Abstract: 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.

Abstract: 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.

Abstract: An optoelectronic measuring system comprises at least two transmission light sources that emit time-sequentially clocked, phased light. A compensation light source is controlled independently of the transmission light sources. A receiver receives the light radiated by the transmission light sources, and the compensation light source converts them into an electrical received signal. At least two evaluation units evaluate the received signal and generate one control signal each. At least two transmission paths each comprise a transmission light source, an evaluation unit and a clock generator. The clock generator generates the clock for the transmission light sources and for the evaluation unit. The evaluation units each generate a control signal. A control unit generates a compensation control signal from the control signals, with which the compensation light source is controlled and supplied.