TWI783389B - Light-emitting diode string control system with carrier wave identification function and method of signal identification the same - Google Patents

Abstract

A light-emitting diode string control system with carrier wave identification function includes a control module, a power capacitor and a light-emitting diode string. The control module switches the DC voltage to a carrier signal through a power switch according to a light-emitting command, and the power capacitor performs a capacitive charge-discharge on the carrier signal to generate a capacitive charge-discharge signal. The light-emitting diode string includes at least one light-emitting diode module, the at least one light-emitting diode module identifies that a charge-discharge characteristics of the capacitive charge-discharge signal belong to a first logic, a second logic, or a latch indication, and generates a driving command for controlling a light-emitting behavior of the light-emitting diode string according to the first logic, the second logic, and the latch indication.

Description

Light-emitting diode light string control system with carrier identification function and its signal identification method

The invention relates to a light-emitting diode string control system and a signal identification method thereof, in particular to a light-emitting diode light string control system with a carrier identification function and a signal identification method thereof.

Since the application of light-emitting diodes is becoming more and more popular, and its manufacturing cost is getting lower and lower, the application of light-emitting diodes in lighting or display is becoming more and more extensive. Correspondingly, there are more and more ways to operate and control the light-emitting behavior of light-emitting diodes. In the application of the light-emitting diode light string, it is necessary to set the light-emitting behavior for each light-emitting diode in order to make the light-emitting diode light string produce visual effects. Therefore, a controller must be used to control each light-emitting diode separately, and each controller must also have the function of identifying a signal, so as to determine whether the signal is a specific light-emitting command.

Among them, since most of the carrier signals received by the existing light-emitting diode strings are high-power and high-frequency switching signals, it is easy to affect the stability of signal recognition due to the interference of high-frequency noise. In this way, it is necessary to use a relatively high-precision identification circuit, or to have a device that is more resistant to noise interference. Components can increase the stability of signal recognition. However, such components or circuits are generally expensive and their operation methods are relatively complicated.

Therefore, how to design a light-emitting diode light string control system with carrier recognition function and its signal recognition method, so as to easily and accurately identify the carrier signal and enable the light-emitting diode light string to perform the lighting behavior correctly, is the subject of this project. It is a major topic of research that creators want to do.

In order to solve the above problems, the present invention provides a light emitting diode string control system with carrier identification function to overcome the problems of the prior art. The light-emitting diode string control system includes a control module, a power capacitor and a light-emitting diode string. The control module switches the DC voltage into a carrier signal through the power switch according to the lighting command. The power capacitor is coupled to the output end of the control module, and performs capacitive charge and discharge on the carrier signal to generate capacitive charge and discharge signals. The light emitting diode string is coupled to the power capacitor and includes at least one light emitting diode module. At least one light-emitting diode module recognizes that the charging and discharging characteristics of the capacitive charging and discharging signal belong to the first logic, the second logic, or the latching instruction, and generates the drive corresponding to the carrier signal according to the first logic, the second logic, and the latching instruction Order. Wherein, the driving command is used to control the light-emitting behavior of the light-emitting diode string.

In order to solve the above-mentioned problems, the present invention provides a signal identification method used in a light-emitting diode string control system to overcome the problems in the prior art. The signal identification method includes the following steps: (a) switching the DC voltage into a carrier signal according to the lighting command. (b) Capacitively charge and discharge the carrier signal to generate a capacitive charge and discharge signal. (c) identifying the charging and discharging characteristics of the capacitive charging and discharging signal belongs to the first logic, Second logical OR latch indication. (d) Generate a driving command corresponding to the carrier signal according to the first logic, the second logic and the latch instruction, so as to control the light-emitting behavior of the light-emitting diode string.

The main purpose and effect of the present invention are that the power capacitor performs capacitive charge and discharge on the carrier signal to generate a capacitive charge and discharge signal, and the light emitting diode module is used to identify the charge and discharge characteristics of the capacitive charge and discharge signal. In this way, the circuit elements are simple, the operation is easy, and it is easy to accurately identify the carrier signal and perform the lighting behavior correctly.

In order to further understand the technology, means and effects that the present invention adopts to achieve the predetermined purpose, please refer to the following detailed description and accompanying drawings of the present invention. It is believed that the purpose, characteristics and characteristics of the present invention can be obtained from this in depth and For specific understanding, however, the accompanying drawings are provided for reference and illustration only, and are not intended to limit the present invention.

100: LED light string control system

1: rectifier

2: Control module

20: Power switch

22: Controller

C: power capacitor

3: LED light string

30: Light emitting diode module

32: light emitting diode

34: Detection circuit

36: Logic circuit

38: Controller

40: filter circuit

Vin: input voltage

Vdc: DC voltage

Cl: luminous command

Cd: drive command

Scr: carrier signal

Scd: capacitive charge and discharge signal

Sc: control signal

Slg: logic signal

Slg1~Slg3: the first logic signal~the third logic signal

V1~V3: first threshold~third threshold

V: predetermined threshold

H: the first voltage level

L: Second voltage level

0: first logic

1: second logic

LK: Latch indication

Fig. 1 is the circuit block diagram of the light-emitting diode light string control system with carrier identification function of the present invention; Fig. 2 is the circuit block diagram of the light-emitting diode module of the present invention; Fig. 3A is the present invention using a predetermined threshold to identify charging and discharging Characteristic waveform diagram; FIG. 3B is the waveform diagram of the present invention using the time width to identify the charging and discharging characteristics;

Hereby, the technical content and detailed description of the present invention are described as follows in conjunction with the drawings: Please refer to FIG. 1 , which is a circuit block diagram of an LED light string control system with carrier identification function according to the present invention. The LED light string control system 100 receives an input voltage Vin through an input terminal, and the LED light string control system 100 includes a rectifier 1 , a control module 2 , a power capacitor C and a LED light string 3 . The control module 2 is coupled to the rectifier 1 and the LED string 3 , and the power capacitor C is coupled between the control module 2 and the LED string 3 . The rectifier 1 rectifies the AC input voltage Vin into a DC voltage Vdc, and the control module 2 switches the DC voltage Vdc into a carrier signal Scr according to an external lighting command Cl. The power capacitor C is coupled to the output end of the control module 2, and performs capacitive charge and discharge on the carrier signal Scr to generate a capacitive charge and discharge signal Scd. The LED lamp string 3 is coupled to the power capacitor C, and the LED lamp string 3 includes at least one LED module 30 . The light emitting diode module 30 includes at least one light emitting diode 32 , and controls the light emitting behavior of the light emitting diode 32 in the light emitting diode string 3 according to the carrier signal Scr. Wherein, when there are multiple light emitting diode modules 30 (in this embodiment, a plurality is illustrated), the light emitting diode modules 30 may be coupled in series or in parallel (not shown in the figure). It is worth mentioning that in an embodiment of the present invention, the LED light string control system 100 may not include the rectifier 1 , and the input voltage Vin received by the LED light string control system 100 is the DC voltage Vdc. Alternatively, the rectifier 1 can be replaced by a DC converter. The DC converter receives a DC input voltage Vin and converts the input voltage Vin into a DC voltage Vdc.

The control module 2 includes a power switch 20 and a controller 22 , and the power switch 20 is coupled between the rectifier 1 and the power capacitor C. The controller 22 is coupled to the control terminal of the power switch 20, and provides a control signal Sc to control the power switch 22 to be turned on or off according to the lighting command Cl, so as to switch the DC voltage Vdc to the carrier wave by controlling the power switch 22 to be turned on or off. Signal Scr. Wherein, the controller 22 may not include a conventional light emitting signal generator inside, and only controls the on or off of the power switch 22 to generate the carrier signal Scr with high level voltage and low level voltage change.

Furthermore, since the carrier signal Scr is mostly composed of pulse waves with different widths, the widths represent specific logic meanings. Because the pulse waves with different widths are affected by the charging and discharging of the power capacitor C, different charging and discharging characteristics will be produced. Therefore, the light emitting diode module 30 is designed to identify the charging and discharging characteristics of the capacitive charging and discharging signal Scd belonging to the first logic (such as but not limited to logic "0") and the second logic (such as but not limited to logic "1") Or a latching instruction (usually at the end of a pulse wave, used to indicate that the corresponding light-emitting diode module 30 can perform a latching action), and generate a corresponding The driving command of the carrier signal Scr is used to control the light-emitting behavior of the light-emitting diode module 30 (light-emitting diode 32 ). Wherein, the driving command may include at least one of address data and luminous data, which can be selectively matched according to actual needs (for example, only luminous data, or both). The address data mainly designates at least one of the light emitting diode modules 30 , and when the light emitting diode modules 30 are odd, the address data designates the only light emitting diode module 30 . When there are multiple light emitting diode modules 30 , the address data can be designated as one or more of the plurality of light emitting diode modules 30 . The luminous data is to specify the luminous behavior of the corresponding light-emitting diodes 32 in the light-emitting diode module 30 . When the number of light emitting diode modules 30 is singular, the luminous data specifies the light emitting behavior of the light emitting diodes 32 in the only light emitting diode module 30 . When there are multiple light emitting diode modules 30 , the luminous data can be specified as the light emitting behavior of the light emitting diodes 32 in one or more of the plurality of light emitting diode modules 30 .

Please refer to FIG. 2 which is a circuit block diagram of the light-emitting diode module of the present invention, and refer to FIG. 1 for the combination. In addition to at least one light emitting diode 32 , the light emitting diode module 30 further includes a detection circuit 34 , a logic circuit 36 and a controller 38 . The detection circuit 34 is coupled to the power capacitor C and detects the capacitive charge and discharge signal Scd to generate a logic signal Slg according to the charge and discharge characteristics of the capacitive charge and discharge signal Scd. The logic circuit 36 is coupled to the detection circuit 34, and identifies the logic signal Slg as belonging to the first logic, the second logic, or the latch indication, so as to generate the driving command Cd correspondingly. Among them, the logic signal Slg can include multiple logic groups (such as but not limited to "1011"), the logic circuit 36 recognizes it as "1011", and uses its logical combination to generate a corresponding driving command Cd. The controller 38 is coupled to the logic circuit 36 and the light emitting diodes 32, and receives the driving command Cd to store the driving command Cd in an internal memory unit (not shown). Thereby, the controller 38 can control the light emitting behavior of the light emitting diode 32 according to the driving command Cd. When there are plural LED modules 30, since the driving command Cd of each LED module 30 may be different, the overall lighting behavior of the LED lamp string 3 may produce, for example but not limited to Sequential lighting, sequential flashing and other changes.

Furthermore, the LED module 30 includes at least two identification methods for charging and discharging characteristics. One of them is that the light-emitting diode module 30 uses a predetermined threshold to identify the charging and discharging characteristics, and the other is that the light-emitting diode module 30 uses a time width to identify the charging and discharging characteristics. When using a predetermined threshold to identify the charging and discharging characteristics, the detection circuit 34 is designed to compare the magnitude of the capacitive charging and discharging signal Scd with the threshold. Specifically, the detection circuit 34 sets a first threshold, a second threshold, and a third threshold, and the thresholds are the first threshold, the second threshold, and the third threshold in descending order. When the voltage value of the capacitive charging and discharging signal Scd triggers the first threshold, the second threshold and the third threshold, the detection circuit 34 correspondingly generates a first logic signal, a second logic signal and a third logic signal (the sum of which is logic signal Slg). According to the first logic signal, the second logic signal and the third logic signal, the logic circuit 36 identifies that the signal belongs to the first logic, the second logic or the latch instruction. For example but not limited to, when the first logic signal, the second logic signal and the third logic signal appear in sequence within a specific time, it can be judged that the waveform of the capacitive charge and discharge signal Scd refers to a latch instruction (according to this analogy).

When using the time width to identify the charging and discharging characteristics, the detection circuit 34 is designed to generate the charging and discharging time width of the capacitive charging and discharging signal Scd, which is exactly the same voltage when the signal is discharged and charged. Specifically, the detection circuit 34 sets a predetermined threshold, and discharges to less than From being equal to the predetermined threshold to being charged to be greater than or equal to the predetermined threshold, a corresponding logic signal Slg is generated. The logic circuit 36 judges that the signal belongs to the first logic, the second logic, or the latch instruction according to the duration of the signal in the logic signal Slg. For example, but not limited to, the one with the longest maintained time width can be judged that the waveform of the capacitive charge and discharge signal Scd refers to the latch indication (and so on).

Referring again to FIG. 2, each light emitting diode module 30 further includes a filter circuit 40, and if it is an analog filter, the filter circuit 40 is coupled between the detection circuit 34 and the power capacitor C, and if it is a digital filter, then The filter circuit 40 is coupled between the detection circuit 34 and the logic circuit 36 . Since there are two implementations, they are shown with dashed lines. Wherein, the filter circuit 40 is used for noise filtering of the capacitive charging and discharging signal Scd. Specifically, since the capacitive charging and discharging signal Scd is a high-power signal, and the power switch 20 is switching at high frequency, the capacitive charging and discharging signal Scd will generate more burrs or switching surges. If there is no filter circuit 40 to filter out the noise of the capacitive charge and discharge signal Scd, the burr or switching surge will affect the detection accuracy of the detection circuit 34 for the capacitive charge and discharge signal Scd. Therefore, using the filter circuit 40 to perform noise filtering on the capacitive charging and discharging signal Scd is a preferred implementation of the LED light string control system 100 .

Please refer to FIG. 3A , which is a waveform diagram of the present invention using predetermined thresholds to identify charging and discharging characteristics, and refer to FIGS. 1-2 for complex cooperation. In Fig. 3A, Scd is the capacitive charge and discharge signal, V1~V3 are the first threshold~the third threshold respectively, Slg is the logic signal, Slg1~Slg3 are the first logic signal~the third logic signal respectively, Cd is the drive command , and "0", "1", and "LK" are respectively the first logic, the second logic, and the latch indication. When the voltage value of the capacitive charging and discharging signal Scd is lower than the first threshold V1, the second threshold V2, and the third threshold V3, the detection circuit 34 generates the first logic signal Slg1, the second logic signal Slg2, and the third logic signal respectively. Signal Slg3. The logic circuit 36 generates the first logic “0” according to the logic signal Slg having only the first logic signal Slg1, and generates the first logic “0” according to the logic signal including the first logic signal Slg1 and the second logic signal Slg2. The logic signal Slg generates a second logic "1". When the logic signal Slg includes the first logic signal Slg1 to the third logic signal Slg3, it means that it is a latch indication “LK”. The corresponding controller 38 takes the combination of the logic “0” and “1” as the driving command Cd and stores it in the internal memory unit (not shown). In this way, the carrier signal Scr can be accurately identified and the lighting behavior can be performed correctly.

It is worth mentioning that, in an embodiment of the present invention, the method of using the predetermined threshold to identify the charging and discharging characteristics is not limited to the above method. For example, any method of judging a logic signal by using a set voltage threshold (such as but not limited to positive edge or negative edge trigger) should be included in the scope of this embodiment. In addition, the logic “0” and the logic “1” can be interchanged (for example, the logic circuit 36 generates the first logic “1” according to the logic signal Slg which only has the first logic signal Slg1, which is not limited to logic “0”) . In addition, in an embodiment of the present invention, the latch indication “LK” can be a longer discharge of the capacitive charge and discharge signal Scd or the potential of the latch indication “LK” is a higher potential for a longer time.

Please refer to FIG. 3B , which is a waveform diagram of the present invention using the time width to identify the characteristics of charge and discharge, and refer to FIGS. 1-3A in combination. In FIG. 3B, Scd is a capacitive charge and discharge signal, V is a predetermined threshold, Slg is a logic signal, Cd is a drive command, and "0", "1", and "LK" are respectively the first logic, the second logic, Latch indication. When the capacitive charge and discharge signal Scd is discharged to be equal to or less than the predetermined threshold V, the logic signal Slg changes to the first voltage level H (ie high level), and when the capacitive charge and discharge signal Scd is charged to be greater than or equal to the predetermined threshold V , the logic signal Slg changes to the second voltage level L (ie low level). The logic circuit 36 judges according to the time width of the logic signal Slg at the first voltage level that the signal belongs to the first logic “0”, the second logic “1” or the latch indication “LK”. When the time width of the logic signal Slg at the first voltage level is short, it is judged as the first logic “0”, and when the time width of the logic signal Slg at the first voltage level is long, it is judged as the second logic "1". When the time width of the logic signal Slg at the first voltage level is the longest, it means that it is a latch indication “LK”. The corresponding controller 38 will The permutation and combination of logic "0" and "1" of is used as the driving command Cd, and is stored in the internal memory unit (not shown). In this way, the carrier signal Scr can be accurately identified and the lighting behavior can be performed correctly.

It is worth mentioning that, in an embodiment of the present invention, the method of using the time width to identify the charging and discharging characteristics is not limited to the above method. All methods for judging logic signals by using the calculation time width should be included in the scope of this embodiment. In addition, the widths corresponding to logic "0" and logic "1" can also be reversed.

Please refer to FIG. 4 , which is a flow chart of the signal identification method used in the light-emitting diode string control system of the present invention. Refer to FIGS. 1-3B for complex cooperation. The signal identification method includes switching the DC voltage into a carrier signal according to a lighting command (S100). A preferred implementation method is to use the controller 22 to provide the control signal Sc to control the power switch 22 to be turned on or off according to the lighting command Cl, so as to switch the DC voltage Vdc into a carrier signal by controlling the power switch 22 to be turned on or off. Scr. Then, perform capacitive charge and discharge on the carrier signal to generate a capacitive charge and discharge signal ( S120 ). A preferred implementation method is that the power capacitor C is used to capacitively charge and discharge the carrier signal Scr to generate the capacitive charge and discharge signal Scd. Then, identifying the charging and discharging characteristics of the capacitive charging and discharging signal belongs to the first logic, the second logic or the latch indication ( S140 ). A preferred embodiment thereof is to utilize the light emitting diode module 30 to identify that the charge and discharge characteristics of the capacitive charge and discharge signal Scd belong to the first logic, the second logic or the latch indication. Specifically, the detection of the capacitive charge and discharge signal Scd can be used to generate the logic signal Slg according to the charge and discharge characteristics of the capacitive charge and discharge signal Scd, and then the logic circuit 36 is used to identify the logic signal Slg as belonging to the first logic, the second logic or Latch indication.

Wherein, the light-emitting diode module 30 includes at least two identification methods for charging and discharging characteristics. One of them is that the light-emitting diode module 30 uses a predetermined threshold to identify the charging and discharging characteristics, and the other is that the light-emitting diode module 30 uses a time width to identify the charging and discharging characteristics. When using predetermined thresholds to identify charging and discharging characteristics, it is preferable to compare the capacitive charging and discharging signal Scd with the first threshold V1, the second threshold V2 and the first threshold V1. The logic signal Slg is generated correspondingly to the three thresholds V3. When using the time width to identify the charge and discharge characteristics, preferably, the logic signal Slg can be generated correspondingly according to the capacitive charge and discharge signal Scd from discharging to less than or equal to the predetermined threshold V to charging to greater than or equal to the predetermined threshold V. Then, according to the first logic, the second logic and the latch instruction, a driving command corresponding to the carrier signal is generated to control the lighting behavior of the light emitting diode string ( S160 ). A preferred implementation method thereof is to use the logic circuit 36 to generate the driving command Cd corresponding to the carrier signal Scr according to the first logic, the second logic and the latch instruction. Then, the drive command Cd is stored in an internal memory unit (not shown) by the controller 38 . Thereby, after all the LED modules 30 inside the LED lamp string 3 have latched the driving command Cd, the light emitting behavior of the LED lamp string 3 can be controlled by the driving command Cd.

In order to prevent ground burrs or switching surges generated by the capacitive charge and discharge signal Scd from affecting the detection accuracy of the detection circuit 34 on the capacitive charge and discharge signal Scd, after step (S120), the capacitive charge and discharge signal can be Perform noise filtering (S180). A preferred embodiment is to use the filter circuit 40 to filter out the noise of the capacitive charging and discharging signal Scd so as not to affect the detection accuracy of the detecting circuit 34 on the capacitive charging and discharging signal Scd.

However, the above description is only a detailed description and drawings of preferred embodiments of the present invention, but the features of the present invention are not limited thereto, and are not intended to limit the present invention. The entire scope of the present invention should be applied for as follows The scope of the patent shall prevail, and all embodiments that conform to the spirit of the patent scope of the present invention and its similar changes shall be included in the scope of the present invention, and any person familiar with the art can easily think of it in the field of the present invention Changes or modifications can be covered by the scope of the following patents in this case.

100: LED light string control system

1: rectifier

2: Control module

20: Power switch

22: Controller

C: power capacitor

3: LED light string

30: Light emitting diode module

32: light emitting diode

Vin: input voltage

Vdc: DC voltage

Cl: luminous command

Scr: carrier signal

Scd: capacitive charge and discharge signal

Sc: control signal

Claims (10)

A light-emitting diode light string control system with a carrier identification function, and the light-emitting diode light string control system includes: a control module, the control module switches a DC voltage through a power switch to A carrier signal; a power capacitor coupled to the output terminal of the control module, and the power capacitor performs a capacitive charge and discharge on the carrier signal to generate a capacitive charge and discharge signal; and a light emitting diode lamp The string is coupled to the power capacitor, and the light-emitting diode string includes at least one light-emitting diode module; the at least one light-emitting diode module recognizes that a charge-discharge characteristic of the capacitive charge-discharge signal belongs to a first A logic, a second logic, or a latch instruction, and the at least one light-emitting diode module generates a driving command corresponding to the carrier signal according to the first logic, the second logic, and the latch instruction; wherein, The driving command is used to control the light-emitting behavior of the light-emitting diode string, and the at least one light-emitting diode module generates a logic signal according to the charge-discharge characteristic of the capacitive charge-discharge signal; and the at least one light-emitting diode module generates a logic signal; The light-emitting diode module uses a predetermined threshold to identify the charging and discharging characteristics; the at least one light-emitting diode module compares the capacitive charging and discharging signal with a first threshold, a second threshold and a third threshold corresponding to generating the logic signal; or wherein the at least one light-emitting diode module uses a time width to identify the charging and discharging characteristics, and the at least one light-emitting diode module is discharged to be less than or equal to a predetermined threshold according to the capacitive charging and discharging signal The logic signal is generated correspondingly until the battery is charged to be greater than or equal to the predetermined threshold. The light-emitting diode string control system according to claim 1, wherein the at least one light-emitting diode module includes: A detection circuit, coupled to the power capacitor, and generating the logic signal according to the charge and discharge characteristics of the capacitive charge and discharge signal; a logic circuit, coupled to the detection circuit, and identifying that the logic signal belongs to the first logic , the second logic or the latch instruction to generate the drive command correspondingly; a controller, coupled to the logic circuit and a light-emitting diode, and receives the drive command to control the light-emitting diode accordingly The glowing behavior. The light-emitting diode light string control system according to claim 2, wherein the at least one light-emitting diode module further includes: a filter circuit coupled to the detection circuit; wherein the filter circuit charges and discharges the capacitive The signal is subjected to a noise filtering. The light-emitting diode light string control system as described in claim 1, wherein the driving command includes at least one of an address data and a light-emitting data, and the address data specifies at least one of the at least one light-emitting diode module One, the luminescence data specifies the luminescence behavior of at least one of the at least one light emitting diode module. The light-emitting diode string control system as described in claim 1, wherein the control module includes: a power switch receiving the DC voltage and coupled to the power capacitor; and a controller coupled to the power switch, and receiving the lighting command; wherein, the controller provides a control signal to control the power switch to be turned on or off according to the lighting command, so as to switch the DC voltage to the carrier signal by controlling the power switch to be turned on or off. The light emitting diode string control system according to claim 1, wherein the at least one light emitting diode module is plural, and the light emitting diode modules are coupled in series or in parallel. A signal identification method for a light-emitting diode string control system, the signal identification method includes the following steps: switching a DC voltage into a carrier signal according to a lighting command; performing a capacitive charge and discharge on the carrier signal and correspondingly Generate a capacitive charge and discharge signal; identify a charge and discharge characteristic of the capacitive charge and discharge signal as belonging to a first logic, a second logic or a latch indication; according to the first logic, the second logic and the lock Store instructions to generate a driving command corresponding to the carrier signal, so as to control a light-emitting behavior of a light-emitting diode string according to the driving command; and generate a logic signal according to the charging and discharging characteristics of the capacitive charging and discharging signal; compare the The capacitive charge and discharge signal corresponds to a first threshold, a second threshold and a third threshold to generate the logic signal; or according to the capacitive charge and discharge signal from discharge to less than or equal to a predetermined threshold to charge to greater than or equal to the capacitive charge and discharge signal The logic signal is generated correspondingly to a predetermined threshold. The signal identification method as described in Claim 7 further includes the following steps: identifying that the logic signal belongs to the first logic, the second logic or the latch instruction, so as to generate the driving command accordingly. The signal identification method as described in claim item 7 further includes the following steps: performing noise filtering on the capacitive charge and discharge signal. The signal identification method as described in claim item 7 further includes the following steps: providing a control signal to control the turn-on or turn-off of a power switch according to the light-emitting command, so as to control the turn-on or turn-off of the power switch to reduce the DC voltage Switch to the carrier signal.

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