WO2023147739A1 - 基于低电势端开关控制的led背光驱动电路及驱动方法 - Google Patents

基于低电势端开关控制的led背光驱动电路及驱动方法 Download PDF

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WO2023147739A1
WO2023147739A1 PCT/CN2022/136047 CN2022136047W WO2023147739A1 WO 2023147739 A1 WO2023147739 A1 WO 2023147739A1 CN 2022136047 W CN2022136047 W CN 2022136047W WO 2023147739 A1 WO2023147739 A1 WO 2023147739A1
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duty cycle
led light
channel
light string
led
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PCT/CN2022/136047
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English (en)
French (fr)
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阳冠欧
王京
孔令新
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北京芯格诺微电子有限公司
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Publication of WO2023147739A1 publication Critical patent/WO2023147739A1/zh

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/3413—Details of control of colour illumination sources
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0257—Reduction of after-image effects
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

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  • the invention relates to the technical field of LED display, in particular to an LED backlight driving circuit and a driving method based on low potential end switch control.
  • the LED backlight drive in the prior art generally adopts a direct drive mode or a row-column scan drive mode. As shown in FIG. 1 , it is the direct drive mode LED backlight control in the prior art.
  • the positive end (high potential end) of each LED light string is connected to the driving voltage V LED .
  • a line selection control switching device and a constant current module are connected to the negative end (low potential end) of each LED light string.
  • this LED backlight drive circuit in direct drive mode is that it can ensure that each LED light string can achieve 100% brightness display, that is, when a certain LED light string needs maximum brightness output, it only needs to control the constant current module to output the maximum The maximum operating current of the LED light string, and the line selection control switch device is set to 100% duty cycle.
  • the defect of the direct drive mode is also very obvious, that is, it requires each LED light string channel in the LED backlight drive circuit to be provided with an independent constant current source module to realize the independent control of the LED light string channel, which makes the hardware cost and control The cost is extremely high.
  • FIG. 2 it is an LED backlight driving circuit using row and column scanning driving mode in the prior art.
  • a plurality of LED light strings are grouped into one group, for example, Each LED light string is set as a group, and the high potential end of each LED light string is provided with a row scanning switch control device, and the low potential end of each group of LED light strings shares a column scanning control switching device, that is, a constant current
  • the module realizes the great simplification of the LED backlight driving control circuit through the above structure, and reduces the hardware cost of the LED backlight driving control circuit.
  • the defects of the LED backlight driving circuit in this mode are also very obvious.
  • the driving current value of the constant current source used must be the required value for a single LED light string multiples of the current value.
  • the row scan switching at the high potential end needs to be controlled and matched with the column scan switching at the low potential end, which greatly increases the difficulty of control.
  • the resulting display "ghost" (afterimage) phenomenon is very obvious, and it is difficult to completely eliminate it even if additional pre-charging control is added.
  • the technical purpose of the present invention is to individually adjust the brightness of each LED light string to break through the upper limit of the average duty ratio, and at the same time greatly simplify the complexity of the LED drive circuit to reduce the circuit cost and drive control. cost.
  • the present invention provides an LED backlight drive circuit based on low potential end switch control, the LED backlight drive circuit includes a plurality of LED light strings 1, channel control switching devices 2, constant current module 3, channel switching Control module 4, signal control unit 5 and SPI interface unit unit 6;
  • each LED light string 1 is directly connected to the LED driving voltage V LED , and the low potential end is connected to a channel control switching device 2; a plurality of LED light strings 1 form a group of LED light strings, and each group of LED light The strings share a constant current module 3, and multiple channel control switching devices 2 in each group of LED light strings are connected to a channel switching control module 4; the channel switching control module 4 is used to control the opening of the LED light strings in this group;
  • the channel switching control module 4 is connected to the signal control unit 5, and the signal control unit 5 is connected to the SPI interface unit 6; the SPI interface unit 6 receives an external display signal and transmits it to the signal control unit 5, which is controlled by the signal
  • the unit 5 determines the turn-on duty cycle of each LED light string in each group of LED light strings according to the display brightness requirement, and transmits the turn-on duty cycle data to the corresponding channel switching control module 4 for controlling each group of each LED light string The turn-on duty cycle of each LED light string in the light string.
  • the constant current module 3 uses an IDAC current source or a VDAC voltage source.
  • the present invention also provides a method for driving LED backlight based on low potential end switch control, the method comprising:
  • the LED light string if the sum of the remaining amount of the duty cycle and the upper limit of the average duty cycle is greater than the brightness demand duty cycle of the LED light string whose brightness demand duty exceeds the upper limit of the average duty cycle, the LED light string The actual open duty is set to its brightness demand duty cycle;
  • the actual turn-on duty cycle of the LED light string It is set as the sum of the remaining amount of the duty cycle and the upper limit of the average duty cycle.
  • four LED light strings are set as a group, and the upper limit of the shared duty cycle is 25%;
  • the brightness requirement duty cycle of the LED light string of the first channel is T 1 , and T 1 >25%;
  • the brightness requirement duty cycle of the LED light string of the second channel is T 2 , and T 2 ⁇ 25%;
  • the brightness requirement duty cycle of the LED light string of the third channel is T 3 , and T 3 ⁇ 25%;
  • the brightness requirement duty cycle of the LED light string of the fourth channel is T 4 , and T 4 ⁇ 25%.
  • the duty cycle remaining amount T s is (25%-T 2 )+(25%-T 3 )+(25%-T 4 );
  • T s +25% is greater than T 1 , the turn-on duty cycle of the LED light string of the first channel is set to T 1 ;
  • T s +25% When T s +25% is less than T 1 , the turn-on duty cycle of the LED light string of the first channel is set to T s +25%.
  • the present invention also provides a method for driving LED backlight based on low potential end switch control, the method comprising:
  • the rest of the LED light strings except the LED light string L max allocate the duty cycle margin T q in equal proportions according to their brightness requirement duty cycle values.
  • four LED light strings are set as a group, and the upper limit of the shared duty cycle is 25%;
  • the brightness requirement duty cycle of the LED light string of the first channel is T 1 , and T 1 >25%;
  • the brightness requirement duty cycle of the LED light string of the second channel is T 2 , and T 2 ⁇ 25%;
  • the brightness requirement duty cycle of the LED light string of the third channel is T 3 , and T 3 ⁇ 25%;
  • the brightness requirement duty cycle of the LED light string of the fourth channel is T 4 , and T 4 ⁇ 25%.
  • the turn-on duty ratio of the LED light string of the second channel is adjusted as T q *T 2 /(T 2 +T 3 +T 4 );
  • the turn-on duty cycle of the LED light string of the third channel is adjusted as T q *T 3 /(T 2 +T 3 +T 4 );
  • the turn-on duty cycle of the LED light string of the fourth channel is adjusted as T q *T 4 /(T 2 +T 3 +T 4 ).
  • the present invention also provides a method for driving LED backlight based on low potential end switch control, the method comprising:
  • four LED light strings are set as a group, and the upper limit of the shared duty cycle is 25%;
  • the brightness requirement duty cycle of the LED light string of the first channel is T 1 , and T 1 >25%;
  • the brightness requirement duty cycle of the LED light string of the second channel is T 2 , and T 2 ⁇ 25%;
  • the brightness requirement duty cycle of the LED light string of the third channel is T 3 , and T 3 ⁇ 25%;
  • the brightness requirement duty cycle of the LED light string of the fourth channel is T 4 , and T 4 ⁇ 25%.
  • the turn-on duty cycle of the LED light string of the first channel is adjusted as T 1 /(T 1 +T 2 +T 3 +T 4 );
  • the turn-on duty ratio of the LED light string of the second channel is adjusted as T 2 /(T 1 +T 2 +T 3 +T 4 );
  • the turn-on duty ratio of the LED light string of the third channel is adjusted as T 3 /(T 1 +T 2 +T 3 +T 4 );
  • the turn-on duty ratio of the LED light string of the fourth channel is adjusted as T 4 /(T 1 +T 2 +T 3 +T 4 ).
  • one or more embodiments of the present invention may have the following advantages:
  • FIG. 1 is a schematic diagram of an LED backlight drive control circuit using a direct drive mode in the prior art
  • FIG. 2 is a schematic diagram of an LED backlight drive control circuit using a row-column scanning mode in the prior art
  • Fig. 3 is a schematic diagram of the LED backlight drive control circuit of the present invention.
  • each LED light string 1 is directly connected to the driving voltage V LED , and each LED light string The low potential end of 1 is connected to a channel control switching device 2 .
  • Multiple LED light strings 1 are combined to form a group of LED light strings, and each group of LED light strings shares a constant current module 3 .
  • Multiple channel control switching devices 2 in each group of LED light strings are connected to a channel switching control module 4 , and the channel switching control module 4 is connected to a signal control unit 5 , and the signal control unit 5 is connected to an SPI interface unit 6 .
  • every four LED light strings form a group, and the four LED light strings share one constant current module. Since four LED light strings share the constant current module, in the case that the LED light strings of all channels equally share the constant current module, the upper limit of the duty ratio that can be shared by the LED light strings of each channel is 25%. And the sum of the on-duty ratios of the LEDs of all channels is at most 100%, that is, the sum of all the duty ratios of the constant current modules shared by the four channels is at most 100%.
  • the other LED light strings in the same group fail to reach the duty cycle margin of 25% duty cycle. Supplemented to LED light strings that require increased brightness, so that the LED light string breaks through the 25% duty cycle limit.
  • the brightness requirements of the LED light strings of channel 1, channel 2, channel 3, and channel 4 are 35%, 15%, 20%, and 25%, respectively. From the above brightness requirements, it can be seen that the brightness requirements of the LED light string of channel 1 have exceeded the upper limit of the average duty cycle, that is, exceeded the 25% duty cycle.
  • the brightness requirements of channel 2 and channel 3 are only 15% and 20%. That is, channel 2 produces a duty cycle margin of 10%, channel 3 produces a duty cycle margin of 5%, and the total duty cycle margin reaches 15%.
  • the channel switching control module 4 can The on-duty cycle of channel 1 is increased to 35%, while the duty cycles of channel 2, channel 3, and channel 4 are set to 15%, 20%, and 25% respectively according to their brightness requirements.
  • the brightness requirements of the LED light strings of channel 1, channel 2, channel 3, and channel 4 are 60%, 15%, 20%, and 25%, respectively. From the above brightness requirements, it can be seen that the brightness requirements of the LED light string of channel 1 have exceeded the upper limit of the average duty cycle, that is, exceeded the 25% duty cycle.
  • the brightness requirements of channel 2 and channel 3 are only 15% and 20%. That is, channel 2 produces a duty cycle margin of 10%, channel 3 produces a duty cycle margin of 5%, and the total duty cycle margin reaches 15%.
  • the brightness upper limit of some LED light string channels is increased to achieve the goal of increased display brightness. Effect.
  • every four LED light strings form a group, and the four LED light strings share one constant current module. Since four LED light strings share the constant current module, the maximum duty cycle of the LED light strings of each channel is 25% under the condition that the LED light strings of all channels equally share the constant current module. However, when the brightness requirement of a certain LED light string exceeds 25%, in the LED backlight driving method of this embodiment, the duty cycle margin of other LED light strings in the same group that fails to reach the 25% duty cycle is supplemented to the required In the LED light string with increased brightness, the LED light string breaks through the duty ratio limit of 25%.
  • the brightness requirements of the LED light strings of channel 1, channel 2, channel 3, and channel 4 are 60%, 15%, 20%, and 25%, respectively. From the above brightness requirements, it can be seen that the brightness requirements of the LED light string of channel 1 have exceeded the upper limit of the average duty cycle, that is, exceeded the 25% duty cycle.
  • the brightness requirements of channel 2 and channel 3 are only 15% and 20%, while the brightness requirement of channel 4 is exactly 25% of the upper limit of the average duty cycle.
  • the brightness requirement duty ratios of the remaining channels 2, 3, and 4 are compressed.
  • the specific compression method is: when the brightness requirement duty ratio of channel 1 When the ratio is 60%, the total duty cycle of channel 2, channel 3 and channel 4 is at most 40%. Therefore, through the channel switching control module 4 , the actual display duty ratios of channels 2 and 3 and channel 4 are allocated to 40% duty ratios according to the ratio of brightness requirement duty ratios.
  • the LED backlight driving method in this embodiment when the demand for LED light strings with increased brightness is fully guaranteed, the brightness of other LED light strings is appropriately reduced, so that the upper limit of the brightness of some LED light string channels is increased to achieve display brightness. added effect.
  • every four LED light strings form a group, and the four LED light strings share one constant current module. Since four LED light strings share the constant current module, the maximum duty cycle of the LED light strings of each channel is 25% under the condition that the LED light strings of all channels equally share the constant current module. However, when the brightness requirement of a certain LED light string exceeds 25%, in the LED backlight driving method of this embodiment, the duty cycle margin of other LED light strings in the same group that fails to reach the 25% duty cycle is supplemented to the required In the LED light string with increased brightness, the LED light string breaks through the duty ratio limit of 25%.
  • the brightness requirements of the LED light strings of channel 1, channel 2, channel 3, and channel 4 are 60%, 15%, 20%, and 25%, respectively. From the above brightness requirements, it can be seen that the brightness requirements of the LED light string of channel 1 have exceeded the upper limit of the average duty cycle, that is, exceeded the 25% duty cycle.
  • the brightness requirements of channel 2 and channel 3 are only 15% and 20%, while the brightness requirement of channel 4 is exactly 25% of the upper limit of the average duty cycle.
  • the brightness requirement duty cycle of channel 1, channel 2, channel 3, and channel 4 is compressed in equal proportions, so as to achieve the effect of appropriately increasing the brightness of the LED light string of channel 1.
  • the on-duty cycles of channel 1, channel 2, channel 3 and channel 4 are adjusted by the channel switching control module 4 according to the following ratio.
  • the brightness requirement duty ratios of channel 1, channel 2, channel 3, and channel 4 are compressed in equal proportions, so that the upper limit of the brightness of some LED light string channels is increased, breaking through the equal share.
  • the upper limit of the space ratio to achieve the effect of increasing the display brightness.
  • Embodiment 1 It can be known from the descriptions of Embodiment 1, Embodiment 2 and Embodiment 3 that the adjustment of the turn-on duty cycle of the driving control of the LED light string in the present invention depends on the aforementioned LED backlight driving circuit structure of the present invention.
  • the adjustment of the duty cycle in the above-mentioned embodiments of the present invention can be realized only by setting the switching device and the channel switching control module at the low potential end of the LED light string.
  • the current structure is greatly simplified compared with the direct drive mode in the prior art, and the cost of the circuit structure is saved .
  • the LEDs in the same group can be adjusted
  • the light string can break through the upper limit of the average duty cycle and achieve higher brightness.

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Abstract

一种基于低电势端开关控制的LED背光驱动电路及背光驱动方法，包括多个LED灯串（1）、通道控制开关器件（2）、恒流模块（3）、通道切换控制模块（4）、信号控制单元（5）和SPI接口单元（6）；每个LED灯串（1）的高电势端直接连接于LED驱动电压V LED，低电势端连接有一个通道控制开关器件（2）和恒流模块（3），每组LED灯串（1）中的多个通道控制开关器件（2）连接于一个通道切换控制模块（4）；通道切换控制模块（4）用于控制本组内LED灯串（1）的开启占空比。

Description

基于低电势端开关控制的LED背光驱动电路及驱动方法 技术领域
本发明涉及LED显示技术领域，尤其涉及一种基于低电势端开关控制的LED背光驱动电路及驱动方法。
背景技术
现有技术中的LED背光驱动一般采用直驱模式或行列扫描驱动模式。如图1所示，为现有技术中的直驱模式的LED背光控制，在该LED背光驱动电路中，每一个LED灯串的正极端(高电势端)均连接驱动电压V LED。在每一个LED灯串的负极端(低电势端)均连接有选线控制开关器件及恒流模块。这种直驱模式下的LED背光驱动电路的优势在于能够保证每一个LED灯串均可以实现100％亮度显示，即当某一个LED灯串需要最大亮度输出时，只需要控制恒流模块输出最大LED灯串最大工作电流，且选线控制开关器件设置为100％占空比即可。但是直驱模式的缺陷也十分明显，即其需要LED背光驱动电路中的每一个LED灯串通道均设置有独立的恒流源模块以实现LED灯串通道的独立控制，这使得硬件成本和控制成本极高。
如图2所示，为现有技术中采用行列扫描驱动模式的LED背光驱动电路，在该LED背光驱动电路中，多个LED灯串被归集为一组，例如图中所示，每4个LED灯串被设定为一组，每一个LED灯串的高电势端均设置有行扫描开关控制器件，而每一组LED灯串的低电势端共用一个列扫描控制开关器件即恒流模块，通过上述结构实现了LED背光驱动控制电路的极大的简化，降低了LED背光驱动控制电路的硬件成本。但是这种模式下的的LED背光驱动电路的缺陷也十分明显。首先，由于多个LED灯串共用恒流源模块，因此为了每一个LED灯串均能够满足实现最大亮度的电流值，所使用的的恒流源的驱动电流值需要是单个LED灯串所需电流值的多倍。且高电势端进行的行扫描切换需要与低电势端的列扫描 切换进行控制匹配，控制难度大大增加。同时这种LED背光控制方式下的由于高电势端在切换时电流较大，由此造成的显示“鬼影”(残影)现象十分明显，即使额外增加预充电控制也很难完全消除。最明显的缺陷是在这种LED背光控制方式下是无法实现某一单个LED灯串的亮度单独的提高，仅仅只能实现一组LED灯串亮度的同时提高。这就使得该LED背光控制方式下在提供某种特殊的局部画面短时亮度暴增(例如爆炸画面)时显示效果不佳。
由此可见现有技术中急需一种能够实现对每一个LED灯串的亮度进行单独控制且硬件成本较低的LED背光驱动电路及驱动方法。
发明内容
本发明所要实现的技术目的在于实现对每一个LED灯串的亮度进行单独的调节使其突破均分占空比上限的限制，并且同时大大简化LED驱动电路的复杂程度以降低电路成和驱动控制成本。
为实现上述技术目的本发明提供了一种基于低电势端开关控制的LED背光驱动电路，所述LED背光驱动电路包括多个LED灯串1、通道控制开关器件2、恒流模块3、通道切换控制模块4、信号控制单元5和SPI接口单元单元6；
每个所述LED灯串1的高电势端直接连接于LED驱动电压V LED，低电势端连接有一个通道控制开关器件2；多个LED灯串1形成一组LED灯串，每组LED灯串共用一个恒流模块3，每组LED灯串中的多个通道控制开关器件2连接于一个通道切换控制模块4；所述通道切换控制模块4用于控制本组内LED灯串的开启；
所述通道切换控制模块4连接于信号控制单元5，所述信号控制单元5连接于SPI接口单元6；所述SPI接口单元6接收外部的显示信号，并传输至信号控制单元5，由信号控制单元5根据显示亮度需求来确定每组LED灯串内的每一个LED灯串的开启占空比，并将开启占空比数据传输至对应的通道切换控制模块4用于控制每组每组LED灯串内的每一个LED灯串的开启占空比。
在一个实施例中，所述恒流模块3采用IDAC电流源或VDAC电压源。
基于前述本发明所提供的LED背光驱动电路，本发明还提供了一种基于低电势端开关控制的LED背光驱动方法，所述方法包括：
确定每组LED灯串中每个LED灯串的亮度需求占空比及均分占空比上限；
计算每个LED灯串的亮度需求占空比与均分占空比上限之间的差值以获取占空比剩余额度；
将占空比剩余额度补偿给亮度需求占空比超出均分占空比上限的LED灯串，以提高该LED灯串的显示亮度；
在一个实施例中，若占空比剩余额度与均分占空比上限之和大于亮度需求占空比超出均分占空比上限的LED灯串的亮度需求占空比，则该LED灯串的实际开启占空设置为其亮度需求占空比；
若占空比剩余额度与均分占空比上限之和小于亮度需求占空比超出均分占空比上限的LED灯串的亮度需求占空比，则该LED灯串的实际开启占空比设置为占空比剩余额度与均分占空比上限之和。
在一个实施例中，以四个LED灯串设置为一组，其均分占空比上限为25％；
第一通道LED灯串的的亮度需求占空比为T 1，且T 1>25％；
第二通道LED灯串的的亮度需求占空比为T 2，且T 2<25％；
第三通道LED灯串的的亮度需求占空比为T 3，且T 3<25％；
第四通道LED灯串的的亮度需求占空比为T 4，且T 4<25％。
则，占空比剩余额度T s为(25％-T 2)+(25％-T 3)+(25％-T 4)；
当T s+25％大于T 1时，第一通道LED灯串的开启占空比设置为T 1；
当T s+25％小于T 1时，第一通道LED灯串的开启占空比设置为T s+25％。
基于前述本发明所提供的LED背光驱动电路，本发明还提供了一种基于低电势端开关控制的LED背光驱动方法，所述方法包括：
确定每组LED灯串中每个LED灯串的亮度需求占空比及均分占空比上限；其中亮度需求占空比超出均分占空比上限的LED灯串记为L max；该LED灯串的的亮度需求占空比记为T max；
计算占空比余量T q，所述占空比余量T q为100％-T max；
除LED灯串L max之外的其余LED灯串根据其亮度需求占空比数值等比例分配所述占空比余量T q。
在一个实施例中，以四个LED灯串设置为一组，其均分占空比上限为25％；
第一通道LED灯串的的亮度需求占空比为T 1，且T 1>25％；
第二通道LED灯串的的亮度需求占空比为T 2，且T 2<25％；
第三通道LED灯串的的亮度需求占空比为T 3，且T 3<25％；
第四通道LED灯串的的亮度需求占空比为T 4，且T 4<25％。
则，占空比余量T q为100％-T 1；
且，第二通道LED灯串的开启占空比调节为T q*T 2/(T 2+T 3+T 4)；
第三通道LED灯串的开启占空比调节为T q*T 3/(T 2+T 3+T 4)；
第四通道LED灯串的开启占空比调节为T q*T 4/(T 2+T 3+T 4)。
基于前述本发明所提供的LED背光驱动电路，本发明还提供了一种基于低电势端开关控制的LED背光驱动方法，所述方法包括：
确定每组LED灯串中每个LED灯串的亮度需求占空比及均分占空比上限；
根据每组LED灯串中每个LED灯串的亮度需求占空比之间的比例关系分配每组LED灯串中每个LED灯串的开启占空比；
在一个实施例中，以四个LED灯串设置为一组，其均分占空比上限为25％；
第一通道LED灯串的的亮度需求占空比为T 1，且T 1>25％；
第二通道LED灯串的的亮度需求占空比为T 2，且T 2<25％；
第三通道LED灯串的的亮度需求占空比为T 3，且T 3<25％；
第四通道LED灯串的的亮度需求占空比为T 4，且T 4<25％。
则，第一通道LED灯串的开启占空比调节为T 1/(T 1+T 2+T 3+T 4)；
第二通道LED灯串的开启占空比调节为T 2/(T 1+T 2+T 3+T 4)；
第三通道LED灯串的开启占空比调节为T 3/(T 1+T 2+T 3+T 4)；
第四通道LED灯串的开启占空比调节为T 4/(T 1+T 2+T 3+T 4)。
与现有技术相比，本发明的一个或多个实施例可以具有如下优点：
1.由于其将若干LED灯串设置为一组并共用恒流模块，因此相比于现有技术中的直驱模式大大简化了电流结构，节省了电路结构成本。
2.本发明中由于在LED灯串的高电势端没有设置行扫描切换电路，因此避免了在切换时产生的大电流，消除显示中的残影现象；同时能够调节同组内的LED灯串能够突破均分占空比上限，达到更高的亮度。。
本发明的其它特征和优点将在随后的说明书中阐述，并且，部分地从说明书中变得显而易见，或者通过实施本发明而了解。本发明的目的和其他优点可通过 在说明书、权利要求书以及附图中所特别指出的结构来实现和获得。
附图说明
附图用来提供对本发明的进一步理解，并且构成说明书的一部分，与本发明的实施例共同用于解释本发明，并不构成对本发明的限制。在附图中：
图1是现有技术中采用直驱模式的LED背光驱动控制电路示意图；
图2是现有技术中采用行列扫描模式的LED背光驱动控制电路示意图；
图3是本发明的LED背光驱动控制电路示意图；
具体实施方式
为使本发明的目的、技术方案和优点更加清楚，以下结合附图对本发明作进一步地详细说明。
如图3所示为本发明的基于低电势端开关控制的LED背光驱动电路，在本发明中每一个LED灯串1的高电势端均直接连接于驱动电压V LED，同时每一个LED灯串1的低电势端连接一个通道控制开关器件2。多个LED灯串1组合构成一组LED灯串，每一组LED灯串共用一个恒流模块3。每组LED灯串中的多个通道控制开关器件2均连接于通道切换控制模块4，所述通道切换控制模块4连接于信号控制单元5，同时信号控制单元5与SPI接口单元单元6。
实施例1
本实施例中，每四个LED灯串构成一组，及四个LED灯串共用一个恒流模块。由于有四个LED灯串共用恒流模块，因此在所有通道LED灯串均分恒流模块的情况下，每一个通道的LED灯串的所能够达到的均分占空比上限为25％。且所有通道的LED的开启占空比的总和最大为100％，即四个通道享有恒流模块的全部占空比之和最大为100％。
但是当某一个LED灯串的亮度需求占空比超出25％时，本实施例的LED背光驱动方法中将同组内的其他LED灯串未中达到25％占空比的占空比余量补充到需要亮度增加的LED灯串中，从而使得该LED灯串突破25％的占空比限制。
如通道1、通道2、通道3、通道4的LED灯串亮度需求分别为35％、15％、20％、25％。从上述亮度需求可知，通道1的LED灯串的亮度需求已经超出的均 分占空比上限，即超过了25％占空比。而通道2和通道3的亮度需求只有15％和20％。即通道2产生了10％的占空比余量，通道3产生了5％的占空比余量，占空比余量总额达到15％。而通道1的亮度需求占空比超额增幅只需要35％-25％＝10％，因此当占空比余量总额完全能够覆盖亮度需求占空比超额增幅时，可以通过通道切换控制模块4将通道1的开启占空比提高至35％，而通道2、通道3、通道4的占空比根据其亮度需求分别设定为15％、20％、25％。
如通道1、通道2、通道3、通道4的LED灯串亮度需求分别为60％、15％、20％、25％。从上述亮度需求可知，通道1的LED灯串的亮度需求已经超出的均分占空比上限，即超过了25％占空比。而通道2和通道3的亮度需求只有15％和20％。即通道2产生了10％的占空比余量，通道3产生了5％的占空比余量，占空比余量总额达到15％。而通道1的亮度需求占空比超额增幅需要60％-25％＝35％。在这种情况下，占空比余量总额不能够覆盖亮度需求占空比超额增幅，因此在不影响其他通道亮度需求的情况下，通道1所能达到的最高的亮度需求占空比智能最高达到25％+15％＝40％。因此通过通道切换控制模块4将通道1的开启占空比提高至40％，而通道2、通道3、通道4的占空比根据其亮度需求分别设定为15％、20％、25％。
本实施例中，通过将所有通道的亮度需求占空比余量补充到有亮度需求占空比超额的通道中，从而实现了部分LED灯串通道的亮度上限被提高，以达到显示亮度增加的效果。
实施例2
与实施例1相同的，本实施例中，每四个LED灯串构成一组，及四个LED灯串共用一个恒流模块。由于有四个LED灯串共用恒流模块，因此在所有通道LED灯串均分恒流模块的情况下，每一个通道的LED灯串的所能够达到的最大的占空比为25％。但是当某一个LED灯串的亮度需求超出25％时，本实施例的LED背光驱动方法中将同组内的其他LED灯串未中达到25％占空比的占空比余量补充到需要亮度增加的LED灯串中，从而使得该LED灯串突破25％的占空比限制。
如通道1、通道2、通道3、通道4的LED灯串亮度需求分别为60％、15％、20％、25％。从上述亮度需求可知，通道1的LED灯串的亮度需求已经超出的均 分占空比上限，即超过了25％占空比。而通道2和通道3的亮度需求只有15％和20％，而通道4的亮度需求恰好为均分占空比上限25％。
本实施例中为了保证通道1亮度需求占空比达到60％，对其余通道2、通道3、通道4的亮度需求占空比进行压缩，具体的压缩方法为：当通道1的亮度需求占空比为60％时，则通道2、通道3的通道4的总的占空比最高为40％。因此通过通道切换控制模块4将通道2、通道3的通道4在的实际显示时的占空比根据亮度需求占空比的比例对40％占空比进行分配。
即，通道2的占空比为40％*15％/(15％+20％+25％+)＝10％；
通道3的占空比为40％*20％/(15％+20％+25％+)＝13.3％；
通道4的占空比为40％*25％/(15％+20％+25％+)＝16.7％。
本实施例中的LED背光驱动方法中在完全保证亮度增高的LED灯串的需求时，适当降低其他LED灯串的亮度，从而实现了部分LED灯串通道的亮度上限被提高，以达到显示亮度增加的效果。
实施例3
与实施例1相同的，本实施例中，每四个LED灯串构成一组，及四个LED灯串共用一个恒流模块。由于有四个LED灯串共用恒流模块，因此在所有通道LED灯串均分恒流模块的情况下，每一个通道的LED灯串的所能够达到的最大的占空比为25％。但是当某一个LED灯串的亮度需求超出25％时，本实施例的LED背光驱动方法中将同组内的其他LED灯串未中达到25％占空比的占空比余量补充到需要亮度增加的LED灯串中，从而使得该LED灯串突破25％的占空比限制。
如通道1、通道2、通道3、通道4的LED灯串亮度需求分别为60％、15％、20％、25％。从上述亮度需求可知，通道1的LED灯串的亮度需求已经超出的均分占空比上限，即超过了25％占空比。而通道2和通道3的亮度需求只有15％和20％，而通道4的亮度需求恰好为均分占空比上限25％。
本实施例中，通过等比例的压缩通道1、通道2、通道3、通道4的亮度需求占空比，从而实现通道1的LED灯串的亮度适当提高的效果。通过通道切换控制模块4对通道1、通道2、通道3、通道4的开启占空比按如下比例进行调整。
即，通道1的开启占空比为60％*/(60％+15％+20％+25％+)＝50％
通道2的占空比为15％*/(60％+15％+20％+25％+)＝12.5％；
通道3的占空比为20％*/(60％+15％+20％+25％+)＝16.7％；
通道4的占空比为25％*/(60％+15％+20％+25％+)＝20.8％。
本实施例中的LED背光驱动方法中通过等比例压缩通道1、通道2、通道3、通道4的亮度需求占空比，从而实现了部分LED灯串通道的亮度上限被提高，突破均分占空比上限，以达到显示亮度增加的效果。
从上市实施例1、实施例2和实施例3的记载可知，本发明对LED灯串的驱动控制的开启占空比调节依赖于本发明前述的LED背光驱动电路结构。只有通过在LED灯串的低电势端设置开关器件及通道切换控制模块才能够实现本发明上述实施例中对占空比的调节。
针对本发明中的LED驱动控制电路，由于其将若干LED灯串设置为一组并共用恒流模块，因此相比于现有技术中的直驱模式大大简化了电流结构，节省了电路结构成本。
另一方面，本发明中由于在LED灯串的高电势端没有设置行扫描切换电路，因此避免了在切换时产生的大电流，消除显示中的残影现象；同时能够调节同组内的LED灯串能够突破均分占空比上限，达到更高的亮度。
以上所述，仅为本发明的具体实施案例，本发明的保护范围并不局限于此，任何熟悉本技术的技术人员在本发明所述的技术规范内，对本发明的修改或替换，都应在本发明的保护范围之内。

Claims (9)

  1. 一种基于低电势端开关控制的LED背光驱动电路，其特征在于，所述LED背光驱动电路包括多个LED灯串1、通道控制开关器件2、恒流模块3、通道切换控制模块4、信号控制单元5和SPI接口单元单元6；
    每个所述LED灯串1的高电势端直接连接于LED驱动电压V LED，低电势端连接有一个通道控制开关器件2；多个LED灯串1形成一组LED灯串，每组LED灯串共用一个恒流模块3，每组LED灯串中的多个通道控制开关器件2连接于一个通道切换控制模块4；所述通道切换控制模块4用于控制本组内LED灯串的开启；
    所述通道切换控制模块4连接于信号控制单元5，所述信号控制单元5连接于SPI接口单元6；所述SPI接口单元6接收外部的显示信号，并传输至信号控制单元5，由信号控制单元5根据显示亮度需求来确定每组LED灯串内的每一个LED灯串的开启占空比，并将开启占空比数据传输至对应的通道切换控制模块4用于控制每组每组LED灯串内的每一个LED灯串的开启占空比。
  2. 根据权利要求1所述的LED背光驱动电路，其特征在于，所述恒流模块3采用IDAC电流源或VDAC电压源。
  3. 一种基于权利要求1-2所述的LED背光驱动电路的LED背光驱动方法，所述方法包括：
    确定每组LED灯串中每个LED灯串的亮度需求占空比及均分占空比上限；
    计算每个LED灯串的亮度需求占空比与均分占空比上限之间的差值以获取占空比剩余额度；
    将占空比剩余额度补偿给亮度需求占空比超出均分占空比上限的LED灯串，以提高该LED灯串的显示亮度；
  4. 根据权利要求3所述的LED背光驱动方法，其特征在于，若占空比剩余额度与均分占空比上限之和大于亮度需求占空比超出均分占空比上限的LED灯串的亮度需求占空比，则该LED灯串的实际开启占空设置为其亮度需求占空比；
    若占空比剩余额度与均分占空比上限之和小于亮度需求占空比超出均分占 空比上限的LED灯串的亮度需求占空比，则该LED灯串的实际开启占空比设置为占空比剩余额度与均分占空比上限之和。
  5. 根据权利要求4所述的LED背光驱动方法，其特征在于，以四个LED灯串设置为一组，其均分占空比上限为25％；
    第一通道LED灯串的的亮度需求占空比为T 1，且T 1>25％；
    第二通道LED灯串的的亮度需求占空比为T 2，且T 2<25％；
    第三通道LED灯串的的亮度需求占空比为T 3，且T 3<25％；
    第四通道LED灯串的的亮度需求占空比为T 4，且T 4<25％。
    则，占空比剩余额度T s为(25％-T 2)+(25％-T 3)+(25％-T 4)；
    当T s+25％大于T 1时，第一通道LED灯串的开启占空比设置为T 1；
    当T s+25％小于T 1时，第一通道LED灯串的开启占空比设置为T s+25％。
  6. 一种基于权利要求1-2所述的LED背光驱动电路的LED背光驱动方法，所述方法包括：
    确定每组LED灯串中每个LED灯串的亮度需求占空比及均分占空比上限；其中亮度需求占空比超出均分占空比上限的LED灯串记为L max；该LED灯串的的亮度需求占空比记为T max；
    计算占空比余量T q，所述占空比余量T q为100％-T max；
    除LED灯串L max之外的其余LED灯串根据其亮度需求占空比数值等比例分配所述占空比余量T q。
  7. 根据权利要求6所述的LED背光驱动方法，其特征在于，以四个LED灯串设置为一组，其均分占空比上限为25％；
    第一通道LED灯串的的亮度需求占空比为T 1，且T 1>25％；
    第二通道LED灯串的的亮度需求占空比为T 2，且T 2<25％；
    第三通道LED灯串的的亮度需求占空比为T 3，且T 3<25％；
    第四通道LED灯串的的亮度需求占空比为T 4，且T 4<25％。
    则，占空比余量T q为100％-T 1；
    且，第二通道LED灯串的开启占空比调节为T q*T 2/(T 2+T 3+T 4)；
    第三通道LED灯串的开启占空比调节为T q*T 3/(T 2+T 3+T 4)；
    第四通道LED灯串的开启占空比调节为T q*T 4/(T 2+T 3+T 4)。
  8. 一种基于权利要求1-2所述的LED背光驱动电路的LED背光驱动方法，所述方法包括：
    确定每组LED灯串中每个LED灯串的亮度需求占空比及均分占空比上限；
    根据每组LED灯串中每个LED灯串的亮度需求占空比之间的比例关系分配每组LED灯串中每个LED灯串的开启占空比；
  9. 根据权利要求8所述的LED背光驱动方法，其特征在于，以四个LED灯串设置为一组，其均分占空比上限为25％；
    第一通道LED灯串的的亮度需求占空比为T 1，且T 1>25％；
    第二通道LED灯串的的亮度需求占空比为T 2，且T 2<25％；
    第三通道LED灯串的的亮度需求占空比为T 3，且T 3<25％；
    第四通道LED灯串的的亮度需求占空比为T 4，且T 4<25％。
    则，第一通道LED灯串的开启占空比调节为T 1/(T 1+T 2+T 3+T 4)；
    第二通道LED灯串的开启占空比调节为T 2/(T 1+T 2+T 3+T 4)；
    第三通道LED灯串的开启占空比调节为T 3/(T 1+T 2+T 3+T 4)；
    第四通道LED灯串的开启占空比调节为T 4/(T 1+T 2+T 3+T 4)。
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