Heat dissipation system

A heat dissipation system for an electronic device comprises a base, a fan, a pulse width modulation speed control circuit controlling the speed of the fan, a converter outputting a voltage signal, a selection switch connected to the motor, and a control element provided on the base, connected to the switch and to the converter. When the control element is operated, the switch selectively enables the motor be connected to the output of the pulse width modulation speed control circuit or to the output of the converter, and when the motor is electrically connected to the converter, the control element can modify the output voltage of the converter.

TECHNICAL FIELD OF THE DISCLOSURE

The disclosure is related to heat dissipation and, particularly, to a heat dissipation system used in an electronic device.

BACKGROUND OF THE DISCLOSURE

Speeds of fans used to dissipate heat in a system are often controlled by Pulse Width Modulation (PWM) circuits. Usually, a heat dissipation system includes a fan controlled by a rotation control unit, a speed control circuit receiving a PWM signal produced by a rotation control unit and converting the PWM signal to a voltage signal. A motor of the fan receives the voltage signal and then adjusts its speed based on the voltage signal. The voltage signal is in a proportional relationship to the speed of the motor.

In use, however, the described system provides no information regarding the temperature of the system, and speed of the fan cannot be adjusted based on the temperature or user intention. Accordingly, when the speed of the motor automatically increases, noise produced by the high speed is inevitable. Further, in unusual situations the PWM speed control circuit may fail to control the speed of the fan normally, with no user-based remedy available.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As shown inFIGS. 2 and 3, an exemplary heat dissipation system mounted in a computer case includes a PWM speed control circuit10, a motor30, a control element40for manual control, a speed control circuit80, and a fan70connected to the motor.

The computer case includes a panel50defining an opening therein. The control element40is disposed in the opening. The control element40may retract into the opening or rebound to extend out of the opening when operated. The control element40can be a mixture of plastic and temperature sensitive color-changing material, and is injection molded. Alternatively, the control element40can be coated with a layer of temperature sensitive color-changing material. Accordingly, the color of the control40changes with temperature in the computer case, providing visual notification of the change. Distance between the notification elements, such as the control element40, and the heat source may, in fact, generate some inaccuracy in the temperature indicated. Accordingly, when defining the colors of the control40corresponding to the temperature change, the inaccuracy should be compensated. Furthermore, for more uniform color change, the control element40can be made of material having higher heat conductivities.

The PWM speed control circuit10receives PWM signals from other device external to the heat dissipation system, converts the signals into a voltage signal Vm and outputs the converted signal.

The speed control circuit80includes a direct current power source Vcc and a converter20connected thereto. The converter20outputs a voltage signal Vx. A voltage regulator provided within the converter20normalizes the output voltage of the converter20. The voltage regulator is connected to, and directed to operate by, the control element40.

The fan is connected to and driven by a motor30. The motor30includes a switch301connected to the control element40. Operation of the control element40controls the switch301to connect to the converter20, and the motor30receives the voltage signal Vx output by the speed control circuit80. The speed of the motor30is in a proportional relationship to the voltage signal Vx. When the control element40controls the switch301to connect to the output of the PWM speed control circuit10, the PWM speed control circuit10outputs a voltage signal Vm to the motor30. The speed of the motor30is in a proportional relationship to the voltage value of the voltage signal Vm now.

When the heat dissipation system controls the speed of the motor30through the PWM speed control circuit10, the speed of the fan is controlled automatically; and when the heat dissipation device is switched to manual speed control, wherein speed of the motor30is controlled by the speed control circuit20, the control element40directly controls the speed of the motor30of the fan.

Referring again toFIG. 1, a speed instruction device60may be provided on the panel50to indicate the current relationship between the control element40and speed of the fan. The speed of the fan can be set to within 1200 to 2400 revolutions per minute (RPM).

The temperature sensitive color-changing material may be gel powder with particle size of 1 to 10 micrometers (μm). Accordingly, the original color of the temperature sensitive color-changing material fades to transparency with temperature increase to or beyond a predetermined value.

The material of the control element40may, for example, be blue color-changing material which changes color at temperature 33° C. combined with red color plastic material. The color changes based on the temperature, specifically, the control element40appearing blue when the temperature is below 29° C. and the blue fading as the temperature rises, becoming fully transparent when the temperature reaches 33° C. such that the control element40shows the red color of the plastic material. Temperature of an inner surface of the computer case is thus indicated automatically. Furthermore, the panel50can be fabricated of blue color material, with resulting color contrast between the control element40and the panel50so as to even more dramatically highlight the indication.

In other embodiments, the temperature sensitive color-changing material may be provided elsewhere on the panel50or other obvious location of the computer case, and is not limited to disposition on the control element40. Additionally, the control element40is not limited to disposition on the panel50.

Furthermore, the heat dissipation system may be used in other electronic devices such as notebooks and tower servers while remaining well within the scope of the disclosure.