Ultrasonic pulse Doppler blood flow meter
AssigneeFujitsu Limited
InventorShin-ichi Amemiya
Life of this patent
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Abstract
An ultrasonic pulse Doppler blood flow meter, wherein an amplitude equalizing circuit is inserted between the high-pass filter provided in the successive stage of the Doppler detector and the Doppler analyzer. The amplitude equalizing circuit not only effectively utilizes the input dynamic range of the Doppler analyzer but also automatically adjusts the cut-off frequency of the high-pass filter in accordance with the input signal. Therefore, a blood flow meter which requires minimal manual adjustment is obtained.
Claims8
An ultrasonic pulse Doppler blood flow meter operatively connected to transmit and receive ultrasonic wave signals, having a specific repetition frequency, to and from living body tissue, comprising:
- an ultrasonic probe for transmitting the ultrasonic wave signals to the living body tissue and receiving the ultrasonic wave signals from the living body tissue at the specified repetition frequency;
- a receiving amplifier, operatively connected to said ultrasonic probe, for amplifying the received ultrasonic wave signals from the ultrasonic probe and outputting an output signal;
- a Doppler detector, operatively connected to said receiving amplifier, for mixing the output signal of said receiving amplifier with a reference signal and for generating a Doppler signal of a specified depth having a low frequency element;
- a high pass filter, operatively connected to said Doppler detector, for eliminating the low frequency element of the Doppler signal and outputting a high pass filtered signal;
- an amplitude equalizing circuit, operatively connected to said high pass filter, for substantially equalizing the amplitude of the high pass filtered signal to a predetermined signal level and outputting an equalized signal;
- a Doppler analyzer, operatively connected to said amplitude equalizing circuit, for analyzing the equalized signal of said amplitude equalizing circuit;
- and
- a display, operatively connected to said Doppler analyzer, for displaying the result of the analysis of said Doppler analyzer.
An ultrasonic pulse Doppler blood flow meter including an ultrasonic probe for transmitting ultrasonic wave signals to living body tissue and receiving the ultrasonic wave signals from the living body tissue at a specific repetition frequency, and a Doppler detector circuit, operatively connected to the ultrasonic probe, for mixing the ultrasonic wave signals with a reference signal and generating a Doppler signal, said ultrasonic pulse Doppler blood flow meter further comprising:
- an amplitude equalizing circuit, operatively connected to the Doppler detector circuit, for substantially equalizing the amplitude of the Doppler signal to a predetermined signal level and outputting an equalized signal, said amplitude equalizing circuit comprising:
- a multiplier circuit operatively connected to the Doppler detector circuit;
- an integrator circuit operatively connected to said multiplier circuit;
- a rectifier circuit, operatively connected between said integrator circuit and said first multiplier circuit, for detecting the amplitude of the Doppler signal;
- and
- a level setter circuit, operatively connected to said integrator circuit, for designating a desired signal level.
Dependencies are inferred from the claim text.