Zf Friedrichshafen Ag

Cherry Corporation

Thomas Luber

Martin K Zapf

Hans-Ludwig Götz

Josef Habenschaden

Werner Beck

Reinhard Pirner

Hans Götz

Werner Keck

A sine wave oscillator for an inductive sensor system is disclosed. The sine wave oscillator comprises a decoupler and a low-pass filter, wherein the decoupler is configured to provide a pulse width modulated signal as a decoupled signal at one output of the decoupler. One input of the low-pass filter is connected to the output of the decoupler. The low-pass filter is configured to provide a sinusoidal signal for the inductive sensor system by using the inverted signal at an output of the low-pass filter. The sine wave oscillator further comprises a microcontroller that is designed to provide the pulse width modulated signal with a predetermined frequency and a predetermined duty cycle at one pin of the microcontroller.

Sine wave oscillator and inductive sensors

The invention relates to an inductive sensor unit having one or several coils, which are mounted on a printed circuit board in a planar manner. According to the invention, a change in the inductance of a sensor coil due to leakage currents in the inductive actuator is correlated with the position of the actuator in two respects i.e., with the distance x to the sensor coils and with the overlapping y of the sensor coils. As a result, an inductive push button switch and an inductive position switching device (a sliding switch) are provided. The invention also relates to the evaluation of the inductance by means of reactance measurement. A relative evaluation of the influence of adjacent sensor coils increases the precision of response in push button switches and, generally, a relative evaluation of the influence of adjacent sensor coils is carried out in position switching devices.

Inductive switch

The invention relates to an inductive sensor unit having one or more sensor coils, which have been mounted on a printed circuit board in a planar manner. According to the invention, a change in the inductance of the sensor coils caused by leakage currents in the conductive actuator is correlated with the position of the actuator with regard to the distance from the sensor coil and with the overlapping of the sensor (at a fixed distance). This provides the basis for an inductive momentary contact switch and an inductive position switching device. The invention also relates to the evaluation of the inductance, e.g. of the momentary contact switch such as in inductive proximity switches by incorporating the inductive sensors in an oscillating circuit. Alternatively, the change in inductance can also be detected by a reactance measurement. A relative evaluation of the influence of adjacent sensor coils is carried out in position switching devices.

An inductive sensor for detecting the position of a vehicle seat or for a gate shifting unit of an automatic transmission is described. The inductive sensor unit has a plurality of sensor coils that are disposed in planar fashion on a printed circuit board A conductive actuation element is guided, spaced apart, in a path over the sensor coils and an electrical evaluation circuit detects changes in inductance of the sensor coils in accordance with the path position of the actuation element and converts the changes into electrical signals corresponding to seat position signals on gear shifting signals. The actuation element is guided along the sensor coils with conductive bottom faces that are staggered in the direction of the path.

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Hahnbach, Germany

Thomas Luber