Holding mechanism of an optical disk clamper and an optical disk drive using the same

An optical disk clamper holding mechanism that holds an optical disk clamper includes a surrounding unit, a flange unit, a rib that touches, when the optical disk clamper moves in the direction of the flange opening, a rim portion of an upper flange unit of the optical disk clamper, the rib protruding inwardly at a position opposite to the flange opening. Since the range of clearance in which the optical disk clamper can move in the optical disk clamper holding mechanism is restricted, the optical disk clamper always fits in the turntable normally and consequently, always clamps the optical disk normally.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an optical disk clamper, and more particularly, to the retracting mechanism of an optical disk clamper and an optical disk drive using the same.

2. Description of the Related Art

A type of optical disk drive has an optical disk clamper held in a holding unit. When an optical disk is set in such type of optical disk drive, a turntable moves upward and the optical disk clamper fits in and is magnetically attracted by the turntable so that the optical disk is clamped on the turntable. The optical disk clamper holding unit has an opening portion through which the optical disk clamper is built in, but supports the optical disk clamper so that the optical disk clamper does not come out once built in.

FIGS. 1A–1Care schematic diagrams showing a conventional optical disk clamper holding unit10. This optical disk clamper holding unit10has a surrounding unit11, a flange unit12, and a built-in opening unit13. The surrounding unit11is shaped like a ring of which a portion is removed. The removed portion corresponds to the built-in opening unit13. Though the built-in opening unit13is formed as small as possible, no devisal is employed. The flange unit12protrudes inwardly from the surrounding unit11.

The optical disk clamper is shaped like a reel, and has a hub unit21, an upper flange unit22, and a lower flange unit23.

The optical disk clamper20is built in the optical disk clamper holding unit10through the built-in opening unit13by bending the lower flange unit23. The hub unit21is positioned inside of the flange unit12and the upper flange unit22is supported by the flange unit12in the manner that the optical disk clamper is freely movable in the optical disk clamper holding unit10, but does not come off through the built-in opening unit13.

Oc is the center of the optical disk clamper20, and Oh is the center of the optical disk clamper holding unit10.

When the turntable moves with the optical disk, the optical disk clamper10fits in the turn table and is magnetically attracted by the turn table, the optical disk is clamped on the turn table.

The range of clearance in which the optical disk clamper20is movable in the holding unit10will be considered as below. The optical disk clamper20can move in the direction of X1, X2, and Y1until the hub unit21touches the flange unit12. As showed inFIG. 1B, the optical disk clamper20can move the distance δX1in the X1direction. In the direction toward the opening unit13, that is, the Y2direction, however, the optical disk clamper20can move, as showed inFIG. 1C, until the upper flange unit22touches the edges11aand11bof the surrounding unit11, that is, the distance δY2.

The distance δY2is about twice the distance δY1. If the optical disk clamper20is moved in the holding unit10in the Y2direction, there is a risk that, when the turntable moves upward with the optical disk, the optical disk clamper10does not fit in the turn table and the optical disk is not normally clamped.

By the way,FIG. 2is a schematic diagram showing a conventional heat radiation mechanism of an electronic component. The heat radiation mechanism showed inFIG. 2is employed by disk drives such as CD-R. In this heat radiation mechanism, the heat generated by a semiconductor component220is radiated by a bottom cover250that carries out the function of a heat radiation plate.

The leads230of the semiconductor component220are connected and fixed to a circuit board210with soldering240. The semiconductor component220generates heat when it is operated.

The bottom cover250is attached to the disk drive so that the bottom cover250faces the circuit board210. This bottom cover250is made of highly conductive metal plate and functions as a heat radiation plate. A heat radiation unit260is formed at the position opposed to the semiconductor component220on the bottom cover250so that the distance between the bottom cover250and the semiconductor component220becomes small.

Conventionally, a heat radiation sheet270is provided on the semiconductor component220to thermally connect the semiconductor component220and the bottom cover250so that this heat radiation sheet270touches the bottom cover250(heat radiation unit260) when the bottom cover250is attached to the optical disk drive. The heat generated by the semiconductor component220is transferred to the bottom cover250through the heat radiation sheet270and radiated by the bottom cover250.

However, in the case of the above structure wherein the heat radiation mechanism uses a portion of an apparatus (a disk drive in this case) into which the heat radiation mechanism is built as an element of the heat radiation mechanism, the performance of the heat radiation mechanism is affected by assembly error of the apparatus, manufacturing error of components, and tolerances (hereinafter, these are referred to as “assembly errors” as a whole).

That is, in the case where the assembly errors exist when the bottom cover250is assembled to the disk drive, and/or the case where the assembly errors exist when the circuit board210is assembled to the disk drive, the heat radiation sheet270may not touch the bottom cover250(heat radiation unit260) as showed inFIG. 3. If the heat radiation sheet270does not touch the bottom cover250, the heat generated by the semiconductor component220is not efficiently transferred to the bottom cover250.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a novel and useful optical disk clamper holding unit and an optical disk drive by which the problem described above is eliminated.

To achieve the above object, an optical disk clamper holding mechanism that holds an optical disk clamper having a hub, an upper flange unit, and a lower flange unit, according to an embodiment of the present invention, includes a surrounding unit that holds said upper flange unit, a flange unit that supports said upper flange unit and holds said hub unit, said flange unit being shaped like a semicircle, projecting inwardly from said surrounding unit and having a flange opening unit between edges in the circumferential direction, a rib that stops, when said optical disk clamper moves in the direction of said flange opening unit, a rim portion of said upper flange unit of said optical disk clamper, said rib protruding inwardly at a position opposite to said flange opening unit.

Compared to the conventional optical disk clamper holding unit, the range of clearance in which the optical disk clamper can move in the optical disk clamper holding mechanism is restricted. Accordingly, the optical disk clamper always fits in the turntable normally and consequently, always clamps the optical disk normally. The optical disk clamper holding mechanism according to the present invention improves the reliability of clamping.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description of the preferred embodiments of the present invention will be given after a brief description of an optical disk drive.FIG. 4is a top view showing an optical disk drive30. A disk tray and an optical base unit assembly are not shown inFIG. 4.FIGS. 5A and 5Bare side views showing the optical disk drive30. The disk tray is not shown. The arrow X1-X2indicates the width direction of the optical disk drive30; the arrow Y1-Y2indicates the depth direction of the optical disk drive30; and the arrow Z1-Z2indicates the height direction of the optical disk drive30.

The optical disk drive30includes a housing31that is a box made of synthetic resin, a disk tray (not showed), and an optical base unit assembly40. The optical disk drive30is horizontally built into the system unit of a computer and so forth.

The optical base unit assembly40is provided with a square supporting base41, a turn table42, a motor43that rotates the turn table42, an optical head44that reads information recorded in an optical disk70, and a motor (not showed) that actuates the optical head44. The supporting base41has an axis45that is located on the Y1side of the supporting base41and protrudes in the X1-X2direction. The axis45is supported by a bearing32of the housing31. The supporting base41further has a rod46that is located on the Y2side of the supporting base41. The rod46is supported by a cam ditch formed on a cam member33fixed on the housing31. Accordingly, the optical base unit assembly40is supported in the housing31. As showed inFIG. 5A, when the optical disk drive30is not being operated, the optical base unit assembly40tilts with the Y2side of the optical base unit assembly40moved downward. The turntable42is positioned at a lower level. The optical disk70is, for example, a CD, a CD-ROM, a CD-R, a CD-RW, and a DVD.

As showed inFIG. 6the turntable42is provided with a cone trapezoid shaped convex unit42aat the center of the turntable42, a hole unit42bat the center of the convex unit42a, and a ring-shaped permanent magnet42cfixed on the top face of the convex unit42a.FIG. 6Bshows the structure of the turntable42in detail.

The housing31has a bridge unit34crossing in the X1-X2directions at the top face side, and an optical disk clamper holding unit50at the center of the bridge unit34. An optical disk clamper60(showed inFIG. 6A) is built into this optical disk clamper holding unit50with some clearance as showed inFIGS. 4 and 5A.

The optical disk clamper60is a reel shaped component made of synthetic resin that has a hub unit61, upper flange unit63, and a lower flange unit62. The optical disk clamper60is provided with a concave unit64at the center of the bottom face and a convex unit65protruding downward at the center of the concave unit64. The convex unit65, a ring shaped steel member, is built into the concave unit64.

When the disk tray is actuated by a disk tray moving mechanism35to set an optical disk70in the housing31, the cam member33moves in the X2direction, the cam ditch pushes up the rod46, and the optical base unit assembly is set at a horizontal position as showed inFIG. 5B. The optical disk70of which the rim around the center hole is supported by the turntable42floats over the disk tray, and the optical disk clamper60is slightly pushed up. The convex unit42afits in the concave unit64, and the hole unit42balso fits around (receives) the convex unit65. Since the steel convex unit65is attracted by the permanent magnet42c, the optical disk70is clamped on the turntable36. Then, a motor43is activated to rotate the optical disk70and the information recorded in the optical disk70is read by the optical head44. While being rotated, the optical disk clamper60remains at a position in which it does not touch the optical disk clamper holding unit50.

When the optical disk drive10is instructed to stop, it reverses the operation of loading. The optical base unit assembly30tilts as showed inFIG. 5A, and the disk tray is subsequently moved in the Y2direction. The optical disk is released from the clamp and discharged out of the housing31.

The optical disk clamper holding unit50will be described next.

As showed inFIGS. 7A,7B and8, the optical disk clamper holding unit50is a shaped component made of synthetic resin. It has a surrounding unit51, a flange unit52, a connection unit53, ribs54,55, a built-in opening unit56, and opening units57,58.

The surrounding unit51is shaped like a ring, of which a portion of ¼ is removed. The removed portion is the opening unit57. The surrounding unit51holds the upper flange unit63of the optical disk clamper60.

The flange unit52inwardly protrudes from the Z2side of the surrounding unit51and is substantially shaped like a semicircle. The opening58is provided between the two end edges of the flange52in the circumferential direction. The built-in opening unit56is formed between the flange opening unit58and the surrounding opening unit57.

The inner diameter D1of the surrounding unit51is greater than the diameter D11of the upper flange unit63of the optical disk clamper60. The inner diameter D2of the flange unit52is greater than the diameter D12of the hub unit61of the optical disk clamper60. The opening unit57is in the X-Z plane, and the built-in opening unit56is in the X-Y plane. As showed inFIG. 8, W1indicates the width of the opening unit57in the X1-X2directions, and at the same time, is the width of the Y2edge of the built-in opening unit56. W1is shorter than the diameter D11of the upper flange unit63of the optical disk clamper60. The width W1is the shortest length wherein the optical disk clamper60can be built into the optical disk clamper holding unit50. W2indicates the width of the flange opening unit58in the X1-X2directions, and is equal to the diameter D12of the hub unit61of the optical disk clamper60.

The connection unit53stretches in the X1-X2directions and connects both edges of the surrounding unit51at the upper side. The connection unit53reinforces the portion of the surrounding unit51that protrudes from the bridge unit34in the Y2direction.

The ribs54,55protrude from the respective edges51a,51bof the surrounding unit51in the radial direction toward the center Oh of the optical disk clamper holding unit50. The width of the ribs54and55is W10. The ribs54and55reduce the clearance of the optical disk clamper60in the Y2direction in the disk clamper holding unit50without making it difficult to build the optical disk clamper60into the optical disk clamper holding unit50. The ribs54and55are formed in the portion of the surrounding unit51that is opposite to the flange opening unit58.

When one builds the optical disk clamper60into the optical disk clamper holding unit50as showed inFIG. 9E, he/she slants the optical disk clamper60as showed inFIG. 9A, and inserts an upper portion of the optical disk clamper60into the built-in opening unit56until the upper flange unit63comes to above the flange unit52. As showed inFIGS. 9B,9C, and9D, the optical disk clamper60is pushed into the optical disk clamper holding unit50and, at the same time the Y2side of the optical disk clamper60is pulled up so that the optical disk clamper60returns to the horizontal position. He/she slightly bends the lower flange unit62to put it under the flange unit52. The hub unit61enters the inside of the flange unit52through the flange opening unit58. The ribs54and55do not disturb the optical disk clamper60when the optical disk clamper60is built into the optical disk clamper holding unit50.

As showed inFIGS. 4,5A,9A, and10A, when the optical disk clamper60is built into the optical disk clamper holding unit50, the hub unit61is positioned in the flange unit52and the upper flange unit63is supported by the flange unit52. A portion of the upper flange unit63protrudes from the optical disk clamper holding unit50in the Y2direction. The optical disk clamper60is movable in the optical disk clamper holding unit50, but it is supported so that it does not come off through the flange opening unit58. Oc indicates the center of the optical disk clamper, and Oh indicates the center of the optical disk clamper holding unit50.

The range of clearance in which the optical disk clamper60is movable in the holding unit50will be discussed below.

As showed inFIGS. 10B,10C, and10D, the movement of the optical disk clamper60in the direction of Y1, X1, and X2is restricted because the hub unit61touches the inner edge52aof the flange52. The ranges in which the optical disk clamper60can move freely are δY1a, δX1a, and δX2a, respectively, all of which are small.

As showed inFIG. 10E, in the case of the direction in which the optical disk clamper60comes out through the flange opening unit58, that is, the Y2direction, the movement of the optical disk clamper60is restricted because the rim portion of the upper flange unit63of the optical disk clamper60on the Y2side touches the ribs54and55. The range in which the optical disk clamper60can move in the Y2direction is δY2a.

If the ribs54and55do not exist, the optical disk clamper60moves until the rim portion of the upper flange unit63of the optical disk clamper60on the Y2side touches the edge portions51aand51bof the surrounding unit51in the circumferential direction. The movable range becomes δY2b.

The above range δY2ais about a half of the range δY2b, and is at the same size range as the above ranges δY1a, δX1a, and δX2a.

Accordingly, since the ribs54and55are provided, the movable range in which the optical disk clamper60can move in the holding unit50becomes equally short in all the directions. Whichever direction the optical disk clamper60is moved, an optical disk70is clamped normally, when the turntable moves upward with the optical disk70as showed inFIGS. 5A and 5B, since the convex unit42asurely fits in the concave unit64and the hole unit42bsurely fits around and receives the convex unit65.

FIGS. 11A and 11Bshow another embodiment of the present invention. InFIGS. 11A and 11B, elements corresponding to those showed inFIGS. 7A and 7Bare referred to by the same numerals. An optical disk clamper holding unit50A has ribs54A and55A. The ribs54A and55A are each shaped like a triangle of which the width W11at the Z1side is shorter than the width W10.

According to this structure, when the optical disk clamper60is slightly pushed up in the Z1direction in the optical disk clamper holding unit50A to clamp the optical disk70, the distance between the rim portion of the upper flange unit63of the optical disk clamper60and the ribs54A and55A becomes greater compared to the distance before the optical disk clamper60is pushed upward. Accordingly, when the optical disk clamper60is rotated in the optical disk clamper holding unit50A, the risk that the optical disk clamper60touches the ribs54A and55A is eliminated.

FIGS. 12A and 12Bshow an optical disk clamper holding unit50B according to yet another embodiment of the present invention. InFIGS. 12A and 12B, elements corresponding to those showed inFIGS. 7A and 7Bare referred to by the same numerals. The surrounding unit51B is shaped like a ring, but no portion of the ring is removed. The surrounding unit51B does not have an opening unit corresponding to the opening unit57showed inFIG. 7B. Ribs54B and55B are formed at positions on the inner face of the surrounding unit51B opposite to the flange opening unit58.

As described above, according to an aspect of the present invention, a rib is provided on the surrounding unit at a position opposing the flange opening unit, the rib protruding toward the inside of the surrounding unit. When the optical disk clamper moves in the direction to the opening unit in a manner so that the optical disk clamper comes off through the opening unit, the rib stops the rim portion of the upper flange unit of the optical disk clamper. Accordingly, the range of clearance in which the optical disk clamper can move in the optical disk clamper holding unit in the direction toward the opening unit is restricted. Consequently, the optical disk clamper always fits in the turntable normally, and the reliability of the clamping of an optical disk is improved. The rib, however, does not disturb the assembly of the optical disk clamper and the optical disk clamper holding unit.

According to another aspect of the present invention, the width at the upper side of the rib described above may be shorter than the width at the lower side of the rib. Accordingly, in the case the optical disk is clamped and, as a result, the optical disk clamper is slightly pushed up, the gap between the rim portion of the upper flange unit of the optical disk clamper and the rib becomes greater, compared to the gap before the optical disk clamper is pushed up. Consequently, the risk of the optical disk clamper touching the rib while the optical disk clamper is rotating is eliminated.

According to yet another aspect of the present invention, an optical disk drive can have the optical disk clamper holding unit described above, a turn table that clamps the optical disk with the optical disk clamper, and an optical head that reads information recorded in the optical disk rotated by the turn table. Accordingly, it is possible to improve the reliability of clamping for the optical disk drive.

By the way,FIGS. 18 and 19show a heat radiation mechanism300A for an electronic component according to an embodiment of the present invention. This heat radiation mechanism300A can be built in a disk drive100showed inFIGS. 13–15, for example. A brief description on the disk drive100will be given before the heat radiation mechanism300A.

The disk drive100is, for example, a CD-R/CD-RW drive. The disk drive100mainly includes a base chassis110, a tray120, a traverse base130, a bottom cover140, and a circuit board310.

The base chassis110is shaped like a box, and each component constituting the disk drive100, such as the tray120, the traverse base130, the bottom cover140, is provided inside of the base chassis110. A bridge unit190is provided over the base chassis110as showed inFIG. 13, and a clamper200is built in at the center of the bridge unit190. When a disk is set at the disk drive100, the clamper200and a turntable (not showed) provided in the traverse base130together clamp the disk and rotate it at a predetermined rotative speed.

The tray120can move in the directions indicated by an arrow X1-X2. A disk supporting unit150is formed on the tray120to support the disk. In the case where the tray120moves in the X1direction relative to the base chassis110(eject state), the disk is set in or removed from the tray120. When the tray120moves in the X2direction relative to the base chassis110(loading state), the disk is clamped between the clamper200and the turntable and rotated. The optical pickup170reads and/or writes information in the disk.

The traverse base130moves up and down relative to the tray120. The traverse base130is provided with the turntable and the optical pickup170as described above. The optical pickup170is supported by guiding shafts180at both sides, and moves in the radial direction (indicated by an arrow X1-X2) of the disk loaded in the disk drive100to write and read information in the disk.

In addition, the tray120is provided with an opening unit160. The above turntable meets the clamper200through this opening unit160, and the optical pickup170performs reading and writing operations through the opening unit160.

While the tray120is moving to eject or load the disk, the turn table stays at a lower position so that the turn table does not disturb the motion of the tray120. When the tray120moves to the loading position, the turntable and the traverse base130move upward together to clamp the disk by fitting in the clamper200.

The traverse base130is positioned so that the traverse base130covers the circuit board310provided at the bottom of the base chassis110. The circuit board310is provided with various electronic components such as a semiconductor component320. These electronic components write and read information in the disk, and actuate various actuators (such as actuating mechanisms of the tray120).

If the circuit board310is exposed to the exterior of the disk drive, the circuit board310may gather dust or the electronic components such as the semiconductor component320may be damaged. The bottom cover140is provided so that the circuit board310does not gather dust and the electronic components are not damaged. The bottom cover140is made of metal plate such as steel plate having high thermal conductivity.

FIG. 15is bottom view of the disk drive100showing the bottom cover140provided at the bottom of the base chassis110. As showed in the figure, a heat radiation mechanism300A and a checking window400are formed on the bottom cover140.

The checking window400is described by reference toFIG. 16in addition toFIG. 15. A ground harness410is connected to the circuit board310. This ground harness410is connected to a connector420provided on the circuit board310. The ground harness must be connected to the, circuit board310so that the electronic circuit provided on the circuit board310is normally operated. An inspection is performed to assure that the ground harness410is surely connected to the circuit board310.

This inspection is performed after the bottom cover140is assembled on the base chassis110since the ground harness410may come off the connector420when the bottom cover140is assembled on the base chassis110. However, it is very difficult to check whether the ground harness410is connected to the connector420after the bottom cover140is assembled on the base chassis110because, conventionally, the position where the connector420is provided is covered by the bottom cover140as showed inFIG. 17.

Contrary to the related art, according to an embodiment, the bottom cover140is provided with a checking window400at a position where the connector420faces when the bottom cover140is assembled to the base chassis110. As showed inFIG. 16, even if the bottom cover140is assembled to the base chassis110, one can check through the checking window400whether the ground harness410is firmly connected to the connector420. Accordingly, it becomes easy to check the connection of the ground harness41and the connector42.

The heat radiation mechanism300A will be described next. As showed inFIG. 15, two heat radiation mechanisms300A, which are identical, are provided in this embodiment.

FIGS. 18 and 19are enlarged side views showing the heat radiation mechanism300A. The heat radiation mechanism300A according to an embodiment is structured to radiate the heat generated by the semiconductor component320provided on the circuit board310. Though the heat radiation mechanism according to this embodiment radiates the heat generated by the semiconductor component320as an electronic component, the present invention is not limited to the heat radiation for the semiconductor component320, but applicable to other heat-generating components.

The semiconductor component320is fixed on the circuit board310by soldering the lead330to the circuit board310(solder340). This semiconductor component320generates heat while it is activated so that the disk drive reads or writes information in the disk. A heat radiation sheet370A is provided on the top face of the semiconductor component320(the semiconductor component320is upside down inFIGS. 18 and 19). This heat radiation sheet370A is mainly made of silicone resin having high thermal conductivity. The heat radiation sheet370A has high thermal conductivity. Since the main component of heat radiation sheet370A is silicon, the heat radiation sheet370A is flexible.

On the other hand, as described before, the bottom cover140opposing to the circuit board310is made of steel plate having high thermal conductivity. Additionally, the heat radiation unit360is formed on the bottom cover140at the position opposing to the semiconductor component320. Accordingly, the bottom cover140is structured to approach the semiconductor component320.

The bottom cover140(heat radiation unit360) according to this embodiment is provided with a boss unit380protruding toward the electronic component at the position in which heat radiation sheet370A touches the bottom cover140. The boss unit380is formed on the bottom cover140as a monolith. The boss unit380according to this embodiment is shaped like a hemisphere and the bottom cover140according to this embodiment is provided with only one boss unit380at the center of the heat radiation unit360. However, the shape of the boss unit380is not limited to a hemisphere, but can be another shape that increases the contact area with the heat radiation sheet370A. The number of the boss units380is not limited to one, but can be a plurality in order to increase the contact area with the heat radiation sheet370A.

By the way, the manufacturing of the disk drive10inevitably involves assembly error of the apparatus, manufacturing error of components, and tolerances (hereinafter, these are referred to as “assembly errors” as a whole). If the assembly errors are too great, the heat radiation sheet370A and the bottom cover140(heat radiation unit360) may separate (not be in contact).

However, the heat radiation mechanism according to the embodiment includes the boss unit380protruding toward the semiconductor component320, the boss unit380formed on the bottom cover140at the position at which the bottom cover140touches the heat radiation sheet370A. Accordingly, the boss unit380surely touches the heat radiation sheet370A even if the distance between the semiconductor component320and the heat radiation unit360(bottom cover140) exceeds a predetermined value due to the above assembly errors. That is why the height of the boss unit380is set at a value greater than the maximum value of the above assembly errors and the like.

Accordingly, even if the assembly errors exist, the bottom cover140surely touches the heat radiation sheet370A, and consequently, the heat generated by the semiconductor component320is surely radiated by the bottom cover140through the heat radiation sheet370A.

On the other hand, in the case where the heat radiation sheet370A approaches the bottom cover140(heat radiation unit360) due to the assembly error, the boss unit380presses hard the heat radiation sheet370A. However, as described above, since the heat radiation sheet370A is flexible, the force is absorbed by the flexibility of the heat radiation sheet370A.

Accordingly, the structure having the boss unit380on the bottom cover140does not damage the bottom cover140and the semiconductor component320. Additionally, because the bottom cover140(heat radiation unit360) touches hard the heat radiation sheet370A, the heat generated by the semiconductor component320is surely transferred to the bottom cover140.

FIG. 20is an enlarged side view of a heat radiation mechanism300B according to another embodiment of the present invention. The heat radiation mechanism300B is characterized in that boss units430A and430B are formed on the heat radiation sheet370B.

As the boss units430A and430B are formed one on each side of the heat radiation sheet370B that is provided between the semiconductor component320and the bottom cover140, even if the distance between the semiconductor component320and the heat radiation unit360(bottom cover140) becomes more than a predetermined value due to the assembly errors and the like, the boss units430A and430B touch the semiconductor component320and the bottom cover140(heat radiation unit360). That is why the height of the boss units430A and430B is set at a value greater than the maximum value of the above assembly errors and the like. Accordingly, even if the assembly errors and the like occur, the semiconductor component320and the bottom cover140surely touch each other through the heat radiation sheet370B, and the heat generated by the semiconductor component320is surely radiated.

On the other hand, in the case where the distance between the semiconductor component320and the bottom cover140(heat radiation unit360) is shortened due to the assembly errors and the like, the boss units430A and430B are pressed hard by the semiconductor component420and the bottom cover140(heat radiation unit360). However, since the heat radiation sheet370B is also flexible, the force of the semiconductor component320and the heat radiation unit360pressing the boss units430A and430B is absorbed by the flexibility of the heat radiation sheet370B, and the force does not cause the semiconductor component320and the bottom cover140to be damaged. Additionally, because the bottom cover140(heat radiation unit360) touches hard the heat radiation sheet370B, the heat generated by the semiconductor component320is surely transferred to the bottom cover140for radiation.

According to an aspect of the present invention, a heat radiation mechanism according to an embodiment includes an electronic component mounted on a circuit board, a heat radiation plate, a heat radiation sheet provided between the electronic component and the heat radiation plate, and a boss unit formed on the heat radiation plate at a position where the heat radiation plate touches the heat radiation sheet, the boss unit protruding toward the electronic component, wherein heat generated by the electronic component is transferred to the heat radiation plate through the heat radiation sheet.

Accordingly, in the case where the distance between the electronic component and the heat radiation plate exceeds a predetermined value due to assembly errors and the like, since the boss unit protruding toward the electronic component touches the heat radiation sheet, the heat generated by the electronic component is surely transferred to the heat radiation plate.

According to another aspect of the present invention, a heat radiation mechanism according to another embodiment includes an electronic component mounted on a circuit board, a heat radiation plate, a heat radiation sheet provided between the electronic component and the heat radiation plate, and one or more boss units formed on the heat radiation sheet at a position where the heat radiation sheet touches the electronic component and/or the heat radiation plate, wherein heat generated by the electronic component is transferred to the heat radiation plate through the heat radiation sheet.

Accordingly, in the case where the distance between the electronic component and the heat radiation plate exceeds a predetermined value due to assembly errors and the like, since the boss units formed on the heat radiation sheet touch the electronic component and the heat radiation plate, the heat generated by the electronic component is surely transferred to the heat radiation plate.

According to yet another aspect of the present invention, a heat radiation mechanism described above is characterized in that the heat radiation sheet is flexible.

Accordingly, in the case where the distance between the electronic component and the heat radiation plate becomes shorter than a predetermined value, since the force pressing the heat radiation sheet is absorbed by the flexibility of the heat radiation sheet, the force does not cause the electronic component and the heat radiation plate to be damaged.

The preferred embodiments of the present invention are described above. The present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention.

This patent application is based on Japanese priority patent application No. 2001-285132 filed on Sep. 19, 2001, and No. 2001-344692 filed on Nov. 9, 2001, the entire contents of which are hereby incorporated by reference.