JP2005115987A - Optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup for preventing control stability from being lost, since the transmission of vibration to a pickup case is minimized, and since the adjustment precision is improved by reducing the light axis adjustment time of an objective lens. <P>SOLUTION: The inclination of an actuator 2 for retaining an objective lens 11 can be adjusted to a required angle in two directions, namely the radius and tangential directions of a disk. Further, the actuator 2 is mounted onto the pickup case 1 via an elastic member 4 so that no cross actions occurs between the radius direction and the tangential direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical pickup used in an optical recording / reproducing apparatus for recording / reproducing signals on / from a disk such as a CD or a DVD.

  An optical pickup device is an information recording / reproducing device characterized by non-contact, large capacity, high-speed access, and low-cost media. Utilizing these features, the optical pickup device can be used as a recording / reproducing device for digital audio signals and digital video signals, or for a computer. It is used as an external storage device.

  Each of the optical pickups mounted on such an optical pickup device condenses laser light emitted from a laser light source on a disk with an objective lens and receives light corresponding to a signal on the disk with a light receiving element. It is converted into a signal and transmitted to an external electric circuit.

  Hereinafter, the configuration of a conventional optical pickup will be described with reference to FIGS. 4A and 4B with reference to the drawings.

  Reference numeral 11 denotes an objective lens, which is fixed to a holder for holding the objective lens by adhesion or the like. Below the objective lens 11, there is a diffraction grating for dividing the return light from the disk into several lights and guiding them to a predetermined position of the light receiving element, and is held in the holder together with the objective lens 11. A focus coil and a tracking coil are fixed to the holder by adhesion or the like so that the objective lens 11 can be driven in the focus direction and the tracking direction. The holder is elastically held by a wire, and one end of the wire is fixedly supported by means such as solder on a substrate attached to the suspension holder.

  The suspension holder is fixed on the yoke by adhesion or the like. A magnet for generating a magnetic field in the focus coil and tracking coil is disposed on the yoke 3 to form a magnetic circuit, and the actuator 2 is configured as a whole. Further, four throttle portions 3m, 3n, 3p, and 3q are provided on the bottom surface of the yoke 3. The four aperture portions are formed by sheet metal pressing so that the yoke 3 has a spherical shape centered on the principal point 12 of the objective lens 11.

  The optical system includes a hologram unit 9 in which a light source that emits a laser beam, a light receiving element that receives return light from the disk, and a hologram element are integrated. The hologram unit 9 is attached to the holo holder 10 by bonding or the like. It is fixed. After the adjustment, the holo holder 10 is fixed to the pickup case 1 by adhesion or the like. Further, the light source 13 includes a light source 13 having another wavelength, an optical lens system (not shown), and a light receiving element 14 that receives return light from the disk. The above optical system is fixed to the pickup case 1 after adjustment by adhesion or the like.

  On the pickup case 1, four seating surfaces 1m, 1n, 1p, 1q for receiving the throttle portions 3m, 3n, 3p, 3q of the yoke 3 shown in FIG. Is slidable. Further, the ita spring 5 is fixed on the pickup case 1 with a screw 6, and the tip of the ita spring 5 is engaged with the X portion of the yoke 3. The yoke 3 is provided with two screw holes 3r and 3t, and is fixed by screws R7 and T8 passed through the two through holes 1r and 1t of the pickup case 1.

  The light emitted from the light source is adjusted so as to rise vertically with respect to the pickup case 1 by the optical lens. In order to ensure the performance of the optical pickup device, tilt adjustment is performed to align the optical axis of the objective lens 11 with the light rising vertically.

  The tilt adjustment is performed with the screws R7 and T8, and the optical axis in the radial direction of the disk can be adjusted by rotating the screw R7, and the optical axis in the tangential direction of the disk can be adjusted by rotating the screw T8.

JP 11-154332 A (FIGS. 1 and 2)

Japanese Patent Laid-Open No. 2002-50058 (FIGS. 5, 6, and 7)

  However, the above conventional optical pickup still has the following problems to be solved in adjusting the tilt of the objective lens 11.

  One is that when the optical axis of the objective lens 11 is adjusted again, the screw R7 and the screw T8 are rotated, so that a cross action occurs and adjustment takes time. In other words, after aligning the radial axis with the screw R7 and then trying to align the tangential optical axis with the screw T8, the radial optical axis will be misaligned due to cross action, and the radial direction will be aligned again. Therefore, there is a problem that adjustment time increases.

  One is that there is no restriction in the rotation direction around the optical axis of the objective lens 11, so that a rotation direction deviation occurs after adjustment, and a three-spot position deviation (angle deviation), which is a tracking control signal, or an objective lens 11 causes an angle shift in the dividing line of the diffraction grating held below 11, resulting in performance deterioration.

  Furthermore, the other is that the drive source of the movable part of the actuator 2 serves as an excitation source, and vibrations are transmitted to the magnet, the yoke 3 and the pickup case 1, causing the optical components on the pickup case to vibrate. In other words, the frequency characteristic of the signal necessary for control cannot be obtained due to the vibration of the optical component, and there is a problem that the control is hindered.

  The first object of the present invention is to solve this problem, so that even if the tilt adjustment of the actuator holding the objective lens is performed, no deviation occurs in the rotational direction around the optical axis passing through the objective lens. Another object of the present invention is to provide an optical pickup device.

  A second object of the present invention is to provide an optical pickup device that can prevent vibration generated by an actuator from being transmitted to a pickup case.

  In order to achieve the above object, the present invention provides a light source that emits a laser beam, an optical means composed of a laser unit in which a light receiving element that receives return light and a hologram element are integrated, and radiation from the light source. An objective lens that focuses the laser beam on the optical disc and emits return light obtained from the disc toward the light receiving element, a focus coil and a tracking coil that drive the objective lens in a focus direction and a tracking direction, A magnetic circuit comprising a magnet and a yoke for supplying a magnetic field to the focus coil and the tracking coil, actuator means for supporting the objective lens and the coils so as to move together, the light source, the optical means, and the actuator means And the radius of the optical disk mounted with the magnetic circuit A pickup case configured to be movable in the direction of the optical disc, and the actuator means can be tilted and adjusted to a required angle in two directions of a radial direction and a tangential direction of the optical disc, and further, between the radial direction and the tangential direction. The optical pickup device is mounted on the pickup case via an elastic member so that no cross action occurs between them.

  In the elastic member, the elastic member has a first arc surface having a first dimension centered on a principal point of the objective lens on a surface side in sliding contact with the actuator means, and is slid on the pickup case. A second arc surface having a second dimension centered on the principal point of the objective lens is provided on the back surface side in contact with the first arc surface in a direction perpendicular to the first arc surface.

  Further, the present invention engages the first guide groove and the first convex portion between the first arc surface of the actuator means and the first arc surface on the surface side of the elastic member. And restricting in the first tilt direction along the first arc surface, between the second arc surface on the back surface side of the elastic member and the second arc surface of the pickup case, the second The convex portion and the second guide groove are engaged to restrict the second tilt direction along the second arc surface.

  In addition, the present invention is characterized in that the elastic member is made of LCP (liquid crystal polymer) or foam molded plastic.

  As described above, according to the present invention, when adjusting the optical axis of the objective lens, the adjustment time and the adjustment accuracy can be improved because a cross action is not generated between the focus direction and the tracking direction.

  In addition, according to the present invention, the displacement in the rotational direction with respect to the optical axis of the objective lens can be suppressed from the assembly stage, and no rotational displacement occurs even after the adjustment. (Angle misalignment) and no angle misalignment occur in the dividing line of the diffraction grating held under the objective lens, and performance degradation is eliminated.

  Further, according to the present invention, the elastic member arranged between the yoke and the pickup case can absorb the vibration generated by the actuator and minimize the transmission of vibration to the pickup case. can get.

  An embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram showing a main part of an optical pickup according to an embodiment of the present invention. 2 is a plan view of the optical pickup according to the embodiment of the present invention, and FIG. 3 is an explanatory view of a tilt mechanism of the optical pickup according to the embodiment of the present invention.

  The optical disc apparatus is configured to be movable in the radial direction of the optical disc by engaging a pickup case 1 constituting the optical pickup device with a support shaft and a guide shaft disposed on a base.

  1, 2, and 3, the objective lens 11 is fixed to an objective lens holder 15 that holds the objective lens by bonding or the like. Below the objective lens 11 is a diffraction grating 16 for dividing the return light from the disk into several light beams and guiding them to a predetermined position of the light receiving element. The diffraction grating 16 together with the objective lens 11 is an objective lens holder 15. Is held in. A focus coil 17 and a tracking coil 18 are fixed to the objective lens holder 15 by bonding or the like so that the objective lens 11 can be driven in the focus direction and the tracking direction. The objective lens holder 15 is elastically held by a wire 19 and is fixedly supported so that one end of the wire 19 can be conducted to a substrate attached to the suspension holder 20 by means such as solder. That is, the suspension holder 20 fixes the objective lens 11, the focus coil 17, the tracking coil 18, and the like via four wires 19 provided at, for example, four locations so that the objective lens 11 can be driven in the focus direction and the tracking direction. The objective lens holder 15 is held. Then, for example, the four wires 19 and the focus coil 17 and the tracking coil 18 are electrically connected by means such as solder, and the other end of the four wires 19 and the substrate attached to the suspension holder 20, for example. Is made conductive between the focus coil 17 and the tracking coil 18 by means of solder or the like.

  Further, the suspension holder 20 is fixed on the yoke 3 by adhesion or the like. A magnet 21 for generating a magnetic field in the focus coil 17 and the tracking coil 18 is disposed opposite to the yoke 3 to form a magnetic circuit.

  The actuator 2 is configured as a whole. On the other hand, the actuator means is constituted by a suspension holder 20 fixed on the yoke 3 that supports the objective lens 11, the focus coil 17 and the tracking coil 18 so as to be movable together.

  Further, as shown in FIG. 3, there are two throttle portions on the bottom surface of the yoke 3 which is a base material of the actuator means (suspension holder 20), and these throttle portions have an arcuate surface (Y) 3a. 3b and convex portions (Y) 3c, 3d. The arcuate surfaces (Y) 3a and 3b of these apertures are formed by sheet metal pressing the yoke 3 so as to have a cylindrical surface shape with the principal point 12 of the objective lens 11 as the center.

  The optical system includes a light source that emits a laser beam, a light receiving element that receives return light from the disk, and a hologram unit 9 in which the hologram element is integrated. The hologram unit 9 is fixed to the holo holder 10 by adhesion or the like. After the adjustment, the holo holder 10 is fixed to the pickup case 1 by adhesion or the like. Furthermore, as another optical system, a light source 13 having a different wavelength, an optical lens system (not shown), and a light receiving element 14 for receiving return light from the disk are provided. The optical system described above is fixed to the pickup case 1 after adjustment by adhesion or the like.

  Next, an embodiment that characterizes the present invention will be described. First, as shown in FIGS. 1 and 3, in order to adjust the tilt angle of the objective lens 11 with respect to the optical axis, the objective is tangential to the surface side (A) (Tan direction perpendicular to the moving direction of the optical pickup). Arc surfaces (A) 4a and 4b and grooves (A) 4c and 4d for tilting the yoke 3 on which the lens 11 is disposed are formed, and the rear surface side (B) is in the radial direction (Rad direction which is the moving direction of the optical pickup). ) Are formed with arcuate surfaces (B) 4e, 4f and convex portions (B) 4g, 4h, and arcuate surfaces (P) 1a, 1b and grooves (P ) 1c and 1d are configured to be tiltable in the radial direction. Further, the elastic member 4 is made of a material (for example, LCP (liquid crystal polymer), foam molded plastic) that absorbs vibration generated by the actuator 2 and minimizes vibration transmission to the pickup case 1. However, the arc surfaces (A) 4a and 4b and the arc surfaces (B) 4e and 4f are sliding surfaces, and the groove portions (A) 4c and 4d and the convex portions (B) 4g and 4h are guide portions (guide portions). As such, these surfaces and portions may be formed of hard surfaces.

  As shown in FIG. 3A, the arc surfaces (Y) 3 a and 3 b of the yoke (Y) 3 that supports the actuator 2 having the objective lens 11 are formed on the surface side (A) of the elastic member 4. The arcuate surfaces (A) 4a and 4b are configured to be slidable. The radii of curvature of the arcuate surfaces (A) 4 a and 4 b are the same as the radii of curvature of the arcuate surfaces (Y) 3 a and 3 b of the yoke 3, and the center thereof is the principal point 12 position of the objective lens 11. The arcuate surfaces (A) 4a and 4b of the elastic member 4 engage with the projections (Y) 3c and 3d of the yoke 3 to guide in the tangential direction (the tilt of the yoke 3 is restricted in the tangential direction). For this purpose, the objective lens 11 disposed on the yoke 3 is configured to be tiltable in the tangential direction (tangential direction) of the disk.

  Further, as shown in FIG. 3B, on the back surface side (B) of the elastic member 4, a direction perpendicular to the direction of the arcuate surfaces (A) 4a and 4b, that is, the radial direction (radial direction) of the disk. Are formed with arcuate surfaces (B) 4e and 4f, and the arcuate surfaces (B) 4e and 4f have convex portions (B) 4g and 4h, respectively.

  As shown in FIG. 1, on the pickup case 1, arcuate surfaces (P) 1a, 1b are slidably contacted with arcuate surfaces (B) 4e, 4f formed on the back side (B) of the elastic member 4. Each of the circular arc surfaces (P) 1a and 1b is engaged with the convex portions (B) 4g and 4h of the elastic member 4 and guided in the radial direction (the inclination of the elastic member 4 is changed in the radial direction). Grooves (P) 1c and 1d (for restriction) are formed, and the elastic member 4 can tilt in the radial direction. At this time, the radii of curvature of the arcuate surfaces (B) 4 e and 4 f of the elastic member 4 and the arcuate surfaces (P) 1 a and 1 b of the pickup case 1 are the same, and the center thereof is the principal point 12 position of the objective lens 11.

  The ita spring 5 is fixed on the pickup case 1 with a screw 6 and the tip of the ita spring 5 is engaged with the X portion of the yoke 3 so as to urge the yoke 3 toward the pickup case 1 side. The yoke 3 is provided with two screw portions 3r and 3t, and the elastic member 4 is sandwiched by the spring force of the screws R7 and T8 and the ita spring 5 passed through the two through holes 1r and 1t of the pickup case 1. In this manner, the entire actuator 2 is pressed against the pickup case 1.

  The light emitted from the light source is adjusted so as to rise vertically with respect to the pickup case 1 by an optical lens (not shown). In order to ensure the performance of the optical pickup device, tilt adjustment is performed to align the optical axis of the objective lens 11 with the light rising vertically.

  The tilt adjustment in the radial direction is performed with the screw R7, and the tilt adjustment in the tangential direction is performed with the screw T8. In this manner, the optical axis in the radial direction of the disk can be adjusted by rotating the screw R7, and the optical axis in the tangential direction of the disk can be adjusted by rotating the screw T8. For example, when the screw R7 is rotated, the yoke 3 slides on the arcuate surfaces (A) 4a and 4b of the elastic member 4 along the guide grooves (A) 4c and 4d, and the objective lens 11 moves in the tangential direction. Will tilt. When the screw T8 is rotated, the elastic member 4 is integrated with the actuator 2 and slides on the circular arc surfaces (P) 1a and 1b on the pickup case 1 along the guide grooves (P) 1c and 1d. The objective lens 11 is tilted in the radial direction.

  As described above, the guide grooves 4c and 4d in the tangential direction or the radial direction between the yoke 3 and the surface side of the elastic member 4 and the protrusions 3c and 3d engaged with the guide grooves are provided. And providing the groove portions 1c and 1d for guiding in the radial direction or the tangential direction and the convex portions 4g and 4h engaged with the guiding groove portions between the back surface side of the elastic member 4 and the pickup case 1. As a result, no cross action occurs between the radial direction and the tangential direction when the objective lens 11 is tilted, and the adjustment time and the adjustment accuracy are improved. Further, since the deviation in the rotation direction with respect to the optical axis of the objective lens 11 can be suppressed from the assembly stage and no rotation deviation occurs even after the adjustment, the positional deviation (angle deviation) of the three spots as the tracking control signal or In addition, there is no angle deviation in the dividing line of the diffraction grating held under the objective lens 11, and performance degradation is eliminated.

  3A and 3B show the curvature radii and arc centers of the arcuate surfaces (Y) 3a and 3b of the yoke 3 and the arcuate surfaces (A) 4a and 4b, arcuate surfaces (B) 4e and 4f of the elastic member 4, respectively. This shows the relationship. By setting the center of each arc as the principal point position of the objective lens 11, it can be configured so that the optical performance is not affected even if the inclination of the objective lens 11 changes during adjustment.

  Furthermore, since the elastic member 4 between the yoke 3 and the pickup case 1 can absorb the vibration generated by the actuator 2 and the vibration transmission to the pickup case 1 can be minimized, a good frequency characteristic can be obtained.

  Further, the present invention relates to the adjustment of the lens optical axis tilt of the objective lens, and the system of the optical system is not limited to the above embodiment.

  According to the present embodiment described above, adjustment time and adjustment accuracy are improved because the optical axis of the objective lens can be adjusted without causing a cross action between the focus direction and the tracking direction.

  Further, according to the present embodiment, the deviation in the rotation direction with respect to the optical axis of the objective lens can be suppressed from the assembly stage, and no rotation deviation occurs even after adjustment. There is no positional deviation (angle deviation) or angular deviation in the diffraction grating division line held under the objective lens, and performance degradation is eliminated.

  In addition, according to the present embodiment, the elastic member disposed between the yoke and the pickup case can absorb vibration generated by the actuator and minimize vibration transmission to the pickup case. Characteristics are obtained.

1 is an exploded perspective view showing a schematic configuration of an embodiment of an optical pickup device according to the present invention. It is a top view which shows one Embodiment of the optical pick-up apparatus which concerns on this invention. 1 is a cross-sectional view of a yoke and an elastic member showing an embodiment of an optical pickup device according to the present invention, where (a) shows tilt adjustment in the tangential direction (Tan direction), and (b) shows radial direction (Rad direction). It is a figure which shows no tilt adjustment. It is a figure which shows schematic structure of the conventional optical pick-up apparatus, (a) shows the disassembled perspective view, (b) is the perspective view which looked at the pickup case from the back side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pick-up case, 1a, 1b ... Arc surface (P), 1c, 1d ... Groove part (P), 1r, 1t ... Through-hole, 2 ... Actuator, 3 ... Yoke, 3a, 3b ... Arc surface (Y), 3c 3d ... convex part (Y), 3r, 3t ... screw part, 4 ... elastic member, 4a, 4b ... arc surface (A), 4c, 4d ... groove part (A), 4e, 4f ... arc surface (B), 4g, 4h ... convex part (B), 5 ... Ita spring, 6 ... screw, 7 ... screw R, 8 ... screw T, 9 ... hologram unit, 10 ... holo holder, 12 ... principal point, 13 ... light source, 14 ... light reception Element: 15 ... Objective lens holder, 16 ... Diffraction grating, 17 ... Focus coil, 18 ... Tracking coil, 19 ... Wire, 20 ... Suspension holder, 21 ... Magnet.

Claims (5)

A light source that emits a laser beam;
Optical means composed of a laser unit in which a light receiving element for receiving return light and a hologram element are integrated;
An objective lens for condensing the laser beam emitted from the light source onto the optical disc and emitting return light obtained from the disc toward the light receiving element;
A focus coil and a tracking coil for driving the objective lens in a focus direction and a tracking direction;
A magnetic circuit comprising a magnet and a yoke for supplying a magnetic field to the focus coil and the tracking coil;
Actuator means for supporting the objective lens and the coils so as to be movable together;
A pickup case mounted with the light source, the optical means, the actuator means and the magnetic circuit and configured to be movable in the radial direction of the optical disc;
The actuator means can be adjusted to be tilted to a required angle in two directions of the optical disk in a radial direction and a tangential direction, and further, an elastic member is interposed so that no cross action occurs between the radial direction and the tangential direction. And an optical pickup device mounted on the pickup case.   The elastic member has a first arcuate surface having a first dimension centered on the principal point of the objective lens on the surface side in sliding contact with the actuator means, and the first surface on the back side in sliding contact with the pickup case. 2. The optical pickup device according to claim 1, further comprising a second arc surface having a second dimension centering on a principal point of the objective lens in a direction perpendicular to the one arc surface.   The first guide groove and the first convex portion are engaged between the first arc surface of the actuator means and the first arc surface on the surface side of the elastic member to The first convex direction is restricted between the second arcuate surface on the back surface side of the elastic member and the second arcuate surface of the pickup case. 3. The optical pickup device according to claim 2, wherein the second guide groove is engaged to be regulated in a second tilt direction along the second arc surface. 4.   4. The optical pickup device according to claim 1, wherein the elastic member is made of LCP (liquid crystal polymer). 4. The optical pickup device according to claim 1, wherein a material of the elastic member is made of foam molded plastic.

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