Touch Switch Inputs - Canon NP6251 Service Manual

4. Touch Switch Inputs

The keys on the touch panel and the control panel controller PCB are connected as
shown in Figure 7-102.
The touch switch panel consists of a sheet of glass having a transparent conducting
membrane and a sheet of film with spacers in between; it shows a pattern consisting of
15 rows and 20 columns.
When its surface is pressed with a finger, contact between the glass and the film
causes electrical continuity, thereby connecting a pair of electrodes so that the
corresponding X/Y coordinates are obtained as in the case of a common key matrix.
In other words, the correspondence between key scan signals from the control panel
controller circuit and the input signals to the control panel controller circuit enables the
control panel controller PCB to identify which key has been pressed.
COPYRIGHT © 1997 CANON INC.
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Figure 7-104
CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 7 EXTERNALS/AUXILIARY MECHANISMS
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