GE HEALTHCARE CARESCAPE Monitor B650 Technical Manual page 131

Theory of operation
Figure 5 User interface board block diagram
Touchscreen sensor
The patient monitor has a resistive touchscreen sensor in the front of the LCD panel. The
touchscreen sensor detects the presence and location of a touch within the display area and
communicates the information to the touchscreen controller.
Keypad
The patient monitor has a backlit keypad board with an on/standby button, two function keys
and three power indicator LEDs.
The keypad is connected to the user interface board with a connector.
Trim Knob
The Trim Knob control is a rotary-switch with a push selection operation. The Trim Knob
encoder detects the direction of the Trim Knob rotation and push button use and passes that
information to the CPU board via the user interface board.
Alarm light board
The right hand side of the alarm light board contains red, yellow and blue LEDs to display
different priority visual alarms. The left hand side of the alarm light board has blue LEDs for the
silence alarm indicator light.
The alarm light board also has a separate light sensor that is capable of measuring the
ambient light intensity. The ambient light feedback can be used to auto-adjust the brightness
of the keypad backlits, alarm light LEDs and the to the different ambient light conditions.
The alarm light board is connected to the user interface board with the alarm light cable.
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