JPH0222656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a mechanical scanning ultrasonic diagnostic device that mechanically scans ultrasonic pulses in a fan shape to obtain ultrasonic tomographic images and diagnose living bodies. be.

Configuration of conventional examples and their problems Mechanical fan-shaped scanning ultrasonic diagnostic equipment generally transmits ultrasonic pulses by applying a pulse voltage to a vibrator made of piezoelectric material, and generates echoes due to differences in acoustic impedance from the subject. A B-mode image is obtained by changing the direction of the transducer in a fan shape in order to receive the ultrasonic pulse and simultaneously deflect the transmitted and received ultrasonic pulse. An example is shown in FIG. As shown in FIG.
1, and is deflected by rotating it around this shaft 12. l is the scanning area. Power for this rotation is applied from a motor 14 having a rotational position/rotation speed detection means 13 typified by a rotary encoder via a transmission means 15 such as a pulley, belt, gear, or the like. Rotational position/rotational speed detection means 13
is the angle θ between the reference position 21 of the rotating body 11 and the scanning start position 0/8, as in the example shown in FIG. 2a.
Generally, the angle θ of the rotating body 11 and the angle of the rotational position/rotational speed detection means 13 shown in FIG. The signal detected from here is =θ=
0, that is, the transducer _P0 Consists of pulse A shown in the figure c, which is generated when the transmission and reception direction of the ultrasonic pulse coincides with the starting point of scanning area l, and pulse B, which is generated at every minute constant angle of θ and The angle θ of the rotating body 11 can be determined from pulses A and B by using a counter or the like, and the pulse B is used to operate a servo circuit that keeps the rotating body 11 at a constant rotation.
Transducer P ₀ is the starting position of the scanning area θ = 0/8
Rotate clockwise from point , pass through point 1/8, and reach point 2/8. Up to this point, the four oscillators P ₀ to P ₃
Of these, only P ₀ is used for transmitting and receiving ultrasonic pulses.
When the transducer P ₀ exceeds 2/8, the transmission and reception by the transducer P ₀ is stopped, and at the same time the transducer entering the scanning area
Waves are transmitted and received by P ₁ , and when reaching 4/8, the wave transmission and reception is switched to oscillator P ₂ . This kind of behavior is
An electronic switch is provided to switch the oscillators P ₀ to _{P 4} .
From the angle θ obtained from pulses A and B, 0/8, 2/8, 4/8,
The electronic switch S may be controlled so as to sequentially switch from P ₀ to P ₁ to P ₂ to P ₃ at the 6/8 position.

However, in this method, the rotational accuracy of the rotating body 11 is affected by the number of pulses B per rotation of the rotational position/rotational speed detection means 13, and the number of ultrasonic pulses transmitted and received per pulse B increases. The accuracy of the deflection angle θ decreases as the angle increases. Figures 1 and 2
In the example shown in the figure, 100 ultrasonic pulses are transmitted and received within the scanning area l, and the pulse A is transmitted from the rotational position/rotational speed detection means 13 once per rotation.
When pulse B is output 100 times per revolution,
For 100 ultrasonic pulses transmitted and received within the scanning area l, only 25 pulses are obtained from the rotational position/speed detection means 13, and only 4 pulses can reliably control the speed of the motor 14 and rotating body 11. In the case of fan-shaped scanning, image distortion is particularly large in long-distance portions, and diagnostic accuracy is reduced. Therefore, it is desirable that the rotational position/rotational speed detection means 13 has a high angular resolution that outputs more pulses B per rotation, but in reality, there is a limit to the number of pulses output per rotation. It becomes expensive.

Purpose of the Invention The present invention has been made to solve the above-mentioned problems.
The aim is to obtain an ultrasonic tomographic image with less distortion by improving the deflection accuracy of ultrasonic pulse transmission and reception. It is something to do.

Structure of the Invention The present invention has been made to achieve the above object, and includes a rotating body that holds and rotates at least one ultrasonic transducer, a driving means for driving the rotating body, and a rotating body that rotates with the driving means. a deceleration transmitting means connected to the driving means and transmitting the deceleration of the rotation of the driving means to the rotating body; a rotating body position detecting means for detecting a rotation reference angle of the rotating body with low precision; and a rotating body position detecting means connected to the driving means and driving the rotating body. A rotational position/rotation angle detection means for detecting the rotational position of the means with high precision, and a scanning range of the ultrasonic transducer and the ultrasonic transducer based on signals from the rotating body position detection means and the rotational position/rotation speed detection means. The present invention provides a mechanical scanning ultrasonic diagnostic apparatus characterized by comprising means for selecting.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 shows an overview of a mechanical scanning ultrasonic diagnostic apparatus according to an embodiment of the present invention.

In the figure, 10 is a vibrator, 11 is a rotating body, 1
2 is a rotating shaft, 13 is a rotational position/rotational speed detection means, 14 is a motor, 31 is a deceleration transmission means, and 32 is a rotating body position detection means.The features of this embodiment are as follows.
The power from the motor 14 causes the pulley, belt,
The rotary body 11 is driven through a deceleration transmission means 31 consisting of a combination of gears, etc., and a rotary body position detection means 32 that generates one pulse at a certain angle of the rotary body 11 is added. The rotating body position detection means 32 uses a combination of an LED and a photodetecting element, or a combination of a magnet and a magnetic detection element, and has the same speed and the same rotation angle as the rotating body 11, or a device that has the same speed and the same rotation angle as the rotating body 11. The present invention is characterized in that a target 32a is attached to the target 32a, and a detection means 32b for detecting the target is configured to detect a constant rotation angle of the rotating body 11.

FIG. 4 shows a control circuit configuration diagram of the above embodiment.
The pulses from the rotating body position detection means 32 and the rotational position/speed detection means 13 operate the N-ary counter 41 which controls the electronic switch 43 which switches the oscillators P ₀ to P ₃ . Although the vibrators P ₀ to P ₃ are actually provided on the circumference of the rotating body 11, they are shown at positions apart from the rotating body 11 in this figure for convenience of explanation. The electronic switch 43 is used to select a transducer within the desired scanning area, and through it sends the transmitting voltage from the device control unit 44 to any of the transducers P ₀ to _{P 3} within the scanning area to produce an echo. Upon receiving the signal, a tomographic image is formed in the device control section 44 and displayed on the display section 45 . In addition, the rotational position/speed detection means 13
is a signal for controlling the motor control section 42 such as a PLL, and rotation control can be performed from the device control section 44 at an arbitrary speed. Here, if the reduction ratio of the reduction transmission means 31 is 1/N, the change in the motor angle with respect to the change in the angle θ of the rotating body 11 will be N times. FIG. 5 shows a time chart of the positional relationship between the rotating body 11 and the rotational position/speed detecting means 13 and the driving pulse thereof when N is 8 as an example.

In FIGS. 5a and 5b, if the angle θ of the rotating body 11 changes the scanning area from 0/8 to 2/8, the change in the angle of the rotational position/speed detection means 13 will be 2 rotations. . Now, assume that the transducer P ₀ starts scanning from the scanning start position 0/8. When the oscillator P ₀ has rotated to 1/8, it completes one revolution and generates the A pulse shown in c in the figure once. If it is completed to 2/8, it will complete one rotation again and generate pulse A. In this way, θ rotates once every 1/8, and pulse A is generated. Therefore, the number of pulses B for operating the servo circuit of the motor 14 is also eight times greater than in the case without the deceleration transmission means 31 shown in the conventional example, and control can be performed twice per scanning line. This becomes the time relationship shown in Figure 6, and each oscillator P ₀ ~
High precision control can be achieved by switching P ₃ to the scanning area I every 2/8 of θ using the electronic switch S. The electronic switch S is set so that the pulse C is detected once from the rotating body position detection means 32 when θ is between 0/8 and 1/8 (see Fig. 6A). ), this pulse C and the pulse A mentioned above (see Fig. 6B) are combined into the fourth
By using the octal counter 41 shown in the figure as a reset and a clock, respectively, it is possible to know the position of the angle θ of the rotating body 11 from the counter output K in FIGS. 4 and 6 C. , it becomes possible to switch the electronic switch 43 from here (see FIG. 6D). In general, the counter 41 that knows the rotational position includes the deceleration transmission means 31.
If the reduction ratio is 1/N, an N-ary counter is used. Further, the rotating body position detecting means 32 only needs to have such accuracy that the rotational position/rotational speed detecting means 13 can be reset during one rotation. Here, a so-called rotary encoder is used as an example of the rotational position/rotational speed detection means 13, but the present invention can also be applied to a rotary encoder that generates, for example, a sinusoidal voltage depending on the angle. Similarly, in the case of Figure 7, which has only one vibrator, the reduction ratio is set to 1/4, and the solid line indicates 0/8 to 2/8.
This can be seen as the same as when P ₁ to _{P 3} of the embodiment shown in FIGS. 3 and 4 are removed. The time chart at this time is shown in Figure 7b. By further expanding the scanning area l from 0/8 to 2/8 shown by the solid line and scanning the circular scanning area from 0/8 to 2/8 shown by the broken line, A circular tomographic image is obtained.

Effects of the Invention In summary, the present invention provides a rotary body that holds and rotates at least one ultrasonic transducer, a drive means that drives the rotary body, a drive means that is connected to the rotary body, and a rotating body that rotates the drive means. a deceleration transmission means for decelerating and transmitting the deceleration to the rotating body; a rotating body position detecting means for detecting a reference rotation angle of the rotating body with low accuracy; and a rotating body position detecting means connected to the driving means and detecting the rotational position of the driving means with high accuracy. The apparatus further comprises a rotational position/rotation angle detection means, and a means for selecting the scanning range of the ultrasonic transducer and the ultrasonic transducer based on the signals from the rotating body position detection means and the rotational position/rotation speed detection means. The present invention provides a mechanical scanning ultrasonic diagnostic device characterized by Even if the same rotational position and rotational speed detection means are used, rotation control can be performed with high accuracy, and images with less distortion can be obtained.

[Brief explanation of drawings]

FIG. 1 is an overview diagram of a conventional mechanical scanning ultrasonic diagnostic device, and FIGS. 2 a and b are diagrams showing the positional relationship between the rotating body and the rotational position/speed detection means of the conventional device.
Fig. 2c is a time chart thereof, Fig. 3 is an overview diagram of a mechanical scanning ultrasonic diagnostic apparatus in an embodiment of the present invention, Fig. 4 is a diagram showing the control circuit configuration of the apparatus in the above embodiment, and Fig. 5 Figures a and b are diagrams showing the positional relationship between the rotating body and the rotational position/rotational speed detection means of the apparatus in the above embodiment, Figure 5c is its time chart, and Figures 6A to 6H are the apparatus in the above embodiment. FIG. 7 is a time chart showing the control relationship, and FIG. 7 is for explaining a mechanical scanning ultrasonic diagnostic apparatus according to another embodiment of the present invention. FIG. It is. 10... Vibrator, 11... Rotating body, 12... Rotating shaft of rotating body, 13... Rotational position/rotational speed detection means, 14... Motor, 15... Transmission means, 31
... Deceleration transmission means, 32 ... Rotational position detection means,
41... Vibrator selection N-ary counter, 42... Motor control unit, 43... Vibrator selection electronic switch, 4
4... device control section, 45... display section.

Claims (1)

[Claims] 1. A rotating body that holds and rotates at least one ultrasonic transducer, a driving means that drives the rotating body, and a device that is connected to the driving means and the rotating body, and decelerates the rotation of the driving means and transmits it to the rotating body. a deceleration transmission means, a rotating body position detecting means for detecting a rotation reference angle of the rotating body with low accuracy, and a rotational position/rotational speed detecting means connected to the driving means and detecting the rotational position of the driving means with high precision. , a mechanical scanning ultrasonic device comprising means for selecting a scanning range of an ultrasonic transducer and an ultrasonic transducer based on signals from the rotating body position detecting means and the rotational position/rotational speed detecting means. Sonic diagnostic equipment.