JPH08280686A - Ultrasonic endoscope - Google Patents

Abstract

PURPOSE: To certainly house an ultrasonic scanning line in an endoscope observing visual field by bending the rotary member connected to the leading end of the rotary shaft passed through the attaching part connected to a main body block so as to extend the same toward the peripheral body part of the attaching part and attaching an ultrasonic transducer to the bent part. CONSTITUTION: The cap 12 surrounding an attaching part 11 is provided to the main body block 10 of a leading end part main body 2C. An ultrasonic observation mechanism performs mechanical radial scanning and an insertion hole 30 is provided so as to pierce the attaching part 11 and a rotary shaft 31 is provided so as to pass through the insertion hole 30 and the base end part of the rotary shaft 31 is connected to a drive shaft through a flexible shaft 33. The rotary bar 37 attached to the other end of the rotary shaft 31 is bent from the state opposed to the leading end surface of the attaching part 11 so as to be opposed to the peripheral body part of the attaching part and the ultrasonic transducer 38 provided to the bent part 37a is positioned in front of an observation window 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic endoscope which is used for medical purposes and which has an endoscope observation mechanism and an ultrasonic observation mechanism provided at the tip of an insertion portion.

[0002]

2. Description of the Related Art An ultrasonic endoscope which is widely used for medical purposes has a main body operation section for an operator to grasp and operate, which is connected to an insertion section into a body cavity or the like. In the case of a light source device, an ultrasonic observation device, an electronic endoscope,
Further, a universal cord that is detachably connected to the video signal processing device or the like is connected. An endoscope observation mechanism for optically observing the insertion part inserted in the body cavity, etc., and an ultrasonic observation mechanism for acquiring information on the internal tissue tomography are respectively provided at the tip of the insertion part. It is provided in.

The endoscope observation mechanism is provided with an illuminating means and an observing means in order to observe in a dark place such as inside a body cavity. The illuminating means is composed of a light guide made of a flexible optical fiber bundle, and an emitting end of the light guide faces an illuminating lens mounted on an illuminating window provided at a tip of the insertion portion. Further, the observation means is provided with an observation window at the tip of the insertion part, and an objective lens is attached to this observation window. In the optical endoscope, the image guide is made to face the image forming position of this objective lens. In the case of an electronic endoscope, a solid-state image sensor is arranged at the image forming position. And
The ultrasonic observation mechanism has an ultrasonic transducer, and this ultrasonic transducer is also attached to the tip of the insertion portion.

Here, as an ultrasonic scanning method in which a so-called B-mode ultrasonic image is acquired by scanning the ultrasonic transducer, a large number of ultrasonic transducers are arranged to form an ultrasonic transducer. There are electronic scanning in which scanning is performed by sequentially operating each ultrasonic transducer, and mechanical scanning in which scanning is performed by transmitting and receiving ultrasonic signals while mechanically moving the ultrasonic transducer itself. As the scanning direction, there are linear scanning for scanning in a linear direction, radial scanning for scanning in a rotating direction, and the like. When ultrasonically inspecting a part where the body cavity tube part or the body cavity wall has a curved surface shape, an ultrasonic tomographic image can be acquired over the entire circumference in the direction orthogonal to this body cavity tube and along the curved surface. It is advantageous in terms.

When performing mechanical radial scanning, the endoscope observation mechanism must be arranged on the proximal end side and the ultrasonic observation mechanism must be arranged on the distal end side at the distal end portion of the insertion section. When the endoscope observation mechanism is located at the tip side, it is necessary to pass a member constituting the endoscope observation mechanism such as a light guide within the scanning range by the ultrasonic transducer,
The ultrasonic observation field is limited accordingly. Therefore, when the endoscope observation mechanism is arranged on the proximal end side of the insertion portion, the endoscope observation field of view normally becomes a side perspective or at most a front perspective.

For example, Japanese Patent Publication No. 6-98133 discloses a structure in which the endoscope observation mechanism is arranged on the distal end side and the ultrasonic observation mechanism is arranged on the proximal end side in the axial direction of the insertion portion. There is. That is, a tip block having a circular cross section is continuously provided to the tip end body of the insertion portion, an endoscope observation mechanism is provided on the tip end surface of the tip block, and a rotary shaft is attached to the tip block. The rotary member is connected to the tip of the rotary member, the rotary member is bent toward the peripheral body portion side of the tip block, and the ultrasonic transducer is attached to the bent portion. With this configuration, when the rotating shaft is driven to rotate, the ultrasonic transducer attached to the rotating member rotates around the axis of the insertion portion, and the ultrasonic observation field of view is 360 °.
Obtainable. Further, since the endoscope observation mechanism is provided on the tip surface of the tip block, the endoscope observation field of view is the front of the insertion portion, that is, the direct-view type. Here, a rotating member is located in front of the endoscope observation field of view, and when performing ultrasonic scanning, this rotating member rotates, so that the endoscope observation field of view is blocked. Therefore, if the rotating member is formed in a plate shape, the width thereof is made as narrow as possible, and the rotating member is rotated at a high speed, it is possible to perform the endoscopic observation while performing the ultrasonic observation.

[0007]

As described above, an ultrasonic endoscope equipped with an ultrasonic observation mechanism of the type that performs mechanical radial scanning has a side-view type as an endoscope observation field of view. Although the direct-view type is known, the ultrasonic observation field of view and the endoscopic observation field of view do not match in any case. In performing an ultrasonic examination, first, the state of the inner wall of the body cavity is inspected by an endoscopic observation mechanism, and as a result, when a lesion site or a suspected site is found, in order to further examine that site, It is common to operate the ultrasonic observation mechanism to obtain information about the tissue slice at the relevant site. Therefore,
In order to obtain an ultrasonic tomographic image at an accurate position, it is preferable to operate the ultrasonic transducer at the position as it is without moving the insertion part as a result of performing endoscopic observation. For this purpose, it is necessary that the positions of the endoscopic observation field of view and the ultrasonic observation field of view are as close as possible, and in particular, the rotation trajectory of the ultrasonic transducer is made to pass almost the center of the endoscopic observation field of view. It is most advantageous to match the endoscopic observation image and the ultrasonic observation image. However, in the conventional technology, the endoscopic observation field of view and the ultrasonic observation field of view do not match, and in particular, when the endoscopic observation field of view is direct or side view, the ultrasonic observation field of view completely overlaps. Even in the front perspective, depending on the direction of the visual field, the ultrasonic scanning line can barely be caught in the endoscopic observation visual field.

The present invention has been made in view of the above points, and it is an object of the present invention to ensure that an ultrasonic scanning line can be contained within an endoscope observation visual field. .

[0009]

In order to achieve the above-mentioned object, according to the present invention, a mounting portion is connected to a body block of a distal end body of an insertion portion in a protruding state, and the mounting portion is rotated by driving means. A rotary shaft to be driven is provided so as to penetrate therethrough, a rotary member is connected to the tip of the rotary shaft, and the rotary member is bent so as to extend toward the peripheral body portion side of the mounting portion, and the bent portion has an ultrasonic transducer. It is characterized in that it is configured so as to follow the rotation axis by being attached, and an observation window of the endoscope observation mechanism is provided in the peripheral body portion of the attachment portion.

[0010]

The tip main body is composed of the main body block and the mounting portion, and the mounting portion projects from the main body block, and the mounting portion has, for example, a substantially cylindrical shape. By providing an observation window on the peripheral body portion of the attachment portion, an endoscope observation visual field in a direction orthogonal to the insertion portion can be obtained. An ultrasonic transducer that performs mechanical radial scanning is provided by connecting a rotary member to the tip of a rotary shaft provided so as to penetrate through the mounting portion, and is mounted on this rotary member. Since it is provided in a bent portion so as to extend to, the ultrasonic transducer rotates around the mounting portion, and the ultrasonic observation field of view also becomes a direction orthogonal to the axis of the insertion portion, and A field of view of 360 ° is obtained.

The arrangement position of the ultrasonic transducer and the mounting position of the observation window are made to coincide with each other as much as possible in the axial direction of the insertion section, and it is preferable that the rotation locus of the ultrasonic transducer is set at the substantially center of the observation field of view of the endoscope. Position it. Then, the ultrasonic transducer blocks the observation field of view of the endoscope located in front of the observation window.However, when the ultrasonic transducer is not operated, it should be placed in a position not covering the observation window. It does not hinder. In order to enable observation by the endoscope observation mechanism even while the ultrasonic transducer is operating, the angle of blocking the observation window is limited by using a small ultrasonic transducer, and It suffices to rotate the rotary member equipped with the transducer at a high speed.

In order to protect the ultrasonic transducer and ensure the safety of the patient, it is general to provide a cap so as to surround the mounting portion. Since the ultrasonic transducer and the observation window are located inside this cap, a cap with excellent acoustic characteristics and being transparent is used. Further, in order to suppress the attenuation of the ultrasonic signal, an ultrasonic transmission medium is enclosed in the cap, and this ultrasonic transmission medium also has excellent transparency. However, even if the ultrasonic transmission medium and the cap are transparent, if the illumination light is irradiated through them, the ultrasonic transmission medium and the cap are greatly attenuated due to reflection at the boundary. To prevent this, place the lighting window outside the cap. However, the illumination light emitted from the illumination window must reach the entire observation field of view through the observation window. Therefore, the illumination window is arranged at a position on the distal end side of the observation window on the diagonal base end side. As a result, it is possible to effectively illuminate the range of the endoscopic observation visual field, and the endoscopic observation can be performed without any trouble.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 shows the overall configuration of an ultrasonic endoscope. In the figure, reference numeral 1 denotes an ultrasonic endoscope, and this ultrasonic endoscope 1 has a main body operating portion 3 connected to a base end portion of an insertion portion 2 which is inserted into a body cavity or the like. The universal cord 4 is connected to the main body operation unit 3. The end portion of the universal cord 4 is divided into three parts, which are a light source device 5, a video signal processing device 6 (the light source device 5 and the video signal processing device 6 are usually provided in the same casing), and an ultrasonic wave. It is detachably connected to the observation device 7. The light source device 5 is equipped with a light source lamp and the like, and the video signal processing device 6 is additionally provided with a monitor 6a for displaying a video image of the inside of the body cavity which has been subjected to signal processing. Also,
The ultrasonic observation device 7 includes a signal processing unit 7a that processes the reflected echo signal that is transmitted / received and received, and a monitor 7b that displays an ultrasonic image based on the signal processed by the signal processing unit 7a. I have it.

Most of the insertion portion 2 is a flexible portion 2a from the connecting side to the main body operating portion 3, the flexible portion 2a is connected to the angle portion 2b, and the angle portion 2b is connected to the tip portion main body 2c. It is set up. As shown in FIGS. 2 and 3, the distal end body 2c is provided with an endoscope observation mechanism and an ultrasonic observation mechanism. Here, the tip end main body 2c is the main body block 10
And a mounting portion 11 having a substantially columnar shape protruding from the tip of the main body block 10, and the main body block 10 is fitted with a cap 12 surrounding the mounting portion 11. Further, a portion of the body block 10 on the base end side of the mounting portion of the cap 12 is an inclined wall 10a directed obliquely forward, and a portion connected to the inclined portion wall 10a is a flat surface portion 10b.
Has become.

The endoscope observation mechanism is composed of illumination means and observation means. The lighting means is the inclined wall 1 of the main body block 10.
0a is provided with an illumination window 20 (which is shown at two locations in the figure, but is not limited to this), and an illumination lens 21 is attached to the illumination window 20 and faces the illumination lens 21. Thus, the emission end face of the light guide 22 faces. Further, the observation means is provided with an observation window 23 on the peripheral body portion of the mounting portion 11, and the imaging optical system 2 is provided in the observation window 23.
4 is provided, and C is provided at the image forming position of the image forming optical system 24.
A solid-state image pickup device 25 such as a CD faces. Here, in the illustrated example, the observation window 23 is provided in the peripheral body portion of the mounting portion 11, but since the solid-state imaging device 25 is oriented in the axial direction of the insertion portion 2, the imaging optical system is formed. As 24,
It is composed of a prism and a lens to bend the optical path by 90 °. However, the optical configuration of the imaging optical system 24 is not limited to this. Although a treatment tool such as forceps is also used, a treatment tool insertion channel 26 for inserting the treatment tool is provided. The observing means may be configured as a so-called optical endoscope using an image guide instead of the solid-state image sensor.

On the other hand, the ultrasonic observation mechanism performs mechanical radial scanning, and for this purpose, an insertion hole 30 is formed so as to penetrate the mounting portion 11, and is rotated so as to penetrate the insertion hole 30. A shaft 31 is provided, and this rotating shaft 3
The bearing 1 is rotatably supported on the mounting portion 11 by a bearing 32. Here, it is preferable that at least the bearing 32 provided on the tip side of the rotating shaft 31 has a sealing function.
The flexible shaft 3 is formed by winding a metal wire rod in the form of a close contact coil on the base end of the rotary shaft 31.
3, the flexible shaft 33 extends from the insertion portion 2 into the main body operation portion 3 and is connected to the drive shaft 34 as shown in FIG. The drive shaft 34 is
It is rotationally driven by a motor 35, and the rotation angle of the drive shaft 34 is detected by an encoder 36.

A rotary bar 37 as a rotary member is attached to the other end of the rotary shaft 31.
Is bent so as to face the peripheral body portion from the state of facing the tip surface of the mounting portion 11, and the ultrasonic transducer 38 is attached to the bent portion 37a. The ultrasonic transducer 38 is located in front of the observation window 23 and has a rotating bar 37.
The ultrasonic transducer 38 is rotated by
In addition, the rotation locus of the ultrasonic transducer 38, that is, the ultrasonic scanning line thereof passes through the center of the endoscopic observation visual field. In order to allow the ultrasonic transducer 38 to rotate smoothly without causing uneven rotation, the ultrasonic transducer 38 is also extended to the side opposite to the bent portion 37a of the rotary bar 37, and like the bent portion 37a, the mounting portion 11 is provided.
A bent portion 37b bent toward the side of the peripheral body is provided, and a counterweight 39 for the ultrasonic transducer 38 is provided in the bent portion 37b. The signal cable to the ultrasonic transducer 38 is the rotary bar 3
It can be guided from the inside of the flexible shaft 33 through the rotary shaft 31 and taken out from the end of the drive shaft 34. Further, an optical sensor 40 is provided at a predetermined position on the tip end surface (or the peripheral body portion) of the mounting portion 11, and the optical sensor 40 can detect the rotational angle position of the ultrasonic transducer.

An ultrasonic transmission medium is enclosed in the cap 12 in order to suppress the attenuation of the ultrasonic transmission / reception signal.
For this purpose, a fluid supply passage 41 is bored in the body block 10, and a fluid supply tube 42 is connected to the fluid supply passage 41. The fluid supply tube 42 is connected from the insertion section 2 to the ultrasonic transmission medium supply section provided outside through the main body operation section 3 and the universal cord, and is supplied into the cap 12. Further, the cap 12 is formed of a member having good acoustic characteristics. Moreover, since the observation window 23 is provided in the cap 12, the cap 12 is formed of a transparent member in order to secure an observation visual field, and the ultrasonic transmission medium enclosed in the cap 12 is also transparent. For example, deaerated water or the like is preferably used. Further, in order to prevent air from intervening between the cap 12 and the inner wall of the body cavity, a balloon 43 made of a transparent flexible bag is provided at a portion from the cap 12 to the main body block 10.
Is installed, and in order to supply an ultrasonic transmission medium into the balloon 43, a fluid supply / drain passage 44 is provided in the main body block 10.
However, the fluid supply / discharge tube 44 also has a fluid supply / discharge tube 45.
, And the fluid supply / discharge tube 45 is connected to the ultrasonic transmission medium supply unit in the same path as the fluid supply tube 42. The sound wave transmission medium can also be discharged.

The present embodiment is configured as described above, and in a state where the inside of the cap 12 is filled with the ultrasonic wave transmission medium, the insertion portion 2 is inserted into the body cavity to perform endoscopic examination and Ultrasonic examination can be performed. For example, when inspecting a part of a body cavity tube such as the esophagus or duodenum, the distal end body 2c of the insertion part 2 is guided to a predetermined observation target part. At this time, the balloon 43 is kept in a state in which the ultrasonic transmission medium is not supplied. Then, under illumination by the illumination window 21, endoscopic observation of the observation target portion is performed through the observation window 23.
Here, the illumination window 21 is not provided inside the cap 12 but is exposed to the outside, and the illumination window 21 is provided on the inclined wall 10a of the main body block 10 and is illuminated obliquely forward. Therefore, the illumination light from the illumination window 21 can be efficiently applied to almost the entire observation visual field. Further, the ultrasonic transmission medium, the cap 12 and the balloon 43 are arranged in front of the observation window 23, but since these are transparent, an endoscope observation visual field can be secured. However, depending on the rotation angle of the rotary bar 37, the ultrasonic transducer 3
The position where the 8 is attached or the counterweight 39 is at the position where the observation window 23 is covered, but when the rotation bar 37 is stopped,
It is necessary that they are located away from the observation window 23.
Further, during observation by the endoscope, by inserting a treatment tool such as forceps into the treatment tool insertion channel 26, it is possible to perform treatments such as cell collection and removal of the affected area.

Now, assume that an abnormal portion such as a partial discoloration of the inner wall of the cavity is found as a result of observation with an endoscope inside the body cavity. Therefore, in order to confirm whether or not this abnormal part is actually a lesion part, it is effective to acquire an ultrasonic tomographic image of the part. Therefore, first, the abnormal portion is arranged at the center position of the observation field of view through the observation window 32. This operation is performed by moving the entire insertion portion 2 or bending the angle portion 2b. Here, in order to surely arrange the abnormal portion in the center of the observation visual field of the endoscope, as shown in FIG. 1, the image P in the body cavity displayed on the monitor 6a attached to the video signal processing device 6 is displayed. It is preferable to display the center line C at the center. Then, the ultrasonic wave transmission medium is supplied from the fluid supply / discharge tube 45 through the fluid supply / discharge path 44 to the balloon 43 to inflate the balloon 43 by a predetermined amount, and as shown in FIG. Four
3 is closely attached to the inner wall of the body cavity.

In this state, when the motor 35 is operated and the drive shaft 34 is rotationally driven, this rotation is transmitted to the rotary shaft 31 via the flexible shaft 33. Rotating shaft 3
Since the rotary bar 37 is connected to the tip of the rotary bar 37, the rotary bar 37 rotates, and the ultrasonic transducer 38 attached to the rotary bar 37 rotates around the mounting portion 11. Here, the ultrasonic transducer 38 performs mechanical radial scanning, but since the rotation locus of this ultrasonic transducer 38, that is, its scanning line, passes through substantially the center of the endoscopic observation visual field. The ultrasonic tomographic image displayed on the monitor 7b of the ultrasonic observation apparatus 7 includes the center of the endoscopic observation visual field. Therefore, the abnormal part discovered by the observation of the endoscope can be reliably captured in the ultrasonic observation visual field. In addition, balloon 4
3 is bulged, the site of the endoscopic observation field of view is the balloon 4
Since the illumination light from the illumination window 20 is reflected by the balloon 43 and the like, the amount of illumination light irradiated to the site of the endoscopic observation visual field is reduced to some extent, and the ultrasonic transducer 38 is covered. Passes through the front of the observation window 23 every one rotation, so that the field of view is interrupted each time and the image quality of the endoscopic image is considerably deteriorated.
Even while performing the ultrasonic examination, the endoscopic observation of the part of the scanning line can be performed. Therefore, in FIG. 5, the ultrasonic scanning line is indicated by UL, the endoscopic observation visual field is indicated by SF, and the illumination range is indicated by LT. As is clear from this figure, the endoscopic observation field of view SF is within the range of the illumination range LT, and the ultrasonic scanning line UL passes through almost the center of the endoscopic observation field of view SF.

At the end of ultrasonic observation, the motor 35 is stopped. At this time, the ultrasonic transducer 38 and the counterweight 39 attached to the rotary bar 37 must be stopped at a position apart from the observation window 23. For this purpose, the optical sensor 4 is attached to the tip surface of the mounting portion 11.
0 is provided, and the stop position of the rotary bar 37 is controlled by the optical sensor 40 to stop at the position where the observation window 23 is not covered. Then, when the rotation bar 37 is stopped and the ultrasonic transmission medium inside the balloon 43 is sucked from the fluid supply / discharge tube 45, the balloon 43
Is returned to the state in which it is in close contact with the cap 12.

Although the illumination window is provided outside the cap in the above-described embodiment, it may be provided at a position side by side with the observation window in the mounting portion. Also, attach the ultrasonic transducer to the rotating bar only on one side,
Although the counterweight is provided on the opposite side, another ultrasonic transducer may be provided on the opposite side, for example, to change the oscillation frequency and focus position of these two ultrasonic transducers. Here, if an ultrasonic transducer that oscillates at high frequency is used, the distance resolution is high, but the ultrasonic wave reaching depth becomes shallow, and if an ultrasonic transducer that emits low frequency is used, the ultrasonic wave reaching depth can be made deep, but the distance resolution is Get lower. The focus position can also be changed depending on the acoustic lens mounted on the ultrasonic transducer. Therefore, for example, as shown in FIG.
To make a cross shape, bend each tip and bend each bent part 5
It is also possible to provide four types of ultrasonic transducers 51 in 0a. Accordingly, if ultrasonic scanning is performed by using an appropriate ultrasonic transducer according to the position of the affected area, an ultrasonic tomographic image from a portion immediately below the mucosa in the body cavity to a deep portion can be acquired. Of course, if a large number of ultrasonic transducers are provided, the frequency with which the observation window is blocked increases, but during ultrasonic scanning, the distal end body of the insertion part should be kept stable. For example, it is not always necessary to obtain an endoscopic image in the body cavity, and therefore, even if the image quality of the obtained endoscopic image is slightly deteriorated, it does not cause any particular problem. Further, the positional relationship between the observation window and the ultrasonic transducer does not necessarily have to overlap each other, and the ultrasonic transducer may be located slightly forward. For example, as in the case of examining the inside of an organ such as the stomach, it is not necessary to provide a special balloon as long as water can be stored in the organ.

[0024]

As described above, according to the present invention, the rotary shaft is provided at the tip of the insertion portion so as to penetrate the mounting portion projecting from the main body block in the tip body, and the rotary member is provided at the tip of the rotary shaft. Are connected to each other, and the rotary member is bent so as to extend toward the peripheral body portion side of the mounting portion, an ultrasonic transducer is attached to the bent portion, and an observation window that constitutes an endoscope observation mechanism is provided on the peripheral body portion of the mounting portion. Since the configuration is adopted, there is an effect that the ultrasonic scanning line can be surely included in the endoscopic observation visual field.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of an ultrasonic endoscope according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of an insertion portion.

FIG. 3 is a sectional view taken along line XX of FIG. 2;

FIG. 4 is a structural explanatory view of a rotation driving unit of the ultrasonic transducer.

FIG. 5 is an explanatory view of the operation of the ultrasonic endoscope.

FIG. 6 is an external view showing another example of a mounting structure for an ultrasonic transducer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic endoscope 2 Insertion part 2c Tip part main body 10 Main body block 11 Mounting part 12 Cap 20 Illumination window 23 Observation window 30 Insertion hole 31 Rotating shaft 33 Flexible shaft 37,50 Rotating bar 37a, 50a Bending portion 38,51 Ultra Sound wave transducer

Claims (4)

[Claims] 1. A mounting block is connected to a body block of a body of a distal end portion of an insertion section so as to project from the mounting block, and a rotary shaft that is driven to rotate by a drive means is provided through the mounting part. A rotary member is connected, the rotary member is bent so as to extend toward the peripheral body portion side of the mounting portion, and an ultrasonic transducer is attached to the bent portion so that the rotary member can be rotated following the rotary shaft. An ultrasonic endoscope having a configuration in which an observation window of an endoscope observation mechanism is provided on a peripheral body portion of the ultrasonic endoscope. 2. The ultrasonic transducer covers a predetermined angle in a peripheral body portion of the mounting portion, and the observation window is arranged at a position where a center of a visual field substantially coincides with a rotation locus of the ultrasonic transducer. The ultrasonic endoscope according to claim 1, wherein: 3. A transparent cap is provided on the tip end body so as to surround the mounting portion, and the ultrasonic transducer and the observation window are arranged in the transparent cap to illuminate the observation target portion. 2. The ultrasonic endoscope according to claim 1, wherein the illumination window for irradiating the light is provided outside the transparent cap at a position on the diagonal base end side of the observation window. 4. The ultrasonic endoscope according to claim 1, wherein a plurality of ultrasonic transducers are attached to the rotating member.