1) The DC controller forms pattern images on the ETB with the optimized developing bias determined in the environment related corrective control, when the

density measurement execution command is sent from the video controller.

2) The DC controller allows the light emitter (LED) to emit light by sending the COLOR MISREGISTRATION/IMAGE DENSITY DETECTION LED DRIVE

signal.

3) The pattern image for the color gradation correction on the ETB reflects the light from the LED and the light receiver (PD) in the density sensor receives the light.

4) The PD converts the received light into voltage value and sends it to the DC controller in analog signal of the IMAGE DENSITY.

5) The DC controller converts the IMAGE DENSITY signal into the digital density data and sends it back to the video controller.

6) The video controller performs the color gradation calibration based on the density data in order to obtain an color gradation, when it receives the density data

from the DC controller.

The DC controller notifies the video controller of each error if the following warnings are given after the image density measurement. The density data is reset and

the initial data is set whenever an error occurs.

- The image density sensor abnormality warning: No density data is obtained.

- Image density measurement out of range warning: The measurement value is out of specified range.

2.4.2.4 Color Misregistration Corrective Control

/ i-SENSYS LBP5360 / i-SENSYS LBP5300

This is to correct a color misregistration caused by the variation inherent in the laser/scanner units and cartridges.

This control corrects the followings.

- Main (horizontal) scanning start position

- Main (horizontal) scanning magnification (see Note)

- Sub (vertical) scanning start position

Main (horizontal) magnification

This is the size of image in the main-scanning (horizontal) direction.

Every color has its own photosensitive drum in each cartridge in this printer. The positions of each drum differ and the laser beam lengths vary because of the

variations among the cartridges, that is, the horizontal scanning area depends on the color. This causes a color misregistration at the edge of image.

The color misregistration detective system to measure the four colors' misregistration level is applied to this printer.

This system is performed by detecting the positions of each color's misregistration pattern images transferred onto the ETB with a pair of sensors for the color

misregistration/image density.

The color misregistration/image density sensor is a reflection type with each of the light emitter (LED) and the light receiver (PD) placed on top of the ETB.

Each color's pattern image is formed on the ETB under the following conditions according to the command from the DC controller.

- At power-ON or door close after cartridge replacement

- After job completion every specified number of printings

- When execution command is sent from the video controller

The following is the operational sequence of this control.

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