JP5076618B2 - Glass lens for optical pickup device - Google Patents

Description

The present invention relates to a glass lens of the objective lens and the like incorporated in the optical pickup device.

Various optical pickup devices for reproducing and recording information on an optical information recording medium such as a CD (compact disc) and a DVD (digital versatile disc) have been developed and manufactured, and are widely used. “Reproduction / recording of information” means reproduction and / or recording of information. As an objective lens incorporated in such an optical pickup device, there is an objective lens made of, for example, a glass material or a resin material and provided with a mark indicating the direction of astigmatism on an outer diameter portion. (See Patent Document 1). This mark is formed by laser marking, inkjet, magic, or the like.
JP 2005-174380 A

The present invention aims at providing a glass lens that can be realized at low cost marking related aberrations.

In order to solve the above problems, a glass lens for an optical pickup device according to the present invention includes a main body portion having an optical surface, a support portion for supporting the main body portion from the periphery, and a three-dimensional index existing in the support portion. The body part, the support part, and the three-dimensional index are integrally formed, and the three-dimensional index is a reference for measuring aberration.
In the said glass lens, it has a three-dimensional parameter | index used as the reference | standard of the circumferential direction in a support part. In this case, when measuring the aberration of the glass lens, a three-dimensional index can be used as a reference, and workability can be improved.

According to a specific aspect or aspect of the present invention, the three-dimensional index is present on the upper surface of the support portion.

In another aspect of the present invention, the three-dimensional index is a notch groove having a marking line shape.

In still another aspect of the present invention, the support portion includes a mark member fixed in an arrangement associated with the directionality of aberration of the glass lens. As described above, in the glass lens, the mark member is fixed on the surface of the glass lens in an arrangement associated with the directionality of the aberration of the glass lens. This optical element can be assembled to a holder of an optical pickup device or the like while taking into consideration. At this time, using the mark member as a mark, the optical element is arranged and fixed so as to reduce the aberration of the glass lens, or the optical element is arranged so as to cancel out the aberration generated by other optical system parts in the optical pickup device.・ Can be fixed. Moreover, it can prevent that the optical function of an optical element is prevented by the mark member formed in the support part.

In still another aspect of the invention, the mark member is formed of an adhesive. Thus, in the said glass lens, the mark member is formed with the adhesive agent, The marking regarding an aberration can be implement | achieved cheaply without damage. Furthermore, desired cleaning can be performed on the optical element by forming the mark member with an adhesive. That is, the adhesive has higher durability against organic cleaning agents such as alcohol as compared with marks made by ink jet or magic. It can be cleaned with a cleaning agent, and there is no need to worry about unintentional removal of marks or contamination of surrounding optical surfaces. In addition, it is also possible to use a dispenser, which is an adhesive supply machine often used when bonding lenses or bonding lenses to a lens frame, without introducing expensive equipment for marking. In addition, the optical element can be manufactured at a low cost.

In still another aspect of the invention, the adhesive forming the mark member is any one of a UV adhesive, a thermosetting resin adhesive, and an epoxy resin adhesive. Thus, in the glass lens, the adhesive forming the mark member is any one of a UV adhesive, a thermosetting resin adhesive, and an epoxy resin adhesive. Since these adhesives are relatively easy to handle and extremely durable against the cleaning agent, the glass lens and the mark member can be handled as an integrated product after the mark member is fixed. Furthermore, since these adhesives can reduce curing shrinkage, the influence of the shrinkage on the lens shape can be reduced, and volatility can be reduced during and after curing.

In still another aspect of the invention, the mark member exhibits a directionality of at least one of coma and astigmatism.

In still another aspect of the invention, the mark member has a color different from that of the glass lens. In this case, it becomes easy to optically identify the mark member, and further, by forming the plurality of mark members with different colors, it is possible to distinguish the plurality of mark members and associate the aberration type and other matters with each other. .

In still another aspect of the invention, the mark member is at least one or more dome-shaped protrusions. In this case, it is easy to observe the mark member by the naked eye or image processing.

  Hereinafter, an embodiment of an optical element according to the present invention will be described with reference to the drawings. 1A is a perspective view illustrating the optical element of the present embodiment, FIG. 1B is a plan view of the optical element, and FIG. 1C is a side view of the optical element. FIG. 1D is a partially enlarged view of the optical element.

  The optical element 20 is an objective lens incorporated in the optical pickup device, and includes a glass lens 21 and a mark member 25. The glass lens 21 is an integral part formed of a glass material, and includes a main body portion 22 and a support portion 23. The mark member 25 is an integral part formed of an adhesive, and is fixed on the surface of the support portion 23 in an arrangement corresponding to the directionality of the aberration of the glass lens 21.

  In the glass lens 21, the main body portion 22 condenses as a spot the incident light beam emitted from the light source and incident and collimated, and the support portion 23 supports the main body portion 22 from the periphery. The main body portion 22 has a circular outline in plan view, and the support portion 23 has an annular outline in plan view. The main body portion 22 has a biconvex lens shape and has a pair of opposed optical surfaces 22a and 22b. When a parallel light beam is incident on one optical surface 22b, a convergent light beam that converges on a spot (not shown) is emitted from the other optical surface 22a. The glass lens 21 is formed by a glass mold method. That is, the main body portion 22 and the support portion 23 are an integral glass product, and for example, temperature adjustment, compression, slow cooling, etc., with a preform prepared in advance being sandwiched between appropriately heated molds. A pair of optical surfaces 22a and 22b is formed by performing the process. The periphery of the support portion 23 does not necessarily become a perfect circle immediately after molding, but has a substantially perfect side surface 23c after being centered by grinding or the like.

  The mark member 25 has a dome-like or hemispherical appearance, and is fixed to the upper surface (optical disc side surface) 23a of the support portion 23 in close contact with the lower end surface 25a. The mark member 25 is cured by attaching a droplet of uncured or uncured UV adhesive to an appropriate position on the upper surface 23a of the support portion 23 and irradiating the droplet with UV light. . The mark member 25 can be a protrusion having an arbitrary size as long as it is suitable for uses such as naked eye detection, microscopic observation, and image processing. For example, the diameter d of the mark member 25 is not particularly limited as long as it fits within the width of the support portion 23. Further, the height h of the mark member 25 is preferably lower than the height of the top of the optical surface 22a. However, even if it is higher than the height of the top of the optical surface 22a, the working element as the objective lens of the optical element 20 is used. There is no particular problem if the distance is not exceeded. The resin forming the mark member 25 may be transparent, but may be opaque, and may be colored including white, black, and chromatic colors. Since the glass lens 21 is generally colorless and transparent, the colored mark member 25 is suitable for visual observation, microscopic observation, image processing, and the like. When incorporating the optical element 20 into the optical pickup device, for example, the optical element 20 is appropriately rotated around the optical axis OA or the system optical axis so as to reduce the aberration of the glass lens 21 by using the mark member 25. For example, the optical element 20 is appropriately arranged around the optical axis OA so as to cancel the aberration generated by the other optical system part in the optical pickup device. Place and fix in the adjusted state after rotating.

  At one place on the upper surface 23a of the support portion 23, a notched groove 27 having a marking line shape is formed as a three-dimensional index. This notch groove 27 is transferred by a mold for glass mold, and is fixedly formed corresponding to the orientation of the mold. The notch groove 27 is used as a reference when measuring the aberration remaining in the main body portion 22 of the glass lens 21. That is, after the glass lens 21 is molded by the glass mold method, the aberration of the glass lens 21 is measured using an interferometer or the like at the stage where the support portion 23 is finished by grinding the peripheral portion. Aberrations include directional astigmatism, third-order coma aberration, and the like. For example, in the case of astigmatism, the direction in which the wavefront travels and the direction in which the wavefront lags exist in a direction perpendicular to the plane perpendicular to the optical axis OA. For example, the direction in which the wavefront travels is the astigmatism direction. In the case of third-order coma aberration, a direction with little wavefront delay or advance and a direction with much wavefront delay or advance exist in a direction perpendicular to the plane perpendicular to the optical axis OA. For example, the wavefront delay The direction with little advance is defined as the third coma aberration direction. Such a measurement result is recorded and stored as aberration information including, for example, an average wavefront aberration value and an aberration direction given as a clockwise angle with the notch groove 27 as a reference. Thereafter, the mark member 25 is formed on the support portion 23 of the glass lens 21 based on the aberration information as described above. In the case of FIG. 1B, the mark member 25 is arranged in the α ° direction clockwise with respect to the notch groove 27, and the astigmatism direction and the coma aberration direction are centered on the optical axis OA. It is present in 25 directions.

  When the glass lens 21 has both astigmatism and third-order coma, a plurality of mark members 25 and 125 can be formed on the support portion 23 of the glass lens 21 as shown in FIG. In this case, if there is a difference between the color of the mark member 25 corresponding to astigmatism and the color of the mark member 125 corresponding to third-order coma aberration, for example, when the optical element 20 is incorporated into the optical pickup device, the color is Using the mark member 25 corresponding to the point aberration, the optical element 20 can be arranged and fixed so as to cancel out aberrations generated by other optical system portions in the optical pickup device. For example, the optical element 20 can be arranged and fixed so as to reduce the aberration of the glass lens 21 by using the mark member 125 corresponding to the third-order coma aberration. When correction of astigmatism and third-order coma aberration does not match, it is possible to switch between astigmatism and third-order coma aberration according to the application.

  As shown in FIG. 3, the optical element 20 can be provided with a protector 29 made of, for example, an elastic resin in addition to the mark member 25. When the optical element 20 is an objective lens for an optical pickup, the optical surface 22a of the glass lens 21 is likely to be close to an optical disc that is an optical information recording medium, and in particular, an objective lens for Blu-ray Disc (also referred to as BD). Is high NA and there is a tendency that the working distance cannot be sufficiently obtained. Therefore, by providing the protector 29, the optical surface 22a of the optical element 20 and the like can be reliably protected. The height of the protector 29 is set higher than the height of the mark member 25.

  FIG. 4 is a plan view of an objective lens actuator in which the optical element 20 of FIG. 1 is assembled as an objective lens. The objective lens actuator 100 includes a lens movable portion 10 that functions as an objective lens unit, suspension wires 61 and 61 that support the lens movable portion 10, and a suspension holder 62 that supports the base side of the suspension wires 61 and 61. . Here, the lens movable unit 10 includes an optical element 20, a holder portion 40, and a magnetic circuit unit 51.

  In the lens movable part 10, the holder part 40 supports the support part 23 of the optical element 20 from the lower surface 23b side. The holder portion 40 is molded from a material such as a plastic material, and has an opening 41 in the upper surface portion 40a. The edge portion of the opening 41 supports the flange-shaped support portion 23 around the optical element 20. The support portion 23 is fixed to the edge portion of the opening 41 of the holder portion 40 with, for example, a UV curable adhesive. As a result, the optical element 20 is fixed in an aligned state with respect to the holder portion 40. Note that the shape of the opening 41 is designed so as not to interfere with the support of the support portion 23, does not interfere with the lower surface of the glass lens 21 of the optical element 20, and does not block incident light on the glass lens 21. It is also possible to provide a step or the like for simplifying the alignment of the optical element 20.

  The magnetic circuit unit 51 includes a focusing coil and a tracking coil that are fixed to the holder part 40 or integrated with the holder part 40, a magnet, a yoke (not shown), and the like. The holder portion 40 can be finely displaced at high speed in the focusing direction along the optical axis OA of the element 20 and in the AB direction which is a tracking direction perpendicular to the optical axis OA.

  In FIG. 4, the mark member 25 of the optical element 20 is disposed in the CD direction perpendicular to the AB direction with the optical axis OA as a reference. For example, the optical axis OA of the optical element 20 is made normal to the paper surface by inclining the upper surface portion 40a of the holder portion 40 or the edge portion of the opening 41 or finely adjusting the thickness of the adhesive for fixing the optical element 20. That is, the system lens can be tilted in the CD direction with respect to the system optical axis, and the glass lens 21 can be arranged to reduce the aberration. Alternatively, the rotational position of the optical element 20 around the system optical axis on the holder portion 40 can be arranged so as to cancel out aberrations generated by other optical system portions in the optical pickup device.

  In FIG. 1B, FIG. 4, etc., the mark member 25 of the optical element 20 has a circular outline in a plan view, but is a plate on which the shape of the discharge port of the dispenser is adjusted or an adhesive is applied. A mark member (not shown) having an arbitrary outline such as a quadrangle can be formed by pressing with. In this case, the plurality of mark members can be identified by their unique shapes without coloring the plurality of mark members.

  FIG. 5 is a diagram illustrating a manufacturing process of the optical element 20 of FIG. First, in the molding apparatus 81, a glass preform is supplied to a mold apparatus part composed of a plurality of molds, and temperature control, compression, and slow cooling are performed on the preform held in the mold of the mold apparatus part. Etc., and the glass lens 21 is obtained. That is, the glass lens 21 as an integrally molded product is manufactured by the glass mold method.

  Thereafter, in the centering device 82, the glass lens 21 is aligned and fixed, and the periphery of the support portion 23 of the glass lens 21 is ground. As a result, the side surface of the glass lens 21, that is, the side surface 23c of the support portion 23 is processed into a substantially perfect circle, facilitating fixing and alignment to the holder portion 40 of FIG. In addition, after the processing by the centering device 82, an antireflection coating or the like can be applied to the surface of the glass lens 21 by using a film forming device.

  Next, in the interferometer 83, the glass lens 21 is aligned and fixed, and the aberration of the main body portion 22 of the glass lens 21 is measured. At this time, various aberrations can be measured by analyzing the interference pattern. However, residual aberrations such as astigmatism and third-order and higher coma are directional aberrations, and the residual aberration is an allowable amount. Even so, it is desirable to place and fix the glass lens 21 on the holder portion 40 so that the influence of such residual aberration can be reduced and canceled if possible. For this reason, astigmatism, third-order coma, and the like are checked not only in magnitude but also in direction, and the magnitude and direction of these aberrations are recorded for each glass lens 21. At this time, the aberration direction, specifically, the astigmatism direction and the coma aberration direction are numerically converted into an angle or the like with reference to the notch groove 27 provided in the glass lens 21.

  Next, in the adhesive attaching device 84, an uncured UV adhesive droplet is attached to one place on the upper surface 23 a of the support portion 23 corresponding to the aberration direction of the glass lens 21 obtained by the interferometer 83. . The adhesive attaching device 84 is an automated device that is disposed adjacent to the interferometer 83, receives the measured glass lens 21 carried out from the interferometer 83, and receives aberration magnitude and aberration from the interferometer 83. Receive information about directions. Thereby, an uncured droplet of UV adhesive is attached to an appropriate position of the support portion 23 so as to form the mark member 25 corresponding to the aberration direction with the notch groove 27 provided in the glass lens 21 as a reference. Can do. At this time, by using a general-purpose dispenser for UV adhesive, it is possible to precisely attach droplets to necessary portions of the large and small glass lenses 21.

  Next, the temporary curing device 85 performs temporary curing on the uncured droplets of the UV adhesive adhered on the glass lens 21. The temporary curing device 85 irradiates the uncured UV adhesive droplets deposited on the glass lens 21 with, for example, ultraviolet rays for several seconds to cure the droplets on the support portion 23 of the glass lens 21. Alternatively, the viscosity is increased to facilitate handling of the optical element 20. The temporary curing device 85 can be provided adjacent to the adhesive attaching device 84 as a separate device, but can be integrated with the adhesive attaching device 84. That is, the dispenser for discharging the UV adhesive and the ultraviolet irradiation device for curing the UV adhesive can be incorporated into one device that operates continuously.

  Next, in the main curing device 86, main curing is performed on the droplets of the UV adhesive in a temporarily cured state attached on the glass lens 21. With the main curing device 86, the block UV adhesive on the glass lens 21 in a temporarily cured state is irradiated with ultraviolet rays for several hours or more, for example, to form the block UV adhesive on the support portion 23 of the glass lens 21. Is completely cured and fixed to the surface of the support portion 23 to complete the formation of the mark member 25. That is, the manufacture of the optical element 20 is completed. Thus, even if the glass lens 21 is subsequently cleaned, the mark member 25 is not removed, and the mark member 25 is not melted and the surface of the glass lens 21 is not contaminated. In this main curing device 86, it often takes time to cure the mark member 25, so it is desirable that a large number of optical elements 20 that have passed through the temporary curing device 85 are stocked and collectively processed by the main curing device 86.

  If the glass lens 21 has only an allowable directional aberration, the processing by the adhesive attaching device 84 is not performed. However, when other information such as identification information and characteristic information of the glass lens 21 is applied to the optical element 20 as the mark member 25, an adhesive application device 84, in order to form the mark member 25 corresponding to the information, The temporary curing device 85 and the main curing device 86 are operated.

  As is clear from the above description, in the optical element 20 of the above-described embodiment, the mark member 25 is fixed on the support portion 23 of the glass lens 21 in an arrangement associated with the directionality of the aberration of the glass lens 21. The optical element 20 can be assembled to the holder portion 40 in consideration of the direction of aberration of the glass lens 21, that is, the optical element 20. Therefore, using the mark member 25 as a mark, the optical element 20 is arranged and fixed so as to reduce the aberration of the glass lens 21, or the optical element 20 so as to cancel out the aberration generated by other optical system parts in the optical pickup device. Can be placed and fixed. Here, the mark member 25 is formed of a UV adhesive, and marking relating to aberration can be realized at low cost without damage. Further, by forming the mark member 25 with a UV adhesive, alcohol cleaning or the like can be performed on the optical element. Note that the UV adhesive, which is the material of the mark member 25, can generally reduce curing shrinkage and has low volatility during and after curing, and thus has an adverse effect on the optical element 20 such as distortion and contamination. There is nothing. In addition, when the UV adhesive is aerobic, it becomes easy to reliably cure the mark member 25.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and various modifications are possible. For example, the material of the mark member 25 is not limited to the UV adhesive, and thermosetting resin, epoxy resin, or the like can be used. When the mark member 25 is formed of thermosetting resin, a droplet of the thermosetting resin adhesive before curing is attached to an appropriate position of the support portion 23 of the glass lens 21 using a dispenser or the like, and a heater or the like is used. The resin droplet is heated together with the glass lens 21. Thereby, this resin droplet can be hardened and the mark member 25 made of a thermosetting resin fixed to an appropriate position of the support portion 23 can be obtained. Further, when the mark member 25 is formed of epoxy resin, a droplet of the epoxy resin adhesive before curing is attached to an appropriate position of the support portion 23 of the glass lens 21 using a dispenser or the like, and left for a necessary time. To cure. Thereby, the mark member 25 made of an epoxy resin fixed to an appropriate position of the support portion 23 can be obtained.

  In the above embodiment, the adhesive mark member 25 corresponding to the aberration direction is provided on the upper surface 23a of the support portion 23 of the glass lens 21, but the adhesive corresponding to the aberration direction is provided on the side surface 23c of the support portion 23. A mark member 25 made of a metal can also be provided.

  In the above embodiment, one mark member is fixed corresponding to the aberration. However, the aberration direction can be changed by changing the number of mark members such as fixing a plurality of mark members in the radial direction of the lens. It is also possible to express the magnitude of the aberration. In order to display the magnitude of aberration, the size of the mark member may be changed in addition to changing the number of mark members.

  In the above embodiment, the optical element 20 is fixed to the holder portion 40 as a single unit, but a plurality of optical elements 20 can be fixed in parallel on the holder portion 40.

  In the above embodiment, the optical element 20 is fixed to the holder part 40 as a single unit. However, the lens unit integrated by combining at least one optical element 20 and another optical element is fixed to the holder part 40. You can also. In this case, for example, as shown in FIG. 6, the lens unit includes a holder 228 for arranging and fixing the optical element 20 of the above embodiment and the other optical element 220 of the diffraction type along the optical axis OA. Is provided. In another example, for example, as shown in FIG. 7, the optical element 20 of the above embodiment is fixed on a holder portion 323 a obtained by expanding the flange 323 of the plastic lens 320, The optical element 20 of the above embodiment can be arranged in parallel in a direction perpendicular to the optical axis OA. At this time, if necessary, the rotational position of the optical element 20 around the optical axis OA can be adjusted, and the inclination angle between the optical axis of the main body portion 322 and the optical axis OA of the optical element 20 can be adjusted. can do.

  In addition, the optical element 20 of the above embodiment is used as an objective lens for an optical pickup, but is not limited to the objective lens, and when directional aberration occurs in various glass lenses used as a collimator lens or the like, One or more mark members 25 exhibiting the directionality of aberration with respect to these lenses can be provided.

  In manufacturing the optical element 20, it is not always necessary to form the notch groove 27. That is, after the glass lens 21 without the notch groove 27 is manufactured in the molding device 81 and the glass lens 21 is centered by the centering device 82, the aberration of the glass lens 21 is measured by the interferometer 83. At the same time, the UV adhesive may be attached with a dispenser at a corresponding position on the support portion 23 corresponding to the obtained aberration direction. In addition, measurement may be performed with a mark or index as a reference before performing aberration measurement.

  In the above embodiment, the mark member 25 uses a UV adhesive, a thermosetting resin adhesive, an epoxy resin adhesive, or the like. However, a hybrid type adhesive material in which various inorganic materials are added to these can also be used. .

(A)-(D) are the perspective view of the optical element of this embodiment, a top view, a side view, and a partial enlarged view. It is a top view explaining the 1st modification of the optical element of FIG. It is a top view explaining the 2nd modification of the optical element of FIG. It is a top view of the objective lens actuator which assembled | attached the optical element of FIG. 1 as an objective lens. It is a block diagram explaining the manufacturing process of the optical element of FIG. It is a side view explaining the example of a lens unit provided with the optical element of FIG. It is a side view explaining the example of another lens unit provided with the optical element of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Lens movable part, 20 ... Optical element, 21 ... Glass lens, 22 ... Main-body part, 22a, 22b ... Optical surface, 23 ... Support part, 23a ... Upper surface, 25 ... Mark member, 27 ... Notch groove, 29 DESCRIPTION OF SYMBOLS ... Protector 40 ... Holder part 41 ... Opening 51 ... Magnetic circuit part 61, 61 ... Suspension wire 81 ... Molding device 82 ... Centering device 83 ... Interferometer 84 ... Adhesive adhesion device 85 ... Temporary curing device, 86 ... Main curing device, 100 ... Objective lens actuator, OA ... Optical axis

Claims (9)

A glass lens for an optical pickup device ,
The glass lens has a main body part having an optical surface, a support part for supporting the main body part from the periphery, and a three-dimensional index existing in the support part,
The main body portion, the support portion, and the three-dimensional indicator are integrally formed,
The three-dimensional index is a reference for measuring aberration, and is a glass lens.   The glass lens according to claim 1, wherein the three-dimensional index is present on an upper surface of the support portion.   The glass lens according to claim 1 or 2, wherein the three-dimensional index is a notch groove having a marking line shape.   The glass lens according to any one of claims 1 to 3, wherein a mark member fixed in an arrangement associated with the directionality of aberration of the glass lens is present in the support portion. .   The glass lens according to claim 4, wherein the mark member is formed of an adhesive.   The adhesive forming the mark member includes a UV adhesive, a thermosetting resin adhesive, and an epoxy.
The glass lens according to claim 5, wherein the glass lens is any one of two resin adhesives.   The mark member exhibits directionality of at least one of coma and astigmatism.
The glass lens according to any one of claims 4 to 6.   The said mark member has a color different from the said glass lens, The glass lens as described in any one of Claims 4-7 characterized by the above-mentioned.   The glass lens according to any one of claims 4 to 8, wherein the mark member is at least one or more dome-shaped protrusions.

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