JP3753875B2 - Electronics - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic device in which an electronic device body having a heat generating electronic component such as a transformer, a transistor, and a diode is housed in a casing, and more particularly to an electronic device particularly suitable for a power supply device such as an AC adapter.
[0002]
[Prior art]
As this type of electronic apparatus, an AC adapter 31 shown in FIG. 4 is conventionally known. As shown in FIG. 5, the AC adapter 31 is formed by bending a commercial AC supplied via a power cable (not shown) into a predetermined DC voltage, and bending a copper plate into a rectangular tube shape. A heat radiating plate 13 disposed so as to enclose the DC power source 2 and resin casings 33a and 33b for housing the DC power source 2 encased by the heat radiating plate 13 are provided. In this case, the DC power source 2 includes a connector 11 for connecting a power cable, a voltage converting transformer, a switching transistor, a rectifying diode, and the like (not shown) and a DC voltage output cable. The printed circuit board 10 to which one end of 12 is soldered is provided. The heat radiating plate 13 radiates heat generated by the DC power source 2 to the casings 33a and 33b and magnetically shields the DC power source 2.
[0003]
On the other hand, the casings 33a, 33b are formed so as to be fitted to each other, and a plurality of ribs 34, 34,... For holding the DC power source 2 encased by the heat radiating plate 13 are formed on the inner walls thereof. (The figure shows only three ribs 34, 34, 34 formed on the inner wall of the casing body 33b). With this configuration, in the AC adapter 31, as a result of the heat sink 13 being held by the ribs 34, 34,..., The internal space S between the heat sink 13 and the casings 33a and 33b as shown in FIG. Is formed.
[0004]
In the AC adapter 31, electronic components such as a transformer and a transistor generate heat when converting commercial AC to DC voltage. For this reason, in order to prevent the performance degradation and thermal destruction of the electronic components due to heat generation, it is necessary to radiate the heat at that time from the surfaces of the casings 33a and 33b to the outside air. On the other hand, if the heat from the electronic components is directly conducted to the casings 33a and 33b at this time, only the surface portions of the directly conducted casings 33a and 33b are remarkably increased in temperature than the other surface portions. In this case, there is a request that the temperature rise of the surfaces of the casings 33a and 33b with respect to the outside air temperature should be suppressed to 30 ° or less due to domestic regulations. For this reason, in this AC adapter 31, the heat from the electronic components is diffused in the internal space S and the surface temperature of the casings 33a and 33b is averaged by averaging the surface temperatures of the casings 33a and 33b. Trying to prevent the temperature rise.
[0005]
Specifically, for example, when a transformer of the DC power source 2 generates heat, a predetermined portion of the heat radiating plate 13 surrounded by a broken line P shown in FIG. 5 is heated by the heat. In this case, since the heat radiating plate 13 is formed of a copper plate having good thermal conductivity, the heat of the heated portion diffuses to the portion surrounded by the broken line P11 shown in FIG. Heat is dissipated in the space S. On the other hand, the heat radiated to the internal space S is conducted to the inner walls of the casings 33a and 33b while being diffused to a wider area along the inner walls of the casings 33a and 33b using the air in the internal space S as a medium. Therefore, for example, on the casing 33a side, a wide area surrounded by a broken line P12 shown in the figure is heated. Further, the heat of the heated portion is radiated from the surfaces of the casings 33a and 33b to the outside air. As a result, by averaging the surface temperatures of the casings 33a and 33b, a local extreme temperature rise on the surfaces of the casings 33a and 33b can be prevented.
[0006]
[Problems to be solved by the invention]
However, the conventional AC adapter 31 has the following problems.
That is, in the conventional AC adapter 31, the heat of the power supply circuit 2 is diffused and dissipated to the part surrounded by the broken line P <b> 12 shown in FIG. 5, and the surface temperature of the casings 33 a and 33 b is averaged. Trying to prevent extreme temperature rise. However, it cannot be said that the area of the surface portion surrounded by the broken line P12 is sufficiently large with respect to the entire surface area of the casings 33a and 33b. For this reason, the surface portion surrounded by the broken line Q11 in the figure, which is the surface of the casing 33a located above the heat generating electronic component, rises by, for example, about 40 ° from the outside air temperature, but is separated from the surface portion. The surface portion surrounded by the broken line Q12 located at a position is a temperature rise of about 25 ° from the outside air temperature, and there is a problem that the effect of preventing the local temperature rise of the surface temperature of the casings 33a and 33b is still low. This problem can be attributed to the following factors.
[0007]
As a first factor, it is conceivable that the thermal conductivity of the casings 33a and 33b is low. That is, in this AC adapter 31, the heat of the heat radiating plate 13 is radiated from the surface thereof toward the casing 33a through the internal space S, so that the heat is conducted to the inner wall of the casing 33a. However, since the heat conductivity of the general-purpose resin material used for the casing 33a is low, most of the heat conducted to the inner wall is not diffused in the casing 33a but is conducted to the surface side. Therefore, when the heat diffusion by the heat radiating plate 13 and the internal space S is insufficient, it is considered that only the local surface of the casing 33a rises significantly in temperature than the other surface portions.
[0008]
In this case, for example, the surface temperature of the casings 33a and 33b can be lowered as a whole by adhering a non-heat-transfer cushioning material to the inner walls of the casings 33a and 33b. However, in such a case, the heat dissipation performance of the AC adapter 31 is significantly reduced and heat is trapped inside the casings 33a and 33b. As a result, it is necessary to use highly heat-resistant electronic components. Another problem arises that increases the manufacturing cost.
[0009]
As a second factor, it is considered that heat diffusion by the heat radiating plate 13 is insufficient. That is, in this AC adapter 31, before the heat in the broken line P of the heat radiating plate 13 is diffused to a wide range through the heat radiating plate 13, it is radiated directly to the inner wall of the casing 33a. Only a part of the surface of the casing 33a is considered to increase in temperature significantly than the other surfaces.
[0010]
Third, the influence of the ribs 34 can be considered. In other words, in the AC adapter 31, the heat of the heat radiating plate 13 is directly conducted to the casings 33a and 33b through the plurality of ribs 34, 34,. Therefore, it is considered that the temperature of the standing portions of the ribs 34, 34,... In the casing 33a is significantly higher than that of the other surfaces.
[0011]
The present invention has been made in view of such problems, and a main object of the present invention is to provide an electronic device capable of preventing a local extreme temperature increase in the surface temperature of the casing while maintaining heat dissipation performance. And
[0012]
[Means for Solving the Problems]
In order to achieve the above object, an electronic device according to claim 1 is a casing for housing an electronic device main body, and is disposed outside the electronic device main body in a state of being separated from the casing, and the electronic device main body. In an electronic device including a heat radiating plate that radiates heat generated by the heat to the casing side, the heat radiated by the heat radiating plate is disposed in close contact with the inner wall of the casing so as to be able to conduct along the inner wall of the casing. A first heat diffusing plate formed and a second heat diffusing plate disposed between the heat radiating plate and the first heat diffusing plate so as to partially contact the heat radiating plate. Features.
[0013]
An electronic device according to claim 2 is characterized in that in the electronic device according to claim 1 , a spacer of a non-heat transfer material that separates the second heat diffusion plate and the first heat diffusion plate from each other is provided. To do.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which an electronic device according to the present invention is applied to an AC adapter will be described with reference to the accompanying drawings. In addition, about the component same as the conventional AC adapter 31, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.
[0015]
First, the configuration of the AC adapter 1 will be described with reference to the drawings.
[0016]
As shown in FIG. 1, the AC adapter 1 includes a DC power source 2 corresponding to the electronic device main body according to the present invention, a heat dissipation plate 13 disposed so as to wrap the DC power source 2, and a resin that is fitted to each other. Accordingly, resin casings 3a and 3b for housing the DC power supply 2 encased by the heat radiating plate 13 are provided.
[0017]
The AC adapter 1 includes heat diffusion plates 4a, 4b, 5a, 5b. In this case, the thermal diffusion plates 4a and 4b correspond to the second thermal diffusion plate in the present invention, and are formed by bending a copper plate into a predetermined shape. The heat diffusing plates 4a and 4b are disposed so as to wrap around the heat radiating plate 13, as shown in FIG. 2, and in the assembled state, while being in partial contact with the heat radiating plate 13, as shown in FIG. , And are spaced apart so that a predetermined gap G is formed. On the other hand, the heat diffusion plates 5a and 5b correspond to the first heat diffusion plates in the present invention, respectively, and are formed by bending a copper plate into a predetermined shape so as to be in close contact with the inner walls of the casings 3a and 3b. As shown in FIG. 3, the heat diffusion plates 5a and 5b are bonded to the inner walls of the casings 3a and 3b with an adhesive T in the assembled state (the figure shows only the heat diffusion plates 5a and the casing 3a. ing).
[0018]
Further, as shown in FIG. 1, a plurality of spacers 6, 6... Formed of a non-heat-conductive foaming resin are bonded to the heat diffusion plates 4 a and 4 b. In the assembled state, as shown in FIG. 2, the spacer 6 is brought into contact with the heat diffusion plates 5a and 5b on the non-adhesive surface side, thereby connecting the heat diffusion plates 4a and 4b and the heat diffusion plates 5a and 5b to each other. In this way, an internal space S is formed between the heat diffusion plates 4a and 4b and the heat diffusion plates 5a and 5b.
[0019]
In the AC adapter 1, internal heat generating electronic components generate heat when the DC power supply 2 is operated, and the heat is released from the DC power supply 2. At this time, the heat causes a predetermined portion of the heat dissipation plate 13 surrounded by a broken line P shown in FIG. 1 to be heated and diffused to a portion surrounded by the broken line P1 in FIG. At this time, the heat diffusing plates 4 a and 4 b covering the heat radiating plate 13 prevent direct conduction of the heat radiated by the heat radiating plate 13 into the internal space S. Therefore, the heat in the broken line P1 is diffused to a part wider than the part surrounded by the broken line P1 in FIG. At this time, most of the heat of the heat radiating plate 13 is conducted to the heat diffusing plates 4a and 4b through the contact portions between the heat radiating plate 13 and the heat diffusing plates 4a and 4b.
[0020]
Next, the heat conducted to the heat diffusing plates 4a and 4b is diffused to the portion surrounded by the broken line P2 in FIG. 1 by conducting the heat diffusing plates 4a and 4b. In addition, although the heat conduction state in the casing 3a side is shown in the figure, since it conducts similarly in the casing 3b side, the heat conduction state in the casing 3a side will be described as a representative.
[0021]
The heat diffused by the heat diffusing plate 4a is radiated from the surface of the heat diffusing plate 4a to the internal space S, and then the heat is transferred to the inner wall of the heat diffusing plate 5a using the air in the internal space S as a medium. Then, it is conducted to the heat diffusion plate 5a while diffusing along a wider area. At this time, in the AC adapter 1, the heat diffusion plates 4a and 4b and the heat diffusion plates 5a and 5b are separated from each other by the foamed resin spacer 6 having low heat conductivity. For this reason, the heat of the heat diffusing plates 4a and 4b is not directly conducted to the heat diffusing plates 5a and 5b, but most of the heat is transferred to the heat diffusing plates 5a and 5b via the air in the internal space S. Only a part thereof is conducted to the heat diffusing plates 5a and 5b as radiant heat from the heat diffusing plates 4a and 4b. Next, the heat conducted to the heat diffusing plate 5a is conducted to the inner wall of the casing 3a while diffusing to a wider area surrounded by the broken line P3 in FIG. Thereafter, the heat conducted to the casing 3a is slightly conducted through the casing 3a and is dissipated from the surface of the casing 3a to the outside air while diffusing to a wider area surrounded by the broken line P4 in the figure.
[0022]
Thus, in this AC adapter 1, compared to the conventional AC adapter 31, the heat generated in the DC power source 2 can be diffused to a very wide range of surface portions of the casings 3 a and 3 b, so that the casings 3 a and 3 b Can be averaged. As a result, it is possible to prevent the casing 3a, 3b from rising to a locally high temperature. In this case, according to the experiment by the inventor, the temperature of the surface portion of the casing 3a surrounded by the broken line Q1 closest to the heat generating electronic component in the DC power supply 2 rises by about 29 ° from the outside air temperature. The temperature of the surface part of the casing 3a surrounded by the broken line Q2, which is a part away from the outside, rises by about 27 ° from the outside air temperature. Therefore, as a result of suppressing the temperature difference to about 2 °, the maximum surface temperature of the AC adapter 1 can be extremely reduced as compared with the conventional AC adapter 31 without reducing the heat dissipation performance. Moreover, the same experimental result is obtained also about the casing 3b side.
[0023]
The present invention is not limited to the configuration shown in the above-described embodiment of the present invention. For example, in the embodiment of the present invention, the spacers 6, 6,... Are bonded to the heat diffusing plates 4a, 4b, but the spacers 6, 6, .. are bonded to the inner walls of the heat diffusing plates 5a, 5b. May be. Moreover, it does not specifically limit about the material of the spacer 6, Various non-heat-transfer materials can be used. Further, in the embodiment of the present invention, the heat diffusion plates 4a, 4b, 5a, 5b are respectively formed in a box shape so as to wrap around the DC power supply 2, but the first and second in the present invention are the same. The shape of the heat diffusion plate is not limited to this, and may be formed in a flat plate shape or a rectangular tube shape, for example. Furthermore, in the embodiment of the present invention, the heat diffusion plates 4a, 4b, 5a, 5b are formed of copper plates, but the material of the heat diffusion plate in the present invention is not limited to this, and various metals, ceramics, etc. It can be made of a highly heat conductive material. In the embodiment of the present invention, the example in which the electronic device according to the present invention is applied to the AC adapter has been described. However, the electronic device according to the present invention is applied to, for example, various power supply devices, wireless devices, personal computers, and the like. You can also.
[0024]
【The invention's effect】
As described above, according to the electronic device of the first aspect, the first heat diffusing plate is disposed in close contact with the inner wall of the casing, so that the heat generated by the electronic device main body can be transferred to a wide area on the casing surface. Since it can be diffused, the surface temperature of the casing can be averaged, thereby preventing a local extreme temperature rise in the surface temperature of the casing while maintaining the heat dissipation performance.
[0025]
Also, by disposing the second thermal diffusion plate heat radiating plate and the first thermal diffusion plates to partially contact with the hot plate release, a wide range of surface than in the heat casing surface from the electronic equipment main body Since it can be diffused to the part, the surface temperature of the casing can be further averaged, and an extreme temperature rise of the surface temperature of the casing can be reliably prevented.
[0026]
Furthermore, according to the electronic device according to claim 2, by each other is spaced a second thermal diffusion plate and the first thermal diffusion plate by a spacer of Hidden thermal mass, the second thermal diffusion plate As a result of preventing direct conduction of heat to one heat diffusion plate, it is possible to more reliably prevent a local extreme temperature rise of the casing.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of an AC adapter 1 according to an embodiment of the present invention.
FIG. 2 is a conceptual cross-sectional view taken along line AA in the AC adapter 1 shown in FIG.
FIG. 3 is an enlarged cross-sectional view of a part of the AC adapter 1 according to the embodiment of the present invention.
4 is an external perspective view of an AC adapter 1 according to an embodiment of the present invention and a conventional AC adapter 31. FIG.
FIG. 5 is an exploded perspective view of a conventional AC adapter 31. FIG.
6 is a conceptual cross-sectional view taken along line AA in the AC adapter 31 shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 AC adapter 2 DC power supply 3a, 3b Casing 4a, 4b Heat diffusion plate 5a, 5b Heat diffusion plate 6 Spacer 13 Heat sink

Claims (2)

A casing for housing the electronic device main body, and a heat dissipating plate that is disposed outside the electronic device main body in a state of being separated from the casing and radiates heat generated by the electronic device main body to the casing side In an electronic device equipped with
The heat dissipated by the heat radiating plate and the first heat diffusing plate disposed in close contact with the inner wall of the casing so as to be able to conduct heat radiated along the inner wall of the casing An electronic apparatus comprising: a plate; and a second heat diffusion plate disposed between the first heat diffusion plate . Electronic equipment according to claim 1, characterized in that it comprises a spacer of a non-heat transfer material is separated from each other and said second thermal diffusion plate and the first thermal diffusion plate.

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