Ricoh M0A0 Service Manual page 588

2.Mechanism
Touch panel
The touch panel of this machine uses a 4-wire resistive film method (low load resistive film analog 4-wire method). It can
detect two points for flick/drag/pinch-in/pinch-out operations. Resistive touch panel has been adopted in order to
allow operation with a prosthetic hand.
Basic Structure
An analog 4-wire resistive film touch panel has 2 layers. Two materials (mainly film or glass) with transparent
conductive film (ITO) are attached such that the transparent conductive film layers face each other.
When the film is pressed with a finger or a pen, the transparent conductive films contact each other and the touch panel
operation is recognized.
Insulators (spacing dots) secure space between the two transparent conductive film layers to prevent short-circuiting.
Because the transparent conductive film has a uniform resistance characteristic, the resistance value reflects the distance
of contact.
[A]: Spacing dot
[B]: PET film
[C]: Transparent conductive film
[D]: Base glass
[E]: LCD panel
Self-Check (multi-touch calibration) mechanism
With the Multi-touch calibration in the self-check function, the touch panel is automatically calibrated using the results of
touches to the top left and bottom right positions.
The values of "EVR_X", "EVR_Y", "X_MAX", and "Y_MAX" are used for internal processing. They do not indicate the
positions or distance of the touched points. There is no problem unless there is a huge difference between the values of
the first calibration and the second calibration.
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