JPS63145957A - Transmission circuit in ultrasonic apparatus - Google Patents

Abstract

PURPOSE:To form a good ultrasonic beam, by providing a means for short- circuiting a nonselection vibrator at the time of transmission or reception. CONSTITUTION:A driver circuit 10 is provided with respect to a vibrator 20 one at a time and a P-N push/pull circuit is composed of P-channel MOSFET Q1 and N-channel MOSFET Q2 to output a drive pulse. The pulse width Pw of said pulse is set to 1/2 f0 with respect to the center frequency f0 of the vibrator. FET Q1 is turned ON at a time t1 to supply a current to load. Next, FET Q1 is turned OFF at a time t2 to turn FET Q2 ON. When FET Q2 is turned ON, FET Q2 performs a so-called sink operation drawing a current from the load. When this ON-state continues, a receiving signal is allowed to pass to be guided to an amplifier 30. Herein, when the vibrator 20 does not participate in transmission, voltage is generated at an E-point by electrical and mechanical coupling. Then, FET Q2 is brought to an ON-state until a predetermined time and the vibrator 20 is earthed through a diode D1 to suppress effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wave transmitting circuit for an ultrasonic diagnostic apparatus, and particularly to a wave transmitting circuit suitable for reducing cross rake between transducers.

[Conventional technology]

Conventional driver circuits are disclosed in Japanese Utility Model Application No. 58-48214,
As described in Japanese Patent Application Laid-open No. 58-86149, a capacitor is charged and a bipolar transistor or M
The configuration was such that high voltage pulses were applied by switching O8L'ET. Furthermore, in order to ground the vibrator, it was necessary to provide a dedicated switch as described in Japanese Utility Model Application No. 58-89006.

[Problems to be Solved by the Invention] Regarding the driver circuit of the prior art described above, when the vibrators are arranged in one-to-one pair 6, 1. AO8FET Alternatively, when a bipolar transistor is turned on, a voltage is applied to the resonator, and a pass-through current flows through the high-voltage power supply and switch, making it impossible and rare to ground the resonator without driving it. . In addition, if a drive circuit is provided for each block and the vibrator is selectively driven via a switch, Dryno (the output is connected to multiple vibrators through multiple switches), and only one of the switches In order to ground other vibrators, a grounding switch was required between the switch and the vibrator.The present invention provides a driver circuit that has the function of grounding the vibrator. There is a particular thing.

[Means for solving problems]

The above purpose is a P-N push-pull circuit or NMOS
This is achieved by using a driver circuit having an output stage of a totem pole type circuit, providing one-to-one correspondence with the vibrators, and controlling the vibrators so that both ends of the unselected vibrators are short-circuited when not selected.

[Effect]

The driver circuit in the output stage of a push-pull or totem drilling machine can separately provide a pulse that activates the source transistor that supplies current to the oscillator and a pulse that activates the sink transistor that extracts the υ expression from the oscillator.

Therefore, by applying only a pulse that operates the sink transistor, it is possible to short-circuit the vibrator without driving it.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to one drawing.

FIG. 1 shows a push-pull configuration driver circuit showing one embodiment of the present invention. One driver circuit 10 is provided for each vibrator 20, and also has a diameter selection switch function. VH is a high voltage power source that drives the vibrator and generates ultrasonic waves. p channel MO8FE
T Ql, Nf Jannel MO8F'ET Q, Yo!
1) Construct a P-N push-pull circuit and output the drive pulse shown in FIG. 2E. This pulse width Pw is given by i/zfo with respect to the center frequency f of the vibrator. Second
The operation will be explained along with the time chart shown in the figure. time【
1, transistor Q1 turns on and supplies current to the load.
At 6o t2, transistor Qt is turned off and IQl is turned on. When Ql is turned on, a so-called /link operation is performed, which sucks the current υ' from the load.

If the off state continues, the received signal passes through and the amplifier 30
lead to. D! is the high voltage protection of the amplifier.

Here, when the vibrator 20 is not involved in wave transmission, the force t
3, when other vibrators are driven as shown by the dotted line, a voltage as shown by the dotted line is generated at point 98 due to electrical and mechanical coupling. Therefore, the effect is suppressed by turning on the transistor Q2 up to 14 times and grounding the vibrator 2° via the diode Dl. In this example.

On-resistance of transistor Q2 and diode potential Vb*
*Alternatively, the voltage due to resistor R1 remains. Further, when not involved in reception after t4, transistor Q2 is turned off. Also, if the other transducers are driven at t5 and the transducer 2o is not involved in wave transmission/reception, then s t5 to t6
By turning on transistor Q during this period, crosstalk is suppressed.

FIG. 3 shows an embodiment in which the output stage is a totem pole type push-pull circuit using an N-channel Mos transistor. The difference from FIG. 1 is that the pull-down circuit is performed by transistors Q2 and Q4 (or only Ql), and reception is performed by transistor Q2. The multiple operations will be explained with reference to the time chart in FIG. When driving the vibrator 2o, the transistor Q! , Qs is turned on to supply current to the load. When performing a pull-down operation at t2, transistors Q2 and Q4 are turned on, or only Q4 is used. When receiving the signal, the transistor Q2 is turned on and the signal is input to the amplifier 3o. During this time, the transistor Q4 may be on or off because the diode D2 prevents the received signal from flowing into Q4. Also, a field piece in which the vibrator 20 does not participate in wave transmission and reception will be explained. When another vibrator is driven at time t4, the voltage of the vibrator can be suppressed to below Vbe of the diode D2 by turning on the transistor Q4.

FIG. 4 shows the Vb of the diode in the three embodiments.
This is an example in which e is removed. As shown in the figure, a +4OS switch Q5 is included to directly ground the vibrator. This operation will be explained using a gs diagram.

During wave transmission, the transistor Q5 may be turned on for a period of time that does not affect wave reception to assist in the pull-down operation, or may be turned off if its capability is sufficient. Vibrator 2
0 is not involved in wave transmission/reception, the transducer is kept in the grounded state by turning it on from t5, thereby suppressing crosstalk.

〔Effect of the invention〕

According to the present invention, all the vibrators other than the vibrators constituting the mouthpiece can be short-circuited via the MOSFET switch.

Therefore, it is possible to reduce the instantaneous acoustic influence on adjacent transducers that conventionally occurs, and it is possible to form an extremely good ultrasonic beam.

Furthermore, it is possible to achieve the above function without using a new switching element, and there is a practical effect.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an embodiment of the present invention.
1, FIGS. 3 and 4 are circuit diagrams showing other embodiments of the present invention, and FIGS. 5 and 6 are the timing charts of FIGS. 3 and 4, respectively. It is a timing chart of an example. 10... Driver circuit, 20... Vibrator, 30...
・Prefix / Mousse 2 Diagram B tF On Off
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Claims (1)

[Claims] 1. A group of ultrasonic transducers arranged in plurality, a wave transmitting unit provided with a wave transmitting circuit for each transducer to select and drive any adjacent plurality of transducers in the group of ultrasonic transducers, and the above selection. An ultrasonic wave transmitting/receiving circuit of an ultrasonic device comprising a receiving section for amplifying a signal received by a selected transducer, characterized in that the ultrasonic device is provided with means for short-circuiting non-selected transducers during wave transmission or reception. Transmission circuit in the device.