Patent Application
20170372672
The present invention relates to liquid crystal display devices and methods of manufacturing liquid crystal display devices.
Liquid crystal display devices with 2K1K resolution (approximately 2000 picture elements in the lateral direction×1000 picture elements in the longitudinal direction) exhibit a pixel charging rate with a sufficient margin. If a data signal line is broken, the device can be repaired by using redundant wiring that is provided in advance around the display unit. The data signal can be delivered to the broken data signal line via the redundant wiring without causing appreciable display unevenness. The margin of the pixel charging rate is, however, decreasing with progressive increase in physical size of the display unit. There is a configuration (see (a) of
Meanwhile, the liquid crystal display device has some area of continuously changing unevenness due to structural elements such as the backlight, optical films, and liquid crystal panel. This “inherent unevenness” can be alleviated by dividing the display unit into a plurality of local areas and correcting pixel data in each local area.
Patent Literature 1: PCT International Application Publication, No. WO2012/157093 (Publication Date: Nov. 22, 2012)
The configuration shown in (a) of
One of objects of the present invention is to provide a liquid crystal display device that reliably exhibits a sufficient pixel charging rate with a large display unit and that affords a solution to broken data signal line problems without compromising on display quality.
The present invention is directed to a liquid crystal display device including: a control circuit configured to perform input correction for a plurality of pixels in each one of local areas of a display unit, the input correction performed separately for each local area; a first driver electrically connected to an end of each one of data signal lines that correspond to the pixels; and a second driver electrically connected to another end of each data signal line, wherein the first and second drivers drive the data signal lines based on the input correction.
In the liquid crystal display device in accordance with the present invention, the first and second drivers drive each data signal line. Therefore, the liquid crystal display device exhibits a sufficient pixel charging rate with a large display unit and if one of the data signal lines is, for example, broken, still allows for individual driving of the two parts separated by the broken site. In addition, if at least one of the data signal lines corresponding to the pixels in a local area is broken, all the other data signal lines are deliberately disconnected, and input correction is performed considering this new condition. This configuration suppresses unevenness that occurs due to broken and disconnected data signal lines, enabling correction of the broken data signal line without compromising on display quality.
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The following will describe embodiments of the present invention in reference to
In the liquid crystal display device 1, each data signal line is driven by the two source drivers 4a and 4b (“double-sided source input drive”), Throughout the following description, the direction in which the scan signal lines extend will be referred to as the “row direction” or the “lateral direction;” the direction in which the data signal lines extend will be referred to as the “column direction” or the “longitudinal direction.”
In the display unit 2, each picture element includes a red (R) pixel (e.g., a pixel i1), a green (G) pixel (e.g., a pixel i2), and a blue (B) pixel (e.g., a pixel i3). The display unit 2 includes, for example, 8K4K picture elements (7680 picture elements in the lateral direction×4320 picture elements in the longitudinal direction). Considering current LCD manufacturing and driving technology, if the refresh rate is 60 Hz, the display unit 2 very preferably includes at least 3240 picture elements in the longitudinal direction (3240 scan signal lines) and diagonally measures at least 60 inches. Examples of such a display unit include integral multiples of 2K1K, which is a current base model (i.e., 1920×1080, 2048×1080, 1920×1200, and 2048×1200 from the television standards, digital cinema standards, PC monitor standards, and the like), such as 4K4K, 6K3K, 6K4K, and 8K4K. If the picture element count or diagonal dimension is smaller than these examples, charging has a sufficient margin to allow for single-sided source input drive in which the source driver is provided on a single side and to thereby enable suitable application of auxiliary wiring correction and other related technology. Note however that because the charging rate loses margin at high refresh rates, if the refresh rate is, for example, 120 Hz, the present invention is also suitably applicable to display units with approximately 4K2K picture elements.
The display unit 2 has a “double source structure” and includes two data signal lines for each column of pixels. Specifically, the odd-numbered pixels in a column of pixels are connected to one of the two data signal lines via transistors, and the even-numbered ones are connected to the other data signal line via transistors.
For example, as to the column-wise adjoining pixels i1, j1, and k1, the pixel i1 is connected to the data signal line S1 via a transistor, the pixel j1 is connected to the data signal line S2 via a transistor, and the pixel k1 is connected to the data signal line S1 via a transistor.
As to the column-wise adjoining pixels i2, j2, and k2, the pixel i2, adjoining the pixel i1 in the row direction, is connected to the data signal line S4 via a transistor, the pixel j2, adjoining the pixel j1 in the row direction, is connected to the data signal line S3 via a transistor, and the pixel k2, adjoining the pixel k1 in the row direction, is connected to the data signal line S4 via a transistor. The data signal lines S2 and S3 are located next to each other in this example. In a double source structure, two-line simultaneous selection is performed in which two adjacent scan signal lines are selected at a time. For example, the scan signal lines Gi and Gj are simultaneously selected before the scan signal lines Gk and Gm are simultaneously selected. Note that because each picture element in the display unit 2 shown in
Under the conditions described above (e.g., either there are 3240 or more scan signal lines, and the diagonal dimension is 60 inches or larger, or the refresh rate is 120 Hz), double-sided source input drive is often still short of providing a sufficient charging rate in single source structures. A double source structure is hence required to increase the charging rate. Therefore, the present embodiment is suitably applicable to a liquid crystal display device that requires double-sided source input drive in a double source structure for sufficient charging rate. The present embodiment is also suitably applicable to a liquid crystal display device having the single source structure (details will be given later) shown in
The display unit 2 is divided into a plurality of blocks (local areas), each measuring 1 pixel in the longitudinal direction and 12 pixels in the lateral direction. For example, as to an i-th row of pixels, a block Bi1 contains the pixels i1 to i12, and a block Bi2 contains the pixels i13 to i24; as to a j-th row of pixels, a block Bj1 contains the pixels j1 to j12, and a block Bj2 contains the pixels j13 to j24; and as to a k-th row of pixels, a block Bk1 contains the pixels k1 to k12, and a block Bk2 contains the pixels k13 to k24.
The control circuit 5 performs, for each block, input correction for pixels in that block. The input correction suppresses inherent unevenness caused by structural elements including the backlight, optical films, and liquid crystal panel. As an example, as depicted in
Portion (a) of
The lookup table LUT1 contains a plurality of corrected values for unevenness correction throughout a single block. Each local area in the present embodiment is preferably set up to have a greater dimension in the lateral direction than in the longitudinal direction: for example, 1×12. When this is actually the case, if the lookup table LUT1 contains corrected values C1 and C12 for the pixels located on the ends of each block (the pixels i1 and i12), for example, a corrected value C8 for the eighth pixel can be calculated by simple linear interpolation between the two points and given by the formula: C8=C1+{(C12−C1)/(12−1)}×(8−1).
The local area may have a lateral dimension of, for example, 16 or 32 for more simple calculation. The corrected values for the 1st and 33rd pixels may be used in correcting pixel data for the 1st to 32nd pixels for more simple division. These modifications can be made without departing from the scope of the present embodiment.
It is possible to specify an independent corrected value for each pixel (i.e., for each primary color). It is however desirable to specify associated corrected values for pixels (e.g., R, G, and B pixels) in each picture element (e.g., specify the same corrected value for all the pixels in each picture element) for more simple calculation, as well as for compatibility with other video processing and grayscale procedures.
The dimensions of the local area may be specified in any manner in accordance with various conditions. The lateral dimension may be selected from approximately 4 to 64 pixels by considering the condition of unevenness (e.g., linearity of unevenness) across the panel and case of implementation. If the lateral dimension is too large, the correction of inherent unevenness is too much to be linearly approximated, and intermediate corrected values need to be introduced, which complicates the calculation. On the other hand, if the lateral dimension is too small, the table grows too large in total size. In either case, the correction circuit needs to bear a heavier workload.
The longitudinal dimension varies depending on how the panel is driven and in what environment the display device is viewed (viewing distance, resolution, and the like) and may tolerably be, for example, two or four lines. If the longitudinal dimension grows large, the interpolation becomes two-dimensional, which complicates calculation. Therefore, generally, the longitudinal dimension is preferably specified not to exceed the size that the viewer recognizes as a single line on a display. In the present embodiment, preferably, the longitudinal dimension is basically one line and may be two lines, for example, when a double source structure (two-line simultaneous selection drive) is used to treat two lines collectively as a single line.
The lookup table LUT1, in a preferred example, contains three sets of data for each 1×n local area (input gray levels, a corrected value for the pixel on the left end, and a corrected value for the pixel on the right end) so that an actual corrected value for each pixel can be calculated from the input gray level and location of the pixel by interpolation. For example, if the three sets of data are (0,0,0), (63,10,12), (127,8,10), (191,4,6), and (255,0,0), and gray level 95 is inputted for the center of the local area, the corrected value for the left end is calculated to be (10+8)/2=9, the corrected value for the right end is calculated to be (12+10)/2=11, the corrected value for the center is calculated to be (9+11)/2=10, and the corrected gray level is calculated to be 95+10=105, and all these results are outputted.
Lattice points that are related to grayscale are designated at every 8 or 16 gray levels out of the 256 gray levels for simple calculation. The inventors have confirmed that these lattice points work reasonably well in the interpolation.
In the liquid crystal display device 1, an end of each data signal line is connected to the source driver 4a, and the other end thereof is connected to the source driver 4b. Therefore, if, for example, the data signal line S4 is broken as shown in (a) of
Accordingly, in the liquid crystal display device 1, if at least one of the data signal lines corresponding to the pixels in a block is broken, all the other data signal lines are deliberately disconnected. Specifically, as to the data signal lines S1 to 24 corresponding to the pixels in the blocks Bi1, Bj1, and Bk1, since the data signal line S4 is broken, all the other data signal lines S1 to S3 and S5 to S24 are deliberately disconnected using, for example, a laser. In this example, the locations of the disconnected sites on the data signal lines S1 to S3 and S5 to S24 in the longitudinal direction are aligned with the location of the broken site on the data signal line S4 in the longitudinal direction, the distances from the source driver 4a to the disconnected sites on the data signal lines S1 to S3 and S5 to S24 are rendered equal to the distance from the source driver 4a to the broken site on the data signal line S4 (the loads on the upper parts of the data signal lines S1 to S24 are all rendered equal), and the distances from the source driver 4b to the disconnected sites on the data signal lines S1 to S3 and S5 to S24 are rendered equal to the distance from the source driver 4b to the broken site on the data signal line S4 (the loads on the lower parts of the data signal lines S1 to S24 are all rendered equal). Hence, the liquid crystal display device 1 is configured as shown in
Subjecting the liquid crystal display device shown in
The control circuit 5 performs, for each block, input correction (inherent unevenness correction and broken-line-/disconnected-line-caused unevenness correction) for the pixels in that block. As an example, as depicted in
As described so far, the liquid crystal display device 1 reliably exhibits a sufficient pixel charging rate with a large display unit and affords a solution to broken data signal line problems without compromising on display quality.
The inspection of a data signal line for a broken site and the disconnection of a broken data signal line with a laser may be performed in the following manner.
First, these processes can be performed on a bare active matrix substrate, in which the data signal lines are so easy to disconnect to accomplish state-of-the-art quality correction. A drawback is that because the active matrix substrate by itself is not capable of producing a display thereon, a broken site may be overlooked. Another drawback is that short-circuiting between a data signal line and a scan signal line (“SG leak”) cannot be discovered.
Next, liquid crystal is injected between the active matrix substrate and an opposite substrate and, the two substrates are combined, to obtain a liquid crystal panel. The processes can also be performed on this liquid crystal panel, in which a display can be produced so that problems can be reasonably easily located.
The liquid crystal panel may be combined with, for example, a polarizer, to obtain a liquid crystal display device. If the inspection and disconnection processes are performed on the liquid crystal display device, problems can be easily located, but the laser light needs to travel through the polarizer to disconnect data signal lines. This requirement results in poor precision and may damage the polarizer, which is undesirable.
It would be understood from the description above that the processes are preferably performed once on the bare active matrix substrate and again on the liquid crystal panel. In view of cost and other factors involved, however, it would be generally sufficient if the processes are performed primarily on the liquid crystal panel.
The LUT2 is preferably prepared on the basis of simultaneous evaluation of inherent unevenness and broken-line-/disconnected-line-caused unevenness in the liquid crystal display device.
Each block in Embodiment 1 measures 1 pixel in the longitudinal direction and 12 pixels in the lateral direction. Alternatively, the block may be of a smaller size (e.g., measuring 1 pixel in the longitudinal direction and 4 pixels in the longitudinal direction) and may be of a larger size (e.g., measuring 1 pixel in the longitudinal direction and 24 pixels in the longitudinal direction). Setting the longitudinal dimension to 1 pixel adds to the number of blocks. Under this setting, however, the correction values can be calculated by simple linear interpolation between the corrected values (reference corrected values) at the left and right ends, and this calculation is completed for each single line. These advantages work in favor of reduction in size of the control circuit 5.
The display unit 2 includes three-color-structure (R, G, and B) picture elements as an example and may alternatively include four-color-structure (R, G, B, and Y (yellow)) picture elements. In addition, the pixels are not necessarily arranged in a matrix and may alternatively be arranged as in a λ type.
Embodiment 1 has described correction of a broken data signal line. The liquid crystal display device 1 also allows for correction of short-circuiting between a data signal line and a scan signal line (“SG leak”).
Specifically, in the liquid crystal display device 1, if at least one of the data signal lines corresponding to the pixels in a block is short-circuited to a scan signal line, the short-circuited section is separated out, and all the other data signal lines are deliberately disconnected. More specifically, as to the data signal lines S1 to 24 corresponding to the pixels in the blocks Bi1, Bj1, and Bk1, since the data signal line S4 is short-circuited to the scan signal line Gk as shown in
The data signal lines S1 to S3 and S5 to S24 may be disconnected either between the blocks Bj1 and Bk1 or between the blocks Bk1 and Bm1 and preferably near the center of the display unit (between the blocks Bj1 and Bk1) where possible as shown in
Performing only the inherent unevenness correction depicted in
Accordingly, performing input correction on the liquid crystal display device shown in
The present invention is directed to a liquid crystal display device including: a control circuit configured to perform input correction for a plurality of pixels in each one of local areas of a display unit, the input correction performed separately for each local area; a first driver electrically connected to an end of each one of data signal lines that correspond to the pixels; and a second driver electrically connected to another end of each data signal line, wherein the first and second drivers drive the data signal lines based on the input correction.
In another aspect of the liquid crystal display device in accordance with the present invention, the first and second drivers supply an identical data signal to the data signal lines at an identical timing.
In yet another aspect of the liquid crystal display device in accordance with the present invention, the data signal lines that correspond to those of the pixels which are in at least one of the local areas include: at least one broken data signal line having a broken site thereon; and at least one disconnected data signal line having a deliberately disconnected site thereon.
In still another aspect of the liquid crystal display device in accordance with the present invention, the broken site and the disconnected site are aligned in a longitudinal direction, where the longitudinal direction is a direction in which the data signal lines extend.
In yet still another aspect of the liquid crystal display device in accordance with the present invention, the input correction, for the at least one of the local areas, suppresses both unevenness that occurs inherently and unevenness that occurs in connection with the broken and disconnected sites.
In a further aspect of the liquid crystal display device in accordance with the present invention, the data signal lines that correspond to those of the pixels which are in at least one of the local areas include: at least one short-circuited data signal line having thereon a short-circuited site where this particular data signal line is short-circuited to a scan signal line and two deliberately disconnected sites that reside across the short-circuited site; and at least one disconnected data signal line having a deliberately disconnected site thereon.
In yet a further aspect of the liquid crystal display device in accordance with the present invention, one of the two disconnected sites on the short-circuited data signal line and the disconnected site on the disconnected data signal line are aligned in a longitudinal direction, where the longitudinal direction is a direction in which the data signal lines extend.
In still a further aspect of the liquid crystal display device in accordance with the present invention, the input correction, for the at least one of the local areas, is intended to suppress both unevenness that occurs inherently and unevenness that occurs in connection with the two disconnected sites on the short-circuited data signal line and the disconnected site on the disconnected data signal line.
In yet still a further aspect of the liquid crystal display device in accordance with the present invention, for those of the pixels which are in the at least one of the local areas, the input correction is performed based on where that one of the local areas is located in the display unit in terms of the longitudinal direction.
In an additional aspect of the liquid crystal display device in accordance with the present invention, each one of the local areas contains one pixel in a longitudinal direction and 2 to 24 pixels in a lateral direction, where the longitudinal direction is a direction in which the data signal lines extend.
In another aspect of the liquid crystal display device in accordance with the present invention, the control circuit determines from a lookup table corrected values for at least two non-adjacent ones of the pixels in each one of the local areas as corrected values that serve as a plurality of references and determines corrected values for other pixels in that one of the local areas through interpolation using the corrected values that serve as the references.
In a further aspect of the liquid crystal display device in accordance with the present invention, one of the pixels in a column of pixels that extends in a longitudinal direction is connected to one of the data signal lines via a transistor, and another one of the pixels in the column is connected to another one of the data signal lines via a transistor, where the longitudinal direction is a direction in which the data signal lines extend.
The present invention is also directed to a method of manufacturing a liquid crystal display device including: a control circuit configured to perform input correction for a plurality of pixels in each one of local areas of a display unit, the input correction performed separately for each local area; a first driver electrically connected to an end of each one of data signal lines that correspond to the pixels; and a second driver electrically connected to another end of each data signal line, wherein the first and second drivers drive the data signal lines based on the input correction, the method including, as to the data signal lines that correspond to those of the pixels which are in each one of the local areas: (A) if at least one of those data signal lines is broken, deliberately disconnecting all the other data signal lines; and (B) if at least one of those data signal lines develops a short-circuited section where that one of the data signal lines is short-circuited to a scan signal line, separating out the short-circuited section and deliberately disconnecting all the other data signal lines.
The present invention is not limited to the embodiments and examples above. Proper variations and combinations of the embodiments and examples in view of general technical knowledge are encompassed in the technical scope of the present invention.
The liquid crystal display device in accordance with the present invention is suitably applicable to liquid crystal televisions, liquid crystal monitors, and television monitors.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-008940 | Jan 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/050474 | 1/8/2016 | WO | 00 |
