JP4451755B2 - Optical pickup - Google Patents

Description

  The present invention relates to an optical pickup for reading information recorded on a recording surface of an optical disc or recording information, and an optical disc apparatus including the same.

  An optical pickup mounted on an optical disc apparatus includes a light emitting element that generates heat during recording and reproduction operations, a drive circuit board for controlling the light emission state from the light emitting element, a high-frequency module, and a lens driving device having a driving coil. ing. These are heat-generating components, and the amount of heat generated is greatly increased particularly during high-speed recording. As a result, thermal deformation due to local temperature distribution occurs in the optical pickup.

  An example of an optical pickup used in a conventional optical disc apparatus is described in Patent Document 1. In the optical pickup described in this publication, the heat generating component has a heat radiating member, and the heat radiating member is connected by a heat conductive sheet to increase the heat radiating efficiency.

JP-A-10-283650 (page 2-9, FIG. 1)

  In a recording / reproducing apparatus that realizes both recording and reproduction as compared with a reproduction-only apparatus that reproduces information on a disc, the output of light emitted from a light emitting element (laser light) of the optical pickup is large, and the optical pickup unit The influence of heat generation in can not be ignored. As described above, the optical pickup includes a heat generating component, and the heat generating component is thermally deformed due to local temperature distribution. When a local temperature distribution occurs in the optical component, for example, the curvature of the spherical surface of the lens changes, the focal length and the focal position change, and the optical axis shifts. As a result, the signal of the disk drive device deteriorates, causing malfunction.

  In order to eliminate the problem caused by having the heat generating component, the optical pickup described in Patent Document 1 promotes heat dissipation from the optical component. However, in the optical pickup described in this publication, since it is insufficient to make the temperature distribution uniform, there is still a risk of thermal deformation, signal deterioration, and malfunction.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to realize a highly reliable optical pickup in an optical disc apparatus capable of recording and reproduction. Another object of the present invention is to prevent signal degradation and malfunction of the optical disk apparatus.

The purpose of the present invention is to provide a light emitting element that emits light, a drive circuit board that controls the emission state of the light from the light emitting element, and guide the emitted light to a predetermined position of the disk via an optical component and reflect it from the disk. A lens driving device for guiding light to a detector; and a pickup housing on which the light emitting element is mounted. A holder having higher thermal conductivity than the optical component is provided around the optical component, and the holder has a flange portion. In the optical pickup having the flange portion provided on a surface different from the positioning surface of the optical component, a plurality of protrusions are provided on the pickup housing, and the protrusion and the optical component are positioned in point contact with each other. Is achieved.

Moreover, the said objective is achieved by forming the said protrusion in the position which does not contact the said holder .

The above object is achieved by integrating the holder with a yoke of a magnetic circuit .

  According to the present invention, since the connection between the lens holder and the pickup housing is a point connection, the lens holder is a good heat conductor, and the temperature distribution of the optical component such as the lens is made uniform. Thermal deformation due to distribution can be prevented. Therefore, relative positional deviation and optical axis deviation between optical components can be prevented, and the reliability of the optical pickup device is improved. In addition, malfunction of the circuit and signal deterioration due to heat generation can be prevented.

  Hereinafter, an embodiment of an optical disk apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an optical pickup used in an optical disc apparatus. In FIG. 1, the x-axis direction is a tangential direction of an optical disk (not shown), the y-axis direction is a tracking direction that is the radial direction of the optical disk, and the z-axis direction is a focusing direction that is the optical axis direction of the objective lens 1.

  In the optical pickup 1, the light emitted from the light emitting element 2 is condensed on the optical disk by the objective lens 4 a of the lens driving device 4 through the optical component 5 such as a mirror or a lens. The objective lens 4a is driven by an actuator in a focus direction perpendicular to the optical disc and a track direction that is a radial direction of the optical disc. Then, the focal point of the objective lens 4a is positioned on the target track of the optical disc. The reflected light from the optical disc enters the light receiving element through the objective lens 4a and the optical component 5. The optical component 5 and the lens driving device are supported by a bearing 8 so as to be able to move roughly in the track direction. The bearing 8 is held by the pickup housing 6.

  In the optical pickup 1, a drive circuit board (IC) 3 that controls the light emitting element 2 and the light emission state from the light emitting element 2, a high frequency module, a driving coil included in the lens driving device 4, and the like during actual recording and reproduction operations Generates heat. When these components generate heat, an uneven temperature distribution occurs in the optical pickup 1. Among these, the optical component 5 is made of glass or resin and has low thermal conductivity. As a result, a temperature difference tends to occur inside the optical component 5 from the joint portion supporting the optical component toward the portion excluding the joint portion.

  When a large temperature difference occurs locally in the optical component 5, for example, when the curvature of the spherical surface of the lens changes, the focal length and focal position of the lens change. Within the component, the expansion varies depending on each part, the support position of the optical component 5 changes, and the optical axis shift occurs due to the tilting of the optical component. In addition, when a temperature difference occurs in each part of the optical component, the refractive index inside the optical component becomes non-uniform, which causes aberrations and deteriorates optical characteristics.

  FIG. 2 shows an example of the temperature distribution of the optical pickup 1. In the vicinity of the light emitting element 2 and the drive circuit board 3 as the heat generating part H1, which is a result obtained by calculating the temperature of each part of the optical pickup used in the past, the vicinity of the light emitting element 2 and the drive circuit board 3 becomes the high temperature part H2, and a temperature gradient is generated in the direction away therefrom. The bearing portion 8 is a low temperature portion H3. In FIG. 2, it can be confirmed that a temperature gradient is also generated at the location 9 where the optical component 5 is mainly disposed. Such a non-uniform distribution of temperature causes an optical axis shift, which causes signal deterioration and malfunction of the optical disk device 112. In particular, in the optical pickup 1 capable of recording information on the disk 113, since the output of the light emitting element 2 necessary for the recording operation is increased, the calorific values of both the light emitting element 2 and the drive circuit board 3 are increased by the supplied power. It has increased.

  Therefore, in the present invention, in order to solve the uneven temperature of each part of the optical component 5, a heat transfer path described in detail below is secured. In other words, the optical component holder 7 having high thermal conductivity was disposed around the optical component 5. Thereby, the amount of heat entering the optical component 5 is transmitted to the holder 7 having high thermal conductivity disposed around the optical component 5, and heat is transmitted to the entire optical component 5 to reduce the temperature difference inside the optical component 5. it can. Moreover, since the holder 7 diffuses heat, heat dissipation is also improved.

  Details of the pickup housing 6 using the holder 7 are shown in a perspective view in FIG. In order to position the optical component 5, a plurality of protrusions 9 a to 9 e are formed on the pickup housing 6. Specifically, a frame-like support member 6 a lacking the upper side is provided upright on a flat pickup housing 6. The support member 6a includes upright portions 6c and 6d and a support portion 6b formed by being bent at one end of the support member 6a.

  A protrusion 9a is formed on the height direction intermediate portion of one surface of the upright portion 6c of the support member 6a, and two protrusions are formed on one surface of the upright portion 6d at positions separated in the height direction. 9b and 9c are formed. Further, a projection 9e is formed on the surface of the support portion 6b in the height direction and facing the projections 9a to 9c. Further, a projection 9d is also formed on the upper surface of the pickup housing 6 and in the vicinity of the support member 6a. Therefore, among these projections 9a to 9e, the projections 9a to 9c are positioned for the plane whose normal is the optical axis, the projection 9d is positioned for the vertical direction (z direction), and the projection 9e is the horizontal direction ( Used for positioning in the y direction).

  Here, the protrusions 9a to 9c used for positioning of the surface having the optical axis as a normal line are provided at one place on the side close to the heat generating component such as the drive circuit board 3 and two on the side away from the heat generating component. The left-right (y-direction) protrusion 9e is provided on the side away from the heat generating component such as the drive circuit board 3. Since these protrusions 9a to 9e are formed, the area where the optical component 5 comes into contact with the pickup housing 6 is large, and as a result, the heat conduction area from the pickup housing 6 to the optical component increases, and the temperature of the optical component 5 increases. The conventional problem of rising can be solved.

  In this embodiment, since the optical component 5 is positioned using the protrusions 9a to 9d, the heat conduction area between the pickup housing 6 and the optical component 5 is reduced, and the amount of heat input to the optical component 5 is reduced. Thereby, the temperature rise of the optical component 5 falls. Further, since the protrusions 9a to 9e are arranged so that the amount of heat flowing into the optical component 5 is equalized vertically and horizontally, the temperature difference in the optical component 5 can be reduced together with the effect of equalization by the holder 7. Further, since the projections 9a to 9e are provided, the positioning of the optical component 5 is facilitated and the assemblability of the optical pickup 1 is improved. In this embodiment, the holder 7 is brought into contact with the projections 9d and 9e in order to further suppress the temperature rise of the optical component 5 such as a lens. Further, the flange 7b of the holder 7 is provided on the surface opposite to the surface where the optical component 5 faces the protrusions 9a to 9c. Thereby, the temperature of the optical component 5 on the side far from the heat generating member can be made uniform. That is, a certain amount of heat is transferred from the pickup housing 6 to the optical component 5 through the protrusions 9d and 9e. Since the amount of heat transfer is determined by the number of protrusions and the contact area of the protrusions, the protrusions can be prevented from contacting the holder 10 as necessary.

  An example of this is shown in FIG. The holder 7 used in the above embodiment has a ring-shaped circumferentially uniform shape, but the holder 10 used in this modification is a portion that contacts the protrusions 9d and 9e provided on the pickup housing 6 and the support member 6a. Was made into the shape of notches 11a and 11b. Accordingly, heat transfer from the pickup housing 6 is hindered by the protrusions 9a to 9e, and the inflow of heat into the optical component 5 made of a material having low thermal conductivity such as glass or resin is suppressed. Moreover, the amount of heat that has flowed into the optical component 5 is made uniform by the holder 10 and propagates throughout the optical component 5. Therefore, the temperature rise of the optical component 5 is reduced, and the temperature difference of each part of the optical component 5 is reduced. The shape of the protrusions 9a to 9e is preferably a spherical surface or a part of a cylinder. In addition, it is desirable that the contact area between the pickup housing 6 and the optical component 5 can be made as small as possible.

  FIG. 5 is a longitudinal sectional view showing another modification of the lens holder. When the optical component 5 is attached to the support member 6a of the pickup housing 6, the recesses 12a to 12c are formed in portions where the optical component 5 contacts the protrusions 9a to 9c. The protrusions 9a to 9c are applied to the recesses 12a to 12c, and the vertical direction and the horizontal direction are positioned. In this case, the protrusions 9d and 9e are unnecessary. According to this modification, the contact area between the support member 6a of the pickup housing and the optical component 5 is reduced, and the temperature rise of the optical component 5 is suppressed.

  In the present modification, the recesses 12a to 12c are hemispherical, but a ring-shaped groove connecting the recesses 12a to 12c may be used so that the circumferential position of the optical component 5 can be adjusted. In the case of the optical component 5 in which aberration is generated due to variations in molding, there are some components that can reduce aberration by adjusting the circumferential position of the optical component 5. It is preferable to make it.

  In this modification, the protrusions 9a to 9e are provided on the support member 6a of the pickup housing 6, but the protrusions 9a to 9e may be provided on the optical component 5 side. When the protrusions 9a to 9e are provided on the optical component 5 side, the mold for molding the pickup housing 6 is simplified, and the cost can be reduced. In the above-described embodiments and modifications, the protrusions 9a to 9e are positioned in order to improve the assemblability. Sometimes fixed in the air. Even in this case, the adhesive material is formed in the same manner as the protrusions 9a to 9e to limit the bonding points. As a result, similarly to the protrusions 9a to 9e, the inflow of heat from the pickup housing 6 to the optical component 5 can be reduced.

  FIG. 6 is a perspective view showing still another modified example of the holder. This is an example in which the optical pickup 1 has a shape in which a part of the optical component 5 is removed in order to reduce the size and thickness. The optical component 5 is a lens, and the upper part (z direction) 13 of the lens 5 is cut away (FIG. (A)) and the upper and lower parts 14a and 14b of the lens 5 are both cut away (figure (b)). )) This is the case. As the lens 5 is cut out, the upper part 15 of the holder 17 (FIG. 1A) and the upper and lower parts 16a and 16b of the holder 18 (FIG. 1B) are also cut out.

  The holders 17 and 18 are both cut out at the upper part or the upper and lower parts, but the flanges 17a and 18a of the holders 17 and 18 are provided with flanges 17a and 18a so that heat is transmitted to the entire circumference of the holders 17 and 18. The portions 17b, 18b, and 18c that are always continuous in the circumferential direction are formed. Further, the sizes of the flange portions 17 a and 18 a of the holders 17 and 18 are set to inner diameters that do not block the light beam incident on the lens 5. As a result, the optical pickup 1 can be made thinner.

  FIG. 7 is a longitudinal sectional view showing another embodiment of the holder. This embodiment differs from the embodiment shown in FIG. 3 in that the lens holder 23 has a double structure. The lens holder 21 is further attached to the outside of the lens holder 22 located on the inner side that is the lens 5 side. And the flange parts 21a and 22a of each lens holder 21 and 22 are arrange | positioned at the processus | protrusion 9a-9c side formed in the supporting member 6a. That is, the protrusions 9 a to 9 c are in direct contact with the flange portion 21 a of the outer lens holder 21. The outer lens holder 21 is a member 21 having a low thermal conductivity, such as a resin, and the inner lens holder 22 is a member 22 having a high thermal conductivity, such as a metal such as aluminum.

  According to the present embodiment, since the thermal conductivity of the lens holder 21 is low, the amount of heat transferred from the protrusions 9a to 9e to the lens holder 21 can be reduced. On the other hand, the amount of heat transmitted to the lens holder 22 is quickly and substantially uniformly transmitted to each part of the lens 5, so that the temperature rise of the lens 5 is reduced and the temperature distribution is also made uniform.

  FIG. 8 is a perspective view showing an embodiment of the lens driving device according to the present invention. The lens driving device 31 has a main lens 5c and a sub lens 5b, and the lens holding member 38 holds the main lens 5c. The left and right side portions 38a and 38b of the holding member 38 hold guide shafts 36a and 36b for enabling the main lens 5c to move along the optical axis. The guide shafts 36a and 36b are attached to the yoke 32 having a magnetic circuit formed by a magnet and a coil for driving the main lens 5c in the optical axis direction via attachment portions 37a and 37b. The yoke 32 is formed in a box shape with an open top.

  The sub lens 5b is disposed in front of the main lens 5c and spaced from the main lens 5c. The sub lens 5b is held by a holder 33 which is integrated with the yoke 32 and formed in an inverted Ω shape in order to reduce the number of parts. The leg part 34 above the holder 33 forms a cover attachment part (not shown) of the optical pickup.

  According to the present embodiment, since the holder 33 is integrated with the yoke 32, the surface area of the holder 33 is increased and the heat dissipation is improved. Since the heat dissipation of the holder 33 is improved, the temperature rise of the lens 5b is suppressed. Since the leg portion 34 of the holder 33 is thermally connected to the cover of the optical pickup, heat is transferred from the leg portion 34 to the cover, and heat dissipation is promoted. In addition, it is desirable to form the protrusions 9a to 9e shown in the embodiment shown in FIG. 1 on the holder 33 so as to reduce the inflow of heat into the lens 5b. This protrusion may be directed to the outer peripheral side of the lens or may be directed to the axial direction. In the lens driving device 31 of this embodiment, since the yoke 32 and the holder 33 are integrated, it becomes a holding means for holding the plurality of optical components 5 with a minimum necessary structure. Therefore, deformation due to heat between the mounted optical components can be suppressed.

  One embodiment of the optical disk device 112 on which the optical pickup 1 shown in the above embodiments and modifications is mounted will be described with reference to FIG. FIG. 9 is a block diagram of the optical disc device 112. The optical disk device 112 includes an optical pickup 1 that reads and writes information from and to the optical disk 113. The optical disk 113 is rotationally driven by a spindle motor 114. A feed control circuit 117 controls a feed mechanism that moves the optical pickup 1 in the radial direction of the optical disk 113. The feed control circuit 117 is connected to the controller 115. A disk rotation control circuit 116 that controls the rotation of the spindle motor 114 is also connected to the controller 115.

  Various signals 118 detected by the optical pickup 1 are sent to a servo signal detection circuit 119 and a reproduction signal detection circuit 120. The servo signal detection circuit 119 generates a focus error signal and a track error signal. A command from the controller 115 and a signal from the actuator drive circuit 121 control the position of the objective lens 4. The reproduction signal detection circuit 120 reproduces information recorded on the optical disc 113. Since the optical pickup 1 described in the above embodiments and modifications is mounted on the optical disk device 112, data can be recorded and reproduced at high speed.

In each of the above embodiments and modifications, the material of the holder 7 is a metal material such as copper, aluminum, or zinc, or a resin with improved thermal conductivity. In the embodiment shown in FIG. 1, the shape of the optical component 5 is a lens shape. In this case, the holder 7 is provided in a ring shape around the optical component 5. When the optical component 5 is not a lens, the holder 7 may have a shape other than the ring shape. In the case of a plate-like optical component 5 such as a mirror, a belt-like holder 7 is preferably used around the optical axis. In the above-described embodiments and modifications, the lens is described as an example of the optical component. However, the present invention can be similarly applied to a mirror, a beam splitter, and a prism other than the lens.

1 is a perspective view of an embodiment of an optical pickup according to the present invention. It is a figure explaining the temperature distribution of an optical pick-up. It is a disassembled perspective view of the holder part used for the optical pick-up shown in FIG. It is a perspective view of the holder used for the holder part shown in FIG. It is a longitudinal cross-sectional view of the other holder used for the holder part shown in FIG. It is a perspective view of the other holder used for the holder part shown in FIG. It is a longitudinal cross-sectional view of the other holder used for the holder part shown in FIG. It is a perspective view of the other holder used for the holder part shown in FIG. 1 is a block diagram of an embodiment of an optical disc apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical pick-up, 2 ... Light emitting element, 3 ... Drive circuit board, 4 ... Lens drive device, 5 ... Optical component, 6 ... Pickup housing, 7 ... Holder, 9a-9e ... Protrusion, 112 ... Optical disk apparatus, 113 ... optical disk.

Claims (3)

A light emitting element that emits light, a drive circuit board that controls the emission state of light from the light emitting element, and guides the emitted light to a predetermined position of the disk through optical components, and detects reflected light from the disk A lens driving device for guiding the light emitting element, and a pickup housing for mounting the light emitting element,
In an optical pickup in which a holder having a higher thermal conductivity than the optical component is provided around the optical component, the holder has a flange portion, and the flange portion is provided on a surface different from the positioning surface of the optical component.
An optical pickup comprising: a plurality of protrusions provided on the pickup housing; and positioning the protrusions and the optical component in point contact .   The optical pickup according to claim 1, wherein the protrusion is formed at a position not in contact with the holder.   2. The optical pickup according to claim 1, wherein the holder is integrated with a yoke of a magnetic circuit.

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