Patent Application
20130241967
1. Technical Field
The present invention relates to a technology for suppressing the occurrence of disclination.
2. Related Art
In a liquid crystal panel, there sometimes occurs a phenomenon, which is called disclination, in which, because of electric-potential between adjacent pixels, there occurs lateral electric field extending in a direction in which adjacent pixel electrodes are arranged, thereby causing liquid crystal molecules to align in a direction different from a desired alignment direction. The occurrence of disclination causes the degradation of a quality of display regarding the liquid crystal panel, and thus, as disclosed in, for example, JP-A-2009-25417, JP-A-2009-104053, JP-A-2009-104055, JP-A-2009-237366 and JP-A-2009-237524, various inventions for suppressing the occurrence of disclination have been made.
Naturally, a correction which is made on display data for one of or both of adjacent pixels between which the lateral electric field strengthens so as to reduces an applied-voltage difference between the adjacent pixels makes it possible to weaken the lateral electric field, thereby, enabling suppression of the occurrence of declination. However, a correction which is made on a certain pixel so as to reduce an electric-field difference with a pixel adjacent to one side of the certain pixel causes an electric-potential difference with another pixel adjacent to the other side of the certain pixel to increase, so that the situation of the occurrence of disclination sometimes becomes worse.
An advantage of some aspects of the invention is to provide a signal processing apparatus and the like which enables realization of a correction which results in a situation where a post-correction electric-potential difference between any two adjacent pixels is not larger than a pre-correction electric-potential difference therebetween.
According to an aspect of the invention, a signal processing apparatus that is used for a liquid crystal apparatus provided with a plurality of pixels, and that processes a signal for controlling gray-scale for display of each of the plurality of pixels, includes a first detection unit configured to, in the case where a first pixel is arranged between a second pixel and a third pixel, the first pixel, the second pixel and the third pixel being pixels among the plurality of pixels, detect a difference between a first gray-scale value corresponding to the first pixel and a second gray-scale value corresponding to the second pixel as a first gray-scale difference; a second detection unit configured to detect a difference between the first gray-scale value corresponding to the first pixel and a third gray-scale value corresponding to the third pixel as a second gray-scale difference; a comparison unit configured to compare the first gray-scale difference and the second gray-scale difference; and a correction unit configured to make correction of at least two of the first gray-scale value, the second gray-scale value and the third gray-scale value such that the first gray-scale difference is reduced to a third gray-scale difference smaller than the first gray-scale difference and the second gray-scale difference is reduced to a fourth gray-scale difference smaller than the second gray-scale difference, and if the first gray-scale difference is larger than the second gray-scale difference, the correction unit makes the correction such that the third gray-scale difference is larger than the fourth gray-scale difference.
According to this configuration, a post-correction gray-scale difference between any two adjacent pixels is smaller than a pre-correction gray-scale difference therebetween, so that it is possible to make a post-correction electric-potential difference between any two adjacent pixels not larger than a pre-correction electric-potential difference therebetween.
In the aspect of the invention, the comparison unit further performs comparison to determine whether or not each of the first gray-scale difference and the second gray-scale difference is larger than or equal to a threshold value, and the correction unit makes the correction if each of the first gray-scale difference and the second gray-scale difference is larger than or equal to the threshold value.
According to this configuration, the correction is made so as to make a gray-scale difference of any two adjacent pixels smaller than that as of before the correction, and thus, the occurrence of boundaries after the correction can be suppressed.
Further, in the aspect of the invention, in the case where there exists a boundary between the first pixel and the third pixel, the correction unit may be configured to correct input display data for the third pixel.
According to this configuration, in the case where a certain pixel may become a high gray-scale side pixel or a low gray-scale side pixel relative to one of both pixels adjacent to the certain pixel, gray-scale values of the respective both pixels adjacent to the certain pixel are corrected, so that it is possible to suppress shifting of any boundary from its position as of before the correction to its position as of after the correction.
In the aspect of the invention, the comparison unit further compares the first gray-scale value, the second gray-scale value and the third gray-scale value, and the correction unit makes the correction if the first gray-scale value>the second gray-scale value>the third gray scale value, or the first gray-scale value<the second gray-scale value<the third gray scale value.
According to this configuration, for a certain pixel which may become a high gray-scale side pixel or a low gray-scale side pixel relative to one of both pixels adjacent to the certain pixel, the above-described correction of gray-scale values of pixels are made, so that it is possible to suppress shifting of any boundary from its position as of before the correction to its position as of after the correction.
Further, in the aspect of the invention, the correction unit may be configured to make the correction on the basis of the second gray-scale difference.
According to this configuration, it is possible to make a post-correction gray-scale difference between any two adjacent pixels not larger than a pre-correction gray-scale difference therebetween, so that it is possible to suppress shifting of any boundary from its position as of before the correction to its position as of after the correction.
According to another aspect of the invention, a signal processing apparatus that is used for a liquid crystal apparatus provided with a plurality of pixels, and that processes a signal for controlling gray-scale for display of each of the plurality of pixels, includes a first detection unit configured to, in the case where a first pixel is arranged between a second pixel and a third pixel, the first pixel, the second pixel and the third pixel being pixels among the plurality of pixels, if a first difference between a first gray-scale value corresponding to the first pixel and a second gray-scale value corresponding to the second pixel is larger than or equal to a threshold value, detect the first difference as a first gray-scale difference; a second detection unit configured to, if a second difference between the first gray-scale value corresponding to the first pixel and a third gray-scale value corresponding to the third pixel is larger than or equal to the threshold value, detect the second difference as a second gray-scale difference; a comparison unit configured to compare the first gray-scale difference and the second gray-scale difference; and a correction unit configured to make correction of at least two of the first gray-scale value, the second gray-scale value and the third gray-scale value such that the first gray-scale difference is reduced to a third gray-scale difference smaller than the first gray-scale difference and the second gray-scale difference is reduced to a fourth gray-scale difference smaller than the second gray-scale difference, and, if the first gray-scale difference is larger than the second gray-scale difference, the correction unit makes the correction such that the third gray-scale difference is larger than the fourth gray-scale difference.
In addition, according to another aspect of the invention, it is possible to conceive a liquid crystal apparatus, an electronics device and signal processing method, besides the signal processing apparatus.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
The timing control circuit 10 controls individual portions of the electro-optic apparatus 1 by generating various control signals in synchronization with a synchronization signal Sync which is supplied from an external apparatus (not illustrated).
The image processing circuit 20 is a circuit for control of display performed by the electro-optic apparatus 1. An input display data Da-in is inputted to the image processing circuit 20 from the external apparatus in synchronization with the synchronization signal Sync. The input display data Da-in is pieces of digital data which specify gray-scale values of a respective plurality of pixels (corresponding to a display area 101 described below) included in the liquid crystal panel 100. The gray-scale value is a parameter for specifying the brightness of a pixel. Here, a piece of the input display data Da-in is made a piece of data of eight bits so that a gray-scale value to be represented by a pixel can be specified by one of decimal values varying, by “1”, from “0” which corresponds to the darkest state, and “255” which corresponds to the brightest state. The pieces input display data Da-in are supplied in order of scanning in accordance with vertical scanning signals, horizontal scanning signals and dot clock signals (these signals are omitted from illustration), which are included in the synchronization signal Sync. The image processing circuit 20 processes the input display data Da-in, and then outputs display data Da-out to the liquid crystal panel 100.
The liquid crystal panel is, for example, a display apparatus (a display unit) of active matrix type, in which each pixel is driven by a switching element such as a transistor. The liquid crystal panel 100 displays images on the basis of the display data Da-out supplied from the image processing circuit 20. In addition, the input display data Da-in specifies gray-scale values of corresponding pixels (each being a pixel 110 described below) included in the liquid crystal panel 100, while applied voltages applied to liquid crystal elements are determined in accordance with the gray-scale values, respectively, and thus, it can be said that the input display data Da-in specifies applied voltages applied to corresponding liquid crystal element.
The scanning line driving circuit 130 and the data line scanning circuit are located in peripheral areas of the display area 101.
The scanning line driving circuit 130 selects one of the scanning lines 112, which is specified by a selection signal Yctr supplied from the timing control circuit 10. The scanning line driving circuit 130 sets a scanning signal corresponding to the selected scanning line 112 to an H (high) level, which corresponds to a selection voltage, and meanwhile, sets each of scanning signals corresponding to the respective other scanning lines 112 to an L (low) level, which corresponds to a non-selection voltage. In
The data line driving circuit 140 is a circuit which drives the pixels 110 by using a so-called voltage modulation method on the basis of the display data Da-out. Specifically, the data line driving circuit 140 supplies the 1st to n-th rows of the data lines 114 with data signals having amounts of voltage corresponding to pieces of display data Da-out, respectively, in accordance with a selection signal Xctr supplied from the timing control circuit 10.
The pixel 110 has a liquid crystal element interposed between a pixel electrode and a common electrode, and while one of the scanning lines 112 is selected, a data signal supplied to one of the data lines 114 is applied to the corresponding pixel electrode.
The driving circuits in the electro-optic apparatus 1 can be realized by cooperation of the scanning line driving circuit 130 and the data line driving circuit 140 which are configured in such a manner as described above.
Here, when the voltage level of a scanning lines 112 is changed to H level, a thin film transistor (TFT) having a gate electrode connected to the scanning line 112 is turned on, so that a corresponding pixel electrode 118 is connected to a corresponding data line 114. Thus, during a period when the voltage level of the scanning line 112 is H level, when a data signal having a voltage level corresponding to a gray-scale value is supplied to the corresponding data line 114, the data signal is supplied to the corresponding pixel electrode 118 via the TFT 116 which is in the turned-on state. When the voltage level of the scanning line 112 has been changed to L level, the TFT 116 is turned off, but the voltage level of the voltage having been applied to the corresponding pixel electrode 118 is held by the capacitance of the liquid crystal element 120 and the auxiliary capacitor 125.
In the liquid crystal element 120, the molecule alignment state of the liquid crystal 105 changes in accordance with electric field caused by the pixel electrode 118 and the common electrode 108. Thus, in the case of a transmissive type, the liquid crystal element 120 has a transmittance ratio depending on the voltage level of an applied voltage or a hold voltage. In the liquid crystal panel 100, in order to change the transmittance ratios for the respective liquid crystal elements 120, the respective pixels 110 are configured so as to include the liquid crystal elements 120. In addition, in this embodiment, the liquid crystal 105 is configured according to a vertical alignment (VA) method, and is in a normally black mode in which the liquid crystal element 120 is in a black state when no voltage is applied thereto.
In order to prevent degradation of the liquid crystal 105, it is a principle to drive the liquid crystal element 120 by using an alternating-current voltage. In the case where the liquid crystal element 120 is driven by using an alternating-current voltage, when driving the liquid crystal element 120 to allow the liquid crystal element 120 to represent a gray-scale value, the alternating-current voltage needs to have two kinds of voltage polarities, one being a positive voltage polarity having a voltage level higher than a central voltage level of the amplitude of the alternating-current voltage, the other one being a negative voltage polarity having a voltage level lower than the central voltage level of the amplitude of the alternating-current voltage.
In addition, in this embodiment, it is supposed that a voltage except for the applied voltage applied to the liquid crystal element 120 is a voltage relative to ground electric-potential (not illustrated) which is made a reference voltage having a voltage level of zero volt, unless explicitly stated. The applied voltage applied to the liquid crystal element 120 corresponds to an electric-potential difference between a voltage LCcom of the common electrode 108 and the electric-potential of the pixel electrode 118. When causing the liquid crystal element 120 to maintain a voltage having a voltage level corresponding to a gray-scale value, in the case where a writing polarity is a positive polarity, the electric-potential of the pixel electrode 118 is higher than the voltage LCcom of the common electrode 108, and in the case where the writing polarity is a negative polarity, the electric-potential of the pixel electrode 118 is lower than the voltage LCcom of the common electrode 108.
Here, when there exist two adjacent pixels including the liquid crystal elements 120 for which applied voltages have voltage levels which are largely different from each other, the magnitude of lateral electric field becomes larger because of the large difference between the applied voltages, so that disclination sometimes occurs. Among these pixels, a low gray-scale side (low electric-potential side) pixel (a first pixel) may indicate a black state or a substantially black state corresponding to a gray-sale value near a minimum gray-scale value, or may indicate a relatively bright state corresponding to a gray-scale value around an intermediate gray-scale value. Meanwhile, a high gray-scale side (high electric-potential side) pixel (a second pixel) may indicate a state of brightness corresponding to a gray-scale value around an intermediate gray-scale level, or may indicate a white state or a substantially white state corresponding to gray-scale level near a maximum gray-scale value. As described above, disclination occurs because of an electric-potential difference between adjacent pixels, and the magnitudes of brightness around the occurrence areas thereof are various.
Here, in order to suppress the occurrence of disclination between the pixel 110a and the pixel 110b, it is necessary to reduce a gray-scale difference (an electric-potential difference) between the pixel 110a and the pixel 110b, and further, in order to suppress the occurrence of disclination between the pixel 110b and the pixel 110c, it is necessary to reduce a gray-scale difference (an electric-potential difference) between the pixel 110b and the pixel 110c. For this reason, in the case where disclination is likely to occur in any one of both pixels adjacent to a pixel, the electro-optic apparatus 1 according to this embodiment causes the image processing circuit 20 to make correction on voltages applied to the pixels such that gray-scale differences with the respective both pixels, not a gray-scale difference with any one of the both pixels, are reduced.
Here, a configuration of the image processing circuit 20 is described with reference to
The frame memory 21 has storage areas corresponding to a pixel array of m rows in the vertical direction and n columns in the horizontal direction, the pixel area corresponding to the display area 101, and stores therein the input display data Da-in whose size is equivalent to that of one segment (one frame). The storage areas store therein pieces of input display data Da-in which specify gray-scale values of the pixels 110 corresponding to the storage areas themselves, respectively. Here, the frame means a period of time necessary to display one segment of image data by driving the liquid crystal panel 100. In the case where the frequency of a vertical scanning signal included in the synchronization signal Sync is 60 Hz, the period of time results in the reciprocal of 60 Hz, that is, 6.7 milliseconds.
In addition, the pieces of input display data Da-in are supplied from an external apparatus, and are written into the corresponding storage areas of the frame memory 21. Further, writing operation of writing the input display data Da-in into the frame memory 21 and reading operation of reading out display data Da-d from the frame memory 21 are performed by, for example, a memory controller (not illustrated) in accordance with driving timing in the liquid crystal panel 100 under the control of the timing control circuit 100. The input display data Da-in and the display data Da-d have substantially the same content of display, but these kinds of data are distinguished from a viewpoint as to whether currently handled data is data to be written into the frame memory 21 or data to be read out from the frame memory 21.
The boundary detection unit 22 analyzes the data Da-d having been read out from the frame memory 21, and thereby, detects boundaries between low gray-scale (low electric-potential) side pixels (second pixels) and high gray-scale (high electric-potential) side pixels (first pixels), the boundaries being ones at each of which a difference between gray-scale values (applied voltage levels), which are specified by the input display data Da-in, is larger than or equal to a threshold value (a boundary detection step). Specifically, the boundary detection unit 22 detects boundaries, at each of which a gray-scale difference value between the first pixel and the second pixel, which are located adjacent to each other, is larger than or equal to a threshold value, on the basis of the display data Da-d. If any boundary satisfying the above condition has been detected, the boundary detection unit 22 sets the value of an output flag Q to “1”, and otherwise, the boundary detection unit 22 sets the value of the output flag Q to “0”. In addition, pixels adjacent to each pixel are, when viewed from a certain pixel, pixels whose side and one of the sides of the certain pixel are opposite to each other. Thus, four pixels are adjacent to a certain one of the pixels except for pixels located at edge portions of the image display area. Moreover, with respect to a threshold value for a voltage difference (a gray-scale difference) between adjacent pixels, the voltage difference being a condition of the occurrence of discrimination, for example, a value having been calculated on a trial basis is set to the image processing circuit 20.
Further, in the case where the boundary detection unit 22 has detected a plurality of boundaries each satisfying the above condition, the boundary detection unit 22 identifies the location of a boundary for which a gray-scale difference between pixels adjacent to a detected boundary is a minimum one among the gray-scale differences with respect to all the detected boundaries, and the detected location of the boundary relative to a pixel of interest is outputted as a signal Dir.
The gray-scale difference calculation unit 23 calculates a gray-scale difference Δ between gray-scale values of two pixels contacted with each of the boundaries having been detected by the boundary detection unit 22, on the basis of the display data Da-d having been read out from the frame memory 21. Here, the gray-scale difference calculation unit 23 calculates the gray-scale difference Δ by subtracting the gray-scale value of the low gray-scale (low electric-potential) side pixel from the gray-scale value of the high gray-scale (high electric-potential) side pixel. In addition, the gray-scale difference Δ corresponds to an applied voltage difference between pixels. Accordingly, as a result, the larger the gray-scale difference Δ becomes, the larger the applied voltage difference, which is related to the liquid crystal element 120, between pixels.
The correction calculation unit 24 has a memory area for storing therein a first correction coefficient α and a second correction coefficient β, and calculates correction values ΔRE1 and ΔRE2 by causing these corresponding correction coefficients to act on the gray-scale difference Δ having been calculated by the gray-scale difference calculation unit 23. In addition, in this embodiment, the correction coefficients α and β satisfy relations: 0≦First correction efficient α≦0.5 and 0≦Second correction efficient β≦0.5, and here, takes values as follows: α=0.5 and β=0.25. The correction calculation unit 24 calculates the correction value ΔRE1 by multiplying the gray-scale difference Δ, which has been calculated by the gray-scale difference calculation unit 23, by (1−First correction coefficient α). For example, when the gray-scale difference Δ is “40”, the correction value ΔRE1 can be calculated as follows: 40×(1−0.5)=20. Further, the correction calculation unit 24 calculates the correction value ΔRE2 by multiplying the gray-scale difference Δ by the second correction coefficient β. For example, when the gray-scale difference Δ is “40”, the correction value ΔRE2 can be calculated as follows: 40×0.25=10.
The correction unit 25 performs correction processing on the display data Da-d related to pixels, and outputs the display data Da-out to the liquid crystal panel 100 (a correction step). The correction unit 25 corrects the display data Da-d, provided that the value of the flag Q, which has been outputted from the boundary detection unit 22, is “1” and the following conditions (1) and (2) are satisfied.
In addition, the minimum gray-scale difference ΔN is a value having been set in advance through a design.
With respect to a high gray-scale side pixel, the correction unit 25 defines a value, which results from subtracting the correction value ΔRE1 from a gray-scale value of the high gray-scale side pixel, as a post-correction gray-scale value. Moreover, with respect to a low gray-scale side pixel, the correction unit 25 defines a value, which results from adding the correction value ΔRE2 to a gray-scale value of the low gray-scale side pixel, as a post-correction gray-scale value.
Subsequently, a specific example of correction processing performed by the correction unit 25 will be described.
Further, in
In the case where a pre-correction state is a state shown in
Here, in the case where the gray-scale difference Δ1 between the high gray-scale side pixel 110a (first pixel) and the low gray-scale side pixel 110b (second pixel) is larger than or equal to the minimum gray-scale difference ΔN, the boundary detection unit 22 determines that there exists a boundary at which disclination is likely to occur, and outputs the flag Q whose value has been set to “1”. Further, the boundary detection unit 22 identifies the location of a boundary at which the gray-scale difference is a minimum one, and a location of this boundary relative to the pixel of interest is outputted as the signal Dir. Here, since the location of the relevant boundary is located at the right side of the pixel of interest, the content of the signal Dir becomes content representing a right side.
Meanwhile, the gray-scale difference calculation unit 23 acquires the gray-scale value (250) specified by the display data Da-d corresponding to the pixel 110a, which is a pixel of interest, and the gray-scale value (190) specified by the display data Da-d corresponding to the pixel 110b, and calculates the gray-scale difference Δ1 between the both pixels. The ray-scale difference calculation unit 23 outputs the calculated gray-scale difference to the correction value calculation unit 24.
Since the value of the flag Q having been outputted form the boundary detection unit 22 is “1”, the correction value calculation unit 24 calculates the correction values ΔRE1 and ΔRE2 on the basis of the gray-scale difference having been obtained from the gray-scale difference calculation unit 23. Here, since the gray-scale difference Δ1 is “60”, the correction value ΔRE1 is calculated as follows: 60×(1−0.5)=30, and Correction value ΔRE2 is calculated as follows: 60×0.25=15. The correction value calculation unit 24 outputs the calculated ΔRE1 and ΔRE2 to the correction unit 25.
Next, in the case where the value of flag Q is “1”, and the above-described conditions (1) and (2) are satisfied, the correction unit 25 corrects the corresponding display data a-d. In the case where the gray-scale difference Δ1 is larger than or equal to the minimum gray-scale difference ΔN, and the boundary exists at the right side of the pixel of interest, the correction unit 25 corrects the pieces of display data Da-d corresponding to the respective pixels 110a and 110b.
Here, the content of the signal Dir indicates a right side, and thus, a boundary regarding the pixel of interest, at which the gray-scale difference becomes a minimum one, is located at the right side of the pixel of interest (i.e., at the pixel 110b side). In the case where a boundary at which the gray-scale difference becomes a minimum one is located at the right side of the pixel of interest, the correction unit 25 calculates the gray-scale value of a pixel which is located at the high gray-scale side relative to the boundary by using a formula: Gray-scale value of pixel at high gray-scale side−ΔRE1. Here, since the gray-scale value of the high gray-scale side pixel 110a is 250, and the ΔRE1 is 30, the post-correction gray-scale value of the pixel 110a becomes 220 (a corresponding applied voltage is a V12). Further, the gray-scale value of a pixel which is located at the low gray-scale side relative to the boundary is calculated by using a formula: Gray-scale value of pixel at low gray-scale side+ΔRE2. Here, since the gray-scale value of the low gray-scale side pixel 110b is 190, and the ΔRE2 is 15, the gray-scale value of the post-correction pixel 110b becomes 205.
Next the image processing circuit assigns the pixel 110b to a pixel of interest. In the case where the pixel 110b has been assigned to a pixel of interest, display data Da-d corresponding to the pixel 110b, which is a pixel of interest, and display data Da-d corresponding to the respective pixels 110a and 110c which are located adjacent to the pixel 110b are read out from the frame memory 21. The boundary detection unit 22 acquires gray-scale values specified by the pieces of display data Da-d corresponding to the respective pixels 110a to 110c, and determines whether or not at each of the boundaries between the pixels 110a and 110b and between the pixels 110b and 110c is a boundary at which disclination is likely to occur. Here, as described above, the boundary between the pixels 110a and 110b is determined as a boundary at which disclination is likely to occur. Moreover, in the case where, with respect to the boundary between the pixels 110b and 110c, the gray-scale difference Δ2 is larger than or equal to the minimum gray-scale difference ΔN, the boundary detection unit 22 determines the boundary between the pixels 110b and 110c as a boundary at which disclination is likely to occur. Since the boundary detection unit 22 has determined that there exists a boundary regarding the pixel of interest, at which disclination is likely to occur, the boundary detection unit 22 outputs the flag Q whose value has been set to “1”.
Further, the boundary detection unit 22 identifies the location of a boundary at which a gray-scale difference is a minimum one among the boundaries at each of which disclination is likely to occur, and outputs the location of the relevant boundary relative the pixel of interest as the signal Dir. Here, the gray-scale difference Δ1 between the pixels 110a and 110b is 60, the gray-scale difference Δ2 between the pixels 110b and 110c is 40, and the location of the boundary at which the gray-scale difference is a minimum one is located at the right side of the pixel of interest, and thus, the content of the signal Dir becomes content representing a right side.
Meanwhile, the gray-scale difference calculation unit 23 acquires the gray-scale value (190) specified by the display data Da-d corresponding to the pixel 110b, and the gray-scale value (150) specified by the display data Da-d corresponding to the pixel 110c, and calculates the gray-scale difference (Δ2=40) between the both pixels. The ray-scale difference calculation unit 23 outputs the calculated gray-scale difference to the correction value calculation unit 24.
Since the value of the flag Q having been outputted from the boundary detection unit 22 is “1”, the correction value calculation unit 24 calculates the correction values ΔRE1 and ΔRE2 on the basis of the gray-scale difference having been obtained from the gray-scale difference calculation unit 23. Here, the correction values ΔRE1 and ΔRE2 are calculated on the basis of the gray-scale difference between the pixels 110b and 110c, the correction value ΔRE1 is calculated as follows: 40×(1−0.5)=20, and the correction value ΔRE2 is calculated as follows: 40×0.25=10.
Next, in the case where the value of flag Q is “1”, and the above-described conditions (1) and (2) are satisfied, the correction unit 25 corrects the corresponding display data Da-d. In addition, here, the content of the signal Dir indicates a right side, and thus, a boundary regarding the pixel of interest, at which the gray-scale difference becomes a minimum one, is located at the right side of the pixel of interest (i.e., at the pixel 110c side).
In the case where a boundary regarding the pixel of interest, at which the gray-scale difference becomes a minimum one, is located at the right side of the pixel of interest, the correction unit 25 calculates the gray-scale value of a pixel which is located at the high gray-scale side relative the boundary by using a formula: Gray-scale value of a pixel at high gray-scale side−ΔRE1. Here, since the gray-scale value of the high gray-scale side pixel 110b is 190, and the ΔRE1 is 20, the post-correction gray-scale value of the pixel 110b becomes 170 (a corresponding applied voltage is a V22). Further, the gray-scale value of a pixel which is located at the low gray-scale side relative to the boundary is calculated by using a formula: Gray-scale value of a pixel at low gray-scale side+ΔRE2. Here, since the gray-scale value of the low gray-scale side pixel 110c is 150, and the ΔRE2 is 10, the gray-scale value of the post-correction pixel 110c becomes 160 (a corresponding applied voltage is a V32).
That is, in the case of
When such a correction has been made, a post-correction gray-scale difference Δ1a between the pixels 110a and 110b becomes 50. Since the pre-correction gray-scale difference Δ1 was 60, the gray-scale difference becomes smaller than that as of before the correction, that is, the gray-scale difference between the pixels becomes smaller. Further, a gray-scale difference Δ2a between the post-correction pixels 110b and 110c becomes 10. Since the pre-correction gray-scale difference Δ2 was 40, the gray-scale difference becomes smaller than that as of before the correction, that is, the gray-scale difference between the pixels becomes smaller.
When correcting the gray-scale values (voltage levels) of pixels by means of the aforementioned method according to this embodiment, the correction is made so as to make electric-potential differences between pixels smaller as compared with those as of before the correction, and thus, it is possible to suppress the occurrences of disclination.
Incidentally, in the case where Δ1>Δ2, the post-correction gray-scale difference Δ1a of the gray-scale difference Δ1 is represented as follows: Δ1a=Δ1−Δ1×(1−α)+Δ2×(1−α). Therefore, the following formula is derived: Δ1−Δ1a=Δ1×(1−α)−Δ2×(1−α)=(Δ1−Δ2)×(1−α). In the case of
Here, in the case where β=0, the formulas above are transformed as follows: Δ1a=Δ1−Δ1×(1−α)+Δ2×(1−α)=Δ1×α+Δ2×(1−α), and Δ2a=Δ2−Δ2×(1−α)=Δ2×α. Since Δ1>Δ2, the following formula is derived: Δ1×α>Δ2×α, so that the following formula is concluded: Δ1a>Δ2a. Next, in the case where β is a value other than 0, Δ2a is further smaller by Δ2×β, and thus, the following formula is always satisfied: Δ1a>Δ2a. That is, it follows that even after the correction, with respect the pixel 110b, a relation, in which the gray-scale difference with a pixel located at the left side of the pixel 110b is larger than the gray-scale difference with a pixel located at the right side of the pixel 110b, is kept.
Next, an example of correction processing in the case where a pre-correction state is shown in
Here, in the case where the gray-scale difference Δ1 between the high gray-scale side pixel 110a and the low gray-scale side pixel 110b is larger than or equal to the minimum gray-scale difference ΔN, the boundary detection unit 22 determines that there exists a boundary at which disclination is likely to occur, and outputs the flag Q whose value has been set to “1”. Further, the boundary detection unit 22 identifies the location of a boundary at which the gray-scale difference is a minimum one, and a location of the relevant boundary relative to the pixel of interest is outputted as the signal Dir. Here, since the location of the relevant boundary is located at the right side of the pixel of interest, the content of the signal Dir becomes content representing a right side.
Meanwhile, the gray-scale difference calculation unit 23 acquires the gray-scale value (250) specified by the display data Da-d corresponding to the pixel 110a, and the gray-scale value (210) specified by the display data Da-d corresponding to the pixel 110b, and calculates the gray-scale difference Δ (Δ1) between the both pixels. The gray-scale difference calculation unit 23 outputs the calculated gray-scale difference to the correction value calculation unit 24.
Since the value of the flag Q having been outputted form boundary detection unit 22 is “1”, the correction value calculation unit 24 calculates the correction values ΔRE1 and ΔRE2 on the basis of the gray-scale difference having been obtained from the gray-scale difference calculation unit 23. Here, since the gray-scale difference Δ1 is “40”, the correction value ΔRE1 is calculated as follows: 40×(1−0.5)=20, and the correction value ΔRE2 is calculated as follows: 40×0.25=10. The correction value calculation unit 24 outputs the calculated ΔRE1 and ΔRE2 to the correction unit 25.
Next, in the case where the value of the flag Q is “1”, and the above-described conditions (1) and (2) are satisfied, the correction unit 25 corrects the corresponding display data Da-d. In the case where the gray-scale difference Δ1 is larger than or equal to the minimum gray-scale difference ΔN, the correction unit 25 corrects the display data Da-d corresponding to the respective pixels 110a and 110b.
Here, the content of the signal Dir indicates a right side, and thus, a boundary regarding the pixel of interest, at which the gray-scale difference becomes a minimum one, is located at the right side of the pixel of interest (i.e., at the pixel 110b side). In the case where a boundary regarding the pixel of interest, at which the gray-scale difference becomes a minimum one, is located at the right side of the pixel of interest, the correction unit 25 calculates the gray-scale value of a pixel which is located at the high gray-scale side relative to the boundary by using a formula: Gray-scale value of a pixel at high gray-scale side−ΔRE1. Here, since the gray-scale value of the high gray-scale side pixel 110a is 250, and the ΔRE1 is 20, the post-correction gray-scale value of the pixel 110a becomes 230 (a corresponding applied voltage is a V13). Further, the gray-scale value of a pixel which is located at the low gray-scale side relative to the pixel of interest is calculated by using a formula: Gray-scale value of a pixel at low gray-scale side+ΔRE2. Here, since the gray-scale value of the low gray-scale side pixel 110b is 210, and the ΔRE2 is 10, the gray-scale value of the post-correction pixel 110b becomes 220.
Next the image processing circuit assigns the pixel 110b to a pixel of interest. In the case where the pixel 110b has been assigned to a pixel of interest, display data Da-d corresponding to the pixel 110b, which is a pixel of interest, and display data Da-d corresponding to the respective pixels 110a and 110c which are located adjacent to the pixel 110b are read out from the frame memory 21. The boundary detection unit 22 acquires gray-scale values specified by the display data Da-d corresponding to the pixels 110a to 110c, and determines whether or not at each of the boundaries between the pixels 110a and 110b and between the pixels 110b and 110c is a boundary at which disclination is likely to occur. Here, as described above, the boundary between the pixels 110a and 110b is determined as a boundary at which disclination is likely to occur. Moreover, in the case where, with respect to the boundary between the pixels 110b and 110c, the gray-scale difference Δ2 is larger than or equal to the minimum gray-scale difference ΔN, the boundary detection unit 22 determines the boundary between the pixels 110b and 110c as a boundary at which disclination is likely to occur. Since the boundary detection unit 22 has determined that there exists a boundary regarding the pixel of interest, at which disclination is likely to occur, the boundary detection unit 22 outputs the flag Q whose value has been set to “1”.
Further, the boundary detection unit 22 identifies the location of a boundary at which a gray-scale difference is a minimum one among the boundaries at each of which disclination is likely to occur, and outputs a location of the relevant boundary relative the pixel of interest as the signal Dir. Here, the gray-scale difference Δ1 between the pixels 110a and 110b is 40, the gray-scale difference Δ2 between the pixels 110b and 110c is 60, and the location of the boundary at which the gray-scale difference is a minimum one is located at the left side of the pixel of interest, and thus, the content of the signal Dir becomes content representing a left side.
Meanwhile, the gray-scale difference calculation unit 23 acquires the gray-scale value (210) specified by the display data Da-d corresponding to the pixel 110b, and the gray-scale value (150) specified by the display data Da-d corresponding to the pixel 110c, and calculates the gray-scale difference (Δ2=60) between the both pixels. The ray-scale difference calculation unit 23 outputs the calculated gray-scale difference to the correction value calculation unit 24.
Since the value of the flag Q having been outputted from the boundary detection unit 22 is “1”, the correction value calculation unit 24 calculates the correction values ΔRE1 and ΔRE2 on the basis of the gray-scale difference having been obtained from the gray-scale difference calculation unit 23. Here, the correction values ΔRE1 and ΔRE2 are calculated on the basis of the gray-scale difference between the pixels 110b and 110c, the correction values ΔRE1 is calculated as follows: 60×(1−0.5)=30, and the correction value ΔRE2 is calculated as follows: 60×0.25=15.
Next, in the case where the value of flag Q is “1”, and the above-described conditions (1) and (2) are satisfied, the correction unit 25 corrects the corresponding display data Da-d. In addition, here, the content of the signal Dir indicates a left side, and thus, a boundary regarding the pixel of interest, at which the gray-scale difference becomes a minimum one, is located at the left side of the pixel of interest (i.e., at the pixel 110a side).
In the case where the boundary regarding the pixel of interest, at which the gray-scale difference becomes a minimum one, is located at the left side of the pixel of interest, the correction unit 25 does not make correction with respect to the pixel 110b, which is a pixel of interest, and makes correction with respect to the pixel 110c, which is located adjacent to the pixel of interest, by using the correction value ΔRE2. Specifically, the gray-scale value of the pixel 110b has become 220 as the result of the above correction, and thus, the gray-scale value of the pixel 110b remains 220 as it is (a corresponding applied voltage is a V42). Further, the gray-scale value of the low gray-scale side pixel 110c relative to the pixel of interest is 150 and the ΔRE2 is 15, and thus, the post-correction gray-scale value of the pixel 110c becomes 165 (a corresponding applied voltage is a V33).
That is, in the case of
When such a correction has been made, the post-correction gray-scale difference Δ1a between the pixels 110a and 110b becomes 10. Since the pre-correction gray-scale difference Δ1 was 40, the gray-scale difference becomes smaller than that as of before the correction, that is, the gray-scale difference between the pixels becomes smaller. Further, the post-correction gray-scale difference Δ2a between the pixels 110b and 110c becomes 55. Since the pre-correction gray-scale difference Δ2 was 60, the gray-scale difference becomes smaller than that as of before the correction, that is, the gray-scale difference between the pixels becomes smaller.
When correcting the gray-scale values (voltage levels) of pixels by means of the aforementioned method according to this embodiment, the correction is made so as to make electric-potential differences between pixels smaller as compared with those as of before the correction, and thus, it is possible to suppress the occurrences of disclination.
Incidentally, in the case where Δ1<Δ2, the post-correction gray-scale difference Δ2a of the gray-scale difference Δ2 is represented as follows: Δ2a=Δ2−Δ2×β+Δ1×β. Therefore, the following formula is derived: Δ2−Δ2a=Δ2×β−Δ1×β=(Δ2−Δ1)×β. In the case of
Here, in the case where α=0, the formulas above are transformed as follows: Δ1a=Δ1−Δ1×β=Δ1×(1−β), and Δ2a=Δ2−Δ2×β+Δ1×β=Δ2×(1−β)+Δ1×β. Since Δ1<Δ2, a formula: Δ2×(1−β)>Δ1×(1−β) is derived, and the following formula is concluded: Δ2a>Δ1a. Next, in the case where a is a value other than 0, Δ1a is further smaller by Δ1×(1−α), and thus, the following formula is constantly satisfied: Δ2a>Δ1a. That is, it follows that even after the correction, with respect to the pixel 110b, a relation, in which the gray-scale difference with a pixel located at the right side of the pixel 110b is larger than the gray-scale difference with a pixel located at the left side of pixel 110b, is kept.
An example of an electronics device employing the electro-optic apparatus 1 will be described.
Here, the configuration of the light valves 100R, 100G and 100B is similar to that of the liquid crystal panel 100 in the aforementioned embodiment, and the light valves are driven by data Da-out which is supplied from an external apparatus (not illustrated), and which corresponds to individual R, G and B colors. Light beams having been modulated by the respective light valves 100R, 100G and 100B are inputted to a dichroic prism 2112 from three directions. Further, in this dichroic prism 2112, the R-colored light beam and the B-colored light beam are each refracted at an angle of 90 degrees; while the G-colored light beam goes straight. Moreover, an image resulting from synthesizing individual colored images is subjected to normal rotation and extended projection, and finally, a color image is displayed on a screen 2120.
Images transmitting through the light valves 100R and 100B are projected after having been reflected by the dichroic prism 2112; while an image transmitting through the light valve 100G is projected as it is, and thus, there is a mirror reversed relation between an image formed by the light valves 100R and 100B, and an image formed by the light valve 100G.
In addition, well-known examples of an electronics device includes, besides the projector, a rear-projection type television device, a direct-view type television device, a mobile telephone, a personal computer, a video camera monitor, a car navigation device, a pager, an electronics diary, an electronic calculator, a word processer, a work station, a video telephone, a point of sales (POS) terminal, a digital still camera, a device with a touch panel, and the like. Further, the electro-optic apparatus according to some aspects of the invention can be also applied to such various types of electronics devices.
Hereinbefore, an embodiment according to the invention has been described, but the invention is not limited to the embodiment described above, and can be practiced in various forms. For example, the above-described embodiment may be transformed as described below, and there, the invention may be practiced. In addition, the above-described embodiment and the following individual modification examples may be appropriately combined.
In the embodiment described above, the liquid crystal panel 100 is a normally black panel, but, may be a normally white panel. In the case of a normally white display panel, a relation between the voltage applied to the liquid crystal element 120 and the gray-scale value regarding the liquid crystal element 120 is inverse to that in the case of a normally black panel, and the smaller the gray-scale value regarding the liquid crystal element 120 becomes, the larger the voltage level of the voltage applied to the liquid crystal element 120.
In the above-described embodiment, in the case where the gray-scale difference Δ1 between a pixel of interest and the pixel located at the left side of the pixel of interest is equal to the gray-scale difference Δ2 between the pixel of interest and the pixel located at the right side of the pixel of interest, correction processing may be performed in a way similar to that in the case where the gray-scale difference Δ2>the gray-scale difference Δ1.
In the above-described embodiment, the gray-scale value of a pixel of interest and the gray-scale values of pixels which are located adjacent to the pixel of interest in the direction in which the scanning lines 112 extend are corrected on the basis of gray-scale differences between the pixel of interest and the pixels which are located adjacent to the pixel of interest in the direction in which the scanning lines 112 extend, but pixels targeted for correction are not limited to such pixels, and, for example, the gray-scale values of pixels which are located adjacent to a pixel of interest in the direction in which the data lines 114 extend may be corrected. Moreover, the correction processing on the gray-scale values of pixels which are located adjacent to a pixel of interest in the direction in which the scanning lines 112 extend and the correction processing on the gray-scale values of pixels which are located adjacent to a pixel of interest in the direction in which the data lines 114 extend may be appropriately combined.
For example, in the case where α=0.5 and β=0.2, the gray-scale values of pixels are such as shown in
Further, in the case where the pixel denoted by (4) is assigned to a pixel of interest, a gray-scale difference between the pixel denoted by (4) and the pixel denoted by (1) is 120, and a gray-scale difference between the pixel denoted by (4) and a pixel denoted by (5) is 70. Thus, the ΔRE1 is calculated as follows: 70×(1−0.5)=35, and a post-correction gray-scale value of the pixel denoted by (4), which is a high gray-scale side pixel, is calculated by using an expression: Gray-scale value of pixel denoted by (4)−ΔRE1, and results in 215.
Moreover, in the case where a pixel denoted by (5) is assigned to a pixel of interest, a gray-scale difference between the pixel denoted by (5) and the pixel denoted by (2) is 50, and a gray-scale difference between the pixel denoted by (5) and a pixel denoted by (8) is 70. Thus, the ΔRE1 is calculated as follows: 50×(1−0.5)=25, and the ΔRE2 is calculated as follows: 50×0.2=10. A post-correction gray-scale value of the pixel denoted by (5), which is a high gray-scale side pixel, results in as follows: Gray-scale value of pixel denoted by (5)−ΔRE1=155, and a post-correction gray-scale value of the pixel denoted by (6), which is a low gray-scale side pixel, results in as follows: Gray-scale value of pixel denoted by (6)+ΔRE2=140.
In the above-described embodiment, the gray-scale values of a pixel of interest and a pixel located adjacent to the right side of the pixel of interest are corrected, but, for example, in the case where the viewable direction of liquid crystal is reverse to the direction thereof in the above-described embodiment, the gray-scale values of a pixel of interest and a pixel located adjacent to the left side of the pixel of interest may be corrected.
Although the foregoing description of operation is made under the condition that the gray-scale value of the pixel 110a>the gray-scale value of the pixel 110b>the gray-scale value of the pixel 110c, any condition under which the correction is made is not limited to this condition. For example, the gray-scale values of the respective pixels 110a to 110c may be corrected even in the case where, as shown in
Moreover, the gray-scale values of the respective pixels 110a to 110c may be also corrected even in the case where, as shown in
Furthermore, the gray-scale values of the respective pixels 110a to 110c may be corrected even in the case where relations between the pre-correction gray-scale values of the pixels 110a to 110c are such that the gray-scale value of the pixel 110a<the gray-scale value of the pixel 110b<the gray-scale value of the pixel 110c.
This application claims priority to Japan Patent Application No. 2012-055393 filed Mar. 13, 2012, the entire disclosures of which are hereby incorporated by reference in their entireties.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-055393 | Mar 2012 | JP | national |
