on whilethe mechanism is in this spatial relationship,the pawl moves away from the control ring,allowing the drive of the main motor (Ml) tobe transmitted to the multifeeder pick-uproller.

When the multifeeder pick-up rollerrotates, copy paper is picked up and sent asfar as the registration roller. The registrationroller in turn controls the copy paper so thatits leading edge matches the leading edge ofthe image on the photosensitive drum.

_- _-\ I 1DC controller PCBI

Paper gui de pl ateFigure 3-403

COPYRI GHT 1995 ANONI NC. CANON NP60121NP6012FI NP6212EV. 1 EPT. 1995Rl NTEOI NJ APAN( I MPRI M~AUJ APON) 3 - 47

8/13/2019 NP 6012, 6212 SM

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C. Controlling the FeedingMechanism1. Controlling the Registration Roller

The registration roller is controlled by thespring clutch, control ring, registration sen-sor, and registration solenoid (SL2).

IWhen the microprocessor on the DCcontroll& PC6 receives the bre-registration

paper detection signal from the pre-registra-tion paper sensor (Q751), it turns on the reg-istration solenoid at a specific timing. Whenthe registration solenoid turns on, the paw1