Light emitting diode driving system, driving device and brightness control circuit

Abstract

A light-emitting diode driving system, a driving device and a brightness control circuit, the system comprises a power supply module, N light-emitting modules, N driving current generating modules, and a brightness adjustment module, each light-emitting module receives a supply voltage provided by the power supply module, each driving current generating module provides a driving current to the corresponding light-emitting module according to a periodic conduction signal and an amplitude control signal, each light-emitting module generates a channel voltage inversely proportional to the amplitude of the driving current according to the supply voltage and the driving current, the brightness adjustment module detects each channel voltage and compares it with a saturation lower limit voltage to generate the amplitude control signal and the periodic conduction signal to the driving current generating module accordingly, when the channel voltage is greater than the saturation lower limit voltage, the current amplitude of the amplitude control signal is increased. In this way, each channel voltage is adjusted to reduce the power consumption of the corresponding driving current generating module.

Description

Technical Field

[0001] The present invention relates to a driving technology in the field of lighting, and in particular to a light emitting diode driving system, a driving device and a brightness control circuit that can maintain brightness and reduce power consumption. Background Art

[0002] See also Figure 1 , is an existing light-emitting diode driving system, comprising a power supply 11 for providing a driving voltage, a plurality of light-emitting diode strings 12 electrically connected to the power supply 11, a plurality of switches 13 electrically connected to the light-emitting diode strings 12, a plurality of current sources 14 electrically connected to the switches 13, and a brightness distributor 15 electrically connected to the switches 13 and the current sources 14.

[0003] Due to the influence of process variables, the forward conduction voltages of the plurality of LEDs 121 connected in series in each LED string 12 are different, so that the voltage across each LED string 12 is different. To ensure that each LED string 12 can receive the required current ILED, the existing method is to increase the driving voltage provided by the power supply 11 so that each switch 13 is operated in a saturation region or a linear region and turned on, thereby forming a channel so that the current provided by each current source 14 flows through the corresponding LED string 12. However, in this way, the switches 13 corresponding to some LED strings 12 with lower voltage across the line will receive a higher conduction voltage, thereby increasing power consumption and causing overheating problems.

[0004] For example, assuming that the voltage across one LED string 12 is 30V, the voltage across another LED string 12 is 32V, and the minimum operating saturation voltage of each switch 13 forming a channel is 0.5V, to ensure that the LED strings 12 can operate normally at the rated current, the driving voltage provided by the power supply 11 must be increased to 32.5V to ensure that the LED strings 12 can emit light normally. However, at this time, the channel voltage will be 2.5V higher, resulting in excess power consumption and heat. Therefore, the circuit architecture of the existing LED driving system needs to be improved. Summary of the invention

[0005] An object of the present invention is to provide a light emitting diode driving system with reduced power consumption.

[0006] The light emitting diode driving system of the present invention comprises a power supply module, N light emitting modules, N driving current generating modules, and a brightness adjusting module.

[0007] The power supply module is used for generating a supply voltage.

[0008] Each light emitting module has a first end electrically connected to the power supply module to receive the supply voltage and a second end, N≥2, and N is a positive integer.

[0009] Each driving current generating module is electrically connected between the second end of the corresponding light-emitting module and the ground, and provides a channel voltage and a driving current to the second end of the corresponding light-emitting module according to a periodic conduction signal and an amplitude control signal. The periodic conduction signal indicates the duty cycle of each cycle time, and the amplitude control signal indicates a current amplitude. The operating voltage of each light-emitting module is proportional to the corresponding amplitude of the driving current, and the channel voltage is proportional to the voltage difference between the supply voltage and the operating voltage of the light-emitting module.

[0010] The brightness adjustment module is electrically connected to the driving current generating module and the second end of each light-emitting module, and detects the channel voltage of each driving current generating module, and compares the channel voltage with a saturation lower limit voltage to correspondingly generate the amplitude control signal and the periodic conduction signal to the driving current generating module. When the channel voltage is greater than the saturation lower limit voltage, the current amplitude of the amplitude control signal is increased.

[0011] In the light emitting diode driving system of the present invention, the brightness adjustment module further reduces the duty cycle so that the product of the increased current amplitude and the reduced duty cycle maintains a constant brightness value.

[0012] The light emitting diode driving system of the present invention, the brightness adjustment module includes a supply voltage adjustment device, the supply voltage adjustment device also presets an upper limit comparison voltage not higher than the maximum of the working voltages, and a lower limit comparison voltage not lower than the minimum of the working voltages,

[0013] When any channel voltage is less than the lower limit comparison voltage, the supply voltage adjustment device controls the supply voltage of the power supply module to increase.

[0014] When the supply voltage adjustment device determines that each channel voltage is greater than the upper limit comparison voltage, the supply voltage adjustment device controls the supply voltage provided by the power supply module to decrease.

[0015] The light emitting diode driving system of the present invention further comprises a first resistor and a second resistor.

[0016] The first resistor includes a first end electrically connected to the power supply module to receive the supply voltage, and a second end. The second resistor includes a first end electrically connected to the second end of the first resistor, and a second end grounded.

[0017] The supply voltage adjustment device includes N high voltage comparators, N low voltage comparators, a first logic gate, a second logic gate, a supply voltage feedback adjustment module, and a current source.

[0018] Each high potential comparator has a second end electrically connected to the light emitting module to receive a non-inverting end of the channel voltage, an inverting end receiving the upper limit comparison voltage, and an output end. Each low potential comparator has a second end electrically connected to the light emitting module to receive an inverting end of the channel voltage, a non-inverting end receiving the lower limit comparison voltage, and an output end. The first logic gate has a plurality of receiving ends electrically connected to the output end of the high potential comparator, and an output end. The second logic gate has a plurality of receiving ends electrically connected to the output end of the low potential comparator, and an output end. The supply voltage feedback adjustment module has a reset end electrically connected to the output end of the first logic gate, a reset end electrically connected to the output end of the second logic gate, and a reset end electrically connected to the output end of the first logic gate. The current source comprises a setting terminal of the output terminal of the gate, and an output terminal, the current source is used to generate an adjustment current, and is electrically connected between the common terminal of the first resistor and the second resistor and the ground, and the magnitude of the adjustment current is controlled by the logic signal generated by the output terminal of the supply voltage feedback adjustment module. When the output signal of the output terminal of each high-voltage comparator is logic 1, the adjustment current is controlled to decrease by a change amount. When the output signal of the output terminal of any low-voltage comparator is logic 1, the adjustment current is controlled to increase by a change amount. When the output signals of the output terminals of each low-voltage comparator are all logic 0, and the output signals of the output terminals of each high-voltage comparator are not all logic 1, the supply voltage feedback adjustment module does not adjust the adjustment current.

[0019] The light-emitting diode driving system of the present invention also includes a fault judgment circuit. When the fault judgment circuit judges that the channel voltage corresponding to any light-emitting module is lower than an open-circuit comparison voltage, the brightness adjustment module outputs an open-circuit fault signal, and the open-circuit fault signal indicates that the light-emitting module is in an open-circuit state. When the brightness adjustment module judges that the channel voltage corresponding to any light-emitting module is higher than a short-circuit comparison voltage, the brightness adjustment module outputs a short-circuit fault signal, and the short-circuit fault signal indicates that the light-emitting module is in a short-circuit state. The channel voltage is the difference between the supply voltage and the working voltage corresponding to the light-emitting module.

[0020] The light emitting diode driving system of the present invention, the fault judgment circuit also includes N open circuit comparators and N short circuit comparators,

[0021] Each open circuit comparator has an inverting end electrically connected to the second end of the light emitting module to receive the channel voltage, a non-inverting end receiving the open circuit comparison voltage, and an output end. When each open circuit comparator determines that the channel voltage received by each open circuit comparator is lower than the open circuit comparison voltage, the open circuit comparator outputs the open circuit fault signal from the output end.

[0022] Each short-circuit comparator has a non-inverting end electrically connected to the second end of the light-emitting module to receive the channel voltage, an inverting end receiving the short-circuit comparison voltage, and an output end. When each short-circuit comparator determines that the channel voltage received by each short-circuit comparator is higher than the short-circuit comparison voltage, the short-circuit comparator outputs the short-circuit fault signal from the output end.

[0023] In the light-emitting diode driving system of the present invention, each driving current generating module comprises a switch for receiving the periodic conduction signal and a current source for receiving the amplitude control signal. The switch comprises a first end electrically connected to the second end of the light-emitting module and providing the channel voltage, a control end electrically connected to the brightness adjustment module to receive the periodic conduction signal, and a second end. The switch operates in one of a conducting state and a non-conducting state according to the duty cycle of the received periodic conduction signal. The current source is electrically connected between the second end of the switch and the ground and is used to generate the driving current according to the received amplitude control signal.

[0024] The light-emitting diode driving system of the present invention further includes a first resistor and a second resistor. The power supply module includes a boost inductor, a transistor, a boost diode, and an output capacitor. The boost inductor has a first end for receiving an input voltage and a second end. The transistor has a first end electrically connected to the second end of the boost inductor, a control end electrically connected to the brightness adjustment module, and a second end connected to ground. The boost diode has an anode end electrically connected to the second end of the boost inductor and a cathode end electrically connected to the first end of the first resistor. The output capacitor has a first end electrically connected to the cathode end of the boost diode and providing a supply voltage, and a second end connected to ground.

[0025] In the LED driving system of the present invention, the relationship between the supply voltage and a regulating current is: V out For the supply voltage, V FB is the voltage between the first resistor and the second resistor, R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, I FBO For the regulation current.

[0026] The light emitting diode driving system of the present invention, the brightness adjustment module includes a channel voltage adjustment device, the channel voltage adjustment device compares whether the channel voltage of the driving current generating module is greater than a minimum saturation voltage, and if so, adjusts the amplitude control signal to increase the amplitude of the corresponding driving current to reduce the channel voltage.

[0027] In the light-emitting diode driving system of the present invention, if not, the channel voltage adjustment device stops increasing the amplitude of the driving current and records an increase percentage as a compensation coefficient, wherein the increase percentage is proportional to a ratio of the amplitude of the driving current corresponding to when the channel voltage is the lowest saturation voltage to the amplitude of the driving current before adjustment, and the channel voltage adjustment device adjusts the duty cycle according to the compensation coefficient.

[0028] The light emitting diode driving system of the present invention comprises a multiplexer, a comparator, a channel voltage feedback adjustment module, and a brightness distributor. The multiplexer is used to receive multiple channel voltages and a selection signal, and output one of the multiple channel voltages according to the selection signal. The comparator receives the lowest saturation voltage and is electrically connected to the multiplexer to receive the channel voltage outputted by the multiplexer, and provides a comparison result after comparing the lowest saturation voltage with the channel voltage. The channel voltage feedback adjustment module is electrically connected to the multiplexer to provide the selection signal and is electrically connected to the comparator to receive the comparison result, and generates an output according to the comparison result. The brightness distributor receives a brightness value and is electrically connected to the channel voltage feedback adjustment module and the driving current generating module, and generates the periodic conduction signal and the amplitude control signal to the driving current generating module corresponding to the comparison result according to the output of the channel voltage feedback adjustment module.

[0029] Furthermore, another object of the present invention is to provide a driving device with reduced power consumption.

[0030] The driving device of the present invention is suitable for driving N light-emitting modules, each light-emitting module has a first end and a second end, N≥2, N is a positive integer, and the driving device includes a power supply module, N driving current generating modules, and a brightness adjustment module.

[0031] The power supply module is used for generating a supply voltage to the first end of each light emitting module.

[0032] Each driving current generating module is electrically connected between the second end of the corresponding light-emitting module and the ground, and provides a channel voltage and a driving current to the second end of the corresponding light-emitting module according to a periodic conduction signal and an amplitude control signal. The periodic conduction signal indicates the duty cycle of each cycle time, and the amplitude control signal indicates a current amplitude. The operating voltage of each light-emitting module is proportional to the corresponding amplitude of the driving current, and the channel voltage is proportional to the voltage difference between the supply voltage and the operating voltage of the light-emitting module.

[0033] The brightness adjustment module is electrically connected to the driving current generating module and the second end of each light-emitting module, and detects the channel voltage of each driving current generating module, and compares the channel voltage with a saturation lower limit voltage to correspondingly generate the amplitude control signal and the periodic conduction signal to the driving current generating module. When the channel voltage is greater than the saturation lower limit voltage, the current amplitude of the amplitude control signal is increased.

[0034] The driving device of the present invention, the brightness adjustment module includes a supply voltage adjustment device, the supply voltage adjustment device also presets an upper limit comparison voltage not higher than the maximum of the working voltages, and a lower limit comparison voltage not lower than the minimum of the working voltages. When any channel voltage is less than the lower limit comparison voltage, the supply voltage adjustment device controls the supply voltage of the power supply module to increase. When the supply voltage adjustment device determines that each channel voltage is greater than the upper limit comparison voltage, the supply voltage adjustment device controls the supply voltage provided by the power supply module to decrease.

[0035] The driving device of the present invention comprises N high potential comparators, N low potential comparators, a first logic gate, a second logic gate, a supply voltage feedback adjustment module, and a current source. Each high potential comparator has a second end electrically connected to the light-emitting module to receive a non-inverting end of the channel voltage, an inverting end receiving the upper limit comparison voltage, and an output end. Each low potential comparator has a second end electrically connected to the light-emitting module to receive an inverting end of the channel voltage, a non-inverting end receiving the lower limit comparison voltage, and an output end. The first logic gate has a plurality of receiving ends electrically connected to the output ends of the high potential comparators, and an output end. The second logic gate has A plurality of receiving ends respectively electrically connected to the output ends of the low potential comparators, and an output end, the supply voltage feedback adjustment module has a reset end electrically connected to the output end of the first logic gate, a set end electrically connected to the output end of the second logic gate, and an output end, the current source is used to generate a regulating current, the magnitude of the regulating current is used to control the magnitude of the supply voltage, and the magnitude of the regulating current is controlled by the logic signal generated by the output end of the supply voltage feedback adjustment module, when the output signal of the output end of each high potential comparator is logic 1, the regulating current is controlled to decrease by a variation, and when the output signal of the output end of any low potential comparator is logic 1, the regulating current is controlled to increase by a variation.

[0036] The driving device of the present invention, the brightness adjustment module includes a channel voltage adjustment device, the channel voltage adjustment device compares whether the channel voltage of the driving current generating module is greater than a minimum saturation voltage, if so, adjusts the amplitude control signal to increase the corresponding amplitude of the driving current to reduce the channel voltage, if not, the channel voltage adjustment device stops increasing the amplitude of the driving current, and records an increase percentage as a compensation coefficient, the increase percentage is proportional to the ratio of the amplitude of the driving current corresponding to the minimum saturation voltage when the channel voltage is the minimum saturation voltage to the amplitude of the driving current before adjustment, and the channel voltage adjustment device adjusts the duty cycle according to the compensation coefficient.

[0037] The driving device of the present invention comprises a multiplexer, a comparator, a channel voltage feedback adjustment module, and a brightness distributor. The multiplexer is used to receive multiple channel voltages and a selection signal, and output one of the multiple channel voltages according to the selection signal. The comparator receives the lowest saturation voltage and is electrically connected to the multiplexer to receive the channel voltage outputted by the multiplexer, and provides a comparison result after comparing the lowest saturation voltage with the channel voltage. The channel voltage feedback adjustment module is electrically connected to the multiplexer to provide the selection signal and is electrically connected to the comparator to receive the comparison result, and generates an output according to the comparison result. The brightness distributor receives a brightness value and is electrically connected to the channel voltage feedback adjustment module and the drive current generating module, and generates the periodic conduction signal and the amplitude control signal to the drive current generating module corresponding to the comparison result according to the output of the channel voltage feedback adjustment module.

[0038] The driving device of the present invention also includes a fault judgment circuit. When the fault judgment circuit judges that the channel voltage corresponding to any light-emitting module is lower than an open-circuit comparison voltage, the brightness adjustment module outputs an open-circuit fault signal, and the open-circuit fault signal indicates that the light-emitting module is in an open-circuit state. When the brightness adjustment module judges that the channel voltage corresponding to any light-emitting module is higher than a short-circuit comparison voltage, the brightness adjustment module outputs a short-circuit fault signal, and the short-circuit fault signal indicates that the light-emitting module is in a short-circuit state. The channel voltage is the difference between the supply voltage and the working voltage corresponding to the light-emitting module.

[0039] Still another object of the present invention is to provide a brightness control circuit that reduces power consumption.

[0040] The brightness control circuit of the present invention is electrically connected to N light-emitting modules, each of which has a first end receiving a supply voltage and a second end, N≥2, N is a positive integer, and the brightness control circuit includes N driving current generating modules and a brightness adjusting module.

[0041] Each driving current generating module is electrically connected between the second end of the corresponding light-emitting module and the ground, and provides a channel voltage and a driving current to the second end of the corresponding light-emitting module according to a periodic conduction signal and an amplitude control signal. The periodic conduction signal indicates the duty cycle of each cycle time, and the amplitude control signal indicates a current amplitude. The operating voltage of each light-emitting module is proportional to the corresponding amplitude of the driving current, and the channel voltage is proportional to the voltage difference between the supply voltage and the operating voltage of the light-emitting module.

[0042] The brightness adjustment module is electrically connected to the driving current generating module and the second end of each light-emitting module, and detects the channel voltage of each driving current generating module, and compares the channel voltage with a saturation lower limit voltage to correspondingly generate the amplitude control signal and the periodic conduction signal to the driving current generating module. When the channel voltage is greater than the saturation lower limit voltage, the current amplitude of the amplitude control signal is increased.

[0043] The effect of the present invention is that the brightness adjustment module controls the current amplitude of the amplitude control signal according to the comparison between the channel voltage and the saturation lower limit voltage, thereby adjusting each channel voltage to reduce the power consumption of the corresponding driving current generating module. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the accompanying drawings:

[0045] Figure 1 is a circuit diagram of an existing light emitting diode driving system;

[0046] Figure 2 is a circuit diagram of an embodiment of a light emitting diode driving system of the present invention;

[0047] Figure 3 is a circuit diagram of the brightness adjustment module of this embodiment;

[0048] Figure 4 is a flow chart of a supply voltage adjustment process performed by an embodiment;

[0049] Figure 5 is a circuit diagram of the supply voltage adjustment device of the embodiment;

[0050] Figure 6 is a schematic diagram of channel voltage regulation of this embodiment;

[0051] Figure 7 is a circuit diagram of the power supply module of this embodiment;

[0052] Figure 8 is a circuit diagram of the channel voltage adjustment device of the embodiment;

[0053] Fig. 9 is a flow chart of a process for adjusting the channel voltage according to the embodiment; and

[0054] Fig.10 is a circuit diagram of the fault judgment circuit of this embodiment. DETAILED DESCRIPTION

[0055] See also Figure 2 , 7 An embodiment of the light emitting diode driving system of the present invention comprises a driving device 1, N light emitting modules 3, a first resistor 6, and a second resistor 7. The driving device 1 comprises a power supply module 2, a brightness control circuit 11 and a fault judgment circuit 12 (see Fig.10 The brightness control circuit 11 includes N driving current generating modules 4 and a brightness adjusting module 5 .

[0056] The power supply module 2 is used to generate a supply voltage.

[0057] Each light-emitting module 3 has a first end 31 and a second end 32 electrically connected to the power supply module 2 to receive the supply voltage, N≥2, N is a positive integer, and each light-emitting module 3 is composed of a plurality of light-emitting diodes connected in series. Due to the influence of process variation, the conduction voltage of each light-emitting diode is not exactly the same. Therefore, each light-emitting module 3 corresponds to a working voltage, and each working voltage is the sum of the conduction voltages of each light-emitting diode of each light-emitting module 3. The working voltage of each light-emitting module 3 is the voltage across the first end 31 and the second end 32. In addition, the first end 31 of each light-emitting module 3 is the anode end of the first one of the light-emitting diodes connected in series to form the light-emitting module 3, and the second end 32 of each light-emitting module 3 is the cathode end of the last one of the light-emitting diodes connected in series to form the light-emitting module 3.

[0058] Each driving current generating module 4 is electrically connected to the second end 32 of the corresponding light-emitting module 3, and provides a driving current to the second end 32 of the corresponding light-emitting module 3 according to a periodic conduction signal and an amplitude control signal, wherein the periodic conduction signal indicates a duty cycle of each periodic time, and the amplitude control signal indicates a current amplitude. The second end 32 of each light-emitting module 3 generates a channel voltage according to the supply voltage and the driving current, that is, each channel voltage is the difference between the supply voltage and the operating voltage of each light-emitting module 3 itself, and the channel voltage is inversely proportional to the amplitude of the driving current. In more detail, each driving current generating module 4 includes a switch 41 receiving the periodic conduction signal, and a current source 41 receiving the amplitude control signal. 2, the switch 41 includes a first end 411 electrically connected to the second end 31 of the light emitting module 3, a control end 412 electrically connected to the brightness adjustment module 5 to receive the periodic conduction signal, and a second end 413 electrically connected to the current source 42, the switch 41 operates in one of a conducting state and a non-conducting state according to the duty cycle of the received periodic conduction signal, the current source 42 generates the driving current according to the received amplitude control signal when the switch 41 operates in the conducting state, and the working voltage of the driving current generating module 4 is the channel voltage corresponding to the second end 32 of the light emitting module 3 (that is, the cross voltage between the first end 411 of the corresponding switch 41 and the ground), that is, the channel voltage (VCH1, VCH2, Figure 1 For the convenience of explanation, only two groups of channel voltages are indicated, but the number is not limited to this).

[0059] The brightness adjustment module 5 is electrically connected to the driving current generating module 4 and the second end of each light-emitting module 3, and detects the channel voltage of the second end of each light-emitting module 3, and compares the channel voltage with a saturation lower limit voltage to correspondingly generate the amplitude control signal and the periodic conduction signal to the driving current generating module 4. When the channel voltage is greater than the saturation lower limit voltage, the current amplitude of the amplitude control signal is increased.

[0060] More specifically, the brightness adjustment module 5 generates a corresponding periodic conduction signal and an amplitude control signal according to a received brightness value. Since the brightness value is the product of the periodic conduction signal and the amplitude control signal, and the conduction voltage of the light-emitting diode is proportional to the driving current flowing through the light-emitting diode, that is, the corresponding working voltage of each light-emitting module 3 is proportional to the driving current flowing through. When the brightness remains unchanged, the conduction voltage of the light-emitting diode can be increased by increasing the current amplitude of the amplitude control signal, that is, the corresponding working voltage of the light-emitting module 3, and at the same time, the duty cycle of the periodic conduction signal is reduced to keep the product of the two unchanged. That is, the brightness adjustment module 5 reduces the duty cycle according to the received brightness value, so that the product of the increased current amplitude and the reduced duty cycle maintains a constant brightness value. Since the cross-voltage of the light-emitting module 3 increases, the channel voltage of the driving current generating module 4 is reduced, so that the power consumption and heat are reduced. In conjunction with the following example, for example, the rated current of a light-emitting module 3 (group A) is 30mA, its working voltage is 30V, and the working voltage of another light-emitting module 3 (group B) is 20V. The voltage is 32V, and the minimum working voltage of the driving current generating module 4 is 0.5V. Since it is necessary to ensure that all the light-emitting modules of groups A and B are normally lit, the supply voltage needs to be 32.5V. However, the channel voltage of the driving current generating module 4 of group A will be as high as 2.5V. The rated current of the light-emitting module 3 (group A) with an original working voltage of 30V is increased by the method of this case until it has the same working voltage of 32V as another light-emitting module 3, then the channel voltage of the corresponding driving current generating module 4 will drop to 0.5V. If the rated current is increased to 33mA at this time, it means that the compensation coefficient (CV) = 1.1 times, and the duty cycle of the periodic conduction signal must be set to PDIM*1 / compensation coefficient (CV) to maintain brightness consistency. The compensation coefficient can be designed to take the minimum variable unit, so that the channel power consumption of the driving current generating module 4 corresponding to the light-emitting module 3 (group A) with an original working voltage of 30V is 2.5*30mA=75mW, and the improved power consumption is 0.5*33mA*1 / 1.1=15mW.

[0061] The first resistor 6 includes a first end 61 electrically connected to the power supply module 2 to receive the supply voltage, and a second end 62 .

[0062] The second resistor 7 includes a first end 71 electrically connected to the second end 62 of the first resistor 6 , and a second end 72 grounded.

[0063] like Figure 3 As shown, the brightness adjustment module 5 includes a supply voltage adjustment device 8 and a channel voltage adjustment device 9. Next, a supply voltage adjustment process and a channel voltage adjustment process of this embodiment are described in more detail.

[0064] Supply voltage adjustment process:

[0065] like Figure 4 As shown, the description of executing a supply voltage adjustment process (first step) in this embodiment is as follows:

[0066] The brightness adjustment module 5 presets an upper limit comparison voltage (VH) not higher than the maximum of the working voltages, and a lower limit comparison voltage (VL) not lower than the minimum of the working voltages. The supply voltage adjustment device 8 of the brightness adjustment module 5 receives each channel voltage, and then the supply voltage adjustment device 8 determines whether any channel voltage is less than the lower limit comparison voltage (VL). If so (when any channel voltage is less than the lower limit comparison voltage), the supply voltage adjustment device 8 increases the adjustment current to increase the supply voltage until all channel voltages are greater than the lower limit comparison voltage (VL). If not (when all channel voltages are greater than the lower limit comparison voltage), the supply voltage adjustment device 8 determines whether all channel voltages are greater than an upper limit comparison voltage (VH). If so, the supply voltage adjustment device 8 reduces the adjustment current to reduce the supply voltage until any channel voltage is less than the lower limit comparison voltage (VL). If not (when all channel voltages are greater than the lower limit comparison voltage, and any channel voltage is between VL and VH), the supply voltage adjustment device 8 is completed.

[0067] like Figure 5 As shown, the supply voltage adjustment device 8 includes N high level comparators 51 , N low level comparators 52 , a first logic gate 53 , a second logic gate 54 , a supply voltage feedback adjustment module 55 , and a current source 56 .

[0068] Each high potential comparator 51 has a non-inverting terminal 511 electrically connected to the second terminal 32 of a light emitting module 3 to receive the channel voltage, an inverting terminal 512 receiving the upper limit comparison voltage, and an output terminal 513 .

[0069] Each low potential comparator 52 has an inverting terminal 521 electrically connected to the second terminal 32 of a light emitting module 3 to receive the channel voltage, a non-inverting terminal 522 receiving the lower limit comparison voltage, and an output terminal 523 .

[0070] The first logic gate 53 is an AND gate having a plurality of receiving terminals 531 electrically connected to the output terminals 513 of the high potential comparator 51 , and an output terminal 532 .

[0071] The second logic gate 54 is an OR gate having a plurality of receiving terminals 541 electrically connected to the output terminals 523 of the low potential comparator 52 , and an output terminal 542 .

[0072] The supply voltage feedback adjustment module 55 has a reset terminal 551 electrically connected to the output terminal 532 of the first logic gate 53, a set terminal 552 electrically connected to the output terminal 542 of the second logic gate 54, and an output terminal 553. Figure 6 For example, and referring to the following truth table (I), three groups of channel voltages are respectively VCH1 to VCH3, but the present invention is not limited thereto.

[0073] Truth table (I)

[0074]

[0075]

[0076] That is, the current source 56 is electrically connected between the common end of the first resistor 6 and the second resistor 7 and the ground, and is controlled by the logic signal generated by the output end 553 of the supply voltage feedback adjustment module 55 to adjust the magnitude of the current.

[0077] When the output signal of the output terminal 523 of any low voltage comparator 52 is logic 1, the supply voltage feedback adjustment module 55 controls the regulation current to increase by a change amount per unit time.

[0078] When the output signal of the output terminal 513 of each high potential comparator 51 is logic 1, the current source 56 controls the regulating current to decrease by a variable amount until the output signal of the output terminal 523 of any low potential comparator 52 is logic 1.

[0079] In addition, when the output signals of the output terminal 523 of the low potential comparator 52 are all logic 0, and the output signals of the output terminal 513 of the high potential comparator 51 are not all logic 1, the current source 56 does not adjust the regulating current. In detail, when the channel voltage VCH received by the inverting terminal 521 of the low potential comparator 52 is greater than the lower limit comparison voltage VL received by the corresponding non-inverting terminal 522, and when the channel voltage VCH received by the non-inverting terminal 511 of the high potential comparator 51 is not all greater than the upper limit comparison voltage received by the corresponding inverting terminal 512, the current source 56 does not adjust the regulating current.

[0080] Related References Figure 7 Next, the specific circuit structure of the power supply module 2 in the supply voltage adjustment process is described, and the relationship between the supply voltage and a regulating current is described in conjunction with the brightness adjustment module 5.

[0081] The power supply module 2 includes a boost inductor 21 , a transistor 22 , a boost diode 23 , an output capacitor 24 , and a pulse controller 25 .

[0082] The boost inductor 21 has a first terminal 211 for receiving an input voltage, and a second terminal 212 .

[0083] The transistor 22 has a first terminal 221 electrically connected to the second terminal 212 of the boost inductor 21, a control terminal 222 electrically connected to the pulse controller 25, and a second terminal 223 electrically connected to the ground. FB The duty ratio of the transistor 22 is controlled.

[0084] The boost diode 23 has an anode terminal 231 electrically connected to the second terminal 212 of the boost inductor 21 , and a cathode terminal 232 electrically connected to the first terminal 61 of the first resistor 6 .

[0085] The output capacitor 24 has a first terminal 241 electrically connected to the cathode terminal 232 of the boost diode 23 and providing the supply voltage, and a second terminal 242 grounded.

[0086] The relationship between the supply voltage and the regulation current is: V out For the supply voltage, V FB is the voltage at the common end of the first resistor 6 and the second resistor 7, R1 is the resistance value of the first resistor 6, R2 is the resistance value of the second resistor 7, I FBO For the regulation current.

[0087] Therefore, when the supply voltage rises to the set rated voltage When the channel voltage of each driving current generating module 4 needs to be maintained at a voltage corresponding to the saturation region to maintain the driving current, Figure 3 The circuit judges that when any channel voltage is less than the lower limit comparison voltage VL, the supply voltage feedback adjustment module 55 increases the adjustment current in sequence per unit time to increase the supply voltage until all channel voltages are greater than the lower limit comparison voltage VL. When all channel voltages are greater than the upper limit comparison voltage VH, the supply voltage feedback adjustment module 55 decreases the adjustment current in sequence per unit time to decrease the supply voltage until any channel voltage is less than the lower limit comparison voltage VL. When all channel voltages are greater than the lower limit comparison voltage VL, and any channel voltage is between the upper limit comparison voltage VH and the lower limit comparison voltage VL, the adjustment current is kept unchanged. However, the upper limit comparison voltage VH and the lower limit comparison voltage VL need to be set within a reasonable range to avoid the hunting phenomenon.

[0088] Channel voltage adjustment process:

[0089] like Figure 8As shown, the channel voltage adjustment device 9 includes a multiplexer 91 , a comparator 92 , a channel voltage feedback adjustment module 93 , a brightness distributor 94 , and an oscillator 95 .

[0090] like Fig. 9 As shown, the channel voltage adjustment device 9 of the brightness adjustment module 5 executes a channel voltage adjustment process (second step). The multiplexer of the channel voltage adjustment device 9 receives multiple channel voltages and a selection signal provided by the channel voltage feedback adjustment module 93, and outputs one of the multiple channel voltages according to the selection signal. The comparator 92 compares each channel voltage one by one whether it is greater than a minimum saturation voltage (Vminsat). If so, the brightness distributor 94 adjusts the amplitude control signal (ADIM) to increase the corresponding amplitude of the driving current to reduce the channel voltage. If not, the channel voltage feedback adjustment module stops increasing the amplitude of the driving current and records an increase percentage as a compensation coefficient (CV). The increase percentage is proportional to the ratio of the amplitude of the driving current corresponding to the minimum saturation voltage when the channel voltage is the minimum saturation voltage to the amplitude of the driving current before adjustment, and the compensation coefficient (CV) is transmitted to the brightness distributor 94. The brightness distributor 94 of the channel voltage adjustment device 9 adjusts the duty cycle according to the compensation coefficient, and then completes the channel voltage adjustment process.

[0091] Here, it is further explained that since each light-emitting module 3 has a different conduction voltage, several corresponding channel voltages will be higher than the minimum saturation voltage, that is, much higher than the saturation lower limit voltage. In order to achieve the best efficiency, the channel voltage must be adjusted. Since the conduction voltage of the light-emitting module 3 is proportional to the received driving current, and the luminous brightness is the product of the amplitude control signal and the periodic conduction signal, the brightness adjustment module 5 sequentially increases the current amplitude of the amplitude control signal to reduce the channel voltage to a preset lower limit value, that is, when it drops to the minimum saturation voltage, stop increasing the current amplitude of the amplitude control signal, and record it. The percentage of increase is recorded as the compensation coefficient (CV). In order to maintain the consistency of the luminous brightness, when the current amplitude of the amplitude control signal increases by a percentage (CV), the duty cycle of the periodic conduction signal must be reduced by the same percentage (CV). The correction formula is BV=PDIM(1 / CV)*ADIM(CV), BV is the brightness value, PDIM is the duty cycle of the periodic conduction signal, and ADIM is the current amplitude of the amplitude control signal. This makes the channel voltage corresponding to each light-emitting module 3 operate at the minimum saturation voltage, thereby achieving low power consumption and low heat generation. The minimum saturation voltage can be set to be the same as the lower limit comparison voltage.

[0092] Through the aforementioned channel voltage regulation mechanism, the cross-voltage of each driving current generating module 4 will be close to the minimum saturation voltage. When the switch 41 is turned on, if the light-emitting diode of the corresponding light-emitting module 3 fails, the embodiment can also determine the fault condition of the light-emitting module 3 according to the voltage change of the light-emitting module 3 through the brightness adjustment module 5. Specifically, when the brightness adjustment module 5 determines that the channel voltage corresponding to any light-emitting module 3 is lower than an open-circuit comparison voltage, the brightness adjustment module 5 outputs an open-circuit fault signal, and the open-circuit fault signal indicates that the light-emitting module is in an open-circuit state; when the brightness adjustment module 5 determines that the channel voltage corresponding to any light-emitting module 3 is higher than a short-circuit comparison voltage, the brightness adjustment module 5 outputs a short-circuit fault signal, and the short-circuit fault signal indicates that the light-emitting module 3 is in a short-circuit state. Then, a third step is used to describe in more detail the detailed circuit of the brightness adjustment module 5 for detecting the fault of the light-emitting module 3.

[0093] Determine the fault (third step):

[0094] See also Fig.10 , further illustrating the detailed circuit architecture of the fault judgment circuit 12 for judging the fault condition of the light emitting module 3 . The fault judgment circuit 12 also includes N open-circuit comparators 57 and N short-circuit comparators 58 .

[0095] Each open circuit comparator 57 has an inverting terminal 571 electrically connected to the second terminal 32 of the light-emitting module 3 to receive the channel voltage, a non-inverting terminal 572 receiving the open circuit comparison voltage, and an output terminal. When each open circuit comparator 57 determines that the channel voltage received by each open circuit comparator is lower than the open circuit comparison voltage, the open circuit comparator outputs the open circuit fault signal from the output terminal.

[0096] Each short-circuit comparator 58 has a non-inverting terminal 581 electrically connected to the second terminal 32 of the light-emitting module 3 to receive the channel voltage, an inverting terminal 582 receiving the short-circuit comparison voltage, and an output terminal. When each short-circuit comparator 58 determines that the channel voltage received by each short-circuit comparator 58 is higher than the short-circuit comparison voltage, the short-circuit comparator 58 outputs the short-circuit fault signal from the output terminal.

[0097] The fault judgment circuit 12 further summarizes the fault mechanism of the light emitting module 3 as follows: when N light emitting diodes in a light emitting module 3 are short-circuited, the channel voltage of the corresponding driving current generating module 4 will increase by VF×N potential, where VF is the unit working voltage of the light emitting module 3. When the channel voltage is greater than the short-circuit detection voltage, the output terminal output signal of the corresponding short-circuit comparator 58 is logic 1; when the switch 41 is turned on, if the light emitting diode of the corresponding light emitting module 3 is open-circuited, its channel voltage is close to zero. At this time, since the channel voltage is less than the open-circuit detection voltage, the output terminal output signal of the corresponding open-circuit comparator 57 is logic 1, the short-circuit detection voltage is set to be greater than the upper limit comparison voltage (VH), and the open-circuit detection voltage is set to be less than the lower limit comparison voltage (VL); when the switch 41 is turned on, the channel voltage is between the short-circuit detection voltage and the open-circuit detection voltage, the output terminal output signal of the open-circuit comparator 57 is logic 0, and the output terminal output signal of the short-circuit comparator 58 is logic 0.

[0098] In summary, the advantages of the above embodiment are: detecting each channel voltage and comparing it with the saturation lower limit voltage, thereby generating a corresponding amplitude control signal and a periodic conduction signal, thereby improving the power consumption of the driving current generating module 4, achieving the situation of maintaining the brightness of the light-emitting module 3 unchanged, and taking into account the reduction of power consumption and heat of the driving current generating module 4, that is, through the brightness adjustment module 5 according to the change of the channel voltage corresponding to each driving current generating module 4, correspondingly increasing / decreasing the adjustment current to adjust the supply voltage, thereby maintaining any channel voltage between the upper and lower comparison voltages, and when the brightness adjustment module 5 adjusts the current amplitude of the amplitude control signal to adjust the channel voltage, in order to maintain the consistency of the light-emitting brightness, it also correspondingly adjusts the duty cycle of the periodic conduction signal to the same percentage, thereby making the channel voltage corresponding to each driving current generating module 4 operate at the lowest saturation voltage to reduce power consumption. In addition, when the light-emitting diode of the light-emitting module 3 fails, the open circuit comparator 57 and the short circuit comparator 58 of the brightness adjustment module 5 can also be used to judge its failure situation to send a corresponding indication signal, so that the purpose of the present invention can be achieved.

[0099] The above is only a preferred embodiment of the present invention, and should not be used to limit the scope of the present invention. That is, any simple equivalent changes and modifications made according to the claims and description of the present invention are still within the scope of the present invention.

Claims

1. A light emitting diode driving system, characterized in that: Include: A power supply module, used for generating a supply voltage; N light-emitting modules, each light-emitting module having a first end and a second end, the first end being electrically connected to the power supply module to receive the supply voltage, N≥2, N being a positive integer; N driving current generating modules, each driving current generating module is electrically connected between the second end of the corresponding light-emitting module and the ground, and provides a channel voltage and a driving current to the second end of the corresponding light-emitting module according to a periodic conduction signal and an amplitude control signal, the periodic conduction signal indicates a duty cycle of each periodic time, the amplitude control signal indicates a current amplitude, the operating voltage of each light-emitting module is proportional to the corresponding amplitude of the driving current, and the channel voltage is proportional to a voltage difference between the supply voltage and the operating voltage of the light-emitting module; and The brightness adjustment module is electrically connected to the driving current generating module and the second end of each light-emitting module, and detects the channel voltage of each driving current generating module, and compares the channel voltage with the saturation lower limit voltage to correspondingly generate the amplitude control signal and the periodic conduction signal to the driving current generating module. When the channel voltage is greater than the saturation lower limit voltage, the current amplitude of the amplitude control signal is increased.

2. The light emitting diode driving system according to claim 1, characterized in that: The brightness adjustment module further reduces the duty cycle so that the product of the increased current amplitude and the reduced duty cycle maintains a constant brightness value.

3. The light emitting diode driving system according to claim 1, characterized in that: The brightness adjustment module includes a supply voltage adjustment device, and the supply voltage adjustment device also presets an upper limit comparison voltage not higher than the maximum of the working voltages and a lower limit comparison voltage not lower than the minimum of the working voltages. When any channel voltage is less than the lower limit comparison voltage, the supply voltage adjustment device controls the supply voltage of the power supply module to increase. When the supply voltage adjustment device determines that each channel voltage is greater than the upper limit comparison voltage, the supply voltage adjustment device controls the supply voltage provided by the power supply module to decrease.

4. The light emitting diode driving system according to claim 3, characterized in that: Also includes a first resistor and a second resistor, The first resistor includes a first end electrically connected to the power supply module to receive the supply voltage, and a second end, the second resistor includes a first end electrically connected to the second end of the first resistor, and a second end grounded, The supply voltage adjustment device includes N high-voltage comparators, N low-voltage comparators, a first logic gate, a second logic gate, a supply voltage feedback adjustment module, and a current source. Each high potential comparator has a second terminal electrically connected to the light emitting module to receive a non-inverting terminal of the channel voltage, an inverting terminal to receive the upper limit comparison voltage, and an output terminal. Each low potential comparator has a second terminal electrically connected to the light emitting module to receive an inverting terminal of the channel voltage, a non-inverting terminal to receive the lower limit comparison voltage, and an output terminal. The first logic gate has a plurality of receiving ends respectively electrically connected to the output ends of the high potential comparator, and an output end. The second logic gate has a plurality of receiving terminals respectively electrically connected to the output terminals of the low potential comparator, and an output terminal. The supply voltage feedback adjustment module has a reset terminal electrically connected to the output terminal of the first logic gate, a set terminal electrically connected to the output terminal of the second logic gate, and an output terminal. The current source is used to generate a regulating current and is electrically connected between a common end of the first resistor and the second resistor and ground, and the magnitude of the regulating current is controlled by a logic signal generated by an output end of the supply voltage feedback adjustment module. When the output signal of the output terminal of each high potential comparator is logic 1, the regulating current is controlled to decrease by a change amount; when the output signal of the output terminal of any low potential comparator is logic 1, the regulating current is controlled to increase by a change amount. When the output signal of the output terminal of each low-level comparator is logic 0, and the output signal of the output terminal of each high-level comparator is not logic 1, the supply voltage feedback adjustment module does not adjust the regulation current.

5. The light emitting diode driving system according to claim 1, characterized in that: It also includes a fault judgment circuit. When the fault judgment circuit judges that the channel voltage corresponding to any light-emitting module is lower than the open-circuit comparison voltage, the brightness adjustment module outputs an open-circuit fault signal, and the open-circuit fault signal indicates that the light-emitting module is in an open-circuit state. When the brightness adjustment module judges that the channel voltage corresponding to any light-emitting module is higher than the short-circuit comparison voltage, the brightness adjustment module outputs a short-circuit fault signal, and the short-circuit fault signal indicates that the light-emitting module is in a short-circuit state. The channel voltage is the difference between the supply voltage and the operating voltage corresponding to the light-emitting module.

6. The light emitting diode driving system according to claim 5, characterized in that: The fault judgment circuit also includes N open-circuit comparators and N short-circuit comparators. Each open circuit comparator has an inverting end electrically connected to the second end of the light-emitting module to receive the channel voltage, a non-inverting end receiving the open circuit comparison voltage, and an output end. When each open circuit comparator determines that the channel voltage received by each open circuit comparator is lower than the open circuit comparison voltage, the open circuit comparator outputs the open circuit fault signal from the output end. Each short-circuit comparator has a non-inverting end electrically connected to the second end of the light-emitting module to receive the channel voltage, an inverting end receiving the short-circuit comparison voltage, and an output end. When each short-circuit comparator determines that the channel voltage received by each short-circuit comparator is higher than the short-circuit comparison voltage, the short-circuit comparator outputs the short-circuit fault signal from the output end.

7. The light emitting diode driving system according to claim 1, characterized in that: Each driving current generating module comprises a switch for receiving the periodic conduction signal and a current source for receiving the amplitude control signal. The switch comprises a first end electrically connected to the second end of the light-emitting module and providing the channel voltage, a control end electrically connected to the brightness adjustment module to receive the periodic conduction signal, and a second end. The switch operates in one of a conducting state and a non-conducting state according to the duty cycle of the received periodic conduction signal. The current source is electrically connected between the second end of the switch and the ground, and is used to generate the driving current according to the received amplitude control signal.

8. The light emitting diode driving system according to claim 1, characterized in that: It also includes a first resistor and a second resistor. The power supply module includes a boost inductor, a transistor, a boost diode, and an output capacitor. The boost inductor has a first terminal for receiving an input voltage, and a second terminal. The transistor has a first end electrically connected to the second end of the boost inductor, a control end electrically connected to the brightness adjustment module, and a second end grounded. The boost diode has an anode terminal electrically connected to the second end of the boost inductor, and a cathode terminal electrically connected to the first end of the first resistor. The output capacitor has a first terminal electrically connected to the cathode terminal of the boost diode and providing a supply voltage, and a second terminal grounded.

9. The light emitting diode driving system according to claim 8, characterized in that: The relationship between the supply voltage and the regulation current is: V out is the supply voltage, V FB is the voltage between the first resistor and the second resistor, R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, I FBO is the regulating current.

10. The light emitting diode driving system according to claim 1, characterized in that: The brightness adjustment module includes a channel voltage adjustment device, which compares whether the channel voltage of the driving current generating module is greater than the minimum saturation voltage. If so, the amplitude control signal is adjusted to increase the amplitude of the corresponding driving current to reduce the channel voltage.

11. The light emitting diode driving system according to claim 10, characterized in that: If not, the channel voltage adjustment device stops increasing the amplitude of the driving current and records the increase percentage as the compensation coefficient, wherein the increase percentage is proportional to the ratio of the amplitude of the driving current corresponding to the lowest saturation voltage of the channel voltage to the amplitude of the driving current before adjustment, and the channel voltage adjustment device adjusts the duty cycle according to the compensation coefficient.

12. The light emitting diode driving system according to claim 10, characterized in that: The channel voltage adjustment device includes a multiplexer, a comparator, a channel voltage feedback adjustment module, and a brightness distributor. The multiplexer is used to receive a plurality of channel voltages and a selection signal, and output one of the plurality of channel voltages according to the selection signal. The comparator receives the minimum saturation voltage and is electrically connected to the multiplexer to receive the channel voltage outputted from the multiplexer, and provides a comparison result after comparing the minimum saturation voltage with the channel voltage. The channel voltage feedback adjustment module is electrically connected to the multiplexer to provide the selection signal and is electrically connected to the comparator to receive the comparison result, and generates an output according to the comparison result. The brightness distributor receives the brightness value and electrically connects the channel voltage feedback adjustment module and the drive current generating module, and generates the periodic conduction signal and the amplitude control signal to the drive current generating module corresponding to the comparison result according to the output of the channel voltage feedback adjustment module.

13. A driving device, suitable for driving N light-emitting modules, each light-emitting module having a first end and a second end, N ≥ 2, N is a positive integer, characterized in that: The driving device comprises: A power supply module, used for generating a supply voltage to a first end of each light emitting module; N driving current generating modules, each driving current generating module is electrically connected between the second end of the corresponding light-emitting module and the ground, and provides a channel voltage and a driving current to the second end of the corresponding light-emitting module according to a periodic conduction signal and an amplitude control signal, the periodic conduction signal indicates a duty cycle of each periodic time, the amplitude control signal indicates a current amplitude, the operating voltage of each light-emitting module is proportional to the corresponding amplitude of the driving current, and the channel voltage is proportional to a voltage difference between the supply voltage and the operating voltage of the light-emitting module; and The brightness adjustment module is electrically connected to the driving current generating module and the second end of each light-emitting module, and detects the channel voltage of each driving current generating module, and compares the channel voltage with the saturation lower limit voltage to correspondingly generate the amplitude control signal and the periodic conduction signal to the driving current generating module. When the channel voltage is greater than the saturation lower limit voltage, the current amplitude of the amplitude control signal is increased.

14. The driving device according to claim 13, characterized in that: The brightness adjustment module includes a supply voltage adjustment device, and the supply voltage adjustment device also presets an upper limit comparison voltage not higher than the maximum of the working voltages and a lower limit comparison voltage not lower than the minimum of the working voltages. When any channel voltage is less than the lower limit comparison voltage, the supply voltage adjustment device controls the supply voltage of the power supply module to increase. When the supply voltage adjustment device determines that each channel voltage is greater than the upper limit comparison voltage, the supply voltage adjustment device controls the supply voltage provided by the power supply module to decrease.

15. The driving device according to claim 14, characterized in that: The supply voltage adjustment device includes N high-voltage comparators, N low-voltage comparators, a first logic gate, a second logic gate, a supply voltage feedback adjustment module, and a current source. Each high potential comparator has a second terminal electrically connected to the light emitting module to receive a non-inverting terminal of the channel voltage, an inverting terminal to receive the upper limit comparison voltage, and an output terminal. Each low potential comparator has a second terminal electrically connected to the light emitting module to receive an inverting terminal of the channel voltage, a non-inverting terminal to receive the lower limit comparison voltage, and an output terminal. The first logic gate has a plurality of receiving ends respectively electrically connected to the output ends of the high potential comparator, and an output end. The second logic gate has a plurality of receiving terminals respectively electrically connected to the output terminals of the low potential comparator, and an output terminal. The supply voltage feedback adjustment module has a reset terminal electrically connected to the output terminal of the first logic gate, a set terminal electrically connected to the output terminal of the second logic gate, and an output terminal. The current source is used to generate a regulating current, the magnitude of which is used to control the magnitude of the supply voltage, and the magnitude of the regulating current is controlled by a logic signal generated at the output end of the supply voltage feedback adjustment module. When the output signal of the output terminal of each high potential comparator is logic 1, the regulating current is controlled to decrease by a change amount. When the output signal of the output terminal of any low potential comparator is logic 1, the regulating current is controlled to increase by a variation.

16. The driving device according to claim 13, characterized in that: The brightness adjustment module includes a channel voltage adjustment device, which compares whether the channel voltage of the driving current generating module is greater than the minimum saturation voltage. If yes, then adjust the amplitude control signal so that the corresponding amplitude of the driving current increases to reduce the channel voltage, If not, the channel voltage adjustment device stops increasing the amplitude of the driving current and records the increase percentage as the compensation coefficient, wherein the increase percentage is proportional to the ratio of the amplitude of the driving current corresponding to the lowest saturation voltage of the channel voltage to the amplitude of the driving current before adjustment, and the channel voltage adjustment device adjusts the duty cycle according to the compensation coefficient.

17. The driving device according to claim 16, characterized in that: The channel voltage adjustment device includes a multiplexer, a comparator, a channel voltage feedback adjustment module, and a brightness distributor. The multiplexer is used to receive a plurality of channel voltages and a selection signal, and output one of the plurality of channel voltages according to the selection signal. The comparator receives the minimum saturation voltage and is electrically connected to the multiplexer to receive the channel voltage outputted from the multiplexer, and provides a comparison result after comparing the minimum saturation voltage with the channel voltage. The channel voltage feedback adjustment module is electrically connected to the multiplexer to provide the selection signal and is electrically connected to the comparator to receive the comparison result, and generates an output according to the comparison result. The brightness distributor receives the brightness value and electrically connects the channel voltage feedback adjustment module and the drive current generating module, and generates the periodic conduction signal and the amplitude control signal to the drive current generating module corresponding to the comparison result according to the output of the channel voltage feedback adjustment module.

18. The driving device according to claim 13, characterized in that: It also includes a fault judgment circuit. When the fault judgment circuit judges that the channel voltage corresponding to any light-emitting module is lower than the open-circuit comparison voltage, the brightness adjustment module outputs an open-circuit fault signal, and the open-circuit fault signal indicates that the light-emitting module is in an open-circuit state. When the brightness adjustment module judges that the channel voltage corresponding to any light-emitting module is higher than the short-circuit comparison voltage, the brightness adjustment module outputs a short-circuit fault signal, and the short-circuit fault signal indicates that the light-emitting module is in a short-circuit state. The channel voltage is the difference between the supply voltage and the operating voltage corresponding to the light-emitting module.

19. A brightness control circuit electrically connected to N light-emitting modules, each light-emitting module having a first terminal for receiving a supply voltage and a second terminal, N≥2, N is a positive integer, characterized in that: The brightness control circuit comprises: N driving current generating modules, each driving current generating module is electrically connected between the second end of the corresponding light-emitting module and the ground, and provides a channel voltage and a driving current to the second end of the corresponding light-emitting module according to a periodic conduction signal and an amplitude control signal, the periodic conduction signal indicates a duty cycle of each periodic time, the amplitude control signal indicates a current amplitude, the operating voltage of each light-emitting module is proportional to the corresponding amplitude of the driving current, and the channel voltage is proportional to a voltage difference between the supply voltage and the operating voltage of the light-emitting module; and The brightness adjustment module is electrically connected to the driving current generating module and the second end of each light-emitting module, and detects the channel voltage of each driving current generating module, and compares the channel voltage with the saturation lower limit voltage to correspondingly generate the amplitude control signal and the periodic conduction signal to the driving current generating module. When the channel voltage is greater than the saturation lower limit voltage, the current amplitude of the amplitude control signal is increased.

Images