UNIT IV
STORAGE AND DISPLAY
DEVICES
U.NAGABALAN ., AP / EEE
M.VENKATESWARAN., AP / EEE
R.VANITHA., AP / EEE
RMD ENGINEERING COLLEGE
TOPICS
• MAGNETIC DISK AND TAPE – RECORDERS
• DIGITAL PLOTTERS
• PRINTERS
• CRT DISPLAY
• DIGITAL CRO
• LED
• LCD
• DOT MATRIX DISPLAY
• DATA LOGGERS
2
RECORDERS
•A recorder is a measuring instrument which records time varying quantity, even
after the quantity or variable to be measured has stopped.
•The electrical quantities such as voltage & current are measured directly.
•The non- electrical quantities are recorded using indirect methods.
•The non- electrical quantities are first converted to their equivalent voltages or
currents, using various transducers.
Electronic recorders may be classified as:
1.Analog recorders
2.Digital recorders
Analog recorders dealing with analog systems can be classified as
•Graphic recorders
•Oscillographic recorders
•Magnetic Tape recorders
Digital recorders dealing with digital output can be classified as
•Incremental digital recorders
•Synchronous digital recorders
MAGNETIC TAPE RECORDER
Basic Components of Tape Recorder
1.Recording Head
2.Magnetic Tape
3.Reproducing Head
4.Tape Transport Mechanism
5.Conditioning Devices
MAGNETIC TAPE RECORDER
TAPE TRANSPORT MECHANISM
PRINTERSIMPACT PRINTERS press formed character faces against an inked ribbon onto the paper.
▪ line printer
▪ dot matrix printer.
NON IMPACT PRINTER and plotters use laser techniques, inkjet sprays, xerographic processes, electrostatic methods and e1ectrothermal methods to get images onto the paper.
• A ink-jet printer
• laser printer
DRUM PRINTERS
DOT MATRIX PRINTERS
LASER PRINTER
DIGITAL PLOTTERS
CRT DISPLAY
DIGITAL CRO
What is an LED?
• Light-emitting diode
• Semiconductor
• Has polarity
LED: How It Works
• When current flows across a diode
• Negative electrons move one way and positive holes move the other way
LED: How It Works
• The wholes exist at a lower energy level than the free electrons
• Therefore when a free electrons falls it losses energy
LED: How It Works
• This energy is emitted in a form of a photon, which causes light
• The color of the light is determined by the fall of the electron and hence energy level of the photon
Inside a Light Emitting Diode
1. Transparent Plastic Case
2. Terminal Pins
3. Diode
Kinds of LEDs
How to Connect a LED:
• Requires 1.5~2.5V and 10 mA
• To prevent overloading, use resistor 470 Ω
https://www.elprocus.com/light-emitting-diode-led-working-application/
LIQUID CRYSTAL DISPLAY (LCD)