Canon EOS DIGITAL REBEL XTi, Руководство по обслуживанию

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Repair Information
10
1.8 Self Cleaning Sensor Unit
Prior to developing this unit, we analyzed the causes of visible dust and their types
and sizes. The dust becomes most noticeable at small apertures. We studied what sizes of
dust were the worst offenders at small apertures. The Self Cleaning Sensor Unit was then
developed to effectively eliminate those types of dust.
１） Unit configuration
Low-pass filter 1 on the front of the sensor is attached to an ultrasonic vibrating unit
driven by a piezoelectric element. By subjecting low-pass filter 1 to ultrasonic vibrations,
the adhering dust is shaken off the surface (Fig. 005). The removed dust then sticks to
an absorbent material* ringing the low-pass filter 1. This unit also has an internal O-ring
around the perimeter to keep out dust.
＊Absorbent material: This is industrial-grade, double-sided tape. It does not lose its stickiness even after alot of dust
adheres to it.
O-ring
Support material
Piezoelectric
element
Low-pass filter 1
CMOS sensor
Low-pass filter 2
Phaser layer
Infrared-absorbing glass
Fig. 035
２） Assurance of Sensor Cleaning Performance at Service Div.
It is difficult to attach the retention component to the low-pass filter and to apply the O
ring. In order to maintain the self-cleaning performance, when any problems are found,
be sure to replace the CMOS sensor unit with new one, instead of trying to repair the unit.
Also, you can determine whether the sensor cleaning operation is working correctly by the
sound (very small sound) it makes when operating. When it is working properly, you can
hear the sound.
Sensor cleaning operation
YES
YES
NO
Any operating sound? Replace CMOS unit.
Sensor cleaning function
works OK.
Fig. 036