JP2009110585A - Optical pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup which can improve a cooling effect of an objective lens with an inexpensive and simple configuration. <P>SOLUTION: The optical pickup includes an objective lens 1 and a support member 3 which supports the objective lens 1 and controls a relative position of the objective lens 1 and an information recording medium 7. The support member 3 forms a plurality of projection parts 6 projecting so as to keep away from an optical axis 1a of the objective lens 1. When the support member 3 is viewed from an objective lens 1 side, at least one of the plurality of projection parts 6 has a portion extended out from other projection parts 6 on the side of information recording medium 7. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical pickup used in an optical recording / reproducing apparatus.

  Conventionally, the relative position between the objective lens and the optical disk is controlled by an electromagnetic actuator composed of a coil and a magnet in order to read information recorded on the optical disk recording medium such as a CD or DVD, or to record on the optical disk recording medium. An optical pickup is generally used.

  The optical pickup includes an objective lens made of plastic and a lens holder that holds the objective lens. This lens holder is provided with a focus coil for driving the objective lens in the focus direction and a tracking coil for driving in the tracking direction. Such an optical pickup is configured to be cantilevered by, for example, four wires.

  In recent years, optical pickups have been increasingly miniaturized and integrated, and an objective lens is disposed in the vicinity of a focus coil and a tracking that are heat sources. Further, the recording / reproducing speed has been increased, and the drive current supplied to the focus coil and tracking coil tends to increase.

  The lens holder is heated by the heat generated from these coils, and the temperature of the objective lens rises. In this case, the objective lens has a temperature distribution in which the side closer to these coils is higher than the far side. As a result, the objective lens made of a plastic having a high coefficient of thermal expansion has a problem that its thickness easily changes, causes axial asymmetric thermal deformation, and increases coma, spherical aberration, and astigmatism. .

As an optical pickup for solving the above problems, there is one proposed in Patent Document 1. In this optical pickup, a plastic lens having a high thermal conductivity such as a beryllium steel alloy formed in an annular shape having a constant thickness so as to be in contact with the lower side of the plastic lens is disposed. This is to reduce the temperature gradient and various aberrations caused by this.
Japanese Patent Laid-Open No. 11-176209

  However, in the configuration of the optical pickup proposed in Patent Document 1, the weight of the lens holder on which the objective lens and the coil that are the movable part of the optical pickup actuator are mounted is increased by the annular member. In this case, there has been a problem that the drive current increases in order to gain thrust for the increase in weight, and as a result, the amount of heat generated by the coil increases. In addition, the cost increases due to the addition of the annular member, and the assembly time of the optical pickup also increases.

  An object of the present invention is to solve the conventional problems as described above, and to provide an optical pickup capable of enhancing the cooling effect of an objective lens with an inexpensive and simple configuration.

  In order to achieve the above object, an optical pickup according to the present invention includes an objective lens and a support member that supports the objective lens, and controls the relative position between the objective lens and an information recording medium. The support member forms a plurality of protrusions that protrude away from the optical axis of the objective lens, and when the support member is viewed from the objective lens side, at least one of the plurality of protrusions is In addition, there is a portion extending from the other protruding portion on the information recording medium side.

  According to the present invention, the cooling effect of the objective lens can be enhanced with an inexpensive and simple configuration.

  According to the optical pickup of the present invention, air that is convected by the rotation of the information recording medium can easily hit the protrusion, and the cooling effect of the objective lens can be enhanced. This effect can be realized by setting the shape of each protrusion, and the effect can be obtained with an inexpensive and simple configuration.

  In the optical pickup according to the aspect of the invention, it is preferable that the plurality of protruding portions have the extended portions except for the protruding portion closest to the information recording medium. According to this configuration, air that is convected by the rotation of the information recording medium can easily hit all the protrusions, which is advantageous for the cooling effect of the objective lens.

  Further, the support member is provided with a magnetic field generating means for driving the support member, and the magnetic field generating means is opposed to an end portion of the protruding portion in a direction orthogonal to the protruding direction of the protruding portion. It is preferable that they are arranged as described above. According to this configuration, the amount of air hitting the magnetic field generating means is increased, and the cooling effect of the magnetic field generating means can be enhanced.

  Further, it is preferable that at least one of the plurality of projecting portions has a groove formed on the information recording medium side. According to this configuration, the contact area between the protrusion and air is increased, and the cooling effect of the objective lens by the protrusion can be further enhanced.

  Further, the support member is provided with a magnetic field generating means for driving the support member, and the magnetic field generating means is opposed to an end portion of the protruding portion in a direction orthogonal to the protruding direction of the protruding portion. It is preferable that at least one of the plurality of projecting portions has a groove on the side of the information recording medium, the tip of which reaches the end portion. According to this configuration, air flows so as to reach the magnetic field generating means along the groove, so that the cooling effect of the magnetic field generating means can also be enhanced.

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

(Embodiment 1)
FIG. 1 is a plan view of an optical pickup 10 according to Embodiment 1 of the present invention. The optical pickup 10 shown in the figure includes an objective lens 1, and the objective lens 1 is supported by a lens holder 3 that is a support member. The lens holder 3 holds a coil substrate 2a and a coil substrate 2b which are magnetic field generating means. The objective lens 1 can be formed of a plastic such as PMMA, and the lens holder 3 can be injection molded of a liquid crystal polymer resin or the like.

  The coil substrates 2 a and 2 b are for driving the lens holder 3. By driving the lens holder 3, the objective lens 1 supported by the lens holder 3 is also driven, and the relative position between the objective lens 1 and a disk as an information recording medium can be controlled. The coil substrates 2a and 2b are formed by integrally laminating a coil wiring pattern for driving the objective lens 1 integrated with the lens holder 3 in the focusing and tracking directions on a printed wiring board.

  Reference numerals 4a and 4b denote magnets of a driving magnetic circuit. Reference numerals 5a, 5b, 5c and 5d are suspension wires for elastically supporting the lens holder 3. The lens holder 3 is cantilevered by the four spun wires 5a-5d.

  In order to drive the objective lens 1, it is necessary to supply current to the coil substrates 2a and 2b. In this case, when the current flows, the coils of the coil substrates 2a and 2b generate heat. This heat is transferred to the objective lens 1 and the temperature of the objective lens 1 rises. In order to suppress this temperature rise, the lens holder 3 is provided with a protrusion 6. The protrusion 6 will be specifically described with reference to FIGS.

  FIG. 2 is a perspective view of the lens holder 3. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2 and also shows a positional relationship with the disk 7 rotated by the spindle motor 8. As shown in FIGS. 2 and 3, the protruding portion 6 protrudes away from the optical axis 1 a of the objective lens 1.

  In FIG. 3, the distance between the optical axis 1 a of the objective lens 1 and the tip of the protruding portion 6 is a protruding distance d. As shown in FIG. 3, the protrusion distance d of each protrusion 6 increases as the distance from the disk 7 increases. That is, when the lens holder 3 is viewed from the objective lens 1 side, each protrusion 6 has a portion extending from the other protrusion 6 on the disk 7 side except for the protrusion 6 closest to the disk 7.

  Here, due to the rotation of the disk 7, air convection occurs around the disk 7. Due to this convection, an air flow is generated that moves away from the disk 7 toward the outer peripheral side of the disk 7 as indicated by an arrow 9 in FIG.

  In FIG. 3, if the protrusion distances d of the respective protrusions 6 are equal, the air flowing as shown by the arrow 9 in FIG. 3 hits the protrusion 6 closest to the disk 7. It becomes difficult to hit the protrusions 6 other than the above, and the cooling effect is insufficient.

  According to the configuration of the protrusions 6 shown in FIGS. 2 and 3, each protrusion 6 hits the air flow as shown by the arrow 9 in FIG. 3. Thereby, the cooling effect of the lens holder 3 can be enhanced.

  Furthermore, by changing the setting of the protrusion distance d of each protrusion 6, the cooling effect by each protrusion 6 also changes. Due to this change in cooling effect, the temperature distribution of the objective lens 1 mounted on the lens holder 3 also changes. Therefore, the temperature distribution of the objective lens 1 may be reduced by setting the protrusion distance d of each protrusion 6.

  In addition, as shown in FIG. 1C, the coil substrates 2a and 2b provided on the lens holder 3 are disposed so as to face the end portion of the protruding portion 6 in the direction orthogonal to the protruding direction of the protruding portion 6. ing. According to this structure, the air which hits the protrusion part 6 also produces the flow of the air which reaches the coil board | substrates 2a and 2b along the protrusion part 6. FIG. Thereby, the cooling effect of the coil substrates 2a and 2b, which are heat sources, can be enhanced.

  From the viewpoint of enhancing the cooling effect, a configuration in which the protruding distance d of each protruding portion 6 increases as the distance from the disk 7 increases as in the examples of FIGS. On the other hand, when trying to reduce the temperature distribution of the objective lens 1 while enhancing the cooling effect, the configuration shown in FIGS. Therefore, when the lens holder 3 is viewed from the objective lens 1 side, a configuration in which at least one of the projecting portions 6 is a projecting portion with a portion extending from the other projecting portion 7 on the disk 7 side is also conceivable.

  Moreover, although the protrusion part 6 demonstrated by the example of rectangular shape, various shapes of the protrusion part 6 are considered, for example, the shape whose front-end | tip is a curved surface is also considered. Even if it is such a shape, what is necessary is just to form each protrusion part so that there may be an extension part.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS. Since the second embodiment has the same configuration as that of the first embodiment except for the configuration of the protruding portion 6, a duplicate description is omitted. FIG. 4 is a perspective view of the lens holder 3 according to the second embodiment. FIG. 5 is a cross-sectional view taken along line BB in FIG.

  The lens holder 3 shown in FIG. 4 is different from the lens holder 3 shown in FIG. 2 in that a groove 11 is provided in the protruding portion 6. Providing the groove 11 in the protruding portion 6 increases the contact area with the convection air generated by the rotation of the disk. Thereby, the cooling effect of the lens holder 3 by the protrusion part 6 can be heightened more.

  4 and 5, the groove 11 is formed so as to reach the coil substrates 2 a and 2 b disposed at the end of the protruding portion 6. Therefore, the air that has entered the groove 11 flows along the groove 11 and reaches the coil substrates 2a and 2b on both sides. This increases the amount of air reaching the coil substrates 2a and 2b, which are heat sources, and can further enhance the cooling effect of the coil substrates 2a and 2b.

  4 and 5, two grooves 11 are formed in each protrusion 6. However, the presence / absence of the grooves 11, the number of grooves 11, and the formation range of the grooves 11 are appropriately determined. That's fine. Moreover, what is necessary is just to determine suitably also about the number of the protrusion parts 6. FIG.

  Hereinafter, the simulation results of the present invention will be described with reference to FIG. 6A is a perspective view showing a comparative example, and FIG. 6B is a perspective view showing an embodiment. The lens holder 20 according to the comparative example has a bottomed box-like body (open on the top and bottom on the bottom) with a height h = 8 mm, a width w = 12 mm, a depth d = 8 mm, and a thickness t1 = 1 mm. It is formed of a member (1 W / ° C. m). On the other hand, the lens holder 30 according to the embodiment shown in FIG. 6B has a total of six protrusions 31 having a thickness t2 = 1 mm on one surface of the lens holder 20 shown in FIG. It is provided. The protruding portion 31 has the same configuration as that of the first embodiment, and the protruding distance is set to 1 mm, 2 mm, and 3 mm in order from the top.

  At an environmental temperature (ambient air temperature) of 50 ° C., 1 W of heat was applied to each of the lens holders 20 and 30, and air (50 ° C.) with a flow velocity of 3 m / s was applied from above (in the direction of the arrow in the figure). As a result, the average temperature of the lens holder 20 according to the comparative example was 99 ° C., whereas the average temperature of the lens holder 20 according to the example was 87 ° C. The addition of the protrusion 31 confirmed the effect of reducing the temperature by 12 ° C. (12%).

  According to the present invention, since the cooling effect of the objective lens can be enhanced with an inexpensive and simple configuration, the present invention is particularly suitable for an optical recording / reproducing apparatus that is designed to be small, thin, and high in speed. Useful as a pickup.

1 is a plan view of an optical pickup according to Embodiment 1 of the present invention. The perspective view of the lens holder 3 shown in FIG. Sectional drawing in the AA line of FIG. The perspective view of the lens holder 3 which concerns on Embodiment 2 of this invention. Sectional drawing in the BB line of FIG. It is a figure explaining the simulation result of this invention, (a) is a perspective view which shows a comparative example, (b) is a perspective view which shows an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Objective lens 2a, 2b Coil board | substrate 3 Lens holder 4a, 4b Magnet 5a, 5b, 5c, 5d Suspension wire 6,31 protrusion part 7 Disk 8 Spindle motor 9 Convection by disk rotation 10 Optical pick-up 11 Groove

Claims (5)

An optical pickup that includes an objective lens and a support member that supports the objective lens, and controls a relative position between the objective lens and the information recording medium,
The support member forms a plurality of protrusions that protrude away from the optical axis of the objective lens,
When the support member is viewed from the objective lens side, at least one of the plurality of protrusions has a portion extending from the other protrusions on the information recording medium side. apparatus.   2. The optical pickup device according to claim 1, wherein the plurality of protruding portions include the extended portion except for the protruding portion closest to the information recording medium.   The support member is provided with a magnetic field generating means for driving the support member, and the magnetic field generating means is opposed to an end portion of the protruding portion in a direction orthogonal to the protruding direction of the protruding portion. The optical pickup device according to claim 1, wherein the optical pickup device is disposed.   4. The optical pickup device according to claim 1, wherein at least one of the plurality of protrusions forms a groove on the information recording medium side. 5.   The support member is provided with a magnetic field generating means for driving the support member, and the magnetic field generating means is opposed to an end portion of the protruding portion in a direction orthogonal to the protruding direction of the protruding portion. 3. The optical pickup device according to claim 1, wherein at least one of the plurality of projecting portions is formed with a groove whose leading end reaches the end portion on the information recording medium side.

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