JP2012042872A - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display capable of continuously preventing burn-in failure without requiring an increase in cost or size.SOLUTION: An electronic parting area 109 that is provided around a display area 108 is divided into two sections: a first electronic parting area 109a adjacent to the display area 108; and a second electronic parting area 109b arranged outside of the first electronic parting area 109a. The first electronic parting area 109a executes black display as original electronic parting operation, and the second electronic parting area 109b executes white or light color display as operation for sweeping impurity ions in liquid crystal.

Description

  The present invention relates to a liquid crystal display device.

  There are two types of liquid crystal display devices, a reflection type and a transmission type depending on how light is used, and a passive matrix method and an active matrix method depending on a pixel driving method. These have been actively commercialized in a wide range of fields as display panels, taking advantage of their characteristics.

  Hereinafter, the principle of the liquid crystal display device will be described with reference to the drawings. 7A and 7B are diagrams showing a conventional liquid crystal display device, where FIG. 7A is a top view and FIG. 7B is a cross-sectional view. The liquid crystal display device illustrated in FIG. 7 includes a glass substrate 101 serving as a light incident substrate, a glass substrate 102 serving as a pixel substrate, a liquid crystal 103 sealed between the glass substrates 101 and 102, and the glass substrates 101 and 102. The sealing material 104 to be bonded is generally configured. Note that a liquid crystal display device called LCOS using a semiconductor substrate as the pixel-side substrate 102 has also been commercialized.

  A display region 108 in which pixel electrodes 105 are formed in a matrix is provided on the glass substrate 102 on the pixel side, and a plurality of pixel electrodes 105 similar to the display region 108 are formed around the display region 108. An electronic parting area 109 is provided. The pixel electrode 105 is formed of a highly reflective metal such as aluminum in the reflective liquid crystal display device, and is formed of a transparent electrode film such as ITO in the transmissive liquid crystal display device. In general, a peripheral circuit including a signal line driving circuit, a selective scanning line driving circuit, a pad region, and the like is provided on the outer periphery of the electronic parting area 109, but these are omitted in FIG.

  A solid-shaped counter electrode 106 made of a transparent conductive film such as ITO is formed on the inner surface side of the light incident side glass substrate 101 at a position facing the pixel electrode 105, and the counter electrode 106 and the pixel electrode 105 form a liquid crystal. A voltage signal is applied to 103 and driving is performed. On the other hand, at the periphery of the outer surface (upper surface in the drawing) of the glass substrate 101 on the light incident side, a light shielding mask 107 (a region surrounded by a thick line in the drawing) covers the upper part of the outer peripheral circuit from the middle of the electron parting region 109. It is provided as follows. In FIG. 7A, although it is not possible to actually look under the light-shielding mask 107, the light-shielding mask 107 is seen through in order to make the explanation easy to understand.

  Here, each pixel electrode 105 constituting the electronic parting area 109 performs black or dark color display by applying a predetermined voltage and functions as an electronic parting surrounding the display area 108. As described above, the liquid crystal display device provides a pixel electrode 105 similar to that of the display area 108 around the display area 108 for displaying an image and performs a parting display. Can be made.

  However, a small amount of impurity ions are mixed in the liquid crystal 103, and a small amount of impurity ions are also attached to the glass substrates 101 and 102, the sealing material 104, the alignment film, and the like (not shown). In the case where the concentration of impurity ions is high, if the same display is continued for a long time, it is known that a display defect called burn-in occurs in which an afterimage of the previous screen remains even after the display is changed. .

  The most commonly used method for driving a liquid crystal display is line-sequential field inversion driving. In this driving, one row of pixel electrodes 105 is sequentially scanned from left to right, and this is performed line by line from top to bottom. In this case, the potential polarity of the counter electrode 106 is inverted for each field to prevent the deterioration of the liquid crystal.

  In this driving method, since the impurity ions move so as to be swept out by the movement of the liquid crystal molecules, they tend to accumulate on the end side in the scanning direction, and in particular, the vertical scanning is compared with the horizontal scanning. Since the frequency is low, the effect of sweeping out impurity ions is large, and burn-in defects tend to occur frequently at the lower end of the screen.

  Further, as a characteristic burn-in defect, when a white or near-light character display is partially performed near the lower end of the screen, burn-in tends to occur around the display. This is the area where the impurity ions that have been swept down at the bottom of the screen and accumulated in the blackout electronic close-up area are displaying white or light color characters whose liquid crystal molecules move significantly differently from the black display. It is thought that this is a phenomenon caused by being attracted to.

  As countermeasures against image sticking defects due to the ionic impurities as described above, inventions such as Patent Documents 1 to 3 have been made.

  Patent Document 1 describes an invention in which impurity ions are diffused throughout the panel by performing high temperature aging at the time of manufacture, thereby preventing poor image sticking.

  Patent Document 2 describes an invention in which impurity ions are collected outside the display region by performing voltage aging at the time of manufacture to prevent burn-in defects.

  Patent Document 3 describes an invention in which a dedicated electrode other than an image display electrode is provided and a DC voltage is applied thereto to adsorb impurity ions.

JP-A-2005-274649 JP 2006-11423 JP-A-6-280498

  However, in the inventions described in Patent Documents 1 and 2, even if it is effective for a short period after the start of use of the liquid crystal display device, the impurity ions return to the same movement as before by driving for a long time. End up. Further, in the invention described in Patent Document 3, there is a problem that the liquid crystal to which the DC voltage is applied gradually deteriorates, and providing a dedicated electrode for preventing a burn-in defect increases the cost of the product. Or lead to an increase in size.

  An object of the present invention is to provide a high-quality liquid crystal display device capable of continuously preventing a burn-in defect without causing an increase in cost or an increase in size.

  A first electrode substrate having a display region formed by a plurality of pixel electrodes arranged in a matrix; and a second electrode substrate having a counter electrode made of a transparent conductive film facing the first electrode substrate. In the liquid crystal display device in which liquid crystal is sealed between the first electrode substrate and the second electrode substrate, an electronic parting area surrounding the display area is provided around the display area. The area includes a first electronic parting area that is adjacent to and surrounds the display area, and a second electronic parting area that is disposed on the outer peripheral side of the first electronic parting area. One electron parting region functions as an electron parting of the display region, and the second electron parting region functions as a means for sweeping out impurity ions in the liquid crystal.

  The driving method for displaying an image in the display area is a line sequential driving system that sequentially scans the plurality of pixel electrodes arranged in a matrix in a row direction and a column direction, and the second electronic parting area is It is arranged on the terminal side of at least one of the row direction and the column direction.

  The second electronic parting area is formed by a plurality of electron parting pixel electrodes having the same form as the pixel electrode.

  The pixel electrode for electronic parting that forms the second electronic parting area is arranged as at least one pixel row along the outer periphery of the display area.

  The electronic parting pixel electrodes forming the second electronic parting area are arranged as three or more pixel columns along the outer periphery of the display area.

  The second electronic parting area is formed of a solid-shaped solid parting electrode for electronic parting.

  At least one of the first electrode substrate and the second electrode substrate is provided with a light shielding mask that covers the outside from the middle of the first electronic parting region.

  The first electronic parting area and the second electronic parting area are formed by a plurality of electron parting pixel electrodes in the same mode as the pixel electrode, and the first electronic parting area and the second electronic parting area. Is characterized in that the range is adjusted by shifting the position of the display region to at least one of the row direction and the column direction of the pixel electrode.

  According to the present invention, by using a part of the electron parting region as the ion sweeping means, it is possible to continuously prevent the image sticking failure without increasing the cost or increasing the size of the product.

Top view showing one embodiment of a liquid crystal display device according to the present invention (Example 1) FIG. 6 is a diagram schematically showing the movement of impurity ions, (a) a state in which black is displayed on the entire screen, (b) a state in which a white character is partially displayed at the lower end of the screen, and (c) a part of the electronic parting area The white is displayed on the screen (d) The white is displayed on the entire screen The top view which shows the modification of Example 1 A diagram showing the relationship between the number of lines in the electronic parting area that displays white and the number of burn-in defects FIG. 6 is a diagram for explaining the relationship between the number of rows in the first electronic parting region and the number of rows in the second electronic parting region; (a) two rows of the first electronic parting region on the lower side of the display area; The top view which shows the case where one line of electronic parting areas is provided, (b) The top view which shows the case where two lines of the first electronic parting area are provided on the lower side of the display area and two lines of the second electronic parting area are provided. FIG. 5 shows another embodiment of the liquid crystal display device according to the present invention, in which (a) a top view and (b) a cross-sectional view (Example 2). It is a figure which shows the conventional liquid crystal display device, (a) Top view, (b) Cross-sectional view

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a top view showing an embodiment of a liquid crystal display device according to the present invention. The liquid crystal display device shown in FIG. 1 has a basic configuration similar to that of the conventional liquid crystal display device shown in FIG. 7, and includes a display area 108 in which a plurality of pixel electrodes 105 are formed in a matrix, and a periphery of the display area 108. The display part 108 is provided with an electronic parting area 109 in which a plurality of pixel electrodes (electron parting pixel electrodes) 105 having the same form are formed. The electronic parting area 109 is disposed adjacent to the display area 108 so as to surround the periphery thereof, and is disposed adjacent to the first electronic parting area 109a and a part of the periphery thereof. And a second electronic parting area 109b. The second electronic parting area 109b is provided so as to divide part of the electronic parting area 109, and at least one of the pixel electrodes 105 formed on one side or a plurality of sides of the electronic parting area 109 from the outermost periphery. It consists of a row or one column (the bottom row is one row in FIG. 1). Further, a light-shielding mask 107 (a region surrounded by a thick line in the drawing) is provided so as to cover the outside of the first electronic parting region 109a from the middle. Note that, as in FIG. 7, the light-shielding mask 107 shows a transparent state for easy understanding.

  The first electronic parting area 109a adjacent to the periphery of the display area 108 functions as an electronic parting of the display area 108 by displaying in black or dark color, while the second electronic parting area 109b is white or By performing bright color display, it functions as a means for sweeping impurity ions in the liquid crystal.

  Here, the reason why the provision of the second parting region 109b will prevent image sticking due to impurity ions will be described with reference to FIG. 2A and 2B are diagrams schematically showing the movement of impurity ions, (a) a state in which black is displayed on the entire screen, (b) a state in which a white character is partially displayed at the lower end of the screen, and (c) an electronic parting out. This represents a state in which white is displayed in a part of the area, and (d) a state in which white is displayed on the entire screen.

  In FIG. 2A, 201 indicates impurity ions, 202 indicates the direction of the driving force acting on the impurity ions, and when black or dark color is displayed on the entire screen as shown in FIG. Driving forces act on the ions 201 in the direction indicated by the arrow 202 (scanning direction end side) by the sequential scanning movement of the liquid crystal molecules, and the impurity ions 201 accumulate in the electron parting area 109 at the lower end of the display area 108.

  In this state, when the white or light character 203 is partially displayed in the display area 108 as shown in FIG. 2B, the impurity ions 201 accumulated in the electronic parting area 109 cause the movement of the liquid crystal molecules. A white or light character 203 different from the black display is sucked around the area where the character 203 is displayed, the ion concentration around the character 203 is increased, and a burn-in defect is likely to occur.

  However, as shown in FIG. 2C, if white or light color is displayed in the second electron parting region 109b, a downward driving force in the figure acts on the impurity ions 201, and impurity ions around the character 203 are displayed. The concentration of 201 is suppressed, and the occurrence of burn-in failure is prevented.

  The burn-in defect as described above occurs when a white or light character display is partially performed in a specific area (here, near the lower end of the display area) in the display area 108. Even when similar white display is performed, such a burn-in defect is unlikely to occur when white display is performed on the entire screen as shown in FIG. This is considered to be because impurity ions are attracted uniformly to the entire row and dispersed without being concentrated in one place.

  In the case of line-sequential field inversion driving that is generally used in liquid crystal display devices, scanning in the vertical direction has a lower scanning frequency than left and right scanning. It tends to occur frequently at the lower end of the region. Therefore, in order to provide the second electronic parting area 109b for preventing such burn-in failure, it is most effective to provide it on the lower side of the display area 108 as shown in FIG. However, depending on the driving frequency and the type of impurity ions, burn-in defects may occur on the right side of the screen. In such a case, it is effective to provide the second electronic parting area 109b on the right side in addition to the lower side.

  Since the pixel electrode 105 constituting the electronic parting area 109 is the same as the pixel electrode 105 in the display area 108, different display can be performed for each pixel. Therefore, the second electronic parting area 109b for preventing burn-in failure can display not all of the matrix in white or light color, but can display only some pixels in the matrix in white or light color. is there. FIG. 3 is a top view showing a modification of the first embodiment. For example, as shown in FIG. 3, when impurity ions are accumulated in the lower right corner of the display area 108, each of the lower side and the right side of the electron parting area 109 is shown. You may provide the 2nd parting area 109b from the middle.

  Some liquid crystal display devices have a function capable of changing the driving direction from right to left or from bottom to top even with the same line-sequential field inversion driving. In this case, the second electronic It is effective to provide the parting area 109b on the upper side or the left side of the display area 108.

  The display color of the second electronic parting area 109b is effective if it is other than black, but the most effective one can be expected to be white or light color display in which the movement of liquid crystal molecules is significantly different from black display. .

  The greater the number of rows or columns of the second electronic parting region 109b, the greater the effect of sweeping impurity ions, so that the electronic parting effect, which is the original purpose of the electronic parting region 109, is not impaired. It is preferable to set as many as possible.

  FIG. 4 is a diagram showing the relationship between the number of lines in the electronic parting area for displaying white and the number of occurrences of burn-in defects. For 30 liquid crystal display devices, the second electronic parting area provided on the lower side of the display area is shown. The experimental result which investigated the relationship between the number of lines and the number of the liquid crystal display devices with which the burn-in defect generate | occur | produced is shown. From this, it can be seen that there is a clear correlation between the number of rows in the second electronic parting area and the occurrence ratio of burn-in defects. That is, as the number of lines in the second electronic parting area increases, the number of occurrences of burn-in defects decreases. When there are three or more lines, no burn-in defects occur. From this, it can be seen that it is particularly effective to prevent the image sticking failure by providing the second electronic parting area in three or more rows.

  FIG. 5 is a diagram for explaining the relationship between the number of lines in the first electronic parting area and the number of lines in the second electronic parting area. (A) Two lines of the first electronic parting area are provided on the lower side of the display area. The top view showing the case where one row of the second electronic parting area is provided, (b) The case where two lines of the first electronic parting area are provided on the lower side of the display area and two lines of the second electronic parting region are provided. It is a top view. As shown in FIG. 5A, the second that can be provided on the lower side of the display area 108 to prevent burn-in from the relationship between the number of pixels used in the display area 108 and the number of pixels used in the electronic parting area 109. When the number of rows of the electron parting region 109b is limited (here, one row), the effect of sweeping impurity ions cannot be obtained sufficiently, and a burn-in defect may occur.

  In such a case, as shown in FIG. 5B, display is performed by shifting the display area 108 upward by one line from the state of FIG. 5A, and the electronic parting area 109 is displayed in FIG. By changing the upper and lower 3 lines shown in FIG. 2 to the upper 2 lines and the lower 4 lines, and among the lower 4 lines of the electronic parting area 109, the 2nd line from the outermost periphery is used as the second electronic parting area 109b, thereby preventing a larger burn-in defect. An effect can be obtained. In this case, the light-shielding mask 107 is attached so as to be shifted upward by one line in accordance with the display area 108.

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In this way, when the panel is manufactured, the display area 108 is determined by adjusting the number of top and bottom or left and right sides of the electronic parting area 109, and the attachment position of the light shielding mask 107 is adjusted accordingly. It is possible to realize an effective countermeasure against burn-in without changing.

  In addition, when the number of rows in the second electronic parting area 109b is more than necessary and sufficient to prevent burn-in failure, only a few lines adjacent to the first electronic parting area 109a are displayed in white, and more than that. The outer rows may be displayed in black as in the first electronic parting area 109a.

  Note that the pixel electrode 105 that forms the second electron parting region 109b does not necessarily have the same shape and function as the pixel electrode 105 that forms the display region 108.

  As described above, the present invention in which a part of the electron parting region is used as a region for sweeping out impurity ions can perform a highly effective burn-in prevention measure without adding new dedicated parts or the like. is there.

  Hereinafter, another embodiment of the present invention will be described with reference to FIG. 6A and 6B are diagrams showing another embodiment of the liquid crystal display device according to the present invention. FIG. 6A is a front view, and FIG. 6B is a cross-sectional view. In the first embodiment, the second electron parting region 109b for sweeping ionic impurities is formed by the plurality of pixel electrodes 105, whereas in the second example, the second electron parting region 109b is formed. A solid electrode (solid electrode for electronic parting) 301 is formed. The solid electrode 301 is under the light-shielding mask 107 and has the same function as the pixel electrode 105 except for the shape. The liquid crystal can be driven by applying a uniform signal to the entire electrode. Here, if a predetermined signal is applied to the solid electrode 301 to display white or a light color close thereto, the same effect as in the first embodiment can be obtained.

  In this configuration, since a solid electrode having a simpler structure than that of the pixel electrode 105 is used, the design is simpler than that of the first embodiment.

  In FIG. 6, the solid electrode 301 is provided all around the display area 108. However, when the place where the burn-in defect occurs is limited to the lower side of the display area 108, for example, it is provided only on the lower side. Just do it.

  In addition, the white display operation of the second electronic parting area 109b is preferably performed continuously during a period in which an image is displayed in the display area 108, but is not limited thereto.

  Further, the first embodiment and the second embodiment can be implemented in combination. For example, in the configuration shown in FIG. 5B, one row on the outermost periphery of the second electronic parting area 109b is configured with a solid electrode. It is also possible to do so.

  In addition, embodiment of this invention is not limited to what was demonstrated above, As long as the summary of this invention is satisfy | filled, it can change arbitrarily.

101 Glass substrate (light incident side)
102 Glass substrate (pixel side)
103 Liquid crystal 104 Sealing material 105 Pixel electrode 106 Counter electrode 107 Light shielding mask 108 Display area 109 Electron parting area 109b First electron parting area 109b Second electron parting area 201 Impurity ions 202 Direction of driving force acting on impurity ions 203 Display character 301 Solid electrode

Claims (8)

A first electrode substrate having a display region formed by a plurality of pixel electrodes arranged in a matrix; and a second electrode substrate having a counter electrode made of a transparent conductive film facing the first electrode substrate. In a liquid crystal display device in which liquid crystal is sealed between the first electrode substrate and the second electrode substrate,
An electronic parting area surrounding the display area is provided around the display area.
The electronic parting area has a first electronic parting area adjacent to and surrounding the display area, and a second electronic parting area arranged on the outer peripheral side of the first electronic parting area. ,
The first electronic parting area functions as an electronic parting of the display area,
The liquid crystal display device, wherein the second electronic parting region functions as means for sweeping impurity ions in the liquid crystal.   The driving method for displaying an image in the display area is a line sequential driving system that sequentially scans the plurality of pixel electrodes arranged in a matrix in a row direction and a column direction, and the second electronic parting area is The liquid crystal display device according to claim 1, wherein the liquid crystal display device is disposed on a terminal end side of at least one of the row direction and the column direction.   3. The liquid crystal display device according to claim 1, wherein the second electronic parting area is formed by a plurality of electron parting pixel electrodes having the same mode as the pixel electrode.   4. The liquid crystal display device according to claim 3, wherein the electron parting pixel electrode forming the second electronic parting region is arranged as at least one pixel column along an outer periphery of the display region. 5. .   5. The liquid crystal display device according to claim 4, wherein the electron parting pixel electrodes forming the second electronic parting region are arranged as three or more pixel columns along an outer periphery of the display region. .   3. The liquid crystal display device according to claim 1, wherein the second electronic parting region is formed by a solid-shaped electron parting solid electrode.   The light-shielding mask which covers the outer side from the middle of the said 1st electronic parting-out area | region is provided in at least any one among the said 1st electrode substrate and the said 2nd electrode substrate. The liquid crystal display device according to any one of 6.   The first electronic parting area and the second electronic parting area are formed by a plurality of electron parting pixel electrodes in the same mode as the pixel electrode, and the first electronic parting area and the second electronic parting area. 8. The liquid crystal according to claim 1, wherein the liquid crystal is adjusted by shifting a position of the display region in at least one of a row direction and a column direction of the pixel electrode. Display device.

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