초록 ▼

Methods and apparatuses for improving cooling fan operation are disclosed. In one embodiment, a cooling fan's speed is maximized by adjusting a PWM signal driving the fan to change the switching point of the fan motor. In another embodiment, a method for starting a low speed cooling fan by increment

Methods and apparatuses for improving cooling fan operation are disclosed. In one embodiment, a cooling fan's speed is maximized by adjusting a PWM signal driving the fan to change the switching point of the fan motor. In another embodiment, a method for starting a low speed cooling fan by incrementally increasing the amplitude of the PWM signal applied to the fan is disclosed. In a further embodiment, a method for controlling a fan and a fan sensor is disclosed. In this embodiment, a PWM signal is generated, a fan is driven using the PWM signal, a cycle of the PWM signal is modified, and the fan sensors is driven using the PWM signal during the cycle. In a further embodiment, a fan incorporating these improvements is disclosed.

대표청구항 ▼

1. A method for starting a low-speed cooling fan, comprising: applying a Pulse Width Modulation (PWM) signal at a desired rate to the cooling fan;reading a speed sensor coupled with the cooling fan;determining whether the cooling fan is moving according to the speed sensor, and if the cooling fan is

1. A method for starting a low-speed cooling fan, comprising: applying a Pulse Width Modulation (PWM) signal at a desired rate to the cooling fan;reading a speed sensor coupled with the cooling fan;determining whether the cooling fan is moving according to the speed sensor, and if the cooling fan is not moving, incrementally increasing the PWM signal until the cooling fan begins moving, and after the fan begins moving restoring the PWM signal to the desired rate, which is insufficient to overcome an initial static force of the cooling fan but sufficient to keep the cooling fan running at a low speed in order to minimize noise. 2. The method of claim 1, further comprising controlling the PWM signal using a logic in a computer system. 3. The method of claim 2, wherein the cooling fan is a direct current (DC) powered fan in a portable computer. 4. The method of claim 1, wherein the desired rate is variable. 5. The method of claim 1, wherein the speed sensor is a tachometer. 6. The method of claim 5, further comprising powering the speed sensor independently of the cooling fan. 7. The method of claim 5, further comprising powering the speed sensor using the PWM signal. 8. A digital processing system, comprising: a digital processor;a memory coupled to said digital processor, the processor: applying a Pulse Width Modulation (PWM) signal at a desired rate to a cooling fan;reading a speed sensor coupled with the cooling fan;determining whether the cooling fan is moving according to the speed sensor, and if the cooling fan is not moving, incrementally increasing the PWM signal until the cooling fan begins moving, and after the fan begins moving restoring the PWM signal to the desired rate, which is insufficient to overcome an initial static force of the cooling fan but sufficient to keep the cooling fan running at a low speed in order to minimize noise. 9. The digital processing system of claim 8, further comprising controlling the PWM signal using a logic in a computer system. 10. The digital processing system of claim 9, wherein the cooling fan is a direct current (DC) powered fan in a portable computer. 11. The digital processing system of claim 10, wherein the desired rate is variable. 12. The digital processing system of claim 8, wherein the speed sensor is a tachometer. 13. The digital processing system of claim 12, further comprising the processor powering the speed sensor independently of the cooling fan. 14. The digital processing system of claim 12, further comprising the processor powering the speed sensor using the PWM signal. 15. A fan system, comprising: a motor to drive a fan;a power input coupled with the motor to drive the motor using a pulse width modulation (PWM) signal at a desired rate, wherein the desired rate is insufficient to overcome an initial static force of the fan but sufficient to keep the fan running at a low speed in order to minimize noise; anda controller coupled to the power input, the controller configured to start the motor at a speed which is insufficient to move the motor and to increase the PWM signal to cause the motor to move and configured to set the PWM signal at the desired rate after the motor is moving. 16. The fan system of claim 15 further comprising a tachometer to measure a speed of the fan, wherein if the fan is not moving, the power input increases the PWM signal until the fan begins moving, and once the fan begins moving the PWM signal is festered set to the desired rate. 17. The fan system of claim 16, wherein a cycle of the PWM signal is modified to drive the tachometer. 18. The fan system of claim 17, wherein the PWM signal is driven to 100% during the cycle.