CN1722213B - Gamma correction device and method for liquid crystal display - Google Patents
Gamma correction device and method for liquid crystal display Download PDFInfo
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Abstract
A gamma correction device for liquid crystal display comprises at least a reference voltage generation circuit and a gamma correction circuit. The reference voltage generating circuit is used for outputting a plurality of corresponding reference voltages according to the pixel data. The gamma correction circuit is used for carrying out gamma correction on the pixel data according to the reference voltage. The invention is characterized in that the reference voltage generating circuit outputs the corresponding reference voltage according to the position of the pixel corresponding to the pixel data on the liquid crystal screen and the color displayed by the pixel, so as to carry out gamma correction on the pixel data.
Description
The application divides an application for following patented claim: the applying date is on January 17th, 2002, and application number is 02102022.1, and denomination of invention is " gamma correcting device and the method that are used for LCD ".
Technical field
The present invention is relevant for a kind of digital analogue signal conversion equipment and method, particularly relevant for a kind of gamma (γ) that is used for LCD (Gamma) means for correcting and method.
Background technology
Because LCD (LCD) has the advantage of thin, the in light weight and low electromagnetic of volume, is widely used gradually in recent years.
Have a plurality of pixels (pixel) of arranging on the LCD screen with matrix form.Each pixel is made up of the liquid crystal layer between upper plate, lower plate and upper plate and the lower plate.A plurality of liquid crystal molecules are filled in the cavity between upper plate and the lower plate, form liquid crystal layer.And upper plate and lower plate have electrode respectively,, make when having institute's making alive between upper plate and lower plate in the electrode application voltage of upper plate and lower plate when respectively, and the arrangement mode of the liquid crystal molecule in the liquid crystal layer can change along with the alive size of institute.And the arrangement mode of liquid crystal molecule can influence the ratio of light penetration pixel, is referred to as light transmission (light transmissivity).The size of light transmission has determined the brightness of pixel.Light transmission is big more, and the brightness of pixel is just big more.So, can make pixels different on the LCD screen have different brightness by institute's making alive size of control upper plate and lower plate.
Please refer to Fig. 1, it illustrates the upper plate of pixel and the gamma curve graph of a relation of institute's making alive between lower plate and light transmission.Institute's making alive and light transmission between pixel upper plate and lower plate are not linear, and the relation of gamma curve as shown in Figure 1.So claim that the institute's making alive between pixel upper plate and lower plate is a gamma electric voltage.In addition, the light transmission of pixel is only relevant with the size of gamma electric voltage, and irrelevant with the polarity of gamma electric voltage.Therefore, gamma curve is by being the center with the ordinate, and the gamma curve 104 of symmetrical positive polarity gamma curve 102 and negative polarity is formed.If a certain pixel is imported two respectively size is identical but gamma electric voltage that polarity is different, then this pixel can have identical light transmission.If supply with the gamma electric voltage of the same polarity of each pixel constantly, can cause the damage of pixel liquid crystal molecule.Therefore, can protect liquid crystal molecule by the polarity of the gamma electric voltage that alternatively changes pixel.
The pixel data of general input LCD is the numerical data of binary format.Because the light transmission of gamma electric voltage and pixel is nonlinear gamma curve relation, therefore, LCD needs special circuit arrangement, be used for concerning according to gamma curve, convert the pixel data of digital format to output corresponding driving voltage to upper substrate or infrabasal plate, make the value of pixel data and the light transmission of pixel be the linear ratio relation.Operation mentioned above is called as gamma correction (gamma correction), is used to improve the image display quality of LCD screen.
Please refer to Fig. 2, it illustrates the synoptic diagram of gamma correction principle.When carrying out gamma correction, choose a plurality of pixel datas at first earlier as the reference pixel data.In Fig. 2, with pixel data D0, D1, D2, D3 and D4 as the reference pixel data.According to gamma curve, each reference pixel data can be distinguished a corresponding positive polarity reference voltage and a negative polarity reference voltage.With reference pixel data D0 is example, and it is a corresponding positive polarity reference voltage V0 and a negative polarity reference voltage V9 respectively.In like manner, 5 reference pixel data D0, D1, D2, D3 and D4 correspond to respectively 5 positive polarity reference voltage V0, V1, V2, V3, with V4 and 5 negative polarity reference voltage V9, V8, V7, V6 and V5, as shown in Figure 2.Described by preamble, general pixel data DATA is eight a binary data, can represent 256 gray levels altogether.When carrying out gamma correction, just the corresponding relation with reference pixel data and reference voltage is as the criterion, and utilizes interpolation method to try to achieve the corresponding respectively driving voltage of other all pixel datas.Wherein, each pixel data all can be distinguished a corresponding positive polarity driving voltage and a negative polarity driving voltage.
Be noted that selected reference pixel data number is many more, when carrying out gamma correction, the pairing driving voltage of each pixel data is just accurate more, generally chooses 8 reference pixel data and carries out gamma correction.According to gamma curve, 8 respectively corresponding eight positive polarity reference voltages of reference pixel data and 8 negative polarity reference voltages.The gamma correcting device of being responsible for the operation of execution gamma correction promptly is as the criterion with these 16 reference voltages and carries out gamma correction.
Please refer to Fig. 3, it illustrates the synoptic diagram of traditional gamma correcting device 300.Gamma correcting device 300 is coupled by gamma-correction circuit 302 and reference voltage generating circuit 304 and forms.Reference voltage generating circuit 304 has a resistance string that is in series by 17 resistance r1～r17.Two nodes of the head and the tail of this resistance string couple with voltage source 304 respectively.By the resistance value of suitably controlling each resistance, make each node of resistance string distinguish output reference voltage Vr, comprising 8 positive polarity reference voltage Vr (+) and 8 negative polarity reference voltage Vr (-).Each reference voltage Vr exports in the gamma-correction circuit 302 through impact damper BUF respectively.Gamma-correction circuit 302 is as the criterion with described reference voltage Vr, uses interpolation method that each pixel data DATA is carried out gamma correction respectively, exports corresponding driving voltage V
GM
Tradition reference voltage generating circuit 304 utilizes the principle of electric resistance partial pressure to export one group of reference voltage Vr to carry out gamma correction for gamma-correction circuit 302.For colour liquid crystal display device, the pixel on the screen shows redness, blueness and green respectively.Show the pixel of different colours, its gamma curve can't be identical.In addition, for large-sized LCD screen, because the difficulty of manufacture process improves, the upper plate of whole LCD screen and the interval between the lower plate (gap) distance can't be identical.The difference of upper plate and lower plate spacing distance can have influence on the gamma curve of pixel.Therefore, for large-sized LCD screen, the gamma curve of all pixels is not all identical.
In sum, the gamma curve of each pixel can be subjected to the influence at interval of color that this pixel shows and this pixel upper plate and lower plate respectively and variant on the LCD screen.Come all pixel datas are carried out gamma correction if only export one group of fixing reference voltage according to a fixing gamma curve, the shown picture color of then whole LCD screen can have error with desirable picture color.The phenomenon of this color drift (color shading) can make LCD can't present best image display quality.
Summary of the invention
Therefore, the purpose of this invention is to provide a kind of gamma correcting device and method, make the effect of gamma correction not be subjected to the shown color of pixel and upper plate and lower plate influence at interval, with the problem of solution LCD screen color drift, and the image display quality of raising LCD screen.
According to purpose of the present invention, a kind of gamma correcting device that is used for LCD is proposed, be used to receive a pixel data, and export a driving voltage to this LCD screen according to this pixel data, wherein, this LCD screen comprises a plurality of pixels, and this driving voltage is used for determining the brightness of this pixel of LCD screen.This gamma correcting device comprises a reference voltage generating circuit and a gamma-correction circuit at least.Wherein, reference voltage generating circuit is used for producing a plurality of reference voltages according to this pixel in the position of this LCD screen.Gamma-correction circuit is used for coming pixel data is carried out gamma correction according to described reference voltage, and produces this driving voltage to this LCD screen.Characteristics of the present invention are that reference voltage generating circuit exports corresponding reference voltage according to the pairing pixel of pixel data in the position and the shown color of this pixel of LCD screen, come pixel data is carried out gamma correction.
For above-mentioned purpose of the present invention, feature and advantage can be become apparent, a preferred embodiment cited below particularly, and cooperate appended accompanying drawing, be described in detail below.
Description of drawings
The institute's making alive of Fig. 1 remarked pixel upper plate and lower plate and the gamma curve graph of a relation of light transmission.
Fig. 2 represents the synoptic diagram of gamma correction principle
Fig. 3 represents the circuit block diagram of traditional gamma correcting device.
Fig. 4 represents the circuit block diagram of gamma correcting device proposed by the invention.
The circuit block diagram of the control element inside in Fig. 5 presentation graphs 4.
Fig. 6 A～6B represents the synoptic diagram that the sideline of adjacent screen block is carried out Fuzzy processing proposed by the invention.
Fig. 7 represents to carry out the circuit block diagram of the reference voltage output circuit of Fuzzy processing.
The synoptic diagram of its effect of low-pass filter of Fig. 8 presentation graphs 7.
Fig. 9 represents to illustrate the synoptic diagram of variable coding principle.
Figure 10 represents the synoptic diagram of another gamma correcting device proposed by the invention.
The drawing reference numeral explanation
102: the positive polarity gamma curve
104: the negative polarity gamma curve
300,400,1000: gamma correcting device
302,402,1002: gamma-correction circuit
304,404,1004: reference voltage generating circuit
306: voltage source
406,1006: memory element
408,1008: reference voltage output circuit
410,1010: control element
502: horizontal counter
504: vertical counter
506: controller
602,604,606,608: the screen block
702: low-pass filter
Embodiment
Characteristics of the present invention are whole LCD screen to be drawn be divided into a plurality of screen blocks.When carrying out gamma correction, according to the shown color of the pixel of each pixel data correspondence, and the screen block under this pixel, carry out gamma correction.
Conception of the present invention is whole LCD screen to be drawn be divided into a plurality of screen blocks, carries out gamma correction respectively.Present embodiment is 1024 * 768 (to be to have 768 pixel columns on the LCD screen with resolution, every row pixel column has 1024 display units, each display unit respectively has three pixels, show red, blue and green respectively) color liquid crystal screen be example, whole LCD screen drawn be divided into 16 * 12 totally 192 screen blocks.Compare with whole LCD screen, in each screen block, pixel upper plate and lower plate are more or less the same at interval, so the difference of the gamma curve of the pixel of same screen block is very little.If with each screen block is unit, carry out gamma correction respectively, then do not have because pixel upper plate and lower plate interval gap cause the problem of LCD screen color drift.
In addition, when pixel data is carried out gamma correction, the screen block under considering the pairing pixel of this pixel data, also to decide its corresponding driving voltage according to the color that this pixel shows.That is the pixel of each screen block all can be carried out gamma correction respectively according to its shown color.In other words, conception of the present invention is in the input different screen block, shows that the pixel data of the pixel of different colours carries out gamma correction respectively.Therefore, can solve because pixel shows the problem of the different LCD screen color drifts that color caused.
Please refer to Fig. 4, it illustrates the circuit block diagram of gamma correcting device proposed by the invention 400, gamma correcting device 400 is coupled by the living circuit 404 of gamma-correction circuit 402 and reference voltage and forms, wherein, reference voltage generating circuit 404 is made up of memory element 406, a plurality of reference voltage output circuit 408 and control element 410.The tradition reference voltage generating circuit utilizes the electric resistance partial pressure of resistance string to produce the reference voltage Vr that gamma correction is used.Way of the present invention shows the gamma curve relation of the pixel of different colours according in the different screen block, preestablishes different reference pixel data sets.Wherein, each reference pixel data set has a plurality of reference pixel data pdr.In the present embodiment, a reference pixel data set has 16 reference pixel data pdr.The reference pixel data pdr of all digital formats is stored in the memory element 406 with the form of corresponding tables (look-up-table).In the present embodiment, whole LCD screen is divided into 192 screen blocks altogether, and each screen block all needs three groups of reference pixel data to come pixel data pd is carried out gamma correction according to the color that pixel shows.So the memory element 406 of reference voltage generating circuit 404 needs to store 16 * 12 * 3, totally 576 groups of reference pixel data sets.Control element 410 can be known pixel that pixel data pd will control according to clock signal clk and horizontal-drive signal H-sync and belong to the color which screen block and this pixel show.Control element 410 is exported control signal ctrl respectively to memory element 406 and reference voltage output circuit 408 according to clock signal clk and horizontal-drive signal H-sync.Memory element 406 is according to this control signal ctrl, and the reference pixel data pdr that will be used for proofreading and correct the reference pixel data set of this pixel data pd exports corresponding reference voltage output circuit 408 respectively to.Reference voltage output circuit 408 is used for according to receiving corresponding reference pixel data pdr from the control signal ctrl that controls element 410 outputs.
In addition, reference voltage output circuit 408 has impact damper BUF and digital analog converter (DAC), is used for exporting corresponding reference voltage Vr to gamma-correction circuit 402 according to these reference pixel data pdr.With Fig. 4 is example, and reference voltage generating circuit 404 has 16 reference voltage output circuits 408 (1)～408 (16), is used for output reference voltage Vr respectively.Wherein, eight reference voltage generating circuit 408 (1)～408 (8) difference output cathode reference voltage Vr (+), and other eight reference voltage generating circuits, 408 (9)～408 (16) output negative pole reference voltage Vr (-).Gamma-correction circuit 402 is as the criterion with these reference voltages Vr, utilizes interpolation method, exports corresponding driving voltage V according to the pixel data pd of each input
GMIn sum, maximum characteristics of the present invention are the screen block under the pixel that reference voltage generating circuit 404 can be controlled according to pixel data pd, and the color that this pixel is used to show exports one group of reference voltage Vr, are used to carry out gamma correction.Therefore, can improve traditional gamma correcting device and only can carry out the shortcoming of gamma correction, and solve because the color difference that pixel shows with one group of reference voltage, and the problem of the LCD screen color drift that caused of the spacing distance difference of pixel upper plate lower plate.
Described by preamble, the present invention is divided into a plurality of screen blocks with whole LCD screen, carries out gamma correction with on the same group reference voltage Vr not respectively again.Therefore, have tangible sideline at each screen block and other screen block joints, and influence the image display quality of LCD screen.So when carrying out gamma correction, need carry out particular processing, with the sideline of each screen block of obfuscation and other screen block joints to the marginal portion of each screen block with gamma correcting device proposed by the invention and method.For convenience of description, this paper is called Fuzzy processing with aforesaid operations.Be noted that because pixel data pd is as the criterion with the position of pairing pixel on LCD screen, according to from left to right, order is from top to bottom imported in the gamma correcting device in regular turn.So when carrying out Fuzzy processing, to the vertical sideline of the adjacent screen block in the left and right sides and to the Fuzzy processing mode in the horizontal sideline of neighbouring screen block and inequality.
Please refer to Fig. 5, it illustrates the circuit block diagram of the control element inside among Fig. 4.Control element 410 comprises horizontal counter (H-counter) 502, vertical counter (V-counter) 504, couples with controller 506 respectively.When carrying out gamma correction, pixel data pd imports in the gamma-correction circuit in regular turn according to clock signal clk.Simultaneously, in clock signal clk difference input level counter 502 and the vertical counter 504, horizontal-drive signal H-sync then imports in the vertical counter 504.Horizontal counter 502 is exported horizontal count signal to controller 506 according to clock signal clk.Vertical counter 504 is exported vertical count signal to controller 506 according to clock signal clk and horizontal-drive signal H-sync respectively.Controller 506 is exported control signal ctrl respectively to memory element and reference voltage output circuit according to horizontal count signal and vertical count signal, be used for the control store element and export corresponding reference pixel data set, and the control reference voltage output circuit is according to corresponding reference pixel data pdr output reference voltage Vr.
Please refer to Fig. 6 A～6B, it illustrates the synoptic diagram that the sideline of adjacent screen block is carried out Fuzzy processing proposed by the invention.Below, be example with screen block 602 screen block 604 and the screen block 606 screen blocks 608 adjacent adjacent respectively, illustrate respectively the vertical sideline of the adjacent screen block in the left and right sides and principle and the operation of the horizontal sideline of neighbouring screen block being carried out Fuzzy processing with bottom with the right.
Please be simultaneously with reference to Fig. 5 and Fig. 6 A.Present embodiment is to be that 1024 * 768 color liquid crystal screen is drawn and is divided into 16 * 12 totally 192 screen blocks with resolution.So the resolution of each screen block is 64 * 64.In other words, when the pixel data pd that belongs to arbitrary row pixel in the screen block 602 is carried out gamma correction, whenever receive 64 clock signal clk in theory, controller 506 is promptly exported control signal ctrl to memory element, and the output of control store element is used for the reference pixel data set of next screen block 604 (i.e. the adjacent screen block 604 in the right).For convenience of explanation, twice output in definition controller 506 front and back ctrl signal received clock signal clk number during the memory element is a clock count.When carrying out Fuzzy processing, the clock count of controller 506 is not fixed as 64 near 64.In the present embodiment, the scope of clock count is 61～67.In other words, when the pixel data pd that belongs to a certain row pixel in the screen block 602 was carried out gamma correction, controller 506 might not 64 clock signal clk of every reception, but in 61～67 scopes arbitrarily selected numeral, for example: 62.When controller 506 received 62 clock signal clk, controller 506 was just exported control signal ctrl to memory element, and the output of control store element is used for the reference pixel data set of next screen block 604.Afterwards, in the time of carrying out gamma correction to the pixel data pd of the next column pixel that belongs to screen block 602, again in the arbitrarily selected numeral of 61～67 these scopes, for example: 67.When controller 506 receives 67 clock signal clk, just export control signal ctrl to memory element, the output of control store element is used for the reference pixel data set of next screen block 604.By that analogy.Be noted that the clock count that controller 506 is used for each row pixel of each screen block preestablishes, or via any number at random mode selected determine.Therefore, then screen block 602 is not to be a vertical straight line with border between 604, but the curve of complications, as shown in Figure 6A, and with the purpose in the sideline, the left and right sides that reaches obfuscation screen block.
Please be simultaneously with reference to Fig. 5 and Fig. 6 B.In the present embodiment, the resolution of each screen block is 64 * 64.In other words, when the pixel data pd that belongs to screen block 602 was carried out gamma correction, horizontal in theory counter 502 every countings 64 times were promptly finished the gamma correction operation to the pixel material pd of the 64 row pixels that belong to screen block 606 respectively.For convenience of explanation, the gamma correction operation to the pixel data pd that belongs to any screen block is finished in definition, and horizontal counter 502 required counts are the level counting.When carrying out Fuzzy processing, the level of horizontal counter 502 is counted near 64, is not fixed as 64.In the present embodiment, the scope of level counting is 61～67.When horizontal counter 502 count down to 61, that is gamma correcting device is when belonging to that each pixel data pd of the 61st row pixel carries out gamma correction in the screen block 606, the reference pixel data set gpdr that controller 506 can be selected the control store element still to export to be used for screen block 606, or output is used for the reference pixel data set gpdr ' of the screen block 608 following adjacent with screen block 606.Simultaneously, the probability of selecting output still to be used for the reference pixel data set gpdr of screen block 606 is used for the reference pixel data set gpdr ' of the adjacent screen block 608 of screen block 606 bottoms much larger than selection output.But along with the value of level counting is increasing, that is when each the pixel data pd that belongs in the screen block 606 the 62nd row or the 63rd row pixel carried out gamma correction, the probability of selecting still to export reference pixel data set gpdr with select output reference pixel data set gpdr ' probability size more and more approaching.When belonging to that each pixel data pd of the 64th row pixel carries out gamma correction in the screen block 606, the probability of selecting output reference pixel data set gpdr is identical with the probability of selecting to export reference pixel data set gpdr '.And work as belonging to the 65th row pixel of screen block 606, that is when each pixel data pd of the 1st row pixel of screen block 608 carried out gamma correction in theory, the probability of selecting output to be used for the reference pixel data set gpdr ' of screen block 608 began greater than selecting output to be used for the probability of the reference pixel data set gpdr of screen block 606.When leveler numerical value equals 66 or 67, in other words, to belonging to the 66th row or the 67th row pixel in the screen block 606, that is when each the pixel data pd that belongs in the screen block 608 the 2nd row or the 3rd row pixel carried out gamma correction, it is increasing to select output to be used for the probability of reference pixel data pdr ' of screen block 608, and it is more and more littler to select output to be used for the probability of reference pixel data pdr of screen block 606.When each pixel data pd of the 4th row pixel carries out gamma correction in to screen block 608, just all export the reference pixel data set gpdr ' that is used for screen block 608.By that analogy, be noted that when the pixel data pd corresponding to each row pixel carried out gamma correction, gamma correcting device preestablishes selected reference pixel data set gpdr or gpdr ', or selected at random by any number.No matter take which kind of mode, resulting result need meet selection reference pixel data set gpdr mentioned above or the probability distribution situation of gpdr '.Therefore, then the border between the screen block 606 and 608 is not to be the straight line of a level, but the curve of complications shown in Fig. 6 B, reaches the purpose of the last lower sideline of obfuscation screen block.
Except method mentioned above, the present invention also proposes another method, also can reach the purpose in the sideline, the left and right sides of obfuscation screen block.Please refer to Fig. 7, its expression can be carried out the circuit block diagram of the reference voltage output circuit of Fuzzy processing.Compare with Fig. 4, reference voltage output circuit 700 shown in Figure 7 also couples a low-pass filter (LPF) 702 after digital analog converter 704.When the reference voltage of digital analog converter 704 outputs changed, low-pass filter 702 was used to slow down its variation.Please refer to Fig. 8, the synoptic diagram of its effect of low-pass filter of its presentation graphs 7.Referring again to Fig. 6 A, when time t0, the gamma correction that the pixel data pd that belongs to screen block 602 is carried out finishes, and memory element can be exported another reference pixel data set, after being used for the pixel data pd that belongs to screen block 604 is carried out gamma correction.If the reference pixel data pdr that reference voltage output circuit 700 receives is with different before, then the reference voltage Vr of digital analog converter 704 outputs also has corresponding change.The reference voltage level of output is Vr1 before supposing, and after t0, the reference voltage Vr2 that corresponding reference pixel data pdr should export.If do not couple low-pass filter after the digital analog converter, then after time t0, at once just the reference voltage Vr of output reference voltage output circuit size becomes Vr2 by Vr1.But owing to couple low-pass filter 702 after the digital analog converter 704, as shown in Figure 7.Then owing to the effect of low-pass filter 702, the reference voltage of output reference voltage output circuit 700 can be changed lentamente by Vr1, just is promoted to Vr2 up to time t1.If so in regular turn the identical pixel data pd of several sizes is carried out gamma correction between time t0～t1, because the reference voltage Vr that is used for gamma correction is along with the time changes slowly, so corresponding driving voltage also increases slowly along with the time.And adjacent driving voltage difference each other is very little.When described driving voltage when the left side of entr screen block 604 is near the pixel of screen block 602 in regular turn, it is not obvious that the difference of each pixel intensity also can become.Therefore, also can reach the purpose in the sideline, the left and right sides of obfuscation screen block.
Present embodiment is to be that 1024 * 768 color liquid crystal screen is drawn and is divided into 16 * 12 totally 192 screen blocks with resolution, carries out gamma correction respectively.And in each screen block, it is also incomplete same to be used for when showing that redness, blueness and green pixel data pd do gamma correction needed reference pixel data set.So need 16 * 12 * 3 reference pixel data sets.When the gamma correcting device of present embodiment carried out gamma correction, each reference pixel data set respectively had 16 reference pixel data pdr, to produce the reference voltage Vr of 8 positive polaritys, 8 negative polarity.And each reference pixel data pdr is 6 a binary data.So if carry out the words of gamma correction with gamma correcting device 400 as shown in Figure 4, then memory element needs 16 * 12 (number of screen block) * 3 (color that pixel shows) * 16 (number of reference pixel data in each reference pixel data set) * 6 (positions) at least, approximate the storage space of 55.3 kilobits (kbit), just enough store needed all reference pixel data pdr of gamma correction method of present embodiment.
In order to reduce the needed memory span of memory element, in the present embodiment, reference pixel data pdr is stored in the memory element in the mode of variable coding (delta coding).Please refer to Fig. 9, its expression illustrates the synoptic diagram of variable coding principle.In Fig. 9, screen block N, N+1 and N+2 respectively have R, G, a B3 reference pixel data set, are used for showing that to being used for redness, green and blue pixels data pd carry out gamma correction respectively.For convenience, in Fig. 9, each reference pixel data set is only listed 8 positive polarity reference pixel data pdr.The design of variable coding storing method is that each reference pixel data pdr is and stores before that pdr is relevant with the corresponding reference pixel data of these reference pixel data pdr when storing reference pixel data pdr.The value of memory element physical holding of the stock is referred to as variable reference pixel data dpdr for this reference pixel data pdr and corresponding with it reference pixel data pdr ' differ.Therefore, then each reference pixel data pdr can be stored in the memory element with the data layout that is less than 6 variable reference pixel data dpdr, to reach the purpose of the storage space of saving memory element.With Fig. 9 is example, if in the R reference pixel data set of memory element with N screen block, the 8th reference pixel data (0) are as the criterion, then when the 7th adjacent reference pixel data (10) of memory element stores, stored variable reference pixel data dpdr value is the difference (10) of itself and the 8th reference pixel data (0).In like manner, the variable reference pixel data dpdr value of memory element stores the 6th reference pixel data (19) is poor (9) of adjacent the 7th reference pixel data (10).By that analogy, then in the R reference pixel data set of N screen block each reference pixel data pdr all can the method be stored in the memory element.Therefore, need just can store each reference pixel data pdr of R reference pixel data set with the form of 4 variable reference pixel data dpdr in the memory element.Afterwards, in the time will storing the G reference pixel data set of N screen block, the stored value of memory element is in the G reference pixel data set, each reference pixel data pdr, and in R reference pixel data set, the difference of corresponding with it reference pixel data pdr.For example: the value of the 2nd reference pixel data (49) of memory element stores G reference pixel data set is poor (1) of corresponding the 2nd reference pixel data (50) in itself and the R reference pixel data set.By that analogy.In like manner, when desire stored the reference pixel data pdr of B reference pixel data set of N screen block, the stored value of memory element was the poor of corresponding with it reference pixel data pdr in itself and the G reference pixel data set.Therefore, memory element only need just can store in the N screen block G and B reference pixel data set in the mode of 3 variable reference pixel data dpdr.Afterwards, when desire stored in the N+1 screen block each reference pixel data pdr, the stored value of memory element was the poor of corresponding with it reference pixel data pdr in itself and the N screen block.For example: when desire stores in the N+1 screen block, during the 1st reference pixel data (62) of R reference pixel data set, the stored value of memory element is poor (1) of the 1st reference pixel data (63) of corresponding with it R reference pixel data set in itself and the N screen block.By that analogy, according to the method, then memory element only need just can store all reference pixel data pdr of other screen blocks in the mode of 2 variable reference pixel data dpdr.In sum,, then do not need each reference pixel data pdr, can reach the purpose of saving storage space all with six data layout storage if memory element stores all reference pixel data pdr with variable coding storing method.
Referring again to Fig. 9, in each group reference pixel data set, the value of corresponding reference pixel data pdr, and each reference pixel data pdr and adjacent reference pixel data pdr's is poor, and its value is all quite approaching, and difference is also not quite.Please refer to Figure 10, it illustrates the synoptic diagram of another gamma correcting device proposed by the invention.In Figure 10, reference voltage generating circuit 1004 has a resistance string, and its two ends couple with reference voltage output circuit 1008 (1) and 1008 (2) respectively.Reference voltage output circuit 1008 (1) and 1008 (2) is maximum and minimum positive polarity reference voltage Vr (+) according to reference pixel data pdr output.Remaining reference voltage Vr (+) then utilizes the principle of electric resistance partial pressure, and in this resistance string, the node that each resistance and other resistance couple comes and exports remaining reference voltage Vr (+) to gamma-correction circuit 1002.In like manner, the reference voltage Vr (-) of negative polarity can also the method produce, and repeats no more in this.Therefore, the reference pixel data set that then is stored in the memory element 1006 only need store two reference voltage pdr for every group, can save the required storage space of memory element.Simultaneously, can too much influence not arranged to the effect of gamma correction yet.Be noted that, the present invention is not limited to only utilize two reference voltage generating circuits 1008 (1) and 1008 (2), can weigh the degree of accuracy of reference voltage Vr and both requirements of degree of saving the storage space of memory element, the reference voltage generating circuit 1008 of proper number is set, comes according to reference pixel data pdr output reference voltage Vr.Remaining reference voltage Vr then can utilize the principle of electric resistance partial pressure, by the node output of the resistance string that couples.And memory element 1006 also can cooperate and utilize previously described variable coding storing method to store required reference pixel data pdr, also can reach the demand of saving the required storage space of memory element.
Disclosed a kind of gamma correcting device of the above embodiment of the present invention and method, wherein, reference voltage generating circuit is exported corresponding reference voltage according to the pairing pixel of pixel data in the position and the shown color of this pixel of LCD screen, comes pixel data is carried out gamma correction.Therefore, can make the effect of gamma correction not be subjected to the influence of the upper plate and the lower plate spacing distance of shown color of pixel and pixel, solving the problem of LCD screen color drift, and improve the image display quality of LCD screen.
In sum; though the present invention with a preferred embodiment openly as above; so it is not to be used to limit the present invention; any technician in the art; under the situation that does not break away from design of the present invention and scope; can carry out various also moving and modifications, so protection scope of the present invention should be with being as the criterion that accompanying Claim was limited.
Claims (3)
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200510082064 CN1722213B (en) | 2002-01-17 | 2002-01-17 | Gamma correction device and method for liquid crystal display |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200510082064 CN1722213B (en) | 2002-01-17 | 2002-01-17 | Gamma correction device and method for liquid crystal display |
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| CN 02102022 Division CN1243337C (en) | 2002-01-17 | 2002-01-17 | Gamma correction device and method for liquid crystal display |
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| CN1722213A CN1722213A (en) | 2006-01-18 |
| CN1722213B true CN1722213B (en) | 2011-12-07 |
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| CN 200510082064 Expired - Fee Related CN1722213B (en) | 2002-01-17 | 2002-01-17 | Gamma correction device and method for liquid crystal display |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR101250787B1 (en) * | 2006-06-30 | 2013-04-08 | 엘지디스플레이 주식회사 | Liquid crystal display device having gamma voltage generator of register type in data driver integrated circuit |
| US10796634B2 (en) | 2018-07-30 | 2020-10-06 | Shenzhen China Star Optoelectronics Semiconductor Display Technology Co. , Ltd. | Display control circuit, method and panel display device |
| CN109147686B (en) * | 2018-07-30 | 2020-05-19 | 深圳市华星光电半导体显示技术有限公司 | Display control circuit and method and flat panel display device |
| CN111862889B (en) * | 2019-04-28 | 2022-12-16 | 京东方科技集团股份有限公司 | Display device, driving device and driving method thereof |
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