JP2007250050A - Optical head and optical recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress resonance of an optical head without obstructing efficient mass productivity even when the optical head is made compact. <P>SOLUTION: The optical head 1 has an objective lens drive 2 driving an objective lens 12, a housing 3 supporting the objective lens drive 2 and a cover 4 having an aperture part 4a for exposing the objective lens 12 and a yoke 14 positioned in the vicinity of the objective lens 12 in a state in which the objective lens drive 2 is supported by the housing 3. The cover 4 is joined to the housing 3 and joined to the yoke 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical head for recording or reproducing data on an optical recording medium such as an optical disk, and an optical recording / reproducing apparatus including the optical head.

  A conventional optical head includes a lens holder that holds an objective lens and is movable in a tracking direction and a focusing direction, a drive coil fixed to the lens holder, a drive magnet disposed to face the drive coil, and the above And an objective lens actuator including an inner yoke disposed opposite the drive magnet with the drive coil interposed therebetween. In this optical head, in order to forcibly prevent the resonance of the inner yoke, a tenon formed at the free end of the leg portion of the inner yoke is press-fitted into a tenon hole formed in a cover provided in the actuator. (For example, refer to Patent Document 1). Hereinafter, this technique is referred to as a first conventional example.

  The conventional optical head is provided with a holder having an objective lens fixed and a coil fixed outside, and two sets of inner yoke and outer yoke so as to face each other through the coil, and Some have an objective lens driving device including a base body in which a holder is displaceably supported, a permanent magnet fixed to the outer yoke, and energization means for energizing the coil to apply a magnetic field. In this objective lens driving device, at least the holder circumference is covered with a cover made of a magnetic material that connects the upper ends of the two sets of inner and outer yokes and has an opening formed in a portion corresponding to the objective lens. Yes. In the cover, a portion where the inner yoke and the outer yoke are contacted is formed of a magnetic material, and the other portion is formed of a resin material, and the magnetic material and the resin material are joined by an adhesive ( For example, see Patent Document 2.) Hereinafter, this technique is referred to as a second conventional example.

  Further, the actuator constituting the conventional optical head includes a pair of yokes projecting perpendicularly to the end of the base, a magnet disposed between the pair of yokes and fixed to the inner surface of one of the yokes, A protective cover that covers the pair of yokes from above and is fitted to the outer peripheral edge of the base, and an auxiliary base that is fixed to the upper inner surface of the protective cover and that covers the entire open end of the pair of yokes. Yes. The auxiliary base is made of synthetic resin and fixed to the inside of a box-shaped protective cover. By applying this protective cover to the base, the auxiliary base covers the pair of yokes, magnets, and air gaps. (For example, refer to Patent Document 3). Hereinafter, this technique is referred to as a third conventional example.

Japanese Patent Laying-Open No. 2005-4884 (Claims, [0018] to [0026], abstract, FIG. 3) JP-A-6-301993 (Claim 1, Claim 3, [0003] to [0007], [0022] to [0027], FIGS. 1 and 4) Japanese Utility Model Publication No. 5-31692 (Claim 1, column 3, line 28 to column 4, line 9, FIG. 1)

  In the first conventional example described above, a tenon formed at the free end of the leg portion of the inner yoke is press-fitted into a tenon hole formed in a cover provided in the actuator. However, the smaller the optical head is, the smaller the shape of the horn to be formed at the free end of the leg portion of the inner yoke made of a magnetic material or the like. There is also a problem of hindering efficient mass productivity because accuracy in assembly is also required. Further, the first conventional example described above has a problem that even if the resonance of the inner yoke can be suppressed, the resonance of the entire optical head cannot be suppressed.

  In the above-described second conventional example, the magnetic material and the resin material constituting the cover are joined with an adhesive. However, the cover is only fixed to the base body by being attracted by the magnetic force of the permanent magnet fixed to the outer yoke, and is not integrated with the inner yoke and the outer yoke. There was a problem that not only the resonance of the inner yoke but also the resonance of the entire optical head could not be suppressed.

Similarly, in the third conventional example described above, the pair of yokes and the protective cover having the auxiliary base fixed to the upper inner surface are not integrated. There was a problem that the entire resonance could not be suppressed.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an optical head and an optical recording / reproducing apparatus capable of solving the above-described problems.

  In order to solve the above-mentioned problems, an optical head according to a first aspect of the present invention includes an objective lens driving device that drives an objective lens, a housing that supports the objective lens driving device, and the objective lens driving device that is the housing. A cover formed with an opening for exposing the objective lens and components of the objective lens driving device located in the vicinity of the objective lens. It is joined and it is joined with the said component of the said objective-lens drive device.

  The invention according to claim 2 relates to the optical head according to claim 1, wherein the cover has the objective lens driving device at a position of the opening facing the component of the objective lens driving device. In the vicinity of the component, a joint is integrally formed, and the end of the joint is processed to increase the strength of adhesion with the component of the objective lens driving device. It is characterized by having.

  According to a third aspect of the present invention, an optical recording / reproducing apparatus includes the optical head according to the first or second aspect.

  According to the present invention, the optical head according to the first aspect of the present invention includes an objective lens driving device that drives the objective lens, a housing that supports the objective lens driving device, and a state in which the objective lens driving device is supported by the housing. The objective lens and a cover formed with an opening for exposing the components of the objective lens driving device located in the vicinity of the objective lens, the cover is joined to the housing, and the objective lens driving device When the optical head is miniaturized, the resonance of the optical head can be suppressed without hindering efficient mass productivity.

  According to the present invention, an optical recording / reproducing apparatus according to a third aspect of the invention includes the optical head according to the first or second aspect. Therefore, in this optical recording / reproducing apparatus, the resonance of the entire optical head is suppressed and the tracking servo is stabilized.

Embodiment 1 FIG.
1 is a partially enlarged perspective view showing an external configuration of an optical head 1 according to Embodiment 1 of the present invention, FIG. 2 is a perspective view showing an external configuration of the optical head 1 shown in FIG. 1, and FIG. FIG. 4 is an exploded perspective view showing the external configuration of the optical head 1 shown in FIG. 1. FIG. 4 is a perspective view of the external configuration of the optical head 1 shown in FIG. The optical head 1 in this example is schematically constituted by an objective lens driving device 2, a housing 3, and a cover 4.

  As shown in FIG. 4, the objective lens driving device 2 has an objective lens 12 fixed to a lens holder 11 with an adhesive or the like, and drives the objective lens 12 in a focus direction and a tracking direction. A permanent magnet 13 and a yoke 14 that constitute a magnetic circuit are disposed in a through-hole 11a formed substantially at the center of the lens holder 11. In addition, a focusing coil 15 and a tracking coil 16 are provided in the penetrating portion 11 a of the lens holder 11.

  The housing 3 is made of, for example, a metal such as aluminum (Al), zinc (Zn), or magnesium (Mg), or a synthetic resin such as liquid crystal polymer (LCP). The housing 3 is formed with a penetrating portion 3a that is substantially similar to the outer peripheral shape of the objective lens driving device 2 and into which the objective lens driving device 2 is loosely fitted. As shown in FIG. 5, the objective lens driving device 2 is loosely fitted into the through-hole 3 a of the housing 3, and the housing 3 is located at several places on the upper peripheral edge 3 aa of the through-hole 3 a and below the through-hole 3 a It is fixed by an adhesive or the like (not shown) at several places on the peripheral edge 3ab (see FIG. 3). Thereby, the housing 3 supports the objective lens driving device 2.

  Although not shown in the figure, the optical path of the light beam emitted from the laser diode is changed to be emitted from the objective lens 12, and the light beam incident from the objective lens 12 is made of a photodiode or the like. An optical system including a beam splitter, a collimating lens, and the like for focusing on the light receiving surface of the detector is provided.

  The cover 4 is made of, for example, a metal such as stainless steel or a synthetic resin. The main purpose of the cover 4 is to prevent dust from entering the objective lens driving device 2 and the housing 3 by covering the upper peripheral edge of the objective lens driving device 2 and the upper and side portions of the housing 3. It is. When the cover 4 is made of a metal such as stainless steel, the thickness of the cover 4 is, for example, 0.15 to 0.25 mm in consideration of the distance from the optical recording medium. In the cover 4, an opening 4 a is formed at a substantially central portion facing the installation position of the objective lens driving device 2 supported by the housing 3.

  The cover 4 drives the objective lens so that the objective lens 12 and the upper part 14a of the yoke 14 are slightly exposed from the opening 4a in a state where the objective lens drive device 2 is supported by the housing 3. The upper surfaces of the device 2 and the housing 3 and the side surfaces (not shown) of the housing 3 are covered. Although not shown, the cover 4 is fixed to several places on the upper surface of the housing 3 with screws, hooks, or an adhesive. In addition, the cover 4 has a hanging portion 4c opposed to the side surface of the housing 3 integrally formed with the flat portion 4b, and is fixed to several locations on the side surface of the housing 3 by screws, hooks, or adhesive.

  As shown in FIGS. 1 and 4, a joint 4 aa is formed in the opening 4 a of the cover 4 at a position close to the upper part 14 a of the yoke 14 constituting the objective lens driving device 2. The joint 4aa is bent acutely toward the lower surface side of the cover 4 from the connecting portion with the flat portion 4b of the cover 4 toward the center of the opening 4a, and then bent acutely at the upper surface side of the cover 4. ing. The end of the joint 4aa is processed into a substantially V shape, a substantially U shape, or a substantially wave shape at a predetermined interval. As shown in FIG. 1, the bonding portion 4aa is bonded to the upper corner portion 14ab of the yoke 14 with an adhesive 5. The end portion of the joint 4aa is processed to increase the adhesive strength of the adhesive 5.

  The adhesive 5 is, for example, epoxy, cyanoacrylate, polyurethane, urea resin, melamine resin, phenol resin, vinyl acetate resin, synthetic rubber, chloroprene rubber solvent, synthetic rubber latex, There are pressure sensitive, emulsion type, hot melt type, elastomer hot melt type, polyamide hot melt type and the like. The hardness of the adhesive 5 is, for example, a Shore A hardness of 30 to 50. When the adhesive 5 is applied to the joint 4aa and the upper corner portion 14ab of the yoke 14, the width of the joint 4aa is 3 minutes so that the adhesive 5 does not rise above the upper surface of the flat portion 4b of the cover 4. Apply to 2 or more of the above.

  FIG. 6 shows an example of phase characteristics in the open loop in the tracking direction of the optical head 1 having the above configuration (after countermeasures: solid line), and the upper corner of the joint 4aa of the cover 4 and the yoke 14 in the optical head 1 having the above configuration. It is a figure which shows an example (before countermeasure: broken line) of the phase characteristic in the open loop of the tracking direction at the time of not joining part 14ab. As can be seen from FIG. 6, in the optical head 1, when the joint 4aa of the cover 4 and the upper corner 14ab of the yoke 14 are joined, resonance of the entire optical head 1 at about 6 kHz can be suppressed. On the other hand, the gain characteristics in the open loop in the tracking direction of the optical head 1 having the above-described configuration are different depending on whether or not the joined portion 4aa of the cover 4 and the upper corner portion 14ab of the yoke 14 are joined. There is no place.

  As described above, in the first embodiment of the present invention, the joint 4aa of the cover 4 and the upper corner 14ab of the yoke 14 are joined to emit light from the objective lens 12 out of the movement of the objective lens driving device 2. The movement of the light beam in the direction orthogonal to the optical axis is partly restricted. Thereby, the vibration of the objective lens driving device 2 is transmitted to the cover 4 and the housing 3, the resonance of the entire optical head 1 at about 6 kHz in the tracking direction is suppressed, and the tracking servo is stabilized.

  Further, in the first embodiment of the present invention, the joint 4aa of the cover 4 and the upper corner 14ab of the yoke 14 are joined by the adhesive 5 and are formed in the horn holes as in the first conventional example described above. The method of press-fitting hozo is not adopted. Therefore, even when the optical head is downsized, efficient mass productivity is not hindered.

Embodiment 2. FIG.
FIG. 7 is a schematic diagram showing a configuration of an optical recording / reproducing apparatus according to Embodiment 2 of the present invention. This optical recording / reproducing apparatus is roughly composed of the optical head 1 according to Embodiment 1 described above, a spindle motor 31, a controller 32, a laser drive circuit 33, and a lens drive circuit.

  The spindle motor 31 rotates the optical disc 35 under the control of the controller 32. The controller 32 controls the spindle motor 31, the laser drive circuit 33, and the lens drive circuit 34 based on the photodetector detection signal supplied from the optical head 1. The laser drive circuit 33 generates a laser drive signal for driving a laser diode that is a light source (not shown) constituting the optical head 1 under the control of the controller 32, and supplies the laser drive signal to the optical head 1. The lens driving circuit 34 generates a lens driving signal for controlling the focusing and tracking of the objective lens 12 (for example, see FIG. 1) constituting the optical head 1 under the control of the controller 32 and supplies the lens driving signal to the optical head 1. To do.

  The controller 32 includes a focus servo tracking circuit 36, a tracking servo tracking circuit 37, and a laser control circuit 38. The focus servo follow-up circuit 36 is a focus servo signal for focusing the light beam emitted from the optical head 1 on the information recording surface of the rotating optical disc 35 based on the photodetector detection signal supplied from the optical head 1. Is supplied to the lens driving circuit 34.

  The tracking servo tracking circuit 37 tracks the beam spot of the light beam emitted from the optical head 1 with respect to the eccentric signal track of the optical disk 35 based on the photodetector detection signal supplied from the optical head 1. Tracking servo signals are generated and supplied to the lens driving circuit 34. The laser control circuit 38 generates an appropriate laser drive signal based on the recording condition setting information recorded on the optical disc 35 extracted from the photodetector detection signal supplied from the optical head 1.

  Thus, according to Embodiment 2 of the present invention, an optical recording / reproducing apparatus is configured using the optical head 1 according to Embodiment 1 described above. Therefore, the optical recording / reproducing apparatus can be configured at low cost.

Embodiment 3 FIG.
In the first and second embodiments described above, an example of an optical head provided with only one light source or an optical recording / reproducing apparatus provided with only one optical head has been described. However, the present invention is not limited to this. The present invention can also be applied to an optical head provided with a plurality of light sources and an optical recording / reproducing apparatus provided with a plurality of optical heads. Such an optical head and an optical recording / reproducing apparatus are disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-295982.

As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the design can be changed without departing from the scope of the present invention. Is included in the present invention.
For example, in each of the above-described embodiments, an example in which the optical recording medium is a disk-shaped optical disk has been described. However, the present invention is not limited to this, and the optical recording medium may be rectangular.
Moreover, in each embodiment mentioned above, although the example which joins the junction part 4aa of the cover 4 and the upper corner | angular part 14ab of the yoke 14 with the adhesive agent 5 was shown, it is not limited to this, An adhesive tape and other joining members May be used.

1 is a partially enlarged perspective view showing an external configuration of an optical head according to Embodiment 1 of the present invention. It is a perspective view which shows the external appearance structure of the optical head shown in FIG. It is the perspective view which looked at the external appearance structure of the optical head shown in FIG. 1 from the back side. It is a disassembled perspective view which shows the external appearance structure of the optical head shown in FIG. FIG. 5 is a perspective view showing a state where the optical head shown in FIG. 4 is attached to the housing shown in FIG. 4. FIG. 3 is a diagram illustrating an example of phase characteristics in an open loop in a tracking direction when the joining portion 4aa of the cover 4 and the upper corner portion 14ab of the yoke 14 are joined or not in the optical head shown in FIG. It is the schematic which shows the structure of the optical recording / reproducing apparatus which concerns on Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical head 2 Objective lens drive device 3 Housing 3a, 11a Penetrating part 3aa Upper peripheral part 3ab Lower peripheral part 4 Cover 4a Opening part 4aa Joining part 4b Flat part 4c Hanging part 5 Adhesive (joining member)
DESCRIPTION OF SYMBOLS 11 Lens holder 12 Objective lens 13 Permanent magnet 14 Yoke 14a Upper part 15 Coil for focusing 16 Coil for tracking 31 Spindle motor 32 Controller 33 Laser drive circuit 34 Lens drive circuit 35 Optical disk 36 Focus servo follow-up circuit 37 Tracking servo follow-up circuit 38 Laser Control circuit

Claims (3)

An objective lens driving device for driving the objective lens;
A housing for supporting the objective lens driving device;
A cover having an opening for exposing the objective lens and components of the objective lens driving device located in the vicinity of the objective lens in a state where the objective lens driving device is supported by the housing. ,
The optical head is characterized in that the cover is bonded to the housing and is bonded to the component of the objective lens driving device.   In the cover, a joint is integrally formed adjacent to the component of the objective lens driving device at a position facing the component of the objective lens driving device in the opening. The optical head according to claim 1, wherein the end portion is processed to increase the strength of adhesion with the component of the objective lens driving device by an adhesive.   An optical recording / reproducing apparatus comprising the optical head according to claim 1.

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