JPS60114243A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus that examines the inside of a subject by transmitting and receiving ultrasonic signals.

Conventional Structure and Problems Conventionally, as shown in FIG. 1, an it'r (sonic wave diagnostic device) has been proposed which has a mechanical fan-shaped scanning mechanism whose main component is an eccentric cam.

In FIG. 1, a wave transmitting/receiving section 1 for transmitting and receiving ultrasonic waves is connected to a scanning shaft 2, and the scanning shaft 2 is connected to a swing link 3. The eccentric cam sid, %, dynamic IQb is rotated by a motor 7 via 6, and is connected to a long hole provided in the swing link 3 by a pin 4 provided on the eccentric cam 5. As a result, the swing link 3 performs a reciprocating rotational movement around the scanning axis 2, and in conjunction with this, the wave transmitting/receiving unit 1
A mechanical sector scan is performed for 5. The amount of rotational angle of the scanning shaft 2 is converted into an angular output by a rotary potentiometer 8.

The exposed probe case 9 protects the necessary parts of the scanning mechanism. The drive pulse generated by the transmitter 20 is applied to the wave transmitting/receiving unit 1 via the signal line 1Q, converted into a 1lfl sound pulse, and transmitted into the subject 35. Conversely, the echo ultrasound signal from the subject 35 is converted into a reception signal by the wave transmitting/receiving section 1, processed by the reception circuit 21 via the signal line 10, and written to the image memory 22 as a detection output.

The memory address of the image memory 22 is determined based on the angle output of the rotary potentiometer 8. Image memory 22
The read result can be displayed on the monitor 23.

In this manner, the above-described scanning mechanism mechanically scans the wave scanning/receiving section 1 in a fan shape by rotating the motor 7 at a constant speed. This method has the advantage that the motor can be controlled more easily than the method in which the wave scanning/receiving section is directly fan-shaped scanned by reciprocating the motor. However, the above method using an eccentric cam has a problem in that the scanning speed is extremely different in both directions, as described below.

FIG. 2 is a conceptual diagram showing the relationship between the rotation angle θ of the scanning shaft 2 and the rotation angle φ of the eccentric cam 5. In FIG. 2, the angle φ=0 degrees corresponds to the position of the bin 4 furthest from the scanning axis 2. At that time, the wave transmitting/receiving unit 1 is located at the center of the fan-shaped scanning area, and its angle is set to θ-0 degrees. If the distance between the pin 4 and the drive shaft 6 is R, and the distance between the drive shaft 6 and the scanning axis 2 is D, then D-sin θ=R・5in(φ-θ) (1) Scanning/receiving section 1
If the maximum deflection angle of is θmax (degrees), then sinθ,. ,=R/D (2). From the above relationship, when the drive shaft 6 rotates at a constant speed, the scanning frame in which the bin 4 passes through φ-
It can be seen that there is a difference between 1 and +i required for scanning one frame between frames scanned through 180 degrees. φ−○
The period of one frame of scanning when passing through φ-180 degrees will be referred to as a low-speed frame, and the period of scanning when passing through φ-180 degrees will be referred to as a high-speed frame. The maximum value of the scanning speed in both frames is φ-0 degrees.

It is also shown to occur at 180 degrees. The scanning speed %t is expressed by the rotational speed of the drive shaft 6φ4t, and is as follows.

dθ/dt=(cos2θ・(1+(D/R)・cos
φ)/(D, IR-1-00Sφ)2)・dφ/dt
(3) Specifically, when θm1LX=20 degrees, there is a difference of nearly twice the value of Δθ between φ=○ degrees and 180 degrees, and this difference increases as θmax increases. Therefore, if the number of transmissions is kept constant, the acoustic scanning line density will be extremely different between low-speed frames and high-speed frames. In other words, the density of scanning lines transferred to the image memory 22 will be different between low-speed frames and high-speed frames. For example, if the minimum necessary scanning line density to complete an image is secured in high-speed frames, the scanning line density in low-speed frames will be different. On the other hand, if the minimum necessary scanning line density was secured in the low-speed frame, the scanning line density would be insufficient in the high-speed frame, making it impossible to complete the image.

OBJECTS OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and when performing mechanical sector scanning using an eccentric cam, it is possible to It is also an object of the present invention to provide an ultrasonic diagnosis and diagnosis apparatus that can set the scanning line density to an optimum value without being insufficient or unnecessarily excessive.

Structure of the Invention In order to achieve this object, the present invention provides a direction detecting section for detecting whether the mechanical sector scan is in a slow frame or a fast frame, and writes the detection output to the image memory at a slow speed. A writing control unit is provided that is enabled only when the frame is in the frame, and the rotational speed of the eccentric cam is increased as much as possible while maintaining a minimum scanning line density of 1.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram showing an ultrasonic diagnostic apparatus according to an embodiment of the present invention, and FIGS. 4(a) and 4(b) are timing diagrams of the direction detecting section of the apparatus. In Fig. 3, 1 is a wave transmitting/receiving unit, 2 is a scanning axis, 3 is a swing link, 4 is a pin, 5 is an eccentric cam, 6 is a drive shaft, 7 is a motor, 8 is a rotary potentiometer, and 9 is a probe. case, 20 is transmitter, 3
Reference numeral 5 denotes a subject, and the echo ultrasound signal reflected within the subject 35 is converted into a received signal by the wave transmitting/receiving unit 1 and sent to the signal line 10.
is processed in the receiving circuit 21 via the image memory 2.
recorded in 2. The A/D converter 12 converts the angular output of the rotary potentiometer 8 into a digital quantity. A/D
As the resolution of the converter 120, l'i of about 8 to 10 bits is selected. The output of A/D converter 12 is used to calculate a memory write address in image memory 22.

Further, the output of the A/D converter 12 is temporarily recorded by a latch 13. As shown in the timing diagram of FIG. 4(A), A/
The conversion timing TO of the D converter 12 ((A) in the same figure) and the clock timing TL of the latch 13 ((A) in the same figure)
)'s (・→) are synchronized.

If each output of the A/D converter 12 is Dl (1-integer) shown in (0) of the same figure (A), the data Di-+ of one clock ago in the latch 13 (in the same figure (A)) ) can be recorded. Therefore, the comparator 14 performs A/D conversion? By comparing the magnitude of each output of the rotary potentiometer 8 and the latch 13, it is detected whether the angular output of the rotary potentiometer 8 is increasing or decreasing over time. Assuming that the rotational direction of the motor 7 is constant, the scanning direction of the wave scanning/receiving section 1 can be detected simply by checking the output of the comparator 14. In the above example, the A/D converter 12. Latch 13. The comparator 14 constitutes a direction detection section 16. An n-FF (D-flip-flop) 15 holds the result of the comparator 14.

The D-FF 15 also operates at the clock timing TL indicated by (/→) in FIG.

In this case, the D-FF 15 constitutes a write control section.

With the above configuration, in mechanical fan-shaped scanning using the eccentric cam 5, it is possible to write the detection output to the image memory 22 only in one direction of scanning. D
- By selecting the polarity of the output of F'F15, the entire detection output is written into the image memory 22 only during low-speed frames, and the rC image is displayed on the monitor 23 based on this.

With this configuration, while maintaining a high number of frames, images with no gaps and short rewriting time can be created.
・I can do things. Furthermore, it is possible to solve the problem of frame-by-frame image shift, which is peculiar to mechanical scanning and reciprocating image display.

Furthermore, based on the results of the direction detection unit 16, the number of times the human body is irradiated with ultrasound can be reduced by stopping the transmission of ultrasound during high-speed frames.

The timing diagram shown in Figure 4 (B) is the timing diagram (A).
This is an example. The clock timing TL of the latch 13 is as shown in () →
As shown in 1/M (M: natural number), in this case A
The frequency is divided into Therefore, the input of latch 13 is
When Dl is shown in (b) of ), there is a clock timing at which data Di-M (in (B) of the same figure)) of M clocks earlier is recorded in the latch 13. In this way, at the lock timing, the difference in the angle outputs of the rotary potentiometers 8 compared in the ratio unit 14 becomes large, and even if the angle output has noise of 101 m, the comparator 14 outputs an incorrect result. 'Efficiency decreases. Based on the above timing diagram (B), the eccentric cam 5
Even in mechanical sector scanning using , it is possible to input the detection output τη into the image memory 22 only during low-speed frames.

As a specific example, the rotational speed of the eccentric cam 5 is set to 4 times for 40 seconds, the period of the drive pulse is set to 4kHz, and the deflection angle of the wave transmitting/receiving unit 1 is set to ±20.
degree. Since the rotation angle of the eccentric cam 60 for one transmission period fij is Δφ - 0.36 degrees, from equations (1) and (2), the acoustic scanning line density at the center of the fan-shaped scan of the slow frame is Δθ - 0,092 degrees/ It becomes a book. It is assumed that this scanning line density allows information to be integrated into the image memory 22 without any gaps, and that if the scanning line density is lower than this, gaps will occur.

In this state, if the detection output is written to the image memory 22 only in low-speed frames, images at 4 frames per second can be obtained.

Writing in high-speed frames also seems to increase the number of frames per second, but the acoustic scanning line density at the center of the fan-shaped scan in high-speed frames is Δθ - 0.187 degrees/line, which is significantly lower than that in low-speed frames. rough. For this reason, images written in high-speed frames have many gaps and become unsightly. In order to obtain an image without gaps in a high-speed frame, the rotation speed of the eccentric cam 5 should be set to 4 minutes and 2 seconds.
You have to go down to the top. Therefore, in this case as well, 4
An image of the frame is obtained. However, in the input/output method using only low-speed frames, no problem occurs even if the drive pulses are stopped during high-speed frames, which is desirable in consideration of the effect on the human body. In addition, since writing to the image memory 22 is performed only during low-speed frames, the method of reading one frame of image memory while bending over is not suitable for the monitor 2.
The image displayed in 3 is easy to see. Because information obtained by scanning in a constant direction is always displayed, there is little positional shift in images between frames. On the other hand, when displaying both forward and backward images, there was a problem that the image would shake in the frame due to mechanical play, deformation, vibration, etc., but this embodiment eliminates these problems. There isn't.

FIG. 5 is a block diagram showing an ultrasonic diagnostic apparatus in another embodiment of the present invention. In the figure, 1 is a wave transmitting/receiving unit, 2 is a scanning axis, 3 is a swing link, 4 is a pin, 5 is an eccentric cam, and 6
1 is a drive shaft, 9 is a motor, 9 is a probe case, 20 is a transmitter, and 35 is a subject. The echo ultrasound signal reflected within the subject 35 is converted into a reception signal by the wave transmitting/receiving unit 1. The signal is processed in the receiving circuit 21 via the signal line 10 and recorded in the image memory 22. A rotary encoder 30 is provided to the motor 7 via a reduction gear head 19. The rotary encoder 3o has a fixed number of pulses per rotation, for example, 256 phase pulses P1 and 1 synchronization pulse P2.
Output. It is possible to synchronize the timing at which the pulse P2 is output with the start of the low-speed frame. It is assumed that a total of N phase pulses are output at the end of the scan of the low-speed frame. Therefore, the counter 31 calculates the phase pulse P
1, and compare this count value with the value of N above in the comparator 14.
By comparing the values, it can be determined from the output of the comparator 14 whether the scanning is in a low-speed frame or not.

It is assumed that the counter 31 is cleared by the synchronization pulse P2. In this example, the counter 31 and the comparator 14 constitute the direction detection section 16. D-FF1s holds the result of the comparator 14. D-FF15 operates in synchronization with phase pulse P1. The output of D-FF1s controls memory writing in the image memory 22. In this way, D-FF
15 constitutes a write control section. With the configuration described above, in mechanical sector scanning using the eccentric cam 5, the detection output is written into the image memory 22 only during low-speed frames, and the image is displayed on the monitor 23.

The PLL (phase locked loop) 32 detects the phase difference between the output of the stable oscillator 33 divided by the L frequency division counter 34 and the phase pulse output of the rotary encoder 30, and and give feedback. In this way, the rotational speed of the eccentric cam 5 can be controlled more precisely. The oscillator 33 outputs NXL pulses during the low-speed frame. By counting the output of the oscillator 33, it is possible to more precisely determine the rotation angle φ of the eccentric cam 6, that is, the angle θ of the scanning axis 2, and based on the angle θ determined in this way, Memory ingress and egress addresses are calculated. In order to calculate the angle θ from the angle φ, the calculation shown in equation (2) is required.
Even if it is expressed in IT, a childish conversion table copy, for example, a 1sKbit ROM is sufficient.

In this example, the same effects as in the previous example were obtained.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention enables direction detection for detecting low-speed frames in mechanical sector scanning using an eccentric cam, and control for recessing the detection output into the image memory only when the low-speed frame is present. As a result, it is possible to obtain images with no gaps and a short 1 μ changing time while maintaining a high number of frames, and by avoiding unnecessary driving of the wave transmitting and receiving unit, it is possible to reduce the risk of damage to the human body. It is also possible to reduce the number of ultrasound irradiations. There is also less possibility of occurrence of problems such as frame-by-frame image shift, which is common in reciprocating image display in mechanical scanning.

[Brief explanation of the drawings] Fig. 1 is a block diagram showing a conventional ultrasonic diagnostic device;
The figure is a conceptual diagram of a conventional scanning mechanism, FIG. 3 is a block diagram of an ultrasonic diagnostic device according to an embodiment of the present invention, FIG. 4 is a timing chart of the same device, and FIG. 5 is another embodiment of the present invention. It is a block diagram of the ultrasonic diagnostic device in . 1-... Wave transmitting/receiving section, 3-... Swinging link, 5-
・Eccentric cam, 7...Motor, 8...Rotating potentiometer, 12-...A/D converter, 13...Latch, 14...Comparator, 15...- D-FF(
correction control unit), 16... one-way detection unit, 20...-
...Transmitter, 21...-Receiver, 22...--Image memory, 30...--Low reencoder, 31
····counter. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 4 (8) (β Di, -Mn ρ3 Figure 5 -\ 20 2/ 2'2' 23 5

Claims (1)

[Claims] a wave transmitting/receiving unit that transmits and receives ultrasonic waves; a scanning axis connected to the wave transmitting/receiving unit; and a swing link connected to the scanning axis;
An eccentric cam that causes the swing link to perform a reciprocating rotational movement with the scanning axis as the central axis, a motor that causes the eccentric cam to perform a rotational movement, and a detection output obtained by processing the received signal from the wave transmitting/receiving unit. . Ultrasonic diagnostic equipment.