Lens unit

Abstract

Provided is a lens unit capable of stably fixing a flange part of a lens, and thus easily focusing the lens. The lens unit 10A includes: a lens 11a that has a lens unit 30 formed in a center and a flange part 32 extending radially outward from the peripheral edge of the lens part 30 and having a rear-end surface 26 on the rear side thereof; a transparent spacer 13a disposed behind the lens 11a in the optical axis direction and used for focusing the lens unit 30, the spacer having a front-end surface 34 facing the rear side of the lens 11a, a separation part 38 facing the lens unit 30 and separated from the lens unit 30 to the rear side in the optical axis direction, and a fixed peripheral edge part 39 extending radially outward from the peripheral edge of the separation part 38; and an adhesive 29b that is disposed between the rear-end surface 26 of the flange part 32 and the fixed peripheral edge part 39 and fixes the lens 11a and the spacer 13a.

Description

[Technical field]

[0001] The present invention relates to a small lens unit that is connected to various sensor modules. [Background technology]

[0002] Various medical endoscopes, such as brain endoscopes, otolaryngological scopes, thoracoscopes, and laparoscopes, are used for diagnosis and treatment. In addition to medical endoscopes, industrial endoscopes are also used for various examinations. In these endoscopes, a small lens unit is installed at the tip of a sensor module (scope). For example, as shown in FIG. 16, the small lens unit has a cover glass 14, an aperture means 12, a lens 11, and a sensor cover member 15, which are arranged in the optical axis direction. In the small lens unit 10H shown in FIG. 16, the flange portion 32 of the lens 11 directly abuts against the sensor cover member 15 to perform focusing, and the abutting surface 26 (rear end surface) of the abutted flange portion 32 and the front end surface 41 of the sensor cover member 15 are fixed by an adhesive 29.

[0003] As an invention relating to a lens unit, a lens unit has been disclosed in which a resin molded portion is formed on a glass substrate, and multiple wafer lenses each having a lens portion formed on a part of the resin molded portion are stacked together (for example, Patent No. 5464502). The lens unit has an exterior member. The exterior member covers the lens unit from the outside, and has an opening through which light is incident on the lens portion. The resin molded portion around the periphery of a first lens portion formed closest to the object forms a protrusion that protrudes toward the object side. The protrusion has an inclined portion whose diameter increases toward the image side on the side opposite the first lens portion, and the opening of the exterior member has an inclined opening into which the inclined portion fits. Summary of the Invention [Problem to be solved by the invention]

[0004] 16, in the method of butting the flange portion 32 of the small lens unit 10H against the cover member for the sensor 15, the flange portion 32 has a structure that allows it to be moved out of the way so as not to interfere with the optical path. The length of the flange portion 32 in the optical axis direction becomes long, and the area of ​​the butt surface 26 (rear end surface) of the flange portion 32 becomes small, making it difficult to stably fix the butt surface 26 of the flange portion 32 to the front end surface 41 of the cover member for the sensor 15. When the abutment surface 26 (rear end surface) and the front end surface 41 are fixed with an adhesive, reducing the amount of adhesive reduces the adhesion area and the fixing strength. Therefore, when a certain load is applied to the flange portion 32, the abutment surface 26 of the flange portion 32 and its vicinity are easily damaged or broken. Furthermore, when the back focus of the lens 11 is increased, the extension dimension of the flange portion 32 toward the rear in the optical axis direction is inevitably increased. Therefore, the area of ​​the abutment surface 26 (rear end surface) becomes extremely small, making it even more difficult to stably fix the abutment surface 26 and the front end surface 41 together.

[0005] An object of the present invention is to provide a lens unit in which the flange portion of the lens can be stably fixed and the lens can be easily focused. [Means for solving the problem]

[0006] The lens unit of the present invention comprises: A lens, A lens portion formed in the center; a flange portion extending radially outward from a periphery of the lens portion, the flange portion having a rear end surface at a rear side; a lens having A transparent spacer is disposed behind the lens in the optical axis direction and used for focusing the lens portion, a front end surface facing the rear of the lens; a separation portion facing the lens portion and separated from the lens portion rearward in the optical axis direction; a fixed peripheral portion extending radially outward from a peripheral edge of the spaced portion; a spacer having an adhesive disposed between the rear end surface of the flange portion and the fixing peripheral portion, the adhesive fixing the lens and the spacer; has. Effect of the Invention

[0007] According to the lens unit of the present invention, the flange portion of the lens can be stably fixed, and the lens can be easily focused. [Brief description of the drawings]

[0008] [Figure 1] A perspective view showing a small lens unit. [Diagram 2] 2 is a cross-sectional view of the small lens unit according to the first embodiment taken along line AA in FIG. [Diagram 3] FIG. 2 is a perspective view of a holder accommodating the small lens unit of FIG. 1; [Figure 4] Cross section of line BB in Figure 3 [Diagram 5] 2 is a cross-sectional view of the small lens unit according to the second embodiment taken along line AA in FIG. [Figure 6] 4 is a cross-sectional view taken along line BB in FIG. 3 of the small lens unit of the second embodiment housed in a holder. [Figure 7] 1. A cross-sectional view of the small lens unit according to the third embodiment taken along line AA in FIG. [Figure 8] 4 is a cross-sectional view taken along line BB in FIG. 3 of the small lens unit of the third embodiment housed in a holder. [Figure 9] 1. A cross-sectional view of the small lens unit according to the fourth embodiment taken along line AA in FIG. [Figure 10] 4 is a cross-sectional view taken along line BB in FIG. 3 of the small lens unit of the fourth embodiment housed in a holder. [Figure 11] 1. A cross-sectional view of the small lens unit according to the fifth embodiment taken along line AA in FIG. [Figure 12] 5 is a cross-sectional view taken along line BB in FIG. 3 of the small lens unit of the fifth embodiment housed in a holder. [Figure 13] 1 showing a cross-sectional view of a small lens unit according to a sixth embodiment. [Figure 14]10 is a cross-sectional view taken along line BB in FIG. 3 of the small lens unit of the sixth embodiment housed in a holder. [Figure 15] 10 is a cross-sectional view taken along line BB in FIG. 3 of the small lens unit of the seventh embodiment housed in a holder. [Figure 16] FIG. 1 is a perspective view of a small lens unit showing a conventional technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First Embodiment The small lens unit of the first embodiment will be described in detail below. Fig. 1 is a perspective view showing a small lens unit 10A. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1 of the first embodiment. Fig. 3 is a perspective view of a holder 16 housing the small lens unit 10A of Fig. 1. Fig. 4 is a cross-sectional view taken along line BB in Fig. 3. In Figs. 1 and 2, the optical axis direction is indicated by arrow X, the radial direction by arrow Y, the forward direction in the optical axis direction by arrow X1, and the rearward direction in the optical axis direction by arrow X2.

[0010] The small lens unit 10A (hereinafter, the same applies to other embodiments) is suitably used as a small lens unit to be installed in various sensor modules. For example, the small lens unit 10A is installed at the tip of a sensor module (scope) of an endoscope (not shown). Endoscopes include various industrial endoscopes, various medical endoscopes such as vascular endoscopes, brain scopes, and otorhinolaryngological scopes, as well as any endoscopes to be developed in the future.

[0011] The lens unit 10A has a lens 11a, an aperture pattern 12 (aperture means), and a spacer 13a. In addition, a cover member 14 and a sensor cover member 15 are arranged in the lens unit 10A. The cover member 14 is arranged in front of the lens 11a in the optical axis direction. The sensor cover member 15 is arranged behind the spacer 13a in the optical axis direction. The cover member 14, the aperture pattern 12, the lens 11a, the spacer 13a, and the sensor cover member 15 are arranged in series in the optical axis direction. The cover member 14, the aperture pattern 12, the lens 11a, the spacer 13a, and the sensor cover member 15 are accommodated in an accommodation space 17 of the holder 16 as shown in FIG. 3.

[0012] The cover member 14, the aperture pattern 12, the lens 11a, the spacer 13a, and the sensor cover member 15 are integrally formed. Note that the lens unit 10A may have the cover member 14, the aperture pattern 12, the lens 11a (including lenses 11b to 11g), the spacer 13a (including spacers 13b to 13f), and the sensor cover member 15. Alternatively, the lens unit 10A may have the cover member 14, the aperture pattern 12, the lens 11a (including lenses 11b to 11g), the spacer 13a (including spacers 13b to 13f), the sensor cover member 15, and the holder 16.

[0013] Alternatively, the lens unit 10A may have the cover member 14, the aperture pattern 12, the lens 11a (including the lenses 11b to 11g), and the spacer 13a (including the spacers 13b to 13f). Alternatively, the lens unit 10A may have the aperture pattern 12, the lens 11a (including the lenses 11b to 11g), the spacer 13a (including the spacers 13b to 13f), and the sensor cover member 15. Alternatively, the lens unit 10A may have the aperture pattern 12, the lens 11a (including the lenses 11b to 11g), the spacer 13a (including the spacers 13b to 13f), the sensor cover member 15, and the holder 16.

[0014] The cover member 14 is formed of transparent glass (cover glass) or transparent synthetic resin. The cover member 14 has a front end face 18, a rear end face 19, four side faces 20, and four corners 21. The front end face 18 is a flat surface located on the object side (indicated by arrow X1). The rear end face 19 is a flat surface on the image side (indicated by arrow X2) located on the opposite side (the side of the lens 11a) of the front end face 18. The four side faces 20 extend between the front end face 18 and the rear end face 19. The corners 21 are located at the locations where the side faces 20 intersect. The shape of the side surface 20 continuing from the front end surface 18 to the rear end surface 19 is a regular square prism (rectangular prism). The cover member 14 has a regular square (quadrilateral) cross section in the radial direction. The corners where the front end surface 18 intersects with each side surface 20 (circumferential surface) are cut, and the corners where the front end surface 18 intersects with each side surface 20 are chamfered. Note that the corners where the front end surface 18 intersects with each side surface 20 do not have to be chamfered.

[0015] 3 and 4, the cover member 14 is fitted in front of the accommodation space 17 of the holder 16 so as to be located in front of the aperture pattern 12 in the optical axis direction. The four corners 21 abut against the inner peripheral surface 23 of the body portion 22 of the holder 16. The body portion 22 of the holder 16 forms a circumscribing circle of the regular quadrangle cross section of the cover member 14. It is sufficient that at least two of the four corners 21 abut against the inner peripheral surface 23 of the body portion 22 of the holder 16.

[0016] The shape of the side surface 20 may be a polygonal prism other than a quadrangular prism (such as a triangular prism, a pentagonal prism, or a hexagonal prism) or a cylinder. The radial cross-sectional shape of the cover member 14 may be a polygonal prism other than a quadrangle (such as a triangular prism, a pentagonal prism, or a hexagonal prism) or a circle. The cover member 14 (including the cover members 14b and 14c) has, for example, a diameter L1 of 1.1 mm, a maximum radial diameter (diagonal length) L2 of 1.2 mm, and a thickness dimension L3 of 0.3 mm. The diameter L1, maximum radial diameter L2, and thickness dimension L3 of the cover member 14 are appropriately determined depending on the type of sensor module to which the small lens unit 10A is connected, and there are no particular limitations on the diameter L1, maximum radial diameter L2, and thickness dimension L3 of the cover member 14.

[0017] The aperture pattern 12 is formed on the rear end surface 19 of the cover member 14. The aperture pattern 12 is a chrome film of a light-blocking color (e.g., black or gray) that is masked on the rear end surface 19 by photoetching. The aperture pattern 12 has the same cross-sectional shape as the cover member 14. The radial cross-sectional shape of the aperture pattern 12 is, for example, a regular rectangle (quadrangle). The aperture pattern 12 is located behind the cover member 14 in the optical axis direction.

[0018] The squeezed pattern 12 has a circular hole 24 in the center. The squeezed pattern 12 may be a squeezed pattern 12 (chrome film) masked on the front end face 18 and the rear end face 19 by photoetching. The squeezed pattern 12 may also be a squeezed pattern 12 (chrome film) masked on the front end face 18 by photoetching.

[0019] The aperture pattern 12 can be formed by photoetching on the rear end surface 19 of the cover member 14 (or on both the front end surface 18 and the rear end surface 19, or on the front end surface 18). This eliminates the need to interpose an aperture copper plate (aperture means) between the lens 11a and the cover member 14, for example, and can save the aperture copper plate as well as the time and effort required for interposing the aperture copper plate between the lens 11a and the cover member 14.

[0020] The lens 11a is formed of transparent glass or transparent synthetic resin. The lens 11a has a front end face 25, a rear end face 26, four side faces 27, and four corners 28. The front end face 25 is a flat surface located on the object side (the side of the cover member 14). The rear end face 26 is an image-side surface located on the opposite side of the front end face 25 (the side of the spacer 13a). The four side faces 27 extend between the front end face 25 and the rear end face 26. The corners 28 are located at the locations where the side faces 27 intersect. The lens 11a is located behind the aperture pattern 12 in the optical axis direction. The front end face 25 faces the rear end face 19 (aperture pattern 12) of the cover member 14. The front end face 25 is fixed to the rear end face 19 (aperture pattern 12) of the cover member 14 by a transparent adhesive 29a.

[0021] The refractive index difference of the adhesive 29a that bonds the front end surface 25 of the lens 11a and the rear end surface 19 of the cover member 14 is within 0.1 for the transparent lens 11a and the transparent cover member 14. Specifically, the refractive index difference between the adhesive 29a and the cover member 14 is 0.1 or less, and the refractive index difference between the adhesive 29a and the lens 11a is 0.1 or less.

[0022] If the difference in refractive index between the transparent lens 11a and the transparent cover member 14 and the transparent adhesive 29a exceeds 0.1, the adhesive 29a refracts light, and the small lens unit 10A may not be able to form an accurate image. In contrast, by making the difference in refractive index between the transparent lens 11a and the transparent cover member 14 and the adhesive 29a within 0.1, the refraction of the image by the adhesive 29a that bonds the lens 11a and the cover member 14 can be suppressed. Furthermore, reflection at the interfaces between the adhesive 29a and each member can be suppressed, and unnecessary light can be prevented from entering the sensor module (sensor). Also, flare and ghosting can be prevented while the small lens unit 10A reliably forms an accurate image.

[0023] The lens 11a has the same cross-sectional shape as the cover member 14. The cross-sectional shape of the lens 11a in the radial direction is a regular rectangle (quadrilateral). The cross-sectional shape of the lens 11a in the radial direction may be a polygon other than a rectangle (such as a triangle, a pentagonal prism, or a hexagonal prism) or a circle. The lens 11a has, for example, a diameter L1 of 1.1 mm and a maximum radial diameter (diagonal length) L2 of 1.2 mm. The diameter L1 and maximum radial diameter L2 of the lens 11a are appropriately determined depending on the type of sensor module to which the small lens unit 10A is connected, and there are no particular limitations on the diameter L1 and maximum radial diameter L2.

[0024] As shown in Fig. 4, the lens 11a is fitted into the center of the accommodation space 17 of the holder 16 so as to be located in front of the spacer 13a in the optical axis direction. Four corners 28 of the lens 11a abut against the inner peripheral surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 forms a circumscribing circle of the regular quadrangle in cross section of the lens 11a. It is sufficient that at least two of the four corners 28 abut against the inner peripheral surface 23 of the body 22 of the holder 16.

[0025] The lens 11a has a convex lens portion 30 (lens portion), an annular recessed portion 31, and a flange portion 32 with a predetermined area. The convex lens portion 30 is circular and formed in the center of the lens 11a. The convex lens portion 30 is convex backward in the optical axis direction toward the spacer 13a. The convex lens portion 30 is a spherical lens, but may be an aspheric lens. The recessed portion 31 is recessed forward in the optical axis direction from the convex lens portion 30 and the flange portion 32. The recessed portion 31 is located between the convex lens portion 30 and the flange portion 32, extends flatly radially outward from the periphery of the convex lens portion 30, and surrounds the periphery of the convex lens portion 30.

[0026] The flange portion 32 extends radially outward from the outer circumferential edge of the recess 31 and surrounds the outer circumferential edge of the recess 31. The flange portion 32 has an inner side surface 33 and a rear end surface 26. The inner side surface 33 extends flared from the outer circumferential edge of the recess 31 rearward in the optical axis direction. The rear end surface 26 is a flat surface extending radially outward from the tip of the inner side surface 33. The rear end surface 26 is spaced rearward in the optical axis direction from the center of the convex lens portion 30 and is located slightly rearward of the center of the convex lens portion 30 in the optical axis direction.

[0027] The spacer 13a is formed of transparent glass or transparent synthetic resin. The spacer 13a has a front end face 34, a rear end face 35, four side faces 36, and four corners 37. The front end face 34 is a flat surface located on the object side (the side of the lens 11a). The rear end face 35 is a flat surface on the image side located on the opposite side of the front end face 34 (the side of the sensor cover member 15). The four side faces 36 extend between the front end face 34 and the rear end face 35. The corners 37 are located at the places where the side faces 36 intersect. The shape of the side faces 36 is a regular square prism (rectangular prism). The cross-sectional shape of the spacer 13a in the radial direction is a regular square (rectangle). The spacer 13a has the same cross-sectional shape as the cover member 14 and the lens 11a.

[0028] The spacer 13a is disposed behind the lens 11a in the optical axis direction and is interposed between the lens 11a and the sensor cover member 15. The length dimension of the spacer 13a in the optical axis direction is adjusted and used for focusing the lens 11a. As shown in FIG. 4, the spacer 13a is fitted below the accommodation space 17 of the holder 16 so as to be located in front of the sensor cover member 15 in the optical axis direction. The four corners 37 abut against the inner circumferential surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 is a circumscribed circle of the square cross section of the spacer 13a. It is sufficient that at least two of the four corners 37 abut against the inner circumferential surface 23 of the body 22 of the holder 16.

[0029] The spacer 13a has a circular spaced portion 38 and a fixing peripheral portion 39. The spaced portion 38 faces the convex lens portion 30 and the recessed portion 31 of the lens 11a. The fixing peripheral portion 39 has a predetermined area and faces the flange portion 32 of the lens 11a. In the spaced portion 38, the front end face 34 is spaced a predetermined distance rearward in the optical axis direction from the convex lens portion 30 and the recessed portion 31 of the lens 11a. The fixing peripheral portion 39 extends radially outward from the outer periphery of the spaced portion 38 and surrounds the spaced portion 38.

[0030] The front end surface 34 of the fixing peripheral portion 39 is flush with the front end surface 34 of the spaced portion 38 and extends radially outward from the periphery of the spaced portion 38. The front end surface 34 of the fixing peripheral portion 39 abuts against the rear end surface 26 of the flange portion 32. The front end surface 34 is fixed to substantially the entire rear end surface 26 of the flange portion 32 by a transparent adhesive 29b. A space 40 is formed between the convex lens portion 30 and the recessed portion 31 of the lens 11a and the front end surface 34 of the spaced portion 38 of the spacer 13a. Note that the uneven portion 50 as shown in FIG. 5 may be formed on the rear end surface 35 of the spacer 13a, or the recessed portion 53 or the protruding portion as shown in FIG. 9 may be formed.

[0031] The side surface 36 may be a polygonal prism other than a square prism (triangular prism, pentagonal prism, hexagonal prism, etc.) or a cylinder. The radial cross-sectional shape of the spacer 13a may be a polygonal prism other than a square (triangle, pentagon, hexagon, etc.) or a circle. The spacer 13a has, for example, a diameter L1 of 1.1 mm and a maximum radial diameter (diagonal length) L2 of 1.2 mm. The diameter L1 and maximum radial diameter L2 of the spacer 13a are appropriately determined depending on the type of sensor module to which the small lens unit 10A is connected, and there are no particular limitations on the diameter L1 and maximum radial diameter L2.

[0032] The sensor cover member 15 is formed of transparent glass (sensor cover glass) or transparent synthetic resin. The sensor cover member 15 is located behind the spacer 13a in the optical axis direction. The sensor cover member 15 has a front end face 41, a rear end face 42, four side faces 43, and four corners 44. The front end face 41 is a flat surface located on the object side (the side of the spacer 13a). The rear end face 42 is a flat surface on the image side located opposite the front end face 41. The four side faces 43 extend between the front end face 41 and the rear end face 42. The corners 44 are located at the places where the side faces 43 intersect. The shape of the side face of the sensor cover member 15 is a regular square prism (rectangular prism). The cross-sectional shape of the sensor cover member 15 in the radial direction is a regular square (rectangle). The sensor cover member 15 has the same cross-sectional shape as the cover member 14, the lens 11a, and the spacer 13a.

[0033] As shown in Fig. 4, the cover member 15 for the sensor is located behind the holder 16. The front end surface 41 faces the rear end surface 35 of the spacer 13a. The front end surface 41 is fixed to the rear end surface 35 of the spacer 13a with a transparent adhesive 29c. A light receiving element 45 is provided on the rear end surface 42 of the cover member 15 for the sensor.

[0034] The rear end surface 35 of the spacer 13a is fixed to the front end surface 41 of the cover member for sensor 15 by the adhesive 29c, so that the front end surface 41 of the cover member for sensor 15 and the rear end surface 35 of the spacer 13a can be stably fixed. Therefore, the front end surface 41 of the cover member for sensor 15 and the rear end surface 35 of the spacer 13a can be firmly fixed by the adhesive 29c, and even if a predetermined load acts on the spacer 13a or the cover member for sensor 15, damage or breakage of the rear end surface 35 of the spacer 13a and the front end surface 41 of the cover member for sensor 15 and their vicinity can be prevented.

[0035] The refractive index difference of the adhesive 29c that bonds the rear end surface 35 of the spacer 13a and the front end surface 41 of the cover member for the sensor 15 is within 0.1 for the transparent spacer 13a and the transparent cover member for the sensor 15. Specifically, the refractive index difference between the adhesive 29c and the spacer 13a is 0.1 or less, and the refractive index difference between the adhesive 29c and the cover member for the sensor 15 is 0.1 or less.

[0036] If the difference in refractive index between the transparent spacer 13a and the transparent sensor cover member 15 and the transparent adhesive 29c exceeds 0.1, the adhesive 29c refracts light, and the small lens unit 10A may not be able to form an accurate image. In contrast, by making the difference in refractive index between the transparent spacer 13a and the transparent sensor cover member 15 and the adhesive 29c within 0.1, the refraction of the image by the adhesive 29c that bonds the spacer 13a and the sensor cover member 15 can be suppressed. Furthermore, reflection at the interface between the adhesive 29c and each member can be suppressed, and excess light can be prevented from entering the sensor module (sensor). Also, flare and ghosting can be prevented while the small lens unit 10A reliably forms an accurate image.

[0037] The shape of the side surface 43 may be a polygonal prism other than a quadrangular prism (triangular prism, pentagonal prism, hexagonal prism, etc.) or a cylinder. The cross-sectional shape in the radial direction of the sensor cover member 15 may be a polygonal prism other than a quadrangle (triangular, pentagonal, hexagonal, etc.) or a circle. The cover member for the sensor 15 has, for example, a diameter L1 of 1.1 mm and a maximum radial diameter (diagonal length) L2 of 1.2 mm. The diameter L1 and maximum radial diameter L2 of the cover member for the sensor 15 are appropriately determined depending on the type of sensor module to which the small lens unit 10A is connected, and there are no particular limitations on the diameter L1 and maximum radial diameter L2.

[0038] The holder 16 is made of synthetic resin (plastic). The holder 16 has a body 22 and an accommodation space 17. The body 22 is cylindrical and long in the optical axis direction. The accommodation space 17 is surrounded by the body 22. The body 22 has a front end 46 and a rear end 47. The diameter L4 of the body 22 (outer diameter of the holder) is, for example, 1.4 mm. The holder 16 may be made of a metal such as SUS or an alloy. The diameter L4 of the body 22 (outer diameter of the holder) is appropriately determined depending on the type of sensor module to which the small lens unit 10A is connected, and there is no particular limit to the diameter L4 of the body 22. The diameter L4 of the body 22 (outer diameter of the holder) is adjusted in the range of 0.5 mm to 3 mm.

[0039] The radial cross-sectional shape of the accommodation space 17 is circular (a perfect circle). The accommodation space 17 is cylindrical and extends from the front end 46 (forward) of the body 22 toward the rear end 47 (rear). The maximum inner diameter of the accommodation space 17 is adjusted within a range of 0.4 mm to 2 mm. This allows a small lens unit 10A to be accommodated in the accommodation space 17 of the holder 16, resulting in an extremely small holder 16 and lens unit 10A that can be suitably connected to a small sensor module.

[0040] The radial cross-sectional shape (circular) of the body 22 differs from the radial cross-sectional shapes (rectangle) of the cover member 14 and the small lens unit 10A (aperture pattern 12, lens 11a, spacer 13a). As a result, a gap 48 extending in the optical axis direction is formed between the inner peripheral surface 23 of the body 22 and each of the side surfaces 20, 27, 36 (outer peripheral surfaces) of the cover member 14 and the small lens unit 10A.

[0041] The gap 48 (housing space 17) is filled (injected) with adhesive 49 (filler). The adhesive 49 hardens in the gap. When light enters through the gap 48, unnecessary light enters the light receiving element 45. However, by making the adhesive 49 black or gray and filling the gap 48 with the adhesive 49 that blocks light, the light entering through the gap 48 can be blocked. This makes it possible to prevent unnecessary light from entering the light receiving element 45. In addition, the adhesive 49 can fix the cover member 14 and the small lens unit 10A to the housing space 17 of the holder 16. It is not necessary to fill the gap 48 (housing space 17) with adhesive 49.

[0042] When the small lens unit 10A in which the cover member 14 and the sensor cover member 15 are connected is installed at the tip of the sensor module (scope) of an endoscope, light transmitted through the cover member 14 passes through the hole 24 of the aperture pattern 12 and enters the lens 11a. The light then passes from the lens 11a through the spacer 13a and the sensor cover member 15 and enters the light receiving element 45 of the sensor module, where it is displayed as an image and output as an optical signal.

[0043] In the small lens unit 10A, the rear end surface 26 of the flange portion 32 is spaced from the center of the convex lens portion 30 in the rear direction in the optical axis direction. Also, the rear end surface 26 of the flange portion 32 is located slightly rearward in the optical axis direction from the center of the convex lens portion 30. Also, the lens 11a has a recess 31 located between the convex lens portion 30 and the flange portion 32 and recessed forward in the optical axis direction from the convex lens portion 30 and the flange portion 32. As a result, a space 40 is formed between the convex lens portion 30 and the front end surface 34 of the separation portion 38 of the spacer 13a. Therefore, it is not necessary to increase the extension dimension of the flange portion 32 of the lens 11a in the rear direction in the optical axis direction, and the area of ​​the rear end surface 26 of the flange portion 32 can be increased, and the bonding area of ​​the rear end surface 26 of the flange portion 32 to the front end surface 34 of the fixing peripheral portion 39 of the spacer 13a is increased.

[0044] The rear end surface 26 of the flange portion 32 of the lens 11a abuts against the front end surface 34 of the fixing peripheral portion 39 extending radially outward from the periphery of the spaced portion 38 of the spacer 13a. The rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 of the spacer 13a are fixed by an adhesive 29b. Therefore, the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 of the spacer 13a can be stably fixed. The rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 can be firmly fixed by the adhesive 29b. Even if a predetermined load acts on the flange portion 32 of the lens 11a or the spacer 13a, damage or breakage of the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 of the spacer 13a, as well as the vicinity thereof, can be prevented.

[0045] <Second embodiment> Fig. 5 is a cross-sectional view of the small lens unit 10B of the second embodiment taken along line AA in Fig. 1. Fig. 6 is a cross-sectional view of the small lens unit 10B housed in the holder 16 taken along line BB in Fig. 3. The small lens unit 10B of this embodiment is different from the first embodiment in that the lens 11b does not have an annular recess 31, the spaced portion 38 of the spacer 13b is recessed rearward in the optical axis direction from the fixed peripheral portion 39, and a plurality of sawtooth-shaped uneven portions 50 (a plurality of recesses and protrusions) are formed on the rear end surface 35 of the spacer 13b. The other configurations of the small lens unit 10B of this embodiment are the same as those of the small lens unit 10A of the first embodiment, so that the same reference numerals as those of the first embodiment are used, and the description of the lens unit 10A of the first embodiment is used to omit detailed description of the other configurations of the lens unit 10B of this embodiment.

[0046] The small lens unit 10B of this embodiment has a lens 11b, an aperture pattern 12, and a spacer 13b. In addition, a cover member 14 and a cover member for a sensor 15 are arranged in the lens unit 10B. The cover member 14 is arranged in front of the lens 11b in the optical axis direction. The cover member for a sensor 15 is arranged behind the spacer 13b in the optical axis direction. The cover member 14, the aperture pattern 12, the lens 11b, the spacer 13b, and the cover member for a sensor 15 are arranged in series in the optical axis direction and are integrated. The cover member 14, the aperture pattern 12, the lens 11b, and the spacer 13b are accommodated in the accommodation space 17 of the holder 16 as shown in FIG. 6. The cover member 14, the aperture pattern 12, the cover member for a sensor 15, and the holder 16 of the lens unit 10B are the same as those of the lens unit 10A of the first embodiment.

[0047] The lens 11b is formed of transparent glass or transparent synthetic resin. The cross-sectional shape of the lens 11b in the radial direction is a regular rectangle (quadrangle). The cross-sectional shape of the lens 11b is the same as the cross-sectional shapes of the cover member 14, the spacer 13b, and the sensor cover member 15. The lens 11b has a front end face 25, a rear end face 26, four side faces 27, and four corners 28. The front end face 25 is a flat surface located on the object side (the cover member 14 side). The rear end face 26 is an image side surface located on the opposite side of the front end face 25 (the spacer 13b side). The four side faces 27 extend between the front end face 25 and the rear end face 26. The corners 28 are located at the locations where the side faces 27 intersect. The front end face 25 of the lens 11b is fixed to the rear end face 19 (the aperture pattern 12) of the cover member 14 by a transparent adhesive 29a. The difference in refractive index between the transparent lens 11b and the transparent cover member 14 and the adhesive 29a is within 0.1.

[0048] 6, the lens 11b is fitted into the center of the accommodation space 17 of the holder 16 so as to be located in front of the spacer 13b in the optical axis direction. Four corners 28 of the lens 11b abut against the inner circumferential surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 forms a circumscribing circle of the regular quadrangle in cross section of the lens 11b. It is sufficient that at least two of the four corners 28 abut against the inner circumferential surface 23 of the body 22 of the holder 16.

[0049] The lens 11b has a convex lens portion 30 (lens portion) and a flange portion 32 with a predetermined area. The convex lens portion 30 is circular and formed in the center of the lens 11b. The convex lens portion 30 is convex rearward in the optical axis direction toward the spacer 13b. The convex lens portion 30 is a spherical lens, but may be an aspheric lens. The flange portion 32 extends radially outward from the outer peripheral edge of the convex lens portion 30 and surrounds the outer peripheral edge of the convex lens portion 30. The flange portion 32 has a flat rear end surface 26 that extends radially outward from the outer peripheral edge of the convex lens portion 30. The rear end surface 26 is located slightly forward in the optical axis direction from the center of the lens portion 30.

[0050] The spacer 13b is formed of transparent glass or transparent synthetic resin. The spacer 13b has a front end face 34, a rear end face 35, four side faces 36, and four corners 37. The front end face 34 is located on the object side (the side of the lens 11b). The rear end face 35 is an image-side surface located on the opposite side of the front end face 34 (the side of the sensor cover member 15). The four side faces 36 extend between the front end face 34 and the rear end face 35. The corners 37 are located at the locations where the side faces 36 intersect. The shape of the side faces 36 is a regular square prism (rectangular prism). The cross-sectional shape of the spacer 13b in the radial direction is a regular square (rectangle). The spacer 13b has the same cross-sectional shape as the cover member 14, the lens 11b, and the sensor cover member 15.

[0051] The spacer 13b is disposed behind the lens 11b in the optical axis direction and is interposed between the lens 11b and the sensor cover member 15. The length dimension of the spacer 13b in the optical axis direction is adjusted and used for focusing the lens 11b. As shown in FIG. 6, the spacer 13b is fitted into the rear of the accommodation space 17 of the holder 16 so as to be located in front of the sensor cover member 15 in the optical axis direction. The four corners 37 abut against the inner circumferential surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 forms a circumscribing circle of the regular square cross section of the spacer 13b. It is sufficient that at least two of the four corners 37 abut against the inner circumferential surface 23 of the body 22 of the holder 16.

[0052] The spacer 13b has a circular spaced portion 38 and a fixing peripheral portion 39. The spaced portion 38 faces the convex lens portion 30 of the lens 11b. The fixing peripheral portion 39 has a predetermined area and faces the flange portion 32 of the lens 11b. The spaced portion 38 is recessed rearward in the optical axis direction from the fixing peripheral portion 39. The front end face 34 of the spaced portion 38, which extends flat in the radial direction, is spaced rearward in the optical axis direction from the convex lens portion 30 by a predetermined distance. The fixing peripheral portion 39 extends radially outward from the outer periphery of the spaced portion 38 and surrounds the spaced portion 38.

[0053] The fixing peripheral portion 39 has an inner surface 51 and a front end face 34. The inner surface 51 extends straight from the outer circumferential edge of the spaced portion 38 rearward in the optical axis direction. The front end face 34 is a flat surface extending radially outward from the tip of the inner surface 51. The front end face 34 of the fixing peripheral portion 39 is spaced a predetermined distance forward in the optical axis direction from the front end face 34 of the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 is located forward in the optical axis direction from the front end face 34 of the spaced portion 38.

[0054] The front end surface 34 of the fixing peripheral portion 39 abuts against the rear end surface 26 of the flange portion 32. The front end surface 34 is fixed to substantially the entire area of ​​the rear end surface 26 of the flange portion 32 by a transparent adhesive 29b. A space 40 is formed between the convex lens portion 30 and the front end surface 34 of the separating portion 38.

[0055] A plurality of sawtooth-like uneven portions 50 (a plurality of concave and convex portions) arranged in the radial direction are formed on the rear end surface 35 of the spacer 13b. Incidentally, uneven portions other than the sawtooth-like uneven portions may be formed on the rear end surface 35. Also, similar to the first embodiment, the rear end surface 35 of the spacer 13b may be flat. The front end surface 41 of the sensor cover member 15 faces the rear end surface 35 of the spacer 13b. The front end surface 41 of the sensor cover member 15 is fixed to the rear end surface 35 of the spacer 13b by a transparent adhesive 29c. The refractive index difference between the transparent spacer 13b and the adhesive 29c with respect to the transparent sensor cover member 15 is within 0.1.

[0056] The adhesive 29c penetrates into the uneven portion 50 formed on the rear end surface 35 of the spacer 13b, and the anchor effect of the adhesive 29c firmly fixes the front end surface 41 of the cover member for sensor 15 to the rear end surface 35 of the spacer 13b. As a result, even if a predetermined load acts on the spacer 13b or the cover member for sensor 15, damage or breakage of the rear end surface 35 of the spacer 13b, the front end surface 41 of the cover member for sensor 15, and the vicinity thereof can be reliably prevented.

[0057] By accommodating the cover member 14 and the small lens unit 10B, whose cross-sectional shape in the radial direction is a regular square (polygon), in the accommodation space 17 of the holder 16, whose cross-sectional shape in the radial direction is a circle, a gap 48 extending in the optical axis direction is formed between each side surface 20, 27, 36 (outer peripheral surface) of the cover member 14 and the small lens unit 10B and the inner peripheral surface 23 of the body 22 of the holder 16. An adhesive 49 (filler) is filled (injected) in the gap 48 (accommodation space 17). When light enters from the gap 48, unnecessary light enters the light receiving element 45, but by filling the gap 48 with the adhesive 49 that blocks light, the light entering from the gap 48 can be blocked. This makes it possible to prevent the unnecessary light from entering the light receiving element 45. In addition, the adhesive 49 can fix the cover member 14 and the small lens unit 10B to the accommodation space 17 of the holder 16. It is not necessary for the adhesive 49 to be filled in the gap 48 (the accommodation space 17).

[0058] In the small lens unit 10B, the rear end face 26 of the flange portion 32 is spaced forward in the optical axis direction from the center of the convex lens portion 30. Also, the rear end face 26 of the flange portion 32 is located slightly forward in the optical axis direction from the center of the convex lens portion 30. Also, the front end face 34 of the fixing peripheral portion 39 of the spacer 13b is located forward in the optical axis direction of the front end face 34 of the separation portion 38. Also, the separation portion 38 of the spacer 13b is recessed backward in the optical axis direction from the fixing peripheral portion 39. As a result, the extension dimension of the flange portion 32 backward in the optical axis direction does not become longer, and the area of ​​the rear end face 26 of the flange portion 32 becomes larger, and the adhesive area of ​​the rear end face 26 of the flange portion 32 to the front end face 34 of the fixing peripheral portion 39 becomes larger.

[0059] The rear end surface 26 of the flange portion 32, which is located slightly forward in the optical axis direction of the convex lens portion 30, abuts against the front end surface 34 of the fixing peripheral portion 39 of the spacer 13b. In addition, the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 of the spacer 13b are fixed to each other by an adhesive 29b. Therefore, the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 can be stably fixed to each other, and the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 can be firmly fixed to each other by the adhesive 29b. In addition, even if a predetermined load is applied to the flange portion 32, damage or breakage of the rear end surface 26 of the flange portion 32 and its vicinity can be prevented.

[0060] <Third embodiment> Fig. 7 is a cross-sectional view of the small lens unit 10C of the third embodiment taken along line AA in Fig. 1. Fig. 8 is a cross-sectional view of the small lens unit 10C housed in the holder 16 taken along line BB in Fig. 3. The small lens unit 10C of this embodiment is different from the first embodiment in that the lens 11b does not have an annular recess 31 and the front end face 34 of the spaced portion 38 of the spacer 13c forms a concave lens 52 recessed backward in the optical axis direction from the front end face 34 of the fixed peripheral portion 39. The other configurations of the small lens unit 10C of this embodiment are the same as those of the small lens unit 10A of the first embodiment, so that the same reference numerals as those of the first embodiment are used and the description of the lens unit 10A of the first embodiment is used to omit detailed description of the other configurations of the lens unit 10C of this embodiment.

[0061] The small lens unit 10C of this embodiment has a lens 11b, an aperture pattern 12, and a spacer 13c. In addition, a cover member 14 and a cover member for a sensor 15 are arranged in the lens unit 10C. The cover member 14 is arranged in front of the lens 11b in the optical axis direction. The cover member for a sensor 15 is arranged behind the spacer 13c in the optical axis direction. The cover member 14, the aperture pattern 12, the lens 11b, the spacer 13c, and the cover member for a sensor 15 are arranged in series in the optical axis direction and are integrated. The cover member 14, the aperture pattern 12, the lens 11b, and the spacer 13c are accommodated in the accommodation space 17 of the holder 16 as shown in FIG. 8. The cover member 14, the aperture pattern 12, the cover member for a sensor 15, and the holder 16 of the lens unit 10C are the same as those of the lens unit 10A of the first embodiment. The lens 11b is the same as the lens unit 10B of the second embodiment.

[0062] The spacer 13c is formed of transparent glass or transparent synthetic resin. The spacer 13c has a front end face 34, a rear end face 35, four side faces 36, and four corners 37. The front end face 34 is located on the object side (the side of the lens 11b). The rear end face 35 is a flat surface on the image side located on the opposite side of the front end face 34 (the side of the sensor cover member 15). The four side faces 36 extend between the front end face 34 and the rear end face 35. The corners 37 are located at the places where the side faces 36 intersect. The shape of the side faces 36 is a regular square prism (rectangular prism). The cross-sectional shape of the spacer 13c in the radial direction is a regular square (rectangle). The spacer 13c has the same cross-sectional shape as the cover member 14, the lens 11b, and the sensor cover member 15.

[0063] The spacer 13c is disposed behind the lens 11b in the optical axis direction and is interposed between the lens 11b and the sensor cover member 15. The length dimension of the spacer 13c in the optical axis direction is adjusted and used for focusing the lens 11b. As shown in FIG. 8, the spacer 13c is fitted to the rear of the accommodation space 17 of the holder 16 so as to be located in front of the sensor cover member 15 in the optical axis direction. The four corners 37 abut against the inner circumferential surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 is a circumscribed circle of the square cross section of the spacer 13c. It is sufficient that at least two of the four corners 37 abut against the inner circumferential surface 23 of the body 22 of the holder 16.

[0064] The spacer 13c has a circular spaced portion 38 and a fixed peripheral portion 39. The spaced portion 38 faces the convex lens portion 30 of the lens 11b. The fixed peripheral portion 39 has a predetermined area and faces the flange portion 32 of the lens 11b. The front end surface 34 of the spaced portion 38 is recessed rearward in the optical axis direction from the front end surface 34 of the fixed peripheral portion 39 toward the center of the spaced portion 38, forming a concave lens 52 facing the convex lens portion 30. The front end surface 34 (concave lens 52) of the spaced portion 38 is spaced rearward in the optical axis direction from the convex lens portion 30 by a predetermined distance.

[0065] The fixing peripheral portion 39 extends radially outward from the outer circumferential edge of the spaced portion 38 and surrounds the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 extends flatly radially outward from the outer circumferential edge of the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 is spaced a predetermined distance forward in the optical axis direction from the front end face 34 of the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 is located forward in the optical axis direction from the front end face 34 of the spaced portion 38.

[0066] The front end surface 34 of the fixing peripheral portion 39 abuts against the rear end surface 26 of the flange portion 32. The front end surface 34 of the fixing peripheral portion 39 is fixed to substantially the entire area of ​​the rear end surface 26 of the flange portion 32 by a transparent adhesive 29b. A space 40 is formed between the lens portion 30 and the front end surface 34 of the separating portion 38.

[0067] The front end surface 41 of the cover member for the sensor 15 faces the rear end surface 35 of the spacer 13c. The front end surface 41 of the cover member for the sensor 15 is fixed to the rear end surface 35 of the spacer 13c by a transparent adhesive 29c. The refractive index difference between the transparent spacer 13c and the adhesive 29c for the transparent cover member for the sensor 15 is within 0.1. Note that a plurality of uneven portions 50 similar to those of the spacer 13b may be formed on the rear end surface 35 of the spacer 13c, or recesses or protrusions may be formed on the rear end surface 35 of the spacer 13c.

[0068] By accommodating the cover member 14 and the small lens unit 10C, whose cross-sectional shape in the radial direction is a regular square (polygon), in the accommodation space 17 of the holder 16, whose cross-sectional shape in the radial direction is a circle, a gap 48 extending in the optical axis direction is formed between each side surface 20, 27, 36 (outer peripheral surface) of the cover member 14 and the small lens unit 10C and the inner peripheral surface 23 of the body 22 of the holder 16. An adhesive 49 (filler) is filled (injected) in the gap 48 (accommodation space 17). When light enters from the gap 48, unnecessary light enters the light receiving element 45, but by filling the gap 48 with the adhesive 49 that blocks light, the light entering from the gap 48 can be blocked. This makes it possible to prevent the unnecessary light from entering the light receiving element 45. In addition, the adhesive 49 can fix the cover member 14 and the small lens unit 10C to the accommodation space 17 of the holder 16. It is not necessary for the adhesive 49 to be filled in the gap 48 (the accommodation space 17).

[0069] In the small lens unit 10C, the rear end surface 26 of the flange portion 32 is spaced forward in the optical axis direction from the center of the convex lens portion 30. Also, the rear end surface 26 of the flange portion 32 is located slightly forward in the optical axis direction from the center of the convex lens portion 30. Also, the front end surface 34 of the fixing peripheral portion 39 of the spacer 13c is located forward in the optical axis direction of the front end surface 34 of the separation portion 38. Also, the front end surface 34 of the separation portion 38 of the spacer 13c forms a concave lens 52 that is recessed backward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39. As a result, the extension dimension of the flange portion 32 backward in the optical axis direction is not increased, and the area of ​​the rear end surface 26 of the flange portion 32 is increased, and the adhesive area of ​​the rear end surface 35 of the flange portion 32 to the front end surface 34 of the fixing peripheral portion 39 of the spacer 13c is increased.

[0070] The rear end surface 26 of the flange portion 32, which is located slightly forward in the optical axis direction of the convex lens portion 30, abuts against the front end surface 34 of the fixing peripheral portion 39 of the spacer 13c. In addition, the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 of the spacer 13c are fixed by an adhesive 29b. Therefore, the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 can be stably fixed, and the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 can be firmly fixed by the adhesive 29b. In addition, even if a load is applied to the spacer 13c or the flange portion 32, damage or breakage of the front end surface 34 of the fixing peripheral portion 39, the rear end surface 26 of the flange portion 32, and the vicinity thereof can be prevented.

[0071] The front end surface 34 of the spaced portion 38 forms a concave lens 52 that is concave rearward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39 toward the center of the spaced portion 38. Therefore, the field curvature, which is one of the aberrations generated in the convex lens portion 30 arranged in front of the spacer 13c, is efficiently corrected, and high optical characteristics are obtained even with a small number of lenses. In addition, since the front end surface 34 of the spaced portion 38 forms the concave lens 52, the resolution of the image captured using the small lens unit 10C is increased, and the image quality is improved.

[0072] <Fourth embodiment> Fig. 9 is a cross-sectional view of the small lens unit 10D of the fourth embodiment taken along line AA in Fig. 1. Fig. 10 is a cross-sectional view of the small lens unit 10D accommodated in the holder 16 taken along line BB in Fig. 3. The small lens unit 10D of this embodiment is different from the first embodiment in that the rear end surface 26 of the flange portion 32 is spaced forward in the optical axis direction from the center of the convex lens portion 30, and the rear end surface 26 is located slightly forward in the optical axis direction from the center of the convex lens portion 30, the front end surface 34 of the spaced portion 38 of the spacer 13d forms a concave lens 52 recessed backward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39, a recess 53 is formed in the rear end surface 35 of the spacer 13d, and the sensor cover member 15 is accommodated in the holder 16. The other configurations of the small lens unit 10D of this embodiment are the same as those of the small lens unit 10A of the first embodiment, so the same symbols as in the first embodiment are used, and by incorporating the description of the lens unit 10A of the first embodiment, detailed descriptions of the other configurations of the lens unit 10D of this embodiment will be omitted.

[0073] The small lens unit 10D of this embodiment has a lens 11c, an aperture pattern 12, and a spacer 13d. In addition, a cover member 14 and a cover member for a sensor 15 are arranged in the lens unit 10D. The cover member 14 is arranged in front of the lens 11c in the optical axis direction. The cover member for a sensor 15 is arranged behind the spacer 13d in the optical axis direction. The cover member 14, the aperture pattern 12, the lens 11c, the spacer 13d, and the cover member for a sensor 15 are arranged in series in the optical axis direction and are integrated. The cover member 14, the aperture pattern 12, the lens 11c, the spacer 13d, and the cover member for a sensor 15 are accommodated in the accommodation space 17 of the holder 16 as shown in FIG. 10. The cover member 14, the aperture pattern 12, and the cover member for a sensor 15 of the lens unit 10D are the same as those of the lens unit 10A of the first embodiment.

[0074] The lens 11c is formed of transparent glass or transparent synthetic resin. The cross-sectional shape of the lens 11c in the radial direction is a regular rectangle (rectangle). The cross-sectional shape of the lens 11c is the same as the cross-sectional shapes of the cover member 14, the spacer 13d, and the sensor cover member 15. The lens 11c has a front end face 25, a rear end face 26, four side faces 27, and four corners 28. The front end face 25 is a flat surface located on the object side (the cover member 14 side). The rear end face 26 is located on the opposite side of the front end face 25 (the spacer 13d side). The four side faces 27 extend between the front end face 25 and the rear end face 26. The corners 28 are located at the locations where the side faces 27 intersect. The lens 11c is located behind the aperture pattern 12 in the optical axis direction. The front end face 25 of the lens 11c faces the rear end face 19 (aperture pattern 12) of the cover member 14. The front end surface 25 is fixed to the rear end surface 19 of the cover member 14 by a transparent adhesive 29a. The refractive index difference between the transparent cover member 14 and the adhesive 29a with respect to the transparent lens 11c is within 0.1.

[0075] 10, the lens 11c is fitted into the center of the accommodation space 17 of the holder 16 so as to be located in front of the spacer 13d in the optical axis direction. Four corners 28 of the lens 11c abut against the inner peripheral surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 forms a circumscribing circle of the regular quadrangle in cross section of the lens 11c. It is sufficient that at least two of the four corners 28 abut against the inner peripheral surface 23 of the body 22 of the holder 16.

[0076] Lens 11c has a convex lens portion 30 (lens portion), an annular recessed portion 31, and a flange portion 32 with a predetermined area. Convex lens portion 30 is circular and formed in the center of lens 11c. Convex lens portion 30 is convex rearward in the optical axis direction toward spacer 13d. Convex lens portion 30 is a spherical lens, but may be an aspherical lens. Recessed portion 31 is recessed forward in the optical axis direction from convex lens portion 30 and flange portion 32. Recessed portion 31 is located between convex lens portion 30 and flange portion 32. Recessed portion 31 extends flatly from the periphery of convex lens portion 30 radially outward and surrounds the periphery of convex lens portion 30.

[0077] The flange portion 32 extends radially outward from the outer circumferential edge of the recess 31 and surrounds the outer circumferential edge of the recess 31. The flange portion 32 has an inner surface 33 and a flat rear end surface 26. The inner surface 33 extends flared from the outer circumferential edge of the recess 31 rearward in the optical axis direction. The rear end surface 26 is a flat surface extending radially outward from the tip of the inner surface 33. The rear end surface 26 of the flange portion 32 is spaced forward in the optical axis direction from the center of the convex lens portion 30. The rear end surface 26 is located slightly forward in the optical axis direction from the center of the convex lens portion 30.

[0078] The spacer 13d is formed of transparent glass or transparent synthetic resin. The spacer 13d has a front end face 34, a rear end face 35, four side faces 36, and four corners 37. The front end face 34 is located on the object side (the side of the lens 11c). The rear end face 35 is an image-side surface located on the opposite side of the front end face 34 (the side of the sensor cover member 15). The four side faces 36 extend between the front end face 34 and the rear end face 35. The corners 37 are located at the locations where the side faces 36 intersect. The shape of the side faces 36 is a regular square prism (rectangular prism). The cross-sectional shape of the spacer 13d in the radial direction is a regular square (rectangle). The spacer 13d has the same cross-sectional shape as the cover member 14, the lens 11c, and the sensor cover member 15.

[0079] The spacer 13d is disposed behind the lens 11c in the optical axis direction and is interposed between the lens 11c and the sensor cover member 15. The length dimension of the spacer 13d in the optical axis direction is adjusted and used for focusing the lens 11c. As shown in FIG. 10, the spacer 13d is fitted into the middle of the accommodation space 17 of the holder 16 so as to be located in front of the sensor cover member 15 in the optical axis direction. The four corners 37 abut against the inner circumferential surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 is a circumscribed circle of the spacer 13d and the sensor cover member 15 in cross section. It is sufficient that at least two corners 37 of the four corners 37 abut against the inner circumferential surface 23 of the body 22 of the holder 16.

[0080] The spacer 13d has a circular spaced portion 38 and a fixed peripheral portion 39. The spaced portion 38 faces the recessed portion 31 and the convex lens portion 30 of the lens 11c. The fixed peripheral portion 39 has a predetermined area and faces the flange portion 32 of the lens 11c. The front end surface 34 of the spaced portion 38 is recessed rearward in the optical axis direction from the front end surface 34 of the fixed peripheral portion 39 toward the center of the spaced portion 38, forming a concave lens 52 facing the recessed portion 31 and the convex lens portion 30 of the lens 11c. The front end surface 34 (concave lens 52) of the spaced portion 38 is spaced rearward in the optical axis direction from the recessed portion 31 and the convex lens portion 30 of the lens 11c by a predetermined distance.

[0081] The fixing peripheral portion 39 extends radially outward from the outer circumferential edge of the spaced portion 38 (concave lens 52) and surrounds the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 extends flatly radially outward from the outer circumferential edge of the spaced portion 38 (concave lens 52). The front end face 34 of the fixing peripheral portion 39 is spaced a predetermined distance forward in the optical axis direction from the front end face 34 (concave lens 52) of the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 is located forward in the optical axis direction of the front end face 34 of the spaced portion 38.

[0082] The front end face 34 of the fixing peripheral portion 39 abuts against the rear end face 26 of the flange portion 32. The front end face 34 is fixed to substantially the entire area of ​​the rear end face 26 of the flange portion 32 by a transparent adhesive 29b. A space 40 is formed between the convex lens portion 30 and the front end face 34 (concave lens 52) of the separating portion 38. A single recess 53 recessed forward in the optical axis direction is formed in the rear end face 35 of the spacer 13d.

[0083] The front end surface 41 of the sensor cover member 15 faces the rear end surface 35 of the spacer 13d. The front end surface 41 of the sensor cover member 15 is fixed to the rear end surface 35 of the spacer 13d by a transparent adhesive 29c. The refractive index difference of the adhesive 29c with respect to the transparent lens 11c and the transparent sensor cover member 15 is within 0.1. The adhesive 29c enters the recess 53 formed in the rear end surface 35 of the spacer 13d, and the front end surface 41 of the sensor cover member 15 and the rear end surface 35 of the spacer 13d can be firmly fixed by the anchor effect of the adhesive 29c. Therefore, even if a predetermined load is applied to the spacer 13d or the sensor cover member 15, damage or breakage of the rear end surface 35 of the spacer 13d and the front end surface 41 of the sensor cover member 15 and their vicinity can be reliably prevented. Note that a plurality of recesses 53 may be formed on the rear end surface 35 of the spacer 13d, a protrusion may be formed on the rear end surface 35 of the spacer 13d, or a plurality of uneven portions may be formed on the rear end surface 35 of the spacer 13d. Moreover, the rear end surface 35 of the spacer 13d may be flat like the rear end surface 35 of the spacer 13a of the first embodiment.

[0084] By accommodating the cover member 14 and the small lens unit 10D, whose cross-sectional shape in the radial direction is a regular square (polygon), in the accommodation space 17 of the holder 16, whose cross-sectional shape in the radial direction is a circle, a gap 48 extending in the optical axis direction is formed between each side surface 20, 27, 36 (outer peripheral surface) of the cover member 14 and the small lens unit 10D and the inner peripheral surface 23 of the body 22 of the holder 16. An adhesive 49 (filler) is filled (injected) in the gap 48 (accommodation space). When light enters from the gap 48, unnecessary light enters the light receiving element 45, but by filling the gap 48 with the adhesive 49 that blocks light, the light entering from the gap 48 can be blocked. This makes it possible to prevent the unnecessary light from entering the light receiving element 45. In addition, the adhesive 49 can fix the cover member 14 and the small lens unit 10D to the accommodation space 17 of the holder 16. It is not necessary for the adhesive 49 to be filled in the gap 48 (the accommodation space 17).

[0085] In the small lens unit 10D, the rear end surface 26 of the flange portion 32 is spaced forward in the optical axis direction from the center of the convex lens portion 30. Also, the rear end surface 26 of the flange portion 32 is located slightly forward in the optical axis direction from the center of the convex lens portion 30. Also, the front end surface 34 of the fixing peripheral portion 39 of the spacer 13d is located forward in the optical axis direction of the front end surface 34 of the separation portion 38. Also, the front end surface 34 of the separation portion 38 of the spacer 13d forms a concave lens 52 that is recessed backward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39. As a result, the extension dimension of the flange portion 32 backward in the optical axis direction is not increased, and the area of ​​the rear end surface 26 of the flange portion 32 is increased, and the adhesive area of ​​the rear end surface 26 of the flange portion 32 to the front end surface 34 of the fixing peripheral portion 39 is increased.

[0086] The rear end surface 26 of the flange portion 32, which is located slightly forward in the optical axis direction of the convex lens portion 30, abuts against the front end surface 34 of the fixing peripheral portion 39 of the spacer 13d. In addition, the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 are fixed by an adhesive 29b. Therefore, the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 can be stably fixed, and the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 can be firmly fixed by the adhesive 29b. In addition, even if a predetermined load acts on the flange portion 32 or the fixing peripheral portion 39 of the spacer 13d, damage or breakage of the rear end surface 26 of the flange portion 32, the front end surface 34 of the spacer 13d, and the vicinity thereof can be prevented.

[0087] The front end surface 34 of the spaced portion 38 of the spacer 13d forms a concave lens 52 that is concave rearward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39 toward the center of the spaced portion 38. Therefore, the field curvature, which is one of the aberrations generated in the convex lens portion 30 arranged in front of the spacer 13d, is efficiently corrected, and high optical characteristics are obtained even with a small number of lenses. In addition, since the front end surface 34 of the spaced portion 38 of the spacer 13d forms the concave lens 52, the resolution of the image captured using the small lens unit 10D is increased, and the image quality is improved.

[0088] <Fifth embodiment> Fig. 11 is a cross-sectional view of the lens unit 10E of the fifth embodiment taken along the line AA in Fig. 1. Fig. 12 is a cross-sectional view of the lens unit 10E accommodated in the holder 16 taken along the line BB in Fig. 3. The lens unit 10E of the present embodiment differs from the first embodiment in that a cover member 14 is not provided, two first and second lenses 11d, 11e are aligned in the optical axis direction, the first lens 11d forms a concave lens 64 that is concave toward the front in the optical axis direction, the front end face 25 of the second lens 11e forms a concave lens portion 65 that is concave toward the front in the optical axis direction, the front end face 34 of the separation portion 38 of the spacer 13e forms a lens 56 having a concave portion 54 that is concave toward the rear in the optical axis direction from the front end face 34 of the fixing peripheral portion 39 and a convex portion 55 that is convex toward the front in the optical axis direction from the inner peripheral edge of the concave portion 54 toward the center of the separation portion 38, a concave portion 53 is formed in the rear end face 35 of the spacer 13e, and a light shielding plate 70 is provided between the first lens 11d and the second lens 11e, and an aperture plate 12 (aperture means) is provided between the second lens 11e and the spacer 13e. The other configurations of the small lens unit 10E of this embodiment are the same as those of the small lens unit 10A of the first embodiment, so the same symbols as in the first embodiment are used, and by quoting the description of the lens unit 10A of the first embodiment, detailed descriptions of the other configurations of the lens unit 10E of this embodiment will be omitted.

[0089] The lens unit 10E of this embodiment has a first lens 11d, a second lens 11e, an aperture plate 12, and a spacer 13e. The second lens 11e is located behind the first lens 11d (light shielding plate 70) in the optical axis direction. The spacer 13e is located behind the second lens 11e (aperture plate 12) in the optical axis direction. In addition, a sensor cover member 15 is disposed behind the spacer 13e in the optical axis direction. Although the lens unit 10E has two lenses, the first lens 11d and the second lens 11e, there is no particular limit to the number of lenses, and the lens unit 10E may have three or more first lenses (convex lenses or concave lenses) to n-th lenses (convex lenses or concave lenses) arranged in the optical axis direction.

[0090] The first lens 11d, the light shielding plate 70, the second lens 11e, the aperture plate 12, the spacer 13e, and the sensor cover member 15 are arranged in series in the optical axis direction and are integrated together. The first lens 11d, the light shielding plate 70, the second lens 11e, the aperture plate 12, the spacer 13e, and the sensor cover member 15 are accommodated in the accommodation space 17 of the holder 16, as shown in FIG.

[0091] The first lens 11d is formed of transparent glass (cover glass) or transparent synthetic resin. The first lens 11d has a front end face 25, a rear end face 26, four side faces 27, and four corners 28. The front end face 25 is located on the object side. The rear end face 26 is an image-side surface located on the opposite side of the front end face 25 (the side of the second lens 11e). The four side faces 27 extend between the front end face 25 and the rear end face 26. The corners 28 are located at the locations where the side faces 27 intersect.

[0092] The shape of the side surface 27 is a regular square prism (rectangular prism). The cross-sectional shape in the radial direction of the first lens 11d is a regular square (rectangle). The front end surface 25 of the first lens 11d is recessed forward in the optical axis direction at its center, and the rear end surface 26 of the first lens 11d is recessed forward in the optical axis direction at its center. This causes the first lens 11d to form a concave lens 64 whose center is recessed forward in the optical axis direction. The flange portion 32 of the first lens 11d surrounds the outer peripheral edge of the concave lens 64.

[0093] As shown in FIG. 12, the first lens 11d is fitted in the front of the storage space 17 of the holder 16. The four corners 28 abut against the inner peripheral surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 is a circumscribing circle of the regular square cross section of the first lens 11d. It is sufficient that at least two of the four corners 28 abut against the inner peripheral surface 23 of the body 22 of the holder 16. The shape of the side surface 27 may be a polygonal prism other than a quadrangular prism (triangular prism, pentagonal prism, hexagonal prism, etc.) or a cylinder. The radial cross-sectional shape of the first lens 11d may be a polygonal prism other than a quadrangle (triangular prism, pentagonal prism, hexagon, etc.) or a circle.

[0094] The light blocking plate 70 is disposed between the first lens 11d and the second lens 11e on the rear end surface 26 of the first lens 11d. The light blocking plate 70 is located rearward in the optical axis direction of the first lens 11d. A circular hole 24 is formed in the center of the light blocking plate 70. The diaphragm plate 12 is disposed between the second lens 11e and the spacer 13e on the rear end surface 26 of the second lens 11e. The diaphragm plate 12 is located rearward in the optical axis direction of the second lens 11e. A circular hole 24 (diaphragm hole) is formed in the center of the diaphragm plate 12.

[0095] The second lens 11e is formed of transparent glass or transparent synthetic resin. The second lens 11e has a front end face 25, a rear end face 26, four side faces 27, and four corners 28. The front end face 25 is located on the object side (the side of the first lens 11d). The rear end face 26 is an image-side surface located on the opposite side of the front end face 25 (the side of the spacer 13e). The four side faces 27 extend between the front end face 25 and the rear end face 26. The corners 28 are located at the locations where the side faces 27 intersect. The second lens 11e is located behind the light shielding plate 70 (the first lens 11d) in the optical axis direction. The radial cross-sectional shape of the second lens 11e is a regular rectangle (rectangle). The second lens 11e has the same cross-sectional shape as the first lens 11d.

[0096] The front end surface 25 of the second lens 11e forms a circular concave lens portion 65 whose center is concave toward the front in the optical axis direction. The rear end surface 26 of the second lens 11e forms a circular convex lens 30 whose center is convex toward the rear in the optical axis direction. The concave lens portion 65 and the convex lens portion 30 are spherical lenses, but may be aspheric lenses. The concave portion 31 is concave toward the front in the optical axis direction from the convex lens portion 30 and the flange portion 32. The concave portion 31 is located between the convex lens portion 30 and the flange portion 32. The concave portion 31 extends flatly from the periphery of the convex lens portion 30 radially outward and surrounds the periphery of the convex lens portion 30.

[0097] The flange portion 32 of the second lens 11e surrounds the outer peripheral edge of the concave lens portion 65 and also surrounds the outer peripheral edge of the recess 31. The flange portion 32 of the second lens 11e has an inner surface 33 and a rear end face 26. The inner surface 33 extends from the outer peripheral edge of the recess 31 in a diverging manner rearward in the optical axis direction. The rear end face 26 is a flat surface extending radially outward from the tip of the inner surface 33. The rear end face 26 of the flange portion 32 of the second lens 11e is spaced rearward in the optical axis direction from the center of the convex lens portion 30. The rear end face 26 is located slightly rearward in the optical axis direction from the center of the convex lens portion 30.

[0098] The front end surface 25 of the flange portion 32 of the second lens 11e faces the rear end surface 26 (light shielding plate 70) of the flange portion 32 of the first lens 11d. The front end surface 25 of the flange portion 32 of the second lens 11e is fixed to the rear end surface 26 of the flange portion 32 of the first lens 11d by a transparent adhesive 29a. The refractive index difference of the adhesive 29a between the first and second lenses 11d, 11e is within 0.1.

[0099] 12, the second lens 11e is fitted into the middle of the accommodation space 17 of the holder 16 so as to be located in front of the spacer 13e in the optical axis direction. The four corners 28 abut against the inner circumferential surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 forms a circumscribing circle of the regular quadrangle in cross section of the second lens 11e. It is sufficient that at least two of the four corners 28 abut against the inner circumferential surface 23 of the body 22 of the holder 16.

[0100] The spacer 13e is formed of transparent glass or transparent synthetic resin. The spacer 13e has a front end face 34, a rear end face 35, four side faces 36, and four corners 37. The front end face 34 is located on the object side (the side of the second lens 11e). The rear end face 35 is an image-side surface located on the opposite side of the front end face 34 (the side of the sensor cover member 15). The four side faces 36 extend between the front end face 34 and the rear end face 35. The corners 37 are located at the locations where the side faces 36 intersect. The shape of the side faces 36 is a regular square prism (rectangular prism). The cross-sectional shape of the spacer 13e in the radial direction is a regular square (rectangle). The spacer 13e has the same cross-sectional shape as the first lens 11d, the second lens 11e, and the sensor cover member 15.

[0101] The spacer 13e is disposed behind the second lens 11e in the optical axis direction and is interposed between the second lens 11e and the sensor cover member 15. The length dimension of the spacer 13e in the optical axis direction is adjusted and used for focusing the focal point defined by the first lens 11d (concave lens 64) and the second lens 11e (convex lens portion 30 and concave lens portion 65). As shown in FIG. 12, the spacer 13e is fitted into the middle of the accommodation space 17 of the holder 16 so as to be located in front of the sensor cover member 15 in the optical axis direction. The four corners 37 abut against the inner circumferential surface 23 of the body portion 22 of the holder 16. The body portion 22 of the holder 16 is a circumscribed circle of the square cross section of the spacer 13e. It is sufficient that at least two corners 37 of the four corners 37 abut against the inner circumferential surface 23 of the body portion 22 of the holder 16.

[0102] The spacer 13e has a circular spaced portion 38 and a fixing peripheral portion 39. The spaced portion 38 faces the recessed portion 31 and the convex lens portion 30 of the second lens 11e. The fixing peripheral portion 39 has a predetermined area and faces the flange portion 32 of the second lens 11e. The front end surface 34 of the spaced portion 38 forms a lens 56 having a recessed portion 54 and a convex portion 55. The recessed portion 54 is circular and recessed rearward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39. The convex portion 55 is circular and convex forward in the optical axis direction from the inner peripheral edge of the recessed portion 54 toward the center of the spaced portion 38. The front end surface 34 of the spaced portion 38 (lens 56 having the recessed portion 54 and the convex portion 55) is spaced rearward in the optical axis direction by a predetermined distance from the recessed portion 31 and the convex lens portion 30 of the second lens 11e.

[0103] The fixing peripheral portion 39 extends radially outward from the outer circumferential edge of the spaced portion 38 and surrounds the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 extends flatly radially outward from the outer circumferential edge of the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 is spaced a predetermined distance forward in the optical axis direction from the front end face 34 of the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 is located forward in the optical axis direction of the front end face 34 of the spaced portion 38.

[0104] The front end face 34 of the fixing peripheral portion 39 abuts against the rear end face 26 of the flange portion 32 of the second lens 11e. The front end face 34 of the fixing peripheral portion 39 is fixed to substantially the entire rear end face 26 of the flange portion 32 of the second lens 11e by a transparent adhesive 29b. A space 40 is formed between the convex lens portion 30 of the second lens 11e and the front end face 34 of the separation portion 38.

[0105] The front end surface 41 of the cover member for the sensor 15 faces the rear end surface 35 of the spacer 13e. The front end surface 41 of the cover member for the sensor 15 is fixed to the rear end surface 35 of the spacer 13e by a transparent adhesive 29c. The refractive index difference between the transparent spacer 13e and the adhesive 29c for the transparent cover member for the sensor 15 is within 0.1. A convex portion may be formed on the rear end surface 35 of the spacer 13e, or a plurality of uneven portions 50 may be formed on the rear end surface 35 of the spacer 13e. Also, the rear end surface 35 of the spacer 13e may not have a concave portion 53 formed thereon, and the rear end surface 35 may be flat.

[0106] The adhesive 29c penetrates into the recess 53 formed in the rear end surface 35 of the spacer 13e, and the anchor effect of the adhesive 29c firmly fixes the front end surface 41 of the cover member for sensor 15 to the rear end surface 35 of the spacer 13e. Therefore, even if a predetermined load acts on the spacer 13e or the cover member for sensor 15, damage or breakage of the rear end surface 35 of the spacer 13e, the front end surface 41 of the cover member for sensor 15 and the vicinity thereof can be reliably prevented.

[0107] By accommodating the small lens unit 10E (first lens 11d, second lens 11e, spacer 13e) and the sensor cover member 15, each of which has a square (polygon) cross-sectional shape in the radial direction, in the accommodation space 17 of the holder 16, which has a circular cross-sectional shape in the radial direction, a gap 48 extending in the optical axis direction is formed between each side surface 27, 36, 43 (outer peripheral surface) of the small lens unit 10E and the sensor cover member 15 and the inner peripheral surface 23 of the body 22 of the holder 16. An adhesive 49 (filler) is filled (injected) in the gap 48 (accommodation space 17). When light enters from the gap 48, unnecessary light enters the light receiving element 45, but by filling the gap 48 with the adhesive 49 that blocks light, the light entering from the gap 48 can be blocked. This makes it possible to prevent unnecessary light from entering the light receiving element 45. The small lens unit 10E and the sensor cover member 15 can be fixed to the accommodation space 17 of the holder 16 by the adhesive 49. It is not necessary for the adhesive 49 to be filled in the gap 48 (accommodation space 17).

[0108] In the small lens unit 10E, the rear end surface 26 of the flange portion 32 of the second lens 11e is spaced rearward in the optical axis direction from the center of the convex lens portion 30. The rear end surface 26 of the flange portion 32 is located slightly rearward in the optical axis direction from the center of the convex lens portion 30. The second lens 11e also has a recess 31 located between the convex lens portion 30 and the flange portion 32 and recessed forward in the optical axis direction from the convex lens portion 30 and the flange portion 32. The front end surface 34 of the separation portion 38 of the spacer 13e forms a lens 56 having a recessed portion 54 recessed rearward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39 and a convex portion 55 that is convex forward in the optical axis direction from the inner peripheral edge of the recessed portion 54 toward the center of the separation portion 38. As a result, the extension dimension of the flange portion 32 of the second lens 11e rearward in the optical axis direction does not become longer, but the area of ​​the rear end face 26 of the flange portion 32 is increased, and the adhesive area of ​​the rear end face 26 of the flange portion 32 of the second lens 11e relative to the front end face 34 of the fixing peripheral portion 39 of the spacer 13e is increased.

[0109] The rear end surface 26 of the flange portion 32, located slightly behind the convex lens portion 30 of the second lens 11e in the optical axis direction, abuts against the front end surface 34 of the fixing peripheral portion 39, located forward in the optical axis direction of the front end surface 34 of the separation portion 38 of the spacer 13e. The rear end surface 26 of the flange portion 32 of the second lens 11e and the front end surface 34 of the fixing peripheral portion 39 of the spacer 13e are fixed by an adhesive 29b. Therefore, the rear end surface 26 of the flange portion 32 of the second lens 11e and the front end surface 34 of the fixing peripheral portion 39 can be stably fixed, and the rear end surface 26 of the flange portion 32 of the second lens 11e and the front end surface 34 of the fixing peripheral portion 39 can be firmly fixed by the adhesive 29b. Furthermore, even if a certain load acts on the flange portion 32 or the fixing peripheral portion 39 of the second lens 11e, damage or breakage of the rear end face 26 of the flange portion 32 of the second lens 11e and the vicinity thereof, including the front end face 34 of the fixing peripheral portion 39, can be prevented.

[0110] The front end surface 34 of the spaced portion 38 of the spacer 13e forms a lens 56 having a recessed portion 54 recessed backward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39, and a convex portion 55 that is convex forward in the optical axis direction from the inner peripheral edge of the recessed portion 54 toward the center of the spaced portion 38. Therefore, the field curvature, which is one of the aberrations generated in the convex lens portion 30 arranged in front of the spacer 13e, is efficiently corrected, and high optical characteristics are obtained even with a small number of lenses. In addition, since the front end surface 34 of the spaced portion 38 of the spacer 13e forms the lens 56, the resolution of the image captured using the small lens unit E is increased, and the image quality is improved.

[0111] Sixth Embodiment Fig. 13 is a cross-sectional view of the small lens unit 10F of the sixth embodiment taken along line AA in Fig. 1. Fig. 14 is a cross-sectional view of the small lens unit 10F accommodated in the holder 16 taken along line BB in Fig. 3. The small lens unit 10F of this embodiment differs from the first embodiment in that a cover member 14 is not provided, two first and second lenses 11f, 11g are aligned in the optical axis direction, the first lens 11f forms a concave lens 64 that is concave toward the front in the optical axis direction, the front end face 25 and the rear end face 26 of the second lens 11g form a concave lens portion 61 that is concave toward the front in the optical axis direction, and the front end face 34 of the separation portion 38 of the spacer 13f forms a lens 60 having a first concave portion 57 that is concave toward the rear in the optical axis direction from the front end face 34 of the fixing peripheral portion 39, a convex portion 58 that is convex toward the front in the optical axis direction from the inner peripheral edge of the first concave portion 57, and a second concave portion 59 that is concave toward the center of the separation portion 38 toward the rear in the optical axis direction. The other configurations of the small lens unit 10F of this embodiment are the same as those of the small lens unit 10A of the first embodiment, so the same symbols as in the first embodiment are used, and by incorporating the description of the lens unit 10A of the first embodiment, detailed descriptions of the other configurations of the lens unit 10F of this embodiment will be omitted.

[0112] The lens unit 10F of this embodiment has a first lens 11f, a second lens 11g, an aperture plate 12, and a spacer 13f. The second lens 11g is located behind the first lens 11f (aperture plate 12) in the optical axis direction. The spacer 13f is located behind the second lens 11g in the optical axis direction. The sensor cover member 15 is disposed behind the spacer 13f in the optical axis direction. Although the lens unit 10F has two lenses, the first lens 11f and the second lens 11g, there is no particular limit to the number of lenses, and the lens unit 10F may have three or more first lenses (convex lenses or concave lenses) to n-th lenses (convex lenses or concave lenses) arranged in the optical axis direction.

[0113] The first lens 11f, the aperture plate 12, the second lens 11g, the spacer 13f, and the sensor cover member 15 are arranged in series in the optical axis direction and are integrated together. The first lens 11f, the aperture plate 12, the second lens 11g, the spacer 13f, and the sensor cover member 15 are accommodated in the accommodation space 17 of the holder 16, as shown in FIG.

[0114] The first lens 11f is formed of transparent glass (cover glass) or transparent synthetic resin. The first lens 11f has a front end face 25, a rear end face 26, four side faces 27, and four corners 28. The front end face 25 is located on the object side. The rear end face 26 is an image-side surface located on the opposite side of the front end face 25 (the side of the second lens 11g). The four side faces 27 extend between the front end face 25 and the rear end face 26. The corners 28 are located at the locations where the side faces 27 intersect.

[0115] The shape of the side surface 27 is a regular square prism (rectangular prism). The cross-sectional shape in the radial direction of the first lens 11f is a regular square (rectangle). The front end surface 25 of the first lens 11f has a center that is recessed forward in the optical axis direction, and the rear end surface 26 of the first lens 11f has a center that is recessed forward in the optical axis direction. As a result, the first lens 11f forms a concave lens 64 whose center is recessed forward in the optical axis direction. The flange portion 32 of the first lens 11f surrounds the outer peripheral edge of the concave lens 64.

[0116] As shown in FIG. 14, the first lens 11f is fitted in the front of the accommodation space 17 of the holder 16. The four corners 28 abut against the inner peripheral surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 is a circumscribing circle of the regular square cross section of the first lens 11f. At least two of the four corners 28 may abut against the inner peripheral surface 23 of the body 22 of the holder 16. The shape of the side surface 27 may be a polygonal prism other than a quadrangular prism (triangular prism, pentagonal prism, hexagonal prism, etc.) or a cylinder, and the cross-sectional shape of the first lens 11f in the radial direction may be a polygonal prism other than a quadrangle (triangle, pentagon, hexagon, etc.) or a circle. The aperture plate 12 is formed between the first lens 11f and the second lens 11g on the rear end surface 26 of the first lens 11f. A circular hole 24 (aperture hole) is formed in the center of the aperture plate 12.

[0117] The second lens 11g is formed of transparent glass or transparent synthetic resin. The second lens 11g has a front end face 25, a rear end face 26, four side faces 27, and four corners 28. The front end face 25 is located on the object side (the side of the first lens 11f). The rear end face 26 is an image-side surface located on the opposite side of the front end face 25 (the side of the spacer 13f). The four side faces 27 extend between the front end face 25 and the rear end face 26. The corners 28 are located at the locations where the side faces 27 intersect. The second lens 11g is located behind the diaphragm plate 12 (the first lens 11f) in the optical axis direction. The radial cross-sectional shape of the second lens 11g is a regular rectangle (rectangle). The second lens 11g has the same cross-sectional shape as the first lens 11f.

[0118] The center of the front end face 25 of the second lens 11g is recessed forward in the optical axis direction. The center of the rear end face 26 of the second lens 11g is recessed forward in the optical axis direction. This forms a circular concave lens portion 61 in which the centers of the front end face 25 and the rear end face 26 are recessed forward in the optical axis direction. The concave lens portion 61 is a spherical lens, but may be an aspheric lens. The recess 31 is recessed forward in the optical axis direction from the convex lens portion 30 and the flange portion 32. The recess 31 is located between the concave lens portion 61 and the flange portion 32. The recess 31 extends flat from the periphery of the concave lens portion 61 radially outward and surrounds the periphery of the concave lens portion 61.

[0119] The flange portion 32 of the second lens 11g surrounds the outer peripheral edge of the recess 31. The flange portion 32 of the second lens 11g has an inner surface 33 and a rear end surface 26. The inner surface 33 extends from the outer peripheral edge of the recess 31 rearward in the optical axis direction in a diverging manner. The rear end surface 26 is a flat surface extending radially outward from the tip of the inner surface 33. The rear end surface 26 of the flange portion 32 of the second lens 11g is spaced rearward in the optical axis direction from the center of the concave lens portion 61. The rear end surface 26 is located slightly rearward in the optical axis direction from the center of the concave lens portion 61.

[0120] The front end surface 25 of the flange portion 32 of the second lens 11g faces the rear end surface 26 (aperture plate 12) of the flange portion 32 of the first lens 11f. The front end surface 25 of the flange portion 32 of the second lens 11g is fixed to the rear end surface 26 of the flange portion 32 of the first lens 11f by a transparent adhesive 29a. The refractive index difference of the adhesive 29a between the first and second lenses 11g and 11f is within 0.1.

[0121] 14, the second lens 11g is fitted into the middle of the accommodation space 17 of the holder 16 so as to be located in front of the spacer 13f in the optical axis direction. The four corners 28 abut against the inner circumferential surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 forms a circumscribing circle of the regular quadrangle in cross section of the second lens 11g. It is sufficient that at least two of the four corners 28 abut against the inner circumferential surface 23 of the body 22 of the holder 16.

[0122] The spacer 13f is formed of transparent glass or transparent synthetic resin. The spacer 13f has a front end face 34, a rear end face 35, four side faces 36, and four corners 37. The front end face 34 is located on the object side (the side of the second lens 11g). The rear end face 35 has an image-side concave-convex portion 50 located on the opposite side of the front end face 34 (the side of the sensor cover member 15). The four side faces 36 extend between the front end face 34 and the rear end face 35. The corners 37 are located at the locations where the side faces 36 intersect. The shape of the side faces 36 is a regular square prism (rectangular prism). The cross-sectional shape of the spacer 13f in the radial direction is a regular square (rectangle). The spacer 13f has the same cross-sectional shape as the first lens 11f, the second lens 11g, and the sensor cover member 15.

[0123] The spacer 13f is disposed behind the second lens 11g in the optical axis direction and is interposed between the second lens 11g and the sensor cover member 15. The length dimension of the spacer 13f in the optical axis direction is adjusted and used for focusing the first lens 11f (concave lens 64) and the second lens 11g (concave lens portion 61). As shown in FIG. 14, the spacer 13f is fitted into the rear of the accommodation space 17 of the holder 16 so as to be located in front of the sensor cover member 15 in the optical axis direction. The four corners 37 abut against the inner circumferential surface 23 of the body 22 of the holder 16. The body 22 of the holder 16 is a circumscribed circle of the square cross section of the spacer 13f. It is sufficient that at least two corners 37 of the four corners 37 abut against the inner circumferential surface 23 of the body 22 of the holder 16.

[0124] The spacer 13f has a circular spaced portion 38 and a fixing peripheral portion 39. The spaced portion 38 faces the recessed portion 31 and the concave lens portion 61 of the second lens 11g. The fixing peripheral portion 39 has a predetermined area and faces the flange portion 32 of the second lens 11g. The front end surface 34 of the spaced portion 38 forms a lens 60 having a first recessed portion 57, a convex portion 58, and a second recessed portion 59. The first recessed portion 57 is recessed backward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39. The convex portion 58 is convex from the inner peripheral edge of the first recessed portion 57 forward in the optical axis direction. The second recessed portion 59 is recessed backward in the optical axis direction from the inner peripheral edge of the convex portion 58 toward the center of the spaced portion 38. The front end face 34 of the spaced portion 38 (lens 60 having a first recessed portion 57, a convex portion 58 and a second recessed portion 59) is spaced a predetermined distance rearward in the optical axis direction from the recessed portion 31 and the concave lens portion 61 of the second lens 11g.

[0125] The fixing peripheral portion 39 extends radially outward from the outer circumferential edge of the spaced portion 38 and surrounds the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 extends flatly radially outward from the outer circumferential edge of the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 is spaced a predetermined distance forward in the optical axis direction from the front end face 34 of the spaced portion 38. The front end face 34 of the fixing peripheral portion 39 is located forward in the optical axis direction of the front end face 34 of the spaced portion 38.

[0126] The front end face 34 of the fixing peripheral portion 39 abuts against the rear end face 26 of the flange portion 32 of the second lens 11g. The front end face 34 of the fixing peripheral portion 39 is fixed to substantially the entire rear end face 26 of the flange portion 32 of the second lens 11g by a transparent adhesive 29b. A space 40 is formed between the concave lens portion 61 of the second lens 11g and the front end face 34 of the separation portion 38 of the spacer 13f.

[0127] The front end surface 41 of the cover member for the sensor 15 faces the rear end surface 35 of the spacer 13f. The front end surface 41 of the cover member for the sensor 15 is fixed to the rear end surface 35 of the spacer 13f by a transparent adhesive 29c. The refractive index difference between the transparent spacer 13f and the adhesive 29c for the transparent cover member for the sensor 15 is within 0.1. Note that a convex portion or a concave portion 53 may be formed on the rear end surface 35 of the spacer 13f, and the rear end surface 35 of the spacer 13f may not be formed with a plurality of concave and convex portions 50, and may be flat.

[0128] The adhesive 29c penetrates into the multiple uneven portions 50 formed on the rear end surface 35 of the spacer 13f, and the anchor effect of the adhesive 29c firmly fixes the front end surface 41 of the cover member for sensor 15 to the rear end surface 35 of the spacer 13f. Therefore, even if a predetermined load acts on the spacer 13f or the cover member for sensor 15, damage or breakage of the rear end surface 35 of the spacer 13f, the front end surface 41 of the cover member for sensor 15 and the vicinity thereof can be reliably prevented.

[0129] By accommodating the small lens unit 10F (first lens 11f, second lens 11g, spacer 13f) and the sensor cover member 15, each of which has a square (polygon) cross-sectional shape in the radial direction, in the accommodation space 17 of the holder 16, which has a circular cross-sectional shape in the radial direction, a gap 48 extending in the optical axis direction is formed between each side surface 27, 36, 43 (outer peripheral surface) of the small lens unit 10F and the sensor cover member 15 and the inner peripheral surface 23 of the body 22 of the holder 16. An adhesive 49 (filler) is filled (injected) in the gap 48 (accommodation space 17). When light enters from the gap 48, unnecessary light enters the light receiving element 45, but by filling the gap 48 with the adhesive 49 that blocks light, the light entering from the gap 48 can be blocked. This makes it possible to prevent unnecessary light from entering the light receiving element 45. The small lens unit 10F and the sensor cover member 15 can be fixed to the accommodation space 17 of the holder 16 by the adhesive 49. It is not necessary for the adhesive 49 to be filled in the gap 48 (accommodation space 17).

[0130] The rear end surface 26 of the flange portion 32 of the second lens 11g is spaced from the center of the concave lens portion 61 rearward in the optical axis direction. The rear end surface 26 of the flange portion 32 is located slightly rearward in the optical axis direction from the center of the concave lens portion 61. The second lens 11g is located between the concave lens portion 61 and the flange portion 32 and has a recess 31 recessed forward in the optical axis direction from the concave lens portion 61 and the flange portion 32. The front end surface 34 of the separation portion 38 of the spacer 13f forms a lens 60 having a first recessed portion 57 recessed rearward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39, a convex portion 58 that is convex forward in the optical axis direction from the inner peripheral edge of the first recessed portion 57, and a second recessed portion 59 recessed rearward in the optical axis direction from the inner peripheral edge of the convex portion 58 toward the center of the separation portion 38. As a result, the extension dimension of the flange portion 32 of the second lens 11g rearward in the optical axis direction does not become longer, but the area of ​​the rear end face 26 of the flange portion 32 is increased, and the adhesive area of ​​the rear end face 26 of the flange portion 32 of the second lens 11g relative to the front end face 34 of the fixing peripheral portion 39 is increased.

[0131] The rear end surface 26 of the flange portion 32, which is located slightly behind the concave lens portion 61 of the second lens 11g in the optical axis direction, abuts against the front end surface 34 of the fixing peripheral portion 39 of the spacer 13f. The rear end surface 26 of the flange portion 32 of the second lens 11g and the front end surface 34 of the fixing peripheral portion 39 are fixed by an adhesive 29b. Therefore, the rear end surface 26 of the flange portion 32 of the second lens 11g and the front end surface 34 of the fixing peripheral portion 39 can be stably fixed, and the rear end surface 26 of the flange portion 32 of the second lens 11g and the front end surface 34 of the fixing peripheral portion 39 can be firmly fixed by the adhesive 29b. In addition, even if a predetermined load acts on the flange portion 32 and the fixing peripheral portion 39 of the second lens 11g, damage or breakage of the rear end surface 26 of the flange portion 32 of the second lens 11g, including the front end surface 34 of the fixing peripheral portion 39, can be prevented.

[0132] The front end surface 34 of the spacer 13f has a lens 60 including a first recessed portion 57 recessed rearward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39, a convex portion 58 protruding forward in the optical axis direction from the inner peripheral edge of the first recessed portion 57, and a second recessed portion 59 recessed rearward in the optical axis direction from the inner peripheral edge of the convex portion 58 toward the center of the spacer 38. Therefore, the curvature of field, which is one of the aberrations generated in the convex lens portion 30 arranged in front of the spacer 13f, is efficiently corrected, and high optical characteristics are obtained even with a small number of lenses. In addition, the front end surface 34 of the spacer 38 forms the lens 60, and the resolution of the image captured using the small lens unit 10F is increased, resulting in good image quality.

[0133] Seventh embodiment Fig. 15 is a cross-sectional view of the small lens unit 10G of the seventh embodiment housed in the holder 66, taken along the line BB in Fig. 3. The small lens unit 10G of this embodiment is different from the first embodiment in that the cover member 14 is not arranged, the aperture pattern 12 (aperture means) or the aperture plate 12 (aperture means) is not present, the annular recess 31 is not formed in the lens 11b, the front end face 34 of the spacer 13c forms a concave lens 52 recessed backward in the optical axis direction from the front end face 34 of the fixing peripheral portion 39, and the covering portion 68 of the holder 66 is located on the front end face 25 of the lens 11b. Since the other configurations of the small lens unit 10G of this embodiment are the same as those of the small lens unit 10A of the first embodiment, the same reference numerals as those of the first embodiment are used, and the detailed description of the other configurations of the lens unit 10G of this embodiment is omitted by using the description of the lens unit 10A of the first embodiment.

[0134] The small lens unit 10G of this embodiment has a lens 11b and a spacer 13c. The spacer 13c is disposed behind the lens 11b in the optical axis direction. The sensor cover member 15 is disposed behind the spacer 13c in the optical axis direction. The lens 11b, the spacer 13c, and the sensor cover member 15 are arranged in series in the optical axis direction and are integrated. The lens 11b and the spacer 13c are accommodated in the accommodation space 17 of the holder 66 as shown in FIG. 15. The lens 11b, the spacer 13c, and the sensor cover member 15 of the lens unit 10G of this embodiment are the same as those of the lens unit 10C of the third embodiment.

[0135] The holder 66 is made of synthetic resin (plastic). The holder 66 has a body 67, a covering portion 68, and a storage space 17. The body 67 is cylindrical and extends in the optical axis direction. The covering portion 68 extends radially inward from the front end 46 of the body 67. The storage space 17 is surrounded by the body 67 and the covering portion 68. The body 67 has a front end 46 and a rear end 47. The diameter L4 of the body 67 (outer diameter of the holder (see FIG. 3)) is, for example, 1.4 mm. The holder 66 may be made of a metal such as SUS or an alloy. The cross-sectional shape of the storage space 17 in the radial direction is a circle (a perfect circle). The storage space 17 is formed in a cylindrical shape extending from the front end 46 (forward) of the body 67 toward the rear end 47 (rear). The maximum inner diameter of the storage space 17 is adjusted in the range of 0.4 mm to 2 mm.

[0136] The lens 11b and the spacer 13c are fitted into the housing space 17. The four corners 28 of the square prism of the lens 11b and the four corners 37 of the square prism of the spacer 13c abut against the inner peripheral surface 23 of the body 67. The body 67 is a circumscribing circle of the square cross section of the lens 11b and the spacer 13c. It is sufficient that at least two of the four corners 28, 37 of the square prism of the lens 11b and the spacer 13c abut against the inner peripheral surface 23 of the body 67 of the holder 66. The covering portion 68 is located on the front end surface 25 of the lens 11b and covers the front end surface 25. A circular hole 69 is formed in the center of the covering portion 68. The front end surface 25 of the lens 11b is exposed from the hole 69.

[0137] The radial cross-sectional shape (circle) of the body 67 is different from the radial cross-sectional shape (rectangle) of the small lens unit 10G (lens 11b, spacer 13c). Therefore, by accommodating the small lens unit 10G having a cross-sectional shape (rectangle) different from the cross-sectional shape (circle) of the accommodation space 17 in the accommodation space 17, a gap 48 extending in the optical axis direction is formed between the inner peripheral surface 23 of the body 67 and each side surface 27, 36 (outer peripheral surface) of the lens unit 10G.

[0138] An adhesive 49 (filler) is filled (injected) into the gap 48 (housing space 17) between each side surface 27, 36 of the small lens unit 10G and the inner peripheral surface 23 of the body 67. The adhesive 49 hardens in the gap. The small lens unit 10G can be fixed to the housing space 17 by the adhesive 49. Note that the adhesive 49 does not have to be filled into the gap 48.

[0139] The rear end surface 26 of the flange portion 32 of the lens 11b is spaced forward in the optical axis direction from the center of the convex lens portion 30. The rear end surface 26 of the flange portion 32 is located slightly forward in the optical axis direction from the center of the convex lens portion 30. The front end surface 34 of the fixing peripheral portion 39 of the spacer 13c is located forward in the optical axis direction of the front end surface 34 of the separation portion 38. The front end surface 34 of the separation portion 38 of the spacer 13c forms a concave lens 52 that is recessed backward in the optical axis direction from the front end surface 34 of the fixing peripheral portion 39. This increases the area of ​​the rear end surface 26 of the flange portion 32 and increases the adhesive area of ​​the rear end surface 35 of the flange portion 32 to the front end surface 34 of the fixing peripheral portion 39 without increasing the extension dimension of the flange portion 32 backward in the optical axis direction.

[0140] The rear end surface 26 of the flange portion 32 of the lens 11b, which is located slightly forward of the convex lens portion 30 in the optical axis direction, abuts against the front end surface 34 of the fixing peripheral portion 39 of the spacer 13c. The rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 are fixed by an adhesive 29b. Therefore, the rear end surface 26 of the flange portion 32 of the lens 11b and the front end surface 34 of the fixing peripheral portion 39 can be stably fixed, and the rear end surface 26 of the flange portion 32 and the front end surface 34 of the fixing peripheral portion 39 can be firmly fixed by the adhesive 29b. In addition, even if a load is applied to the spacer 13c or the flange portion 32 of the lens 11b, damage or breakage of the front end surface 34 of the fixing peripheral portion 39 and the vicinity thereof, including the rear end surface 26 of the flange portion 32, can be prevented.

[0141] The front end surface 34 of the spaced portion 38 of the spacer 13c forms a concave lens 52 that is concave from the front end surface 34 of the fixed peripheral portion 39 toward the center of the spaced portion 38 toward the rear in the optical axis direction. Therefore, the field curvature, which is one of the aberrations generated in the convex lens portion 30 arranged in front of the spacer 13c, is efficiently corrected, and high optical characteristics can be obtained even with a small number of lenses. In addition, since the front end surface 34 of the spaced portion 38 forms the concave lens 52, the resolution of the image taken using the small lens unit 10G is increased, and the image quality is improved. The covering portion 68 covers the front end surface 25 of the lens 11b, and a circular hole 69 is formed in the center of the covering portion 68, and the covering portion 68 forms an aperture means. Therefore, the aperture pattern 12 can be omitted.

[0142] In the small lens units 10A to 10G of the first to seventh embodiments, the radial length of the rear end face 26 of the flange portion 32 of the lenses 11a to 11g fixed to the front end face 34 of the fixing peripheral portion 39 of the spacers 13a to 13f is in the range of 0.15 to 0.4 mm. Therefore, in the small lens units 10A to 10G, the rear end face 26 of the flange portion 32 and the front end face 34 of the fixing peripheral portion 39 of the spacers 13a to 13f are fixed to each other within the radial length range of 0.15 to 0.4 mm.

[0143] If the radial length of the rear end face 26 of the flange portion 32 of the lenses 11a to 11g is less than 0.15 mm, the area of ​​the rear end face 26 of the flange portion 32 cannot be increased, and the rear end face 26 of the flange portion 32 and the front end face 34 of the fixing peripheral portion 39 of the spacers 13a to 13f cannot be stably fixed to each other. In addition, the rear end face 26 of the flange portion 32 and the front end face 34 of the fixing peripheral portion 39 cannot be firmly fixed to each other by the adhesive 29. If the radial length of the rear end face 26 of the flange portion 32 of the lenses 11a to 11g exceeds 0.4 mm, the lens units 10A to 10G cannot be made as small as required.

[0144] In the small lens units 10A to 10G, the radial length of the rear end face 26 of the flange portion 32 fixed to the front end face 34 of the fixing peripheral portion 39 of the spacers 13a to 13f is in the range of 0.15 to 0.4 mm. Therefore, even though the lens units 10A to 10G are small, the area of ​​the rear end face 26 of the flange portion 32 is large, and the rear end face 26 of the flange portion 32 and the front end face 34 of the fixing peripheral portion 39 of the spacers 13a to 13f can be stably fixed. In addition, the rear end face 26 of the flange portion 32 and the front end face 34 of the fixing peripheral portion 39 can be firmly fixed by the adhesive 29b. As a result, even if a predetermined load acts on the flange portions 32 of the lenses 11a to 11g or the fixing peripheral portions 39 of the spacers 13a to 13f, damage or breakage of the rear end face 26 of the flange portion 32 and the front end face 34 of the fixing peripheral portion 39 and their vicinity can be prevented.

[0145] The compact lens units 10A-10G can be easily manufactured into a regular quadrilateral (polygonal) compact lens unit 10A-10G including the cover member 14 and the sensor cover member 15 by cutting the integrated cover member 14, the aperture pattern 12, the lenses 11a-11g, the spacers 13a-13f, and the sensor cover member 15. This reduces the difficulty of processing without adopting a complex structure. In addition, the lens units 10A-10G can be mass-produced mechanically and efficiently, and the polygonal lens units 10A-10G without any precision deviation can be manufactured inexpensively.

[0146] In the small lens units 10A-10G, at least two corners of the cover member 14 whose cross section is formed into a regular quadrangle (polygon), at least two corners of the small lens units 10A-10G whose cross section is formed into a regular quadrangle (polygon), and at least two corners of the sensor cover member 15 whose cross section is formed into a regular quadrangle (polygon) abut against the inner circumferential surface 23 of the accommodation space 17 of the holder 16. Therefore, the cover member 14, the small lens units 10A-10G, and the sensor cover member 15 are prevented from shifting in the accommodation space 17, and the cover member 14, the small lens units 10A-10G, and the sensor cover member 15 can be fixed to the accommodation space 17.

[0147] It should be noted that lens unit 10A of the first embodiment, lens unit 10B of the second embodiment, lens unit 10C of the third embodiment, lens unit 10D of the fourth embodiment, and lens unit 10G of the seventh embodiment may each have two or more lenses. [Explanation of symbols]

[0148] 10A~10G Small lens unit 11a~11g Lenses 12 Squeeze pattern (squeeze method) 13a~13f Spacer 14 Cover member 15 Sensor cover material 16 Holder 17 Storage Space 18 Front end surface 19 Rear end surface 20 Side 21 corners 22 Torso 23 Inner peripheral surface 24 holes 25 Front end surface 26 Rear end surface 27 Side 28 corners 29 Adhesives (fillers) 30 Convex lens part 31 Recess 32 Flange section 33 Inner surface 34 Front end surface 35 Rear end surface 36 Side 37 angle 38 Separation part 39 Fixation edge 40 Space 41 Front end surface 42 Rear end surface 43 Side 44 angle 45 Photodetector 46 Front end 47 Rear end 48 Gap 49 Adhesive 50 Uneven part 51 Inner surface 52 Concave Lens 53 Recess 54 Concave part 55 Convex part 56 Lens 57 1st concave part 58 Convex part 59 Second concave part 60 Lenses 61 Concave lens part 62 Convex lens part 64 Concave Lens 65 Concave lens part 66 Holder 67 Torso 68 Covering part 69 holes 70 Shading plate L1 diameter L2 Maximum diameter in the radial direction (length of the diagonal) L3 thickness dimension L4 diameter (outer diameter of holder)

Claims

1. A lens, A lens portion formed in the center; a flange portion extending radially outward from a periphery of the lens portion, the flange portion having a rear end surface at a rear side; a lens having A transparent spacer is disposed behind the lens in the optical axis direction and used for focusing the lens portion, a front end surface facing the rear of the lens; a separation portion facing the lens portion and separated from the lens portion rearward in the optical axis direction; a fixed peripheral portion extending radially outward from a peripheral edge of the spaced portion; a spacer having an adhesive disposed between the rear end surface of the flange portion and the fixing peripheral portion, the adhesive fixing the lens and the spacer; a transparent sensor cover member disposed rearward of the spacer along the optical axis; a third adhesive that bonds the spacer and the sensor cover member; a holder having an accommodation space for accommodating the lens and the spacer, the accommodation space having a circular radial cross-sectional shape; a filler filled between the lens and the spacer accommodated in the accommodation space and an inner peripheral surface of the holder; having a refractive index difference of the third adhesive with respect to the spacer and the sensor cover member is within 0.1; The maximum inner diameter of the storage space is 0.4 mm to 2 mm; Lens unit.

2. the rear end surface of the flange portion is located rearward in the optical axis direction from the center of the lens portion, the front end surface of the fixing peripheral portion extends radially outward from the periphery of the spaced portion in flush with the front end surface of the spaced portion; A space is formed between the lens portion and the spaced portion, the rear end surface of the flange portion and the front end surface of the fixing peripheral portion are fixed to each other by the adhesive while being in contact with each other; The lens unit according to claim 1 .

3. the rear end surface of the flange portion is located forward in the optical axis direction from the center of the lens portion, the front end surface of the fixing peripheral portion is located forward of the front end surface of the separation portion in the optical axis direction, the spaced portion is recessed rearward in the optical axis direction from the fixed peripheral portion, a space is formed between the lens portion and the front end surface of the spaced portion; the rear end surface of the flange portion and the front end surface of the fixing peripheral portion are fixed to each other by the adhesive while being in contact with each other; The lens unit according to claim 1 .

4. The lens has a recess located between the lens portion and the flange portion, extending radially outward from a periphery of the lens portion, and recessed forward in the optical axis direction from the lens portion and the flange portion. The lens unit according to any one of claims 1 to 3.

5. The lens portion is either a convex lens portion that is convex toward the rear in the optical axis direction, or a concave lens portion that is concave toward the front in the optical axis direction. The lens unit according to any one of claims 1 to 4.

6. the front end surface of the spaced apart portion forms a concave lens that is concave rearward in the optical axis direction from the front end surface of the fixing peripheral portion toward the center of the spaced apart portion, The lens unit according to any one of claims 1 to 5.

7. the front end surface of the spaced portion forms a lens having a recessed portion recessed rearward in the optical axis direction from the front end surface of the fixing peripheral portion, and a convex portion convex forward in the optical axis direction from an inner peripheral edge of the recessed portion toward a center of the spaced portion. The lens unit according to any one of claims 1 to 5.

8. a first recessed portion recessed rearward in the optical axis direction from the front end surface of the fixed peripheral portion, a convex portion protruding forward in the optical axis direction from an inner peripheral edge of the first recessed portion, and a second recessed portion recessed rearward in the optical axis direction from the inner peripheral edge of the convex portion toward the center of the separation portion, The lens unit according to any one of claims 1 to 5.

9. The radial length of the rear end surface of the flange portion fixed to the fixing peripheral portion is 0.15 to 0.4 mm. The lens unit according to any one of claims 1 to 8.

10. a transparent cover member disposed in front of the lens in the optical axis direction; a second adhesive that bonds the lens and the cover member; The lens unit according to any one of claims 1 to 9, further comprising:

11. A refractive index difference of the second adhesive with respect to the lens and the cover member is within 0.

1. The lens unit according to claim 10.

12. The spacer has a rear end surface formed with a recess, a protrusion, or an uneven portion. The lens unit according to any one of claims 1 to 11.

13. the lens and the spacer have a polygonal radial cross-sectional shape; At least two corners of the lens and the spacer abut against the inner circumferential surface of the holder. The lens unit according to any one of claims 1 to 12.

14. The lens and the spacer are installed in a sensor module of a medical endoscope or a sensor module of an industrial endoscope. The lens unit according to any one of claims 1 to 13.

15. The filler blocks light from entering between the inner circumferential surface of the holder. The lens unit according to any one of claims 1 to 14.

Images