JPH0116060Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a device in which a large number of ultrasonic transducers (vibration elements) are arranged in parallel, and linear electronic scanning is performed by sequentially switching the analog switches of each of them. The present invention relates to a switching circuit for an ultrasonic transducer that prevents unnecessary echo signals from generating noise on the receiver circuit side.

Conventional ultrasonic linear electronic scanning methods include the method shown in FIG. 1 and the method shown in FIG.

What is shown in FIG. 1 is that when there are n transducers 1 ₁ , 1 ₂ . . . 1 _o , an independent pulse generation circuit 2 ₁ , _{2 2} . ₁ , 3 ₂ ... 3 _o , and a switch 4 ₁ , 4 ₂ ... 4 _o provided on the output side of these receiver circuits 3 ₁ , 3 ₂ ... 3 _o is connected to a sequence control circuit 5
This is a method of switching control. The method shown in FIG. 1 has the disadvantage that the circuit configuration is complicated and expensive because it includes pulse generation circuits and receiver circuits corresponding to the number of elements in the transducer.

However, if _{the sensitivity} of the transducer is sufficiently high, as _shown in FIG. There is also a method of direct _switching using analog switches 4 ₁ , 4 ₂ . It has the characteristic of being able to

However, even in the circuit method shown in FIG. 2, since an analog switch is used for switching the transducer, the switching operation of the analog switch has an adverse effect on the transducer. More specifically, for example, if the analog switch ₄₃ is turned on at a certain time, pulse input power as shown in FIG. 4a from the pulse generation circuit 2 is applied to one contact A of the switch ₄₃ , and the other The waveform of contact B is shown in Figure 4b.
As shown in FIG. 4, although there are some disturbances such as at point P due to the influence of on-state, both the excite pulse signal Q and the echo signal R are the same as in FIG. 4a. However, if, for example, the analog switch ₄₆ is turned off at the same time, one contact C is the same as the contact A, but the other contact D has a waveform as shown in FIG. 4c. Then, the electrical shock wave S generated when the switch is turned off excites the transducer, thereby emitting an acoustic wave and returning an echo signal T from the object to be inspected. This echo signal T
Although it is an unnecessary signal, it enters the receiver circuit 3 in the operating state as noise through the ground wire, power line, acoustic coupling between the transducer, re-radiation of acoustic waves by the transducer, etc. This has the drawback of deteriorating the S/N ratio of the necessary echo signal. In addition, in FIGS. 1 and 2, 6 is a reference signal (clock) oscillator, and 7 is a reference signal (clock) oscillator.
₁ , 7 ₂ ... 7 _o is a variable delay circuit, 8 is an addition circuit,
9 is a CRT monitor.

This invention was made to improve the above-mentioned drawbacks.Among analog switches that switch a transducer, for those that switch from on to off, the transducer side of the analog switch The contact is connected to ground using a short-circuit switch. With this configuration, it is possible to suppress the excitement of the transducer due to the electrical shock wave when the switch is turned off, prevent the generation of unnecessary echo signals, and prevent noise from entering the receiver circuit. .

An embodiment of the present invention will be described below with reference to FIG. Note that the same parts as in FIGS. 1 and 2 are given the same reference numerals. In FIG. 3, reference numeral 6 denotes a reference signal (clock) oscillator, and this oscillator 6 is coupled to the sequence control circuit 5. This sequence control circuit 5 is connected to a receiver circuit 3 and a CRT monitor 9 via a pulse generation circuit 2 that generates an exciting pulse. The output side of the pulse generating circuit 2 is connected to one contact 10 ₁ , 10 ₂ . . . 10 _{o of} analog switches 4 ₁ , 4 ₂ . Ultrasonic transducers _{1 1} , 1 ₂ ... 1 _o are coupled to 11 1 , 11 ₂ ... 11 _o via variable delay circuits _{7 1} , 7 ₂ ... 7 _o , respectively. The other ends of users 1 ₁ , 1 ₂ . . . 1 _o are grounded. Furthermore, the analog switch 4 ₁ ,
The other contacts 11 ₁ , 11 ₂ ... 11 _o of 4 ₂ ... 4 _o are further provided with short-circuit switches 12 ₁ , 12 ₂ ... 12 _o
One contact point 13 ₁ , 13 ₂ ... 13 _o is connected,
The other contacts 14 ₁ , 14 ₂ . . . 14 _o are grounded. The analog switches 4 ₁ , 4 ₂ . . .
...4 _o , short circuit switches 12 ₁ , 12 ₂ ... 12 _o , and variable delay circuits 7 ₁ , 7 ₂ ... 7 _o are coupled to the sequence control circuit 5 to be switched and controlled for scanning. ing.

Next, the effect of the above circuit configuration will be explained.

When the sequence control circuit 5 outputs an excitement pulse control signal based on the clock signal from the oscillator 6, the pulse generation circuit 2 generates an excitement pulse at predetermined intervals. At the same time, a switch switching signal and a delay control signal are output from the sequence control circuit 5, and a plurality of transducers 1 ₁ , 1 ₂ . . . 1 _o and delay circuits 7 ₁ , 7 _{2 .} It is sequentially switched at predetermined time intervals. For more details, see analog switch 4 ₁ , 4 ₂
...4 _o , for example, 1st to 8th, 2nd to 9th,
If the 8 transducers are made into a group and shifted one by one, such as 3rd to 10th, etc., the scanning lines will be the same as the mounting pitch of transducers 1 ₁ , 1 ₂ . . . 1 _o , Also, 1st to 8th, 1st to 9th, 2nd to 9th, 2nd to 10th, etc.
If you switch, the pitch will be 1/2. These switchings are determined as appropriate depending on the pitch of the transducer and the purpose of use. In addition, a short circuit switch 12 ₁ ,
12 ₂ ...12 _o are analog switches 4 ₁ , 4 ₂ ...
…4 Opening and closing are controlled in the opposite direction to _o . Furthermore, the delay circuits 7 ₁ , 7 ₂ . . . 7 _o are controlled so that the beams are focused on the part of the subject.

Here, assuming that the analog switch ₄₃ is closed, the excite pulse from the pulse generation circuit 2 passes through the analog switch ₄₃ and the delay circuit ₇₃ , vibrates the transducer ₁₃ , and emits an ultrasonic beam. . The same transducer ₁₃ receives the echo from the part of the subject again, reverses it and sends it to the receiver circuit 3, where it is sent to the CRT monitor 9.
to be displayed. At this time, the waveforms at the contacts 10 ₃ and 11 ₃ of the analog switch 4 ₃ are as shown in FIGS. 4a and 4b.

On the other hand, an open analog switch e.g. 4 ₁
If you look at the corresponding short-circuit switch 1
2 ₁ is closed and transducer 1 ₁ is delay circuit 7 ₁
is grounded through. Therefore, the electric shock S as shown in FIG. 4C when this analog switch 4 ₁ is opened is absorbed by the ground, and the ground side contact 11 ₁ of this short circuit switch 4 ₁ receives an electric shock as shown in FIG. There is only a slight shock wave U, and this shock wave U
In some cases, the transducer will not be excited and will not output an echo signal.

In addition, in Fig. 4, the vertical axis of a and b is 10V/
The vertical axis of cm, c, d is 0.5V/cm, and the horizontal axis is a, b,
Both c and d are 0.5 μs/cm.

As mentioned above, in this invention, when a transducer is off, the transducer is short-circuited to ground using a short-circuit switch. The generation of noise can be prevented. Therefore, an excellent effect is obtained in that noise is not generated on the receiver circuit side through the ground wire, the power supply wire, the acoustic coupling between the transducers, etc.

[Brief explanation of drawings]

1 and 2 are block diagrams showing the switching circuit of a conventional ultrasonic transducer, FIG. 3 is a block diagram showing an embodiment of the switching circuit of the ultrasonic transducer according to the present invention, and FIG. Figures a, b, c, and d are output waveform diagrams of each part. 1 ₁ ~ 1 _o ... Ultrasonic transducer, 2,2
₁ ~ 2 _o ... Pulse generation circuit, 3, 3 ₁ ~ 3 _o ... Receiver circuit, 4 ₁ ~ 4 _o ... Analog switch, 5
... Sequence control circuit, 6 ... Reference signal generation circuit, 7 ₁ - 7 _o ... Variable delay circuit, 8 ... Addition circuit, 9 ... CRT monitor, 10 ₁ - 10 _o , 11 ₁ -
11 _o ... contact, 12 ₁ - 12 _o ... short circuit switch, 13 ₁ - 13 _o , 14 ₁ - 14 _o ... contact.

Claims (1)

[Claims for Utility Model Registration] (1) Each of a plurality of ultrasonic transducers is coupled to the same pulse generation circuit and receiver circuit via a corresponding analog switch, and the analog switch is sequentially switched to A short circuit in which one end of the ultrasonic transducer is connected to a contact on the ultrasonic transducer side of the analog switch and the other end is grounded. and a switch for
An ultrasonic transducer comprising: a sequence control circuit that opens a corresponding short-circuit switch when the analog switch is closed, and closes a corresponding short-circuit switch when the analog switch is opened. switching circuit. (2) The ultrasonic transformer according to claim 1, wherein the sequence control circuit controls an analog switch and a shorting switch so that a plurality of ultrasonic transducers are simultaneously driven as one group. Jusa switching circuit. (3) A switching circuit for an ultrasonic transducer according to claim 1 or 2, which comprises a variable delay circuit inserted between an analog switch and a corresponding ultrasonic transducer.