JPH04129542A - Ultrasonic probe - Google Patents

Abstract

PURPOSE:To efficiently irradiate the ultrasonic beam without increasing the impedance and improve reception sensitivity by forming a sheath top edge to an acoustic window through which ultrasonic wave transmits, installing an ultrasonic vibrator element along the inner wall of the acoustic window, and installing an acoustic lens which is formed so as to allow the received ultrasonic wave to converge and be irradiated, in turnable manner in opposed state to the ultrasonic vibrator element inside the sheath top edge part. CONSTITUTION:The ultrasonic beam irradiated from ultrasonic vibrator elements 2b and 2c radiates on the spherical surface of an acoustic lens 4 where an ultrasonic absorbing member 7 is not installed, and is converged, and the substantially equivalent state to the ultrasonic vibrator element having a wide aperture is generated, and the transmission of the fine ultrasonic beam to a remote position is enabled. Further, since the ultrasonic vibrator elements 2b and 2c are installed along the inner wall of a sheath top edge part 1, a wide area can be secured and the impedance lowers, and the matching with the signal lines 3b and 3c can be easily performed. Further, the echo reflected from an inspected body transmits through the acoustic lens 4, and is received by the ultrasonic vibrator elements 2b and 2c, and since, in this case, the matching with the signal lines 3b and 3c is performed, the reception sensitivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasound probe that is used by being inserted into the forceps port of an ultrasound endoscope.

[Conventional technology]

It is well known that ultrasound endoscopes are used in the medical field. This ultrasound endoscope inserts an ultrasound probe into the body cavity through the forceps mouth, emits an ultrasound beam to the subject to be examined, receives echoes, processes the received signals with an observation device, and displays the image on a monitor. It is now possible to observe the situation. At the tip of the ultrasonic probe, there is provided an ultrasonic vibrator that includes a piezoelectric element, a matching layer, etc., and emits an ultrasonic beam when excited.

For example, Japanese Patent Laid-Open No. 64-2632 discloses a catheter having an outer diameter that can be inserted into a forceps channel of an endoscope, and a catheter that is attached to the distal end of the catheter and has an outer diameter that can be inserted into the forceps channel. A transendoscopically insertable ultrasound imaging system is disclosed that includes an ultrasound probe with a laterally oriented beam pattern to obtain the required ultrasound images.

[Problem to be solved by the invention]

However, the conventional ultrasound probe described above is formed to have a small diameter so that it can be inserted through the forceps port of the endoscope.
The ultrasonic transducer provided at the tip also needs to be small.

Therefore, the area of the ultrasonic transducer becomes small and the electrical impedance becomes high, making it impossible to achieve sufficient matching with the signal cable connected to the ultrasonic transducer. There is a problem in that the transmitted pulse for excitation cannot be efficiently converted into an ultrasonic signal.

In addition, echoes from the subject to be examined are received by an ultrasound transducer,
There is also a problem in that the receiving sensitivity is low when transmitting signals to observation equipment via signal cables.

In addition, since the incident area of the ultrasound beam is small and the exit aperture is small, the ultrasound beam exits (
There is a problem in that the ultrasonic images that are formed by processing the echoes have poor resolution.

The present invention is proposed to solve the above-mentioned problems.
To provide an ultrasonic probe that efficiently emits an ultrasonic beam without increasing the impedance of an ultrasonic transducer, improves receiving sensitivity, and improves resolution despite being a small-diameter ultrasonic probe. It is intended for this purpose.

[Means and effects for solving the problems] In order to achieve the above object, the present invention forms the sheath tip as an acoustic window through which ultrasonic waves can pass, and installs an ultrasonic transducer along the inner wall of the acoustic window. The ultrasonic probe is provided with an acoustic lens formed inside the tip of the probe so as to be able to converge and emit incident ultrasonic waves so as to be rotatable while facing the ultrasonic transducer.

Since the ultrasonic transducer is provided along the inner wall of the acoustic window in this manner, the aperture of the ultrasonic transducer is enlarged to lower impedance, and efficient radiation of ultrasonic waves and improvement in receiving sensitivity can be achieved. Furthermore, since the ultrasonic waves can be converged and emitted, the ultrasonic waves can be narrowed and transmitted to distant locations, improving resolution.

〔Example〕

1 and 2 show a first embodiment of the present invention, and FIG. 1A is a cross-sectional view in a direction perpendicular to the probe axis direction;
B is a longitudinal sectional view including the probe axis. The cylindrical sheath tip 1 itself serves as an acoustic window through which ultrasonic waves can pass. This sheath distal end l is provided with a cylindrical ultrasonic transducer provided along the inner wall. The ultrasonic transducers 2a, 2b, and 2c are continuous in the circumferential direction to form a cylinder, and are made of polymer piezoelectric material, composite piezoelectric material, etc., and are provided so that the ultrasonic radiation surface is on the inside. It is. And an ultrasonic transducer 2a.

2b and 2c each have a signal line and are connected to a circuit described later.

Furthermore, the sheath tip l has an acoustic lens 4 formed of an acoustically transparent material inside thereof rotatably provided via a flexible shaft 5 extending in the probe axis direction. This acoustic lens 4 has four parts 6 for converging the ultrasonic beam on a part of the outer periphery facing the ultrasonic transducer, and a part of the outer periphery adjacent to the recess 6 is made of ultrasonic absorbing material. 7 is provided.

FIG. 2 is a block diagram of an ultrasonic diagnostic apparatus using an ultrasonic probe. The ultrasonic transducers 2a, 2b, 2c are
Switches 8a, 8 via signal lines 3a, 13bs, 3c
b.

8c, and these switches are connected to the transmitter/receiver circuit 9. In addition, the ultrasonic diagnostic apparatus has a rotational position detection circuit lO, which is connected to a motor (not shown).
The rotational positions of the flexible shaft 5 and the acoustic lens 4 are detected.

Further, the received wave output from the transmitter/receiver circuit 9 and the output from the rotational position detection circuit 10 are input to a digital scan converter (DSC) 11, where an ultrasonic tomographic image is generated and displayed on the TV monitor 12. It has become. Note that the transmitting/receiving circuit 9 and the rotational position detecting circuit 10 are connected so as to be controlled by a control circuit 13.

The operation of this embodiment configured in this way will be explained as follows.
First, as shown in FIG. 1A, when the recess 6 of the acoustic lens 4 is in a position facing the ultrasonic transducer 2a, turn off the switch 8a to which the ultrasonic transducer 2a is connected, and turn off the ultrasonic transducer. Switches 8b and 8 to which 2b and 2c are connected
Turn on c to emit an ultrasonic beam. Then, a part of the ultrasound beam is absorbed by the ultrasound absorbing material 7, and the other ultrasound beam enters from the opposite side of the recess 6, is converged into a narrow beam, exits from the recess 6, and is directed toward the subject. irradiated.

In other words, the ultrasonic beams emitted from the ultrasonic transducers 2b and 2c are incident on the spherical surface of the acoustic lens 4 on which the ultrasonic absorbing material 7 is not provided and are converged. They are substantially equivalent, and can be transmitted as a thin ultrasonic beam to a long distance location. Further, since the ultrasonic transducers 2b and 2c are provided along the inner wall of the sheath tip l, a large area can be secured, impedance is reduced, and matching with the signal lines 3b and 3c is facilitated.

In addition, the echo reflected from the object passes through the acoustic lens 4 and is received by the ultrasound transducers 2b and 2c, but in this case as well, the reception sensitivity is improved because it is matched with the signal lines 3b and 3c. do.

After driving the ultrasonic transducers 2b and 2c as described above, the acoustic lens 4 is then rotated and the ultrasonic transducers 2a and 2c are driven.
Radial scanning can be carried out by sequentially performing transmission and reception such as driving the acoustic lens 4 to receive echoes, then rotating the acoustic lens 4 and driving the ultrasonic transducers 2a and 2b to receive the echoes. Needless to say, the switching of the ultrasonic transducer to be driven in this case is done by the switches 8a to 8c and the control circuit I3. In addition, after receiving the echo, T
The explanation of the operation up to displaying the ultrasonic tomographic image on the V monitor 12 is omitted because it is the same as that well known.

FIG. 3 shows a second embodiment of the present invention, in which parts corresponding to those in the first embodiment are given the same reference numerals. In this embodiment, the ultrasonic transducers 2d and 2e provided along the inner wall of the sheath tip l are shifted in the sheath axis direction as shown in Fig. B, and both ultrasonic transducers 2d , 2e
is in the shape of a circular arc with a portion cut away, and is positioned over 360° with an apparent overlapping portion in the circumferential direction. It should be noted that portions 2f and 2g show an apparent overlapping state in the circumferential direction.

Furthermore, in this embodiment, the acoustic lenses 4a and 4b, which are rotatable via the flexible shaft 5, are arranged in parallel in the sheath axis direction via the vibration absorbing material 14, and the acoustic lenses 4a and 4b, which are rotatable via the flexible shaft 5, are arranged side by side in the sheath axial direction. The four parts 6a and 6b are 18
It is arranged so that it is positioned with a 0° shift. The acoustic lenses 4a and 4b each include the ultrasonic transducer 2a,
2b and rotate while facing each other.

The other configurations are almost the same as in the first embodiment.

FIG. 4 is a block diagram of the ultrasonic diagnostic apparatus according to this embodiment. The ultrasonic transducers 2a and 2b are connected to signal lines 3a and 3b.
The transmitter/receiver circuits 9a and 9b are connected to each other via the transmitter/receiver circuits 9a and 9b. The received wave outputs from the transmitting/receiving circuits 9a and 9b and the output from the rotational position detecting circuit 10 are input to the DSC 11, processed, and displayed on the TV monitor 12.

According to this embodiment configured in this way, since the two ultrasonic transducers 2a and 2b transmit and receive ultrasonic waves,
The scan rate can be improved compared to the first embodiment, and it is possible to obtain an appropriate ultrasonic tomographic image. The first advantage is that it can transmit a thin ultrasonic beam to a long distance, it can emit an ultrasonic beam efficiently without increasing the impedance of the ultrasonic transducer, and it improves receiving sensitivity. This is similar to the example.

By the way, in order to perform ultrasonic scanning using the apparatus according to each of the embodiments described above, the acoustic lens 4 is connected to the flexible shaft 5.
(In the case of conventional ultrasound probes, the ultrasound transducer is rotated by a flexible shaft.) In this case, since the flexible shaft 5 tends to cause uneven rotation, it is difficult to scan a good ultrasonic tomographic layer even when ultrasonic scanning is performed. To solve this problem, a power source for rotating the ultrasonic transducer may be provided within the sheath tip.

However, it is extremely difficult to miniaturize a device such as a motor as a power source and provide it at the distal end of the sheath.

Therefore, it has fewer parts than rotating equipment such as motors,
A reciprocating device such as a solenoid, which can be miniaturized and easily manufactured, may be used. For this purpose, a device that converts reciprocating motion into rotational motion as shown below may be used.

FIG. 5 is a perspective view of the gear device, which is the converting device, with a part of the device lifted up. This gear device has a first gear 15 shown in FIG. 6A, a second gear 16 shown in FIG. 6B, and a third gear 17 shown in FIG. 6C. The first gear has the shape of a so-called crank gear, and has a cylindrical space 18 formed in its center. The side surfaces are formed with right triangular serrations to have a ratchet effect. It goes without saying that the shape of the teeth is not limited as long as it has a ratchet effect. The second gear 16 has an outer diameter that can fit into the space 18 of the first gear 15, and has the same tooth profile and number of teeth as the first gear 16. The third gear 17 has the same shape, outer diameter, tooth profile, and number of teeth as the first gear, and is arranged so that it can face the first gear 15 and the second gear 16 and mesh with them simultaneously. be.

FIG. 5 shows the state immediately before the gears are engaged.

Note that the second gear 16 is coaxially fitted into the first gear 15, and the teeth of both gears are arranged in different phases. The third gear 17 is movable in the axial direction and rotatable in the circumferential direction, so that the opposing gear can be suppressed by a spring 19 or the like.

The operation of the gear device configured in this way will be explained with reference to FIG. 7. First, the first gear 15 is moved in the axial direction ( (downward on the drawing).

Then, as shown in FIG. 7A, the third gear 17
9 and meshes only with the second gear 16. In this case, at least one tooth 17a of the third gear 17 meshes with one tooth 16a of the second gear 16. Next, as shown in FIG. B, when the first gear I5 is moved in the axial direction (upward in the drawing), the third gear 17 is pushed up and disengaged from the second gear 16. In this case, the teeth 17a of the third gear 17 slide along the surfaces of the teeth 15a of the first gear 15, rotate in the circumferential direction by a half period of the teeth, engage, and stop. Next, as shown in FIG. gear 1
Contact with 6. However, since the third gear 17 has already rotated by half a tooth period, the tooth 17a is rotated by the tooth 1 of the gear 16.
It abuts the tooth 16b adjacent to the tooth 6a. and the tooth 16b
It slides on top of the teeth, rotates in the circumferential direction for half a tooth period, engages, and stops. The figure shows this state. By repeating this operation, the tooth 16 in A of the same figure is
The tooth 17a that was meshing with the tooth a is replaced with the tooth 16 in the same drawing.
The first gear 15 meshes with the tooth 16b adjacent to the first gear 15a.
The axial movement of the third gear 17 is converted into the rotational movement of the third gear 17.

To actually drive this gear device, a solenoid is used as a power source, for example, as shown in FIG. In other words,
A permanent magnet 2o is fixedly attached to the first gear 15, a coil 21 is disposed at a position facing the permanent magnet 2o, and an alternating current is applied to the coil 21, thereby alternately applying an attractive force and a repulsive force to the permanent magnet 20. This gives the first gear reciprocating motion in the axial direction. Further, as shown in FIG. 9, a piezoelectric element 22 is used as a power source. In this case, since the amplitude of the piezoelectric element 22 is generally small, the first gear 1 is
Connected to 5. If the resonance frequency determined by the spring constant of the spring 23 and the quality I of the first gear 15 is set to be the frequency of the alternating current applied to the piezoelectric element 22, the resonance effect will cause the first gear 15 to It is possible to provide the necessary amplitude for reciprocating motion.

FIG. 10 is a schematic diagram of the tip of an ultrasonic probe using the driving principle shown in FIG. 9. A housing 25 is rotatably provided inside a sheath tip 24 made of an acoustically transparent material such as Teflon via a step 24a. Additionally, a second
A gear 26 is formed.

Furthermore, a piezoelectric element 27 and a spring 28 are provided on the tip side. The first gear 29, which is provided in correspondence with the piezoelectric element 27 via the spring 28, forms a resonance system with the spring 28, magnifies the minute amplitude of the piezoelectric element 27, and causes the first gear 29 to It is designed to give. The third gear 30 presses the first gear 29 and the second gear 26 by a spring 31. Each shaft 30a of the third gear 30 is inserted into the square hole 25a of the housing 25 so as to be able to reciprocate, so the housing 25 rotates as the third gear 30 rotates. Therefore, even if the housing 25 receives fluctuations in the reaction force of the spring 31, it does not move in the axial direction and does not cause any trouble. Note that the rotating vibrator 32
and the signal line 33 are electrically connected via a slip ring 34.

By transmitting and receiving pulses to and from the vibrator 32, mechanical radial scanning using ultrasonic waves can be performed.

According to this embodiment, a gear device for rotating the ultrasonic transducer can be provided at the distal end of the sheath, eliminating the need for a flexible shaft as a rotating means, which has been a cause of image quality deterioration in ultrasonic tomographic images. Tomoyoshi.

〔Effect of the invention〕

As described above, according to the present invention, since the ultrasonic transducer is provided along the inner wall of the sheath, the opening of the ultrasonic transducer can be made thicker and the electrical impedance can be lowered. Efficient radiation and improved reception sensitivity can be achieved.In addition, the incident area of the ultrasonic waves is widened and the ultrasonic waves can be converged and emitted, so the ultrasonic waves can be narrowed and transmitted to distant locations. The resolution of sonic tomographic images can be improved and appropriate ultrasound diagnosis becomes possible.

[Brief explanation of drawings]

1A and 1B are a vertical sectional view and an axial longitudinal sectional view of a first embodiment of the present invention, and FIG. 2 is a block diagram of an ultrasonic diagnostic apparatus using the same embodiment. 3A and 3B are a vertical sectional view and an axial longitudinal sectional view of the second embodiment of the present invention, and FIG. 4 is a block diagram of an ultrasonic diagnostic apparatus using the same embodiment. The figure is a perspective view of the gear device, FIGS. 6A-C are perspective views of the gear alone, FIGS. 7A-D are operation explanatory diagrams of the gear device, and FIGS. 8 and 9.
The figure shows the driving principle of the gear device, and FIG. 10 shows an example of an ultrasonic probe using the gear device. 1... Sheath tip 2a to 2c... Ultrasonic transducer 4... Acoustic lens 7... Ultrasonic absorber Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 6 Fig. 7 Figure 8 Figure 9 Figure 10 Procedural amendment January 10, 1991

Claims (1)

[Claims] 1. The sheath tip is formed as an acoustic window through which ultrasonic waves can pass, and an ultrasonic transducer is provided along the inner wall of the acoustic window, so that the incident ultrasonic waves can be converged and emitted inside the sheath tip. An ultrasonic probe characterized in that an acoustic lens formed in the above-mentioned shape is rotatably provided while facing the ultrasonic transducer.