Abstract:
An arrangement and method for enhancing the cooling capacity of portable personal computers. More particularly, disclosed is the provision of an arrangement for increasing the cooling capacity of laptop computers which are constrained in size, weight and power consumption, through which transfers and dissipates heat from semiconductor chips located in the computer and which are to be cooled, to the rear side of a liquid-crystal display of the laptop computer.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present application relates to an arrangement and method for enhancing the cooling capacity of portable personal computers. More particularly, the invention is directed to the provision of an arrangement for increasing the cooling capacity of laptop computers which are constrained in size, weight and power consumption, through which transfers and dissipates heat from semiconductor chips located in the computer and which are to be cooled, to the rear side of a liquid-crystal display of the laptop computer.  
           [0003]    The capacity and performance of portable personal computers, such as laptop computers, notebook computers or the like, has recently been enhanced to such an extent that; for example, since the beginning of 1996, the thermal dissipation requirements of portable personal computers (PCs) have increased from about 10 watts to presently about 50 watts and potentially even higher values. This increase in the thermal dissipation requirements is a result of ever increasing CPU performance and additional functionality; such as DVD, modem, audio and the like, which are provided by future PCs. As elucidated in an article by Albert Yu, AThe Future of Microprocessors@, IEEE Micro, December 1996, pages 46 through 53, the trend of increasing power dissipation in the form of heat for portable personal computers will continue in the foreseeable future. Thus, at the widely employed A4 form factor for a portable personal computer; for instance, the cooling limit for a portable PC without a cooling fan is currently in excess of 20 watts and possibly up to 50 watts. Thus, providing a greater cooling capacity than the current limits in order to meet the anticipated thermal dissipation requirements of future portable personal computers, represents not only a potential competitive advantage in industry, but also provides a significant product differentiation from currently available and commercially sold portable personal computers.  
           [0004]    In essence, as set forth hereinabove, the power consumption of laptop computers, especially the power of the CPU is continually increasing in the computer technology. Thus, for instance, the total power of a laptop computer is usually above 10 watts and has now increased to the range of about 30 to 50 watts or higher, whereas CPU power has increased from about 3 to 6 watts and, conceivably, can be as high as in the 40 watts range. Most of this power will eventually be dissipated in the form of heat to the surroundings. Consequently, being able to disperse increased amounts of heat from the laptop computer becomes a critical factor in the design and commercial aspects of laptop computers. This may be accomplished through the incorporating into the computers of not only passive heat dissipating or heat sink structures such as fins, heat pipes, or the like, but also of active heat transfer devices, possibly in the form of fans and similar features.  
           [0005]    2. Discussion of the Prior Art  
           [0006]    Various arrangements and devices for increasing the cooling capacities of laptop or personal computers are currently known in the technology.  
           [0007]    Janik et al. U.S. Pat. No. 6,212,069 B1 discloses a thermally efficient portable computer wherein electronics are mounted on the display side of the portable computer having two separate plates, one for electronics and one for the display. The two plates can be brought into contact when the portable computer is closed and wherein the heat spreader comprises a separate component from an insulating rear cover closer to a display module when the portable computer is not in use, and for moving the heat spreader and insulating rear cover a distance away from the display module during use of the portable computer. This enables the spreading of the heat and efficient cooling of the heat spreader, however, is not concerned with transferring and dissipating heat from a CPU located in the main box of the computer.  
           [0008]    Haley et al. U.S. Pat. No. 6,181,555 B1 discloses a cooling system for integrated circuit chips arranged in a portable computer wherein a lid having integrated circuit components requiring heat dissipation is provided with a flexible expansion structure under the action of a spring providing for passageways in order to enable the flow of cooling air between a module and display assembly.  
           [0009]    Goto et al. U.S. Pat. No. 6,069,791 discloses a cooling device for notebook personal computers, wherein a flow passageway for cooling medium is located rearwardly of a liquid crystal display in the cover portion of the personal computer. This construction facilitates the transfer of heat from the main box of the computer to a display side in which a heat sink is positioned within a cavity rearwardly of the liquid crystal display, and wherein air is permitted flow within the cavity around the heat sink to effectuate heat dissipation.  
           [0010]    Haley et al. U.S. Pat. No. 5,982,617 discloses an arrangement for cooling the electronics which are arranged in a separate structure rearwardly above a liquid crystal display panel, and wherein flow of air is adapted to pass intermediate initially spaced components.  
         SUMMARY OF THE INVENTION  
         [0011]    Although the foregoing personal computer or laptop computer constructions each provide various types of methods to enable the heat transfer and dissipation thereof from electronic components, such as from computer chips or CPUs arranged within a personal computer, the present invention is directed to an improved arrangement and method of dissipating heat for essentially conventional portable computers in which most of the heat generating components, such as the CPU (central processing unit) are located in the main box, and wherein heat is transferred to a display component such as a cover hingedly connected to the main box and mounting the liquid crystal display. Moreover, the inventive arrangements for causing the heat to be transferred from the CPU and dissipated are unlike the prior art and provide for an expedient and highly efficient method of dissipating the generated heat.  
           [0012]    Pursuant to a first embodiment of the invention, a thermal hinge interconnecting the main box housing the CPU and the cover housing the display is employed to conduct a portion of the heat generated by the central processing unit (CPU) to heat spreaders located rearwardly of the liquid crystal display, and wherein generally flexible bellows-shaped air duct is connected between the outlet of a cooling fan located proximate the CPU to the inlet of a channel defined by two spaced heat spreaders rearwardly of the display. Air is forced into the channel from the bottom of the cover towards top edge of the cover housing the display, in that the fan is adapted to draw heated air away from the electronics or CPU into the air duct and into the channel formed by the heat spreaders so as to be conducted to the surroundings.  
           [0013]    Pursuant to a modified embodiment of the invention, the heated air generated by the electronics or CPU in the main box structure of the computer is conducted rearwardly by the action of the fan and diverted into a free space externally of the main box and rearwardly of the display cover mounting the liquid crystal display, wherein self-retractable air diverter means is employed to maintain the airflow close to the outer surface of the display cover.  
           [0014]    Accordingly, it is an object of the present invention to provide a portable device, such as a portable personal computer or the like, wherein improved cooling of the electronics contained in a main box is effected by an air stream emanating from a fan located proximate the CPU to cause the air to flow through a thermal hinge into a channel between heat spreaders rearwardly of a liquid crystal display housed in a cover portion which is hingedly connected to the main box.  
           [0015]    Pursuant to another object of the invention, the air flow is directed from the fan through a flexible bellows type thermal hinge interconnecting the cover portion mounting the liquid crystal display, and the main box housing the heat-generating electronic components, is directed therefrom into a heat spreading channel extending between heat spreaders rearwardly of the liquid crystal display and the cover of the portable computer so as to be conducted to the surroundings.  
           [0016]    In accordance with another object of the invention, the flow of air emanating from the main box containing the electronic components or CPU is directed into a free space rearwardly of the cover housing the liquid crystal display, and a mechanism adapted to open and close an air diverter automatically responsive to opening and closing of the display cover is provided to enable the heated airflow to discharge into the surrounding rearwardly of the computer cover. 
       
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS  
       [0017]    Reference may now be made to the following detailed description of preferred embodiments of the invention, taken in conjunction with the accompanying drawings; in which:  
         [0018]    [0018]FIG. 1 illustrates a perspective representation of a portable computer, such as a laptop computer, shown in an open operative condition providing a novel cooling arrangement for air conducted from a fan cooling electronics in a main box into a passageway or channel intermediate two heat spreaders arranged rearwardly of a liquid crystal display in the cover which is hinged to the main box;  
         [0019]    [0019]FIG. 2 illustrates, on an enlarged scale, a fragmentary portion of a heat dissipating and transfer arrangement, taken along line  2 - 2  in FIG. 1;  
         [0020]    [0020]FIG. 3 illustrates a perspective representation of a modified cooling mechanism for a laptop computer with an automated air diverter;  
         [0021]    [0021]FIG. 4 illustrates, on an enlarged scale, a fragmentary view taken along line  4 - 4  in FIG. 3; and  
         [0022]    [0022]FIG. 5 illustrates, in a perspective representation, the laptop computer of FIG. 3 shown in the closed position thereof. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0023]    Referring in specific detail to the embodiment of FIGS. 1 and 2 of the drawings, there is illustrated a laptop computer  10  which comprises a main box structure  12  housing the electronic components, such as a CPU (central processing unit)  14  of the computer. Arranged on top of a semiconductor chip which generally comprises the CPU  14  and which represents is the primary source of the generation of heat during the operation of the computer  10  is a cooling fan assembly  40  containing fan  16 .  
         [0024]    In a hinged construction, connected to the rear upper edge  18  of the main box  12  of the computer  10  is a cover  20  which comprises a rectangular member and wherein the interior surface  22  thereof where a liquid crystal display (not shown in FIG. 1) will be placed.  
         [0025]    Referring to FIG. 2, rearwardly of the liquid crystal display  24  there is located at least one heat spreader  26 , which may be in the form of a plate mounting the liquid crystal display  24 , and between which there may be provided a layer of a thermal insulating material  28  so as to prevent any heat or warming aspect of the heat spreader  26  from being conducted to the liquid crystal display  24 .  
         [0026]    Pursuant to the present invention, spaced from the rear surface of the heat spreader plate  26  may be a second heat spreader  32  in the form of a plate which is adhesively fastened to the inner surface  22  of the cover  20  in good thermal contact therewith, in parallel with first heat spreader  26  providing a narrow passageway or channel  34  between the heat spreaders  26 ,  32  and extending along the full height of the cover while being opened at generally both upper and lower ends thereof.  
         [0027]    The computer  10  has main box  12  containing most semiconductor chips and their associated electronics parts forming CPU  14 , which are not shown in detail for the purpose of clear illustration of the novel cooling mechanism. Fan assembly  16  is placed on top of the main heat-generating semiconductor chip, which is typically the Central-Processing Unit (CPU)  14  of the computer whereby the outlet of the fan of assembly  16  is connected to an air duct  42 . A portion of the heat generated from the CPU is carried by the air from the fan assembly, and another portion of the heat is transferred to a thermal hinge  44  via a heat pipe  46  which is mounted between the fan  160  and the thermal hinge  44 . Another heat pipe  46   a  is mounted proximate the bottom of the display cover  20  so as to carry the heat from the thermal hinge  44  to the heat spreaders  26  and  32 . Both heat spreader plates  26 ,  32  preferably are made of thermally conductive materials such as aluminum, copper, or graphite fiber composite, and form the air channel  34  between the computer display  24  and display cover  20 . The distance between these two heat spreaders is 0.5 to 10 mm to form the air channel  34 . Alternatively, the air channel can be formed by a rectangular duct with a high aspect ratio, of which all four walls are made of thermally conductive materials. The arrows A in FIG. 2 define the airflow path from the fan  16  through the air duct  42 , across a gap  48  between the air duct  42  and the display cover  20 , and to the channel  34  between the two heat spreader plates  26  and  32 . The air duct  42  is tapered such that the output end of the air duct is wider than the input end and is preferably formed by flexible bellows type wall structure such that its output end is pressed against the inlet to channel  34  between the heat spreader. The mechanical fixture to ensure the air duct output end facing the channel  34  is not shown in the drawing. The air will exit from the channel  34  at the other end of the display cover  20 , whereby grills may be provided which are not shown in the drawings.  
         [0028]    Alternatively, pursuant to a modification, in lieu of the two spaced heat spreader plates  26  and  32 , the channel or passageway  34  may be formed by only the first heat spreader plate supporting the liquid crystal display  24 , and by the interior wall surface  22  of the cover  20 , thereby eliminating the second heat spreader plate  32  shown in FIG. 2 of the drawings.  
         [0029]    Pursuant to the embodiment of FIGS. 3 through 5, wherein similar or identical parts as in the preceding embodiment are identified by the same reference numerals, the air is blown out beyond the rear of the cover  20 , whereby the heat spreader plate  26  has been eliminated, as described hereinbelow.  
         [0030]    In this embodiment, the air is blown out to the rear side of the main box  12  from the fan  16 . An air diverter  50  is placed outside the rear end wall  52  of the computer main box  12 , and the bottom edge  54  thereof is anchored inside the main box using a pivot  56  which is shown in FIG. 4 of the drawing. The air diverter  50  can be rotated about this pivot  56  during the opening and closing of the display cover  20 . Referring specifically to FIG. 4, there are provided several standoffs  58  at the upper edge  60  of the air diverter  50  so as to ensure the forming of a clearance  62  between the air diverter  50  and the outer surface of the display cover  20 . Several extension-type of springs  66  may be employed to pull the air diverter  50  against the display cover  20 . Thus, when the display cover  20  is in the closed position, the springs  66  will pull the air diverter  50  back into contact with the main box rear wall  52  as shown in FIG. 5. However, other type of springs such as a torsion type can also be readily used for this purpose. The arrows B in FIG. 4 illustrate the typical air flow pattern encountered when the display cover  20  is in an open position. Referring to FIG. 3, as in the embodiment of FIGS. 1 and 2, a heat pipe  46  is connected between the fan  16  and the thermal hinge  44  which is placed at the inner side of the rear wall of the computer main box  12 . Another heat pipe  46   a  is used to connect the thermal hinge  44  to a heat spreader  32  which is mounted to the inner surface  22  of the display cover  20  using adhesives so as to ensure a good thermal contact with the display cover  20 .  
         [0031]    From the foregoing it becomes readily apparent that the various embodiments which incorporate the different methods and arrangements for the improved heat dissipation provide for an inexpensive and superior type of heat transfer from the electronics or heat generating components in a computer to the surroundings.  
         [0032]    While the invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.