Light detecting circuit, laser distance measuring circuit and light detecting method
View Patent ↗A light detecting circuit includes a power source circuit, an optoelectronic component, a switch and a Trans Impedance Amplifier (TIA) circuit. The power source circuit provides an electric signal. When the optoelectronic component is biased at a bias voltage, the optoelectronic component generates a corresponding current according to the received light density. The switch has a trigger receiver. After the trigger receiver receives a trigger signal, the switch turns on and the optoelectronic component is biased at the bias voltage. The TIA circuit transforms the corresponding current to a corresponding voltage and then calculates the corresponding voltage to obtain the light density.
1. A light detecting circuit comprising:
a power circuit providing a power signal;
an optoelectronic device generating a corresponding current according to the amplitude of a received light signal; and
a switching circuit comprising:
a trigger receiver;
a first transistor comprising a first source, a first drain and a first gate, the first source connecting with the power circuit, the first drain connecting with the optoelectronic device;
a second transistor comprising a second source, a second drain and a second gate, the second source connecting with a ground terminal, the second gate connecting with the trigger receiver to receive a trigger signal;
a first resistance connected between the power circuit and the first gate; and
a second resistance connected between the first gate and the second drain, wherein the switching circuit is turned on when the trigger receiver receiving the trigger signal and the switching circuit transmits the power signal to the optoelectronic device.
2. The light detecting circuit of claim 1 , wherein the power circuit further comprises a third resistance, a first capacitance and a second capacitance, the third resistance is connected between the first capacitance and the second capacitance, the first capacitance is connected between a voltage source of the power circuit and the ground terminal, and the second capacitance is connected between the switching circuit and the ground terminal.
3. The light detecting circuit of claim 1 , further comprising a transform impedance amplifier, wherein the transform impedance amplifier receives the corresponding current and transforms the corresponding current into a corresponding voltage.
4. The light detecting circuit of claim 3 , wherein the corresponding current is proportional to the corresponding voltage.
5. The light detecting circuit of claim 3 , wherein the corresponding voltage is proportional to the amplitude of the light signal.
6. The light detecting circuit of claim 1 further comprising a laser emitter to emit a laser beam, and a controlling terminal transmitting the trigger signal after a predetermined period the laser beam is emitted.
7. The light detecting circuit of claim 1 , wherein the optoelectronic device is an avalanche photo diode (APD).
8. A laser distance measuring circuit comprising:
a power circuit providing a power signal;
a laser emitter emitting a laser beam to a surface and reflected by the surface, and a controlling terminal transmits a trigger signal after a predetermined period the laser beam has been emitted;
an optoelectronic device generating a corresponding current according to the reflected laser beam;
a switching circuit comprising:
a trigger receiver;
a first transistor comprising a first source, a first drain and a first gate, the first source connected with the voltage source circuit, and the first drain connecting with the optoelectronic device;
a second transistor comprising a second source, a second drain and a second gate, the second source connecting with a ground terminal, and the second gate connecting with the trigger receiver to receive the trigger signal;
a first resistance connecting between the voltage source circuit and the first gate; and
a second resistance connecting between the first gate and the second drain,
wherein the switching circuit is turned on when the trigger receiver receives the trigger signal, and the switching circuit transmits the power signal to the optoelectronic device; and
a transform impedance amplifier receiving the corresponding current and transforming the corresponding current into a corresponding voltage to determine a distance between the surface and the laser emitter.
9. The laser distance measuring circuit of claim 8 , wherein the power circuit further comprises:
a third resistance, a first capacitance and a second capacitance, the third resistance connecting between the first capacitance and the second capacitance, the first capacitance connecting between a voltage source of the power circuit and the ground terminal, and the second capacitance connecting between the switching circuit and the ground terminal.
10. The laser distance measuring circuit of claim 8 , wherein the corresponding current is proportional to the corresponding voltage.
11. The laser distance measuring circuit of claim 8 , wherein the corresponding voltage is proportional to the distance.
12. The laser distance measuring circuit of claim 8 , wherein the optoelectronic device is an avalanche photo diode (APD).
13. A light detecting method applied to a light detecting circuit, comprising:
(a) providing a power signal generated by a power circuit to the light detecting circuit;
(b) applying an optoelectronic transforming device for generating a corresponding current according to the amplitude of a received light signal; and
(c) receiving a trigger signal from a switch with a trigger receiver to turn on the switch, and the switch transmits the power signal to the optoelectronic transforming device, wherein the switch comprises:
a first turn-on device comprising a first connector, a second connector and a third connector, the first connector connects with the power circuit, and the second connector connecting with the optoelectronic transforming device;
a second turn-on device comprising a fourth connector, a fifth connector and a sixth connector, the fourth connector connects with a ground terminal, the sixth connector connects with the trigger receiver for receiving the trigger signal;
a first impedance connected between the power circuit and the third connector; and
a second impedance connected between the third connector and the fifth connector.
14. The light detecting method of claim 13 , wherein the corresponding current is direct proportional to the corresponding voltage.
15. The light detecting method of claim 13 , wherein the corresponding voltage is proportional to the amplitude of the received light signal.
16. The light detecting method of claim 13 , further comprising
outputting the trigger signal by a controlling terminal after a specific period of a laser beam emitter emitting a laser beam.
17. The light detecting method of claim 16 , wherein the trigger signal is a high voltage signal.