Control Of Exposure Lamp; General Description - Toshiba e-STUDIO350 Service Manual

6.4 Control of Exposure Lamp

6.4.1 General description

Control circuit for the exposure lamp consists of the following 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 correction
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 plate
6
(b) Black reference formation - reads the light amount at the regulation position with the exposure
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-STUDIO350/450 SCANNER
Shading correction plate
Original
CCD
Exposure lamp (xenon lamp)
PWA-SLG
A/D
Image processing circuit
Fig. 6-401
6 - 8
Lighting device for
xenon lamp
(Inverter)
Scanner
CPU
November 2003 © TOSHIBA TEC