Canon Vizcam 1000, Service Manual

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3. OPERATION AND TIMING
COPYRIGHT © 2001 CANON INC. CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
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4. Touch Switch
The keys on the touch switch panel and the control panel controller PCB are connected as shown in
Figure 3-703. The touch switch panel consists of two sheets of glass coated with transparent conducting
membranes and joined with spacers in between; it has a matrix of 12 rows and 20 columns of keys.
When the surface of the top plate is pressed by a finger, the two plates of glass come into contact to
allow electrical continuity.
A pair of electrodes are connected and, as in the case of a conventional matrix, X/Y coordinates may be
identified. In other words, the correspondence between a key scan signal from the control panel controller
circuit and an input signal to the control panel controller PCB allows the control panel controller PCB to
recognize which key has been pressed.
Figure 3-703
Electrode Spacer
Electrode Glass plate
Glass plate