Control Of Exposure Lamp; General Description - Toshiba e-STUDIO453 Service Manual

6.4 Control of Exposure Lamp

6.4.1 General description

Control crcut for the exposure lamp conssts of the followng three blocks:
(1) Lighting device for the xenon lamp (Inverter)
Turns ON/OFF the exposure lamp.
(2) CCD circuit
This circuit converts the reflected light amount from the original surface and the shading correc-
tion plate to electrical signals. The exposure amount is controlled in two ways:
(a) White reference formation - reads the reflected light amount from the white shading correction
6
plate
(b) Black reference formation - reads the light amount at the regulation position with the expo-
sure lamp lights OFF
(3) Image processing circuit
A series of image processes such as a gamma correction and a shading correction are applied
on the output signal from the CCD. The signal is then digitized and output from this circuit.
PWA-CCD
e-STUDIO350/352/353/450/452/453
SCANNER
Shading correction plate
Original
CCD
Exposure lamp (xenon lamp)
PWA-SLG
A/D
Image processing circuit
Fig. 6-401
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Lighting device
for xenon lamp
(Inverter)
Scanner
CPU