Dimming control system, dimming control device, control chip and dimming control method

Abstract

The invention relates to a dimming control system, a dimming control device, a control chip and a dimming control method. The dimming control system includes: a power switch that is turned on or off based on a switch control signal to control power supply to the lamp; and a control chip for generating a switch control signal, the control chip comprising: a dimming control module configured to generate a dimming control signal based on a dimming signal for the lamp, the switch control signal being generated based on the dimming control signal, and the dimming signal being switched on when the time of an on stage of the dimming signal is greater than or equal to a preset time; in the turn-off stage of the dimming signal, the dimming control signal and the dimming signal are turned off consistently, and the switch control signal is turned off synchronously; under the condition that the time of the turn-on stage of the dimming signal is less than the preset time, in the turn-off stage of the dimming signal, the dimming control signal is turned off after delaying at least one period of the switch control signal relative to the dimming signal, and the switch control signal is turned off after continuing at least one period.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit technology, and more specifically to a dimming control system, a dimming control device, a control chip and a dimming control method. Background Art

[0002] In the LED backlight application of switching power supply, multi-channel constant current backlight drive is a common system architecture, and its advantage is that the backlight distribution is relatively uniform. Compared with the single-string LED backlight system, the multi-string parallel LED backlight system can be evenly distributed under the screen, and the brightness of each area of ​​the screen is consistent. There will be no problem of high brightness in the middle of the screen and low brightness in the four corners in the single-string LED backlight system. However, the traditional system may have a low input energy when the high-frequency PWM dimming duty cycle is small, resulting in a lower output voltage, which causes the current output to the LED lamp to drop during high-frequency dimming, affecting the normal dimming function. Summary of the invention

[0003] In one aspect, a dimming control system is provided according to an embodiment of the present application, the dimming control system comprising: a power switch, which is turned on or off based on a switch control signal to control the power supply to a lamp; and a control chip, which generates a switch control signal, wherein the control chip comprises: a dimming control module, which is configured to generate a dimming control signal based on a dimming signal for the lamp, wherein the switch control signal is generated based on the dimming control signal, and wherein, when the time of the turn-on phase of the dimming signal is greater than or equal to a preset time, in the turn-off phase of the dimming signal, the dimming control signal is turned off consistently with the dimming signal, and the switch control signal is turned off synchronously; when the time of the turn-on phase of the dimming signal is less than the preset time, in the turn-off phase of the dimming signal, the dimming control signal is delayed by at least one cycle of the switch control signal relative to the dimming signal before being turned off, and the switch control signal continues to be turned off after at least one cycle.

[0004] On the other hand, according to an embodiment of the present application, a dimming control device is provided, which includes: a detection unit, configured to determine the time of the on-phase of a dimming signal for a lamp, and compare the determined time of the on-phase of the dimming signal with a preset time; a direct determination unit, configured to generate a control signal consistent with the dimming signal in the off-phase of the dimming signal when the result of the comparison indicates that the time of the on-phase of the dimming signal is greater than or equal to the preset time; a timing determination unit, configured to generate a control signal that is delayed by at least one cycle of a switch control signal for controlling the power supply to the lamp in the off-phase of the dimming signal when the result of the comparison indicates that the time of the on-phase of the dimming signal is less than the preset time; and a mode selection unit, configured to provide the control signal of the direct determination unit or the control signal of the timing determination unit as the dimming control signal.

[0005] In another aspect, a dimming control chip is provided according to an embodiment of the present application. The dimming control chip includes a dimming control device according to an embodiment of the present application.

[0006] In another aspect, a dimming control method is provided according to an embodiment of the present application, and the dimming control method includes: generating a dimming control signal based on a dimming signal for a lamp, and generating a switch control signal based on the dimming control signal to control power supply to the lamp; wherein, when the time of the on-phase of the dimming signal is greater than or equal to a preset time, in the off-phase of the dimming signal, the dimming control signal is turned off in unison with the dimming signal, and the switch control signal is turned off synchronously; when the time of the on-phase of the dimming signal is less than the preset time, in the off-phase of the dimming signal, the dimming control signal is delayed by at least one cycle of the switch control signal relative to the dimming signal before being turned off, and the switch control signal continues to be turned off after at least one cycle.

[0007] The dimming control system, dimming control device, control chip and dimming control method provided in the embodiments of the present application can effectively achieve normal dimming, and can especially ensure normal dimming during high-frequency dimming. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Various aspects of the present application may be best understood through the following detailed description when read in conjunction with the accompanying drawings. Note that, in accordance with standard industry practice, various features are not necessarily drawn to scale. In the various figures, like numerical numerals describe like components. In the drawings:

[0009] Figure 1 Schematic diagram of a traditional dimming control system.

[0010] Figure 2This is a timing diagram of a traditional dimming control system in MPRT mode.

[0011] Figure 3 Schematic diagram of a dimming control system according to an embodiment of the present application.

[0012] Figure 4 is a timing diagram of the dimming control system in MPRT mode according to an embodiment of the present application.

[0013] Figure 5 4 is a block diagram of an MPRT dimming control module according to an embodiment of the present application.

[0014] Figure 6 Flow chart of a dimming control method according to an embodiment of the present application.

[0015] Figure 7 The flowchart is a flowchart of generating a dimming control signal based on a dimming signal according to an embodiment of the present application. DETAILED DESCRIPTION

[0016] The features and exemplary embodiments of various aspects of the application will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the application. However, it is obvious to those skilled in the art that the application can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the application by illustrating the example of the application. The application is by no means limited to any specific configuration and algorithm proposed below, but covers any modification, replacement and improvement of elements, parts and algorithms without departing from the spirit of the application. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid causing unnecessary ambiguity to the application.

[0017] Figure 1 Figure 1 is a schematic diagram of a traditional dimming system. Figure 1 As shown, the conventional dimming system 100 may be based on the Boost architecture. Figure 1 In the embodiment, the conventional dimming system 100 includes an input part 101, a control part 102 and an output part 103.

[0018] The input part 101 includes an input capacitor C1 and an inductor L1. The first end of the input capacitor C1 is connected to the input voltage VIN of the system, and the second end is connected to the ground. The first end of the inductor L1 is connected to the first end of the input capacitor C1, and the second end of the inductor L1 is connected to the control part 102.

[0019] The control part 102 is connected between the input part 101 and the output part 102. The control part 102 includes a control chip U, a switch tube M1, a first resistor R1, a second resistor R2, and a second capacitor C2.

[0020] The control chip U has an input terminal VIN, an enable terminal ENA, a ground terminal GND, a comparison terminal CMP, a pulse width modulation terminal PWM, a current setting terminal ISET, at least one LED terminal (LED1-LEDX are shown in the figure), a sampling terminal CS and a control terminal GATE, wherein the comparison terminal CMP is grounded through the second capacitor C2, and the current setting terminal ISET is grounded via the second resistor R2. The switch tube M1 and the first resistor R1 are connected in series between the second end of the inductor L1 and the ground. The drain of the switch tube M1 is connected to the second end of the inductor L1, and the gate of the switch tube M1 is used to receive a switch control signal from the control terminal GATE of the control chip U (also marked as GATE here), and the voltage of the source of the switch tube M1 (that is, the voltage on the first resistor R1) is sampled by the sampling terminal CS of the control chip U.

[0021] like Figure 1 As shown, the control chip U includes a voltage stabilizing module 102-1, a PWM detection module 102-2, a current control module 102-3, a first comparator cmp1, a feedback module 102-4, an error amplifier EA, an amplifier CS_amp, an oscillator OSC, a selector S, a second comparator cmp2, ​​a control logic module 102-5 and a driver Driver.

[0022] The voltage regulator module 102-1 is connected to the input voltage VIN and the enable terminal ENA, and is used to provide the reference voltage Vref and the internal reference voltage EA_ref. The voltage regulator module 102-1 can provide the reference voltage Vref and the internal reference voltage EA_ref through, for example, a voltage regulator LDO, an undervoltage protector UVLO, and a reference voltage / current source Vref&Iref.

[0023] The PWM detection module 102 - 2 is connected to the pulse width modulation terminal PWM to provide a PWM dimming signal PWM_in.

[0024] The current control module 102-3 is connected to at least one LED terminal ((as shown in the figure LED1-LEDX), and the first comparator cmp1 is connected to the current setting terminal ISET. The current control module 102-3 performs constant current control on the LED lamp of at least one channel (the LED lamp of each channel is respectively connected to at least one LED terminal) based on the PWM dimming signal PWM_in and the voltage generated on the second resistor R2 based on the current set at the current setting terminal ISET or the comparison of the voltage with the reference voltage Vref via the first comparator cmp1.

[0025] The feedback module 102 - 4 is connected to the current control module 102 - 3 and collects the lowest voltage in at least one path as the feedback signal DHC via the current control module 102 - 3 .

[0026] The error amplifier EA is connected to the feedback module 102 - 4 and the comparison terminal CMP. The error amplifier EA performs error amplification on the internal reference voltage EA_ref and the feedback signal DHC based on the PWM dimming signal PWM_in to generate a comparison signal CMP.

[0027] The amplifier CS_amp is connected to the sampling terminal CS, and amplifies the sampled voltage at the source terminal of the switch tube M1 to generate an amplified signal.

[0028] The oscillator OSC generates a clock signal CLK based on the PWM dimming signal PWM_in. The high level signal of the switch control signal GATE is generated by the clock signal CLK.

[0029] The selector S selectively provides the clock signal CLK or the amplified signal from the amplifier CS_amp as the ramp signal Ramp.

[0030] The second comparator cmp2 compares the comparison signal CMP and the ramp signal Ramp. The control logic module 102-5 generates a logic control signal based on the comparison result of the second comparator cmp2. The driver Driver provides a switch control signal GATE for controlling the gate of the switch tube M1 to be turned on / off based on the logic control signal. The switch control signal GATE is then provided to the gate of the switch tube M1 via the control terminal GATE, thereby controlling the on / off of the switch tube M1.

[0031] The output part 103 includes a freewheeling diode D1 and an output capacitor D3. The freewheeling diode D1 is connected between the drain of the switch tube M1 and the first end of the output capacitor C3, and the second end of the output capacitor C3 is grounded. The first end of the output capacitor C3 provides an output voltage Vout to power the LED lamp of at least one channel.

[0032] exist Figure 1 In the dimming system shown, when the switch control signal GATE from the control terminal GATE of the control chip U is at a high level, the switch tube M1 is turned on, and the input voltage VIN stores energy through the inductor L1. When the signal from the control terminal GATE of the control chip U is at a low level, the switch tube M1 is turned off, and the input voltage VIN superimposed on the energy stored in the inductor L1 charges the output capacitor C3 through the freewheeling diode D1, and the output voltage Vout gradually increases. When the output voltage Vout increases to a certain voltage, at least one LED lamp in the path is turned on.

[0033] Finally, when the internal reference voltage EA_ref and the feedback signal DHC are equal, a suitable output Vout is generated. The suitable output Vout can not only meet the voltage required for the LED lamp output (due to the difference in the on-state voltage of the LED, the output voltage must meet the demand of the LED lamp with the maximum on-state voltage) but also minimize the loss of the control chip U.

[0034] In LED backlight applications, MPRT (Motion Picture Response Time) is a technology that improves the quality of dynamic images by reducing motion blur. The MPRT mode is usually achieved by controlling the on / off or frequency of the backlight. This technology is called backlight strobing, which aims to reduce motion blur and improve the clarity of dynamic images. In the latest version of MPRT, the PWM signal is a complete PWM cycle that includes low-frequency PWM dimming signals at the beginning and end of the frame and high-frequency PWM dimming signals in the middle of the frame. The frequency of a frame signal is 120HZ, of which the frequency of high-frequency PWM dimming is 20KHz---50Khz. This requires the control chip to process the high-frequency dimming signal and switch between the high-frequency PWM dimming signal and the low-frequency PWM dimming signal in real time. In the traditional architecture, the switch control signal GATE is normally output during the PWM ON phase, and the switch control signal GATE is immediately turned off during the PWM OFF phase. Therefore, when the PWM signal is a high-frequency signal and the duty cycle is relatively small, the PWM ON phase is short, so the energy provided during the PWM ON phase may not be sufficient to maintain the consumption of the output load, resulting in a decrease in the output voltage during high-frequency dimming, and a corresponding decrease in the voltage VLED on the LED lamp, which ultimately causes the current output to the LED lamp to decrease during high-frequency dimming, affecting the normal dimming function.

[0035] Figure 2 This is the timing diagram of the traditional dimming system in MPRT mode. Figure 2 It can be seen that the PWM dimming signal is a high-frequency signal added to a low-frequency signal. When the PWM dimming signal is at a high level, the switch control signal GATE is output normally; when the PWM dimming signal is at a low level, the switch control signal GATE is immediately turned off. When the PWM dimming signal is a low-frequency signal, the voltage VLED on the LED lamp is adjusted to a normal set value, and the current ILED output to the LED lamp is normal; when the PWM dimming signal is a high-frequency signal, the number of pulses of the switch control signal GATE in the PWM ON stage is too small, resulting in the energy consumed being greater than the energy provided. In addition, from Figure 2It can also be seen that in the PWM ON stage, the voltage VLED on the LED lamp gradually decreases, causing the high level of the waveform of the current ILED output to the LED lamp to decrease, and its average current may be lower than the set value, affecting the dimming function.

[0036] In view of the above, the present disclosure provides an optimized dimming system, which effectively controls the voltage VLED on the LED lamp by adding an MPRT control module on the basis of the traditional dimming system, thereby ensuring a constant current output to the LED lamp.

[0037] Figure 3 FIG. 1 is a schematic diagram of a dimming system according to an embodiment of the present application. Figure 3 As shown, the dimming system 300 according to the embodiment of the present application is Figure 1 The difference between the conventional dimming system 100 described in the main embodiment is the addition of an MPRT control module, which is described in detail below.

[0038] exist Figure 3 In the embodiment of the present application, the dimming system 300 includes an input part 301, a control part 302 and an output part 303.

[0039] The input part 301 includes an input capacitor C1 and an inductor L1. The first end of the input capacitor C1 is connected to the input voltage VIN of the system, and the second end is connected to the ground. The first end of the inductor L1 is connected to the first end of the input capacitor C1, and the second end of the inductor L1 is connected to the control part 302.

[0040] The control part 302 is connected between the input part 301 and the output part 302. The control part 302 includes a control chip U, a switch tube M1, a first resistor R1, a second resistor R2 and a second capacitor C2.

[0041] The control chip U has an input terminal VIN, an enable terminal ENA, a ground terminal GND, a comparison terminal CMP, a pulse width modulation terminal PWM, a current setting terminal ISET, a plurality of LED terminals LED1-LEDX, a sampling terminal CS and a control terminal GATE, wherein the comparison terminal CMP is grounded through a second capacitor C2, and the current setting terminal ISET is grounded via a second resistor R2. The switch tube M1 and the first resistor R1 are connected in series between the second end of the inductor L1 and the ground. The drain of the switch tube M1 is connected to the second end of the inductor L1, and the gate of the switch tube M1 is used to receive a switch control signal GATE from the control terminal GATE of the control chip U. The voltage of the source of the switch tube M1 (i.e., the voltage on the first resistor R1) is sampled by the sampling terminal CS of the control chip U.

[0042] like Figure 3As shown, the control chip U includes a voltage stabilization module 302-1, a PWM detection module 302-2, an MPRT control module 302-3, a current control module 302-4, a first comparator cmp1, a feedback module 302-5, an error amplifier EA, an amplifier CS_amp, an oscillator OSC, a selector S, a second comparator cmp2, ​​a control logic module 302-6 and a driver Driver.

[0043] The voltage regulator module 302-1 is connected to the input voltage VIN and the enable terminal ENA, and is used to provide the reference voltage Vref and the internal reference voltage EA_ref. The voltage regulator module 302-1 can provide the reference voltage Vref and the internal reference voltage EA_ref through, for example, a voltage regulator LDO, an undervoltage protector UVLO, and a reference voltage / current source Vref&Iref.

[0044] The PWM detection module 302 - 2 is connected to the pulse width modulation terminal PWM to provide a PWM dimming signal PWM_in.

[0045] The MPRT control module 302 - 3 is connected to the PWM detection module 302 - 2 , and generates the MPRT control signal MPRT_out based on the PWM dimming signal PWM_in.

[0046] The current control module 302-4 is connected to at least one LED terminal (LED1-LEDX shown in the figure), and the first comparator cmp1 is connected to the current setting terminal ISET. The current control module 302-4 performs constant current control on the LED lamp of at least one channel (the LED lamp of each channel is respectively connected to at least one LED terminal) based on the MPRT control signal MPRT_out and the voltage generated on the second resistor R2 based on the current set at the current setting terminal ISET or the comparison of the voltage with the reference voltage Vref via the first comparator cmp1.

[0047] The feedback module 302 - 5 is connected to the current control module 302 - 4 , and collects the lowest voltage in at least one path as the feedback signal DHC via the current control module 302 - 4 .

[0048] The error amplifier EA is connected to the feedback module 302 - 5 and the comparison terminal CMP. The error amplifier EA performs error amplification on the internal reference voltage EA_ref and the feedback signal DHC based on the PWM dimming signal PWM_in to generate a comparison signal CMP.

[0049] The amplifier CS_amp is connected to the sampling terminal CS, and amplifies the sampled voltage at the source terminal of the switch tube M1 to generate an amplified signal.

[0050] The oscillator OSC generates a clock signal CLK based on the MPRT control signal MPRT_out. The high level signal of the switch control signal GATE is generated by the clock signal CLK.

[0051] The selector S selectively provides the clock signal CLK or the amplified signal from the amplifier CS_amp as the ramp signal Ramp.

[0052] The second comparator cmp2 compares the comparison signal CMP and the ramp signal Ramp. The control logic module 302-6 generates a logic control signal based on the comparison result of the second comparator cmp2. The driver Driver provides a switch control signal GATE for controlling the gate of the switch tube M1 to be turned on / off based on the logic control signal. The switch control signal GATE is then provided to the gate of the switch tube M1 via the control terminal GATE, thereby controlling the on / off of the switch tube M1.

[0053] The output part 303 includes a freewheeling diode D1 and an output capacitor D3. The freewheeling diode D1 is connected between the drain of the switch tube M1 and the first end of the output capacitor C3, and the second end of the output capacitor C3 is grounded. The first end of the output capacitor C3 provides an output voltage Vout to power the LED lamp of at least one channel.

[0054] exist Figure 3 In the dimming system according to the embodiment of the present application shown, when the switch control signal GATE from the control terminal GATE of the control chip U is at a high level, the switch tube M1 is turned on, and the input voltage VIN is stored through the inductor L1. When the switch control signal GATE from the control terminal GATE of the control chip U is at a low level, the switch tube M1 is turned off, and the input voltage VIN superimposed on the energy stored in the inductor L1 charges the output capacitor C3 through the freewheeling diode D1, and the output voltage Vout gradually increases. When the output voltage Vout increases to a certain voltage, the LED lamp of at least one path is turned on.

[0055] exist Figure 3In the dimming system according to the embodiment of the present application shown, the MPRT control module 302-3 determines whether to enter the MPRT control mode according to the time of the on (PWM ON) stage of the PWM dimming signal PWM_in. In some embodiments, when the time of the PWM ON stage is less than the preset time, the control chip U enters the MPRT control mode. In the MPRT control mode, in the PWM ON stage, the switch control signal GATE outputs normally, and in the PWM OFF stage, the MPRT control signal MPRT_out delays the switch control signal GATE for N cycles before turning off, and the oscillator OSC also delays the N cycles to turn off accordingly. Due to the existence of delayed shutdown, the output voltage drops relatively little or does not drop, and the voltage VLED on the LED lamp is sufficient for constant current output. As an example, the number of cycles N=1, or N=2, or N=3. It should be understood that the value of N is not limited to this and can be set according to system requirements.

[0056] Based on the above, according to an embodiment of the present application, a dimming control system is provided, including: a power switch, which is turned on or off based on a switch control signal to control the power supply to the lamp; and a control chip, which generates a switch control signal, wherein the control chip includes: a dimming control module, which is configured to generate a dimming control signal based on the dimming signal for the lamp, wherein the switch control signal is generated based on the dimming control signal, and wherein, when the time of the turn-on phase of the dimming signal is greater than or equal to the preset time, in the turn-off phase of the dimming signal, the dimming control signal is turned off consistently with the dimming signal, and the switch control signal is turned off synchronously; when the time of the turn-on phase of the dimming signal is less than the preset time, in the turn-off phase of the dimming signal, the dimming control signal is delayed by at least one cycle of the switch control signal relative to the dimming signal before being turned off, and the switch control signal continues to be turned off after at least one cycle.

[0057] In some implementations, during the on-stage of the dimming signal, the dimming control signal is turned on in unison with the dimming signal, and the switch control signal is turned on synchronously.

[0058] Figure 4 : is a timing diagram of the dimming control system in MPRT mode according to an embodiment of the present application. Figure 4It can be seen that the PWM dimming signal is a high-frequency signal added to a low-frequency signal. When the PWM dimming signal is a low-frequency signal, the time of the PWM ON stage is greater than or equal to the preset time, and the control signal MPRT_out generated by the control chip U is consistent with the PWM signal. In this case, in the PWM ON stage, the switch control signal GATE is output normally, and in the PWM OFF stage, the switch control signal GATE is immediately turned off. When the PWM dimming signal is a high-frequency signal, the time of the PWM ON stage is less than the preset time. At this time, the MPRT control signal MPRT_out generated by the control chip U is delayed by at least one cycle (for example, 2 cycles) of the switching control signal in the PWM OFF stage before it is turned off. In this case, in the PWM ON stage, the switch control signal GATE is output normally, and in the PWM OFF stage, the switch control signal GATE is also delayed by 2 cycles before it is turned off. Finally, due to the delayed shutdown, the voltage VLED output to the LED lamp in the PWM ON stage during high-frequency dimming is higher than the voltage output to the LED lamp during low-frequency dimming, so that the channel has enough voltage to maintain constant current operation. From Figure 4 It can also be seen from the ILED in that the high level of the current ILED output to the LED lamp is consistent during the entire dimming process, so that the average current can be consistent with the preset current.

[0059] Figure 5 FIG. 1 is a block diagram of an MPRT control module according to an embodiment of the present application. Figure 5 As shown, the MPRT control module 302-3 includes:

[0060] The detection unit 3-1 is configured to determine the time of the on phase of the PWM dimming signal PWM_in for the lamp, and compare the determined time of the on phase of the PWM dimming signal PWM_in with a preset time, thereby providing a comparison result mpt;

[0061] The direct determination unit 3-2 is configured to generate a first control signal (i.e., MPRT turn-off signal MPRT_OFF) consistent with the PWM dimming signal PWM_in during the turn-off phase of the PWM dimming signal PWM_in when the comparison result mpt indicates that the time of the turn-on phase of the PWM dimming signal PWM_in is greater than or equal to the preset time (at this time, mpt is a low level);

[0062] The timing determination unit 3-3 is configured to generate a second control signal (i.e., MPRT turn-off signal MPRT_ON) that is delayed by at least one cycle of the switch control signal GATE for controlling the power supply to the lamp in the turn-off phase of the PWM dimming signal PWM_in when the comparison result mpt indicates that the time of the turn-on phase of the PWM dimming signal PWM_in is less than the preset time (at this time, mpt is a high level) relative to the PWM dimming signal PWM_in.

[0063] The mode selection unit 3 - 4 is configured to provide the first control signal of the direct determination unit 3 - 2 or the second control signal of the timing determination unit 3 - 3 as a dimming control signal (ie, the MPRT off signal MPRT_out).

[0064] In some implementations, the direct determination unit 3 - 2 may also be configured to generate a control signal consistent with the dimming signal during the on-phase of the dimming signal.

[0065] In some implementations, the dimming signal may be a high frequency pulse width modulation (PWM) signal.

[0066] According to the dimming system of the embodiment of the present application, the control chip U determines the time of the on-phase of the PWM dimming signal. When the time of the PWM ON phase is greater than or equal to the preset time, the dimming control signal is the same as the externally input PWM dimming signal. In the PWM OFF phase, the switch control signal GATE is immediately turned off following the PWM dimming signal. When the PWM ON time is less than the preset time, the dimming control signal is turned off after delaying at least one cycle of the switch control signal GATE. In the PWM OFF phase, the switch control signal GATE continues to output at least one cycle. In this control mode, it is possible to ensure that the voltage VLED on the LED lamp is sufficient for constant current output.

[0067] Figure 6 FIG. 1 is a flow chart of a dimming control method according to an embodiment of the present application. Figure 6 As shown, the dimming control method 600 according to the embodiment of the present application can be Figure 3 The dimming control system 300 shown is implemented according to the embodiment of the present application.

[0068] like Figure 6 As shown, the dimming control method 600 according to the embodiment of the present application includes S601 - S602 .

[0069] In S601, a dimming control signal is generated based on a dimming signal for a lamp.

[0070] In S602 , a switch control signal is generated based on the dimming control signal to control power supply to the lamp.

[0071] Wherein, when the time of the on phase of the dimming signal is greater than or equal to the preset time, in the off phase of the dimming signal, the dimming control signal is turned off in unison with the dimming signal, and the switch control signal is turned off synchronously;

[0072] When the on-phase time of the dimming signal is less than the preset time, in the off-phase of the dimming signal, the dimming control signal is delayed by at least one cycle of the switch control signal relative to the dimming signal before being turned off, and the switch control signal continues to be turned off after at least one cycle.

[0073] Figure 7 FIG. 1 is a flow chart of generating a dimming control signal based on a dimming signal for a lamp according to an embodiment of the present application. Figure 7 As shown, generating a dimming control signal 700 based on a dimming signal includes S701 - S704 .

[0074] At S701, determining the time of the on phase of the dimming signal, and comparing the determined time of the on phase of the dimming signal with a preset time;

[0075] At S702, when the comparison result indicates that the time of the on phase of the dimming signal is greater than or equal to the preset time, a first control signal consistent with the dimming signal is generated in the off phase of the dimming signal;

[0076] At S703, when the comparison result indicates that the time of the on phase of the dimming signal is less than the preset time, a second control signal is generated in the off phase of the dimming signal, which is turned off by delaying the switch control signal by at least one cycle relative to the dimming signal; and

[0077] In S703 , the first control signal or the second control signal is provided as a dimming control signal.

[0078] In some implementations, according to the dimming control method of the embodiment of the present application, generating a dimming control signal based on the dimming signal also includes: in the activation phase of the dimming signal, generating a control signal consistent with the dimming signal, and the switch control signal is synchronously activated.

[0079] In some implementations, the dimming signal may be a high frequency pulse width modulation (PWM) signal.

[0080] According to the dimming method of the embodiment of the present application, when the time of the on phase of the dimming signal is less than the preset time, in the off phase of the dimming signal, the dimming control signal is delayed by at least one cycle of the switch control signal before being turned off, and the switch control signal continues to be output for at least one cycle before being turned off. In this control mode, it is possible to ensure that the voltage VLED on the LED lamp is sufficient for constant current output.

[0081] It should be noted that the above description is described in the context of backlight applications. However, the dimming control technology and MPRT control module according to the embodiments of the present application can also be applied to other dimming application scenarios, such as other high-frequency dimming occasions and high-contrast deep dimming occasions. In addition, the above description and drawings are described in the context of 1-N LED light strings. However, the control technology and MPRT control module according to the embodiments of the present application can also adjust more or fewer LED light strings.

[0082] The mechanism of the present application has been described above with reference to the accompanying drawings and various embodiments. It should be understood that the present application is not limited thereto, but can be implemented in other forms without departing from the subject matter and essential features of the present application. The current embodiments are to be considered in all respects as illustrative rather than restrictive, the scope of the present invention is defined by the appended claims rather than the above description, and all changes falling within the meaning and equivalents of the claims are included within the scope of the present application.

Claims

1. A dimming control system, comprising: A power switch, which is turned on or off based on a switch control signal to control the power supply to the lamp; as well as A control chip generates the switch control signal, Wherein, the control chip includes: a dimming control module configured to generate a dimming control signal based on a dimming signal for the lamp, wherein the switch control signal is generated based on the dimming control signal, and Wherein, when the time of the on phase of the dimming signal is greater than or equal to the preset time, in the off phase of the dimming signal, the dimming control signal is turned off in unison with the dimming signal, and the switch control signal is turned off synchronously; When the time of the on phase of the dimming signal is less than the preset time, in the off phase of the dimming signal, the dimming control signal is delayed by at least one cycle of the switch control signal relative to the dimming signal before being turned off, and the switch control signal is turned off after continuing for at least one cycle. 2 . The dimming control system according to claim 1 , wherein in the on-stage of the dimming signal, the dimming control signal is turned on in unison with the dimming signal, and the switch control signal is turned on synchronously.

3. The dimming control system according to claim 1, wherein the dimming control module comprises: a detection unit configured to determine a time of an on-phase of the dimming signal, and compare the determined time of the on-phase of the dimming signal with a preset time; a direct determination unit configured to generate a control signal consistent with the dimming signal during the off phase of the dimming signal if the comparison result indicates that the time during the on phase of the dimming signal is greater than or equal to a preset time; a timing determination unit, configured to generate a control signal that is turned off by delaying the switch control signal by at least one cycle relative to the dimming signal during the turn-off phase of the dimming signal if the comparison result indicates that the time during the turn-on phase of the dimming signal is less than a preset time; as well as A mode selection unit is configured to provide the control signal of the direct determination unit or the control signal of the timing determination unit as the dimming control signal. 4 . The dimming control system according to claim 3 , wherein the direct determination unit is further configured to generate a control signal consistent with the dimming signal during an on-phase of the dimming signal. 5 . The dimming control system according to claim 1 , wherein the dimming signal is a high-frequency pulse width modulation (PWM) signal.

6. A dimming control device, comprising: A detection unit, configured to determine the time of the on-phase of the dimming signal for the lamp, and compare the determined time of the on-phase of the dimming signal with a preset time; a direct determination unit configured to generate a first control signal consistent with the dimming signal during a shut-off phase of the dimming signal if the comparison result indicates that the time during the on phase of the dimming signal is greater than or equal to a preset time; a timing determination unit configured to generate, in a turn-off phase of the dimming signal, a second control signal that is delayed by at least one cycle of a switch control signal for controlling power supply to the lamp relative to the dimming signal before turning off, if the comparison result indicates that the time of the turn-on phase of the dimming signal is less than a preset time; as well as A mode selection unit is configured to provide the first control signal of the direct determination unit or the second control signal of the timing determination unit as the dimming control signal. 7 . The dimming control device according to claim 6 , wherein the direct determination unit is further configured to generate a control signal consistent with the dimming signal during an on-phase of the dimming signal. 8 . The dimming control device according to claim 6 , wherein the dimming signal is a high-frequency pulse width modulation (PWM) signal.

9. A control chip, comprising the dimming control device according to any one of claims 6 to 8.

10. A dimming control method, comprising: generating a dimming control signal based on the dimming signal for the lamp, generating a switch control signal based on the dimming control signal to control the power supply to the lamp, Wherein, when the time of the on phase of the dimming signal is greater than or equal to the preset time, in the off phase of the dimming signal, the dimming control signal is turned off in unison with the dimming signal, and the switch control signal is turned off synchronously; When the time of the on phase of the dimming signal is less than the preset time, in the off phase of the dimming signal, the dimming control signal is delayed by at least one cycle of the switch control signal relative to the dimming signal before being turned off, and the switch control signal is turned off after continuing for at least one cycle.

11. The dimming control method according to claim 10, wherein generating the dimming control signal based on the dimming signal for the lamp comprises: Determining a time of an on phase of the dimming signal, and comparing the determined time of the on phase of the dimming signal with a preset time; When the comparison result indicates that the time during the on-phase of the dimming signal is greater than or equal to the preset time, generating a first control signal consistent with the dimming signal during the off-phase of the dimming signal; When the comparison result indicates that the time of the on phase of the dimming signal is less than the preset time, generating a second control signal in the off phase of the dimming signal that is turned off after delaying the switch control signal by at least one cycle relative to the dimming signal; as well as The first control signal or the second control signal is provided as the dimming control signal.

12. The dimming control method according to claim 10, wherein generating the dimming control signal based on the dimming signal for the lamp further comprises: In the on-state of the dimming signal, a control signal consistent with the dimming signal is generated, and The switch control signals are turned on synchronously. 13 . The dimming control device according to claim 10 , wherein the dimming signal is a high-frequency pulse width modulation (PWM) signal.

Images