CN104485073A - Brightness adjustment method and system for LED display screens - Google Patents
Brightness adjustment method and system for LED display screens Download PDFInfo
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Abstract
The invention relates to a brightness adjustment method and system for LED display screens. The method comprises the following steps: determining current corresponding to each point through the brightness of each point, determining benchmark reference current corresponding to each point through the current corresponding to each point, and therefore adjusting the brightness of the LED display screen according to the benchmark reference current corresponding to each point. The current output peak value of a constant-current drive circuit is adjustable, and the adjustment benchmark value is set by an external resistor and is not limited by the external resistor. The overall brightness adjustment overall brightness tends to the selected standard brightness conforming to the requirement of the display screen, and the overall brightness overall brightness cannot be reduced. The method does not need to independently reply on current pulse width adjustment, and the gray-scale sacrifice is reduced, that is, under the conditions of sacrificing less gray scales and preventing display brightness reduction, the adjustment for the brightness consistency of the LED display screen is realized.
Description
Technical field
The present invention relates to LED display technical field, particularly relate to a kind of LED display brightness adjusting method, a kind of LED display brightness control system.
Background technology
Current full-color LED (Light-Emitting Diode, light emitting diode) display screen adopts special constant current drive IC (integrated circuit, integrated circuit) display.Under existing LED manufacturing process, the luminosity of each LED component is often inconsistent, and the brightness of display screen so assembled is also inconsistent.Existing LED display gamma correction mode is the luminosity by regulating electric current pulsewidth to regulate LED component, makes the brightness of LED display reach consistent.But there are following two deficiencies in the correcting mode of this adjustment electric current pulsewidth:
The first, be confined to outer meeting resistance and be PCB (Printed Circuit Board, printed circuit board) time fixes, peak point current originally can not increase again, and so the overall brightness of display screen regulates and trends towards, to minimum brightness snap, namely reducing overall brightness;
The second, in a driving circuit, realize GTG display be GCLK (gray-scale Control clock) effect under counting.GCLK is fixing in a scan pattern, i.e. a fixing frequency, and so will sweep a complete GTG display is n GCLK.Such as, as shown in Figure 1, t=0.6Ts realizes a complete GTG (256 grades) display.Due to the demand of brightness uniformity, the brightness of certain LED is needed to reduce, and adopt the method for pulse-width regulated brightness to be reduce current duty cycle, so current duty cycle is less than 0.6Ts and can realizes brightness requirement, t now can not meet the time span requirement of 256 grades of GTG scannings, needs compression.Namely the method for this pulse-width regulated brightness can sacrifice certain GTG effect, especially when electric current pulse-width regulated amplitude is larger time.
Summary of the invention
Based on this, being necessary for the problems referred to above, a kind of LED display brightness adjusting method and system are provided, making the adjustment obtaining good brightness uniformity when sacrificing lower GTG.
A kind of LED display brightness control system, comprise connected constant-current drive circuit, data acquisition and processing (DAP) circuit, wherein said constant-current drive circuit comprises connected reference current generating circuit, reference current generating circuit;
Reference current generating circuit generates reference current according to the outer meeting resistance of constant-current drive circuit, and reference current is input to reference current generating circuit; Reference current is generated each reference electric current by current mirroring circuit by reference current generating circuit;
Data acquisition and processing (DAP) circuit gathers the brightness value of LED display each point, the brightness value meeting display screen display and require is chosen from each brightness value, and using the mean value of one of them brightness value chosen or the brightness value chosen as Benchmark brightness value, wherein said Benchmark brightness value is corresponding with reference current; Determine the brightness value of each point and the luminance difference of Benchmark brightness value, obtain the electric current of each point and the current differential of reference current according to each luminance difference, the electric current corresponding according to each current differential determination each point; The reference electric current with the difference of each electric current within the scope of certain predetermined is chosen from each reference electric current, and using the reference electric current chosen as drive current corresponding to each point;
Drive current corresponding for each point is input to LED display by constant-current drive circuit.
A kind of LED display brightness adjusting method, comprises step:
According to the outer meeting resistance setting reference current of constant-current drive circuit, reference current is produced each reference electric current by current mirroring circuit;
Gather the brightness value of LED display each point, the brightness value meeting display screen display and require is chosen from each brightness value, and using the mean value of one of them brightness value chosen or the brightness value chosen as Benchmark brightness value, described Benchmark brightness value is corresponding with reference current;
Determine the brightness value of each point and the luminance difference of Benchmark brightness value, obtain the electric current of each point and the current differential of reference current according to each luminance difference, the electric current corresponding according to each current differential determination each point;
The reference electric current with the difference of each electric current within the scope of certain predetermined is chosen from each reference electric current, and using the reference electric current chosen as drive current corresponding to each point;
Drive current corresponding for each point is input to LED display.
LED display brightness adjusting method of the present invention and system, by the electric current that the brightness determination each point of each point is corresponding, the reference electric current corresponding according to the electric current determination each point that each point is corresponding, thus according to the reference electric current that each point is corresponding, brightness regulation is carried out to LED display.Namely the electric current of constant-current drive circuit exports peak value is adjustable, its adjustment reference value is set by outer meeting resistance, unrestricted in outer meeting resistance, the overall brightness of display screen regulates and trends towards meeting display screen required standard brightness snap to what choose, can not reduce the brightness that display screen is overall; First by regulating current peak to regulate LED display brightness, and then by regulating electric current pulsewidth to finely tune LED display brightness, do not need independent dependence electric current pulse-width regulated, and the adjustment of pulsewidth can be reduced largely, so decrease the sacrifice of GTG, that is to say when sacrificing less GTG and avoiding display brightness to reduce, achieve the adjustment of LED display brightness uniformity.
Accompanying drawing explanation
Fig. 1 is pulsewidth schematic diagram in prior art;
Fig. 2 is the structural representation of present system embodiment;
Fig. 3 is the circuit diagram of reference current generating circuit of the present invention and reference current generating circuit specific embodiment;
Fig. 4 is the circuit diagram of reinforcing band loading capability circuit embodiments of the present invention;
Fig. 5 is the structural representation of the analog module embodiment of constant-current drive circuit of the present invention;
Fig. 6 is the schematic diagram of switch arrays circuit specific embodiment of the present invention;
Fig. 7 is the circuit diagram of output-stage circuit specific embodiment of the present invention;
Fig. 8 is the structural representation of the digital module embodiment of constant-current drive circuit of the present invention;
Fig. 9 is the schematic flow sheet of the inventive method embodiment.
Embodiment
In order to understand the technical problem to be solved in the present invention, the technical scheme taked and the technique effect reached more clearly, introduce in detail below in conjunction with the embodiment of accompanying drawing to LED display brightness control system of the present invention.It should be noted that, first, second word such as grade in literary composition, just to distinguishing the device of identical type in different circuit, is not limited the order and number etc. of device.
As shown in Figure 1, a kind of LED display brightness control system, comprise connected constant-current drive circuit 200, data acquisition and processing (DAP) circuit 100, wherein said constant-current drive circuit 200 comprises connected reference current generating circuit 210, reference current generating circuit 220;
Reference current generating circuit 210 generates reference current according to the outer meeting resistance of constant-current drive circuit, and reference current is input to reference current generating circuit 220; Reference current is generated each reference electric current by current mirroring circuit by reference current generating circuit 220;
Data acquisition and processing (DAP) circuit 100 gathers the brightness value of LED display each point, the brightness value meeting display screen display and require is chosen from each brightness value, and using the mean value of one of them brightness value chosen or the brightness value chosen as Benchmark brightness value, wherein said Benchmark brightness value is corresponding with reference current; Determine the brightness value of each point and the luminance difference of Benchmark brightness value, obtain the electric current of each point and the current differential of reference current according to each luminance difference, the electric current corresponding according to each current differential determination each point; The reference electric current with the difference of each electric current within the scope of certain predetermined is chosen from each reference electric current, and using the reference electric current chosen as drive current corresponding to each point;
Drive current corresponding for each point is input to LED display by constant-current drive circuit 200.
Data acquisition and processing (DAP) circuit 100 chooses the brightness value meeting display screen requirement from each brightness value, when there being multiple brightness value to meet display screen requirement, a brightness value can be chosen arbitrarily as Benchmark brightness value from the brightness value meeting display screen requirement, also can using the mean value of brightness value chosen as Benchmark brightness value etc., what Benchmark brightness value was corresponding is the reference current that outer meeting resistance is determined, then successively by brightness value a little and Benchmark brightness value compare, analyze the difference of brightness value a little and Benchmark brightness value, according to the relation of drive current and brightness, the difference of the brightness value of each point and Benchmark brightness value is converted to the current value of each point and the difference of reference current, wherein after display panel type is determined, the relation of drive current and brightness is existing known.After the difference of the current value and reference current that obtain each point, namely data acquisition and processing (DAP) circuit 100 can determine the current value of each point, then chooses corresponding reference electric current according to the current value of each point.Such as, reference electric current be 0.80*iref, 0.85*iref, 0.90*iref ..., iref is reference current, supposes that preset range is for [0-0.025*iref], the current value corresponding when certain point is 0.85*iref, then the reference electric current of this some correspondence is 0.85*iref; When the electric current that certain point is corresponding is 0.81*iref, the reference electric current of this some correspondence is 0.80*iref; When the electric current that certain point is corresponding is 0.825*iref, the reference current of this some correspondence can be 0.80*iref or 0.85*iref.
Due to the adjustment of the present invention mainly by regulating the current peak of constant-current drive circuit to realize brightness of display screen, so in order to ensure that current peak is adjustable, additionally provide reference current generating circuit 210 and reference current generating circuit 220.In order to more clearly understand the implementation of reference current generating circuit 210 and reference current generating circuit 220, the instantiation below in conjunction with the accurate reference current generative circuit of 9 roadbed shown in Fig. 3 is described.
As shown in Figure 3, reference current generating circuit 210 can comprise the first field effect transistor m1, the second field effect transistor m2, the second amplifier op_2, outer meeting resistance R_EXT;
The source electrode of the first field effect transistor m1 is connected with VDD (device inside operating voltage), and grid is connected with reference current generating circuit 220, and drain electrode is connected with the drain electrode of the second field effect transistor m2, and grid is connected with drain electrode; The grid of the second field effect transistor m2 is connected with the output terminal of the second amplifier op_2; The positive input terminal of the second amplifier op_2 inputs the first internal reference voltage; Outer meeting resistance R_EXT one end ground connection, the other end is connected with the negative input end of the second amplifier op_2, the source electrode of the second field effect transistor m2 respectively.
Reference current generating circuit 210 is by external precision resister R_EXT, and be applied to the internal reference voltage vref of amplifier op_2 positive input terminal, produce the accurate current i ref of a roadbed, such as vref is the reference current iref=1.2/R_EXT of 1.2V (volt), generation.
The road reference current input reference reference current generative circuit 220 that reference current generating circuit 210 produces, reference generative circuit 220 generates the accurate reference current of each roadbed by each current mirroring circuit.Reference current generating circuit 220 can reference electric current as required determine need current mirroring circuit number.The mode that current mirroring circuit realizes has a variety of, and such as, as shown in Figure 3, reference current generating circuit 220 comprises each current mirroring circuit, and each current mirroring circuit can have identical circuit structure.For the first current mirror branch road shown in Fig. 3, current mirroring circuit can comprise the 3rd field effect transistor m3, the 4th field effect transistor m4, the 5th field effect transistor m5, the 3rd amplifier op_3 and four high guaily unit op_4;
The source electrode of the 3rd field effect transistor m3 is connected with VDD, and grid is connected with the grid of the first field effect transistor m1, and drain electrode is connected with the negative input end of the 3rd amplifier op_3, the source electrode of the 4th field effect transistor m4 respectively; The positive input terminal of the 3rd amplifier op_3 is connected with the grid of the first field effect transistor m1, and output terminal is connected with the grid of the 4th field effect transistor m4; The drain electrode of the 4th field effect transistor m4 is connected with the positive input terminal of four high guaily unit op_4, the drain electrode of the 5th field effect transistor m5 respectively; 5th field effect transistor m5 grid is connected with the output terminal of four high guaily unit op_4, source ground; The negative input end of four high guaily unit op_4 inputs the second internal reference voltage, output terminal output reference voltage, wherein the second internal reference voltage is different from the first internal reference voltage numerical value, and such as the first internal reference voltage is 1.2v, and the second internal reference voltage is 0.9v.
Each current mirroring circuit structure is identical, and the breadth length ratio of the field effect transistor comprised is different, thus the reference electric current generated and reference current proportional.Reference current generating circuit such as shown in Fig. 3, has the current mirroring circuit that 9 structures are identical, and the breadth length ratio of m3, m6, m9, m12, m15, m18, m21, m23, m27 pipe is different.The ratio of their breadth length ratio and the breadth length ratio of m1 is respectively: 0.80,0.85,0.90,0.95,1.00,1.05,1.10,1.15,1.20, reference electric current according to the corresponding generation of the principle of current mirror is respectively: 0.80*iref, 0.85*iref, 0.90*iref, 0.95*iref, 1.00*iref, 1.05*iref, 1.10*iref, 1.15*iref and 1.2*iref, wherein iref represents reference current.Amplifier op_3, op_5, op_7, op_9, op_11, op_13, op_15, op_17, op_19 serve the grid and drain voltage effect that regulate the field effect transistor such as m3, m6, m9, m12, m15, m18, m21, m23, m27.For the first current mirror branch road, op_3 is by regulating the gate voltage of m4, make the grid of m3 equal with drain voltage, and then ensure that this current mirror branch road accurately copying reference current, namely ensure that accurate 0.80 times of reference current copies on this branch road, ensure that follow-up current stabilization and high precision.
Each current mirroring circuit gives corresponding reference voltage, and such as, as shown in Figure 3, the reference voltage terminal that 9 road current mirror branch roads provide is v_0.80, v_0.85, v_0.90, v_0.95, v_1.00, v_1.05, v_1.10, v_1.15 and v_1.20.Because the equivalent capacity of follow-up output stage pipe is comparatively large, so need the load capacity increasing each current mirroring circuit signal.Reference current generating circuit 220 can also comprise each reinforcing band loading capability circuit, and each reinforcing band loading capability circuit comprises the first amplifier respectively; The positive input terminal of the first amplifier is connected with corresponding reference voltage terminal, and negative input end is connected with output terminal, and output terminal exports the reference voltage after strengthening.Such as reference voltage terminal is as shown in Figure 4 the branch road of v_0.80, comprise amplifier op_1, op_1 input reference voltage v_0.80, the reference voltage exported after strengthening is v_0.80c, be similar to the circuit structure shown in Fig. 4,9 reference voltages, through corresponding reinforcing band loading capability circuit, strengthen respectively as v_0.80_c, v_0.85_c, v_0.90_c, v_0.95_c, v_1.00_c, v_1.05_c, v_1.10_c, v_1.15_c and v_1.20_c.
After obtaining reference electric current corresponding to each point, constant-current drive circuit 200 needs the reference electric current of each point to be outputted to LED display, to realize the adjustment to each point brightness.So present system can also comprise the access card be connected between data acquisition and processing (DAP) circuit 100 and constant-current drive circuit 200.As shown in Figure 5, described constant-current drive circuit 200 can also comprise switching signal gating circuit 230, constant current output circuit 250, the switch arrays circuit 240 be connected with switching signal gating circuit 230 output terminal, reference current generating circuit 220 output terminal, constant current output circuit 250 input end respectively.
Data acquisition and processing (DAP) circuit 100 is by drive current corresponding for each point stored in access card, and when constant-current drive circuit initialization, access card is by drive current write switch signal gating circuit 230 corresponding for each point of storage;
The drive current that switching signal gating circuit 230 is corresponding according to the row surface sweeping signal acquisition respective point of input, and be input to switch arrays circuit 240;
The drive current that switch arrays circuit 240 is corresponding according to the respective point of input, carries out gating to each reference electric current, and is input to the corresponding output-stage circuit of constant current output circuit 250;
Corresponding reference electric current is input to LED display and puts accordingly and carry out brightness regulation by each output-stage circuit.
Reference information corresponding for each point, mainly in order to store reference current information corresponding to each point, when constant-current drive circuit 200 initialization, being input to switching signal gating circuit 230, thus carrying out the output of electric current by access card.Constant-current drive circuit 200 comprises analog module, the function of analog module be realize reference current generation to constant current output, comprise the reference current generating circuit 210 shown in Fig. 5, reference current generating circuit 220, switching signal gating circuit 230, switch arrays circuit 240, constant current output circuit 250.Exporting the process of each point drive current in order to understand constant-current drive circuit 220 more clearly, being described in detail below in conjunction with the specific implementation of accompanying drawing to switching signal gating circuit 230, switch arrays circuit 240, constant current output circuit 250.
As shown in Figure 5, the input signal of switching signal gating circuit 230 is line scan signals A, B, C, D, E and synchronous control signal T, and output signal is the control signal of switch arrays circuit.Switching signal gating circuit 230 can adopt 16 scannings, also can adopt 32 scannings etc.When employing 16 is swept, what suppose that reference current generating circuit 220 generates is the accurate reference current of 9 roadbed, what then switching signal gating circuit 230 exported is the permutation signal of a 16*9, the switch arrays of corresponding 16*9 respectively, namely 16 switches are divided into, each switch is 9, other scanning number and reference electric current number similar.
The scanning of circuit carries out line by line, can obtain from the state of A, B, C, D and E.Sweep and the accurate reference current of 9 roadbed for 16, in time scanning 16 LED component of the first row, this drive current required for 16 LED that switching signal gating circuit 230 just obtains the first row, also i.e. this reference electric current required for 16 LED, and then exporting the control signal of these 16 LED, the control signal wherein exported is the permutation signal of 16*9.When having scanned the first row, when entering scanning the second row, sweep circuit is had an appointment blanking time of 1 ~ 10us (microsecond), and switching signal gating circuit 230 obtains the current information of the second row LED, by that analogy, until a scan period complete.
Switch arrays circuit 240 mainly carries out gating according to the control signal of input to reference current signal.In order to understand the principle of work of switch arrays circuit 240 more clearly, the switch arrays circuit arranged below in conjunction with 16 row 9 is described, it should be noted that, the switch arrays circuit of this 16 row 9 row does not make restriction to the line number of switch arrays circuit 240 of the present invention and columns, and the line number of concrete switch arrays circuit 240 and columns are determined according to the way of reference electric current and switching signal gating circuit 230.
As shown in Figure 6, be the switch arrays circuit that 16 row 9 arrange, the signal of the accurate reference current of 9 roadbed receives 9 row of switch arrays circuit respectively, and every a line of switch arrays circuit receives the benchmark input end of an output-stage circuit.The switch of every a line only allows a conducting, ensure that an output-stage circuit receives only a reference current signal.Such as, the first output-stage circuit needs the iref benchmark of 1 times, and so the benchmark input end of this output-stage circuit receives v_1.00_c, and namely the switch k15 switch of the first row closes, and other 8 switches disconnect, by that analogy.
Constant current output circuit 250 comprises multiple output-stage circuit, and such as will realize 16 channel currents and export, then comprise 16 road output-stage circuits, the circuit structure of each output-stage circuit can be identical.As shown in Figure 7, each output-stage circuit can comprise each switch, the 5th amplifier op_21, analog switch t1, not gate inv, the 6th field effect transistor m30, double diffused field effect pipe m32, the 7th field effect transistor m31 respectively;
Each reference voltage after enhancing is respectively through the grid of corresponding switch to the 7th field effect transistor m31, the positive input terminal of the 5th amplifier op_21; 7th field effect transistor m31 drain electrode is connected with the negative input end of the 5th amplifier op_21, the source electrode of double diffused field effect pipe m32 respectively, source ground; Analog switch t1 is connected with the output terminal of the 5th amplifier op_21, control signal input end ch1, the grid of double diffused field effect pipe m32, the grid of the 6th field effect transistor m30 respectively; Not gate inv input end is connected with control signal input end ch1, and output terminal is connected with the grid of the 6th field effect transistor m30; The drain electrode of the 6th field effect transistor m30 is connected with the grid of double diffused field effect pipe m32, source ground; The drain electrode of double diffused field effect pipe m32 is connected by LED and VDD.
Export and the accurate reference current of 9 roadbeds for 16 passages, the benchmark input reference voltage of output-stage circuit is ov01, ov02, ov03, ov04, ov05, ov06, ov07, ov08, ov09, ov10, ov11, ov12, ov13, ov14, ov15, ov16, reference voltage v_0.80_c, v_0.85_c, v_0.90_c, v_0.95_c, v_1.00_c, v_1.05_c, v_1.10_c, v_1.15_c and v_1.20_c after so strengthening, through the reference edge of 9 switches to output-stage circuit, form selection circuit.Carried out the benchmark gating of single output-stage circuit by 9 switches, these 9 switches have and only have a conducting, this ensure that the gate voltage of the 7th field effect transistor m31 only has a signal to come in.Switch kij is connected to the 7th field effect transistor m31 and prime forms current mirror, and different switch is connected to different reference electric currents.And the 7th field effect transistor m31 and double diffused field effect pipe m32 forms cascode structure constant current source, wherein double diffused field effect pipe m32 adopts DMOS (Double-diffused Metal-Oxid-Semiconductor) pipe, larger voltage can be born, 7th field effect transistor m31 realizes the amplification of reference electric current, realizes steady current and exports.In order to ensure that the 7th field effect transistor m31 can accurately copy, will ensure that the leakage of the 7th field effect transistor m31 is consistent with gate voltage, so adopt amplifier op_21 to carry out process to the leakage of the 7th field effect transistor m31 and gate voltage to export and control double diffused field effect pipe m32, make double diffused field effect pipe m32 adjustment electric current reach the leakage of the 7th field effect transistor m31 effect consistent with gate voltage.And the control of amplifier op_21 to double diffused field effect pipe m32 gate voltage is by an analog switch t1, this analog switch t1 is controlled by the signal of control signal input end ch1, field effect transistor m30 realizes releasing the effect of electric charge when the signal of control signal input end ch1 makes double diffused field effect pipe m32 close, and shortens the time of closing constant current output.
Such as, output-stage circuit reference signal selects v_0.80_c, so the field effect transistor of the 7th field effect transistor m31 and previous stage forms current mirroring circuit, time ch1 is high level, the Drazin inverse double diffused field effect pipe m32 of amplifier op_21, regulates the drain-source voltage of the 7th field effect transistor m31 equal with gate source voltage, makes the electric current exact mirror image of constant current output and prime field effect transistor, reach the object of accurate constant current, also like this time output-stage circuit reference signal selects other signals.
Described constant-current drive circuit 200 not only comprises mimic channel, also comprises digital circuit, digital circuit mainly realize gradation data input, latch, change, compare, then export the signal controlling output-stage circuit output switch.As shown in Figure 8, digital circuit can comprise shift register, impact damper, isochronous controller, counter, each comparer, each Sheffer stroke gate, wherein SIN is display gray scale data input pin, data output end time SOUT is driving circuit cascade, DCLK is data input control clock, LAT is the latch signal of data input, GCLK is gray-scale Control clock, OE signal is the switch that the overall situation controls the output of multiple output-stage circuit, turn off time OE signal is high level and export, can normally export time OE is low level.
Under DCLK effect, shift register input display gray scale data, when the display gray scale data inputted reach maximum storage threshold value, LAT provides high level, enters in impact damper by display gray scale data buffer storage; Display gray scale data are input to the input end of corresponding comparer by impact damper respectively; Under the synchronizing signal effect of isochronous controller, counter starts the cycle calculating GCLK, and the number of cycles of output is input to another input end of each comparer respectively; Each comparer compares display gray scale data and the number of cycles of its input, and Output rusults is inputted an input end of corresponding Sheffer stroke gate, OE control signal inputs another input end of each Sheffer stroke gate by not gate, and the output signal of each Sheffer stroke gate is for controlling the output switch of corresponding output-stage circuit.
In order to more clearly understand the workflow of digital module, be now described in conjunction with an instantiation.Under the effect of DCLK, the gradation data of SIN is moved in the shift register of 16*8 position, when gradation data in the shift register of 16*8 position reaches 128, LAT provides high level, is entered in buffer by the gradation data buffer memory of the shift register of 16*8 position.The gradation data of 8 is input to the input end of 16 8 bit comparators by buffer, and now 16 8 bit comparators export as low level.Under the synchronizing signal effect of isochronous controller, 8 digit counters start to calculate GCLK number of cycles from 0, and the GCLK number of cycles of calculating is input to respectively another input end of 16 8 bit comparators, the now output of 16 8 bit comparators becomes high level, and Output rusults is inputted respectively corresponding two input nand gates.Another input ends of 16 two input nand gates receives the signal that OE switch is sent by not gate, exports the control signal to the output switch of corresponding output-stage circuit according to the result of computing.
Based on same inventive concept, the present invention also provides a kind of LED display brightness adjusting method, is described in detail below in conjunction with the embodiment of accompanying drawing to the inventive method.
As shown in Figure 9, a kind of LED display brightness adjusting method, comprises step:
S910, according to the outer meeting resistance of constant-current drive circuit setting reference current, reference current is produced each reference electric current by current mirroring circuit;
The brightness value of S920, collection LED display each point, the brightness value meeting display screen display and require is chosen from each brightness value, and using the mean value of one of them brightness value chosen or the brightness value chosen as Benchmark brightness value, described Benchmark brightness value is corresponding with reference current;
The luminance difference of S930, the brightness value determining each point and Benchmark brightness value, obtains the electric current of each point and the current differential of reference current according to each luminance difference, the electric current corresponding according to each current differential determination each point;
S940, from each reference electric current, choose reference electric current with the difference of each electric current within the scope of certain predetermined, and using the reference electric current chosen as drive current corresponding to each point;
S950, drive current corresponding for each point is input to LED display.
The brightness value meeting display screen requirement is chosen from each brightness value, when there being multiple brightness value to meet display screen requirement, a brightness value can be chosen arbitrarily as Benchmark brightness value from the brightness value meeting display screen requirement, also can using the mean value of brightness value chosen as Benchmark brightness value etc., what Benchmark brightness value was corresponding is the reference current that outer meeting resistance is determined, then successively by brightness value a little and Benchmark brightness value compare, analyze the difference of brightness value a little and Benchmark brightness value, according to the relation of drive current and brightness, the difference of the brightness value of each point and Benchmark brightness value is converted to the current value of each point and the difference of reference current, wherein after display panel type is determined, the relation of drive current and brightness is existing known.After the difference of the current value and reference current that obtain each point, namely the current value of each point can be determined, then corresponding reference electric current is chosen according to the current value of each point, wherein reference electric current can comprise 0.80*iref, 0.85*iref, 0.90*iref, 0.95*iref, 1.00*iref, 1.05*iref, 1.10*iref, 1.15*iref and 1.2*iref etc., and iref represents reference current.When choosing reference electric current corresponding to each point, whether can determine within the scope of certain predetermined according to the difference of the current value of each point and reference electric current.Such as, reference electric current be 0.80*iref, 0.85*iref, 0.90*iref ..., suppose that preset range is for [0-0.025*iref], when current value corresponding to certain point is 0.85*iref, then the reference electric current of this some correspondence is 0.85*iref; When the electric current that certain point is corresponding is 0.81*iref, the reference electric current of this some correspondence is 0.80*iref; When the electric current that certain point is corresponding is 0.825*iref, the reference current of this some correspondence can be 0.80*iref or 0.85*iref.
The inventive method obtains the step of reference current and each reference electric current, and specifically drive current corresponding for each point is input to the step that LED display carries out brightness regulation, identical with said system, does not repeat them here.
The above embodiment only have expressed several embodiment of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.
Claims (10)
1. a LED display brightness control system, is characterized in that, comprises connected constant-current drive circuit, data acquisition and processing (DAP) circuit, and wherein said constant-current drive circuit comprises connected reference current generating circuit, reference current generating circuit;
Reference current generating circuit generates reference current according to the outer meeting resistance of constant-current drive circuit, and reference current is input to reference current generating circuit; Reference current is generated each reference electric current by current mirroring circuit by reference current generating circuit;
Data acquisition and processing (DAP) circuit gathers the brightness value of LED display each point, the brightness value meeting display screen display and require is chosen from each brightness value, and using the mean value of one of them brightness value chosen or the brightness value chosen as Benchmark brightness value, wherein said Benchmark brightness value is corresponding with reference current; Determine the brightness value of each point and the luminance difference of Benchmark brightness value, obtain the electric current of each point and the current differential of reference current according to each luminance difference, the electric current corresponding according to each current differential determination each point; The reference electric current with the difference of each electric current within the scope of certain predetermined is chosen from each reference electric current, and using the reference electric current chosen as drive current corresponding to each point;
Drive current corresponding for each point is input to LED display by constant-current drive circuit.
2. LED display brightness control system according to claim 1, is characterized in that, reference current generating circuit comprises the first field effect transistor, the second field effect transistor, the second amplifier, outer meeting resistance;
The source electrode of the first field effect transistor is connected with VDD, and grid is connected with reference current generating circuit, and drain electrode is connected with the drain electrode of the second field effect transistor, and grid is connected with drain electrode; The grid of the second field effect transistor is connected with the output terminal of the second amplifier; The positive input terminal of the second amplifier inputs the first internal reference voltage; Outer meeting resistance one end ground connection, the other end is connected with the negative input end of the second amplifier, the source electrode of the second field effect transistor respectively.
3. LED display brightness control system according to claim 2, it is characterized in that, reference current generating circuit comprises each current mirroring circuit, and each current mirroring circuit comprises the 3rd field effect transistor, the 4th field effect transistor, the 5th field effect transistor, the 3rd amplifier and four high guaily unit respectively;
The source electrode of the 3rd field effect transistor is connected with VDD, and grid is connected with the grid of the first field effect transistor, and drain electrode is connected with the negative input end of the 3rd amplifier, the source electrode of the 4th field effect transistor respectively; The positive input terminal of the 3rd amplifier is connected with the grid of the first field effect transistor, and output terminal is connected with the grid of the 4th field effect transistor; The drain electrode of the 4th field effect transistor is connected with the positive input terminal of four high guaily unit, the drain electrode of the 5th field effect transistor respectively; 5th fet gate is connected with the output terminal of four high guaily unit, source ground; The negative input end of four high guaily unit inputs the second internal reference voltage, output terminal output reference voltage.
4. LED display brightness control system according to claim 3, is characterized in that, reference current generating circuit also comprises each reinforcing band loading capability circuit, and each reinforcing band loading capability circuit comprises the first amplifier respectively; The positive input terminal of the first amplifier is connected with corresponding reference voltage terminal, and negative input end is connected with output terminal, and output terminal exports the reference voltage after strengthening.
5. LED display brightness control system according to claim 4, it is characterized in that, also comprise the access card be connected between data acquisition and processing (DAP) circuit and constant-current drive circuit, described constant-current drive circuit also comprises switching signal gating circuit, constant current output circuit, the switch arrays circuit be connected with switching signal gating circuit output terminal, reference current generating circuit output terminal, constant current output circuit input end respectively;
Data acquisition and processing (DAP) circuit is by drive current corresponding for each point stored in access card, and when constant-current drive circuit initialization, access card is by drive current write switch signal gating circuit corresponding for each point of storage;
The drive current that switching signal gating circuit is corresponding according to the row surface sweeping signal acquisition respective point of input, and be input to switch arrays circuit;
The drive current that switch arrays circuit is corresponding according to the respective point of input, carries out gating to each reference electric current, and is input to the corresponding output-stage circuit of constant current output circuit;
Corresponding reference electric current is input to LED display and puts accordingly and carry out brightness regulation by each output-stage circuit.
6. LED display brightness control system according to claim 5, is characterized in that, each output-stage circuit comprises each switch, the 5th amplifier, analog switch, not gate, the 6th field effect transistor, double diffused field effect pipe, the 7th field effect transistor respectively;
Each reference voltage after enhancing is respectively through the grid of corresponding switch to the 7th field effect transistor, the positive input terminal of the 5th amplifier; 7th field effect transistor drain electrode is connected with the negative input end of the 5th amplifier, the source electrode of double diffused field effect pipe respectively, source ground; Analog switch is connected with the output terminal of the 5th amplifier, control signal input end, the grid of double diffused field effect pipe, the grid of the 6th field effect transistor respectively; Not gate input end is connected with control signal input end, and output terminal is connected with the grid of the 6th field effect transistor; The drain electrode of the 6th field effect transistor is connected with the grid of double diffused field effect pipe, source ground; The drain electrode of double diffused field effect pipe is connected by LED and VDD.
7. LED display brightness control system according to claim 5, is characterized in that, described constant-current drive circuit also comprises digital circuit, and digital circuit comprises shift register, impact damper, isochronous controller, counter, each comparer, each Sheffer stroke gate;
Under DCLK effect, shift register input display gray scale data, when the display gray scale data inputted reach maximum storage threshold value, LAT provides high level, enters in impact damper by display gray scale data buffer storage; Display gray scale data are input to the input end of corresponding comparer by impact damper respectively; Under the synchronizing signal effect of isochronous controller, counter starts the cycle calculating GCLK, and the number of cycles of output is input to another input end of each comparer respectively; Each comparer compares display gray scale data and the number of cycles of its input, and Output rusults is inputted an input end of corresponding Sheffer stroke gate, OE control signal inputs another input end of each Sheffer stroke gate by not gate, and the output signal of each Sheffer stroke gate is for controlling the output switch of corresponding output-stage circuit.
8. the LED display brightness control system according to claim 1 to 7 any one, it is characterized in that, each reference electric current comprises 0.80*iref, 0.85*iref, 0.90*iref, 0.95*iref, 1.00*iref, 1.05*iref, 1.10*iref, 1.15*iref and 1.2*iref, and wherein iref represents reference current.
9. a LED display brightness adjusting method, is characterized in that, comprises step:
According to the outer meeting resistance setting reference current of constant-current drive circuit, reference current is produced each reference electric current by current mirroring circuit;
Gather the brightness value of LED display each point, the brightness value meeting display screen display and require is chosen from each brightness value, and using the mean value of one of them brightness value chosen or the brightness value chosen as Benchmark brightness value, described Benchmark brightness value is corresponding with reference current;
Determine the brightness value of each point and the luminance difference of Benchmark brightness value, obtain the electric current of each point and the current differential of reference current according to each luminance difference, the electric current corresponding according to each current differential determination each point;
The reference electric current with the difference of each electric current within the scope of certain predetermined is chosen from each reference electric current, and using the reference electric current chosen as drive current corresponding to each point;
Drive current corresponding for each point is input to LED display.
10. LED display brightness adjusting method according to claim 9, it is characterized in that, each reference electric current comprises 0.80*iref, 0.85*iref, 0.90*iref, 0.95*iref, 1.00*iref, 1.05*iref, 1.10*iref, 1.15*iref and 1.2*iref, and wherein iref represents reference current.
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Address after: Kezhu road high tech Industrial Development Zone, Guangzhou city of Guangdong Province, No. 233 510670 Patentee after: Wei Chong group Limited by Share Ltd Address before: 510670 Guangdong city of Guangzhou province Kezhu Guangzhou high tech Industrial Development Zone, Road No. 233 Patentee before: Guangdong Weichuangshixun Science and Technology Co., Ltd. |