JP2005183585A - Electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To execute effective temperature control over an electronic device which includes a unit showing a large characteristics change in response to a temperature change and is under temperature control using a liquid cooling system, without accompanying a decline in functions and an increase in consumption power of the electronic device. <P>SOLUTION: According to the temperature control over the electronic device, when the temperature of the unit having a temperature dependent characteristics rises beyond a preset threshold, the circulation path of a liquid that has exchanged heat with a unit generating accompanying heat is changed so that the circulation path does not include a heat exchanger connected thermally to the unit having the temperature dependent characteristics. When the temperature of the unit having the temperature dependent characteristics drops below the preset threshold, the circulation path of the liquid having exchanged heat is changed so that the circulation path includes the heat exchanger connected thermally to the unit having the temperature dependent characteristics. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electronic device that includes a device whose characteristics change greatly due to a temperature change, and performs temperature control by a liquid cooling system.

  Various electronic devices that include devices whose characteristics change greatly due to temperature changes and whose temperature is controlled by a liquid cooling system have been put to practical use. An information processing device including a display device will be referred to as an example of the electronic device. explain.

  In recent years, information processing apparatuses have become widespread, but liquid crystal display devices excellent in miniaturization and space saving are frequently used from those using conventional cathode ray tubes as these display devices.

  An example of this liquid crystal display device is shown in FIG. This figure is an example of a liquid crystal display device using an edge light type backlight unit generally used in a portable information processing device. The backlight 7 is a light source, and the light is condensed in one direction by the reflector 22. The condensed light is uniformly diffused with respect to the liquid crystal panel 24 by the light guide 23. The liquid crystal panel 24 displays a screen by adjusting the transmittance of each display pixel by the liquid crystal control circuit 25 and adjusting the amount of light from the light guide 23. Liquid crystal display devices that are currently in practical use may have different backlight positions or different driving methods for display pixels on the liquid crystal panel. The same configuration is adopted in that the display method is adopted.

  Although there are EL elements, LEDs, and the like in this backlight, generally a cathode ray tube (for example, a cold cathode fluorescent tube) is widespread. A cathode ray tube is excellent as a light source for a transmissive liquid crystal display device because of its good luminous efficiency and low cost. However, a disadvantage is that the change in characteristics due to a temperature change is large. For example, as shown in FIG. 3, the brightness in the case of the same power is lowered because the excitation rate of mercury is slow in the environment of 0 degrees as compared with the brightness in the environment of 25 degrees. When viewed from the user of the information processing apparatus, the visibility changes due to a change in the ambient temperature, and the visibility deteriorates remarkably due to a decrease in luminance particularly at low temperatures.

  In addition, the life of the cathode ray tube changes remarkably due to changes in ambient temperature. FIG. 4 shows the life characteristics of the cathode tube with respect to changes in ambient temperature. As shown in this figure, the lifetime of the cathode ray tube is extremely reduced when the temperature is lower than 0 degrees, and the lifetime is decreased even when the temperature is higher than 40 degrees.

  In order to solve the above problems, various backlight heating and cooling techniques have been proposed.

  In the method proposed in Patent Document 1, a Peltier device is arranged in the backlight unit, the temperature of the backlight is detected to control the voltage of the Peltier device, and the backlight unit is heated using a fluorescent tube or the like. Cooling is performed. In Patent Document 3, the Peltier element is controlled in the same manner, but the periphery of the backlight using a cold cathode fluorescent tube (CFL) and the Peltier element are thermally coupled using a liquid having high thermal conductivity. This makes it possible to heat and cool the backlight.

  However, in the above two cases, an electronic reaction such as a Peltier element is used for heating and cooling, and an applied power of the Peltier element is required. Further, since it is necessary to add an electric circuit for control to the voltage control of the Peltier element, the result is that the power consumption of the entire system is increased. This is not a good idea, especially in a portable information processing apparatus, because it has a great influence on the battery duration. Furthermore, since the Peltier element is an element that performs heat exchange, even when the temperature of the backlight is lowered, heat generation of the lowered temperature is generated on the opposite surface of the element on the working side. Therefore, it is necessary to consider the heat dissipation of this heat generation.

  Patent Document 2 proposes a method of preheating a backlight by conducting heat of a heat generating component other than a backlight using a mercury lamp inside an electronic device to a peripheral portion of the backlight by a heat conduction plate. Yes. The invention described in this document has the advantage of not affecting power consumption because no additional electronic circuit is required. However, since the backlight is always heated, an excessively high temperature state is created when the ambient temperature is high. There is a problem that the life is deteriorated due to the aging.

Japanese Patent Application Laid-Open No. 07-175035 Japanese Patent Laid-Open No. 10-321035 JP 2003-15130 A

  Conventionally, it has been necessary to use components with high power consumption in order to control the temperature of an electronic device. At the same time, for example, in a portable information processing apparatus that occupies a large percentage of convenience in battery duration, it is necessary to reduce power consumption without impairing the function. An object of the present invention is to provide an electronic device that includes a device whose characteristics change greatly due to a temperature change and performs the temperature control by a liquid cooling system, without reducing its function and increasing power consumption. An object of the present invention is to provide an electronic device that can be effectively used.

  The outline of typical inventions among inventions disclosed in this document will be described as follows.

  (1) In an electronic apparatus including a first device having a temperature-dependent characteristic, a second device that generates heat incidentally, and a liquid cooling system, the liquid cooling system is a temperature of the first device. , A first heat exchanger thermally coupled to the first device, and a second heat exchanger for exchanging heat from the second device to the liquid And a liquid circulation system for circulating the liquid, and a liquid circulation control means for controlling the circulation path of the liquid based on the output of the temperature sensor, and the output of the temperature sensor has a preset threshold value. When exceeded, the circulation path of the liquid to which heat has been transferred from the second heat exchanger is switched to one that does not include the first heat exchanger, and the output of the temperature sensor is preset. When the temperature falls below the threshold, heat is transferred from the second heat exchanger. The electronic device is characterized in that the circulation path of the liquid is switched to one including the first heat exchanger.

  (2) The electronic device according to (1), wherein the switching of the circulation path of the liquid is performed by a switching valve provided in the circulation path of the liquid.

  (3) In the electronic device according to (2), when switching to a device that does not include the first heat exchanger, the circulation path of the liquid to which heat is transmitted from the second heat exchanger is An electronic apparatus characterized in that the switching valve can physically and completely shut off the liquid circulation path including the first heat exchanger.

  (4) In the electronic device according to (3), each of the two liquid circulation paths formed inside the switching valve includes a water turbine, the water turbines are connected to each other by a conduction shaft, and the rotation of one of the water turbines is performed. Can be conducted to the other water wheel.

  (5) The electronic device according to any one of (1) to (4), wherein a hysteresis characteristic is given to switching of a circulation path based on an output of the temperature sensor.

  (6) In the electronic device according to any one of (1) to (5), the first device is any one of a backlight light source, a hard disk drive, a battery, a touch pad, a crystal resonator, and an oscillator of a display device. And the second device is any one of a CPU, a chip set, a power source, and a lamp.

  According to the present invention, in an electronic device that includes a device whose characteristics change greatly due to a temperature change and performs the temperature control by a liquid cooling system, the temperature control is effective without decreasing its function and increasing power consumption. Can be done.

  The present invention relates to an electronic device that includes a device whose characteristics change greatly due to a temperature change and performs temperature control by a liquid cooling system. In the following description, an information processing device including a display device is described. A representative example will be described in detail. The following description applies not only to a display device such as a liquid crystal display device, but also to temperature control in other electronic devices including other devices whose characteristics change greatly due to temperature changes.

  FIG. 1 shows a first embodiment of an electronic device according to the present invention. In this embodiment, a liquid is used as a heat conductive material for cooling the heat-generating component, and a cold cathode fluorescent lamp as a backlight of a display device such as a liquid crystal display device. The present invention is applied to an information processing apparatus using a tube).

  In FIG. 1, a heat generating component 1 is a component that generates a large amount of heat inside the information processing apparatus, such as a CPU (Central Processing Unit), a chip set, a power source (including a fuel cell), a lamp, and the like. Etc. Heat generated from the heat generating component 1 is transferred to the heat exchanger 2 and transferred to the liquid passing through the heat exchanger 2. An example of the structure of the heat exchanger 2 is shown in FIG. The heat exchanger 2 is made of a material having good heat conductivity, and has a liquid channel 31 inside thereof, and the heat is conducted to the liquid by the liquid passing through the channel 31. This liquid preferably has good thermal conductivity and low viscosity (for example, water). This liquid fills all of the circulation paths 51 to 56 shown in FIG. 1 and plays a role of mediating heat conduction. The liquid heated by the heat exchanger 2 is circulated in the direction of the circulation path 51 to 52 by the liquid circulation mechanism 3. As the liquid circulation mechanism 3, a water turbine pump driven by a motor, a vibration by a piezoelectric element, and the like are known. The liquid flows into the switching valve 4 by the liquid circulation mechanism 3.

  The switching valve 4 receives a control signal from the switching valve control circuit 9 and changes the state of the internal valve. A schematic diagram of the internal structure of the switching valve 4 is shown in FIG. The liquid flows into the switching valve 4 from the circulation path 52. In the case of the state 1 shown in FIG. 7A, the valve 41 moves in a direction to stop the outflow of the liquid to the circulation path 55. Therefore, all of the liquid flowing in from the circulation path 52 flows out to the circulation path 53. Further, in the case of the state 2 shown in FIG. 7B, the valve 41 moves in a direction in which the outflow to the circulation path 53 is stopped. Therefore, all of the liquid flowing in from the circulation path 52 flows out to the circulation path 55.

  Next, the backlight heat exchanger 5 will be described. FIG. 6 shows an example of the backlight heat exchanger 5. A backlight 7 made of a cold cathode fluorescent tube built in the display device 6 is disposed in contact with or close to the backlight heat exchanger 5 and is thermally coupled thereto. The backlight heat exchanger 5 has a circulation path 53 into which liquid from the switching valve flows and an outflow path to the circulation path 54. Further, a temperature sensor 8 is provided between the backlight 7 and the backlight heat exchanger 5, detects the temperature of the backlight 7, and electrically transmits the information to the switching valve control circuit 9. The switching valve control circuit 9 is a circuit that stores a predetermined threshold, and compares the temperature information from the temperature sensor 8 with the threshold to change the state of the switching valve before and after the threshold.

  The heat radiating unit 10 is for radiating the heat of the liquid flowing through the circulation path 56, and lowers the temperature of the liquid by thermally coupling a portion having a low temperature inside the information processing apparatus to the liquid circulation path 56. Works. Further, the circulation path 56 is connected to both the circulation path 54 and the circulation path 55 by the joint 12, and liquid can be introduced from either of the circulation paths.

  In the information processing apparatus according to the present embodiment, it is assumed that the operation of all other electric mechanisms is started at the same time when the apparatus is turned on or after the heating component 1 is turned on. Yes.

  Next, the actual operation in this embodiment will be described. When the information processing apparatus is turned on, the heat generating component 1 starts to generate heat, and the liquid circulation mechanism 3 starts to operate to circulate the liquid. At the same time, the switching valve control circuit 9 acquires the temperature of the backlight 7 from the temperature sensor 8. Next, the switching valve control circuit 9 compares the threshold value preset and stored therein with the temperature acquired from the temperature sensor 8, and when the temperature is lower than the threshold value, the switching valve 4 is switched to ( The valve 41 is controlled to be in the state 1 shown in a). By doing so, the liquid heated in the heat exchanger 2 flows into the backlight heat exchanger 5 via the circulation path 52, the switching valve 4, and the circulation path 53. Therefore, even when the ambient temperature is extremely low, the ambient temperature of the backlight 7 rises due to the heat of the liquid, so that adverse effects on luminance and life can be minimized. In this case, the circulation path 55 is a closed channel, and the liquid from the circulation path 54 flows toward the circulation path 56, so that there is no large inflow to the circulation path 55.

  When the temperature acquired from the temperature sensor 8 is higher than the threshold value, that is, when the temperature of the backlight 7 is higher than the threshold value, the switching valve control circuit 9 switches the valve so as to be in the state 2 shown in FIG. 41 is controlled. In this case, the liquid heated by the heat exchanger 2 flows directly through the circulation path 52 and the switching valve 4 via the circulation path 55 to the heat radiating unit 10 to radiate the heat. Therefore, since the heated liquid does not flow into the circulation path 53, the backlight heat exchanger 5, and the circulation path 54 that are closed with respect to the liquid flow path, further heating of the backlight 7 is prevented. I can do it. With the above operation, a mechanism for heating the backlight 7 at a low temperature and stopping the heating of the backlight 7 at a high temperature can be configured.

  Next, a second embodiment of the electronic apparatus according to the present invention is shown in FIG. In the present embodiment, the configuration of the liquid outlet from the switching valve 4 and the backlight heat exchanger 5 is different from that of the first embodiment. In the first embodiment, the liquid flowing out from the backlight heat exchanger 5 is a circulation path 56 that flows to the heat radiating portion 10 through the joint 12 through the circulation path 54. However, in this embodiment, the backlight heat exchange is performed. The liquid flowing out of the vessel 5 flows into the switching valve 4 via the circulation path 57. FIG. 9 shows a schematic diagram of the structure and state of the switching valve 4 in the present embodiment. The feature of this switching valve is that two valves, a valve 42 and a valve 43, are provided inside, and these two valves can be controlled simultaneously. In the state 3 shown in FIG. 9A, the valve 42 and the valve 43 move so as to connect the circulation path 52 and the circulation path 53 and the circulation path 57 and the circulation path 56. In the state 4 shown in FIG. 9B, the valve 42 and the valve 43 move so as to connect the circulation path 52 and the circulation path 56 and connect the circulation path 53 and the circulation path 57, respectively. Further, as shown in FIG. 8, a heat radiating portion 11 for radiating the heat of the liquid is provided in the middle of the circulation path 57.

  Next, the operation in the second embodiment will be described. When the temperature of the backlight 7 is lower than a preset threshold value, the switching valve control circuit 9 controls the valve 42 and the valve 43 so as to be in the state 3 shown in FIG. At this time, the liquid heated by the heat exchanger 2 flows into the backlight heat exchanger 5 from the circulation path 52 via the circulation path 53 and raises the temperature around the backlight 7. Thereafter, the liquid flows out to the circulation path 56 via the circulation path 57 and the switching valve 4 and reaches the heat radiating unit 10.

  Further, when the temperature of the backlight 7 is higher than the threshold value, the switching valve control circuit 9 controls the valve 42 and the valve 43 so as to be in the state 4 shown in FIG. In this case, the liquid heated by the heat exchanger 2 reaches the heat radiating unit 10 directly via the circulation path 52, the switching valve 4, and the circulation path 56. The liquid circulation path including the backlight heat exchanger 5 is a closed loop of the circulation path 53, the backlight heat exchanger 5, and the circulation path 57, and is completely separated from the heated liquid from the heat exchanger 2. Therefore, the heat conduction from the heated liquid can be reliably interrupted as compared with the case of the first embodiment. Further, when the circulation path 57 and the heat radiating portion 11 in the closed loop are brought to a position higher than the backlight heat exchanger 5, the liquid whose temperature has risen due to the self-heating of the backlight 7 is circulated by the circulation path 57 due to natural convection. Therefore, the backlight 7 can also dissipate heat.

  Next, a third embodiment of the electronic device according to the present invention will be described. In this embodiment, the switching valve 4 in the second embodiment is configured as shown in FIG. This is because a water wheel 44 that rotates when a liquid flows is disposed between a circulation path 52 and a circulation path 56 inside the switching valve 4, and this rotation is transmitted between the circulation path 53 and the circulation path 57 by a transmission shaft 45. It tells the arranged water wheel 46. The water wheel 44 does not operate when the valve 42 and the valve 43 are in the position of the state 3 shown in FIG. 9A, that is, when the circulation path 52 and the circulation path 56 are blocked, When the valve 42 and the valve 43 are in the state 4 position shown in FIG. 9B, that is, when the circulation path 52 and the circulation path 56 are connected, the circulation is performed by the circulation flow by the liquid circulation mechanism 3. When there is a flow from the path 52 to the circulation path 56, the water wheel 44 rotates. This rotation is transmitted to the water wheel 46 through the transmission shaft 45, and the water wheel 46 also rotates. At this time, the circulation path in which the water wheel 46 exists is a closed loop composed of the circulation path 53, the backlight heat exchanger 5, and the circulation path 57 in FIG. 8, but when the water wheel 46 rotates, The forced circulation of the liquid in this closed loop becomes possible. That is, in the second embodiment, since the circulation of the liquid in the closed loop is due to the natural convection of the liquid, the circulation path 57 and the heat dissipating part 11 are physically higher than the backlight heat exchanger 5. However, in this embodiment, the backlight 7 can radiate heat regardless of the positional relationship between the circulation path 57 and the heat radiating portion 11.

  In the first to third embodiments described so far, only one value is given as the threshold value of the switching valve control circuit 9, but in this case, the temperature of the backlight 7 is frequently near the threshold value. Since the operation of the switching valve 4 is performed each time, it is disadvantageous from the viewpoint of the durability of the valve. In order to improve this, it is possible to provide the switching valve control circuit 9 with two thresholds so that the valve switching operation has hysteresis. An example of the operation of the switching valve in this case is shown in FIG. In FIG. 11, states 1 and 2 are synonymous with states 1 and 2 shown in FIGS. 7A and 7B showing the operation state of the switching valve 4 in the first embodiment. For example, the high temperature side operating point is 60 degrees and the low temperature side operating point is 50 degrees. If the temperature has risen, the switching valve 4 will be in the state 2 position when the temperature reaches 60 degrees, but once it exceeds 60 degrees and the temperature drops, it will drop to 50 degrees. State 1 position. Thereby, even if the temperature rises and falls around 60 degrees of the high temperature side operating point, frequent switching of the valve does not occur, so that the durability of the switching valve 4 can be increased.

  In the above description, the backlight for the liquid crystal display device has been described as an example of a device having temperature-dependent characteristics, and the CPU, chip set, or power supply has been described as an example of a device that generates heat incidentally. It is not limited to.

  In the configuration of FIG. 1 described above, the heat generating component 1, the backlight 7, and the backlight heat exchanger 5 are replaced with a device 101 that generates heat incidentally, a device 107 that has temperature-dependent characteristics, and a heat exchanger 105. FIG. 12 shows the configuration of the present invention with generality. Similarly, for the configuration of FIG. 8 described above, the heat generating component 1, the backlight 7, and the backlight heat exchanger 5 include the device 101 that generates heat incidentally, the device 107 having temperature dependent characteristics, and the heat. Of course, by replacing with the exchanger 105, a general configuration diagram of the present invention can be obtained.

  Next, a further embodiment according to the present invention will be described with reference to FIG.

  In this embodiment, the present invention is applied to a personal computer (hereinafter abbreviated as PC). In FIG. 12, a device corresponding to the device 107 having temperature dependent characteristics is a magnetic head used in a hard disk drive (hereinafter abbreviated as HDD), and a device 101 that generates heat incidentally is a CPU. . The magnetic head used in the HDD generally has a problem that an error or the like is likely to occur because the magnetic force is reduced due to the reduction of the magnetic head at a low temperature.

  Therefore, in this embodiment, the temperature of the HDD is raised by increasing the ambient temperature of the HDD by using incidental heat (hereinafter referred to as waste heat) generated from the CPU or the like, thereby stabilizing the characteristics of the magnetic head. Thus, a highly reliable HDD is obtained. On the other hand, if the temperature rises too much, the life of the disk will be affected. Therefore, by controlling the switching valve 4 in FIG.

  In this embodiment, it is more effective to add a configuration in which the disk is turned on after the CPU or the like is activated and the temperature around the HDD rises (that is, pre-heat treatment).

  In this embodiment, the present invention is applied to an apparatus using a battery. In FIG. 12, a device corresponding to the device 107 having temperature dependent characteristics is a battery, and a device 101 that generates heat incidentally is a CPU, for example.

  Batteries (especially secondary batteries) are charged / discharged using chemical reactions, but if left in a state where the ambient temperature is low, the deterioration rate of chemical substances inside the battery will It will be faster than in the case of. When this is applied to a PC, if the battery is charged and discharged frequently, it can be prevented to some extent by self-heating during charging / discharging, but for example, it is always kept at a low temperature. When the environment is such that there is not much charge / discharge, there is a problem that the deterioration is accelerated as compared with the case at room temperature.

  Therefore, in this embodiment, in FIG. 12, the device corresponding to the device 107 having the temperature dependence characteristic is a battery, and the device 101 that generates heat incidentally is a CPU, for example. In this embodiment, waste heat from the CPU or the like is used to keep the periphery of the battery at a constant temperature, thereby preventing deterioration inside the battery and minimizing a decrease in life in a low temperature environment. It becomes possible. In addition, the battery has self-heating during charging / discharging, but by adjusting the temperature with the configuration of FIG. 12, the temperature of the battery unit can be prevented from rising locally, and the PC can be used comfortably. It becomes possible.

  In this embodiment, the present invention is applied to an apparatus using a touch pad. In FIG. 12, a device corresponding to the device 107 having temperature dependent characteristics is a touch pad, and a device 101 that generates heat incidentally is a CPU, for example.

  Recently, a touch pad is often used as a built-in input device such as a notebook PC. However, when the user touches the cursor or the like when the touch pad is cooled in a low temperature environment, A small amount of moisture may be condensed on the touchpad. In particular, in the case of an electrostatic induction type touch pad, if the moisture remains on the touch pad as it is, there is a problem that the movement of the cursor does not interlock with the movement of the finger and causes a malfunction.

  Therefore, in the present embodiment, in FIG. 12, the device corresponding to the device 107 having the temperature dependence characteristic is a touch pad, and the device 101 that generates heat incidentally is a CPU, for example. In this embodiment, waste heat from a CPU or the like is used to increase the temperature of the touch pad itself, thereby preventing a minute amount of moisture from remaining on the touch pad. Further, by adjusting the temperature with the configuration of FIG. 12, the temperature of the part that is always touched with a finger is controlled, so that a more comfortable input environment can be obtained.

  In this embodiment, the present invention is applied to a liquid crystal projector. In FIG. 12, a device corresponding to the temperature-dependent device 107 is a crystal resonator or an oscillator mounted on a control board, and the device 101 that generates heat incidentally serves as a light source for the liquid crystal projector. It is a lamp.

  In the case of a liquid crystal projector, the most heat generating source is a lamp that functions as a light source of the liquid crystal projector. In this case, the heat generation amount of the light source lamp is very large compared to the heat generation amount of the CPU or the like mounted on the control board. Therefore, this embodiment uses the waste heat of the light source lamp in the liquid cooling system.

  Normally, when the power is turned on, the lamp on the light source is turned on after the CPU on the control board starts operating, but the ambient temperature is very low (for example, when installed outdoors) Crystal oscillators or oscillators that generate a synchronous clock on the substrate often cause oscillation failures at low temperatures, and there is a problem that the liquid crystal projector system itself may not start up.

  Therefore, in the present embodiment, in FIG. 12, a device corresponding to the temperature-dependent characteristic 107 is a crystal resonator or an oscillator on the control board, and the device 101 that generates heat incidentally is a liquid crystal. The lamp serves as a light source for the projector.

  In the liquid crystal projector in the present embodiment, the starting system of the power source circuit of the light source lamp when the power is turned on and the starting system of the control circuit of the liquid crystal projector when the power is turned on are separately provided. First, the light source lamp is allowed to emit light unconditionally, and the waste heat is used to preheat the crystal or the oscillator on the control board. Next, the control board is operated only when the crystal resonator or oscillator on the control board reaches a preset temperature. With this configuration, the control board can be reliably operated even when the ambient temperature is very low. After that, as in the first embodiment, the temperature of the crystal resonator or oscillator on the control board can be controlled.

Block diagram illustrating a first embodiment according to the present invention. Schematic sectional view of the structure of the backlight part of the liquid crystal display device Graph showing the effect of brightness on the ambient temperature of a cathode ray tube Graph showing the effect of life on the ambient temperature of the cathode tube A perspective view showing an example of a heat exchanger Perspective view showing an example of a backlight heat exchanger Sectional drawing explaining the structure and operation | movement of the switching valve 4 in 1st Example. Block diagram for explaining a second embodiment of the present invention Sectional drawing explaining the structure and operation | movement of the switching valve 4 in 2nd Example. Sectional drawing explaining the structure and operation | movement of the switching valve 4 in 3rd Example. A graph for explaining the operation when a hysteresis operation is added to the switching valve control circuit 9 Configuration diagram of the present invention obtained by further generalizing the configuration of the first embodiment of the present invention

Explanation of symbols

1 ... exothermic parts, 2 ... heat exchanger, 3 ... liquid circulation mechanism, 4 ... switching valve,
5 ... Backlight heat exchanger, 6 ... Display device, 7 ... Backlight,
8 ... Temperature sensor, 9 ... Switch valve control circuit, 10 ... Heat radiator,
11 ... Radiating part (connected to the outflow path from the backlight heat exchanger),
12 ... Joint, 22 ... Reflector, 23 ... Light guide,
24 ... LCD panel, 25 ... LCD control circuit, 26 ... Frame,
31 ... Liquid flow path in the heat exchanger,
41 ... Valve inside the switching valve in the first embodiment,
42 ... Valve (No. 1) inside the switching valve in the second embodiment,
43 ... Valve (2) inside the switching valve in the second embodiment,
51. Liquid circulation path (path from the liquid circulation mechanism to the heat exchanger),
52. Liquid circulation path (path from heat exchanger to switching valve),
53. Liquid circulation path (path from the switching valve to the backlight heat exchanger),
54 ... Liquid circulation path (path from the backlight heat exchanger to the joint),
55. Liquid circulation path (path from the switching valve to the joint),
56 ... Liquid circulation path (path from joint or switching valve to heat radiation part),
57 ... Liquid circulation path (path from the backlight heat exchanger to the switching valve),
101. Equipment that generates heat incidentally,
105 ... heat exchanger,
107: Equipment having temperature dependent characteristics.

Claims (6)

In an electronic device including a first device having temperature dependent characteristics, a second device that incidentally generates heat, and a liquid cooling system,
The liquid cooling system is
A temperature sensor for detecting the temperature of the first device;
A first heat exchanger thermally coupled to the first device;
A second heat exchanger for exchanging heat from the second device into a liquid;
A liquid circulation system for circulating the liquid;
A liquid circulation control means for controlling a circulation path of the liquid based on an output of the temperature sensor;
When the output of the temperature sensor exceeds a preset threshold, the circulation path of the liquid to which heat is transferred from the second heat exchanger is not included in the first heat exchanger. switching,
When the output of the temperature sensor falls below a preset threshold value, the circulation path of the liquid to which heat has been transferred from the second heat exchanger is switched to that including the first heat exchanger. An electronic device characterized by that.   The electronic device according to claim 1, wherein the switching of the circulation path of the liquid is performed by a switching valve provided in the circulation path of the liquid.   When switching to the one that does not include the first heat exchanger, the circulation path of the liquid to which heat is transferred from the second heat exchanger is connected to the first heat exchanger by the switching valve. The electronic device according to claim 2, wherein the electronic device can be physically and completely cut off from the contained liquid circulation path.   A water turbine is provided in each of the two liquid circulation paths formed inside the switching valve, the water turbines are connected to each other by a transmission shaft, and the rotation of one water turbine can be transmitted to the other water turbine. 3. The electronic device according to 3.   The electronic device according to claim 1, wherein a hysteresis characteristic is given to switching of a circulation path based on an output of the temperature sensor. The first device is one of a backlight light source, a hard disk drive, a battery, a touch pad, a crystal resonator, and an oscillator of a display device, and the second device is a CPU (Central Processing Unit), a chip set The electronic device according to claim 1, which is any one of a power source and a lamp.

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