JP3149245B2 - Ultrasonic reception dynamic focus circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic receiving dynamic focus circuit. A convergent wavefront can be formed by time-delaying an ultrasonic pulse for driving each probe (vibrator) to a transducer having a large number of probes arranged in an array.

This has the effect of narrowing the beam diameter in the same way as using an acoustic lens or a concave vibrator. This is called electronic focus. It is necessary to focus the ultrasonic waves similarly at the time of reception.

FIG. 6 is a diagram showing the principle of the electronic focusing at the time of reception, and FIGS. 7 and 8 are diagrams showing the principle of the dynamic focus. As shown in FIG. 6, in each probe (vibrator), the received ultrasonic echo signal is focused on the ultrasonic echo signal using an electronic focus for delaying a predetermined time, respectively.
When the phases are aligned and added at the addition point, the width of the ultrasonic beam in the vicinity of the focus point can be reduced as shown in the figure to improve the resolution.

However, at locations other than the vicinity of the focal point, the width of the ultrasonic beam is widened. As shown in FIG. 7A, when the focus point is set at a short distance from the probe, the width of the ultrasonic beam increases at a long distance, and the ultrasonic tomographic image deteriorates.

Conversely, as shown in FIG. 7B, if the focus point is set at a long distance, the ultrasonic beam cannot be sufficiently focused at a short distance, so that the ultrasonic tomographic image deteriorates. Therefore, as shown in FIG. 8 (c), it is conceivable that the focus point is moved from a short distance to a long distance to always maintain the best ultrasonic beam width.

[0006] In one transmission, only a certain point can be focused, but in reception, the focus point can be dynamically moved, which is called reception dynamic focus. By changing the focus point at the time of reception, the width of the ultrasonic beam can be made smaller regardless of the depth as compared with the fixed focus.

Conventionally, various techniques have been known as the ultrasonic receiving dynamic focus technique. However, there are problems such as an increase in circuit scale, a problem in which a received waveform is distorted, and a problem in which switching noise is generated. Yes,
There is a need for an ultrasonic reception dynamic focus circuit that can effectively perform dynamic focus.

[0008]

2. Description of the Related Art FIG. 9 is a diagram for explaining a conventional ultrasonic receiving dynamic focus circuit. FIG. 9A shows a case where a delay group is switched by an analog switch, and FIG. 9B shows a delay using a variable capacitance diode. The line shows the case where the delay amount is changed by changing the voltage applied to the variable capacitance diode, and FIG. 3 (c) shows the case where the delay amount is changed by controlling the phase of the received signal with the phase of the local oscillator.

First, in the circuit shown in FIG. 9 (a), the delay amount is changed by switching each delay tap from A to B at reception using the delay line 1 with tap. Thereby, the focus by A and the focus by B are obtained.

In the circuit shown in FIG. 9B, the voltage applied to the variable capacitance diode (D) 11 is changed to
It changes the delay amount of 1. FIG. 9 (c) is an application published in Japanese Patent Application Laid-Open No. 54-96286. In summary, before the delay amount from the delay line 1 is subjected to phasing addition, it is necessary to correspond to each probe. Then, a variable phase shifter as shown in the figure is provided to enable addition with accurate phase coherence, thereby realizing the above-described dynamic focus. In the variable phase shifter, the received signal is frequency-modulated by heterodyne processing by a mixer, and the phase of the received signal is controlled by the phase of a local oscillator used at that time. That is, the ultrasonic signal received from the probe is frequency-modulated by the mixer, input to the delay line 1, and after a required delay, the delayed ultrasonic reception signal from each probe 1 is added. Will be done.

[0011]

In the circuit for switching the tap of the delay line 1 shown in FIG. 9A, there is a problem that switching noise is included in the received signal when the tap is switched.

The variable capacitance diode shown in FIG.
In the circuit using (D), there is a problem that the impedance of the delay line 1 changes, reflection occurs on the delay line 1, and the received waveform is distorted.

Further, the variable phase shifter shown in FIG.
In a circuit that performs addition with accurate phase coherence, there is a problem that a large delay cannot be applied due to a phase change, and a problem that the circuit scale becomes large.

In view of the above-mentioned conventional disadvantages, the present invention provides an ultrasonic receiving dynamic focus circuit capable of forming a near-ideal dynamic focus circuit without switching noise by reducing the circuit scale. It is intended to provide a circuit.

[0015]

FIG. 1 is a block diagram showing the principle of the present invention. The above problem can be solved by the ultrasonic receiving dynamic focus circuit configured as follows.

An ultrasonic diagnostic apparatus having a mechanism for inputting an ultrasonic pulse for driving each probe with a time delay to a transducer having a plurality of probes arranged in an array and performing electronic focusing, A circuit for dynamically changing the delay of the ultrasonic reception signal received by each probe () is provided for each probe () by a tapped delay line 1 and each tap 10 by a transistor 2. A collector (C) is connected, the emitter (E) of the transistor 2 is made common, a signal source 3 of a constant current input corresponding to a received ultrasonic signal is inputted, and the base (B) of each transistor 2 is inputted. Respectively attenuate components of the signal below a certain frequency.
Low-pass filter circuit and low-pass filter circuit
Clamp circuit that clamps the output of the device within a specified voltage range
And a logic control circuit 5 is connected to the base signal generation circuit 4. In response to a tap switching signal from the logic control circuit 5, A circuit for obtaining a received ultrasonic signal dynamically delayed from the terminal side of the delay line 1 is constituted by a plurality of circuits provided for each probe (). In this case,
-Pass filter circuit integrates a resistor and a capacitor
Circuit, wherein one end of each of the clamp circuits is
Opposite to each other connected to the base of the transistor (2)
Two diodes arranged in parallel in the
Apply each voltage to the other end of each of the two diodes.
Diodes common to several transistors (2)
It may be composed of a bias circuit .

[0017]

In other words, in the present invention, each tap of the delay line 1
Connect the collector (C) of transistor 2 to 10 and
The emitter (E) of the plurality of transistors 2 is shared, and the signal to the delay line 1 is a constant current output.

For example, a received ultrasonic signal is input to the base (B) of the transistor 30 constituting the constant current output source, and a constant current output corresponding to the received ultrasonic signal is output to the transistor 2. To the emitter (E).

The base of the plurality of transistors 2
In (B), the logic control circuit 5 generates and inputs a signal that is at the “H” level necessary for the required tap 10 and for the required period.

For the base input signal, for example, a logic signal of a transistor transistor logic (TTL) level generated by the logic control circuit 5 is input to the base signal generation circuit 4 and is input into the base signal generation circuit 4. When the signal is input to an integrated circuit including a normal resistor (R) and a capacitor (C), as described later, the period “H” is short after the tap switching base signal having the long period “H”. When the tap switching base signal comes, the integrated signal of the tap switching base signal having the short period “H” is buried in the integrated signal of the tap switching base signal having the long period “H”. ,
The integrated signal is clamped by a diode and two types of diode bias voltages (V1, V2), so that the period “H” of the base input signal has a similar slope regardless of whether it is long or short. A base signal proportional to H ″ can be input to the transistor 2.

Therefore, with a simple circuit, the switching noise is small, the impedance change in the delay line 1 is small, and the base signal proportional to the tap switching period “H” regardless of the length of the tap switching period “H”. Is the base of transistor 2 connected to each tap 10 (B)
Can be applied to the ultrasonic receiving signal, and the ultrasonic receiving signal can be provided with a plurality of the circuits corresponding to the respective probes. There is an effect that an ultrasonic image can be obtained.

[0022]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a diagram showing the principle of the present invention.
FIG. 5 is a diagram showing one embodiment of the present invention, and FIG.
FIG. 3 shows an example of the configuration of a base signal generation circuit, FIG. 4 shows an example of generation of a base signal, and FIG. 5 shows a switching signal from tap 1 to tap 2. Is shown.

According to the present invention, there is provided an ultrasonic diagnostic apparatus comprising a transducer having a plurality of probes arranged in an array and a mechanism for performing an electronic focusing by delaying an ultrasonic pulse for driving each probe with a time delay. In the above, a circuit for dynamically changing the focus point of the ultrasonic reception is connected to a delay line 1 with a tap and a tap 10 for each probe, and a collector (C) of a transistor 2 is connected to each of the taps. The emitter (E) of the transistor 2 is shared, and the signal source 3 of the constant current input corresponding to the received ultrasonic signal is input. The base (B) of each transistor 2 is shared by a resistor, a capacitor, a diode, and a common resistor, respectively. Connected to a base signal generation circuit 4 consisting of a diode bias voltage circuit 40, and a logic control circuit 5 connected to the base signal generation circuit 4. Plurality providing means Te is a means necessary for carrying out the present invention. Note that the same reference numerals indicate the same object throughout the drawings.

The operation of the configuration of the ultrasonic receiving dynamic focus circuit according to the present invention will be described below with reference to FIGS. First, in the ultrasonic receiving dynamic focus circuit of the present invention, the collector (C) of the transistor 2 is connected to each of the delay line 1 with tap and each tap 10 for one circuit for each probe. The emitter (E) of the transistor 2 is shared, and the signal source 3 of the constant current input corresponding to the received ultrasonic signal is input. The base (B) of each transistor 2 has a resistor, a capacitor, a diode, and a common resistor, respectively. A base signal generation circuit 4 including a simplified diode bias voltage circuit 40 is connected, and the base signal generation circuit 4 is connected to a logic control circuit 5.

In the ultrasonic diagnostic apparatus, in order to perform dynamic focusing, as described above, an electronic focusing mechanism, that is, an ultra-high-frequency driving mechanism for driving each probe of a transducer in which a plurality of probes are arranged in an array. It is necessary to time-delay the sound wave pulse, and at the time of reception, to give a time delay to each probe at the reception focus point.

The constant current source input signal source 3 composed of the transistor 30 is provided, and the base (B) is driven by the received ultrasonic signal to generate the constant current mode signal source 3. be able to.

The base (B) of the transistor 2 having the emitter of the signal source 3 of the constant current source input corresponding to the received ultrasonic signal is controlled by a tap switching signal from the logic control circuit 5 to obtain the reception signal. The delayed ultrasonic signal can be delayed.

At this time, each tap (1) to (n) 10 of the delay line 1
On the other hand, as shown in FIG. 2, tap switching signals A having different tap switching periods “H” are input to the base signal generation circuit 4. This is because the amount of delay with respect to the ultrasonic echo signal received by one probe is changed to the change of the focus point as a whole.

If the tap switching signals A1, A2,... Having different tap switching periods "H" are supplied to the base (B) of the transistor 2 as they are, switching noise is generated as described above.

Therefore, in the present invention, the tap switching signal is integrated into the base (B) of the transistor 2 by the integrating circuit 41 including the resistor and the capacitor shown in FIG.

At this time, after the tap switching signal A1 having a long tap switching period “H” (corresponding to the tap switching signal of the tap (1) in FIG. 2), the tap switching signal A2 having a short tap switching period “H” is shown. Two taps
When｝ corresponding to the tap switching signal of (1) comes, the integrated waveform becomes as shown by a solid line and a dotted line in FIG. 4A, and the integrated waveform a1 (1) of the tap switching signal A1 having a long tap switching period “H”. (Indicated by a solid line), the integrated waveform a of the short tap switching signal A2 during the subsequent tap switching period “H”.
2 (indicated by the dotted line) may be buried.

Therefore, in the present invention, a diode circuit is provided after the integrating circuit 41 of the base signal generating circuit 4.
By providing the clamp circuit 40 composed of the diode bias voltage circuit 401 and the diode bias voltage circuit 401, the integrated waveform a1 shown in FIG. 4 (b) is changed to the tap shown in FIG. 2 as shown in FIG. 4 (b). The integration operation starts and ends at the rising and falling timings of the switching signal.
Shifting up by one gives a trapezoidal waveform clamped at voltage V2.

Accordingly, as shown in FIGS. 4C and 5, the tap switching signal A1 having a long tap switching period "H" is used.
Is not buried in the integrated waveform a1 (shown by a solid line) of the tap switching signal A2 having a short tap switching period “H” thereafter.
A tap signal can be supplied to the base (B) of the transistor 2 at the correct timing. Of course, as shown in FIG. 4 (c), the switching signal is shaped into a trapezoidal signal and applied to the base (B) of the transistor 1, so that the switching noise that has conventionally occurred can be reduced. it can.

As described above, according to the present invention, in an ultrasonic diagnostic apparatus having a transducer in which a plurality of probes are arranged in an array, a circuit for dynamically changing a focus point of ultrasonic reception is provided for each probe. One circuit is provided for each
The circuit is connected to a delay line with taps and to each tap, a collector (C) of a transistor is connected, an emitter (E) of the transistor is shared, and a current input signal source corresponding to a received ultrasonic signal is provided. And a base signal generation circuit composed of a resistor, a capacitor, a diode, and a common diode bias voltage circuit connected to the base (B) of each transistor, and a logic control circuit is connected to the base signal generation circuit. Are connected to each other, and in response to a tap switching signal from the logic control circuit, a reception ultrasonic signal dynamically delayed from the terminal side of the delay line is obtained. There is a feature in that a plurality is provided corresponding to the child.

[0035]

As described in detail above, the ultrasonic receiving dynamic focus circuit of the present invention is an ultrasonic diagnostic apparatus having a transducer in which a plurality of probes are arranged in an array. One circuit for dynamically changing the focus point is provided for each probe,
Each circuit is connected to a delay line with a tap, and to each tap, a collector (C) of a transistor is connected, and an emitter (E) of the transistor is shared so that a current input corresponding to a received ultrasonic signal is input. A signal source is input, and a base signal generation circuit composed of a resistor, a capacitor, a diode, and a common diode bias voltage circuit is connected to a base (B) of each transistor, and a logic is connected to the base signal generation circuit. A control circuit is connected to and configured to obtain a received ultrasonic signal that is dynamically delayed from the terminal side of the delay line in response to a tap switching signal from the logic control circuit. Since a plurality of probes are provided corresponding to the probe, the switching noise is small with a simple circuit, and the tap switching period is “H”.
Irrespective of the length of the tap, the base signal proportional to the tap switching period “H” can be input to the base (B) of the transistor 2 connected to each tap 10, and the delay close to the ideal Signals can be provided, and by providing a plurality of the circuits corresponding to the respective probes, the reception dynamic focus can be realized, and there is an effect that a higher quality ultrasonic image can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of the principle of the present invention.

FIG. 2 shows an embodiment of the present invention (part 1).

FIG. 3 shows an embodiment of the present invention (part 2).

FIG. 4 shows an embodiment of the present invention (part 3).

FIG. 5 shows an embodiment of the present invention (part 4).

FIG. 6 is a diagram showing the principle of electronic focusing.

FIG. 7 shows the principle of dynamic focus (part 1).

FIG. 8 shows the principle of dynamic focus (part 2).

FIG. 9 is a diagram illustrating a conventional ultrasonic reception dynamic focus circuit.

[Explanation of symbols]

1 Delay line 10 tap 2, 30 Transistor 3 Constant current input signal source 4 Base signal generation circuit 40 Clamp circuit 400 Diode circuit 401 Diode bias voltage circuit 41 Integrator circuit 5 Logic control circuit Probe

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-242051 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 29/00-29/28 A61B 8 / 00-8/15

Claims (2)

(57) [Claims] An electronic focusing mechanism is provided in which a plurality of probes () are arranged in an array, and an ultrasonic pulse for driving each probe () is input with a time delay to a transducer. In the ultrasonic diagnostic apparatus, a circuit for dynamically changing the delay of the ultrasonic reception signal received by each probe () is provided for each probe () by a tapped delay line (1) and each tap ( 10), the collector (C) of the transistor (2) is connected, the emitter (B) of the transistor (2) is shared, and the signal source (3) of the constant current input corresponding to the received ultrasonic signal is connected. ) And the base (B) of each transistor (2)
Reduce the frequency components below the specified frequency.
Low-pass filter circuit and low-pass filter circuit
Circuit that clamps the output of the circuit within a specified voltage range.
And a logic control circuit (5) connected to the base signal generation circuit (4). The logic control circuit (5) A circuit for obtaining a received ultrasonic signal dynamically delayed from the terminal side of the delay line (1) in response to the tap switching signal of
An ultrasonic receiving dynamic focus circuit comprising a plurality of ultrasonic waves provided for each of the plurality of ultrasonic waves. 2. The low-pass filter circuit according to claim 1, wherein
An integrating circuit comprising a capacitor and the clamp circuit.
Is one end of which is the base of the transistor (2).
Two connected in parallel in opposite directions to each other
Diodes and the other end of each of these two diodes
Applying each voltage to a plurality of transistors (2)
And a common diode bias circuit.
The ultrasonic receiving dyna according to claim 1, wherein
Mic focus circuit.