JP4147670B2 - Optical head lens support structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens support structure for an optical head used in an optical disk device, a magneto-optical disk device, etc., and prevents an optical axis change due to a temperature change.
[0002]
[Prior art]
An example of a mounting structure for mounting a non-movable lens (a lens that is not a movable lens such as an objective lens) in the optical head is shown in FIG. A lens holding V-shaped groove 12 is formed in the fixed portion 10 in the optical head. A lens 14 is accommodated in the V-shaped groove 12 with its optical axis (center axis) 16 aligned with a predetermined optical axis position in the optical head. A presser spring (plate spring) 18 is fixed to the fixed portion 10 by fixing one end thereof with a screw 19. The lower surface near the other end of the presser spring 18 is pressed against the outer peripheral surface 14 a of the lens 14 to press and hold the lens 14 in the V-shaped groove 12.
[0003]
[Problems to be solved by the invention]
According to the lens support structure of FIG. 2, when the lens 14 expands and contracts due to a temperature change, the diameter of the lens 14 changes, for example, as indicated by reference numeral 14 ', and accordingly, the position of the optical axis 16 is indicated by reference numeral 16'. It changes (shifts) as shown. This deviation amount ΔL is expressed by the following equation.
ΔL = r × ΔT × K
Where r: lens radius ΔT: temperature change K: linear expansion coefficient
A plastic lens is often used as a lens of the optical head in order to reduce the cost and weight. However, since the plastic lens has a large linear expansion coefficient K, the shift amount ΔL of the optical axis 16 due to the temperature change ΔT is large. In order to reduce the amount of deviation ΔL of the optical axis 16, the following measures are necessary.
(A) Replace with a lens (such as a glass lens) having a small linear expansion coefficient.
(B) In order to reduce the value of the radius r, an outer cylinder is made of a metal having a small linear expansion coefficient and the lens 14 is held in the outer cylinder.
[0005]
However, the method (a) has a problem that the lens is expensive, and the method (b) is expensive because the outer cylinder is used.
[0006]
The present invention is intended to provide a lens support structure for an optical head that solves the problems in the prior art and prevents the change of the optical axis due to temperature.
[0007]
[Means for Solving the Problems]
The lens support structure of the present invention is a structure in which a supported body in which a lens body is fixedly arranged is supported by a support portion of an optical head body, and the supported body is supported at a predetermined optical axis position of the optical head, The supported body has first and second supported surfaces at opposite positions of the periphery of the lens body across the optical axis of the lens body. Having first and second support surfaces for abutting and supporting the first and second supported surfaces, and interposing an elastic force by an elastic member between the supported body and the support portion, The first and second supported surfaces are pressed against and contacted with the first and second support surfaces, respectively, and the supported body is supported by the support portion. Is configured on a first plane passing through the optical axis of the lens body.
[0008]
According to this lens support structure, the first and second supported surfaces formed on the planes passing through the optical axis at the positions on both sides of the optical axis of the lens main body are supported by the lens body. Is supported in contact with the first and second support surfaces formed on the support portion of the optical head main body, so that the supported body is supported on the first plane passing through the lens optical axis. For this reason, even if the lens expands and contracts in the radial direction due to temperature change, the optical axis position does not change. Therefore, a lens having a large linear expansion coefficient such as a plastic lens can be used.
[0009]
Further, according to another lens support structure of the present invention, in addition to the support structure by the first and second supported surfaces and the support surface, the supported body is a light beam of the lens body at the peripheral portion of the lens body. Third and fourth supported surfaces further having third and fourth supported surfaces at positions opposite to each other with the shaft interposed therebetween, wherein the support portion abuts and supports the third and fourth supported surfaces. The third and fourth supported surfaces are further provided by the elastic force by the elastic member or the elastic force by the elastic member separately interposed between the supported body and the support portion. Each of the third and fourth supported surfaces is on a second plane passing through the optical axis of the lens body by pressing and abutting on the fourth support surface to support the supported body on the support portion. It is composed of.
[0010]
According to this another lens support structure, since the supported body having the lens body is supported on the first and second planes orthogonal to the lens optical axis, the change in the lens optical axis due to the temperature change in two directions. Can be suppressed about. The first and second planes can be planes that are orthogonal to each other or planes that are not orthogonal to each other.
[0011]
According to still another lens support structure of the present invention, in addition to the support structure by the first and second supported surfaces and the support surface, the supported body has a third supported surface at the peripheral portion of the lens body. And further including a third support surface that abuts and supports the third supported surface, and an elastic force by the elastic member or separately between the supported body and the support portion. The third supported surface is supported by the support portion by pressing and contacting the third supported surface with the third supporting surface by the elastic force of the interposed elastic member. The surface is configured on a second plane that passes through the optical axis of the lens body and is orthogonal to the first plane.
[0012]
According to this further lens support structure, the supported body having the lens body is supported on the first and second planes orthogonal to the lens optical axis and orthogonal to each other. The change can be suppressed in two directions.
[0013]
Still another lens support structure of the present invention includes a direction passing through the optical axis of the lens body and perpendicular to the first plane, in addition to the support structure by the first and second supported surfaces and the support surface. A convex and concave fitting structure is formed on the opposed surface of the supported body and the supporting part, and the optical axis of the lens body is moved in the direction along the first plane by the fitting structure. It is formed by locking.
[0014]
According to this still another lens support structure, the change of the optical axis of the lens can be suppressed in two directions orthogonal to each other by the fitting structure of the first plane and the convex portion and the concave portion in the direction orthogonal to the first plane. it can.
[0015]
In addition, the said to-be-supported body can be comprised by integral molding of a plastics, for example, and can comprise each said support surface on the one side of the protrusion part comprised by protruding to the outward from the peripheral part of the lens main body.
[0016]
Further, the elastic member can be constituted by a leaf spring in which one end is supported by a fixed portion of the optical head and the other end presses and contacts the outer peripheral surface of the supported body to generate the elastic force, for example. .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment in which the present invention is applied to a non-movable lens such as a condenser lens or a collimator lens in front of the photodetector in the optical head will be described below.
[0018]
(Embodiment 1)
A first embodiment of the present invention is shown in FIG. The supported body 20 is entirely made of an integrally molded product of plastic. The supported body 20 includes a lens body 22 having a cylindrical outer shape and projecting portions 24 and 26. The projecting portions 24 and 26 are configured to extend in a direction parallel to the optical axis 28 at positions opposite to each other across the optical axis (center axis) 28 of the lens body 22 on the peripheral edge of the lens body 22. Yes. Side surfaces 24a and 26a on the same side of the protrusions 24 and 26 constitute first and second supported surfaces. The supported surfaces 24 a and 26 a are configured on a first plane 30 that passes through the optical axis 28.
[0019]
A support portion 34 having a groove 32 having a predetermined width is formed in a fixed portion of the optical head. The support portion 34 is made of metal die casting or the like. The upper surfaces 34a and 34b of the support portion 34 constitute first and second support surfaces at positions on both sides of the opening end of the groove 32. The supported body 20 is inserted into the groove 32, and the first and second supported surfaces 24a and 26a are brought into contact with the first and second support surfaces 34a and 34b, respectively, and are supported by the support portion 34. Yes. The width W of the groove 32 is substantially the same as or slightly larger than the diameter L of the supported body 20. The optical axis 28 of the lens body 22 coincides with a predetermined optical axis position in the optical head.
[0020]
The presser spring 36 is configured by a leaf spring, one end (not shown) is fixed to the support portion 34 with a screw or the like, and one surface near the other end 36a is the top of the outer peripheral surface 20a of the supported body 20 (the optical axis 28 is connected). And a position on the line of intersection between the outer surface 20a and a plane orthogonal to the first plane. As a result, the first and second supported surfaces 24a and 26a of the supported body 20 are fixed to the support portion 34 by pressing against the first and second support surfaces 34a and 34b.
[0021]
According to the above configuration, the contact surfaces of the first and second supported surfaces 24 a and 26 a and the first and second support surfaces 34 a and 34 b are on the first plane 30 passing through the optical axis 28. Therefore, even if the supported body 20 expands and contracts due to a temperature change, the position of the optical axis 28 in the direction perpendicular to the first plane 30 does not change. Further, since the width direction of the supported body 20 is regulated by the width W of the groove 32, the position of the optical axis 28 in the direction along the first plane 30 does not change.
[0022]
(Embodiment 2)
A second embodiment of the present invention is shown in FIG. The supported body 38 is entirely made of an integrally molded product of plastic. The supported body 38 includes a lens body 40 having a cylindrical outer shape and projecting portions 42, 44, 46, and 48. The protrusions 42 and 44 are parallel to the optical axis 50 at positions opposite to each other across the optical axis 50 of the lens body 40 at the same position in the optical axis (center axis) 50 direction. It is configured to extend. The side surfaces 42a and 44a on the same side of the protrusions 42 and 44 constitute first and second supported surfaces. The supported surfaces 42 a and 44 a are configured on a first plane 52 that passes through the optical axis 50.
[0023]
The protrusions 46 and 48 are at the same position in the direction of the optical axis 50 (the positions of the protrusions 42 and 44 are shifted in the direction of the optical axis 50 and in the circumferential direction). In a direction parallel to the optical axis 50 at positions opposite to each other with respect to each other. Side surfaces 46a, 48a on the same side of the protrusions 46, 48 constitute third and fourth supported surfaces. The supported surfaces 46 a and 48 a are configured on a second plane 54 that passes through the optical axis 50.
[0024]
A support portion 60 is formed in the fixed portion of the optical head. The support portion 60 is formed with grooves 56 and 58 having a predetermined width communicating with each other. The support part 60 is made of metal die casting or the like. The upper surfaces 60a and 60b of the support portion 60 form first and second support surfaces at positions on both sides of the opening end of the groove 56. The upper surfaces 60c and 60d of the support portion 60 constitute third and fourth support surfaces at positions on both sides of the opening end of the groove 58.
[0025]
The supported body 20 is inserted into the grooves 56 and 58, and the first and second supported surfaces 58a and 58b are brought into contact with the first and second supported surfaces 60a and 60b, respectively. The supported surfaces 58c and 58d are in contact with the third and fourth support surfaces 60c and 60d, respectively, and are supported by the support portion 60. The widths W of the grooves 56 and 58 are formed to be slightly larger than the diameter L of the supported body 20. The optical axis 50 of the lens body 40 coincides with a predetermined optical axis position in the optical head.
[0026]
The presser spring 62 is configured by a leaf spring, one end (not shown) is fixed to the support portion 60 with a screw or the like, and one surface near the other end 62a is the top of the outer peripheral surface 38a of the supported body 38 (through the optical axis 50). In addition, it is in pressure contact with a position on the line of intersection between the plane passing through the middle between the first and second planes 52 and 54 and the outer peripheral surface 38a. As a result, the supported body 38 has the first and second supported surfaces 42a and 44a pressed against and in contact with the first and second supported surfaces 60a and 60b, and the third and fourth supported surfaces 46a and 48a. The third and fourth support surfaces 60 c and 60 d are pressed against and fixed to the support portion 60.
[0027]
According to the above configuration, the contact surfaces of the first and second supported surfaces 42 a and 44 a and the first and second support surfaces 60 a and 60 b are on the first plane 52 that passes through the optical axis 50. The abutting surfaces of the third and fourth supported surfaces 46 a and 48 a and the third and fourth supporting surfaces 60 c and 60 d are configured on a second plane 54 that passes through the optical axis 50. Therefore, even if the supported body 38 expands and contracts due to a temperature change, the optical axis 50 is prohibited from moving on a plane orthogonal to the optical axis 50, and its position does not change.
[0028]
(Embodiment 3)
A third embodiment of the present invention is shown in FIG. The supported body 64 is made entirely of a plastic integrally molded product. The supported body 64 includes a lens body 66 having a cylindrical outer shape, projecting portions 68 and 70, and a convex portion 72. The protrusions 68 and 70 are configured to extend in a direction parallel to the optical axis 74 at positions opposite to each other on the periphery of the lens main body 66 across the optical axis (center axis) 74 of the lens main body 66. Yes. Side surfaces 68a and 70a on the same side of the protrusions 68 and 70 constitute first and second supported surfaces. The supported surfaces 68 a and 70 a are configured on a first plane 76 that passes through the optical axis 74.
[0029]
The convex portion 72 has a constant width along a line of intersection between a plane 78 passing through the optical axis 74 and orthogonal to the first plane 76 and the lower surface of the outer peripheral surface 64a of the supported body 64, and from the lower surface of the outer peripheral surface 64a. It is configured to protrude downward.
[0030]
A support portion 82 having a groove 80 having a predetermined width is formed in the fixed portion of the optical head. The support portion 82 is made of metal die casting or the like. The upper surfaces 82a and 82b of the support portion 82 constitute first and second support surfaces at positions on both sides of the opening end of the groove 80. The supported body 64 is inserted into the groove 80 and supported by the support portion 82 with the first and second supported surfaces 68a and 70a abutting against the first and second supported surfaces 82a and 82b, respectively. Yes. The width W of the groove 80 is formed to be slightly larger than the diameter L of the supported body 64. The optical axis 74 of the lens body 22 coincides with a predetermined optical axis position in the optical head. A concave portion 84 is formed at the bottom of the groove 80 along the position where the convex portion 72 of the supported body 64 is accommodated. The width w1 of the concave portion 84 is formed slightly larger than the width w2 of the convex portion 72, and the concave portion 84 and the convex portion 72 are disposed so as to be relatively movable in the vertical direction (direction perpendicular to the first plane 76). .
[0031]
The presser spring 86 is configured by a plate spring, one end (not shown) is fixed to the support portion 82 with a screw or the like, and one surface near the other end 86a is the top of the outer peripheral surface 64a of the supported body 64 (the flat surface 78 and the outer peripheral surface). 64a (position on the line of intersection with 64a). Accordingly, the first and second supported surfaces 68a and 70a of the supported body 64 are fixed to the support portion 82 by pressing and contacting the first and second supported surfaces 82a and 82b. At this time, the convex portion 72 on the lower surface of the supported body 64 is accommodated in the concave portion 84 of the support portion 82 so as to be movable in the vertical direction (almost immovable in the horizontal direction).
[0032]
According to the above configuration, the contact surfaces of the first and second supported surfaces 68 a and 70 a and the first and second support surfaces 82 a and 82 b are on the first plane 76 that passes through the optical axis 74. Thus, even if the supported body 64 expands and contracts due to a temperature change, the position of the optical axis 74 in the direction perpendicular to the first plane 76 does not change. Further, due to the fitting structure of the convex portion 72 and the concave portion, the position in the direction along the first plane 76 of the optical axis 74 does not change. Contrary to the above, a concave portion can be formed on the supported body 64 side, and a convex portion can be formed on the support portion 82 side.
[0033]
(Embodiment 4)
A fourth embodiment of the present invention is shown in FIG. The supported body 88 is entirely made of an integrally molded product of plastic. The supported body 88 includes a lens body 90 having a cylindrical outer shape and projecting portions 92, 94, and 96. The protrusions 92 and 94 are configured to extend in the direction parallel to the optical axis 98 at positions opposite to each other across the optical axis (center axis) 98 of the lens body 90 on the periphery of the lens body 90. Yes. The side surfaces 92a and 94a on the same side of the protruding portions 92 and 94 constitute first and second supported surfaces. The supported surfaces 92 a and 94 a are configured on a first plane 100 that passes through the optical axis 98.
[0034]
The protruding portion 96 is configured to extend in the direction parallel to the optical axis 98 on the lower surface of the support 88. One side surface 96a of the projecting portion 96 constitutes a third supported surface. The supported surface 96 a is configured on a second plane 102 that passes through the optical axis 98 and is orthogonal to the first plane 100.
[0035]
A support portion 106 having a groove 104 having a predetermined width is formed in a fixed portion of the optical head. The support part 106 is made of metal die casting or the like. The upper surfaces 106a and 106b of the support portion 106 constitute first and second support surfaces at positions on both sides of the opening end of the groove 104. Further, a step is formed at the center in the width direction of the bottom surface in the groove 104, and the step is configured as a third support surface 106c perpendicular to the first and second support surfaces 106a and 106b.
[0036]
The supported body 88 is inserted into the groove 104, and the first, second, and third supported surfaces 92a, 94a, and 96a are respectively contacted with the first, second, and third support surfaces 106a, 106b, and 106c. It is contacted and supported by the support portion 106. The width W of the groove 104 is formed to be slightly larger than the diameter L of the supported body 88. The depth D1 of the shallow portion of the groove 104 is formed to be slightly larger than the diameter L of the supported body 88, and the depth D2 of the deep portion is an appropriate gap between the lower end portion of the projecting portion 96 and the bottom surface of the groove 104. It is formed in the size which is formed. The optical axis 98 of the lens body 90 coincides with a predetermined optical axis position in the optical head.
[0037]
The presser spring 108 is configured by a leaf spring, one end (not shown) is fixed to the support portion 106 with a screw or the like, and one surface in the vicinity of the other end 108a is inclined at an angle of 45 ° with respect to the outer peripheral surface 88a of the supported body 88 ( It is in pressure contact with a plane passing through the optical axis 98 and passing through the middle between the first and second planes 100 and 102 and the outer peripheral surface 88a. As a result, the supported body 88 is fixed to the support portion 106 with the first, second, and third supported surfaces 92a, 94a, and 96a pressed against the first and second support surfaces 106a, 106b, and 106c. The
[0038]
According to the above configuration, the contact surfaces of the first and second supported surfaces 92a and 94a and the first and second support surfaces 106a and 106b are on the first plane 100 passing through the optical axis 98. Therefore, even if the supported body 88 expands and contracts due to a temperature change, the position of the optical axis 98 in the direction perpendicular to the first plane 100 does not change. In addition, the contact surface between the third supported surface 96a and the third support surface 106c is formed on the second plane 102 that passes through the optical axis 98 and is orthogonal to the first plane 100, so that the light The position of the axis 98 in the direction along the first plane 100 does not change.
[0039]
In addition, in each said embodiment, although one presser spring was used, a presser spring can also be separately arrange | positioned for every direction to press. In each of the above embodiments, the supported body is formed by integrally molding the lens body, the projecting portion, and the projecting portion. However, it may be configured as a separate body that is assembled and integrated. The supported body or the lens body of the present invention can be made of glass as well as plastic.
[Brief description of the drawings]
1A and 1B are views showing a first embodiment of the present invention, in which FIG. 1A is a view as seen from the optical axis direction, and FIG. 1B is a view taken in the direction of arrow A in FIG.
FIG. 2 is a diagram showing a conventional support structure as viewed from the optical axis direction.
FIGS. 3A and 3B are diagrams showing a second embodiment of the present invention, where FIG. 3A is a view as seen from the optical axis direction, and FIGS. 3B and 3C are views taken along arrows B and C in FIG. is there.
FIGS. 4A and 4B are diagrams showing a third embodiment of the present invention, in which FIG. 4A is a view as seen from the optical axis direction, and FIG. 4B is a view taken along arrow D in FIG.
FIGS. 5A and 5B are diagrams showing a fourth embodiment of the present invention, where FIG. 5A is a view as seen from the optical axis direction, and FIG. 5B is a view taken along arrow E in FIG.
[Explanation of symbols]
20, 38, 64, 88 ... supported body, 22, 40, 66, 90 ... lens body, 24, 26, 42, 44, 46, 48, 68, 70, 92, 94, 96 ... projection, 24a, 42a, 68a, 92a ... first supported surface, 26a, 44a, 70a, 94a ... second supported surface, 28, 50, 74, 98 ... optical axis of lens body, 30, 52, 76, 100 ... 1st plane, 34, 60, 82, 106 ... support part, 34a, 60a, 82a, 106a ... 1st support surface, 34b, 60b, 82b, 106b ... 2nd support surface, 36, 62, 86, 108 ... Presser spring (elastic member), 46a, 96a ... third supported surface, 48a ... fourth supported surface, 60c, 106c ... third supporting surface, 60d ... fourth supporting surface, 54, 102 ... 2nd plane, 72 ... convex part, 84 ... concave part.

Claims (6)

A structure in which a supported body in which a lens body is fixedly arranged is supported by a support portion of an optical head body and the supported body is supported at a predetermined optical axis position of the optical head,
The supported body has first and second supported surfaces at positions opposite to each other across the optical axis of the lens body at the periphery of the lens body;
The support portion includes first and second support surfaces that contact and support the first and second supported surfaces of the supported body;
An elastic force by an elastic member is interposed between the supported body and the support portion, and the first and second supported surfaces are pressed against the first and second support surfaces, respectively, The supported body is supported by the support part,
A lens support structure for an optical head, wherein the first and second supported surfaces are configured on a first plane passing through an optical axis of the lens body. The supported body further has third and fourth supported surfaces at positions opposite to each other across the optical axis of the lens body at the periphery of the lens body;
The support portion further includes third and fourth support surfaces that contact and support the third and fourth supported surfaces;
The third and fourth supported surfaces are changed to the third and fourth support surfaces by an elastic force by the elastic members or by an elastic force by an elastic member separately interposed between the supported body and the support portion. Each pressing and abutting, supporting the supported body on the support part,
The lens support structure for an optical head according to claim 1, wherein the third and fourth supported surfaces are configured on a second plane passing through the optical axis of the lens body. The supported body further has a third supported surface at the periphery of the lens body;
The support portion further includes a third support surface that abuts and supports the third supported surface;
The third supported surface is pressed against the third support surface by the elastic force of the elastic member or the elastic force of the elastic member separately interposed between the supported body and the support part, The support is supported by the support part,
The lens support structure for an optical head according to claim 1, wherein the third supported surface is configured on a second plane that passes through the optical axis of the lens body and is orthogonal to the first plane. A fitting structure of a convex part and a concave part is formed on the opposed surface of the supported body and the support part in a direction passing through the optical axis of the lens body and orthogonal to the first plane, and the lens is formed by the fitting structure. 2. The lens support structure for an optical head according to claim 1, wherein the movement of the optical axis of the main body in the direction along the first plane is locked. The said support body is comprised by integral molding of plastic, and each said support surface is comprised on the one side of the protrusion part comprised by protruding outward from the peripheral part of the said lens main body. A lens support structure for an optical head according to any one of the above. 6. The elastic member is constituted by a leaf spring in which one end is supported by a fixed portion of an optical head and the other end is pressed and brought into contact with an outer peripheral surface of the supported body to generate the elastic force. A lens support structure for an optical head according to any one of the above.

Images