CN107545864B

CN107545864B - LED display device, driving circuit and driving method thereof

Info

Publication number: CN107545864B
Application number: CN201710667819.7A
Authority: CN
Inventors: 许明薛
Original assignee: Hangzhou Shixin Technology Co ltd
Current assignee: Hangzhou Shixin Technology Co ltd
Priority date: 2017-08-07
Filing date: 2017-08-07
Publication date: 2023-11-24
Anticipated expiration: 2037-08-07
Also published as: CN107545864A

Abstract

The utility model discloses an LED display device, a driving circuit and a driving method thereof. In the method, gray-scale data is divided into a storage bit and a transmission bit; transmitting the storage bits with the data signal before each frame period starts, and storing data of the storage bits in a driving circuit; and transmitting the transmission bit by adopting the data signal during the plurality of subframes, and combining the data of the storage bit and the transmission bit into subframe data for display, wherein the accumulated lighting time of the plurality of LED lamps in each frame period corresponds to a gray-scale data value represented by the data signal. The method reduces the memory space of the driving circuit and the circuit cost by transmitting the data of the memory bit only once before each frame period and transmitting the data of the transmission bit during a plurality of subframes of each frame period respectively.

Description

LED display device, driving circuit and driving method thereof

Technical Field

The present utility model relates to the field of display technologies, and more particularly, to an LED display device, and a driving circuit and a driving method thereof.

Background

The pixel elements of the LED display screen are Light Emitting Diodes (LEDs). The LED display screen has the following advantages: high gray scale, wide viewing angle, rich colors, and customizable screen shape. Therefore, the LED display is widely used in various fields of industry, traffic, commercial advertisement, information distribution, sports, etc.

In the LED display screen, a current control method and a conduction time control method can be adopted to realize multi-level gray scale. In the current control method, the brightness of the LED is controlled by adjusting the magnitude of the current flowing through the LED. In the on-time control method, constant current driving is employed to control the brightness of the LED by changing the duty ratio.

And using an on-time control method, expressing gray scales by using the accumulated lighting time of the LED lamp in each frame period, and displaying images. In each frame period, for each LED lamp, multi-bit gray-scale data corresponding to a respective pixel of the image is provided. The weight of each data bit of the gray scale data corresponds to the effective display time of the LED lamp. And extracting data bits from the gray-scale data bit by bit, and turning on or off the corresponding effective display time according to each data bit. The effective lighting time accumulated by the LED lamp coincides with the gray-scale data of the corresponding pixel throughout the frame period.

The LED display device comprises a plurality of driving circuits which are connected in series, and the LED lamps connected with the output ends of the driving circuits are turned on or off by controlling the high and low levels of the output ends of the driving circuits.

During operation, the LED display device receives a data signal DIN from the control terminal. The data signal DIN is passed in stages within the series of drive circuits, each of which can latch the gray scale data associated therewith. The LED display device also receives an enable signal EN matched with the data signal from the control terminal. Each driving circuit controls the driving terminal Out to output high and low levels according to the received data signal DIN and the enable signal EN.

The LED display device updates the screen at a fixed frame rate. In displaying an image, it is necessary to provide and display corresponding grayscale data for each LED pixel within one frame time Tf. In order to improve the visual effect, the refresh rate index of the LED display device needs to be increased, and one frame time Tf needs to be subdivided into a plurality of time slices, i.e., a plurality of subframes. In the conventional driving method of the LED display, the driving circuit completely stores gray-scale data of all the LED lamps controlled by the driving circuit before displaying the next frame of image during displaying the images of the continuous frames. Assuming that the gray-scale data of the LED display device is 16 bits, the number of scans of each frame of image of the LED display screen is 16, and the driving output ends included in the driving circuit are usually 16, the storage space required for one driving circuit to completely store the gray-scale data of the next frame of image is 16 bits 16 x 4096 bits.

With the development of applications, the LED display device needs to provide higher gray levels and use higher scanning numbers, for example, 32 times for each frame of image, which results in that the driving circuit needs to be built in a larger and larger storage space, and the circuit cost is higher.

Further improvements in LED display devices and driving circuits and driving methods thereof are desired to reduce memory space and circuit cost.

Disclosure of Invention

In view of the above, the embodiments of the present utility model provide a new LED display device, a driving circuit and a driving method thereof, which can reduce the memory space of the driving circuit by transmitting and storing a part of gray-scale data before a frame period.

According to a first aspect of the present utility model, there is provided a driving method of an LED display device including at least one driving circuit, and a plurality of LED lamps connected to the at least one driving circuit, the at least one driving circuit being sequentially connected in series, a data signal being transmitted by the driving circuit one by one, the LED display device displaying an image of a corresponding frame in each frame period, the frame period including a plurality of sub-frame periods, the driving method comprising: dividing gray-scale data into storage bits and transmission bits; transmitting the storage bits with the data signal before each frame period starts, and storing data of the storage bits in a driving circuit; and transmitting the transmission bit by adopting the data signal during the plurality of subframes, and combining the data of the storage bit and the transmission bit into subframe data for display, wherein the accumulated lighting time of the plurality of LED lamps in each frame period corresponds to a gray-scale data value represented by the data signal.

Preferably, the gray-scale data includes a plurality of data bits, bit weights of the plurality of data bits respectively corresponding to effective display times in the frame period.

Preferably, the high-significant bits of the grayscale data are used as the storage bits, and the low-significant bits of the grayscale data are used as the transmission bits.

Preferably, the bit weights of the stored bits are dispersed in selected subframes or each subframe of the plurality of subframes, and the bit weights of the transmission bits are dispersed in selected subframes of the plurality of subframes.

Preferably, the driving circuit further receives a shift clock, and shifts the data signal under control of the shift clock to obtain the storage bit and the transmission bit.

Preferably, the plurality of LED lamps are turned on or off according to the gray scale data during the plurality of subframes.

According to a second aspect of the present utility model, there is provided an LED display device for displaying an image of a corresponding frame in a plurality of consecutive frame periods, the frame periods including a plurality of sub-frame periods, the LED display device comprising: at least one driving circuit; and a plurality of LED lamps connected with the at least one driving circuit, wherein the at least one driving circuit is connected in series in sequence, data signals are transmitted by the driving circuits one by one, the at least one driving circuit receives and stores storage bits of the data signals before each frame period starts, and during the plurality of subframes, transmission bits of the data signals are received, and data of the storage bits and the transmission bits are combined into subframe data for displaying, so that the accumulated lighting time of the plurality of LED lamps in each frame period corresponds to a gray scale data value represented by the data signals.

Preferably, the driving circuit includes: a storage unit for storing the storage bits of the gray-scale data; a latch unit for storing the transmission bit of the gray-scale data; a shift register group for receiving a data signal and shifting the data signal among a plurality of registers of the shift register group under control of a shift clock signal, thereby obtaining gray-scale data; a storage selection module for transmitting the storage bit and the transmission bit of the gray-scale data to the storage unit and the latch unit, respectively; a reading module for reading the storage bits of the gray-scale data from the storage unit; the display processing module is used for judging whether transmission bits of the gray-scale data exist or not, and combining storage bits and transmission bits of the gray-scale data into subframe data when the transmission bits exist; and a constant current driving module for providing a driving current such that an accumulated lighting time of the plurality of LED lamps in each frame period corresponds to a gray scale data value represented by the data signal.

Preferably, the storage selection module transfers the storage bits of the gray-scale data to the storage unit before each frame period starts, and transfers the transmission bits of the gray-scale data to the latch unit during the plurality of subframes.

Preferably, the driving circuit turns on or off the plurality of LED lamps according to the gray scale data during the plurality of subframes.

According to a third aspect of the present utility model, there is provided a driving circuit of an LED display device, the driving circuit being connected to a plurality of LED lamps, displaying an image of a corresponding frame in each frame period according to gray-scale data, the frame period including a plurality of sub-frame periods, the driving circuit comprising: a storage unit for storing the storage bits of the gray-scale data; a latch unit for storing the transmission bit of the gray-scale data; a shift register group for receiving the data signal and shifting the data signal in a plurality of registers under control of a shift clock signal, thereby obtaining gray-scale data; a storage selection module for transmitting the storage bit and the transmission bit of the gray-scale data to the storage unit and the latch unit, respectively; a reading module for reading the storage bits of the gray-scale data from the storage unit; the display processing module is used for judging whether transmission bits of the gray-scale data exist or not, and combining storage bits and transmission bits of the gray-scale data into subframe data when the transmission bits exist; and a constant current driving module for providing a driving current such that an accumulated lighting time of the plurality of LED lamps in each frame period corresponds to a gray scale data value represented by the data signal.

According to the driving method of the embodiment of the present utility model, gray-scale data is divided into two parts: a storage bit and a transmission bit, data of the storage bit being transferred and stored before a frame period, data of the transmission bit being transferred during a subframe of the frame period. At least the data of the transmission bit does not occupy a memory space inside the driving circuit, is transmitted only during the sub-frame, and is then combined with the pre-stored memory bit data to form sub-frame data. The LED display device not only can obtain better display performance, but also can reduce the storage space.

Drawings

The above and other objects, features and advantages of the present utility model will become more apparent by describing embodiments thereof with reference to the following drawings in which:

fig. 1 is a schematic block diagram of an LED display device according to the prior art.

Fig. 2 is a schematic block diagram of a driving circuit in an LED display device according to the related art.

Fig. 3 is a schematic block diagram of an LED display device according to an embodiment of the present utility model.

Fig. 4 is a schematic block diagram of a driving circuit in an LED display device according to an embodiment of the present utility model.

Fig. 5 is a timing chart of a driving method of an LED display device according to an embodiment of the present utility model.

Detailed Description

The utility model will be described in more detail below with reference to the accompanying drawings. Like elements are denoted by like reference numerals throughout the various figures. For clarity, the various features of the drawings are not drawn to scale. Furthermore, some well-known portions may not be shown.

In the present utility model, the term "storage bit" means data transferred before the start of each frame period and stored in the driving circuit. The term "transmission bit" denotes a gray-scale data bit transmitted during a plurality of subframes. During a plurality of subframes, data of the storage bits and the transmission bits are combined into subframe data, and a driving current is generated according to the subframe data to perform display.

Fig. 1 is a schematic block diagram of a prior art LED display device. The LED display device includes a control terminal 110 and a plurality of LED modules 210. The modules 210 are, for example, serially connected. Each LED module 210 includes a plurality of driving circuits 211 connected in series in sequence, and a plurality of LED lamps 212 arranged in an array.

In each LED module 210, the plurality of driving circuits 211 are respectively used to drive the plurality of LED lamps 212 connected thereto, thereby being used to display a partial area of an image. The plurality of modules 210 are respectively used for displaying images of different areas, so that the images can be spliced together into a complete image.

The control terminal 110 provides the data signal DIN, the shift clock DCLK, and the count clock GCLK to the plurality of die sets.

The shift clock DCLK and the count clock GCLK described above are transferred from the control terminal 110 to the corresponding shift signal terminal DCLK and the count signal terminal GCLK of each driving circuit 211 in each of the die sets 210.

The data signal DIN is transmitted from module to module. The data signal DIN is used to represent gray scale data of the pixel. Inside each module 210, the data signal DIN is transferred from the driving circuit 211 to the next. From the control terminal 110, the data signal DIN is first supplied to the data input terminal DIN of the first driving circuit 211 of the first LED module 210, and sequentially transferred among the plurality of driving circuits in the LED module 210, and is output through the data output terminal Dout of the last driving circuit. The data signal DIN is then provided to the second LED module. The data signal DIN is sequentially transmitted through the LED modules connected in series, the last LED module of the previous stage is output to the first driving circuit of the LED module of the current stage, and the last driving circuit of the LED module of the current stage is output to the first driving circuit of the LED module of the next stage. The last driving circuit of the last stage LED module does not output a data signal.

In each LED module, the anode terminals of the plurality of LED lamps 212 are respectively connected to the power supply VDD, and the cathode terminal is connected to the driving output terminal Out of the corresponding driving circuit 211. When the driving output Out supplies a pull-down constant current, the LED lamp 212 is turned on.

In the LED display device, the LED modules include respective driving circuits. In each subframe in a frame period, the control end repeatedly transmits gray-scale data bits to the driving circuit of the LED module. Therefore, all the gradation data bits in the LED display device are storage bits.

Fig. 2 is a schematic block diagram of a driving circuit in an LED display device according to the related art. The driving circuit 211 includes a shift register group 2111, a storage unit 2112, a PWM module 2113, and a driving module 2114.

The shift register group 2111 receives the shift clock signal DClk from the control terminal 110 through the shift signal terminal DClk, and receives the data signal supplied from the control terminal 110 or the data output terminal Dout of the previous stage driving circuit 211 through the data signal input terminal Din. The shift register group 2111 receives the data signal Din, and the data signal Din is shifted among the plurality of registers in the shift register group 2111 under the control of the shift clock signal DCLK, and is output to the next stage driving circuit or the next stage LED module via the data signal output terminal Dout. The storage unit 2112 locally stores the received grayscale data. The PWM module 2113 counts using a count clock GCLK, and the count value coincides with the value of the gray-scale data, thereby generating a pulse width modulation signal. Therefore, the duty ratio of the pulse modulation signal coincides with the value of the gray-scale data. For example, the gray-scale data of the LED display device is 16Bit, and when the driving circuit reads that the gray-scale data value of a certain LED lamp in the next frame of image is 249, the driving circuit controls the driving end connected with the LED lamp to output a duty ratio of 249/65535 when the next frame of image is displayed. The driving module 2114 supplies a pull-down constant current at each driving output Out according to the PWM signal, thereby controlling the on/off of the LED lamp 212 and the duration thereof.

Fig. 3 is a schematic block diagram of an LED display device according to an embodiment of the present utility model. The LED display device includes a control terminal 120 and a plurality of LED modules 310. The modules 310 are, for example, serially connected. Each LED module 310 includes a plurality of driving circuits 311 connected in series in sequence, and a plurality of LED lamps 212 arranged in an array.

In each LED module 310, the plurality of driving circuits 311 are respectively used to drive the plurality of LED lamps 212 connected thereto, thereby being used to display a partial area of an image. The modules 310 are respectively used for displaying images of different areas, so that the images can be spliced together into a complete image.

The control terminal 120 supplies the data signal DIN and the shift clock DCLK to the plurality of blocks.

The shift clock DCLK is transferred from the control terminal 120 to the corresponding shift signal terminal DCLK of each driving circuit 311 in each module 310.

The data signal DIN is transmitted from module to module. The data signal DIN is used to represent gray scale data of the pixel. Inside each module 310, the data signal DIN is transferred by the driving circuit 311 one by one. From the control terminal 120, the data signal DIN is first supplied to the data input terminal DIN of the first driving circuit 311 of the first LED module 310, and sequentially transferred among the plurality of driving circuits in the LED module 310, and output through the data output terminal Dout of the last driving circuit. The data signal DIN is then provided to the second LED module. The data signal DIN is sequentially transmitted through the LED modules connected in series, the last LED module of the previous stage is output to the first driving circuit of the LED module of the current stage, and the last driving circuit of the LED module of the current stage is output to the first driving circuit of the LED module of the next stage. The last driving circuit of the last stage LED module does not output a data signal.

In each LED module, the anode terminals of the LED lamps 212 are respectively connected to the power supply VDD, and the cathode terminal is connected to the driving output terminal Out of the corresponding driving circuit 311. When the driving output Out supplies a pull-down constant current, the LED lamp 212 is turned on.

In the LED display device of this embodiment, the control end sends the gray-scale data storage bit of the next frame image after the transmission switching through the data signal DIN, where the transmission switching is performed after all the data bits of the current frame image, including the storage bit and the transmission bit, are transmitted.

After the display of the current frame is completed, the display is switched, and the control end sends the transmission bit in the previous subframe of the transmission bit for display through the data signal DIN. When all transmission bits are transmitted, the control end performs transmission switching and sends the image data of the next frame according to the mode.

The driving circuit reads the data value of the storage bit and receives the data value of the transmission bit when displaying. Further, the driving circuit combines the storage bits and the transmission bits into sub-frame data. Whether the corresponding driving output terminal OUT outputs a pull-down constant current is determined according to the bit data value 0 or 1 of the gray-scale data. That is, when the bit data value is 0, the corresponding driving output terminal OUT is controlled not to output a pull-down constant current, and the LED lamp connected with the driving output terminal is turned off; when the bit data value is 1, the corresponding driving output end OUT is controlled to output a pull-down constant current consistent with the gray scale data duration, and the LED lamp connected with the driving output end OUT is turned on.

Similarly, when the driving circuit performs display, it is determined whether the corresponding driving output terminal Out outputs a pull-down constant current and the duration of the pull-down constant current according to the received data value of the transmission bit.

Fig. 4 is a schematic block diagram of a driving circuit in an LED display device according to an embodiment of the present utility model. The driving circuit 311 includes a shift register group 2111, a memory selection module 3111, a memory unit 2112, a latch unit 3112, a reading module 3113, a display processing module 3114, and a driving module 2114.

The shift register group 2111 receives a clock signal from the control terminal 120 through the shift clock signal terminal DClk, and receives a data signal supplied from the control terminal 120 or the data output terminal Dout of the previous stage driving circuit 311 through the data signal input terminal Din. Under the control of the shift clock signal DCLK, the data signal Din is shifted among the plurality of registers in the shift register group 2111, and is output to the next stage driving circuit or the next stage LED module via the data signal output terminal Dout.

The memory selection module 3111 stores or latches display data. For example, after the transmission of all the data bits of the current frame image is completed and the transmission is switched, the control terminal transmits the gray-scale data storage bits of the next frame image before the display of the next frame image is started, and the storage selection module 3111 writes the gray-scale data transferred from the shift register into the storage unit 2112. During the display period of one frame, if the transmission bit exists in the next subframe, the control terminal sends the gray-scale data transmission bit of the next subframe, and the storage selection module 3111 latches the data transferred by the shift register to the latch unit 3112 for use in the display of the next subframe.

The reading module 3113 reads the memory bit to be displayed for the current subframe, and sends the memory bit to the display processing module 3114.

The display processing module 3114 determines whether the current subframe has transmission bits to be displayed, if so, the storage bits of the gray-scale data and the transmission bits compose the subframe data, and the driving module 2114 is controlled to perform driving display according to the obtained data, and a pull-down constant current and a duration thereof are provided at each driving output terminal Out, so as to control the on/off of the LED lamp 212 and the duration thereof.

According to the driving circuit provided by the embodiment of the utility model, during the display period of each frame of image, part of gray-scale data bits are stored in the driving circuit as storage bits, and part of gray-scale data bits are transmitted sub-frame by sub-frame as transmission bits, so that the LED display device can obtain better display performance and reduce storage space.

For convenience of description, the driving method provided by the utility model is further described by taking 10Bit gray-scale data as an example. The 10Bit gray-scale data is marked as D [0:9]]The weight of the data bits may be 2 ⁿ To represent. Assume that the least significant bit of the gray-scale data corresponds to the weight W [0] of the effective display time]1, each data bit D [ i ]]Weights W [ i ] corresponding to effective display times]Is 2 ⁱ As shown in table 1:

TABLE 1 weights of different bits of 10-bit Gray data in the prior art

Data bits	D[0]	D[1]	D[2]	D[3]	D[4]	D[5]	D[6]	D[7]	D[8]	D[9]
											Weight W	1	2	4	8	16	32	64	128	256	512

And if the effective display time corresponding to the least significant bit of the gray scale data is t. The effective display time corresponding to each gray-scale data bit is shown in table 2 according to the weight of the data bit:

TABLE 2 effective display time for different bits of 10-bit gray-scale data in the prior art

Data bits

D[0]

D[1]

D[2]

D[3]

D[4]

D[5]

D[6]

D[7]

D[8]

D[9]

Effective time

t

2t

4t

8t

16t

32t

64t

128t

256t

512t

Taking the upper 7 bits D3:9 of the gray-scale data as storage bits, and the lower 3 bits D0, D1 and D2 of the gray-scale data as transmission bits; and subdivides a frame time Tf into 32 time slices, i.e., 32 subframes. And dividing the storage bits D [3:9] into 4-bit storage high bits D [6:9] and 3-bit storage low bits D [3:5], wherein the storage high bits are gray scale data bits displayed by each subframe, and the storage low bits are gray scale data bits displayed by only partial subframes.

Since the high order bits D [6:9] are stored for display per sub-frame, the effective display time of the high order bits stored in each sub-frame is shown in Table 3.

TABLE 3 effective display time for storing high order bits in each sub-frame

The number of occurrences of the stored low order D [3:5] in 32 subframes and the effective display time may be as shown in Table 4.

TABLE 4 subframe configuration and effective display time for storing low order bits

Data bits	D[5]	D[4]	D[3]
				Total effective time	32t	16t	8t
Number of subframes	16	8	4
				Effective time	2t	2t	2t

As can be seen from table 4, the number of occurrences of the lower bits in the 32 subframes is 16+8+4, and a total of 28 times is stored. There are 4 subframes remaining in the 32 subframes, which can be used as displays of the transmission bits D [0], D [1], D [2 ]. The order of display of the 10Bit gray-scale data D [0:9] in each sub-frame and the effective display time can be as shown in Table 5.

Table 5, gray scale data arrangement example

As shown in Table 5, the effective display time for storing the high order D [6:9] is dispersed into 32 subframes; storing 16 sub-frames of the low order D5 in 32 sub-frames, wherein the occurrence of the low order D5 is once every 2 sub-frames for the purpose of uniform display; storing that the low order D4 appears in 8 subframes in 32 subframes, namely, appears once every 4 subframes; the lower bits D3 are stored to occur in 4 subframes out of 32 subframes, i.e. every 8 subframes. The 32 subframes are divided into 4 groups, each 8 subframes are divided into one group, and after the storage bits are uniformly distributed, each group of subframes is free for one subframe position, so that the transmission bits can be displayed. The idle positions of the first and the third groups of subframes are used for displaying a transmission bit D2, and the effective display time is 2t; the idle position of the second group of subframes is used for displaying a transmission bit D1, and the effective display time is 2t; the free position of the fourth group of subframes is used for displaying the transmission bit D [0], and the effective display time is t.

Thus, the display of the 10-bit gray-scale data shown in table 2 can be completed.

In the LED display device, gray-scale data bits need to be transferred to bits before display is performed, wherein the storage bits need to be stored in advance in the storage unit 2112 of the driving circuit, and the transfer bits need to be transferred to bits at the start of display, and the transfer should be performed in a subframe preceding the displayed subframe without considering scanning. Therefore, without considering scanning, if the 10Bit gray-scale data is displayed in the order shown in table 5, then: the storage bits D [3:9] are required to be transmitted and stored before the display of the image of the frame is started, and the transmission bits D [0], D [1] and D [2] are required to be transmitted before the subframes displayed respectively. As shown in table 5, transmission bit D2 is displayed in subframe 2 and subframe 18, transmission bit D1 is displayed in subframe 10, and transmission bit D0 is displayed in subframe 26, then: the transmission bit D2 should be transmitted in sub-frame 1 and sub-frame 17, the transmission bit D1 should be transmitted in sub-frame 9, and the transmission bit D0 should be transmitted in sub-frame 25; the other subframes only need to read the stored data bits when displaying, and the data transmission requirement is not met, so that the subframes without the transmission requirement can be utilized to transmit the gray-scale data storage bits of the next frame of image. For example, the storage bits D [3:9] may be transmitted and stored during subframes 26-32 of the previous frame image. Table 6 shows the transmission display timing sequence of the above 10Bit gray scale data without considering scanning, and the timing diagram is shown in FIG. 5.

Table 6, gray data Transmission and display timing examples

In the above embodiment, the driving circuit needs to store data from the original 10Bit to 7Bit, and the memory space needed in the circuit is reduced by 30% from the original 10Bit by 16 to 7Bit by 16.

The above embodiment takes 10Bit gray-scale data as an example, which is only for convenience of description, and can be extended for more bits of gray-scale data in practical application. When the number of bits of the gray-scale data increases, the number of bits of the transmission bits may be increased, or the number of bits storing the lower bits, the number of extended subframes, etc. may be increased. For example, there may be 4 transmission bits, 12 storage bits, 8 of which store high bits, 4 of which store low bits, and a subframe number of 64 for 16Bit gray scale data. As long as it is ensured that all the storage bits are transferred into place before the display is switched, that is, there are enough subframes not required to transfer the transmission bits to transfer the storage bits of the gray-scale data of the next frame image before the next frame image is displayed. Also, the number of bits of the supported gray-scale data can be changed by changing the number of bits of the transmission Bit and the storage Bit given the storage space, for example, to achieve the case of supporting higher gray-scale data such as 18Bit gray-scale data.

The number of bits of the gray-scale data expressed in the embodiments of the present utility model, the number of bits of the high-order bits stored, the low-order bits stored, and the transmission bits are all examples, and scanning is not considered in the transmission examples. Those skilled in the art can use the present utility model to select different bits, set different weights, increase the number of scans, and change the bit and weight arrangement in the subframe and the transmission position of the gray data bits.

The utility model provides a driving method which is basically characterized in that n-bit gray-scale data are split: the a bit is used as a storage high bit and stored in the driving circuit, and each subframe is displayed; b bits are used as storage low bits and stored in the driving circuit, and part of subframes are displayed; the remaining lower bits of the n-a-b bit gray scale data are used as transmission bits, so that the storage space inside a driving circuit is not occupied, and the transmission is carried out in the previous subframe needing to be displayed.

The LED driving method and the display system can well meet the performance indexes such as the increasingly improved refresh rate and gray level of the LED display device, effectively reduce the storage space required by the driving circuit, and improve the display performance and the display effect of the system.

Although the preferred embodiments of the present utility model have been described above, it should be understood that the present utility model is not limited to the embodiments described above, and that various changes and modifications can be made by one skilled in the art without departing from the spirit and scope of the present utility model, and the scope of the present utility model shall be defined by the appended claims.

The above description is only of the preferred embodiments of the present utility model and is not intended to limit the present utility model, and various modifications and variations may be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.

Claims

1. A driving method of an LED display device including at least one driving circuit and a plurality of LED lamps connected to the at least one driving circuit, the at least one driving circuit being sequentially connected in series, a data signal being transmitted from the driving circuit to the driving circuit, the LED display device displaying an image of a corresponding frame in each frame period, the frame period including a plurality of sub-frame periods, the driving method comprising:

dividing gray-scale data into storage bits and transmission bits;

transmitting the storage bits with the data signal before each frame period starts, and storing data of the storage bits in a driving circuit;

during the plurality of subframes, dispersing bit weights of storage high bits of the storage bits in each of the plurality of subframes, transmitting the transmission bits with the data signal, and combining data of the storage bits and the transmission bits into subframe data, and generating a driving current according to the subframe data for display,

wherein the accumulated lighting time of the plurality of LED lamps in each frame period corresponds to a gray scale data value represented by the data signal.

2. The driving method of claim 1, wherein the gray-scale data includes a plurality of data bits, bit weights of the plurality of data bits respectively corresponding to effective display times in a frame period.

3. The driving method according to claim 2, wherein a high-significant bit of the grayscale data is used as the storage bit and a low-significant bit of the grayscale data is used as the transmission bit.

4. The driving method of claim 3, wherein bit weights of storage low bits of the storage bits are dispersed in selected subframes of the plurality of subframes, and bit weights of the transmission bits are dispersed in selected subframes of the plurality of subframes.

5. The driving method according to claim 1, wherein the driving circuit further receives a shift clock, and shifts a data signal under control of the shift clock to obtain the storage bit and the transmission bit.

6. The driving method according to claim 1, wherein the plurality of LED lamps are turned on or off according to the grayscale data during the plurality of subframes.

7. An LED display device for displaying an image of a corresponding frame in a continuous plurality of frame periods, the frame periods including a plurality of sub-frame periods, the LED display device comprising:

at least one driving circuit; and

a plurality of LED lamps connected with the at least one driving circuit,

wherein the at least one driving circuit is connected in series in sequence, the data signals are transmitted by the driving circuit one by one,

the at least one driving circuit receives and stores a storage bit of the data signal before each frame period starts, distributes a bit weight of a storage high bit of the storage bit in each of the plurality of subframes during the plurality of subframes, receives a transmission bit of the data signal and combines data of the storage bit and the transmission bit into subframe data, and generates a driving current to display according to the subframe data such that an accumulated lighting time of the plurality of LED lamps in each frame period corresponds to a gray scale data value represented by the data signal.

8. The LED display device of claim 7, wherein the grayscale data includes a plurality of data bits, bit weights of the plurality of data bits respectively corresponding to effective display times in a frame period.

9. The LED display device of claim 8, wherein the more significant bits of the grayscale data are the storage bits and the less significant bits of the grayscale data are the transmission bits.

10. The LED display device of claim 9, wherein the bit weights of the storage low order bits of the storage bits are dispersed in selected ones of the plurality of subframes and the bit weights of the transmission bits are dispersed in selected ones of the plurality of subframes.

11. The LED display device of claim 7, wherein the drive circuit comprises:

a storage unit for storing the storage bits of the gray-scale data;

a latch unit for storing the transmission bit of the gray-scale data;

a shift register group for receiving a data signal and shifting the data signal among a plurality of registers of the shift register group under control of a shift clock signal, thereby obtaining gray-scale data;

a storage selection module for transmitting the storage bit and the transmission bit of the gray-scale data to the storage unit and the latch unit, respectively;

a reading module for reading the storage bits of the gray-scale data from the storage unit;

the display processing module is used for judging whether transmission bits of the gray-scale data exist or not, and combining storage bits and transmission bits of the gray-scale data into subframe data when the transmission bits exist; and

and the constant current driving module is used for providing driving current so that the accumulated lighting time of the plurality of LED lamps in each frame period corresponds to the gray-scale data value represented by the data signal.

12. The LED display device of claim 11, wherein the memory selection module transfers the memory bits of the gray-scale data to the memory cells before each frame period starts, and transfers the transfer bits of the gray-scale data to the latch cells during the plurality of subframes.

13. The LED display device of claim 7, wherein the drive circuit turns on or off the plurality of LED lamps according to the grayscale data during the plurality of subframes.

14. A driving circuit of an LED display device, the driving circuit being connected to a plurality of LED lamps, displaying an image of a corresponding frame in each frame period according to gray-scale data, the frame period including a plurality of sub-frame periods, the driving circuit comprising:

a storage unit for storing the storage bits of the gray-scale data;

a latch unit for storing the transmission bit of the gray-scale data;

a shift register group for receiving a data signal and shifting the data signal in a plurality of registers under control of a shift clock signal, thereby obtaining gray-scale data;

15. The driving circuit of claim 14, wherein the storage selection module transfers the storage bits of the gray-scale data to the storage unit before each frame period starts, and transfers the transmission bits of the gray-scale data to the latch unit during the plurality of subframes.