Ricoh SP 200 Specifications download pdf (Page 25)

2.2 SBU (SENSOR BOARD UNIT)

The CCD converts the light reflected from the original into an analog signal.

The CCD line has 5,000 pixels and the resolution is 400 dpi (15.7 lines/mm).

The CCD has two output lines, for odd and even pixels, to the analog

processing IC. The analog processing IC performs the following operations

on the signals from the CCD:

1) Z/C (Zero Clamp):

Adjusts the black level reference for even pixels to match the odd pixels.

2) Signal Composition:

Analog signals for odd and even pixels from the CCD are merged by a

switching device.

3) Signal Amplification

The analog signal is amplified by operational amplifiers in the AGC circuit.

The maximum gains of the operational amplifiers are controlled by the

CPU on the BICU board.

After the above processing, the analog signals are converted to 8-bit signals

by the A/D converter. This will give a value for each pixel on a scale of 256

grades. Then, the digitized image data goes to the BICU board.

CCD

AGC

Reference

Controller

Z/C

Vin

ref

IPU

Analog

Processing IC

SBU

BICU

Z/C: Zero Clamp

AGC: Automatic Gain Control Circuit

ODD

EVEN

Amp.

A/D

A193D502.wmf

IMAGE PROCESSING 1 August 1996

2-6

1 2 ... 20 21 22 23 24 25 26 27 28 29 30 ... 237 238

No comments

Ricoh SP 200 Specifications Page 25