JPH0226499B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention transmits ultrasonic waves to a subject, receives the reflected echoes from the subject, and generates ultrasonic waves based on the received reflected echoes. The present invention relates to an ultrasonic diagnostic apparatus that obtains information regarding tissues inside a subject, and particularly relates to improving azimuth resolution.

(b) Prior art A linear electronic scanning type ultrasonic diagnostic device uses multiple ultrasonic probes or multiple ultrasonic probes in one.
When the block is divided into multiple blocks, ultrasonic waves are transmitted and received by transmitting and receiving ultrasonic waves with a slight time delay between the outer ultrasonic probe of each block and the inner ultrasonic probe. There are some that have a narrower beam and higher lateral resolution. However, with this method, it is relatively easy to set the above-mentioned time in order to increase the azimuth resolution for a diagnostic site at a specific distance, but it is relatively easy to set the above-mentioned time for a diagnostic site at an undefined distance. There are some difficulties in configuring the settings.
Therefore, very complex control and processing circuits are required to obtain the desired resolution even for diagnostic sites at undefined distances.

(c) Purpose It is an object of the present invention to enable ultrasonic waves to be transmitted and received easily and with high resolution even at diagnostic sites located at undefined distances using a simple circuit configuration.

(D) Structure In order to achieve the above object, the present invention applies logarithmic amplification to the output signals of the ultrasound probe arranged in the center and the output signals of the ultrasound probes arranged on both sides. After that, both output signals are multiplied by a multiplier, and the output of the multiplier is detected and taken out from a bandpass filter, and the ultrasonic probes on both sides are moved from the center to the outside as time passes. The drive is switched in the direction in which they are arranged.

(E) Embodiment FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention. The linear electronic scanning ultrasound diagnostic apparatus of this embodiment has a large number of ultrasound probes arranged in an array. Each of these ultrasonic probes is divided into a plurality of blocks for linear electronic scanning, and FIG. 1 shows ultrasonic probes TD ₁ -TD ₇ in one of the blocks. A ₁ to _{A 3} are first to third adders, respectively, and DL ₁ to DL ₃ are first to third delay circuits that temporally delay input signals. In terms of codes, the length of the delay time increases in the order of DL ₁ , DL ₂ , and DL ₃ . 1st adder
A ₁ is the fourth ultrasound probe TD ₄ arranged in the center
The respective output signals of the first and seventh ultrasonic probes TD ₁ and TD ₇ which are arranged at the farthest distance from each other are added.
The second and third adders A ₂ and A ₃ are the first and seventh adders, respectively.
4th ultrasonic probe than ultrasonic probe TD ₁ , TD ₇
Each output signal of _the second and sixth ultrasonic probes TD ₂ and TD ₆ closer to TD 4 and the third and fifth ultrasonic probes TD ₃ ,
Add each output signal of TD ₅ . GA ₁ to GA ₄ are first to fourth gain control amplifiers controlled by a gain control device GC so that the magnitude of gain changes over time. In the code, GA ₁ is Fig. 2 d, GA ₂ is Fig. 2
GA ₃ has the gain characteristics shown in FIG. 2b, and GA ₄ has the gain characteristics shown in FIG. 2a, respectively. By providing each of the gain control type amplifiers GA ₁ to _{GA 4} with such a gain characteristic, each of the ultrasound probes arranged on both sides of the fourth ultrasound probe TD ₄ arranged in the center can be There is no need to provide a changeover switch for sequentially switching in a direction away from the fourth ultrasonic probe _TD4 . This eliminates the need to take measures against switching noise that occurs when switching such a changeover switch.

Furthermore, since the gain increases over time, an output signal having a predetermined level can be obtained no matter where the diagnostic site of the subject is located. _A4 is a fourth amplifier that adds the output signals of the first to third gain control amplifiers _GA1 to _GA3 .
It is an adder.

LOG ₁ is a first logarithmic amplifier that logarithmically amplifies the output signal of the fourth adder A ₄ , and LOG ₂ is a second logarithmic amplifier that logarithmically amplifies the output signal of the fourth gain control type amplifier GA ₄ . Each of these logarithmic amplifiers LOG ₁ ,
LOG ₂ is for converting the exponential attenuation of the amplitude of the reflected echo according to the depth of the object into an almost linear attenuation. A signal corresponding to the output signal of the fourth ultrasound probe TD ₄ arranged in the center is given to the second logarithmic amplifier LOG ₂ , and the signal S ₁ shown in FIG. 3a is output from its output section. Ru. The first logarithmic amplifier LOG ₁ is given a signal corresponding to the output signal of the other ultrasonic probes arranged on both sides, and the signal S ₂ shown in FIG. 3b is outputted from its output section. The first and second signals S ₁ and S ₂ have a phase difference depending on the direction of the diagnostic site where the ultrasound waves are transmitted.

M is a multiplier that multiplies the output signals of the logarithmic amplifiers LOG ₁ and LOG ₂ . This multiplier M outputs a signal having a positive waveform for portions of the first and second signals S ₁ and S ₂ with the same polarity, and outputs a signal having a negative waveform for portions with different polarities. do. Therefore,
The first and second signals S ₁ and S ₂ as shown in FIG. 3 a and b
In this case, the multiplier M outputs a third signal _S3 having a waveform as shown in FIG. 3c.
DT is a detector that detects the third signal _S3 from the multiplier M. This detector DT cuts signals having negative polarity, and when a third signal S3 as shown in FIG. 3c is input, a fourth signal _S3 as shown in FIG. 3d is input. Detected at ₄ . Therefore, the larger the phase difference between the first and second signals S ₁ and S ₂ (however, it does not exceed 180°), the more the negative polarity portion of the third signal S ₃ is cut by the detector DT. The proportion of BPF is a bandpass filter that filters the fourth signal _S4 from the detector DT. If the third signal S ₃ has even a slight negative polarity, the output signal of this band filter BPF is different from the first and second signals S ₁ and S ₂
If there is even a slight phase difference between them, the level will be very small. Figure 3 e shows the bandpass filter BPF.
The waveform of the fifth signal _S5 outputted from is shown. Therefore, according to this embodiment, when the output signal of the ultrasound probe arranged in the center and the output signal of the ultrasound probes arranged on both sides are in phase,
If a fifth signal _S5 with a very high level is obtained from the bandpass filter BPF, and there is even a slight phase difference between the two output signals, the level of the fifth signal _S5 becomes very small. Therefore, the directivity of the ultrasonic beam becomes extremely high, and the azimuth resolution is greatly improved. Further, according to this embodiment, since the frequency of the signal is doubled by the multiplier M, the response speed of the detector (not shown) when the output of the bandpass filter BPF is detected by the detector can be increased. . In addition,
In the above embodiment, no logarithmic amplifier is provided;
Alternatively, a polarity discriminator may be placed on one side.

(F) Effect As described above, according to the present invention, the signals corresponding to the output signals from the ultrasound probe arranged in the center and the ultrasound probes arranged on both sides are multiplied by the multiplier. A signal for displaying an ultrasonic tomographic image with high lateral resolution can be easily obtained with a simple circuit that multiplies, detects, and then filters and extracts the signal using a bandpass filter. can.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a circuit diagram showing the overall configuration, FIG. 2 is a diagram showing the gain characteristics of a gain control type amplifier, and FIG. 3 is a diagram showing the output of each part to explain the operation. It is a signal waveform diagram. TD ₁ to TD ₇ ... Ultrasonic probe, M... Multiplier,
DT...detector, BPF...bandwidth filter.

Claims (1)

[Claims] 1 Output signal of the ultrasound probe arranged in the center among multiple ultrasound probes arranged in an array, and the ultrasound probes arranged on both sides of this ultrasound probe A multiplier that multiplies the output signal of the multiplier by each corresponding signal, a detector that detects the output signal of this multiplier, and a bandpass filter that filters the output signal of this detector. An ultrasonic diagnostic apparatus characterized in that the probes are sequentially switched and driven in a direction arranged at a distance from a central ultrasonic probe as time passes.