JP2014049157A - Laser device and optical pickup device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve highly accurate fine adjustment of a laser beam, which is difficult to achieve because the clearance between a conventional laser device arranged in a housing away from a diffraction grating and the diffraction grating changes.SOLUTION: In a laser device 1, a rotation member 4 to which a diffraction grating 6 is fastened is pressed against and fixed to a side surface 3 of a housing 2 with a leaf spring 5. Movement of the rotation member 4 in an optical axis direction is restricted on the side surface 3, but the rotation member 4 can rotate along the side surface 3. This structure fixes the clearance between the diffraction grating and a light-emitting point of an LD, and further allows rotation adjustment of the diffraction grating 6 after the laser device 1 is fixed to the housing, achieving highly accurate fine adjustment of the laser beam.

Description

  The present invention relates to a laser device that performs recording and / or reproduction using light of a plurality of types of wavelengths, and an optical pickup device using the same.

  As shown in FIG. 7, the conventional optical pickup device 61 is configured to, for example, use a BD (Blu-ray Disc), DVD (Digital Versatile Disk), or CD (Compact Disk) standard laser light for an optical disc (optical information recording medium). It has the function of condensing on the information recording layer, receiving the reflected light from the information recording layer, and converting it into an electrical signal.

  Specifically, the optical pickup device 61 includes a first laser device 62 that emits BD standard laser light, and a second laser device 63 that emits CD or DVD standard laser light. Laser light emitted from the first laser device 62 passes through the first diffraction grating 64, is reflected by the first half mirror 65, and then travels through a common optical path 66. The laser light emitted from the second laser device 63 passes through the second diffraction grating 67 and the second half mirror 68 and travels through a common optical path 66. Each laser beam is reflected by an optical disk (not shown), travels again on a common optical path 66, and is received by a common photodetector 69.

  In the optical pickup device 61, the optical path 66 is made common to the respective laser beams, and the optical elements such as the photodetector 69 are made common, thereby reducing the number of optical elements and realizing miniaturization thereof. (For example, refer to Patent Document 1).

JP 2012-74126 A (page 8-9, FIG. 1)

  As described above, in the conventional optical pickup device 61, for example, after the optical axis adjustment of the BD standard laser light emitted from the first laser device 62 and the spot position adjustment to the optical disc are performed, the second The optical axis adjustment of the laser beam of CD standard or DVD standard emitted from the laser device 63, the spot position adjustment to the optical disk, etc. are performed.

  At this time, in the second laser device 63, the optical axis adjustment and the like are already performed using the photodetector 69 whose position is already fixed in the housing. Since the second laser device 63 is finely adjusted in the XYZ axis direction within the housing, it is not bonded and fixed to the reference surface of the housing. Therefore, the separation distance between the second diffraction grating 67 and the second laser device 63 is likely to fluctuate due to the movement of the position of the second laser device 63. Further, there is a problem that it is difficult to adjust the position of the side spot on the light receiving element or the optical disk due to the variation in the separation distance.

  In particular, the second laser device 63 has a built-in CD standard laser diode and a DVD standard laser diode, and the light emitting points from which the respective laser beams are emitted are different. There is a problem that it is difficult to adjust the spot position on the optical disk.

  It is made in view of each situation described above, and in the laser device of the present invention, a laser element that emits laser light is disposed, and a housing in which an opening is formed in a region through which the laser light passes, A diffraction grating disposed on one main surface side of the casing provided with the opening so as to diffract the laser light, and the diffraction grating rotates along one main surface of the casing The diffraction grating is fixed to the housing after rotation adjustment.

  Further, in the optical pickup device of the present invention, in the optical pickup device that writes data to the optical information recording medium or reads data from the optical information recording medium by at least laser light emitted from the laser device, A laser device is provided.

  In the present invention, the separation distance between the diffraction grating and the light emitting point of the laser diode is fixed by incorporating the diffraction grating on one main surface side of the laser device. Further, even after the laser apparatus is fixed, the rotation of the diffraction grating can be adjusted, and the laser light can be finely adjusted with high accuracy by the stepwise optical adjustment.

  Further, in the present invention, the rotating member to which the diffraction grating is fixed is prevented from shifting with respect to the optical axis direction on one main surface of the laser device, and the laser light can be finely adjusted with high accuracy. .

  Further, in the present invention, the rotating member to which the diffraction grating is fixed rotates without shifting along one main surface of the laser device, so that the laser light can be finely adjusted with high accuracy.

  In the present invention, the rotating member to which the diffraction grating is fixed is prevented from rotating too much along one main surface of the laser device, and the fine adjustment of the laser beam is facilitated.

  In the present invention, the above laser device incorporating a diffraction grating is used in an optical pickup device, so that fine adjustment of the laser light can be performed with high accuracy.

It is a perspective view explaining the laser apparatus in embodiment of this invention. It is a perspective view explaining the laser apparatus in embodiment of this invention. It is the (A) perspective view and (B) perspective view explaining the optical adjustment method of the laser apparatus in embodiment of this invention. It is a figure explaining the characteristic at the time of the optical adjustment of the laser apparatus in embodiment of this invention. It is the schematic explaining the optical system of the optical pick-up apparatus in embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS (A) Perspective view and (B) Perspective view for explaining an optical pickup device in an embodiment of the present invention. It is the schematic explaining the optical system of the optical pick-up apparatus in conventional embodiment.

<First Embodiment>
The laser apparatus according to the present embodiment will be described with reference to FIGS.

  FIG. 1 is a perspective view for explaining a laser device incorporating a diffraction grating. FIG. 2 is a perspective view for explaining a laser device and members incorporated into the laser device. 3A and 3B are perspective views for explaining an optical adjustment method of the laser device. FIG. 4 is a diagram for explaining characteristics of the laser device during optical adjustment.

  In the following description, for example, the paper surface X-axis direction is the horizontal width direction of the laser device (housing width direction), the paper surface Y-axis direction is the laser device vertical width direction (housing height direction), and the paper surface Z-axis direction. The direction is the depth width direction of the laser device (the depth width direction of the housing). The Z-axis direction on the paper surface coincides with the optical axis direction of the optical pickup device.

  As shown in FIG. 1, a laser diode (hereinafter referred to as “LD”) is built in a housing 2 of the laser device 1, and the LD is fixed on a stem (not shown). The side surface 3 of the housing 2 is formed as a plane parallel to the reference plane in the paper plane XY direction, and is a plane perpendicular to the optical axis direction (Z-axis direction). Then, the rotating member 4 is pressed and fixed by the leaf spring 5 so as to come into contact with the side surface 3. With this structure, in the temporarily fixed state by the leaf spring 5, the rotation member 4 is restricted from moving in the optical axis direction (paper surface Z-axis direction), and along the side surface 3 (along the reference surface in the paper surface XY direction). Only) Rotation is possible. The rotating member 4 is bonded and fixed to the housing 2 after adjusting the rotation (after adjusting the spot position on the optical disk).

  The diffraction grating 6 is bonded and fixed to the rotating member 4 and rotates integrally with the rotating member 4. As described above, the movement of the rotating member 4 in the optical axis direction with respect to the laser device 1 is restricted, and the separation distance between the light emitting point of the LD and the diffraction grating 6 in the optical axis direction is fixed to a certain distance.

  A pair of recesses 8 and 9 are disposed on the upper surface 7 of the housing 2. The recesses 8 and 9 are regions into which protrusions (not shown) of the laser device holder (see FIG. 3A) are inserted when the laser device 1 is installed in the housing. As shown in the figure, the recess 8 has a circular cross section and the recess 9 has an oval cross section. But it can respond. And the opening end part of the recessed parts 8 and 9 is made into a taper shape, The operation | work which inserts the said projection part into the recessed parts 8 and 9, and the operation | work extracted from the recessed parts 8 and 9 becomes easy.

  In addition, a recess 10 shallower than the recesses 8 and 9 is disposed between the recesses 8 and 9 of the upper surface 7 of the housing 2. The concave portion 10 is formed by, for example, an eject pin when releasing the housing 2 from the mold, and is disposed in the suction region of the laser device holder.

  Further, as indicated by a circle S, a plurality of concave portions for bonding with the housing are provided on the side surface of the housing 2. By providing an uneven shape in the bonding recess, the surface area as the bonding region is increased, and the bonding strength is improved.

  The upper surface 7 of the housing 2 is formed as a parallel surface of the reference surface in the paper surface ZX direction.

  As shown in FIG. 2, the housing 2 of the laser device 1 is formed by injection molding a metal material such as a zinc alloy, for example. The housing 2 has a hollow structure because the LD is built therein.

  As shown in the figure, a cylindrical opening 11 through which laser light passes is formed on the side surface 3 of the housing 2, and a pair of protrusions 12 and 13 are formed on both sides of the opening 11. . The protrusions 12 and 13 have, for example, a cylindrical shape and protrude in the Z-axis direction on the paper surface. The protrusion 12 is used as a rotation fulcrum member of the rotation member 4, and the protrusion 13 is used as a rotation restriction member of the rotation member 4.

  The rotating member 4 is formed, for example, by injection molding a thermoplastic synthetic resin such as polycarbonate having a lower hardness than the metal material of the housing 2. The front surface 14 and the back surface 15 of the rotating member 4 are formed as parallel surfaces of the reference surface in the paper plane XY direction. Then, the back surface 15 of the rotating member 4 is disposed in contact with the side surface 3 of the housing 2, whereby the reference surface in the paper surface XY direction of the rotating member 4 is fixed.

  A cylindrical opening 16 is formed in the central region of the rotating member 4. When the opening 16 is fixed to the housing 2, the opening 16 is disposed at a position corresponding to the opening 11 of the housing 2. This is the area where light passes.

  The rotating member 4 is formed with a cylindrical opening 17 at a position corresponding to the protrusion 12 of the housing 2. The opening shape of the opening 17 is a circular shape similar to the cross-sectional shape of the protrusion 12, but one end thereof is a D-cut shape.

  As described above, the housing 2 is made of a metal material, and the rotating member 4 is made of a resin material. Thus, when the protrusion 12 of the housing 2 is fitted into the opening 17 of the rotating member 4, The rotating member 4 in the D-cut shape portion is cut. And since the projection part 12 fits in the opening part 17 without gap, the rotation member 4 rotates by using the projection part 12 as a rotation fulcrum, and the rotation position does not shift, and high-precision fine adjustment is possible. It becomes.

  On the other hand, a U-shaped opening 18 is formed in the rotating member 4 at a position corresponding to the protrusion 13 of the housing 2. The rotating member 4 is disposed on the side surface 3 of the housing 2 such that the protrusion 13 is disposed in the opening 18. As described above, the rotating member 4 rotates on the side surface 3 of the housing 2, but the rotating member 4 is prevented from rotating more than necessary by the protrusion 13.

  Next, projecting regions 19 and 20 are formed on the surface 14 of the rotating member 4 in the vertical direction of the paper surface of the opening 16, and a recess 21 between the projecting regions 19 and 20 serves as an arrangement region for the diffraction grating 6. . The surfaces 22 and 23 of the projecting regions 19 and 20 are formed as parallel surfaces of the reference surface in the XZ direction on the paper surface, and the diffraction grating 6 is disposed in contact with the surfaces 22 and 23, so that the diffraction grating 6 The reference plane in the XZ direction is fixed.

  The leaf spring 5 is fitted into the recessed region 24 of the upper surface 7 and the lower surface (not shown) of the housing 2, and the belt-shaped portion that comes into contact with the rotating member 4 is bent, so that the rotating member 4 becomes the housing 2. It is held on the side surface 3 while being pressed to the side.

  As shown in FIGS. 3A and 3B, the position of the laser device 1 is adjusted in the X, Y, and Z directions in the housing while monitoring the output data from the photodetector, and the adjustment of the laser beam in the optical axis direction is performed. And the optical axis azimuth angle θ is adjusted. Thereafter, by rotating and adjusting the diffraction grating 6, it is possible to perform two-stage optical adjustment, and fine adjustment of the laser light with high accuracy is possible.

  First, as shown in FIG. 3 (A), a protrusion (not shown) of a laser device holder 25 is inserted into the recesses 8 and 9 (see FIG. 1) on the upper surface 7 side of the laser device 1, and the upper surface is also combined. 7 is fixed by suction. At this time, the protrusion of the laser device holder 25 is inserted into the recesses 8 and 9, so that the laser device 1 has the reference plane in the XYZ directions fixed to the laser device holder 25. And after arrange | positioning the laser apparatus 1 in the desired position in a housing, the upper surface 7 side is attracted and fixed with the laser apparatus holder 25, and the lower surface side is supported by position adjustment jigs 26, such as an eccentric pin Thus, the laser apparatus 1 is finely adjusted as appropriate in the XYZ axis directions, thereby adjusting the optical axis direction of the laser light and adjusting the optical axis azimuth angle θ.

  After the position of the laser device 1 is determined by the above adjustment, the laser device 1 is bonded and fixed to the housing.

  Next, as shown in FIG. 3B, after the laser device 1 is bonded and fixed to the housing, it is temporarily fixed by the leaf spring 5 by a diffraction grating adjusting jig (not shown) such as an eccentric pin. The rotating member 4 is rotated. Then, as indicated by an arrow 27, the diffraction grating 6 is rotationally adjusted in a direction perpendicular to the optical axis direction, thereby adjusting the side spot position on the optical disc.

  The laser apparatus 1 includes, for example, a DVD standard LD and a CD standard LD, and each LD has a different light emission point. By adjusting the spot position with respect to the final optical disk, the laser light is highly accurate. Fine adjustment is possible.

  At this time, the rotating member 4 is pressed and fixed to the side surface 3 of the housing 2 by the leaf spring 5, so that when the rotating member 4 rotates, the rotating member 4 and the housing 2 are not rotated. A large frictional force works between them. Then, by rotating the rotating member 4 with the diffraction grating adjustment jig in a state where this frictional force is applied, the rotating member 4 is prevented from rotating too much, and a very small amount of rotation adjustment is possible. Become.

  Finally, after the position of the rotating member 4 is determined, the rotating member 4 is bonded and fixed to the laser device 1.

  FIG. 4 is a diagram for explaining the amount of change in the pitch between the side spots on the light receiving element when the laser device is adjusted in the optical axis direction according to the light receiving element bonded and fixed in the housing. The X axis represents the adjustment amount (μm) in the optical axis direction of the laser device, and the Y axis represents the pitch (μm) between the side spots on the light receiving element.

  First, the solid line shows the case where a laser device incorporating a diffraction grating as shown in FIG. 1 is used, and the diffraction grating moves in the optical axis direction integrally with the laser device, and the separation distance between them is always constant. Become.

  As shown in the figure, when the laser device is arranged at a predetermined position in the housing, the design value of the pitch on the light receiving element is 140 μm. When the laser device moved from the predetermined position in the optical axis direction by +0.1 μm, the pitch on the light receiving element was 141.11 μm, which was 1.11 μm wider than the design value. On the other hand, when the laser apparatus moved from the predetermined position in the optical axis direction by −0.1 μm, the pitch on the light receiving element was 138.92 μm, which was narrowed by 1.08 μm from the design value.

  Next, a dotted line is a case where a laser device in which the diffraction grating is fixed to the housing and the diffraction grating is not incorporated is used, and only the laser device moves in the optical axis direction, and the two are separated according to the movement. The distance varies.

  As shown in the figure, when the laser device is arranged at a predetermined position in the housing, the design value of the pitch on the light receiving element is 140 μm. When the laser apparatus moved +0.1 μm from the predetermined position in the optical axis direction, the pitch on the light receiving element was 147.90 μm, which was 7.90 μm wider than the design value. On the other hand, when the laser apparatus moved from the predetermined position in the optical axis direction by −0.1 μm, the pitch on the light receiving element was 132.12 μm, and the pitch was narrowed by 7.88 μm from the design value.

  As described above, the diffraction grating is incorporated in the laser device, and both of them move together, so that the amount of change in pitch on the light receiving element is greatly reduced. And since the amount of change in pitch is reduced, highly accurate fine adjustment of laser light is easily realized, and characteristic deterioration is prevented.

In the present embodiment, the case where the diffraction grating 6 is fixed to the rotating member 4 and the rotating member 4 is fixed to the side surface 3 of the laser device 1 has been described. However, the present invention is not limited to this case. For example, the diffraction grating 6 may be directly fixed to the side surface 3 of the laser device 1 and the diffraction grating itself may be rotationally adjusted. In addition, various modifications can be made without departing from the scope of the present invention.
<Second Embodiment>
With reference to FIGS. 5 and 6, the optical pickup apparatus according to the present embodiment will be described.

  FIG. 5 is a schematic diagram illustrating an optical system of the optical pickup device. 6A and 6B are perspective views illustrating an optical pickup device including the laser device described in the first embodiment. In the description of the present embodiment, the description of the first embodiment is referred to as appropriate.

  As shown in FIG. 5, the optical pickup device 31 is configured to apply BD (Blu-ray Disc), DVD (Digital Versatile Disk) or CD (Compact Disc) standard laser light to an information recording layer of an optical disc (optical information recording medium). It has a function of condensing and receiving the reflected light from the information recording layer and converting it into an electrical signal.

  The optical pickup device 31 includes various optical elements built in the housing. As optical elements, the first and second laser devices 32 and 33, the first and second diffraction gratings 34 and 35, the optical path synthesis prism 36, the half mirror 37, the quarter wavelength plate 38, the collimator lens 39, the first The first and second raising mirrors 40 and 41, the first and second objective lenses 42 and 43, the anamorphic lens 44, and the photodetector 45 are shown.

  The first laser device 32 is a laser beam having a DVD standard wavelength (red wavelength band 645 nm to 675 nm (for example, 655 nm)) and a CD standard wavelength (infrared wavelength band 765 nm to 805 nm (for example, 785 nm)). Is emitted. The first laser device 32 has the same structure as the laser device 1 of the first embodiment described above, and the first laser device 32 has a diffraction grating 34 via a rotating member (not shown). Fixed.

  The laser light emitted from the first laser device 32 is separated into 0th order light, + 1st order diffracted light, and −1st order diffracted light by the first diffraction grating 34, and passes through the optical path synthesis prism 36.

  The second laser device 33 emits laser light having a BD standard wavelength (blue-violet (blue) wavelength band of 400 nm to 420 nm (for example, 405 nm)). The second laser device 33 may be a CAN type package or a lead frame type package.

  Then, the laser light emitted from the second laser device 33 is separated into 0th order light, + 1st order diffracted light, and −1st order diffracted light by the second diffraction grating 35 and reflected by the polarization plane of the optical path combining prism 36. To do.

  As shown in the drawing, the laser light emitted from the first and second laser devices 32 and 33 travels on a common optical path 46 after passing through the optical path combining prism 36. Specifically, each laser beam is reflected by the half mirror 37 and then passes through the quarter-wave plate 38 and the collimator lens 39. The laser light of the DVD standard and the CD standard is reflected by the first rising mirror 40 and condensed on the information recording layer of the optical disc 47 by the first objective lens 42. On the other hand, the BD standard laser light passes through the first rising mirror 40, is reflected by the second rising mirror 41, and is condensed on the information recording layer of the optical disc 47 by the second objective lens 43. The

  Next, the DVD standard and CD standard laser light reflected from the optical disk 47 passes through the first objective lens 42 and is reflected by the first rising mirror 40. On the other hand, the BD standard laser light reflected from the optical disk 47 passes through the second objective lens 43, is reflected by the second raising mirror 41, and passes through the first raising mirror 40. Thereafter, each laser beam passes through a collimator lens 39, a quarter wavelength plate 38, a half mirror 37 and an anamorphic lens 44 and then enters a photodetector (PDIC) 45. Based on the optical signal detected by the photodetector 45, focus control, tracking control, and radial tilt control are performed.

  As described above, in the optical pickup device 31, the optical path 46 is made common to the respective laser beams, and the common optical elements 36 to 39, 44, and 45 are used, thereby reducing the number of optical elements, The miniaturization is realized.

  FIG. 6A shows a perspective view from the upper surface side of the optical pickup device 31. The first laser device 32 is disposed in the housing 48 of the optical pickup device 31, and the second laser device 33 is It arrange | positions in the recessed part 49 provided along the side surface of the housing 48.

  As described in the first embodiment, first, the second laser device 33 that emits BD standard laser light is bonded and fixed to the housing 48. At this time, the side surface in the recess 49 of the housing 48 is formed as a parallel surface of the reference surface in the paper XYZ axial direction, and the second laser device 33 is pressed and fixed to these side surfaces. Thereafter, the second diffraction grating 35 disposed in the housing 48 is rotated and adjusted to adjust the optical axis direction of the BD standard laser beam, the optical axis azimuth θ, and the side spot position on the optical disc. Adjustments are made.

  Next, the first laser device 32 that emits the DVD standard and CD standard laser light is disposed in a desired region 50 of the housing 48. As shown in FIG. 6B, an adjustment hole 51 is arranged at a position corresponding to the region 50 on the lower surface side of the housing 48, and a position adjustment jig (not shown) is inserted into the housing 48 from the adjustment hole 51. Is inserted into. The first laser device 32 is held in a state where the upper surface side of the first laser device 32 is sucked by the laser device holder and the lower surface side of the first laser device 32 is supported by the position adjusting jig. By finely adjusting the position of, the adjustment of the optical axis direction of the laser light of the DVD standard and the CD standard and the adjustment of the optical axis azimuth angle θ are performed.

  Finally, as described with reference to FIG. 3B of the first embodiment, the diffraction grating 34 incorporated in the first laser device 32 is rotated and adjusted in a direction perpendicular to the optical axis direction. As a result, the position of the side spot on the optical disc is adjusted.

  In addition, for a detailed description of a member incorporated in the first laser device 32 such as a rotating member and an adjustment method, refer to the description of FIGS. 1 to 4, and the description thereof is omitted here.

  In the present embodiment, the case where a diffraction grating capable of rotational adjustment is incorporated in the first laser device incorporating the LD of the DVD standard and the CD standard has been described. However, the present invention is not limited to this case. For example, a structure in which a diffraction grating capable of rotation adjustment is incorporated in a second laser device incorporating a BD-standard LD and a diffraction grating is not incorporated in the first laser device may be employed. In this case, the same effect can be obtained by first bonding and fixing the first laser device to the housing and then placing the second laser device in the housing with fine adjustment as described above. It is done. In addition, various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Laser apparatus 2 Housing | casing 4 Rotating member 5 Leaf spring 6 Diffraction grating 8 Concave part 9 Concave part 12 Protruding part 13 Protruding part 17 Opening part 18 Opening part 25 Laser apparatus holder 31 Optical pick-up apparatus 32 1st laser apparatus 33 2nd Laser equipment 34 First diffraction grating 45 Photodetector

Claims (6)

A housing in which a laser element that emits laser light is arranged and an opening is formed in a region through which the laser light passes;
A diffraction grating disposed on one main surface side of the casing provided with the opening so as to diffract the laser beam;
The said diffraction grating rotates along one main surface of the said housing | casing, The said diffraction grating is fixed with respect to the said housing | casing after rotation adjustment.   The diffraction grating is fixed to a rotating member, and the rotating member is pressed and fixed to one main surface of the casing by an elastic member, and the rotating member rotates along one main surface of the casing. The laser device according to claim 1, wherein: The main surface of the housing is provided with first and second protrusions so as to sandwich the opening, and the rotating member is provided with a rotation fulcrum opening.
The laser device according to claim 2, wherein the rotation fulcrum opening is fitted to the first protrusion, and the first protrusion serves as a rotation fulcrum of the rotating member.   The laser device according to claim 3, wherein the rotation member is provided with a rotation restricting opening, and the second protrusion is disposed in the rotation restricting opening. The casing is made of a metal material, and the rotating member is made of a material having a lower hardness than the metal material,
The said 1st projection part is a column shape, The said opening part for rotation fulcrum is a shape where a part of circular shape corresponding to the said column shape was notched, The Claim 3 or Claim 4 characterized by the above-mentioned. The laser device described in 1. In an optical pickup device for writing data to an optical information recording medium or reading data from the optical information recording medium by at least laser light emitted from the laser device,
6. The optical pickup device according to claim 1, wherein the laser device is the laser device according to any one of claims 1 to 5.

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