The tip of the endoscope, and the endoscope

Abstract

The endoscope tip 8 is provided with high watertight sealing between the cover glass 20 and the tip member 10, and with high reliability. [Solution] The endoscope tip 8 comprises a cylindrical tip member having a first through hole in which an enlarged diameter region is formed on the first tip surface, a first optical element fitted into the enlarged diameter region and having a circular second tip surface, which is made of single crystal sapphire having a smaller coefficient of thermal expansion than the tip member, and solder sealing the gap between the side surface of the first optical element and the inner surface of the enlarged diameter region of the first through hole, wherein the c-axis direction of the single crystal sapphire is substantially parallel to a first imaginary line connecting the center point of the first tip surface of the tip member, the first proximity point on the outer circumference of the first tip surface that is closest to the first optical element, and the first center point of the first through hole.

Description

Technical Field

[0001] The present invention relates to an endoscope tip portion in which an optical element is watertightly fixed to a tip member, and an endoscope having an endoscope tip portion in which an optical element is watertightly fixed to a tip member.

Background Art

[0002] An endoscope that inserts an elongated insertion portion into the body of a subject that cannot be observed from the outside and observes the inside of the body using a camera unit disposed at the tip portion or performs treatment / procedure using a treatment tool protruding from the tip portion is widely used. After use, the endoscope is disinfected and sterilized to prevent cross-infection between patients.

[0003] As a method for disinfecting and sterilizing an endoscope, the autoclave method (high-temperature and high-pressure steam method) is becoming the mainstream. The autoclave method does not involve complicated operations, can be used immediately after sterilization, and has a low running cost.

[0004] In the autoclave method, since the entire endoscope is exposed to a high-temperature, high-pressure, and high-humidity state, an O-ring or the like that watertightly seals an optical system such as a camera unit disposed in a through-hole of a tip rigid member and a tip member is likely to deteriorate, and there is a risk that water vapor may enter the optical system. When water vapor enters the optical system, the optical elements (cover glass, lens) become cloudy, and thus an appropriate image cannot be obtained.

[0005] Japanese Patent Application Laid-Open No. 2002-253487 discloses an endoscope in which an outermost optical element is fixed to a tip member using solder. The endoscope realizes highly reliable watertight sealing by using solder, which is a metal material, as a joining member.

Summary of the Invention

Problems to be Solved by the Invention

[0006] As will be described later, when an optical element is fixed to a tip member using solder, stress is applied to the optical element due to the difference between the thermal expansion coefficient of the optical element and the thermal expansion coefficient of the tip member.

[0007] Sapphire single crystals, which are preferred as optical elements due to their high hardness and resistance to scratches, have a limited flexural strength in certain plane orientations. Therefore, when sapphire single crystal elements are fixed to tip components using solder, there is a risk of breakage or reduced reliability due to stress caused by the difference in thermal expansion coefficients.

[0008] Embodiments of the present invention aim to provide an endoscope tip having high watertight sealing between an optical element and a tip member, and a highly reliable endoscope tip having high watertight sealing between an optical element and a tip member, and an endoscope having a highly reliable endoscope tip. [Means for solving the problem]

[0009] The endoscope tip of the embodiment comprises a cylindrical tip member having a first through-hole with an enlarged diameter region formed on its first tip surface, a first optical element fitted into the enlarged diameter region and having a circular second tip surface, which is made of single-crystal sapphire having a smaller coefficient of thermal expansion than the tip member, and solder sealing the gap between the side surface of the first optical element and the inner surface of the enlarged diameter region of the first through-hole, wherein the c-axis direction of the single-crystal sapphire is substantially parallel to a first imaginary line connecting the center point of the first tip surface of the tip member, the first proximity point on the outer circumference of the first tip surface closest to the first optical element, and the first center point of the first through-hole.

[0010] The endoscope of the embodiment has an endoscope tip at the tip of the insertion portion, and the endoscope tip comprises a cylindrical tip member having a first through hole in which an enlarged diameter region is formed on the first tip surface, a first optical element fitted into the enlarged diameter region and having a circular second tip surface, which is made of single crystal sapphire having a smaller coefficient of thermal expansion than the tip member, and solder sealing the gap between the side surface of the first optical element and the inner surface of the enlarged diameter region of the first through hole, wherein the c-axis direction of the single crystal sapphire is substantially parallel to a first imaginary line connecting the center point of the first tip surface of the tip member, the first proximity point on the outer circumference of the first tip surface that is closest to the first optical element, and the first center point of the first through hole. [Effects of the Invention]

[0011] According to embodiments of the present invention, it is possible to provide an endoscope tip having high watertight sealing between the optical element and the tip member and high reliability, and an endoscope having an endoscope tip having high watertight sealing between the optical element and the tip member and high reliability. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 shows an endoscopic system including an endoscope according to an embodiment. [Figure 2] Figure 2 is an exploded cross-sectional view of the tip of the endoscope in the first embodiment. [Figure 3] Figure 3 is a cross-sectional view of the endoscope tip of the first embodiment. [Figure 4] Figure 4 is a plan view of the tip surface of the endoscope tip of the first embodiment. [Figure 5] Figure 5 is a plan view of the tip surface of the endoscope tip of Modified Example 1 of the First Embodiment. [Figure 6] Figure 6 is a plan view of the tip surface of the endoscope tip of a modified example 2 of the first embodiment. [Figure 7] Figure 7 is a plan view of the tip surface of the endoscope tip of Modification 3 of the first embodiment. [Figure 8]Figure 8 is a plan view of the tip surface of the endoscope tip of the second embodiment. [Figure 9] Figure 9 is a plan view of the tip surface of the endoscope tip of Modified Example 1 of the second embodiment. [Figure 10] Figure 10 is a plan view of the tip surface of the endoscope tip of the third embodiment. [Figure 11] Figure 11 is an exploded cross-sectional view of the endoscope tip of the fourth embodiment. [Figure 12] Figure 12 is a plan view of the tip surface of the endoscope tip of the fourth embodiment. [Best Mode for Carrying Out the Invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. The drawings based on the embodiments are schematic. The illustration and reference numerals of some components have been omitted.

[0014] <First Embodiment> As shown in Figure 1, the endoscope 9 of this embodiment, together with the processor 2 that processes image signals, the monitor 3, and the input unit 4, constitutes the endoscope system 1.

[0015] The endoscope 9 comprises an elongated insertion section 7 that is inserted into the body, and a universal cord 6 that extends from the insertion section 7 via an operating section (not shown). The endoscope tip 8 of the insertion section 7 comprises a cylindrical tip member 10, a cover glass 20A which is a first optical element, a camera unit 13, and solder 30 that watertightly fixes the cover glass 20A to the tip member 10. The outer surface of the insertion section 7 is covered with a flexible resin 7A.

[0016] The camera unit 13 has an imaging element 13A such as a CCD, and an objective optical system 13B including a plurality of lenses. The universal code 6 has an electronic connector 5 connected to the processor 2 on the base end side. The subject image captured by the camera unit 13 is signal-processed by the processor 2 and displayed on the screen of the monitor 3. The user uses the input unit 4 to set the endoscope 9 and the processor 2. The input unit 4 gives instructions such as brightness, contrast, and color adjustment of the display image on the monitor 3. Further, the input unit 4 enables input of instructions for changing the emission amount and illumination wavelength range of a light source (laser, LED, xenon lamp, etc.), not shown, which is the illumination optical system of the endoscope 9. According to the instruction of the input unit 4, the emitted light from the light source is controlled by the processor 2, enters an optical fiber bundle, not shown, and the illumination light set by the illumination lens system at the distal end of the endoscope is emitted.

[0017] As shown in FIGS. 2 and 3, the distal end member 10 of the distal end of the endoscope 8 has a first through-hole H10A having a circular opening in the first distal end surface 10SA. The camera unit 13 is housed in the first through-hole H10A. The cover glass 20A closes the opening of the first through-hole H10A and is fixed to the distal end member 10 by solder 30. The optical axis O of the camera unit 13 coincides with the central axis of the first through-hole H10A.

[0018] The first through-hole H10A has a diameter-expanded region H10W with a circular opening on the first distal end surface 10SA side. The diameter-expanded region H10W is a surface region of the first through-hole H10A where the inner diameter, which is the cross-sectional area, is larger than that of the deep part, formed by so-called counterboring. When the distal end member 10 is created by injection molding or the like in which resin is poured into a mold, the diameter-expanded region H10W may be considered at the time of mold design.

[0019] The cover glass 20A is fitted into the enlarged diameter region H10W. That is, the diameter R20 of the cover glass 20A is smaller than the inner diameter R10W of the enlarged diameter region H10W, and larger than the inner diameter R10 of the first through hole H10A. The diameter R20 of the cover glass 20A is, for example, 1 μm to 30 μm smaller than the inner diameter R10W of the enlarged diameter region H10W. The outer diameter of the first tip surface 10SA is, for example, 1 mm to 5 mm.

[0020] The solder 30 is ring-shaped and seals the gap between the side surface 20SS of the cover glass 20A and the inner surface H10SS of the enlarged diameter region H10W of the first through hole H10A. The side surface 20SS of the cover glass 20A and the inner surface H10SS of the enlarged diameter region H10W are coated with, for example, a metal film to improve solder jointability. The side surface 20SS of the cover glass 20A may also be coated with a black layer containing carbon to prevent flare and ghosting.

[0021] Furthermore, the solder 30 does not need to completely fill the gap as long as it seals the gap. For example, in Figure 3, it is not necessary for the solder 30 to be placed all the way down to the bottom of the gap.

[0022] The cover glass 20A is a parallel plate single crystal sapphire. The tip member 10 is a hard member made of stainless steel. The solder 30 is a lead-free solder containing at least one of Zn, Sb, Al, and In.

[0023] As already explained, the linear thermal expansion coefficient of single-crystal sapphire (α20 ≈ 7 ppm / °C) is smaller than that of stainless steel (α10 ≈ 17 ppm / °C). Therefore, when the cover glass 20A is heated above the melting temperature of the solder 30 (e.g., 300°C) to fix it to the tip member 10 using solder 30, and then returns to room temperature (e.g., 25°C), stress is applied to the cover glass 20A.

[0024] As shown in Figure 4, stress is applied to the cover glass 20A along a first imaginary line L1 connecting the center point C10 of the first tip surface 10SA of the tip member 10, the first proximity point C10B which is closest to the cover glass 20A on the outer circumference of the first tip surface 10SA, and the center point CH10A of the first through hole H10A (the first center point C20A of the cover glass 20A). The greatest stress is applied to the cover glass 20A in the vicinity of region D1 on the first tip surface 10SA where the thickness of the tip member 10 (the dimension parallel to the first tip surface 10SA) is thinnest.

[0025] As shown in Figure 4, the endoscope tip 8 is positioned so that the c-axis PO of the sapphire is approximately parallel to the first virtual line L1. "Approximately parallel" means, for example, that the c-axis PO with respect to the first virtual line L1 is ±20 degrees or less, and more specifically, ±5 degrees or less.

[0026] Single-crystal sapphire has the greatest flexural strength in the c-axis direction. Since the direction in which strong stress is applied is the direction of greatest flexural strength, there is no risk of the cover glass 20A breaking.

[0027] The endoscope tip 8 has high watertightness because the gap between the cover glass 20A and the tip member 10 is sealed with solder 30. Furthermore, since there is no risk of the cover glass 20A being damaged by stress, the endoscope tip 8 is highly reliable. The endoscope 9 having the endoscope tip 8 has high watertightness and is highly reliable.

[0028] By providing an enlarged diameter region H10W in the tip member 10 in this way, the assembly of the watertight seal by soldering the cover glass 20A becomes easier.

[0029] As shown in Figure 3, the thickness of the cover glass 20A is greater than the depth of the enlarged diameter region H10W (counterboring depth: size in the optical axis O direction). Therefore, the second tip surface 20SA of the cover glass 20A protrudes from the first tip surface 10SA of the tip member 10 by a predetermined protrusion length P.

[0030] The protrusion length P is preferably greater than 0.1 mm and less than 0.3 mm. This is because when the protrusion length P is within the above range, the stress applied to the cover glass 20A is smaller than when the protrusion length P is outside the above range.

[0031] Alternatively, instead of the cover glass 20A as the first optical element, a plano-concave lens may be fitted into the enlarged diameter region H10W and fixed with solder 30. Furthermore, the cover glass 20A may have a chamfered edge where the second front surface 20SA and the side surface 20SS intersect.

[0032] Next, modifications of the embodiment will be described. The endoscope tip portions 8A-8E described below are similar to the endoscope tip portion 8. For this reason, the same reference numerals are used for the same components as the endoscope tip portion 8, and their descriptions are omitted.

[0033] <Modification 1 of the first embodiment> The tip member 10A of the endoscope tip 8A in this modified example shown in Figure 5 has a second through-hole H10B with a second center point CH10B located on the extension of the first imaginary line L1. A cover glass 20B, which is the second optical element of the illumination optical system, is fitted into the enlarged diameter region of the second through-hole H10B. The cover glass 20B is fixed to the tip member 10 by solder 30. The illumination optical system is an optical system for illumination light that illuminates the subject.

[0034] Large stresses are applied to the cover glass 20A in the vicinity of region D1 and region D2 on the first tip surface 10SA, where the thickness of the tip member 10B decreases.

[0035] The second center point CH10B of the second through-hole H10B lies on the extension of the first virtual line L1, and regions D1 and D2 also lie on the extension of the first virtual line L1. Therefore, the direction of stress is parallel to the first virtual line L1. The cover glass 20B is positioned approximately parallel to the c-axis direction PO of the sapphire with respect to the first virtual line L1. Therefore, there is no risk of the cover glass 20B breaking.

[0036] Furthermore, the areas where significant stress is applied to the cover glass 20B are near regions D2 and D3 on the first tip surface 10SA, where the thickness of the tip member 10A decreases. The direction of the stress is parallel to the first imaginary line L1. Therefore, if the cover glass 20B is made of single-crystal sapphire, there is no risk of breakage if the c-axis direction PO of the sapphire is positioned approximately parallel to the first imaginary line L1.

[0037] <Modification 2 of the first embodiment> The tip member 10B of the endoscope tip 8B of this modified example shown in Figure 6 has a third through-hole H10C with a third center point CH10C and a fourth through-hole H10D with a fourth center point CH10D at two symmetrical positions with the extension of the first imaginary line L1 as the center line.

[0038] Illumination optical systems are positioned in the third through-hole H10C and the fourth through-hole H10D, respectively. The third through-hole H10C, like the second through-hole H10B, has an enlarged diameter region, and the third optical element (cover glass 20C) is fixed to the enlarged diameter region using solder 30. The fourth through-hole H10D, like the third through-hole H10C, has an enlarged diameter region, and the fourth optical element (cover glass 20D) is fixed to the enlarged diameter region using solder 30.

[0039] Large stresses are applied to the cover glass 20A in the vicinity of region D1, region D4, and region D5 of the first tip surface 10SA where the thickness of the tip member 10B decreases. The direction of the total stress, which is the sum of the stress applied to region D4 and the stress applied to region D5, is parallel to the first virtual line L1. The endoscope tip 8B is not at risk of breakage because the cover glass 20A is positioned approximately parallel to the first virtual line L1 in the c-axis direction PO of the sapphire.

[0040] The directions of the stresses applied to the cover glasses 20C and 20D are not parallel to the first virtual line L1, but are approximately parallel. If the cover glasses 20C and 20D are sapphire, and the c-axis direction PO of the sapphire is positioned approximately parallel to the first virtual line L1, then the cover glasses 20C and 20D are not likely to break.

[0041] <Modification 3 of the first embodiment> The tip member 10C of the endoscope tip 8C of this modified example shown in Figure 7 has a fifth through-hole H10E with a fifth center point CH10E on the extension of the first imaginary line L1. The fifth through-hole H10E is, for example, a forceps channel. That is, the opening of the through-hole does not need to be covered by an optical element.

[0042] Furthermore, at two symmetrical positions with respect to the extension of the first virtual line L1 as the center line, there is a sixth through-hole H10F with a sixth center point CH10F and a seventh through-hole H10G with a seventh center point CH10G.

[0043] A cover glass 20F, which is the sixth optical element of the illumination optical system, is placed in the sixth through-hole H10F, and a cover glass 20G, which is the seventh optical element of the illumination optical system, is placed in the seventh through-hole H10G.

[0044] The greatest stress is applied to the cover glass 20A in the vicinity of region D1 and region D2, similar to the endoscope tip 8A, and the stress direction is parallel to the first virtual line L1. In the endoscope tip 8C, there is no risk of breakage because the cover glass 20A is positioned approximately parallel to the first virtual line L1 in the c-axis direction PO of the sapphire.

[0045] Furthermore, if the tip member has multiple through holes, it is preferable that the largest of the multiple through holes has its center point on the extension of the first virtual line L1.

[0046] <Second Embodiment> The tip member 10D of the endoscope tip 8D in this embodiment shown in Figure 8 has an eighth through-hole H10H with a substantially rectangular opening in the first tip surface 10SA. The eighth through-hole H10H has an expanded region with a substantially rectangular opening, and a cover glass 20H, which is an eighth optical element with a substantially rectangular shape, is fixed to the expanded region using solder 30.

[0047] The eighth rectangular through-hole H10H is positioned symmetrically with respect to a second imaginary line L2 that passes through the center of the first tip surface 10SA. The second imaginary line L2 is perpendicular to the long axis of the cover glass 20H.

[0048] The eighth through-hole H10H houses, for example, a camera unit for capturing stereoscopic images, in which two camera units are arranged in parallel.

[0049] The cover glass 20H experiences significant stress in the vicinity of region D7 and region D8 on the first tip surface 10SA, where the thickness of the tip member 10D decreases. The direction of the combined stress, resulting from the stress applied to region D7 and region D8, is approximately parallel to the long axis direction of the cover glass 20H. Therefore, by positioning the c-axis direction PO of the sapphire approximately parallel to the long axis direction of the cover glass 20H, there is no risk of breakage.

[0050] <Modified form of the second embodiment> The tip member 10E of the endoscope tip 8E of the modified endoscope shown in Figure 9 has an eighth through hole H10H with a substantially rectangular opening in the first tip surface 10SA, a ninth through hole H10I having a ninth center point CH10I, and a tenth through hole H10J having a tenth center point CH10J.

[0051] The rectangular eighth through-hole H10H is positioned symmetrically with respect to a second imaginary line L2 that passes through the center of the first tip surface 10SA. The eighth optical element, a cover glass 20H, is fitted into the extended region of the eighth through-hole H10H and fixed in place by solder 30. The second imaginary line L2 is perpendicular to the long axis direction of the cover glass 20H.

[0052] The ninth through-hole H10I and the tenth through-hole H10J are positioned at two symmetrical locations with respect to the second virtual line L2 as the center line.

[0053] A cover glass 20I, which is the ninth optical element of the illumination optical system, is placed in the ninth through-hole H10I, and a cover glass 20J, which is the tenth optical element of the illumination optical system, is placed in the tenth through-hole H10J.

[0054] The greatest stress is applied to the cover glass 20H, which is made of single-crystal sapphire, in the vicinity of region D9 and region D10, where the thickness of the tip member 10E (a dimension parallel to the first tip surface 10SA) is thinnest. The direction of the stress is parallel to the second imaginary line L2.

[0055] Since the c-axis direction of the sapphire at the endoscope tip 8E is approximately parallel to the second virtual line L2, there is no risk of the cover glass 20H being damaged.

[0056] <Third Embodiment> The tip member 10F of the endoscope tip 8F of this embodiment shown in Figure 10 comprises a cylindrical tip member 10E having an 11th through hole H10K with an 11th center point CH10K, and an enlarged diameter region formed on the first tip surface 10SA. The center point (11th center point CH10K) of the circular cover glass 20K made of single crystal sapphire, which is the 11th optical element fitted into the enlarged diameter region, is at the same position as the surface center point C10 of the first tip surface 10SA.

[0057] At the endoscope tip 8F, the stress applied to the cover glass 20K is perpendicular to the first tip surface 10SA. Therefore, by positioning the c-axis direction of the sapphire in the cover glass 20K approximately parallel to the optical axis O of the cover glass 20K, there is no risk of breakage.

[0058] <Fourth Embodiment> The endoscope tip 8G of the endoscope 9A in this embodiment, shown in Figures 11 and 12, is similar to the endoscope tip 8 shown in Figures 2 to 5. However, as shown in Figure 11, the first through-hole H10A does not have an extended region on the first tip surface 10SA side.

[0059] The first through-hole H10A of the tip member 10G has an inner diameter R10 that is, for example, 1 μm to 30 μm larger than the diameter R20 of the cover glass 20A. The solder 30 is ring-shaped and seals the gap between the side surface 20SS of the cover glass 20A and the inner surface H10SS of the first through-hole H10A.

[0060] In other words, the tip member 10G comprises a cylindrical tip member 10G, a cover glass 20A which is a first optical element, and solder 30. The tip member 10G has a first through hole H10A in its first tip surface 10SA. The cover glass 20A, which is fitted into the tip side of the first through hole H10A, is made of single crystal sapphire with a smaller coefficient of thermal expansion than the tip member 10G, and has a circular second tip surface 20SA. The solder 30 seals the gap between the side surface of the cover glass 20A and the inner surface on the tip side of the first through hole H10A.

[0061] Figure 12 is a plan view of the first tip surface 10SA of the endoscope tip 8G, which appears to be the same as Figure 4 (endoscope tip 8). As shown in Figure 12, the c-axis direction PO of the single crystal sapphire is approximately parallel to the first imaginary line L1, which connects the center point C10 of the first tip surface 10SA of the tip member 10G (center point CH10A of the first through hole H10A), the first proximity point C10B which is closest to the cover glass 20A on the outer circumference of the first tip surface 10SA, and the first center point C20A of the first through hole H10A.

[0062] Single-crystal sapphire has the greatest flexural strength in the c-axis direction. Since the direction in which strong stress is applied is the direction of greatest flexural strength, there is no risk of the cover glass 20A breaking.

[0063] <Modified form of the fourth embodiment> The endoscope tip portions of the following modified endoscopes 9A are similar to the endoscope tip portions 8A-8F, but none of them, like the tip member 10G, have an enlarged diameter region (expanded region) in the through-hole into which the cover glass is fitted. The plan views of the first tip surface 10SA of each of the endoscope tip portions 8A-8F are visually the same as those in Figures 5-10, and therefore are omitted from the illustration.

[0064] <Modification 1 of the 4th embodiment> The tip member of the endoscope tip in this modified example has a second through-hole with a second center point located on the extension of the first imaginary line, similar to the tip member 10A shown in Figure 5. A second optical element is fitted into the second through-hole and fixed using solder.

[0065] <Modification 2 of the 4th embodiment> The tip member of the endoscope tip in this modified example has, like the tip member 10B shown in Figure 6, a third through-hole with a third center point and a fourth through-hole with a fourth center point at two symmetrical positions with the extension of the first imaginary line as the center line.

[0066] A third optical element is fitted into the third through-hole and secured with solder. A fourth optical element is fitted into the fourth through-hole and secured with solder.

[0067] <Modification 3 of the 4th embodiment> The tip member of the endoscope tip in this modified example has a fifth through-hole with a fifth center point, which is the forceps channel, on the extension of the first imaginary line, similar to the tip member 10C shown in Figure 7. It also has a sixth through-hole with a sixth center point and a seventh through-hole with a seventh center point at two symmetrical positions with the extension of the first imaginary line as the center line. A sixth optical element is fitted into the sixth through-hole and fixed using solder. A seventh optical element is fitted into the seventh through-hole and fixed using solder.

[0068] The tip member has multiple through holes, and of these multiple through holes, the largest is the one whose center point lies on the extension of the first imaginary line.

[0069] <Modification 4 of the fourth embodiment> The tip member of the endoscope tip in this modified example comprises a cylindrical tip member having an eighth through-hole with a substantially rectangular opening on its first tip surface, similar to the tip member 10D shown in Figure 8; an eighth optical element made of single-crystal sapphire with a smaller coefficient of thermal expansion than the tip member and having a substantially rectangular second tip surface, fitted into the tip side of the eighth through-hole; and solder sealing the gap between the side surface of the eighth optical element and the inner surface on the tip side of the eighth through-hole.

[0070] The eighth optical element is arranged symmetrically with respect to a second imaginary line passing through the center of the first tip surface. The c-axis direction of the single crystal sapphire is approximately perpendicular to the second imaginary line.

[0071] <Modification 5 of the 4th embodiment> The tip member of the endoscope tip in this modified example comprises a cylindrical tip member having an eighth through-hole with a substantially rectangular opening on its first tip surface, similar to the tip member 10E shown in Figure 9; an eighth optical element made of single-crystal sapphire with a smaller coefficient of thermal expansion than the tip member fitted into the eighth through-hole, having a substantially rectangular second tip surface; and solder sealing the gap between the side surface of the eighth optical element and the inner surface on the tip side of the eighth through-hole.

[0072] The eighth optical element is arranged symmetrically with respect to a second imaginary line passing through the center of the first tip surface. The tip member has a ninth through-hole with a ninth center point and a tenth through-hole with a tenth center point, located symmetrically with respect to the second imaginary line as the center line. The ninth optical element is fitted into the ninth through-hole and fixed in place using solder. The tenth optical element is fitted into the tenth through-hole and fixed in place using solder. The c-axis direction of the single crystal sapphire is approximately parallel to the second imaginary line.

[0073] <Modification 6 of the fourth embodiment> The tip member of the endoscope tip in this modified example comprises a cylindrical tip member having an eleventh through-hole on its first tip surface, similar to the tip member 10F shown in Figure 10; an eleventh optical element made of single-crystal sapphire having a smaller coefficient of thermal expansion than the tip member, fitted into the tip side of the eleventh through-hole; and solder sealing the gap between the side surface of the eleventh optical element and the inner surface on the tip side of the eleventh through-hole.

[0074] The center point of the first tip surface and the center point of the 11th through hole are in approximately the same position. The c-axis direction of the single crystal sapphire is approximately parallel to the optical axis of the 11th optical element.

[0075] In the modified version of the fourth embodiment, the single-crystal sapphire has the greatest flexural strength in the c-axis direction. Since the direction in which strong stress is applied is the direction in which the flexural strength is greatest, the cover glass is not at risk of breaking.

[0076] The present invention is not limited to the embodiments described above, and various changes, combinations, and modifications can be made without altering the essence of the invention. [Explanation of Symbols]

[0077] 1. Endoscopy System 7. Insertion part 7A...Soft resin 8, 8A-8G... Endoscope tip 9, 9A... Endoscope 10, 10A-10G... Tip component 10SA...First tip surface 13. Camera Unit 13A...Image sensor 13B... Objective optical system 20, 20A-20K... Cover glass 20SA...Second tip surface 20SS...Side 30.. Handa

Claims

1. A cylindrical tip member having a first through hole in which an enlarged diameter region with a larger inner diameter than the deep portion is formed on the first tip surface, A first optical element, fitted into the enlarged diameter region, is made of single-crystal sapphire having a smaller coefficient of thermal expansion than the tip member, and has a circular second tip surface. The device comprises solder sealing the gap between the side surface of the first optical element and the inner surface of the enlarged diameter region of the first through hole, The endoscope tip is characterized in that the c-axis direction of the single crystal sapphire is substantially parallel to a first imaginary line connecting the center point of the first tip surface of the tip member, the first proximity point on the outer circumference of the first tip surface that is closest to the first optical element, and the first center point of the first through hole.

2. The tip member has a second through hole with a second center point located on the extension of the first imaginary line, The endoscope tip according to claim 1, characterized in that a second optical element is fitted into the second through-hole and fixed using solder.

3. The tip member has a third through-hole with a third center point and a fourth through-hole with a fourth center point at two symmetrical positions with the extension of the first imaginary line as the center line, A third optical element is fitted into the third through-hole and fixed in place using solder. The endoscope tip according to claim 1, characterized in that a fourth optical element is fitted into the fourth through-hole and fixed using solder.

4. The tip member has a fifth through-hole with a fifth center point, which is the forceps opening, on the extension of the first imaginary line. The extension of the first imaginary line has two symmetrical positions with respect to the center line, having a sixth through-hole with a sixth center point and a seventh through-hole with a seventh center point. A sixth optical element is fitted into the sixth through-hole and fixed in place using solder. The endoscope tip according to claim 1, characterized in that a seventh optical element is fitted into the seventh through-hole and fixed using solder.

5. The endoscope tip portion according to claim 1, characterized in that the tip member has a plurality of through holes, and among the plurality of through holes, the through hole whose center point is on the extension of the first imaginary line is the largest.

6. A cylindrical tip member having an eighth through-hole on the first tip surface, in which an opening with a cross-sectional area larger than that of the depth portion is formed, forming a substantially rectangular expanded region, An eighth optical element, fitted into the aforementioned expanded region, is made of single-crystal sapphire having a smaller coefficient of thermal expansion than the aforementioned tip member, and has a substantially rectangular second tip surface. The device comprises solder sealing the gap between the side surface of the eighth optical element and the inner surface of the expanded region of the eighth through hole, The eighth optical element is arranged symmetrically with respect to a second imaginary line passing through the center of the first tip surface. The tip of the endoscope is characterized in that the c-axis direction of the single-crystal sapphire is substantially perpendicular to the second imaginary line.

7. A cylindrical tip member having an eighth through-hole on the first tip surface, in which an expanded region with a substantially rectangular opening is formed, and the cross-sectional area is larger than that of the deep portion. An eighth optical element, fitted into the aforementioned expanded region, is made of single-crystal sapphire having a smaller coefficient of thermal expansion than the aforementioned tip member, and has a substantially rectangular second tip surface. The device comprises solder sealing the gap between the side surface of the eighth optical element and the inner surface of the expanded region of the eighth through hole, The eighth optical element is arranged symmetrically with respect to a second imaginary line passing through the center of the first tip surface. The tip member has a ninth through-hole having a ninth center point and a tenth through-hole having a tenth center point, positioned symmetrically with respect to the second imaginary line as the center line. A ninth optical element is fitted into the ninth through-hole and fixed in place using solder. A tenth optical element is fitted into the tenth through-hole and fixed in place using solder. The tip of the endoscope is characterized in that the c-axis direction of the single-crystal sapphire is substantially parallel to the second imaginary line.

8. A cylindrical tip member having a 11th through-hole in which an enlarged diameter region is formed on the first tip surface, where the inner diameter is larger than that of the deep portion, An eleventh optical element, made of single-crystal sapphire having a smaller coefficient of thermal expansion than the tip member, is fitted into the enlarged diameter region, The device comprises solder sealing the gap between the side surface of the 11th optical element and the inner surface of the enlarged diameter region of the 11th through hole, The center point of the first tip surface and the center point of the 11th through hole are located in approximately the same position. The tip of the endoscope is characterized in that the c-axis direction of the single crystal sapphire is substantially parallel to the optical axis of the 11th optical element.

9. The endoscope tip portion according to claim 1, characterized in that the second tip surface of the first optical element protrudes by more than 0.1 mm and less than 0.3 mm relative to the first tip surface of the tip member.

10. The endoscope tip portion according to claim 1, characterized in that the solder completely covers the side surface of the first optical element without any gaps.

11. The endoscope tip according to claim 1, characterized in that the first optical element is a parallel plate cover glass.

12. The endoscope tip portion according to claim 1, characterized in that the tip member is made of stainless steel.

13. The endoscope tip portion according to claim 1, characterized in that the first optical element is located at the tip of the objective optical system.

14. A cylindrical tip member having a first through hole on its first tip surface, A first optical element, which is fitted into the tip side of the first through hole, is made of single-crystal sapphire having a smaller coefficient of thermal expansion than the tip member, and has a circular second tip surface, The device comprises solder sealing the gap between the side surface of the first optical element and the inner surface on the tip side of the first through hole, The endoscope tip is characterized in that the c-axis direction of the single crystal sapphire is substantially parallel to a first imaginary line connecting the center point of the first tip surface of the tip member, the first proximity point on the outer circumference of the first tip surface that is closest to the first optical element, and the first center point of the first through hole.

15. The tip member has a second through hole with a second center point located on the extension of the first imaginary line, The endoscope tip according to claim 14, characterized in that a second optical element is fitted into the second through-hole and fixed using solder.

16. The tip member has a third through-hole with a third center point and a fourth through-hole with a fourth center point at two symmetrical positions with the extension of the first imaginary line as the center line, A third optical element is fitted into the third through-hole and fixed in place using solder. The endoscope tip according to claim 14, characterized in that a fourth optical element is fitted into the fourth through-hole and fixed using solder.

17. The tip member has a fifth through-hole with a fifth center point, which is the forceps opening, on the extension of the first imaginary line. The extension of the first imaginary line has two symmetrical positions with respect to the center line, having a sixth through-hole with a sixth center point and a seventh through-hole with a seventh center point. A sixth optical element is fitted into the sixth through-hole and fixed in place using solder. The endoscope tip according to claim 14, characterized in that a seventh optical element is fitted into the seventh through-hole and fixed using solder.

18. The endoscope tip portion according to claim 14, characterized in that the tip member has a plurality of through holes, and among the plurality of through holes, the through hole whose center point is on the extension of the first imaginary line is the largest.

19. A cylindrical tip member having an eighth through-hole with a substantially rectangular opening on its first tip surface, An eighth optical element, fitted into the tip side of the eighth through hole, is made of single-crystal sapphire having a smaller coefficient of thermal expansion than the tip member, and has a substantially rectangular second tip surface, The device comprises solder sealing the gap between the side surface of the eighth optical element and the inner surface at the tip of the eighth through hole, The eighth optical element is arranged symmetrically with respect to a second imaginary line passing through the center of the first tip surface. The tip of the endoscope is characterized in that the c-axis direction of the single-crystal sapphire is substantially perpendicular to the second imaginary line.

20. A cylindrical tip member having an eighth through-hole with a substantially rectangular opening on its first tip surface, An eighth optical element, fitted into the tip side of the eighth through hole, is made of single-crystal sapphire having a smaller coefficient of thermal expansion than the tip member, and has a substantially rectangular second tip surface, The device comprises solder sealing the gap between the side surface of the eighth optical element and the inner surface at the tip of the eighth through hole, The eighth optical element is arranged symmetrically with respect to a second imaginary line passing through the center of the first tip surface. The tip member has a ninth through-hole having a ninth center point and a tenth through-hole having a tenth center point, positioned symmetrically with respect to the second imaginary line as the center line. A ninth optical element is fitted into the ninth through-hole and fixed in place using solder. A tenth optical element is fitted into the tenth through-hole and fixed in place using solder. The tip of the endoscope is characterized in that the c-axis direction of the single-crystal sapphire is substantially parallel to the second imaginary line.

21. A cylindrical tip member having an eleventh through hole on its first tip surface, An 11th optical element, made of single-crystal sapphire having a smaller coefficient of thermal expansion than the tip member, is fitted into the tip side of the 11th through hole, The device comprises solder sealing the gap between the side surface of the 11th optical element and the inner surface at the tip of the 11th through hole, The center point of the first tip surface and the center point of the 11th through hole are located in approximately the same position. The tip of the endoscope is characterized in that the c-axis direction of the single crystal sapphire is substantially parallel to the optical axis of the 11th optical element.

22. The endoscope tip portion according to claim 14, characterized in that the second tip surface of the first optical element protrudes by more than 0.1 mm and less than 0.3 mm relative to the first tip surface of the tip member.

23. The endoscope tip portion according to claim 14, characterized in that the solder completely covers the side surface of the first optical element without any gaps.

24. The endoscope tip according to claim 14, characterized in that the first optical element is a parallel plate cover glass.

25. The endoscope tip portion according to claim 14, characterized in that the tip member is made of stainless steel.

26. The endoscope tip portion according to claim 14, characterized in that the first optical element is located at the tip of the objective optical system.

27. The insertion section has an endoscope tip at its tip, and the endoscope tip is, A cylindrical tip member having a first through hole in which an enlarged diameter region with a larger inner diameter than the deep portion is formed on the first tip surface, A first optical element, fitted into the enlarged diameter region, is made of single-crystal sapphire having a smaller coefficient of thermal expansion than the tip member, and has a circular second tip surface. The device comprises solder sealing the gap between the side surface of the first optical element and the inner surface of the enlarged diameter region of the first through hole, An endoscope characterized in that the c-axis direction of the single crystal sapphire is substantially parallel to a first imaginary line connecting the center point of the first tip surface of the tip member, the first proximity point on the outer circumference of the first tip surface that is closest to the first optical element, and the first center point of the first through hole.

28. The insertion section has an endoscope tip at its tip, and the endoscope tip is, A cylindrical tip member having a first through hole on its first tip surface, A first optical element, which is fitted into the tip side of the first through hole, is made of single-crystal sapphire having a smaller coefficient of thermal expansion than the tip member, and has a circular second tip surface, The device comprises solder sealing the gap between the side surface of the first optical element and the inner surface on the tip side of the first through hole, An endoscope characterized in that the c-axis direction of the single crystal sapphire is substantially parallel to a first imaginary line connecting the center point of the first tip surface of the tip member, the first proximity point on the outer circumference of the first tip surface that is closest to the first optical element, and the first center point of the first through hole.

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