Canon imagePRESS 1135 Series Service Manual page 99

2
Technology > Image Formation System > Various Types of Control > Image Stabilization Control
● Patch Image Density Detection
Toner density is detected by the patch density sensor on the ITB.
Part configuration
The patch density sensor consists of the light sending part (LED) and light receiving part
(reflected light detection, direct light detection).
1) Light sending part (LED): Apply light to a patch image.
2) Reflected light detection part: Receive reflected light from a patch image
3) Direct light detection part: Receive LED light.
Patch sensor
PATCH_OUT
PATCH_LED_REF
DC controller PCB
PATCH_LED_ON
Description
The LED light is reflected to the patch image on the ITB, and then received at the reflected
light detection part.
Since black toner has the feature that absorbs the light, if the patch image density is dark, the
reflection light that is detected by the light-receiving block becomes weak and if it is light, the
reflection light that is detected by the light-receiving block becomes strong.
The light detected by the light-receiving block is transferred to the DC controller as a density
signal (PATCH_OUT). DC controller corrects the image density according to this density
signal.
Also, the patch sensor automatically adjusts the LED light intensity to be even by using the
REF voltage (PATCH_LED_REF) that is given by the DC controller.
MEMO :
Since this machine detects the home position of the photosensitive drum, a patch
image is developed onto a specified position on the photosensitive drum.
2 Technology > Image Formation System > Various Types of Control > Image Stabilization Control
Photosensitive drum
Patch image
ITB unit
F-2-66
Related Error Code
• Patch sensor light intensity error
E020-1000: The value detected when patch sensor LED is corrected is less than
specified value.
< Patch image at the D-max control >
A patch consists of a halftone patch area and a shadow patch area.
Halftone patch is used to correct a halftone patch density.
Shadow patch is used to correct a solid density (maximum density).
Drum rotation direction
Approx Halftone patch
49 mm (for correction of halftone)
Approx 80 mm
< Patch image at the D-half control >
Patch images are 9 types at the maximum. This patch is for copy model and PS option.
The printer model of Canon PDL doesn't execute D-half control.
< Patch image >
Drum rotation direction
14 patches x 9 types (dither pattern)
PS/PDF (Adobe/EFI)
1
Equipped model
2
3
Unequipped model
4
Shadow patch
(for correction of solid density)
Approx 80 mm
F-2-68
Reader Patch image
Available 9 types
Unavailable 6 types
Available 3 types
Unavailable -
2-51
F-2-67
T-2-44
2-51