Electronic device, cooling fan, method for controlling cooling fan, and program

Abstract

An electronic device (100) comprises: a first control device (11) which calculates a provisional duty ratio on the basis of the difference between the temperature detected by a first temperature sensor (12a) and a first reference temperature; a storage device (21M) in which reference information indicating a correspondence relationship between a duty ratio and a target rotation speed is stored; and a second control device (21) which refers to the reference information to calculate the target rotation speed corresponding to the provisional duty ratio calculated by the first control device (11) and which calculates a final duty ratio on the basis of the difference between an actual rotation speed and the calculated target rotation speed. According to this electronic device, even when cooling fans are mass-produced, the cooling fans are operated at a desired rotation speed irrespective of individual cooling fan properties.

Description

Electronic device, cooling fan, cooling fan control method, and program

[0001] The present disclosure relates to an electronic device, a cooling fan, a control method for a cooling fan, and a program.

[0002] Inside electronic devices such as game consoles, personal computers, and server computers, cooling fans are placed to cool heat-generating components such as CPUs (Central Processing Units) and GPUs (Graphics Processing Units) mounted on circuit boards (International Publication No. 2021 / 193882).

[0003] Conventional electronic devices have a control device mounted on the device body (main board) and a motor drive circuit mounted on the cooling fan. The control device detects the temperature of the heat-generating component based on the output of a temperature sensor installed in the heat-generating component. When the temperature of the heat-generating component exceeds a reference temperature, the control device refers to reference information stored in advance in a storage device and calculates a duty ratio corresponding to the difference between the reference temperature and the temperature of the heat-generating component. The motor drive circuit applies a voltage corresponding to the duty ratio to the fan motor, causing the fan motor to rotate at a speed corresponding to that voltage.

[0004] When cooling fans are mass-produced, the rotation speed of the fan motor may vary from one cooling fan to another even if the duty ratio input from the control device is the same. Therefore, it is necessary to determine in advance the above-mentioned reference information (e.g., the relational expression showing the relationship between the temperature difference and the duty ratio) taking into account the possible difference in rotation speed that may occur among the produced cooling fans.

[0005] The electronic device proposed in the present disclosure includes a first temperature sensor for detecting the temperature of a first heat-generating component, a rotational speed sensor for detecting the rotational speed of a cooling fan, a first control device that calculates a provisional duty ratio based on the difference between the temperature detected by the first temperature sensor and a first reference temperature, a storage device that stores reference information indicating the correspondence between the duty ratio and the target rotational speed, a second control device that calculates a target rotational speed corresponding to the provisional duty ratio calculated by the first control device by referring to the reference information, and calculates a final duty ratio based on the difference between the actual rotational speed detected by the rotational speed sensor and the calculated target rotational speed, and a motor drive circuit that supplies a voltage corresponding to the final duty ratio to a fan motor.

[0006] In the cooling fan control method proposed in the present disclosure, the temperature of a first heat-generating component is detected by a first temperature sensor, a provisional duty ratio is calculated based on the difference between the temperature of the first heat-generating component detected by the first temperature sensor and a first reference temperature, a target rotation speed corresponding to the provisional duty ratio is calculated by referring to reference information stored in a memory device that indicates the correspondence between the duty ratio and the target rotation speed, and a final duty ratio is calculated based on the difference between the actual rotation speed of the cooling fan detected by a rotation speed sensor and the calculated target rotation speed.

[0007] The program proposed in the present disclosure includes a first program module that causes a first computer to function as temperature detection means that detects the temperature of a first heat-generating component using a first temperature sensor and provisional duty ratio calculation means that calculates a provisional duty ratio based on the difference between the temperature of the first heat-generating component detected by the first temperature sensor and a first reference temperature, and a second program module that causes a second computer to function as target rotation speed calculation means that calculates a target rotation speed corresponding to the provisional duty ratio by referring to reference information that indicates a correspondence between the duty ratio and a target rotation speed, and a final duty ratio calculation means that calculates a final duty ratio based on the difference between an actual rotation speed of the cooling fan detected by a rotation speed sensor and the calculated target rotation speed.

[0008] The cooling fan proposed in the present disclosure includes a rotational speed sensor for detecting the rotational speed of a fan motor, a memory device storing reference information indicating the correspondence between duty ratios and target rotational speeds, a control device that receives a provisional duty ratio calculated based on the difference between the temperature of a first heat-generating component and a first reference temperature, calculates a target rotational speed corresponding to the provisional duty ratio by referring to the reference information, and calculates a final duty ratio based on the difference between the actual rotational speed detected by the rotational speed sensor and the calculated target rotational speed, and a motor drive circuit that supplies a voltage corresponding to the final duty ratio to the fan motor.

[0009] The program proposed in the present disclosure causes a computer to function as a target rotation speed calculation means that calculates a target rotation speed corresponding to a provisional duty ratio calculated based on the difference between the temperature of the first heat-generating component and a first reference temperature by referring to reference information that indicates the correspondence between the duty ratio and the target rotation speed, and as a final duty ratio calculation means that calculates a final duty ratio based on the difference between the actual rotation speed of the cooling fan detected by a rotation speed sensor and the calculated target rotation speed.

[0010] According to the above-described electronic device, cooling fan, cooling fan control method, and program, even when cooling fans are mass-produced, the cooling fans can be operated at a desired rotation speed regardless of the characteristics of each individual cooling fan.

[0011] The first control device calculates a provisional duty ratio, and the second control device controls the fan motor so that the target rotation speed corresponds to this provisional duty ratio. Therefore, the first control device can be the same as the control device installed in an electronic device in which a PWM signal with a duty ratio corresponding to the difference between the actual temperature of a heat-generating component and a reference temperature is directly input to a motor drive circuit.

[0012] 1 is a block diagram showing the configuration of an electronic device proposed in the present disclosure; FIG. 2 is a block diagram showing the functions of a first control device possessed by the device main body; FIG. 3 is a block diagram showing the functions of a second control device possessed by the cooling fan; FIG. 4 is a diagram for explaining processing performed by a first duty ratio calculation unit; FIG. 5 is a diagram for explaining an example of reference information stored in a storage device possessed by the cooling fan; FIG. 6 is a flow chart showing an example of processing executed by the first control device; and FIG. 7 is a flow chart showing an example of processing executed by the second control device.

[0013] The electronic device, cooling fan, cooling fan control method, and program proposed in the present disclosure will be described below.

[0014] The electronic device proposed in this disclosure is, for example, an entertainment device that functions as a game device or audio-visual device. The electronic device outputs video data generated by executing a game program, video and audio data acquired over a network, and video and audio data acquired from a recording medium such as an optical disc to a display device such as a television. The electronic device may also be a personal computer or a server computer.

[0015] As shown in FIG. 1, the electronic device 100 includes a device body 10 and a cooling fan 20 .

[0016] [Device Main Body] The device main body 10 has one or more heat-generating components that generate heat when the electronic device 100 is operating. In the example shown in FIG. 1 , the device main body 10 has a first heat-generating component 12A. The first heat-generating component 12A may be a processor that executes a program stored in a storage device to control the entire electronic device 100. If the electronic device 100 is a game device, the first heat-generating component 12A may be a processor that executes a game program stored in the storage device and generates a game screen. The first heat-generating component 12A may be, for example, a central processing unit (CPU) or a graphics processing unit (GPU). Alternatively, the first heat-generating component 12A may be a system on a chip (SoC) equipped with functions such as a CPU, a GPU, and a random access memory (RAM). The storage device may include a RAM, a read-only memory (ROM), or the like. The storage device may also include a solid-state drive (SSD), a hard disk drive (HDD), or the like.

[0017] 1 , the device body 10 may further include a second heat-generating component 12B. The second heat-generating component 12B may be, for example, a transistor (e.g., a metal-oxide-semiconductor field-effect transistor (MOSFET)) for supplying power to a CPU or the like using power supplied from a power supply. The electronic device 100 may include a power supply circuit 13 that supplies power to the device body 10 and the cooling fan 20 using power supplied from a power supply external to the electronic device 100. The second heat-generating component 12B may be a component (e.g., a power transistor) that constitutes the power supply circuit 13.

[0018] 1, the device main body 10 has a first temperature sensor 12a for detecting the temperature of the first heat-generating component 12A and a second temperature sensor 12b for detecting the temperature of the second heat-generating component 12B. The first temperature sensor 12a may be, for example, a thermal diode built into a CPU, a GPU, or the like. The second temperature sensor 12b may also be, for example, a thermal diode mounted on the second heat-generating component 12B. The type of temperature sensor is not limited to the example described here, as long as it is a sensor that outputs a signal corresponding to the temperature of the heat-generating component.

[0019] The number of heat-generating components whose temperatures are detected by the temperature sensors is not limited to two. For example, three temperature sensors may be provided for each of the three heat-generating components. Furthermore, the number of components whose temperatures are detected by the temperature sensors may be only one.

[0020] 1, the device main body 10 has a first control device 11. The first control device 11 may have, for example, a microprocessor and a storage device 11M. The storage device 11M may include RAM, ROM, etc. The first control device 11 executes a program stored in the storage device 11M and controls the cooling fan 20 based on output signals from the temperature sensors 12a and 12b.

[0021] The first control device 11 for controlling the cooling fan 20 may include a CPU, a GPU, an SoC, etc., and may control the entire electronic device 100. If the electronic device 100 is a game device, the first control device 11 may execute a game program. In other words, the first heat-generating component 12A described above may be the first control device 11.

[0022] [Cooling Fan] The device main body 10 and the cooling fan 20 are housed in a housing (not shown) of the electronic device 100. The cooling fan 20 draws air from outside the electronic device 100 and forms an airflow inside the housing to cool the heat-generating components 12A and 12B. The device main body 10 may have a heat sink thermally connected to the heat-generating components 12A and 12B. In this case, the cooling fan 20 may send air toward the heat sink.

[0023] 1, the cooling fan 20 includes a second control device 21, a motor drive circuit 23, a fan motor 24, and a rotation speed sensor 24a. The cooling fan 20 includes an impeller (not shown) attached to the fan motor 24.

[0024] The second control device 21 includes, for example, a microprocessor and a storage device 21M. The storage device 21M may include RAM, ROM, etc. The second control device 21 executes a program stored in the storage device 21M to control the fan motor 24.

[0025] The motor drive circuit 23 is connected to, for example, the power supply circuit 13 included in the device main body 10. The motor drive circuit 23 uses the power supplied from the power supply circuit 13 to supply drive power to the fan motor 24. The motor drive circuit 23 has a power transistor, and applies a voltage to the fan motor 24 according to a signal (specifically, a PWM signal) output from the second control device 21.

[0026] The fan motor 24 is, for example, a DC motor, and rotates at a speed corresponding to the voltage applied from the motor drive circuit 23. The rotation speed sensor 24a is a sensor for detecting the rotation speed of the fan motor 24, and includes, for example, an encoder.

[0027] The first control device 11 may be mounted together with the CPU and GPU on a main circuit board provided in the device body 10. On the other hand, the second control device 21 may be mounted on a circuit board provided in the cooling fan 20, which is formed separately from the surface circuit board. The first control device 11 and the second control device 21 may be connected via electric wires.

[0028] [First control device] The following describes the functions of the first control device 11. As shown in Fig. 2A, the first control device 11 includes, as its functions, a first temperature detection unit 11a, a first reference temperature acquisition unit 11b, a first duty ratio calculation unit 11c, a second temperature detection unit 11e, a second reference temperature acquisition unit 11f, a second duty ratio calculation unit 11g, and a provisional duty ratio calculation unit 11h.

[0029] The first temperature detector 11a detects the temperature of the first heat-generating component 12A based on the output of the first temperature sensor 12a.

[0030] The first reference temperature acquisition unit 11b acquires a reference temperature (first reference temperature) set for the first heat-generating component 12A. Here, the first reference temperature is a temperature that is set in advance so that the first heat-generating component 12A operates appropriately. For example, when the temperature of the first heat-generating component 12A exceeds the first reference temperature, an airflow is generated inside the electronic device 100 by the cooling fan 20 (described later) so that the temperature of the first heat-generating component 12A drops to the first reference temperature.

[0031] The reference temperature of the first heat-generating component 12A may be a value that changes based on the operating state of the first heat-generating component 12A. In this case, the first reference temperature acquisition unit 11b may detect the operating state of the first heat-generating component 12A (the load acting on the first heat-generating component 12A, more specifically, the CPU usage rate or the GPU usage rate) and calculate the first reference temperature based on this operating state. In this case, the storage device 11M may store information (e.g., a map or an arithmetic expression) that represents the relationship between the operating state of the first heat-generating component 12A and the first reference temperature. Alternatively, the first reference temperature may be a fixed value that does not depend on the operating state of the first heat-generating component 12A.

[0032] The first duty ratio calculation unit 11c calculates the first duty ratio based on the difference between the first reference temperature and the temperature detected by the first temperature detection unit 11a (hereinafter referred to as the "actual temperature"). For example, the first duty ratio calculation unit 11c may calculate the first duty ratio so that the first duty ratio is proportional to the temperature difference (P control). Alternatively, the first duty ratio calculation unit 11c may integrate the temperature difference with respect to time and calculate the first duty ratio based on a value proportional to the temperature difference and the integration result (PI control). Furthermore, the first duty ratio calculation unit 11c may differentiate the temperature difference with respect to time and calculate the first duty ratio based on a value proportional to the temperature difference, the integration result, and the differentiation result (PID control).

[0033] FIG. 3 is a diagram illustrating the control of the first duty ratio calculation unit 11c. In the diagram, the horizontal axis represents time, and the vertical axis represents the temperature of the first heat-generating component 12A. In the diagram, the electronic device 100 starts operating at time t0, and the temperature of the first heat-generating component 12A begins to rise. Then, at time t1, the temperature of the first heat-generating component 12A exceeds the first reference temperature. In this case, the first duty ratio calculation unit 11c may calculate a predetermined lower limit value for the duty ratio up to time t1. After time t1, the first duty ratio calculation unit 11c may calculate a first duty ratio corresponding to the difference between the actual temperature of the first heat-generating component 12A and the first reference temperature (actual temperature - first reference temperature).

[0034] The processing of the second temperature detection unit 11e, the second reference temperature acquisition unit 11f, and the second duty ratio calculation unit 11g may be the same as that of the first temperature detection unit 11a, the first reference temperature acquisition unit 11b, and the first duty ratio calculation unit 11c described above, respectively.

[0035] That is, the second temperature detection unit 11e detects the actual temperature of the second heat-generating component 12B based on the output of the second temperature sensor 12b. The second reference temperature acquisition unit 11f acquires a reference temperature (second reference temperature) set for the second heat-generating component 12B. The second duty ratio calculation unit 11g calculates the second duty ratio based on the difference between the second reference temperature and the actual temperature detected by the second temperature detection unit 11e.

[0036] The provisional duty ratio calculation unit 11h calculates a duty ratio (provisional duty ratio) to be transmitted to the second control device 21 mounted on the cooling fan 20 based on the first duty ratio and the second duty ratio. The provisional duty ratio calculation unit 11h may, for example, compare the first duty ratio with the second duty ratio and select the larger duty ratio as the provisional duty ratio. A lower limit value, which is a duty ratio corresponding to the lower limit value of the rotation speed of the cooling fan 20, may be set as the provisional duty ratio. If both the first duty ratio and the second duty ratio are lower than this lower limit value, the provisional duty ratio calculation unit 11h may set this lower limit value as the provisional duty ratio.

[0037] The first control unit 11 transmits a PWM signal corresponding to the provisional duty ratio to the second control unit 21 of the cooling fan 20 .

[0038] [Second Control Device] The following describes the functions of the second control device 21. As shown in Fig. 2B, the second control device 21 includes, as its functions, a target rotation speed calculation unit 21a, an actual rotation speed detection unit 21b, and a final duty ratio calculation unit 21c.

[0039] The target rotation speed calculation unit 21a calculates the target rotation speed of the fan motor 24 based on the provisional duty ratio (in other words, the PWM signal) received from the first control unit 11. Reference information that associates the duty ratio with the target rotation speed is stored in advance in the storage device 21M of the second control unit 21. The target rotation speed calculation unit 21a may calculate the target rotation speed corresponding to the provisional duty ratio received from the first control unit 11 by referring to this reference information.

[0040] The reference information is, for example, a map. FIG. 4 is a diagram showing an example of such a map. In this diagram, the horizontal axis represents the duty ratio, and the vertical axis represents the target rotation speed. The map is set so that the target rotation speed increases as the duty ratio increases. Furthermore, the map may set lower limits for the target rotation speed and the duty ratio. In the example shown in FIG. 4, Dmin is set as the lower limit of the duty ratio, and Rmin is set as the lower limit of the target rotation speed corresponding to the lower limit Dmin.

[0041] The reference information is not limited to a map, and may be, for example, a relational expression that indicates the relationship between the duty ratio and the target rotation speed.

[0042] The actual rotation speed detection unit 21b detects the rotation speed (actual rotation speed) of the fan motor 24 based on the output of the rotation speed sensor 24a.

[0043] The final duty ratio calculation unit 21c calculates a duty ratio to be output to the motor drive circuit 23 based on the difference between the target rotation speed and the actual rotation speed (hereinafter, this duty ratio will be referred to as the "final duty ratio"). For example, the final duty ratio calculation unit 21c may calculate the final duty ratio so that the final duty ratio is proportional to the rotation speed difference (P control). Alternatively, the final duty ratio calculation unit 21c may integrate the rotation speed difference with respect to time and calculate the final duty ratio based on a value proportional to the rotation speed difference and the integration result (PI control). Furthermore, the final duty ratio calculation unit 21c may differentiate the rotation speed difference with respect to time and calculate the final duty ratio based on a value proportional to the rotation speed difference, the integration result, and the differentiation result (PID control).

[0044] The second control device 21 outputs a PWM signal corresponding to the calculated final duty ratio to the motor drive circuit 23. The motor drive circuit 23 uses the power supplied from the power supply circuit 13 to apply a voltage corresponding to the input PWM signal to the fan motor 24. As a result, the fan motor 24 rotates at a rotation speed corresponding to the PWM signal.

[0045] With such electronic device 100, when cooling fans 20 are mass-produced, the cooling fans 20 can be operated at a desired rotation speed regardless of the characteristics of each individual cooling fan 20. For example, suppose a PWM signal with a "duty ratio: 50%" is input to motor drive circuit 23, and a cooling fan 20 that should rotate at 2000 rpm only rotates at 1900 rpm. Even in this case, the second control device 21 processes the motor drive circuit 23 to input a final duty ratio higher than 50% so that the actual rotation speed becomes the target rotation speed of 2000 rpm.

[0046] Furthermore, first control device 11 calculates a provisional duty ratio, and second control device 21 controls fan motor 24 so that the target rotation speed corresponds to this provisional duty ratio. Therefore, the same control device as that installed in an electronic device in which a PWM signal with a duty ratio corresponding to the difference between the actual temperature of heat-generating components 12A and 12B and a reference temperature is directly input to motor drive circuit 23 can be used as first control device 11.

[0047] The final duty ratio calculation unit 21c may correct the duty ratio according to the difference between the target rotation speed and the actual rotation speed (for example, a duty ratio proportional to the difference) and use the result of the correction as the final duty ratio.

[0048] 5A is a flow diagram showing an example of processing executed by first control device 11. The processing shown in this diagram is repeatedly executed at a predetermined cycle while electronic device 100 is in operation.

[0049] First, the first control device 11 (temperature detection units 11a and 11e) detect the temperatures of the heat-generating components 12A and 12B based on the outputs of the temperature sensors 12a and 12b (S101). The first control device 11 (reference temperature acquisition units 11b and 11f) acquire the reference temperatures of the heat-generating components 12A and 12B (S102). As described above, the first control device 11 may calculate the reference temperatures based on the operating states of the heat-generating components 12A and 12B. If the reference temperatures are fixed values, the first control device 11 may read these fixed values ​​from the storage device 11M.

[0050] The first control device 11 (first duty ratio calculation unit 11c) calculates a first duty ratio based on the difference between the actual temperature of the first heat-generating component 12A detected based on the output of the first temperature sensor 12a and the reference temperature of the first heat-generating component 12A (S103), and the first control device 11 (second duty ratio calculation unit 11g) calculates a second duty ratio based on the difference between the actual temperature of the second heat-generating component 12B detected based on the output of the second temperature sensor 12b and the reference temperature of the second heat-generating component 12B (S103).

[0051] The provisional duty ratio calculation unit 11h calculates a provisional duty ratio based on the first duty ratio and the second duty ratio calculated in S103 (S104). As described above, the provisional duty ratio calculation unit 11h may compare the first duty ratio and the second duty ratio and select the higher duty ratio as the provisional duty ratio. The first control unit 11 transmits a PWM signal corresponding to the provisional duty ratio to the second control unit 21 of the cooling fan 20 (S105). Then, the first control unit 11 ends the current process and restarts the process of S101.

[0052] 5B is a flow diagram showing an example of processing executed by second control device 21. The processing shown in this diagram is also repeatedly executed at a predetermined cycle while electronic device 100 is in operation.

[0053] The second control device 21 (target rotation speed calculation unit 21a) calculates a target rotation speed of the fan motor 24 according to the provisional duty ratio received from the first control device 11 (S201). The second control device 21 (actual rotation speed detection unit 21b) detects the actual rotation speed of the fan motor 24 based on the output of the rotation speed sensor 24a (S202). Next, the second control device 21 (final duty ratio calculation unit 21c) calculates a final duty ratio based on the difference (rotation speed difference) between the target rotation speed of the fan motor 24 and the actual rotation speed of the fan motor 24 (S203). The second control device 21 then outputs a PWM signal according to the final duty ratio to the motor drive circuit 23 (S204).

[0054] [Summary] (1) As described above, the electronic device proposed in this disclosure includes a first temperature sensor for detecting the temperature of a first heat-generating component, a rotational speed sensor for detecting the rotational speed of a cooling fan, a first control device that calculates a provisional duty ratio based on the difference between the temperature detected by the first temperature sensor and a first reference temperature, a storage device that stores reference information indicating the correspondence between the duty ratio and the target rotational speed, a second control device that calculates a target rotational speed according to the provisional duty ratio calculated by the first control device by referring to the reference information, and calculates a final duty ratio based on the difference between the actual rotational speed detected by the rotational speed sensor and the calculated target rotational speed, and a motor drive circuit that supplies a voltage according to the final duty ratio to a fan motor.

[0055] According to this electronic device, even when cooling fans are mass-produced, the cooling fans can be operated at a desired rotation speed regardless of the characteristics of each individual cooling fan. Furthermore, the first control device calculates a provisional duty ratio, and the second control device controls the fan motor to achieve a target rotation speed corresponding to this provisional duty ratio. Therefore, the first control device can be the same as the control device installed in an electronic device in which a PWM signal with a duty ratio corresponding to the difference between the actual temperature of a heat-generating component and a reference temperature is directly input to a motor drive circuit.

[0056] (2) The electronic device of (1) may further include a second temperature sensor for detecting a temperature of a second heat-generating component. The first control device may calculate the provisional duty ratio based on the difference between the temperature of the first heat-generating component detected by the first temperature sensor and the first reference temperature, and the difference between the temperature of the second heat-generating component detected by the second temperature sensor and the second reference temperature.

[0057] (3) The electronic device of (1) or (2) may include a device body having the first temperature sensor and the first control device, and a cooling fan having the rotational speed sensor, the storage device, the second control device, and the motor drive circuit. The first control device may transmit a PWM signal corresponding to the temporary duty ratio to the second control device.

[0058] (4) In the control method proposed in the present disclosure, the temperature of a first heat-generating component is detected by a first temperature sensor, a provisional duty ratio is calculated based on the difference between the temperature of the first heat-generating component detected by the first temperature sensor and a first reference temperature, a target rotation speed corresponding to the provisional duty ratio is calculated by referring to reference information stored in a memory device that indicates the correspondence between the duty ratio and the target rotation speed, and a final duty ratio is calculated based on the difference between the actual rotation speed of the cooling fan detected by a rotation speed sensor and the calculated target rotation speed.

[0059] (5) The program proposed in the present disclosure includes a first program module executed by the first control device 11 and a second program module executed by the second control device 21. The first program module causes the first control device 11 to function as temperature detection means that detects the temperature of a first heat-generating component using a first temperature sensor and as provisional duty ratio calculation means that calculates a provisional duty ratio based on the difference between the temperature of the first heat-generating component detected by the first temperature sensor and a first reference temperature. The second program module causes the second control device 21 to function as target rotation speed calculation means that calculates a target rotation speed corresponding to the provisional duty ratio by referring to reference information indicating a correspondence between the duty ratio and a target rotation speed, and as final duty ratio calculation means that calculates a final duty ratio based on the difference between an actual rotation speed of the cooling fan detected by a rotation speed sensor and the calculated target rotation speed.

[0060] (6) A cooling fan proposed in this disclosure includes a rotational speed sensor for detecting the rotational speed of a fan motor, a storage device storing reference information indicating a correspondence relationship between a duty ratio and a target rotational speed, and a control device. The control device receives a provisional duty ratio calculated based on the difference between the temperature of a first heat-generating component and a first reference temperature, calculates a target rotational speed corresponding to the provisional duty ratio by referring to the reference information, and calculates a final duty ratio based on the difference between an actual rotational speed detected by the rotational speed sensor and the calculated target rotational speed. The cooling fan also includes a motor drive circuit that supplies a voltage corresponding to the final duty ratio to the fan motor.

[0061] (7) The program proposed in this disclosure causes the second control device provided in the cooling fan to function as a target rotation speed calculation means that calculates a target rotation speed corresponding to a provisional duty ratio calculated based on the difference between the temperature of the first heat-generating component and the first reference temperature by referring to reference information indicating the correspondence between the duty ratio and the target rotation speed, and as a final duty ratio calculation means that calculates a final duty ratio based on the difference between the actual rotation speed of the cooling fan detected by the rotation speed sensor and the calculated target rotation speed.

[0062] [Others] The electronic device proposed in the present disclosure is not limited to the electronic device 100 described above.

[0063] For example, the number of heat-generating components included in the device body 10 (the number of heat-generating components whose temperatures are detected by the temperature sensor) may be one.

[0064] Furthermore, some of the elements and functions of the cooling fan 20 described above may be included in the device main body 10. Conversely, some of the elements and functions of the device main body 10 may be included in the cooling fan 20.

Claims

1. An electronic device having: a first temperature sensor for detecting the temperature of a first heat-generating component; a rotation speed sensor for detecting the rotation speed of a cooling fan; a first control device for calculating a provisional duty ratio based on the difference between the temperature detected by said first temperature sensor and a first reference temperature; a storage device storing reference information showing the correspondence between duty ratios and target rotation speeds; a second control device for calculating a target rotation speed according to the provisional duty ratio calculated by said first control device by referring to the reference information, and for calculating a final duty ratio based on the difference between the actual rotation speed detected by said rotation speed sensor and the calculated target rotation speed; and a motor drive circuit for supplying a voltage according to the final duty ratio to a fan motor.

2. The electronic device according to claim 1, further comprising a second temperature sensor for detecting the temperature of a second heat-generating component, wherein the first control device calculates the provisional duty ratio based on the difference between the temperature of the first heat-generating component detected by the first temperature sensor and the first reference temperature, and the difference between the temperature of the second heat-generating component detected by the second temperature sensor and the second reference temperature.

3. An electronic device according to claim 1, comprising: an equipment body having the first temperature sensor and the first control device; and a cooling fan having the rotational speed sensor, the memory device, the second control device, and the motor drive circuit, wherein the first control device transmits a PWM signal according to the provisional duty ratio to the second control device.

4. A cooling fan control method comprising: detecting the temperature of a first heat-generating component with a first temperature sensor; calculating a provisional duty ratio based on the difference between the temperature of the first heat-generating component detected by said first temperature sensor and a first reference temperature; calculating a target rotation speed corresponding to said provisional duty ratio by referring to reference information stored in a storage device that indicates the correspondence between duty ratios and target rotation speeds; and calculating a final duty ratio based on the difference between the actual rotation speed of the cooling fan detected by a rotation speed sensor and said calculated target rotation speed.

5. A program including: a first program module that causes a first computer to function as: temperature detection means that detects the temperature of a first heat-generating component using a first temperature sensor; and provisional duty ratio calculation means that calculates a provisional duty ratio based on the difference between the temperature of the first heat-generating component detected by said first temperature sensor and a first reference temperature; target rotation speed calculation means that calculates a target rotation speed according to said provisional duty ratio by referring to reference information that indicates the correspondence between duty ratios and target rotation speeds; and a second program module that causes a second computer to function as: final duty ratio calculation means that calculates a final duty ratio based on the difference between the actual rotation speed of a cooling fan detected by a rotation speed sensor and said calculated target rotation speed.

6. A cooling fan comprising: a rotation speed sensor for detecting the rotation speed of a fan motor; a storage device storing reference information indicating the correspondence between duty ratios and target rotation speeds; a control device that receives a provisional duty ratio calculated based on the difference between the temperature of a first heat-generating component and a first reference temperature, calculates a target rotation speed corresponding to the provisional duty ratio by referring to the reference information, and calculates a final duty ratio based on the difference between the actual rotation speed detected by the rotation speed sensor and the calculated target rotation speed; and a motor drive circuit that supplies a voltage corresponding to the final duty ratio to the fan motor.

7. A program that causes a computer to function as: a target rotation speed calculation means that calculates a target rotation speed according to a provisional duty ratio calculated based on the difference between the temperature of the first heat-generating component and a first reference temperature by referring to reference information that indicates the correspondence between the duty ratio and the target rotation speed; and a final duty ratio calculation means that calculates a final duty ratio based on the difference between the actual rotation speed of the cooling fan detected by a rotation speed sensor and the calculated target rotation speed.

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