This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-196864, filed Jun. 29, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a cooling unit for accelerating the dissipation of heat generated from a heat generating component such as a semiconductor package, and an electronic apparatus equipped with the cooling unit.
Various types of portable electronic apparatuses, represented by notebook-sized portable computers or mobile information apparatuses, have recently become available. These electronic apparatuses incorporate an MPU (Micro Processing Unit) for processing multimedia information such as characters, voice and animation, etc. In accordance with the increase in processing speed or the enhancement of functionality, the power consumption of the MPU continues to increase. In proportion to this increase, the amount of heat generated during the operation of the MPU is also increasing. Accordingly, it is necessary to increase the degree of heat dissipation of the MPU in order to secure stable operation. To this end, various types of heat-dissipating/cooling means such as a heat sink and a heat pipe, etc. are indispensable.
A portable computer equipped with an MPU of a high heat release value generally has a heat sink on a circuit board that is provided with the MPU mounted thereon. The heat sink is thermally connected to the MPU via a heat pipe or a heat conduction sheet. Cooling air is forcibly supplied to the heat sink, using an electric fan.
In this conventional cooling system, cooling air is the medium that absorbs the heat of the MPU, which means that the ability to cool the MPU mainly depends upon the blowing performance of the electric fan. However, an increase in the amount of cooling air involves an increase in the rotational speed of the electric fan and hence an increase in the noise of the fan. Furthermore, since, in portable computers, housings containing the MPU or the electric fan are designed to be thin and compact, they are not big enough to house a large, high blowing performance electric fan, or to secure an ideal air passage.
In the near future, MPUs for portable computers are expected to consume greater amounts of power, and accordingly the amount of heat generated is expected to rise remarkably. In light of this, it is very possible that the cooling performance of the conventional forcible air cooling system will be insufficient, or will reach its limits.
To avoid this, a cooling system is attempted, which utilizes so-called liquid cooling, in order to enhance the efficiency of cooling the MPU, wherein a liquid having a much higher specific heat than air is used as a heat transfer medium (cooling medium).
In this new cooling system, a heat receiving head thermally connected to the MPU is located in the housing, and a heat dissipation plate is located in a display unit supported by the housing. The heat receiving head and the heat dissipation plate are connected to each other by means of a liquid-circulating pipe.
In this cooling system, since a liquid is circulated between the heat receiving head and the heat dissipation plate, the heat of the MPU is transferred to the heat receiving head, and then to the heat dissipation plate by means of the liquid. The heat transferred to the heat dissipation plate is dissipated to the air as a result of heat diffusion due to heat conduction to the display unit. Accordingly, the cooling system utilizing liquid cooling can more efficiently transfer the heat of the MPU to the display unit than the conventional cooling system utilizing forcible air cooling. Thus, the performance of cooling the MPU is enhanced and no problems occur in terms of noise.
In the cooling system utilizing liquid cooling, the heat dissipation plate is installed in the display unit and not in the housing. Therefore, a circulation pipe for flowing the liquid therethrough must be provided between the display unit and the housing.
The housing supports the display unit such that the unit can pivot between its closure position in which it covers the upper surface of the housing, and its open position in which the upper surface of the housing is exposed. Accordingly, each time the display unit is pivoted, stress created by the pivoting operation of the display unit concentrates, in particular, on the portion of the circulation pipe, which is located between the housing and the display unit. As a result, it is possible that this portion will be damaged.
The damage of the circulation pipe may lead to leakage of the liquid into the housing or the display unit, thereby causing the circuit board to short-circuit. In light of the typical manner of use of portable computers, this is the primary problem to be solved.
It is the object of the present invention to provide a cooling unit and an electronic apparatus including the cooling unit, in which the stress applied to circulation means when pivoting its display unit is reduced to an allowable level, and hence which is free from damage of the circulation means and leakage of coolant due to the damage.
To attain the object, according to a first aspect of the invention, there is provided a cooling unit for use in an electronic apparatus including a main body having a heat generating component, and a display unit pivotably supported by the main body using a hinge shaft, comprising: heat receiving means provided in the main body and thermally connected to the heat generating component; heat exchange means provided in the display unit; and circulation means for circulating cooling medium between the heat receiving means and the heat exchange means, the circulation means including a bending-force-absorbing section having a shape that is deformable to twist about an axis of the hinge shaft when the display unit is pivoted.
According to a second aspect of the invention, there is provided an electronic apparatus comprising: a main body having a heat generating component; a display unit pivotably supported by the main body using a hinge shaft; heat receiving means provided in the main body and thermally connected to the heat generating component; heat exchange means provided in the display unit; and circulation means for circulating cooling medium between the heat receiving means and the heat exchange means, the circulation means including a bending-force-absorbing section having a shape that is deformable to twist about an axis of the hinge shaft when the display unit is pivoted, the bending-force-absorbing section being located along an extended line of the axis of the hinge shaft.
In the above-described structure, the heat of the heat generating component is transferred from the heat receiving means to cooling medium. In accordance with the flow of cooling medium, the heat is transferred to the heat exchange means, where it is discharged to the atmosphere as a result of heat exchange. Cooling medium cooled by the heat exchange means is returned to the heat receiving means via the circulation means, where it again receives heat generated by the heat generating component. The repetition of this cycle enables the heat of the heat generating component to be efficiently discharged from the display unit to the atmosphere.
When the display unit is pivoted on the hinge shaft, the bending-force-absorbing section of the circulation means smoothly twists to thereby absorb a bending force applied to the circulation means during the pivoting operation. Accordingly, concentration of stress on a particular portion of the circulation means is avoided, whereby the stress on the circulation means can be reduced to an allowable value.
According to a third aspect of the invention, there is provided an electronic apparatus comprising: a main body having a heat generating component; a display unit pivotably supported by the main body using a hinge shaft; heat receiving means provided in the main body and thermally connected to the heat generating component; heat exchange means provided in the display unit; and circulation means for circulating cooling medium between the heat receiving means and the heat exchange means, the circulation means including a first heat transfer pipe for guiding, to the heat exchange means, cooling medium heated by heat conducted from the heat receiving means, and a second heat transfer pipe for guiding, to the heat receiving means, cooling medium cooled by the heat exchange means, the first and second heat transfer pipes including respective twistable bending-force-absorbing sections having a plurality of loops that are formed by coiling the first and second heat transfer pipes about an axis of the hinge shaft, the bending-force-absorbing sections of the first and second heat transfer pipes being coaxial so that the loops are engaged with the loops along an extended line of the axis of the hinge shaft.
In the above-described structure, the heat of the heat generating component is transferred from the heat receiving means to cooling medium. In accordance with the flow of cooling medium, the heat is transferred to the heat exchange means, where it is discharged to the atmosphere as a result of heat exchange. Cooling medium cooled by the heat exchange means is returned to the heat receiving means via the second heat transfer pipe, where it again receives heat generated by the heat generating component. The repetition of this cycle enables the heat of the heat generating component to be efficiently discharged from the display unit to the atmosphere.
When the display unit is pivoted on the hinge shaft, the bending-force-absorbing sections of the first and second heat transfer pipes smoothly twist to thereby absorb a bending force applied to the pipes. More specifically, the bending-force-absorbing sections have a plurality of loops formed by coiling the pipes about an extended line of the axis of the hinge shaft. When a bending force is applied to the bending-force-absorbing sections, the loops deform in a direction in which they are tightly wound, or in a direction in which they are loosely wound, thereby absorbing the bending force. As a result, concentration of stress on a particular portion of the first or second heat transfer pipe is avoided, whereby the stress on the pipes can be reduced to an allowable value.
Furthermore, since the bending-force-absorbing sections of the first and second heat transfer pipes are reliably meshed with each other, they will not be separated. Accordingly, the bending-force-absorbing sections can be formed compact at middle portions of the first and second heat transfer pipes. This means that it is not necessary to secure a wide space for individually containing the bending-force-absorbing sections of the first and second heat transfer pipes.
According to a fourth aspect of the invention, there is provided an electronic apparatus comprising: a main body having a heat generating component; a display unit pivotably supported by the main body using a hinge shaft; heat receiving means provided in the main body and thermally connected to the heat generating component; heat exchange means provided in the display unit; and circulation means for circulating cooling medium between the heat receiving means and the heat exchange means, the circulation means including an elastically-deformable hollow bending-force-absorbing section coaxial with an axis of the hinge shaft, the bending-force-absorbing section having a first passage for guiding, to the heat exchange means, cooling medium heated by heat conducted from the heat receiving means, and a second passage for guiding, to the heat receiving means, cooling medium cooled by the heat exchange means.
In the above-described structure, the heat of the heat generating component is transferred from the heat receiving means to cooling medium. In accordance with the flow of cooling medium, the heat is transferred to the heat exchange means, where it is discharged to the atmosphere as a result of heat exchange. Cooling medium cooled by the heat exchange means is returned to the heat receiving means via the circulation means, where it again receives heat generated by the heat generating component. The repetition of this cycle enables the heat of the heat generating component to be efficiently discharged from the display unit to the atmosphere.
When the display unit is pivoted on the hinge shaft, the bending-force-absorbing section of the circulation means smoothly twists to thereby absorb a bending force applied to the circulation means during the pivoting operation. Since the hollow bending-force-absorbing section is located in the axial direction of the hinge shaft, it easily twists about an extended line of the axis of the hinge shaft. Therefore, when a bending force is applied to the bending-force-absorbing section, this section smoothly twists to thereby absorb the bending force applied to the circulation means. As a result, concentration of stress on a particular portion of the circulation means is avoided, whereby the stress on the circulation means can be reduced to an allowable value.
Moreover, in the above structure, the bending-force-absorbing section includes a first passage for guiding heated cooling medium to the heat exchange means, and a second passage for guiding cooled cooling medium to the heat receiving means. Therefore, it is sufficient if the bending-force-absorbing section is provided at one location in the cooling medium circulation line, which makes it unnecessary to secure a wide space in the main body or the display unit for containing the bending-force-absorbing section.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.