JPS58206990A - Ultrasonic reflected wave receiving device - Google Patents

Abstract

PURPOSE:To eliminate a noise caused by a multipath reflection, by making a receiving signal branch, giving delay and attenuation, and adding it so as to become antiphase to the receiving signal. CONSTITUTION:A reflected wave which reaches a vibrator of a probe 11 hits against a discontinuous face of acoustic impedance except a target and generates a multipath reflection, therefore, following a reflected wave P0 reflected by the target, reflected waves P1, P2 by the multipath reflection appear. In this case, when an output of a receiving circuit 14 is adjusted suitably by a delaying circuit 22 so that a delayed signal P0' is set so as to appear at the time coinciding with the first multiple reflected wave P1 as shown in B, and also the attenuation quantity of an attenuating circuit 23 is adjusted so that amplitude of the delayed signal P0' is set so as to coincide with amplitude of the first multiple reflected wave P1, an output signal of the attenuating circuit 23 becomes like C. When this output signal is added to negative phase by an adding circuit 15, a desired reflected wave P0 only appears in the output of the adding circuit as shown in D, and unnecessary multiple reflected waves P1, P2... can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to improvements in medical ultrasonic diagnostic devices and other devices for detecting reflected waves of ultrasonic waves. In particular, the present invention relates to a device equipped with a circuit that removes noise caused by multiple reflections.

[Background of the invention]

2. Description of the Related Art Techniques for emitting ultrasonic pulses toward a target object, receiving and analyzing the ultrasonic waves reflected by the target object, and observing the state of the target object have been applied to ultrasonic diagnostic devices and other devices. Figure 1 is a conceptual diagram showing an example of this.
The ultrasonic waves emitted from the body pass through the matching layer 2, pass through the rubber lens 3, and enter the body from the body surface 4. When this ultrasonic wave hits a target object 5 whose acoustic impedance suddenly changes, it is reflected and returns to the transducer 1, where it is converted into an electrical signal and returned.

At this time, between the probe tip 1 and the matching layer 2,
Since there is also an acoustic impedance mismatching surface between the rubber lens 3 and the body surface 4, reflections as shown by the arrows in FIG. 1 occur here as well.

If the reflected wave is reflected by the target object 5 or further reflected by an incongruent surface like this, it becomes noise due to so-called multiple reflections. The horizontal axis shows the time and the vertical axis shows the received signal level.
Pulse P reflected from the VC1 target as shown in K.

is received, the vt pulse P1 due to multiple reflections Vc
, P2, and P3 are repeatedly received without being attenuated by the body.

[Purpose of the invention]

An object of the present invention is to eliminate noise caused by such multiple reflections in an electronic circuit of a receiving device.

[Key points of the invention]

Present invention 4, branching the received signal to provide delay and attenuation,
The main feature is that it is equipped with a circuit means for OXing the received 1s signal so that it is in reverse phase.

[Explanation based on examples]

FIG. 3 is a circuit block diagram of a practical example device of the present invention. Probe 11 includes the above-mentioned transducer 1, which acts as an electroacoustic transducer for converting electric pulses into ultrasonic pulses during transmission. C. When receiving, it acts as an acoustic converter that converts the ultrasonic signal into a 1H signal. This probe 11 is used in contact with the body surface, and the electrical input/output circuit of the probe 11 ν, ↓, coupling l! 2 circuits connected to 12 n cores. The output of the transmitting circuit 13 is connected to the transmission signal input of this coupling circuit 12, and the output of the coupling circuit 12 is connected to the receiving circuit 1.
4 inputs are connected. The coupling circuit 12 is composed of a switch circuit synchronized with a known transmitting circuit or a directional coupling circuit.The receiving circuit 14 is composed of a time gain control circuit (TGC) or a known circuit for combining received pulses with a chest width detection circuit. The output signal of this receiving circuit 14, which can accommodate all logarithmic amplifiers, is passed through a digital calculation circuit 15 (connected to the input of an amplifier 16).This amplifier 160 is connected to the video circuit of a CRT device (not shown). The feature of the present invention is that the output signal of the receiving circuit 14 is branched and guided to the input of the amplifier 21, and the output signal of this amplifier 21 is sent to the delay circuit 22.
In addition to 0 human power, the output of this delay circuit 22 is applied to an attenuation circuit 23.
The delay circuit 22 has a variable delay amount, and the attenuation circuit 23 Vi has a configuration formula n so that its attenuation amount is variable. .

To explain the operation of the mufictIL configured in this way, a transmission pulse is sent out from the transmission circuit 13, and this is applied to the transducer of the probe 11 from the coupling circuit 12. In this device, this transmitted pulse is converted into an ultrasonic pulse,
As illustrated in Figure 1, it continuously passes through the body surface 4 and penetrates into the body. When the waves of this ultrasonic pulse reach a target object 5 with a different acoustic impedance, a reflected wave is generated, which travels backwards through the body and enters the camera element 1, where it is converted into an electrical signal.This electrical signal is The signal from the coupling circuit 12711 is input to the receiving circuit 14, where it is amplified, detected, or waveform-shaped and output. This waveform is an example of t! 'i It becomes as shown in FIG. 2A.

The reflected wave that reaches the vibrator of the probe 11 causes multiple reflections on the discontinuous surface of the acoustic impedance as described above, and the reflected wave P that is reflected from the target object.

In addition, reflections due to multiple reflections vP1, P2, PM・
...is dusted off.

As shown in FIG. 3, the output of the receiving circuit 14 is
2, so if you adjust the amount of delay appropriately, as shown in Fig. 2B, V will be reflected to the target and i! Ai
The distance can be set so that the reflected signal Po' appears at the time coincident with the first multiple reflected wave P1.

Further, the attenuation amount of the attenuation circuit 23 can be set to attenuate the delayed signal Po' so that its amplitude matches the amplitude of the negative-th multiple reflected wave P1. The output signal of this attenuation circuit 23 becomes as shown in FIG. 2C.

This output signal is inputted to the adder circuit 15 as shown in FIG.
7]'': Only the desired reflected wave po appears, and all unnecessary multiple reflected waves P1, P2, P3, . . . can be removed.

In this way, even if multiple reflections occur, they do not become noise when observed.

In the above example, it was explained that the output signal of the receiving circuit 14 is completely delayed, then attenuated, and then added in reverse phase. good. For example, the output signal of the receiving circuit 14 is branched to 2
It is also possible to invert the signal 7''l, attenuate it, and then delay it.

In the above example "'C", we explained the case where the cause of multiple reflections is -, but what is the cause of multiple reflections? When counting J, a plurality of such circuit means can be provided for each cause. In this case, a portion of the circuit can be shared, such as by using a tapped circuit as the delay circuit and sharing it with a plurality of (ro)path means.

It is preferable to make the delay circuit and the attenuation circuit variable, respectively, but for a specific cause of multiple reflections, they can also be fixed after being set.

In addition, the points at which the signals of the receiving circuit are branched and the points at which they are added do not necessarily have to be the output signals of the entire receiving circuit, but can be appropriately selected in the middle of various circuits included in the receiving circuit.

[Application of invention]

In addition to the ultrasonic diagnostic apparatus described in the above example, the present invention can be applied to various types of devices to be measured using ultrasonic reflection.

As explained above, according to the present invention, even if multiple reflections occur, they can be removed within the receiving device. Therefore, observation becomes more accurate and multiple reflections due to gloves and other objects can be tolerated.
There is an advantage that the scope of application of the device can be extended to others.

[Brief explanation of drawings]

FIG. 1 is a structural diagram for explaining an example of multiple reflection. FIG. 2 is a waveform diagram for explaining operation. This waveform diagram is exaggerated to make the explanation easier to understand. FIG. 3 is a circuit diagram of a device according to an embodiment of the present invention. 1. Two oscillators, 2... Indigo layer, 3... Comrence,
4...Body surface, 5...Target, l]...Glove, 12...Coupling circuit, 13...Transmission circuit, 14...
・Receiving circuit, 15... 71Ll score circuit, 16... Bank width amplifier, 21... Amplifier, 22... Delay circuit, 23.
...Attenuation circuit. ^ 2 Figure 3

Claims (1)

[Claims] (1) In a 5′ ultrasonic reflected wave receiver including an acoustoelectric transducer that captures ultrasonic waves reflected from a target object and converts them into electrical signals, and a receiving circuit that amplifies and detects the output electrical signals of the acoustoelectric transducer. 2. An ultrasonic reflected wave receiving device comprising circuit means for branching the signal of the receiving circuit to give delay and attenuation, and adding it to the output signal of the receiving circuit so as to have an opposite phase.