Robert Boschgmbh

Klaus Berger

Karl-Heinz Affeldt

Arno Illenberger

Gert Ruprecht

Lutz Bottcher

To improve the accuracy of blood pressure measurement by utilizing the Korotkoff noises, the frequency spectrum of the Korotkoff noises is analyzed, either by a plurality of filters (16, 17, 18; FIG. 1) or by a Fast Fourier Transform (FFT) system (54, 55; FIG. 2). If a plurality of filters are used (FIG. 1), which may be analog or digital, then the output amplitudes are rectified (19, 20, 21) and quotients are formed. If the quotients have a predetermined relationship, as determined by a discriminator (27, 28), a control logic provides output signals to a manometer (31) to indicate, respectively, systolic and diastolic blood pressure. For Fast Fourier Transform, a microprocessor can be used which, simultaneously, can provide clock sources to digitize output from the microphone coupled to the cuff of the blood pressure measuring instrument.

Method and apparatus for measuring blood pressure by instantaneous

Proceeding in order from the light-side to the beam-side of the target structure, the structure includes a transparent glass plate, a transparent signal electrode, a photoconductive layer of n-type CdSe, and a layer of n-type ZnSe. The interface between the two n-type layers is possessed of a multitude of interface states capable of capturing holes optically liberated in the photoconductor and electrons injected by the scanning beam. Beam-injected electrons cannot pass directly across the interface, and therefore dark current is reduced in a manner as effective as with p-n junction target structures. Each optically generated hole trapped at the interface lowers the potential barrier for beam-injected trapped electrons by an amount such as to cause more than one such electron to enter the conduction band of the CdSe layer, resulting in greater-than-unity amplification. Amplification by factors in excess of 100 can be achieved.

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Berlin, Germany

Klaus Berger