JPH10333782A - Heat radiating device for electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a heat radiating device in which a case surface can be turned into high temperature in a relatively simple method while any danger on a human body or a setting place can be prevented, and the case can be obtained in a sealed form, and heat can be transmitted to the case and the heat can be cooled by natural convection and radiation. SOLUTION: At least one part of the case of an electronic equipment is composed of a metallic board 1, and a resin board 2 is provided so that the outside of the metallic board 1 can be covered. One sides of the metallic board 1 and the resin board 2 are connected so as to be opened and closed by a hinge 4, and the other side of the resin board 2 is pushed down by a restraining safety lug mechanism 5 while being linked with the opening motion of an outer cover 6 at the time of using the electronic equipment so that natural convection can be generated in a clearance between the metallic board 1 and the resin board 2, and the heating of the circuit part of the electronic equipment can be radiated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiating device for an electronic device, and more particularly to a heat radiating device comprising a metal plate for radiating the temperature of an electronic device such as a portable terminal device and a resin plate configured to cover the metal plate. Related to the device.

[0002]

2. Description of the Related Art The trend of miniaturization of electronic equipment in recent years has been remarkable. This can be realized in particular by high integration of active elements such as ICs and LSIs, downsizing of general electronic components, and progress of high-density mounting technology. But,
With such a high degree of integration, the reduction in heat generation of elements and components cannot keep up with the speed of miniaturization, and as a result, the heat density increases and the inside of electronic devices tends to become even hotter.
Moreover, heat-sensitive components are frequently used in electronic devices. Therefore, it is necessary to efficiently dissipate the generated heat to the outside and to reduce the ambient temperature of the component to a safe temperature or lower.

[0003] When the housing of an electronic device is considered from the viewpoint of cooling, it is divided into a closed housing and an open housing. Since the closed casing has no opening for ventilation, heat is radiated exclusively from the surface of the casing, but is advantageous against intrusion of foreign matter such as dust and moisture. In a closed housing, the final heat radiating part is the surface of the housing. If the thermal resistance inside the device is made sufficiently small, the thermal resistance on the housing surface becomes the dominant term of the overall thermal resistance.

There are several formulas showing the heat radiation characteristic from the housing surface, and the following formula is often used. P (W) = 1.86 (4 / 3St + Ss + 2 / 3Sb) .DELTA.t1.25 + 4.sigma.Tm3S.DELTA.t1) where P (W) is the amount of heat dissipation, .DELTA.t is the temperature rise from the ambient temperature of the housing surface, and S is The surface area of the housing effective for heat dissipation, t,
s and b are suffixes indicating the top, side, and bottom surfaces of the housing, respectively, and σ is a step fan-Boltzmann constant, where σ
= 5.67 × 10 −8 (W / m 2 · / K 4), ε is the average thermal emissivity of the housing surface, Tm is the average temperature of the housing surface, and S = S
It is assumed that t + Ss + Sb.

[0005] The result of the calculation according to the equation 1) is obtained for a small housing or when the air inside the housing is well stirred and Δt
Is almost constant with respect to the entire casing surface, it is in good agreement with the actually measured value.

FIG. 7 shows a comparison between a measured value of the temperature rise of the closed casing and a calculated value based on the equation 1) in consideration of the emissivity. Here, FIG. 7A shows the case where the average thermal emissivity ε = 0.9, and FIG. 7B shows the case where the average thermal emissivity ε = 0.2.

FIG. 8 is a table showing thermal specifications of components of a notebook personal computer as an example of an electronic device and what kind of problems the components cause due to heat. Main heat sources in a notebook computer are a CPU chip and other ICs, a resistor, a power supply coil, a battery for charging, and the like. The largest heat source is the CPU chip and the surface temperature of the module is 1
It is about 20 ° C.

On the other hand, as parts that dislike heat, each part has each temperature specification as shown in FIG. 8, and it is desired to keep the specification. For example,
The temperature of the CPU is desirably about 100 ° C. Similarly, VG
An IC such as A (color image display IC) may run away at 100 ° C. or higher.

Also, an HDD (hard disk drive)
When the ambient temperature exceeds 55 ° C., problems such as a decrease in head clearance occur, and in an FDD (floppy disk drive), deformation of the medium may become a problem at high temperatures. Furthermore, PC card and C
In the vicinity of a D-ROM or the like, a malfunction may occur due to heat.

Conventionally, as a heat radiating device in a portable electronic device, for example, a portable terminal device or a portable notebook personal computer, 1) a method of cooling by performing forced convection using an air-cooling fan 2) externally Two methods have been used, in which the heat of the heat generating portion is transmitted to the housing, and the heat is transmitted to the external air by heat conduction and radiation to cool the case.

However, the method 1) using an air-cooling fan requires a large space for installing the air-cooling fan, and also uses electric power. Therefore, when a battery is used as a power supply, the life of the battery is shortened. Air cooling fan rotation noise,
There was a problem that wind noise was generated. In addition, in this case, the housing often has an open type that forcibly takes in air inside the device, so that dust enters the device and it is unprotected against the invasion of moisture, which is a cause of failure. There was also the problem of becoming.

On the other hand, in the method of 2) mainly used for a closed casing for transferring heat to the outer casing, if the outer casing is made of metal, there is a danger that the user will be burned if the temperature becomes too high. In addition, there is also a concern that the desk and the like may be damaged, and the temperature cannot be raised so much, so that the heat radiation effect is limited.

In the case of using a resin-made casing that is not a metal, even in this case, if the temperature is raised, there is a problem that the user is uncomfortable or the resin is deteriorated. However, since the resin has poor thermal conductivity and thermal emissivity, there is a problem that the heat radiation effect is small.

The heat radiation effect depends on the temperature difference Δt between the ambient air and the surface of the housing, as is apparent from the equation (1). Therefore, it is originally preferable to raise the temperature even slightly. However, there is a problem that the heat release is not sufficient because of the above reasons, and from this point too, heat radiation is not sufficient.

[0015]

As described above, in the case of a conventional heat radiating device such as a portable terminal device or a personal computer, when a fan is used, the size of the device becomes large, dust easily enters the device, and battery power is consumed. There is a problem that is large. Also, if the case is made of metal and the temperature is conducted and cooled there, there is a risk of causing burns or discomfort to the user, so the temperature can not be raised much, There is a problem that the heat radiation effect is not sufficient.

The present invention solves this problem by using a relatively simple method to raise the temperature of the housing surface to increase the temperature difference from the outside air, and without danger to the human body or the installation place. It is an object of the present invention to realize a heat radiating device that adopts a method of conducting heat to a housing and cooling the heat by natural convection and heat radiation, which can be a sealed type.

[0017]

According to the present invention, a part of a housing of an electronic device is formed of a metal plate, and heat generated by circuit components of the electronic device is transmitted to the metal plate. In a heat dissipation device of an electronic device that dissipates heat, a resin plate provided so as to cover the outside of the metal plate, and an inter-plate opening unit that functions to leave a space between the metal plate and the resin plate when the electronic device is used. It is characterized by having.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a heat radiating device according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a transparent perspective view showing the gist of one embodiment of the present invention. In FIG. 1, 1 is a metal plate (here, an aluminum plate), 2 is ABS.
The resin plate 3, electronic components inside the electronic device, 4 is a hinge connecting the metal plate 1 and the ABS resin plate 2, 5 is a mechanical component for pushing and expanding the hinge 4 (an engaging claw mechanism), and 6 is a lid of the main body. is there. The ABS resin plate 2 serves as a cover for covering the metal plate 1 when the electronic device is not used.

The operation of the radiator will be described with reference to FIG. The electronic component 3 inside the electronic device is provided so as to be in contact with the metal plate 1, and is designed to conduct heat generated by the electronic component 3 to the metal plate 1 and radiate the heat. In FIG. 1, the electronic component 3 is shown as one block as a representative. However, it is a matter of course that the electronic component 3 may be a substrate on which a plurality of elements are arranged. It is assumed that it is adhered to the plate 1 or attached so as to be in contact with it.

In the use state in which the lid 6 of the electronic apparatus main body is opened and upright, the mechanical component 5 rotates with the movement of raising the lid 6 of the main body, and the rotation of the mechanical component 5 causes the metal plate 1 and the ABS resin plate to rotate. 2 is pushed open about the hinge 4 so that the ABS resin plate 2 is located below. When the electronic device is placed on a horizontal surface in this state, the metal plate 1 is placed in a state inclined with respect to the horizontal surface.

FIG. 2A shows an external perspective view of the electronic device when it is not used, and FIG. 2B shows an external perspective view of the electronic device when it is used. As is clear from FIGS. 2A and 2B, the electronic device has a rectangular parallelepiped shape when not in use, but the metal plate 1 and the ABS resin plate when used with the main body lid 6 standing. A gap space 7 is formed between the two.

FIGS. 3 to 5 show that a clearance space 7 is formed between the metal plate 1 and the ABS resin plate 2 as the lid 6 of the device body is opened for the purpose of using the electronic device. It is explanatory drawing explaining a process. First, in the closed state of FIG. 3, there is no contact between the mechanical component 5 attached to the lid 6 of the main body and the ABS resin plate 2, and the metal plate 1 and the ABS resin plate 2
Are in close contact with each other.

Next, as shown in FIG. 4, when the lid 6 of the main body is opened little by little, the mechanical component 5 pushes the projection 8 on the ABS resin plate 2 and gradually removes the ABS resin plate 2 from the metal plate 1. Go away. Finally, as shown in FIG. 5, when the cover 6 of the main body is completely opened, the metal plate 1 is in the horizontal position A
The angle θ is shown with respect to the BS resin plate 2, and the gap space 7 is opened.

Conversely, when the cover 6 of the main body is closed, the reverse operation proceeds from the state shown in FIG. 5, and when the mechanical component 5 moves away from the ABS resin plate 2, the gap space is formed by the weight of the electronic device main body. 7 automatically closes, and a closed state as shown in FIG. 3 ends.

FIG. 6 shows the flow of air in use when the cover 6 of the main body is opened as shown in FIG.
As shown by arrows in FIG. 6, external air enters the gap 7 between the metal plate 1 and the ABS resin plate 2 from both sides of the electronic device and is warmed by the metal plate 1 and has a low specific gravity. As a result, it rises along the metal plate 1 and performs natural convection exhausted from behind the electronic device. In this way, the natural convection of the air is promoted, so that heat is efficiently radiated from the surface of the metal plate 1.

When the metal plate 1 is radiated to the bottom surface of the housing as described above, the temperature of the metal plate 1 becomes high. However, since the ABS resin plate 2 covering the metal plate 1 is further provided,
The metal plate 1 does not directly touch the desk and does not directly touch the user's hand, so that heat or damage to the person or the desk does not occur. Since the heat damage is prevented as described above, the metal plate 1 can be heated to 70 ° C., and even when the metal plate 1 reaches 70 ° C., the temperature outside the ABS resin plate 2 is maintained. It was found that when the outside air temperature was 25 ° C, the temperature was raised only to 35 ° C.

At this time, the temperature rise inside the electronic device was about 50 ° C. when the air gap angle θ was about 5 °. This is the internal temperature for a closed enclosure, about 80
This means that the temperature can be lowered by about 30 ° C. as compared with the temperature of ° C.

Since a sufficient cooling effect can be obtained when the gap angle θ constituting the gap space 7 is about 5 °, for example, in a notebook computer, the inclination of the keyboard portion can be used as it is for the gap space 7 for heat radiation. This eliminates the need for special consideration in the device configuration.

In the above description, the bottom surface of the housing has been described as the metal plate 1 for radiating heat from this portion. However, the side surface and part of the surface of the housing are formed of a metal plate. It is also possible to create a small space between the resin plate and the metal plate as a cover at the time of use in the portion, to cause convection in this space to radiate heat and further enhance the heat radiation effect.

As described above, in the present invention,
The bottom surface of the housing is made of a metal plate 1, and this metal plate 1
Is maintained at a constant angle with respect to the horizontal plane, the clearance space 7 is formed at this angle, and by using this metal plate 1 as a heat sink, natural convection heat radiation is effectively performed and the temperature inside the device is reduced. It became possible to lower it.

Moreover, since the outer side of the metal plate 1 is covered by the ABS resin plate 2, even if the metal plate 1 becomes hot, the user will not be burned or damage a desk or the like. In addition, since the metal plate 1 takes an angle of about 5 ° with respect to the horizontal plane during this use and has a sufficient cooling effect, this inclination can be used as the inclination of the keyboard surface, and no special consideration is required in the device configuration. May be.

Further, according to such a method, it is not necessary to provide a cooling fan, and the housing can be made a closed type.
The battery life can be kept long without consuming power supply power, and the problem of failure caused by dust and moisture entering the electronic device is reduced.

[0033]

As described above, according to the present invention, at least a part of the housing of an electronic device is formed of a metal plate, and heat generated from circuit components of the electronic device is conducted to the metal plate to radiate heat. A resin plate is provided outside the metal plate so as to cover the metal plate, and when the electronic device is used, a gap is automatically provided between the metal plate and the resin plate by opening and closing the lid. Thereby, a cooling method using natural convection and thermal radiation can be used, and a heat radiating device that does not damage a human body or a desk even when the metal plate is heated can be realized. Furthermore, since the housing can be sealed, there is little problem of failure due to dust or moisture, and since no fan is used, there is no problem of battery power consumption and noise, and the device can be downsized. be able to.

[Brief description of the drawings]

FIG. 1 is a transparent perspective view showing a gist of an embodiment of a heat radiator of the present invention.

FIG. 2 is an external perspective view of the electronic device using the heat radiating device shown in FIG. 1 when it is not used and when it is used.

FIG. 3 is a view showing the formation of a gap space with the opening of a lid of an electronic device using the heat radiating device shown in FIG. 1;

FIG. 4 is a view showing the formation of a gap space with the opening of a lid of an electronic device using the heat radiating device shown in FIG. 1;

FIG. 5 is a view showing the formation of a gap space with the opening of a lid of an electronic device using the heat radiating device shown in FIG. 1;

FIG. 6 is an explanatory diagram showing the flow of air when the electronic apparatus using the heat radiating device shown in FIG. 1 is used with a lid opened.

FIG. 7 is an explanatory diagram showing a comparison between a measured value and a calculated value of a temperature rise in the closed casing.

FIG. 8 is a table showing thermal specifications of a notebook personal computer and contents of a problem caused by heat.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal plate, 2 ... ABS resin plate, 3 ... Electronic components inside electronic equipment, 4 ... Hinge, 5 ... Mechanical components, 6 ... Lid of body, 7
... gap space, 8 ... projections.

Claims (4)

[Claims] 1. A heat radiating device for an electronic device, wherein at least a part of a housing of the electronic device is formed of a metal plate, and heat generated by a circuit component of the electronic device is conducted to the metal plate to radiate heat. A resin plate provided so as to cover the metal plate, and inter-plate opening means functioning to leave a space between the metal plate and the resin plate when the electronic device is used. 2. The inter-plate opening / closing means having a function of closing a space between the metal plate and the resin plate when the electronic device is not used. Electronic equipment heat dissipation device. 3. The metal plate forms a bottom surface of the housing. The inter-plate opening means includes hinge means for opening and closing one side of the metal plate and the resin plate. 2. A claw mechanism provided on the outer lid and engaging a pawl mechanism for pushing down the other side of the resin plate opposite to the one side in conjunction with the movement of opening the outer lid. A heat dissipation device for an electronic device according to claim 2. 4. The heat radiation of an electronic device according to claim 1, wherein the casing is a closed casing except for the outer lid and the resin plate. apparatus.