8

Liquid Crystal Display Modules

Transflective LCD

Transflector bonded to the rear polarizer re-

flects light

from the front as well as enabling

lights to pass through the back. Used with

backlight off in bright light and with it on in low

light to reduce power consumption.

Transmissive LCD

Without reflector or transflector bonded to the

rear

polarizer. Backlight required. Most com-

mon is transmissive negative image.

EL (Electroluminescent Lamp) backlight

LED (Light Emitting Diode) backlight

Features: EL: thin, inverter required

LED: long service life, low voltage

driving, no inverter required

REFLECTIVE/TRANSFLECTIVE/TRANSMISSIVE LCD

POSITIVE/NEGATIVE MODE

TN TYPE/STN TYPE/FSTN TYPE

STRUCTURE AND FEATURE OF LCD MODULE WITH BACKLIGHT

POWER SUPPLY

CFL (Cold Cathode Fluorescent Lamp) backlight

Features: high brightness, long service life, inverter required

Reflective LCD

Reflector bonded to the rear polarizer

reflects the incoming ambient light. Low power

consumption because no backlight is required.

Edge backlight type

(G2446,G242C)

(G321D,G649D)

Backlight type

Frame

LCD

CFL

PCB

Light guide

PCB

PCB

CFL

LCD

LCD

PCB

EL or LED

Frame

Frame

LCD module

VR

GND

+ 5V

GND

+ 5V

*

VR

GND

+ 5V

- 2V (min)

VR

GND

+ 5V

GND

+ 5V

Character modules (single power supply)

LCD module

LCD module

LCD module

LCD module

Negative

voltage

Negative

voltage

G2446,G242C (Built-in DC-DC conv.)

G321D, G324E and G649D

Character Modules(Dual power supply)

Y1206 and G1226

*

Negative voltage should be variable for

contrast adjustment.

Note 1:Contrast can be adjusted by VR.

Note 2:For module with backlight, power supply

for backlight is necessary.

light

source

reflected

light

reflector

transmitted

light

transflector

light

source

reflected light

light source

(backlight)

light source

(backlight)

transmitted

light

Positive

type

Negative

type

Negative type

(inverse image)

(when data is inverted)

TN

STN

FSTN

(Background/dot color)

Gray/Black

White/Black

Yellowgreen/Dark blue

Gray/Dark blue

White/Blue

TN( Twisted Nematic) type is most conventional and economical. It is used for static drive LCD and

low-duty drive LCD ( watch,calculator, etc.)

STN (Super Twisted Nematic) type has a higher twist angle, and thus provides clear visibility

and wider viewing angle. This is suitable especially for high-duty drive LCD.

FSTN (Film Super Twisted Nematic) type utilizes RCF (Retardation Control Film) to remove

the coloring of STN LCD. Thus FSTN type provides easy-to-read black-and-white display.