CS206229B1 - Connection for digital evaluation of measuring the thickness of material by the ultrasound - Google Patents

Description

The invention relates to a circuit for the digital evaluation of material thickness measurement by ultrasound.

The digital measurement of material thickness by ultrasound is performed by sending an ultrasonic pulse into the material, which is again received after reflection from the second wall. An input pulse is obtained, the duration of which is equal to the time of ultrasonic signal passing through the measured material and is proportional to the thickness of the measured material. During this input pulse, pulses from the pulse generator are fed to the counter. The count count is proportional to the thickness measured. The accuracy of measurement is given by the pulse generator frequency and is limited to those frequencies that the following circuits are capable of processing. In order to read directly the measured thickness on the counter, it is necessary to divide the pulses before arriving at the counter by a suitable constant. In order not to reduce the accuracy of the reading of the thickness gauges, a plurality of successive input pulses are measured. The disadvantage of this method is that the resulting reading on the counter, which is the average of the individual measurements, does not affect the thickness deviations in the short term. The resulting measurement accuracy in this method is given by the pulse generator frequency used.

The above-mentioned drawbacks are overcome by the circuit according to the invention, the essence of which lies

In that a voltage source of one polarity and a voltage source of opposite polarity are connected to a switch whose output is connected to an integrator The integrator output is connected to a comparator input whose output is connected to one gate circuit terminal, while the other parallel circuit terminal is connected to a pulse generator and a gate circuit output is coupled to a pulse counter.

The circuit according to the invention makes it possible, by means of an analogue integrator, to extend the time during which the pulses from the pulse generator are fed to the counter and thereby increase the achievable accuracy of the digital measurement evaluation. The extension of the time during which the pulses are fed into the counter can be selected so that the number of counted pulses and thus the reading on the counter display is directly equal to the measured thickness. Extending this time can simply be accomplished by varying the voltage applied to the integrator, allowing easy adjustment of the blood pressure gauge for materials with different ultrasonic signal propagation rates.

1 shows a block diagram, FIG. 2a shows a graph of the input pulse time, FIG. 2b shows the voltage on the input integrator, FIG. 2c shows the time the comparator is tipped over, FIG. Fig. 2d shows the waveform of the pulse counter input; Fig. 2e shows the waveform of the integrator input at different source voltages.

One polarity voltage source 1 and opposite polarity voltage source 1 are connected by switch 4 to integrator 5. The output of integrator 5 is connected to comparator 6. Comparator 6 is connected to a gate circuit 7, to which the second pulse generator 8 is connected. The output of the gate circuit 7 is connected to a pulse counter 9.

The input pulse 3, corresponding to the time of the ultrasonic signal passing through the measured material, is controlled by a switch 4 which for the duration t of the input pulse (FIG. 2a) connects to the input of the integrator 5 a voltage source of one polarity. As long as this power supply is connected, the voltage at the integrator output increases linearly. Upon completion of the input pulse 3, a reverse polarity voltage source 2 is connected to the integrator 5 input via switch 4. The output voltage of the integrator 5 starts to decrease linearly up to the limit value and then stays at this value until the next input pulses arrive.

FIG. 2b. The comparator 6 is set to flip as soon as the voltage at the output of the integron 5 rises above the limit value. The comparator is overturned below the time T (FIG. 2c), which is the sum of the time duration t of the input pulse and the time t1 for which the integrator returns to the extreme limit. The time T depends on the voltage magnitude of the sources 1 and 2 and the integration constant of the integrator 5 and can be easily adjusted so that the number of pulses read by the pulse counter is directly equal to the measured thickness. The adjustment can be made, for example, by a control element in the source 2 circuit of the opposite polarity, thereby changing the rate of decrease of the voltage of the integrator 5 and hence the time t '(Fig. 2e). The output of the comparators 6 controls the gate circuit 7, which in turn. the time T passes the pulses from the 8-pulse generator to the 9-pulse counter (Fig. 2d). The measured thickness is read on a 9 pulse counter. By increasing the time that pulses from the pulse generator from time t to time T are supplied to the counter, the number of pulses read by the counter is increased in the ratio T: time and the same ratio increases the accuracy of the digital thickness measurement.

The wiring can be used in other fields, where the pulse duration is measured digitally, in addition to the mentioned use in the digital evaluation of material thickness measurement by ultrasound.

Claims (1)

SUBJECT Circuit for digital evaluation of material thickness measurement by ultrasound, characterized in that it comprises a source (1) of one polarity voltage and a source (2) of opposite polarity whose outputs are connected to a switch (4), the output of which is connected to the integrator (5) wherein the output of the integrator (5) is OF THE INVENTION connected to a comparator input (6) whose output is connected to one gate circuit terminal (7), while a second gate circuit terminal (7) is connected to a pulse generator (8) and a gate circuit output (7) is connected to a counter (7) 9) pulses.