Image Density Calibration (D-Max) Control; Image Halftone Calibration (D-Half) Control; Developing Rotary; Outline - Canon MF8100 Series Service Manual

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Chapter 2

2.3.3.2 Image Density Calibration (D-max) Control

This control is performed to stabilize the image density of the printer engine.

The DCNT Board forms density patterns in each color on the ITB as varying the developing bias when specified conditions are met. Then the DCNT Board measures

the density of the patterns with the density sensor and controls the developing bias to obtain a proper density based on the measured density.

2.3.3.3 Image Halftone Calibration (D-half) Control

This control is utilized to measure a halftone density output from the SCNT Board in order for the SCNT Board to perform halftone calibration, and to return the

measurement results to the SCNT Board.

The DCNT Board forms image detection patterns for each color on the drum with a proper developing bias specified in the D-max control based on image data sent

from the SCNT Board. Then the DCNT Board measures the patterns with the density sensor and returns image data to the SCNT Board. The SCNT Board performs

the halftone calibration to obtain an ideal halftone image based on data.

2.3.4 Developing Rotary

2.3.4.1 Outline

The developing rotary has a function of moving a toner cartridge to a specified position. There are four toner cartridges (Y, M, C, Bk) stored in the rotary.

The rotary is illustrated in the figure below.

The developing rotary motor (DCM703) rotates the rotary so that the EP-87 toner cartridges in each-color face the drum one by one. As the rotary stops, the devel-

oping rotary stopper solenoid (SL93) is driven to lock the rotary.

The rotary performs engaging operations of the rotary and of the memory tag contacts, with the engaging motor (PM704). (See the memory tag engaging control

on page 2-60 for details on an engaging operation of the memory tag contacts.)

There are two sensors for the rotary, which performs position detection and engaging detection.

The functions the rotary has are described next.

2.3.4.2 Developing Rotary Rotation Control

This control is utilized to rotate the rotary during a print or toner cartridge removal operation in order to move each toner cartridge to its specified position.

The DCNT Board moves the rotary by turning on/off the developing rotary motor (DCM703) as monitoring the position of the rotary with the developing rotary

home position sensor (PS51). When the rotary stops, the DCNT Board drives the developing rotary stopper solenoid (SL93) to lock the rotary.

The DCNT Board monitors the PS51 to determine the stopping position of the rotary. It detects the position of the rotary from time for four cartridge flags located

on the left side of the rotary to pass the PS51.

The four cartridge flags are for detecting the developing positions for each cartridge. The DCNT Board determines a cartridge developing position when these flags

interrupt the PS51, and stops the rotation of the DCM703.

The flags are used for detecting the removing position for each cartridge also. The DCNT Board rotates the DCM703 for a specified period from the position at

where each flag interrupts the PS51 and then stops it. This position will be a removing position for each cartridge.

The DCNT Board will assume any of the following conditions to be a fault in the developing rotary locking mechanism and will stop the printer engine and, at the

same time, communicate the fact to the SCNT Board:

1) The home position detecting flag cannot be detected by PS51.

2) A fault exits during the period of detection between flags by PS51.

2-16

DCNT Board

Engaging

704

motor

Developing

rotary

stopper

solenoid