Patent Description:
The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

As the applications of light-emitting diodes (LEDs) are becoming more and more popular, and their manufacturing costs are getting lower and lower, the applications of LEDs in lighting or display are becoming more and more widespread. Therefore, there are more and more manners to operate and control lighting behavior of LEDs. In the applications of the LED light string, since it is necessary to set lighting behavior of each LED, the LED light string can produce a visual effect. Accordingly, a controller should be used to control each LED, and each controller also has the function of identifying signals so as to be able to determine whether the signals are specific lighting commands.

However, the signal received by the controller must be also used for the internal operating power of the controller. In the process of identifying the signal, the controller consumes a large amount of power, causing the voltage level of the signal to gradually decrease. If the voltage level of this signal cannot maintain the normal operation of the controller, the LED light string will fail.

<CIT> discloses a switching regulator with constant on time control which adopts a timer to time when the system is in discontinuous current mode (DCM). If the DCM lasted for a set time, a power stage in the switching regulator is controlled to be ON for a minimum on time duration, so as to ensure the switching regulator enters sleep mode. The control circuit comprises a control module for converting convert a DC voltage into a drive signal according to a command, and an electronic device coupled to the control module. A detection circuit is provided to generate a detected signal corresponding to the drive signal, and a logic circuit is provided to determine a first level being a first logic signal, a second logic signal, or a latch signal according to a time duration of the detected signal at the first level, and an oscillator is provided to provide a clock signal to the logic circuit for calculating the time duration according to the first level and go into a sleep mode according to a sleep signal. The logic circuit provides the sleep signal according to the detected signal at a second level, or the detected signal at the second level is used as the sleep signal for the oscillator. The application to control of LED light strings is not disclosed. Moreover, an LED module latching the first logic signal and the second logic signal as a drive command, and controlling lighting behavior of the at least one LED according to the drive command is not disclosed.

It is an object of the present invention to provide a light-emitting diode (LED) light string control system using carrier signal control and a corresponding signal control method of a light-emitting diode (LED) light string, enabling a reduced power consumption and a versatile control operation.

This problem is solved by a light-emitting diode (LED) light string control system using carrier signal control as claimed in claim <NUM>, and by a signal control method of a light-emitting diode (LED) light string as claimed in claim <NUM>. Further advantageous embodiments are the subject-matter of the dependent claims.

The main purpose and effect of the present disclosure are that a logic determination is performed when the lighting drive signal is at the high-level voltage and the LED module sleeps when the lighting drive signal is at the low-level voltage. Therefore, when the lighting drive signal is at the low-level voltage, the LED module hardly consumes power, which can prevent the voltage level of the lighting drive signal from being lower than the reset voltage of the LED module due to excessive power consumption.

It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the present disclosure as claimed. Other advantages and features of the present disclosure will be apparent from the following description, drawings and claims.

The present disclosure can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawing as follows:.

Reference will now be made to the drawing figures to describe the present disclosure in detail. It will be understood that the drawing figures and exemplified embodiments of present disclosure are not limited to the details thereof.

Please refer to <FIG>, which shows a block circuit diagram of a light-emitting diode (LED) light string control system using carrier signal control according to the present disclosure. The LED light string control system <NUM> receives an input voltage Vin through an input end. The LED light string control system <NUM> includes a rectifier <NUM>, a control module <NUM>, and an LED light string <NUM>. The control module <NUM> is coupled to the rectifier <NUM> and the LED light string <NUM>. The rectifier <NUM> rectifies an AC input voltage Vin into a DC voltage Vdc. The control module <NUM> receives the DC voltage Vdc, and converts (switches) the DC voltage Vdc into a carry-based lighting drive signal Sl according to a lighting command Cl externally provided. The LED light string <NUM> is coupled to the control module <NUM>, and the LED light string <NUM> includes at least one LED module <NUM> (multiple LED modules <NUM> are exemplified for demonstration in this embodiment). Each LED module <NUM> includes at least one LED <NUM>, and the LED module <NUM> controls lighting behavior of the at least one LED <NUM> according to the lighting drive signal Sl. When the at least one LED module <NUM> is plural, these LED modules <NUM> may be coupled in series (shown in <FIG>) or coupled in parallel (not shown). In one embodiment, the LED light string control system <NUM> may not include the rectifier <NUM>, that is, the LED light string control system <NUM> directly receives the DC voltage Vdc as the input voltage. Alternatively, the rectifier <NUM> may be replaced by a DC converter, and the DC converter receives a DC input voltage Vin and converts the input voltage Vin into the DC voltage Vdc.

The control module <NUM> includes a power switch <NUM> and a controller <NUM>. The power switch <NUM> is coupled between the rectifier <NUM> and the LED light string <NUM>. The controller <NUM> is coupled to a control end of the power switch <NUM>, and provides a control signal Sc to control turning on and turning off the power switch <NUM> according to the lighting command Cl so as to convert (switch) the DC voltage Vdc into the lighting drive signal Sl by turning on and turning off the power switch <NUM>. In particular, the controller <NUM> may not include a traditional lighting signal generator, and generates the lighting drive signal Sl with changes in high-level voltage and low-level voltage by controlling turning on or turning off the power switch <NUM>.

Please refer to <FIG>, which shows a block circuit diagram of an LED module according to the present disclosure, and also refer to <FIG>. Each LED module <NUM> further includes a detection circuit <NUM>, a logic circuit <NUM>, and an oscillator <NUM>. The detection circuit <NUM> is coupled to the control module <NUM>, and detects the lighting drive signal Sl to generate a detected signal Ss corresponding to the lighting drive signal Sl. The logic circuit <NUM> is coupled to the detection circuit <NUM>, and determines whether to provide a sleep signal Ssp according to the detected signal Ss. In one embodiment, the sleep signal is, but not limited to, an internal signal. The oscillator <NUM> is coupled to the logic circuit <NUM>, and whether the oscillator <NUM> goes to sleep (i.e., goes into a sleep mode) or not depends on whether it receives the sleep signal Ssp.

Specifically, the detection circuit <NUM> may generate the detected signal Ss complementary to the lighting drive signal Sl or proportional to the lighting drive signal Sl by detecting the lighting drive signal Sl. The logic circuit <NUM> determines whether the first level is the first logic signal (such as logic "<NUM>"), the second logic signal (such as logic "<NUM>"), or the latch signal according to a time duration of the detected signal Ss at the first level. The logic circuit <NUM> provides the sleep signal Ssp according to the detected signal Ss at a second level, or the detected signal Ss at the second level is directly used as the sleep signal Ssp for the oscillator <NUM>. Therefore, the oscillator <NUM> is controlled to go to sleep to save power consume when the lighting drive signal Sl is at the low-level voltage so that the low-level voltage will be not consumed too much and be not lower than the reset voltage. When the oscillator <NUM> does not receive the sleep signal Ssp, the oscillator <NUM> provides the clock signal Sck to the logic circuit <NUM> for calculating the time duration. When the oscillator <NUM> receives the sleep signal Ssp, the oscillator <NUM> goes to sleep (or goes into a sleep mode) and does not provide the clock signal Sck so that internal circuits (such as latch circuits, drive circuits, etc.) operated based on the clock signal Sck will also go to sleep due to the absence of the clock signal Sck, thereby significantly reducing the power consume of the LED module <NUM>.

When the logic circuit <NUM> determines that the time duration of the detected signal Ss at the first level is the latch signal, the logic circuit <NUM> notifies the LED module <NUM> to latch and memorize (store) the temporarily stored first logic signal and second logic signal as a drive command. Afterward, the LED module <NUM> may use the drive command to control lighting behavior of the LED <NUM>. Take the complementary of the lighting drive signal Sl and the detected signal Ss as an example, the first level, i.e., the low-level voltage is corresponding to the high-level voltage of the lighting drive signal Sl, and the second level, i.e., the high-level voltage) is corresponding to the low-level voltage of the lighting drive signal Sl.

Moreover, in order to reduce the installation cost of the LED light string control system <NUM>, the LED module <NUM> without the power-off memory function is usually implemented. The LED module <NUM> with the power-off memory function will reset and forget the settings and the memorized drive commands when the received power (i.e., the lighting drive signal SI) of the LED module <NUM> is lower than the reset voltage (i.e., the required working voltage for internal operation). In order to avoid the above situation, the operation of the LED light string control system <NUM> is usually to prevent the voltage level of the lighting drive signal Sl from being lower than the reset voltage as much as possible. However, the lighting drive signal Sl is usually a pulse voltage with alternating high voltage level and low voltage level. When the lighting drive signal Sl is at the low level voltage for logic determination (that is, the first logic signal, the second logic signal, and the latch signal are determined), the LED module <NUM> is still working and consumes power. Therefore, it is easy to happen that the voltage level of the lighting drive signal Sl is consumed below the reset voltage due to excessive power consumption during the determination process.

The main purpose and effect of the present disclosure are that a logic determination is performed when the lighting drive signal Sl is at the high-level voltage and the LED module <NUM> goes to sleep when the lighting drive signal Sl is at the low-level voltage. Therefore, when the lighting drive signal Sl is at the low-level voltage, the LED module <NUM> hardly consumes power, which can prevent the voltage level of the lighting drive signal Sl from being lower than the reset voltage of the LED module <NUM> due to excessive power consumption.

Please refer to <FIG> again, each LED module <NUM> further include a filter circuit <NUM>, and the filter circuit <NUM> is coupled to the detection circuit <NUM>. The filter circuit <NUM> may be coupled between the detection circuit <NUM> and the control module <NUM> for filtering noise of the lighting drive signal Sl. Alternatively, the filter circuit <NUM> may be coupled between the detection circuit <NUM> and the logic circuit <NUM> for filtering noise of the detected signal Ss. Specifically, since the lighting drive signal Sl is a high-power signal and the power switch <NUM> is switched at a high frequency, the lighting drive signal Sl produces more rough edges or switching surges, and the rough edges or switching surges will affect the detection accuracy of the time duration of the detected signal Ss. It even misjudges the signal that should be logic "<NUM>" or logic "<NUM>" as other signals. Therefore, using the filter circuit <NUM> to filter noise of the lighting drive signal Sl or noise of the detected signal Ss is a preferred embodiment of the LED light string control system <NUM>. Since the LED module <NUM> is a weak-current operation and consumes less power during operation, the filter circuit <NUM> coupled between the detection circuit <NUM> and the logic circuit <NUM> is a preferred embodiment.

Please refer to <FIG>, which shows a waveform diagram of signals related to the LED light string control system according to the present disclosure, and also refer to <FIG> and <FIG>. In <FIG>, Sl is the lighting drive signal, Ss is the detected signal, Sf is a filtered detected signal (hereinafter referred to as "filtered signal Sf', and Sk is a latched signal. The control module <NUM> converts (switches) the DC voltage Vdc into the carry-based lighting drive signal Sl. The lighting drive signal Sl has a high-level voltage and a low-level voltage, and the low-level voltage is not lower than a reset voltage Vr. In the lighting drive signal Sl, there is a high-level voltage with a longer width X, which represents that the previous carrier has been generated, and the correspondingly received LED module <NUM> can latch the drive command corresponding to the previous carrier. The detection circuit <NUM> detects the lighting drive signal Sl to generate a detected signal Ss complementary to the lighting drive signal Sl, and the filter circuit <NUM> filters the detected signal Ss to generate the filtered signal Sf that slightly delays to the detected signal Ss.

When the detected signal Ss is at the second level (that is, when the lighting drive signal Sl is at a low-level voltage), the LED module <NUM> controls the oscillator <NUM> to go to sleep so that most of the circuits that consume more power inside the LED module <NUM> are slept and the low-level voltage of the lighting drive signal Sl consumes less power. Therefore, the low-level voltage will be not consumed too much and be not lower than the reset voltage Vr. When the detected signal Ss is at the first level (that is, when the lighting drive signal Sl is at a high-level voltage), the logic circuit <NUM> uses the clock signal Sck provided by the oscillator <NUM> to calculate the time duration Y (for example, a wider width is determined to be a logic "<NUM>" and a narrower width is determined to be a logic "<NUM>"). When the width of the detected signal Ss at the first level is the widest (i.e., the width X), it is determined as the latch signal, and the previous filtered signal Sf is latched. Finally, after latching for a short period of time, the latched signal Sk is provided to inform the completion of latching the drive command. In particular, since the latch signal is usually maintained for a long time and the time for determining the low-level lighting drive signal Sl is long to make the LED module <NUM> consume power for a long time, it is easy to produce a situation where the lighting drive signal Sl is lower than the reset voltage Vr. Therefore, the low-level latch signal changes to the high-level latch signal (i.e., the width X is the high-level voltage) by the controller <NUM> to avoid this situation that the lighting drive signal Sl is lower than the reset voltage Vr.

Please refer to <FIG>, which shows a flowchart of a signal control method of the LED light string control system according to the present disclosure, and also refer to <FIG>. The signal control method includes steps of converting a DC voltage into a lighting drive signal according to a lighting command (S100). In one embodiment, a controller <NUM> is used to provide a control signal Sc to control turning on or turning off a power switch <NUM> according to a lighting command Cl so as to convert the DC voltage Vdc into the lighting drive signal Sl. Afterward, generating a detected signal corresponding to the lighting drive signal (S120). In one embodiment, a detection circuit <NUM> is used to detect the lighting drive signal Sl to generate the detected signal Ss corresponding to the lighting drive signal Sl, for example, the detected signal Ss is complementary to the lighting drive signal Sl or proportional to the lighting drive signal Sl. Afterward, determining a first level being a first logic signal, a second logic signal, or a latch signal according to a time duration of the detected signal at the first level (S140). In one embodiment, a logic circuit <NUM> is used determines that the first level is the first logic signal (such as logic "<NUM>"), the second logic signal (such as logic "<NUM>"), or the latch signal according to the time duration of the detected signal Ss at the first level.

Afterward, providing a clock signal according to the first level and calculating the time duration by the clock signal (S160). In one embodiment, an oscillator <NUM> is used to provide a clock signal Sck to the logic circuit <NUM> notified by the detection circuit <NUM> or the logic circuit <NUM> for calculating the time duration according to the detected signal Ss at the first level so as to determine that the first level of the detected signal Ss is the first logic signal, the second logic signal, or the latch signal. Afterward, providing a sleep signal according to the detected signal at a second level (S180). In one embodiment, the logic circuit <NUM> is used to provide the sleep signal Ssp according to the detected signal Ss at the second level, or the detected signal Ss at the second level is directly used as the sleep signal Ssp for the oscillator <NUM>. Finally, without providing the clock signal according to the sleep signal (S200). When the oscillator <NUM> receives the sleep signal Ssp, the oscillator <NUM> goes to sleep and does not provide the clock signal Sck so that internal circuits (such as latch circuits, drive circuits, etc.) operated based on the clock signal Sck will also go to sleep due to the absence of the clock signal Sck.

Claim 1:
A light-emitting diode (LED) light string control system (<NUM>) using carrier signal control, comprising:
a control module (<NUM>) configured to convert a DC voltage (Vdc) into a lighting drive signal (Sl) according to a lighting command (Cl), and
an LED light string (<NUM>) comprising at least one LED module (<NUM>), and coupled to the control module (<NUM>), and the at least one LED module (<NUM>) comprising:
a detection circuit (<NUM>) configured to generate a detected signal (Ss) corresponding to the lighting drive signal (Sl),
a logic circuit (<NUM>) configured to determine a first level being a first logic signal, a second logic signal, or a latch signal according to a time duration of the detected signal (Ss) at the first level,
an oscillator (<NUM>) configured to provide a clock signal (Sck) to the logic circuit (<NUM>) for calculating the time duration according to the first level and go into a sleep mode according to a sleep signal (Ssp), and
at least one LED (<NUM>),
wherein the logic circuit (<NUM>) is configured to provide the sleep signal (Ssp) according to the detected signal (Ss) at a second level, or the oscillator is configured to receive the detected signal (Ss) at the second level that is used as the sleep signal (Ssp) for the oscillator (<NUM>),
wherein the at least one LED module (<NUM>) is configured to latch the first logic signal and the second logic signal as a drive command, and control lighting behavior of the at least one LED (<NUM>) according to the drive command, and
wherein the oscillator (<NUM>) does not provide the clock signal (Sck) when in the sleep mode.