JPS62250386A - Ultrasonic measuring apparatus - Google Patents

Abstract

PURPOSE:To accurately measure the time between transmitting and receiving pulses without using an A/D converter, by controlling time measurement on the basis of the comparison with the max. peak holding value one before of a time attenuation type holding circuit. CONSTITUTION:The echo signal due to the reflection of an ultrasonic wave by a probe 11 and a receiving circuit 12 is supplied to a comparator 18 through a buffer circuit 15 and a gate circuit 16, and the max. value thereof is compared with the max. value of a receiving echo one before held to the peak holding circuit 17 of a time attenuation type holding circuit. Whereupon, because there is the difference with the holding value smaller than the lately max. value and having a level equal to or more than a noise level by attenuation, a stop signal is generated from the comparator 18 and the measurement of a time measuring circuit 19 is stopped at an accurate position where the receiving echo takes the max. value. By this method, the time between transmitting and receiving pulses can be measured accurately by a simple constitution requiring no A/D converter.

Description

[Detailed description of the invention] [Industrial use! The present invention relates to an ultrasonic measuring device, and in particular, an ultrasonic measuring device that performs various 7i-1 constants using ultrasonic signals, and an ultrasonic 1111 constant device that can measure ultrasound echoes without performing A/D conversion. The present invention relates to an ultrasonic measuring device that can detect the position of the maximum level of a received signal (hereinafter referred to as an echo signal), and can also measure the time until the echo.

[Prior Art] In an ultrasonic measuring device, thickness measurement, defect inspection, flaw detection, etc. are performed using ultrasonic signals. One waveform is as shown in FIG.

As shown in FIG. 3, when a transmission pulse l is applied to the probe, an ultrasound echo is returned, and the echo signal 2-1.
This is received as 2-2.2-3, but at this time, the state of the echo signal varies depending on the object to be inspected, and its waveform and number of pulses also differ. In addition,
Reference numeral 3 in FIG. 3 indicates a gate signal for extracting the echo signal.

In the case of plate thickness gage, defect inspection, flaw detection, etc., echo signal S; 2 2 from transmission pulse L (or surface echo)
By measuring the time t, the thickness of the object to be measured, the position of the flaw, etc. are determined by δ-1. However, in this case, in addition to the deliberate echo signal (2-1, 2-3), noise signals and surrounding signals are mixed in as echo signals 2-1, 2-3. Incidentally, the echo signal that is really desired to be obtained is generally a pulse signal when its peak value becomes maximum, as shown by echo signal 2-2 among the received echo signals.

[Problem to be solved] Conventionally, in ultrasonic measurement devices, in order to measure the following, the waveform of the echo signal itself is converted to A/1], and the subsequent processing is performed by converting the image into an image using software (program). This is done using a processing note. This method uses a high-speed A/D
With 7 converters and large capacity memo IJ+, the system becomes enormous.

In addition, as a similar method, in the case of crack measurement using ultrasonic waves, as shown in Figure 4, an echo transmitter is used.
Set the threshold voltage F1.4 at the level of , and measure the time until that level is exceeded. However, in this case, only the first time or the last time exceeding the threshold level 4 can be measured in total 71111, and it is not necessarily the time measurement of the maximum peak value of the echo signal.

That is, in FIG. 4, echo signal 2-1 is detected and time 1. is measured, or the echo signal 2-3 is detected and the time t2 is measured, which is different from the original measured value t.

[Purpose of the Invention] The present invention solves the problems of the prior art, and detects the position of the maximum value of the echo signal level and measures the time without performing A/D conversion. The purpose of the present invention is to provide an ultrasonic measuring device that can perform

[Means for Solving the Problems] The first stage of the ultrasonic measurement device of the present invention that achieves the above object generates a transmission pulse at a constant cycle, receives an echo from the object to be measured, and In an ultrasonic measurement device that measures the time until the echo signal and performs -1 constant,
The maximum value of the echo signal or a signal corresponding thereto (for example, an electrical signal corresponding to the ultrasound echo) is held by a time-attenuated holding circuit, and the echo signal or signal corresponding to the echo signal for subsequent echoes is maintained by a time-attenuated holding circuit. The maximum value is compared with the value held by the holding circuit, and the time measurement is terminated by outputting the difference.

[Operation: In this way, the maximum value of the previous echo signal or the signal corresponding to it is held by a time-attenuation type holding circuit, and the attenuation value of the held value does not fall below the level of noise or unnecessary signals. compares this held value with subsequent similar signals. Thereby, a pulse can be reliably generated at the position of the maximum value of the echo signal without being affected by noise or unnecessary signals.

As a result, the position of the maximum level of the echo signal -j can be reliably detected without A/D conversion, and the transmitted pulse (or its surface echo) can be detected at the peak of the echo signal.
It is possible to more accurately measure the time between the two, and it can be realized with a simple circuit.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram mainly showing the time measuring device in the ultrasonic measuring device of the present invention, and FIG. 2 is an explanatory diagram illustrating its operation. In addition, Fig. 3.

Components that are the same as those in FIG. 4 are designated by the same reference numerals.

In the ultrasonic measuring device 10, first, a received signal (echo signal) from the probe 11 passes through the receiving circuit 12, is inputted to the buffer 1 circuit 15, and passes through the gate circuit 16, as shown in FIG. 2(b). A target echo signal is extracted with the timing and width of the gate pulse signal 3, and is sent to a time-attenuation type peak hold circuit 17. Here, the gate circuit 16 is constituted by, for example, an analog switch.

Since the ultrasonic pulse reception signal is a high frequency analog signal, the echo reception value is as shown in Fig. 2 (a).
) as seen in the general super, 'zgL? gL type,
When this passes through the bumper circuit 15 and the gate circuit 16, it becomes a waveform as shown in FIG. 2(b), and only the analog echo signal between the gates is extracted. therefore,
Only ultrasonic echoes of an arbitrary period that are smaller than the transmitted pulse are obtained as echo signals corresponding to the echoes, and the maximum peak value of these echoes is held in a time-attenuated peak hold circuit 17.

In general, the peak hold circuit 17 has the characteristic that its holding voltage attenuates over time, but in particular, the term "time attenuation type" here means that the next echo Until the signal reaches its maximum value, it attenuates to a certain level lower than this, and that value is higher than the noise level. Note that the peak hold circuit generally has a built-in capacitive element such as a capacitor, and thereby stores the peak voltage value. Therefore, as time passes, the t and y values naturally decrease due to the discharge.

The output value of the value held in this peak hold circuit 17 (
For example, the voltage value) is then input to the comparator 18. The other side of the comparator 18 receives an echo signal corresponding to the echo signal shown in FIG. 2(b) output from the gate circuit 16, and the peak values are compared between them. Ru.

The comparator 18 then produces an output only when the latest peak value obtained from the gate circuit 16 exceeds the previous maximum peak value already held. Next, this output is inputted to the hour meter f11 circuit 19 and used as a stop signal for time measurement.

The time measuring circuit 19 is started by the reference signal S synchronized with the transmission pulse 1 and stopped by the output of the comparator 18. As a result, the measured time value is output to a measurement circuit such as a time-thickness conversion circuit in the next stage. Note that this time measuring circuit 19 uses a counter circuit using a digital element or an analog circuit. In the case of an analog circuit, an integrating circuit is started at the same time as the start signal, and a so-called ramp voltage is generated to output the output from the comparator 18. This is done by sampling and holding the lamp voltage at that time using a signal.

Now, in a state in which an object to be measured is measured by generating an ultrasonic signal, the transmission pulse 1 is generated at a constant cycle. As a result, the time-attenuated peak hold circuit 17
The maximum peak value of a signal that always comes in for a certain period of time (
For example, only the voltage value) is periodically held. That is, the peak hold circuit 17 periodically holds the maximum peak value of the echo signal 2-2 shown in FIG. 2(b) in accordance with the measurement period.

On the other hand, the echo signal outputted from the gate circuit 16 is also periodically input to the other input of the comparator 18. Here, the maximum peak value measured in the previous cycle held in the peak hold circuit 17 has already attenuated and has become a smaller value than at the time of holding. As a result, a difference occurs between the new maximum peak value determined by fl11 in the next cycle. This difference is periodically detected by the comparator 18. Therefore, the stop pulse can be reliably generated from the comparator 18 at the timing when the maximum peak (for example, maximum voltage) of the echo signal occurs.

That is, the comparator 18 generates an output at the position of the maximum peak of the latest echo signal, and no output is generated in the previous and subsequent echo signals 2-1, 2-3 shown in FIG. 2(b). What is important is that the echo signal of the ultrasound echo measured in the next cycle is sampled under the same conditions, so the holding voltage of the maximum peak value measured in the previous cycle is detected by the comparator. The value should be slightly smaller than the latest one to the extent possible. Note that this measurement period may be at least twice every 1- second period.

As described above, the time-attenuated peak hold circuit in the embodiment is for clearly explaining the invention, and a general peak hold circuit has a tendency for its held voltage value to attenuate over time. Therefore, this can be used.As mentioned above, the attenuation rate of the holding voltage is related to the measurement period.

As a specific example, although it depends on the characteristics of the peak hold circuit used, a normal peak hold circuit can be used for a relatively low measurement cycle of 2 kHz or less, and for example, for a measurement frequency of about 5 kHz or less, For l- type, one with a somewhat high attenuation rate is used.

Further, in the embodiment, the maximum peak value of the echo signal is held, but even if such a maximum value is inverted and becomes the minimum value, it is equivalent to looking at the maximum value, This is the maximum value referred to in this invention.

Furthermore, in the example, the echo signals for all constant echoes occurring in the next cycle are compared, but not the echo signals for the next measurement (however, some are thinned out and the echo signals in the measurement several cycles later are compared). It may also be compared with the maximum peak value.

Preferably, this may be an echo signal in subsequent measurements.

[Effects of the Invention] As can be understood from the explanation below, in this invention, the maximum value of the previous echo signal or the signal corresponding thereto is held by a time-attenuated holding circuit, This held value is compared with subsequent similar signals by ensuring that the attenuation value of the held value does not exceed the level of noise or the main type signal. As a result, a pulse can be reliably generated at the position of the maximum value of the echo signal without being affected by noise or other essential signals.

As a result, the position of the maximum level of the echo signal can be reliably detected without A/D conversion, and the time measurement 11 between the peak of the echo signal and the transmitted pulse (or its surface echo) can be made more accurately. 11
This can be achieved using a basic circuit.

[Brief explanation of drawings]

Fig. 1 is a block diagram centered on the time measuring device in the ultrasonic measurement device of the present invention, Fig. 2 is an explanatory diagram explaining its operation, and Fig. 3 is a general transmission/reception waveform in ultrasonic measurement. FIG. 4 is an explanatory diagram of a threshold level when extracting the position of an echo signal from a conventional received waveform. 1... Ultrasonic transmission pulse signal, 2-1.2-2.2-3... Ultrasonic echo signal, 3
...Gate signal, 4...Threshold level, IO...Ultrasonic measuring device, 11...Probe, 12
...Reception circuit, 15...Buffer circuit, 16...
Gate circuit, 17...Peak hold circuit, 18...
・Con Valley Evening, 19...Time measurement circuit. Patent issuer 11 Ritsukenki Co., Ltd. agent Patent attorney]: Makoto Kajiyama Patent attorney 7 Tomi [
1” Teruo No. 17 Fig. 3 Fig. 4

Claims (2)

[Claims] (1) In an ultrasonic measurement device that performs a predetermined measurement by generating a transmission pulse at a constant cycle, receiving an echo from an object to be measured, and measuring the time until the echo, the received signal of the echo or The maximum value of the signal corresponding to this is held by a time-attenuated holding circuit, and the maximum value of the received signal of the subsequent echo or the signal corresponding thereto is compared with the held value of the holding circuit, and the difference is output. An ultrasonic measuring device characterized in that time measurement is ended by. (2) The time decay type holding circuit is a peak hold circuit, and the received signal of the subsequent echo is the received signal of the next cycle of echoes, and the held value of the peak hold circuit and the received signal of the next echo or 2. The ultrasonic measurement device according to claim 1, wherein the comparison of the maximum values of the corresponding signals is performed by a comparator, and the measurement operation of the time measurement circuit is stopped by the output of the comparator.