Specifications

EE
LCD Flat Panel Interface
Page 4
substrate, while Y grid conductors connect to the upper substrate.
Applying an electrical signal to both conductors at the location of a
pixel causes that pixel to be visible from the front of the display.
Driving the Flat Panel Display
Several methods exist to drive the flat panel display. One method involves
use of a single scan in one pass of the display pixels to provide display drive.
A faster method which provides better response and display contrast
involves splitting the screen into two equal parts (upper and lower) and
scanning each separately, thus reducing the time required to complete each
scan cycle. This method is known as dual scanning.
Pixel information in monochrome displays shifts into the matrix at each
controller clock pulse. This information can be shifted into the matrix by the
controller at up to eight pixels per clock pulse.
In color displays, bits of color data can be shifted into the display matrix at a
rate of up to six bits per color per pixel during one clock pulse. New
technology promises to increase this rate to eight bits per color per pixel.
During dual scans of the display, the controller can deliver four data bits to
the upper area and four data bits to the lower area simultaneously.
LCD Contrast/Backlight Control
Flat Panel Contrast and Backlight Control
Although the EPC-30 does not support flat panel display contrast or
backlight control, these functions are supported by the Cirrus Logic
CL-GD6245 display driver IC. You must use an external power
supply which provides the correct control voltages to enable these
functions. Refer to documentation from the flat panel manufacturer
for additional information.
LCD Contrast Control
An adjustable power supply and associated circuitry are necessary
to allow control of the contrast setting of an LCD flat panel. This
device should provide two variable voltages, positive and negative,
to the flat panel at the appropriate cable pins. Varying these
voltages (positive and negative values changing together) causes
contrast change in the flat panel.
LCD Backlight Control