JPH0791B2 - Ultrasonic wave reception dynamic focus circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to an ultrasonic wave reception dynamic focus circuit that dynamically varies a focus position received using an array element, and gradually taps when performing reception dynamic focus using a delay line with taps. A delay line with taps for adjusting the delay time of the ultrasonic reception signal received by each array element, with the purpose of preventing switching and mixing of switching noise and having a simple circuit configuration. A switching element that adjusts the delay time so as to perform reception dynamic focusing by switching to any tap of the delay line with taps, and supplies a selection signal that gradually changes to one of the switching elements. Gradually switch from one tap to another and switch It is configured to suppress receiving noise and perform dynamic reception focusing.

[Industrial application field]

The present invention relates to an ultrasonic receiving dynamic focus circuit that dynamically changes a focus position received using an array element.

[Problems to be solved by conventional technology and invention]

In order to improve the quality of an image such as a B-mode image in an ultrasonic diagnostic apparatus, reception dynamic focus is performed. Conventionally, there is a circuit as shown in FIG. 6 as a circuit for performing the reception dynamic focus. This circuit uses a tap selection circuit 24 for a tapped delay line 25 to dynamically switch to any tap for receiving dynamic focus. At this time, since the taps were switched in response to the pulsed selection signal supplied from the control circuit 26 to the tap selection circuit 24, the switching noise generated at the time of tap switching is mixed in the ultrasonic reception signal. However, there is a problem that the image quality is deteriorated.

FIG. 6 The configuration and operation will be briefly described.

In FIG. 6, the probe 21 is an ultrasonic array element that transmits and receives ultrasonic waves to and from the living body.

The preamplifier 22 amplifies the ultrasonic reflection signal received by the probe 21.

The delay circuit (small) 23 gives a predetermined delay time to the received signal in order to adjust the receiving direction for receiving the ultrasonic wave. This delay time is fixedly given for each line.

The tap selection circuit 24 dynamically switches to an arbitrary tap of the tapped delay line 25 so as to provide reception dynamic focus.

The tapped delay line 25 is a delay line having a tap for adjusting the delay time.

Next, the operation will be described. The ultrasonic reflection signal received by the probe 21 is amplified by the purine up 22 and then
A predetermined delay time is given by the delay circuit 23, and the delay circuit 23 is set to detect a received signal in a predetermined direction. Next, taps are sequentially switched by the tap selection circuit 24 and the delay line 25 with taps so that the reception dynamic focus is performed on one line.

The present invention gradually switches taps when performing dynamic reception focusing using a delay line with taps,
The purpose is to prevent mixing of switching noise and to make a simple circuit configuration.

[Means for solving problems]

Means for solving the problem will be described with reference to FIG.

In FIG. 1, a delay line 1 with a tap is a delay line with a tap for switching a delay time.

The switching element 2 switches the taps of the delay line 1 with taps.

The selection signal generating circuit 3 is for generating a gradually changing selection signal for driving the switching element 2.

The current source 4 is for generating a current corresponding to the ultrasonic reception signal.

[Action]

The present invention, as shown in FIG. 1, performs tap switching to any one of the switching elements 2 by a gradually changing selection signal generated by a selection signal generating circuit 3 and receives ultrasonic waves supplied from a current source 4. A current corresponding to the signal is supplied to the corresponding tap of the delay line with a tap 1 so as to give a receiving dynamic focus.

Therefore, tap switching of the delay line 1 with taps is gradually performed, it is possible to prevent generation of switching noise at the time of tap switching, and to perform reception dynamic focus with a simple circuit configuration.

〔Example〕

Next, the configuration and operation of one embodiment of the present invention will be sequentially described in detail with reference to FIGS. 1 to 5.

In FIG. 1, the selection signal generating circuit 3 includes a level detector 3-1 which generates selection signals Y ₁ to Y _n corresponding to the level of the control signal l _i , and the generated selection signals Y ₁ to Y _n.
It is composed of an LPF (low-pass filter) 3-2 that removes steep signal components from.

The level detector (window comparator) 3-1 is provided with a control signal generating circuit shown in FIG. 3 which will be described later, in order to give reception dynamic focus to the ultrasonic wave reception signal received from the element i constituting the ultrasonic array element. The level of the generated control signal l _i is detected. The level of the control signal l _i sets the selection signal Y _i corresponding to the range of a certain voltage level V (l _i ) to the H level, as shown in FIG. As described above, the selection for selecting the tap of the delay line with tap 1 is performed by generating the analog control signal l _i corresponding to the reception dynamic focus by the circuit of FIG. 3 and further generating the selection signals Y ₁ to Y _n. Signal Y ₁ or
The circuit configuration for generating Y _n becomes extremely simple.

The LPF 3-2 removes the steep signal component of the pulse-shaped selection signals Y ₁ to Y _n generated by the level detector 3-1, and prevents the generation of switching noise. The selection signals Y ₁ to Y _n from which the steep signal components have been removed are input to the bases of the transistors forming the switching element 2.

The amplifier 5 amplifies the ultrasonic wave reception signal delayed by the tapped delay line 1.

Next, the operation of the configuration shown in FIG. 1 will be described with reference to FIG.

Control signal l _i for giving reception dynamic focus
Input to the level detector 3-1, the corresponding selection signal Y ₁
Is set to the H level, the selection signal Y _j of the H level has been set to the L level, and the steep signal components of these signals are removed by the LPF 3-2. Then, as shown in FIG. Are input to the bases of the corresponding transistors constituting the. As a result, as shown in FIG.
The transistor TR _i to which the L-level to H-level selection signal Y ₁ is input is gradually turned on, and the transistor TR _j to which the H-level to L-level selection signal Y _j is input.
Gradually becomes a non-conducting state, the tap switching is smoothly performed, and it is possible to prevent switching noise from being mixed into the ultrasonic wave reception signal as in the conventional case. Here, the frequency component for removing the steep signal component by the LPF 3-2 is such that it does not affect the ultrasonic reception signal, and for example, frequencies above about 2 MHz are removed.

The generation of the control signal l _i will be described in detail with reference to FIG. The circuit shown in FIG. 3 is a circuit for generating a control signal l _i for giving a receiving dynamic focus to each element constituting the ultrasonic array element by using a simple configuration.

In FIG. 3, a counter 5 counts clocks in synchronization with a drive signal which is a timing pulse for radiating a pulsed ultrasonic signal from an ultrasonic array element. The counted clock corresponds to the time from the time when the ultrasonic beam is emitted to the living body.

ROMs (1) 6-1 to 6-4 are read-only memories, and are delay times required to give reception dynamic focus as data in association with addresses (clocks counted by the counter 5). The control signal corresponding to is stored in advance.

The D / A (1) 7-1 to 7-4 convert the data read from the ROM (1) 6-1 to 6-4 into an analog signal.

The control signal (analog) l _i is a control signal given to each of the ultrasonic array elements 0 to (n / 2-1) and (n-1) to n / 2 for receiving dynamic focus. These control signals l _i are generated from D / A (1) 7-1 to 7-4 using, for example, control signals at four points,
A control signal to be given to another corresponding element is generated in such a manner that the points are proportionally distributed using the resistor network shown. This simplifies the circuit configuration.

Next, the operation will be described.

In FIG. 3, after inputting a drive signal to the counter 5 to clear the counter 5, the clock is counted and the ROM
(1) Enter the address in 6-1 to 6-4. Corresponding to this, the read data is transferred to D / A (1) 7-1 to 7-4.
To a control signal l _i for each element i by a resistor network. Thus, for one line of ultrasonic waves, the delay time corresponding to the control signal l _i with respect to the ultrasonic wave reception signal received from each element is set to the first delay time so that the reception focus position is sequentially moved with the passage of time. Given by the diagram circuit.

FIG. 4 is an operation explanatory diagram of the level detector 3-1. The level detector 3-1 detects the level range of the control signal l _i generated by the circuit of FIG. 3 and sets the corresponding selection signal Y _i to the H level as shown.

FIG. 5 shows an example of reception direction and dynamic focus addition. This is a main part of a circuit configuration for controlling the reception dynamic focus and the reception direction of ultrasonic waves using one tapped delay line 1. In this way, the control signal l _i generated using the circuit of FIG. 3 and the signal corresponding to the reception direction generated using the FF (flip-flop) 8 and D / A 9 are added using the adder 10. After that, the level detector 3-1 and the LPF3-2 in FIG. 1 (not shown), the switching element 2, and the delay line 1 with a tap are used to control the delay corresponding to the reception dynamic focus and the reception direction together. Good.

〔The invention's effect〕

As described above, according to the present invention, since the taps of the tapped delay line 1 are gradually switched, it is possible to prevent switching noise from occurring at the time of tap switching. Moreover, in order to generate the control signal l _i for switching the taps, the values for all the other elements are generated by the proportional distribution by the resistor network from the analog values for the plurality of elements. It becomes possible to focus.

[Brief description of drawings]

FIG. 1 is a configuration diagram of one embodiment of the present invention, FIG. 2 is an operation explanatory diagram of the present invention, FIG. 3 is an example of a control signal generating circuit according to the present invention, FIG. 4 is an operation explanatory diagram of a level detector, FIG. 5 shows a receiving direction and an example of dynamic focus addition, and FIG. 6 is an explanatory view of the prior art. In the figure, 1 is a delay line with a tap, 2 is a switching element, 3 is a selection signal generating circuit, 3-1 is a level detector, and 3-2.
Is LPF, 5 is counter, 6-1 to 6-4 is ROM, 7-1 to 7
-4 and 9 represent D / A, 8 represents FF, and 10 represents an adder.

Claims (1)

[Claims] 1. A tap having a tap for adjusting a delay time of an ultrasonic reception signal received by each array element in an ultrasonic reception dynamic focus circuit for dynamically varying a focus position received by using an array element. And a switching element (2) for adjusting the delay time so as to perform reception dynamic focus by switching to any tap of the delay line with taps (1). ) Is supplied with a gradually changing selection signal to gradually switch from one tap to another tap to suppress switching noise and perform reception dynamic focus. Receive dynamic focus circuit.