| CPC B60R 1/0602 (2013.01) [B60S 1/0848 (2013.01); B60S 1/56 (2013.01); G01J 1/0252 (2013.01); G01V 8/12 (2013.01)] | 10 Claims |
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1. A foreign object detecting system, comprising:
a light transmitter disposed adjacent to a detected object and configured to emit a light signal toward the detected object;
a light receiver disposed adjacent to the detected object in a path along which the light signal reflected by the detected object travels, wherein the light receiver includes a photoelectric component, a processor circuit, an analog-digital converter, a logic control circuit, a counter circuit, a digital processor, an overflow unit, a digital control circuit and a gain amplifier circuit, the processor circuit is connected to the photoelectric component and the analog-digital converter, the logic control circuit is connected to the analog-digital converter and the counter circuit, the digital processor is connected to the counter circuit and the overflow unit, the digital control circuit is connected to the processor circuit, the analog-digital converter, the logic control circuit and the digital processor, and the gain amplifier circuit is connected to the processor circuit and the digital processor; and
a control circuit connected to the light transmitter and the light receiver, and configured to control the light transmitter and the light receiver in a pre-operation and a detection operation;
wherein in the pre-operation, the control circuit obtains and defines the light signal received by the light receiver when a foreign object is not on the detected object as a first reflected light signal;
wherein in the detection operation, the photoelectric component converts light energy of the light signal reflected to the photoelectric component into a photocurrent and provides the photocurrent to the processor circuit, the processor circuit converts the photocurrent into a voltage, the processor circuit outputs an analog voltage signal having the voltage that is converted from the photocurrent to the analog-digital converter, the analog-digital converter converts the analog voltage signal into a digital voltage signal and outputs the digital voltage signal to the logic control circuit, the logic control circuit outputs a logic signal to the counter circuit according to the digital voltage signal from the analog-digital converter, and the counter circuit counts a number of pulse waves of the logic signal each time when the logic signal reaches a high level;
wherein the digital processor includes a signal processing circuit and a finite state machine;
wherein, in the detection operation, the digital processor controls the gain amplifier circuit according to a correctness of the logic signal;
wherein, in the detection operation, when the signal processing circuit of the digital processor determines that the logic signal distorts such that the number of pulse waves counted by the counter circuit is incorrect, the digital processor controls the gain amplifier circuit to multiply the voltage of the analog voltage signal by a gain to compensate the voltage of the analog voltage signal, the processor circuit transmits the analog voltage signal that is compensated from the gain amplifier circuit to the analog-digital converter, the analog-digital converter converts the analog voltage signal that is compensated into the digital voltage signal that is compensated, the logic control circuit outputs the logic signal that is compensated to the counter circuit according to the digital voltage signal that is compensated, and the counter circuit counts a correct number of pulse waves according to the logic signal that is compensated;
wherein, in the detection operation, when the signal processing circuit of the digital processor determines that energy of the photocurrent decreases during an operation of converting the photocurrent into the voltage such that the number of pulse waves counted by the counter circuit is incorrect, the signal processing circuit of the digital processor corrects the logic signal and outputs the logic signal that is corrected to the counter circuit for counting the correct number of pulse waves;
wherein, in the detection operation, the signal processing circuit of the digital processor outputs logic levels of the logic signal to the finite state machine connected to the signal processing circuit, and the finite state machine determines whether the logic levels of the logic signal are correctly determined by the counter circuit;
wherein, in the detection operation, when a number of the logic levels of the logic signal is more than a number of the logic levels allowed to be inputted to the finite state machine each time, the logic levels that overflow are temporarily stored in the overflow unit;
wherein, in the detection operation, the control circuit, according to the correct number of pulse waves, determines whether a difference exists between the light signal currently received by the light receiver and the first reflected light signal to determine whether the foreign object is on the detected object.
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