JPS6357037A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic diagnostic apparatus, and particularly to a pulser circuit that supplies drive pulses to an ultrasonic transducer.

[Conventional technology]

Generally, in an ultrasonic diagnostic device, an ultrasonic transducer such as a piezoelectric element is brought close to the subject, a high-frequency AC voltage in the MHI band is applied to it for a very short period of time, and the transducer emits pulsed ultrasonic waves. It is radiating.

Here, if the object to be examined is a homogeneous medium, it propagates straight through it, and after a predetermined time, if there is an interface between tissues with different acoustic impedances, some of it will be reflected and some of it will be reflected. To Penetrate. This reflected wave is received by the transducer, and the distance from the transducer to the boundary surface is measured based on the speed of the ultrasonic wave and the ultrasonic pulse that returns back and forth.

In a radial scanning type diagnostic device, the vibrator is rotated within the cross section of the subject. By transmitting and receiving ultrasonic pulses by the transducer 0 times every time the transducer rotates, a scanning line is obtained by dividing a circle centered on the transducer into n equal parts in the angular direction, and thereby an image of the subject can be obtained. It will be done.

[Problems to be Solved by the Invention] Here, conventionally, a probe equipped with an ultrasonic transducer and a reflected ultrasonic signal obtained from the transducer by applying a driving pulse (high frequency AC voltage) to the ultrasonic transducer are used. The electrical circuitry that forms the image is separate from the main unit. Further, the types of ultrasonic molecules differ depending on the subject. For example, there are resonant frequencies, and the optimal pulse width of the driving pulse of the ultrasonic transducer differs depending on the resonant frequency.

However, the electric circuit part can be expensive, and conventionally the same one is used for all probes. For this reason, depending on the type of probe to be connected, it may not be possible to supply a drive pulse with an optimal pulse width to the ultrasonic transducer. Driving the ultrasonic transducer with a drive pulse having a pulse width that does not correspond to the resonance frequency has the disadvantage that vibrations in modes other than thickness imaging also occur.

This invention was made to deal with the above-mentioned circumstances,
The purpose is to provide an ultrasonic diagnostic apparatus that can always drive an ultrasonic transducer with a drive pulse having an optimal pulse width even if the resonance frequencies of the ultrasonic transducer differ.

[Means for solving problems]

The ultrasonic diagnostic apparatus according to the present invention has an ultrasonic transducer 12.1.
Observation equipment that generates driving pulses with periodic intervals of 4 scans @24
, a switch 26 for selecting one of the ultrasonic transducers 12.14, and a pulse width conversion circuit 28 for converting the pulse width of the drive pulse according to the resonance frequency of the ultrasonic transducer 12.14 selected by the switch 26. Equipped with.

[Effect]

According to the ultrasonic diagnosis i'Xa according to the present invention, one of the plurality of ultrasonic transducers 12 and 14 that are integrally scanned and each having a different resonance frequency is selected by the switch 26, and the pulse width of the drive pulse is selected. Ultrasonic transducer 12.14
By converting the pulse according to the resonant frequency of the ultrasonic transducer and then supplying it to the ultrasonic transducer, the ultrasonic perturber can always be driven with a drive pulse having an optimal pulse width even if the resonant frequency of the ultrasonic transducer is different.

〔Example〕

An embodiment of the ultrasonic diagnostic apparatus according to the present invention will be described below with reference to the drawings. Here, instead of changing the ultrasonic transducer by replacing the probe with the ultrasonic transducer,
It is assumed that a plurality of ultrasonic transducers that are integrally scanned are provided in the probe, and that the ultrasonic transducers are electrically switched. This has the advantage that the ultrasonic transducer can be changed depending on the subject without changing the probe each time. Of course, it is also possible to provide a plurality of probe nibs each having an ultrasonic transducer with a different resonance frequency, and to switch the ultrasonic transducer by changing the probe depending on the subject. As an example, inside? JBI! Is it scanned integrally with the tip of the insertion section of the (fiberscope)? ! An ultrasonic endoscope device incorporating several ultrasonic transducers will be described.

FIG. 1 is a schematic diagram showing the configuration of the first embodiment.

Two ultrasonic vibrators (piezoelectric elements) with different resonance frequencies 1
2.14 is fixed to the vibrator fixing member 16. The transducer fixing member 16 is rotated by a motor 18 at an end opposite to the end to which the ultrasound system mover 12.14 is fixed. As a result, the ultrasonic system movers 12 and 14 are rotated integrally. @The moving element fixing member 1G is inserted into the insertion section of the endoscope and radially scans the subject.

Since the ultrasonic transducers 12 and 14 are fixed at different locations in the circumferential direction of the transducer fixing member 16, the ultrasonic transducers 1
2.14 is rotated with a predetermined phase difference (for example, 180°).

A rotary encoder 20 is connected to the motor 18, and the output of the rotary encoder 20 is sent to an encoder control circuit 22.
supplied to The rotary encoder 20 generates pulses periodically as the motor 18 rotates, for example, 256 periodic pulses per rotation. The rotational speed of the motor 18 is controlled by an encoder control circuit 22.

The encoder control circuit 22 generates pulses (512 pulses during one rotation) at the rising and falling edges of the periodic pulse supplied from the rotary encoder 20, and observes these pulses as timing signals for photographing the vibrator. Supplied to device 24. A positioning pulse for determining the writing start position on the screen is also supplied from the encoder control circuit 22 to the observation Vt position 24.

The observation device 24 supplies a timing signal and periodic drive pulses to a pulser circuit 28 via a switch 26 . The switch 26 is manually switched, and the observation V4 position 24
A drive pulse from the pulser circuit 28 is supplied to the pulser circuit 28 via either the first or second output terminal.

The pulser circuit 28 boosts this pulse and sends it to the switch 26.
Depending on which side the ultrasonic transducers 12 and 14 are switched to, the ultrasonic transducers 12 and 14 are supplied.

Ultrasonic pulses transmitted from the ultrasound transducer, reflected at the interface between tissues having different acoustic impedances, and received by the ultrasound transducer again are converted into received signals and input to the observation device 24 via the amplifier 30. be done. Observation device 24
modulates the brightness of the received signal and displays a cross-sectional image of the subject on a monitor.

Here, when the switch 26 is switched, the positioning pulse for writing on the screen is moved by the encoder control circuit 22. As a result, even if the starting position on the monitor screen of the observation device 24 changes and the rotational phase changes due to switching of the ultrasonic transducer, the positional relationship of the subject to the transducer on the monitor will not change. ing.

The pulsar circuit 28 is connected to the observation device 24 via the switch 26.
Before outputting the drive pulses supplied from the ultrasonic transducers 12.14 to the ultrasonic transducers 12.
2. Set the pulse width to suit the resonance frequency of 14.

Therefore, in the first embodiment, C as shown in FIG.
An R differentiator circuit is used. By adjusting the value of the time constant CR, the pulse width of the output pulse you out can be adjusted. That is, a differential circuit having a time constant CR capable of obtaining a pulse width suitable for the resonance frequency of the ultrasonic transducer 12.14 is connected to each ultrasonic transducer 12.14,
The first and second outputs of the switch 30 are respectively supplied to differentiating circuits. That is, by selecting the switch 26, one of the differentiating circuits is selected, and the pulse width of the drive pulse is converted to a pulse width corresponding to the resonance frequency. Actually, the second
As shown in Figure (b), a drive pulse is supplied to the differentiating circuit via the transformer 32.

In this way, by making the pulse width of the drive pulse correspond to the resonance frequency of the ultrasonic transducer, imaging in modes other than the required thickness vibration mode is reduced.

Additionally, in general, it takes time for the voltage of an ultrasonic transducer to subside mechanical vibration (see Figures 4(a) and (b)).
At the resonant frequency (see Figure 3), electrical energy is efficiently converted into mechanical energy, so vibrations are well contained. Therefore, when displaying an image with an observation device, the voltage of the vibrator quickly drops to O, and the potential is 0 by the time the next drive pulse is input, meaning that there is no influence from other pulses, and the Resolution is improved in image display.

As explained above, according to the first embodiment, when the ultrasonic transducer is switched, the pulse width of the drive pulse output from the observation device 24 is changed by switching the time constant of the differential circuit. It can be converted to the optimal drive pulse width corresponding to the resonant frequency, reducing pulse signal loss,
It is possible to improve the image resolution of the observation device, and to drive the ultrasonic transducer efficiently.

Next, another embodiment of the invention will be described. Figure 5 is the second
FIG. 3 is a circuit diagram of a portion of a pulser circuit according to an embodiment. The second embodiment is the same as the first embodiment except for the pulser circuit, so only the pulser circuit will be described.

In the second embodiment, a one-shot multivibrator 50 is used as the pulse width conversion means. The one-shot multivibrator 50 changes the pulse width of the output pulse by changing the resistance value of an external variable resistor R'. This also provides a drive pulse with a pulse width corresponding to the resonance frequency of the ultrasonic transducer, and provides the same effects as in the first embodiment.

FIG. 6 is a circuit diagram of the pulser circuit portion of the third embodiment. In the third embodiment, a plurality of probes each having an ultrasonic wave W1111 having a different resonance frequency are provided,
Assume that the ultrasonic transducer is changed by changing the probe. A drive pulse from the observation device is supplied to the input terminal Vin of the PROM 60. A switch 62 is connected to the PROM 60, and driving pulses are outputted from either output terminal by switching the switch 62. PROM
A plurality of one-shot multivibrators 64 having different time constants are connected to each of the output terminals 60, respectively. The output of the one-shot multivibrator 64 is supplied to the ultrasonic ffl element via an oven collector transistor 66. That is, by switching the switch 62, the drive pulse is converted into a pulse with a different pulse width, so even if the probe is replaced and the resonance frequency of the ultrasonic transducer changes, the one-shot multivibrator 6 can be changed by switching the switch 62.
This can be dealt with by selecting 4. Further, if the signal supplied from the PROM 60 to the one-shot multi-vibration brake 64 is selected from among a plurality of signals using a switch as in the first embodiment, it can be applied to the case where a plurality of vibrators with different resonant frequencies are driven. .

〔Effect of the invention〕

As explained above, according to the present invention, the pulse width of the drive pulse is converted into a pulse width corresponding to the resonant frequency of the ultrasonic transducer and then supplied to the transducer, so the drive efficiency is increased and the signal transmission time is increased. It is possible to provide an ultrasonic transducer with high resolution by reducing pulse signal loss and suppressing mechanical vibration. Note that the present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the spirit thereof. For example, within ultrasound? J! ffl, and the operation of the observation device is not limited in any way.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the outline of a first embodiment of the ultrasonic diagnostic apparatus according to the present invention, FIGS. Figure 3 is a diagram showing the impedance characteristics of a general ultrasound transducer, Figures 4 (a) and (b) are diagrams showing the input/output characteristics of a typical ultrasound transducer, and Figure 5 is a diagram showing the impedance characteristics of a typical ultrasound transducer. FIG. 6 is a diagram showing a one-shot multivibrator used in the pulser circuit of the example, and FIG. 6 is a diagram showing the pulser circuit of the third embodiment. 12.14...Ultrasonic transducer 18...Motor 20...Rotary encoder 22...Encoder control circuit 24...Observation device 28...Pulsar circuit Vout/Vin e-12 Fig. 2

Claims (6)

[Claims] (1) In an ultrasonic diagnostic device comprising an ultrasonic probe and a signal processing circuit that processes reflected signals obtained from the ultrasonic probe, the signal processing circuit generates drive pulses that are periodic to the scanning of the ultrasonic probe. An ultrasonic diagnostic apparatus characterized by comprising means for converting the pulse width of the drive pulse according to a resonance frequency of an ultrasonic transducer in the ultrasonic probe. (2) The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic probe is built into an insertion section of an endoscope. (3) The ultrasonic probe includes a plurality of ultrasonic transducers each having a different resonance frequency, and the pulse width conversion means includes means for selecting one of the plurality of ultrasonic transducers, and a pulse width of the driving pulse. The method is characterized by comprising means for converting the width according to the resonance frequency of the selected ultrasonic transducer, and means for supplying the drive pulse with the converted pulse width to the selected ultrasonic transducer. An ultrasonic diagnostic apparatus according to claim 1. (4) The ultrasonic probe according to claim 3, wherein the ultrasonic probe is built in an insertion section of an endoscope, and the plurality of ultrasonic transducers are integrally radially scanned. Diagnostic equipment. (5) The ultrasonic diagnostic apparatus according to any one of claims 1 to 4, wherein the pulse width conversion means is a differential circuit. (6) The ultrasonic diagnostic apparatus according to any one of claims 1 to 4, wherein the pulse width conversion means is a one-shot multivibrator.