KR101028664B1 - Image degradation correction in novel liquid crystal displays with split blue subpixels - Google Patents

Abstract

A system and method are disclosed for correcting an image degraded signal on a liquid crystal display panel. A panel including a subpixel repeating group having an even number of subpixels in the first direction may have parasitic capacitance and other signal errors due to an incomplete point inversion scheme. Techniques for signal correction and localizing errors to specific sub-pixels are disclosed.

Description

IMAGE DEGRADATION CORRECTION IN NOVEL LIQUID CRYSTAL DISPLAYS WITH SPLIT BLUE SUBPIXELS

Commonly owned US patent application, namely (1) US Patent Application Serial No. 09,916,232, entitled "ARRANGEMENT OF COLOR PIXELS FOR FULL COLOR IMAGING DEVICES WITH SIMPLIFIED ADDRESSING," filed July 25, 2001. do"); (2) U.S. Patent Application Serial No. 10 / 278,353 filed "OEM PROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS FOR SUB-PIXEL RENDERING WITH INCREASED MODULATION TRANSFER FUNCTION RESPONSE," filed October 22, 2002 (" "Refers to 353 application"); (3) United States Patent Application Serial No. 10 / 278,352, entitled "IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS FOR SUB-PIXEL RENDERING WITH SPLIT BLUE SUB-PIXELS," filed October 22, 2002 (" '352 application "; (4) US Patent Application Serial No. 10 / 243,094, entitled "IMPROVED FOUR COLOR ARRANGEMENTS AND EMITTERS FOR SUB-PIXEL RENDERING," filed September 13, 2002; (5) U.S. Patent Application Serial No. 10 / 278,328, entitled "IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS WITH REDUCED BLUE LUMINANCE WELL VISIBILITY," filed October 22, 2002 "); (6) US Patent Application Serial No. 10 / 278,393, entitled "COLOR DISPLAY HAVING HORIZONTAL SUB-PIXEL ARRANGEMENTS AND LAYOUTS," filed Oct. 22, 2002 (called "393 Application"); (7) US Patent Application Serial No. 01 / 347,001 filed on January 16, 2003 entitled " IMPROVED SUB-PIXEL ARRANGEMENTS FOR STRIPED DISPLAYS AND METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING SAME, " In each of these, the entire contents are incorporated herein by reference in their entirety, and a novel subpixel device is disclosed for improving the cost / performance curve for an image display device.

These improvements are also described in this application and in the commonly owned U.S. patent application, which is hereby incorporated by reference in its entirety, namely (1) "CONVERSION OF RGB PIXEL FORMAT DATA TO PENTILE MATRIX, filed Jan. 16, 2002." SUB-PIXEL DATA FORMAT, US Patent Application Serial No. 10 / 051,612 entitled "" 612 Application "; (2) U.S. Patent Application Serial No. 10 / 150,355, entitled "METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING WITH GAMMA ADJUSTMENT," filed May 17, 2002 (called "355 application"); (3) US patent application Ser. No. 10 / 215,843, entitled “METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING WITH ADAPTIVE FILTERING,” filed Aug. 8, 2002; (4) US Patent Application Serial No. 10 / 379,767, entitled "SYSTEMS AND METHODS FOR TEMPORAL SUB-PIXEL RENDERING OF IMAGE DATA," filed March 4, 2003; (5) US Patent Application Serial No. 10 / 379,765, filed March 4, 2003, entitled "SYSTEMS AND METHODS FOR MOTION ADAPTIVE FILTERING,"; (6) US Patent Application Serial No. 10 / 379,766, entitled "SUB-PIXEL RENDERING SYSTEMS AND METHOD FOR IMPROVED DISPLAY VIEWING ANGLES," filed March 4, 2003; (7) in combination with a subpixel rendering (SPR) system and method, further disclosed in US Patent Application Serial No. 10 / 409,413, entitled "IMAGE DATA SET WITH EMBEDDED PRE-SUBPIXEL RENDERED IMAGE," filed April 7, 2003. Appears especially when

This application is a commonly owned US patent application, the disclosure of which is hereby incorporated by reference in its entirety, namely, (1) US entitled "DISPLAY PANEL HAVING CROSSOVER CONNECTIONS EFFECTING DOT INVERSION," filed June 6, 2003. Patent application serial number 10 / 455,925; (2) US Patent Application Serial No. 10 / 455,931 filed June 6, 2003 entitled "SYSTEM AND METHOD OF PERFORMING DOT INVERSION WITH STANDARD DRIVERS AND BACKPLANE ON NOVEL DISPLAY PANEL LAYOUTS,"; (3) US Patent Application Serial No. 10 / 455,927 filed June 6, 2003 entitled "SYSTEM AND METHOD FOR COMPENSATING FOR VISUAL EFFECTS UPON PANELS HAVING FIXED PATTERN NOISE WITH REDUCED QUANTIZATION ERROR," filed June 6, 2003; (4) US Patent Application Serial No. 10 / 456,806, entitled “DOT INVERSION ON NOVEL DISPLAY PANEL LAYOUTS WITH EXTRA DRIVERS, filed June 6, 2003; (5) US Patent Application Serial No. 10 / 456,838 entitled "LIQUID CRYSTAL DISPLAY BACKPLANE LAYOUTS AND ADDRESSING FOR NON-STANDARD SUBPIXEL ARRANGEMENTS,"

FIG. 1A illustrates an active matrix liquid crystal display (AMLCD) having a thin film transistor (TFT) 116 for activating sub-pixels of individual colors of red 104, green 106, and blue 108 subpixels, respectively. A conventional RGB stripe structure on 100 is shown. As can be seen, the red, green and blue subpixels form a repeating group of subpixels 102 that make up the panel.

As also shown, each pixel is connected to a column line (each driven by column driver 110) and a row line (eg, 112 and 114). In the field of AMLCDs it is known to drive the panel in a point reversal manner to reduce crosstalk or flicker. 1A shows one particular point inversion scheme, ie 1 x 1 point inversion, indicated by the "+" and "-" polarities provided at the center of each sub-pixel. Each row line is typically connected to a gate (not shown in FIG. 1A) of the TFT 116. The image data transferred via the column line is usually connected to the source of each TFT. Image data is written to the panel one row at a time, and a polarity bias scheme is provided as indicated herein in the ODD ("O") or EVEN ("E") scheme. As shown, row 112 is written in an ODD polarity manner at a given time, and row 114 is written in an EVEN polarity manner at the next time. In this 1 × 1 point inversion method, the polarity alternates between ODD and EVEN methods one row at a time.

Figure 1b shows another conventional RGB stripe panel with another point inversion scheme, i.e. 1 x 2 point inversion. In this case, the polarity is changed over the course of two rows, such that the polarity is reversed for every row at 1 × 1 point inversion. In both of these two point inversion schemes, some observations are noted: (1) In 1 x 1 point inversion, all two physically adjacent sub-pixels (both horizontal and vertical) have different polarities; (2) in 1x2 point inversion, all two physically adjacent subpixels in the horizontal direction have different polarities; (3) Over any given row, each successive color subpixel has a polarity opposite to its neighbor. Thus, for example, two consecutive red subpixels along a row become (+,-) or (-, +). Of course, in a 1 × 1 point inversion, two consecutive red subpixels along one column have the opposite polarity, whereas in 1 × 2 point inversion, each group of two consecutive red subpixels is opposite. It has polarity. This polarity change reduces the visible visual effects that occur with the particular image rendered on the AMLCD panel.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments and embodiments of the invention and, together with the description, serve to explain the principles of the invention.

1A shows a conventional RGB stripe panel having a 1 × 1 point inversion scheme.

1B illustrates a conventional RGB stripe panel having a 1 × 2 point inversion scheme.

FIG. 2 shows a panel with a novel subpixel repeating group with even pixels in the first (row) direction. FIG.

3 shows a panel with repeating grouping of FIG. 2 with multiple standard driver chips where any degradation of the image acts on the blue sub-pixels.

FIG. 4 is a diagram showing a phase relationship with respect to the plurality of driver chips of FIG. 3. FIG.

5 shows a panel with the subpixel repeating group of FIG. 2 in which the driver chip driving the panel is a four-phase chip in which any degradation of the image acts on the blue subpixel.

FIG. 6 shows a panel with a subpixel repeating group having two narrow columns of blue subpixels acting on a blue subpixel column substantially all or most of the image degradation.

Reference is now made in detail to embodiments and examples, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts.

FIG. 2 shows one panel that includes repeating subpixel grouping 202 as also described in the '353 application. As can be seen, the repeating subpixel grouping 202 is a group of eight subpixel repeats, including a checkerboard of red subpixels and blue subpixels between two rows of green subpixels of reduced area. do. If a standard 1 × 1 point reversal scheme is applied to a panel that includes such repeat grouping (as shown in FIG. 2), the characteristics described above with respect to the RGB striped panel (ie, in one row and / or in one column) It is clear that pixels of successive colors have different polarities) are now violated. This condition can cause a number of visual defects that appear on the panel, especially when certain image patterns are displayed. This observation also occurs with other novel subpixel repetition groupings, e.g., subpixel repetition grouping in FIG. 1 of the '352 application, and other repetitive groupings other than odd repeating subpixels across a row. Sometimes. Therefore, since a conventional RGB striped panel has three such repeating subpixels in its repeating group (i.e., R, G, B), these conventional panels do not necessarily violate the aforementioned conditions. However, the repeat grouping of FIG. 2 in this application has four (ie even) subpixels in its repeating group over one row (eg, R, G, B and G). It will be appreciated that the embodiments described herein are equally applicable to repeating groupings of all such even modules.

In order to avoid visual degradation and other problems in the AMLCD, not only the polarity of the data line transitions along each select line must be randomized, but also the polarity of the data line transitions must also be randomized for each color and position in the display. do. This randomization occurs naturally as an RGB triplet color subpixel in combination with a commonly used alternating column-inverted data driver system, when an even number of subpixels are used along a row line. More difficult to achieve.

In a design embodiment of one even module, the rows are formed from a combination of smaller green pixels and fewer but larger red and blue pixels. Normally, the polarity of the data line transitions is reversed on the alternating data lines, so that each pixel has a capacitive coupling almost equally to the data line on either side thereof. In this way, these capacitor-induced transient errors are approximately equal and opposite, and tend to cancel each other out in the pixels themselves. However, in this case, the polarities of the subpixels of the same color are the same, and image degradation may occur.

3 shows the pixel layout of an even module using 2x1 point inversion. Since the polarities of the same color pixels appear alternately, vertical image degradation is eliminated. Horizontal image degradation due to pixels of the same color is reduced by periodically changing the phase of the point inversion. Driver chips 301A-301D provide data to the display, and the driver outputs are driven with +,-, +,-, ... or-, +,-, +, .... Phasing of the polarity of the first four lines of the display is shown in FIG. 4. For example, the first column of chips 301B has phases of-,-, +, +, ....

In one embodiment, the subpixels bordered on either side by column lines driving the same polarity at any given time may experience reduced luminance for any given image signal. Thus, two goals are to reduce the number of subpixels affected and to reduce the image degradation effect of any particular subpixel that is inevitably affected. Some of the techniques in this and other related applications incorporated herein are designed to minimize both the number of subpixels and their effects on which an image has degraded.

One such technique is to select which pixels will degrade if degradation is unavoidable. In Fig. 3, the phase adjustment is designed so that the same polarity occurs on the circled blue subpixel 302. In this way, the polarity of subpixels of the same color along one row is reversed every two driver chips, which minimizes or eliminates horizontal image degradation. Periodically circled blue subpixels 302 are slightly darker (i.e. for LCDs that are normally black) or slightly lighter (i.e. for LCDs that are normally white) than other blue subpixels in the array, Since the eye is not so sensitive to blue luminance changes, the difference is substantially less visible.

Another technique is to add a correction signal to any affected subpixel. When it is known which subpixel will have image degradation, it becomes possible to add a correction signal to the image data signal. For example, most parasitic capacitances mentioned in this and other applications tend to lower the amount of luminance with respect to the affected sub-pixels. It is possible to determine the running characteristics of the subpixels for the panel through learning or heuristically (eg by testing a pattern for a particular panel) and to add the signal back to correct the degradation. In particular, if it is necessary to correct a small error on the circled pixel in FIG. 3, a correction term may be added to the data relating to the circled blue subpixel.

In another embodiment of the present invention, it is possible to design other driver chips that further reduce the effects of image degradation. As shown in Figure 5, for example, a four-phase clock is used for polarity inversion. By using such a pattern or a similar pattern, only the blue subpixels in the array have the same polarity deterioration. However, all pixels are equally degraded, making them substantially less visible to the human eye. If necessary, a correction signal can be applied to compensate for darker or lighter blue subpixels.

These drive waveforms can be generated with data driver chips provided in more complex power supply switching systems than those used in relatively simple alternating polarity inversion designs. In this two-stage data driver design, the analog signal is now generated as done in the first stage. However, the polarity-switching stage is driven with a unique cross-connection matrix in the second stage of the data driver to provide the more complex polarity inversion indicated.

Another embodiment of the technique described herein is to confine the image degradation effect onto a subset of blue subpixels across the panel in both the row direction and the column direction. For example, a "checkerboard" (ie, skip every other blue subpixel in one of the row and / or column directions) of the blue subpixels can be used to localize the image degradation signal. As mentioned above, the human eye whose sensitivity decreases in blue spatial resolution may be less aware of this error. It will be appreciated that other subsets of blue subpixels may also be selected to limit this error. Additionally, different driver chips with four or fewer phases may drive such panels.

FIG. 6 is yet another embodiment of a panel 600 consisting substantially of sub-pixel repeating groups 602 of even modules. In this case, group 602 consists of a checkerboard of red 104 subpixels and green 106 subpixels interspersed with two columns of blue 108 subpixels. As noted, it is possible (but not necessarily) to have blue subpixels that are smaller in width than red or green subpixels. As can be seen, the two neighboring columns of blue subpixels are of the blue subpixels that are suitably remapped to avoid sharing the correct data values, possibly through the same column driver via interconnect 604. Can share with TFT

In a standard column driver that performs 2x1 point inversion, it can be seen that the blue subpixel column 606 has the same polarity as the columns of the red and green subpixels just to its right. Although this can lead to image degradation (which can be compensated with some correction signal), such degradation is confined to dark colored (e.g. blue) subpixel columns, thus becoming less visible to the human eye. It is advantageous.

As described above, the present invention can be used to correct image deterioration in a liquid crystal display with divided blue subpixels.

Claims (36)

As a liquid crystal display, Substantially a panel comprising a subpixel repeating group comprising an even number of subpixels in a row, the subpixel repeating group further comprising a column of blue subpixels; A driver circuit for transmitting image data and a polarity signal to said panel, And any image degradation in the signal is localized on the column of blue subpixels. delete 2. The liquid crystal display of claim 1, wherein the subpixel repeating group comprises a checkerboard of red subpixels and green subpixels interspersed in substantially two columns of blue subpixels. 4. The liquid crystal display of claim 3, wherein two columns of blue subpixels share the same column driver. The liquid crystal display of claim 1, wherein the one or more sub pixels receive a correction signal. As a liquid crystal display, Substantially a panel comprising a subpixel repeating group comprising an even number of subpixels in a row, the group further comprising a column of blue subpixels; A driver circuit having at least two phases, said driver circuit sending image data and a polarity signal to said panel, said phase of said driver circuit being subject to any parasitic effect acting on any sub-pixel And a driver circuit selected to substantially act on said column of pixels. 7. The liquid crystal display of claim 6, wherein a correction signal is sent to one or more subpixels. As a method of correcting image degradation of a liquid crystal display, Disposing subpixels in a subpixel repeating group of a panel including an even number of subpixels in a row, the subpixel repeating group further comprising a column of blue subpixels; Correcting image degradation of the liquid crystal display, comprising providing a driver signal to the subpixels of the panel to transmit image data and polarity signals such that image degradation in the driver signal is localized on the column of blue subpixels. How to. delete 9. The liquid crystal display of claim 8, wherein disposing subpixels in the subpixel repeating group comprises forming a checkerboard of red and green subpixels interspersed with two columns of blue subpixels. How to correct image degradation. 12. The method of claim 10, wherein providing a driver signal comprises providing a signal to two columns of blue subpixels from a same column driver. 10. The method of claim 8, further comprising providing a correction signal to one or more subpixels of the group of subpixels. As a method of correcting image degradation of a liquid crystal display, Disposing subpixels in at least one subpixel repeating group of one panel, the subpixel repeating group comprising an even number of subpixels in one row and a column of at least one blue subpixel; Pixel arrangement; Providing a signal relating to image data and polarity data to a panel having a driver circuit having at least two phases selected such that the parasitic effect acting on any subpixel substantially affects a column of the at least one blue subpixel. To correct image degradation of the liquid crystal display. 15. The method of claim 13, further comprising providing a correction signal to one or more subpixels. As a liquid crystal display, Means for arranging subpixels in a subpixel repeating group of a panel comprising an even number of subpixels in a row, the subpixel repeating group further comprising a column of blue subpixels; Means for providing a driver signal to a subpixel in the panel to transmit image data and a polarity signal such that image degradation in the driver signal is localized on the column of blue subpixels. delete 16. The liquid crystal display of claim 15, wherein the means for placing subpixels in the subpixel repeating group comprises means for forming a checkerboard of red and green subpixels interspersed with two columns of blue subpixels. 18. The liquid crystal display of claim 17, wherein the means for providing a driver signal comprises means for providing a signal to two columns of blue subpixels from the same column driver. 16. The liquid crystal display of claim 15, further comprising means for providing a correction signal to one or more subpixels in the group of subpixels. As a liquid crystal display, Means for arranging subpixels in at least one subpixel repeating group in one panel, the subpixel repeating groups comprising an even number of subpixels in one row and a column of blue subpixels and; Means for providing a signal relating to image data and polar data to a panel having a driver circuit having at least two phases selected such that any parasitic effect acting on any subpixel substantially affects at least one column of blue subpixels. Including, a liquid crystal display. 21. The liquid crystal display of claim 20, further comprising means for providing a correction signal to one or more sub pixels. As a liquid crystal display, A panel substantially comprising a subpixel repeating group comprising an even number of subpixels in a first direction; A driver circuit for transmitting image data and a polarity signal to said panel, said driver circuit comprising a driver circuit for transmitting a correction signal to a plurality of subpixels having a substantially constant luminance error. 23. The liquid crystal display of claim 22, wherein the polarity signal is in dot inversion. The liquid crystal display of claim 23, wherein the polarity signal is a 1 × 1 point inversion scheme. The liquid crystal display of claim 23, wherein the polarity signal is a 1 × 2 point inversion scheme. 23. The liquid crystal display of claim 22, wherein the polarity signal is a four phase point inversion scheme. 23. The liquid crystal display of claim 22, wherein the plurality of subpixels having a substantially constant luminance error is a subpixel of blue color. A method of correcting image degradation in a panel in a liquid crystal display comprising a panel substantially comprising a subpixel repeating group comprising an even number of subpixels in a first direction, the method comprising: Determining a sub pixel having a substantially constant luminance error; Determining a correction signal for an image data signal to be applied to the subpixel; And And adding the correction signal for the image data signal to the sub-pixels. 29. The method of claim 28, wherein determining the subpixel further comprises measuring an error displayed by one subpixel with a test signal. 29. The method of claim 28, wherein determining the correction signal further comprises testing the correction signal experimentally and confirming that the correction signal substantially corrects an error. . As a liquid crystal display, A panel substantially comprising a subpixel repeating group comprising an even number of subpixels in a first direction; A plurality of two-phase driver chips that transmit image data and polarity signals to the panel, wherein the phase of the driver chips is substantially parasitic to the blue subpixels, with any parasitic effect acting on any subpixel at the boundary of the driver chip. And a phase driver chip selected to act as a. 32. The liquid crystal display according to claim 31, wherein a correction signal is transmitted to said even subpixels having parasitic effects. As a liquid crystal display, A panel substantially comprising a subpixel repeating group comprising an even number of subpixels in a first direction; A driver circuit having at least two phases and transmitting image data and a polarity signal to the panel, wherein the phase of the driver circuit is selected such that any parasitic effect acting on any subpixel substantially acts on the blue subpixel. And a driver circuit. 34. The liquid crystal display according to claim 33, wherein a correction signal is transmitted to the even subpixels having a parasitic effect. 34. The liquid crystal display of claim 33, wherein the subpixels are all blue subpixels of the panel. 34. The liquid crystal display of claim 33, wherein the subpixels are a subset of all blue subpixels of the panel.

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