Endoscope lighting system and endoscope equipped with the same

Abstract

Provided are an endoscope lighting system and an endoscope equipped with the endoscope lighting system. Provided is an endoscope lighting system with high lighting efficiency. The endoscope lighting system (1) is an endoscope lighting system arranged at an insertion portion, and comprises: an exit surface (2) for emitting illumination light, an incident side optical surface (3) for incident illumination light, and an exit side optical surface (4) for emitting illumination light. The incident side optical surface (3) comprises an inner light distribution surface (3a) and an outer light distribution surface (3b), and the outer light distribution surface (3b) is located farther from the central axis (5) of the insertion portion than the inner light distribution surface (3a). The inner light distribution surface (3a) comprises a first inner side surface, and the first inner side surface is a curved surface convex toward the exit surface (2). The outer light distribution surface (3b) is a plane or a curved surface concave toward the exit surface (2).

Description

Technical Field

[0001] The present invention relates to an endoscope lighting system and an endoscope equipped with the endoscope lighting system. Background Art

[0002] Patent Document 1 discloses an illumination optical system for an endoscope. The illumination optical system includes a light distribution member and a light guide. The light distribution member includes a convex lens. The convex surface of the convex lens faces the emission surface of the light guide. The illumination optical system is arranged around the observation optical system.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-054369 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] In the illumination optical system disclosed in Patent Document 1, the central axis of the convex lens does not coincide with the central axis of the light guide. The central axis of the convex lens is located between the central axis of the light guide and the optical axis of the observation optical system.

[0008] One of the two ends of the light guide is referred to as a distal end, and the other as a proximal end. The distal end is located farther from the observation optical system than the proximal end.

[0009] The illumination light emitted from the light guide is incident on the convex surface. The central axis of the convex lens is located on the observation optical system side. In this case, the illumination light emitted from the distal end is significantly refracted compared to the illumination light emitted from the proximal end. Therefore, the illumination light emitted from the distal end is irradiated outside the field of view of the observation optical system. As a result, illumination efficiency is reduced.

[0010] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an endoscope lighting system having high lighting efficiency and an endoscope including the endoscope lighting system.

[0011] Solutions for solving problems

[0012] In order to solve the above-mentioned problems and achieve the purpose, at least some embodiments of the present invention relate to an endoscope lighting system that is disposed in an insertion portion and includes:

[0013] an exit surface for emitting illumination light;

[0014] an optical surface on the incident side for incident illumination light; and

[0015] The optical surface on the output side emits the illumination light,

[0016] The incident side optical surface has an inner light distribution surface and an outer light distribution surface.

[0017] The outer light distribution surface is located farther from the central axis of the insertion portion than the inner light distribution surface.

[0018] The inner light distribution surface has a first inner surface.

[0019] The first inner side surface is a curved surface convex toward the exit surface.

[0020] The outer light distribution surface is a flat surface or a curved surface that is concave toward the light exiting surface.

[0021] Furthermore, an endoscope lighting system according to at least some embodiments of the present invention is an endoscope lighting system disposed in an insertion portion and includes:

[0022] an exit surface for emitting illumination light;

[0023] an optical surface on the incident side for incident illumination light; and

[0024] The optical surface on the output side emits the illumination light,

[0025] The incident side optical surface includes a first plane, a first curved surface connected to the first plane, and a second plane connected to the first curved surface, which are sequentially arranged from the side close to the central axis of the insertion portion.

[0026] The light-emitting side optical surface has a third plane and a second curved surface connected to the third plane, which are sequentially arranged from the side close to the central axis of the insertion portion.

[0027] The first curved surface is a surface that is convex toward the exit surface.

[0028] The second curved surface is a surface that is convex outward.

[0029] Furthermore, at least some embodiments of the present invention relate to an endoscope having:

[0030] The endoscope lighting system described above; and

[0031] Objective optical system,

[0032] Among them, the endoscope illumination system is located farther from the central axis than the objective optical system.

[0033] Effects of the Invention

[0034] According to the present invention, it is possible to provide an endoscope lighting system having high lighting efficiency and an endoscope including the endoscope lighting system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0036] Figure 2 1 is a diagram showing an example of an emission surface.

[0037] Figure 3 It is a diagram showing an endoscope lighting system and light distribution.

[0038] Figure 4 It is a diagram showing an endoscope lighting system and light distribution.

[0039] Figure 5 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0040] Figure 6 It is a diagram showing an endoscope lighting system and light distribution.

[0041] Figure 7 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0042] Figure 8 It is a diagram showing an endoscope lighting system and light distribution.

[0043] Figure 9 is a diagram showing parameters.

[0044] Figure 10 It is a diagram showing an endoscope lighting system and light distribution.

[0045] Figure 11 It is a diagram showing an endoscope lighting system and light distribution.

[0046] Figure 12 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0047] Figure 13 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0048] Figure 14 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0049] Figure 15 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0050] Figure 16 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0051] Figure 17 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0052] Figure 18 It is a diagram showing the endoscope lighting system and light distribution according to this embodiment.

[0053] Figure 19It is a diagram showing the endoscope lighting system and light distribution according to this embodiment.

[0054] Figure 20 It is a diagram showing an endoscope system.

[0055] Figure 21 It is a cross-sectional view of the distal end of the insertion portion.

[0056] Figure 22 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0057] Figure 23 1 is a diagram showing an endoscope lighting system according to this embodiment.

[0058] Figure 24 1 is a diagram showing an endoscope lighting system according to this embodiment. DETAILED DESCRIPTION

[0059] Next, the reasons and effects of the endoscope lighting system and the endoscope according to the present embodiment having such a configuration will be described.

[0060] The endoscope illumination system of this embodiment is configured for an insertion portion and includes an exit surface for emitting illumination light, an incident-side optical surface for receiving illumination light, and an exit-side optical surface for emitting illumination light. The incident-side optical surface includes an inner light distribution surface and an outer light distribution surface, with the outer light distribution surface being located farther from the central axis of the insertion portion than the inner light distribution surface. The inner light distribution surface includes a first inner side surface, which is a curved surface convex toward the exit surface. The outer light distribution surface is either a flat surface or a curved surface concave toward the exit surface.

[0061] Figure 1 1 is a diagram showing an endoscope lighting system according to this embodiment. Figure 1 (a) is a diagram showing a first example of the endoscope lighting system according to the present embodiment. Figure 1 (b) is a diagram showing a second example of the endoscope lighting system according to this embodiment.

[0062] The endoscope lighting system of the present embodiment is arranged at the distal end of the insertion portion of the endoscope. Figure 1 (a) and Figure 1 (b) is a cross-sectional view of the front end of the insertion portion. The specific structure of the front end of the insertion portion will be described later.

[0063] The endoscope illumination system 1 is a first example of an endoscope illumination system. The endoscope illumination system 6 is a second example of an endoscope illumination system. The endoscope illumination system 1 and the endoscope illumination system 6 have an emission surface 2. In the endoscope illumination system 1 and the endoscope illumination system 6, illumination light is emitted from the emission surface 2.

[0064] Figure 2 1 is a diagram showing an example of an emission surface. Figure 2 (a) is a diagram showing a first example of the emission surface. Figure 2 (b) is a diagram showing a second example of the exit surface. Figure 2 (c) is a diagram showing a third example of the exit surface.

[0065] The emission surface of the first example is the emission surface of the light emitting element. Figure 2 As shown in FIG. 1 ( a ), the light emitting element 10 includes a light emitting portion 11 and a sealing resin 12 . The light emitting element 10 is, for example, an LED (light emitting diode) or an LD (laser diode). The emission surface 13 is the surface of the sealing resin 12 .

[0066] The light emitted from the light emitting portion 11 travels through the sealing resin 12 and reaches the emission surface 13 . The light reaching the emission surface 13 is emitted from the emission surface 13 .

[0067] The exit surface of the second example is the end surface of the light guide. Figure 2 As shown in FIG. 2( b ), the light guide 20 includes a fiber bundle 21 and a protective tube 22 . The fiber bundle 21 is formed of a plurality of optical fibers. The emission surface 23 is an end surface of the fiber bundle 21 .

[0068] Light emitted from a light source (not shown) travels through the light guide 20 and reaches the emission surface 23 . The light that has reached the emission surface 23 is emitted from the emission surface 23 .

[0069] The exit surface of the third example is the exit surface of the lighting unit. Figure 2 As shown in FIG. 5( c ), the lighting unit 30 includes a fluorescent body 31 and a sealing resin 32 . The emission surface 33 is a surface of the sealing resin 32 .

[0070] An optical fiber 34 is connected to the phosphor 31. Light emitted from a light source (not shown) travels through the optical fiber 34 and reaches the phosphor 31. The phosphor 31 emits the light emitted from the light source and fluorescence. The wavelength of the fluorescence is longer than that of the light emitted from the light source.

[0071] The light emitted from the fluorescent body 31 travels through the sealing resin 32 and reaches the emission surface 33 . The light that has reached the emission surface 33 is emitted from the emission surface 33 .

[0072] Return to Figure 1 (a) and Figure 1 (b) is explained. Figure 1 As shown in FIG. 1 ( a ), the endoscope illumination system 1 further includes an incident optical surface 3 and an exit optical surface 4 . In the endoscope illumination system 1 , the incident optical surface 3 faces the exit surface 2 . Illumination light emitted from the exit surface 2 enters the incident optical surface 3 .

[0073] The incident-side optical surface 3 includes an inner light distribution surface 3a and an outer light distribution surface 3b. The outer light distribution surface 3b is located farther from the central axis 5 than the inner light distribution surface 3a. The central axis 5 is the central axis of the insertion portion.

[0074] The inner light distribution surface 3a has a first inner side surface. The first inner side surface is a curved surface convex toward the light exiting surface 2. Figure 1 In (a), the inner light distribution surface 3a is formed only by a curved surface that is convex toward the light exit surface 2. Therefore, the inner light distribution surface 3a is formed only by the first inner side surface.

[0075] like Figure 1 As shown in FIG. 2 ( b ), the endoscope illumination system 6 further includes an incident optical surface 7 and an exit optical surface 4 . In the endoscope illumination system 6 , the incident optical surface 7 faces the exit surface 2 . The illumination light emitted from the exit surface 2 enters the incident optical surface 7 .

[0076] The incident-side optical surface 7 includes an inner light distribution surface 7a and an outer light distribution surface 7b. The outer light distribution surface 7b is located farther from the central axis 5 than the inner light distribution surface 7a.

[0077] The inner light distribution surface 7a has a first inner side surface. The first inner side surface is a curved surface convex toward the light exiting surface 2. Figure 1 In (b), the inner light distribution surface 7a is formed only by a curved surface that is convex toward the light exit surface 2. Therefore, the inner light distribution surface 7a is formed only by the first inner side surface.

[0078] The first inner side surface is, for example, a surface obtained by cutting away a portion of an annular surface. The annular surface is the surface of a rotating body formed when a circle and a straight line that does not intersect the circle exist on a plane and the circle is rotated about the straight line as an axis.

[0079] In the endoscope illumination system of this embodiment, the outer light distribution surface is a flat surface or a curved surface that is concave toward the exit surface. In the endoscope illumination system 1, the outer light distribution surface 3b is a flat surface. In the endoscope illumination system 6, the outer light distribution surface 7b is a curved surface that is concave toward the exit surface 2.

[0080] Figure 3 It is a diagram showing an endoscope lighting system and light distribution. Figure 3 (a) is a diagram showing an endoscope lighting system of a first example. Figure 3 (b) is a diagram showing a conventional endoscope lighting system. Figure 3 (c) is a graph showing the distribution of illumination light. Figure 1 (a) The same components are denoted by the same reference numerals, and description thereof will be omitted.

[0081] The illumination light is emitted from the exit surface in all directions. Figure 3 (a) and Figure 3 (b) shows only the illumination light emitted parallel to the central axis.

[0082] use Figure 3 (a) The endoscope lighting system 1 will be described. As described above, the endoscope lighting system 1 is a first example of an endoscope lighting system according to the present embodiment.

[0083] Illumination light IL1, illumination light IL2, and illumination light IL3 are emitted from emission surface 2. Illumination light IL1, illumination light IL2, and illumination light IL3 are incident on incident-side optical surface 3. Incident-side optical surface 3 has inner light distribution surface 3a and outer light distribution surface 3b.

[0084] The illumination light IL3 enters the inner light distribution surface 3a. The inner light distribution surface 3a is a curved surface. Therefore, the illumination light IL3 is refracted and converged by the inner light distribution surface 3a.

[0085] The illumination light IL1 and the illumination light IL2 enter the outer light distribution surface 3 b . The outer light distribution surface 3 b is a flat surface. Therefore, the illumination light IL1 and the illumination light IL2 are not refracted by the outer light distribution surface 3 b and travel parallel to the central axis 5 .

[0086] The space between the incident-side optical surface 3 and the emitting-side optical surface 4 is filled with, for example, a transparent medium having a refractive index greater than 1. The illumination lights IL1 , IL2 , and IL3 travel through the transparent medium and reach the emitting-side optical surface 4 .

[0087] Illumination light IL1, illumination light IL2, and illumination light IL3 are incident on the exit-side optical surface 4. Illumination light IL1 and illumination light IL2 are not refracted by the exit-side optical surface 4 and travel parallel to the central axis 5. Illumination light IL3 converges and then diverges.

[0088] use Figure 3 (b) will now describe the endoscope illumination system 40 . The endoscope illumination system 40 is a conventional endoscope illumination system. The endoscope illumination system 40 includes the emission surface 2 , an incident-side optical surface 41 , and an emission-side optical surface 4 .

[0089] The illumination light IL1 , the illumination light IL2 , and the illumination light IL3 are emitted from the emission surface 2 . The incident-side optical surface 41 faces the emission surface 2 . The illumination light IL1 , the illumination light IL2 , and the illumination light IL3 are incident on the incident-side optical surface 41 .

[0090] The incident-side optical surface 41 is formed only of a curved surface convex toward the emission surface 2. Therefore, the illumination light IL1 and the illumination light IL2 are refracted by the curved surface and travel so as to intersect the central axis 5. The illumination light IL3 is refracted by the curved surface and converges.

[0091] Illumination light IL1 and illumination light IL2 are located farther from central axis 5 than illumination light IL3. Therefore, the angles of incidence of illumination light IL1 and illumination light IL2 on incident-side optical surface 41 are greater than the angle of incidence of illumination light IL3 on incident-side optical surface 41. As a result, illumination light IL1 and illumination light IL2 are refracted more significantly than illumination light IL3.

[0092] The space between the incident-side optical surface 41 and the emitting-side optical surface 4 is filled with, for example, a transparent medium having a refractive index greater than 1. The illumination lights IL1 , IL2 , and IL3 travel through the transparent medium and reach the emitting-side optical surface 4 .

[0093] Illumination light IL1, IL2, and IL3 are incident on exit-side optical surface 4. Illumination light IL1 is reflected by total internal reflection on exit-side optical surface 4. Illumination light IL2 is further refracted by exit-side optical surface 4, traveling across central axis 5. Illumination light IL3 converges and then diverges.

[0094] In the endoscope illumination system 40, illumination light IL1 is refracted by the incident-side optical surface 41 and then reflected by the exit-side optical surface 4. Therefore, illumination light IL1 does not exit from the exit-side optical surface 4. Illumination light IL2 is refracted by both the incident-side optical surface 41 and the exit-side optical surface 4, traveling in a manner that intersects the central axis 5. Therefore, illumination light IL2 exits from the exit-side optical surface 4. However, due to the significant refraction at the incident-side optical surface 41, illumination light IL2 is irradiated outside the observation range. This results in reduced illumination efficiency.

[0095] In contrast, in the endoscope illumination system 1, the illumination light IL1 and the illumination light IL2 are not refracted by either the incident-side optical surface 3 or the exit-side optical surface 4, and travel parallel to the central axis 5. Therefore, the illumination light IL1 and the illumination light IL2 are emitted from the exit-side optical surface 4. Furthermore, the illumination light IL1 and the illumination light IL2 are not irradiated outside the observation range. As a result, a decrease in illumination efficiency can be prevented.

[0096] exist Figure 3 In (c) of FIG. 2 , the light distribution of the illumination light in the endoscope illumination system 1 is indicated by a solid line, and the light distribution of the illumination light in the endoscope illumination system 40 is indicated by a dotted line. Figure 3 (c) shows the light distribution when the endoscope illumination system is arranged symmetrically across the central axis 5. The horizontal axis represents angle, and the vertical axis represents intensity.

[0097] In the endoscope lighting system 1, the angle at which the intensity is zero is less than 80°. In contrast, in the endoscope lighting system 40, the angle at which the intensity is zero is greater than 80°. If the size of the angle represents the width of the illumination range, then Figure 3(c) shows a case where the illumination range of the endoscope illumination system 1 is narrower than the illumination range of the endoscope illumination system 40 .

[0098] If the illumination range is narrower than the illumination range, the amount of illumination light irradiated outside the observation range is also small. Therefore, compared with the endoscope illumination system 40, the endoscope illumination system 1 can illuminate the observation range more efficiently.

[0099] As described above, the outer light distribution surface 3b is located farther from the central axis 5 than the inner light distribution surface 3a. When the center of the observation range is located on the central axis 5, the illumination light IL1 and the illumination light IL2 reach the periphery of the observation range (the peripheral area within the observation range). Therefore, the periphery of the observation range can be brightly illuminated.

[0100] Figure 4 It is a diagram showing an endoscope lighting system and light distribution. Figure 4 (a) is a diagram showing an endoscope lighting system of a second example. Figure 4 (b) is a diagram showing a conventional endoscope lighting system. Figure 4 (c) is a graph showing the distribution of illumination light. Figure 1 (b) The same components are denoted by the same reference numerals and their description is omitted. Figure 4 (b) and Figure 3 Same as (b).

[0101] The illuminating light is emitted from the exit surface in all directions, but Figure 4 (a) and Figure 4 (b) shows only the illumination light emitted parallel to the central axis.

[0102] use Figure 4 (a) will describe the endoscope lighting system 6. As described above, the endoscope lighting system 6 is a second example of the endoscope lighting system of this embodiment.

[0103] The illumination light IL1 , the illumination light IL2 , and the illumination light IL3 are emitted from the emission surface 2 , and the illumination light IL1 , the illumination light IL2 , and the illumination light IL3 are incident on the incident-side optical surface 7 .

[0104] The incident-side optical surface 7 includes an inner light distribution surface 7a and an outer light distribution surface 7b. The illumination light IL3 is incident on the inner light distribution surface 7a. The inner light distribution surface 7a is a curved surface. Therefore, the illumination light IL3 is refracted and converged by the inner light distribution surface 7a.

[0105] Illumination light beams IL1 and IL2 are incident on outer light distribution surface 7b. Outer light distribution surface 7b is a curved surface that is concave toward exit surface 2. Therefore, illumination light beams IL1 and IL2 are refracted by outer light distribution surface 7b. Illumination light beam IL1 travels away from central axis 5, while illumination light beam IL2 travels approximately parallel to the central axis.

[0106] The space between the incident-side optical surface 7 and the emitting-side optical surface 4 is filled with, for example, a transparent medium having a refractive index greater than 1. The illumination lights IL1 , IL2 , and IL3 travel through the transparent medium and reach the emitting-side optical surface 4 .

[0107] Illumination light beams IL1, IL2, and IL3 are incident on exit-side optical surface 4. Illumination light beams IL1, IL2, and IL3 are refracted by exit-side optical surface 4. Illumination light beam IL1 travels away from central axis 5. Illumination light beam IL2 travels approximately parallel to the central axis. Illumination light beam IL3 converges and then diverges.

[0108] As described above, in the endoscope illumination system 40, the illumination light IL1 is not emitted from the emission-side optical surface 4. The illumination light IL2 is emitted from the emission-side optical surface 4 but is irradiated outside the observation range. As a result, the illumination efficiency is reduced.

[0109] In contrast, in the endoscope illumination system 6, the illumination light IL1 and the illumination light IL2 are refracted by both the incident-side optical surface 7 and the exit-side optical surface 4. However, the illumination light IL1 is not refracted as significantly as in the endoscope illumination system 40. The illumination light IL2 travels approximately parallel to the central axis 5. Therefore, the illumination light IL1 and the illumination light IL2 are emitted from the exit-side optical surface 4. Furthermore, the illumination light IL1 and the illumination light IL2 are not irradiated outside the observation range. As a result, a decrease in illumination efficiency can be prevented.

[0110] exist Figure 4 In (c) of FIG. 5 , the light distribution of the illumination light in the endoscope illumination system 6 is indicated by a solid line, and the light distribution of the illumination light in the endoscope illumination system 40 is indicated by a dotted line. Figure 4 (c) shows the light distribution when the endoscope illumination system is arranged symmetrically across the central axis 5. The horizontal axis represents angle, and the vertical axis represents intensity.

[0111] In the endoscope illumination system 6 , the angle at which the intensity is zero is less than 80°. In contrast, in the endoscope illumination system 40 , the angle at which the intensity is zero is greater than 80°. Figure 4 (c) shows a case where the illumination range of the endoscope illumination system 6 is narrower than the illumination range of the endoscope illumination system 40 .

[0112] If the illumination range is narrower than the illumination range, the amount of illumination light irradiated outside the observation range is also small. Therefore, compared with the endoscope illumination system 40, the endoscope illumination system 6 can illuminate the observation range more efficiently.

[0113] As described above, the outer light distribution surface 7b is located farther from the central axis 5 than the inner light distribution surface 7a. When the center of the observation range is on the central axis 5, the illumination light IL1 and the illumination light IL2 reach the periphery of the observation range. Therefore, the periphery of the observation range can be brightly illuminated.

[0114] In the endoscope illumination system of this embodiment, preferably, the inner light distribution surface includes a first inner side surface and a second inner side surface, the second inner side surface is a flat surface, and the second inner side surface is located closer to the central axis than the first inner side surface.

[0115] Figure 5 : is a diagram showing an endoscope lighting system according to this embodiment. Figure 5 A third example of the endoscope lighting system of this embodiment is shown in FIG. Figure 1 (a) The same components are denoted by the same reference numerals, and description thereof will be omitted.

[0116] The endoscope illumination system 50 is an endoscope illumination system of the third example. The endoscope illumination system 50 includes an emission surface 2, an incident-side optical surface 51, and an emission-side optical surface 4. In the endoscope illumination system 50, illumination light is emitted from the emission surface 2.

[0117] The illumination light emitted from the emission surface 2 is incident on the incident optical surface 51. The incident optical surface 51 includes an inner light distribution surface 51a and an outer light distribution surface 51b. The outer light distribution surface 51b is located farther from the central axis 5 than the inner light distribution surface 51a.

[0118] The inner light distribution surface 51a includes a first inner side surface 51a1 and a second inner side surface 51a2. The first inner side surface 51a1 is a curved surface convex toward the emission surface 2. The second inner side surface 51a2 is a flat surface located closer to the central axis 5 than the first inner side surface 51a1.

[0119] In the endoscope illumination system of the present embodiment, the outer light distribution surface is a flat surface or a curved surface that is concave toward the emission surface. In the endoscope illumination system 50, the outer light distribution surface 51b is a flat surface.

[0120] Figure 6 It is a diagram showing an endoscope lighting system and light distribution. Figure 6 (a) is a diagram showing an endoscope lighting system according to a third example. Figure 6 (b) is a diagram showing a conventional endoscope lighting system. Figure 6(c) is a graph showing the distribution of illumination light. Figure 5 The same components are denoted by the same reference numerals, and description thereof will be omitted.

[0121] The illuminating light is emitted from the exit surface in all directions, but Figure 6 (a) and Figure 6 (b) shows only the illumination light emitted parallel to the central axis.

[0122] use Figure 6 (a) will now describe the endoscope lighting system 50. As described above, the endoscope lighting system 50 is a third example of the endoscope lighting system of the present embodiment.

[0123] Illumination light IL1, IL2, IL3, and IL4 are emitted from the emission surface 2. Illumination light IL1, IL2, IL3, and IL4 are incident on the incident-side optical surface 51. The incident-side optical surface 51 has an inner light distribution surface 51a and an outer light distribution surface 51b.

[0124] The illumination light IL3 and the illumination light IL4 enter the inner light distribution surface 51a. The inner light distribution surface 51a has a first inner side surface 51a1 and a second inner side surface 51a2.

[0125] The illumination light IL3 is incident on the first inner side surface 51a1. Since the first inner side surface 51a1 is a curved surface, the illumination light IL3 is refracted and converged by the first inner side surface 51a1.

[0126] The illumination light IL4 is incident on the second inner side surface 51a2. Since the second inner side surface 51a2 is a flat surface, the illumination light IL4 is not refracted by the second inner side surface 51a2 and travels parallel to the central axis 5.

[0127] The illumination light IL1 and the illumination light IL2 enter the outer light distribution surface 51 b. The outer light distribution surface 51 b is a flat surface. Therefore, the illumination light IL1 and the illumination light IL2 are not refracted by the outer light distribution surface 51 b and travel parallel to the central axis 5 .

[0128] The space between the incident-side optical surface 51 and the emitting-side optical surface 4 is filled with, for example, a transparent medium having a refractive index greater than 1. The illumination lights IL1 , IL2 , IL3 , and IL4 travel through the transparent medium and reach the emitting-side optical surface 4 .

[0129] Illumination lights IL1, IL2, IL3, and IL4 are incident on the exit-side optical surface 4. Illumination lights IL1, IL2, and IL4 are not refracted by the exit-side optical surface 4 and travel parallel to the central axis 5. Illumination light IL3 converges and then diverges.

[0130] use Figure 6 (b) will now describe the endoscope illumination system 60 . The endoscope illumination system 60 is a conventional endoscope illumination system. The endoscope illumination system 60 includes the emission surface 2 , an incident-side optical surface 61 , and an emission-side optical surface 62 .

[0131] The illumination light IL1 , the illumination light IL2 , and the illumination light IL3 are emitted from the emission surface 2 . The incident-side optical surface 61 faces the emission surface 2 . The illumination light IL1 , the illumination light IL2 , and the illumination light IL3 are incident on the incident-side optical surface 61 .

[0132] The incident-side optical surface 61 is formed only of a curved surface convex toward the emission surface 2. Therefore, the illumination light IL1 and the illumination light IL2 are refracted by the curved surface and travel so as to intersect the central axis 5. The illumination light IL3 is refracted by the curved surface and converges.

[0133] Illumination light IL1 and illumination light IL2 are located farther from central axis 5 than illumination light IL3. Therefore, the angles of incidence of illumination light IL1 and illumination light IL2 on incident-side optical surface 61 are greater than the angle of incidence of illumination light IL3 on incident-side optical surface 61. As a result, illumination light IL1 and illumination light IL2 are refracted more significantly than illumination light IL3.

[0134] The space between the incident-side optical surface 61 and the emitting-side optical surface 62 is filled with, for example, a transparent medium having a refractive index greater than 1. The illumination lights IL1 , IL2 , and IL3 travel through the transparent medium and reach the emitting-side optical surface 62 .

[0135] Illumination light IL1, illumination light IL2, and illumination light IL3 are incident on the exit-side optical surface 62. Illumination light IL1 is reflected by total internal reflection from the exit-side optical surface 62. Illumination light IL2 is further refracted by the exit-side optical surface 62, traveling in a manner intersecting the central axis 5. Illumination light IL3 converges and then diverges.

[0136] In the endoscope illumination system 60, similar to the endoscope illumination system 40, the illumination light IL1 is not emitted from the exit-side optical surface 62. Instead, the illumination light IL2 is emitted from the exit-side optical surface 62. However, due to the large refraction at the incident-side optical surface 61, the illumination light IL2 is irradiated outside the observation range. As a result, the illumination efficiency is reduced.

[0137] In contrast, in the endoscope illumination system 50, the illumination light IL1 and the illumination light IL2 are not refracted by either the incident-side optical surface 51 or the exit-side optical surface 4, and travel parallel to the central axis 5. Therefore, the illumination light IL1 and the illumination light IL2 are emitted from the exit-side optical surface 4. Furthermore, the illumination light IL1 and the illumination light IL2 are not irradiated outside the observation range. As a result, a decrease in illumination efficiency can be prevented.

[0138] exist Figure 6 In (c) of FIG. 5 , the light distribution of the illumination light in the endoscope illumination system 50 is indicated by a solid line, and the light distribution of the illumination light in the endoscope illumination system 60 is indicated by a dotted line. Figure 6 (c) shows the light distribution when the endoscope illumination system is arranged symmetrically across the central axis 5. The horizontal axis represents angle, and the vertical axis represents intensity.

[0139] In the endoscope lighting system 50, the angle at which the intensity is zero is less than 80°. In contrast, in the endoscope lighting system 60, the angle at which the intensity is zero is approximately 80°. If the size of the angle represents the width of the illumination range, then Figure 6 (c) shows a case where the illumination range of the endoscope illumination system 50 is narrower than the illumination range of the endoscope illumination system 60 .

[0140] If the illumination range is narrower than the illumination range, the amount of illumination light irradiated outside the observation range is also small. Therefore, compared with the endoscope illumination system 60, the endoscope illumination system 50 can illuminate the observation range more efficiently.

[0141] As described above, the outer light distribution surface 51b is located farther from the central axis 5 than the inner light distribution surface 51a. When the center of the observation range is on the central axis 5, the illumination light IL1 and the illumination light IL2 reach the periphery of the observation range. Therefore, the periphery of the observation range can be brightly illuminated.

[0142] Furthermore, illumination light IL4 is incident perpendicularly to both the outer light distribution surface 51a2 and the exit-side optical surface 4. In this case, it is not refracted by either of these surfaces and travels parallel to the central axis 5. Illumination light IL4 is located closer to the central axis 5. Therefore, illumination light IL4 is directed toward the center of the observation range. As a result, a decrease in illumination efficiency is prevented, and bright illumination is achieved near the center of the observation range.

[0143] In the endoscope lighting system of this embodiment, preferably, the optical surface on the exit side has a first exit side surface and a second exit side surface, the first exit side surface is a plane, the second exit side surface is a curved surface, the second exit side surface is located farther from the center axis than the first exit side surface, and a straight line parallel to the center axis and passing through the boundary between the first exit side surface and the second exit side surface intersects the exit surface.

[0144] Figure 7 1 is a diagram showing an endoscope lighting system according to this embodiment. Figure 7 (a) is a diagram showing an endoscope lighting system of a first example. Figure 7 (b) is a diagram showing an endoscope lighting system of the fourth example. Figure 1(a) The same components are denoted by the same reference numerals, and description thereof will be omitted.

[0145] exist Figure 7 (a) and Figure 7 In (b), only a portion of the illumination light emitted from the exit surface is shown. In addition, the illumination light is emitted from the exit surface in various directions, but only the illumination light emitted parallel to the central axis is shown.

[0146] use Figure 7 (a) The endoscope lighting system 70 will be described. The endoscope lighting system 70 is a first example of an endoscope lighting system according to the present embodiment.

[0147] The light-emitting optical surface 71 includes a first light-emitting side surface 71 a and a second light-emitting side surface 71 b . The first light-emitting side surface 71 a is a flat surface, and the second light-emitting side surface 71 b is a curved surface.

[0148] The second emission side surface 71b is located farther from the central axis 5 than the first emission side surface 71a. The straight line 72 is parallel to the central axis 5 and passes through the boundary between the first emission side surface 71a and the second emission side surface 71b.

[0149] In the endoscope illumination system 70, the straight line 72 does not intersect the exit surface 2. In this case, the illumination light IL1 and the illumination light IL2 reach the first exit side surface 71a. The first exit side surface 71a is a flat surface. Therefore, the illumination light IL1 and the illumination light IL2 are not refracted by the exit-side optical surface 71 and travel parallel to the central axis 5.

[0150] use Figure 7 (b) will now describe the endoscope lighting system 80. The endoscope lighting system 80 is a fourth example of the endoscope lighting system of the present embodiment.

[0151] The light-emitting optical surface 81 includes a first light-emitting side surface 81 a and a second light-emitting side surface 81 b . The first light-emitting side surface 81 a is a flat surface, and the second light-emitting side surface 81 b is a curved surface.

[0152] The second emission side surface 81b is located farther from the central axis 5 than the first emission side surface 81a. The straight line 82 is parallel to the central axis 5 and passes through the boundary between the first emission side surface 81a and the second emission side surface 81.

[0153] In the endoscope illumination system 80, the straight line 82 intersects the exit surface 2. In this case, the illumination light IL1 and the illumination light IL2 reach the second exit side surface 81b. The second exit side surface 81b is a curved surface. Therefore, the illumination light IL1 and the illumination light IL2 are refracted by the exit-side optical surface 81 and travel in a manner that intersects the central axis 5.

[0154] Refraction of the illumination light IL1 and the illumination light IL2 occurs only at the second exit side surface 81b. In this case, the illumination light IL1 and the illumination light IL2 are not refracted significantly compared to conventional endoscope illumination systems. Therefore, the illumination light IL1 and the illumination light IL2 are not irradiated outside the observation range. As a result, a decrease in illumination efficiency can be prevented.

[0155] As described above, the second emission side surface 81b is located farther from the central axis 5 than the first emission side surface 81a. When the center of the observation range is located on the central axis 5, the illumination light IL1 and the illumination light IL2 reach near the center of the observation range. Therefore, the vicinity of the center of the observation range can be brightly illuminated.

[0156] Figure 8 It is a diagram showing an endoscope lighting system and light distribution. Figure 8 (a) is a diagram showing an endoscope lighting system according to a fifth example. Figure 8 (b) is a diagram showing a conventional endoscope lighting system. Figure 8 (c) is a graph showing the distribution of illumination light. Figure 4 The same components as in (a) and (b) are denoted by the same reference numerals, and description thereof will be omitted.

[0157] The illuminating light is emitted from the exit surface in all directions, but Figure 8 (a) and Figure 8 (b) shows only the illumination light emitted parallel to the central axis.

[0158] use Figure 8 (a) will now describe an endoscope lighting system 90. The endoscope lighting system 90 is a fifth example of the endoscope lighting system of the present embodiment.

[0159] The illumination light IL1 , the illumination light IL2 , and the illumination light IL3 are emitted from the emission surface 2 , and the illumination light IL1 , the illumination light IL2 , and the illumination light IL3 are incident on the incident-side optical surface 7 .

[0160] The incident-side optical surface 7 includes an inner light distribution surface 7a and an outer light distribution surface 7b. The illumination light IL3 is incident on the inner light distribution surface 7a, and the illumination light IL1 and the illumination light IL2 are incident on the outer light distribution surface 7b.

[0161] The illumination light IL3 is refracted and converged by the inner light distribution surface 7a. The illumination light IL1 and the illumination light IL2 are refracted by the outer light distribution surface 7b. The illumination light IL1 travels away from the central axis 5, and the illumination light IL2 travels substantially parallel to the central axis.

[0162] The space between the incident-side optical surface 7 and the emitting-side optical surface 91 is filled with, for example, a transparent medium having a refractive index greater than 1. The illumination lights IL1 , IL2 , and IL3 travel through the transparent medium and reach the emitting-side optical surface 91 .

[0163] The light-emitting optical surface 91 includes a first light-emitting side surface 91a and a second light-emitting side surface 91b. The first light-emitting side surface 91a is a flat surface, and the second light-emitting side surface 91b is a curved surface. The second light-emitting side surface 91b is located farther from the central axis 5 than the first light-emitting side surface 91a.

[0164] In the endoscope illumination system 90, the straight line 92 intersects the exit surface 2. In this case, the second exit side surface 91b is located closer to the central axis 5 than when the straight line 92 does not intersect the exit surface 2. Therefore, the illumination light IL1 and the illumination light IL2 are incident on the second exit side surface 91b, and the illumination light IL3 is incident on the first exit side surface 91a.

[0165] The illumination light IL1 is refracted by the second emission side surface 91b and travels away from the central axis 5. The illumination light IL2 is refracted by the second emission side surface 91b and travels substantially parallel to the central axis. The illumination light IL3 converges and then diverges.

[0166] Furthermore, if the second light exit side surface 91b is spherical, its center of curvature is close to the outer light distribution surface 7b. This close proximity to the outer light distribution surface 7b reduces the angle of incidence of the illumination light IL1 on the second light exit side surface 91b. In this case, the refraction of the illumination light IL1 at the second light exit side surface 91b is reduced, preventing the illumination light IL1 from being irradiated outside the observation range. This prevents a decrease in illumination efficiency.

[0167] use Figure 8 (b) will now describe an endoscope illumination system 100 . The endoscope illumination system 100 is a conventional endoscope illumination system. The endoscope illumination system 100 includes a light-emitting surface 2 , an incident-side optical surface 41 , and a light-emitting-side optical surface 101 .

[0168] The illumination light IL1 , the illumination light IL2 , and the illumination light IL3 are emitted from the emission surface 2 . The incident-side optical surface 41 faces the emission surface 2 . The illumination light IL1 , the illumination light IL2 , and the illumination light IL3 are incident on the incident-side optical surface 41 .

[0169] The space between the incident-side optical surface 41 and the emitting-side optical surface 101 is filled with, for example, a transparent medium having a refractive index greater than 1. The illumination lights IL1 , IL2 , and IL3 travel through the transparent medium and reach the emitting-side optical surface 101 .

[0170] The light-emitting optical surface 101 includes a first light-emitting side surface 101a and a second light-emitting side surface 101b. The first light-emitting side surface 101a is a flat surface, and the second light-emitting side surface 101b is a curved surface. The second light-emitting side surface 101b is located farther from the central axis 5 than the first light-emitting side surface 101a.

[0171] In the endoscope illumination system 100, the straight line 102 intersects the exit surface 2. In this case, the second exit side surface 101b is located closer to the central axis 5 than when the straight line 102 does not intersect the exit surface 2. However, the illumination light IL1, the illumination light IL2, and the illumination light IL3 are not incident on the second exit side surface 101b.

[0172] Illumination light IL1, illumination light IL2, and illumination light IL3 are incident on first emitting side surface 101a. That is, illumination light IL1, illumination light IL2, and illumination light IL3 are incident on a flat surface. Therefore, illumination light IL1 is reflected by first emitting side surface 101a by total internal reflection. Illumination light IL2 is further refracted by first emitting side surface 101a, traveling in a manner intersecting central axis 5. Illumination light IL3 converges and then diverges.

[0173] In the endoscope illumination system 100, illumination light IL1 is refracted by the incident-side optical surface 41 and then reflected by the exit-side optical surface 101. Therefore, illumination light IL1 does not exit from the exit-side optical surface 101. Illumination light IL2 is refracted by both the incident-side optical surface 41 and the exit-side optical surface 101, traveling in a manner that intersects the central axis 5. Therefore, illumination light IL2 exits from the exit-side optical surface 101. However, due to the significant refraction at the incident-side optical surface 41, illumination light IL2 is irradiated outside the observation range. This results in reduced illumination efficiency.

[0174] In contrast, in the endoscope illumination system 90, the illumination light IL1 and the illumination light IL2 are refracted by both the incident-side optical surface 7 and the exit-side optical surface 91. However, the illumination light IL1 is not refracted as significantly as in the endoscope illumination system 100. The illumination light IL2 travels approximately parallel to the central axis 5. Therefore, the illumination light IL1 and the illumination light IL2 are emitted from the exit-side optical surface 91. Furthermore, the illumination light IL1 and the illumination light IL2 are not irradiated outside the observation range. As a result, a decrease in illumination efficiency can be prevented.

[0175] exist Figure 8 In (c) of FIG. 2 , the light distribution of the illumination light in the endoscope illumination system 90 is indicated by a solid line, and the light distribution of the illumination light in the endoscope illumination system 100 is indicated by a dotted line. Figure 8 (c) shows the light distribution when the endoscope illumination system is arranged symmetrically across the central axis 5. The horizontal axis represents angle, and the vertical axis represents intensity.

[0176] The angle at which the intensity becomes zero is approximately 70° in the endoscope illumination system 90. In contrast, the angle at which the intensity becomes zero in the endoscope illumination system 100 is larger than 70°. Figure 8 (c) shows a case where the illumination range of the endoscope illumination system 90 is narrower than the illumination range of the endoscope illumination system 100 .

[0177] If the illumination range is narrower than the illumination range, the amount of illumination light irradiated outside the observation range is also small. Therefore, compared with the endoscope illumination system 100, the endoscope illumination system 90 can illuminate the observation range more efficiently.

[0178] As described above, the outer light distribution surface 7b is located farther from the central axis 5 than the inner light distribution surface 7a. When the center of the observation range is on the central axis 5, the illumination light IL1 and the illumination light IL2 reach the periphery of the observation range. Therefore, the periphery of the observation range can be brightly illuminated.

[0179] The endoscope lighting system of the present embodiment preferably satisfies the following conditional expression (1).

[0180] 8≤d1 / d2≤32 (1)

[0181] Here,

[0182] d1 is the width of the inner light distribution surface,

[0183] d2 is the width of the outer light distribution surface.

[0184] Figure 9 is a diagram showing the parameters. Figure 9 A cross-sectional view including the central axis of the insertion portion is shown in FIG. Figure 9 (a) is a diagram showing the inner light distribution surface of the first example. Figure 9 (b) is a diagram showing the inner light distribution surface of the second example. Figure 9 (c) is a diagram showing the inner light distribution surface of the third example. Figure 1 (a) and Figure 5 The same components are denoted by the same reference numerals, and description thereof will be omitted.

[0185] d1 is the width of the inner light distribution surface. d2 is the width of the outer light distribution surface. d1 and d2 are the widths of the cross section including the central axis of the insertion portion.

[0186] use Figure 9(a) illustrates the inner light distribution surface of the first example. Regarding the inner light distribution surface of the first example, the inner light distribution surface 3a is in contact with the outer light distribution surface 3b and surface S1. The inner light distribution surface 3a is a curved surface. The outer light distribution surface 3b and surface S1 are flat surfaces. In this case, the boundary B1 between the inner light distribution surface 3a and the outer light distribution surface 3b, and the boundary B2 between the inner light distribution surface 3a and plane S1 are clear. Therefore, for the inner light distribution surface of the first example, d1 can be calculated based on boundary B1 and boundary B2.

[0187] use Figure 9 (b) will now describe the inner light distribution surface of the second example. Regarding the inner light distribution surface of the second example, the inner light distribution surface 3a is in contact with the outer light distribution surface 3b and the surface S2.

[0188] The inner light distribution surface 3a is a curved surface. Since the outer light distribution surface 3b is a flat surface, the boundary B1 between the inner light distribution surface 3a and the outer light distribution surface 3b is clear. Since surface S2 is the same curved surface as the inner light distribution surface 3a, the boundary between the inner light distribution surface 3a and the flat surface S2 is unclear. Therefore, for the inner light distribution surface in the second example, d1 cannot be calculated based on the boundary. Therefore, for the inner light distribution surface in the second example, d1 is calculated based on the boundary B1 and position P1, or based on the boundary B1 and position P2.

[0189] When using boundary B1 and position P1, d1 is represented by the distance Δ1 between boundary B1 and position P1. Position P1 is the intersection of inner light distribution surface 3a and straight line SL. Straight line SL is a straight line passing through one end of light exit surface 2 and parallel to the central axis.

[0190] When using boundary B1 and position P2, d1 is represented by the distance Δ2 between boundary B1 and position P2. Position P2 is the intersection of the inner light distribution surface 3a and the predetermined illumination light. The predetermined illumination light is the illumination light that passes through the position farthest from position P1 among the illumination light reaching the observation range.

[0191] use Figure 9 (c) will now describe the inner light distribution surface of the third example. Regarding the inner light distribution surface of the third example, the inner light distribution surface 51a is in contact with the outer light distribution surface 51b and the surface S3.

[0192] The inner light distribution surface 51a includes a first inner side surface 51a1 and a second inner side surface 51a2. The first inner side surface 51a1 is in contact with the outer light distribution surface 51b, and the second inner side surface 51a2 is in contact with the surface S3.

[0193] The first inner side surface 51a1 is a curved surface. Because the outer light distribution surface 3b is a flat surface, the boundary B1 between the first inner side surface 51a1 and the outer light distribution surface 51b is clear. The second inner side surface 51a2 is a flat surface. Because surface S3 is coplanar with the second inner side surface 51a2, the boundary between the second inner side surface 51a2 and plane S3 is unclear. Therefore, for the inner light distribution surface of the third example, d1 cannot be calculated based on the boundary. Therefore, for the inner light distribution surface of the third example, d1 is calculated based on boundary B1 and position P3 or based on boundary B1 and position P4.

[0194] When using boundary B1 and position P3, d1 is represented by the distance Δ3 between boundary B1 and position P3. When using boundary B1 and position P4, d1 is represented by the distance Δ4 between boundary B1 and position P4. Position P3 is the intersection of inner light distribution surface 51a and straight line SL. Position P4 is the intersection of inner light distribution surface 51a and the specified illumination light.

[0195] In the first example, the boundary B2 can be regarded as the intersection of the inner light distribution surface 3a and the predetermined illumination light. Alternatively, the boundary B2 may be located closer to the central axis than the intersection of the inner light distribution surface 3a and the predetermined illumination light.

[0196] By satisfying the conditional expression (1), it is possible to prevent a decrease in illumination efficiency while ensuring a wide light distribution.

[0197] If the value falls below the lower limit of conditional expression (1), the outer light distribution surface becomes too large. In this case, the inner light distribution surface becomes relatively narrow. At the inner light distribution surface, the illumination light converges and then diverges. If the inner light distribution surface becomes narrower, the divergence of the illumination light becomes smaller. As a result, the light distribution becomes narrower.

[0198] If the upper limit of conditional expression (1) is exceeded, the outer light distribution surface becomes too narrow. Therefore, more illumination light is irradiated outside the observation range, resulting in a decrease in illumination efficiency.

[0199] Figure 10 It is a diagram showing an endoscope lighting system and light distribution. Figure 10 (a) is a diagram showing an endoscope lighting system according to a sixth example. Figure 10 (b) is a diagram showing a conventional endoscope lighting system. Figure 10 (c) is a graph showing the light distribution of the illumination light.

[0200] The illuminating light is emitted from the exit surface in all directions, but Figure 10 (a) and Figure 10 (b) shows only the illumination light emitted parallel to the central axis.

[0201] use Figure 10(a) The endoscope lighting system 110 will be described. The endoscope lighting system 110 is a sixth example of the endoscope lighting system of the present embodiment.

[0202] The endoscope illumination system 110 includes an emission surface 2 , an incident-side optical surface 111 , and an emission-side optical surface 112 . In the endoscope illumination system 110 , illumination light is emitted from the emission surface 2 .

[0203] The illumination light is incident on the incident-side optical surface 111. The incident-side optical surface 111 includes an inner light distribution surface 111a and an outer light distribution surface 111b. The outer light distribution surface 111b is located farther from the central axis 5 than the inner light distribution surface 111a.

[0204] The inner light distribution surface 111a has a first inner side surface. The first inner side surface is a curved surface convex toward the light exiting surface 2. Figure 10 In (a), the inner light distribution surface 111a is formed only by a curved surface that is convex toward the light exit surface 2. Therefore, the inner light distribution surface 111a is formed only by the first inner side surface.

[0205] In the endoscope illumination system of this embodiment, the outer light distribution surface is a flat surface or a curved surface that is concave toward the emission surface. In the endoscope illumination system 110 , the outer light distribution surface 111 b is a flat surface.

[0206] The illumination light IL1 passes through the outer light distribution surface 111b and the emission-side optical surface 112. The illumination light IL1 is incident on the outer light distribution surface 111b and the emission-side optical surface 112. Therefore, the illumination light IL1 travels parallel to the central axis 5.

[0207] In the endoscope illumination system 110, the value of d1 / d2 is 20.4. Therefore, the endoscope illumination system of the sixth example satisfies the conditional expression (1).

[0208] use Figure 10 (b) The endoscope illumination system 120 is described. The endoscope illumination system 120 is a conventional endoscope illumination system. The endoscope illumination system 120 includes the exit surface 2, an incident side optical surface 121, and an exit side optical surface 122. The incident side optical surface 121 is formed solely of a curved surface that is convex toward the exit surface 2.

[0209] In the endoscope illumination system 120, the illumination light IL1 is emitted from the emission-side optical surface 122. However, due to the large refraction at the incident-side optical surface 121, the illumination light IL1 is irradiated outside the observation range, resulting in a decrease in illumination efficiency.

[0210] In contrast, in the endoscope illumination system 110, the illumination light IL1 is not refracted by either the incident-side optical surface 111 or the exit-side optical surface 112, but travels parallel to the central axis 5. Therefore, the illumination light IL1 is not irradiated outside the observation range, thereby preventing a decrease in illumination efficiency.

[0211] exist Figure 10 In (c) of FIG. 2 , the light distribution of the illumination light in the endoscope illumination system 110 is indicated by a solid line, and the light distribution of the illumination light in the endoscope illumination system 120 is indicated by a dotted line. Figure 10 (c) shows the light distribution when the endoscope illumination system is arranged symmetrically across the central axis 5. The horizontal axis represents angle, and the vertical axis represents intensity.

[0212] In the endoscope lighting system 110, the angle at which the intensity is zero is less than 80°. In contrast, in the endoscope lighting system 120, the angle at which the intensity is zero is approximately 80°. If the size of the angle represents the width of the illumination range, then Figure 10 (c) shows a case where the illumination range of the endoscope illumination system 110 is narrower than the illumination range of the endoscope illumination system 120 .

[0213] If the illumination range is narrower than the illumination range, the amount of illumination light irradiated outside the observation range is also small. Therefore, the endoscope illumination system 110 can illuminate the observation range more efficiently than the endoscope illumination system 120.

[0214] As described above, the outer light distribution surface 111b is located farther from the central axis 5 than the inner light distribution surface 111a. When the center of the observation range is on the central axis 5, the illumination light IL1 reaches the periphery of the observation range. Therefore, the periphery of the observation range can be brightly illuminated.

[0215] Figure 11 It is a diagram showing an endoscope lighting system and light distribution. Figure 11 (a) is a diagram showing an endoscope lighting system of a seventh example. Figure 11 (b) is a diagram showing a conventional endoscope lighting system. Figure 11 (c) is a graph showing the light distribution of the illumination light.

[0216] The illuminating light is emitted from the exit surface in all directions, but Figure 11 (a) and Figure 11 (b) shows only the illumination light emitted parallel to the central axis.

[0217] use Figure 11 (a) will describe the endoscope lighting system 130. The endoscope lighting system 130 is a seventh example of the endoscope lighting system of the present embodiment.

[0218] The endoscope illumination system 130 includes an emission surface 2 , an incident-side optical surface 131 , and an emission-side optical surface 132 . In the endoscope illumination system 130 , illumination light is emitted from the emission surface 2 .

[0219] The illumination light enters the incident-side optical surface 131. The incident-side optical surface 131 includes an inner light distribution surface 131a and an outer light distribution surface 131b. The outer light distribution surface 131b is located farther from the central axis 5 than the inner light distribution surface 131a.

[0220] The inner light distribution surface 131a has a first inner side surface. The first inner side surface is a curved surface convex toward the light exiting surface 2. Figure 11 In (a), the inner light distribution surface 131a is formed only by a curved surface that is convex toward the light exit surface 2. Therefore, the inner light distribution surface 131a is formed only by the first inner side surface.

[0221] In the endoscope illumination system of this embodiment, the outer light distribution surface is a flat surface or a curved surface that is concave toward the emission surface. In the endoscope illumination system 130, the outer light distribution surface 131b is a flat surface.

[0222] The illumination light IL1 and the illumination light IL2 pass through the outer light distribution surface 131b and the exit-side optical surface 132. The illumination light IL1 and the illumination light IL2 are incident on the outer light distribution surface 131b and the exit-side optical surface 132. Therefore, the illumination light IL1 and the illumination light IL2 travel parallel to the central axis 5.

[0223] In the endoscope illumination system 130, the value of d1 / d2 is 16.9. Therefore, the endoscope illumination system of the seventh example satisfies the conditional expression (1).

[0224] use Figure 11 (b) describes the endoscope illumination system 140. The endoscope illumination system 140 is a conventional endoscope illumination system. The endoscope illumination system 140 includes the exit surface 2, an incident side optical surface 141, and an exit side optical surface 142. The incident side optical surface 141 is formed solely of a curved surface that is convex toward the exit surface 2.

[0225] In the endoscope illumination system 140, illumination light IL1 is not emitted from the exit-side optical surface 142. Illumination light IL2 is emitted from the exit-side optical surface 142. However, due to the large refraction at the incident-side optical surface 141, illumination light IL2 is irradiated outside the observation range. As a result, illumination efficiency is reduced.

[0226] In contrast, in the endoscope illumination system 130, the illumination light IL1 and the illumination light IL2 are not refracted by either the incident-side optical surface 131 or the exit-side optical surface 132, and travel parallel to the central axis 5. Therefore, the illumination light IL1 and the illumination light IL2 are not irradiated outside the observation range. As a result, a decrease in illumination efficiency can be prevented.

[0227] exist Figure 11 In (c) of FIG. 5 , the light distribution of the illumination light in the endoscope illumination system 130 is indicated by a solid line, and the light distribution of the illumination light in the endoscope illumination system 140 is indicated by a dotted line. Figure 11 (c) shows the light distribution when the endoscope illumination system is arranged symmetrically across the central axis 5. The horizontal axis represents angle, and the vertical axis represents intensity.

[0228] In the endoscope lighting system 130, the angle at which the intensity is zero is less than 80°. In contrast, in the endoscope lighting system 140, the angle at which the intensity is zero is approximately 80°. If the size of the angle represents the width of the illumination range, then Figure 11 (c) shows a case where the illumination range of the endoscope illumination system 130 is narrower than the illumination range of the endoscope illumination system 140 .

[0229] If the illumination range is narrower than the illumination range, the amount of illumination light irradiated outside the observation range is also small. Therefore, the endoscope illumination system 130 can illuminate the observation range more efficiently than the endoscope illumination system 140.

[0230] As described above, the outer light distribution surface 131b is located farther from the central axis 5 than the inner light distribution surface 131a. When the center of the observation range is on the central axis 5, the illumination light IL1 and the illumination light IL2 reach the periphery of the observation range. Therefore, the periphery of the observation range can be brightly illuminated.

[0231] The corresponding values of the conditional expression (1) are shown below for the endoscope lighting system of each example. The endoscope lighting system of each example satisfies the conditional expression (1).

[0232]

[0233] Preferably, the endoscope illumination system of the present embodiment includes a light-transmitting member, an inner surface of the light-transmitting member includes an incident-side optical surface, and an outer surface of the light-transmitting member includes an emitting-side optical surface.

[0234] Figure 12 : is a diagram showing an endoscope lighting system according to this embodiment. Figure 12 FIG. 8 shows an eighth example of the endoscope lighting system of this embodiment. Figure 1 (a) The same components are denoted by the same reference numerals, and description thereof will be omitted.

[0235] The endoscope illumination system of the eighth example uses one light-transmitting member. The endoscope illumination system 150 includes a light-transmitting member 151. The light-transmitting member 151 includes an inner surface 152 and an outer surface 153.

[0236] The inner surface 152 includes the incident-side optical surface 3 and an inner peripheral surface 154 . The outer surface 153 includes the exit-side optical surface 4 and an outer peripheral surface 155 .

[0237] The light-transmitting member 151 can function as a front end cover. The light-transmitting member 151 can be manufactured by molding. In the absence of the outer light distribution surface 3b, the inner light distribution surface 3a is directly connected to the inner peripheral surface 154. In this case, during molding, the connection between the inner peripheral surface 154 and the inner light distribution surface 3a may form a flat surface.

[0238] In the light-transmitting member 151, the outer light distribution surface 3b is located between the inner light distribution surface 3a and the inner peripheral surface 154. The outer light distribution surface 3b is an intentionally formed surface and is not a surface formed as a result.

[0239] Preferably, the endoscope lighting system of this embodiment has a first light-transmitting component and a second light-transmitting component, the first light-transmitting component is located between the exit surface and the second light-transmitting component, the inner surface of the first light-transmitting component has an incident side optical surface, and the outer surface of the second light-transmitting component has an exit side optical surface.

[0240] Figure 13 : is a diagram showing an endoscope lighting system according to this embodiment. Figure 13 The ninth example of the endoscope lighting system of this embodiment is shown in FIG. Figure 1 (a) The same components are denoted by the same reference numerals, and description thereof will be omitted.

[0241] In the endoscope illumination system of the ninth example, two light-transmitting members are used. The endoscope illumination system 160 includes a first light-transmitting member 161 and a second light-transmitting member 162. The first light-transmitting member 161 is located between the emission surface and the second light-transmitting member 162.

[0242] The first light-transmitting member 161 has an inner surface 163. The inner surface 163 has an incident-side optical surface 3.

[0243] The second light-transmitting member 162 has an outer surface 164 . The outer surface 164 has an exit-side optical surface 4 and an outer peripheral surface 165 .

[0244] It is preferred that the first light-transmitting member 161 is in close contact with the second light-transmitting member 162. Figure 13In the embodiment, a gap is provided between the first light transmitting member 161 and the second light transmitting member 162 for easy observation.

[0245] In the endoscope lighting system of this embodiment, it is preferred that the first area and the second area are areas where the insertion part is divided into two parts by a virtual plane including the center axis, and an exit surface, an incident side optical surface and an exit side optical surface are provided in each area of the first area and the second area.

[0246] Figure 14 1 is a diagram showing an endoscope lighting system according to this embodiment. Figure 14 (a) is a front view of the front end of the insertion portion. Figure 14 (b) is a cross-sectional view of the front end of the insertion portion taken along the cutting line AA.

[0247] The endoscope lighting system 170 will be described. The endoscope lighting system 170 is a tenth example of the endoscope lighting system of this embodiment. The endoscope lighting system 170 is disposed in the insertion portion 171 .

[0248] Insertion portion 171 can be divided into two regions by a virtual plane including central axis 172. Line 173 indicates the position of the virtual plane. One of the two regions is referred to as first region 174, and the other is referred to as second region 175.

[0249] The endoscope lighting system 170 includes an endoscope lighting system 180 and an endoscope lighting system 190. The endoscope lighting system 180 is located in a first area 174. The endoscope lighting system 190 is located in a second area 175.

[0250] The endoscope illumination system 180 includes an emission surface 181, an incident optical surface 182, and an emission optical surface 183. The emission surface 181 is an end surface of a light guide 184. Illumination light emitted from the emission surface 181 is incident on the incident optical surface 182.

[0251] The incident-side optical surface 182 includes an inner light distribution surface 182a and an outer light distribution surface 182b. The outer light distribution surface 182b is located farther from the central axis 172 than the inner light distribution surface 182a. The central axis 172 is the central axis of the insertion portion 171.

[0252] The inner light distribution surface 182a has a first inner side surface. The first inner side surface is a curved surface convex toward the emission surface 181. Figure 14 In (b), the inner light distribution surface 182a is formed only by a curved surface that is convex toward the emission surface 181. Therefore, the inner light distribution surface 182a is formed only by the first inner side surface. The outer light distribution surface 182b is a flat surface.

[0253] The endoscope illumination system 190 includes an emission surface 191, an incident optical surface 192, and an emission optical surface 193. The emission surface 191 is an end surface of a light guide 194. Illumination light emitted from the emission surface 191 is incident on the incident optical surface 192.

[0254] The incident-side optical surface 192 includes an inner light distribution surface 192a and an outer light distribution surface 192b. The outer light distribution surface 192b is located farther from the central axis 172 than the inner light distribution surface 192a.

[0255] The inner light distribution surface 192a has a first inner side surface. The first inner side surface is a curved surface convex toward the emission surface 191. Figure 14 In (b), the inner light distribution surface 192a is formed only by a curved surface that is convex toward the emission surface 191. Therefore, the inner light distribution surface 192a is formed only by the first inner side surface. The outer light distribution surface 192b is a flat surface.

[0256] exist Figure 14 In (a), the shape of the emission surface 181 and the shape of the emission surface 191 are parts of a ring. The shape of the emission surface can be a circle, an ellipse, a polygon, or a comb shape (a shape in which one side of a rectangle is an arc).

[0257] In the endoscope lighting system of this embodiment, it is preferred that the exit surface in the first area is the same as the exit surface in the second area, the incident side optical surface in the first area is the same as the incident side optical surface in the second area, and the exit side optical surface in the first area is the same as the exit side optical surface in the second area.

[0258] In the endoscope illumination system 170, the endoscope illumination system 180 is identical to the endoscope illumination system 190. The shape of the exit surface 191 is identical to the shape of the exit surface 181. The shape of the incident-side optical surface 192 is identical to the shape of the incident-side optical surface 182. The shape of the exit-side optical surface 193 is identical to the shape of the exit-side optical surface 183.

[0259] In the endoscope illumination system of the present embodiment, preferably, the incident-side optical surface in the first region is different from the incident-side optical surface in the second region.

[0260] Figure 15 1 is a diagram showing an endoscope lighting system according to this embodiment. Figure 15 (a) is a diagram showing an endoscope lighting system according to an eleventh example. Figure 15 (b) is a diagram showing an endoscope lighting system of the twelfth example. Figure 14 (b) The same components are denoted by the same reference numerals and their description is omitted.

[0261] use Figure 15(a) of the present invention will describe an endoscope lighting system 200 . The endoscope lighting system 200 is an eleventh example of the endoscope lighting system of the present embodiment. The endoscope lighting system 200 is disposed in the insertion portion 171 .

[0262] The endoscope lighting system 200 includes the endoscope lighting system 180 and the endoscope lighting system 210. The endoscope lighting system 210 is located in the second area 175.

[0263] The endoscope illumination system 210 includes an emission surface 191 , an incident-side optical surface 211 , and an emission-side optical surface 193 . The illumination light emitted from the emission surface 191 is incident on the incident-side optical surface 211 .

[0264] The incident-side optical surface 211 includes an inner light distribution surface 211 a and an outer light distribution surface 211 b . The outer light distribution surface 211 b is located farther from the central axis 172 than the inner light distribution surface 211 a .

[0265] The inner light distribution surface 211a has a first inner side surface. The first inner side surface is a curved surface convex toward the emission surface 191. Figure 15 In (a), the inner light distribution surface 211a is formed only by a curved surface that is convex toward the emission surface 191. Therefore, the inner light distribution surface 211a is formed only by the first inner side surface. The outer light distribution surface 211b is a curved surface that is concave toward the emission surface 191.

[0266] The endoscope illumination system 200 differs from the endoscope illumination system 180 and the endoscope illumination system 210. The shape of the incident-side optical surface 211 differs from the shape of the incident-side optical surface 182. While the outer light distribution surface 182b of the endoscope illumination system 180 is flat, the outer light distribution surface 211b of the endoscope illumination system 210 is curved.

[0267] use Figure 15 (b) The endoscope lighting system 220 will be described. The endoscope lighting system 220 is a twelfth example of the endoscope lighting system of this embodiment. The endoscope lighting system 220 is disposed in the insertion portion 171 .

[0268] The endoscope lighting system 220 includes the endoscope lighting system 180 and the endoscope lighting system 230. The endoscope lighting system 230 is located in the second area 175.

[0269] The endoscope illumination system 230 includes an emission surface 191 , an incident-side optical surface 231 , and an emission-side optical surface 193 . The illumination light emitted from the emission surface 191 is incident on the incident-side optical surface 231 .

[0270] The incident-side optical surface 231 includes an inner light distribution surface 231 a and an outer light distribution surface 231 b . The outer light distribution surface 231 b is located farther from the central axis 172 than the inner light distribution surface 231 a .

[0271] The inner light distribution surface 231a has a first inner side surface 231a1 and a second inner side surface 231a2. The first inner side surface 231a1 is a curved surface convex toward the emission surface 191. The second inner side surface 231a2 is a flat surface. The outer light distribution surface 231b is a flat surface.

[0272] The endoscope illumination system 220 differs from the endoscope illumination system 180 and the endoscope illumination system 230. The shape of the incident-side optical surface 231 differs from the shape of the incident-side optical surface 182. In the endoscope illumination system 180, the inner light distribution surface 182b is formed solely of a curved surface. In contrast, in the endoscope illumination system 230, the inner light distribution surface 231a is formed of both a flat surface and a curved surface.

[0273] Figure 16 1 is a diagram showing an endoscope lighting system according to this embodiment. Figure 16 13 is a diagram showing an endoscope lighting system according to the 13th example. Figure 15 (b) The same components are denoted by the same reference numerals and their description is omitted.

[0274] use Figure 16 The endoscope lighting system 240 will be described. The endoscope lighting system 240 is a thirteenth example of the endoscope lighting system of this embodiment. The endoscope lighting system 240 is disposed in the insertion portion 171 .

[0275] The endoscope lighting system 240 includes the endoscope lighting system 230 and the endoscope lighting system 250. The endoscope lighting system 250 is located in the first area 174.

[0276] The endoscope illumination system 250 includes an emission surface 181 , an incident-side optical surface 251 , and an emission-side optical surface 183 . The illumination light emitted from the emission surface 181 is incident on the incident-side optical surface 251 .

[0277] The incident-side optical surface 251 includes an inner light distribution surface 251 a and an outer light distribution surface 251 b . The outer light distribution surface 251 b is located farther from the central axis 172 than the inner light distribution surface 251 a .

[0278] The inner light distribution surface 251a has a first inner side surface 251a1 and a second inner side surface 251a2. The first inner side surface 251a1 is a curved surface convex toward the emission surface 181. The second inner side surface 251a2 is a flat surface. The outer light distribution surface 251b is a flat surface.

[0279] In the endoscope lighting system 240, the endoscope lighting system 230 is different from the endoscope lighting system 250. The width of the first inner side surface 251a1 is different from the width of the first inner side surface 231a1. The width of the second inner side surface 251a2 is different from the width of the second inner side surface 231a2.

[0280] Figure 17 1 is a diagram showing an endoscope lighting system according to this embodiment. Figure 17 (a) is a diagram showing an endoscope lighting system of a fourteenth example. Figure 17 (b) is a diagram showing an endoscope lighting system of the fifteenth example.

[0281] use Figure 17 (a) will now describe an endoscope illumination system 270 . The endoscope illumination system 270 is a fourteenth example of the endoscope illumination system of this embodiment. The endoscope illumination system 270 includes an emission surface 271 , an emission surface 272 , and an emission surface 273 .

[0282] An incident-side optical surface and an exit-side optical surface are provided at a position facing the exit surface 271 , a position facing the exit surface 272 , and a position facing the exit surface 273 .

[0283] The endoscope illumination system 270 uses three exit surfaces. Therefore, the number of incident-side optical surfaces and the number of exit-side optical surfaces are also three. One exit surface can be the same as or different from the other exit surfaces. One incident-side optical surface can be the same as or different from the other incident-side optical surfaces.

[0284] use Figure 17 (b) will now describe an endoscope lighting system 280 . The endoscope lighting system 280 is a fifteenth example of the endoscope lighting system of this embodiment. The endoscope lighting system 280 includes an emission surface 281 , an emission surface 282 , an emission surface 283 , and an emission surface 284 .

[0285] An incident-side optical surface and an exit-side optical surface are provided at a position facing the exit surface 281 , a position facing the exit surface 282 , a position facing the exit surface 283 , and a position facing the exit surface 284 .

[0286] Endoscope illumination system 280 uses four exit surfaces. Therefore, the number of incident-side optical surfaces and the number of exit-side optical surfaces are also four. One exit surface can be identical to or different from the other exit surfaces. One incident-side optical surface can be identical to or different from the other incident-side optical surfaces.

[0287] A cylindrical space 285 is formed in the center of the insertion portion. For example, an objective optical system can be disposed in space 285. In the endoscope illumination system of the fifteenth example, the central axis of space 285 coincides with the central axis of the insertion portion. Therefore, in the endoscope illumination system of the fifteenth example, when the objective optical system is disposed in space 285, the objective optical system is not eccentric relative to the center of the insertion portion.

[0288] In the endoscope illumination system of the present embodiment, preferably, the emission surface in the first region is different from the emission surface in the second region.

[0289] Figure 18 and Figure 19 It is a diagram showing the endoscope lighting system and light distribution according to this embodiment. Figure 18 (a) and Figure 19 (a) is a diagram showing an endoscope lighting system of a sixteenth example. Figure 18 (b) and Figure 19 (b) is a graph showing the distribution of illumination light. Figure 14 (b) The same components are denoted by the same reference numerals and their description is omitted.

[0290] and Figure 17 Similarly to the endoscope lighting system 280 shown in (b), the endoscope lighting system of the sixteenth example has four endoscope lighting systems. As described above, in the endoscope lighting system 280, the central axis of the space 285 coincides with the central axis of the insertion portion. In contrast, in the endoscope lighting system of the sixteenth example, the central axis of the cylindrical space is eccentric relative to the central axis of the insertion portion.

[0291] In the endoscope illumination system 280, the direction from the endoscope illumination system 283 toward the endoscope illumination system 281 is defined as the first direction, and the direction from the endoscope illumination system 282 toward the endoscope illumination system 284 is defined as the second direction. In the endoscope illumination system of the sixteenth example, the cylindrical space is eccentric in the first direction but not in the second direction.

[0292] In the endoscope illumination system of the sixteenth example, the endoscope illumination system 290 is arranged in the first direction, and the endoscope illumination system 320 is arranged in the second direction.

[0293] use Figure 18 (a) will now describe the endoscope illumination system 290 . The endoscope illumination system 290 is disposed in the insertion portion 171 . The endoscope illumination system 290 includes an endoscope illumination system 300 and the endoscope illumination system 190 . The endoscope illumination system 300 is located in the first region 174 .

[0294] The endoscope illumination system 300 includes an emission surface 301, an incident-side optical surface 302, and an emission-side optical surface 183. The emission surface 301 is an end surface of the light guide 303. Illumination light emitted from the emission surface 301 is incident on the incident-side optical surface 302.

[0295] The incident-side optical surface 302 includes an inner light distribution surface 302a and an outer light distribution surface 302b. The outer light distribution surface 302b is located farther from the central axis 172 than the inner light distribution surface 302a.

[0296] The inner light distribution surface 302a has a first inner side surface. The first inner side surface is a curved surface convex toward the light exiting surface 301. Figure 18 In (a), the inner light distribution surface 302a is formed only by a curved surface that is convex toward the emission surface 301. Therefore, the inner light distribution surface 302a is formed only by the first inner side surface. The outer light distribution surface 302b is a flat surface.

[0297] In the first direction, the central axis of cylindrical space 310 is eccentric relative to central axis 172. More than half of space 310 is located in first region 174. In this case, the range in which the endoscope lighting system can be placed in first region 174 is narrower than the range in second region 175 in which the endoscope lighting system can be placed.

[0298] Therefore, in the endoscope illumination system 290, the endoscope illumination system 300 is different from the endoscope illumination system 190. The width of the exit surface 301 is different from the width of the exit surface 191. The width of the exit surface 301 is narrower than the width of the exit surface 191. The shape of the incident-side optical surface 302 is different from the shape of the incident-side optical surface 192. The width of the incident-side optical surface 302 is narrower than the width of the incident-side optical surface 192.

[0299] exist Figure 18 In (b), the solid line shows the distribution of illumination light in the endoscope illumination system 290, and the dotted line shows the distribution of illumination light in a conventional endoscope illumination system (not shown). The horizontal axis is angle, and the vertical axis is intensity.

[0300] In the endoscope lighting system 290, the angle at which the intensity is zero is less than 80°. In contrast, in conventional endoscope lighting systems, the angle at which the intensity is zero is approximately 80°. If the size of the angle represents the width of the lighting range, then Figure 18 (b) shows a case where the illumination range of the endoscope illumination system 290 is narrower than that of a conventional endoscope illumination system.

[0301] If the illumination range is narrower than the illumination range, the amount of illumination light irradiated outside the observation range is also small. Therefore, compared with conventional endoscope illumination systems, the endoscope illumination system 290 can illuminate the observation range more efficiently.

[0302] use Figure 19 (a) will now describe the endoscope lighting system 320. The endoscope lighting system 320 is disposed in the insertion portion 171. The endoscope lighting system 320 includes an endoscope lighting system 330 and an endoscope lighting system 340. The endoscope lighting system 330 is located in the third region 174'. The endoscope lighting system 340 is located in the fourth region 175'.

[0303] The third and fourth areas are areas where the insertion portion is divided into two parts by different virtual planes. Figure 14 A surface of a straight line that is orthogonal to the straight line 173 shown in (a).

[0304] The endoscope illumination system 330 includes an emission surface 331, an incident-side optical surface 332, and an emission-side optical surface 183. The emission surface 331 is an end surface of the light guide 333. Illumination light emitted from the emission surface 331 is incident on the incident-side optical surface 332.

[0305] The incident-side optical surface 332 includes an inner light distribution surface 332a and an outer light distribution surface 332b. The outer light distribution surface 332b is located farther from the central axis 172 than the inner light distribution surface 332a.

[0306] The inner light distribution surface 332a has a first inner side surface. The first inner side surface is a curved surface convex toward the emission surface 331. Figure 19 In (a), the inner light distribution surface 332a is formed only by a curved surface that is convex toward the emission surface 331. Therefore, the inner light distribution surface 332a is formed only by the first inner side surface. The outer light distribution surface 332b is a flat surface.

[0307] The endoscope illumination system 340 includes an emission surface 341, an incident-side optical surface 342, and an emission-side optical surface 193. The emission surface 341 is an end surface of the light guide 343. Illumination light emitted from the emission surface 341 is incident on the incident-side optical surface 342.

[0308] The incident-side optical surface 342 includes an inner light distribution surface 342a and an outer light distribution surface 342b. The outer light distribution surface 342b is located farther from the central axis 172 than the inner light distribution surface 342a.

[0309] The inner light distribution surface 342a has a first inner side surface. The first inner side surface is a curved surface convex toward the emission surface 341. Figure 19 In (a), the inner light distribution surface 342a is formed only by a curved surface that is convex toward the emission surface 341. Therefore, the inner light distribution surface 342a is formed only by the first inner side surface. The outer light distribution surface 342b is a flat surface.

[0310] In the second direction, the central axis of cylindrical space 310 is not eccentric relative to central axis 172. Half of space 310 is located in first region 174', and the remaining half is located in second region 175'. In this case, the range within which the endoscope lighting system can be placed in first region 174' is the same as the range within second region 175' within which the endoscope lighting system can be placed.

[0311] Therefore, in the endoscope illumination system 320, the endoscope illumination system 330 is identical to the endoscope illumination system 340. The shape of the exit surface 341 is identical to the shape of the exit surface 331. The shape of the incident-side optical surface 342 is identical to the shape of the incident-side optical surface 332. The shape of the exit-side optical surface 193 is identical to the shape of the exit-side optical surface 183.

[0312] exist Figure 19 In (b), the solid line shows the distribution of illumination light in the endoscope illumination system 320, and the dotted line shows the distribution of illumination light in a conventional endoscope illumination system (not shown). The horizontal axis represents angle, and the vertical axis represents intensity.

[0313] In the endoscope lighting system 320, the angle at which the intensity is zero is less than 80°. In contrast, in conventional endoscope lighting systems, the angle at which the intensity is zero is approximately 80°. If the size of the angle represents the width of the lighting range, then Figure 19 (b) shows a case where the illumination range of the endoscope illumination system 320 is narrower than that of a conventional endoscope illumination system.

[0314] If the illumination range is narrower than the illumination range, the amount of illumination light irradiated outside the observation range is also small. Therefore, compared with conventional endoscope illumination systems, the endoscope illumination system 320 can illuminate the observation range more efficiently.

[0315] The endoscope lighting system of this embodiment is provided with an exit surface, an incident side optical surface, and an exit side optical surface not only in the first and second regions, but also in each of the third and fourth regions. The third and fourth regions are regions where the insertion portion is divided into two parts by a virtual plane orthogonal to the virtual plane. The incident side optical surface in the second region is larger than the incident side optical surface in the first region and satisfies the following conditional expression (2). The incident side optical surface in the third region is the same as the incident side optical surface in the fourth region and satisfies the following conditional expression (3).

[0316] 8≤din2 / dout2≤32 (2)

[0317] 8≤din3 / dout3≤26 (3)

[0318] Here,

[0319] din2 is the width of the inner light distribution surface in the second area,

[0320] dout2 is the width of the outer light distribution surface in the second area,

[0321] din3 is the width of the inner light distribution surface in the third area,

[0322] dout3 is the width of the outer light distribution surface in the third area.

[0323] As described above, in the endoscope illumination system of the sixteenth example, the incident optical surface 192 in the second region 175 is larger than the incident optical surface 302 in the first region 174. The incident optical surface 332 in the third region 174' is identical to the incident optical surface 342 in the fourth region 175'.

[0324] The following lists the corresponding values of conditional expression (2) and conditional expression (3) for the endoscope illumination system of the sixteenth example. For reference, the values of the ratio of the width of the inner light distribution surface (din1, din4) to the width of the outer light distribution surface (dout1, dout4) are also listed for the first and fourth regions.

[0325]

[0326] The endoscope lighting system of the sixteenth example satisfies conditional expressions (2) and (3). By satisfying conditional expressions (2) and (3), it is possible to prevent a decrease in lighting efficiency while ensuring a wide light distribution.

[0327] For example, an objective optical system can be arranged in cylindrical space 310. In the first direction, the central axis of cylindrical space 310 is eccentric relative to central axis 172. Therefore, when an objective optical system is arranged in space 310, the objective optical system is eccentric relative to the center of the insertion portion. However, since conditional expressions (2) and (3) are satisfied, it is possible to prevent a decrease in illumination efficiency while ensuring a wide light distribution.

[0328] The endoscope of the present embodiment includes the endoscope illumination system of the present embodiment and an objective optical system. The endoscope illumination system is located farther from the central axis than the objective optical system.

[0329] Figure 20 FIG is a diagram showing an endoscope system. Figure 20 In the figure, only a part of the endoscope is depicted in an enlarged manner in order to explain the structure of the endoscope.

[0330] The endoscope system 350 includes an endoscope 360 and an image processing device 370. The endoscope 360 includes a scope 360a and a connection line 360b. A display unit 380 is connected to the image processing device 370.

[0331] The scope 360a is broadly divided into an operating section 390 and an insertion section 391. The insertion section 391 is elongated and can be inserted into a patient's body cavity. Furthermore, the insertion section 391 is made of a flexible member. The observer can perform various operations using the angle knob and other components provided on the operating section 390.

[0332] Furthermore, a connection line portion 360 b extends from the operation portion 390 . The connection line portion 360 b includes a universal cable 400 . The universal cable 400 is connected to the image processing device 370 via a connector 410 .

[0333] Universal cable 400 is used to transmit and receive various signals. Examples of these signals include power supply voltage signals and CCD drive signals. These signals are transmitted from the power supply unit or video processor to the mirror body 360a. Another example of these signals is an image signal, which is transmitted from the mirror body 360a to the video processor.

[0334] The video processor in the image processing device 370 can be connected to peripheral devices such as a video printer (not shown). The video processor processes the image signal from the scope 360a and displays the endoscopic image on the display screen of the display unit 380 based on the image signal.

[0335] Figure 21 is a cross-sectional view of the front end of the insertion portion. Figure 14 (a) Figure 14 (b) The same components are denoted by the same reference numerals and their description is omitted.

[0336] The endoscope illumination system 170 and the objective optical system 420 are disposed at the distal end of the insertion portion 391. The endoscope illumination system 170 is located farther from the central axis 172 than the objective optical system 420.

[0337] An image of the object is formed by the objective optical system 420. The image of the object is captured by the imaging element 430. As a result, an image of the object can be acquired.

[0338] exist Figure 21 , the objective optical system 420 is not eccentric with respect to the central axis 172. Therefore, the optical axis of the objective optical system 420 coincides with the central axis 172. However, the objective optical system 420 may also be eccentric with respect to the central axis 172.

[0339] The endoscope lighting system of this embodiment is an endoscope lighting system configured at an insertion portion, and comprises an exit surface for emitting illumination light, an incident side optical surface for receiving illumination light, and an exit side optical surface for emitting illumination light. The incident side optical surface comprises a first plane, a first curved surface connected to the first plane, and a second plane connected to the first curved surface, arranged in sequence from the side close to the central axis of the insertion portion. The exit side optical surface comprises a third plane, and a second curved surface connected to the third plane, arranged in sequence from the side close to the central axis of the insertion portion. The first curved surface is a surface convex toward the exit surface, and the second curved surface is a surface convex outward.

[0340] Figure 22 1 is a diagram showing an endoscope lighting system according to this embodiment. Figure 22 17 is a diagram showing an endoscope lighting system. Figure 5 The same components are denoted by the same reference numerals, and description thereof will be omitted.

[0341] The endoscope illumination system 500 is an endoscope illumination system according to the seventeenth example and includes the emission surface 2 , an incident-side optical surface 51 , and an emission-side optical surface 510 .

[0342] The second inner side surface 51a2 is set as the first flat surface, the first inner side surface 51a1 is set as the first curved surface, and the outer light distribution surface 51b is set as the second flat surface. In this case, the incident-side optical surface 51 includes, starting from the side closest to the central axis 5 of the insertion portion, a first flat surface, a first curved surface connected to the first flat surface, and a second flat surface connected to the first curved surface. The first curved surface is a surface convex toward the exit surface 2.

[0343] The light-emitting optical surface 510 includes a first light-emitting side surface 510a and a second light-emitting side surface 510b. The first light-emitting side surface 510a is a flat surface, and the second light-emitting side surface 510b is a curved surface.

[0344] The first emission side surface 510a is set as the third plane, and the second emission side surface 510b is set as the second curved surface. In this case, the emission side optical surface 510 has a third plane and a second curved surface connected to the third plane, which are arranged in sequence from the side closest to the central axis 5 of the insertion portion. The second curved surface is a surface with a convex shape toward the outside.

[0345] In the endoscope illumination system of the present embodiment, preferably, a straight line parallel to the central axis and passing through a boundary between the first curved surface and the second flat surface intersects the second curved surface.

[0346] exist Figure 22 5. A straight line 520 is shown in FIG. The straight line 520 is parallel to the central axis and passes through the boundary between the first curved surface and the second plane. In the endoscope illumination system 500, the straight line 520 intersects the second emission side surface 510b, that is, the second curved surface.

[0347] In the endoscope illumination system of the present embodiment, it is preferable that the ratio of light rays passing through the first curved surface and the third flat surface is 70% or more of the entire light rays emitted from the emission surface.

[0348] Light rays emitted from the exit surface pass through the incident-side optical surface and the exit-side optical surface. As described above, the incident-side optical surface has a first flat surface, a first curved surface, and a second flat surface. The exit-side optical surface has a third flat surface and a second curved surface. Therefore, the light rays emitted perpendicularly from the exit surface can be divided into a first light group, a second light group, a third light group, and a fourth light group.

[0349] The first ray group is formed by rays passing through the first plane and the third plane. The second ray group is formed by rays passing through the first curved surface and the third plane. The third ray group is formed by rays passing through the first curved surface and the second curved surface. The fourth ray group is formed by rays passing through the second plane and the second curved surface.

[0350] Curved surfaces are susceptible to manufacturing errors. Therefore, the relative positions of the first and second curved surfaces, as well as the angles between them, are susceptible to deviation. The third light group is formed by light rays passing through the first and second curved surfaces. The greater the number of third light groups, the greater the deviation in light distribution due to manufacturing errors.

[0351] The first curved surface is necessary to achieve a wide light distribution. Therefore, by increasing the number of rays passing through the third plane, the number of rays passing through the second curved surface can be reduced. The second light group is formed by rays passing through the first curved surface and the third plane. Therefore, by ensuring that the proportion of the second light group accounts for at least 70% of the total number of rays passing through the first curved surface, a lighting design less susceptible to manufacturing errors can be achieved.

[0352] In the endoscope illumination system of the present embodiment, it is preferable that the emission surface includes a first emission surface located in the first region and a second emission surface located in the second region, and satisfies the following conditional expression (4).

[0353] 120°≤α+β (4)

[0354] Here,

[0355] α is the central angle of the fan-shaped area including the first exit surface,

[0356] β is the central angle of the fan-shaped area including the second exit surface,

[0357] A sector is a shape formed by two radii of a specified circle and the arc between them.

[0358] The predetermined circle is a circle centered on the central axis within a virtual plane perpendicular to the central axis.

[0359] Figure 23 1 is a diagram showing an endoscope lighting system according to this embodiment. Figure 23 FIG. 1 is a diagram showing an endoscope lighting system according to an eighteenth example.

[0360] Endoscope illumination system 600 is the eighteenth example of an endoscope illumination system in this embodiment. In endoscope illumination system 600, the emission surface includes a first emission surface 601 and a second emission surface 602. First emission surface 601 is located in a first region 603, and second emission surface 602 is located in a second region 604. First region 603 and second region 604 are two regions defined by a virtual plane including a central axis 605. Line 606 indicates the position of the virtual plane.

[0361] First emission surface 601 is included in sector-shaped region 607. Second emission surface 602 is included in sector-shaped region 608. Sector-shaped region 607 and sector-shaped region 608 are figures enclosed by two radii of a prescribed circle and an arc located therebetween. The prescribed circle is a circle centered on central axis 605 within a virtual plane perpendicular to central axis 605.

[0362] In the endoscope illumination system 600 , light emitted from the first emission surface 601 travels toward the second region 604 , and light emitted from the second emission surface 602 travels toward the first region 603 .

[0363] If the first emission surface 601 is enlarged, more light travels toward the second area 604. If the second emission surface 602 is enlarged, more light travels toward the first area 603. As a result, a wide and bright illumination range in front can be provided.

[0364] Angle α is the central angle of sector-shaped area 607. If the first exit surface 601 becomes larger, angle α becomes larger. Angle β is the central angle of sector-shaped area 608. If the second exit surface 602 becomes larger, angle β becomes larger.

[0365] When the conditional expression (4) is satisfied, the first emission surface 601 and the second emission surface 602 can be made sufficiently large. As a result, a wide and bright illumination range can be provided. Figure 23 , α+β=220°.

[0366] If conditional expression (4) is not satisfied, the first exit surface 601 and the second exit surface 602 cannot be made sufficiently large. In this case, the range indicated by the arrow becomes larger. Within the range indicated by the arrow, the illumination light does not reach or the illumination light that reaches is small. Therefore, it is impossible to illuminate the illumination range broadly and brightly.

[0367] It is preferable to satisfy the conditional expression (4') instead of the conditional expression (4).

[0368] 180°≤α+β (4')

[0369] When conditional expression (4') is satisfied, a wider and brighter illumination range can be provided.

[0370] In space 609, as Figure 21 As shown in FIG, an objective optical system and an imaging element are arranged. Figure 23 The light receiving surface 610 of the imaging element is shown in FIG. As the angles α and β increase, more light travels diagonally to the light receiving surface 610 .

[0371] As described above, when conditional expression (4) is satisfied, the forward illumination range can be illuminated broadly and brightly, thereby enabling a good image capture of the object.

[0372] exist Figure 23 In the embodiment, the space 609 is not eccentric with respect to the central axis 605. However, the space 609 may also be Figure 18 The endoscope lighting system 290 shown in (a) is similarly eccentric with respect to the central axis 609. In this case, the front lighting range can be illuminated broadly and brightly by satisfying the conditional expression (4). Therefore, the object can be well photographed.

[0373] In the endoscope illumination system of the present embodiment, preferably, the width of the second inner side surface varies depending on the position.

[0374] Figure 24 (a) and (b) are diagrams showing the endoscope lighting system according to the present embodiment. Figure 24 FIG. 1 is a diagram showing an endoscope lighting system according to a nineteenth example. Figure 24 (a) is a diagram showing an endoscope lighting system in an eccentric direction. Figure 24 (b) is a diagram showing an endoscope lighting system in a non-eccentric direction. Figure 16 The same components are denoted by the same reference numerals, and description thereof will be omitted.

[0375] The endoscope illumination system 700 includes the endoscope illumination system 230, the endoscope illumination system 250, the endoscope illumination system 710, and the endoscope illumination system 720. In the endoscope illumination system 700, the objective optical system is eccentric with respect to the center of the insertion portion.

[0376] As mentioned above, the first direction is Figure 17 In the endoscope illumination system 280 shown in (b), the first direction is from the endoscope illumination system 283 toward the endoscope illumination system 281. The second direction is from the endoscope illumination system 282 toward the endoscope illumination system 284. In the endoscope illumination system of the nineteenth example, the cylindrical space is eccentric in the first direction but not in the second direction.

[0377] The endoscope illumination system 710 includes an emission surface 711, an incident-side optical surface 712, and an emission-side optical surface 193. The emission surface 711 is an end surface of a light guide 713. Illumination light emitted from the emission surface 711 is incident on the incident-side optical surface 712.

[0378] The incident-side optical surface 712 includes an inner light distribution surface 712a and an outer light distribution surface 712b. The outer light distribution surface 712b is located farther from the central axis 172 than the inner light distribution surface 712a.

[0379] The inner light distribution surface 712a has a first inner side surface 712a1 and a second inner side surface 712a2. The first inner side surface 712a1 is a curved surface convex toward the emission surface 711. The second inner side surface 712a2 is a flat surface. The outer light distribution surface 712b is a flat surface.

[0380] The endoscope illumination system 720 includes an emission surface 721, an incident-side optical surface 722, and an emission-side optical surface 193. The emission surface 721 is an end surface of the light guide 723. Illumination light emitted from the emission surface 721 is incident on the incident-side optical surface 722.

[0381] The incident-side optical surface 722 includes an inner light distribution surface 722a and an outer light distribution surface 722b. The outer light distribution surface 722b is located farther from the central axis 172 than the inner light distribution surface 722a.

[0382] The inner light distribution surface 722a has a first inner side surface 722a1 and a second inner side surface 722a2. The first inner side surface 722a1 is a curved surface convex toward the emission surface 721. The second inner side surface 722a2 is a flat surface. The outer light distribution surface 722b is a flat surface.

[0383] In the first direction, the central axis of the cylindrical space 310 is eccentric with respect to the central axis 172. More than half of the space 310 is located on the side of the endoscope illumination system 710. In this case, the range where the endoscope illumination system can be placed on the side of the endoscope illumination system 710 is narrower than the range where the endoscope illumination system can be placed on the side of the endoscope illumination system 720.

[0384] Therefore, in the endoscope illumination system 700, the endoscope illumination system 710 is different from the endoscope illumination system 720. The width of the emission surface 711 is different from the width of the emission surface 721. The width of the emission surface 711 is narrower than the width of the emission surface 721.

[0385] The shape of the incident-side optical surface 712 is different from the shape of the incident-side optical surface 722. The width of the incident-side optical surface 712 is narrower than the width of the incident-side optical surface 722. The width of the second inner side surface 712a2 is narrower than the width of the second inner side surface 722a2.

[0386] To maintain uniform light distribution when the objective optical system is off-center relative to the center of the insertion portion, it is desirable to maintain the same positional relationship between the curved surface of the incident-side optical surface and the curved surface of the exit-side optical surface regardless of the location. To maintain this relationship, the width of the second inner surface can be varied depending on the location. This can mitigate uneven light distribution.

[0387] In the endoscope illumination system of this embodiment, the emission surface can be formed by a single surface or multiple surfaces. For example, if the emission surface is in the shape of a ring, the emission surface is formed by a single surface. If the emission surface is in the shape of a partial ring, the emission surface is formed by multiple surfaces. A partial ring is the shape of a ring that has a portion cut away.

[0388] The incident-side optical surface may be formed by a single surface or by multiple surfaces. For example, if the incident-side optical surface is in the shape of a ring, the exit surface is formed by a single surface. If the incident-side optical surface is in the shape of a partial ring, the exit surface is formed by multiple surfaces.

[0389] Industrial applicability

[0390] As described above, the present invention is suitable for an endoscope lighting system having high lighting efficiency and an endoscope including the endoscope lighting system.

[0391] Description of Reference Numerals

[0392] 1, 6: Endoscope lighting system; 2: Output surface; 3, 7: Incident side optical surface; 3a, 7a: Inner light distribution surface (first inner surface); 3b, 7b: Outer light distribution surface; 4: Output side optical surface; 5: Central axis; 10: Light emitting element; 11: Light emitting portion; 12: Sealing resin; 13, 23, 33: Output surface; 20: Light guide; 21: Fiber bundle; 22: Protective tube; 30: Lighting unit; 31: Phosphor; 32: Sealing resin; 33: Output surface; 34: Optical fiber; 40: Endoscope lighting system; 41: Incident side optical surface; 50: Endoscope lighting system; 51: Incident side optical surface; 51a: Inner light distribution surface; 51a1: First inner surface; 51a2: Second inner surface; 51b: Outer Side light distribution surface; 60: Endoscope lighting system; 61: Incident side optical surface; 62: Exit side optical surface; 70, 80, 90, 100: Endoscope lighting system; 71, 81, 91, 101: Exit side optical surface; 71a, 81a, 91a, 101a: First exit side surface; 71b, 81b, 91b, 101b: Second exit side surface; 72, 82, 92, 102: Straight line; 110, 120, 130, 140: Endoscope lighting system; 111, 121, 131, 141: Incident side optical surface; 111a, 131a: Inner light distribution surface; 111b, 131b: Outer light distribution surface; 112, 122, 132, 142: Exit side optical surface; 150, 160: Endoscope illumination system; 151: Light-transmitting member; 152, 163: Inner surface; 153, 164: Outer surface; 154: Inner peripheral surface; 155, 165: Outer peripheral surface; 161: First light-transmitting member; 162: Second light-transmitting member; 170, 180, 190: Endoscope illumination system; 171: Insertion portion; 172: Center axis; 173: Straight line; 174: First region; 175: Second region; 174': Third region; 175': Fourth region; 181, 191: Exiting surface; 182, 192: Incident-side optical surface; 182a, 192a: Inner light distribution surface; 182b, 192b: Outer light distribution surface; 183, 193: Exiting optical surface; 184, 194: Light guide; 200, 210, 220, 230, 240, 250: Endoscope illumination system; 211, 231, 251: Incident-side optical surface; 211a, 231a, 251a: Inner light distribution surface; 211b, 231b, 251b: Outer light distribution surface; 231a1, 251a1: First inner side surface; 231a2, 251a2: Second inner side surface; 270, 280: Endoscope illumination system; 271, 272, 273: Exit surface; 281, 282, 283, 284: Exit surface; 285: Cylindrical space; 290, 300, 320, 330, 340: Endoscope illumination system; 301, 331, 341: Exit surface;302, 332, 342: Incident-side optical surface; 302a, 332a, 342a: Inner light distribution surface; 302b, 332b, 342b: Outer light distribution surface; 303, 333, 343: Light guide; 310: Cylindrical space; 350: Endoscope system; 360: Endoscope; 360a: Mirror body; 360b: Connecting cable; 370: Image processing device; 380: Display unit; 390: Operation unit; 391: Insertion unit; 400: Universal cable; 410: Connector; 420: Objective optical system; 430: Image sensor; 500: Endoscope illumination system; 510a: First emission side surface; 510b: Second emission side surface; 520: Linear; 60 0: Endoscope illumination system; 601: First emission surface; 602: Second emission surface; 603: First area; 604: Second area; 605: Central axis; 606: Line; 607, 608: Fan-shaped areas; 609: Space; 610: Light-receiving surface of the imaging element; 700, 710, 720: Endoscope illumination system; 711, 721: Emission surface; 712, 722: Incident-side optical surface; 713, 723: Light guide; 712a, 722a: Inner light distribution surface; 712b, 722b: Outer light distribution surface; 712a1, 722a1: First inner side surface; 712a2, 722a2: Second inner side surface; IL1, IL2, IL3, IL4: Illumination light.

Claims

1. An endoscope lighting system, disposed at an insertion portion, wherein the endoscope lighting system comprises: an exit surface for emitting illumination light; an optical surface on the incident side into which the illumination light is incident; and an optical surface on the output side for emitting the illumination light, in, The incident side optical surface has an inner light distribution surface and an outer light distribution surface. The outer light distribution surface is located farther from the central axis of the insertion portion than the inner light distribution surface. The inner light distribution surface has a first inner side surface, The first inner side surface is a curved surface convex toward the exit surface. The outer light distribution surface is a flat surface or a curved surface that is concave toward the emission surface. Satisfy the following conditional formula (1), 8≤d1 / d2≤32 (1) Here, d1 is the width of the inner light distribution surface, d2 is the width of the outer light distribution surface.

2. The endoscope lighting system according to claim 1, wherein: The inner light distribution surface has the first inner side surface and the second inner side surface. The second inner side surface is a plane, The second inner side surface is located closer to the central axis than the first inner side surface.

3. The endoscope lighting system according to claim 1, wherein: The optical surface on the exit side has a first exit side surface and a second exit side surface, The first emission side surface is a plane, The second emission side surface is a curved surface, The second emission side surface is located farther from the central axis than the first emission side surface. A straight line parallel to the central axis and passing through a boundary between the first exit side surface and the second exit side surface intersects the exit surface.

4. The endoscope lighting system according to claim 1, wherein: having a light-transmitting member, The inner surface of the light-transmitting member has the incident-side optical surface, The outer side surface of the light-transmitting member has the emission-side optical surface.

5. The endoscope lighting system according to claim 1, wherein: having a first light-transmitting member and a second light-transmitting member, The first light-transmitting member is located between the emission surface and the second light-transmitting member, The inner surface of the first light-transmitting member has the incident-side optical surface, The outer side surface of the second light-transmitting member has the emission-side optical surface.

6. The endoscope lighting system according to claim 1, characterized in that The first area and the second area are areas when the insertion portion is divided into two parts by a virtual plane including the central axis. The emission surface, the incident-side optical surface, and the emission-side optical surface are provided in each of the first region and the second region.

7. The endoscope lighting system according to claim 6, characterized in that: The exit surface in the first region is the same as the exit surface in the second region, the incident side optical surface in the first region is the same as the incident side optical surface in the second region, and the exit side optical surface in the first region is the same as the exit side optical surface in the second region.

8. The endoscope lighting system according to claim 6, characterized in that: The incident-side optical surface in the first region is different from the incident-side optical surface in the second region.

9. The endoscope lighting system according to claim 6, wherein: The exit surface in the first region is different from the exit surface in the second region.

10. The endoscope lighting system according to claim 6, wherein: The third area and the fourth area are areas when the insertion portion is divided into two parts by a virtual plane including the central axis and perpendicular to the virtual plane. The emission surface, the incident side optical surface, and the emission side optical surface are provided in each of the third region and the fourth region. The incident-side optical surface in the second region is larger than the incident-side optical surface in the first region and satisfies the following conditional expression (2): The incident-side optical surface in the third region is identical to the incident-side optical surface in the fourth region and satisfies the following conditional expression (3): 8≤din2 / dout2≤32 (2) 8≤din3 / dout3≤26 (3) Here, din2 is the width of the inner light distribution surface in the second area, dout2 is the width of the outer light distribution surface in the second area, din3 is the width of the inner light distribution surface in the third area, dout3 is the width of the outer light distribution surface in the third area.

11. An endoscope lighting system, disposed at an insertion portion, characterized in that it comprises: an exit surface for emitting illumination light; an optical surface on the incident side into which the illumination light is incident; and an optical surface on the output side for emitting the illumination light, in, The incident side optical surface includes a first flat surface, a first curved surface connected to the first flat surface, and a second flat surface connected to the first curved surface, which are sequentially arranged from the side close to the central axis of the insertion portion. The light-emitting side optical surface includes a third plane and a second curved surface connected to the third plane, which are sequentially arranged from the side close to the central axis of the insertion portion. The first curved surface is a surface convex toward the exit surface. The second curved surface is a surface convex outward.

12. The endoscope lighting system according to claim 11, characterized in that: A straight line parallel to the central axis and passing through a boundary between the first curved surface and the second plane intersects the second curved surface.

13. An endoscope comprising: The endoscope lighting system according to claim 1 or 11; and Objective optical system, in, The endoscope illumination system is located farther from the central axis than the objective optical system.

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