JP2015031930A - Lens unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens unit which causes minimal distortion of a resin lens when mounting the resin lens in a holder (lens barrel, barrel).SOLUTION: A lens unit includes a resin lens 22 and a fourth holder 5 having a fitting hole 25 for the resin lens 22 to be fitted. The fourth holder 5 has a plurality of fitting protrusions 28 which are provided on an inner circumferential surface of the fitting hole 25 at an interval along a circumferential direction thereof and protrudes from the inner circumferential surface of the fitting hole 25 to be in contact with an outer circumferential surface of the resin lens 22 at a plurality of points, thereby holding the resin lens 22. A recess 30 with a gap between itself and the outer circumferential surface of the resin lens 22 is provided between each of the fitting protrusions 28 on the inner circumferential surface of the fitting hole 25. The resin lens 22 is bonded to the fourth holder 5 by filling the recesses 30 with an adhesive.

Description

  The present invention relates to a lens unit in which a resin lens is incorporated.

In home video cameras and digital still cameras, a lens unit that uses multiple lenses by combining a fixed imaging lens with a moving lens for focusing, zooming, camera shake correction, etc. (For example, refer to Patent Documents 1 and 2).
In such a lens unit, a resin lens (plastic lens) is used instead of a part of a conventional glass lens.

  In such a lens unit, a fixed lens is supported by a holder (lens barrel, barrel) fixedly provided on the lens unit case, and in the optical axis direction like a lens for focusing or zooming. The moving lens is supported by a holder that is movable in the optical axis direction within the case. At least a part of the camera shake correction lens is supported by a holder that can move in the Y direction and the Z direction when the optical axis direction is the X direction.

  For example, a circular resin lens is supported in a state of being fitted into the cylindrical fitting hole of the holder by being pushed into a fitting hole having a cylindrical inner peripheral surface of the holder, and is bonded, for example. It is fixed to the holder by the agent.

  The resin lens is molded by, for example, injection molding, and the gate is cut at the time of molding. For example, the gate mark after cutting the resin lens gate protrudes from the cylindrical outer peripheral surface of the resin lens. Then, when the resin lens is fitted into the cylindrical fitting hole of the holder as described above, the gate mark becomes an obstacle. Further, by fitting the resin lens to the holder as described above, the outer peripheral surface of the resin lens is positioned on the inner peripheral surface of the holder, and the optical axis position of the resin lens is aligned. This interferes with lens positioning.

  Therefore, when the gate of the resin lens is cut, the gate is cut slightly inside the circular outer shape of the resin lens. In this case, the outer shape of the resin lens is not a perfect circle, and a part of the outer periphery of the circle is linear.

  In addition, the resin lens is not made circular when molding the resin lens. From the beginning, a part of the outer periphery of the circle is molded into a linearly cut shape, and a gate is provided in the cut shape. By cutting the gate at a portion, the gate trace of the cut gate may be arranged inside the outer circle of the resin lens.

Japanese Patent No. 2012-220920 Japanese Patent No. 2012-53230

  By the way, there exists a possibility that a resin lens may produce distortion by the stress which arises by fitting, when making it fit in a holder as mentioned above. Further, when fixing with an adhesive, the lens is distorted due to the stress caused by curing shrinkage of the adhesive. In this case, although depending on conditions such as the type of adhesive and the type of resin of the resin lens, distortion of 0.5 μm to 1.2 μm may occur.

  Further, as described above, if the outer diameter is not circular so that the gate mark does not interfere with the attachment of the lens to the holder, the stress is likely to be partially concentrated and easily distorted. If the resin lens is distorted as described above, the optical characteristics required for the resin lens may not be satisfied.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lens unit that can suppress distortion of a resin lens when the resin lens is attached to a holder (lens barrel, barrel). .

The lens unit of the present invention is a lens unit comprising a resin lens and a holder having a fitting hole into which the resin lens is fitted,
A plurality of the holders are provided on the inner peripheral surface of the fitting hole at intervals in the circumferential direction, and protrude from the inner peripheral surface of the fitting hole to contact the outer peripheral surface of the resin lens from a plurality of locations. A fitting convex part to be fitted with the resin lens;
A concave portion is provided between the fitting convex portions on the inner peripheral surface of the fitting hole and spaced from the outer peripheral surface of the resin lens.

According to such a configuration, when the resin lens is pushed into the fitting hole of the holder and fitted, the concave portion that does not contact the outer peripheral surface of the resin lens is sandwiched between the inner peripheral surface of the fitting hole of the holder. Thus, only the plurality of fitting convex portions provided in contact with the outer peripheral surface of the resin lens are fitted.
As a result, it is possible to reduce the force applied to the resin lens as compared with the case where the substantially entire outer peripheral surface of the resin lens and the substantially entire inner peripheral surface of the fitting hole come into contact with each other. The distortion of the resin lens can be reduced. Thereby, sufficient optical characteristics required for the resin lens can be obtained.

In the configuration of the present invention, the holder is provided so as to protrude from the inner peripheral surface of the fitting hole, and is in contact with the outer peripheral portion of one lens surface of the resin lens along the optical axis direction of the resin lens. It has a positioning part that determines the position,
The fitting convex portion includes a facing surface that is a concave arc surface facing the cylindrical outer peripheral surface of the resin lens,
The opposing surface is provided adjacent to the positioning portion, and a fitting surface that contacts the outer peripheral surface of the resin lens and fits the resin lens;
A guide which is provided adjacent to the opposite side of the positioning portion of the fitting surface and is an arc surface whose diameter is larger than that of the fitting surface in order to guide the resin lens inserted into the fitting hole. With a surface,
The length of the fitting surface along the optical axis direction is preferably shorter than the length of the outer peripheral surface of the resin lens along the optical axis direction.

  According to such a configuration, the entire facing surface of the fitting convex portion facing the resin lens does not contact the outer peripheral surface of the resin lens, but the front side in the pushing direction when the resin lens is pushed into the fitting hole. Only the outer peripheral surface of the lens comes into contact with the mating surface of the opposing surface of the fitting convex portion, and the force applied to the resin lens can be reduced compared to the case where the entire opposing surface is fitted to the outer peripheral surface of the resin lens. It becomes possible, and distortion of a resin lens can be reduced. The guide surface, which is an arc surface adjacent to the fitting surface, is an arc surface having a diameter larger than the diameter of the fitting surface, which is an arc surface contacting the outer peripheral surface of the resin lens, and is inserted into the fitting hole. Since it is a surface for guiding the resin lens, it does not come into contact with the outer peripheral surface of the resin lens fitted in the fitting hole. When the resin lens is fitted into the fitting hole in the state guided by the guide surface, it is possible to prevent the resin lens from being inclined and inserted with respect to the axial direction of the fitting hole. If the resin lens is inserted into the fitting hole in a slightly tilted state, an extra force is applied to the resin lens, causing distortion of the resin lens, but this can be suppressed by providing a guide surface.

  Moreover, in the said structure of this invention, the outer peripheral surface of the said resin lens and the inner peripheral surface of the said fitting hole are adhere | attached by the said recessed part by putting the adhesive which becomes rubbery when it hardens | cures in the said recessed part. Preferably it is.

  According to such a configuration, since an adhesive that becomes rubbery when cured is used, for example, the stress generated in the lens is reduced compared to the case where the adhesive that is cured when cured is cured and contracted, and distortion of the lens is reduced. Occurrence can be suppressed. Further, in this case, since the entire outer peripheral surface of the lens is not bonded, but is bonded only at the concave portion, even if there is an influence due to curing shrinkage or the like, it can be reduced. Moreover, the recessed part produced between a fitting convex part can be utilized effectively for adhesion | attachment.

Further, in the configuration of the present invention, the resin lens is provided with a gate mark of a gate cut at the time of injection molding of the resin lens protruding outward from the outer peripheral surface of the resin lens,
It is preferable that the gate mark is disposed in the recess.

  According to such a configuration, since the resin lens is not cut in the outer peripheral surface as in the prior art, it is difficult for stress to concentrate when a force acts on the outer peripheral surface of the resin lens. Lens distortion can be reduced. Moreover, the recessed part produced between the said fitting convex parts can be used effectively.

  According to the present invention, since distortion of the resin lens that occurs when the resin lens is attached to the holder can be reduced, the optical characteristics required for the resin lens can be sufficiently satisfied.

It is sectional drawing which shows the lens unit of embodiment of this invention. It is a front view which shows the holder of the said lens unit. It is a perspective view which shows the said holder and a lens. It is a perspective sectional view showing the holder and a lens. It is a perspective sectional view showing the holder and a lens. It is sectional drawing which shows the said lens unit. It is principal part sectional drawing which shows the said lens unit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The lens unit of this embodiment mainly has an optical zoom function and an optical camera shake correction function provided in a video camera for general consumers, and both a glass lens and a resin lens are used. .

  As shown in FIG. 1, the lens unit of this embodiment includes a main case 1 and a plurality (13 pieces) of the main case 1 arranged in the main case 1 from the objective side (photographing target side) to the imaging side (imaging element side). Lenses 11 to 23 are arranged side by side.

  The four objective lenses 11 to 14 are lenses that are fixed to the main case 1 and supported by a first holder 2 that is fixedly provided at an end of the main case 1 on the objective side. These lenses 11 to 14 are glass lenses.

  A second holder 3 that is movable along the optical axis direction for zooming is disposed on the image forming side of the first holder 2, and three lenses 15 to 17 are supported on the second holder 3. Yes. These lenses 15 to 17 are glass lenses.

  On the image forming side of the second holder 3, the third holder 4 that supports the camera shake correction lenses 18 and 19 is disposed. The third holder 4 includes a portion that fixes the lens 18 to the main case 1 and a portion that supports the lens 19 so that the lens 19 is movable in a direction orthogonal to the optical axis. The lens 18 is a glass lens, and the lens 19 is a resin lens.

  On the image forming side of the third holder 4, a fourth holder 5 that is movable along the optical axis direction is arranged for focusing. The fourth holder 5 is supported by three lenses 20 to 22. Has been. Of the three lenses 20 to 22, the two lenses 20 and 21 on the objective side are glass lenses, and the lens 22 on the most imaging side is a resin lens.

  A fifth holder 6 fixed to the main case 1 is disposed on the image forming side of the fourth holder 5, that is, the image forming side, and a lens 23 is supported by the fifth holder 6. It is a resin lens.

  In such a lens unit, the resin lens 19, the resin lens 22, and the resin lens 23 are attached to the third holder 4, the fourth holder 5, and the fifth holder 6, respectively, by a substantially similar attachment structure.

The structure for attaching the resin lens to the holder, which is a characteristic part of the lens unit of this embodiment, will be described taking the structure for attaching the resin lens 11 to the fourth holder 5 as an example.
As shown in FIGS. 2 to 7, the fourth holder 5 has two glass lenses 20 and 21 (shown in FIG. 1) supported on the object side and one resin lens 22 supported on the imaging side. The The fourth holder 5 includes a fitting hole 25 that supports the lenses 20 to 22 including the resin lens 22.

  A positioning portion 26 is provided on the inner peripheral surface of the fitting hole 25 so as to protrude inward from the inner peripheral surface. The positioning portion 26 is annular and provided in a plate shape, and is disposed so as to be orthogonal to the axial direction of the fitting hole 25. The two side surfaces of the positioning portion 26 are substantially flat surfaces that are orthogonal to the axial direction of the fitting hole 25.

  The image forming side of the positioning portion 26 is a portion to which the resin lens 22 is attached, and the objective side of the positioning portion 26 is a portion to which the glass lenses 20 and 21 are attached. The inner diameter of the positioning portion 26 is narrower than the outer shape of the resin lens 22 attached to the fitting hole 25, and the one lens surface on the objective side of the resin lens 22 that is pushed into the fitting hole 25 from the imaging side. The outer peripheral part contacts the positioning part 26, and the position along the optical axis direction of the resin lens 22 is determined.

  The surface of the positioning portion 26 on the side where the outer peripheral portion of the resin lens 22 on the imaging side abuts has two steps, and the abutment surface 27 differs in position along the axial direction of the fitting hole 25 and the non-contact surface 27. A plurality of contact surfaces 29 are provided. Each contact surface 27 has the same position along the axial direction of the fitting hole 25, and each non-contact surface 29 has the same position along the axial direction of the fitting hole 25. Further, the contact surface 27 is arranged on the image forming side with respect to the non-contact surface 29. As a result, only the contact surface 27 of the positioning portion 26 contacts the outer peripheral portion of one lens surface of the resin lens 22 fitted in the fitting hole 25, and the non-contact surface 29 of the positioning portion 26 has the resin lens 22. It is supposed not to touch.

  Further, the contact surface 27 and the non-contact surface 29 are alternately provided along the circumferential direction of the annular positioning portion 26, and the contact surface 27 is equally spaced along the circumferential direction of the positioning portion 26. A plurality (six) are provided, and a plurality (six) of non-contact surfaces 29 are provided at equal intervals along the circumferential direction. The positions of the contact surfaces 27 along the circumferential direction of the fitting holes 25 correspond to the positions of the recesses 30 described later, and the positions of the non-contact surfaces 29 along the circumferential direction of the fitting holes 25 are described later. The positions of the fitting convex portions 28 are arranged correspondingly.

  The inner peripheral surface on the object side from the positioning portion 26 protrudes from the inner peripheral surface of the fitting hole 25 toward the outer peripheral surface of the resin lens 22 positioned by the positioning portion 26, and comes into contact with the outer peripheral surface of the resin lens 22. A plurality of fitting projections 28 are provided. The fitting projections 28 are provided on the inner peripheral surface of the fitting hole 25 so as to be arranged at equal intervals in the circumferential direction. In this embodiment, six fitting projections 28 are provided.

  In addition, between the adjacent fitting convex portions 28, there is a concave portion 30 separated from the outer peripheral surface of the resin lens 22 fitted in the fitting hole 25. Therefore, the inner peripheral surface of the fitting hole 25 has a shape in which unevenness is repeated, and the inner peripheral surface of the fitting hole 25 contacts the outer peripheral surface of the resin lens 22 at the portion of the fitting convex portion 28, and the concave portion 30. In this part, the inner peripheral surface of the fitting hole 25 is separated from the outer peripheral surface of the resin lens 22. Thereby, the six fitting convex portions 28 come into contact with the outer peripheral surface of the resin lens 22 from six locations and are fitted to the resin lens 22.

  Further, in more detail, as shown in FIG. 7, the facing surface 31 of the fitting convex portion 28 facing the resin lens 22 is substantially the same as the width along the optical axis direction of the outer peripheral surface of the resin lens 22. The side adjacent to the positioning portion 26 has a width as a fitting surface 32 with the width being about half of the width, and the portion adjacent to the opposite side of the positioning portion 26 of the fitting surface 32 is a guide surface. 33.

  The fitting surface 32 of each fitting convex portion 28 is an arc surface having a radius of curvature substantially the same as the radius of the cylindrical outer peripheral surface of the resin lens 22, and an arc surface centering on the central axis of the fitting hole 25. It has become. By pushing the resin lens 22 into the fitting hole 25 so that the six fitting surfaces 32 are in contact with the outer peripheral surface of the resin lens 22, the resin lens 22 is formed on the six fitting convex portions 28. The state is engaged. In this state, the resin lens 22 is positioned so that its optical axis position coincides with the center axis of the fitting hole 25. That is, the fitting surface 32 abuts on the half-width portion of the outer peripheral surface of the resin lens 22 on the objective side, thereby fitting the resin lens 22 and positioning the resin lens 22 by the outer peripheral surface.

  The guide surface 33 is provided adjacent to the image forming side of the fitting surface 32, that is, adjacent to the opposite side of the positioning portion 26, and the radius of the arc surface serving as the guide surface 33 is slightly smaller than the radius of the outer peripheral surface of the resin lens 22. The guide surface 33 is separated from the outer peripheral surface of the resin lens 22 in a state where the fitting surface 32 is in contact with the outer peripheral circle of the resin lens 22. The center of the arc of the fitting surface 32 and the center of the arc of the guide surface 33 coincide.

  The guide surface 33 is provided up to the end of the fitting hole 25 on the image forming side, and corresponds to the end of the guide surface 33 on the fitting surface 32 side and the end of the fitting hole 25 on the image forming side. Each of the end portions is a part of a conical surface whose diameter increases as the distance from the positioning portion 26 increases. When the resin lens 22 is inserted into the fitting hole 25, the resin lens 22 is inserted into the fitting hole 25. Guide to the center side.

  That is, when the resin lens 22 is pushed into the fitting hole 25, the guide surface 33 guides the resin lens 22 toward the center side of the plurality of guide surfaces 33 at the imaging side end of the guide surface 33. Further, when the resin lens 22 is moved from the position of the guide surface 33 to the position of the fitting surface 32, the resin lens 22 is guided to the center side of the plurality of fitting surfaces 32. Thus, the resin lens 22 is prevented from fitting into the fitting hole 25 while the optical axis direction of the resin lens 22 is oblique with respect to the central axis of the fitting hole 25.

  The concave portion 30 has a shape in which the side facing the resin lens 22 fitted in the fitting hole 25 and the imaging side are opened and the objective side is closed. Further, the concave 30 is closed by the resin lens 22 on the side facing the resin lens 22. In addition, the surface that closes the objective side of the concave portion 30 (the surface that faces the imaging side of the concave portion) is disposed closer to the imaging side than the surface that faces the imaging side of the positioning portion 26. At the portions of these concave portions 30, there is a gap between the outer peripheral surface of the resin lens 22 and the inner peripheral surface of the fitting hole 25, and the image forming side of the portion that becomes the gap is opened.

These recesses 30 are filled (injected) with an adhesive from a portion opened to the imaging side of these recesses 30, and the outer peripheral surface of the resin lens 22 and the fitting hole 25 separated from each other at the recess 30 portion. Are adhered to the inner peripheral surface.
This adhesive preferably has a high viscosity, for example, 20000 to 50000 mP (2 to 5 Pa · S). If the viscosity is low, the adhesive may enter the outer peripheral surface of one of the positioning portion 26 and the resin lens 22 by capillary action, and the resin lens 22 positioned on the positioning portion 26 may be displaced.

Moreover, it is preferable that an adhesive agent is what has thixotropy (high thing). The thixotropy means that the solid shape is relatively maintained in a stationary state where no force is applied. For example, the thixotropy exhibits a characteristic that the liquid does not easily drip when applied to a wall surface.
The adhesive preferably exhibits rubber-like flexibility when cured. For example, an elastomer-based adhesive, an elastic adhesive (silicone-based adhesive, modified silicone-based adhesive, urethane-based adhesive) Agents) and the like.

  The resin lens 22 is a resin lens having an outer peripheral surface formed into a cylindrical shape, and a gate mark 40 of a gate cut at the time of injection molding protrudes from the outer peripheral surface. This gate mark 40 is disposed in the recess 30. The protruding length of the gate mark 40 from the outer peripheral surface of the resin lens 22 is shorter than the distance between the outer peripheral surface of the resin lens 22 and the inner peripheral surface of the fitting hole 25 in the recess 30.

  Next, a method for attaching the resin lens 22 to the fourth holder 5 in such a lens unit will be described. For example, the fourth holder 5 is arranged with the surface facing the image forming side facing upward, and the resin lens 22 is pushed into the fitting hole 25. At this time, the resin lens 22 is guided by the guide surface of the fitting convex portion 28, thereby preventing the resin lens 22 from being tilted when being pushed into the fitting hole 25.

  Further, when the resin lens 22 is pushed into the fitting hole 25, the gate mark 40 of the resin lens 22 is set to a position where it enters any one of the plurality of recesses 30. Thereby, even if the gate mark 40 protrudes from the outer peripheral surface of the resin lens 22, the insertion of the resin lens 22 into the fitting hole 25 is not obstructed, and the positioning by the outer peripheral surface of the resin lens 22 is obstructed. Never become. The resin lens 22 is pushed into the fitting hole 25 until it contacts the positioning portion 26.

  Next, an adhesive is potted in the recess 30. As a result, the outer peripheral surface of the resin lens 22 and the inner peripheral surface of the fitting hole 25 (the inner surface of the concave portion 30) facing each other with a gap in the concave portion 30 are bonded, and the resin lens 22 is fixed to the fourth holder 5. To do.

  In such a lens unit, when the resin lens 22 is fitted into the fitting hole 25 of the holder (fourth holder 5), a force does not act on the entire outer periphery of the resin lens 22, but the fitting convexity. Since the force acts only on the portion of the portion 28 that contacts the fitting surface 32, distortion due to the fitting of the resin lens 22 into the fitting hole 25 can be reduced. That is, for example, about half of the length along the circumferential direction of the outer peripheral surface of the resin lens 22 and only about half of the length along the optical axis direction of the outer peripheral surface of the resin lens 22 are fitted to the fitting surface 32. Therefore, although the fitting force becomes weak, the force applied to the resin lens 22 can be reduced by that amount, and the distortion of the resin lens 22 can be reduced.

Further, since the fixing with the adhesive is also performed only in the concave portion 30, the force applied to the resin lens 22 due to curing shrinkage or the like can be reduced.
Furthermore, the adhesive force between the resin lens 22 and the holder (fourth holder 5) is reduced by using a rubber-curing adhesive to reduce the force acting on the resin lens 22 from the adhesive such as curing shrinkage. Distortion can be reduced.

  Furthermore, since the resin lens 22 has the gate mark 40 protruding from the outer peripheral surface, a part of the resin lens is not linearly cut, and the outer peripheral surface is cylindrical (rounded). (Similar shape), it is difficult to distort, and distortion can be further reduced.

  For these reasons, the distortion of the resin lens 22 that occurs when the resin lens 22 is fitted into the fitting hole 25 of the holder and bonded with an adhesive is reduced, and the optical characteristics inherent to the resin lens 22 are reduced. It is possible to prevent deterioration due to distortion.

5 Fourth holder (holder)
22 resin lens 25 fitting hole 26 positioning portion 28 fitting convex portion 30 concave portion 32 fitting surface 33 guide surface 40 gate mark

Claims (4)

A lens unit comprising a resin lens and a holder having a fitting hole into which the resin lens is fitted,
A plurality of the holders are provided on the inner peripheral surface of the fitting hole at intervals in the circumferential direction, and protrude from the inner peripheral surface of the fitting hole to contact the outer peripheral surface of the resin lens from a plurality of locations. A fitting convex part to be fitted with the resin lens;
A lens unit comprising: a concave portion spaced between the fitting convex portions on the inner peripheral surface of the fitting hole and the outer peripheral surface of the resin lens. The holder includes a positioning portion that protrudes from an inner peripheral surface of the fitting hole and determines a position along the optical axis direction of the resin lens by contacting an outer peripheral portion of one lens surface of the resin lens. ,
The fitting convex portion includes a facing surface that is a concave arc surface facing the cylindrical outer peripheral surface of the resin lens,
The opposing surface is provided adjacent to the positioning portion, and a fitting surface that contacts the outer peripheral surface of the resin lens and fits the resin lens;
A guide which is provided adjacent to the opposite side of the positioning portion of the fitting surface and is an arc surface whose diameter is larger than that of the fitting surface in order to guide the resin lens inserted into the fitting hole. With a surface,
The lens unit according to claim 1, wherein a length of the fitting surface along the optical axis direction is shorter than a length of the outer peripheral surface of the resin lens along the optical axis direction.   2. The outer peripheral surface of the resin lens and the inner peripheral surface of the fitting hole are bonded to each other by inserting an adhesive that becomes rubbery when cured into the concave portion. Alternatively, the lens unit according to claim 2. The resin lens is provided with a gate mark of a gate cut at the time of injection molding of the resin lens protruding outward from the outer peripheral surface of the resin lens,
The lens unit according to any one of claims 1 to 3, wherein the gate mark is disposed in the concave portion.

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