Heating and contrast for the liquid-crystal display

A heater built into the display ensures good legibility even at low ambient temperatures. The heater is switched on if the temperature of the liquid-crystal display is below 10° Celsius. The switch-on signal is transmitted (by the CAS control unit to the instrument cluster via the K-CAN) when the driver's door is opened.

The contrast of the liquid-crystal display is automatically set as a function of the temperature of the liquid-crystal display and the operating time. A counter registers the standby times and operating times logged by the instrument cluster, so that due allowance can be made for ageing. Contrast voltage is automatically adjusted depending on increasing time in operation (ageing).