JP5285502B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a technique for improving display quality in a liquid crystal display device.

  Japanese Patent Application Laid-Open No. 63-92927 (Patent Document 1) has a portion for performing light-shielding printing on the back surface of a liquid crystal display element, forming a white pattern at the same time, and constantly displaying the portion by parallel alignment processing. In the transmissive negative liquid crystal display element, a liquid crystal display element is disclosed in which a part of the segment wiring intersects with the common wiring in the parallel alignment treatment region. According to the liquid crystal display element of this conventional example, the common wiring that affects the frequency characteristics of the liquid crystal display element can be made thick, so that the wiring resistance can be lowered and the lighting at the intersection is not perceived by the eyes. And a high-quality liquid crystal display element is realized.

  By the way, the above-described prior art is based on a liquid crystal display element having a specific structure, and is considered to lack versatility from the viewpoint of application to various liquid crystal display elements. For example, if it is necessary to place the intersection of the segment wiring and the common wiring in the effective display area due to design restrictions, the lighting state at the wiring intersection is visually recognized in the above-described conventional technology. It is difficult to make it difficult. On the other hand, it is also conceivable to make the lighting state in the crossing portion inconspicuous by reducing the line width of the wiring in the crossing portion of the wiring. However, when the line width of the wiring is narrowed, another inconvenience of increasing the wiring resistance occurs.

JP-A-63-92927

  A specific aspect of the present invention is to provide a liquid crystal display device that can make it difficult to visually recognize a lighting state at an intersection of wirings without increasing wiring resistance so much.

A liquid crystal display device according to one aspect of the present invention includes a first substrate having a first electrode and a first wiring connected to the first electrode on one surface, a second electrode and a second electrode connected to the second electrode. A second substrate having two wirings on one surface, and a liquid crystal layer sandwiched between the one surface of the first substrate and the one surface of the second substrate, the first wiring and the first wiring One or more first openings are provided in the first wiring in an intersecting region where two wirings overlap in plan view, and the width of the first opening is set to 100 μm or more .

According to the liquid crystal display device described above, the intersection region of the first wiring and the second wiring is divided into a plurality of portions with the first opening interposed therebetween, so that compared with a case where such a first opening is not provided. The area of the intersection between the first wiring and the second wiring can be further reduced. Further, it is not necessary to particularly narrow the line width of each wiring, and the wiring resistance is not increased so much by providing the first opening as will be described in detail later. Therefore, it is possible to provide a liquid crystal display device that can make it difficult to visually recognize the lighting state at the intersection of the wirings without increasing the wiring resistance so much. This is particularly effective in a negative display type liquid crystal display device. In addition, since the distance between the intersections of the first wiring and the second wiring can be separated by 100 μm or more, the intersection of the first wiring and the second wiring can be determined by taking into account the characteristics of human eyes described later. It can be made more difficult to see.

  In the above liquid crystal display device, preferably, the line width of the first wiring and the width of the first opening are set so that the wiring widths on both sides of the first opening with respect to the first opening are 100 μm or less, respectively. The width is set.

  Considering that the minimum resolution of human eyes is generally about 100 μm, the intersection between the first wiring and the second wiring can be more visually recognized by setting the line width and the opening width as described above. Can be difficult.

  Note that when the liquid crystal display device (liquid crystal display element) performs negative display and has a particularly high contrast, transmitted light is observed even when the line width of the intersection is about 100 μm. There is a case. In this case, by limiting the line width of the intersecting portion to about 50 μm or less, the intersecting portion can be made less visible.

  As an example of the liquid crystal display element having a high contrast described above, a liquid crystal display sandwiched between crossed Nicols polarizing plates after compensating the optical rotation and birefringence of the liquid crystal layer among various types with an optical compensator. Examples thereof include an element and a negative display type vertical alignment mode liquid crystal display element in which optical rotation and birefringence hardly occur when not turned on.

In the manufacturing process of a liquid crystal display device of segment type In general, it is often used a patterning process not very accurate. In this case, it is not preferable to form a wiring portion having an extremely narrow line width because disconnection may occur, or an abnormal increase in sheet resistance accompanying change in electrode material due to, for example, a heat treatment process may occur. In order to avoid this inconvenience, it is preferable to form the wiring portion so that the line width is not less than about 30 μm.

  In the above liquid crystal display device, it is also preferable that one or more second openings are provided in the second wiring in the intersection region.

  As a result, the intersections between the first wiring and the second wiring can be divided into a larger number, so that the visibility at the intersections can be further reduced.

  In the above liquid crystal display device, the line width of the second wiring and the width of the second opening are set such that the wiring widths on both sides of the second opening of the second wiring are 100 μm or less, respectively. It is also preferable that it is set.

  Considering the characteristics of human eyes, setting the line width and the opening width as described above makes it possible to make the intersection between the first wiring and the second wiring less visible.

  In the above liquid crystal display device, it is also preferable that the width of the second opening is set to 100 μm or more.

  Thereby, since the distance between the intersections of the first wiring and the second wiring can be separated by 100 μm or more, the intersection of the first wiring and the second wiring can be taken into consideration when the characteristics of the human eye are taken into consideration. Can be made less visible.

FIG. 1 is a plan view schematically showing a liquid crystal display device according to an embodiment. FIG. 2 is a partial cross-sectional view showing a cross-sectional structure corresponding to the line II-II shown in FIG. FIG. 3 is an enlarged view of a part of the terminal portion shown in FIG. FIG. 4 is an enlarged plan view showing the intersection region b shown in FIG. FIG. 5 is a schematic plan view showing a structural example in an intersection region between the first wiring and the second wiring. FIG. 6 is a schematic plan view showing a structural example in an intersection region between the first wiring and the second wiring. FIG. 7 is a diagram for explaining a simulation model for verifying the wiring resistance value. FIG. 8 is a diagram for explaining a modified embodiment in which a plurality of openings are provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view schematically showing a liquid crystal display device according to an embodiment. A liquid crystal display device 1 according to this embodiment shown in FIG. 1 includes a display unit 2 and a terminal unit 3 having a plurality of external connection terminals for supplying a drive signal to the display unit 2 from the outside. In the present embodiment, a segment type display unit is considered as the display unit 2. The liquid crystal display device 1 is used as an information display unit in various electronic devices such as in-vehicle and consumer devices.

  FIG. 2 is a partial cross-sectional view showing a cross-sectional structure corresponding to the line II-II shown in FIG. As shown in FIG. 2, the liquid crystal display device 1 of the present embodiment includes a first substrate 11 and a second substrate 15 that are arranged to face each other, and a liquid crystal layer 14 that is arranged between the two substrates. A first polarizing plate 21 is disposed outside the first substrate 11, and a second polarizing plate 22 is disposed outside the second substrate 15. Hereinafter, the structure of the liquid crystal display device 1 will be described in more detail. Note that illustration and description of members such as a sealing material for sealing the periphery of the liquid crystal layer 14 are omitted.

  The first substrate (COM side substrate) 11 is a transparent substrate such as a glass substrate or a plastic substrate. Similar to the first substrate 11, the second substrate (SEG side substrate) 15 is a transparent substrate such as a glass substrate or a plastic substrate. As illustrated, the first substrate 11 and the second substrate 15 are bonded to each other with a predetermined gap (for example, several μm) so that the first electrode 12 and the second electrode 16 face each other.

  The first electrode (COM electrode) 12 is provided on one surface side of the first substrate 11. The first electrode 12 is configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example. A first wiring is connected to the first electrode 12 as described later.

  The alignment film 13 is provided on one surface side of the first substrate 11 so as to cover the first electrode 12. The alignment film 13 regulates the alignment state of the liquid crystal layer 14 in the initial state (when no voltage is applied).

  The second electrode (SEG electrode) 16 is provided on one surface side of the second substrate 15. Similar to the first electrode 12, the second electrode 16 is configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example. A second wiring is connected to the second electrode 16 as will be described later.

  The alignment film 17 is provided on one surface side of the second substrate 15 so as to cover the second electrode 16. This alignment film 17 regulates the alignment state in the initial state of the liquid crystal layer 14 in the same manner as the alignment film 13 described above.

  The liquid crystal layer 14 is provided between the first electrode 12 of the first substrate 11 and the second electrode 16 of the second substrate 15. In the present embodiment, the liquid crystal layer 14 is configured using a liquid crystal material having a positive dielectric anisotropy Δε (Δε> 0). The thick line shown in the liquid crystal layer 14 schematically shows the orientation direction of the liquid crystal molecules in the initial state where no voltage is applied to the liquid crystal layer 14. The liquid crystal layer 14 of this embodiment is set to a TN alignment mode in which the alignment direction of liquid crystal molecules when no voltage is applied is twisted by approximately 90 ° from the first substrate 11 side toward the second substrate 15 side.

  FIG. 3 is an enlarged view of a part of the terminal portion 3 shown in FIG. 1 (portion indicated by symbol “a” in the drawing). As shown in FIG. 3, the first substrate 11 has a first wiring 31 connected to the first electrode 12 on one surface. The second substrate 15 has a second wiring 32 connected to the second electrode 16 on one surface. The first wiring 31 and the second wiring 32 are basically laid out so as not to overlap each other. This is to avoid an unnecessary voltage being applied to the liquid crystal layer 14 and an unintended display (lighting state). However, it is impossible to avoid the intersection of the first wiring 31 and the second wiring 32, and it is difficult to arrange the intersection in the seal area 4 or the like. There is a case where it must be placed in. For example, in the liquid crystal display device 1 of the present embodiment, the first wiring 31 and the second wiring 32 intersect with each other in a plan view inside the display unit 2 as indicated by a symbol b in FIG. Next, the structure of the intersection region b will be described in more detail.

  FIG. 4 is an enlarged plan view showing the intersection region b shown in FIG. As shown in FIG. 4, in the liquid crystal display device 1 of the present embodiment, the first opening 31 (slit) 33 is formed in the first wiring 31 in the intersection region b where the first wiring 31 and the second wiring 32 overlap in plan view. Is provided. The line width L1 at the portion where the first opening 33 of the first wiring 31 is provided is, for example, 100 μm. The width L4 of the first opening 33 is, for example, 20 μm. In this example, the wiring widths L2 and L3 on both sides of the first opening 33 of the first wiring 31 are 40 μm. In this example, the wiring widths L2 and L3 are made equal, but they may be different.

  Based on FIG. 4, the mutual relationship between the sizes of the first wiring 31, the second wiring 32, and the first opening 33 will be described qualitatively. The line width L1 of the first wiring 31 and the width L2 of the first opening 33 are set such that the wiring widths L2 and L3 on both sides of the first opening 31 across the first opening 31 are 100 μm or less, respectively. Is preferred. This is based on the reason that the resolution of the human eye is generally about 100 μm. According to this, by setting the wiring widths L2 and L3 to 100 μm or less respectively, the intersections 34 and 35 in the intersection region b each have at least one side of 100 μm or less. Can be made inconspicuous, i.e., less visible to the human eye. Further, by setting the line width L5 of the second wiring 32 in the intersection region b to 100 μm or less, the other one side of each intersection 34 and 35 can be set to 100 μm or less. Becomes an area smaller than 100 μm square. Thereby, the lighting state in each of the intersections 34 and 35 can be made more inconspicuous. Note that the preferable conditions for the mutual relationship between the first wiring 31, the second wiring 32, and the first opening 33 described here are common to the second opening 36 described later.

  FIG. 5 is a schematic plan view showing a structural example in an intersection region between the first wiring and the second wiring. FIG. 5A is a diagram showing the structure shown in FIG. 4 again, and shows an example in which an opening is provided only in the first wiring 31 on the first substrate 11 side. By providing the first opening 33 in the first wiring 31 as in this structural example, the intersection region between the first wiring 31 and the second wiring 32 can be divided into two intersections 34 and 35. In the comparative example in which the opening shown in FIG. 5D is not provided, there is one intersection 41 in the intersection region between the first wiring 31 and the second wiring 32. Assuming that the shapes and sizes of the first wiring 31 and the second wiring 32 are the same, in the structure shown in FIG. 5A, the area of each of the intersections 34 and 35 is less than that of the intersection 41 of the comparative example. 2 or less. Thereby, the visibility of the lighting state in each intersection location 34 and 35 becomes low compared with the intersection location 41 of a comparative example.

  FIG. 5B shows an example in which openings are provided in both the first wiring 31 on the first substrate 11 side and the second wiring 32 on the second substrate 15 side. As in this structure example, the first opening 33 can be provided in the first wiring 31 and the second opening 36 can be provided in the second wiring 32. In this case, the intersection area between the first wiring 31 and the second wiring 32 can be divided into four intersections 37, 38, 39, and 40 as shown in the figure. In contrast to the comparative example shown in FIG. 5D, if the shape and size of the first wiring 31 and the second wiring 32 are the same, the intersections 37 to 40 in the structure shown in FIG. Is less than or equal to ¼ compared to the intersection 41 of the comparative example. Thereby, the visibility of the lighting state at each of the intersections 37 to 40 is lower than that of the structural example shown in FIG. 5A, and the intersection 41 of the comparative example shown in FIG. Compared to this, it becomes even lower.

  FIG. 5C shows a case where an opening is provided in each of the first wiring 31 on the first substrate 11 side and the second wiring 32 on the second substrate 15 side, as in FIG. An example in which the width of the opening is made larger (thicker) is shown. Specifically, the first opening 33a in the example shown in FIG. 5C is several times (for example, five times) wider than the first opening 33 in the example shown in FIG. 5B. Is formed. Thereby, the space | interval (inter-distance) between the crossing places 37 and 38 and the crossing places 39 and 40 can be expanded more, and it becomes possible to further lower the visibility of the lighting state in each crossing places 37-40. More specifically, the width of the first opening 33a is desirably 100 μm or more. Thereby, since the distance between the intersections 37 and 38 and the intersections 39 and 40 can be separated by 100 μm or more, the above-described characteristics of the human eye can further reduce the visibility of each intersection. Become prominent.

  Further, the second opening 36a in the example shown in FIG. 5C is formed to have a width several times (for example, five times) that of the second opening 36 in the example shown in FIG. 5B. Yes. Thereby, the space | interval (inter-distance) between the crossing places 37 and 39 and the crossing places 38 and 40 can be expanded more, and it becomes possible to further lower the visibility of the lighting state in each crossing places 37-40. More specifically, the width of the second opening 36a is desirably 100 μm or more. Thereby, since the distance between the intersections 37 and 39 and the intersections 38 and 40 can be separated by 100 μm or more, the above-described characteristics of the human eye can further reduce the visibility of each intersection. Become prominent.

  By combining the wide first opening 33a and the wide second opening 36a as described above, the distance between the intersections 37 to 40 is increased, and the visibility can be reduced. Note that only one of the first opening 33a and the second opening 36 may be widened, and even in that case, the effect of reducing the visibility of the lighting state at each of the intersections 37 to 40 can be obtained.

  FIG. 6 is a schematic plan view showing a structural example in an intersection region between the first wiring and the second wiring. In the example shown in FIG. 6A, the second wiring 32 is formed with a narrow line width in the middle thereof, and the first wiring 31 and the second wiring intersect at a portion where the line width is narrowed. . In this way, when the line width of one wiring (second wiring 32 in this example) can be partially narrowed, the opening (the first wiring 31 in this example) is formed only in the other wiring (first wiring 31 in this example). Even by providing the opening 33), the area of each intersection 34, 35 can be reduced, and the visibility of the lighting state can be sufficiently reduced. Such a configuration example is particularly suitable when the line width of one wiring can be designed to be narrow. In addition, you may provide an opening part in both wiring.

  On the other hand, in the example shown in FIG. 6B, the second wiring 32 does not have a particularly narrow line width even at a portion that intersects the first wiring 31. Instead, the second wiring 32 has a second opening 36b formed with a wider width. Thus, by providing an opening having a wider width, the area of each intersection 37, 38, 39, 40 can be reduced, and the distance between the intersections can be increased. Thereby, the visibility of the lighting state in each intersection can be sufficiently reduced. Such a configuration example is preferable in that it is not necessary to reduce the line width even at a portion where the first wiring 31 and the second wiring 32 intersect. This is because the advantage of increasing the degree of freedom of design and the advantage of lowering the probability of disconnection can be obtained. In this example, a wide opening is provided in only one wiring, but a wide opening may be provided in both wirings.

  Next, a result of verifying how much the wiring resistance value is affected by providing the first opening or the second opening using the simulation model shown in FIG. 7 will be described. FIG. 7A is a plan view showing a wiring model of a linear pattern (solid pattern) having no opening, and FIG. 7B is a wiring of a linear pattern (slit pattern) having an opening. It is the top view which showed the model. In the following, the differences in wiring resistance values will be examined using these models. As a premise of the simulation, the sheet resistance value of each wiring model shown in FIGS. 7A and 7B is 100Ω / □, the wiring length is 2 mm, and the wiring width is 0.1 mm.

In the wiring model shown in FIG. 7A, the wiring resistance value Ra from the start point (START) to the end point (FINISH) can be calculated as follows.
Ra = sheet resistance value × wiring length × (1 / wiring width) (1)
According to this calculation formula (1), the wiring resistance value R in the wiring model shown in FIG. 7A is calculated as follows.
Ra = 100Ω × 2 mm × (1 / 0.1 mm) = 2 kΩ

In the wiring model shown in FIG. 7B, the wiring resistance value Rb from the start point to the end point is the resistance value R1 from the start point to the point a and the resistance value R2 from the point a to the point b. , B can be expressed as the sum of resistance values R3 from the point b to the end point. Of these, the resistance values R1 and R3 can be expressed in the same manner as the above-described calculation formula (1), and thus are calculated as follows.
R1 = 100Ω × 0.95 mm × (1 / 0.1 mm) = 0.95 kΩ
R3 = 100Ω × 0.95 mm × (1 / 0.1 mm) = 0.95 kΩ
Further, the resistance value R2 can be expressed as a resistance value when the resistance value R4 of one wiring branch and the resistance value R5 of the other wiring branch across the opening are connected in parallel.
1 / R2 = 1 / R4 + 1 / R5 (2)
Therefore, the resistance value R2 is calculated as follows.
R4 = 100Ω × 0.1 mm × (1 / 0.04 mm) = 0.25 kΩ
R5 = 100Ω × 0.1 mm × (1 / 0.04 mm) = 0.25 kΩ
∴ R2 = 0.125kΩ
From the above, Rb is calculated as follows.
Rb = R1 + R2 + R3 = 2.025kΩ

  Comparing the wiring resistance values of the wiring models shown above, the difference in resistance value due to the presence or absence of the opening is 0.025 kΩ, that is, 25Ω. From this result, it is understood that the resistance value does not increase so much even if an opening is provided in the wiring.

  As described above, according to the present embodiment, it is possible to obtain a liquid crystal display device that can make it difficult to visually recognize the lighting state at the intersection of the wirings without increasing the wiring resistance so much.

  In addition, this invention is not limited to the content of embodiment mentioned above, In the range of the summary of this invention, it can change and implement variously. For example, in the above-described embodiment, an example in which the present invention is applied to the segment type liquid crystal display device has been described. However, the present invention can be similarly applied to other types of liquid crystal display devices. is there.

  In the above-described embodiment, only one opening is provided for each wiring. However, a plurality of openings may be provided as in the modified example illustrated in FIG. Specifically, in the modified example shown in FIG. 8A, the first wiring 31 has two first openings 133 and 134 arranged in parallel. In this example, it is also preferable that the distance L6 between the two first openings 133 and 134 is 100 μm or less. This is because when the width of the wiring portion between the two first openings 133 and 134 is 100 μm or less, the wiring portion is hardly visually recognized. In the modified embodiment shown in FIG. 8B, the first wiring 31 has two first openings 135 and 136 arranged in series. Even in such an embodiment, the same effect as described above can be obtained. In this example, it is also preferable that the distance L7 between the two first openings 135 and 136 is 100 μm or less. This is because when the width of the wiring portion between the two first openings 135 and 136 is 100 μm or less, the wiring portion is hardly visible. Similarly, the second wiring 32 may be provided with a plurality of second openings. Further, one opening may be provided in one of the wirings, and a plurality of openings may be provided in the other wiring.

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2 ... Display part, 3 ... Terminal part, 4 ... Seal area, 11 ... 1st board | substrate, 12 ... 1st electrode, 13 ... Alignment film | membrane, 14 ... Liquid crystal layer, 15 ... 2nd board | substrate, 16 2nd electrode, 17 ... Alignment film, 21 ... 1st polarizing plate, 22 ... 2nd polarizing plate, 31 ... 1st wiring, 32 ... 2nd wiring, 33, 33a ... 1st opening part (slit), 36, 36a, 36b ... second opening (slit), 34, 35, 37, 38, 39, 40, 41 ... intersections

Claims (3)

A first substrate having a first electrode and a first wiring connected to the first electrode on one surface;
A second substrate having a second electrode and a second wiring connected to the second electrode on one surface;
A liquid crystal layer sandwiched between one surface of the first substrate and one surface of the second substrate;
Including
One or more first openings are provided in the first wiring in an intersecting region where the first wiring and the second wiring overlap in plan view, and the width of the first opening is set to 100 μm or more;
Liquid crystal display device.   The line width of the first wiring and the width of the first opening are set so that the wiring width on both sides of the first opening of the first wiring is 100 μm or less, respectively. The liquid crystal display device described. Further, the second opening of at least one said second wiring in the intersection region is provided, the liquid crystal display device according to claim 1 or 2.