Technical Description
User Interface
Illumination
The phone is illuminated with 14 SMD LED's, 4 for the display and 10 for the key-
board. The LED's are switched on and off from GUSTAV. A voltage regulating cir-
cuit is included which prevents changes in the battery voltage from affecting the
backlighting intensity.
Buzzer
The buzzer, which emits the Beep-, Ring- and Alarm signals, is an electromagnetic
resonance buzzer with a resonance frequency of about 3 KHz.
The sounds are generated in GUSTAV by software control and then fed to the
buzzer.
LCD Display
The display is a 1- row segmented LCD which utilizes chip on glass technology for
mounting of the driver chip on the LCD module. No negative voltage supply is
required for this LCD and no contrast control is needed since the display in EF738
utilizes a technology which provides a wide viewing cone.
Keypad
There is a 5 x 4 keyboard scanning connected to GUSTAV.
A detection signal is set high when the END/PWR/NO key is pressed and by looking
at a feed-back signal GUSTAV is informed and turns the phone on.
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