Nokia RM-555, Руководство по обслуживанию

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User interface
Resistive touch screen
Proximity sensor
The proximity sensor is used to turn off the touch input, when the phone is against user’s ear during call.
This prevents accidental touch signals that could happen when, for example, user’s cheek touches the phone.
The main parts of the proximity sensor subsystem are:
•
Proximity sensor
•
Proximity boot (mechanical part)
Figure 76 Proximity sensor and boot
The proximity sensor is located on the upper flex assembly.
Features
The Proximity sensor has following features:
•
2.8V
•
1.8V compatible IOs
•
Low power consumption
•
10-20 mm sensing distance (white reflector)
•
Factory calibrated, no calibration required in care
•
Pb free/RoHS compliancy
The proximity sensor works by sending out a beam of IR light, and then switching when the beam is reflected
back. When the object is under 15 mm distance, detection will happen and output will go to high state (1.8V).
Touch screen controller
TSC2004 (N500 on Main FPC) is a touch screen controller for resistive touch pads. It contains a complete
ultralow-power, 12-bit, analog-to-digital (A/D) resistive touch screen converter, including drivers and control
logic to measure touch pressure.
It also has embedded pre-processing function to reduce the output bus load. The host interface in TSC2004
is I2C.
RM-555
System Module and User Interface
Issue 1 COMPANY CONFIDENTIAL Page 6 –23
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