JPS624981B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic scanning ultrasonic diagnostic apparatus.

Conventional electronic scanning ultrasonic diagnostic equipment has the disadvantage that false echoes appear when there is a strong reflector in the distance. For example, in FIG. 1, when the ultrasonic transducer 11 is scanned in the order of 1, 2, 3, and 4, the reflected echo signal of the pulse transmitted to display the scanning line 1 is reflected from the distant reflector 12. When the echo signal of is strong, due to its time delay,
It overlaps with the echo signal for displaying the next scanning line 2 to form a pseudo echo, which is displayed as if there was a reflector at a nearby location 13 indicated by a dotted line.

An object of the present invention is to provide an improved electronic scanning ultrasonic diagnostic apparatus in order to reduce false echoes caused by strong echo signals from a distance.

In order to achieve the above object, the present invention continuously transmits and receives mutually symmetrical deflection angles θ and -θ at the same delay time, and then changes the delay time setting to transmit and receive other mutually symmetrical deflection angles. It is characterized in that it is configured to continuously execute transmission and reception regarding the corners. For example, as shown in FIG. 2, scanning is performed from the center to the periphery in the order of θ ₁ , −θ ₁ , θ ₂ , −θ _{2 .} . . while skipping left and right alternately, or as shown in FIG. From the periphery to the center θ _o , −θ _o , θ _o-
1 , -θ _o-1 , . . . in the order of scanning while alternately skipping left and right.

According to the present invention, compared to the conventional sequential scanning method, since echoes from the previous scanning line are not picked up all at once, the influence of pseudo echoes can be reduced. Furthermore, compared to the random scanning method, this method is superior in that in the case of a fast-moving image, there is less discontinuity in the image between scanning lines, and a smooth image can be obtained. The user usually brings the most interesting and important part of the image to the center of the image plane, but according to the present invention,
The time difference between adjacent scanning lines at the center is 1 in the case of Fig. 2, and 1 in the case of 5 and 6 in Fig. 3, each being one scanning interval. The smallest time difference between adjacent scan lines even in the part far from the center is two scan intervals,
The time difference does not exceed this, and a very clear image can be obtained as a whole.

Next, an embodiment of the present invention will be described based on the circuit block diagram of FIG.

In the figure, 1 is a drive pulse generator, 2 is a delay circuit, 3 is a multiplexer, 4 is a pulser, and 5 is a summing amplifier. 2
-1, 2-2...2-32 causes a time difference and is transmitted from the transducer in a predetermined beam direction, and the echo signal passes through the same delay circuit again and is taken out to the summing amplifier 5, where it is sent to various processing circuits. sent to. The multiplexer 3 selects delay circuit terminals 0-1, 0-2, ...0-32 when the selection signal S is "0".
and pulsers 4-1, 4-2...4-32 are connected respectively, and when S is "1", delay circuit terminals 1-1,
1-2,...1-32 and pulsa 4-1, 4-2...
...Connect 4-32 respectively. Therefore, if delay circuits 2-1, 2-2...2-32 are each set to a predetermined delay time, and the beam deflection angle at that time is θ, then without changing the state of the delay circuits, By switching the control terminal signal S, the beam deflection angle can be switched to -θ.

The counter 6 counts clock pulses, and the lower 5 bits _A1 are outputted as a delay line selection address signal, and the remaining upper half bits _A2 are outputted as a deflection address signal. The decoder 7 receives a delay circuit designation signal using the delay line selection address signal.
Output L ₁ ...L ₃₂ . Data that provides a predetermined delay time to the delay circuit is read from the ROM (read only memory) 8 in accordance with the delay line selection address signal _A1 and the deflection address signal _A2 . The control circuit 9 controls switching of the selection signal S of the multiplexer 3 in synchronization with the change in the state of the counter 6.

The setting of the delay time of the delay circuit 2 and the switching of the multiplexer 3 are performed alternately. When the selection signal S of the multiplexer is "0", the counter 6 counts the clocks, and when the deflection address A ₂ corresponds to the deflection angle θ ₁ , the delay line selection address
A ₁ advances sequentially, and the decoder 7 accordingly advances L ₁
to L ₃₂ sequentially and output to delay circuits 2-1, 2-
2,...2-32 are selected. In parallel with the selection, the ROM 8 outputs delay time data, and a predetermined delay time is set in each delay circuit. Next, the drive pulse generator 1 operates to generate pulses, the pulser 4 is driven and an ultrasonic wave with a deflection angle θ is transmitted, and the echo signal is received by the summing amplifier 5 and subjected to appropriate signal processing. Is displayed. Next, the selection signal S is switched to "1" without changing the state of the delay circuit 2, and the ultrasonic wave is transmitted at a deflection angle of -θ ₁ , received and displayed. Here, the contents of the deflection address _A2 are incremented to the one corresponding to the deflection angle _θ2 , and the decoder 7 sends L1 to _L1 as before.
Output _L32 and rewrite the delay time of delay circuit 2. Then, transmission and reception of the deflection angle θ ₂ are executed at S=0, and then transmission and reception of the deflection angle −θ ₂ are executed at S=1. Similarly, θ ₃ , −θ
Scanning is performed in the order of ₃ , θ ₄ and -θ ₄ .

As another embodiment of the present invention, the present invention can be implemented in a linear ultrasonic diagnostic apparatus by simply changing the contents written in the ROM.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional scanning method, FIGS. 2 and 3 are diagrams showing a scanning method according to the present invention, and FIG. 4 is a circuit block diagram showing an embodiment of the present invention. 1... Drive pulse generator, 2... Delay circuit, 3
... multiplexer, 4 ... pulser, 6 ... counter, 7 ... decoder, 8 ... ROM, 9 ... control circuit.

Claims (1)

[Claims] 1. In a device that transmits and receives ultrasonic waves at a predetermined deflection angle by providing a delay circuit for each ultrasonic transducer, a circuit switching device is interposed between the ultrasonic transducer and the delay circuit, and a circuit switching device is interposed between the ultrasonic transducer and the delay circuit, and A device for setting predetermined delay time data is provided, and with the delay time corresponding to the predetermined deflection angle θ set in each of the delay circuits, the circuit switching device is operated to change the deflection angle θ and its symmetrical deflection angle −θ. An ultrasonic diagnostic apparatus configured to continuously transmit and receive a pair of deflection angles that are symmetrical to each other while sequentially changing the deflection angle θ.