JP4551646B2 - Plastic lens and optical pickup device - Google Patents

Description

  The present invention relates to a plastic lens used for an optical element such as a camera or an optical disk device, and an optical pickup device equipped with the plastic lens.

  In recent years, optical disk apparatuses that record and reproduce various information on optical recording media such as digital cameras, CDs, and DVDs have become widespread. For example, the optical disc apparatus includes an optical pickup device that reads information recorded on an optical recording medium. The optical pickup device includes a pickup lens for condensing light from a light source onto an optical recording medium.

  The pickup lens is generally manufactured by molding a plastic such as polyolefin resin or acrylic resin, or glass. A plastic pickup lens is manufactured by injection molding or transfer molding using a molding die. For example, in injection molding, a pickup lens is manufactured by pouring a resin from a gate into a cavity in a mold and cooling the resin.

  On the other hand, this type of plastic lens is mass-produced in order to lower the product unit price. Therefore, a plurality of lenses are manufactured simultaneously using a molding die having a plurality of cavities. For example, a molding die having eight cavities is used, and eight lenses are manufactured at the same time. In this case, it is desirable that lenses having the same quality are manufactured in the respective cavities, but in reality, variations in quality may occur. In addition, there may be variations in manufacturing quality for each molding die and each molding machine.

  The technique for marking plastic lenses is disclosed in, for example, Patent Document 1, but in this example, a coating film that becomes a marking by printing, coating or vapor deposition is provided on one side of the ribs to distinguish the lens surface. It is provided. Therefore, since the lens and the marking are not the same material, in this method, when the lens is formed by injection molding, it is necessary to provide a marking forming step separately from the molding.

  On the other hand, the technique disclosed in Patent Document 2 is provided with a convex or concave portion on the flange surface to indicate the injection position of the resin. However, there is no description about the manufacturing method and the molding die. Since it is on the upper surface of the flange surface, the marking is likely to be scraped or soiled when placed on a desk or due to handling, etc., and the marking information may not be transmitted well.

  The marking disclosed in Patent Document 2 is for gate alignment, and is not for identifying a lens or managing history in the production process. This is obvious from the fact that the markings disclosed in the document are provided only in one place and individual lenses cannot be identified among a plurality of lenses.

Further, the convex marking in the configuration example shown in FIG. 5 of Patent Document 2 protrudes by 0.1 to 0.5 mm from the upper end of the flange surface. Therefore, the stability when the side with the convex portion is placed is inferior, and the convex marking may be scraped in contact with other members and the marking may disappear. Since foreign matter accumulates in the concave shape of such a size provided at the upper end of the flange and the visibility becomes poor, a structure in which the marking itself can be visually recognized separately from the flange surface and is not in contact with other members is desired.
JP 2002-122711 A JP 2000-111709 A

  As described above, in the method of manufacturing a lens using a molding die, there may be variations in quality for each molding die or cavity. Therefore, for quality control, manufacturing control, and management of the history of the lens after being incorporated into an optical device, marking for easily identifying a manufacturing jig such as a molding die or a cavity or a manufacturing line on the lens itself. It is desirable to apply. However, the lens is an optical component, and the marking cannot be formed in such a manner as to reduce the performance required for the optical component. For example, an optical function part is formed at the center of the lens. However, it is not preferable to apply this optical function part to the optical function because it impedes the optical function.

  Further, when the marking is damaged by sliding with other members, it is difficult to visually recognize the marking itself, and the damaged portion adheres to the optical function portion, resulting in deterioration of optical performance.

  The present invention has been made to solve such a problem, and an object thereof is to provide a lens and an optical pickup device in which marking is performed in an optimum manner.

Lens according to the present invention is a plastic lens obtained by injection molding a resin material, comprises a flange portion on the outer periphery of the lens portion with two lens surfaces, at least one surface of the two lens surfaces, flange surface of the flange portion has a projecting surface formed higher than the optically functional section of the lens surface, the marking surface formed at a position lower than the projecting surface, injection together before Kemah Kingu surface A molded convex marking is provided , and the upper end of the marking is lower than the protruding surface of the flange surface.

  Here, it is desirable to have a notch on the outer peripheral side surface of the flange portion.

Moreover, it is preferable that the area | region vicinity in which the marking of the said marking surface was formed is a mirror surface.

Furthermore, it is preferable that the convex marking has a hemispherical protruding shape.

Furthermore, the marking is preferably a marking for identifying a mold / cavity used for manufacturing the lens.

Moreover, it is preferable that a plurality of the convex markings are provided.
In this case, it is preferable to include a plurality of convex markings having different shapes.

The plurality of convex markings are preferably convex markings indicating gate positions or convex markings for mold / cavity identification.

Furthermore, it is preferable that the plurality of convex markings consist of a combination of two parallel convex markings and a single convex marking.

Furthermore, it is preferable that the level difference between the flange surface and the marking surface is less than 100 μm in the optical axis direction.

Moreover, it is preferable that 2 <W / M <10 is satisfied, where M is the width of the bottom of the convex marking and W is the width of the marking surface.

Furthermore, it is preferable that the boundary between the flange surface on which the marking of the flange portion is provided and the lens surface is located inside the boundary between the other flange surface and the lens surface.

  ADVANTAGE OF THE INVENTION According to this invention, the lens and optical pick-up apparatus to which marking was given in the optimal aspect can be provided.

Embodiment 1 of the Invention
The lens according to the first embodiment of the invention will be described with reference to FIGS. 1 and 2, taking a pickup lens as an example.

  FIG. 1A is a top view of the lens. FIG.1 (b) is a side view of a lens, and the left half has shown the cross section. As shown in the figure, a flange portion 2 is formed on the outer periphery of the lens 1. The flange portion 2 is provided with a flange surface 21 on the optical recording medium side when the lens 1 is attached to the optical disc apparatus and information is read from the optical recording medium. Hereinafter, for the sake of explanation, the optical recording medium side will be described as the upper side 21 and the opposite side will be described as the lower side 23. The flange part 2 is located in the outer periphery of the optical function part of the lens 1, and is formed in the strip | belt shape over the perimeter. In addition, the flange part 2 does not need to be continuous on the outer periphery, and may have a shape having a notch portion on a part of the outer periphery.

  As shown in FIG. 1B, when viewed from the optical axis direction, the flange surface 21 is formed with a portion that is higher than the upper surface of the optical function portion. Therefore, even when the lens 1 is placed on a desk or the like with the flange surface 21 side down during work, the flange surface 21 contacts the desk and the optical function unit does not contact the desk. Therefore, damage due to contact of the optical function unit with a desk or the like can be avoided. Further, it is possible to avoid damage caused by the optical recording medium coming into direct contact with the optical function unit after the lens 1 is attached to the optical disc apparatus.

  The lens according to this example (including the flange portion 2) has a diameter of 5.8 mm. And the width | variety of the up-down direction of the flange part 2 is 0.9 mm. The diameter of the lens according to another example is 3.8 mm.

  As shown in FIG. 1 (a), a stepped portion 20 is provided on the upper surface of the flange surface 21, and, for example, a molding die, a cavity, and a manufacturing jig such as an injection molding apparatus are provided in that portion. Marking 3a, 3b for identification is provided in two places. The markings 3 a and 3 b are provided so as not to protrude from the uppermost surface of the flange surface 21. The markings 3a and 3b are formed integrally by providing shapes corresponding to the markings 3a and 3b in the mold portion facing the upper surface of the flange surface 21 during molding. The reason why the markings 3a and 3b are provided at two locations is to make it possible to identify different lenses such as a manufacturing jig by making their relative positions different. For example, when a cavity is identified by marking, the marking is provided at a different relative position for each cavity. For example, in the case of the first cavity, the marking is arranged at a position where the angle formed by the line connecting the center of the lens and the position of each marking is 180 degrees. In the case of the second cavity, the markings are arranged at different positions in the circumferential direction so as to be 120 degrees.

  The markings 3a and 3b are convex bodies having a shape such that a hemisphere protrudes. The concave body also functions as a marking, but the convex body is preferable because the mold can be easily manufactured. The height of the markings 3a and 3b according to this example is 0.02 to 0.03 mm. Thus, if marking 3a, 3b is made hemispherical shape, there exists an advantage that manufacture using a metal mold | die is easy. The shape of the marking 3 itself may not be hemispherical, but may be other shapes such as a square shape or a cross shape, or may be a letter such as an alphabet or a number. In this example, the marking 3a and the marking 3b have the same shape, but may have different shapes. Three or more markings 3 may be provided. Further, if the markings have different shapes in units to be identified such as each cavity, the number may be one. Further, when a marking indicating the gate position is present on the lens, it can be identified by the relative position between the marking indicating the gate position and the marking 3. Furthermore, a marking that can identify each of the mold and the cavity may be provided on one lens. For example, the marking for identifying the mold is two parallel convex portions, and the marking for identifying the cavity is one convex portion, so that the two can be distinguished.

  FIG. 2 shows an enlarged cross-sectional view of the vicinity of the flange portion 2 of the lens 1. Here, when the marking 3 is attached to the surface of the horizontal flange surface 21 that is the highest in the optical axis direction, sliding contact with the installation location at the time of operation and contact with the optical recording medium when the lens 1 is mounted on the optical pickup device. Therefore, there is a possibility that the minute marking 3 is damaged and cannot be confirmed. In addition, the marking 3 may be scraped, which may cause a disadvantage that plastic dust is generated. Therefore, in order to eliminate such inconvenience, the flange surface has a stepped portion at least partially, and the marking 3 is configured such that its upper end is lower than the highest portion of the flange surface 21. In the embodiment of the present invention, the flange surface has a step portion in the circumferential direction, and the marking 3 on the step portion is configured such that its upper end is lower than the highest portion of the flange surface 21. . With such a configuration, the marking 3 does not protrude from the flange surface 21, and the possibility of damage due to sliding contact or the like can be reduced.

  Of the flange surface 21, particularly regarding the stepped portion provided with the marking 3 b, a surface 211 that is lower in the optical axis direction than the flange surface is referred to as a marking surface. The marking surface 211 is preferably less than 100 μm from the highest surface of the flange surface 21 and more preferably lower within a range of 50 μm in order to easily release the molded product from the mold. Further, the height of the marking surface may be higher or lower than the height of the lens surface.

The flange surface 21 including the marking surface 211 is mirror-finished by a corresponding mold polishing process. Since the region subjected to the mirror finish has a higher light reflectance than the region not subjected to the mirror finish, the difference in brightness between the marking 3 portion and the other portions is increased. Therefore, there is an advantage that the visibility of the marking 3 is improved. In addition, although the whole area | region of the flange surface 21 is good also as a mirror surface, the vicinity of the area | region in which marking was formed should just be a mirror surface. When marking is provided on the marking surface, the ratio M / W of the marking bottom width (M) to the marking surface width (W) is preferably 2 or more and 10 or less, more preferably 2.5 or more and 5 or less. .
It is preferable that the marking surface 211 is provided with the highest portion of the flange surface on the outer periphery of the marking surface 211 and does not extend to the outer periphery of the lens so that an adhesive or the like flows into the marking surface 211.

  From the viewpoint of preventing damage due to sliding contact, it is also conceivable to arrange the marking 3 not on the flange surface 21 but on a region other than the optical function part, for example, the outermost peripheral surface of the lens surface. However, in the case of such a configuration, there arises a problem that the marking 3 is difficult to see behind the flange portion 2. In order to obtain a large effective diameter, that is, a wider optical function portion, it is not preferable to provide the marking 3 on the lens surface. Therefore, in the embodiment of the present invention, the marking 3 is provided on the flange portion 2. In the embodiment of the present invention, since the marking 3 is provided on the flange surface 21, the marking 3 can be visually observed even when the lens 1 is mounted on the optical disc apparatus.

  In the embodiment of the present invention, as shown in FIG. 2, the upper and lower portions of the lens have a shape that does not match the minimum thickness. That is, the boundary Q between the flange surface 23 and the lens surface is located outside the boundary P between the flange surface 21 and the lens surface. By adopting such a shape, the marking surface having a sufficient width can be secured even when the thickness of the entire lens is reduced and thereby the thickness of the flange portion is also reduced.

Embodiment 2 of the Invention
The lens according to the second embodiment of the invention is different from the lens according to the first embodiment of the invention in the shape of the flange portion. Since the other points are the same as those of the first embodiment, the description thereof is omitted.

  FIG. 3 is an enlarged cross-sectional view of the flange portion of the lens according to the second embodiment of the invention. As shown in the figure, a concave portion is provided on the flange surface, and the bottom surface of the concave portion is used as a marking surface. The bottom surface of the recess is also a step portion that is lower than the high surface of the flange surface 21. The marking surface 211 extends to the inner peripheral portion of the flange portion, but a high surface of the flange surface 21 is formed on the inner peripheral side as in the outer peripheral side as shown in FIG. 3, and the marking surface 211 is sandwiched between the flange surfaces 21. In this case, the two flange surfaces 21 do not have to have the same height.

  The flange surface 21 is preferably perpendicular to the optical axis direction, but may be an inclined surface.

  Here, a method for manufacturing a lens having the above-described structure by injection molding will be briefly described.

  First, a mold is created. The mold has a shape corresponding to the shape of the molded product. In particular, the mold used in the embodiment of the present invention has such a shape that a marking is formed on the flange surface 21.

  Next, a mold is mounted on the injection molding machine. Thereafter, in an injection molding machine, resin is poured from the gate into the cavity in the mold. Then, the lens is manufactured by cooling the resin poured into the cavity.

  As described above, the lens according to the embodiment of the present invention is provided with markings for identifying a manufacturing jig such as a cavity number and a mold number in an optimal manner. The same effect as the form can be obtained.

Embodiment 3 of the Invention
The lens according to the third embodiment of the invention differs from the lens according to the first embodiment in the marking position. Since the other points are the same as those of the first embodiment, the description thereof is omitted.

  FIG. 4 is an enlarged cross-sectional view of the flange portion of the lens according to the third embodiment of the invention. As shown in the figure, the marking 3 b is a convex portion protruding in a hemispherical shape and provided on the flange surface 21. The marking 3b is formed such that its upper end is lower than the highest surface of the flange surface 21. In the lens according to the third embodiment of the present invention, the step portion 20 is provided in the outer region of the flange surface 21.

  As described above, the lens according to the third embodiment of the present invention is provided with markings for identifying manufacturing jigs such as cavities and molding dies in an optimal manner. The same effect can be obtained.

Embodiment 4 of the Invention
The lens according to the fourth embodiment of the invention differs from the lens according to the first embodiment of the invention in the shape of the outer peripheral side surface of the flange portion. Since the other points are the same as those of the first embodiment, the description thereof is omitted.

  FIG. 5 is an enlarged cross-sectional view of the flange portion of the lens according to the fourth embodiment of the invention, and particularly shows a state in which the lens is fixed to the pickup holder of the optical pickup device. As shown in the figure, a notch 221 is formed on the outer peripheral side surface of the flange portion 2 of the lens. The notch portion 221 is formed so as to cut out a part of the upper end of the outer peripheral side surface of the flange portion 2. The notch portion 221 is provided over the entire circumference of the flange portion 2, but does not necessarily have to be the entire circumference.

  The pickup holder 4 has a shape that comes into contact with the flange lower portion 23 and the flange side portion 22. Specifically, it has a mounting portion 41 on which the flange lower portion 23 is mounted, and a convex portion 42 protruding upward on the outside of the mounting portion 41.

The bottom of the notch 221 is formed so as to be substantially the same height as the top of the convex portion 42 of the pickup holder 4. That is, the height H of the convex portion 42 is formed to be substantially the same as the distance from the flange lower portion 23 at the bottom of the notch 221.

  When the lens 1 is fixed to the pickup holder 4, it is common to use an adhesive. However, by providing the notch 221 as described above, the notch 221 becomes a pool of adhesive. Function as. Therefore, it is possible to prevent the adhesive from flowing into the area where the marking 3b is provided and erasing the marking 3b.

Embodiment 5 of the Invention
The lens according to the fifth embodiment of the invention has the same shape as the lens according to the first embodiment of the invention, and a part of the mold is nested in the manufacturing process. Since the other points are the same as those of the first embodiment, the description thereof is omitted.

FIG. 6 is a side view of a lens according to a fifth embodiment of the invention, and also shows nestings 51 and 52. As shown in the figure, dies 51 and 52 are used as molds for forming a portion including the optical function portion of the lens 1. The molds for the other flange portions 2 are formed by molds 53 and 54 that are separate from the inserts 51 and 52. It should be noted that the surface on which no marking is provided may be an integrated type in which the mold 54 and the insert 52 are integrated without using the insert 52.
As can be seen from the description, the optical function unit means the diameter of the light beam that actually passes through the lens, and the diameter varies depending on the application. For example, NA is 0.45 for CD, NA is 0.60 for DVD, and NA is 0.85 for Blu-ray, which is located on the inner peripheral side from the lens surface diameter.

  The division | segmentation location of the nests 51 and 52 and other parts should just be between the outermost periphery of the optical function part of a lens, and the innermost periphery of a marking surface. More preferably, it is desirable that the nest portions 51 and 52 and other portions are divided at the innermost peripheral portion of the flange portion 2. The first reason is that even when burrs that are sharp protrusions occur when the resin hardens at the boundary between the nestings 51 and 52 and other parts, the burrs exceed the stepped portion provided separately. This is because there is no problem if it does not. Secondly, if the nesting portions 51 and 52 and other portions are divided at the thin portion at the boundary between the flange surface 21 and the lens surface, it is difficult to mirror the flange surface 21.

  A portion that functions as a marking is provided in a portion of the separate mold 53 that faces the upper surface 21 of the flange portion, and this portion is formed into the marking 3b on the flange surface by injection molding.

  In this way, the reason why the portion corresponding to the optical function portion is mainly set as the nest 51 is that the marking provided on the upper surface of the flange is also integrally formed. This is because it is desirable to appropriately rotate the nesting part of the optical function part only around the optical axis without moving the nesting part of the flange part for marking the cavity number as a marking. As in the case where the optical function part is molded with a single mold, it is not necessary to provide a part functioning as a marking on the flange part each time in another integral mold.

For example, if the lens manufactured once with the nesting portion installed at a predetermined position is not good, the lens is rotated and manufactured again, and the nesting position is adjusted until the performance is improved.
In the present embodiment, the mold member that forms other than the optical function unit may be two or more members.

  In the present invention, the marking is provided not on the optical function part but on the other part, but this is particularly suitable for the manufacturing method in the case where the part corresponding to the optical function part is the nest 51. That is, when processing into a shape in which the marking is formed at a position corresponding to the marking of the mold, the mold 53 to be processed is a separate body from the nest 51 forming the optical function part, This is because the possibility of damaging the nest 51 can be reduced.

Embodiment 6 of the Invention
The sixth embodiment of the present invention relates to an optical pickup device equipped with the lens according to the first to seventh embodiments of the present invention.

  FIG. 7 shows a configuration of an optical pickup device 100 in which the lens 1 is mounted. The lens 1 is fixed at four points by a pickup holder 4. In particular, the flange portion 2 of the lens 1 and the pickup holder 4 are fixed with an adhesive.

  Thus, in a state where the lens 1 is mounted on the optical pickup device 100, the marking provided on the flange portion 2 can be observed visually or with a magnifying glass. For a lens having a predetermined defect, it is possible to manage the history of manufacturing jigs, molds, manufacturing lines, manufacturing locations, producers, etc. using the marking as a clue.

Other embodiments.
As the shape of the lens of the present invention, for example, it can be used for a meniscus-shaped lens in which one surface is convex and the other surface side is concave.

It is a figure which shows the upper side figure and side view of the lens concerning this invention. It is an expanded sectional view of the flange part of the lens concerning the present invention. It is an expanded sectional view of the flange part of the lens concerning the present invention. It is an expanded sectional view of the flange part of the lens concerning the present invention. It is an expanded sectional view of the flange part of the lens concerning the present invention. It is sectional drawing which shows the mode of manufacture of the lens concerning this invention. It is a figure which shows the optical pick-up apparatus concerning this invention.

Explanation of symbols

1 Lens 2 Flange 3 Marking 4 Pickup Holder 100 Optical Pickup Device

Claims (24)

A plastic objective lens for an optical pickup obtained by injection molding a resin material,
A flange portion is provided on the outer periphery of the lens portion having two lens surfaces,
The plastic objective lens is bonded to the pickup holder and an adhesive at the flange side portion of the flange portion,
Flange surface of the optical recording medium side of the flange portion, said a projecting surface higher formed from optically functional section of the lens surface of the optical recording medium side, is formed lower than the projected surface position, and inside the said projecting surface Having a marking surface located at
The marking surface is provided with a convex marking integrally injection-molded,
A plastic objective lens for an optical pickup, wherein an upper end of the marking is lower than a protruding surface of the flange surface. 2. The plastic objective lens for an optical pickup according to claim 1, further comprising a notch on an outer peripheral side surface of the flange portion. The plastic objective lens for an optical pickup according to claim 1 or 2, wherein the vicinity of a region where the marking on the marking surface is formed is a mirror surface. 4. The plastic objective lens for an optical pickup according to claim 1, wherein the marking is a marking for identifying a mold and a cavity used for manufacturing the lens. 5. The plastic objective lens for an optical pickup according to claim 1, wherein an amount of a step between the flange surface and the marking surface is less than 100 μm in an optical axis direction. 6. The optical pickup plastic according to claim 1, wherein M is a bottom width of the convex marking and W is a width of the marking surface, wherein 2 <W / M <10 is satisfied. Objective lens. The said marking surface is provided with the 1st convex marking integrally injection-molded, and the 2nd convex marking different from the said 1st marking. Plastic objective lens. The plastic objective lens according to claim 7, wherein the first marking and the second marking show different information. The plastic objective lens according to claim 7 or 8, wherein the first marking and the second marking have different shapes. 9. The plastic objective lens according to claim 7, wherein the first marking is a plurality of parallel convex portions, and the second marking is one convex portion. 11. The plastic objective lens according to claim 7, wherein the second marking is a marking indicating predetermined information according to a relative positional relationship with the first marking. 11. The first marking is a marking indicating a gate position, and the second marking is a marking indicating predetermined information according to a relative positional relationship with the first marking. The plastic objective lens according to any one of 11. The plastic according to any one of claims 7 to 12, wherein the second marking is a marking for identifying a mold or a cavity by a relative positional relationship with the first marking. Objective lens. The plastic objective lens according to any one of claims 1 to 13, wherein the plastic objective lens is a Blu-ray optical pickup objective lens. The optical pick-up apparatus carrying the plastic objective lens as described in any one of Claims 1 thru | or 14. An optical pickup objective lens for plastic Blu-ray obtained by injection molding a resin material,
A flange portion is provided on the outer periphery of the lens portion having two lens surfaces,
The optical pickup objective lens for Blu-ray is bonded to the pickup holder and an adhesive at the flange side portion of the flange portion,
The flange surface of the flange portion on the optical recording medium side is formed with a projecting surface formed higher than the optical function portion of the lens surface on the optical recording medium side, and at a position lower than the projecting surface, and inside the projecting surface. Having a marking surface located at
The marking surface is provided with a convex marking integrally injection-molded,
An optical pickup objective lens for Blu-ray, wherein an upper end of the marking is lower than a protruding surface of the flange surface. 17. The optical pickup objective lens for Blu-ray according to claim 16, further comprising a cutout portion on an outer peripheral side surface of the flange portion. The marking surface is provided with a first convex marking integrally injection-molded and a second convex marking different from the first marking. The optical pickup objective lens for Blu-ray described. 19. The optical pickup objective lens for Blu-ray according to claim 18, wherein the first marking and the second marking show different information. 20. The optical pickup objective lens for Blu-ray according to claim 18, wherein the first marking and the second marking have different shapes. 20. The optical pickup objective lens for Blu-ray according to claim 18, wherein the first marking is a plurality of juxtaposed convex portions, and the second marking is one convex portion. The optical pickup for Blu-ray according to any one of claims 18 to 21, wherein the second marking is a marking indicating predetermined information according to a relative positional relationship with the first marking. Objective lens. 19. The marking according to claim 18, wherein the first marking is a marking indicating a gate position, and the second marking is a marking indicating predetermined information according to a relative positional relationship with the first marking. The optical pickup objective lens for Blu-ray according to any one of 22 items. The Blu-ray according to any one of claims 18 to 23, wherein the second marking is a marking for identifying a mold or a cavity based on a relative positional relationship with the first marking. Optical pickup objective lens.

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