JPH09319465A - Portable type equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable type equipment in which the radiating performance of a heat sink is improved, further, of which structure is simplified, cost can be reduced, and quiet operating is enabled while saving power. SOLUTION: This portable type equipment is provided with a box-shaped casing 2, 1st and 2nd circuit boards 12 and 13 housed inside the casing, TCP 26 mounted on the 1st circuit board so as to generate heat while operating, heat sink 50 arranged on the 1st circuit board so as to discharge heat propagated from the TCP, and motor-driven fan 65 for sucking air inside the casing and discharging this air through the heat sink to the outside of the casing. The 2nd circuit board has a cover part 81 facing the heat sink, and this cover part constitutes a cooling air passage 82 inside the casing while cooperating with the heat sink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable device having a circuit element which generates heat during operation, and more particularly to a structure for promoting heat radiation of the circuit element.

[0002]

2. Description of the Related Art In recent years, the performance of book-type or notebook-type portable computers has been remarkably improved, and in particular, the processing speed of CPUs mounted on computers tends to be further increased. This type of CPU is mounted on a circuit board, and is housed in a computer housing together with the circuit board.

By the way, as the processing speed of the CPU increases, the power consumption of the CPU increases, and the amount of heat generation increases accordingly. Therefore, when accommodating a CPU that generates a large amount of heat in the housing, it is necessary to improve the heat dissipation performance of the CPU inside the housing.

As a method for promoting heat dissipation from a CPU, conventionally, a circuit board on which the CPU is mounted is provided with a heat conductive cold plate in contact with the CPU, and a heat sink having an electric fan is attached to the cold plate. It has been known.

This heat sink has a heat radiating panel to which heat of the CPU is transmitted through the cold plate. The heat radiating panel is exposed to the inside of the housing substantially in parallel with the circuit board. The heat radiating panel integrally includes a large number of heat radiating fins and a fan supporting portion for supporting the electric fan. Has been formed. Therefore, when the electric fan is driven, the air inside the housing is sucked, and this air becomes cooling air and is guided to the heat radiation panel and the heat radiation fins. This air flow forcibly cools the heat dissipation panel, and the heat of the CPU transmitted to the heat dissipation panel is multiplied by the air flow to be discharged to the outside of the housing.

[0006]

In the case of the conventional heat radiation method, the heat radiation panel of the heat sink is widely opened inside the housing, and a relatively large space is formed around the heat radiation panel. There is. Therefore, the electric fan
Not only the warm air around the heat dissipation panel, but also the cold air away from the heat dissipation panel will be sucked together, and the warm air around the heat dissipation panel will be efficiently discharged to the outside of the housing. Can not be.

As a result, the heat of the CPU easily collects around the heat dissipation panel, and although the heat sink is forcibly air-cooled, the heat dissipation of the CPU is insufficient and the heat influence on the circuit board is large. There is a problem such as.

In order to deal with this problem, it is conceivable to use an electric fan with a large air flow rate or rotate the electric fan at a high speed to increase the air flow rate. However, in any case, new problems such as noise accompanying the rotation of the fan and an increase in current consumption of the fan occur, which cannot be an effective solution for improving the heat dissipation performance of the CPU.

The present invention has been made under such circumstances, and the heat around the heat sink can be efficiently discharged to the outside of the housing to enhance the heat radiation performance of the circuit element. It is an object of the present invention to provide a portable device that does not require any special parts for enhancing performance, has a simple structure, can reduce cost, and can operate quietly with low power consumption.

[0010]

In order to achieve the above object, a portable device according to a first aspect of the present invention comprises a box-shaped casing, which is housed inside the casing and spaced from each other. First and second circuit boards arranged in parallel; said first
Circuit elements that are mounted on the circuit board and generate heat during operation;
A heat sink arranged in a mounting portion of the circuit element on the first circuit board, for radiating heat transferred from the circuit element; and a heat sink housed inside the casing for removing air inside the casing. And an electric fan that sucks the air and discharges the air to the outside of the housing via the heat sink. The second circuit board integrally has a cover portion facing the heat sink, and the cover portion cooperates with the heat sink to form a cooling air passage inside the housing. Is connected to the electric fan.

In such a structure, when the electric fan is driven, the air inside the housing is sucked, and this air becomes cooling air and flows through the cooling air passage. Since the cooling air passage is formed between the heat sink and the cover portion of the second circuit board, the cooling air passage is not widely opened inside the housing, and the electric fan is mainly Intake the warm air around the heat sink intensively. Therefore, the heat dissipation performance of the heat sink is improved, and the heat of the circuit element transmitted to the heat sink can be efficiently discharged to the outside of the housing.

At the same time, since the air around the heat sink can be intensively sucked, it is not necessary to significantly increase the rotation speed of the electric fan or to use a large electric fan with a large air volume, resulting in power saving and noise reduction. It is possible to reduce.

The cover portion forming the cooling air passage is
Since it is a part of the second circuit board, a dedicated component for forming the cooling air passage is unnecessary. Therefore, an increase in the number of parts can be prevented, and the structure around the cooling air passage does not become complicated.

According to a second aspect, the heat sink according to the first aspect includes a heat radiation panel facing the cover portion of the second circuit board, and a fan support portion connected to the heat radiation panel. The electric fan is supported by a fan support portion.

With this configuration, the positional relationship between the electric fan and the heat radiation panel can be maintained optimally, and a portion that interrupts or disturbs the flow of the cooling air is interposed between the electric fan and the cooling air passage. It will not be done. Therefore, the air permeability around the heat radiating panel becomes good, and the heat radiating performance of the heat radiating panel and eventually the circuit element can be further enhanced.

According to a third aspect of the present invention, the heat dissipation panel according to the second aspect is provided with a large number of heat dissipation projections interposed in the cooling air passage. According to this structure, the contact area between the heat dissipation panel and the cooling air increases due to the presence of the heat dissipation protrusion, and the heat dissipation area of the heat dissipation panel itself increases. Therefore, the heat dissipation performance of the heat dissipation panel can be further improved.

According to a fourth aspect of the present invention, the tips of the heat radiation projections according to the third aspect and the cover portion of the second circuit board are separated from each other, and the tips of the heat radiation projections and the cover portion are separated from each other. It is characterized in that a gap is formed between them.

According to this structure, the cooling air flowing through the gap functions as a heat insulating layer, and it becomes difficult for the heat of the heat radiating protrusions to be transferred to the second circuit board. Therefore, although the cooling air passage is formed by using a part of the second circuit board, it is possible to suppress the thermal influence on the second circuit board to be small.

According to a fifth aspect, the heat dissipation panel according to the third aspect has a side wall located around the heat dissipation protrusion and extending from the heat dissipation surface toward the cover portion.
The side wall divides the cooling air passage from the inside of the housing and is connected to the fan support portion.

According to this structure, it is possible to prevent the electric fan from sucking excess air inside the housing, and the amount and flow velocity of the cooling air flowing through the cooling air passage are both increased accordingly. Therefore, the warm air around the heat sink can be more intensively discharged, which contributes to the improvement of the heat dissipation performance of the heat dissipation panel.

According to claim 6, the second circuit board according to claim 1 has a plurality of circuit elements and a wiring pattern for electrically connecting these circuit elements. Further, the wiring pattern is arranged at a position avoiding the cover portion.

According to this structure, it is possible to suppress the thermal influence on the circuit element and the wiring pattern as much as possible, and it is possible to prevent the deterioration of the function of the circuit element. To achieve the above object, the portable device according to claim 7 includes a box-shaped housing; first and first housings housed inside the housing and arranged in parallel with each other with a space therebetween. A second circuit board; the first
Circuit elements that are mounted on the circuit board and generate heat during operation;
A heat sink arranged in a mounting portion of the circuit element on the first circuit board, for radiating heat transferred from the circuit element; housed in the housing, and sucking air inside the housing And an electric fan that discharges this air to the outside of the casing via the heat sink. Then, the second circuit board integrally has a cover portion facing the heat sink, and the cover portion cooperates with the heat sink to form a cooling air passage communicating with the electric fan inside the housing. At the same time, the surface of the cover facing the cooling air passage is
It is characterized by being covered with a sheet material for shielding heat.

In such a structure, when the electric fan is driven, the air inside the housing is sucked, and this air becomes cooling air and flows through the cooling air passage. Since the cooling air passage is formed between the heat sink and the cover portion of the second circuit board, the cooling air passage is not widely opened inside the housing, and the electric fan is mainly Intake the warm air around the heat sink intensively. Therefore, the heat dissipation performance of the heat sink is improved, and the heat of the circuit element transmitted to the heat sink can be efficiently discharged to the outside of the housing.

At the same time, since the air around the heat sink can be intensively sucked, it is not necessary to significantly increase the rotation speed of the electric fan or to use a large electric fan with a large air volume, which saves power and reduces noise. It is possible to reduce.

The cover forming the cooling air passage is
Since it is a part of the second circuit board, a dedicated component for forming the cooling air passage is unnecessary. Therefore, an increase in the number of parts can be prevented, and the structure around the cooling air passage does not become complicated.

Moreover, according to the above structure, the presence of the sheet material makes it difficult for the heat of the heat sink to be transferred to the cover portion of the second circuit board. Therefore, the surface of the cover portion on the side opposite to the cooling air passage can be used as a mounting area for the circuit elements, and a large number of circuit elements can be arranged in high density on the second circuit board.

In order to achieve the above object, a portable device according to an eighth aspect of the present invention is a box-shaped housing; and a circuit element housed inside the housing and having a circuit element that generates heat during operation is mounted. 1
A second circuit board that is housed inside the housing and that is arranged in parallel with the first circuit board and that has a mounting surface that faces the first circuit board; A heat sink disposed in a mounting portion of the circuit element on the circuit board for discharging heat transferred from the circuit element; and a heat sink housed in the housing and sucking air in the housing, And an electric fan that discharges this air to the outside of the casing via the heat sink. Then, the second circuit board is
It has a cover part facing the above heat sink integrally,
The cover portion cooperates with the heat sink to form a cooling air passage communicating with the electric fan inside the housing.
The cooling air passage has a cooling air inlet located on the opposite side of the fan, and the cooling air passage faces the first circuit board on the mounting surface of the second circuit board adjacent to the cooling air inlet. It is characterized by arranging a projection that is projected to narrow the opening area of the cooling air inlet.

In such a structure, when the electric fan is driven, the air inside the casing is sucked, and this air becomes cooling air and is guided from the cooling air inlet to the cooling air passage.
Since the cooling air passage is formed between the heat sink and the cover portion of the second circuit board, the cooling air passage is not widely opened inside the housing, and the electric fan is mainly Intake the warm air around the heat sink intensively.

Moreover, since the opening area of the cooling air inlet is narrowed, the flow velocity of the cooling air flowing from the inside of the housing to the cooling air passage is increased, and the air permeability around the heat sink is improved. Therefore, the heat dissipation performance of the heat sink is further improved, and the heat of the circuit element transmitted to the heat sink can be efficiently discharged to the outside of the housing.

Further, since the air around the heat sink can be intensively sucked, it is not necessary to significantly increase the rotation speed of the electric fan or to use a large electric fan with a large air volume, which saves power and reduces noise. Is possible.

The cover forming the cooling air passage is
Since it is a part of the second circuit board, a dedicated component for forming the cooling air passage is unnecessary. Therefore, an increase in the number of parts can be prevented, and the structure around the cooling air passage does not become complicated.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows B
1 shows a portable computer 1 having a book size of 5 sizes. The computer 1 includes a flat box-shaped housing 2 and a flat panel display unit 3 supported by the housing 2.

The housing 2 is composed of a lower housing 4 and an upper housing 5 connected to the lower housing 4. The lower housing 4 has a bottom wall 4a and a pair of side walls 4b and 4c connected to the bottom wall 4a, a front wall 4d and a rear wall 4e.

The upper housing 5 has an upper wall 5a,
The peripheral portion of the upper wall 5a is connected to the side walls 4b and 4c, the front wall 4d and the rear wall 4e. The front half of the upper wall 5a is an armrest 6, and a pair of click switch buttons 7a and 7b are arranged in the center of the armrest 6. A keyboard mounting opening 9 is formed in the latter half of the upper wall 5a. The keyboard mounting opening 9 has a size that covers substantially the entire rear half portion, and a keyboard 10 is fitted into the keyboard mounting opening 9.

A pair of display supporting portions 11a and 11b are formed at the rear end of the upper wall 5a. The display support parts 11a and 11b are arranged apart from each other in the width direction of the housing 2.
The display unit 3 is rotatably supported by a hinge metal fitting (not shown) at 1b.

As shown in FIGS. 3 and 5, the housing 2 accommodates first and second circuit boards 12 and 13. The first circuit board 12 is screwed to a boss portion (not shown) on the bottom wall 4a of the housing 2 and arranged in parallel with the bottom wall 4a. The first circuit board 12 has a front surface 12a.
And a back surface 12b, and the back surface 12b faces the bottom wall 4a of the housing 2. Surface 1 of first circuit board 12
Various circuit elements 14 such as a DRAM and a card connector 15 are mounted on the back surface 2a and the back surface 12b, respectively. Further, as shown in FIG. 6, a plurality of extension connectors 16 for connecting various peripheral devices are arranged in a line at the rear of the surface 12a of the first circuit board 12.

The second circuit board 13 is the first circuit board 1.
It is arranged above the second circuit board 2 in parallel with the first circuit board 12. First circuit board 12 and second circuit board 1
3 are separated from each other in the thickness direction of the housing 2, and the circuit boards 12 and 13 are electrically connected to each other via a stacking connector (not shown).

The second circuit board 13 has a front surface 13a as a mounting surface and a back surface 13b. The back surface 13b of the second circuit board 13 is the front surface 12a of the first circuit board 12.
And face each other. Surface 13a of second circuit board 13
Various circuit elements 18 such as an LSI package are mounted on the back surface 13b and the back surface 13b, and these circuit elements 18 are connected to the wiring pattern 19 on the second circuit board 13.

On the left side of the back surface 13b of the second circuit board 13, a plurality of extension connectors 2 for connecting peripheral devices are provided.
0 and a metallic connector panel 21 that supports these expansion connectors 20 are supported. Connector panel 2
1 extends downward from the back surface 13b of the second circuit board 13 and partially closes the gap between the first circuit board 12 and the second circuit board 13 from the left side.

As shown in FIG. 3 and FIG. 8, the CPU 2 as a circuit element is provided on the back surface 12b of the first circuit board 12.
5 is installed. LSI configuring this CPU 25
As a package, TCP (Tape Carrier Package)
26 is used. TCP26 is a computer 1
The power consumption during operation has become large due to the increase in speed and the increase in capacity accompanying the diversification of the functions of, and the amount of heat generated has also become very large.

As shown in FIG. 8, the TCP 26 includes a carrier 27 made of a flexible resin film, and a carrier 27.
7 and an IC chip 28 supported in the central portion. The carrier 27 has a quadrangular shape having four edges, and a large number of leads 29 made of copper foil are formed on the carrier 27. These leads 29 are
It has one end soldered to the IC chip 28 and the other end protruding from the edge of the carrier 27.

The TCP 26 is mounted on the back surface 12b of the first circuit board 12 in a so-called face-up posture, and the other end of the lead 29 is soldered to the pad on the back surface 12b. The TCP 26 is located on the left side of the rear end of the first circuit board 12.

The first circuit board 12 has a square through hole 3
1 and four insertion holes 32a to 32d. The through hole 31 is located at the mounting portion of the TCP 26,
Facing the tip 28. The through hole 31 has a similar shape to the IC chip 28 and has an opening shape larger than the planar shape of the IC chip 28. The insertion holes 32a to 32d are outside the through hole 31, and
It is arranged at a position corresponding to the corner of this through hole 31.

As shown in FIGS. 7 and 8, a cold plate 33 is arranged on the front surface 12a of the first circuit board 12 so as to correspond to the mounting portion on the TCP 26. The cold plate 33 is made of a metal material having excellent thermal conductivity such as a copper alloy material. Cold plate 33
Has a flat square shape having a plane shape much larger than the through hole 31.

The cold plate 33 has a lower surface 33a overlaid on the front surface 12a of the first circuit board 12a and an upper surface 33b exposed on the first circuit board 12a. Boss portions 34 are provided at four corners of the upper surface 33b of the cold plate 33, respectively. Each boss 3
4 has a screw hole 35. One end of the screw hole 35 is
The upper surface of the boss portion 34 is opened and the screw hole 3
The other end of 5 is opened on the lower surface 33 a of the cold plate 33. The screw hole 35 is connected to the insertion holes 32a to 32d of the first circuit board 12.

Of these insertion holes 32a to 32d, two screw insertion holes 32a and 32c located on the diagonal line are
The screw 36 is inserted from below the first circuit board 12. The screw 36 penetrates through the insertion holes 32 a and 32 c and is screwed into the screw hole 35. The cold plate 33 is held on the first circuit board 12 by this screwing.

A heat receiving portion 38 is integrally formed at the central portion of the lower surface 33a of the cold plate 33. Heat receiving part 3
Reference numeral 8 projects downward from the lower surface 33 a of the cold plate 33 and is fitted into the through hole 31 of the first circuit board 12. The tip of the heat receiving portion 38 is a flat heat receiving surface 39. The heat receiving surface 39 is the back surface 12b of the first circuit board 12.
And the IC chip 28 is bonded to the heat receiving surface 39. Therefore, TCP2
When the 6 heats up, the heat of the TCP 26 is transmitted to the cold plate 33 through the heat receiving portion 38.

As shown in FIGS. 7 and 8, a cover 41 is attached to the back surface 12b of the first circuit board 12. The cover 41 has a square shape having substantially the same size as that of the cold plate 33.
And covers the screw 36. Through holes 42 a to 42 d are opened at the four corners of the cover 41. The through holes 42 a to 42 d are the insertion holes 3 of the first circuit board 12.
2a to 32d. Of the through holes 42a to 42d, two through holes 42b and 42d located on a diagonal line.
A screw 43 is inserted from below the first circuit board 12. The screw 43 penetrates the through holes 42b and 42d and the insertion holes 32b and 32d, and the cold plate 3
3 is screwed into the screw hole 35. By this screwing, the cover 41 is held on the first circuit board 12.

As shown in FIGS. 3, 7 and 8, a heat sink 50 is attached to the cold plate 33. The heat sink 50 is the cold plate 33.
To release the heat of TCP26 transmitted to
It is made of a metal material having excellent thermal conductivity such as a magnesium alloy or an aluminum alloy.

The heat sink 50 includes a heat dissipation panel 51,
A fan support portion 52 integrally formed with the heat dissipation panel 51
And The heat dissipation panel 51 has substantially the same size as the cold plate 33. The heat dissipation panel 51 is
It has a flat heat receiving surface 51 a facing the upper surface 33 a of the cold plate 33, and a flat heat radiating surface 51 b exposed upward of the first circuit board 12. Heat dissipation surface 5
A large number of columnar heat-dissipating protrusions 53 are integrally provided on the 1b. The heat dissipation projections 53 are arranged side by side in a matrix, and the existence of these heat dissipation projections 53 ensures a sufficient heat dissipation area of the heat dissipation surface 51b.

The heat dissipation panel 51 has four fitting recesses 54 opened in the heat receiving surface 51a. Fitting recess 5
Numeral 4 is for fitting the boss portion 34 of the cold plate 33, and the communication hole 5 is provided at the end of these fitting concave portions 54.
5 is opened. The communication holes 55 are continuous with the screw holes 35 of the boss portion 34, and the screws 56 are inserted into the communication holes 55 from above the heat sink 50. The screw 56 penetrates the communication hole 55 and is screwed into the screw hole 35. By this screwing, the heat sink 50 is held on the first circuit board 12 via the cold plate 33.

An elastic sheet 57 is interposed between the heat radiation panel 51 and the cold plate 33. The elastic sheet 57 has thermal conductivity, and is sandwiched between the heat radiation panel 51 and the cold plate 33 by tightening the screw 56.

The fan support portion 52 is a heat dissipation panel 51.
It is connected to the rear end. The fan support portion 52 is a pair of support walls 60 a and 60 b extending above the heat dissipation panel 51.
And a connecting wall 61 that straddles the lower ends of the support walls 60a and 60b. The fan support portion 52 has a first
Located at the rear end of the circuit board 12 of the lower housing 4
Is adjacent to the rear wall 4e. A notch 62 that avoids the lower end of the fan support 52 is formed in the rear edge 12b of the first circuit board 12.

An electric fan 65 is supported on the fan supporting portion 52. The electric fan 65 is the fan frame 6
6 and a rotor 67 supported by the fan frame 66.
The rotor 67 is driven to rotate by a motor (not shown). The electric fan 65 is
It is screwed to the upper surface of the connecting wall 61 of the fan frame 66 and is arranged between the supporting walls 60a and 60b.

The electric fan 65 is connected to the first circuit board 12 via a lead wire 68. The electric fan 65 is driven when the ambient temperature of the TCP 26 reaches a predetermined temperature.

As shown in FIGS. 3 and 5, the electric fan 65
Is adjacent to the rear wall 4e of the lower housing 4 inside the lower housing 4. An exhaust port 70 facing the electric fan 65 is opened in the rear wall 4e. Therefore, when the electric fan 65 is driven, the air inside the housing 2 is sucked, the air becomes cooling air, is guided to the heat sink 50, and is then discharged from the exhaust port 70 to the outside of the housing 2. To be done.

As shown in FIGS. 5 and 6, the heat dissipation panel 51
Integrally includes a side wall 75 extending upward. The side wall 75 extends in the depth direction of the housing 4 on one side of the heat dissipation panel 51 that is off the heat dissipation protrusion 53. The rear end portion of the side wall 75 is connected to one support wall 60b of the fan support portion 52.

The upper end of the side wall 75 and the upper end of the other supporting wall 60a of the fan supporting portion 52 are in contact with the back surface 13b of the second circuit board 13. A support piece 76 for supporting the second circuit board 13 is integrally formed on the upper portion of the side wall 75. The support piece 76 and the support wall 60a are integrally formed.
The second circuit board 13 is fastened and fixed via screws 77.

The heat dissipation panel 51 is integrally provided with an extension wall 78 on the side opposite to the side wall 75. Extension wall 7
The circuit board 8 is arranged between the first circuit board 12 and the second circuit board 13 in parallel with the circuit boards 12 and 13. The tip of the extension wall 78 is in contact with the connector panel 21.

As shown in FIGS. 3 and 5, the second circuit board 13 is integrally provided with a cover portion 81 facing the heat radiation panel 51 of the heat sink 50. The cover portion 81 is composed only of the insulating layer of the second circuit board 13, and the wiring pattern 19 and the circuit element 18 of the second circuit board 13 are arranged at positions avoiding the cover portion 81.

The cover portion 81 is provided on the heat radiation panel 51.
A cooling air passage 82 is formed inside the housing 2 in cooperation with the above. The cooling air passage 82 is provided on the side wall 75 of the heat dissipation panel 51.
It is partitioned from the inside of the housing 2 by the extension wall portion 78 and the connector panel 21. This cooling air passage 8
Reference numeral 2 denotes a cooling air inlet 83 that is opened toward the front of the housing 2 and a cooling air that is opened toward the rear of the housing 2 between the first circuit board 12 and the second circuit board 13. Wind exit 8
4 and. The cooling air outlet 84 is located immediately before the electric fan 65. Therefore, the electric fan 6
When 5 is driven, the air inside the housing 2 flows into the cooling air passage 82 from the cooling air inlet 83, as shown by the arrow in FIG.

Further, as shown in FIG.
The heat radiation protrusion 53 extends from the heat radiation surface 51 b toward the cover 81 and is interposed in the cooling air passage 82. The tips of the heat radiating projections 53 and the cover 81 are separated from each other, and a gap 85 is formed between the tips of the heat radiating projections 53 and the cover 81.

In such a configuration, the computer 1
Is operated, the IC chip 28 generates heat as the TCP 26 consumes power. Since the IC chip 28 is adhered to the heat receiving portion 38 of the cold plate 33, the heat of the IC chip 28 is transferred from the heat receiving portion 38 to the cold plate 33. Since the heat dissipation panel 51 of the heat sink 50 is attached to the upper surface 33b of the cold plate 33 via the elastic sheet 57, the heat of the IC chip 28 transmitted to the cold plate 33 is directly released to the heat dissipation panel 51. Be done. Heat dissipation surface 51 of heat dissipation panel 51
Since b has a large number of heat radiation projections 53, the heat radiation surface 5
The heat radiation area of 1b is increased, and the heat radiation property of the heat radiation panel 51 itself is improved.

While the computer 1 is operating, the TCP 26
When the ambient temperature of 1 reaches a predetermined temperature, the electric fan 65 starts operating. Rotor 6 of electric fan 65
When 7 is rotationally driven, the air inside the housing 2 is sucked toward the heat sink 50. That is, the electric fan 6
Since 5 is facing the cooling air outlet 84 of the cooling air passage 82, the air in the cooling air passage 82 is supplied to the electric fan 6
The air inside the housing 2 flows into the cooling air passage 82 from the cooling air inlet 83. Therefore, the air inside the housing 2 becomes cooling air, flows through the cooling air passage 82, and is discharged from the exhaust port 70 of the housing 2 to the outside.

In this case, according to the above configuration, the cooling air passage 82 inside the housing 2 is formed between the heat radiation panel 51 of the heat sink 50 and the cover portion 81 of the second circuit board 13, and moreover, the heat sink. Since it is partitioned from the inside of the casing 2 by the side wall 75 of 50, the extension wall portion 78, and the connector panel 21, the cooling air passage 82 itself has a flat tunnel shape. Therefore, most of the cooling air passage 82 is partitioned from the inside of the housing 2 except for the cooling air inlet 83, and the cooling air passage 82 is widely opened inside the housing 2. You don't have to.

Therefore, the electric fan 65 mainly sucks the warm air around the heat dissipation panel 51 in a concentrated manner without sucking the excess air in the portion away from the heat sink 50. The air volume and flow velocity of the cooling air flowing through the cooling air passage 82 increases. Further, since the heat dissipation projections 53 of the heat dissipation panel 51 are exposed to the flow of cooling air, the heat dissipation area of the heat dissipation panel 51 is increased as described above, and the heat dissipation performance of the heat dissipation panel 51 is improved. The heat of the IC chip 28 transmitted to the heat dissipation panel 51 can be efficiently released by multiplying it by the flow of the cooling air.

Further, according to the above configuration, the heat dissipation panel 5
Because the warm air around 1 can be concentrated and sucked in,
It is not necessary to increase the rotation speed of the electric fan 65 or use a large fan with a large air volume. As a result, the operating noise of the electric fan 65 can be reduced, noise can be reduced, and power saving can be achieved.

Further, the cover portion 81, which constitutes the cooling air passage 82 in cooperation with the heat dissipation panel 51, has the second circuit board 1
Since it is a part of No. 3, special parts for forming the cooling air passage 82 are unnecessary. Therefore, the cooling air passage 82 can be formed inside the housing 2 without increasing the number of components, and the internal structure of the housing 2 can be prevented from becoming complicated.

Further, in the present embodiment, since the electric fan 65 is directly supported by the heat radiation panel 51, the portion between the electric fan 65 and the heat radiation panel 51 that disturbs or disturbs the flow of the cooling air. Therefore, the positional relationship between the electric fan 65 and the heat radiation panel 51 can be optimally maintained. Therefore, the air permeability of the cooling air passage 82 is improved, and the warm air around the heat dissipation panel 51 can be efficiently exhausted.

At the same time, since a gap 85 is formed between the heat dissipation protrusion 53 of the heat dissipation panel 51 and the cover portion 81 of the second circuit board 13, the heat of the heat dissipation protrusion 53 is directly applied to the cover portion 81. It can be prevented from being transmitted, and the cooling air flowing through the gap 85 functions as a heat insulating layer. Therefore, a part of the second circuit board 13 is utilized to make the cooling air passage 8
Despite the construction of No. 2, the thermal influence on the second circuit board 13 is reduced.

In addition, since the circuit element 18 and the wiring pattern 19 on the second circuit board 13 are arranged at positions excluding the cover portion 81, thermal influence on the circuit element 18 and the wiring pattern 19 is prevented. It can be suppressed as low as possible, and the deterioration of the function of the circuit element 18 can be prevented.

The present invention is not limited to the first embodiment described above, and FIG. 9 shows a second embodiment of the present invention. In the second embodiment, the configuration mainly for suppressing the thermal influence on the second circuit board 13 is the above first embodiment.
The third embodiment is different from the first embodiment, and the other structure is the same as that of the first embodiment. Therefore, in the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 9, the cover portion 81 of the second circuit board 13 has a flat lower surface 81 facing the cooling air passage 82.
It has a and an upper surface 81b exposed to the upper side of the housing 2. A sheet material 91 for shielding heat is attached to the lower surface 81a. As the sheet material 91, for example, glass wool or a ceramic material is used.

On the upper surface 81b of the cover portion 81, L
Various circuit elements 92 such as an SI package are mounted. With such a configuration, the presence of the sheet material 91 makes it difficult for the heat of the heat sink 50 to be transferred to the cover portion 81. Therefore, the upper surface 81b of the cover 81 can be used as a mounting area of the circuit element 91, and
The numerous circuit elements 18, 91 of the circuit board 13 can be arranged without difficulty.

FIG. 10 discloses a third embodiment of the present invention. The third embodiment is a further development of the first embodiment, and its main configuration is as follows.
This is the same as in the first embodiment.

As shown in FIG. 10, the second circuit board 13
Among the circuit elements 18 mounted on the back surface 13b of the above, the circuit element 18a having a large downward protruding height H is arranged immediately before the cooling air inlet 83. As the circuit element 18a, one having excellent heat resistance is used, and the opening area of the cooling air inlet 83 is narrowed by the presence of the circuit element 18a.

According to such a configuration, the circuit element 18a
Since the opening area of the cooling air inlet 83 is narrowed by this, the circuit element 18a functions as a kind of orifice, and when the electric fan 65 is driven, the flow velocity of the cooling air flowing from the cooling air inlet 83 into the cooling air passage 82 is high. Become.

As a result, the warm air around the heat dissipation panel 51 can be discharged more efficiently, and the heat dissipation performance of the heat sink 50 is improved. In the above-described embodiment, TCP is taken as an example of a circuit element that generates heat, but this circuit element is not limited to TCP and may be another LSI package. Further, the portable device according to the present invention is not limited to the portable computer, but can be similarly applied to other devices such as a text writing device.

[0079]

According to the first, the seventh and the eighth aspects of the invention, the electric fan intensively sucks the warm air around the heat sink without sucking the excess air in the portion distant from the heat sink. The heat dissipation performance of the heat sink is improved, and the heat of the circuit element transferred to the heat sink can be efficiently exhausted to the outside of the housing by being multiplied by the flow of the cooling air. Moreover, in this case, it is not necessary to increase the rotation speed of the electric fan or to use a large fan with a large air volume, which enables quiet operation,
Power saving can also be achieved. Further, since the cover portion that cooperates with the heat sink to form the cooling air passage is a part of the second circuit board, no special component is required to form the cooling air passage. For this reason, the cooling air passage can be formed inside the housing without increasing the number of parts, and the internal structure of the housing can be prevented from becoming complicated and the cost can be reduced.

Further, according to claim 7, the heat of the heat sink is less likely to be transmitted to the cover portion due to the presence of the sheet material, so that the cover portion can be utilized as a mounting area of the circuit element, and the second circuit board Many circuit elements can be mounted at high density.

Further, according to the eighth aspect, since the opening area of the cooling air inlet is narrowed by the projection, the flow velocity of the cooling air flowing from the cooling air inlet into the cooling air passage during the operation of the electric fan becomes faster. Therefore, there is an advantage that the warm air around the heat sink can be discharged more efficiently, and the heat dissipation performance of the heat sink is improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a portable computer showing a state in which a display unit is opened according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the portable computer with the display unit closed.

FIG. 3 is an exemplary cross-sectional view of the portable computer showing a mounting portion of the heat sink;

FIG. 4 is a perspective view showing a state in which a heat sink having an electric fan and a second circuit board are incorporated in a lower housing of a housing.

FIG. 5 is an exploded perspective view showing a positional relationship between a heat sink on a first circuit board and a second circuit board.

FIG. 6 is a perspective view showing a state where a heat sink having an electric fan is incorporated in the lower housing of the housing.

FIG. 7 is an exploded perspective view showing a positional relationship between a first circuit board and a heat sink.

FIG. 8 is an exploded perspective view showing a positional relationship between a first circuit board and a heat sink.

FIG. 9 is a sectional view of the portable computer showing a mounting portion of a heat sink in the second embodiment of the invention.

FIG. 10 is a cross-sectional view of a portable computer showing a mounting portion of a heat sink according to the third embodiment of the present invention.

[Explanation of symbols]

 2 ... Casing 12 ... 1st circuit board 13 ... 2nd circuit board 18a ... Protrusion (circuit element) 26 ... Circuit element (TCP) 50 ... Heat sink 65 ... Electric fan 81 ... Cover part 82 ... Cooling air passage 91 ... Sheet material

Claims (8)

[Claims] 1. A box-shaped casing; first and second circuit boards housed inside the casing and arranged in parallel at a distance from each other; mounted on the first circuit substrate A circuit element that generates heat during operation; a heat sink that is disposed in a mounting portion of the circuit element on the first circuit board and that radiates heat transferred from the circuit element; And an electric fan that sucks the air inside the housing and discharges the air to the outside of the housing through the heat sink. The second circuit board includes the heat sink. Integrally with a cover portion facing the heat sink, which cooperates with the heat sink to form a cooling air passage inside the housing.
A portable device characterized in that the cooling air passage is connected to the electric fan. 2. The heat sink according to claim 1, wherein the heat sink has a heat radiation panel facing the cover portion of the second circuit board, and a fan support portion connected to the heat radiation panel, and the fan support portion has the fan support portion. A portable device characterized in that an electric fan is supported. 3. The portable device according to claim 2, wherein the heat dissipation panel of the heat sink includes a large number of heat dissipation protrusions interposed in the cooling air passage. 4. The tip of the heat dissipation protrusion and the cover of the second circuit board are separated from each other according to claim 3, and a gap is provided between the tip of the heat dissipation protrusion and the cover. A portable device characterized by being formed with. 5. The heat dissipating panel according to claim 3, wherein the heat dissipating panel has a side wall that is located around the heat dissipating protrusion and extends toward the cover portion, and the side wall forms the cooling air passage in the housing. A portable device characterized by being partitioned from the inside of the fan and being connected to the fan support portion. 6. The second circuit board according to claim 1, wherein the second circuit board has a plurality of circuit elements and a wiring pattern for electrically connecting the circuit elements. A portable device characterized in that it is arranged at a position avoiding the cover portion. 7. A box-shaped housing; first and second circuit boards housed inside the housing and arranged in parallel at a distance from each other; mounted on the first circuit board A circuit element that generates heat during operation; a heat sink that is disposed in a mounting portion of the circuit element on the first circuit board and that radiates heat transferred from the circuit element; And an electric fan that sucks the air inside the housing and discharges the air to the outside of the housing through the heat sink. The second circuit board includes the heat sink. And a cover portion that integrally faces the cooling fan and that forms a cooling air passage communicating with the electric fan inside the housing in cooperation with the heat sink and that faces the cooling air passage of the cover portion. Is the heat Portable device characterized in that it is covered by the sheet material for shielding. 8. A box-shaped housing; a first circuit board housed inside the housing, on which a circuit element that generates heat during operation is mounted; A second circuit board disposed in parallel with the first circuit board and having a mounting surface facing the first circuit board;
A heat sink disposed in a mounting portion of the circuit element on the circuit board for discharging heat transferred from the circuit element; and a heat sink housed in the housing and sucking air in the housing, An electric fan that discharges this air to the outside of the housing through the heat sink; and the second circuit board integrally has a cover portion that faces the heat sink. In cooperation with the heat sink, a cooling air passage communicating with the electric fan is formed inside the housing, and the cooling air passage has a cooling air inlet located on the side opposite to the electric fan. On the mounting surface of the second circuit board adjacent to the cooling air inlet, there is arranged a protrusion protruding toward the first circuit board to reduce the opening area of the cooling air inlet. Portable device.