| 摘要 |
<p>The present invention provides a circuit (70) for detecting a change in light intensity, comprising: a voltage source (100) with a positive terminal and a negative terminal; an analogue to digital converter, the analogue 'to digital converter comprising: a phototransistor (110) operable to receive incident light, the phototransistor having a collector and an emitter, the collector connected to the positive terminal of the voltage source; a capacitor (120) having a first terminal connected to the emitter of the phototransistor, and a second terminal connected to the negative terminal of the voltage source, wherein charging of the capacitor is dependent upon the light incident on the phototransistor; and a microcontroller (150) having a first input terminal connected to the first terminal of the capacitor; wherein the microcontroller is operable to monitor light intensity incident on the phototransistor, and to compare changes in the light intensity with a profile pre-stored in the microcontroller. The present invention further provides a spray system including the above circuit for detecting a change in light intensity, so as to judge whether a replaceable refill is a genuine refill or a non-genuine refill.</p> |
