JP2004004339A - Cubic prism and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure good accuracy of attachment of face-to-face superposed sidewall plane surfaces 22a1, 22b1 by a simple structure. <P>SOLUTION: Parts of face-to-face superposed sidewall plane surfaces 22a1, 22b1 constituting the reflective surface 22m of triangular prisms 22a, 22b are formed as attachment surfaces 22a2, 22a2 brought into contact with stationary members 22c, 22c and high accuracy of attachment to the reflective surface 22m is easily ensured by directly positioning the reflective surface 22m itself formed by the sidewall plane surfaces 22a1, 22b1 using the stationary members 22c, 22c. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cube prism having a configuration in which two triangular prism prism pieces are integrated.
[0002]
[Prior art]
2. Description of the Related Art Generally, an optical device that forms an optical path of an optical system by using a cube-type prism is widely known. For example, in the case of an optical head device used for recording / reproducing on an optical recording medium such as a CD and a DVD, as shown in FIG. Since the light guides 3 and 4 pass through the light guide system 5 a plurality of times, a cube-type prism is often employed as the light guide system 5 in order to suppress aberrations caused by the plurality of passes.
[0003]
For example, as shown in FIG. 6, such a cube type prism 5 has two triangular prism type prism pieces 5a and 5b having a substantially triangular prism shape, and the two triangular prism type prism pieces 5a and 5b. 5b, one of the three side wall planes of each of the side walls 5a1 and 5b1 has an integrated structure such that the bonding surfaces 5a1 and 5b1 are superposed face to face. A reflection surface 5m made of a half mirror film or the like is formed on one of the paired side wall planes.
[0004]
When mounting and fixing the cube-type prism 5 having such a structure, flat surfaces 5b2 and 5b2 corresponding to side walls other than the reflection surface 5m provided on each of the triangular prism-type prism pieces 5a and 5b are formed as mounting surfaces. In a state where the mounting surfaces 5b2 and 5b2 other than the reflection surface 5m are positioned by being pressed against the two fixing members 6 and 6, they are positioned by using an adhesive or the like. It is fixed to the main unit.
[0005]
In mounting and fixing such a cube-type prism 5, it is necessary that the reflecting surface 5m be mounted within a predetermined accuracy so as to satisfy the accuracy required optically. The surfaces including the mounting surfaces 5b2 and 5b2 are polished.
[0006]
[Problems to be solved by the invention]
However, as described above, no matter how much the accuracy of each surface including the mounting surfaces 5b2 and 5b2 is obtained, the mounting accuracy of the reflection surface 5m depends on the relationship with the mounting surfaces 5b2 and 5b2. The actual mounting state shown by the solid line may be displaced from the planned state shown by the broken line, and as a result, the mounting accuracy of the reflecting surface 5m may not be sufficiently obtained. is there.
[0007]
Therefore, an object of the present invention is to provide a cube-type prism with a simple configuration and good mounting accuracy of the reflecting surface.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, in the cube-type prism according to the first aspect of the present invention, a part of the facing overlapping side wall plane, which is face-to-face overlapped in the pair of triangular prism type prism pieces, is attached to the mounting surface abutting on the fixing member. Is formed, whereby the reflection surface itself formed on one side of the two-faced overlapping side wall plane is directly positioned by the fixing member, and the mounting accuracy with respect to the reflection surface is easy and high precision. You can get it.
[0009]
In the cube prism according to the second aspect of the present invention, the two triangular prism pieces according to the first aspect have substantially similar triangular bottom shapes that are different from each other. Since the non-overlapping portion of the facing overlapping side wall plane is formed as an attachment surface, only the larger one of the two triangular prism prism pieces is superimposed on the larger one, and the larger triangular prism prism piece becomes The mounting surface is easily formed on the protruding portion so as to protrude from the smaller side.
[0010]
Furthermore, in the cube type prism according to the third aspect of the present invention, the two triangular prism type prism pieces according to the first aspect have a bottom surface shape of a substantially congruent triangular shape, and these two substantially identical triangular prism type prisms. A non-overlapping portion formed by arranging the pieces so as to be displaced from each other along the plane direction of the facing overlapping side wall plane, thereby forming a mounting surface, and the cube prism according to the invention of claim 4. According to the third aspect, since the mounting surface is provided on each of the two triangular prism-shaped prism pieces, one of the two triangular prism-shaped prism pieces can be made identical to each other. This is extremely advantageous in terms of efficiency.
[0011]
Furthermore, in the cube-type prism according to the fifth aspect of the present invention, a part of the facing overlapping side wall plane in at least one of the two triangular-prism-type prism pieces of the first aspect is removed. Polishing is necessary because a part of the facing overlapping side wall plane of the other triangular prism type prism piece exposed from the removed portion of the facing overlapping side wall plane of the one side triangular prism type prism piece forms an attachment surface. When performing an appropriate polishing step on each of the surfaces, no protruding portion or the like of the triangular prism type prism piece is provided in the direction of polishing, as in the method of manufacturing a cube type prism according to the invention of claim 6. The face-to-face overlapping side wall planes in each of the two triangular prism type prism pieces of the cube type prism according to claim 5 are described. In any of the stages before and after the surface polymerization and integration, since there is no projection part of the triangular prism type prism piece in the polishing direction as described above, each surface that needs polishing is Can be subjected to an appropriate polishing process, and as a result, the degree of freedom of the manufacturing process is expanded.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to that, a schematic structure of an optical head device employing a cube prism according to the present invention will be described.
[0013]
In the optical head device 10 shown in FIG. 1, a resin or metal frame 30 is connected to two guide shafts 20A and 20B attached so as to extend in parallel with each other. It is mounted so as to be able to reciprocate via 301, 302, 303, and an optical system as described below is mounted on the frame 30.
[0014]
That is, the optical system of the optical head device 10 shown in FIG. 1 includes a DVD laser diode 40 and a CD laser diode 50, and the first laser beam emitted from each of the laser diodes 40 and 50. Laser light L1 (wavelength 650 nm or 635 nm) and the second laser light L2 (wavelength 780 nm to 800 nm) are selectively guided to the common optical path 60, and by using the common optical path 60, the CD, Recording / reproducing is performed on each recording medium such as CD-R and DVD.
[0015]
The common optical path 60 forms an optical path from the light receiving element 11 attached to one edge of the frame 30 to the objective lens 90, and is formed between the light receiving element 11 and the objective lens 90. , A rising mirror 80 including a sensor lens 12, a light guide system 20, a collimating lens 70, and a total reflection mirror, and the objective lens 90 is located immediately above the rising mirror 80.
[0016]
The two laser diodes 40 and 50 are arranged on the same side of the light guide system 20 in the common optical path 60 so that their optical axes L10 and L20 are parallel to each other. The DVD laser diode 40 is arranged in a region closer to the light receiving element 11 than the CD laser diode 50. Then, the first laser light L1 emitted from the DVD laser diode 40 is directly incident on the light guide system 21, and the second laser light L2 emitted from the CD laser diode 50 is After being split into three beams by the action of the diffraction grating 12, the light is incident on the light guide system 22.
[0017]
Further, the above-described light guide system 20 includes a half mirror 21 having a partial reflection surface, and a cubic prism 22 according to the present invention having a partial reflection surface. The half mirror 21 is arranged such that its partial reflection surface is inclined by 45 degrees with respect to the optical axis L10 of the first laser beam L1 emitted from the DVD laser diode 40. On the other hand, the cubic prism 22 is arranged such that its partial reflection surface is inclined by 45 degrees with respect to the optical axis L20 of the second laser beam L2 emitted from the CD laser diode 50. . The detailed structure of the cubic prism 22 according to the present invention and a method of manufacturing the same will be described later.
[0018]
In the optical head device 10 thus grooved, the objective lens driving device 70 for driving the objective lens 90 in the focusing direction and the tracking direction has a lens holder 71 holding the objective lens 90. The lens holder 71 has a trunk portion 72 formed in a partially cylindrical shape, and a cylindrical bearing portion 73 formed on the inner peripheral side of the trunk portion 72. A pair of tracking driving coils 81 and a pair of focusing driving coils 82 are adhered to the outer peripheral surface of the trunk portion 72.
[0019]
A support shaft 91 is attached to the bottom wall of the holder support member 35 held by the frame 30 so as to stand upright, and the bearing portion of the lens holder 71 described above is supported by the support shaft 91. 73 is inserted so that it can reciprocate in the axial direction. A pair of tracking drive magnets 83 that constitute a tracking magnetic circuit are attached to the holder support member 35 so as to face the tracking drive coil 81 on the lens holder 71 side in the radial direction. With such a configuration, the lens holder 71 is rotated around the support shaft 91 to perform tracking error correction.
[0020]
Further, a pair of focusing drive magnets 84 that constitute a focusing magnetic circuit are attached to the holder support member 35 so as to radially face the focusing drive coil 82 on the lens holder 71 side. With such a configuration, the lens holder 71 is moved in the axial direction of the support shaft 91 to perform a focusing error correction.
[0021]
Next, an embodiment of a detailed structure of the above-described cubic prism 22 used in the optical head device 10 and a method of manufacturing the same will be described.
[0022]
First, the cubic prism 22 in the embodiment shown in FIG. 2 has two triangular prism prism pieces 22a and 22b formed in a substantially triangular prism shape having a triangular bottom surface. One of the three side wall planes 22a1 and 22b1 of the pair of triangular prism type prism pieces 22a and 22b is bonded to each other so as to face each other, so that the two triangular prism type prism pieces 22a and 22b. The cubic prisms 22 are formed integrally with each other, thereby forming a single cubic prism 22.
[0023]
Then, a half mirror film is formed on one of the facing overlapping side wall planes 22a1 and 22b1 as the bonding surfaces which are overlapped with each other in the pair of triangular prism prism pieces 22a and 22b. A reflection surface 22m is formed by the half mirror film. An appropriate polishing step is applied to the surface of the three side wall planes constituting the pair of triangular prism type prism pieces 22a and 22b through which the light beam passes.
[0024]
At this time, the two triangular prism-shaped prism pieces 22a and 22b are formed in two substantially similar triangular shapes having different sizes on the bottom surface of the triangular prism. The facing overlapping side wall planes (bonding surfaces) 22a1 and 22b1 provided on the two large and small triangular prism prism pieces 22a and 22b having different sizes are overlapped so as to face each other. The bonding surface 22b1 of the triangular prism-shaped prism piece 22b is superposed face-to-face so as to be located substantially at the center of the facing superposed sidewall plane 22a1 of the larger triangular prism-shaped prism piece 22a.
[0025]
In other words, in a state where the two facing facing side wall surfaces 22a1 and 22b1 of the pair of triangular prism type prism pieces 22a and 22b face each other, the larger the facing facing side wall surface 22b1 of the smaller triangular prism type prism piece 22b. Both end portions of the facing overlapping side wall plane 22a1 of the triangular prism type prism piece 22a are formed so as to protrude outwardly. The two projecting portions where the facing overlapping side wall plane 22a1 of the larger triangular prism type prism piece 22a protrudes outward are configured as non-overlapping portions, and the two non-overlapping portions are formed. Portions are formed on the mounting surfaces 22a2 and 22a2, respectively. Each of the two mounting surfaces 22a2 and 22a2 is positioned by being pressed against two fixing members 22c and 22c provided on the apparatus main body side corresponding thereto so as to be positioned. In this state, it is fixed by using an adhesive or the like.
[0026]
That is, in the present embodiment, a part of the facing overlapping side wall plane 22a1, which is a bonding surface of the pair of triangular prism type prism pieces 22a constituting the cube type prism 22, is brought into contact with the fixing members 22c, 22c. It is formed so as to constitute the mounting surfaces 22a2 and 22a2. Therefore, the facing overlapping side wall planes 22a1 and 22b1 themselves are directly positioned by the fixing members 22c and 22c, and the mounting accuracy with respect to the reflecting surface 22m formed by one of the facing overlapping side wall planes 22a1 and 22b1 is improved. , And can be obtained easily and with high precision.
[0027]
Further, in the embodiment shown in FIG. 3, the two triangular prism-type prism pieces 22a and 22b constituting the single cubic prism 22 are substantially the same triangle whose bottom shapes of the triangular prisms are substantially congruent with each other. It is formed in a shape. The two triangular prism-shaped prism pieces 22a and 22b having substantially the same shape are displaced from each other in a diagonal direction in the drawing along the plane direction of the facing overlapping side wall planes 22a1 and 22b1 forming the reflection surface 22m. The non-overlapping portions formed by the misalignment are formed on the mounting surfaces 22a2 and 22b2, respectively.
[0028]
That is, each of these mounting surfaces 22a2, 22b2 is provided one by one on both of the two triangular prism type prism pieces 22a, 22b, and these mounting surfaces 22a2, 22b2 are attached to the two fixing members 22c, 22c. It is positioned by being pressed and contacted, and is fixed using an adhesive or the like in the positioned state.
[0029]
In the embodiment shown in FIG. 3, it is possible to make the two triangular prism type prism pieces 22a and 22b the same, which is extremely advantageous in terms of parts cost.
[0030]
On the other hand, in the embodiment shown in FIG. 4, the triangular prism prism piece 22b on one side (upper side in the figure) of the two triangular prism prism pieces 22a and 22b constituting the single cubic prism 22 is provided. Part of both end portions of the provided facing overlapping side wall plane 22b1 is removed. The step of removing the facing overlapping side wall plane 22b1 is performed by cutting both end portions of the triangular prism type prism piece 22b in a direction substantially perpendicular to the facing overlapping side wall plane 22b1.
[0031]
Then, both ends of the triangular prism prism piece 22a on the other side (lower side in the drawing) exposed outward from the removed portion of the overlapping side wall plane 22b1 of the triangular prism prism piece 22b, that is, the facing surface forming the reflection surface 22m Both ends of the plane having the overlapping side wall plane 22a1 are formed on the mounting surfaces 22a2 and 22a2. The mounting surfaces 22a2 and 22a2 of the triangular prism-type prism piece 22a are provided one by one on both sides of the other triangular prism-type prism piece 22b, and the two mounting surfaces 22a2 and 22a2 are connected to the two fixing members 22c. , 22c by being pressed against and abutting against each other, and is fixed using an adhesive or the like in the positioned state.
[0032]
Here, when mounting and fixing the cube-type prism 22, it is necessary that the reflecting surface 22m be mounted within a predetermined accuracy so as to satisfy the optically required accuracy. The respective surfaces including the mounting surfaces 22a2 and 22a2 are polished. Then, in performing such polishing of each outer surface, according to the embodiment shown in FIG. 4 described above, since a protruding portion or the like that hinders the polishing direction is not provided, The necessary polishing step for each surface of the cubic prism 22 is performed before or after the bonding surfaces 22a1 and 22b1 of the two triangular prism prism pieces 22a and 22b are integrated by facing each other. Is also possible, and as a result, the degree of freedom of the manufacturing process is expanded.
[0033]
As described above, the invention made by the inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say.
[0034]
For example, the application range of the present invention is not limited to the optical head device as in the above-described embodiment, and can be similarly applied to a bonding portion of various kinds of optical elements.
[0035]
【The invention's effect】
As described above, the cube-type prism according to the first aspect of the present invention is configured such that a part of the facing overlapping side wall plane that constitutes the reflecting surface of the triangular prism type is attached to the mounting surface that is in contact with the fixing member. Forming and directly positioning the reflecting surface itself formed on one side of the two facing overlapping side wall planes by a fixing member so that the mounting accuracy with respect to the reflecting surface can be obtained easily and with high accuracy. Therefore, with a simple configuration, it is possible to obtain good mounting accuracy of the reflection surface, and it is possible to increase both the reliability and the productivity of the cube prism.
[0036]
According to a second aspect of the present invention, there is provided a cube-type prism, wherein the two triangular prism-type prism pieces in the first aspect have bottom shapes of substantially similar triangular shapes different from each other. The non-overlapping portion of the facing overlapping side wall plane is formed as an attachment surface, and only the smaller one of the two triangular prism prism pieces is superimposed on the larger one, and the larger triangular prism prism piece starts from the smaller one. Since the mounting surface is easily formed at the protruding portion so as to protrude, the above-described effects can be obtained at low cost and reliably.
[0037]
Further, in the cube prism according to the third aspect of the present invention, the two triangular prism prism pieces according to the first aspect have a triangular bottom shape substantially congruent with each other, and these two substantially identical triangular prism prisms are used. A non-overlapping portion formed by being arranged so as to be displaced from each other along the plane direction of the facing overlapping side wall plane of the piece is formed as a mounting surface, and the cube type prism according to the invention of claim 4, Since the mounting surface according to the third aspect is provided at one place on each of the two triangular prism-type prism pieces, it is possible to make the two triangular prism-type prism pieces identical with each other, thereby significantly reducing component costs. Since it is advantageous, it is possible to improve particularly the low cost effect among the effects described above.
[0038]
Furthermore, in the cube-type prism according to the fifth aspect of the present invention, at least one of the two triangular-prism-type prism pieces according to the first aspect has a triangular prism-type prism piece in which a part of the facing overlapping side wall plane is removed. Polishing is necessary because a part of the facing overlapping side wall plane of the other triangular prism type prism piece exposed from the removed part of the facing overlapping side wall plane of the triangular prism type prism piece on one side forms an attachment surface. When performing an appropriate polishing step on each of the surfaces, no protruding portion or the like of the triangular prism type prism piece is provided in the direction of polishing, as in the method of manufacturing a cube type prism according to the invention of claim 6. A face-to-face overlapping side wall face of each of the two triangular prism-type prism pieces of the cube-type prism according to claim 5 is face-to-face. At the stage before or after combining and integrating, it is possible to perform an appropriate polishing process on each surface that requires polishing, so that the degree of freedom of the manufacturing process is expanded. Therefore, among the effects described above, particularly, productivity can be improved.
[Brief description of the drawings]
FIG. 1 is an explanatory plan view showing a main part of an optical head device to which the present invention is applied.
FIG. 2 is an explanatory plan view showing a structure of a cube prism according to an embodiment of the present invention.
FIG. 3 is an explanatory plan view illustrating a structure of a cube prism according to another embodiment of the present invention.
FIG. 4 is an explanatory plan view showing a structure of a cube prism according to still another embodiment of the present invention.
FIG. 5 is an explanatory side view showing a schematic configuration of a light guide system using a generally used cube prism.
FIG. 6 is an explanatory plan view showing the structure of a generally used cube prism.
FIG. 7 is an explanatory plan view showing an attached state of a generally used cube prism.
[Explanation of symbols]
Reference Signs List 10 optical head device 22 cubic prisms 22a, 22b triangular prism prism pieces 22a1, 22b1 facing overlapping side wall planes 22a2, 22a2, 22b2 mounting surfaces 22c, 22c fixing member 22m reflection surface

Claims (6)

A pair of triangular prism-shaped prism pieces formed in a substantially triangular prism shape having three side wall planes are integrated by being face-to-face superposed,
A reflection surface is formed on one of the pair of side wall planes that are superposed face to face, and
A cube type structure in which the mounting surface formed on any of the three side wall planes of each of the triangular prisms is fixed in a state where it is positioned by being brought into contact with at least two fixing members. In the prism
A cube-type prism, wherein a part of a face-to-face overlapping side wall surface of the pair of triangular prism-type prism pieces, which is face-to-face overlapped, is formed on the mounting surface abutting on the fixing member. The two triangular prism-type prism pieces have a bottom shape formed of substantially similar triangular shapes different from each other,
2. The cube-type prism according to claim 1, wherein non-overlapping portions of the facing overlapping side wall planes of the two large and small triangular prism type prism pieces are formed as the mounting surface. The two triangular prism-type prism pieces have a bottom shape formed of substantially congruent triangular shapes,
A non-overlapping portion formed by arranging these two substantially identical triangular prism prism pieces so as to be displaced from each other along the plane direction of the facing overlapping side wall plane is formed as the mounting surface. 2. The cube-type prism according to claim 1, wherein: 4. The cube-type prism according to claim 3, wherein the mounting surface is provided on each of the two triangular prism-type prism pieces. A part of the facing overlapping side wall plane in at least one of the two triangular prism prism pieces is removed,
A part of the facing overlapping side wall plane of the other triangular prism type prism piece exposed from the removed portion of the facing overlapping side wall plane in the one side triangular prism type prism piece is configured to form the mounting surface. The cube-type prism according to claim 1, wherein A method for manufacturing a cube-type prism according to claim 5,
Face-to-face superposition in each of the two triangular prism-type prism pieces Before or at the point after the time when face-to-face superposition of side wall planes is integrated, or at a later stage, an appropriate polishing process is performed on each surface that requires polishing. A method for manufacturing a cube-type prism, characterized in that:

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