U.S. Philips Corporation

Dietrich Meyer-Ebrecht

Gunter Kowalski

Wolfgang Wagner

Hermann Weiss

Klaus Pasedach

Gunther Groh

Jens H Christiansen

A simple circuit for converting the resistance variations of a strain gauge measuring bridge into a frequency variation of an oscillator. The circuit includes first and second phase shift circuits connected in cascade in a feedback loop with a frequency-independent device having a variable gain factor F connected in parallel with the first phase shift circuit. The first phase shift circuit includes a high pass filter and a summing amplifier and the second phase shift circuit includes an all-pass filter circuit.

Circuit arrangement for converting a resistance variation into a

In the conventional transformation coding of pictures the value ranges of the coefficients then produced are extended during the performance of the individual arithmetical steps. As a result thereof these coefficients have a great redundancy. According to the invention, the arithmetical steps which are formed by the basic transformation of two values are performed so that as a result of each arithmetical step only the original word length is obtained, because in each arithmetical step a portion of the value range of the result is mapped onto a different area. An example for the technical implementation of such a mapping on modified coefficients and the retransformation of these modified coefficients is described.

Arrangement for storing or transmitting and for recovering picture

A circuit arrangement for transmitting signals from a measuring transducer via a two-wire circuit to a receiver which, in turn, via the same two-wire circuit supplies power for operating the transducer. The circuit arrangement comprises a voltage controller, a current switch a current generator, and a power-storage capacitor connected at the transducer end of the two-wire line. The voltage controller supplies the voltage from the two-wire circuit to the measuring transducer as a regulated voltage. Parallel to this the current switch charges the power storage capacitor in the rhythm of the frequency-analog measurement signal. Via the current generator, e.g. an ohmic resistor, the capacitor also receives the voltage input from the measuring transducer. The operating current of the measuring transducer is thus provided partly by the voltage controller and partly by the current generator or resistor. The ratio of these currents determines the modulation depth of the current pulses on the two-wire circuit.

Circuit arrangement for the transmission of measurement value signals

In fan beam X-ray scanners operating with a large number of detectors, errors at and near the center of rotation are caused by the fact that the radiation absorption in said area is substantially always measured by the same detectors and that the sensitivity of all detectors is not exactly the same. The invention provides an improvement in that the measurement is carried out with a larger number of detectors than is necessary for the measurement of the scanning field and that the detectors pivot during the measurement. As a result, the absorption in the center of rotation is measured by different detectors so that, for a sufficient number of detectors the different sensitivities, errors are averaged and thus reduced or cancelled.

Fan beam CT scanner with compensating detector motion

A device for correcting measuring values of a group of radiation detectors for measuring the intensity or distribution of radiation, comprising an additional radiation source for direct irradiation of the detectors. The radiation of the said additional radiation source can be switched on each time when the radiation to be measured is not incident on the radiation detectors. The device furthermore comprises a calculating device which forms for each radiation detector the quotient of the measuring value (M1(x)) and the reference measuring value (M2(x)) of the radiaton detectors when exposed to the radiation of the additional radiation source.

Device for measuring radiation absorption or emission

A carrier wave compensator includes a novel sampling filter connected between a null amplifier and a compensation potentiometer to suppress interference voltages without deteriorating the dynamic response of the system. The sampling filter includes a multiplier, an integrator and a sample and hold circuit which is reset during zero passages of the carrier wave.

Carrier wave compensator with interference suppression circuit means

The bridge unbalance of a measuring bridge including a measuring transducer is converted into a frequency variation of an RC-oscillator. Since measuring transducers often have characteristics which are not exactly linear, such a conversion, which exactly compensates for said non-linearity, would be effective. For this purpose, correction voltages are derived from the voltages supplied by the oscillator by means of differentiation circuits and integration circuits, which voltages are proportional to the positive respectively the negative powers of the frequency. The differentiation circuits and integration circuits respectively are supplied with oscillator voltages such that at their outputs voltages of the correct phase are obtained. The voltages from the differentiation circuits and integration circuits are added via summing resistors and are superimposed on the compensation voltage of the oscillator.

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Hamburg, Germany

Dietrich Meyer-Ebrecht