The signals subjected to phtoconversion in the light-receiving segment are sent out in two types of analog signals: even-number (EVEN) pixels and odd-

number (ODD) pixels.

6.2.4 Gain Correction and Offset Correction of the CCD Output

/ iR8070

To correct discrepancies in the efficiency of photoconversion among pixels, the analog video signals from the CCD are corrected: in gain correction, the

rates of amplification are standardized; in offset correction, on the other hand, the output voltage in the absence of incoming light is set to a specific level.

6.2.5 A/D Conversion of the CCD Output

/ iR8070

The analog video signals of odd-number and even-number pixels after correction are converted into 8-bit digital signals that correspond to specific pixel

voltage levels by the A/D converter.

Service Mode:

- COPIER/ADJUST>ADJ-XY>ADJ-Y (CCD read start position adjustment)

It is used to adjust the parameter used determining the read start position in main scanning direction.

Range: 100 to 400

(A change by '1' results in a shift of 0.1 mm.)

6.2.6 4-Channel High-Speed Reading CCD

iR105i/iR105+ / iR9070

To support high-speed reading at 80 ipm, the machine uses a 4-channel high-speed reading CCD. It consists of two CCDs connected to form a single entity

(each, half length of a common CCD); the entire CCD is divided in the middle into first half and last half.

Reading starts simultaneously at both left and right sides, thereby cutting the data transfer time required for reading by half and ultimately enabling high-

speed reading.

The image data is divided into 4 channels: first-half even-numbered pixels, first-half odd-numbered pixels, last-half even-numbered pixels, and last-half

odd-numbered pixels. The following diagram shows how CCD data is transferred:

Shift register

Gate

Light receiving

segment

(photodiode)

Shift register

Decrease

Increase

Original

Vertical size plate

Output buffer