JP2002304758A - Optical head unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical head unit capable of sufficiently emitting heat generated at the heat generative electronic component of a drive IC 106 or the like to the outside. SOLUTION: A heat generative electronic component (IC) is brought into contact with a wall surface part provided in an optical base 3 made of a metallic material. Thus, thermal connection from the IC to the optical base is increased, and heat generated at the IC is sufficiently emitted to the optical base.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device, and more particularly to a heat dissipation structure of an optical head device having a built-in heat-generating electronic component.

[0002]

2. Description of the Related Art Due to the recent development of technology, optical disk devices have been reduced in size and weight year by year, and particularly in portable type optical disk devices.

[0003] In the flow of such technology, the size of the optical head has also been reduced. However, the optical head is a core component that can be called the heart of the optical disc device, and heat-generating components such as ICs are mounted on the optical head base. There is a contradictory issue to be addressed.

Japanese Patent Laid-Open No. 11-18 / 1999 discloses a heat radiation structure for an optical head incorporating such heat-generating electronic components.
What is described in 5273 gazette is known.

FIG. 5 shows a heat radiation structure of a conventional optical head device, particularly at a laser mounting portion. Here, description of the configuration of the entire optical head is omitted.

Reference numeral 101 denotes an optical base, reference numeral 102 denotes a laser diode mounting base fixed to the optical base 101, and reference numeral 103 denotes a laser diode as a light emitting element, which is fixed to the laser diode mounting base 102. Further, a circuit board 105 is fixed to the laser diode mounting base 102 via a shield base 104.
The three legs are connected and fixed, and an IC for driving a laser diode (hereinafter, drive IC 106) is mounted.

Furthermore, in this optical head device, a driving IC
The entire circuit board 105, including 106, is covered by a shield case 107 for electromagnetic waves, which is fixed to the laser diode mounting base 102. Drive IC
A heat transfer member 108 having better heat conductivity than air, for example, a silicone gel, a special rubber material, a sponge material, or the like is interposed between the shield case 107 and the heat transfer member 108.

With such a structure, the driving IC 10
6 is transmitted to the shield case 107 through the heat transfer member 108, and further, to the shield case 107.
Released into the air from the surface.

[0009]

However, in the optical head device having the above-described structure, there is a problem that the heat radiation may be insufficient as described below.

Since the shield case 107 is originally intended for measures against electromagnetic waves, a thin metal material of about 0.1 to 0.2 mm is generally used. However, the heat transfer performance is represented by thermal resistance, and the thermal resistance has the property of increasing as the cross-sectional area is smaller, similarly to electrical resistance. That is, since a thin material used for the shield case 107 has a large thermal resistance, heat does not easily spread to the entire shield case 107, and the heat radiation performance may be insufficient.

Further, since the shield case 107 has a cap-like form, it is generally formed by drawing, and it is difficult to use a thick material in terms of processing. Further, in the above conventional example, the driving IC 1
The heat transfer member 108 is interposed between the heat transfer member 106 and the shield case 107. The heat conductivity of silicon gel or the like is significantly smaller than that of a metal material such as aluminum. The maximum is about 5 Wm ° C., but the aluminum material is 200 Wm ° C. or more. Therefore, when the heat transfer member 108 interposed is thick, there is a problem that the thermal resistance is increased and the heat radiation characteristics are significantly reduced.

In the above-described conventional example, the driving IC
It is necessary to arrange the arrangement of the laser diode 103 on the left and right. Generally, since an IC package takes a plate-like form, the dimensions in the width and length directions are larger than those in the thickness direction. Therefore, as in the above-described conventional example, the laser diode 1
03 and the drive IC 106 are arranged side by side, the space required for mounting both of them needs to be as wide as the width of the laser diode 103 and the width of the package of the drive IC 106, which hinders miniaturization. Problem.

An object of the present invention is to provide an optical head device capable of sufficiently releasing heat generated by heat-generating electronic components such as the drive IC 106 to the outside.

Further, the present invention provides a heat radiation
An object of the present invention is to provide an optical head device suitable for miniaturization of the arrangement of the heat-generating electronic components such as the drive IC 106 and the laser diode 103.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to an optical head device having a built-in heat-generating electronic component near a light-emitting element. And the heat generated by the electronic component is released to the optical base.

The optical base is made of metal.

Further, the electronic component and the light emitting element are electrically connected by a flexible substrate.

Further, a vertical wall is provided on the optical base so as to be rearward with respect to the light emitting direction of the light emitting element mounted on the optical base and substantially perpendicular to the light emitting optical axis, and the electronic component is in close contact with the vertical wall. And thermally connected.

Also, a vertical wall is provided between the light emitting component and the electronic component.

[0020]

(Embodiment 1) Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory diagram showing a configuration near a light emitting element in an optical head device according to the present invention, and FIG. 2 shows an optical disk drive device as a whole.

In FIG. 1, reference numeral 1 denotes an optical disk which rotates together with a spindle motor (not shown). Reference numeral 2 denotes an entire optical head device, and an optical base 3 of the optical head device.
Are supported movably in the radial direction of the optical disk 1 along the two guide shafts 4a and 4b, and are slid by an optical head feed mechanism (not shown) as the optical disk 1 rotates. .

The optical base 3 of the optical head device 2 incorporates a light emitting element for emitting laser light, a laser diode 5, a photodetector (not shown) for detecting laser light, and other optical components (not shown). The light emitted from the laser diode 5 is applied to the signal recording surface of the optical disc 1 through the objective lens 6, and the reflected light returns through the objective lens 6 and is detected by the photo detector.

FIG. 1 shows the structure near the laser diode 5 mounting portion in the optical head device 2. The laser diode 5 is fixed to the optical base 3. The optical base 3 is provided with a vertical wall 8 that is orthogonal to the light emitting optical axis 7 of the laser diode 5 and opposite to the light emitting direction of the laser diode 5. The laser diode 5 and an integrated circuit for driving a laser (hereinafter, drive IC 9) are connected by a flexible substrate 10, and a photodetector (not shown) is similarly mounted on the flexible substrate 10 and fixed on the optical base 3. Here, the drive IC 9 is a heat-generating electronic component that consumes power during operation and generates heat. The flexible substrate 10 is drawn out of the optical head device 2 and connected to an external circuit (not shown) to exchange signals. The optical base 3 including the vertical wall 8 is made of aluminum having high thermal conductivity.

Since the driving IC 9 and the laser diode 5 are connected by the flexible substrate 10, there is no need to arrange them on the same plane, and a three-dimensional arrangement is possible. Therefore, the driving IC 9 includes the laser diode 5 and the driving IC 9.
Are mounted in close contact with the vertical wall 8 so as to sandwich the vertical wall 8.

The driving IC 9 is pressed by a leaf spring 11 from the back surface so as to be securely in contact with the vertical wall. At this time, the flexible substrate 10 connecting the laser diode 5 and the driving IC 9 is folded in a U-shape as shown in the figure. In general, the positional accuracy and the accuracy in the thickness direction when mounting the IC component on the substrate are lower than the accuracy of machining, but since the drive IC 9 is mounted on the flexible substrate 10, There is a degree of freedom in positioning, and the upper surface of the drive IC and the vertical wall 8 can be reliably brought into contact with each other. At this time, the driving IC 9 and the vertical wall 8
The flexible substrate 10 is not sandwiched between them. In other words, the surface of the drive IC 9 in contact with the vertical wall 8 is the opposite surface of the surface of the drive IC 9 facing the flexible substrate 10.

As described above, since the drive IC 9 and the vertical wall 8 can be brought into contact with each other in a plane-to-plane manner,
There is no need to interpose a heat transfer member between the vertical wall 9 and the vertical wall 8 for absorbing low positional accuracy. For this reason, the thermal resistance between the drive IC 9 and the vertical wall 8 is small and the structure is thermally connected, so that the heat generated by the drive IC 9 can be reliably transmitted to the vertical wall 8. Since the vertical wall 8 is a part of the optical base 3, the heat conducted from the driving IC 9 to the vertical wall 8 is transmitted to the optical base 3 having a large surface area and diffused into the air. Thus, according to the optical head of the present invention, the drive IC 9 is thermally connected to the vertical wall 8, that is, to the optical base 3, and the heat generated by the drive IC 9 is transferred to the optical base 3.
As a result, the thermal resistance in heat conduction can be reduced, and the temperature rise of the drive IC 9 can be sufficiently suppressed.

The drive IC 9 can be surrounded by a plate-like upper shield cover 12 and lower shield cover 13 (both not shown in FIG. 1) and the optical base 3. By doing so, the drive IC 9 is electromagnetically shielded, and measures against electromagnetic waves are taken.

Further, since the vertical wall 8 is provided behind the laser diode 5 and the flexible base is folded and mounted in a U-shape, the laser diode 5 and the driving IC 9 are not arranged side by side. Electrical wiring length can be reduced. At the same time, the size of the optical head device 2 can be reduced. The miniaturization will be briefly described as follows.

As described in the problem of the conventional example, generally, I
Since the package of C takes a plate-like form, the dimensions in the width and length directions are larger than those in the thickness direction. For this reason, when the laser diode 5 and the driving IC 9 are arranged side by side as in the conventional example, the mounting of both requires a width that is equal to the width of the laser diode 5 and the width of the package of the driving IC 9. I will. However, with the arrangement according to the present invention, the space required for mounting both of them only increases in the thickness direction of the drive IC 9, so that the size can be significantly reduced as compared with the case where they are arranged side by side in the width direction. is there.

In this embodiment, the material of the optical base 3 including the vertical wall is aluminum, but another material may be used. In other words, the material of the optical base 3 may be any material having a sufficiently high thermal conductivity, and many metal materials satisfy this. For example, alloys mainly composed of zinc or magnesium may be used. These have lower thermal conductivity than aluminum, but have sufficiently higher thermal conductivity than air or silicon gel. Even so, the effects of the present invention can be exhibited.

Although the vertical wall 8 is arranged between the laser diode 5 and the driving IC 9 in the above embodiment, this need not always be the case. For example, as shown in FIG. 3, the driving IC 9 may be provided between the vertical wall and the laser diode. In this case, on the flexible substrate, the soldering surface of the laser diode 5 and the driving IC 9
It is necessary to use a double-sided flexible substrate because the soldering surfaces of the two sides are opposite. However, there is no difference in dissipating the heat generated by the drive IC 9 to the optical base 3. It does not depart from the gist.

The shield covers 12, 13 need not be provided on both upper and lower sides. For example, a structure covered with the optical base itself instead of the upper shield cover 12 may be used.

Although no intervening member for heat conduction is inserted between the vertical wall 8 and the driving IC 9, this is not necessarily the case. For example, thin silicon grease may be applied to the surface of the drive IC 9. As a result, the gap generated by the very small irregularities on the surface of the drive IC and the surface of the vertical wall 8 is filled with silicon grease having a higher thermal conductivity than air, so that the thermal resistance between the drive IC 9 and the vertical wall 8 is reduced. The size can be reduced, and a more preferable state can be realized.

The leaf spring 11 for pressing the drive IC 9 against the vertical wall 8 may not be provided depending on the configuration. For example, the leaf spring 11 may be pressed by the elasticity of the flexible substrate 10 itself.

It is not always necessary to use the vertical wall 8. For example, the IC may be facing up. In that case,
As shown in FIG. 4, the space required on the rear side of the laser diode 5 is slightly increased, but there is no difference in dissipating the heat generated by the drive IC 9 to the optical base 3. This does not depart from the whole spirit of the present invention.

In the above embodiment, the flexible substrate 10 for connecting the drive IC 9 and the laser diode 5 is folded into a U-shape, but this is not necessarily required. The flexible substrate 10 may be bent in any manner as long as the drive IC 9 can be brought into close contact with the optical base including the vertical wall 8.

In the above embodiment, the drive IC 9 having the function of driving the laser is used as the electronic component having heat generation. However, the present invention is not limited to the drive IC 9 having the function of driving the laser. It is apparent that heat can be released to the optical base 3 with the same configuration as long as the electronic component has heat generation. For example, the same effect can be obtained by applying the present invention to an IV conversion integrated circuit that converts a current signal detected by a photodetector into a voltage signal.

Although the light emitting element is shown as the laser diode 5 in the above embodiment, it does not necessarily have to be constituted by the laser diode 5 alone. For example, a light-receiving / light-emitting element in which optical components such as a light-receiving photodetector and a beam splitter are integrated in one package in addition to the light-emitting element may be used. In this case, the laser diode 5 shown in the above embodiment may be used. Obviously, the same effect can be obtained by replacing the light emitting and receiving elements.

[0039]

As described above, according to the present invention, an electronic component arranged near the laser diode 5 as a light emitting element, for example, a drive IC 9 for supplying a current to the laser diode is provided in one of the optical bases 3. Since it is configured to be in close contact with the vertical wall 8 which is a part, the thermal resistance between the drive IC 9 and the optical base 3 can be reduced, and the heat generated in the drive IC 9 can be effectively released to the optical base 3. became.

In particular, since the optical base 3 is made of a metal part such as aluminum, the heat conductivity is small and the heat can be effectively released.

Further, since the driving IC 9 and the laser diode 5 are connected by the flexible substrate 10, the degree of freedom in positioning the driving IC 9 is increased, and the positioning accuracy when the driving IC 9 is mounted on the flexible substrate 10, the thickness accuracy of the parts themselves, and the like. However, the drive IC 9 and the optical base 3 can be surely brought into close contact with each other even if the value is slightly worse.

A laser diode 5 as a light emitting element
Since the vertical wall 8 is provided rearward of the light emitting direction and substantially perpendicular to the light emitting optical axis, and the vertical wall 8 and the driving IC 9 are in close contact with each other, the space for mounting the driving IC 9 can be reduced. Thus, miniaturization of the optical head can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration near a light emitting element according to an embodiment of the present invention.

FIG. 2 is an overall view of an optical head according to the present invention.

FIG. 3 is an explanatory view of another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a configuration example when there is no vertical wall;

FIG. 5 is a sectional view showing a heat dissipation structure of a conventional optical head.

[Description of Reference Numerals] 1 optical disk 2 optical head device 3 optical base 4a, 4b guide shaft 5 laser diode 6 objective lens 7 light emitting optical axis 8 vertical wall 9 drive IC 10 flexible substrate 11 leaf spring 12 upper shield cover 13 lower shield cover 101 Optical base 102 Laser diode mounting base 103 Laser diode 104 Shield base 105 Circuit board 106 Drive IC 107 Shield case 108 Heat transfer member

Continuation of front page (72) Inventor Fumicho Yamazaki 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5D117 AA02 HH01 HH11 5D119 AA50 BA01 FA32 5F073 BA05 EA29 FA15 FA23 FA30

Claims (8)

[Claims] An optical head device having a built-in heat-generating electronic component disposed in the vicinity of a light-emitting element, wherein an optical base and the electronic component are in close contact and thermally connected to each other, and the heat generated by the electronic component is generated by the electronic component. An optical head device characterized in that it is structured to escape to an optical base. 2. The optical head device according to claim 1, wherein the optical base is made of metal. 3. The optical head device according to claim 1, wherein the electronic component is an integrated circuit component for supplying a current to the light emitting element. 4. The electronic component and the light emitting element are electrically connected by a flexible substrate.
The optical head device according to the above. 5. The optical head device according to claim 4, wherein the electronic component is in close contact with the optical base on a surface facing the surface of the electronic component facing the flexible substrate. 6. A vertical wall is provided on the optical base so as to be rearward with respect to a light emitting direction of the light emitting element and substantially perpendicular to a light emitting optical axis, and an electronic component is in close contact with the vertical wall and thermally connected thereto. The optical head device according to claim 1, wherein: 7. The optical head device according to claim 6, wherein a vertical wall is arranged between the light emitting component and the electronic component on an extension of the light emitting optical axis of the light emitting element. 8. The optical component according to claim 1, wherein a heat conductive member is interposed between the electronic component and the optical base, and the electronic component and the optical base are brought into close contact with each other. Optical head device.