JP4848164B2 - Optical pickup - Google Patents

Description

  The present invention relates to an optical pickup.

In an optical disk device, an optical pickup that reads and records information from and on an optical disk becomes high temperature when the power consumption of a semiconductor laser or a laser driving integrated circuit is large.
When the temperature is high, the semiconductor laser deteriorates in terms of life and performance, and the laser-driven integrated circuit also deteriorates in performance in terms of electrical characteristics and life, so that the reliability of the optical pickup is significantly lowered.

  For this reason, in particular, semiconductor lasers and laser-driven integrated circuits have a structure that increases heat dissipation, and are designed so that their temperatures do not exceed the guaranteed temperature of the components.

In order to improve the heat dissipation of the optical pickup, it is preferable to increase the surface area and volume of the optical pickup, but this increases the size of the device, and it is necessary to avoid the increase in size in terms of customer requirements for the product. is there.
Since the optical pickup is movable and supported in the radial direction of the optical disc by only two axes so that the information from the inner circumference to the outer circumference of the optical disc can be accessed in the optical disc apparatus, the electrical signal and the portion in contact with this axis Other than the flexible wiring for exchanging data, the optical disk device is floating in the air.

  For this reason, in the conventional optical pickup, in order to improve the heat dissipation in the part floating in the air, a heat dissipation structure that directly uses the wind generated with the rotation of the optical disk has been adopted.

  Patent Document 1 describes a description of securing a heat radiation property by attaching a heat radiating plate extending to the vicinity of an objective lens along an optical disk surface to a semiconductor laser.

  Patent Document 2 describes a structure in which a laser-driven integrated circuit is disposed on the optical disc side with a gap from the pickup case, and a heat sink for cooling the laser-driven integrated circuit is disposed on the optical disc side.

Japanese Unexamined Patent Publication No. Hei 8-94965

Japanese Patent Laid-Open No. 2004-192751

  In recent years, optical disc apparatuses have been required to increase the speed of recording and reproducing information, and to improve the transfer speed of electrical and optical signals and the rotational speed of optical discs. As the rotational speed of the optical disk increases, the amount of heat generated by the spindle motor increases, and the temperature inside the optical disk apparatus, that is, around the optical pickup increases. As the temperature rises with the increase in the heat generated by the semiconductor laser and the laser-driven integrated circuit, the optical pickup is required to have improved heat dissipation to maintain reliability.

  In the prior art, for cooling using the flow associated with the rotation of the optical disk, a heat sink for cooling either the semiconductor laser or the laser-driven integrated circuit is attached to the optical disk facing surface of the pickup case. By providing a heat sink on the optical disk facing surface of the optical pickup, a strong wind from the rotation of the optical disk is directly applied to the heat sink. Therefore, effective cooling can be expected for a component to which this heat sink is attached. In the conventional optical pickup, the heat generation amount of the laser-driven integrated circuit is around 1 W, the heat generation amount of the semiconductor laser is less than 0.5 W, and the heat radiation of the semiconductor laser can be radiated by the pickup case having the conventional structure. For this reason, it has been optimal for the balance of the heat pickup structure of the optical pickup to radiate the heat from the laser-driven integrated circuit with a heat radiating plate installed on the optical disk facing surface and to apply the heat radiation capability of the pickup case to the semiconductor laser.

  However, in this structure, since the heat radiating plate blocks the upper surface of the pickup case, the cooling performance of the components attached to the pickup case cannot be improved. In the future, if the heat generation amount of the semiconductor laser is improved or a lens adjustment drive mechanism is mounted in the pickup, improvement of the heat dissipation capability of the pickup case is inevitable. In addition, since there is a possibility that the amount of heat generated also increases in the laser drive integrated circuit, it is necessary to actively dissipate heat as in the conventional structure. For this reason, a structure capable of cooling the upper surface of the pickup case is required while maintaining a structure having a heat sink on the optical disk facing surface of the conventional structure.

  An object of the present invention is to solve the above-mentioned problems, to improve the heat dissipation of the entire optical pickup without increasing the volume, and to provide a reliable optical pickup.

The object is to provide a semiconductor laser that emits a laser beam for recording and reproducing information on an optical disc, a pickup case that houses an optical component that guides the reflected light of the laser beam to a photodetector, and a recording surface of the optical disc for the laser beam. In an optical pickup comprising an objective lens for condensing light, an actuator for driving the objective lens, a laser drive integrated circuit for driving the semiconductor laser, and an electronic substrate on which the laser drive integrated circuit is mounted. And the laser-driven integrated circuit is arranged in parallel to the optical disc and in the vicinity of the optical disc, and forms a space between the electronic substrate and the pickup case with a spacer and a side wall that guides air flow, Both surfaces of the electronic substrate are air flowing radially from the center of the rotating optical disc to the outer periphery, and It is accomplished by being cooled by the air flowing through the from the outer periphery to the inner periphery space of the disk.

The object is achieved by forming the space by a plurality of spacers provided between the electronic substrate and the pickup .

  According to the present invention, it is possible to improve the heat dissipation of the entire optical pickup without increasing the volume of the optical pickup by flowing air between the electronic substrate and the pickup case, and to provide a highly reliable optical pickup.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of an optical pickup provided with this embodiment.
FIG. 2 is a perspective view of the optical pickup when the heat sink 3 shown in FIG. 1 is removed.
In FIG. 1, the semiconductor laser 1 is mounted in two places on the optical pickup. This is because a laser having a wavelength conforming to the CD and DVD standards is mounted, and there are cases where three semiconductor lasers including a semiconductor laser conforming to the optical disk standard using a blue laser are mounted in the future. Further, the semiconductor laser 1 shown here is an electronic component on which an element that oscillates a laser is mounted, and there is one in which two or more laser oscillation elements are mounted in one package.

  The heat radiating plate 3 is parallel to the optical disk (not shown) and is disposed in the vicinity of the optical disk, and has a high heat dissipation property because it can receive the wind directly from the rotation of the optical disk. The wind due to the rotation of the optical disk is stronger as it is closer to the optical disk. However, in consideration of vibration and deformation of the optical disk, it is necessary to avoid contact with the optical disk during recording and reproduction. Conventionally, the objective lens 8, the actuator case 9, the suspension holder 10, and the like are designed so as not to come into contact with the optical disk in the vicinity of the optical disk because the objective lens 8 needs to be driven in the vicinity of the optical disk. Therefore, it is desirable that the heat radiating plate 3 is also designed to have the same height as the optical disk facing surface of the actuator case 9 and the suspension holder 10 in order to obtain a cooling effect by the rotation of the optical disk.

  In FIG. 2, a laser drive integrated circuit 2 (described as an electronic component in the claims) is provided below the heat radiating plate 3, and the laser drive integrated circuit 2 is attached to an electronic substrate 11. The laser driving integrated circuit 2 and the heat radiating plate 3 are in contact with each other through a heat conducting member, and the heat of the laser driving integrated circuit 2 is radiated by the heat radiating plate 3. Since the electronic substrate 11 is an electronic component including copper wiring, depending on the wiring pattern, the electronic substrate 11 has an effect of diffusing and radiating heat, which is an effect of the heat radiating plate 3. Depending on the amount of heat generated by the laser-driven integrated circuit 2, even if the heat-dissipating plate 3 is not provided as shown in FIG. Can be secured.

  The electronic substrate 11 has a space above the pickup case 4 via the spacer 5. The pickup case 4 is provided with optical components arranged and attached so as to guide the laser emitted from the semiconductor laser 1 to the optical disk and guide the reflected light to the photodetector. Conventionally, this pickup case 4 may be made of a resin for an optical pickup with a small amount of heat generated by a semiconductor laser, but for an optical pickup with a large amount of heat generated, a die cast product such as a zinc alloy, an aluminum alloy, or a magnesium alloy. It is common to be made with.

  The spacer 5 may be made as a part of the pickup case 4 or may be a separate part. However, in order to secure a space between the electronic substrate 11 and the pickup case 4, the height of the spacer 5 is a length in a direction perpendicular to the optical disc, and when the spacer 5 is cut along a plane parallel to the optical disc. When comparing the diameters of circles with an area equal to the area, the spacer height must be larger than the diameter of this circle. Also, it is desirable that the number of spacers be as small as possible. In the pickup device of the present embodiment, there are three spacers 5 (only one is shown in FIGS. 1 and 2), and the three spacers. Is substituted by changing the shape of the pickup case 4.

  Thus, by reducing the cross-sectional area and the number, it is possible not only to ensure air circulation but also to suppress the heat of the laser-driven integrated circuit 2 from flowing through the electronic substrate 11 to the pickup case 4 due to heat conduction. It is possible to suppress the temperature rise of the heat generating component attached to the pickup case 4. In order to suppress heat conduction, the spacer 5 is preferably made of a resin having low heat conductivity. However, since the spacer 5 is attached to the electronic board by screwing, the effect that the electronic board can be used as an electrical GND while keeping the distance from the pickup case 4 by using the spacer 5 as a metal. There is also.

  Two types of flexible wirings 6 are attached to the electronic substrate 11 roughly. One is a flexible wiring connecting the optical pickup and the optical disk device. This is attached to the optical disc outer peripheral side of the optical pickup movable in the radial direction from the inner periphery to the outer periphery of the optical disc, and follows the optical pickup. Generally, the flexible wiring connecting the optical disk device and the optical pickup is arranged in a semicircular shape so as to wrap around the optical disk outer peripheral side of the optical pickup, so that the wind enters the optical disk outer peripheral side of the optical pickup inside. It has become difficult.

  Another flexible wiring connects the electronic substrate 11 and the components inside the optical pickup. An actuator device that drives the objective lens 8, a semiconductor laser 1, a photoelectric conversion integrated circuit 12 having a photoelectric conversion element that converts a light signal into an electric signal, and a component called a front monitor are connected to the electronic substrate 11 by this flexible wiring. linked.

FIG. 3 is a perspective view of the internal structure of the actuator device that drives the objective lens.
In FIG. 3, the objective lens 8 is attached to a lens holder 15, and the lens holder 15 is supported in the air by a suspension wire 17 attached to the suspension holder 10. Since the suspension wire 17 is a metal wire having a small diameter, the lens holder 15 can move within a certain range with a small force in a direction perpendicular to the optical disk, a radial direction of the optical disk, or the like. A coil 14 is attached to the lens holder 15, and a magnet 16 is attached to the actuator case 9. By passing an electric current through the suspension wire 17 described above, the lens holder 15 is driven by electromagnetic force.

  As described above, there is a clearance space for driving the lens holder 15 in the actuator device.

  The flow associated with the rotation of the optical disk is very strong in the vicinity of the optical disk, but the flow velocity around the optical pickup that is slightly apart, particularly around the pickup case 4 is very weak compared to the vicinity of the optical disk. In addition, the pressure is likely to drop in a portion where the distance is narrow, such as between the optical disk facing surface of the actuator device and the optical disk. Therefore, in the actuator device, a flow that rises from the pickup case 4 side to the objective lens 8 side that is the optical disk facing surface is generated.

  The air flow in the vicinity of the optical disc flows in the rotation direction of the optical disc and flows radially from the center of the optical disc to the outer periphery due to centrifugal force. For this reason, as with the centrifugal pump, the pressure on the outer periphery of the optical disk is high, the pressure is low at the center of the optical disk, and a flow toward the center of the optical disk is generated in the central part at a distance from the optical disk. This flow is particularly noticeable when the optical disk is rotating at high speed.

  In the present invention, a space is provided between the electronic substrate 11 and the pickup case 4 with the spacer 5 interposed. This space is not directly affected by the rotation of the optical disk because it passes through the electronic substrate 11, and therefore a flow having a component from the outer periphery of the optical disk to the inner periphery is likely to occur. Thereby, the surface at the side of the pickup case 4 of the electronic substrate 11 can be cooled.

  That is, the laser-driven integrated circuit 2 can radiate heat to the air around the optical pickup through two paths: the heat dissipation plate 3 and the electronic substrate 11. Further, the pickup case 4 can also use the surface on the optical disc side as a heat radiating surface, so that the heat radiating capability is improved. In order to easily obtain this effect, it is preferable that the upper surface of the pickup case 4 facing the space facing the electronic substrate 11 can dissipate heat directly from the surface of the pickup case 4 by preventing flexible wiring as much as possible.

  It is also considered effective to provide a fin-shaped heat dissipation member on the upper surface of the pickup. In order not to transfer the heat of the laser-driven integrated circuit 2 to the pickup case 4, the fin-shaped heat radiating member should not be in contact with the electronic substrate and should not impair heat dissipation by suppressing the flow. Don't be.

  In addition, the presence of the space has a heat separation effect that suppresses the heat of the electronic substrate, particularly the heat of the laser-driven integrated circuit 2, from being transmitted to the pickup case 4. Of the optical pickups, the laser drive integrated circuit 2 often generates the largest amount of heat. If this heat is transmitted to the pickup case 4, the temperature of the entire pickup case 4 is increased. However, according to this thermal separation structure, it is possible to suppress the temperature rise of the heat generating component attached to the pickup case 4.

  Although the objective lens 8 does not generate heat, the temperature rise is relatively large because there is a coil that generates heat nearby. In addition, when a single objective lens is used for optical discs of multiple standards, such as a standard using a blue laser, the lens becomes relatively large, and the amount of heat generated by the coil to drive this lens. Also grows. For this reason, it is thought that it is necessary in the future to examine the heat dissipation of the objective lens 8.

  In the preceding column, the pressure on the optical disk-facing surface of the actuator device is low, and there is an air flow from the pickup case 4 to the optical disk surface side inside the actuator device. However, according to the present invention, air flows to the pickup case 4 side of the actuator device. Therefore, cooling inside the actuator device is also promoted.

  In addition, the structure according to the present embodiment uses the conventional heat sink 3, electronic substrate 11, and pickup case 4, so the number of components does not increase, and thus the cost and volume increase (enlargement) do not result.

  With these effects, it is possible to improve the heat dissipation of the entire optical pickup without increasing the volume of the optical pickup, and to provide a highly reliable optical pickup.

FIG. 4 is a perspective view of an optical pickup provided with this embodiment.
FIG. 5 is a perspective view of the optical pickup provided with the present embodiment as viewed from the optical disk side.
6 is a cross-sectional view taken along line AA in FIG.
4 to 6, in the space between the electronic substrate 11 and the pickup case 4 in order to make it easier to generate an air flow from the outer periphery of the optical disk to the inner periphery, that is, in the direction of the arrow 18 in FIG. Further, while ensuring the flowability in the direction of the arrow 18, a member that inhibits the air permeability for suppressing disturbance is provided on the other surface. Conversely, for the flow in the direction of the arrow 18, it becomes a side wall that guides the flow, and can smoothly flow to the inner peripheral direction of the optical disc or to the actuator device.

  Specifically, as shown in FIG. 4, a heat sink bent portion 3 a is provided at the end of the heat sink 3 provided on the upper surface of the electronic substrate 11. The bent portion 3a can also play a role of pressing the flexible wiring 6 that connects the electronic substrate 11 and the electronic components inside the pickup, and at the same time, the pressed flexible wiring 6 serves as a flow guide plate. Moreover, since the surface area of the heat sink 3 is increased, the heat dissipation of the laser-driven integrated circuit 2 is improved. Further, the heat radiating plate 3 is prevented from contacting the pickup case 4 so that the heat of the laser drive integrated circuit 2 is not transmitted to the pickup case 4.

FIG. 7 is a perspective view of an optical pickup provided with another embodiment.
In FIG. 7, in the present embodiment, a second heat radiating plate 3 ′ is provided, and a guide wall 3′a is provided on the second heat radiating plate 3 ′. You may cut and cut and form a part of attached heat sink 3 '. In a place where the flexible wiring 6 is not required to be pressed, there is a means for extending the pickup case 4 to the optical disk side and providing a guide wall 3'a. Also in this case, it is desirable not to contact the pickup case 4 side so that the heat of the laser drive integrated circuit 2 is not transmitted. When a wall is provided from the pickup case 4 side, the heat dissipation of the pickup case 4 is improved due to the effect of increasing the surface area.

  In addition, by providing the actuator case opening 19 as shown in FIG. 7, the flow induced by the guide wall 3′a can be easily taken into the actuator device, and the heat dissipation of the objective lens 8 can be improved. .

  With these effects, it is possible to improve the heat dissipation of the entire optical pickup without increasing the volume of the optical pickup and to provide a reliable optical pickup.

As described above, the present invention
1. A semiconductor laser that emits a laser beam for recording / reproducing information on an optical disc, a pickup case containing an optical component that guides reflected light of the laser beam to a photodetector, and the laser beam is condensed on the recording surface of the optical disc In an optical pickup comprising an objective lens, an actuator for driving the objective lens, an electronic component for driving the semiconductor laser, and an electronic substrate on which the electronic component is mounted, the electronic substrate is arranged in parallel with the optical disk. In addition, a space in which wind flows is provided between the electronic substrate and the optical disc facing surface side of the pickup case.
2. The space is formed by a plurality of legs provided between the electronic substrate and the pickup.
3. Cooling air passes through both surfaces of the electronic substrate.
4). The air guide wall is provided on the side surface of the space so that the air in the radial direction from the optical disk penetrates the space formed by the electronic substrate and the pickup case.
5). A heat radiating plate that is thermally connected to the electronic components on the electronic board is provided, a bent portion is provided on the heat radiating plate, and the flexible wiring is positioned by the bent portion.

  Accordingly, the semiconductor laser and the pickup case on which the semiconductor laser is mounted, the laser drive integrated circuit for driving the semiconductor laser, and the electronic substrate on which the laser drive integrated circuit is mounted, and reading and recording information on the rotating optical disk In addition to cooling the laser-driven integrated circuit and the electronic substrate from both sides, the pickup case is cooled, and the temperature of the laser-driven integrated circuit and the semiconductor laser is lowered.

It is a perspective view of the optical pick-up provided with one Example of this invention. It is a perspective view of an optical pick up at the time of removing heat sink 3 shown in FIG. It is a perspective view of the internal structure of the actuator apparatus which drives an objective lens. It is a perspective view of the optical pick-up provided with the present Example. It is the perspective view which looked at the optical pick-up provided with the present Example from the optical disk side. It is the sectional view on the AA line of FIG. It is a perspective view of the optical pick-up provided with the other Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser, 2 ... Laser drive integrated circuit, 3 ... Heat sink, 3a ... Heat sink bending part, 4 ... Pickup case, 5 ... Spacer, 6 ... Flexible wiring, 8 ... Objective lens, 9 ... Actuator case, 10 ... Suspension holder, 11 ... Electronic substrate, 12 ... Photoelectric conversion integrated circuit, 13 ... Optical disk, 14 ... Coil, 15 ... Lens holder, 16 ... Magnet, 17 ... Suspension wire, 18 ... Arrow (direction of flow), 19 ... Actuator case Aperture.

Claims (2)

A semiconductor laser that emits a laser beam for recording / reproducing information on an optical disc, a pickup case containing an optical component that guides reflected light of the laser beam to a photodetector, and the laser beam is condensed on the recording surface of the optical disc In an optical pickup comprising an objective lens, an actuator that drives the objective lens, a laser drive integrated circuit that drives the semiconductor laser, and an electronic substrate on which the laser drive integrated circuit is mounted,
The electronic substrate and the laser drive integrated circuit are arranged in parallel to the optical disc and in the vicinity of the optical disc, and a space is formed between the electronic substrate and the pickup case by a spacer and a side wall for guiding the air flow. And
The both sides of the electronic substrate are cooled by air flowing radially from the center of the rotating optical disk to the outer periphery and by air flowing through the space from the outer periphery to the inner periphery of the optical disk . The optical pickup according to claim 1,
The optical pickup is characterized in that the space is formed by a plurality of spacers provided between the electronic substrate and the pickup.

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