JP2720191B2 - Transmission pulse generation circuit of ultrasonic measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission pulse generation circuit of an ultrasonic measuring device, and more particularly, to a transmission pulse generation circuit for an ultrasonic flaw detector, wherein the frequency of a control pulse applied from the outside is generated. Even if the transmission frequency is higher than the maximum frequency set in the circuit, the transmission pulse applied to the ultrasonic probe (hereinafter referred to as a probe) can generate a transmission pulse of a specified voltage. The present invention relates to improvement of a pulse generation circuit.

[Prior art] Ultrasonic measuring devices are used for various tests on parts, such as various materials, defect inspection of mechanical parts, defect inspection of electronic parts, and state inspection such as mutual comparison of similar parts. It's being used.

This type of ultrasonic measuring apparatus is provided with an XYZ scanning device that scans an object within X, Y, and Z coordinates, performs a C scan of the internal state of the object or a change thereof, and reflects the reflected wave from the object. Is received as an echo reception signal, processed by a computer, and an image such as a C-scope image is displayed and observed or data processing is performed to perform a predetermined inspection.

The configuration of such an ultrasonic measuring device includes a pulser / receiver that generates a transmission / reception signal, a probe that receives a transmission signal from the pulser / receiver, and an object (inspected object) received by the probe. Amplified echo received signal is amplified by the pulsar receiver, and the amplified echo received signal is directly A / D
A gate and peak detector for converting and inputting to a computer for image processing or gating an echo reception signal to detect a peak value, a waveform monitoring device for monitoring a waveform, and a gate / peak detector , An A / D converter that converts the peak value sampled and held into a digital value, an image processing device having a monitor TV, and the like.

In this type of ultrasonic measurement device, generally, after transmitting a transmission wave, a reflected wave of the pulse is received and processed, and then,
Transmit the next transmission wave. It is a predetermined period (measurement period)
The measurement is performed by intermittently transmitting ultrasonic waves. In this case, the transmission wave applied to the probe is a pulse with a large energy, and in order to generate the pulse repeatedly, the transmission pulse generation circuit charges the capacitor with high-voltage power and charges the capacitor during transmission. Is discharged at a time to generate a high-voltage transmission pulse.

[Problem to be Solved] However, when the repetition period (measurement period) is shortened, the repetition of the transmission wave is accelerated, so that the transmission pulse generation circuit must charge and discharge the capacitor at high speed. Therefore, there arises a problem that the charging of the capacitor cannot keep up, and a large-capacity power supply for generating a high voltage is required.

Usually, the repetition period of the transmission pulse is also related to the time for receiving the echo reception signal required for the measurement, and can be adjusted according to the subject and the measurement content. In many cases, it can be controlled by setting from an external computer or the like connected to the ultrasonic flaw detector.

In a transmission pulse generation circuit that generates a transmission pulse according to an external control clock, the maximum repetition frequency (minimum period of generation of the transmission pulse) and a trigger signal corresponding to a clock signal for controlling the same on the computer side A shift occurs, and the transmission pulse generation circuit is triggered at a repetition higher than the maximum repetition frequency. Therefore, there is a disadvantage that a transmission pulse of a specified voltage is not applied to the probe, and as a result, there is a high possibility that an error in measurement data occurs.

The present invention solves such a problem of the prior art, and transmits a specified voltage even when the frequency of an external control clock is higher than the maximum frequency set in a transmission pulse generating circuit. An object of the present invention is to provide a transmission pulse generation circuit of an ultrasonic measurement device capable of generating a pulse.

[Means for Solving the Problems] The transmission pulse generation circuit of the present invention is characterized in that a pulse is generated by charging a capacitor and discharging the charged charge in response to an external trigger signal. A trigger circuit that generates a trigger signal in response to an external control signal and generates a trigger signal of a lower frequency when the control signal input is higher than a set frequency. It is provided.

[Operation] In the case where the pulse generation circuit is driven by receiving a control signal such as an external clock and generating a trigger signal in response thereto, as described above, when the input of the control signal is higher than the specified maximum frequency, By providing a control signal generation circuit that generates a trigger signal at a lower frequency, even if the external control signal has a higher frequency than the specified frequency, the transmission pulse that generates the transmission pulse from the generation circuit can be controlled by the specified signal. Since the cycle becomes longer than the minimum repetition cycle, the pulse generation circuit can sufficiently charge the capacitor with electric charge, and thereafter discharge the pulse to generate a transmission pulse.

As a result, the voltage of the generated transmission pulse does not drop below the specified value even if a control signal having a frequency higher than the specified maximum frequency is externally received. Therefore, a stable specified output can be obtained, and accurate ultrasonic measurement can be performed.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram mainly showing a transmission pulse generating circuit of the ultrasonic measuring apparatus of the present invention, FIG. 2 is an explanatory diagram of a specific example of the clock limiting circuit, and FIG. FIG. 4 is an explanatory diagram of a limiting circuit, and FIG. 4 is an explanatory diagram of a specific example of another clock limiting circuit.

In FIG. 1, 1 is a clock limiting circuit,
A control signal having a frequency corresponding to a transmission pulse to be transmitted to the probe is received as an external clock from an external device such as a computer. Reference numeral 6 denotes an input terminal for receiving the external clock, and the clock limiting circuit 1 operates in response to receiving the external clock at the input terminal 6, and outputs an external clock having a frequency higher than the maximum repetition frequency of the transmission pulse. When received, the display circuit 11 displays an indication to that effect, for example, an alarm display indicating that the external clock is abnormal, and indicates that the measurement is being performed at a longer cycle (lower frequency) than the cycle of the clock. . Therefore, when the frequency of the external clock is higher than the maximum repetition frequency of the transmission pulse, it is intermittently synchronized with the external clock,
Further, a trigger pulse having a frequency lower than the maximum frequency is generated and transmitted to the switching circuit 4.

Reference numeral 2 denotes a clock generation circuit which generates a trigger pulse having a period corresponding to the control signal from the repetition period setting device 3 and sends it to the switching circuit 4. In addition,
The repetition cycle setter 3 generates the above-mentioned control signal in response to an external operation or an external control signal, and the settable repetition cycle is a pulse for generating a transmission pulse to be described later with respect to the clock generation circuit 2. The minimum repetition period (specified maximum frequency) or a longer repetition period (frequency lower than the specified maximum frequency), which is determined by the specification of the generation circuit 5 and holds a voltage at which a voltage can be guaranteed as a transmission pulse, is maintained. Thus, it is possible to variably set in this range.

The switching circuit 4 is a selection circuit for selecting an internal trigger and an external trigger controlled by an external clock.
The switching is performed in response to a control signal input to.
Then, either one of the trigger pulse from the clock limiting circuit 1 as an external trigger and the trigger pulse from the clock generating circuit 2 as an internal trigger is selected and applied to the transmission pulse generating circuit 5.

The transmission pulse generation circuit 5 has a capacitor for charging high-voltage power therein, generates a transmission pulse by discharging the charged capacitor in response to the trigger pulse, and outputs the transmission pulse to an output terminal. Output from 7 and added to the probe. Here, when the selection circuit 4 is switched to an external trigger (external clock side) to receive an external control signal, the clock limiting circuit 1 generates a pulse from an external clock received from an external control device such as a computer. Even if the clock pulse is higher than the maximum frequency (minimum repetition period) set in the circuit 5 and the frequency of the trigger pulse is lower than the maximum frequency, the transmission pulse generated from the pulse generation circuit 5 is the maximum. It can be generated below the frequency. Therefore, the transmission pulse actually applied to the probe is a prescribed high-voltage pulse.

Here, the clock limiting circuit 1 is composed of, for example, a waveform shaping circuit 8 and one-shot circuits (mono-multivibrators) 9 and 10 as shown in FIG. First, the signal is input to the waveform shaping circuit 8 and the waveform and the distortion due to the connection cable and the like are removed and the waveform is shaped. The external clock whose waveform has been shaped is next input as a trigger pulse to the one-shot circuit 9 and the one-shot circuit 10, and is used as each trigger pulse.

One-shot circuit 9 outputs a pulse having a pulse width corresponding to a time constant determined by the resistor R ₁ and capacitor C ₁ in response to a trigger pulse from the waveform shaping circuit 8 to the output terminal 12. Further, the Q output (for example, HIGH level (hereinafter, “H”)) of the one-shot circuit 9 is fed back to the A terminal, and the output of the one-shot circuit 9 is changed until the A terminal becomes LOW level (hereinafter, “L”). Does not respond to B terminal input signal. Therefore, even if the next input signal is input until the Q output drops (becomes "L"), it does not respond to it. Therefore, the Q output does not occur.

Here, the pulse width of the pulse generated by the one-shot circuit 9 is set to be substantially equal to or slightly longer than the maximum repetition period. Therefore, when the period of the external clock input to the input terminal 6 is longer than this pulse width, when one pulse is input, the one-shot circuit 9 synchronizes with the output of the pulse and outputs the Q output (“H”).
Occurs, and after the output is completed, the next external clock is accepted and the next Q output is generated accordingly.

In other words, when the period of the external clock is longer than the maximum repetition period, the output of the one-shot circuit 9 has a frequency (or repetition period) corresponding to the external clock although the pulse width is different from that of the external clock. Therefore, by adding this to the pulse generation circuit 5 as a trigger signal,
Using the rise (or fall) of the one-shot circuit 9 as a trigger, the pulse generation circuit 5 can synchronize with an external clock and generate a transmission pulse of a corresponding cycle.

On the other hand, when the period of the external clock input to the input terminal 6 is shorter than the pulse width of the one-shot circuit 9, one pulse is input and the Q output of the one-shot circuit 9 is generated correspondingly. Even if the next pulse is input, there is no change in the Q output of the one-shot circuit 9 and it is ignored. Therefore, when the next external clock is input, the next trigger pulse to the pulse generation circuit 5 is not applied. The next trigger pulse applied to the pulse generation circuit 5 corresponds to an external clock applied after the Q output of the one-shot circuit 9 has dropped. As a result, even if the cycle of the external clock is shortened, the trigger pulse has a cycle longer than the cycle determined by the pulse width of the one-shot circuit 9 at the maximum.

In other words, even if the external clock is input at a period substantially equal to or shorter than the maximum repetition period, the one-shot circuit 9 outputs an output pulse having a period longer than the maximum repetition period to every other external clock, for example, every other clock. , And the pulse generation circuit 5 is triggered in that cycle. Therefore, the pulse generation circuit 5 generates a transmission pulse having a cycle longer than the maximum repetition cycle. As a result, the charge / discharge capacitor of the pulse generation circuit 5 performs an operation of discharging after charging is completely performed.

Now, the one-shot circuit 10, in response to a trigger pulse from the waveform shaping circuit 8, and outputs a pulse having a pulse width corresponding to a time constant determined by the resistor R ₂ and capacitor C ₂ to the display circuit 11. The pulse width of the one-shot circuit 10 is set equal to or longer than that of the one-shot circuit 9. This circuit drives the display circuit 11 by detecting when the external clock input to the input terminal 6 has a frequency equal to or higher than the specified maximum frequency of the pulse generation circuit 5 (a period shorter than the maximum repetition period). As a result, the display circuit 11 indicates that the generation of the transmission pulse and the external clock for controlling the repetition period are shorter than the maximum repetition period, and issues an alarm indicating that the external clock is abnormal.

By the way, the Q output (“H”) of the one-shot circuit 9 is input to the enable terminal (E) of the one-shot circuit 10. Therefore, the operation of the one-shot circuit 10 is stopped while the Q output (“H”) of the one-shot circuit 9 is not generated. Therefore, when an external clock having a frequency higher than the maximum frequency is generated, the Q of the one-shot circuit 9 is
An output (“H”) is generated, and at that time, when the next clock of the first clock of the external clock having a frequency equal to or higher than the maximum frequency is input to the input terminal B of the one-shot circuit 10, Q output (detection output, “H”) is generated. The generation of this output detects that the external clock has a frequency higher than the maximum frequency. Then, this detection output is supplied to the display circuit 11.

Therefore, the resistor R ₂ and the capacitor C _{2 of} the one-shot circuit 10
By increasing the pulse width corresponding to the time constant determined by
D and the like can be turned on. In this case, this lighting is an intermittent display in which when the external clock has a frequency higher than or equal to the maximum frequency, it blinks at a cycle of an integral number of the frequency. Therefore, the pulse width may be further increased in order to make the lamp light continuously.

In this way, the transmission pulse generation circuit can be externally controlled with peace of mind even if the transmission pulse generation circuit is externally driven by a clock near the maximum frequency, and the measurement data can also be controlled. No more errors.

Also, when the frequency of the trigger pulse input from the outside may exceed the specified maximum frequency, it is displayed on the display circuit 11, which makes it easy to take countermeasures for the measurement and eliminates the inclusion of erroneous measurement data. Can be.
In particular, when the display is on, the operator indicates that the transmitted pulse has a frequency lower than the frequency of the external clock, for example, 1 /
It can be seen that measurements are made at frequencies below 2. In addition, when the external clock has a frequency lower than the maximum frequency, a transmission pulse having a frequency corresponding to the external clock is generated in synchronism with the external clock, and the measurement is performed accordingly.

FIG. 3 shows the one-shot circuit 10 and the display circuit 11 of FIG.
As retrigger be one obtained by inserting a trouble one-shot circuit 13, the resistor R ₃ and capacitor C ₃ and a pulse for driving the display circuit 11 the pulse of a pulse width corresponding to a time constant determined by the between the Send out. In this case, if the pulse width of the retrigable one-shot circuit 13 is set to be at least twice the period of the specified maximum frequency, the LEDs of the display circuit 11 can be continuously turned on.

FIG. 4 shows a case where a JK flip-flop 14 is used in place of the one-shot circuit 10 of FIG. 2. When a Q output is generated in the one-shot circuit 10, it is input to the J terminal side. The output is input to the K terminal side, so that the JK flip-flop 14 performs the same operation as the one-shot circuit 10 in FIG. Therefore, the Q output is a detection signal indicating that an external clock having a frequency equal to or higher than the specified maximum frequency is input.

As described above, the configuration of the clock limiting circuit in the embodiment is merely an example, and this circuit can be easily realized with a different configuration by combining various logic circuits or pulse circuits.

[Effects of the Invention] As can be understood from the above description, according to the present invention, when the input of an externally applied control signal is higher than a specified maximum frequency, a control signal that generates a trigger signal at a lower frequency than the specified maximum frequency By providing the generation circuit, even if the external control signal has a higher frequency than the specified frequency, the transmission pulse generated from the transmission pulse generation circuit has a period longer than the specified minimum repetition period, and the pulse generation circuit The capacitor can be charged sufficiently, and then discharged to generate a transmission pulse.

As a result, the voltage of the generated transmission pulse does not drop below the specified value even if a control signal having a frequency higher than the specified maximum frequency is externally received. Therefore, a stable specified output can be obtained, and accurate ultrasonic measurement can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram mainly showing a transmission pulse generating circuit of the ultrasonic measuring apparatus of the present invention, FIG. 2 is an explanatory diagram of a specific example of the clock limiting circuit, and FIG. 3 is another clock limiting circuit. FIG. 4 is an explanatory diagram of a specific example of still another clock limiting circuit. 1 clock limiting circuit, 2 clock generating circuit, 3 repetition cycle setting circuit, 4 switching circuit, 5 pulse generating circuit.

Claims (1)

(57) [Claims] In an ultrasonic measuring apparatus for measuring a subject by applying a transmission pulse to an ultrasonic probe at a predetermined period, an electric charge is charged to a capacitor, and the charged electric charge is responded to an external trigger signal. And a pulse generating circuit that generates the transmission pulse by discharging, and receives the control signal from the outside, generates the trigger signal in response thereto, and when the input of the control signal is higher than a set frequency, And a trigger signal generating circuit for generating the trigger signal having a low frequency.