JPS6367150B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a device in which a large number of ultrasonic transducers (vibration elements) are arranged in parallel and a linear electronic scan is performed by sequentially switching the analog switches of each of them. ,
By appropriately setting the relationship between the transducer's excitement timing and the analog switch's turn-on timing, the sensitivity of the pulse echo signal can be increased and the electrical shock when the analog switch is turned on can be minimized. This invention relates to an exciting method for an ultrasonic transducer.

In general, in the ultrasonic linear electronic scanning method, if the sensitivity of the transducer is sufficiently high, one pulse generator circuit 2 and one receiver circuit 3 are used as shown in FIG.
There is a method of directly switching ₁ , ₁₂ ... _1o using analog switches ₄₁ , ₄₂ ... _4o . This method has a feature that the circuit configuration is very simple and can be realized at low cost. _However , in this conventional circuit method, as shown in characteristics _{A and B} in _{FIG .} Because the excitement timing was at the same time,
The excite waveform attempts to pass through the analog switches 4 ₁ , 4 ₂ ... 4 _o before the analog switches 4 ₁ , 4 _{2 ,} ... 4 _o completely rise, that is, before they reach a completely saturated state. Therefore, there is a drawback that the sensitivity D of the echo signal is lowered, as shown in characteristic C in FIG. 3b.

In FIG. 1, 5 is a reference signal (clock) oscillator, 6 is a sequence control circuit, 7 ₁ ,
7 ₂ ...7 _o is a variable delay circuit, and 8 is a CRT monitor.

The present invention has been made to improve the above-mentioned drawbacks, and is designed to delay the excitation timing of the transducer slightly, specifically by about 50 to 600 nsec, from the timing when the analog switch is turned on. This is what I did. By adopting such a method, it is possible to increase the sensitivity of the pulse echo signal and to minimize the electrical shock wave when the analog switch is turned on.

An embodiment of the present invention will be described below with reference to FIG. Note that the same parts as in FIG. 1 are given the same reference numerals. In Figure 2, 5 is the reference signal (clock)
This oscillator 5 is coupled to a sequence control circuit 6. This sequence control circuit 6
is coupled to a receiver circuit 3 and a CRT monitor 8 via a pulse generating circuit 2 that generates an exciting pulse. Further, on the output side of the pulse generating circuit 2, there are contacts 9 ₁ , 9 ₂ . . . ₉ of analog switches 4 ₁ , 4 ₂ .
_o , and ultrasonic transducers 1 1 , 1 2 _... 1 _o are coupled to the other contacts 10 ₁ , 10 ₂ ... 10 _o via variable delay circuits 7 ₁ , _{7 2 ...} 7 _o , respectively. , these transducers 1 ₁ , 1 ₂ ...1 _o
The other end is grounded. Further, the analog switches 4 ₁ , 4 _{2 .} . . 4 _o and the variable delay circuit 7
₁ , 7 ₂ . . . 7 _o are connected to the sequence control circuit 6 and are controlled to be switched for scanning.

The pulse generation circuit 2 includes a MOSFET 11, resistors 12, 13, 14, a coil 15, and a diode 1.
6, 17 and a capacitor 18,
The gate of the MOSFET 11 is connected to the sequence control circuit 6, the source is grounded, the drain is connected to a high voltage power supply terminal (+E) of about 100V via a resistor 12, and a high voltage charging/discharging capacitor 18. It is connected to the. (+B)
is the bias power supply. Further, a resistor 19 is inserted on the line before the receiver circuit 3, and diodes 20 and 21 connected in parallel in opposite directions are inserted between this line and the ground.

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

Based on the clock signal from the oscillator 5, the sequence control circuit 6 first outputs a switch switching signal and a delay control signal, which are then output to the plurality of transducers 1 ₁ , 1 ₂ . . . 1 _o and delay circuits 7 ₁ , 7 , respectively. ₂ ...7 _o
are sequentially switched at predetermined time intervals as one group. At this time, analog switches 4 ₁ , 4 ₂ ... 4 _o
The rise of is as shown in characteristic E in FIG. 4a.

After the analog switches 4 ₁ , 4 _{2 .} . . 4 _o are turned on, an excite pulse control signal is output from the sequence control circuit 6 with a slight time delay.
Input to the gate of MOSFET11. Then, the pulse generating circuit 2 generates an exciting pulse F with a slight time delay, specifically, a time delay of about 50 to 600 nsec, as shown in FIG. 4a.

Note that the analog switches ₄₁ , ₄₂ ... _4o are, for example, 1st to 8th, 2nd to 9th, 3rd to 10th...
If you switch 8 pieces as 1 group like this,
The scanning lines are the same as the mounting pitches of transducers 1 ₁ , 1 ₂ ... 1 _o , and the 1st to 8th, 1st to 8th
9th, 2nd to 9th, 2nd to 10th, etc.
If switched, the pitch will be reduced to 1/2. These switchings are determined as appropriate depending on the pitch of the transducer and the purpose of use. Furthermore, delay circuits 7 ₁ , 7 ₂
...7 _o is controlled so that the beam is focused on the region of the subject.

Here, assuming that the analog switch ₄₃ is closed, the excite pulse F from the pulse generation circuit 2 passes through the analog switch ₄₃ and the delay circuit ₇₃ , vibrates the transducer ₁₃ , and generates an ultrasonic beam. Let it fire. The same transducer ₁₃ receives the echo from the part of the subject again, sends it back to the receiver circuit 3, and displays it on the CRT monitor 9. The pulse echo waveform at this time has a characteristic G shown in FIG. 4b, and it can be seen that the sensitivity H is 1.6 to 2 times higher than that of the echo waveform shown in FIG. 3b.

Note that if the timing of excitation of transducers 1 ₁ , 1 ₂ . . . 1 _o is too late, the fifth
As shown in figures a and b, the analog switch 4 ₁ ,
The electrical shock wave I when 4 ₂ ... 4 _o is turned on causes it to appear as noise just before the original echo output K, as shown at J in Figure 5b. Therefore, it is desirable that the time is not too slow, specifically about 50 to 600 nsec as described above.

As described above, in the present invention, the timing at which the ultrasonic transducer excites is slightly delayed from the timing at which the analog switch is turned on, so that the excite pulse sufficiently vibrates the transducer, and the pulse echo signal is The sensitivity of the analog switch can be increased, and the generation of noise due to electrical shock waves when the analog switch is turned on can be minimized.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the excite circuit of an ultrasonic transducer, Fig. 2 is a specific electric circuit diagram of the excite circuit for explaining the method according to the present invention, and Fig. 3 is a diagram showing how to turn on an analog switch using the conventional method. Figure 4 is a waveform diagram of various parts when the timing of the excited pulse is delayed by the method of the present invention, Figure 5 is when the exciting pulse is delayed excessively. FIG. 1 ₁ to 1 _o ... Ultrasonic transducer, 2... Pulse generation circuit, 3... Receiver circuit, 4 ₁ to 4 _o ... Analog switch, 5... Reference signal oscillator, 6... Sequence control circuit, 7 ₁ to 7 _o ... Variable delay circuit, 8...
CRT monitor, 11...MOSFET.

Claims (1)

[Claims] 1. A plurality of ultrasonic transducers are coupled to the same pulse generation circuit and receiver circuit through corresponding analog switches, and the transducers and analog switches are sequentially switched by a sequence control circuit. A linear scan is performed using the analog switch, and an echo signal is sent to the receiver circuit, wherein the timing at which the transducer is excited is delayed by a predetermined period of time from the timing at which the analog switch is turned on. How to excite a sonic transducer. 2. The method for exciting an ultrasonic transducer according to claim 1, wherein the timing delay for exciting the transducer is 50 to 600 nsec.