JP2007250725A - Portable terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable terminal in which sensible temperature of the housing can be reduced while suppressing temperature distribution on the surface thereof. <P>SOLUTION: The portable terminal has a housing containing electronic components. The housing comprises a plate 22 composed of a first material, and coating layers 21 and 23 composed of a second material having a thermal conductivity lower than that of the first material and covering the inner and outer surfaces of the plate 22. The first material is a metal and the second material is resin. The housing is formed by insertion molding. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mobile terminal device, and more particularly to a technique for suppressing temperature distribution on the surface of a housing.

  2. Description of the Related Art In recent years, the amount of heat generated inside a mobile terminal device such as a mobile phone has increased as the functionality and performance have increased. On the other hand, the size of the mobile terminal device tends to be reduced, and the internal electronic component and the housing are often arranged in close proximity. In such a case, a large amount of heat generated in the electronic component is transmitted to the housing, so that the surface of the housing locally becomes hot, and there is a problem in that the user who uses the device feels uncomfortable.

  In order to suppress the user's discomfort, for example, there is a method of monitoring the temperature inside the apparatus using a thermistor and reducing the supply current when the temperature exceeds a set temperature. However, if the supply current is reduced, the function of the mobile terminal device is reduced by that amount, which may cause inconvenience to the user during use.

With respect to the above problem, Patent Document 1 proposes to dispose a metal thin film having high thermal conductivity on the front surface and the back surface of the casing of the mobile terminal device.
JP2003-060369A (FIG. 2)

  According to the portable terminal device of Patent Document 1, heat dissipation is efficiently performed by a metal thin film, and the temperature distribution on the housing surface can be suppressed. However, since the metal thin film is exposed on the surface of the casing in the portable terminal device of the same document, a new problem arises that the temperature of the body surface is increased.

  That is, since the specific heat of the metal is smaller than that of the resin, the metal is likely to have a higher temperature than the resin even if it absorbs the same amount of heat. Moreover, since heat conductivity is large compared with resin, heat | fever flows easily with respect to a contact thing. Therefore, in the portable terminal device disclosed in this document in which the metal sheet is exposed on the surface of the housing, the temperature distribution on the surface of the housing is suppressed, but it feels hotter when touched with a finger or the like.

  In order to reduce the discomfort given to the user when using the mobile terminal device, it is essential to reduce the temperature at which the user feels when touching the casing of the mobile terminal device. In view of the above, an object of the present invention is to provide a portable terminal device that can suppress the temperature distribution on the surface of the housing and reduce the temperature of the housing.

In order to achieve the above object, a mobile terminal device according to the present invention is a mobile terminal device including a housing that houses an electronic component therein.
The housing is composed of a plate material made of a first material and a coating layer made of a second material having a lower thermal conductivity than the first material and covering the inner and outer surfaces of the plate material. It is characterized by that.

  According to the portable terminal device of the present invention, the heat that reaches the housing from the electronic component is efficiently diffused by the plate material in the in-plane direction of the plate material, and thereby the temperature distribution on the surface of the housing becomes uniform. Moreover, since the surface layer of the housing is composed of a coating layer having a lower thermal conductivity than the plate material, it is possible to reduce the sensible temperature when touching the housing.

  In addition, even if the electronic component and the housing are arranged close to each other and the plate material is made of an electrically conductive material, a coating layer is formed on the inner side of the plate material. A short circuit can be prevented. In addition, since the coating layer having a lower thermal conductivity than the plate material is interposed between the electronic component and the plate material, it is possible to suppress the heat generated in the electronic component from being directly transmitted to the plate material having good heat absorption. Therefore, the temperature rise of the housing surface can be suppressed, and the body temperature of the housing can be further reduced.

  In a preferred aspect of the present invention, the first material is a metal, and the second material is a resin. Since the metal has a high thermal conductivity and the resin has a low thermal conductivity, the temperature of the casing can be effectively reduced while effectively suppressing the temperature distribution on the casing surface.

  In a preferred aspect of the present invention, the first material is graphite and the second material is a resin. Since graphite has high thermal conductivity and resin has low thermal conductivity, the temperature of the casing can be effectively reduced while effectively suppressing the temperature distribution on the casing surface. Moreover, since the electrical conductivity of graphite is low, it is possible to suppress a decrease in electrical performance of the antenna of the mobile terminal device.

  In a preferred aspect of the present invention, the first material has a thermal conductivity of 50 W / m · K or more. In this case, the heat reaching the housing from the electronic component can be efficiently diffused in the plane of the plate material by the plate material.

  In a preferred aspect of the present invention, the casing is formed by insert molding. By being formed by insert molding, a housing having the same appearance as a resin molded product formed by resin injection into a mold can be manufactured at low cost. In the case formed by insert molding, the plate member and the covering layer are physically fixed, and therefore, they can be easily separated from each other during recycling or the like.

  Hereinafter, the present invention will be described in more detail based on embodiments of the present invention with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a mobile terminal device according to an embodiment of the present invention. The mobile terminal device 10 is configured as, for example, a mobile phone, and includes a wiring board 11, various electronic components 12 mounted on the wiring board 11, and a housing 13 that houses the wiring board 11 and the electronic components 12. The electronic component 12 is an electronic component that generates a large amount of heat, and is, for example, a power amplifier (PA), a charging IC (Integrated Circuit), a charging FET (Field Effect Transistor), or the like.

  FIG. 2 is an enlarged cross-sectional view of the broken line portion 14 of FIG. The housing 13 includes a first coating layer 21, a plate material 22, and a second coating layer 23 that are sequentially stacked from the inside of the mobile terminal device 10. In the present embodiment, the plate material 22 is made of, for example, a copper plate, and the covering layers 21 and 23 are made of, for example, resin. The thermal conductivity of copper is, for example, 385 W / m · K. The thermal conductivity of the coating layers 21 and 23 is, for example, less than 1.0 W / m · K. The resin constituting the covering layers 21 and 23 is, for example, an ABS resin or a polycarbonate resin.

  In forming the housing 13, for example, it is possible to use insert molding in which a copper plate constituting the plate material 22 is loaded in a mold and then a resin material constituting the coating layers 21 and 23 is injected. By adopting insert molding, the housing 13 having the same appearance as a resin molded product formed by resin injection into a mold can be manufactured at low cost. In the housing 13 formed by insert molding, the fixing between the plate member 22 and the coating layers 21 and 23 is a physical fixing, and is not a chemical or electrical fixing like painting or resin coating. Therefore, there is an advantage that peeling between each other is easy and suitable for recycling.

  The heat generated in the electronic component 12 reaches the housing 13 via the air inside the mobile terminal device 10 or the like. The heat that has reached the housing 13 is efficiently dissipated by the plate material 22 in the in-plane direction of the plate material 22, whereby the temperature distribution on the surface of the housing 13 becomes uniform. On the other hand, since the surface layer of the housing 13 is composed of the second coating layer 23 having a specific heat larger than that of the plate material 22 and having a small thermal conductivity, the sensory temperature when the housing 13 is touched is set. Can be reduced.

  Even if the electronic component 12 and the housing 13 are arranged close to each other, the first coating layer 21 is formed inside the plate material 22, so that the electronic component 12, the plate material 22 having electrical conductivity, A short circuit can be prevented. Furthermore, the first coating layer 21 is interposed between the electronic component 12 and the plate material 22, whereby the heat generated in the electronic component 12 can be suppressed from being directly transmitted to the plate material 22 with good heat absorption. Therefore, the temperature rise of the surface of the housing 13 can be suppressed, and the sensible temperature of the housing 13 can be further reduced.

  The mobile terminal device 10 of the above-described embodiment was actually manufactured and used as the mobile terminal device of the example. Moreover, in the portable terminal device 10 of the said embodiment, the portable terminal device which comprised the housing | casing 13 only with the resin layer was manufactured, and it was set as the portable terminal device of the comparative example. About the portable terminal device of an Example and a comparative example, the temperature distribution of the housing | casing surface was measured. The results are shown in FIGS. 3 (a) and 3 (b), respectively.

  In the portable terminal device of the example, the temperature of the surface of the housing 13 is uniformly about 28 ° C., and almost no temperature distribution is seen. On the other hand, in the portable terminal device of the comparative example, the temperature of the surface of the housing 13 is about 31 ° C. at the center of the portable terminal device 10 in which the electronic component 12 having a large heat generation amount is disposed, whereas the peripheral portion The temperature is about 25 ° C., and a large temperature distribution is generated between the central portion and the peripheral portion. Thereby, it was confirmed that the temperature distribution can be effectively suppressed in the mobile terminal device 10 of the present embodiment.

  In the mobile terminal device according to the modified example of the above-described embodiment, in the mobile terminal device 10 shown in FIGS. 1 and 2, the plate material 22 is made of a graphite sheet. The thermal conductivity of the graphite sheet is about 200 W / m · K. In the mobile terminal device, when a metal having high conductivity is used for the housing 13, the electrical performance of the antenna or the like may be deteriorated. In this modification, by using a graphite sheet having low conductivity and high thermal conductivity for the plate member 22, it is possible to suppress the temperature distribution while suppressing a decrease in electrical performance of the mobile terminal device.

  The material of the plate 22 is not limited to the copper plate shown in the embodiment or the graphite sheet shown in the modification, and the temperature distribution can be obtained by using a material having a thermal conductivity of 50 W / m · K or more. It can be effectively suppressed. For example, the rigidity of the housing 13 can be increased by using a material having high rigidity.

  When the housing 13 is formed by insert molding, a part of the plate material 22 may come into contact with the mold, and the contacted portion may be exposed on the surface of the housing 13. However, if the portion close to the electronic component 12 that generates a large amount of heat is covered with the first coating layer 21 and the portion that comes into contact with the user's fingers is covered with the second coating layer 23, the effects of the above-described embodiment can be obtained. Can be obtained.

  As mentioned above, although this invention was demonstrated based on the suitable embodiment, the portable terminal device which concerns on this invention is not limited only to the structure of the said embodiment, A various correction | amendment and various from the structure of the said embodiment. The mobile terminal device that has been changed is also included in the scope of the present invention.

It is sectional drawing which shows the structure of the portable terminal device which concerns on one Embodiment of this invention. It is sectional drawing which expands and shows the broken-line part of FIG. FIG. 3A is a diagram illustrating the temperature distribution on the surface of the casing for the portable terminal device of the example, and FIG. 3B is the temperature distribution on the surface of the casing for the portable terminal device of the comparative example. FIG.

Explanation of symbols

10: mobile terminal device 11: wiring board 12: electronic component 13: housing 14: broken line portion 21: first covering layer 22: plate material 23: second covering layer

Claims (5)

In a mobile terminal device having a housing containing electronic components therein,
The housing is composed of a plate material made of a first material and a coating layer made of a second material having a lower thermal conductivity than the first material and covering the inner and outer surfaces of the plate material. A portable terminal device.   The portable terminal device according to claim 1, wherein the first material is a metal and the second material is a resin.   The portable terminal device according to claim 1, wherein the first material is graphite and the second material is resin.   The portable terminal device according to claim 1, wherein the first material has a thermal conductivity of 50 W / m · K or more.   The portable terminal device according to claim 1, wherein the casing is formed by insert molding.

Images