CN2745163Y - Device for controlling gray scale of LED display screen - Google Patents
Device for controlling gray scale of LED display screen Download PDFInfo
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- CN2745163Y CN2745163Y CN 200420084711 CN200420084711U CN2745163Y CN 2745163 Y CN2745163 Y CN 2745163Y CN 200420084711 CN200420084711 CN 200420084711 CN 200420084711 U CN200420084711 U CN 200420084711U CN 2745163 Y CN2745163 Y CN 2745163Y
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Abstract
The utility model discloses a device for controlling gray scale of an LED display screen, comprising a cell memory, an address counter, a frequency demultiplier, a grey scale counter, a gray-scale value comparator and a serial entry drive chip set. The utility model is introduced the cell memory and adopted with the less expensive serial entry drive chip, such as TIP6B595 or TLC5921, realizing the gamma control effect of the expensive TLC5902. Namely, the LED is the gamma control technique of 'consistency luminescence' without the dynamic state false contouring phenomenon because of the realization of subfield mode by subfield mode, substantially raising the display image quality of the LED. Compared with the LED screen with TLC5902 scheme, the data is all processed concurrently, but the cost of the chip is obviously reduced. Moreover, compared with the scheme of consecutive processing machine format, the data processing rate and the image quality is obviously improved with very high ratio of performance and price.
Description
Technical field
The utility model belongs to light emitting diode (LED) display screen technology field, particularly the gray-scale Control and the Driving technique of LED screen.
Background technology
The method that two kinds of control LED gray scales are arranged: a kind of is to change the electric current that flows through LED; Another kind is the visual persistence that utilizes human eye, realizes gray-scale Control with pulse duration modulation method, just periodically-varied light impulse length, i.e. dutycycle.As long as this cycle that repeats to light is enough short, promptly display frequency is enough high, and human eye is being shaken with regard to imperceptible light-emitting pixels.Because width modulation is more suitable in digital control, nearly all LED screen all is to adopt width modulation to control gray shade scale.
LED directly is connected with chip for driving, and with regard to data entry mode, the LED chip for driving can be divided into two big classes: serial input chip for driving, and as TIP6B595 and TLC5921, and parallel input chip for driving, as TLC5902.LED screen uses several ten thousand even tens0000 chip for driving, and it is important to the LED anode for the price of chip for driving.
Serial input chip for driving TLC5921 is generally adopted because of cheap, and normal employing the " a son display mode " realized gray-scale Control, and a son weight is that output pulse width length equals the effective time span of chip for driving output enable end.This gradation control method is simple and easy to realize, but the general character shortcoming of an existence display mode, the generation gray scale is disturbed when promptly dynamically showing, shows as dynamic false outline (DFC) phenomenon, as seeing in plasm TV.
The view data of gray-scale Control and chip for driving TLC5902 adopts parallel input, the pulse of output pulse width subject image data modulation, driving LED is luminous, in a TV Field LED luminous be successional, the control of luminosity subject image data.Obviously, there is not the dynamic false outline phenomenon in this gradation control method, and picture quality is better than a son display mode, but such chip for driving is not generally adopted because of costing an arm and a leg.
Summary of the invention
The purpose of this utility model is to provide a kind of device of controlling the light emitting diode (LED) display screen gray scale.This device uses cheap serial input chip for driving, can realize the gray-scale Control effect of expensive parallel input chip for driving, thereby reduce cost of products effectively, greatly is beneficial to industrialization.
LED display, particularly outdoor screen, it is that subdivision carries out that its LED drives.Data are serial transfers in the unit, then are parallel transfer between the unit.The view data that the utility model adopts cell memory to store a certain display unit, cell memory is arranged in the unit controls driver.Desirable 16 * 8 (totally 128 points) of pixel count in the display unit, 16 * 16 (totally 256 points), 32 * 16 (totally 512 points) etc., it is few more to count, and attainable number of greyscale levels is high more, or display frequency is high more.
The gray-scale Control device of the utility model design is made up of cell memory, address counter, frequency divider, gray scale counter, gray-scale value comparator circuit and serial input chip for driving group.Cell memory is stored the view data of this unit, and the cell memory address increases progressively since 0, presses the unit and shows opposite sequential storage view data.Address counter moves the address bus signal of clock generating unit storer according to string, and address counter is a cycle counter, and when auto zero when 0 count down to M-1, M equals the display unit pixel count.
The utility model serial input chip for driving group comprises red, green, blue three groups, controls a kind of LED of color respectively, and the chip for driving in each group is by the serial mode cascade.
The gray-scale value comparator circuit is further divided into red gray-scale value comparator circuit, green gray-scale value comparator circuit and blue color shade value comparator circuit in the utility model, connects homochromy chip for driving group behind the gray-scale value comparator circuit of all kinds.Gray-scale value comparator circuit structure of all kinds is identical, all by or door, null detector and " greater than " comparer forms." greater than " comparer finishes the data gray-scale value read from cell memory and the comparison of gray scale Counter Value.If the data gray-scale value of reading from cell memory is greater than the gray scale Counter Value, " greater than " comparer is output as ' 1 '; If the data gray-scale value read from cell memory is less than or equal to the gray scale Counter Value, then " greater than " comparer is output as ' 0 '.Under string moves clock control, " greater than " the comparison information serial of comparer output moves into this group chip for driving.Null detector detects whether the data gray-scale value read from cell memory is ' 0 ', if then be output as ' 1 ', by or door reset " greater than " comparer makes it be output as ' 0 '.
Each TV Field begins, and positive pulse field sync signal (Vsync) is to the zero clearing that resets of address counter, gray scale counter and comparer.Move at string under the control of clock, cell memory 0 begins to read view data from the address, red (R) data are sent into red gray-scale value comparator circuit, and green (G) data and Lan Se (B) data are sent into green gray-scale value comparator circuit and blue color shade value comparator circuit respectively.
The every string through M moved clock, and string moves clock and produces a positive pulse through frequency divider, and one the tunnel sends into the gray scale counter as count pulse, make densitometer numerical value increase progressively 1, another road is latched at the M position this comparison information altogether, and is controlled the luminous of corresponding LED as the latch signal of chip for driving.
Compared with prior art, the utlity model has following beneficial effect:
1, parallel processing view data, the speed height.
2, use cheap serial input chip for driving, realized the gray-scale Control effect of expensive parallel input chip for driving, with low cost.
3, different with a son display mode, the direct subject image data modulation of the pulse width of driving LED, the luminous of LED is successional in each TV Field, do not have distinctive dynamic false outline phenomenon under the son display mode.
Below in conjunction with drawings and Examples the utility model is described further.
Description of drawings
Serve as reasons a large amount of display units of Fig. 1 are formed the synoptic diagram of LED screen.
Fig. 2 is the utility model structure principle chart.Wherein, 1 is cell memory, and 2 is address counter, and 3 is the gray scale counter, 4 be " greater than " comparer, 5 is null detector, and 6 are or door, and 7 be frequency divider, and 8 is that chip for driving is imported in serial.
Fig. 3 is the mapping relations figure of unit storage order and pixel sequence number.
Embodiment
Referring to Fig. 1, LED display, particularly outdoor screen, it is that subdivision carries out that its LED drives.Data are serial transfers in the unit, then are parallel transfer between the unit.The view data that the utility model adopts cell memory to store a certain display unit, cell memory is arranged in the unit controls driver.Desirable 32 points of pixel count in the display unit, 64 points, 128 points, 256 points, 512 or 1024 etc.In the present embodiment, being at 512 with the pixel count in the display unit is that example describes.
As shown in Figure 2, the device of the control LED screen gray scale of the utility model design is made up of cell memory 1, address counter 2, gray scale counter 3, frequency divider 7, gray-scale value comparator circuit and serial input chip for driving group.
The view data of this unit of cell memory 1 storage, cell memory address increase progressively since 0, press the opposite sequential storage view data of unit demonstration, as shown in Figure 3.Sense data through chip for driving displacement inverted sequence once can correctly show.
The gray-scale value comparator circuit comprises red gray-scale value comparator circuit, green gray-scale value comparator circuit and blue color shade value comparator circuit; Serial input chip for driving group comprises red chip for driving group, green chip for driving group and blue look chip for driving group, controls a kind of LED of color respectively, and the chip for driving in each group is by the serial mode cascade.Chip for driving group of all kinds is connected after its homochromy gray-scale value comparator circuit.
Gray-scale value comparator circuit structure of all kinds is identical, and chip for driving group structure of all kinds is also identical, so Fig. 2 only shows the details of red gray-scale value comparator circuit (seeing left empty frame among the figure) and red chip for driving group (seeing right empty frame among the figure).Referring to Fig. 2, gray-scale value comparator circuit of all kinds by or door 6, null detector 5 and " greater than " comparer 4 forms.Null detector 5 detects whether the data gray-scale value of reading from cell memory 1 is ' 0 ', if then be output as ' 1 ', by or door 6 reset " greater than " comparer 4 makes it be output as ' 0 '." greater than " comparer 4 finishes the data gray-scale value read from cell memory 1 and the comparison of gray scale Counter Value.If the data gray-scale value of reading from cell memory 1 is greater than the gray scale Counter Value, " greater than " comparer 4 is output as ' 1 '; If the data gray-scale value read from cell memory 1 is less than or equal to the gray scale Counter Value, then " greater than " comparer 4 is output as ' 0 '.Under string moves clock clk1 control, " greater than " the comparison information serial of comparer 4 outputs moves into homochromy chip for driving group.
Every through 512 clk1 clocks, moved 512 after, clk1 produces a positive pulse (being clk2) through frequency divider 7, one the tunnel sends into gray scale counter 3 as count pulse, make densitometer numerical value increase progressively 1, another road is as the latch signal of chip for driving 8, with this comparison information totally 512 latch, and control the luminous situation of corresponding LED, be gray-scale value greater than 0 luminous, equal 0 not luminous.
In the present embodiment, serial input chip for driving is selected chip for driving TLC5921 for use, and XLAT is a latch signal among Fig. 2, and SI is the serial data input end, and SO is the serial data output terminal.Pixel count in the display unit is 512 points, and every pixel is made up of red, green, blue three color pixels, and every TLC5921 drives the LED of 16 colors of the same race, and the every look chip for driving of a display unit group needs 32 TLC5921, serially concatenateds as shown in the figure.
Each TV Field begins, positive pulse field sync signal (Vsync) to address counter 2, gray scale counter 3 and " greater than " comparer 4 zero clearing that resets.Move at string under the control of clock clk1, cell memory 10 begins to read view data from the address, red (R) data are sent into red gray-scale value comparator circuit, and green (G) data and Lan Se (B) data are sent into green gray-scale value comparator circuit and blue color shade value comparator circuit respectively.Below with the R data instance processing procedure is described, this is identical in the processing of G data and B data.
For chip for driving TLC5921, string moves the highest desirable 20MHz of clock clk1, and the corresponding cycle is 0.05us, selects the display unit of 512 pixels for use, and then the string cycle of moving equals 512 * 0.05us=25.6us.
From above analysis as can be known, gray-scale value is the view data of n, the pulse width of modulation output is that n string moves the cycle, since show with the TV Field to be unit, for the picture signal of 60Hz (16667us), the highest attainable number of greyscale levels N=16667us/25.6us=651 level, if it is 325 that number of greyscale levels is compressed half, then 1 TV Field can show 2 times, and promptly display frequency is 2 * 60=120Hz, is far longer than the critical flicker frequency of human eye.
The utility model gray-scale Control technology is introduced cell memory, cooperates cheap chip for driving TLC5921, has realized the gray-scale Control effect of expensive gray-scale Control chip for driving TLC5902.For 1920 * 1080 high definition virtual LEDs screen, adopt the TLC5902 scheme, need 97200 TLC5902 altogether.If adopt the utility model scheme, need 97200 TLC5921 and 2000 cell memory, suppose that TLC5902 is higher 20 yuan than TLC5921 price, employing the utility model scheme will save more than 190 ten thousand, much larger than 20,000 yuan of the 2000 blade unit cost of memory of adding, cost performance is high.
Present embodiment only for illustrating technical solutions of the utility model, should not be construed as restriction of the present utility model.The all modifications of being done based on the invention thinking adopts the TIP6B595 chip as chip for driving, and perhaps the pixel in the display unit is counted etc. for other, all should belong to protection domain of the present utility model.
Claims (4)
1. device of controlling the light emitting diode (LED) display screen gray scale is characterized in that: described device is made up of cell memory (1), address counter (2), gray scale counter (3), frequency divider (7), gray-scale value comparator circuit and serial input chip for driving group;
The view data that cell memory (1) is stored this unit, cell memory address increase progressively since 0, press the unit and show opposite sequential storage view data;
Address counter (2) moves the address bus signal of clock generating unit storer (1) according to string, and address counter (2) is a cycle counter, and when auto zero when 0 count down to M-1, M equals the display unit pixel count;
The gray-scale value comparator circuit comprises red gray-scale value comparator circuit, green gray-scale value comparator circuit and blue color shade value comparator circuit; Serial input chip for driving group comprises red chip for driving group, green chip for driving group and blue look chip for driving group, controls a kind of LED of color respectively, and the chip for driving in each group is by the serial mode cascade; Chip for driving group of all kinds is connected after its homochromy gray-scale value comparator circuit;
Gray-scale value comparator circuit structure of all kinds is identical, all by or door (6), null detector (5) and " greater than " comparer (4) forms; Null detector (5) detects whether the data gray-scale value read from cell memory (1) is ' 0 ', if then be output as ' 1 ', by or door (6) reset " greater than " comparer (4) makes it be output as ' 0 '; " greater than " comparer (4) finishes the data gray-scale value read from cell memory (1) and the comparison of gray scale Counter Value: if the data gray-scale value of reading from cell memory (1) is greater than the gray scale Counter Value, " greater than " comparer (4) is output as ' 1 '; If the data gray-scale value read from cell memory (1) is less than or equal to the gray scale Counter Value, then " greater than " comparer (4) is output as ' 0 '; Under string moves clock control, " greater than " the comparison information serial of comparer (4) output moves into homochromy chip for driving group;
Each TV Field begins, the positive pulse field sync signal to address counter (2), gray scale counter (3) and " greater than " comparer (4) zero clearing that resets; Move at string under the control of clock, cell memory (1) 0 begins to read view data from the address, red (R) data are sent into red gray-scale value comparator circuit, and green (G) data and Lan Se (B) data are sent into green gray-scale value comparator circuit and blue color shade value comparator circuit respectively;
The every string through M moved clock, string moves clock and produces a positive pulse through frequency divider (7), one the tunnel sends into gray scale counter (3) as count pulse, make densitometer numerical value increase progressively 1, another road is as the latch signal of chip for driving, this comparison information is latched the M position altogether, and control the luminous of corresponding LED.
2. the device of control light emitting diode (LED) display screen gray scale according to claim 1 is characterized in that: the used chip for driving of described serial input chip for driving group is TLC5921.
3. the device of control light emitting diode (LED) display screen gray scale according to claim 1 is characterized in that: the used chip for driving of described serial input chip for driving group is TIP6B595.
4. according to the device of claim 1 or 2 or 3 described control light emitting diode (LED) display screen gray scales, it is characterized in that: described M value is 32,64,128,256,512 or 1024.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200420084711 CN2745163Y (en) | 2004-08-05 | 2004-08-05 | Device for controlling gray scale of LED display screen |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200420084711 CN2745163Y (en) | 2004-08-05 | 2004-08-05 | Device for controlling gray scale of LED display screen |
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| CN 200420084711 Expired - Fee Related CN2745163Y (en) | 2004-08-05 | 2004-08-05 | Device for controlling gray scale of LED display screen |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105185312A (en) * | 2015-10-12 | 2015-12-23 | 利亚德光电股份有限公司 | LED driver, LED display screen including the same and method for driving LED driving chip |
| CN110599951A (en) * | 2019-10-17 | 2019-12-20 | 深圳市富满电子集团股份有限公司 | Image data output circuit, display circuit and method |
| CN113129808A (en) * | 2019-12-31 | 2021-07-16 | Tcl集团股份有限公司 | Driving method and driving device of LED array and display device |
-
2004
- 2004-08-05 CN CN 200420084711 patent/CN2745163Y/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105185312A (en) * | 2015-10-12 | 2015-12-23 | 利亚德光电股份有限公司 | LED driver, LED display screen including the same and method for driving LED driving chip |
| CN105185312B (en) * | 2015-10-12 | 2018-06-12 | 利亚德光电股份有限公司 | LED driver, including its LED display and LED drive chip driving method |
| CN110599951A (en) * | 2019-10-17 | 2019-12-20 | 深圳市富满电子集团股份有限公司 | Image data output circuit, display circuit and method |
| CN110599951B (en) * | 2019-10-17 | 2024-04-05 | 富满微电子集团股份有限公司 | Image data output circuit, display circuit and method |
| CN113129808A (en) * | 2019-12-31 | 2021-07-16 | Tcl集团股份有限公司 | Driving method and driving device of LED array and display device |
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Granted publication date: 20051207 Termination date: 20110805 |