Liquid crystal display device
In the case that a first scanning line having a smaller number of pixels to be driven than that of a second scanning line in a display device having a heteromorphic display region, capacitance is added to an extended scanning line in which the first scanning line extends to an outside of the display region. A large difference in RC delay between scanning lines generated by the number of pixels to be driven can be compensated for by adding the capacitance, so that luminance unevenness can be prevented to contribute to improvement of display quality.
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This application is a reissue application under 35 U.S.C. § 251 of U.S. patent application Ser. No. 16/147,903, now U.S. Pat. No. 10,656,489, filed on Oct. 1, 2018, which claims benefit of priority to Japanese Patent Application No. 2017-196993 filed Oct. 10, 2017, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION Field of the InventionThe present invention relates to a panel used in a display device, particularly to a liquid crystal display panel including a heteromorphic display region that is not rectangular.
Description of the Background ArtIn the liquid crystal display device, there is an increasing demand for a heteromorphic panel in which the shape of the panel is not rectangular particularly in on-vehicle use. Various shapes such as a circular or semicircular shape, a concave or convex shape, a polygonal shape, and a shape having a notch exist as the shape of the heteromorphic panel, and the display region also has a heteromorphic shape that is not rectangular. (Japanese Unexamined Patent Application Publication No. 2002-14366)
One of features of the heteromorphic panel is that the number of pixels to be driven per scanning line or signal line is different among wirings. When the number of pixels to be driven is different among the wirings, capacitance or resistance is different in each wiring, and a difference in signal delay amount is generated. For the delay in the signal line, a bad influence of the delay on the display quality can be prevented by optimizing charging design of a thin film transistor (TFT) such as charging capacity and a charging time.
On the other hand, the signal delay of the scanning line influences a recharging characteristic generated in changing the scanning signal from ON to OFF, and therefore a pixel potential is influenced. It is also difficult to prevent this influence by a measure such as the charging design and avoidance by timing. Unevenness of the pixel potential caused by the difference in delay amount of the scanning signal causes luminance unevenness to degrade display quality.
Various techniques are known in order to improve the display quality. For example, in a panel having a circular or polygonal shape, there has been a technique of correcting the difference of each wiring by changing the area of the intersection of the scanning line and the signal line to adjusting the capacitance between pixels of the scanning line having a small number of driving pixels and pixels of other scanning lines. (Japanese Unexamined Patent Application Publication. No. 2006-276360) A method in which correction is similarly performed by appropriately crossing the signal line and the scanning line outside the display region has also been proposed. (Japanese Unexamined Patent Application Publication No. 2009-069768 and International Publication No. 2008-62575)
In designing the panel shape and arrangement of a driving circuit, layout is hardly performed in some cases even when the conventional technique is adopted. Specifically, the layout is hardly performed when the display panel has an L-shape or a concave shape. As used herein, the concave shape means a shape partially having a recessed region which does not contribute to the display in the display region. Details will be described later.
In the case that the display panel has the L-shape or the concave shape, the number of pixel arrays changes discontinuously and largely unlike circular shape, and the influence on appearance is larger because a characteristic changes largely with a notch as a boundary. In the case that the display panel has the concave shape having the notch, it is difficult to cross all the signal lines and the scanning lines in the region between the driving circuit and the display.
SUMMARYAn object of the present invention is to uniformize the display characteristic in a plane by reducing the difference in delay amount of the scanning signal, and to prevent display defects such as the luminance unevenness and a flicker, even in a panel having a notch and having a shape in which the number of pixels in each wiring varies discontinuously and largely.
A liquid crystal display device according to one aspect of the present invention is a liquid crystal display device including an array substrate and a counter substrate opposed to the array substrate, the array substrate and counter substrate being bonded to each other so as to enclose liquid crystal. The array substrate includes a display region and a peripheral region. A scanning line and a signal line that crosses the scanning line with an insulating film interposed therebetween extend from the display region to the peripheral region. The scanning line and the signal line cross each other in the display region define a pixel. The scanning line includes a first scanning line and a second scanning line. The first scanning line is smaller than the second scanning line in a number of the pixels to be driven. Capacitance is added to at least the first scanning line in the peripheral region.
In the liquid crystal display device of the present invention, the capacitance is added to at least the first scanning line in the peripheral region. Therefore, the display characteristic can be uniformized within the plane, and the display defects such as the luminance unevenness and the flicker can be prevented, even in the panel having the shape in which the number of pixels in each wiring discontinuously and largely.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
Referring to
In the pixel P, a pixel electrode PE is formed, and a pixel transistor TFT which is a switching element and is connected to the pixel electrode PE is formed. In other words, the display region 101 is configured by the plurality of pixels P, and the pixel electrode PE and the thin film transistor TFT are formed in each pixel P. A counter electrode or a common electrode (not illustrated) opposed to the pixel electrode PE is also formed, and liquid crystal molecules in the liquid crystal layer are driven by an electric field between the pixel electrode PE and the counter electrode to contribute to display.
A connection relationship between the wiring and the driving circuit will be described. A plurality of scanning lines XA, XB that are the scanning lines X extend from the display region 101 to the peripheral region 102, and are connected to a scanning line driving circuit 2A or a scanning line driving circuit 2B through a terminal (not illustrated). In
The plurality of signal lines Y intersect the plurality of scanning lines XA, XB in the display region 101, extend to the peripheral region 102, and are connected to a signal line driving circuit 3 through a terminal (not illustrated). The plurality of signal lines Y and the plurality of scanning lines X intersect each other with an insulating film (not illustrated) interposed therebetween. A display signal potential contributing to the display is supplied from the signal line driving circuit 3 to the plurality of signal lines Y. Similarly, a scanning signal potential is supplied from the scanning line driving circuit 2A or the scanning line driving circuit 2B to the plurality of scanning lines XA, XB.
The scanning line may be formed to intersect an inside of the display region 101, or may be formed to be divided into a left half and a right half in
The display region 101 has a shape in which an upper side is partially recessed in
In general, display means other than the liquid crystal display device in
The first scanning lines XAW1, XAW2 are compared to the second scanning line XA, in the region where the recessed region U does not exist in the display region 101. Lengths of the first scanning lines XAW1, XAW2 are shorter than a length of the second scanning line XA.
For this reason, the second scanning lines larger than the first scanning lines XAW1, XAW2 in the number of the pixels P in which the wiring intersects and in the number of the pixels P to be driven by the wiring. Consequently, a difference in wiring resistance or capacitance is generated. Additionally, difference in wiring resistance or capacitance is maximized at a boundary between the presence and absence of the projections WA, WB and generated discontinuously, so that the luminance unevenness such that the luminance varies largely is generated at the boundary between the projections WA, WB, specifically, between upper and lower portions of the region where the notch edge side U1 is extended to the left and right.
In the first preferred embodiment, as illustrated in
The capacitors C1, C2 are used to compensate for a difference in RC delay caused by the difference of the wiring length or the number of pixels between the first scanning lines XAW1, XAW2 and the second scanning line XA, and each capacitor is set to a value suitable for the compensation. According to this configuration, the unevenness generated between the upper and lower portions of the region where the notch edge side U1 is extended to the right and left can be prevented, so that the degradation of the display quality can be prevented even in the case that a notch shape having the high design effect is adopted as illustrated in
As to the form of the capacitors C1, C2, a capacitor electrode (not illustrated) having a region opposed to the extended scanning line may be formed with a film made of an insulating material such as SiO2 (silicon oxide) or SiN (silicon nitride) interposed therebetween. The capacitor electrode may be formed using the same material in the same layer as the signal line Y. Further, a common electrode or a pixel electrode layer, which is usually formed on the array substrate, may be used as the capacitance electrode.
In the case that the edge sides W1, W2 of the projections WA, WB are formed so as to be obliquely crossing the first scanning lines XAW, XBW as illustrated in
In the case that the influence of the number of pixels in the display region 101 is larger than the influence of the wiring routing in the peripheral region 102, it can be said that the scanning line XAW1 having the larger number of pixels P to be driven in the display region 101 and the scanning line XAW2 having the smaller number of pixels P to be driven are illustrated among the first scanning lines. In any case, a value of capacitance C may be changed according to magnitude of the value. In the first scanning lines XAW, XBW, the capacitance may be decreased with increasing number of pixels P to be driven. In that case, the capacitance of C1 may be smaller than the capacitance of C2 in
As described above, the capacitance value may be decreased with increasing lengths of the first scanning lines XAW1, XAW2. For example, an area of the pattern forming the capacitance may be reduced. Not only the unevenness generated in the vicinity of the projection but also the display quality in the right and left projections WA, WB can be improved by the combination of this mode.
In the first preferred embodiment, the first scanning lines XAW1, XAW2 in the projection WA have been described. However, the same holds true for the first scanning lines XBW1, XBW2 in the projection WB.
Second Preferred EmbodimentIn the description of the first preferred embodiment, the scanning lines XAW, XBW divided by the projections WA, WB are drawn to the outside of the display region 101 to connect the capacitors. The means for compensating for the influence of the wiring length between the first scanning lines XAW, XBW and the second scanning lines XA, XB is not limited to the first preferred embodiment. For example, the influence may be compensated by changing the length or width of the extended scanning line that is the scanning line extended to the outside of the display region 101.
Hereinafter, two scanning lines XAW1, XAW2 will be described as an example of the first scanning line, and the same holds true for a relationship between the scanning line XB and the first scanning line. In the second preferred embodiment, a bent portion V is formed on the first scanning line outside the display region 101, namely, the extended scanning line. On the other hand, the bent portion V is not provided in the second scanning line. With this configuration, the substantial length of the first scanning line is extended, so that the difference in length between the first scanning line XAW1, XAW2 and the second scanning line XA is compensated for. Consequently, the degradation of the display quality can be prevented similarly to the first preferred embodiment.
In
Although not illustrated, the width of the extended scanning line may be changed. In the second preferred embodiment, the compensation can be performed in a wider range by appropriately combining the method for substantially lengthening the wiring by providing the bent portion V in the extended scanning line and the method for changing the width of the extended scanning line.
Third Preferred EmbodimentThe method for lengthening the extended scanning line has been described in the second preferred embodiment. However, merely lengthening the extended scanning line requires an extra space outside the display region 101, which increases the non-display portion of the liquid crystal display device. In the third preferred embodiment, as illustrated in
In this way, it is not necessary to add the extra space by routing the extended scanning line in the region that is secured as the frame of the liquid crystal display device, which contributes to the narrow frame of the liquid crystal display device.
Fourth Preferred EmbodimentThe mode contributing to the narrow frame of the liquid crystal display device has been described in the third preferred embodiment. In a fourth preferred embodiment, a different mode will be described with reference to
The scanning lines XAW1, XAW2 that are first scanning lines are illustrated in
As illustrated in
In this configuration, the first scanning lines XAW1, XAW2 are located in the same layer, while the extended scanning line XAW1E of the first scanning line XAW1 and the extended scanning line XAW2EE of the first scanning line XAW2 are formed in different layers with the insulating film PSV interposed therebetween.
In the fourth preferred embodiment, as illustrated in
The display region includes the notch in the first to fourth preferred embodiments.
These may appropriately be combined. Although the effect is restricted as compared with the case including the notch, the preferred embodiment of the present invention can be applied even to the display region such as a triangle or a trapezoid, which does not include the notch.
In the preferred embodiments, the scanning line X is separated on the left and right by the projection. However, the present invention can also be applied to a configuration in which the scanning line X is not separated. However, in this case, an extent of compensation becomes larger, so that the range of the compensation and an occupied area of the capacitance or the extended scanning line can be narrowed in the mode in which the scanning line is divided on the left and right as described in the preferred embodiments.
Further, the present invention cart be applied to not only the liquid crystal display device but also a display device in which unevenness of electric resistance of the wiring and capacitance becomes problematic, for example, an organic EL display device or a display device in which an electrophoretic principle is used.
While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.
Claims
1. A liquid crystal display device comprising:
- an array substrate; and
- a counter substrate opposed to the array substrate, the array substrate and the counter substrate being bonded to each other so as to enclose liquid crystal,
- wherein
- the array substrate includes a display region and a peripheral region,
- a plurality of scanning lines and a plurality of signal lines that cross the scanning lines with an insulating film interposed therebetween extend from the display region to the peripheral region,
- the scanning lines and the signal lines cross each other in the display region to define respective pixels,
- the scanning lines include a plurality of first scanning lines and a plurality of second scanning lines,
- each of the first scanning lines drives a smaller number of the pixels than a number of the pixels driven by any of the second scanning lines,
- a first capacitance is added to a first one of the first scanning lines in the peripheral region, and a second capacitance is added to a second one of the first scanning lines in the peripheral region, and
- the array substrate includes two opposing edge sides, each extending obliquely with respect to an extending direction of the first scanning lines to form a recessed region that increases in width in a direction away from the second scanning lines toward an outer edge of the array substrate, such that the first one of the first scanning lines closest to the second scanning lines is longer than the second one of the first scanning lines further away from the second scanning lines, and a value of the first capacitance is smaller than a value of the second capacitance.
2. The liquid crystal display device according to claim 1, wherein
- the display region includes the recessed region and a projection on a side identical to the recessed region,
- the first scanning lines are disposed in the display region of the projection, and
- the second scanning lines are disposed in the display region other than the projection.
3. The liquid crystal display device according to claim 2, wherein the value of the first capacitance increases with decreasing number of the pixels to be driven in the first one of the first scanning lines, and the value of the second capacitance increases with decreasing number of the pixels to be driven in the second one of the first scanning lines.
4. The display device according to claim 2, wherein
- one of the first scanning lines further includes an extended scanning line that is extended to an outside the display region, and
- the extended scanning line is lengthened with decreasing number of the pixels to be driven in the one of the first scanning lines.
5. The liquid crystal display device according to claim 2, wherein
- one of the first scanning lines further includes an extended scanning line that is extended to an outside the display region, and
- the extended scanning line is extended to at least one of a notch upper frame that is a vicinity of an edge side of the recessed region and a non-notched upper frame that is a vicinity of an edge side of the projection.
6. The liquid crystal display device according to claim 2, wherein
- one of the first scanning lines includes: an extended scanning line that is extended to an outside the display region; and a conversion portion in which at least one of the extended scanning lines is converted into a different layer with an insulating film interposed therebetween,
- the extended scanning line converted into the different layer includes a region overlapping another extended scanning line, which is not converted, with the insulating film interposed therebetween.
7. The liquid crystal display device according to claim 1, wherein
- the second scanning lines are not directly connected to the first scanning lines.
8. The liquid crystal display device according to claim 1, wherein
- the second scanning lines extend further into the display region than all of the first scanning lines in plan view.
9. An array substrate, comprising:
- a display region;
- a peripheral region; and
- a plurality of scanning lines and a plurality of signal lines extending from the display region to the peripheral region, wherein
- the plurality of scanning lines and the plurality of signal lines cross each other in the display region to define respective pixels,
- the plurality of scanning lines includes a plurality of first scanning lines and a plurality of second scanning lines,
- each of the plurality of first scanning lines drives a smaller number of the pixels than a number of the pixels driven by any of the plurality of second scanning lines,
- the plurality of first scanning lines includes a first one of the first scanning lines and a second one of the first scanning lines, and the plurality of second scanning lines includes a first one of the second scanning lines,
- the shortest distance between the first one of the first scanning lines and the first one of the second scanning lines is less than the shortest distance between the second one of the first scanning lines and the first one of the second scanning lines,
- a first capacitance is formed by the first one of the first scanning lines in the peripheral region, and a second capacitance is formed by the second one of the first scanning lines in the peripheral region, and
- the array substrate includes two opposing edge sides, each extending obliquely with respect to an extending direction of the plurality of first scanning lines to form at least a recessed region relative to an outline of the array substrate that increases in width in a direction away from the plurality of second scanning lines toward an outer edge of the array substrate, such that the first one of the first scanning lines closest to the plurality of second scanning lines is longer than the second one of the first scanning lines farther away from the plurality of second scanning lines, and a value of the first capacitance is smaller than a value of the second capacitance.
10. The array substrate according to claim 9, wherein
- the display region includes a rectangle region and a projection region,
- the plurality of first scanning lines are disposed in the projection region, and
- the plurality of second scanning lines are disposed in the rectangle region.
11. The array substrate according to claim 9, wherein
- a number of the pixels driven by the first one of the first scanning lines is larger than a number of the pixels driven by the second one of the first scanning lines.
12. The array substrate according to claim 9, wherein
- the first capacitance is formed with the first one of the first scanning lines and a first capacitive electrode that is in the same layer as the plurality of signal lines, and
- the second capacitance is formed with the second one of the first scanning lines and a second capacitive electrode that is in the same layer as the plurality of signal lines.
13. The array substrate according to claim 9, further comprising:
- a common electrode, wherein
- the first capacitance is formed with the first one of the first scanning lines and a first capacitive electrode that is in the same layer as the common electrode, and
- the second capacitance is formed with the second one of the first scanning lines and a second capacitive electrode that is in the same layer as the common electrode.
14. The array substrate according to claim 9, further comprising:
- a pixel electrode, wherein
- the first capacitance is formed with the first one of the first scanning lines and a first capacitive electrode that is in the same layer as the pixel electrode, and
- the second capacitance is formed with the second one of the first scanning lines and a second capacitive electrode that is in the same layer as the pixel electrode.
15. The array substrate according to claim 9, wherein
- the display region includes a rectangle region and a projection region, and
- the plurality of first scanning lines in the peripheral region includes portions extending along an edge of the projection region.
16. The array substrate according to claim 9, wherein
- the first one of the first scanning lines is formed in a first layer,
- the second one of the first scanning lines is formed in the first layer and in a second layer that is different from the first layer, with an insulating film interposed therebetween,
- the second one of the first scanning lines includes a conversion portion at which the second one of the first scanning lines in the first layer is converted into the second one of the first scanning lines in the second layer, and
- the second one of the first scanning lines in the second layer at least partially overlaps with the first one of the first scanning lines.
17. The array substrate according to claim 9, wherein
- the display region is narrower in width in a direction away from the plurality of second scanning lines toward an outer edge of the array substrate.
18. The array substrate according to claim 17, wherein
- the first one of the first scanning lines in the display region is longer than the second one of the first scanning lines in the display region, and
- the first one of the first scanning lines in the peripheral region is shorter than the second one of the first scanning lines in the peripheral region.
19. The array substrate according to claim 9, wherein
- the outline of the array substrate is rectangular.
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Type: Grant
Filed: Apr 28, 2022
Date of Patent: Oct 1, 2024
Assignee: Trivale Technologies (Santa Clara, CA)
Inventor: Shohei Yasuda (Tokyo)
Primary Examiner: Ling X Xu
Application Number: 17/732,458
International Classification: G02F 1/1362 (20060101); G02F 1/1368 (20060101);