JP4679906B2 - Lens fixing structure - Google Patents

Description

  The present invention relates to a lens fixing structure for fixing a lens to a lens barrel.

  Conventionally, many structures for fixing a lens to a lens barrel have been proposed.

  For example, after multiple lenses are inserted into the lens barrel and the optical axis of the lens is adjusted, a filler is injected between the peripheral surface of the lens and the inner surface of the lens barrel to cure the filler. A structure for fixing the lens to the lens barrel has been proposed (see, for example, Patent Document 1).

  In addition, a structure is known in which a lens is dropped into a lens holder, a lens support member is covered on the upper surface, and the lens holder and the lens support member are welded by heating with a caulking jig, and the lens is sandwiched and fixed from above and below. (See, for example, cited document 2).

Furthermore, the lens support tube formed inside the lens barrel is fitted into the lens with the flange formed, and the end of the lens support tube is heat caulked inward to fix the lens. A structure has been proposed (see, for example, Patent Document 3).
Japanese Patent Application Laid-Open No. 7-11937 JP 2001-511176 A JP 2002-189160 A

  However, in the lens fixing structure disclosed in Patent Document 1, since it is necessary to fix the lens with a filler such as an adhesive, the adhesive before curing flows out to the lens and cures on the lens surface or occurs at the time of curing. There is a problem that the lens surface may be clouded by outgas, which may deteriorate the optical characteristics and reduce the product quality.

  Moreover, in the lens fixing structure shown in Patent Document 2, the lens is fixed by welding the lens support member and the lens holder, and it is necessary to perform welding from a direction parallel to the axial direction of the lens holder. There is a problem that it is necessary to provide a corresponding number of welding locations in the lens barrel in accordance with an increase in the number of lenses installed, which leads to an increase in the size of the lens barrel. Further, when a plurality of lenses having substantially the same lens diameter are used, there is a problem that it is difficult to provide a welding portion and the lens cannot be easily fixed.

  Further, in the lens fixing structure shown in the cited document 3, in order to position the lens on the lens barrel, there are methods of making a screw on the lens barrel and pressing the lens, or pressing the lens into the lens barrel. Although commonly used, there is a problem in that if a lens barrel is screwed, the manufacturing time becomes long and costs increase, and when the lens is press-fitted into the lens barrel, the inner diameter of the lens barrel Therefore, it is necessary to increase the accuracy of the lens and the outer diameter of the lens, so that a high technique is required for molding, and the yield of the product is reduced.

  The present invention has been made in view of the above problems, and has a lens fixing structure that can reduce the burden on the lens fixing work, prevent the lens barrel from becoming large, and reduce the cost. The issue is to provide.

In order to solve the above-described problems, an invention according to claim 1 is directed to a lens, a lens barrel that accommodates the lens, and an inner wall of the lens barrel that is deformed after the lens is accommodated in the lens barrel. And a fixing portion that is erected in a direction perpendicular to the axis of the lens barrel and fixes the lens to the inner wall, and on the same circumference of the lens barrel on which the fixing portion is formed A direction in which the fixed portion is formed by forming the lens at a position facing the fixed portion across the axis of the lens barrel so as to face a peripheral side surface or a lens surface end of the lens. And a lens fixing structure having an opening for pushing the lens .

  According to a second aspect of the present invention, in the lens fixing structure according to the first aspect, the lens barrel is made of a thermoplastic material, and heat or ultrasonic waves are applied to the inner wall of the lens barrel. Thus, the inner wall is deformed to form the fixing portion.

According to a third aspect of the present invention, in the lens fixing structure according to the first or second aspect, at least two or more of the fixing portions are formed on the same circumference of the inner surface of the lens barrel. In addition, at least two openings are formed on the same circumference .

  According to a fourth aspect of the present invention, in the lens fixing structure according to any one of the first to third aspects, the lens barrel comes into contact with a lens surface end of one lens surface of the lens. An abutting part is formed, and the fixed part is brought into contact with the lens surface end of the other lens surface of the lens that is positioned in contact with the abutting part. It is characterized by being fixed to.

According to a fifth aspect of the present invention, in the lens fixing structure according to any one of the first to third aspects, the holding member that maintains a constant interval between the plurality of lenses housed in the lens barrel. has, on the lens surface end of one lens a certain distance is secured by the holding member, is brought into contact with the fixed portion, the lens surface end of the other lens, the end of the lens barrel the edge frame portion that is smaller in diameter than the opening diameter of the aperture of the lens diameter by abutting a plurality of the lens and between the holding member, is sandwiched between the inner surface of the edge frame portion and said fixed portion It is characterized by fixing.

  According to a sixth aspect of the present invention, in the lens fixing structure according to the fourth or fifth aspect, the lens surface end portion of the lens that contacts the fixing portion has a lens surface end portion that is smaller than the lens center portion. It is characterized by being inclined so as to be lowered.

  According to a seventh aspect of the present invention, in the lens fixing structure according to any one of the first to third aspects, the lens surface end portions of the upper surface and the lower surface of the lens that are in contact with the fixing portion are provided on the lens. It is formed by a plane perpendicular to the optical axis.

The invention according to an eighth aspect is the lens fixing structure according to any one of the first to seventh aspects, wherein the lens is adjusted after the optical axis of the lens is adjusted through the opening. It is fixed to the lens barrel by a fixing portion.

The invention according to claim 9 is the lens fixing structure according to any one of claims 1 to 8, wherein the opening and the fixing portion are formed at three locations at equal intervals in the circumferential direction. Features.

  The invention according to claim 10 is the lens fixing mechanism according to any one of claims 1 to 9, wherein the thickness of the cylindrical wall of the lens barrel in which the fixing portion is formed is different from that of the other cylinder. It is characterized by being thinner than the wall thickness.

  According to an eleventh aspect of the present invention, in the lens fixing structure according to any one of the first to tenth aspects, the lens is formed of glass.

  The invention according to claim 12 is the lens fixing structure according to any one of claims 1 to 10, wherein the lens is formed of a resin having a heat deformation temperature higher than a heat deformation temperature of the lens barrel. It is characterized by being.

According to claim 1 3 invention is characterized by an image reading unit using the lens fixing structure according to any one of claims 1 to 1 2.

According to claim 1 4 invention is characterized in that it is an image forming apparatus using the lens fixing structure according to any one of claims 1 to 1 2.

  According to the first to third aspects of the invention, the inner wall of the lens barrel is deformed to form the fixing portion, so that the lens wall of the lens barrel can be formed without increasing the processing accuracy of the lens and the lens barrel. By deforming it, it becomes possible to fix the lens to the lens barrel with high accuracy, and the cost can be reduced.

  Further, even when a plurality of lenses are fixed to the lens barrel, the lens can be fixed without increasing the inner diameter of the lens barrel, so that it is easy to reduce the size of the lens unit. .

Further, since the lens can be fixed to the lens barrel without using a filler such as an adhesive, the lens surface is not contaminated and stable optical characteristics can be ensured.
Furthermore, an opening is formed on the same circumference of the lens barrel on which the fixing portion is formed so as to face the peripheral side surface of the lens or the end of the lens surface. After adjusting the optical axis of the lens from this opening, the fixing portion Since the lens can be fixed by this, the optical axis can be adjusted in consideration of the variation of individual lenses, and a lens unit having more stable optical characteristics can be provided.
In addition, by inserting a rod-like member that is elongated from the opening and moving the lens surface in the direction in which the fixed portion is formed, the lens can be easily separated from the lens barrel, so the lens and the lens barrel can be reused. It becomes easy to improve recyclability.

In particular, according to the lens fixing structure according to claim 2, since the fixing portion can be formed by heat welding or ultrasonic welding, no outgas or the like is generated when fixing the lens, and the optical characteristics of the lens are improved. The lens can be fixed while being secured. In addition, the lens can be fixed more quickly than in the past.
According to the lens fixing structure of the third aspect, it is easy to fix the lens in a stable state by forming at least two fixing portions. Furthermore, since two or more openings are formed, the optical axis of the lens can be adjusted with higher accuracy, and the lens can be stably disassembled.

  According to the lens fixing structure of the fourth aspect, since the lens positioned by the abutting portion is fixed by the fixing portion, the lens can be fixed in a state where the position of the lens in the optical axis direction is personal and stable. It is possible to ensure high optical characteristics of the lens unit.

According to the lens fixing structure of the fifth aspect, by using the holding member, it is possible to keep the distance between the lenses constant and to stabilize the position of the lens in the optical axis direction. Furthermore, since the lens is positioned when the lens surface end of the lens contacts the inner surface of the edge frame, the lens can be easily positioned and fixed, and the number of lens assembly steps can be reduced. Can be achieved.

  According to the lens fixing structure of the sixth aspect, when the lens is fixed by the fixing portion, the fixing portion presses the lens toward the back surface of the lens, so that the lens can be fixed in a stable state.

  According to the lens fixing structure of the seventh aspect, since the lens surface end portions of the upper surface and the lower surface of the lens are formed by planes perpendicular to the optical axis of the lens, the force is applied from the side of the lens by the fixing portion. Is applied, an equal force is applied in the axial direction, making it difficult for the lens to move, making it easy to stabilize the fixed position of the lens.

  According to the lens fixing structure according to the eighth aspect, since the lens is fixed by the fixing portion after the position adjustment of the lens is completed and the optical axis adjustment is completed, it is possible to perform the adjustment considering the variation for each lens, and more stable. The obtained optical characteristics can be obtained.

  According to the lens fixing structure according to the tenth aspect, since the cylindrical wall of the lens barrel that forms the fixing portion is thin, when forming the fixing portion, only the thin wall portion is deformed to form another cylindrical wall. Therefore, the lens can be fixed without deforming the lens barrel body.

  According to the lens fixing structure of the eleventh aspect, since the lens is formed of glass, the lens is not deformed by the influence of heat or the like when the fixing portion is formed on the lens barrel, and the optical characteristics are reduced. Can be obtained stably.

  Further, according to the lens fixing structure according to claim 12, since the lens is formed of a resin having a heat deformation temperature higher than that of the lens barrel, similarly to the lens fixing structure according to claim 11. When the fixing portion is formed on the lens barrel, the lens is not deformed by the influence of heat or the like, and a lens unit having excellent optical characteristics can be stably obtained.

According to the image reading unit according to claim 1 3, the positioning of the lens can be accurately performed, it is provided with the lens unit having the optical properties of high precision, without causing a read error of the image, high reliability An image reading unit having performance can be provided.

According to the image forming apparatus according to claims 1 to 4, the positioning of the lens can be accurately performed, is provided with the lens unit having the optical properties of high precision, without causing a read error of the image, high reliability An image forming apparatus having performance can be provided.

Hereinafter, a lens unit using a lens fixing structure according to the present invention will be described in detail with reference to the drawings.

As shown in FIGS. 1 and 2, the lens unit 1 having the lens fixing structure according to the first embodiment includes three lenses 2 to 4 and a lens barrel 5 that houses the lenses 2 to 4. ing.

  The lens barrel 5 is made of thermoplastic resin, and is made of, for example, MULTILON RN-3120 (PC + ABS) manufactured by Teijin Chemicals Limited. The lens barrel 5 has a stepped cylindrical shape in which two cylindrical portions having different diameters are connected. The diameter of the upper first cylindrical portion 5a is larger than the diameter of the lower second cylindrical portion 5b, and the connecting portion between the first cylindrical portion 5a and the second cylindrical portion 5b has a cylindrical inner side. A stepped butting portion 6 is formed. Further, an abutting portion 7 that protrudes in the direction of the axis L from the inner wall of the lens barrel 5 is also formed in the middle of the second cylindrical portion 5b.

The lens 2 is stored in the first cylindrical portion 5a, and the lens 3 and the lens 4 are stored in the second cylindrical portion 5b. In the first cylindrical portion 5a, an opening 8 is formed in the vicinity of the abutting portion 6 so as to be able to face the peripheral side surface and the lens surface end of the lens 2 fixed to the first cylindrical portion 5a. The second cylindrical portion 5b also has openings 9 and 10 facing the peripheral side surfaces of the lens 3 and the lens 4 and the end portions of the lens surface at two locations near the upper surface and near the lower surface of the abutting portion 7. . As shown in FIG. 3, these openings 8 to 10 have a plane (for example, a BB plane in FIG. 2A) that vertically crosses the axis L of the lens barrel 5 and a cylinder of the lens barrel 5. Three portions are formed at equal intervals on the circumference (on the same circumference ) of the lens barrel 5 intersecting with the wall. The openings 8 to 10 are formed in an oval shape or a rectangular shape that is long in the direction of the axis L of the lens barrel 5, and the ends of the openings 8 to 10 are fixing portions 18a for fixing lenses 2 to 4 described later. It has reached the range beyond the position where .about.18c is formed.

  Also, the wall thickness of the first cylindrical portion 5a near the upper surface end of the lens 2, the vicinity of the side surface of the lens 3 of the second cylindrical portion 5b, and the vicinity of the lower end of the lens 4 is thinner than other cylindrical walls. Thin wall portions 12 to 14 are formed. Specifically, the thickness of the thin portions 12 to 14 is 2 mm, whereas the thickness of the other portions is 4 mm. Each of the thin portions 12 to 14 is equally provided at three places on the same circumference of the lens barrel 5. In the present embodiment, each of the thin portions 12 to 14 is provided at three locations, but is not limited to three locations, and may be two locations or four or more locations. Since the lenses 2 to 4 can be held from a plurality of locations by providing the thin portions 12 to 14 at two or more locations, the lenses 2 to 4 can be stably fixed.

  The lenses 2 to 4 are glass lenses formed of glass, the lens 2 is a convex meniscus lens, the lens 3 is a biconcave lens, and the lens 4 is a convex meniscus lens. The outer diameter of the lens 2 is formed to be substantially the same as or slightly smaller than the inner diameter of the first cylindrical portion 5a of the lens barrel 5, and the outer diameter of the lenses 3 and 4 is the same as that of the second cylindrical portion 5b. It is formed to be substantially the same as the inner diameter or slightly smaller in diameter.

  Next, a procedure for fixing the lenses 2 to 4 to the lens barrel 5 will be described.

  First, the lens 3 is inserted from the end opening 16 of the first cylindrical portion 5a, and the lower end portion of the lens 3 is brought into contact with the abutting portion 7 of the second cylindrical portion 5b. When the lens 3 comes into contact with the abutting portion 7, the opening 9 can face the peripheral side surface of the lens 3, so that the optical axis adjustment (position adjustment) of the lens 3 can be performed through the opening 9. After adjusting the optical axis of the lens 3, the thin portion 13 is deformed by applying heat to the thin portion 13 from the outer wall side of the lens barrel 5 using a heater or an ultrasonic horn. 5 is formed so as to stand in the direction of the axis L. When the fixing portion 18b is formed, heat is applied to the thin portion 13, but since the lens 3 is a glass lens, the lens itself is not deformed by heat. By forming the fixing portion 18b, the fixing portion 18b presses the lens 3 from the side to fix the lens 3 to the lens barrel 5.

  Similarly, the lens 2 is fitted into the first cylindrical portion 5a through the end opening 16 of the first cylindrical portion wall 5a, and the lower end of the lens 2 is brought into contact with the abutting portion 6 so that the opening 8 is formed. After the optical axis adjustment is performed, the inner wall of the thin portion 12 is deformed to form the fixing portion 18a, and the lens 2 is fixed. At this time, the lens 2 is a convex meniscus lens, and the lens surface with which the fixed portion 18a abuts has a convex shape, and the end of the lens surface is inclined so that the end is lower than the center of the lens. Therefore, the fixing portion 18a in contact with the end portion of the lens surface pushes the lens 2 down to the abutting portion 6 side, and the lens 2 can be securely fixed in the lens barrel 5 without play.

  Similarly, from the end opening 19 of the second cylindrical portion 5b, the lens 4 is fitted into the second cylindrical portion 5b, the upper end portion of the lens 4 is brought into contact with the abutting portion 7, and light is transmitted through the opening 10. After adjusting the axis, the inner wall of the thin portion 14 is deformed to form a fixing portion 18c, and the lens 4 is fixed. At this time, the lens 4 is a concave meniscus lens, and the lens surface with which the fixed portion 18c comes into contact is a downwardly inclined surface, so that the fixed portion 18c in contact with the end of the lens surface abuts the lens 4. The lens 4 is pushed up to the side 7 so that the lens 4 can be securely fixed at the fixed position without play.

  In this way, the lenses 2 to 4 are fixed to the lens barrel 5 by applying heat from the outer wall direction of the lens barrel 5 to form the fixing portions 18a to 18c. It is not necessary to perform heat treatment or the like from a direction parallel to the axial direction from the opening of the part, and the work burden can be reduced. Further, even if the processing accuracy of the lens barrel 5 is not increased in order to fix the lenses 2 to 4, the thin portions 12 to 14 are deformed to form the fixing portions 18a to 18c. Since it can be accurately fixed to the lens barrel, an inexpensive lens unit can be provided.

  In addition, since the thin portions 12 to 14 of the lens barrel 5 are heated to form the fixing portions 18a to 18c, the lens positions are fixed for each of the lenses 2 to 4 after the positions of the lenses 2 to 4 are adjusted. It is possible to perform adjustment in consideration of individual variations of the lenses 2 to 4, and to obtain more stable optical characteristics. In particular, since the individual lenses 2 to 4 can be adjusted for each lens by the openings 8 to 10 formed in the lens barrel 5 before the lenses are fixed by the fixing portions 18a to 18c, the accuracy is high. Optical characteristics can be obtained.

  Further, even when a plurality of lenses 2 to 4 are fixed to the lens barrel 5, the lenses 2 to 4 can be fixed to the lens barrel 5 without increasing the size of the lens barrel 5. It becomes easy to reduce the size of the unit 1.

  Furthermore, since it is not necessary to use an adhesive or the like to fix the lenses 2 to 4 to the lens barrel 5, there is no risk that the adhesive will adhere to the lens surface or the outgassing will cause the lens surface to become dirty. It is possible to ensure stable optical characteristics.

  Further, since the lenses 2 to 4 can be fixed by bringing the lenses 2 to 4 into contact with the abutting portions 6 and 7, the lenses 2 to 4 can be fixed in a state where the lenses 2 to 4 are stabilized. .

  Furthermore, since the thin portions 12 to 14 are only deformed to form the fixing portions 18a to 18c, the lenses 2 to 4 can be fixed without deforming other portions of the lens barrel 5.

  When the lenses 2 to 4 are removed from the lens barrel 5, a rod-like member elongated from the openings 8 to 10 is inserted, and the lenses 2 to 4 are pushed and moved in the direction in which the fixing portions 18a to 18c are formed. 4 can be separated from the lens barrel 5. In this way, the lenses 2 to 4 can be easily separated from the lens barrel 5, so that it becomes easy to improve the reuse and recyclability of the lens unit 1.

  While the lens unit according to the present invention has been described with reference to the drawings, the lens unit according to the present invention is not limited to the above-described one. For example, in the above-described first embodiment, the case where the lens is formed of glass has been described. However, the lens is not necessarily formed of glass. For example, even when a resin lens is used, if the thermal deformation temperature of the lens is higher than the thermal deformation temperature of the lens barrel, when the fixing portion is formed, the thermal deformation of the lens barrel By applying heat not lower than the temperature and not higher than the thermal deformation temperature of the lens to the thin portion, the fixed portion can be formed without deforming the optical characteristics of the lens. In the first embodiment described above, as an example, the case where MULTILON RN-3120 manufactured by Teijin Chemicals Ltd. is used for the lens barrel is shown. However, since the heat deformation temperature of this material is 86 ° C., the temperature is higher than this temperature. By forming the lens using ZEONEX E48R (thermal deformation temperature 110 ° C.) manufactured by Nippon Zeon Co., Ltd., which has a high deformation temperature, it is possible to form the fixed portion on the lens barrel without causing the lens to be thermally deformed. .

  In the first embodiment described above, the lens optical axis adjustment and fixing processing is performed one by one for each lens. However, the lens fixing processing does not necessarily have to be performed for each lens, and the light of all lenses is used. After performing the axis adjustment, multiple lenses may be fixed at a time, and after adjusting the optical axes of several lenses, the optical axes of the remaining lenses are adjusted and fixed. It is good also as a structure which performs a process.

  Next, a further description of the lens fixing structure according to the present invention will be given using another example 2 and example 3 different from the example 1 described above.

In Example 2, another lens unit including the lens fixing structure according to the present invention will be described. In the lens unit according to the second embodiment, the same members as those in the lens unit described in the first embodiment are denoted by the same reference numerals, and the detailed description thereof has already been performed in the first embodiment, and thus the description thereof is omitted. In addition, the lens unit shown in the second embodiment has the same configuration as the configuration described in the first embodiment, and thus has a common effect. However, the effects already described in the first embodiment are similarly described. Omitted.

  As shown in FIG. 4, the lens unit 20 according to the second embodiment includes three lenses 2 to 4, a lens barrel 21, and holding members 22 and 23. The three lenses 2 to 4 are made of glass in the same manner as in the first embodiment, and include a convex meniscus lens, a biconcave lens, and a convex meniscus lens.

  The lens barrel 21 is formed of a thermoplastic resin, and is formed of, for example, MULTILON RN-3120 (PC + ABS) manufactured by Teijin Chemicals Limited. The lens barrel 21 has a stepped cylindrical shape in which two cylindrical portions having different diameters are connected. The diameter of the upper first cylindrical portion 21a is larger than the diameter of the lower second cylindrical portion 21b, and the connecting portion between the first cylindrical portion 21a and the second cylindrical portion 21b has a cylindrical inner side. A stepped abutting portion 6 is formed. The edge opening 24 of the second cylindrical portion 21b has an edge frame portion 25 that is formed by bending in the direction of the axis L of the lens barrel 21 in accordance with the mirror surface shape of the lens surface circumferential end portion of the lens 4. Is formed. Due to the edge frame portion 25, the opening diameter of the end opening 24 of the second cylindrical portion 21 b is an opening having a smaller diameter than the diameter of the lens 4.

In the first cylindrical portion 21a, an opening 8 is formed in the vicinity of the abutting portion 6 so as to be able to face the peripheral side surface and the lens surface end of the lens 2 fixed to the first cylindrical portion 21a. The openings 8 are arranged at equal intervals on the circumference (on the same circumference ) of the lens barrel 21 where the plane perpendicular to the axis L of the lens barrel 21 and the cylinder wall of the lens barrel 21 intersect. Three places are formed. The opening 8 is formed in an elliptical or rectangular shape that is long in the direction of the axis L of the lens barrel 21, and the end of the opening 8 exceeds the position where the fixing portion 24 for fixing the lens 2 is formed. The range has been reached.

  Further, in the first cylindrical portion 21a, a thin portion 12 having a wall thickness thinner than that of other cylindrical walls is formed in the vicinity of the end of the lens surface on the upper surface of the lens 2. Specifically, the thickness of the thin portion 12 is 2 mm, whereas the thickness of the other portions is 4 mm. The thin wall portion 12 is equally provided at three locations on the same circumference of the lens barrel 21. In the second embodiment, the three thin portions 12 are provided. However, the present invention is not limited to the three locations, and similarly to the first embodiment, the number of the thin portions 12 is four or more. Also good.

  The holding members 22 and 23 are columnar members having a cylindrical member or a skeleton combined with an outer diameter substantially the same as the inner diameter of the second cylindrical portion 21 b, and are installed between the lens 2 and the lens 3. The first holding member 22 and the second holding member 23 installed between the lens 3 and the lens 4 are configured.

  Next, a procedure for housing the lenses 2 to 4 in the lens barrel 21 will be described.

  First, the lens 4 is inserted from the end opening 26 of the first cylindrical portion 21a with the convex surface of the lens 4 facing down, and the lens 4 is inserted into the end frame portion 25 formed in the end opening 24 of the second cylindrical portion 21b. Contact the inner wall surface. At this time, the lens 4 is locked by the edge frame portion 25 and optical positioning is performed.

  Next, the second holding member 23 is inserted from the end opening 26 of the first cylindrical portion 21a, and the lower end portion of the second holding member 23 is placed on the lens surface end portion of the lens 4 on the first cylindrical portion 21a side. Abut. Further, by inserting the lens 3 thereon, the second holding member 23 keeps the distance between the lens 3 and the lens 4 constant, and performs accurate positioning of the lens 3.

  Further, the first holding member 22 is inserted from the end opening 26 of the first cylindrical portion 21 a, the first holding member 22 is brought into contact with the lens surface on the end opening 26 side of the lens 3, and then the concave surface of the lens 2. The lens 2 is inserted from the end opening 26 so that the side contacts the upper end of the first holding member 22. The first holding member 22 can keep the distance between the lens 2 and the lens 3 at a predetermined distance, and the second holding member 23 can keep the distance between the lens 3 and the lens 4 at a predetermined distance. It becomes. Thus, by keeping the lenses 2 to 4 at a constant interval, the optical axes of the lenses 2 to 4 can be adjusted easily and accurately, and high optical characteristics can be ensured.

  After the lens positions of the lenses 2 to 4 are adjusted, the thin portion 12 is thermally deformed to form the fixing portion 18, whereby the lens 2 is fixed by the fixing portion 18. In particular, the end of the lens surface of the lens 2 with which the fixed portion 18 abuts becomes an upwardly inclined surface, so that the fixed portion 18 in contact with the end of the lens surface pushes down the lens 2 toward the second cylindrical portion 21b. More specifically, not only the lens 2 but also the lenses 3 and 4, the first holding member 22, and the second holding member 23 are pushed down toward the edge frame portion 25 by the fixing portion 18, so that the lenses 2 to 4 are not played. The lens barrel 21 can be securely fixed.

  Furthermore, since the opening diameter of the end opening 24 of the second cylindrical portion 21 b is smaller than the diameter of the lens 4 by the edge frame portion 25, the lens surface end portion of the lens 4 is brought into contact with the edge frame portion 25. By fixing the lens unit 20, the lenses 2 to 4 can be easily positioned, and it becomes easy to reduce the number of steps for assembling the lens unit 20.

In Example 3, another lens unit including the lens fixing structure according to the present invention will be described. In the lens unit according to the third embodiment, the same members as those in the lens units described in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof has been omitted. In addition, the lens unit shown in the third embodiment also has the same configuration as that described in the first and second embodiments, and thus has a common effect, but has already been described in the first and second embodiments. A description of the effect is omitted.

As shown in FIG. 5, the lens unit 30 having the lens fixing structure according to the third embodiment includes three lenses 32 to 34 and a lens barrel 31 that houses the lenses 32 to 34.

  The lens barrel 31 is formed of a thermoplastic resin, and is formed of, for example, MULTILON RN-3120 (PC + ABS) manufactured by Teijin Chemicals Limited. The lens barrel 31 has a stepped cylindrical shape in which two cylindrical portions having different diameters are connected. The diameter of the upper first cylindrical portion 31a is larger than that of the lower second cylindrical portion 31b, and the connecting portion between the first cylindrical portion 31a and the second cylindrical portion 31b has a cylindrical inner side. A stepped abutting portion 6 is formed.

A lens 32 is stored in the first cylindrical portion 31a, and a lens 33 and a lens 34 are stored in the second cylindrical portion 31b. In the first cylindrical portion 31a, an opening 35 that can face the peripheral side surface and the lens surface end of the lens 32 fixed to the first cylindrical portion 31a is formed in the vicinity of the abutting portion 6. The second cylindrical portion 31b also has an opening 36 facing the peripheral side surface of the lens 33 at the top of the cylinder, and an opening 37 facing the peripheral side surface of the lens 34 and the end of the lens surface at the bottom of the cylinder. These openings 35 to 37 are equally spaced on the circumference (on the same circumference ) of the lens barrel where the plane perpendicular to the axis L of the lens barrel 31 and the cylinder wall of the lens barrel 31 intersect. Three places are formed at intervals. The openings 35 to 37 are formed in an elliptical shape or a rectangular shape that is long in the axis L direction of the lens barrel 31, and ends of the openings 35 to 37 are fixing portions 40 for fixing lenses 32 to 34 described later. It is substantially the same position as the upper and lower ends of .about.42.

  Further, in the first cylindrical portion 31a and the second cylindrical portion 31b, thin portions 43 to 45 extending in a range longer in the axial center L direction than the lens thickness of the lenses 32 to 34 at positions where the lenses 32 to 34 are fixed. Is formed. Specifically, the thickness of the thin portions 43 to 45 is 2 mm, whereas the thickness of the other cylindrical wall is 4 mm. The thin portions 43 to 45 are equally provided at three places on the same circumference of the lens barrel 31. In the third embodiment, each of the thin portions 43 to 45 is provided at three locations, but is not limited to three locations, and may be two locations or four or more locations. Since the lenses 32 to 34 can be held from a plurality of locations by providing two or more thin portions, the lenses 32 to 34 can be fixed in a stable state.

  The lenses 32 to 34 are glass lenses made of glass. The lens 32 is a convex meniscus lens, and the outer diameter of the lens 32 is substantially the same as or slightly smaller than the inner diameter of the first cylindrical portion 31a. A belt-like portion 47 is formed on the outer peripheral edge of the lens 32, and an upper surface 47a and a lower surface 47b of the belt-like portion 47 are constituted by planes perpendicular to the optical axis. The lens 33 is a biconcave lens, and the lens 34 is a convex meniscus lens. Similarly, the lenses 33 and 34 have a belt-like portion 48 formed of a plane in which an upper surface and a lower surface intersect perpendicularly to the optical axis at the outer peripheral edge. 49 is formed, and the outer diameter of the lens is substantially the same as or slightly smaller than the inner diameter of the second cylindrical portion 31b.

  Next, a method for fixing the lenses 32 to 34 to the lens barrel 31 will be described.

  First, the lens 33 is inserted into the second lens barrel 31b of the lens barrel 31, and the lens 33 is disposed near the thin portion 44 formed on the first lens barrel 31a side of the second lens barrel 31b. At this time, the arm portion of the chuck is inserted from the opening 36 of the second lens barrel 31b, the lens 33 is sandwiched from the side, and the fixing position of the lens 33 is adjusted. The position of the lens 33 may be adjusted by operating a chuck at a predetermined position, or an image for adjusting the lens position is captured and the result calculated using the captured image is compared. It is also possible to adjust the position. After the position adjustment is completed, the fixing portion 40 (40a, 40b) is formed by applying heat to the thin portion 44 as in the first and second embodiments, and the lens 33 is fixed. At this time, a belt-like portion 48 constituted by a plane whose upper and lower surfaces intersect perpendicularly to the optical axis is formed at the outer peripheral edge of the lens 33, and the thickness of the lens of the lens 33, that is, the thickness of the belt-like portion 48. Since a wide thin portion 44 is formed in the direction of the axis L, heat is applied to the thin portion 44 to form the fixing portions 40 (40a, 40b), so that the lens 33 is fixed to the lens surface end portions on both surfaces of the lens 33. The portions 40a and 40b are formed, and the lens 33 is sandwiched and fixed by the fixing portions 40a and 40b formed on both surfaces. Since the lens 33 is sandwiched and fixed from both surfaces of the lens surface in this way, the lens 33 is firmly and accurately fixed, and stable optical characteristics can be ensured.

  In particular, the upper surface and the lower surface of the belt-shaped portion 48 are configured by planes that intersect perpendicularly to the optical axis, and when the optical axis of the lens 33 is adjusted, the optical axis and the axis L of the lens barrel 31 coincide with each other. Since the upper surface and the lower surface of the belt-like portion 48 are perpendicular to the inner surface of the lens barrel 31, the fixing portion 40 can apply force evenly from the lateral direction to the axis L direction with respect to the lens 33, so that the lens is It becomes difficult to move, and it becomes easy to stabilize the fixed position of the lens.

  Similarly, the lens 32 and the lens 34 are also firmly fixed to the lens barrel 31 by heating the thin portions 43 and 45 to form the fixing portions 41 and 42 in a state where the position is adjusted by the chuck. And it can be fixed with high accuracy.

  Although the lens unit 30 according to the third embodiment has been described above, the lens unit using the lens fixing structure according to the present invention is not limited to the one described in the third embodiment. For example, in the above-described third embodiment, the lenses 32 to 34 are held by the chuck via the openings 35 to 37 to adjust the lens position. However, the chuck openings 35 to 37 are not necessarily provided. A configuration may be adopted in which the front or rear surface of the lens is clamped with an air chuck or the like for adjustment and positioning. The upper and lower surfaces of the strips 47 to 49 are parallel surfaces formed by a plane perpendicular to the optical axis, but these two surfaces are not necessarily parallel to the optical axis. It may be an inclined surface having a certain angle.

  In addition, the lens unit according to the present invention is not limited to those described in the first to third embodiments, and may have another configuration. For example, the lens units shown in the first to third embodiments are configured by three lenses, which are a convex lens, a concave lens, and a convex lens (triplet type), but are not limited to a three-lens configuration. It may be composed of a single spherical lens or aspherical lens, and may be composed of two or more lenses, or may be composed of a group of lenses. It may be. The convex lens used may be a plano-convex lens or a convex mechanical lens, and the concave lens used may be a plano-convex lens, a biconcave lens, or a concave mechanical lens. It may be a lens.

  Further, in the case of a lens barrel having a structure in which the insertion direction of the lens is not limited to one direction as in the lens barrel 31 shown in the third embodiment, the lens is inserted from one direction to adjust the optical axis and fix the lens. Alternatively, the optical axis may be adjusted and fixed by inserting lenses from both sides.

Further, the lens fixing structure according to the present invention is not necessarily used only for the lens unit, but may be an image reading unit or an image forming apparatus using a lens fixing mechanism.

1 is a perspective view showing a lens unit according to Embodiment 1. FIG. It is a side sectional view showing an AA section shown in FIG. 1, (a) is an overall view, (b) is an enlarged view showing a broken line B1, (c) is an enlarged view showing a broken line B2, d) is an enlarged view showing a broken line B3. It is the plane sectional view showing the BB section shown in FIG. FIG. 6 is a cross-sectional view illustrating a lens unit according to Example 2, where (a) is an overall view and (b) is an enlarged view showing a broken line C1. FIG. 5 is a cross-sectional view illustrating a lens unit according to Example 3, where (a) is an overall view, (b) is an enlarged view showing a broken line D1, (c) is an enlarged view showing a broken line D2, and (d) is an enlarged view. It is the enlarged view which showed the broken line D3.

Explanation of symbols

1, 20, 30 Lens unit 2, 3, 4, 32, 33, 34 Lens 5, 21, 31 Lens barrel 8, 9, 10, 35, 36, 37 Aperture 12, 13, 14, 43, 44, 45 Thin part 18, 18a-18c, 40, 40a, 40b, 41, 42 Fixed part 6, 7 Abutting part

Claims (14)

A lens,
A lens barrel that houses the lens;
After the lens is stored in the lens barrel, the inner wall of the lens barrel is deformed to stand upright in a direction perpendicular to the axis of the lens barrel and fix the lens to the inner wall. Fixed part of
The peripheral side surface of the lens or the end of the lens surface faces the fixed portion on the same circumference of the lens barrel where the fixed portion is formed, and faces the fixed portion across the axis of the lens barrel. An opening for moving the lens in the direction in which the fixing portion is formed , and
The lens fixing structure characterized by having .   The lens barrel is formed of a thermoplastic material, and the inner wall is deformed by applying heat or ultrasonic waves to the inner wall of the lens barrel to form the fixing portion. The lens fixing structure according to claim 1. At least two fixing parts are formed on the same circumference of the inner surface of the lens barrel, and at least two openings are formed on the same circumference. The lens fixing structure according to claim 1 or 2.   The lens barrel is formed with an abutting portion that abuts on the lens surface end of one lens surface of the lens, and the lens on the other lens surface of the lens positioned in contact with the abutting portion. The lens fixing structure according to any one of claims 1 to 3, wherein the lens is fixed to the lens barrel by bringing the fixing portion into contact with a surface end portion. A holding member that holds a constant interval between the plurality of lenses housed in the lens barrel;
The lens surface end of one lens a certain distance is secured by the holding member, is brought into contact with the fixed portion, the lens surface end of the other lens, the opening diameter of the end opening of the lens barrel by abutting the edge frame portion that is smaller in diameter than the diameter of the lens, a plurality of the lens and between the holding member, to be fixed by sandwiched between the inner surface of the edge frame portion and said fixed portion The lens fixing structure according to any one of claims 1 to 3, wherein:   6. The lens surface end portion of the lens that contacts the fixed portion is inclined so that the lens surface end portion is lower than the lens center portion. Lens fixing structure.   4. The lens surface ends of the upper surface and the lower surface of the lens with which the fixed portion abuts are formed by a plane perpendicular to the optical axis of the lens. The lens fixing structure according to Item 1. 8. The lens according to claim 1, wherein the lens is fixed to the lens barrel by the fixing portion after the optical axis of the lens is adjusted through the opening. 9. The lens fixing structure described in 1. The lens fixing structure according to any one of claims 1 to 8, wherein the opening and the fixing portion are formed at three positions at equal intervals in the circumferential direction . The thickness of the cylindrical wall of the lens barrel in which the fixing portion is formed is thinner than the thickness of the other cylindrical walls. The lens fixing structure described in 1.   The lens fixing structure according to any one of claims 1 to 10, wherein the lens is made of glass.   The lens fixing structure according to any one of claims 1 to 10, wherein the lens is formed of a resin having a heat deformation temperature higher than a heat deformation temperature of the lens barrel. An image reading unit using the lens fixing structure according to any one of claims 1 to 12. An image forming apparatus using the lens fixing structure according to any one of claims 1 to 12.

Images