JPS61220591A - Ultrasonic wave probe - Google Patents

Abstract

PURPOSE:To improve the efficiency of transmission/receiving by connecting a resistor in parallel and an inductor in series with the vibrating element of an ultrasonic wave probe that is equipped with a coaxial cable which transfers transmitting/receiving voltage to the vibrating element. CONSTITUTION:When transmitting ultrasonic wave, a vibrating element 1 is driven by an oscillating part 8 through a resistor 7, a diode 6, a coaxial cable 4 and an inductor 2 and also, both ends of the cable are bypassed to the ground through an inductor 5 and a resistor 3. By resonating in parallel the electrostatic capacity of the inductor 5 and the cable 4, a voltage e3 that is applied to the resistor 3 becomes e3 eg.Z3/(Z3+Z7) by an equivalent circuit shown at a figure and works as a constant voltage source against a piezo-electric element 1 and the inductor 2. When receiving, the oscillating part 8 is separated by the diode 6 and, the inductor 5 and the cable 4 resonate in parallel and the resistor 3, the inductor 2 and an oscillator 1 resonate in series against the receiving signal. Thereby, efficient transmission/receiving is realized.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an ultrasound probe (hereinafter simply referred to as a probe) for an ultrasound diagnostic device, and is particularly applicable to ultrasound transmission and reception technology of the probe. It is related to effective technology.

[Background technology]

The transmitter/receiver section of a conventional probe is usually
As described in Japanese Patent No. 82, inductors are connected in parallel in order to compensate for losses due to interelectrode capacitance of the vibrating element, stray capacitance of the coaxial cable, and the like.

Furthermore, it is generally known that the resolution of a probe is determined by the length of the resonant waveform of the vibrator.

For this reason, the longer the resonance continues, the lower the resolution becomes, so the damping resistance is set to one order of magnitude. for that,
There is a problem in that the loss of ultrasonic transmission and reception signals increases and the transmission and reception efficiency decreases.

[Purpose of the invention]

An object of the present invention is to provide a technique that can improve the transmission and reception efficiency of ultrasonic waves in a probe.

The above and other objects and novel features of the present invention will become clear from the description of the present specification and the accompanying drawings.

[Summary of the invention]

In order to achieve the above object [1], the present invention provides a probe equipped with a transducer element and a coaxial cable for transmitting and receiving voltages to the transducer. , and an inductor is connected in series with the vibration terminal f.

[Structure of the invention]

The configuration of the present invention will be explained using examples and drawings.

5b. In all the figures explaining the embodiment, parts having the same functions are denoted by the same reference numerals 1 and 1, and repeated explanations thereof will be omitted.

FIG. 1 shows a schematic configuration of a direct transmission and reception path of a probe according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a vibration element, which transmits and receives ultrasonic waves. 2 is an inductor, and vibration element 1
connected in series. This inductor 2 constitutes a series resonant circuit with the eight views between the electrodes of the vibrating element 1 when transmitting and receiving ultrasonic waves.

3 is a resistor, which is connected in parallel to the vibration element 1 and the inductor 2. This resistor 3 acts on the voltage applied to the vibrating element 1 during ultrasonic transmission 18, and on the magnitude of the received voltage and the magnitude of Q of series resonance during reception. The voltage applied to the vibrating element 1 during ultrasonic transmission is supplied by the oscillator 8 via the coaxial cable 4. 5 is an inductor,
A parallel resonant circuit is configured with the capacitance of the coaxial cable 4, and its resonant frequency is set to the ξ vibration frequency of the vibration element 1. 6 is connected to the diode 1, and is provided to isolate the internal resistor 7 so that it does not become a load on the received signal detection terminal 9 during ultrasonic reception. 7 is an internal resistance of the oscillation section 8, and its value is set sufficiently small.

This causes the oscillation section 8 to operate as a constant voltage source.

Next, the operation of the ultrasonic transmitter/receiver section of the probe of this embodiment will be explained.

FIG. 2 shows the configuration of an equivalent circuit during ultrasonic transmission in this embodiment.

As shown in FIG. 2, the vibrating element 1 can be isometrically replaced by an interelectrode capacitance when a voltage is applied. The coaxial cable has only capacitance and is in a parallel resonance state with inductor 5, so the resistance 3 can be ignored. Therefore, resistance 3
The voltage e3 applied to the voltage e3 can be calculated using the following approximate formula.

[4jmi(le[・73 / (Z:l +z,,) voltage e3 is connected to the series resonance system of piezoelectric element l and inductor 2 and acts as a constant voltage source, and the maximum current is ryed in the resonant state, and its As a result, voltage is applied to the vibrating element l most efficiently.

FIG. 3 shows the configuration of an approximate equivalent circuit for receiving a voltage signal generated by sound pressure in the vibrating element 1 using the inductor 5 as a load. The capacitances of the inductor 5 and the coaxial cable 4 are in a parallel resonance state, and from the perspective of the received signal er, FIG. 3 can be further converted into nlR8 as shown in FIG. 4. In Fig. 4, a series resonant circuit is constituted by a vibrating element l, an inductor 2, and a resistor 3 for the received signals F and r, and the maximum voltage due to the series resonant current can be detected at the isometric measurement position, that is, at the resistor 3. .

That is, the probe has two contradictory functions: it must perform transmission and reception with maximum efficiency, and at the same time it must suppress electrical and mechanical vibrations in the shortest possible time. In this embodiment, series resonance is used to increase efficiency.

In addition, as is clear from the ultrasonic receiving circuit shown in Fig. 4, the resistor 3 acts as a damping resistance of 4-, and the larger the value, the more effective it is. It also affects reception efficiency, so it is better to make it larger.

Furthermore, as is clear from the equivalent circuit during transmission shown in Fig. 2, the larger the resistor 3 is, the better from the point of view of transmission efficiency1.With this configuration, the vibration element 1 can be driven by a series resonance system, and Since it is possible to transmit and receive sound waves, it is possible to use an array type vibrator with a small radiation area, a vibrator with a small dielectric constant such as a lead titanate type vibrator, an organic piezoelectric film, or the like. This makes it possible to improve the efficiency of transmitting and receiving ultrasonic waves from the probe.

The structure of another embodiment in which the principle of the above embodiment is applied to a probe having an array structure is shown in a schematic diagram in FIG.

As shown in FIG. 5, the probe of this embodiment has a plurality of vibrating elements 1 arranged in an array structure, and the same number of inductors 2 as the plurality of vibrating elements 1 are connected in series with the vibrating elements 1. It is something. In order to arrange a large number of the inductors in an array, it is necessary to reduce the size of the inductor 2 in terms of packaging density. Therefore, in this embodiment, the inductor 2 is supported as shown in FIG. Substrate 10. , l2 are arranged in an array structure. Also, the resistor 3 is the inductor 2
are connected in parallel with the inductor 2 between each of them and the coaxial cable 4, and arranged on the resistor mounting board 11-1-. The support substrate 10 of the inductor 2 is a resistor mounting substrate 11 . ``T'' is provided collectively in ``2''.

With this configuration, it is possible to use a probe with an array structure in which a large number of microscopic vibrating elements are arranged at regular intervals, thereby improving the ultrasonic transmission and reception efficiency of the probe. .

Although the present invention has been specifically explained using the above embodiments, the present invention is not limited to the above embodiments, and can be modified in various ways without departing from the gist thereof. Of course.

For example, it goes without saying that the present invention can be applied to probes other than those having an array structure. Furthermore, the arrangement and support positions of the inductor 2 and the resistor 3 are limited to the above embodiments.
Instead, they may be provided anywhere as necessary, as long as the electrical connections that perform the function of the present invention are made.

〔effect〕

As explained above, Jt according to the present invention can transmit and receive by driving the vibrating element with a series resonance system, so it is possible to transmit and receive by driving the vibrating element with a series resonance system. A vibrator with a small dielectric constant, such as an organic piezoelectric film, can be used. Thereby, the efficiency of transmitting and receiving ultrasonic waves of the probe can be improved.

[Brief explanation of the drawing]

FIG. 1 is a general configuration diagram of a transceiver circuit of a probe according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing the configuration of an equivalent circuit when transmitting ultrasonic waves according to this embodiment. is an equivalent circuit diagram of an approximated ultrasonic receiving circuit when receiving a voltage signal generated by sound pressure in the vibrating element of this embodiment with an inductor as a load, and FIG. 4 is an equivalent circuit diagram of the circuit shown in FIG. 3. 1 is a circuit diagram, and FIG. 5 is a schematic drawing showing the configuration of another embodiment in which the principle of the embodiment described above is applied to an IT probe having an array structure. FIG. 6 is an external view of an inductor. 11 dynamic element, 2 - inductor, 3... resistor, 4...
・・Coaxial cable, 5・-inductor, 6・diode-1
~, 7... Internal resistance of the oscillation section, 8... Oscillation section. 9... Reception signal detection terminal, 10... Inductor support board, 11... Resistor mounting board if).

Claims (1)

[Claims] (1) In an ultrasonic probe equipped with a vibrating element and a coaxial cable for transmitting and receiving voltage to the vibrating element, a resistor is connected in parallel with the vibrating element, and an inductor is connected in series with the vibrating element. An ultrasonic probe characterized by: