The Current Injection Method for AC Plasma Display

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IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 51, NO. 3, JUNE 2004 615

The Current Injection Method for AC Plasma DisplayPanel (PDP) Sustainer

Jun-Young Lee, Jin-Sung Kim, Nam-Sung Jung, and Bo-Hyung Cho, Senior Member, IEEE

AbstractA new concept of energy recovery for a plasmadisplay panel (PDP) is proposed. Different from conventional

LC resonant sustaining drivers, the current built up beforeinverting the polarity of the panel electrodes is utilized to changethe panel polarity together with energy previously charged inpanel capacitance. This operation provides zero-voltage switchingof switches and reduction of electromagnetic interference byrejecting the surge current when the sustain switches are turnedon. The buildup current helps to reduce the transition time of thepanel polarity and may produce more stable light waveforms. Thismethod is suitable for a PDP sustaining driver requiring stablelight emission characteristic while it maintains low circuit loss likethe series-resonant-type energy recovery circuit which is knownto be a very effective method.

Index TermsEnergy recovery, plasma display panel (PDP),resonance.

I. INTRODUCTION

T HE plasma display panel (PDP) has an advantages overother flat panel displays including wide view angle, largescreen, high brightness, and thinness. Thanks to the attractive

merits, the PDP is expected to be a promising candidate in the

display market [1]. Fig. 1 shows the simplified PDP structure

with three electrodes. It consists of two glass plates with

chemically stable rare gases filled between them. The scanning

and sustaining electrodes are built on the front glass, which is

coated with a dielectric layer and the addressing electrode is on

the rear glass. A desired color light can be obtained by exciting

the phosphors on the addressing electrode to emit visible light

with the ultraviolet photons generated by gas discharge [2].

The operation of a PDP is divided into three periods of setup,

addressing, and sustaining periods. During the setup period, all

of the PDP cells are erased and prepared to carry out addressing

by forming adequate wall charges. After that, selective write

discharges to form an image are ignited by applying data and

scanning pulses to the addressing and scanning electrodes,

respectively [3]. Since addressing discharge itself emits an

insufficient visible light, high-voltage ac square pulses are con-

tinuously applied between sustaining and scanning electrodesfor strong light emission of selective cells. The high-voltage

pulses can be generated using a simple full-bridge driver, as

Manuscript received April 16, 2002; revised July 18, 2003. Abstract pub-lished on the Internet January 14, 2004.

J.-Y. Lee, J.-S. Kim, and N.-S. Jung are with the PDP Circuit Development1 Team, PDP Division, Samsung SDI Company Ltd., Chonan City 330-300,Korea (e-mail: [email protected]; [email protected]).

B.-H. Cho is with the Power Electronics Laboratory, School of Electrical En-gineering, Seoul National University, Seoul 151-742, Korea (e-mail: [email protected]).

Digital Object Identifier 10.1109/TIE.2004.825359

Fig. 1. Simplified PDP structure with three electrodes.

Fig. 2. Basic full-bridge sustaining driver and its sustain waveform.

shown in Fig. 2, and most of the PDP power is consumed during

this sustaining period. Since a dielectric layer is encrusted on

sustaining and scanning electrodes, capacitance between two

electrodes exits inherently. When a sustaining pulse is applied

to electrodes, an amount of energy is dissipated in

switches and parasitic resistances of wire during charging and

discharging transients, where is panel capacitance and is

sustain voltage. If an average frequency of sustaining pulse is ,

then the total dissipated power is [4]. Without propermethods to recover the energy, a large amount of surge current

causes electromagnetic interference (EMI) and the heating

problem of switching devices. To solve the problems, Webber

et al. suggest an energy recovery circuit (ERC) using the series

LC resonant concept [5]. It features high efficiency and good

circuit flexibility to cope with various driving methods, which

leads many PDP makers such as Samsung, LG, Matsushita, and

FHP to adopt this circuit. Ohba et al. have reduced this circuit

supporting parallel LCresonance, adopted by NEC [4]. Several

researchers have studied various circuit types to improve

0278-0046/04$20.00 2004 IEEE


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616 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 51, NO. 3, JUNE 2004

Fig. 3. LCresonant-type PDP driving circuit. (a) Series resonant type. (b) Parallel resonant type.

Fig. 4. Equivalent circuits during LCresonance and the panel voltage waveforms. (a) Series resonant type. (b) Parallel resonant type.

performance and reduce circuit volumes [4], [7]. However, due

to the considerable circulating current, efficiency and flexibility

are not good compared with conventional PDP drivers, which

makes it difficult to produce them on a commercial scale.

In this paper, new concept of energy recovery using current

injection method (CIM) is proposed. Before inverting the po-

larity of the panel electrodes, the inductor current is built up

and it is used to invert the panel polarity together with energy

previously charged in panel capacitance. This operation helps

to achieve the zero-voltage switching of switches and reduce

the EMI by rejecting the surge current. In addition, it helps to

reduce the transition time of the panel polarity, which may pro-

duce more stable light waveforms. By reducing the circulating

current, good circuit efficiency can be obtained in the prototype

driver for a 42-in PDP.

II. PRIOR APPROACHES

Fig. 3 shows the prior approaches suggested by Webber and

Ohba using series or parallel LC resonance. Their equivalentcircuits during the LC resonant period and the panel voltage

waveforms are shown in Fig. 4. The sustain voltages go up

or ramp down to some voltage level in a resonant manner

and sustain switches are turned on to hold a sustain voltage.

At that moment, a large surge current occurs. In this figure,

means the parasitic resistance including on-resistances of

switches and means the diode forward drop. Based on

this figure, the panel voltage can be obtained as follows:

series resonant type

(1)


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LEE et al.: CURRENT INJECTION METHOD FOR AC PLASMA PANEL DISPLAY (PDP) SUSTAINER 617

Fig. 5. PDP driver circuit to adopt the new method.

parallel resonant type

(2)

where and . If

and can be ignored, (1) and (2) are simply

rewritten as


(3)


(4)

where . The peak values of the two equations

occur at and can be obtained as follows:


(5)


(6)

It says that increase of the parasitic resistance causes therecovery efficiency to be degraded. Naturally, it is necessary

to reduce the parasitic resistance by designing the circuit

board optimally as well as choosing switching devices with

small on-resistance and low on-drop voltage to minimize the

hard-switching stress and improve the recovery performance.

However, since it is impossible to get rid of the parasitic

components completely, EMI and switching stress caused by

the surge current are inevitable. It shows the limitations of the

simple LC resonant method. On the other hand, reduction of

the inductor value produces similar results and, thus, using a

too small value of is not desirable in the aspects of driving

loss and EMI.

III. MODE ANALYSIS

Fig. 5 is the PDP driver circuit to adopt the CIM. This cir-cuit is similar to a series resonant type circuit except that the

energy storage capacitors are connected in series betweenand ground. However, the operation is different from the simpleLC resonant method. Fig. 6 shows the key waveforms of theproposed method, divided by eight modes, and their operationalmode diagrams are as shown in Fig. 7. It is assumed that be-fore the start of mode 1, the switches and are on and

. In addition, recovery capacitors of , , ,and are charged to half of the sustain voltage. Because theoperation of the two half cycles is symmetric, mode analysis isperformed about the first half cycle.

A. Mode 1

Referring to Fig. 7, once the switch of the Y electrode is

turnedon, there forms a current pathincluding , , , andinsequence.On the other hand, whentheswitch oftheX elec-trode is turned on, there forms a current path including , ,

, and in sequence.Accordingly, and flowingtoand linearly increase with the slope of to store themagnetic energy in the inductors. The currents are expressed as

(7)

B. Mode 2

When and are turned off, the currents built up duringmode 1 flow through , , , , , and in sequence.A resonant current caused by the panel capacitance flows and

the terminal voltage of the panel capacitor is inverted inpolarity from to . That is, the Y electrode voltageat the Y electrode rises from ground to the sustain voltageand the X electrode voltage at the X electrode falls from thesustain voltage to ground. In this mode, the equivalent circuitis Fig. 8. From this circuit , , and are written as

(8)

(9)

where and .


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Fig. 7. Operational mode diagrams.

Fig. 8. Equivalent circuit for the proposed method during mode 2.

method to predict the circuit consumption and investigate the

trend of power consumption according to circuit parameters.Furthermore, they are used for suggesting a design guideline.

Based on the mode analysis and Fig. 9, the power dissipated in

diodes and switches averaged over a switching period can be

written as follows:

(13)

Fig. 9. Current waveforms of energy recovery and sustain circuits.

(14)


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Fig. 10. Calculated power losses under T and L variations at V = 1 6 5 V when panel discharge is removed.

(15)

where and are on-resistances of energy re-

covery and sustain MOSFETs, respectively. In addition, since

the clamping currents through , , , and cannot

be ignored, the power loss caused by this current expressed as

(16) should be considered

(16)

where is the output capacitance of the energy recovery

switches and

(17)

Since the power dissipation caused by a large amount of

surge current of sustain switches can be removed by using

this method, most of the circuit losses are conduction loss.

Different from simple LC resonant methods, it has some

circulating current due to the current built up before inverting

the panel polarity and this current may contribute to degrade

the circuit efficiency. Using (13)(17), the power losses under

the buildup time and inductor value variations can be calcu-

lated with parameters used in prototype PDP driver, which is

Fig. 11. 42-in test PDP set for the proposed method.

TABLE I

KEY COMPONENTS FOR PROTOTYPE DRIVER

shown in Fig. 10. The power loss goes up as the buildup times

and inductor values are varied so that the circulating current


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Fig. 12. Currents drawn from the sustain power supply at V = 1 6 5 V with buildup time and resonant inductor variations.

Fig. 13. Sustain voltage and inductor current waveforms atL = 0 : 4 2

H, T = 1 5 0

ns, andV = 1 6 5

V. (a) Y electrode. (b) X electrode.

increases. Therefore, it is not desirable to choose an excessively

large buildup time or small inductor value.

V. DESIGN

To validate the proposed method, a prototype PDP driver cir-

cuit has been designed for 42-in PDP panels with the following

specifications:

sustain voltage: V;

switching frequency: kHz;

transition time: ns;

panel capacitance: about nF;

scan method: single scan (scan line lines,

address line lines).

The test set is as shown in Fig. 11. The PDP driver is divided into

two board of X and Y boards to reduce the parasitic impedance

between board outputs and panel electrodes. Scan boards are

located at between Y board and Y electrode. The logic board

to generate switching signals and perform various algorithms

is at the right side of Y board. Supplying power is carried out

by switched-mode power supply (SMPS) at the left side of X

board. Table I shows the circuit components of sustain and en-

ergy recovery circuits. Fig. 12 is the interaction plot that shows


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Fig. 14. Sustain voltage and light waveforms with panel discharge at V = 1 6 5 V. (a) CIM. (b) Series resonant method.

Fig. 15. Power consumption of PDP set with and without panel discharge at V = 1 6 5 V.

the currents supplied by the sustain power supply with buildup

time and resonant inductor variations when the panel dis-charge is removed to observe the circuit loss itself. The power

loss is measured under five test image patterns such as full white,

full red, full green, full blue, and nine white square images.

The full white image pattern has the largest discharge current

of about 150 A in the 42-in panel, but its sustain pulse number

is smallest among other patterns. It is about 400 pulses. Mean-

while, the nine white square pattern has the smallest discharge

current, but about 2000 pulses are applied to the panel to obtain

a peak brightness. The interaction plot shows that when and

are selected as 0.42 H and 150 ns, the circuit power loss

can be minimized. Using the selected values, the transition time

can be obtained as 500 ns from (12).

VI. EXPERIMENTAL RESULTS

Fig. 13 shows the sustain voltage and inductor current wave-forms. Before the panel polarity is inverted, the inductor cur-

rents are built up to about 35 A and they are recovered to the ca-

pacitors after changing the panelpolarity. The clamping currents

caused by parasitic capacitance of energy recovery switches

are also shown in this figure. The measured waveforms in box

shows that soft switching can be accomplished. Fig. 14 is the

voltage waveforms of the panel electrodes accompanied by light

waveforms when panel discharge for emitting light happens. As

can be seen in this figure, the start voltage of the panel discharge

is higher than series resonant type and more stable light wave-

form can be obtained especially at the nine white square image

pattern. Fig. 15 is the power loss comparison plot. It shows that


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Fig. 16. EMI radiation comparisons between two methods. (a) CIM. (b) Series resonant method.

the power loss is similar to that of series resonant type energy

recovery circuit. It is desirable characteristic since this type has

been known to be very effective method. The test result of EMIradiation at full white image pattern is as shown in Fig. 16.

The newly developed method shows a lower EMI level at the

100 MHz200-MHz band due to the reduction of surge currentwhen the sustain switches conduct.

VII. CONCLUSION

In this paper, a new concept of energy recovery using cur-

rent injection method (CIM) was proposed and verified with a

42 in PDP panel. Experimental results show that with the help

of the buildup inductor current just prior to inverting the panel

polarity, zero-voltage switching of switches can be achieved re-

gardless of theparasitic resistance and it reduces the EMIcausedby the surge current. The prototype driver circuit improves the

light waveform uniformity and sustain voltage waveform while

it has a desirable characteristic that power loss does not fall be-

hind that of the series resonant method. Therefore, the proposed

sustainer is expected to be suitable for a PDP sustaining driver

requiring stable discharge characteristics. This concept can be

applied to a parallel resonant driver and address recovery cir-

cuit as well as a series resonant driver.

REFERENCES

[1] A. Sobel, Plasma displays, IEEE Trans. Plasma Sci., vol. 19, pp.10321047, Dec. 1991.

[2] H. Hirakawa, T. Katayama, S. Juroki, H. Nakahara, T. Nanto, K.Yoshikawa, A. Otsuka, and M. Wakitani, Cell structure and drivingmethod of a 25-in (64 cm) diagonal high-resolution color ac plasmadisplay, in Proc. Symp. Society for Information Display, vol. 29, 1998,pp. 279282.

[3] L. F. Webber, Plasma display device challenges, in Proc. Asia Dis-play98, 1998, pp. 1527.

[4] S. Y. Lin, C. L. Chen, and K. Lee, Novel regenerative sustain driver forplasma display panel, in Proc. IEEE PESC98, Fukuoka, Japan, 1998,pp. 17391743.

[5] L. F. Webber and K. W. Warren, Power efficient sustain drivers andaddress drivers for plasma panel, U.S. Patent 4 866 349, Sept. 1989.

[6] M. Ohba and Y. Sano, Energy recovery driver for a dot matrix ACplasma panel with a parallel resonant circuit allowing power reduction,U.S. Patent 5 670974, Sept. 1997.

[7] H. B. Hsu, C. L. Chen, S. Y. Lin, and K. M. Lee, Representative powerelectronics driver for plasma panel in sustain mode operation, IEEETrans. Ind. Electron., vol. 47, pp. 11181125, Oct. 2000.

Jun-Young Lee was born in Seoul, Korea, in 1970.He received the B.S. degree from Korea University,Seoul, Korea, in 1993, and the M.S. and Ph.D.degrees from Korea Advanced Institute of Scienceand Technology (KAIST), Taejon, Korea, in 1996and 2001, respectively, all in electrical engineering.

He is currently a Manager with the PDP Divi-sion, Samsung SDI Company Ltd., Chonan City,Korea. His research interests are in the area ofpower electronics, including ac/dc PFC convertertopology design, converter modeling, soft-switching

techniques, display driving circuits, PDP driving systems, and address energyrecovery technology.

Dr. Lee is a Member of the Korea Institute of Electrical Engineering (KIEE)and Korea Institute of Power Electronics (KIPE).


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Jin-Sung Kim was born in Seoul, Korea, in 1972.He received the B.S. and M.S. degrees from SeoulNational University, Seoul, Korea, in 1996 and 1998,respectively.

He is currently a Manager with the PDP Division,Samsung SDI Company Ltd., Chonan City, Korea, incharge of driver circuit development for PDPs. Hisresearch interests include display driving circuits,PDP driving methods, and address energy recovery

circuits.

Nam-Sung Jung was born in Seoul, Korea, in1962. He received the B.S. degree from HanyangUniversity, Seoul, Korea, in 1985, and the M.S. andPh.D. degrees from Korea Advanced Institute ofScience and Technology (KAIST), Taejon, Korea,in 1990 and 1999, respectively, all in electricalengineering.

He is currently a General Manager with the PDPDivision, Samsung SDI Company Ltd., Chonan City,Korea. His research interests are in the area of powerelectronics, includinginverter and converter topology

design, modeling, and soft-switching techniques in PDPs.Dr. Jung is a Member of the Korean Information Display Society (KIDS) and

Korea Institute of Power Electronics (KIPE).

Bo-Hyung Cho (M89SM95) received the B.S.and M.E. degrees from the California Institute ofTechnology, Pasadena, and the Ph.D. degree fromVirginia Polytechnic Institute and State Univer-sity (Virginia Tech), Blacksburg, all in electricalengineering.

Prior to his research at Virginia Tech, he workedfor two years as a Member of Technical Staff, PowerConversion Electronics Department, TRW Defense

and Space System Group, where he was involvedin the design and analysis of spacecraft power pro-cessing equipment. From 1982 to 1995, he was a Professor in the Departmentof Electrical Engineering, Virginia Tech. In 1995, he joined the School ofElectrical Engineering, Seoul National University, Seoul, Korea, where he iscurrently a Professor. His main research interests include power electronics,modeling, analysis, and control of spacecraft power processing equipment,power systems for space stations and space platforms, and distributed powersystems.

Dr. Cho received the 1989 Presidential Young Investigator Award from theNational Science Foundation. He is a member of Tau Beta Pi.

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The Current Injection Method for AC Plasma Display

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