Patent ID: 8373409

Claim:
A fan speed testing system for testing a testing fan, a label attached to the testing fan and capable of rotating with the testing fan, the fan speed testing system comprising: a collecting module, the collecting module is configured to collect light reflected off of the label as the testing fan rotates in order to produce a pulse signal; a processing module configured to adjust the pulse signal to be a standard square wave; a converting module configured to obtain a fan speed data of the testing fan according to conversion times between high levels and low levels of the standard square wave during a given period of time; a displaying module configured to display the fan speed data; the collecting module comprises a light-emitting diode and a phototransistor; light from the light-emitting diode is capable of reflecting off of the label, and the phototransistor is capable of being periodically turned on after collecting light reflected off of the label in order to produce the pulse signal; an emitter of the phototransistor is connected to ground, and a collector of the phototransistor is connected to a first voltage source via a resistor; and the processing module comprises a first comparator and a second comparator; a first negative input terminal of the first comparator is connected to the collector of the phototransistor, and a first positive input terminal of the first comparator is connected to a second voltage source; a first output terminal of the first comparator is connected to a second positive input terminal of the second comparator, a second negative input terminal of the second comparator is connected to a second output terminal of the second comparator, and the second output terminal is connected to the converting module.