Abstract:
An electronic apparatus includes a housing, a first heat-generating member provided in the housing, a heat-radiating member thermally connected to the first heat-generating member, a first fan module guiding air to the heat-radiating member, a second heat-generating member provided in the housing, a second fan module discharging air out of the housing, and a wall section provided in the housing, located between the first fan module and the second fan module.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2003-032448, filed Feb. 10, 2003, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a electronic apparatus and a method of cooling the electronic apparatus, which are particularly favorable for a notebook personal computer and the like.  
         [0004]     2. Description of the Related Art  
         [0005]     A notebook personal computer comprises a housing in which a cooling fan module is provided. The cooling fan module cools the entire system of the computer including a CPU. The compute also comprises a temperature sensing IC for sensing the temperature of the CPU. When the temperature of the CPU exceeds a preset temperature, the IC supplies a sensing signal to the cooling fan to rotate the cooling fan and thus cool the entire system of the computer including the CPU.  
         [0006]     Jpn. Pat. Appln. KOKAI Publication No. 10-307648 discloses a method of controlling the rotation speed of a single fan module based on information obtained from temperature sensors located in different positions as well as a position corresponding to a CPU in a notebook personal computer.  
         [0007]     In the computer of the Publication, the temperature sensors have their own temperature values in advance. When the temperature actually sensed by at least one temperature sensor is not lower than the preset temperature value, the fan module rotates to cool the entire system of the personal computer including the CPU.  
         [0008]     Another system including a plurality of cooling fan modules to increase the volume of cooled air and the number of main cooling points is proposed. This system is similar to the control method of the above Publication in that the cooling fan modules turn on/off together.  
         [0009]     As described above, conventionally, the entire system of a personal computer including a CPU is cooled by turning on/off cooling fan modules or controlling the rotation speed of the cooling fan modules.  
         [0010]     Assume that a heating member such as a CPU that operates at high speed and generates a large amount of heat is loaded into a notebook personal computer whose cooling space is limited. It is very likely that the cooling fan modules will have to rotate at all times. This is not realistic in view of power consumption and noise.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     An object of the present invention is to provide a electronic apparatus that can efficiently cope with the thermal load of the system, and a method of cooling the electronic apparatus at a considerably small amount of power consumption even though a heating member such as a CPU having a large heating value is located in restricted space.  
         [0012]     An electronic apparatus according to an aspect of the present invention, comprises a housing, a first heat-generating member provided in the housing, a heat-radiating member thermally connected to the first heat-generating member, a first fan module guiding air to the heat-radiating member, a second heat-generating member provided in the housing, a second fan module discharging air out of the housing, and a wall section provided in the housing, located between the first fan module and the second fan module.  
         [0013]     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.  
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0014]     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
         [0015]      FIG. 1  is a perspective view illustrating a cooling fan module and a cooling passage on the bottom of a notebook personal computer according to an embodiment of the present invention.  
         [0016]      FIG. 2  is a perspective view showing a mounting state of a system cooling fan module of the personal computer according to the embodiment of the present invention.  
         [0017]      FIG. 3  shows a relationship between a substrate and first and second mounting areas of the personal computer according to the embodiment of the present invention.  
         [0018]      FIG. 4  is a sectional view showing a structure of a main body housing of the personal computer, taken along line A-A OF  FIG. 1 .  
         [0019]      FIG. 5  is a sectional view showing a structure of a main body housing of the personal computer, taken along line B-B of  FIG. 1 .  
         [0020]      FIG. 6  is a block diagram of the arrangement of a cooling control circuit of a system of the personal computer according to the embodiment of the present invention.  
         [0021]      FIG. 7  shows contents of fan control registers held by an embedded controller of the personal computer according to the embodiment of the present invention.  
         [0022]      FIG. 8  shows contents of fan control tables set by the embedded controller of the personal computer according to the embodiment of the present invention.  
         [0023]      FIG. 9  shows contents of a control table required by BIOS of the personal computer according to the embodiment of the present invention.  
         [0024]      FIGS. 10A and 10B  are graphs each showing a relationship between the temperature range of the control table shown in  FIG. 9  and the rotation speed of each fun module.  
         [0025]      FIG. 11  is a flowchart of controlled contents of the CPU cooling fan module of the personal computer according to the embodiment of the present invention.  
         [0026]      FIG. 12  is a flowchart of controlled contents of the system cooling fan module according to the embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]     A notebook personal computer according to an embodiment of the present invention will now be described with reference to the accompanying drawings.  
         [0028]      FIG. 1  shows the bottom of a main body housing  20  of a personal computer (PC) when it is viewed from the back thereof. In  FIG. 1 , reference numeral  21  indicates a heat sink that is thermally connected to a CPU  30  located on the underside of the housing  20  to diffuse and cool the heat generated from the CPU  30 . The heat sink  21  is provided in a CPU first cooling passage together with a CPU cooling fan module  23 . The first cooling passage is spatially separated from, e.g., other circuit elements of the personal computer by a partition wall  22 .  
         [0029]     A fan panel  24  and a CPU panel (not shown) are mounted on the bottom of the main body housing  20  to cover a first opening O 1 . Actually, the first opening O 1  includes the CPU  30 , heat sink  21  and CPU cooling fan module  23 .  
         [0030]     The fan panel  24  has a slit serving as a second opening O 2  through which cooled air is introduced by rotation of the CPU cooling fan module  23 .  
         [0031]     The cooling fan module  23  is secured to the cooling passage with screws  25  and the fan panel  24  and CPU panel are mounted with screws  26  or the like. When the cooling fan module  23  rotates under these conditions, outside air, which is taken from above the fan panel  24 , is blown toward the heat sink  21 . The air is then guided outside the main body housing  20  through a fourth opening O 4  formed on the back of the housing  20 .  
         [0032]     When the above personal computer is actually used, a slight space is secured between the bottom of the personal computer and the mounting surface such as the top of a desk by legs F formed on the bottom of the main body housing  20  ( FIG. 1  shows only two legs on the back of the housing but the housing requires at least four legs). This space allows air to be inhaled through the bottom of the housing  20 .  
         [0033]     The heat generated from the CPU  30  moves to the heat sink  21  and the flow of air discharged from the fan  23  cools the heat sink  21 . The CPU  30  is cooled accordingly.  
         [0034]     Reference numeral  28  (broken line) denotes a system cooling fan module. The system control fan module  28  cools circuit elements excluding the CPU  30  and heat sink  21  at once in the main body housing  20 .  
         [0035]     The system cooling fan module  28  is provided at the exit of a U-shaped second cooling passage that is formed to detour around the above CPU first cooling passage formed by the partition wall  22 . The circuit elements other than the CPU  30  are arranged appropriately in the second cooling passage.  
         [0036]     According to the present embodiment, the amount of air moved by one rotation of the CPU cooling fan module  23  is larger than that of air moved by one rotation of the system cooling fan module  28 . The CPU cooling fan module  23  has a larger cooling capacity.  
         [0037]     Therefore, even though the thermal load of the CPU  30  is equal to that of each of the circuit elements other than the CPU  30 , the CPU cooling fan module  23  can cool the CPU  30  at a lower rotation speed.  
         [0038]      FIG. 2  illustrates a mounting state of the system cooling fan module  28 . The system cooling fan module  28  is mounted in a position of the main body housing  20 , which corresponds to the second cooling passage, by screws  29 .  
         [0039]     In  FIG. 2 , reference numeral  22   a  denotes partition wall fitting sections that are formed integrally with the inner surface of the main body housing  20  and projected therefrom.  
         [0040]     Since the partition wall fitting sections  22   a  are fitted to the partition wall  22 , the first cooling passage for the CPU  30  and the second cooling passage for the circuit elements other than the CPU  30  are spatially separated from each other. Thus, the CPU  30  and the other circuit elements are cooled individually by the rotation of the CPU cooling fan module  23  and that of the system cooling fan module  28 .  
         [0041]      FIG. 3  shows mounting areas in a circuit board CB formed in the main body housing  20  of the personal computer. The mounting surface of the circuit board CB is divided into first and second mounting areas A 1  and A 2  by the partition wall  22 .  
         [0042]     The first mounting area A 1  includes the CPU  30 , heat sink  21  thermally connected to the CPU  30 , and CPU cooling fan module  23 .  
         [0043]     The second mounting area A 2  includes the system cooling fan module  23  and the circuit elements other than the CPU  30 .  
         [0044]     In the first mounting area A 1 , the CPU cooling fan module  23  rotates to inhale air in the direction orthogonal to  FIG. 3 . The air discharged above from the CPU cooling fan module  23  is heat-exchanged with the heat sink  21  to cool the CPU  30 . The heated air is discharged outside the main body housing  20  through the fourth opening O 4  (not shown) from above the heat sink  21 .  
         [0045]     In the second mounting area A 2 , the air inhaled from the left side of  FIG. 3  by the rotation of the system cooling fan module  28  flows in the form of the letter U so as to keep away from the first mounting area A 1  on the circuit board CB. While the air is flowing, it is heat-exchanged with the circuit elements to cool them. The cooled air is discharged out of the main body housing  20  through the third opening O 3  (not shown) on the right side of  FIG. 3  by the system cooling fan module  28 .  
         [0046]      FIG. 4  shows a section of the main body housing  20  of the personal computer, taken along line A-A of  FIG. 1 . As in  FIG. 1 , the top of the section corresponds to the bottom of the main body housing  20 .  
         [0047]     Like  FIG. 1 ,  FIG. 4  shows the main body housing  20  from which the fan panel  24  is detached. The heat sink  21  is thermally connected to the CPU  30  mounted on the circuit board CB to cover the CPU  30 . The heat sink  21  is fixed to the circuit board CB. As shown in  FIG. 3 , too, the first mounting area A 1  including the CPU  30  and heat sink  21  and the second mounting area A 2  including the system cooling fan  28  are spatially separated from each other by the partition wall  22 .  
         [0048]      FIG. 5  shows a section of the main body housing  20  of the personal computer, taken along line B-B of  FIG. 1 . As in  FIG. 1 , the top of the section corresponds to the bottom of the main body housing  20 .  
         [0049]     In the first mounting area A 1 , the air taken through the second opening O 2  of the fan panel  24  from above  FIG. 5  by the rotation of the CPU cooling fan module  23  is heat-exchanged by the heat sink  21 . The heat sink  21  is projected from the right side of the CPU cooling fan module  23  and connected to the CPU  30 . The heat-exchanged air is then discharged out of the housing  20  through the fourth opening O 4 . The air flows in the form of the letter L.  
         [0050]     The flow path of the first mounting area A 1  is longer and its air resistance is lower than that of the flow path of the second mounting area A 2  having a number of bending portions.  
         [0051]     Consequently, the CPU cooling fan module  23  can cool the CPU  30  more efficiently than the system cooling fan module  28  since its air volume is greater than that of the cooling fan module  28 .  
         [0052]      FIG. 6  shows a circuit arrangement for cooling the entire system including the CPU cooling fan module  23  and system cooling fan module  28 . A temperature sensing IC  31  monitors the temperature of the CPU  30  thermally connected to the heat sink  21 , which is one to be controlled.  
         [0053]     The temperature sensing IC  31  is connected to a south bridge circuit  32  via a serial bus  33  and supplies a sensed-temperature signal THRM# of the CPU  30  to the south bridge circuit  32  and embedded controller  34 .  
         [0054]     When the temperature of the CPU  30  exceeds a preset temperature, the IC  31  senses it and sends a cooling-request signal FANREQ to the embedded controller  34 .  
         [0055]     The south bridge circuit  32  is connected to the CPU  30  to control the interface of the entire system. The south bridge circuit  32  is also connected to a BIOS  35  and embedded controller  34 .  
         [0056]     The BIOS  35  is a program executed between the south bridge circuit  32  and OS  36  to control various peripheral devices that make up the personal computer.  
         [0057]     On the other hand, the system cooling fan module  28  and temperature sensing element  38  are provided at circuit elements  37  to be cooled excluding the CPU  30 .  
         [0058]     The temperature sensing element  38  is formed of, e.g., a thermistor. It is provided in that position of the circuit elements  37  which greatly decreases in performance and thus needs to be cooled because of a temperature rise. The element  38  sends a sensing signal corresponding to the sensed temperature to the embedded controller  34 .  
         [0059]     The embedded controller  34  holds a set value for individually controlling the rotation speeds of the CPU cooling fan module  23  and system cooling fan module  28  which are provided by the BIOS  35  through the south bridge circuit  32 .  
         [0060]     Upon receiving the sensed-temperature signal THRM# and cooling-request signal FANREQ from the temperature sensing IC  31 , the embedded controller  34  causes a fan driving circuit  39  to apply a voltage to the CPU cooling fan module  23  to rotate the fan module  23  in accordance with the set value.  
         [0061]     An operation of the personal computer according to the above-described embodiment will now be described.  
         [0062]      FIG. 7  shows the contents of a fan control register R held by the embedded controller  34 . The contents of the register R can be read/written by the BIOS  35  through the south bridge circuit  32 .  
         [0063]     The fan control register R includes a CPU fan control register R 1  for the CPU cooling fan module  23  and a system fan control register R 2  for the system cooling fan module  28 .  
         [0064]     The CPU fan control register R 1  includes a zeroth register. The zeroth register holds rotation speed information of the CPU cooling fan module  23  required by the BIOS  35  or OS  36 .  
         [0065]     The system fan control register R 2  includes zeroth to third registers.  
         [0066]     The zeroth register of the register R 2  holds rotation speed information of the system cooling fan module  28  required by the BIOS  35  or OS  36 .  
         [0067]     The first register of the register R 2  holds temperature information for shifting an operation of the system cooling fan module  28  from off-state to on-state in response to a sensing signal from the temperature sensing element  38 .  
         [0068]     The second register of the register R 2  holds temperature information for shifting an operation of the system cooling fan module  28  from on-state to off-state in response to a sensing signal from the temperature sensing element  38 .  
         [0069]     The third register of the register R 2  holds rotation speed information of the system cooling fan module  28  required in response to a sensing signal from the temperature sensing element  38 .  
         [0070]     The zeroth register of the CPU fan control register R 1  and the zeroth and third registers of the system fan control register R 2  hold information of the rotation speeds required for the respective fans. To stop the rotation, they hold a value “0”.  
         [0071]      FIG. 8  shows contents of a fan control table T held by the embedded controller  34 . The contents of the table T are set by the internal processing of the embedded controller  34 .  
         [0072]     The fan control table T includes a CPU fan control internal table T 1  for the CPU cooling fan module  23  and a system fan control internal table T 2  for the system cooling fan module  28 .  
         [0073]     The CPU fan control internal table T 1  includes a zeroth table and a first table.  
         [0074]     The rotation speed information of the CPU cooling fan module  23  transmitted from the BIOS  35  or OS  36  is set in the zeroth table of the table T 1 .  
         [0075]     The rotation speed information obtained when the CPU cooling fan module  23  rotates in response to a cooling request signal FANREQ from the temperature sensing IC  31  is set in the first table of the table T 1 .  
         [0076]     The system fan control internal table T 2  includes zeroth to second tables.  
         [0077]     The rotation speed information of the system cooling fan module  28  transmitted from the BIOS  35  or OS  36  is set in the zeroth table of the table T 2 .  
         [0078]     The rotation speed information obtained when the system cooling fan module  28  rotates in response to a cooling request signal FANREQ from the temperature sensing IC  31  is set in the first table of the table T 2 .  
         [0079]     The rotation speed information obtained when the system cooling fan module  28  rotates in response to a sensing signal from the temperature sensing element  38  is set in the second table of the table T 2 .  
         [0080]     Information of the rotation speeds necessary for the respective fans is set in the zeroth and first tables of the CPU fan control internal table T 1  and the zeroth to second tables of the system fan control internal table T 2 . To stop the rotation, a value “0” is set in the tables.  
         [0081]      FIG. 9  is a control table TB for the CPU cooling fan module  23  and system cooling fan module  28  that are managed by the BIOS  35 . The BIOS  35  reads the temperature of the CPU  30  sensed by the temperature sensing IC  31  from the south bridge circuit  32  via the serial bus and reads the rotation speed information of each of the fan modules  23  and  28  from the control table TB based on the sensed temperature. The read rotation speed information is supplied to the embedded controller  34  and held in the zeroth registers of the CPU fan control register R 1  and system fan control register R 2  of the fan control register R. The fan modules  23  and  28  are therefore required to rotate.  
         [0082]     In the control table TB, different rotation speeds are preset to the CPU cooling fan module  23  and system cooling fan module  28  for respective temperature ranges. In the lowest-temperature range  1 , for example, a value “0” is set to both the rotation speed A 1  of the CPU cooling fan module  23  and the rotation speed B 1  of the system cooling fan module  28 . Consequently, the fan modules  23  and  28  can be prevented from uselessly rotating in a low-temperature range.  
         [0083]     After that, different rotation speeds are preset to the CPU cooling fan module  23  and system cooling fan module  28  for each temperature range. The amount of air (cooling capacity) of the CPU cooling fan module  23  is larger than that of the system cooling fan module  28  as described above. Thus, the rotation speed An of the fan module  23  is set relatively lower than the rotation speed Bn of the fan module  28  even in the same temperature range  n .  
         [0084]     Assume that the rotation speed of the CPU cooling fan module  23  increases linearly as the temperature of the temperature range rises as shown in  FIG. 10A .  
         [0085]     Assume that the system cooling fan module  28  rotates at a preset maximum rotation speed even though the temperature of the temperature range rises and exceeds a certain value as shown in  FIG. 10B .  
         [0086]      FIG. 11  shows a process of rotation control of the CPU cooling fan module  23  executed by the embedded controller  34  based on the contents that have been described with reference to FIGS.  7  to  10 B.  
         [0087]     First, the controller  34  determines whether a request to control the CPU cooling fan module  23  is issued from the BIOS  35  (step A 01 ).  
         [0088]     Only when the controller  34  determines that the request is issued, it holds the rotation speed information of the fan module  23  transmitted from the BIOS  35  in the zeroth register of the CPU fan control register R 1  of the control register R, transfers the contents of the zeroth register to the zeroth table of the CPU fan control internal table T 1  of the fan control table T, and sets them to the zeroth table (step A 02 ).  
         [0089]     After that, the controller  34  determines whether the temperature sensing IC  31  issues a cooling request signal FANREQ (step A 03 ).  
         [0090]     When the signal FANREQ is not issued, the controller  34  sets the rotation speed “0” indicating that the fan module  23  does not rotate in the first table of the CPU fan control internal table T 1  (step A 04 ). When the signal FANREQ is issued, the controller  34  sets a preset value, and more specifically, the maximum rotation speed of the fan module  23  in the first table of the table T 1  (step A 05 ).  
         [0091]     After that, the value “0” indicating that the CPU cooling fan module  23  does not rotate is temporarily set as a target rotation speed for driving the fan module  23  (step A 06 ).  
         [0092]     A loop process is performed based on the total number of tables of the CPU control internal table T 1  of the fan control table T (steps A 07  to A 10 ).  
         [0093]     In the loop process, when the target rotation speed of the CPU cooling fan module  23  is not higher than the set value of the i-th table indicated by the loop count value  i , a process of resetting the set value as a target rotation speed is repeated while updating the loop count value  i  by “+1” in sequence from “1” until the value  i  reaches the maximum (=2).  
         [0094]     In the loop process, the target rotation speed is updated by selecting the largest one from the rotation speeds of the CPU cooling fan module  23  in each of the tables of the CPU fan control internal table T 1 .  
         [0095]     After the loop process, the CPU cooling fan module  23  rotates at the target rotation speed (step A 11 ). The control process of the CPU cooling fan module  23  ends.  
         [0096]      FIG. 12  shows a process of rotation control of the system cooling fan module  28  executed by the embedded controller  34 .  
         [0097]     First, the controller  34  determines whether a request to control the system cooling fan module  28  is issued from the BIOS  35  (step B 01 ).  
         [0098]     Only when the controller  34  determines that the request is issued, it holds the rotation speed information of the fan module  28  transmitted from the BIOS  35  in the zeroth register of the system fan control register R 2  of the control register R, transfers the contents of the zeroth register to the zeroth table of the system fan control internal table T 2  of the fan control table T, and sets them to the zeroth table (step B 02 ).  
         [0099]     After that, the controller  34  determines whether the temperature sensing IC  31  issues a cooling request signal FANREQ (step B 03 ).  
         [0100]     When the signal FANREQ is not issued, the controller  34  sets the rotation speed “0” indicating that the fan module  28  does not rotate in the first table of the system fan control internal table T 2  (step B 04 ).  
         [0101]     When the signal FANREQ is issued, the controller  34  sets a preset value and, more specifically, the maximum rotation speed of the fan module  28  in the first table of the table T 2  (step B 05 ).  
         [0102]     The controller  34  then determines whether the temperature of the cooling passage sensed by the temperature sensing element  38  is not lower than the temperature held in the first register of the system fan control register R 2  (step B 06 ).  
         [0103]     When the controller  34  determines that the temperature of the cooling passage is not lower than the temperature held in the first register, it sets the rotation speed information of the fan module  28 , which is held in the third register of the register R 2 , in the second table of the table T 2  (step B 07 ).  
         [0104]     When the controller  34  determines in step B 06  that the temperature sensed by the element  38  is lower than the temperature held in the first register of the register R 2 , it determines whether the sensed temperature is lower than temperature held in the second register of the register R 2  (step B 08 ).  
         [0105]     Only when the controller  34  determines that the temperature sensed by the element  38  is lower than the temperature held in the second register of the register R 2 , it sets the rotation speed “0” indicating that the fan module  28  does not rotate in the second table of the system fan control internal table T 2  (step B 09 ).  
         [0106]     After that, the value “0” indicating that the system cooling fan module  28  does not rotate is temporarily set as a target rotation speed for driving the fan module  28  (step B 10 ).  
         [0107]     A loop process is performed based on the total number of tables of the system fan control internal table T 2  of the fan control table T (steps B 11  to B 14 ).  
         [0108]     In the loop process, when the target rotation speed of the system cooling fan module  28  is not higher than the set value of the i-th table indicated by the loop count value  i , a process of resetting the set value as a target rotation speed is repeated while updating the loop count value  i  by “+1” in sequence from “1” until the value  i  reaches the maximum (=3).  
         [0109]     In the loop process, the target rotation speed is updated by selecting the largest one from the rotation speeds of the system cooling fan module  28  in each of the tables of the system fan control internal table T 2 .  
         [0110]     After the loop process, the system cooling fan module  28  rotates at the target rotation speed (step B 15 ). The control process of the system cooling fan module  28  ends.  
         [0111]     As described above, the CPU  30  and the other circuit elements configuring the system are spatially separated into two cooling passages. The elements in the respective cooling passages are individually cooled using the CPU cooling fan module  23  and system cooling fan module  28 . Consequently, though the CPU  30  having a large heating value is loaded into a notebook personal computer, it can be cooled with efficiency even at such a relatively low rotation speed as not to cause any noise problem if the CPU cooling fan module  23  has a high volume of air to cope with the thermal load of the computer.  
         [0112]     The circuit elements other than the CPU  30  are arranged in the cooling passage spatially separated from that of the CPU  30 . Basically, the circuit elements are cooled by the rotation of the system cooling fan module  28  independently of the heat generation of the CPU  30 .  
         [0113]     The system of the CPU  30  and that of the circuit elements other than the CPU  30  are cooled separately from each other. The cooling operation has only to be performed to a required extent in a required system. Wasted power consumption can thus be avoided.  
         [0114]     When the step A 03  in  FIG. 11  determines that the cooling-request signal FANREQ is input to the embedded controller  34  from the temperature sensing IC  31 , a value preset in the first table of the CPU fan control internal table T 1  and, more specifically, the maximum rotation speed of the CPU cooling fan module  23  is set in the subsequent step A 05 . When the step B 03  in  FIG. 12  make the same determination, a value preset in the first table of the table T 2  and, more specifically, the maximum rotation speed of the system cooling fan module  28  is set in the subsequent step B 05 .  
         [0115]     When the heating value of the CPU  30  that is the operation center of the personal computer is extraordinarily high, not only the CPU cooling fan module  23  for the CPU  30  but also the system cooling fan module  28  for the system other than the CPU  30  rotates at the maximum rotation speed and these fans cool the two cooling passages at the largest cooling capacity.  
         [0116]     Consequently, the cooling of the cooling passage on the system other than the CPU  30  can contribute to that of the CPU  30 .  
         [0117]     As has been described with reference to FIGS.  7  to  9 ,  11  and  12 , the BIOS  35  sets the rotation speed of each of the CPU and system cooling fan modules  23  and  28  and a comparative value between the temperatures sensed by the temperature sensing IC  31  and temperature sensing element  38  in the embedded controller  34 . Based on the contents set in the BIOS  35 , the controller  34  controls the rotation of the fan modules  23  and  28 .  
         [0118]     The personal computer has its own temperature characteristics such as air-flowing efficiency of each of two cooling passages spatially separated by the partition wall  22 , an amount of air cooled by the fan modules  23  and  28 , and an amount of heat generated from the CPU  30  and the other circuit elements. If the BIOS  35  sets proper contents in the main body housing  20  of the personal computer according to the temperature characteristics, the CPU  30  and the other circuit elements can reliably be cooled with high efficiency without wasting power.  
         [0119]     As shown in  FIG. 9  and  FIGS. 10A and 10B  in particular, the BIOS  35  sets the rotation speed of each of the CPU and system cooling fan modules  23  and  28  to a higher value in accordance with a rise in the temperature of ranges including the temperatures sensed by the temperature sensing IC  31  and temperature sensing element  38  rise.  
         [0120]     Power consumption can thus be minimized without any wasted driving of the fan modules  23  and  28  at a high rotation speed. The user of the personal computer can be provided with a comfortable environment for use.  
         [0121]     In the foregoing embodiment, two spaces corresponding to the first and second mounting areas A 1  and A 2  on the circuit board CB are separated from each other by the partition wall  22 . However, the following modification can be made, depending on the relationship in arrangement between the CPU  30  and heat sink  21  on the mounting area A 1  and some of the circuit elements on the mounting area A 2  that have a large heating value. The two spaces can be connected to each other by forming a notch in the partition wall  22  to inhale air corresponding to the second mounting area A 2  and discharge it from the fourth opening O 4  by rotating the CPU cooling fan module  23  or inhale air corresponding to the first mounting area A 1  and discharge it from the third opening O 3  by rotating the system cooling fan module  28 .  
         [0122]     The notch formed in an appropriate position of the partition wall  22  allows the two spaces to be connected to each other to mutually assist in the cooling operations of the fan modules  23  and  28 . When only one of the fans is used to cool an element on one side, it can cool another element on the other side to some extent. Consequently, the personal computer can be operated efficiently by reducing power consumption.  
         [0123]     The forgoing embodiment is directed to a notebook personal computer. The present invention is not limited to the notebook personal computer but can be applied to an information processing apparatus, such as a board type personal computer and a PDA (personal digital assistant), if the apparatus has a processing performance and cools the heat generated from a circuit element with efficiency though the size of the housing is restricted.  
         [0124]     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.