JP2004205823A - Optical element unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element unit such that a mark formed on a lower lens can be viewed even while a plurality optical elements are combined one over another. <P>SOLUTION: The optical element unit 10 is constituted by combining one over the other a plurality of optical elements 20 and 30 which are molded by injecting molten resin into metal mold cavities and has marks 40 and 50 showing with which of a plurality of metal mold cavities the optical elements are molded. At least part of an area A2 other than an optical surface on both top and reverse surfaces of the top optical element is made smooth so that the mark of the optical element arranged below the top optical element can be viewed from the top surface side of the optical element arranged at the top. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical element unit used for an optical pickup device that focuses a light beam on an information recording surface of an optical information recording medium.
[0002]
[Prior art]
In recent years, an objective lens of an optical pickup device used for recording / reproducing of an information recording medium such as an optical disk has a large numerical aperture due to a demand for storing a large amount of information.
If the numerical aperture is up to about 0.65, one aspherical lens can be manufactured by glass pressing or resin molding or a combination thereof, but if the numerical aperture exceeds this, one lens (single lens) It becomes difficult to form an objective lens with a lens), and an objective lens may be formed by combining two or more single lenses, that is, as a unit.
[0003]
FIG. 5 schematically shows the structure of a mold 100 for molding a lens. Four gates 102 are provided on a runner 101 which is a resin injection channel, and first to fourth gates are provided at the tip of each gate 102. Mold cavities 103 to 106 are provided.
FIG. 6 shows an internal structure of a mold cavity, which is provided on a substantially hemispherical lens forming portion 107 for forming an optical surface of a lens and on a peripheral edge of the lens forming portion 107 and does not contribute to an optical function. It is composed of a peripheral portion 108 that forms a portion other than the optical surface.
First to fourth mark forming recesses 109 to 112 slightly projecting upward are provided on the upper surface of the peripheral portion.
[0004]
Each of the mark forming recesses 109 to 112 is formed at a predetermined position with respect to each of the mold cavities 103 to 106. For example, with respect to the first mold cavity 103, at the peripheral portion 108. A first mark forming recess 109 is formed in the vicinity of the portion to be joined to the gate 102 (at 12 o'clock in FIG. 6).
For the second mold cavity 104, a second mark forming recess 110 is formed at a position (3 o'clock position in FIG. 6) that is a 90 ° rotation from a portion which is a peripheral edge portion 108 and is joined to the gate 102. Have been. Hereinafter, similarly, a third mark forming recess 111 is formed at the position of 6 o'clock in FIG. 6 with respect to the third mold cavity 105, and FIG. A fourth mark forming recess 112 is formed at 6 o'clock 9 o'clock.
[0005]
In the lens molding operation, first, a molten resin is injected into the runner 101 and introduced into each of the mold cavities 103 to 106 via the gate 102. Next, after the molten resin that has reached the lens forming portion 107 and the peripheral portion 108 of each of the mold cavities 103 to 106 is solidified, the solidified resin is taken out from the mold 100 and cut at the gate portion to cut the four lenses. It is molded at the same time.
[0006]
Here, in general, since each lens has a slight difference in optical function according to the manufactured mold cavity, when manufacturing an objective lens by combining two single lenses up and down, For example, in the case where the upper lens is manufactured in the first mold cavity 103, in order to obtain a good optical function, it is necessary to determine in advance which cavity is preferably used for the lower lens. Ask for it. The lens used as the lower lens is usually manufactured by another mold different from the mold 100 described above.
[0007]
Then, the operator can check the position of the convex shape (mark) formed by transferring the concave shape of each of the mark forming concave portions 109 to 112 formed on each lens and the cutting mark remaining at the time of gate cutting. Based on the position, the lens is recognized in which mold cavity it is molded, and the assembling operation of the upper and lower lenses that can obtain a good optical function is performed.
[0008]
In addition, a technique of forming a mark on the surface of two lenses arranged vertically and performing an assembling operation of the two lenses based on the mark is conventionally known (for example, see Patent Document 1).
[0009]
[Patent Document 1]
JP, 2002-71909, A
[Problems to be solved by the invention]
FIG. 7 shows an assembled state of the upper and lower two lenses 201 and 202 on which marks M1 and M2 are formed. Generally, portions other than the optical surface that does not contribute to the optical function of the lens (portions indicated by oblique lines in FIG. 7) have a rough surface, and light is diffused, so that light transmittance is low.
Accordingly, the worker cannot visually recognize the position of the mark M2 of the lower lens 202 when the two lenses 201 and 202 are arranged vertically and viewed from the upper surface side of the upper lens 201. There has been a problem that it is not possible to recognize whether or not the product is molded in the mold cavity.
[0011]
In addition, the invention disclosed in Patent Document 1 is based on a mark formed on the surface of two vertically arranged lenses, and a relative displacement of the two lenses in the optical axis direction or the direction orthogonal to the optical axis. Is detected and corrected to make the center positions of the two lenses coincide with each other on the optical axis, thereby manufacturing an objective lens having a good optical function. Therefore, it is difficult to apply the present invention to a technique for grasping the mark formation position of the lower lens when viewed from the upper surface side of the upper lens among the two lenses arranged vertically as described above.
[0012]
An object of the present invention is to provide an optical element unit in which a mark formed on a lower lens can be visually recognized even in a state in which a plurality of optical elements are vertically combined. It is.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 is formed by injecting a molten resin into a mold cavity and determining which mold cavity among a plurality of mold cavities is formed. An optical element unit configured by combining a plurality of optical elements provided with marks shown above and below,
The optical surface between the upper and lower surfaces of the uppermost optical element so that the mark of the optical element disposed below the uppermost optical element is visible from the upper surface side of the optical element disposed at the uppermost position. It is characterized in that at least a part of the other region is smoothed.
[0014]
According to the first aspect of the present invention, the uppermost optical element is arranged such that a mark of an optical element disposed below the uppermost optical element is visible from the upper surface side of the uppermost optical element. At least a part of a region other than the optical surface among the upper and lower surfaces of the element is smoothed.
Therefore, even when a plurality of optical elements are vertically combined, the operator can visually recognize the mark of the lower optical element from a region other than the upper optical surface of the uppermost optical element, and It is possible to recognize in which of the plurality of mold cavities the optical element is manufactured.
[0015]
The invention according to claim 2 is the optical element unit according to claim 1, wherein an annular zone around the optical axis of a region other than the optical surface between the upper and lower surfaces of the uppermost optical element. It is characterized by smoothing.
[0016]
According to the second aspect of the present invention, the same effects as those of the first aspect can be obtained, and the annular zone around the optical axis of a region other than the optical surface on the upper and lower surfaces of the uppermost optical element can be obtained. Make it smooth.
Therefore, in a process after combining a plurality of optical elements up and down, for example, when performing an adjustment operation for correcting astigmatism, coma aberration, and the like, the uppermost optical element is moved relative to the lower optical element. In some cases, the upper optical element is rotated relative to the lower optical element. The position can be visually recognized from the uppermost optical element side, and the workability of the adjustment operation can be improved.
[0017]
According to a third aspect of the present invention, there is provided the optical element unit according to the first or second aspect, wherein protection is provided on an upper surface of the uppermost optical element to prevent damage to an optical surface on an upper surface of the optical element. The member is disposed, and the mark of the optical element disposed below the uppermost optical element is visible from the upper surface of the uppermost optical element, where the protective member is not disposed. It is provided at a certain position.
[0018]
According to the third aspect of the present invention, the same effect as in the first or second aspect can be obtained, and even when the protective member is provided, the mark position of the lower optical element is shifted to the uppermost optical element side. Can be seen from
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of an optical element unit of the present invention will be described in order with reference to the drawings.
In the present embodiment, an objective lens unitized by vertically combining two optical elements (lenses) will be described as an optical element unit used in an optical pickup device.
[0020]
Both the upper and lower lenses (hereinafter, referred to as an “upper lens 20” and a “lower lens 30”) of the objective lens 10 shown in FIGS. 1 and 2 inject molten resin (lens raw material) into a mold, so-called injection. It is manufactured by molding.
The upper lens 20 has a substantially circular shape around the optical axis L and has an optical function area A1 (hereinafter, a surface on which the optical function area A1 is formed is referred to as an “optical surface” of the upper lens 20). ), And an annular peripheral area A2 centered on the optical axis L having no optical function and formed at a position covering the periphery of the optical function area A1.
The vertical position (height) of the peripheral region A2 on the upper surface of the upper lens 20 is formed so as to be slightly lower than the position of the upper surface of the optical function region A1, and goes upward from the inner peripheral portion of the upper surface of the peripheral region A2. The upper surface of the peripheral region A2 and the upper surface of the optical function region A1 are continuous with each other via the inclined surface 21 inclined.
[0021]
Similarly, the lower surface of the peripheral region A2 and the lower surface of the optical function region A1 are continuous via an inclined surface 22 that is inclined upward from the inner peripheral portion of the peripheral region A2 on the lower surface of the upper lens 20.
[0022]
In the present embodiment, a mark 40 indicating which mold cavity of the plurality of mold cavities the upper lens 20 is formed on is formed on the inclined surface 21 at the 9 o'clock position shown in FIG. Have been. Note that the method of forming the mark 40 is the same as the conventional method, and a description thereof will be omitted.
Although not shown, a trace of cutting when the upper lens 20 is cut from the gate portion is left at the position of 12 o'clock in FIG. 1 on the side surface of the peripheral region A2.
By reading the positional relationship between the cut mark formed on the upper lens 20 and the mark 40, an operator can recognize which mold cavity has formed the upper lens 20.
[0023]
In addition, portions other than the inclined surface 21 on the upper surface of the peripheral region A2 and portions other than the inclined surface 22 on the lower surface of the peripheral region A2 (portions indicated by oblique lines in FIGS. 1 and 2) are formed of smooth surfaces.
Here, the “smooth surface” refers to a peripheral region of the upper lens 20 in a state where the upper lens 20 and the lower lens 30 are vertically combined by suppressing irregular reflection of incident light and reflected light on the upper lens 20. A2 refers to a surface having a surface roughness such that the mark 50 formed on the lower lens 30 is visible from the upper surface side.
The work for smoothing the surface may be performed, for example, by polishing after the injection molding of the upper lens 20 is completed and the lens is removed from the mold cavity, or the inner surface of the mold cavity may be formed smoothly. By doing so, the inner surface shape of the mold cavity may be transferred to the upper lens 20 in the injection molding stage.
[0024]
Similarly to the upper lens 20, the lower lens 30 has a substantially circular shape around the optical axis L and has an optical function area B1 having an optical function (hereinafter, the surface on which the optical function area B1 is formed is a lower lens). 30), and a ring-shaped peripheral area B2 formed around the optical function area B1 and centered on the optical axis L having no optical function.
A convex portion 31 projecting upward (toward the upper lens 20) is formed in an outer peripheral portion of the peripheral region B2, and a concave portion 23 is formed in an outer peripheral portion of the peripheral region A2 of the upper lens 20. Then, by fitting the concave portion 23 to the convex portion 31, the movement of the upper lens 20 in the left-right direction is regulated, and the upper lens 20 is positioned in the left-right direction with respect to the lower lens 30. .
[0025]
In the present embodiment, the mark 50 indicating which mold cavity of the plurality of mold cavities the lower lens 30 is formed on is located at the 9 o'clock position shown in FIG. Is formed.
Although not shown, a trace of cutting when the lower lens 30 is cut from the gate portion is left on the side surface of the peripheral region B2 at the position of 12:00 in FIG.
[0026]
Here, as described above, the portion other than the inclined surface 21 on the upper surface of the peripheral region A2 of the upper lens 20 and the portion other than the inclined surface 22 on the lower surface of the peripheral region A2 are both formed as smooth surfaces. In a state where the lower lens 30 and the lower lens 30 are combined vertically, an operator can visually check where the mark 50 of the lower lens 30 is formed on the lower lens 30 from the upper surface side of the peripheral area A2 of the upper lens 20. Can be.
Then, based on the position of the mark 50 of the lower lens 30 read in this manner and the above-mentioned trace of cutting on the side surface of the lower lens 30, it is possible to recognize in which mold cavity the lower lens 30 has been molded.
Therefore, the worker can recognize in which cavity the upper lens 20 and the lower lens 30 are manufactured, respectively, at a stage after the upper lens 20 and the lower lens 30 are vertically combined.
[0027]
In a process after the upper lens 20 and the lower lens 30 are vertically combined, for example, astigmatism or coma aberration generated due to solidification of the molten resin in a state deviated from the optical axis L. There is a case where an adjustment operation for correcting the above is performed.
This adjustment is performed by fitting the concave portion 23 of the upper lens 20 to the convex portion 31 of the lower lens 30, and positioning the upper lens 20 in the left-right direction with the upper lens 20 positioned relative to the lower lens 30. Relative to the optical axis L.
[0028]
Here, in the present embodiment, as described above, portions other than the inclined surface 21 on the upper surface of the annular zone A2 of the upper lens 20 and portions other than the inclined surface 22 on the lower surface of the peripheral region A2 are smooth surfaces. Make up. Therefore, no matter how much the upper lens 20 is rotated with respect to the lower lens 30, the position of the mark 50 of the lower lens 30 can always be visually recognized from the upper lens 20 side. Can be improved.
[0029]
In the present embodiment, the portion other than the inclined surface 21 on the upper surface of the peripheral region A2 of the upper lens 20 and the portion other than the inclined surface 22 on the lower surface of the peripheral region A2 are configured as smooth surfaces. For example, as shown in FIG. 3, in a state where the upper lens 20 and the lower lens 30 are vertically combined, a portion other than the inclined surface 21 on the upper surface of the peripheral region A2 of the upper lens 20 and the inclined surface on the lower surface of the peripheral region A2. Only a region other than the region 22 and located above the mark 50 of the lower lens 30 (a region indicated by oblique lines in FIG. 3) may be constituted by a smooth surface.
In this case, when the upper lens 20 is rotated with respect to the lower lens 30, the range in which the position of the mark 50 of the lower lens 30 can be visually recognized from the upper lens 20 side is limited. Since the area for forming the surface can be reduced, the time and cost required for forming a smooth surface can be reduced.
[0030]
Further, as shown in FIG. 4, for example, when the objective lens 10 is moved closer to the optical information recording medium in the front, damage due to the optical surface of the upper lens 20 contacting the optical information recording medium is prevented. A protective member 60 for performing the operation may be attached to the peripheral area A2 of the upper lens 20 in some cases.
As the protection member 60, for example, a member having elasticity formed in a ring shape around the optical axis L is used.
[0031]
Therefore, even when such a protection member 60 is attached, predetermined regions on both the upper and lower sides of the peripheral region A2 of the upper lens 20 are formed of smooth surfaces, and the mark 50 of the lower lens 30 is formed by, for example, the convex portion. By forming the mark near the side surface of the lower lens 31, the position of the mark 50 of the lower lens 30 can be visually recognized from the upper lens 20 side.
In the present embodiment, the case where two lenses are vertically combined is described. However, the present invention is not limited to this, and three or more lenses may be vertically combined.
Also, the objective lens 10 unitized by combining lenses has been described. However, the present invention is not limited to this, and the optical element unit of the present invention can be applied to an optical element included in an optical pickup device such as a collimator.
Further, the lens shape, the shape of the mark, the formation position, and the like can be appropriately changed within the scope of the present invention.
[0032]
【The invention's effect】
According to the first aspect of the present invention, the uppermost optical element is arranged such that a mark of an optical element disposed below the uppermost optical element is visible from the upper surface side of the uppermost optical element. At least a part of a region other than the optical surface among the upper and lower surfaces of the element is smoothed.
Therefore, even when a plurality of optical elements are vertically combined, the operator can visually recognize the mark of the lower optical element from a region other than the upper optical surface of the uppermost optical element, and It is possible to recognize in which of the plurality of mold cavities the optical element is manufactured.
[0033]
According to the second aspect of the present invention, the same effects as those of the first aspect can be obtained, and the annular zone around the optical axis of a region other than the optical surface on the upper and lower surfaces of the uppermost optical element can be obtained. Make it smooth.
Therefore, in a process after combining a plurality of optical elements up and down, for example, when performing an adjustment operation for correcting astigmatism, coma aberration, and the like, the uppermost optical element is moved relative to the lower optical element. In some cases, the upper optical element is rotated relative to the lower optical element. The position can be visually recognized from the uppermost optical element side, and the workability of the adjustment operation can be improved.
[0034]
According to the third aspect of the present invention, the same effects as those of the first or second aspect can be obtained, and even when the protective member is provided, the mark position of the lower optical element is shifted to the uppermost optical element side. Can be seen from
[Brief description of the drawings]
FIG. 1 is a plan view showing a state in which two upper and lower lenses are combined.
FIG. 2 is a longitudinal sectional view showing a state where two lenses, upper and lower, are combined.
FIG. 3 is a plan view showing a state where two upper and lower lenses are combined.
FIG. 4 is a longitudinal sectional view showing a mark forming position of a lower lens when a protective member is attached.
FIG. 5 is a main part plan view showing the structure of a mold.
FIG. 6 is a plan view of a main part showing a structure of a mold cavity.
FIG. 7 is a plan view showing a state in which two upper and lower lenses are combined.
[Explanation of symbols]
A1 Optical function area A2 Perimeter area B1 Optical function area B2 Perimeter area 10 Optical element unit (objective lens)
20 Optical element (upper lens)
30 Optical element (lower lens)
40 mark 50 mark 50 Protective member

Claims (3)

An optical element that is formed by injecting a molten resin into a mold cavity, and is configured by combining a plurality of optical elements having marks indicating which mold cavity is formed among a plurality of mold cavities in a vertical direction. An element unit,
The optical surface between the upper and lower surfaces of the uppermost optical element so that the mark of the optical element disposed below the uppermost optical element is visible from the upper surface side of the optical element disposed at the uppermost position. An optical element unit for smoothing at least a part of a region other than the region. The optical element unit according to claim 1,
An optical element unit for smoothing an annular zone centered on an optical axis of a region other than the optical surface of the upper and lower surfaces of the uppermost optical element. The optical element unit according to claim 1, wherein:
On the upper surface of the uppermost optical element, a protective member for preventing damage to the optical surface of the upper surface of the optical element is provided,
The mark of the optical element disposed below the uppermost optical element may be provided at a position on the upper surface of the uppermost optical element, where the mark is visible from a portion where the protective member is not provided. Characteristic optical element unit.

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