Sanyo TI5110LCD Training Manual page 18

System of LCD Display
5-5 Active Matrix System
In the active matrix system, a switch element is attached for every pixel at the intersection of the X and Y-
electrodes of a passive matrix system. Each pixel is now controlled by the switch element (active ele-
ment). Since the switch for each pixel is turned On and Off independently, the response speed is
increased. Thin Film Transistor (TFT) is used for the switch element and is attached on the glass board.
The LCD display using this TFT is called "TFT LCD display".
The upper electrode for the whole pattern is formed on the upper glass plate and is called the "Common
Electrode". A pixel electrode (pixel pattern), TFT (switch element) which drives a pixel electrode, and X
electrode for gate input and Y electrode for source input of TFT are formed on the lower glass plate. In
this structure, the electric field is generated in the area between the pixel electrode and the common
electrode, and the LCD shutter for 1 pixel is operated.
When an electric signal (voltage) is supplied to the Y and X electrode of TFT, TFT is turned On, and the
liquid crystal molecules are operated as a light switch. Refer to Fig. 17 (Address X1 and Y0).
Glass Plate
(Upper)
Liquid
Crystal
Layer
Glass Plate
(Lower)
Y Electrode
Liquid
Y
0
Crystal
Pixel Electrode
TFT
Y Electrode
Equivalent Circuit
COMMON
COMMON
Electrode
Electrode
Pixel
Y
1
Electrode
X1
X1
X Electrode
X2
Gate
Source
By TFT, the shutter of a pixel at the
address (X1, Y0) is turned On or Off.
COMMON
Electrode
Pixel Electrode
(Pixel Pattern)
X Electrode
TFT
(Switch Element)
Equivalent Circuit
(TFT)
COMMON COMMON
Liquid
Crystal
Drain
X1
Gate
Source
TFT
Y
0
-18-
Training Manual Principle of LCD
Fig. 16
Structure of Active
Matrix System
(Switch)
Drain
Switch
Y
0
(On / Off)
Fig. 17
Equivalent Circuit of
Active Matrix System