JPH0569538B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to an ultrasonic diagnostic apparatus.

[Technical background of the invention]

FIG. 1 shows an example of a conventional ultrasonic diagnostic apparatus commonly used.

In the figure, 1 is a transducer that transmits and receives ultrasonic waves, and an arbitrary number of vibration elements 2a, 2b,
2c, . . . , 2n. Each vibration element 2
The ultrasonic echoes received by a, 2b, 2c, . 4n.

At this time, since the echo signal corresponding to a deeper part of the object has a lower level as shown in FIG. 2a, each preamplifier 4a, 4b, 4c, …
..., 4n, and when an echo signal corresponding to a deep part is input, the gain of the preamplifier is increased, and when an echo corresponding to a shallow part is input, the gain of the preamplifier is decreased.

This is pre-STC (Sensitivity Time Control)
This is an operation called. The pre-STC operation is performed by a control signal _N1 from the control circuit 7.

Each echo signal amplified by the preamplifiers 4a, 4b, 4c, . . . , 4n is input to element number variable means 5a, 5c, 5c, .

Element number variable means 5a, 5b, 5c, ..., 5n
has the function of increasing or decreasing the number of transducer elements of the transducer 1 used when transmitting ultrasonic pulses when receiving ultrasonic echoes, and as a result, the ultrasonic wave Efforts are being made to improve the sound field characteristics by narrowing down the beam.

This will be explained in further detail with reference to FIG. 4a.

The figure schematically shows the transducer 1, and includes vibration elements 2a, 2b, 2c, ..., 2n.
This means that echoes are received only by the vibrating elements in the center that are turned on.

Such element number variable means 5a, 5b, 5c,
..., 5n is called "variable aperture". This is because the effective diameter of the transducer 1 changes as the number of vibration elements 2a, 2b, . . . , 2n increases or decreases.

The variable aperture can be realized, for example, by a switch (not shown) that is turned on and off electronically.

The variable aperture is also controlled by a control signal _N2 from the control circuit 7.

Element number variable means 5a, 5b, 5c, ..., 5n
The respective output signals of weighting means 6a, 6
b, 6c, . . . , 6n, respectively.

Weighting means 6a, 6b, 6c,...
6n is each vibrating element 2a, 2 of the transducer 1
It has a function of weighting the gain of each channel corresponding to b, 2c, .

This will be explained in further detail with reference to FIG. 4b.

The figure shows each vibrating element 2a of the transducer 1,
2b, 2c, . . . , 2n and how the gains are weighted for them.

That is, in the figure, the weighting means 6a, 6b, 6 are arranged so that the gain for the central vibrating element is large and the gain is smaller for the vibrating elements at the ends.
This shows that weighting is performed by c, . . . , 6n.

Such weighting means 6a, 6b, 6
Weighting by c, .

Weighting means 6a, 6b, 6c, ...,
The weighting control by 6n is also performed by the control signal _N2 from the control circuit 7.

Each weighting means 6a, 6b, 6c,...
..., 6n are input to the reception delay circuit 8.

The reception delay circuit 8 performs phase matching between channels corresponding to each echo signal, and outputs a single composite signal.

This single composite signal is processed by the amplification/detection circuit 9 and input to the display means 10.

In the display means 10, for example, an ultrasonic tomographic image is displayed on a cathode ray tube as a result of 64 electronic scans performed by the transducer 1.

[Problems with background technology]

In the conventional ultrasonic diagnostic apparatus described above, a circuit configuration as shown in FIG. 3 is often used as the preamplifiers 4a, 4b, . . . , 4c.

In the same figure, 11 is an input terminal, 12 is an output terminal, 13 is a gain control terminal, TR ₁ , TR ₂
is an amplification transistor, and TR ₃ is a gain control transistor.

The preamplifier shown in FIG. 3 is designed to control the amount of feedback of the transistor TR ₁ by changing the equivalent resistance of the transistor TR ₃ using the DC voltage applied to the gain control terminal 13. It is widely used.

However, there is a characteristic that the gain control characteristics differ significantly due to deviations in the characteristics of the transistor TR ₃ and circuit elements, and the
If this preamplifier is used for each of the transducer elements 2a, _2b , . .

Furthermore, since the gain control characteristic of the preamplifier described above is exponential, it has been difficult to ensure the accuracy of the pre-STC.

Furthermore, the echo signals are transmitted to the preamplifiers 4a, 4b, 4c, . . .
n, element number variable means 5a, 5b, 5c, ..., 5
n and weighting means 6a, 6b, 6c,...
. . , 6n, which has the disadvantage of significant deterioration.

Furthermore, in the case of a device using a transducer with a large number of vibrating elements, the preamplifiers 4a, 4b,
4c, ..., 4n, element number variable means 5a, 5b,
5c, ..., 5n and weighting means 6a,
6b, 6c, . . . , 6n are required as many as the number of elements, and therefore, there is also a drawback that the scale of the configuration of the ultrasonic diagnostic apparatus increases.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and by using an analog multiplier as a preamplifier, a means for varying the number of elements, and a weighting means, there is no deviation in the gain control characteristics of each channel and accurate preamplifier can be achieved. The object of the present invention is to provide an ultrasonic diagnostic apparatus that has STC characteristics, prevents deterioration of echo signals, and prevents expansion of the configuration.

[Summary of the invention]

The outline of the present invention for achieving the above object includes a transducer having a plurality of oscillators, and a transducer having a plurality of oscillators. A plurality of preamplifier means consisting of an analog multiplier provided for each channel corrects the difference in received signal level, and a means for variable number of elements that changes in the time direction from the received signal for each channel and a control signal that changes in the time direction. a plurality of element number variable means consisting of an analog multiplier provided for each channel that increases or decreases the number of receiving elements to change the effective aperture of the transducer; and a receiving signal for each channel that changes in the time direction. a plurality of weighting means comprising analog multipliers provided for each channel for weighting the received signal for each channel to improve sound field characteristics from a control signal for each preamplifier; A common unit that outputs the preamplifier means control signal that changes in the time direction, the element number variable means control signal that changes in the time direction to each of the element number variable means, and the weighting means control signal to each of the weighting means. The invention is characterized by comprising a control means.

[Embodiments of the invention]

Examples of the present invention will be described in detail below.

FIG. 5 shows a receiving circuit 2 in an embodiment of the present invention.
This figure shows an analog multiplier 21 used for 0.

In the same figure, X is an input, Y is a control input, and V _p
represents the output, and K represents the coefficient, respectively.

These relationships are shown in equation (1) below.

V _p =K.X.Y (1) Note that the coefficient K can be set to any value by an external resistor connected to the analog multiplier 21.

The relationship in equation (1) is determined by the configuration of the analog multiplier 21, and is the same among analog multipliers with the same configuration.

As is clear from the above equation (1), by inputting an echo signal as the input X and a DC voltage as the control input Y, for example, it is clear that the amplitude of the echo signal is controlled, that is, the gain is controlled.

FIG. 6 shows a first embodiment of the present invention,
Components having the same functions as those of the device shown in FIG. 1 are given the same symbols and their explanations will be omitted.

The difference between the device shown in the figure and the one shown in FIG. 1 is that the preamplifiers 4a, 4b, 4c, ..., 4n,
Element number variable means 5a, 5b, 5c,..., 5n and weighting means 6a, 6b, 6c,...,
6n respectively into analog multipliers 21A ₁ , 21A ₂ ,
21A ₃ ,..., 21An, 21B ₁ , 21B ₂ , 21
B ₃ , ..., 21Bn, 21C ₁ , 21C ₂ , 21C ₃ ,
..., 21Cn to configure the receiving circuit 20.

In the device having the above configuration, the transducer 1
The echo signals from each vibrating element 2a, 2b, 2c, ..., 2n are sent to analog multipliers 21A ₁ , 21A ₂ ,
21A ₃ , .
A ₁ , 21A ₂ , 21A ₃ , . . . , 21An are multiplied according to the above equation (1).

Therefore, each output V _p is uniquely determined according to equation (1), and does not depend on the characteristics of the transistor TR ₃ unlike a conventional preamplifier, but rather ,2c,...,2n
It is possible to eliminate the gain deviation between channels corresponding to , and since equation (1) is in a simple form, it is possible to easily perform pre-STC.

Each analog multiplier 21B ₁ , 21B ₂ , 21B ₃ ,
..., 21Bn's input X and the output of each analog multiplier 21A ₁ , 21A ₂ , 21A ₃ , ..., 21An
V _p is applied to each, and a control voltage is applied from the control circuit 7 as each control input Y.

Similarly, each analog multiplier 21C ₁ , 21C ₂ , 2
Each analog multiplier 21B ₁ , 21B ₂ , 21B ₃ , ..., 21Bn as input X of 1C ₃ , ..., 21Cn
The output V _p of the control circuit 7 is applied thereto, and a control voltage is applied as each control input Y from the control circuit 7.

Therefore, analog multipliers 21B ₁ , 21B ₂ ,
21B ₃ , ..., 21Bn variable number of elements, analog multiplier 21C ₁ , 21C ₂ , 21C ₃ , ..., 2
Weighting by 1Cn can also be achieved according to equation (1), and there is no need for an electronic switch for varying the number of elements or a resistance for weighting as in the conventional device. Note that the control voltage sent from the control circuit 7 can be stored in a memory or the like in advance and read out for use.

FIG. 7 shows a second embodiment of the present invention, and parts having the same functions as the device shown in FIG. 2 are denoted by the same reference numerals, and the explanation thereof will be omitted.

The difference between the device shown in FIG. 2 and the device shown in FIG. 2 is that the analog multipliers 21A ₁ , 21B ₁ , 21C ₁ are replaced with one analog multiplier 21D ₁ , and the analog multipliers 21A ₂ , 21B ₂ , 21C 2 are replaced with one analog multiplier 21D ₁ . The analog multiplier 2
1D ₂ , analog multipliers 21A ₃ , 21B ₃ , 21
C ₃ to the analog multiplier 21D ₃ , and the following three analog multipliers that share three different functions are combined into one analog multiplier, and the control circuit 7A allows the pre-STC variable aperture, A composite control signal N _p in which each weighting control signal is combined is sent to each analog multiplier 21D ₁ ,
21D ₂ , 21D ₃ , . . . , Dn are inputted as each control input Y.

The composite control signal No. is stored in the memory 23 in advance, and is sent to the control circuit 7 according to instructions from the CPU 24.
It is designed to be output from A.

In the device having the above configuration, echo signals from each vibrating element 2a, 2b, 2c, ..., 2n of the transducer 1 are sent to the analog multiplier 21 of the receiving circuit 20A.
Each input X of D ₁ , 21D ₂ , 21D ₃ , ..., 21Dn
and when the composite control signal No. is added as each input Y from the control circuit 7A,
Each analog multiplier 21D ₁ , 21D ₂ , 21D ₃ ,...
..., 21Dn performs three types of multiplication processing: pre-STC, variable aperture, and weighting according to equation (1) above.

Therefore, the receiving circuit 20A is functionally the sixth
In addition to the functions of the receiving circuit 20 shown in the figure, the number of analog multipliers used for each channel is reduced to 1/3, making it possible to reduce the size of the configuration and reducing the number of echo signal passing circuits, thereby preventing its deterioration. It becomes possible to do so.

It goes without saying that the present invention is not limited to the embodiments described above, and that various modifications can be made within the scope of the invention.

〔Effect of the invention〕

According to the present invention described in detail above, by configuring the analog multiplier to multiply the received ultrasound signal and the control signal that changes over time, the multiplication process is performed in accordance with the intensity of the echo signal. Puri
STC is easy and the gain deviation between each channel can be reduced without adjustment.

Furthermore, echo signal amplification, variable aperture, and weighting can be achieved with one circuit for each channel, making it possible to prevent echo signal deterioration and reduce the overall configuration scale.

[Brief explanation of drawings]

Figure 1 is a block diagram showing a conventional ultrasound diagnostic device, Figure 2a is an explanatory diagram of the pre-STC, showing the relationship between the intensity and depth of ultrasound echoes, and Figure 2b is a diagram of the same preamplifier. Figure 3 shows the relationship between gain and depth. Figure 3 is a circuit diagram of a preamplifier used in a conventional ultrasonic diagnostic device. Figure 4 a is an explanatory diagram showing the state of the variable aperture of the transducer. Figure 4 b is a diagram of the transformer. FIG. 5 is an explanatory diagram showing the weighting of the gain of each channel corresponding to the multiplier, FIG. 5 is an explanatory diagram of the analog multiplier used in the embodiment of the present invention, and FIG. 6 is a block diagram showing the first embodiment of the present invention. 7 are block diagrams showing a second embodiment of the present invention. 1...transducer, 2a, 2b, 2c,
..., 2n... Vibration element, 4a, 4b, 4c,...
..., 4n...preamplifier, 5a, 5b, 5c,...
..., 5n... element number variable means, 6a, 6b, 6
c, ..., 6n... weighting means, 20,
20A...Receiving circuit, 21A ₁ , 21A ₂ , 21
A ₃ ,...,21An...analog multiplier, 21
B ₁ , 21B ₂ , 21B ₃ , ..., 21Bn ... analog multiplier, 21C ₁ , 21C ₂ , 21C ₃ , ..., 2
1Cn...analog multiplier, 21D ₁ , 21D ₂ , 2
1D ₃ ,..., 21Dn...Analog multiplier.

Claims (1)

[Claims] 1. A transducer having a plurality of vibrators;
A plurality of preamplifier means consisting of an analog multiplier provided for each channel corrects the difference in the received signal level of each transducer in the time direction from the received signal from each transducer and the preamplifier control signal that changes in the time direction. and a means for changing the effective diameter of the transducer by increasing or decreasing the number of effective receiving elements in the time direction based on the received signal for each channel and a control signal for changing the number of elements in the time direction. The sound field characteristics are improved by weighting the received signal for each channel using a plurality of element number variable means consisting of analog multipliers, and a weighting means control signal that changes in the time direction. a plurality of weighting means each consisting of an analog multiplier provided for each channel, the preamplifier means control signal changing in the time direction for each of the preamplifier means, and the preamplifier means control signal changing in the time direction for each of the element number variable means. An ultrasonic diagnostic apparatus comprising: a common control means for outputting the element number variable means control signal and the weighting means control signal to each of the weighting means. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the preamplifier means, element number variable means, and weighting means for each channel are constructed by the same multiplier.