Automatic temperature and humidity regulation – Ventilator type – Electrically actuated
Reexamination Certificate
2000-06-27
2002-05-21
Tanner, Harry B. (Department: 2856)
Automatic temperature and humidity regulation
Ventilator type
Electrically actuated
C236SDIG009
Reexamination Certificate
active
06390379
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to a method for controlling the revolving speed of a heat-dissipating fan, and particularly to a method for controlling the revolving speed of a fan for efficiently dissipating heat from an electronic apparatus to which the fan is applied. The present invention is also related to a device for controlling the revolving speed of a heat-dissipating fan.
BACKGROUND OF THE INVENTION
Nowadays, an electronic apparatus becomes more and more compact due to the enhanced manufacturing techniques. Along with the reduction in size, there is likely to be a problem in heat-dissipation. Therefore, much attention is paid to the development and improvement on efficient heat-dissipating devices.
For an electronic apparatus equipped with a microprocessor, for example a personal computer, a fan with a two-stage controlling mode is conventionally used for performing heat dissipation. The two controlling stages of the heat-dissipating fan include revolution at full speed and suspension of revolution. The former is performed for quick heat dissipation when a heat-dissipating operation is required, and the latter is selected for economizing electricity and reducing noise when no heat-dissipating operation is necessary. Obviously, such control means for heat dissipation is quite inflexible.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and a device for controlling the revolving speed of a heat-dissipating fan in order to properly regulate the power of the fan according to the thermal situation of an electronic apparatus in which the fan is used.
The present invention is related to a method and a device for controlling a revolving speed of a heat-dissipating fan. The fan is mounted to an electronic apparatus and revolving for dissipating heat generated during the operation of the electronic apparatus.
The method according to the present invention includes a data-input step, a temperature-measuring step, a temperature-comparing step, and a selective signal-output step. Preferably, the temperature-measuring step, the temperature-comparing step, and the selective signal-output step are repeated at predetermined intervals.
The data-input step is carried out by predetermining a target A temperature and a tolerance value.
The temperature-measuring step is carried out by measuring a current temperature of the electronic apparatus in operation.
The temperature-comparing step is carried out by comparing the current temperature with the target temperature.
The selective signal-output step is carried out by outputting a triggering signal to change the revolution of the fan when a difference between the current temperature and the target temperature is greater than the tolerance value. For example, the selective signal-output step can be performed by triggering an increase of an electric power supplied to the fan so as to speed up the revolution of the fan when the current temperature is less than the target temperature at least by the tolerance value, and/or triggering a decrease of the electric power supplied to the fan so as to speed down the revolution of the fan when the current temperature is greater than the target temperature at least by the tolerance value. Furthermore, the increase and the decrease of the electric power can be achieved by changing a duty cycle of a voltage signal supplied to the fan. Alternatively, they can be achieved by changing a level of a voltage supplied to the fan.
Preferably, a learning procedure is performed in advance to determine an actuating value and/or a suspending value of the electric power to actuate the revolution of the fan. By the previous determination of the actuating and/or the suspending values of the electric power, the present invention is adapted to be used with different kinds of fans which are actuated and/or suspended by different electric powers. In addition, the fan can be quickly actuated and/or stopped to improve dissipating efficiency and/or economize electricity thereby.
The learning procedure for determining the actuating value of the electric power can be performed by the following steps. An electric power is provided for the fan in a motionless state. The electric power is intermittently stepped up to revolve the fan. A revolving speed of the fan is detected at each power-change step. Then, a first threshold value of the electric power making the revolving speed of the fan exceed a first given value is determined as the actuating value.
On the other hand, the learning procedure for determining the suspending value of the electric power includes the following steps. the electric power provided for the fan in a motional state is intermittently stepped down. A revolving speed of the fan is detected at each power-change step. Then, a second threshold value of the electric power making the revolving speed of the fan lower than a second given value is determined as the suspending value.
A device according to a third aspect of the present invention includes a temperature sensor, a temperature comparator, and a power supply.
The temperature sensor, e.g. a thermistor, a transistor, or a thermal diode, is used for measuring a current temperature of the electronic apparatus in operation.
The temperature comparator electrically is connected to the thermometer for comparing the current temperature with a predetermined target temperature, and outputting a triggering signal if the current temperature is beyond a tolerance value from the predetermined target temperature.
The power supply is electrically connected to the temperature comparator and the fan for providing an electric power for the fan to make the fan revolve, and changing a value of the electric power in response to the triggering signal to regulate a revolving speed of the fan.
Preferably, the device further includes a memorizing device such as a memory or registers for storing therein the predetermined target temperature and the tolerance value.
The device preferably further includes a revolving-speed comparator for comparing revolving speeds of the fan detected under different electric powers in a learning procedure to determine an actuating value and/or a suspending value of the electric power to actuate and/or stop the revolution of the fan, respectively.
Preferably, the device further includes a memorizing device such as a memory or registers for storing therein the predetermined target temperature, the tolerance value, the actuating value and the suspending value.
In a preferred embodiment of the present device, the power supply is a pulse-width-modulation (PWM) voltage supply, by which a voltage signal is provided to revolve the fan, and the revolving speed of the fan is adjusted by changing a duty cycle of the voltage signal. The PWM voltage supply includes a time register, a digital pulse-width-modulation signal generator, and a signal converting circuit. The time register is used for storing therein a time unit for once pulse width modulation. The digital pulse-width-modulation signal generator is electrically connected to the temperature comparator and the time register for outputting a digital pulse-width-modulation signal, a duty cycle of which is changed in a predetermined manner in response to the triggering signal and the time unit. The signal converting circuit is electrically connected to the digital pulse-width-modulation signal generator and the fan for converting the digital pulse-width-modulation signal into the voltage signal to be provided for the fan.
Furthermore, the digital pulse-width-modulation signal generator includes an up/down counter, a cyclic counter, and a digital comparator. The up/down counter is electrically connected to the temperature comparator, and accumulatively counts upwards or downwards in response to the triggering signal. The cyclic counter is electrically connected to the time register, and counts a cycle in each the time unit. The digital comparator is electrically connected to the up/down counter and the cyclic counter, and compares counting values of the up/
Tanner Harry B.
Winbond Electronics Corporation
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