Claims
- 1. A multiple fan system, comprisingat least two simultaneously operated fans, each fan being capable of operating as a constant speed fan or as an oscillating speed fan, only one of the fans being operated as a constant speed fan, each other fan being operated as an oscillating speed fan; and one fan controller capable of controlling a plurality of oscillating speed fans for controlling a plurality of the oscillating speed fans within a different range of speed from each other oscillating speed fan, the means for controlling providing an output voltage having a varying duty cycle and providing an oscillating fan speed profile having an oscillating speed range.
- 2. The multiple fan system of claim 1 wherein the controlling means includes a separate fan controller for each oscillating speed fan.
- 3. The multiple fan system of claim 2 wherein the fan controller includes a waveform generating portion coupled to a duty-cycle modulator portion.
- 4. The multiple fan system of claim 1 wherein each of the fans is electrically operated by a DC voltage and the controlling means varies the DC voltage.
- 5. The multiple fan system of claim 1 wherein each of the fans is electrically operated by a DC voltage and the controlling means utilizes a continuously varying duty-cycle for varying the DC voltage.
- 6. The multiple fan system of claim 1 wherein each of the fans is electrically operated by a DC voltage and the controlling means includes a waveform generator and a duty-cycle modulator for varying the DC voltage.
- 7. The multiple fan system of claim 1 wherein the multiple fan system includes two oscillating speed fans and wherein the control means operates a first fan within a first range of speed and a second fan within a second range of speed.
- 8. A multiple fan system, comprising:at least two simultaneously operated fans, each fan being capable of operating as a constant speed fan or as an oscillating speed fan, only one of the fans being operated as a constant speed fan, each other fan being operated as an oscillating speed fan; and one fan controller capable of controlling a plurality of oscillating speed fans connected to each of the oscillating speed fans, the fan controller operating each fan to produce a respective acoustic emission having a range of frequency different than each of the other oscillating speed fans, and the fan controller providing an output voltage having a varying duty cycle and providing an oscillating fan speed profile having an oscillating speed range.
- 9. A multiple fan system, comprising:a constant speed fan; at least one oscillating speed fans operated simultaneously with the constant speed fan; and one fan controller capable of controlling a plurality of oscillating speed fans operating each of the oscillating speed fans within a different range of speed from each other oscillating speed fan, the fan controller providing an output voltage having a varying duty cycle and providing an oscillating fan speed profile having an oscillating speed range, the fan controller further including a waveform generating portion coupled to a duty-cycle modulator portion.
Parent Case Info
This application is a division of application Ser. No. 09/245,145, filed Feb. 4, 1999.
US Referenced Citations (28)