Device for checking the evaluation circuit for automatic switching operations of illumination device in vehicles

Abstract

A device for checking the evaluation circuit for automatic switching operations of the illumination devices in vehicles. A sensor device contains a global sensor for detecting the light conditions in the environment of the vehicle and a directional sensor for the directed detection of the light conditions in the direction of travel in front of the vehicle. The signals of the sensor device are supplied to the evaluation circuit, to determine whether a change in the switching state of the illumination devices is necessary. In order to check the evaluation circuit which is designed using analog technology, in the operating state, the voltage supply to the sensor unit is briefly interrupted at predetermined intervals, as a result of which the condition “night” is simulated. When the evaluation circuit is functioning correctly, this is detected by it as such. When the evaluation circuit is not functioning correctly, a signal is generated, directing attention to the faulty functioning and causing further steps to be initiated. In an embodiment, the checking operation and the voltage interruption are carried out by a microcontroller. In a second checking operation, it is established, in particular in the software, whether the emitted signal values of the evaluation circuit do not exceed a lower value that is determined by the hardware. In a third checking operation, the correct functioning of the A/D converter unit is ascertained.

Dependencies are inferred from the claim text.