Block diagram of steering angle detection

The following block diagram shows the steering angle detection in simplified form.

Fig 1: Steering Angle Detection Block Diagram

Courtesy of BMW OF NORTH AMERICA, INC.

COMPONENTS DESCRIPTION CHART

Index	Explanation
1	Sliding register
2	Schmitt trigger
3	Photo-transistor
4	Code disc
5	Light-conducting element
6	LED (infrared)
7	Sensor circuit board
8	Activation of LED

The LED (8) is supplied with pulse-width modulated voltage, thus also supplying the light-conducting element (5) with infrared light. The light-conducting element projects the light onto the code disc (4). The photo-transistors (3) pick up the light signals.

The signals of the photo-transistors are processed in the downstream electronics (2) into the signals "1" or "0". The signals of the 12 photo-transistors are put together to form the digital code.

The sliding register (1) picks up the digital code and forwards it to the electronics of the steering column switch cluster.