JP4176881B2 - Endoscope visual field conversion prism holding structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a holding structure for a field conversion prism arranged at the distal end of an endoscope in order to enable observation in a perspective direction.
[0002]
[Prior art]
An endoscope in which a field conversion prism is arranged at the tip to enable observation in a perspective direction is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-87403. The field conversion prism includes a first surface on which light from the observation target side is incident, a second surface that reflects the light beam incident from the first surface toward the first surface so as to satisfy the total reflection condition on the first surface, And a third surface that transmits the light beam totally reflected by the first surface.
[0003]
The field-of-view conversion prism is generally fixed to the endoscope distal end portion via a holding plate bonded to the first surface side. The holding plate is a perforated plate in which a through hole is formed corresponding to an effective incident range that is an effective range of light incident on the first surface of the field conversion prism from the observation target side, and light from the observation target is The light enters the field conversion prism through the through hole.
When the field conversion prism is bonded to the holding plate, it is desirable that the bonding range is wide in order to secure a strong bonding strength, but the range where the reflected light from the second surface is totally reflected on the first surface (total reflection). If the adhesive adheres to (range), the total reflection condition is lost and the reflectivity is partially reduced. Therefore, it is necessary to avoid the adhesive from protruding into the total reflection range.
[0004]
[Problems to be solved by the invention]
However, in the field-of-view conversion prism holding structure using the conventional holding plate described above, the adhesive on the holding plate is divided into the range corresponding to the total reflection range and the adhesive is applied on the same plane. Therefore, as described above, the work of bonding while keeping the bonding strength and avoiding the protrusion to the total reflection range is a difficult work that requires extremely high precision.
[0005]
The present invention has been made in view of the above-described problems of the prior art. When bonding the field conversion prism and the holding plate, the adhesive protrudes into the total reflection range with an easy operation while maintaining the adhesive strength. It is an object to provide an endoscope field conversion prism holding structure that can avoid
(Purpose)
[0006]
[Means for Solving the Problems]
The endoscope field-of-view conversion prism holding structure according to the present invention has a field-of-view conversion prism that enables observation in a perspective direction at the tip of the endoscope, and the field-of-view conversion prism is inserted through the holding plate into the tip of the endoscope. In the structure fixed to the part, the field conversion prism directs the first surface on which light from the observation target side is incident and the light beam incident from the first surface toward the first surface so as to satisfy the total reflection condition on the first surface. The second surface to be reflected and a third surface to transmit the light beam totally reflected by the first surface, and the holding plate has an effective incidence that is an effective range of incident light from the observation target side to the first surface. A non-contact portion that does not contact the first surface during bonding corresponding to the total reflection range in which the through hole is formed corresponding to the range and the reflected light from the second surface is totally reflected on the first surface. However, it should be formed with a step on the adhesive surface And features.
[0007]
According to said structure, the part corresponding to a total reflection range is formed in a level | step difference with respect to the surrounding adhesion surface as a non-contact part. Therefore, the visual field conversion prism and the holding plate are bonded by applying an adhesive only to the bonding surface. Thereby, the protrusion of the adhesive to the total reflection range is avoided.
[0008]
The non-contact portion can be formed as a through hole. Since the effective incident range and the total reflection range usually partially overlap each other, the formed through-hole has an oval shape including regions corresponding to the effective incident range and the total reflection range.
Further, the non-contact portion can be formed not as a through hole but as a counterbore hole having a predetermined thickness cut from the first surface side.
Furthermore, the holding plate includes a lower layer plate in which through holes are formed in a portion corresponding to the effective incident range and a portion corresponding to the total reflection range, and an upper layer plate in which through holes are formed only in the portion corresponding to the effective incident range. Can be formed. In this case, the lower layer plate and the upper layer plate are overlapped and fixed with the lower layer plate as the first surface side.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a field conversion prism holding structure of an endoscope according to the present invention will be described.
1 and 2 show a first embodiment of the present invention. Initially, the whole structure of the endoscope front-end | tip part is demonstrated based on FIG.
The endoscope distal end shown in FIG. 2 is a distal end of a perspective endoscope, and includes a distal end block 10 whose distal end surface 10a is cut obliquely. The distal end block 10 has an outer periphery excluding the distal end surface. Covered by the tip cover 11. The tip block 10 is formed with an observation hole 10b and an air / water supply hole 10c penetrating along the axial direction.
[0010]
An observation optical system 20 is disposed in the observation hole 10b. The observation optical system 20 includes a plano-concave first lens 21 that also serves as an observation window disposed facing the front end surface 10a, a field conversion prism 22, biconvex second and third lenses 23 and 24, and a concave flat. A fourth lens 29 and a CCD 25 are provided. The field-of-view conversion prism 22 has the effect of aligning the optical axis of the first lens 21 directed in the oblique direction with the optical axes of the second, third, and fourth lenses 23, 24, and 29 parallel to the axial direction of the endoscope. have. The field conversion prism 22 is supported by being bonded to a holding plate 26 which is in contact with the first lens 21 and is fixed to the tip block 10. The holding plate 26 is a metal or resin flat plate in which a through hole 26a is formed at the center.
[0011]
The second, third, and fourth lenses 23, 24, and 29 are provided in the observation hole 10b in a state of being integrally supported by the lens barrel 27. The light from the observation target incident from the first lens 21 enters the prism 22 from the first surface R1 of the field conversion prism 22, and is sequentially reflected by the second surface R2 and the first surface R1, and the third surface R3. Ejected from. The light emitted from the field conversion prism 22 forms an image to be observed on the CCD 25 through the cover glass 25a disposed on the front surface through the second, third, and fourth lenses 23, 24, and 29. An image processing circuit 30 for processing an image signal output from the CCD 25 is disposed behind the CCD 25, and the signal processed here is connected to the proximal end side of the endoscope through the transmission cable 31. It is transmitted to a display device, a recording device, etc. not shown.
[0012]
On the other hand, an air / water supply pipe 40 is fitted into the air / water supply hole 10c from the proximal end side, and a nozzle 41 is attached to the distal end side. The air or water sent from the base end side via the air / water supply pipe 40 reaches the nozzle 41 via the air / water supply hole 10c and is injected from the injection port 41a of the nozzle 41 to the first lens 21 side. Is done. Thereby, the surface of the 1st lens 21 to which dirt etc. adhered can be washed and dried.
[0013]
Next, the configuration of the field conversion prism 22 and the holding plate 26 will be described in detail with reference to FIG. FIG. 1A is a plan view of the holding plate 26 viewed from the first lens side, and FIG. 1B is a cross-sectional view taken along the line BB in FIG. However, in FIG. 1B, the field conversion prism 22 is not hatched.
As shown in FIG. 1B, the first surface R1 of the field conversion prism 22 is bonded to the bonding surface 26b of the holding plate 26, thereby fixing both of them. Then, the light incident from the first surface R1 of the field conversion prism 22 is reflected by the second surface R2 to which the reflective coating is applied and travels again toward the first surface R1. The wedge angle formed by the first surface R1 and the second surface R2 is determined so that the light reflected by the second surface R2 and incident on the first surface R1 satisfies the total reflection condition. 5 degrees. The light totally reflected by the first surface R1 is emitted from the third surface R3 to the second lens 23 side.
[0014]
Here, if the effective incident range of light from the observation target with respect to the first surface R1 is L1, and the range in which the light beam reflected by the second surface R2 is totally reflected by the first surface R1 is L2, these ranges are planar. In FIG. 1A, a circular range partially overlapping each other as indicated by a broken line. The holding plate 26 is formed with an oval through hole 26a including a region corresponding to the effective incident range L1 and the total reflection range L2. A range corresponding to the total reflection range L2 of the through hole 26a is a non-contact portion that does not contact the first surface R1 during bonding. In this specification, such a through hole 26a is also included in what has a "step" with respect to the bonding surface 26b.
[0015]
According to the first embodiment, a region (non-contact portion) corresponding to the total reflection range L2 of the first surface R1 on the holding plate 26 is formed as a part of the through hole 26a. Adhesive cannot be applied. Therefore, the adhesive can be applied only to the adhesive surface 26b bonded to the first surface R1 without the need for precise work, thereby preventing the adhesive from protruding into the total reflection range L2 during the bonding. it can. Moreover, since the non-contact part is formed as a simple through hole, it is easy to process.
[0016]
Next, a second embodiment of the present invention will be described with reference to FIGS. The holding plate 28 of the second embodiment is different from that of the first embodiment except for the shape of the non-contact portion. 3A is a plan view of the holding plate 28 viewed from the first lens side, FIG. 3B is a cross-sectional view taken along the line BB of FIG. 4A, and FIG. It is the perspective view seen from 22 side.
In the holding plate 28 of the second embodiment, a circular through hole 28a is formed corresponding to the effective incident range, and the non-contact portion corresponding to the total reflection range is penetrated as in the first embodiment. A counterbore hole 28c is formed by cutting a predetermined thickness from the first surface R1 side instead of the hole. That is, the counterbore hole 28c is formed in a single step from the surrounding adhesive surface 28b, and the region where the counterbore hole 28c is formed is about half as thin as the adhesive surface 28b.
[0017]
According to the second embodiment, a region (non-contact portion) corresponding to only the total reflection range of the first surface R1 on the holding plate 28 is formed as a counterbore hole 28c. 28b can be clearly distinguished, and even if an adhesive is applied to the portion of the counterbore hole 28c, it does not contact the first surface R1 of the field conversion prism 22 if the amount is small. Therefore, it is possible to apply the adhesive only to the adhesive surface 28b to be bonded to the first surface R1 without using a precise work, and to prevent the adhesive from protruding into the total reflection range during bonding. it can.
In the second embodiment, since the total reflection range except for the effective incident range is covered with the counterbore hole 28c, harmful light from the outside can be prevented from entering the portion, and the harmful light interferes with observation. Can be prevented.
[0018]
FIG. 5 shows a third embodiment of the present invention. The holding plate 50 of the third embodiment is configured by stacking two plates, an upper layer plate 51 and a lower layer plate 52. 5A is a plan view of the upper layer plate 51, FIG. 5B is a plan view of the lower layer plate 52, FIG. 5C is a plan view when both plates are overlapped, and FIG. 5D is a DD of FIG. It is sectional drawing which follows a line.
The upper layer plate 51 is a rectangular flat plate shown in FIG. 5A, and a through hole 51a is formed at the center corresponding to the effective incidence range of the field conversion prism. The lower layer plate 52 is also the same rectangular flat plate as the upper layer plate 51, and an oval through hole 52a including a portion corresponding to the effective incidence range and the total reflection range of the field conversion prism is formed at the center. When these upper layer plate 51 and lower layer plate 52 are overlapped and fixed, as shown in FIGS. 5 (C) and 5 (D), the outer holding plate is identical to the holding plate 28 of the second embodiment. 50 can be configured.
[0019]
According to the third embodiment, by combining two plates in which through holes that can be easily formed are combined, the same effect as in the second embodiment can be exhibited, and the burden on the machining process is reduced. can do. That is, when the counterbore hole used in the second embodiment is directly cut, the cutting tool must be accurately controlled three-dimensionally. However, as in the third embodiment, two plates are used. When each through hole is formed, it is only in the two-dimensional direction that accurate control of the cutting tool is required, so that control of the cutting tool is facilitated.
[0020]
【The invention's effect】
As described above, according to the present invention, the non-contact portion is formed on the holding plate so as to correspond to the total reflection range of the field conversion prism as in claim 1, The area corresponding to the total reflection range that should prevent the adhesive from protruding can be clearly distinguished, and the adhesive can be applied to the necessary and sufficient area on the holding plate without the need for precise work. . Therefore, it is possible to prevent the adhesive from protruding into the total reflection range by an easy operation while maintaining the adhesive strength between the field conversion prism and the holding plate.
[0021]
In the case where the non-contact part is a through hole as in the second aspect, since the adhesive cannot be applied to this part, it is very easy to apply the adhesive to the necessary part of the holding plate. Further, the holding plate can be formed by simple processing.
When the non-contact part is a counterbore hole as in claim 3, in addition to the effect of claim 1, the total reflection range excluding the effective incident range is covered with the counterbore hole, thereby causing harmful light from the outside to this part. Can be prevented, and harmful light can be prevented from interfering with observation.
When the holding plate is composed of an upper layer plate and a lower layer plate as in claim 4, the same effect as in claim 3 of preventing incidence of harmful light from the total reflection range is obtained, and each plate is provided with On the other hand, since it is sufficient to form a through hole that is easy to process, the burden on the processing process is small.
[Brief description of the drawings]
1A and 1B show a field conversion prism holding structure according to a first embodiment, in which FIG. 1A is a plan view of a holding plate viewed from the first lens side, and FIG. 1B is taken along line BB in FIG. Sectional view.
FIG. 2 is a cross-sectional view showing a distal end portion of an endoscope to which the holding structure of FIG. 1 is applied.
3A and 3B show a field conversion prism holding structure according to a second embodiment, in which FIG. 3A is a plan view of a holding plate viewed from the first lens side, and FIG. 3B is taken along line BB in FIG. Sectional view.
4 is a perspective view of the holding plate of FIG. 3 as viewed from the visual field conversion prism 22 side.
FIGS. 5A and 5B show a holding plate of a field conversion prism holding structure according to a third embodiment, where FIG. 5A is a plan view of an upper layer plate, FIG. 5B is a plan view of a lower layer plate, and FIG. The top view at the time of match | combining, (D) is sectional drawing which follows the DD line | wire of (C).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Tip block 10a Tip surface 10b Observation hole 10c Air / water supply hole 11 Tip cover 20 Observation optical system 21 First lens 22 Field conversion prism 23 Second lens 24 Third lens 29 Fourth lens 25 CCD
25a Cover glass 26 Holding plate 26a Through hole 26b Adhesion surface 27 Lens barrel 30 Image processing circuit 31 Transmission cable 40 Air / water supply pipe 41 Nozzle 41a Injection port

Claims (4)

An endoscope in which a field conversion prism that enables observation in a perspective direction is arranged at the distal end of the endoscope, and the field conversion prism is bonded and fixed to an adhesive surface of a holding plate fixed to the distal end portion of the endoscope. In the field conversion prism holding structure of
The field-of-view conversion prism reflects a first surface on which light from the observation target side is incident and a light beam incident from the first surface toward the first surface so that the total reflection condition is satisfied on the first surface. Two surfaces, and a third surface that transmits the light beam totally reflected by the first surface,
The holding plate is formed with a through hole corresponding to an effective incident range that is an effective range of incident light from the observation target side to the first surface, and reflection from the second surface on the first surface. A non-contact portion that does not contact the first surface at the time of bonding is formed so as to have a step with respect to the bonding surface, corresponding to a total reflection range in which light is totally reflected. The field-of-view conversion prism holding structure of the endoscope The non-contact part is a through hole, and the holding plate is formed with an oval through hole including a region corresponding to the effective incident range and the total reflection range. The endoscope field-of-view conversion prism holding structure according to claim 1. The endoscope field-of-view conversion prism holding structure according to claim 1, wherein the non-contact portion is formed as a counterbore hole having a predetermined thickness cut from the first surface side. The holding plate has a lower plate in which an oval through hole including a region corresponding to the effective incident range and the total reflection range is formed, and a through hole is formed only in a portion corresponding to the effective incident range. The endoscope field-of-view conversion prism holding according to claim 1, further comprising an upper layer plate, wherein the lower layer plate faces the first surface and the lower layer plate and the upper layer plate are overlapped with each other. Construction.

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