Light emitting diode light string control system and signal control method thereof

Abstract

The application discloses a light emitting diode (LED) lamp string control system and a signal control method thereof. The LED lamp string control system comprises a control module and an LED lamp string. The control module switches a direct current voltage into a light emitting driving signal according to a light emitting command, and the LED lamp string is coupled to the control module. The LED lamp string comprises at least one LED module, and the at least one LED module comprises a detection circuit, a logic circuit and an oscillator. The detection circuit detects the light emitting driving signal, and the logic circuit judges whether the light emitting driving signal belongs to a first logic signal, a second logic signal or a latch signal according to a maintaining width of a high level of the light emitting driving signal. The oscillator provides a frequency signal to the logic circuit according to the light emitting driving signal of the high level, so as to calculate the maintaining width.

Description

Technical Field

[0001] This invention relates to a light-emitting diode (LED) string control system and its signal control method, and more particularly to a light-emitting diode string control system and its signal control method for carrier wave control. Background Technology

[0002] With the increasing prevalence of LEDs and their decreasing manufacturing costs, their applications in lighting and displays are becoming more widespread. Consequently, there are also increasing methods for operating and controlling the light-emitting behavior of LEDs. In LED string applications, the lighting behavior of each LED needs to be set to achieve the desired visual effect. Therefore, individual controllers are required to control each LED, and each controller must have the ability to identify signals to determine whether a signal represents a specific lighting command.

[0003] However, the signals received by the controller must also be used to power its internal operation. Furthermore, the controller consumes a significant amount of power during signal recognition, causing the voltage level of this signal to gradually decrease. If the voltage level of this signal cannot maintain normal controller operation, the entire LED string will fail.

[0004] Therefore, how to design a control system for LED strings and its signal control method to avoid the failure of LED strings due to excessive power consumption by the controller is a major research topic that the creators of this project intend to study. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a light-emitting diode (LED) string control system for carrier control, overcoming the limitations of known technologies. The LED string control system includes a control module and an LED string. The control module switches a DC voltage to a light-emitting drive signal according to a light-emitting command, and the LED string is coupled to the control module. The LED string includes at least one LED module, and each LED module includes a detection circuit, a logic circuit, and an oscillator. The detection circuit generates a detection signal corresponding to the light-emitting drive signal. The logic circuit determines whether the first level belongs to a first logic signal, a second logic signal, or a latched signal based on the sustaining width of the detection signal at a first level. The oscillator enters sleep mode based on a sleep signal and provides a frequency signal based on the first level for the logic circuit to calculate the sustaining width. Alternatively, the logic circuit may provide a sleep signal based on the detection signal at a second level, or the oscillator may use the detection signal at the second level as the sleep signal.

[0006] To address the aforementioned problems, this invention provides a signal control method for LED strings, overcoming the limitations of known technologies. The signal control method includes the following steps: switching a DC voltage to a light-emitting drive signal according to a light-emitting command; generating a detection signal corresponding to the light-emitting drive signal; determining, based on the holding width of the detection signal at a first level, whether the first level belongs to a first logic signal, a second logic signal, or a latching signal; and providing a frequency signal based on the first level, and calculating the holding width using the frequency signal.

[0007] The main objective and benefit of this invention is to perform logic judgments using a high-level LED driving signal and to put the LED module into sleep mode when the LED driving signal is at a low-level voltage. Thus, when the LED driving signal is at a low level voltage, the LED module consumes almost no power, preventing the voltage level of the LED driving signal from dropping below the LED module's reset voltage due to excessive power consumption.

[0008] To gain a deeper understanding of the techniques, means, and effects employed by this invention to achieve its intended purpose, please refer to the following detailed description and accompanying drawings. It is believed that the purpose, features, and characteristics of this invention can be understood in a thorough and specific manner from these drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit the scope of this invention. Attached Figure Description

[0009] Figure 1 This is a circuit block diagram of the LED string control system for carrier control according to the present invention.

[0010] Figure 2 This is a circuit block diagram of the light-emitting diode module of the present invention;

[0011] Figure 3 The circuit waveform diagram of the LED string control system of the present invention is shown below; and

[0012] Figure 4 This is a flowchart of the signal control method for LED strings according to the present invention.

[0013] Explanation of symbols in the attached diagram:

[0014] 100 LED string control system;

[0015] 1. Rectifier;

[0016] 2. Control module;

[0017] 20 Power switches;

[0018] 22 Controllers;

[0019] 3. LED string lights;

[0020] 30 LED modules;

[0021] 32. Light-emitting diode;

[0022] 34. Detection circuit;

[0023] 36. Logic circuits;

[0024] 38. Oscillator;

[0025] 40. Filtering circuit;

[0026] Vin: Input voltage;

[0027] Vdc DC voltage;

[0028] Vr resets the voltage;

[0029] Cl command to emit light;

[0030] Sl light-emitting drive signal;

[0031] Sc control signal;

[0032] Ss detects signals;

[0033] SSP sleep signal;

[0034] Sck frequency signal;

[0035] Sf filter signal;

[0036] Sk latch completion signal;

[0037] Steps (S100) to (S220). Detailed Implementation

[0038] The technical content and detailed description of the present invention are explained below with reference to the accompanying drawings:

[0039] Please see Figure 1This is a circuit block diagram of the LED string control system for carrier control according to the present invention. The LED string control system 100 receives an input voltage Vin through an input terminal and includes a rectifier 1, a control module 2, and an LED string 3. The control module 2 is coupled to the rectifier 1 and the LED string 3, and the rectifier 1 rectifies the AC input voltage Vin into a DC voltage Vdc. The control module 2 receives the DC voltage Vdc and switches it to a carrier-type light-emitting drive signal Sl according to an externally provided light-emitting command C1. The LED string 3 is coupled to the control module 2 and includes at least one LED module 30 (multiple modules are shown in this embodiment, but it can be a single module). Each LED module 30 includes at least one LED 32, and the light-emitting behavior of the LED 32 is controlled according to the light-emitting drive signal Sl. When there are multiple LED modules 30, they can be connected in series or in parallel (not shown in the figure). It is worth mentioning that, in one embodiment of the present invention, the LED string control system 100 may not include the rectifier 1, and the input voltage Vin received by the LED string control system 100 is the DC voltage Vdc. Alternatively, the rectifier 1 can be replaced by a DC converter. The DC converter receives the DC input voltage Vin and converts the input voltage Vin into a DC voltage Vdc.

[0040] The control module 2 includes a power switch 20 and a controller 22, with the power switch 20 coupled between the rectifier 1 and the LED string 3. The controller 22 is coupled to the control terminal of the power switch 20 and provides a control signal Sc according to the light-emitting command C1 to control the power switch 22 to turn on or off, thereby switching the DC voltage Vdc to a light-emitting drive signal Sl by controlling the power switch 22 to turn it on or off. The controller 22 may not contain a traditional light-emitting signal generator; it only generates the light-emitting drive signal Sl, which changes between high-level and low-level voltages, by controlling the power switch 22 to turn it on or off.

[0041] Please see Figure 2 This is a circuit block diagram of the LED module of the present invention, for reference only. Figure 1 Each LED module 30 includes at least one LED 32, a detection circuit 34, a logic circuit 36, and an oscillator 38. The detection circuit 34 is coupled to the control module 2 and detects the light-emitting drive signal S1 to generate a detection signal Ss corresponding to the light-emitting drive signal S1. The logic circuit 36 ​​is coupled to the detection circuit 34 and determines whether to provide a sleep signal Ssp based on the detection signal Ss. The oscillator 38 is coupled to the logic circuit 36 ​​and enters sleep mode based on whether it receives the sleep signal Ssp.

[0042] Specifically, the detection circuit 34 can generate a detection signal Ss that is complementary to, but not limited to, the light-emitting driving signal Sl, or a detection signal Ss that is proportionally scaled to the light-emitting driving signal Sl, by detecting the light-emitting driving signal Sl. The logic circuit 36 ​​determines whether the first level belongs to a first logic signal (e.g., logic "0"), a second logic signal (e.g., logic "1"), or a latch signal based on the maintenance width of the detection signal Ss at the first level. The logic circuit 36 ​​provides a sleep signal Ssp based on the detection signal Ss at the second level (or, the oscillator 38 directly uses the detection signal Ss at the second level as the sleep signal Ssp), so as to save the power consumption of the light-emitting driving signal Sl at low level voltage by controlling the sleep of the oscillator 38, thereby avoiding excessive power consumption at low level voltage that falls below the reset voltage. When oscillator 38 does not receive the sleep signal Ssp, it provides a frequency signal Sck for logic circuit 36 ​​to calculate the sustain width. When oscillator 38 receives the sleep signal Ssp, it goes into sleep mode and does not provide the frequency signal Sck. When oscillator 38 is in sleep mode and does not provide the frequency signal Sck, internal circuits that operate using the frequency signal Sck (such as latch circuits and drive circuits) will also go into sleep mode due to the lack of a frequency signal. This significantly reduces the power consumption of the LED module 30.

[0043] When logic circuit 36 ​​determines that the holding width of the detection signal Ss at the first level is a latching signal, it notifies the LED module 30 to latch and memorize the aforementioned temporarily stored first and second logic signals as a drive command. Afterward, the LED module 30 can use this drive command to control the light-emitting behavior of its own LED 32. Taking the complementary nature of the light-emitting drive signal S1 and the detection signal Ss as an example, the first level (low level voltage) corresponds to the high level voltage of the light-emitting drive signal S1, and the second level (high level voltage) corresponds to the low level voltage of the light-emitting drive signal S1.

[0044] Furthermore, to reduce the construction cost of the LED string control system 100, it is typically implemented using LED modules 30 without power-off memory function. Because LED modules 30 with power-off memory function will reset and forget all settings and remembered drive commands when the received power (i.e., the light-emitting drive signal S1) is lower than the reset voltage (i.e., lower than the operating voltage required for internal operation). To avoid this situation, the LED string control system 100 typically tries to prevent the voltage level of the light-emitting drive signal S1 from falling below the reset voltage. However, the light-emitting drive signal S1 is typically a pulse voltage alternating between high and low voltage levels. If logic judgments are performed when the light-emitting drive signal S1 is at a low voltage level (i.e., judging the first logic signal, the second logic signal, and the latch signal), the LED module 30 is still working and consuming power. Therefore, it is easy for the voltage level of the light-emitting drive signal S1 to fall below the reset voltage due to excessive power consumption during the judgment process.

[0045] Therefore, the main objective and effect of this invention is to utilize the light-emitting drive signal S1 at a high voltage level for logic judgment, and to put the light-emitting diode module 30 into sleep mode when the light-emitting drive signal S1 is at a low voltage level. In this way, when the light-emitting drive signal S1 is at a low voltage level, the light-emitting diode module 30 consumes almost no power, thus avoiding a situation where excessive power consumption causes the voltage level of the light-emitting drive signal S1 to drop below the reset voltage of the light-emitting diode module 30.

[0046] See also Figure 2 Each LED module 30 further includes a filter circuit 40, which is coupled to the detection circuit 34. The filter circuit 40 can be coupled between the detection circuit 34 and the control module 2 to filter noise from the light-emitting drive signal S1. Alternatively, it can be coupled between the detection circuit 34 and the logic circuit 36 ​​to filter noise from the detection signal Ss. Specifically, since the light-emitting drive signal S1 is a high-power signal and the power switch 20 performs high-frequency switching, the light-emitting drive signal S1 will generate more jagged edges or switching spikes. If the filter circuit 40 does not filter noise from the light-emitting drive signal S1 or the detection signal Ss, the jagged edges or switching spikes will affect the accuracy of the logic circuit 36 ​​in determining the holding width of the detection signal Ss. It may even misinterpret a signal that should be a logic "0" or logic "1" as another signal. Therefore, using the filter circuit 40 to filter out noise from the light-emitting drive signal S1 or the detection signal Ss is a preferred implementation method for the LED string control system 100. Since the operation within the LED module 30 is low-voltage, consuming relatively little power, coupling the filter circuit 40 between the detection circuit 34 and the logic circuit 36 ​​is the optimal implementation method.

[0047] Please see Figure 3 The diagram shows the circuit waveforms of the LED string control system of this invention, in conjunction with other relevant documents. Figures 1-2 .exist Figure 3 In this diagram, Sl is the light-emitting drive signal, Ss is the detection signal, Sf is the filtered detection signal (hereinafter referred to as the filtered signal Sf), and Sk is the latch completion signal. Control module 2 switches the DC voltage Vdc to a carrier-type light-emitting drive signal Sl. The light-emitting drive signal Sl includes a high-level voltage and a low-level voltage, with the low-level voltage not lower than the reset voltage Vr. Within the light-emitting drive signal Sl, there is a relatively long high-level voltage segment, indicating that the previous carrier segment has been generated. The corresponding receiving LED module 30 can latch the drive command corresponding to the previous carrier segment. Detection circuit 34 detects the light-emitting drive signal Sl and generates a complementary detection signal Ss, while filtering circuit 40 filters the detection signal Ss to generate a slightly delayed filtered signal Sf.

[0048] When the detection signal Ss is at the second level (i.e., when the light-emitting drive signal Sl is at a low level voltage), the LED module 30 controls the oscillator 38 to go into sleep mode, causing most of the power-consuming circuits inside the LED module 30 to go into sleep mode, thus reducing power consumption when the light-emitting drive signal Sl is at a low level voltage. Therefore, the low level voltage is not consumed excessively and falls below the reset voltage Vr. When the detection signal Ss is at the first level (i.e., when the light-emitting drive signal Sl is at a high level voltage), the logic circuit 36 ​​uses the frequency signal Sck provided by the oscillator 38 to calculate the maintenance width Y (e.g., a wider width is judged as logic "1", and a narrower width as logic "0"). When the detection signal Ss is at its widest width (i.e., width X) at the first level, it is determined that this is a latch signal, and the previous filtered signal Sf is latched. Finally, after a short latching period, a latch completion signal Sk is issued to indicate that the latching action of the drive command has been completed. It is worth mentioning that, since the latch signal is usually maintained for a relatively long time, if it is represented by a low-level light-emitting drive signal Sl, the long judgment time will result in a longer power consumption time for the LED module 30, which may easily lead to the light-emitting drive signal Sl falling below the reset voltage Vr. Therefore, by setting the controller 22 to change the original low-level latch signal to a high-level latch signal (i.e., width X is the high-level voltage), this situation can be avoided.

[0049] Please see Figure 4 This is a flowchart of the signal control method for LED strings according to the present invention, and can be consulted in conjunction with other relevant documents. Figures 1-3The signal control method includes switching a DC voltage to a light-emitting drive signal according to a light-emitting command (S100). A preferred embodiment involves using a controller 22 to provide a control signal Sc according to the light-emitting command C1 to control the on / off state of a power switch 22, thereby switching the DC voltage Vdc to a light-emitting drive signal S1 by controlling the on / off state of the power switch 22. Then, a detection signal corresponding to the light-emitting drive signal is generated (S120). A preferred embodiment involves using a detection circuit 34 to detect the light-emitting drive signal S1 and generate a detection signal Ss corresponding to the light-emitting drive signal S1, where the detection signal Ss is, for example, but not limited to, complementary to the light-emitting drive signal S1, or a proportionally scaled light-emitting drive signal S1. Then, based on the maintenance width of the detection signal at a first level, it is determined whether the first level belongs to a first logic signal, a second logic signal, or a latching signal (S140). A preferred implementation is to use logic circuit 36 ​​to determine whether the first level belongs to a first logic signal (e.g., logic "0"), a second logic signal (e.g., logic "1"), or a latching signal based on the maintenance width of the detection signal Ss at the first level.

[0050] Then, a frequency signal is provided based on the first level, and a sustaining width is calculated using the frequency signal (S160). A preferred embodiment is that the oscillator 38 provides a frequency signal Sck based on the detection signal Ss of the first level (which may be notified by the detection circuit 34 or the logic circuit 36) for the logic circuit 36 ​​to calculate the sustaining width, to determine whether the first level of the detection signal Ss belongs to a first logic signal, a second logic signal, or a latching signal. Then, a sleep signal is provided based on the detection signal at the second level (S180). A preferred embodiment is that the logic circuit 36 ​​provides a sleep signal Ssp based on the detection signal Ss at the second level, or the oscillator 38 directly uses the detection signal Ss of the second level as the sleep signal Ssp. Finally, no frequency signal is provided based on the sleep signal (S200). When the oscillator 38 receives the sleep signal Ssp, the oscillator 38 goes into sleep mode and does not provide the frequency signal Sck. As a result, the internal circuits that operate using the frequency signal Sck (such as latch circuits, drive circuits, etc.) will also go into sleep mode because there is no frequency signal.

[0051] To prevent the ground jagged edges or switching surges generated by the light-emitting driving signal Sl from affecting the accuracy of the logic circuit 36 ​​in determining the holding width of the detection signal Ss, noise filtering can be performed on the light-emitting driving signal or the detection signal before or after step (S120) (S220). A preferred embodiment is to use a filtering circuit 40 to filter the noise from the light-emitting driving signal Sl or the detection signal Ss to avoid affecting the accuracy of the logic circuit 36 ​​in determining the holding width of the detection signal Ss.

[0052] The above description is merely a detailed explanation and illustration 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 scope of the present invention should be determined by the scope of the claims of the patent application. All embodiments that conform to the spirit of the claims of the present invention and similar variations thereof should be included in the scope of the present invention. Any variations or modifications that can be easily conceived by a person skilled in the art within the field of the present invention can be covered by the following patent scope of the present invention.

Claims

1. A control system for LED string lights, characterized in that, include: A control module switches a DC voltage to a light-emitting drive signal based on a light-emitting command; A string of light-emitting diodes (LEDs) coupled to the control module, and including at least one LED module, the at least one LED module comprising: A detection circuit generates a detection signal corresponding to the light-emitting driving signal, wherein when the light-emitting driving signal is at a high level, the detection signal is at a first level; and when the light-emitting driving signal is at a low level, the detection signal is at a second level. A logic circuit determines, based on a holding width of the detection signal at the first level, whether the first level belongs to a first logic signal, a second logic signal, or a latch signal; and An oscillator that goes into sleep mode based on a sleep signal and provides a frequency signal based on the first level for the logic circuit to calculate the sustain width; The logic circuit provides the sleep signal based on the detection signal at the second level, or the oscillator uses the detection signal at the second level as the sleep signal.

2. The LED string control system as described in claim 1, characterized in that, The at least one light-emitting diode module further includes at least one light-emitting diode, and the at least one light-emitting diode module latches the first logic signal and the second logic signal into a drive command according to the latch signal, so as to control the light-emitting behavior of the at least one light-emitting diode according to the drive command.

3. The LED string control system as described in claim 1, characterized in that, The oscillator does not provide this frequency signal when it is in sleep mode.

4. The LED string control system as described in claim 1, characterized in that, The at least one light-emitting diode module further includes: A filter circuit is coupled to the detection circuit; The filtering circuit performs noise filtering on the light-emitting drive signal or the detection signal.

5. The LED string control system as described in claim 1, characterized in that, The control module includes: A power switch receives the DC voltage and is coupled to the LED string; and A controller, coupled to the power switch, receives the light-emitting command; The controller provides a control signal based on the light-emitting command to control the power switch to turn on or off, thereby switching the DC voltage into the light-emitting drive signal by controlling the power switch to turn on or off.

6. The LED string control system as described in claim 1, characterized in that, When there are multiple light-emitting diode modules, these light-emitting diode modules are connected in series or in parallel.

7. A signal control method for a string of light-emitting diodes (LEDs), characterized in that, Includes the following steps: The DC voltage is switched to an LED driving signal according to an LED emission command. Generate a detection signal corresponding to the light-emitting driving signal; Based on a sustaining width of the detection signal at a first level, it is determined whether the first level belongs to a first logic signal, a second logic signal, or a latching signal; and A frequency signal is provided based on the first level, and the sustain width is calculated using the frequency signal.

8. The signal control method for a string of light-emitting diodes as described in claim 7, characterized in that, It further includes the following steps: providing a sleep signal based on the detection signal at a second level; and The frequency signal is not provided based on the sleep signal.

9. The signal control method for a string of light-emitting diodes as described in claim 7, characterized in that, It further includes the following steps: providing a control signal according to the light-emitting command to control the on or off of a power switch, so as to switch the DC voltage to the light-emitting drive signal by controlling the on or off of the power switch.

10. The signal control method for a string of light-emitting diodes as described in claim 7, characterized in that, It also includes the following steps: performing noise filtering on the light-emitting drive signal or the detection signal.

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