Signal modulation method and signal rectification and modulation device

1. A signal modulation method for a receiving-end module of an induction type power supply system, the signal modulation method comprising:

configuring a plurality of modulation periods corresponding to a modulation signal;

comparing a voltage on a first terminal or a second terminal of an induction coil of the receiving-end module with a reference voltage, to generate a comparison result; and

determining time points where the plurality of modulation periods start or stop according to the comparison result;

wherein each of the plurality of modulation periods starts when the first terminal of the induction coil is at a first voltage level and ends when the first terminal of the induction coil is at the first voltage level wherein the voltage on the first terminal of the induction coil is compared with the reference voltage, and the step of determining the time points where the plurality of modulation periods start or stop according to the comparison result comprises: configuring a predetermined time corresponding to each of the plurality of modulation periods; determining a voltage level of the first terminal of the induction coil according to the comparison result and determining whether to start a modulation period corresponding to the first terminal among the plurality of modulation periods accordingly, when an indication of signal modulation is received; starting a timer when the modulation period starts; and determining the voltage level of the first terminal of the induction coil according to the comparison result and determining whether to stop the modulation period accordingly, when the timer expires on the predetermine time.

2. The signal modulation method of claim 1 , wherein the step of determining the voltage level of the first terminal of the induction coil according to the comparison result and determining whether to start the modulation period accordingly when the indication of signal modulation is received comprises:

determining a time point where the voltage level of the first terminal of the induction coil falls to a low voltage level lower than the reference voltage via the comparison result; and

starting the modulation period at the time point, so that the first terminal of the induction coil starts to undergo modulation in the low voltage level.

3. The signal modulation method of claim 1 , wherein the step of determining the voltage level of the first terminal of the induction coil according to the comparison result and determining whether to stop the modulation period accordingly when the timer expires on the predetermined time comprises:

determining a time point where the voltage level of the first terminal of the induction coil falls to a low voltage level lower than the reference voltage via the comparison result; and

stopping the modulation period at the time point, so that the first terminal of the induction coil stops undergoing modulation in the low voltage level.

4. The signal modulation method of claim 1 , wherein the voltage on the first terminal of the induction coil is compared with the reference voltage, and the step of determining the time points where the plurality of modulation periods start or stop according to the comparison result comprises:

configuring a predetermined time corresponding to each of the plurality of modulation periods;

determining a voltage level of the first terminal of the induction coil according to the comparison result in order to determine a voltage level of the second terminal of the induction coil, and determining whether to start a modulation period corresponding to the second terminal among the plurality of modulation periods accordingly, when an indication of signal modulation is received;

starting a timer when the modulation period starts; and

determining the voltage level of the first terminal of the induction coil according to the comparison result in order to determine the voltage level of the second terminal of the induction coil, and determining whether to stop the modulation period accordingly, when the timer expires on the predetermined time.

5. The signal modulation method of claim 4 , wherein the step of determining the voltage level of the first terminal of the induction coil according to the comparison result in order to determine the voltage level of the second terminal of the induction coil and determining whether to start the modulation period accordingly when the indication of signal modulation is received comprises:

determining a time point where the voltage level of the first terminal of the induction coil rises to a high voltage level higher than the reference voltage via the comparison result;

determining that the second terminal of the induction coil is in a low voltage level when the first terminal of the induction coil is in the high voltage level; and

starting the modulation period at the time point, so that the second terminal of the induction coil starts to undergo modulation in the low voltage level.

6. The signal modulation method of claim 4 , wherein the step of determining the voltage level of the first terminal of the induction coil according to the comparison result in order to determine the voltage level of the second terminal of the induction coil and determining whether to stop the modulation period accordingly when the timer expires on the predetermined time comprises:

determining a time point where the voltage level of the first terminal of the induction coil rises to a high voltage level higher than the reference voltage via the comparison result;

determining that the second terminal of the induction coil is in a low voltage level when the first terminal of the induction coil is in the high voltage level; and

stopping the modulation period at the time point, so that the second terminal of the induction coil stops undergoing modulation in the low voltage level.

7. A signal rectification and modulation device for a receiving-end module of an induction type power supply system, the receiving-end module comprising an induction coil for receiving power from a supplying-end module of the induction type power supply system, the rectification and modulation device comprising:

a first rectification transistor, coupled between a first terminal of the induction coil and a ground terminal, for performing rectification on the first terminal of the induction coil;

a second rectification transistor, coupled between a second terminal of the induction coil and the ground terminal, for performing rectification on the second terminal of the induction coil;

a first rectification control module, coupled to the first terminal and the second terminal of the induction coil and the first rectification transistor, for outputting a first rectification control signal to control the first rectification transistor to perform rectification according to voltages on the first terminal and the second terminal of the induction coil;

a second rectification control module, coupled to the first terminal and the second terminal of the induction coil and the second rectification transistor, for outputting a second rectification control signal to control the second rectification transistor to perform rectification according to the voltages on the first terminal and the second terminal of the induction coil;

a first modulation control module, coupled to the first terminal of the induction coil, for performing signal modulation on the first terminal;

a second modulation control module, coupled to the second terminal of the induction coil, for performing signal modulation on the second terminal;

a reference voltage generator, for generating a reference voltage;

a comparator, coupled to the reference voltage generator and the first rectification control module or the second rectification control module, for comparing the reference voltage with a coil voltage of the induction coil, to generate a comparison result; and

a processor, coupled to the comparator, the first rectification control module, the second rectification control module, the first modulation control module and the second modulation control module, for controlling the first modulation control module and the second modulation control module to alternately perform modulation on the first terminal and the second terminal of the induction coil according to the comparison result;

wherein the processor controls the second rectification control module to turn off the second rectification transistor to interrupt the rectification on the second terminal of the induction coil when controlling the first modulation control module to perform modulation on the first terminal of the induction coil, and controls the first rectification control module to turn off the first rectification transistor to interrupt the rectification on the first terminal of the induction coil when controlling the second modulation control module to perform modulation on the second terminal of the induction coil.

8. The signal rectification and modulation device of claim 7 , wherein the comparator comprises:

a first input terminal, for receiving a gate voltage of a rectification control transistor of the first rectification control module or the second rectification control module, wherein the gate voltage corresponds to the coil voltage of the induction coil;

a second input terminal, for receiving the reference voltage; and

an output terminal, for outputting the comparison result to the processor according to levels of the gate voltage and the reference voltage.

9. The signal rectification and modulation device of claim 7 , wherein the processor further executes the following step to perform the signal modulation:

determining time points where a plurality of modulation periods start or stop according to the comparison result.

10. The signal rectification and modulation device of claim 7 , wherein the processor is determined to be turned on or not according to the comparison result of the comparator.