U.S. Philips Corporation

Jurgen Kordts

Gerhard Martens

Thomas Helzel

Axel Nathe

Ralf Beier

Friedrich E Hahn

Paul Sonnenberger

Wolfgang Hoppe

Reinhard Knochel

Reiner U Orlowski

Friedrich-Karl Beckmann

Georg Weidinger

Michael Ramm

Joachim W Gensel

Georg Kisters

Ingobert H Gorlt

Gerald K Finck

Peter Rolla

The binary values of the data word to be converted in a widely used type of D/A converter are supplied to a series of stages in which binarily stepped currents are supplied to a common output or derived therefrom, or are conducted to a second common output. To control the current switch, each stage comprises a flipflop in which the binary value to be converted is stored. Integration processes are often used in the integration of analog circuits by means of which digital circuit components cannot be usefully realized, for example, in the IIL technology. In the flipflop comprising cross-coupled transistors, the emitters are connected to a reference voltage which lies between ground potential and the supply voltage so as to obtain a favorable conversion of the digital signals for triggering the current switch. This renders it possible to connect the collectors of the transistors of the flipflop directly to the bases of the current switch. In addition, the control of the flipflop is simplified thereby, and the delay time is shortened.

Circuit arrangement for a memory cell of a D/A converter

A symmetrical amplifier includes a current mirror circuit and a current splitting circuit. The current splitting circuit splits up an input signal applied to the amplifier as a function of the signal polarity. Negative input currents are applied to the current mirror circuit whose controlled output current is applied to a control input of a first current amplifier circuit arranged in the amplifier. In order to insure symmetrical operation of the amplifier, positive input currents flowing into the amplifier are applied to a control input of a second current amplifier circuit arranged in the amplifier. The second current amplifier circuit is the same as the first current amplifier circuit. The first current amplifier circuit is connected to a positive supply voltage and the second current amplifier circuit is connected to a negative power supply voltage, and the two current amplifier circuits operate into a common load at their output ends.

Amplifier having a symmetrical output characteristic

A sensor includes a pair of resiliently loaded jaws for receiving a finger, the sensor including a pair of fiber optic light transmitting guides secured in fixed spaced relation to one of the jaws for sensing blood in the finger tip. A control unit includes a light generator for transmitting light modulated at first and second frequencies to one of the guides via a light guide transfer section. The finger pulse modulates the received transmitted light. The modulated light is sensed by the other guide and returned to a receiver in the control unit via the transfer section for separating and demodulating the different frequency signals. The control unit includes a calculating unit which has two branches for processing and then combining by dividing the processed demodulated signals for determining the oxygen content of the blood from the relative magnitudes of the pulse-dependent modulation factor of the wave reflected from the finger.

Non-invasive oximeter arrangement

A processing circuit for a magnetoresistive rotary speed sensor (13) or the like having a comparator (11) with switching hysteresis for converting an analog sensor signal into a digital switching signal. An apparatus is provided at the input side of the comparator in order to alternately supply each of the comparator inputs, as a function of the switching signal at the output side of the comparator, symmetrically with a given hysteresis signal as a switching threshold. This apparatus also includes a preamplifier (15) which precedes the comparator non-inverting input and which amplifies the sensor signal, and an offset amplifier (18) of the same construction which precedes the comparator inverting input and which amplifiers an offset signal of a preceding offset network (21). The processing circuit provides a simple, integrable circuit which suppresses offsets and compensates for temperature and supply voltage fluctuations and any spread in tolerances of the circuit components.

Magnetoresistive speed sensor processing circuit utilizing a symmetrical

The invention relates to an optical sensor arrangement having a light emitting arrangement (2), which feeds a first emission light beam into a first emission optical waveguide (3) and a second emission light beam into a second emission optical waveguide, having a polarizer (5), which is coupled with the two emission optical waveguides and generates from the first and second emission light beam a respective linearly polarized light beam, and having an optical sensor (1), which alters the state of polarization of a supplied polarized light beam as a function of a physical quantity acting on the sensor and which supplies a sensor light beam formed from a polarized light beam. Behind the optical sensor (1) there is disposed an analyzer (7), which separates each sensor light beam into two linearly polarized reception light beams, one of which is fed to a light receiving arrangement (12) via a first reception optical waveguide (9) and the other via a second reception optical waveguide (11). From the reception light beams, the light receiving arrangement forms electrical signals, from which an evaluation circuit ( 13) determines the physical quantity.

Optical sensor arrangement including polarization-altering sensor

The invention relates to a fiber-optical sensor, comprising a light transmitter device (6) which couples transmitted light into at least one first ligthwave conductor (3,4) and also comprising a light receiver device (7) which receives light from the first lightwave conductor and at least one second lightwave conductor (4,3). The lightwave conductors (3,4) comprise adjacently situated portions (1) which can contact one another in a light-transferring manner at given areas and which are accommodated together in an envelope (5) at this area, a force or a pressure being applied to the lightwave conductor via said envelope. The light transmitter device (6) also couples a first transmitted light into the first lightwave conductor (3,4) and a second transmitted light into the second lightwave conductor (4,3).

Fiber-optical pressure sensor with contacting lightwave conductors

A circuit arrangement for temperature compensation of capacitive pressure sensors and differential pressure sensors includes two measuring capacitors (1,2) which are arranged in respective feedback branches of two measuring integrators (3, 4). The capacitance values vary as a function of the pressure or differential pressure to be detected and are converted into measurement signals by the measuring interconnect. A negative feedback circuit is provided which comprises a Schmitt trigger circuit (5) which at least generates a temperature-dependent activation signal for the measuring integrators from a measurement signal.

Circuit arrangement for temperature compensation of capacitive pressure

The invention relates to a voltage/frequency converter which contains a first and second change-over switch (13, 20). The first change-over switch supplies in its first position a measurement voltage and in its second position a reference voltage to a first input (15) of a comparison circuit (16). The second change-over switch supplies in its first position a first signal to be integrated and in its second position a second signal to be integrated via an integrator (22, 34) to the second input of the comparison circuit. The comparison circuit generates pulses dependent on the measurement voltage and sets the two change-over switches into their first position when the voltage supplied by the integrator is equal to the reference voltage, and into their second position when the value supplied by the integrator is equal to the measurement voltage. In this arrangement, one of the signals to be integrated is derived from the measurement voltage.

Voltage/frequency converter and its use in an optical wave guide

During the transmission of measurement values of a sensor from a transmitter circuit to a receiver circuit, for example via an optical fibre, use has been made of a device which must be activated by the receiver circuit before a measurement value can be transmitted. This is done in order to achieve potential freedom. The novel device for transmitting the sensor measurement values aims to operate faster and independently of the receiver circuit. The sensor (1) is activated by control pulses generated by a pulse generator circuit (3) and applies to the pulse generator circuit, during the occurrence of a control pulse, a measurement pulse which is dependent on the measurement value circuit. The repetition frequency and/or the width of the control pulse then depends on the amplitude value of the measurement pulses.

Device for transmitting measurement values of a sensor

A method of transmitting at least two measured values by means of light pulses which are passed by an optical transmitter through an optical transmission path to an optical receiver and whose relative separation in time is proportional to the measured value. The energy consumption for the optical transmission of the measured values is reduced by transmitting needle pulses cyclically, one after another in the same order of succession, in that per measured value an optical measuring pulse is transmitted, whose separation in time from the optical measuring pulse associated with a preceding measured value is proportional the magnitude of the measured value, and in that for each group of measured values an optical identification pulse is transmitted, whose distance in time from a preceding measuring pulse is smaller than the smallest possible distance in time between two successive optical measuring pulses.

Method of transmitting a group at least two measured values through an

The invention relates to a method of taking measurements along an optical transmission path by means of an optical sensor. The optical sensor includes an optical converter whose optical attenuation properties can be influenced according to the value to be measured and through which a first beam portion of a high-frequency amplitude-modulated optical transmission beam is passed. A second beam portion of this transmission beam is conveyed via a delay element. The second beam portion is applied together with the first beam portion outputted by the optical converter, via the transmission path as a receive beam to the receiver arrangement. In this way the modulation change produced by the sensor is processed and evaluated as an information about the measure value. Measuring a value at the transmitter end is possible with any optical transmission path of an undefined length, without recalibration of the receiver arrangement, because the optical transmitter beam is additionally subjected to low-frequency modulation. An original modulation factor m.sub.o of the transmission beam is preset as the ratio of the high-frequency (I.sub.HF) to the low-frequency (I.sub.NF) modulation amplitude and is fed the receiver arrangement 3. The received sensor-influenced modulation factor of the receive beam is measured by the receive arrangement 3. The received-to-original modulation signal ratio is evaluated as information about the measuring value (M).

Method of determining measuring data on an optical transmission path by

A circuits for compensating temperature-dependent and temperature-independent drift of a capacitive sensor including two measuring capacitors (3, 4) comprises pulse duration demodulators (11, 12) in the relevant input circuits. In accordance with pulses supplied by oscillators and whose duration is proportional to the capacitance of the capacitors, a d.c. voltage (U.sub.O) is applied to respective charging capacitors (17, 18) of the pulse duration demodulators (11, 12) for a predetermined period of time in order to charge this capacitors, after which zero potential is applied thereto in order to discharge the capacitors. The output of the relevant pulse duration demodulator is connected to the input (20, 21) of a summing/substraction member (19) whose output (23) supplies a d.c. voltage (U.sub.r). A d.c. voltage (U.sub.O), supplied by a controller (16) which compares one controller input d.c. voltage (U.sub.r) with a fixed reference voltage (U.sub.ref), is readjusted so that the d.c. voltage (U.sub.r) at the output (23) of the summing/subtraction member equals the fixed d.c. reference voltage (U.sub.ref) so that the output voltage (U.sub.a) of the circuit is free of temperature-dependent and temperature-independent drift.

Circuit arrangement for the compensation of temperature-dependent and

The invention relates to an optical time domain reflectometer (OTDR) with heterodyne reception for determining the attentuation of an optical waveguide (measuring waveguide) by measuring the back-scattered portion of light pulses sent into the measuring waveguide. This structure is comprised of a modulated laser light source sending a send beam into the measuring waveguide and a laser light source which constitutes a local oscillator and transmits continuous light, on whose light of a wavelength differing by an intermediate-frequency from the back-scattered light from the transmission light source is superposed and is applied to a photodetector having an intermediate-frequency electric output signal which is filtered and evaluated. To improve the signal-to-noise ratio it is provided that the transmission light source is a transmission laser 1 whose light is influenced in consecutive time intervals (t.sub.1 to t.sub.2) such that the light frequency varies between two cut-off frequencies f.sub.L1 and f.sub.L2 and that the light source forming the local oscillator is a laser transmitting light at a frequency f.sub.LO, which is located outside the range between the cut-off frequencies f.sub.L1 and f.sub.L2 and differs from a frequency value (f.sub.LM), located between the frequencies f.sub.L1 and f.sub.L2, by the intermediate frequency (F.sub.ZF).

Optical time domain reflectometer with heterodyne reception

An optical movement sensor for clearly accurately detecting deformations of a human body. The movement sensor consists of a belt with a buckle made up of two parts which are joined together mechanically by a light-transmitting sensor element. Transmitting and a receiving fibre optic light guides are connected to one part of the buckle in such a way that light emitted by the transmitting light guide passes through the sensor element by way of a polarizer and is coupled to the receiving light guide via an analyzer.

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Norderstedt, Germany

Jurgen Kordts