CN102142230A - LED (Light Emitting Diode) scanning screen blanking method, device and LED scanning screen - Google Patents
LED (Light Emitting Diode) scanning screen blanking method, device and LED scanning screen Download PDFInfo
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- CN102142230A CN102142230A CN2011100796686A CN201110079668A CN102142230A CN 102142230 A CN102142230 A CN 102142230A CN 2011100796686 A CN2011100796686 A CN 2011100796686A CN 201110079668 A CN201110079668 A CN 201110079668A CN 102142230 A CN102142230 A CN 102142230A
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Abstract
The invention relates to an LED (Light Emitting Diode) scanning screen blanking method, a device and an LED scanning screen. The method comprises the following steps: detecting a data latch signal for leading the LED screen to drive the data transmission; and discharging parasitic capacitance of each LED when a high-level signal of the data latch signal is detected. In the invention, when the high-level signal of the data latch signal is detected, the parasitic capacitance of each LED is discharged through detecting the data latch signal for leading the LED screen to drive the data transmission; when an output enable signal is at high level, all PMOS (Channel Metal Oxide Semiconductors) are cut off according to the time sequence of an LED screen module data interface; when a data latch signal LE is at high level, the signal enable signal also is at high level so as to ensure that when the parasitic capacitance is discharged under the situation that the data latch signal LE is at the high level, all PMOS are cut off to realize the effect that the parasitic capacitance is discharged under the situation that all the PMOS tubes are cut off, therefore, the conditions of generating the darkness and the brightness are damaged, and the dark and bright phenomena are eliminated.
Description
Technical field
The present invention relates to a kind of LED scan screen blanking method, device and a kind of LED scan screen.
Background technology
As shown in Figure 1, be the principle schematic of LED scan screen, its basic implementation is the switch by a plurality of PMOS pipes of quick control, a shared constant current source chip, reaches the purpose of saving cost.Existing LED scan screen exists when exporting oblique line on the LED screen and can see obviously that there is the phenomenon of faint shade in oblique line in actual applications, influences output effect.The reason that causes this phenomenon occurring has a lot, and wherein chief reason is that LED has certain stray capacitance, and stray capacitance forms weak current by the LED discharge and causes LED secretly bright.When constant current source is closed, the conducting of control PMOS pipe, though can not light LED, but can charge to stray capacitance, be filled with in stray capacitance under the situation of certain electricity, the conducting of control PMOS pipe ends, and starts constant current source and sucks electric current, then stray capacitance forms weak current and causes LED secretly bright by the discharge of LED forward.
In technology early, the refreshing frequency of LED screen is not high, and in order to solve above-mentioned dark bright problem, the LED screen controller is after turning off PMOS pipe and constant current source, reserve one period blanking time (being called the horizontal blanking interval), wait for that LED stray capacitance leakage discharge finishes.The increase horizontal blanking interval can be alleviated dark bright problem to a certain extent, but can not tackle the problem at its root, and can reduce the refreshing frequency of screen, growing along with technology, demand to refreshing frequency improves day by day, and the measure that increases the horizontal blanking interval is more infeasible.
Therefore, in order to eliminate the dark bright problem of LED scan screen, the method that present LED screen manufacturing industry generally adopts is: the positive pole at each LED connects a resistance to ground, to accelerate the discharge of stray capacitance, as shown in Figure 2, show the LED scanning theory figure that increases discharge resistance.According to this mode, can effectively eliminate secretly bright, but still have numerous shortcomings: at first,, can cause unnecessary energy consumption to increase as long as the conducting of PMOS pipe just necessarily has current flowing resistance; Secondly, when LED of appearance is reversed puncture among several LED of a current source of parallel connection connection, the effect of discharge resistance is equivalent on constant current source resistance in parallel on earth, the schematic equivalent circuit when reverse breakdown occurring has been shown, at this moment among Fig. 3, every other LED can form current return by this resistance, even if close constant current source, also can there be electric current to flow through LED, at this moment, relevant LED will be out of control, is embodied in LED screen Chang Liang.
Summary of the invention
At above-mentioned problems of the prior art, the object of the present invention is to provide a kind of LED scan screen blanking method, a kind of LED scan screen blanker and a kind of LED scan screen, it can be implemented under the situation that all PMOS pipes end the stray capacitance rapid discharge, destroy producing dark bright condition, eliminate dark bright phenomenon.
For achieving the above object, the present invention by the following technical solutions:
A kind of LED scan screen blanking method comprises step:
Detect the data latch signal of LED screen driving data transmission, when detecting the high level signal of data latch signal, to the parasitic capacitance discharge of each LED.
A kind of LED scan screen blanker, comprise: more than one controlled discharge circuit, each described controlled discharge circuit interconnects PMOS be connected corresponding with diode of pipe with one group respectively, the control end of each described controlled discharge circuit joins with the drain electrode of corresponding PMOS pipe, the positive pole of diode respectively, the source termination of each described controlled discharge circuit is gone into the data latch signal of LED screen driving data transmission, and each described controlled discharge circuit discharges when receiving the high level signal of described data latch signal.
A kind of LED scan screen, comprise constant current source, two groups of above interconnective PMOS manage and diode, the drain electrode of each described PMOS pipe connects with the positive pole of corresponding diode, the source electrode of each described PMOS pipe is connected with power supply, the negative pole of each described diode is connected with described constant current source, the other end ground connection of described constant current source, also comprise: more than one controlled discharge circuit, each described controlled discharge circuit is managed be connected corresponding with diode with one group of interconnective PMOS respectively, the control end of each described controlled discharge circuit respectively with the drain electrode of corresponding PMOS pipe, the positive pole of diode joins, the source termination of each described controlled discharge circuit is gone into the data latch signal of LED screen driving data transmission, and each described controlled discharge circuit discharges when receiving the high level signal of described data latch signal.
According to the invention described above scheme, its cardinal principle is by detecting the data latch signal of LED screen driving data transmission, when detecting the high level signal of data latch signal, stray capacitance to each diode is discharged, because according to the sequential of LED screen module data-interface, when the output enable signal
During for high level, all PMOS end, and when data latch signal LE is high level, the output enable signal
It also is high level, thereby guaranteed that at data latch signal LE be under the situation of high level during to parasitic capacitance discharge, all PMOS pipes end, and can be implemented under the situation that all PMOS pipes end the stray capacitance rapid discharge, destroy producing dark bright condition, eliminate dark bright phenomenon.
Description of drawings
Fig. 1 is the principle schematic of LED scan screen;
Fig. 2 is the LED scanning theory figure that increases discharge resistance;
Fig. 3 is the schematic equivalent circuit when reverse breakdown occurring;
Fig. 4 is the schematic flow sheet of LED scan screen blanking method embodiment of the present invention;
Fig. 5 is the sequential synoptic diagram of LED screen module data-interface;
Fig. 6 is the structural representation of LED scan screen blanker embodiment one of the present invention;
Fig. 7 is the structural representation of LED scan screen blanker embodiment two of the present invention.
Embodiment
Below be that example is described in detail the present invention program with the preferred embodiment.
As shown in Figure 4, be the schematic flow sheet of LED scan screen blanking method embodiment of the present invention, it comprises step:
Step S101: detect the data latch signal of LED screen driving data transmission, enter step S102;
Step S102: when detecting the high level signal of data latch signal, to the parasitic capacitance discharge of each diode.
According to the invention described above scheme, it is by detecting the data latch signal of LED screen driving data transmission, when detecting the high level signal of data latch signal, the stray capacitance of each diode being discharged.Use the inventive method, can be implemented under the situation that all PMOS pipes end, below describe at this point the stray capacitance rapid discharge.
The data-interface of LED screen module includes: serial data (SDI), clock (CLK), data latching (LE), output enable
As shown in Figure 5, be the sequential synoptic diagram of the data-interface of LED screen module.As seen from Figure 5, when the output enable signal
During for high level, all PMOS end, and when data latch signal LE is high level, the output enable signal
It also is high level, thereby guaranteed that at data latch signal LE be under the situation of high level during to parasitic capacitance discharge, all PMOS pipes end, thereby can be implemented under the situation that all PMOS pipes end the stray capacitance rapid discharge, destroy producing dark bright condition, eliminate dark bright phenomenon.
As shown in Figure 6, be the structural representation of LED scan screen blanker embodiment one of the present invention.
Referring to shown in Figure 1, existing LED scan screen in the prior art, be to include the above interconnective PMOS pipe of constant current source, two groups and diode (in the present invention program's description, the PMOS pipe that connects one to one is called one group with diode), the drain electrode of each PMOS pipe connects with the positive pole of corresponding diode, the grid Access Control switching signal of each PMOS pipe, and the source electrode of each PMOS pipe is connected with power supply, the negative pole of each diode all is connected with constant current source, the other end ground connection of constant current source.
LED scan screen blanker of the present invention shown in Figure 6, include a plurality of controlled discharge circuit, the number of controlled discharge circuit is identical with the number of PMOS pipe or diode, promptly for any one group of interconnective PMOS pipe and diode, all be correspondingly provided with a controlled discharge circuit, for any one controlled discharge circuit, all with one group of interconnective PMOS is connected corresponding of pipe with diode, during connection, the source end of controlled discharge circuit (the S end shown in Fig. 6) inserts the data latch signal (LE signal) of LED screen driving data transmission, the drain electrode of the control end of controlled discharge circuit and corresponding PMOS pipe, the positive pole of diode joins, and the controlled discharge circuit discharges when receiving the high level signal of data latch signal.
The specific implementation of controlled discharge circuit can be with of the prior art identical, does not repeat them here.
With identical in the LED Screen Blanking method of the invention described above, sequential synoptic diagram referring to the data-interface of the LED screen module shown in Fig. 5, can learn, can be implemented under the situation that all PMOS pipes end the stray capacitance rapid discharge according to the present invention program, destroy producing dark bright condition, eliminate dark bright phenomenon.
According to the LED Screen Blanking device of the invention described above, not only can effectively eliminate dark bright phenomenon, and discharge process is to carry out under the situation that the PMOS pipe ends, can not influence normal screen display.With the exception of this, can also reach following beneficial effect simultaneously:
At first, can not start always, only when data latch signal LE is high level, just enable, can not cause significant energy consumption to increase yet, save energy consumption owing to put dot circuit;
Secondly, it is to utilize existing control signal (data latch signal LE) control of discharging, and the data signal interfaces of LED screen need not change, the LED screen control system need not produce special-purpose discharge control signal, all effective to all existing control system, convenient convenient, upgrading is convenient.
In the example shown in Fig. 6, be for any one group of interconnective PMOS pipe and diode, all being correspondingly provided with a controlled discharge circuit describes, according to actual needs, also each controlled discharge circuit can be integrated on the chip piece, further to reduce the cost of controlled discharge circuit, reduce the shared volume of controlled discharge circuit.
As shown in Figure 7, it is the structural representation of LED Screen Blanking device embodiment two of the present invention, in this embodiment, be all to be integrated in the integrated chip with each controlled discharge circuit to describe, and be to be that chip 74HC245 describes in shown in Figure 7 with this integrated chip.
For chip 74HC245, referring to shown in Figure 7, its 19th pin
Be Enable Pin, if input signal is " 1 ", the then not conducting of signal of A/B end is only when input signal is " 0 ", A/B just is activated, and plays the effect of switch, and according to the present invention, be to discharge during for high level at data latch signal, therefore, at the 19th pin of chip 74HC245
A not gate can be inserted in the outside of Enable Pin, makes that at data latch signal LE be at 1 o'clock, the 19th pin of chip 74HC245
Enable Pin be input as 0, make the conducting of A/B end, enable, discharge.
In addition, for chip 74HC245, referring to shown in Figure 7, its the 1st pin DIR is the input/output port transformation, signal is held output by the input of A end, B when DIR=" 1 " is high level, and signal was held output by the input of B end, A when DIR=" 0 " was low level, in the connected mode as shown in Figure 7, A holds equal ground connection, is the B end is connected with the drain electrode of PMOS pipe, the positive pole of diode.In addition, in the connected mode shown in Figure 7, the 1st pin DIR of chip 74HC245 joins by resistance and power supply.
According to the invention described above scheme, the present invention also provides a kind of LED display, it includes constant current source, two groups of above interconnective PMOS manage and diode, the drain electrode of each PMOS pipe connects with the positive pole of corresponding diode, the grid Access Control switching signal of each PMOS pipe, the source electrode of each PMOS pipe is connected with power supply, the negative pole of each diode all is connected with constant current source, the other end ground connection of constant current source, also comprise aforesaid LED display blanker, identical among each embodiment of the specific implementation of LED display blanker and the invention described above do not repeat them here.
Above-described embodiment of the present invention only is the detailed description to preferred embodiment of the present invention, does not constitute the qualification to protection domain of the present invention.Any modification of being done within the spirit and principles in the present invention, be equal to and replace and improvement etc., all should be included within the claim protection domain of the present invention.
Claims (9)
1. a LED scan screen blanking method is characterized in that, comprises step:
Detect the data latch signal of LED screen driving data transmission, when detecting the high level signal of data latch signal, to the parasitic capacitance discharge of each LED.
2. LED scan screen blanking method according to claim 1 is characterized in that, adopts the controlled discharge circuit to described parasitic capacitance discharge.
3. LED scan screen blanking method according to claim 2 is characterized in that, described controlled discharge circuit adopts chip 74HC245 to realize that described data latch signal inserts the Enable Pin of described chip 74HC245 by not gate.
4. LED scan screen blanker, it is characterized in that, comprise: more than one controlled discharge circuit, each described controlled discharge circuit interconnects PMOS be connected corresponding with diode of pipe with one group respectively, the control end of each described controlled discharge circuit joins with the drain electrode of corresponding PMOS pipe, the positive pole of diode respectively, the source termination of each described controlled discharge circuit is gone into the data latch signal of LED screen driving data transmission, and each described controlled discharge circuit discharges when receiving the high level signal of described data latch signal.
5. LED scan screen blanker according to claim 4 is characterized in that, each described controlled discharge circuit all is integrated among the chip 74HC245, and described data latch signal inserts the Enable Pin of described chip 74HC245 by not gate.
6. LED scan screen blanker according to claim 5 is characterized in that the input/output terminal of described chip 74HC245 joins by resistance and power supply.
7. LED scan screen, comprise constant current source, two groups of above interconnective PMOS manage and diode, the drain electrode of each described PMOS pipe connects with the positive pole of corresponding diode, the source electrode of each described PMOS pipe is connected with power supply, the negative pole of each described diode is connected with described constant current source, the other end ground connection of described constant current source, it is characterized in that, also comprise: more than one controlled discharge circuit, each described controlled discharge circuit is managed be connected corresponding with diode with one group of interconnective PMOS respectively, the control end of each described controlled discharge circuit respectively with the drain electrode of corresponding PMOS pipe, the positive pole of diode joins, the source termination of each described controlled discharge circuit is gone into the data latch signal of LED screen driving data transmission, and each described controlled discharge circuit discharges when receiving the high level signal of described data latch signal.
8. LED scan screen according to claim 7 is characterized in that, each described controlled discharge circuit all is integrated among the chip 74HC245 realizes that described data latch signal inserts the Enable Pin of described chip 74HC245 by not gate.
9. LED scan screen according to claim 8 is characterized in that the input/output terminal of described chip 74HC245 joins by resistance and power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011100796686A CN102142230B (en) | 2011-03-31 | 2011-03-31 | LED (Light Emitting Diode) scanning screen blanking method, device and LED scanning screen |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2011100796686A CN102142230B (en) | 2011-03-31 | 2011-03-31 | LED (Light Emitting Diode) scanning screen blanking method, device and LED scanning screen |
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| CN102142230A true CN102142230A (en) | 2011-08-03 |
| CN102142230B CN102142230B (en) | 2012-11-21 |
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| CN102592542A (en) * | 2012-02-27 | 2012-07-18 | 深圳市明微电子股份有限公司 | Blanking control circuit for LED (light-emitting diode) display screens and LED drive chip |
| CN103258499A (en) * | 2012-02-15 | 2013-08-21 | 广州硅芯电子科技有限公司 | Circuit for removing ghost image in display panel having light emitter |
| CN104992675A (en) * | 2015-07-30 | 2015-10-21 | 西安诺瓦电子科技有限公司 | Led lamp panel |
| CN107947569A (en) * | 2017-12-20 | 2018-04-20 | 深圳市明微电子股份有限公司 | One kind disappears shadow voltage control system and method |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103258499A (en) * | 2012-02-15 | 2013-08-21 | 广州硅芯电子科技有限公司 | Circuit for removing ghost image in display panel having light emitter |
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| CN102592542B (en) * | 2012-02-27 | 2015-03-18 | 深圳市明微电子股份有限公司 | Blanking control circuit for LED (light-emitting diode) display screens and LED drive chip |
| CN104992675A (en) * | 2015-07-30 | 2015-10-21 | 西安诺瓦电子科技有限公司 | Led lamp panel |
| CN107947569A (en) * | 2017-12-20 | 2018-04-20 | 深圳市明微电子股份有限公司 | One kind disappears shadow voltage control system and method |
| CN107947569B (en) * | 2017-12-20 | 2024-02-06 | 深圳市明微电子股份有限公司 | Shadow eliminating voltage control system and method |
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| CN102142230B (en) | 2012-11-21 |
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