Mechaless Systems Gmbh

Elmos Semiconductor Ag

Erhard Schweninger

Michael Hase

Rolf Melcher

Erhard Müsch

Roberto Zawacki

Opto-electronic measuring arrangement which is largely independent of extraneous light, comprising emitted and compensation light sources, which emit light time-sequentially and in a phased manner, wherein the emitted light is phase-shifted respectively by 180&#xb0;. An optical receiver receives the light emitted by the emitted light source and reflected by the object being measured together with the light from the compensation light source. The actuation signals for the emitted and compensation light sources are controlled such that the synchronous signal difference occurring in the receiver between the different phases is reduced to zero. The optical coupling between the compensation light source and the receiver diode occurs mainly via an optical system in a printed circuit board on which the compensation light source and the receiver are arranged. The printed circuit board itself, i.e. the FR4 component thereof, may constitute the optical conductor between the compensation light source and receiver diode.

Compensation for an optical sensor via a printed circuit board

The interference-compensated sensor for detecting an object located in a detection area in a contactless manner, particularly a rain sensor, is provided with a first and a second measuring channel each having a control device and an output, wherein both measuring channels are substantially identical. The sensor further comprises a main subtractor having an output for outputting the difference of the signals at the outputs of the measuring channels. The sensor is provided with a controller unit having an input that is connected to the output of the main subtractor and with an output for outputting a controller signal, by means of which the two measuring channels can be controlled in such a way that the signal at the output of the main subtractor can be controlled to zero. By means of the magnitude of the signal at the output of the controller, it can be determined if an object is located in the detection area.

Interference-compensated sensor

An opto-electronic measuring arrangement being independent from extraneous light includes a transmission light source and a compensation light source which sequentially emit light on a clocked phase basis. The emitted light is respectively phase-shifted. The light sources can be controlled such that the clock-synchronous signal difference between different phases becomes zero. A basic coupling light source transmits light directly to the optical receiver without the light being influenced by the measuring object. The basic coupling control current is so that a desired sensitivity of the measuring arrangement is achieved and/or a desired operating point can be set. The controllable current source for generating a clocked transmission control current and the controllable basic coupling current source for generating a clocked basic coupling control current are phase-synchronously clocked. The controllable compensation current source for generating a clocked compensation control current is clocked with the inverted clock signal of the clock generator.

Opto-electronic measuring arrangement with electro-optical basic coupling

An optical operating element comprises a light-emitting transmitter, an optical receiver, a prism, and a cover. The prism has a side surface that is an active sensor area, and the prism is arranged below the cover such that the active sensor area is oriented substantially parallel to the underside of the cover. The cover has a sensor region which is above the active sensor area and which has a transmittance of at most 99%, at most 95%, at most 90%, at most 80% or at most 50%. Light emitted by the transmitter is guided through the prism and passes through the active sensor area and the cover. The emitted light reflected at an object enters through the sensor region and the active sensor area and is guided through the prism to the receiver. A change in reflection is identified by an evaluation circuit and is interpreted as switching.

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Karlsruhe, Germany

Erhard Schweninger