Casio QV-10A Service Manual & Parts List page 14

TFT-LCD
Gate Frame period
pulse
t1
Vy
Y1
GND
Y2
Y3
Va
X1
Vb
t1 t2 t3
Picture
element
A
Each picture element electrode is controlled by a transistor. To the gate electrodes, the gate pulse is applied
timesharing. VCOM voltage is applied to the common electrodes.
The above figure shows the operation of TFT-LCD. If the gate pulse is not applied to the gate electrodes,
the transistors do not operate even when the potential difference is given between the common electrodes
and source electrodes, and no effect is given to the liquid crystal. If the gate pulse is applied to Y1, the
transistorT1 is in operation during a priod of t1, and voltage of source electrode of Va is applied to the LCD
layer of picture element A, then electric charges are stored in the picture element of A. After the period of
t1, T1 is turned off, and voltage in the LCD layer of A is held until next gate pulse comes, but it drops little
by little through off leak resistance of TFT and leak resistance of LCD itself.
BACK LIGHT
The camera unit is equipped with a fluorescent light source to provide the back lighting for its LCD. The
normal service life of the backlight is approximately six years, when the camera is used for about two hours
a day.
The backlight is consumption items, so even under guarantee replace it under charge basis.
Selective period
Y1
Picture
element A
Y2
Y3
Ym
— 12 —
Gate electrode
Source electrode
T1
T3 T4
T2
X2 X3 X4
X1
TFT array substrate
Common
electrode
V COM
Tn
Xn
Common substrate