Patent ID: 11958413
Assignee: ANPEC ELECTRONICS CORPORATION
Field: Transport (Mechanical engineering)
Classification: CPC B  G | IPC B  G

Claim 5:
6. A foreign object detecting method, comprising processes of:
(a) emitting a light signal toward a detected object by a light transmitter;
(b) converting, by a photoelectric component included in a light receiver, light energy of the light signal reflected to the photoelectric component into a photocurrent;
(c) defining the light signal that is received by the photoelectric component of the light receiver when a foreign object is not on the detected object as a first reflected light signal, by a control circuit;
(d) converting the photocurrent into a voltage by a processor circuit included in the light receiver;
(e) outputting, by the processor circuit of the light receiver, an analog voltage signal having the voltage that is converted from the photocurrent to an analog-digital converter included in the light receiver;
(f) converting the analog voltage signal into a digital voltage signal, by the analog-digital converter of the light receiver;
(g) outputting, by a logic control circuit included in the light receiver, a logic signal to a counter circuit included in the light receiver according to the digital voltage signal from the analog-digital converter;
(h) counting, by the counter circuit of the light receiver, a number of pulse waves of the logic signal each time when the logic signal reaches a high level;
(i) controlling a gain amplifier circuit that is included in the light receiver according to a correctness of the logic signal, by a digital processor of the light receiver;
(j) determining, by a signal processing circuit of the digital processor of the light receiver, whether or not the logic signal distorts such that the number of pulse waves counted by the counter circuit is incorrect, in response to determining that the logic signal does not distort such that the number of pulse waves counted by the counter circuit is incorrect, performing the process (o), and in response to determining that the logic signal distorts such that the number of pulse waves counted by the counter circuit is incorrect, controlling the gain amplifier circuit to multiply the voltage of the analog voltage signal by a gain for compensating the voltage of the analog voltage signal and then sequentially performing the processes (k) to (o);
(k) transmitting the analog voltage signal that is compensated from the gain amplifier circuit to the analog-digital converter by the processor circuit of the light receiver;
(l) converting, by the analog-digital converter, the analog voltage signal that is compensated into the digital voltage signal that is compensated;
(m) outputting, by the logic control circuit, the logic signal that is compensated to the counter circuit according to the digital voltage signal that is compensated;
(n) counting, by the counter circuit of the light receiver, a correct number of pulse waves according to the logic signal that is compensated;
(o) determining, by the signal processing circuit of the digital processor of the light receiver, whether or not 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, in response to determining that the energy of the photocurrent is not decreased, sequentially performing processes (p) to (s), and in response to determining that the energy of the photocurrent decreases, 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 and then sequentially performing processes (p) to (s);
(p) outputting, by the signal processing circuit of the digital processor of the light receiver, logic levels of the logic signal to a finite state machine included in the digital processor of the light receiver;
(q) determining, by the finite state machine of the digital processor of the light receiver, whether the logic levels of the logic signal are correctly determined by the counter circuit;
(r) storing temporarily the logic levels that overflow by an overflow unit included in the light receiver 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;
(s) determining, by the control circuit, according to the correct number of pulse waves, 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.