CN111654948B - LED driving circuit, driving method and display device - Google Patents
LED driving circuit, driving method and display device Download PDFInfo
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Abstract
The invention provides an LED drive circuit, a drive method and a display device, wherein the LED drive circuit comprises a processing controller and a selection switching device; the processing controller outputs a corresponding control instruction according to the display mode and/or the display brightness level so as to increase the duty ratio of the PWM signal of the sub constant current driving module; and the selection switching device disconnects or connects the input end and/or the output end of the sub constant current driving module according to the control instruction, and controls the connection state between the LED ports so as to increase the duty ratio of the PWM signal and drive the Mth sub constant current driving module to drive a plurality of LED ports at the same time. According to the LED driving circuit, the driving method and the display device, the duty ratio of the PWM signal of the sub constant current driving module is correspondingly increased, and the series-parallel ratio of the LED lamp strings is switched, so that the brightness of the backlight module is ensured, the circuit conversion efficiency is improved, and the power consumption of the LED driving circuit in different display modes and different display brightness levels is reduced.
Description
Technical Field
The invention relates to the field of display, in particular to an LED driving circuit, a driving method and a display device.
Background
Liquid Crystal Display (LCD) devices have many advantages such as being light, thin, energy-saving, and radiation-free, and thus have gradually replaced conventional Cathode Ray Tube (CRT) displays. Liquid crystal displays are widely used in high definition digital televisions, desktop computers, personal Digital Assistants (PDAs), notebook computers, mobile phones, digital cameras, and other electronic devices.
When the existing liquid crystal display device provides backlight through the backlight module, the LED driving circuit outputs corresponding constant current to the plurality of LED lamp strings of the lamp group through the plurality of sub-constant current driving modules of the constant current driving module. However, in different display modes or different display brightness levels, the driving currents on the LED strings are different, and the conversion efficiencies of the corresponding LED driving circuits are also different. For example, when the wide viewing angle is switched to the narrow viewing angle, the driving current of the LED becomes small, the conversion efficiency of the LED driving circuit becomes low, and further, when the display luminance level is lowered in the narrow viewing angle display mode, that is, by adjusting the duty ratio of the PWM signal, the driving current of the LED becomes further small, and the conversion efficiency of the LED driving circuit is lowered again, which causes the problem of out-of-specification power consumption.
Referring to fig. 1, fig. 1 is a schematic diagram of an LED driving circuit in the prior art. As shown in fig. 1, when adjusting the driving current output to the LED lamp set, the driving current input to the LED lamp set can be adjusted by adjusting the current ISET provided by the current input terminal (i.e. adjusting the current upper limit value of the sub-constant current driving module), or by adjusting the duty ratio of the PWM signal (under pulse width modulation, different driving currents mean different duty ratios). It should be noted that, in the prior art, a single sub constant current driving module drives a corresponding group of LED lamp sets under different conditions, and only in different conditions, such as display mode switching or different display brightness levels under different display modes, the driving current output from the sub constant current driving module to the LED lamp sets is adjusted to achieve adjustment of the display brightness.
Disclosure of Invention
In view of the above, the present invention provides an LED driving circuit, a driving method and a display device, which can improve the circuit conversion efficiency while ensuring the brightness of the backlight module, so as to solve the problem of over-specification power consumption in a specific display mode and display brightness level.
In order to achieve the above object, an embodiment of the present invention provides an LED driving circuit, as an implementation manner, the LED driving circuit includes a constant current driving module 100 and m LED ports, the constant current driving module 100 includes m sub-constant current driving modules 110, the m LED ports are used to be connected to m LED strings of an LED light group 200 one by one, m is an integer greater than 1, and the LED driving circuit further includes:
the processing controller 300, the processing controller 300 is connected to the m sub constant current driving modules 110, and is configured to output corresponding control instructions according to the display mode and/or the display brightness level, so as to increase duty ratios of the PWM signals of the m sub constant current driving modules 110;
and the selection switching device 400 is connected with the processing controller 300, and the selection switching device 400 is arranged between the constant current driving module 100 and the M LED ports, and is used for disconnecting or connecting the input end and/or the output end of the M sub-constant current driving modules 110 according to a control instruction, and controlling the connection state between the M LED ports, so that the mth sub-constant current driving module after increasing the duty ratio of the PWM signal drives a plurality of LED ports at the same time, where M is a natural number less than or equal to M.
As one of the embodiments, the selection switching device 400 includes m control switches 410 and a selection device, where the control switches are disposed between the sub constant current driving modules and the LED ports, and connected to the processing controller, and are configured to control connection states of the m LED ports and the corresponding m sub constant current driving modules according to a control instruction; the selection device is arranged between the constant current driving module and the m LED ports and used for controlling the connection states of the m LED ports.
As one embodiment, the selection device is disposed between the constant current driving module and the m LED ports, and all the switch elements in the selection device are connected to the processing controller, and are configured to control connection states of the m LED ports according to the control instruction.
As one embodiment, the selection device is disposed between the constant current driving module and the m LED ports, and the control terminals of all the switching elements in the selection device are connected to the output terminal of the sub constant current driving module, and are configured to control the connection states of the m LED ports according to the output current of the sub constant current driving module.
As one of the embodiments, the structure of the selection device corresponds to the maximum number of LED ports that can be simultaneously driven by a single sub-constant current driving module.
As one embodiment, the current upper limit value of the sub constant current driving module 110 is adjusted when the display mode is switched.
As one embodiment, when the maximum number of LED ports that a single sub constant-current driving module can simultaneously drive is 6, the selection means includes first to nineteenth switching elements,
first pass ends of the first to fifth switching elements are respectively connected with output ends of the second to sixth sub constant current driving modules, second pass ends of the first to fifth switching elements are respectively connected with second to sixth LED ports, and control ends of the first to fifth switching elements are respectively connected with output ends of the second to sixth sub constant current driving modules;
the sixth switching element to the tenth switching element are sequentially connected in series, a first path end of the sixth switching element is connected with an output end of the first sub constant current driving module, a second path end of the tenth switching element is connected with a second path end of the eighteenth switching element, and control ends of the sixth switching element to the tenth switching element are respectively connected with output ends of the first sub constant current driving module to the sixth sub constant current driving module;
first path ends of the eleventh to fifteenth switching elements are connected with second path ends of the sixth to tenth switching elements respectively, second path ends of the eleventh to fifteenth switching elements are connected with second to sixth LED ports respectively, and control ends of the eleventh to fifteenth switching elements are connected with output ends of the second to sixth constant current driving modules respectively;
control ends and first path ends of the sixteenth to eighteenth switching elements are respectively connected with output ends of the third to fifth sub-constant current driving modules, and second path ends of the sixteenth to eighteenth switching elements are respectively connected with second path ends of the eighth to tenth switching elements;
a first path end and a control end of the nineteenth switching element are connected with a second path end of the seventeenth switching element, and a second path end of the nineteenth switching element is connected with a second path end of the tenth switching element;
the first to fifth switching elements, the sixteenth to nineteenth switching elements are NMOS transistors, and the sixth to fifteenth switching elements are PMOS transistors.
The embodiment of the invention also provides a driving method of an LED driving circuit, the LED driving circuit comprises a constant current driving module 100 and m LED ports, the constant current driving module 100 comprises m constant current driving modules 110, the m LED ports are used for being connected with m LED lamp strings of an LED lamp group 200 one by one, m is an integer larger than 1, and the driving method comprises the following steps:
outputting a corresponding control instruction according to the display mode and/or the display brightness level to increase the duty ratio of the PWM signals of the m sub constant current driving modules 110;
and disconnecting or conducting the input end and/or the output end of the M sub constant current driving modules 110 according to the control instruction, and controlling the connection state among the M LED ports so as to increase the duty ratio of the PWM signal, and then the Mth sub constant current driving module drives a plurality of LED ports at the same time, wherein M is a natural number less than or equal to M.
As one of the embodiments, the driving method includes the steps of:
and controlling the connection states of the m LED ports according to the output current of the sub constant current driving module.
The embodiment of the invention also provides a display device which comprises the LED driving circuit.
In summary, according to the LED driving circuit, the LED driving method and the LED display device provided by the present invention, the processing controller outputs the corresponding control instruction according to the display mode and/or the display brightness level, so as to increase the duty ratio of the PWM signal of the sub constant current driving module; and the selection switching device disconnects or connects the input end and/or the output end of the sub constant current driving module according to the control instruction, and controls the connection state between the LED ports so as to increase the duty ratio of the PWM signal and drive the Mth sub constant current driving module to drive the plurality of LED ports at the same time. Therefore, the circuit conversion efficiency is improved and the power consumption of the LED driving circuit in different display modes and different display brightness levels is reduced while the brightness of the backlight module is ensured.
In order to make the aforementioned and other objects, features and advantages of the invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
Fig. 1 is a schematic diagram of a prior art LED driving circuit.
Fig. 2 is a block diagram of an LED driving circuit according to an embodiment of the invention.
Fig. 3 is a specific connection diagram of an LED driving circuit according to an embodiment of the invention.
Fig. 4 is a schematic structural diagram of a selection device in an LED driving circuit according to an embodiment of the invention.
Fig. 5 is a schematic shunting diagram of an LED driving circuit according to an embodiment of the invention.
Fig. 6 is a schematic shunting diagram of an LED driving circuit according to another embodiment of the present invention.
Fig. 7 is a flowchart of a driving method of an LED driving circuit according to an embodiment of the invention.
Detailed Description
To further illustrate the technical means and effects of the present invention for achieving the intended purpose, the following detailed description is given to specific embodiments, methods, steps, structures, features and effects of the LED driving circuit, the LED driving method and the LED display device according to the present invention with reference to the accompanying drawings and preferred embodiments.
The foregoing and other technical and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments, as illustrated in the accompanying drawings. While the invention has been described in connection with specific embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.
Referring to fig. 2, fig. 2 is a block diagram of an LED driving circuit according to an embodiment of the invention. As shown in fig. 2, the LED driving circuit includes a constant current driving module 100 and m LED ports, the constant current driving module 100 includes m sub-constant current driving modules 110, m LED ports (P0 to Pm-1 are used to connect with m LED strings (LED 0 to LED m-1, m is an integer greater than 1) of the LED light group 200 one by one, and the LED driving circuit further includes a processing controller 300 and a selection switching device 400.
The processing controller 300 is connected to the m sub constant current driving modules 110, and is configured to output a corresponding control instruction according to a display mode and/or a display brightness level, so as to increase duty ratios of PWM signals of the m sub constant current driving modules 110. The processing controller 300 may first input a signal to determine the type of the display mode and/or the display brightness level, and then output a corresponding control command according to the corresponding display mode and/or the display brightness level. For example, the processing controller 300 may output a corresponding control command according to a change of the display mode from the wide viewing angle display mode to the narrow viewing angle display mode, and/or may output a corresponding control command according to a change of the display brightness level in the narrow viewing angle display mode (the change of the display brightness level means a change of the current output to the LED lamp set, and when using the pulse width modulation means a change of the duty ratio of the PWM signal, so as to increase the duty ratio of the PWM signal of the sub constant current driving module 110, wherein in the technical solution of the embodiment, when the duty ratio of the PWM signal is increased, the conversion efficiency of the LED driving circuit is increased, for example, when the duty ratio is 75%, the conversion efficiency is higher than when the duty ratio is 50%.
The selection switching device 400 is connected to the processing controller 300, and the selection switching device 400 is disposed between the constant current driving module 100 and the M LED ports, and is configured to disconnect or connect the input end and/or the output end of the M sub-constant current driving modules 110 according to a control instruction, and control a connection state between the M LED ports, so that the mth sub-constant current driving module after increasing the duty ratio of the PWM signal drives a plurality of LED ports at the same time, where M is a natural number less than or equal to M.
Specifically, the input end and/or the output end of the m sub-constant current driving modules 110 are turned off or turned on according to the control instruction, that is, several of the m sub-constant current driving modules 110 are selectively driven to drive the LED lamp group, and the input end may be turned off, or the output end may be turned off. The connection state between the m LED ports is controlled by changing a series-parallel ratio between the m LED ports, for example, in a narrow viewing angle display mode, when a display brightness level is 1 or low (i.e., the driving current of the LED lamp groups in different definition modes of the level is 4mA, at this time, a single sub constant current driving module outputs a current of 4mA to drive one LED lamp group, which can meet a requirement, and at this time, in a low current state, the duty ratio of the PWM signal is low, and at this time, the conversion efficiency of the LED driving circuit is low.
In one embodiment, when the display mode is switched, the LED driving circuit changes the current upper limit value of the sub constant current driving module 110 accordingly.
Specifically, for example, in the narrow viewing angle display mode and with the duty ratio of the PWM signal being 100 percent, the driving current output by the sub constant current driving module 110 is 7mA, while in the wide viewing angle display mode and with the duty ratio of the PWM signal being 100 percent, the driving current output by the sub constant current driving module 110 is required to be 20mA, and at this time, the display brightness levels in the two cases may be corresponding, but only providing the adjustment of the duty ratio of the PWM signal cannot achieve the driving current in the two cases. Therefore, in this case, the current ISET provided by the regulation current input terminal, i.e., the current upper limit value of the sub constant-current driving module 110, needs to be adjusted.
Referring to fig. 3, fig. 3 is a circuit connection diagram of an LED driving circuit according to an embodiment of the invention. As shown in fig. 3, the selection switching device 400 includes m control switches 410 and a selection device 420, where the control switches 410 are disposed between the sub constant current driving modules 110 and the LED ports, and connected to the processing controller 300, and are used to control connection states of the m LED ports and the corresponding m sub constant current driving modules 110 according to the control instruction; the selecting device 420 is disposed between the constant current driving module 100 and the m LED ports, and is configured to control connection states of the m LED ports.
Specifically, the control switch 410 may be any switching element, such as an NMOS transistor, a PMOS transistor, or a triode, which mainly functions as a switch, and is turned on or off, and may be disposed between the sub constant current driving module 110 and the LED port, or may be disposed at the input end of the sub constant current driving module 110. The selection device 420 is disposed between the constant current driving module 110 and the m LED ports, or between the sub-constant current driving module 110 and the m LED ports, and is configured to control a connection state of the m LED ports, that is, a serial-to-parallel ratio between the m LED ports.
It should be noted that, in fig. 3, only one control switch 410 is indicated for simplicity, and the selecting device may be connected to the process controller or may not be controlled by the process controller, so that the connecting lines are not illustrated in fig. 3.
In one embodiment, the selection device 420 is disposed between the constant current driving module 100 and the m LED ports, and all the switch elements in the selection device 420 are connected to the process controller 300, and are configured to control connection states of the m LED ports according to a control instruction.
Specifically, in this embodiment, all the switch elements in the selection device 420 are connected to the process controller 300, and the process controller 300 outputs corresponding levels to control the switch elements, so as to change the connection manner between the m LED ports, where the selection device 420 has a simple structure, and is easy to be implemented by a person skilled in the art, and therefore, the details are not repeated herein.
In one embodiment, the selection device 420 is disposed between the constant current driving module 100 and the m LED ports, and the control terminals of all the switching elements in the selection device 420 are connected to the output terminal of the sub constant current driving module 110, so as to control the connection states of the m LED ports according to the output current of the sub constant current driving module 1100.
Specifically, in this embodiment, the selection device 420 is directly controlled by the output current of each sub constant current driving module 110, so that the state of each switching element is related to the output of each sub constant current driving module 110, and there are two cases in the specific structure of the selection device 420, one is formed by multiple sets of repeated sub units, for example, there are 12 sets of light sets in total, the 1 st to 4 th sets of light sets correspond to one sub unit, the 5 th to 8 th sets of light sets correspond to one sub unit, the 9 th to 12 th sets of light sets correspond to one sub unit, and the structures of 3 sub units are the same. Alternatively, the group 1 to group 12 lamp sets correspond to a subunit, and the subunit is the selection device.
Therefore, in an embodiment, the structure of the selection device 420 corresponds to the maximum number of LED ports that can be driven simultaneously by a single sub-constant current driving module 110.
Specifically, taking the maximum number of LED ports that can be simultaneously driven by a single sub constant current driving module 110 as 6 as an example, that is, the selecting device 420 in this case can satisfy the situation that a single sub constant current driving module 110 drives 1 to 6 LED ports 6.
Referring to fig. 4 to 6, fig. 4 is a schematic structural diagram of a selection device in an LED driving circuit according to an embodiment of the invention. Fig. 5 is a schematic shunting diagram of an LED driving circuit according to an embodiment of the invention. Fig. 6 is a schematic shunting diagram of an LED driving circuit according to another embodiment of the present invention.
As shown in fig. 4, the selection device 420 includes first to nineteenth switching elements Q1 to Q19, first path ends of the first to fifth switching elements Q1 to Q5 are respectively connected with output ends of the second to sixth sub constant current driving modules, second path ends of the first to fifth switching elements Q1 to Q5 are respectively connected with second to sixth LED ports, and control ends of the first to fifth switching elements Q1 to Q5 are respectively connected with output ends of the second to sixth sub constant current driving modules;
the sixth switching element Q6 to the tenth switching element Q10 are sequentially connected in series, a first path end of the sixth switching element Q6 is connected with the output end of the first sub constant current driving module, a second path end of the tenth switching element Q10 is connected with a second path end of the eighteenth switching element Q18, and control ends of the sixth switching element Q6 to the tenth switching element Q10 are respectively connected with the output ends of the first sub constant current driving module to the sixth sub constant current driving module;
first path ends of eleventh to fifteenth switching elements Q11 to Q15 are respectively connected with second path ends of sixth to tenth switching elements Q6 to Q10, second path ends of the eleventh to fifteenth switching elements Q11 to Q15 are respectively connected with second to sixth LED ports, and control ends of the eleventh to fifteenth switching elements Q11 to Q15 are respectively connected with output ends of the second to sixth sub constant current driving modules;
control ends and first path ends of sixteenth to eighteenth switching elements Q16 to Q18 are respectively connected with output ends of the third to fifth sub constant current driving modules, and second path ends of the sixteenth to eighteenth switching elements Q16 to Q18 are respectively connected with second path ends of the eighth to tenth switching elements Q8 to Q10;
a first path terminal and a control terminal of the nineteenth switching element Q19 are connected to a second path terminal of the seventeenth switching element Q17, and a second path terminal of the nineteenth switching element Q19 is connected to a second path terminal of the tenth switching element Q10;
the first to fifth switching elements Q1 to Q5, the sixteenth to nineteenth switching elements Q16 to Q19 are NMOS transistors, and the sixth to fifteenth switching elements Q6 to Q15 are PMOS transistors.
The selection device 420 provided by this embodiment may satisfy the situation that a single sub-constant current driving module 110 drives 1 to 6 LED ports 6, as shown in fig. 5, fig. 5 shows the situation that a single sub-constant current driving module 110 drives 2 groups of LED ports simultaneously, that is, 2 groups of LED ports shunt the driving current of one sub-constant current driving module 110. At this time, in the first to sixth sub constant current driving modules 110 to 110, the control switches corresponding to the 1, 3, and 5 sub constant current driving modules 110 are in an on state, so that the output indicates a high level by H, and the control switches corresponding to the 2, 4, and 6 sub constant current driving modules 110 are in an off state, so that the output indicates a low level by L. The state of the switching elements in the corresponding selection means 420 is shown in fig. 5.
As shown in fig. 6, fig. 6 shows a case where a single sub constant current driving module 110 drives 6 groups of LED ports simultaneously, that is, the 6 groups of LED ports shunt the driving current of one sub constant current driving module 110. At this time, in the first sub constant current driving module 110 to the sixth sub constant current driving module 1110, the control switch corresponding to the first sub constant current driving module 110 is in an on state, so that the output represents a high level by H, and the control switch corresponding to the second sub constant current driving module 110 to the sixth sub constant current driving module 110 is in an off state, so that the output represents a low level by L. The state of the switching element in the corresponding selection means 420 is shown in fig. 6.
In fig. 5 and 6, arrows indicate the flow of current, and x indicates off, where fig. 5 only marks the first group of parallel ports, and the circuit in which the switching element not marked in fig. 6 is located also indicates off.
In summary, the selection switching device 400 increases the duty ratio of the PWM signal according to the control instruction, and correspondingly switches the serial-to-parallel ratio of the LED strings, thereby improving the circuit conversion efficiency and reducing the circuit power consumption while ensuring the brightness of the backlight module. In addition, the present embodiment is not limited thereto, and other technical solutions within the inventive concept are within the scope of the present invention.
Referring to fig. 7, fig. 7 is a flowchart illustrating a driving method of an LED driving circuit according to an embodiment of the present invention. As shown in fig. 7, the LED driving circuit includes a constant current driving module 100 and m LED ports, the constant current driving module 100 includes m constant current driving sub-modules 110, the m LED ports are used to connect with m LED strings of the LED light group 200 one by one, m is an integer greater than 1, and the LED driving method includes the steps of:
s1, outputting a corresponding control instruction according to a display mode and/or a display brightness level to increase the duty ratio of PWM signals of m sub constant current driving modules 110;
and S2, disconnecting or connecting the input end and/or the output end of the M sub constant current driving modules 110 according to the control instruction, and controlling the connection state among the M LED ports so as to increase the duty ratio of the PWM signal, wherein the Mth sub constant current driving module drives a plurality of LED ports at the same time, and M is a natural number smaller than or equal to M.
In one embodiment, the LED driving method further includes the steps of:
and controlling the connection states of the m LED ports according to the output current of the sub constant current driving module.
The LED driving method of the present embodiment can refer to the implementation of the LED driving circuit, and is not described in detail herein.
According to the driving method of the LED driving circuit of the embodiment, different control instructions are output according to different display modes and/or different display brightness levels to increase the duty ratios of the PWM signals of the m sub-constant current driving modules 110, and the plurality of LED ports are controlled to be divided into the corresponding plurality of groups of LED ports according to the corresponding control instructions, and all the LED lamp strings in the same group are connected to the same sub-constant current driving module 110, that is, the serial-to-parallel ratio of the LED lamp strings is correspondingly switched according to the corresponding control instructions, so that the luminance of the backlight module is ensured, the circuit conversion efficiency is improved, and the problem of the over-specification power consumption of the driving circuit is solved.
The embodiment of the invention also provides a display device which comprises the LED driving circuit in any one of the embodiments.
For the implementation of the display device of this embodiment, reference may be made to the implementation of the LED driving circuit, which is not described in detail herein.
In the display device of this embodiment, the processing controller 300 outputs different control instructions according to different display modes and/or different display brightness levels to increase the duty ratios of the PWM signals of the m sub-constant current driving modules 110, the selection switching device controls the plurality of LED ports to be divided into corresponding groups of LED ports according to corresponding control instructions, and all the LED strings in the same group are connected to the same sub-constant current driving module 110, that is, the serial-to-parallel ratio of the LED strings is correspondingly switched according to the corresponding control instructions, so that the luminance of the backlight module is ensured, the circuit conversion efficiency is improved, and the problem of over-specification power consumption of the driving circuit is solved.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. The utility model provides a LED drive circuit, LED drive circuit includes constant current drive module (100) and m LED ports, constant current drive module (100) includes m sub-constant current drive module (110), m LED ports are used for linking to each other with m LED lamp cluster of LED banks (200) one by one, and m is the integer that is greater than 1, its characterized in that, LED drive circuit still includes: the processing controller (300) is connected with the m sub constant current driving modules (110) and is used for outputting corresponding control instructions according to a display mode and/or a display brightness level so as to increase the duty ratios of the PWM signals of the m sub constant current driving modules (110); the selection switching device (400), the selection switching device (400) is connected with the processing controller (300), and the selection switching device (400) is arranged between the constant current driving module (100) and the M LED ports, and is used for disconnecting or connecting the input end and/or the output end of the M sub constant current driving modules (110) according to the control instruction, and controlling the connection state between the M LED ports, so that the Mth sub constant current driving module (110) after increasing the duty ratio of the PWM signal drives a plurality of LED ports at the same time, wherein M is a natural number less than or equal to M;
the selection switching device (400) comprises m control switches (410) and a selection device (420), wherein the control switches (410) are arranged between the sub constant current driving modules (110) and the LED ports, are connected with the processing controller (300), and are used for controlling the connection states of the m LED ports and the corresponding m sub constant current driving modules (110) according to the control instruction; the selection device (420) is arranged between the constant current driving module (100) and the m LED ports and used for controlling the connection states of the m LED ports.
2. The LED driving circuit according to claim 1, wherein the selection device (420) is disposed between the constant current driving module (100) and the m LED ports, and all the switch elements in the selection device (420) are connected to the process controller (300) for controlling the connection states of the m LED ports according to the control command.
3. The LED driving circuit according to claim 1, wherein the selection device (420) is disposed between the constant current driving module (100) and the m LED ports, and control terminals of all switching elements in the selection device (420) are connected to the output terminal of the sub constant current driving module (110) for controlling connection states of the m LED ports according to the output current of the sub constant current driving module (110).
4. The LED driving circuit according to claim 3, wherein the structure of the selection device (420) corresponds to the maximum number of LED ports that a single sub-constant current driving module (110) can drive simultaneously.
5. The LED driving circuit according to claim 1, wherein the current upper limit value of the sub constant current driving module (110) is adjusted when the display mode is switched.
6. The LED driving circuit according to claim 4, wherein when the maximum number of LED ports that a single sub-constant current driving module (110) can drive simultaneously is 6, the selection means (420) includes first to nineteenth switching elements,
first path ends of the first switching element to the fifth switching element are respectively connected with output ends of the second constant current driving sub-module to the sixth constant current driving sub-module, second path ends of the first switching element to the fifth switching element are respectively connected with second LED ports to sixth LED ports, and control ends of the first switching element to the fifth switching element are respectively connected with output ends of the second constant current driving sub-module to the sixth constant current driving sub-module;
the sixth switching element to the tenth switching element are sequentially connected in series, a first path end of the sixth switching element is connected with an output end of the first sub constant current driving module, a second path end of the tenth switching element is connected with a second path end of the eighteenth switching element, and control ends of the sixth switching element to the tenth switching element are respectively connected with output ends of the first sub constant current driving module to the sixth sub constant current driving module;
first path ends of the eleventh to fifteenth switching elements are respectively connected with second path ends of the sixth to tenth switching elements, second path ends of the eleventh to fifteenth switching elements are respectively connected with second to sixth LED ports, and control ends of the eleventh to fifteenth switching elements are respectively connected with output ends of the second to sixth sub constant current driving modules;
the control ends and the first path ends of the sixteenth switching element to the eighteenth switching element are respectively connected with the output ends of the third sub-constant current driving module to the fifth sub-constant current driving module, and the second path ends of the sixteenth switching element to the eighteenth switching element are respectively connected with the second path ends of the eighth switching element to the tenth switching element; a first path end and a control end of the nineteenth switching element are connected to a second path end of the seventeenth switching element, and a second path end of the nineteenth switching element is connected to a second path end of the tenth switching element;
the first to fifth switching elements, the sixteenth to nineteenth switching elements are NMOS transistors, and the sixth to fifteenth switching elements are PMOS transistors.
7. A driving method of an LED driving circuit, which is applied to the LED driving circuit according to any one of claims 1 to 6, wherein the LED driving circuit includes a constant current driving module (100) and m LED ports, the constant current driving module (100) includes m constant current driving modules (110), the m LED ports are used for being connected to m LED strings of an LED light group (200) one by one, m is an integer greater than 1, and the driving method includes the steps of:
outputting a corresponding control instruction according to a display mode and/or a display brightness level to increase the duty ratio of the PWM signals of the m sub constant current driving modules (110);
and disconnecting or conducting the input end and/or the output end of the M sub constant current driving modules (110) according to the control instruction, and controlling the connection state among the M LED ports so as to increase the duty ratio of the PWM signal, so that the Mth sub constant current driving module drives a plurality of LED ports at the same time, wherein M is a natural number less than or equal to M.
8. The driving method according to claim 7, characterized by comprising the steps of: and controlling the connection state of the m LED ports according to the output current of the sub constant current driving module.
9. A display device comprising the LED driving circuit according to any one of claims 1 to 6.
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