Siemens Aktiengesellschaft

Alfred Forster

Robert Schwarz

Gerd Schorner

Rudolf Zimmermann

Heinz Walker

Thomas Koelpin

Helmut Riss

In the case of ultrasonic proximity switch systems having separate evaluation electronics and varying sensor designs, the evaluation parameters must usually be adapted to the particular sensor type. To avoid errors relating to this, it is advantageous when the system is switched over automatically when a new sensor type is connected. Previously, sensor identification has been realized through manual coding or by coupling different voltage levels to a sensor output signal. The aim is to reduce the susceptibility to faults and the expenditure entailed by this method by applying a plurality of sensors. This is achieved in that the oscillator frequency corresponding to the sensor type is indicated with the help of a counter by means of a pulse-width modulated signal, which corresponds to the pulses of the oscillator frequency that are counted according to the counter content. This counter is advantageously accommodated in an integrated circuit, with which a pulse-width modulated signal is already generated as temperature information.

Automatic sensor identification for ultrasonic proximity switches

The transmitting pulse required to operate an ultrasonic proximity switch is usually generated externally in separate evaluation electronics. This requires additional circuitry, either analog or digital circuits, or a microprocessor and associated software. In the case of ultrasonic proximity switches, which have an integrated circuit with transmitting oscillator, the generation of the transmitting pulse is performed by additional means provided on the integrated circuit for generating a transmitting clock pulse. By means of a control signal, it is possible to select between the operation with this transmitting clock pulse and a transmitting clock pulse supplied externally by the evaluation electronics.

Integrated automatic control for ultrasonic proximity switches

In measuring distance with an ultrasonic proximity initiator stochastic interference signals can cause false pulses which have been suppressed largely by pulse width evaluation. While limiting false releases based on false pulses, the evaluation of the echo signal has been coarse because the amplitude of the pulses is not evaluated. This shortcoming is eliminated by sampling the analog echo signal at the ultrasonic proximity initiator at given time intervals and then subsequently converting the sampled values into digital values. This step is followed by a program controlled mathematical combining of the new digital values with digital values stored in a data memory that were derived from corresponding times in previous echo signals. The new digital values produced by the mathematical combination are stored in a data memory and evaluated with respect to amplitude or pulse width to determine distance. The distance thus obtained is displayed for each pulse cycle. The method can be used in ultrasonic proximity initiators for measuring distance.

Method for the interference suppression in ultrasonic distance

A motor vehicle backup monitor introduces a reflector into the detection range of a sensor in predetermined manner during a test phase. The reflector can comprise, for example, the flap of the housing which encloses the sensor. The reflector is removed from the detection range of the sensor during its operational phase. The monitor unit is particularly applicable to ultrasonic sensors used to monitor a motor vehicle when it is backing up.

Monitor unit for sensors, particularly ultrasonic sensors, for motor

A method for suppressing interference signals during operation of ultrasonic proximity transducers suppresses the interference signals that are generated by continuous noises. Repeated ultrasonic pulses are transmitted from an ultrasonic proximity transducer, and the received signals are scanned. The scanned values of the received signal are converted into digital values. After storage, the digital values are compared with a step function having one or more step sections of constant value serving as a time-dependent interference noise threshold so that the usable echo signal can be determined and separated from the interference signals. With further evaluation, the echo transit time of the usable echo signal is determined and provided to a control and evaluation unit. By suppressing continuous noises, and further suppressing stochastic interference signals, the usable echo signal is reliably filtered from a reception signal that is overlaid with interference signals.

Method for the suppression of interference signals during operation of

An apparatus for remote distance measurement varies the decay time of an electronic transducer to measure the distance to objects that are close to the transducer. The decay time for the amplitude of the oscillations of the transducer is varied by changing the transmitting frequency of the transducer since the rate at which the transducer oscillations decay depends on the transmitting frequency. The frequency is changed using a circuit comprising an electroacoustic transducer, a generator, a receiving amplifier and a control circuit. The generator generates an oscillation signal having a constant transmitting frequency and constant amplitude for a given transmitting time that depends on the distance of the object from the transducer. The transmitting frequency is chosen to measure the distance to a close object so that the transducer amplitude decays so fast that the echo signal can be received and evaluated without interference. The circuit for the remote distance measurement apparatus has particular application in motor vehicles.

Apparatus for remote distance measurement

This invention is of an ultrasonic proximity switch having a range selection control circuit. The range selection control circuit is in this instance separated from the sensor by being installed in a separate housing which can be mounted in the switching unit. It is equipped with a potentiometer in the form of encoding switches and an actual value display which can be designed in the form of an LCD design. In addition, various selector switches can be mounted in the housing.

Ultrasonic proximity switch

The invention relates to an ultrasonic converter with a plate type ceramic oscillator in which metal electrodes are fastened to the oscillator. At one end face of the ceramic oscillator an adaptation layer of plastic is present. The entire ultrasonic oscillator, except for the side of the adaptation layer facing the medium to be insonated, is provided with a foam covering, to reduce decay damping without a substantial loss in the transmission factor.

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Schwandorf, Germany

Alfred Forster