Abstract A cooling fan for use inside a circuit system, especially a pulse-width modulation speed controllable DC cooling fan which can automatically vary its speed according to the internal temperature of the circuit system. An object of the invention is to control the rotation speed of the fan by a pulse-width modulation fan speed control circuit composed of a plurality of resistors, capacitors, diodes, Zener diodes, ICs and a thermistor, which is installed inside a circuit system in combination with a DC brushless fan. The control circuit in turn outputs control signal pulse following a monostable IC of said circuit continuously triggered by a phase changing cycle timing pulse signal transmitted of the fan motor. The pulse width of the control signal pulse is determined by a resistor element within a set of monostable pulse width timing resistor-capacitor (RC). The resistor element is a thermistor which is characterized in that it can vary the resistance depending on the temperature resulting in the variation of the output pulse width as the temperature changing to control the OFF time of the phase changing cycle of the fan motor for the purpose of controlling the rotation speed of the fan.
Inventors
👤 K. N. Hsu Canon
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-28 20:32
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/08
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
103 words
A pulse-width modulation, speed controllable D brushless cooling fan for use inside a circuit system which is characterized in that said cooling fan is provided with a pulse-width modulation fan speed controlling circuit which comprises a driving IC, a Hall effect inductive IC connected with the two terminals on the input side of the driving IC and a rising-falling edge trigger monostable IC connected with the two terminals on the output side of the driving IC; wherein the rising-falling edge trigger monostable IC further has a monostable pulse width timing resistor and a monostable pulse width timing capacitor on the output side thereof.
Claim 2
Dependent Claim
103 words
A pulse-width modulation, speed controllable D brushless cooling fan for use inside a circuit system which is characterized in that said cooling fan is provided with a pulse-width modulation fan speed controlling circuit which comprises a driving IC, a Hall effect inductive IC connected with the two terminals on the input side of the driving IC and a rising-falling edge trigger monostable IC connected with the two terminals on the output side of the driving IC; wherein the rising-falling edge trigger monostable IC further has a monostable pulse width timing resistor and a monostable pulse width timing capacitor on the output side thereof.
Claim 3
Dependent Claim
31 words
A pulse-width modulation, speed controllable DC brushless cooling fan as claimed in claim 1 whcih is characterized in that the rising-falling edge trigger monostable IC is further connected with two resistors.