WO2012002196A1

WO2012002196A1 - Optical pick-up device

Info

Publication number: WO2012002196A1
Application number: PCT/JP2011/064185
Authority: WO
Inventors: 貴史阿久津
Original assignee: 三洋電機株式会社
Priority date: 2010-06-21
Filing date: 2011-06-22
Publication date: 2012-01-05
Also published as: JP2013069353A

Abstract

Provided is an optical pick-up device which makes it possible to reduce the number of parts and operation steps for attaching a diffraction grating to a housing. An optical pick-up device (1) is provided with a diffraction grating (8) and a housing (2) on an optical axis between a laser light source (6) and an object lens (5). The diffraction grating (8) diffracts laser light emitted from the laser light source (6) and is housed in a housing chamber (20) in the housing (2). The housing chamber (20) has a shape which prevents the diffraction grating (8) from moving in a second direction perpendicular to a first direction in which a periodic structure repeats in the grating surface of the diffraction grating (8).

Description

Optical pickup device

The present invention relates to an optical pickup device.

For example, an inline DPP (Differential Push-Pull) system is known as a tracking error signal detection system for an optical pickup device. In the in-line DPP method, the laser beam emitted from the laser light source is separated into a main beam and a sub beam by using a diffraction grating in which a predetermined periodic structure is provided in each divided region. These light beams are condensed on the recording surface of the optical disk by the objective lens to form a main spot and a sub spot, and the reflected light of these spots is received by the photodetector. A tracking error signal is obtained by performing an operation based on the detection signal detected by the photodetector.

In such an inline DPP method, a diffraction grating divided into at least two regions having a predetermined periodic structure is used. In this case, in order to obtain an accurate tracking signal, the center of the entire periodic structure is placed at the center of the laser light so that the amount of laser light applied to the diffraction grating is uniform in each divided region of the diffraction grating. It is necessary to approximately match the axis. Therefore, an optical pickup device capable of adjusting the positioning of the diffraction grating is known (see, for example, Patent Document 1).

In this optical pickup device, the diffraction grating is supported by the first holder, and the first holder is coupled to the second holder so as to be rotatable around the optical axis of the laser beam. The first holder and the second holder are accommodated in an accommodation chamber provided in the housing. In the storage chamber, the first holder can rotate with respect to the second holder, and the first and second holders can move in a second direction orthogonal to the first direction in which the periodic structure is repeated on the grating surface of the diffraction grating. It has become. That is, the grating surface of the diffraction grating is rotated and adjusted with respect to the laser beam by rotating the first holder using an adjustment jig or the like. Further, by moving the second holder in the second direction, the position of the diffraction grating in the second direction with respect to the laser light is adjusted independently of the rotation adjustment.

JP 2008-97667 A

However, in the conventional optical pickup device, for example, two parts of the first and second holders are required to attach the diffraction grating to the housing, and the optical pickup device may be increased in size. In addition, for example, an extra work step for coupling the first holder and the second holder is required, and the assembly work of the optical pickup device may be complicated.

Also, in the market etc., there is a demand for an optical pickup device with a reduced number of parts and work processes.

A main invention for solving the above-described problem is a diffraction grating that is interposed on an optical axis between a laser light source and an objective lens and diffracts laser light emitted from the laser light source, and a housing in which the diffraction grating is housed. A housing having a chamber, and the storage chamber has a shape that prohibits the diffraction grating from moving in a second direction orthogonal to a first direction in which a periodic structure is repeated on a grating surface of the diffraction grating. Is an optical pickup device.

Further, another main invention for solving the above-described problem is that the diffraction grating is interposed on the optical axis between the laser light source and the objective lens and diffracts the laser light emitted from the laser light source, and the diffraction grating, A reflection mirror interposed on the optical axis between the objective lens and reflecting the laser beam so that the laser beam is directed toward the objective lens; a first receiving chamber containing the diffraction grating; and the reflection A housing having a second housing chamber in which a mirror is housed, wherein the second housing chamber has the laser with respect to the reflecting surface of the reflecting mirror so that the laser light is transmitted through a substantial center of the objective lens. An optical pickup device having a shape capable of adjusting a reflection angle of light.

Another main invention for solving the above-described problem is a reflection mirror that is interposed on the optical axis between the diffraction grating and the objective lens and reflects the laser light so that the laser light is directed toward the objective lens, A housing having a housing chamber in which the reflecting mirror is housed, wherein the housing chamber has a reflection angle of the laser light with respect to a reflecting surface of the reflecting mirror so that the laser light passes through a substantially center of the objective lens. It is an optical pick-up apparatus characterized by exhibiting the shape which can be adjusted.

Other features of the present invention will become apparent from the accompanying drawings and the description of the present specification.

According to the present invention, it is possible to provide an optical pickup device capable of reducing the number of parts and work processes for attaching the diffraction grating to the housing.

Moreover, according to the present invention, an optical pickup device capable of reducing the number of parts and the work process can be provided.

It is a perspective view of the optical pick-up apparatus concerning this embodiment. It is the perspective view which abbreviate | omitted the cover and objective lens holder of the optical pick-up apparatus shown in FIG. It is a perspective view for demonstrating the optical system in the optical pick-up apparatus shown in FIG. It is a figure which shows the grating surface of the diffraction grating in the optical pick-up apparatus shown in FIG. It is a visual field characteristic figure which shows the level change of the tracking error signal with respect to the moving amount | distance of the tracking direction of an objective lens. It is a perspective view of the back surface side of the optical pick-up apparatus shown in FIG. FIG. 6B is an enlarged view of a portion surrounded by a broken line of the optical pickup device shown in FIG. 6A cut along a-a ′. It is a front view of the cross section of the optical pick-up apparatus shown to FIG. 6B. FIG. 6B is an enlarged view of a portion surrounded by a broken line of the optical pickup device shown in FIG. 6A. It is a figure for demonstrating position adjustment of the reflective mirror of the optical pick-up apparatus shown in FIG. It is an enlarged view of the reflective mirror of the optical pick-up apparatus shown to FIG. 7A. It is a perspective view for demonstrating adhesion | attachment with the housing and reflection mirror of the optical pick-up apparatus shown to FIG. 7A. It is an enlarged view of the part enclosed with the broken line of the optical pick-up apparatus shown to FIG. 8A. It is a side view of a gonio stage and a reflective mirror. It is a perspective view of a gonio stage and a reflective mirror shown to FIG. 9A. It is a perspective view at the time of attaching a gonio stage to the optical pick-up apparatus shown to FIG. 7A.

At least the following matters will become clear from the description of this specification and the accompanying drawings.

=== Optical pickup device ===
<<< Overall configuration >>>
With reference to FIG. 1 thru | or FIG. 3, the whole structure of the optical pick-up apparatus 1 concerning this embodiment is demonstrated.

In the optical pickup device 1, the focus direction F is, for example, the optical axis direction through which laser light passes through the objective lens 5. The tracking direction Tr is, for example, orthogonal to the focus direction F and is the radial direction of an optical disk (not shown). The tracking direction Tr is a moving direction of the optical pickup device 1 from the inner peripheral side to the outer peripheral side of the optical disc and / or a moving direction of the optical pickup device 1 applied from the outer peripheral side to the inner peripheral side of the optical disc. Further, the tangential direction Tn is, for example, orthogonal to the focus direction F, orthogonal to the tracking direction Tr which is the radial direction of the optical disc and the moving direction of the optical pickup device 1, and is substantially spiral / circumferential of the optical disc. It is considered to be a direction.

Further, when the optical pickup device 1 located in the vicinity of the optical disc and viewed from the side is used as a reference, the side on which the objective lens 5 of the optical pickup device 1 approaches the optical disc is defined as the + side of the focus direction F. The side on which the objective lens 5 moves away is defined as the minus side of the focus direction F. Further, when the objective lens 5 of the optical pickup device 1 that is located in the vicinity of the optical disc and is viewed in plan is used as a reference, the inner peripheral side of the optical disc is set to the + side of the tracking direction Tr, and the outer peripheral side of the optical disc is set to the tracking direction Tr. The negative side. Further, when the objective lens 5 of the optical pickup device 1 that is located in the vicinity of the optical disk and viewed in plan is used as a reference, the clockwise direction side is the positive side of the tangential direction Tn, and the counterclockwise direction side is the tangential side. The negative side of the direction Tn.

In addition, each direction and ± side of each direction in the present invention are defined as each direction when viewing the optical disc with respect to the optical pickup device 1 and ± side of each direction. In this specification, each direction and the definition of the ± side of each direction are defined for convenience in describing the optical pickup device 1.

The optical pickup device 1 includes a housing 2, an objective lens holder 4, an objective lens 5, a laser light source 6, a holder 7, a diffraction grating 8, a polarization beam splitter 9, a quarter wavelength plate 10, and a collimator. The lens 11, the reflection mirror 12, the

parallel plates

13 and 14, the photodetector 15, and the light receiving element 16 are accommodated. A cover 3 is attached to the housing 2 so as to cover the configuration other than the objective lens 5 and the objective lens holder 4 that supports the objective lens 5. Then, an information recording surface (single layer or multiple layers) such as CD (Compact Disc), DVD (Digital Versatile Disc), Blu-ray (Blu-ray Disc) (registered trademark) is applied to the objective lens 5 exposed from the cover 3. An optical disc having a signal layer) is opposed to the optical disc. The optical pickup device 1 records, reproduces, and erases information by irradiating the information recording surface of the optical disc with laser light. An example of an optical system for laser light emitted from the laser light source 6 of the optical pickup device 1 will be described.

The laser light source 6 emits laser light in an infrared wavelength band (for example, 765 nm to 840 nm) for irradiating the information recording surface of the CD when a control voltage is applied from a laser driver (not shown). Further, the laser light source 6 emits laser light in a red wavelength band (for example, 630 nm to 685 nm) for irradiating the information recording surface of the DVD when a control voltage is applied from a laser driver. Further, the laser light source 6 emits laser light in a blue-violet wavelength band (for example, 400 nm to 450 nm) for irradiating the information recording surface of Blu-ray when a control voltage is applied from a laser driver. That is, when a CD standard first optical disc (not shown) is mounted on a turntable (not shown), laser light in the infrared wavelength band is emitted from the laser light source 6. Further, when a DVD standard second optical disk (not shown) is mounted on the turntable, a laser beam in the red wavelength band is emitted from the laser light source 6. Further, when a Blu-ray standard third optical disc (not shown) is mounted on the turntable, a laser beam in the blue-violet wavelength band is emitted from the laser light source 6. The optical pickup device 1 corresponds to, for example, at least one type of optical discs among the various types of optical discs. Hereinafter, the first to third optical disks are collectively referred to as optical disks.

Thus, the laser light source 6 emits a laser beam for irradiating the information recording surface of various optical discs when the control voltage is applied from the laser driver. The optical pickup device 1 records, reproduces, and erases information by irradiating the information recording surface of various optical discs with the laser light from the laser light source 6 through the objective lens 5. Therefore, for each configuration of the optical system housed in the housing 2 of the optical pickup device 1, an optical path (forward path) until the laser light emitted from the laser light source 6 is irradiated onto the optical disk through the objective lens 5, and the optical disk A description will be given by dividing into the optical path (return path) until the laser beam reflected by is received by the photodetector 15.

<<< About the outgoing path of laser light >>>
First, a configuration interposed in the forward path of laser light will be described. The laser light emitted from the laser light source 6 is sequentially passed through the diffraction grating 8 supported by the holder 7, the polarization beam splitter 9, the quarter wavelength plate 10, the collimator lens 11, the reflection mirror 12, and the objective lens 5. The information recording surface is irradiated.

The laser light emitted from the laser light source 6 is diffracted by the diffraction grating 8 and split into one main beam and at least two sub beams. The diffraction grating 8 is housed in a first housing chamber 20 provided in the housing 2 in a state where the grating surface 82 is supported by the holder 7 so as to be orthogonal to the optical axis of the laser light. A specific configuration of the diffraction grating 8 and a structure for attaching the holder 7 to the housing 2 will be described later.

The laser beam dispersed by the diffraction grating 8 is reflected by the polarizing beam splitter 9 toward the quarter wavelength plate 10. The laser light incident on the quarter wavelength plate 10 is converted from linearly polarized light to circularly polarized light. The laser beam converted into circularly polarized light is incident on the collimator lens 11 and converted into substantially parallel light. The laser light converted into substantially parallel light is reflected toward the objective lens 5 by the reflection mirror 12. The reflection mirror 12 is accommodated in a second accommodation chamber 21 provided in the housing 2. A structure for attaching the reflection mirror 12 to the housing 2 will be described later. The laser light incident on the objective lens 5 is condensed on the information recording surface of the optical disk, and becomes at least three condensing spots.

The light receiving element 16 detects a component transmitted through the polarization beam splitter 9 from the laser light emitted from the laser light source 6 and outputs a signal corresponding thereto. Based on this signal, a signal for applying feedback to the laser light source 6 is generated.

<<< About the return path of laser light >>>
Next, the configuration interposed in the return path of the laser light will be described. The laser light reflected from at least three condensing spots formed on the information recording surface of the optical disc is sequentially an objective lens 5, a reflecting mirror 12, a collimator lens 11, a quarter wavelength plate 10, a polarizing beam splitter 9, and a parallel beam. The light is received by the photodetector 15 after passing through the flat plate 13 and the parallel plate 14.

The laser light reflected from the optical disk is converted into substantially parallel light by the objective lens 5. The laser light converted into substantially parallel light is reflected by the reflecting mirror 12 toward the collimator lens 11 and converted into convergent light by the collimator lens 11. The laser light converted into convergent light is converted from circularly polarized light into linearly polarized light by the quarter wavelength plate 10. The laser beam converted into linearly polarized light is transmitted toward the parallel plate 13 by the polarization beam splitter 9, and astigmatism is corrected by the parallel plate 13. The astigmatism-corrected laser light is given astigmatism as a focus error component by the parallel plate 14, and the coma generated by the polarization beam splitter 9 and the parallel plate 13 is corrected, and then light detection is performed. The light is received by the device 15.

The photodetector 15 that has received the laser light generates an electrical signal that is photoelectrically converted according to the amount of the main beam of the laser light, and outputs it to a processing circuit (not shown). As a result, information is reproduced from the information recording surface of the optical disc based on the electrical signal corresponding to the main beam. In addition, the photodetector 15 generates an electrical signal that is photoelectrically converted in accordance with the amount of laser beam sub-beams, and outputs the electrical signal to the processing circuit. As a result, a tracking error signal (TE signal), a focus error signal (FE signal), and the like are generated based on the electrical signals corresponding to the main beam and sub beam of the laser light. Based on these signals, the objective lens holder 4 of the optical pickup device 1 is displaced in the tracking direction Tr and the focus direction F.

<<< About diffraction grating >>>
A specific configuration of the diffraction grating 8 will be described with reference to FIG. The diffraction grating 8 is formed using, for example, glass / plastic that transmits laser light from the laser light source 6 as a base material, and has a periodic structure in which the concave portions 80 and the convex portions 81 are alternately repeated by processing such as photoetching. The lattice plane 82 is provided. The lattice plane 82 includes a first region 8a and a second region 8b that are joined with the dividing line 8c as a boundary. The periodic structure of the first region 8a and the second region 8b is repeated along the direction of the dividing line 8c, and the phase difference between them is 180 degrees. Thus, the laser light is incident on the diffraction grating 8 so as to pass through the dividing line 8c, whereby the laser light is split into one main beam and at least two sub-beams that are 180 degrees out of phase with each other. The diffraction grating 8 is configured as a multiple division type diffraction grating 8 including at least a plurality of regions of a first region 8a and a second region 8b. For example, it is preferable to use an even-divided type diffraction grating 8 including at least a first region 8a and a second region 8b. The direction in which the periodic structure is repeated on the grating surface 82 of the diffraction grating 8 is defined as a first direction A, and the direction orthogonal to the first direction A is defined as a second direction B. That is, the dividing line 8c extends the center in the second direction B of the diffraction grating 8 along the first direction A and divides the first region 8a and the second region 8b.

At least three beams dispersed by the diffraction grating 8 are condensed on the information recording surface of the optical disk by the objective lens 5 as described above, and become at least three condensing spots. In the in-line DPP method, in order to increase the accuracy of the TE signal, it is necessary to form these at least three focused spots on the same track of the optical disc. In order for at least three focused spots to be formed on the same track of the optical disc, the optical axis of the laser beam (the intensity center point of the laser beam) is a diffraction grating so as to increase the phase symmetry of at least two sub beams. It is preferable to pass through approximately the center of the objective lens 5 when passing through the eight dividing lines 8c and at the reference position. The reference position is a position where the objective lens 5 is not displaced to the + side or the − side of the tracking direction Tr, and the amount of movement of the objective lens 5 in the tracking direction Tr (hereinafter simply referred to as the amount of movement) becomes zero. It is.

Here, the relationship between the position of the optical axis of the laser beam passing through the diffraction grating 8, the amount of movement of the objective lens 5, and the level change of the TE signal will be described with reference to FIG. FIG. 5 is a visual field characteristic diagram showing the degree of deterioration of the amplitude of the TE signal with respect to the amount of movement of the objective lens 5 when the laser light passes through the approximate center of the objective lens 5 when the objective lens 5 is at the reference position. It is. This visual field characteristic diagram shows the symmetry of the TE signal (the symmetry of the visual field characteristic) when the objective lens 5 moves from the reference position to the + side of the tracking direction Tr and to the − side. . The higher the symmetry of the visual field characteristic, the higher the accuracy of the TE signal.

5, a curve CP indicated by a solid line is a visual field characteristic of the TE signal when the optical axis of the laser light passes on the dividing line 8 c of the diffraction grating 8. A curve CP shows a maximum value when the objective lens 5 is at the reference position, and is approximately symmetrical on the + side and the − side of the movement amount of the objective lens 5 around the maximum value. On the other hand, the curve CQ indicated by the dotted line and the curve CR indicated by the alternate long and short dash line are respectively the case where the optical axis of the laser beam is shifted from the division line 8c of the diffraction grating 8 toward the first region 8a and the second region 8b. It is a visual field characteristic of TE signal when it has shifted to the side. Both the curve CQ and the curve CR do not show the maximum value when the objective lens 5 is at the reference position, and the symmetry of the visual field characteristics is lower than that of the curve CR.

For this reason, in the optical pickup device 1, in order to increase the accuracy of the TE signal, the position of the optical axis of the laser light emitted from the laser light source 6 and the position of the dividing line 8c of the diffraction grating 8 are considered in advance. 2 is attached to the holder 7.

<<< About the mounting structure of the holder to the housing >>>
A structure for attaching the holder 7 to the housing 2 will be described with reference to FIGS. 6A to 6D. In the optical pickup device 1, the holder is placed in the first storage chamber 20 provided in the housing 2 so that the diffraction grating 8 supported by the holder 7 is interposed on the optical axis between the laser light source 6 and the polarization beam splitter 9. 7 is accommodated.

The holder 7 sandwiches the outer edge side of the grating surface 82 from both sides in the direction orthogonal to the grating surface 82 so that the grating surface 82 of the diffraction grating 8 is exposed. The holder 7 includes a cylindrical member 70 that protrudes toward the laser light source 6 in a direction orthogonal to the grating surface 82 of the diffraction grating 8 when accommodated in the first accommodation chamber 20.

The first accommodating chamber 20 has a shape that accommodates the holder 7 so that the optical axis of the laser beam passes the dividing line 8 c of the diffraction grating 8 and prohibits the accommodated holder 7 from moving in the second direction B. ing. Specifically, the first storage chamber 20 includes

walls

20 a and 20 b that are orthogonal to the optical axis of the laser light emitted from the laser light source 6.

Cutouts

20c and 20d through which laser light passes are formed in the

walls

20a and 20b facing each other. Further, a cylindrical member 20e that is rotatably coupled to the cylindrical member 70 of the holder 7 is formed on the inner surface 20f of the first wall 20b on the laser light source 6 side of the first storage chamber 20. The cylindrical member 20 e protrudes toward the holder 7 along the optical axis direction C (third direction) of the laser light, and has an inner diameter slightly longer than the outer diameter of the cylindrical member 70. By fitting the cylindrical member 20e and the cylindrical member 70 so that the outer surface 7a of the cylindrical member 70 faces the inner surface 20f of the cylindrical member 20e, the holder 7 moves around the optical axis of the laser beam in the first storage chamber 20. The diffraction grating 8 is disposed so that the grating surface 82 is orthogonal to the optical axis of the laser beam. In addition, the holder 7 and the diffraction grating 8 are prohibited from moving in the second direction B in the first storage chamber 20. The optical axis direction C is, for example, the axial direction of laser light that is emitted from the laser light source 6 and passes through the dividing line 8c of the diffraction grating 8 located in the first storage chamber 20.

Further, in the first storage chamber 20, a leaf spring 17 (plate spring / elastic body) that applies an elastic force to the holder 7 to prohibit the holder 7 from moving in the optical axis direction C of the laser light is provided in the holder. 7 is housed together. The length L1 of the laser light in the first storage chamber 20 in the optical axis direction C is longer than the length L2 of the holder 7 in the same direction C. Therefore, the holder 7 is inserted from a position close to the second wall 20a of the first storage chamber 20, and the cylindrical member 70 is pushed into the interior 20g of the cylindrical member 20e, whereby the second wall 20a of the first storage chamber 20 is inserted. The leaf spring 17 is accommodated in a space 20 h formed between the holder 7 and the holder 7. Further, the plate spring 17 has a notched surface 17 a facing the diffraction grating 8. The holder 7 is pressed against the first wall 20b of the first storage chamber 20 by the leaf spring 17, so that the holder 7 can rotate around the optical axis of the laser light while moving the laser light in the optical axis direction C. Movement is prohibited. Therefore, the grating surface 82 of the diffraction grating 8 can be rotated and adjusted with respect to the optical axis of the laser beam by rotating the holder 7 around the optical axis using an adjustment jig (not shown). At this time, since the movement of the holder 7 in the second direction B and the optical axis direction C of the laser beam is prohibited, the diffraction grating 8 moves in the second direction B or the laser beam as the diffraction grating 8 rotates. Can be prevented from moving in the optical axis direction C.

As described above, in the optical pickup device 1, the first storage chamber 20 is provided with respect to the housing 2 so that the optical axis of the laser light emitted from the laser light source 6 passes on the dividing line 8 c of the diffraction grating 8. ing. As a result, for example, the holder 7 does not need to be composed of two parts in order to perform the rotation adjustment of the diffraction grating 8 and the position adjustment in the second direction B independently, and the diffraction grating 8 is attached to the housing 2. The number of parts and the work process can be reduced. In addition, since the number of parts can be reduced, the optical pickup device 1 can be reduced in size and the manufacturing cost can be reduced.

By the way, in the optical pickup device 1, in order to increase the accuracy of the TE signal, the movement in the second direction B is performed in the first storage chamber 20 provided in advance in consideration of the positional relationship between the laser light source 6 and the diffraction grating 8. The holder 7 is accommodated in a state in which is prohibited. However, in order to further improve the accuracy of the TE signal, it is necessary to consider, for example, variations caused by the configuration and assembly of the optical system in the housing 2.

Therefore, in the optical pickup device 1, when the reflection mirror 12 is attached to the housing 2, the reflection angle of the laser beam with respect to the reflection surface 12 a of the reflection mirror 12 is adjusted according to the variation caused by the actual configuration or assembly, The position of the optical axis of the laser beam passing through the objective lens 5 is adjusted.

<<< About the reflection mirror mounting structure for the housing >>>
Hereinafter, the attachment structure of the holder 7 to the housing 2 will be described with reference to FIGS. 7A to 9D. In the optical pickup device 1, the reflection mirror 12 is accommodated in the second accommodation chamber 21 provided in the housing 2 so as to be interposed on the optical axis of the laser light between the collimator lens 11 and the objective lens 5.

The second storage chamber 21 has a reflection angle of the laser beam with respect to the reflection surface 12a of the stored reflection mirror 12, that is, an angle of the reflection surface 12a of the reflection mirror 12 with respect to the optical axis of the laser beam from the collimator lens 11 (hereinafter simply referred to as a reflection surface). (Referred to as the angle of 12a). Specifically, the second storage chamber 21 has a box shape in which the + side in the focus direction F and the side facing the collimator lens 11 are open. The second storage chamber 21 has a shape slightly larger than that of the reflection mirror 12 so that a space (gap) 21 c is formed between the wall surfaces 21 a and 21 b and the reflection mirror 12.

Accordingly, in the inside 21d of the second storage chamber 21, the + side of the tracking direction Tr of the reflecting surface 12a of the reflecting mirror 12 is set to the + side of the focus direction F with respect to the − side (the direction indicated by the arrow b in FIG. 7B). The optical axis of the laser beam reflected by the reflecting mirror 12 can be moved to the minus side of the tracking direction Tr. Similarly, by moving the reflecting mirror 12 in the direction indicated by the arrow c in FIG. 7B, the optical axis of the laser light can be moved to the negative side of the tangential direction Tn. Further, by moving the reflection mirror 12 in the direction indicated by the arrow d in FIG. 7B, the optical axis of the laser light can be moved to the + side of the tracking direction Tr. Further, by moving the reflecting mirror 12 in the direction indicated by the arrow e in FIG. 7B, the optical axis of the laser light can be moved to the + side of the tangential direction Tn.

In the inside 21d of the second storage chamber 21, the reflection mirror 12 whose angle of the reflection surface 12a is adjusted is fixed to the negative side wall surface (bottom surface) 21b in the focus direction F of the second storage chamber 21 by an adhesive. The The adhesive is a UV (ultraviolet) curable adhesive that is cured by being irradiated with ultraviolet rays. For example, as shown in FIG. 8B, at least three

adhesive spots

22 a and 22 b on the bottom surface of the second storage chamber 21. 22c. The reflection mirror 12 accommodated in the second storage chamber 21 is first placed on the

adhesion spots

22a, 22b, 22c before UV irradiation. Next, the angle of the reflecting surface 12a of the reflecting mirror 12 is adjusted in the above-described direction in accordance with variations caused by the configuration and assembly in the optical system of the optical pickup device 1. Then, the

adhesion spots

22a, 22b, and 22c are irradiated with UV while maintaining the adjusted angle of the reflecting surface 12a of the reflecting mirror 12. Since the adhesive is thereby cured, the reflection mirror 12 is attached to the housing 2 in a state where the angle of the reflection surface 12a is adjusted.

<<< Adjustment of the reflection angle of the laser beam to the reflection surface of the reflection mirror >>>
In the following, an example of a method for adjusting the angle of the reflecting surface 12a of the reflecting mirror 12 according to variations in the configuration and assembly of the optical system of the optical pickup device 1 will be described mainly with reference to FIGS. 9A to 9C. To do.

In this embodiment, the reflecting mirror 12 is accommodated in the second accommodating chamber 21 using the gonio stage 30 and an autocollimator (not shown), and the reflecting mirror 12 is attached to the housing 2 while adjusting the angle of the reflecting surface 12a. At this time, the laser light passing through the objective lens 5 is adjusted by adjusting the angle of the reflection surface 12a of the reflection mirror 12 in accordance with the variation occurring in the configuration from the laser light source 6 to the reflection mirror 12 in the forward path of the laser light. Adjust the position of the optical axis.

The gonio stage 30 includes a main body 34, adjustment knobs (adjustment knobs) 32 and 33 provided in the main body 34, and an adsorption member 31 provided in the main body 34. By rotating the adjustment knob 32, the stage 34a of the main body 34 can be moved in the direction indicated by the arrow g in FIG. 9B. Further, by rotating the adjustment knob 33, the stage 34a of the main body 34 can be moved in the direction indicated by the arrow f in FIG. 9A. One end of the adsorption member 31 is attached to the stage 34a of the main body 34, and is linked to the stage 34a. Further, a suction pad (not shown) or the like is attached to the other end of the suction member 31, and the suction pad can be attached to and detached from the reflection surface 12a of the reflection mirror 12.

The autocollimator irradiates the reflection mirror 12 with laser light for adjustment, the position (measurement position) of the optical axis of the reflected light, and the optical axis of the reflected light obtained when the reflection mirror 12 is tilted to a target angle. Are displayed on a monitor or the like (not shown). Therefore, for example, the angle of the reflecting surface 12a of the reflecting mirror 12 can be adjusted to a target angle by rotating the adjustment knobs 32 and 33 of the gonio stage 30 while confirming the display on the monitor of the autocollimator.

Hereinafter, the angle of the reflecting surface 12a of the reflecting mirror 12 is adjusted by the gonio stage 30 and the autocollimator so that the optical axis of the laser light from the reflecting mirror 12 passes through the approximate center of the objective lens 5 at the reference position. explain.

First, an optical system excluding the reflecting mirror 12 and the objective lens 5 is incorporated in the housing 2. Then, laser light is emitted from the laser light source 6, and the focus direction of the optical axis of the laser light reflected from the reflection mirror 12 through the diffraction grating 8, the polarization beam splitter 9, the quarter wavelength plate 10, and the collimator lens 11. An angle with respect to F (detection optical axis angle) is detected. When the detection optical axis angle varies in the configuration from the laser light source 6 to the reflection mirror 12, the angle of the optical axis of the laser light passing through the center position of the objective lens 5 with respect to the focus direction F (target optical axis angle). ). Therefore, according to the deviation amount between the detected optical axis angle and the target optical axis angle, the target collimator is set to the autocollimator so that the position of the optical axis of the laser light from the reflecting mirror 12 substantially coincides with the center position of the objective lens 5. Set the position.

Next, as shown in FIG. 9C, with respect to the optical pickup device 1, the main body 34 is parallel to the direction in which the objective lens 5 is attached with the reflection mirror 12 attached to the other end of the adsorption member 31. Install. Further, the adjustment mirror light is irradiated to the reflection mirror 12 of the autocollimator, and the measurement position and the set target position are displayed on the monitor. While checking this monitor, the adjustment knobs 32 and 33 of the gonio stage 30 are rotated so that the measurement position substantially coincides with the target position. In addition, by rotating the adjustment knob 32, the reflecting mirror 12 can be moved in the direction indicated by the arrow b or the arrow d in FIG. 7B. Further, by rotating the adjustment knob 33, the reflection mirror 12 can be moved in the direction indicated by the arrow c or the arrow e in FIG. 7B.

Thereby, the angle of the reflecting surface 12a of the reflecting mirror 12 is adjusted to a target angle. Then, UV irradiation is performed on the

adhesion spots

22a, 22b, and 22c in a state where the reflection mirror 12 is adsorbed to the adsorption member 31 of the goniometer 30. When the adhesive is cured by this, the reflection surface 12a of the reflection mirror 12 is adjusted, and the reflection angle of the laser beam with respect to the reflection surface 12a is adjusted. For this reason, the reflection mirror 12 can be attached to the housing 2 so that the optical axis of the laser light from the reflection mirror 12 passes through the approximate center of the objective lens 5.

Here, the case where the angle of the reflecting surface 12a of the reflecting mirror 12 is adjusted so that the optical axis of the laser beam from the reflecting mirror 12 passes through the approximate center of the objective lens 5 has been described. However, for example, when there is a variation in the position of the optical axis of the laser light emitted from the laser light source 6 and the position of the dividing line 8c of the diffraction grating 8, the position of the optical axis of the laser light passing through the diffraction grating 8 Depending on the angle, the angle of the reflecting surface 12a of the reflecting mirror 12 may be adjusted. Thereby, the accuracy of the TE signal can be further increased.

For example, the curve CQ shown in FIG. 5 is the visual field characteristic of the TE signal when the optical axis of the laser beam is shifted to the first region 8a side from the dividing line 8c of the diffraction grating 8, but the objective lens 5 is tracking. The maximum value is shown when the lens moves about -0.1 mm to the-side of the direction Tr. For this reason, the symmetry of the field characteristic of the curve CQ is improved by moving the position of the optical axis of the laser beam passing through the objective lens 5 at the reference position from the center position of the objective lens 5 to, for example, the + side of the tracking direction Tr. Thus, the accuracy of the TE signal can be increased.

Similarly, with respect to the curve CR shown in FIG. 5, the position of the optical axis of the laser light passing through the objective lens 5 at the reference position is moved from the center position of the objective lens 5 to, for example, the minus side in the tracking direction Tr. Can be improved, and the accuracy of the TE signal can be improved.

As described above, the optical pickup device 1 according to this embodiment includes at least the diffraction grating 8 that is interposed on the optical axis between the laser light source 6 and the objective lens 5 and diffracts the laser light emitted from the laser light source 6. And a housing 2 having a first storage chamber 20 in which the diffraction grating 8 is stored. The first storage chamber 20 is orthogonal to a first direction A in which the periodic structure is repeated on the grating surface 82 of the diffraction grating 8. The shape which prohibits the diffraction grating 8 moving to the two directions B should just be exhibited.

According to this optical pickup device 1, the positional relationship between the laser light source 6 and the diffraction grating 8 is considered in advance so that the optical axis of the laser light emitted from the laser light source 6 passes on the dividing line 8 c of the diffraction grating 8. Thus, the first storage chamber 20 is provided in the housing 2. And the holder 7 is accommodated in the 1st storage chamber 20 in the state in which the movement to the 2nd direction B was prohibited. As a result, for example, the holder 7 does not need to be composed of two parts in order to perform the rotation adjustment of the diffraction grating 8 and the position adjustment in the second direction B independently, and the diffraction grating 8 is attached to the housing 2. The number of parts and the work process can be reduced. In addition, since the number of parts can be reduced, the optical pickup device 1 can be reduced in size and the manufacturing cost can be reduced.

Further, in the optical pickup device 1 described above, the leaf spring 17 that applies an elastic force that prohibits the diffraction grating 8 from moving in the optical axis direction C to the diffraction grating 8 accommodated in the first accommodation chamber 20 is provided. I have. According to the optical pickup device 1, the diffraction grating 8 can be fixed in the first storage chamber 20 so as to be rotatable around the optical axis of the laser light and prohibited from moving in the optical axis direction C. Accordingly, it is possible to prevent the diffraction grating 8 from moving in the optical axis direction C with the rotation adjustment of the diffraction grating 8 with a simple configuration and to easily prevent a decrease in the accuracy of the TE signal. it can.

The optical pickup device 1 according to the present embodiment includes at least a diffraction grating 8 that is interposed on the optical axis between the laser light source 6 and the objective lens 5 and diffracts the laser light emitted from the laser light source 6. A reflection mirror 12 interposed on the optical axis between the diffraction grating 8 and the objective lens 5 to reflect the laser light so that the laser light is directed toward the objective lens 5, and a first accommodation chamber 20 in which the diffraction grating 8 is accommodated. And a housing 2 having a second housing chamber 21 in which the reflecting mirror 12 is housed, and the second housing chamber 21 is configured so that the laser beam passes through the substantial center of the objective lens 5 so that the laser light passes through the center. The shape which can adjust the reflection angle of the laser beam with respect to the reflective surface 12a should just be exhibited.

According to the optical pickup device 1, the optical axis of the laser light from the reflection mirror 12 is transmitted through substantially the center of the objective lens 5 in consideration of variations caused by the configuration and assembly of the optical system in the housing 2. The angle of the reflecting surface 12a of the reflecting mirror 12 can be adjusted. That is, the reflection angle of the laser beam with respect to the reflection surface 12a of the reflection mirror 12 can be adjusted. As a result, the number of parts and work steps for attaching the diffraction grating 8 to the housing 2 can be reduced, and the accuracy of the TE signal and the like can be increased.

In the optical pickup device 1 described above, the second storage chamber 21 has at least one of the first direction A in which the periodic structure is repeated on the grating surface 82 of the diffraction grating 8 and the second direction B orthogonal to the first direction A. A shape in which the reflection angle of the laser beam with respect to the reflection surface 12a of the reflection mirror 12 can be adjusted in a direction corresponding to one of them is exhibited.

According to this optical pickup device 1, when there is a variation in the position of the optical axis of the laser light emitted from the laser light source 6 and the position of the dividing line 8 c of the diffraction grating 8, the laser that passes through the diffraction grating 8. The angle of the reflecting surface 12a of the reflecting mirror 12 can be adjusted according to the position of the optical axis of the light. Specifically, the first direction A of the diffraction grating 8 optically corresponds to the tangential direction Tn, and the second direction B of the diffraction grating 8 optically corresponds to the tracking direction Tr. Therefore, for example, when the position through which the optical axis of the laser beam passes in the second direction B of the diffraction grating 8 deviates from the dividing line 8c, the optical axis of the laser beam from the reflection mirror 12 is tracked according to the amount of deviation. The reflecting mirror 12 is moved in the direction indicated by the arrow b or the arrow d in FIG. 7B so as to move in the direction Tr. Thereby, the symmetry of the visual field characteristic of the TE signal can be increased, and the accuracy of the TE signal can be increased.

In the optical pickup device 1 described above, the reflection angle of the laser beam with respect to the reflection surface 12a of the reflection mirror 12 is adjusted by the gonio stage 30. In the optical pickup device 1, the angle of the reflection surface 12 a of the reflection mirror 12 can be easily and easily adjusted using the gonio stage 30 and the autocollimator.

The embodiment described above is for facilitating understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

In the optical pickup device 1 described above, the objective lens holder 4 holds, for example, one objective lens 5 that focuses laser light on the first, second, and / or third optical disc. It is not limited. For example, the objective lens holder 4 includes a first objective lens (not shown) that focuses laser light on first and second optical disks, and a second objective lens (not shown) that focuses laser light on a third optical disk. These two objective lenses may be held, for example, in a state of being arranged substantially along the radial direction of the optical disk, here along the tracking direction Tr. The objective lens holder 4 includes a first objective lens (not shown) for condensing the laser light on the first and second optical disks, and a second objective lens (not shown) for condensing the laser light on the third optical disk. These two objective lenses may be held in a state of being aligned substantially along the tangential direction Tn of the optical disk.

Further, the optical pickup device 1 may not include the optical system for the first optical disc. Further, the optical pickup device 1 may not include the optical system for the second optical disc. Further, the optical pickup device 1 may not include the optical system for the third optical disc.

Further, instead of the two-divided type diffraction grating 8 including the two first regions 8a and the second region 8b, a three-divided type diffraction grating (not shown) including three regions may be used. Further, for example, instead of the two-divided diffraction grating 8 including the two first regions 8a and the second region 8b, a four-divided diffraction grating (not shown) including four regions may be used. As described above, a multi-partition type diffraction grating having a plurality of regions can be used.

DESCRIPTION OF SYMBOLS 1 ... Optical pick-up apparatus, 2 ... Housing, 3 ... Cover, 4 ... Objective lens holder, 5 ... Objective lens, 6 ... Laser light source, 7 ... Holder, 7a ... Outer surface, 8 ... Diffraction grating, 8a ... 1st area | region, 8b 2nd region, 8c ... dividing line, 9 ... polarizing beam splitter, 10 ... 1/4 wavelength plate, 11 ... collimator lens, 12 ... reflecting mirror, 12a ... reflecting surface, 13, 14 ... parallel plate, 15 ... light detection 16 ... light receiving element, 17 ... leaf spring, 17a ... surface, 20 ... first accommodating chamber, 20a ... second wall, 20b ... first wall, 20c, 20d ... notch, 20e, 70 ... cylindrical member 20f ... inner surface, 20g, 21d ... inside, 20h, 21c ... space, 21 ... second storage chamber, 21a, 21b ... wall surface, 22a, 22b, 22c ... adhesion spot, 30 ... gonio stage, 31 ... adsorption member, 32 33 ... Adjustment knob 34 ... main body, 34a ... stage, 80 ... concave part, 81 ... convex part, 82 ... lattice plane, A ... first direction, B ... second direction, C ... optical axis direction, F ... focus direction, L1, L2 ... Length, Tn ... tangential direction, Tr ... tracking direction

Claims

A diffraction grating interposed on the optical axis between the laser light source and the objective lens and diffracting the laser light emitted from the laser light source;
A housing having a storage chamber in which the diffraction grating is stored;
With
The optical pickup device, wherein the storage chamber has a shape that prohibits the diffraction grating from moving in a second direction orthogonal to a first direction in which a periodic structure is repeated on a grating surface of the diffraction grating.
An elastic body that applies elastic force to the diffraction grating accommodated in the accommodation chamber to prohibit the diffraction grating from moving in the optical axis direction;
The optical pickup device according to claim 1, further comprising:
A diffraction grating interposed on the optical axis between the laser light source and the objective lens and diffracting the laser light emitted from the laser light source;
A reflection mirror that is interposed on the optical axis between the diffraction grating and the objective lens and reflects the laser light so that the laser light is directed toward the objective lens;
A first storage chamber in which the diffraction grating is stored; a second storage chamber in which the reflection mirror is stored;
A housing having
With
The second storage chamber has a shape capable of adjusting a reflection angle of the laser light with respect to a reflection surface of the reflection mirror so that the laser light passes through a substantially center of the objective lens. .
The second storage chamber has the reflection mirror reflected in a direction corresponding to at least one of a first direction in which a periodic structure is repeated on a grating surface of the diffraction grating and a second direction orthogonal to the first direction. The optical pickup device according to claim 3, wherein the optical pickup device has a shape capable of adjusting a reflection angle of the laser beam with respect to a surface.
The optical pickup device according to claim 3 or 4, wherein the reflection angle of the laser beam with respect to the reflection surface of the reflection mirror is adjusted by a gonio stage.
A reflection mirror that is interposed on the optical axis between the diffraction grating and the objective lens and reflects the laser light so that the laser light is directed toward the objective lens;
A housing having a storage chamber in which the reflection mirror is stored;
With
The optical pickup device, wherein the storage chamber has a shape capable of adjusting a reflection angle of the laser beam with respect to a reflection surface of the reflection mirror so that the laser beam passes through a substantially center of the objective lens.
The optical pickup device according to claim 6, wherein the reflection angle of the laser light with respect to the reflection surface of the reflection mirror is adjusted by a gonio stage.