Electricity: motive power systems – Automatic and/or with time-delay means
Reexamination Certificate
2000-02-29
2001-10-30
Nappi, Robert E. (Department: 2837)
Electricity: motive power systems
Automatic and/or with time-delay means
C318S268000, C318S799000, C318S599000, C388S907500
Reexamination Certificate
active
06310453
ABSTRACT:
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention relates to a drive circuit for a speed adjustable fan, particular to a drive circuit, which is disposed in a fan to control the current passing through coils of the fan so as to adjust the speed of the fan without any other outside circuit.
2. DESCRIPTION OF RELATED ART
As shown in
FIG. 1
, a prior art of drive circuit for a fan comprises a 4-pin Hall sensor (IC
1
′), a computing IC (IC
2
′). It is noted that the designation of IC in the specification is an abbreviation of integrated circuit. The power source connects a third pin of the computing IC (IC
2
′) and connects a first pin of the Hall sensor (IC
1
′) through a resistor (R
1
′) respectively. The second and fourth pins of the Hall sensor (IC′) are connected to the fourth and fifth pins of the computing IC (IC
2
′) respectively. The sixth pin of the computing IC (IC
2
′) is grounded through a capacitor (C). The seventh and ninth pins of the computing IC (IC
2
′) connect two coils (V
1
′, V
2
′) respectively to drive the fan. The other ends of the coils (V
1
′, V
2
′) are connected to the power supply through a protective diode (D′). However, once the coils and the power supply in the circuit have been fixedly connected to each other, the speed of rotation can not be changed to suit the requirements of user's system. It is a trend that the speed of a fan can be changed in accordance with the user's command. It is known that heat dissipation by way of a fan is not limited under a condition of maximum load. Moreover, the problem of noise by using the fan will generate as well even under a condition of minimum load. Therefore, to improve the prior art circuit becomes necessary in order to meet the regulations of energy and noise for the environmental protection.
In view of the drawbacks of the prior art drive circuit for a fan, the inventor has dedicated in research for improvement. After having conducting various designs, investigations and prototype productions and revision based on professional experiences of the inventor, the drive circuit for a speed adjustable fan according the present invention has been developed advantageously.
SUMMARY OF THE INVENTION
The drive circuit for a speed adjustable fan of present invention is comprised of a Hall IC, a computing IC connecting to the Hall IC, an input terminal for external signals, and a current control circuit. The computing IC controls two transistors connecting therewith in a state of connecting and in a state of disconnecting sequentially to magnetize two coils in the fan alternately such that the fan can be actuated to rotate. The input signal terminal for external signals senses an external signal source. The current control circuit to control the current passing through the coils to adjust the rotational speed of the fan.
Accordingly, a primary objective of the present invention is to provide a drive circuit for a speed adjustable fan, which is arranged in the fan to adjust and control the rotational speed of the fan.
Another objective of the present invention is to provide a drive circuit for a speed adjustable fan, with which any external separate circuit is not necessary to use additionally.
REFERENCES:
patent: 3942083 (1976-03-01), Takahashi et al.
patent: 4856078 (1989-08-01), Konopka
patent: 5309076 (1994-05-01), Madsen et al.
patent: 5363024 (1994-11-01), Hiratsuka et al.
patent: 5845045 (1998-12-01), Jeske et al.
patent: 5952798 (1999-09-01), Jones et al.
patent: 6091887 (2000-07-01), Dieterle et al.
Asia Vital Components Co., LTD
Connolly Bove & Lodge & Hutz LLP
Martin Edgardo San
Nappi Robert E.
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