JP2009186814A - Liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal cell capable of reducing low temperature bubbles while securing load resistance. <P>SOLUTION: Elastic layers 26, 44 are respectively formed on substrates 16, 17 which are arranged so as to be faced to each other. A plurality of spacers 19 for holding a gap between the substrates 16, 17 are fixed on prescribed positions between the substrates 16, 17 by adhesive layers 47, 48. Load applied to the spacers 19 is uniformly dispersed into the elastic layers 26, 44 and the applied load is surely received by the spacers 19 and the elastic layers 26, 44. Even when a liquid crystal layer 18 is contracted under a low temperature environment, the elastic layers 26, 44 are contracted following the contraction of the liquid crystal layer 18. Consequently, low temperature bubbles can be reduced while securing load resistance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display element including a plurality of gap holding members that are located between substrates and hold gaps between the substrates.

  Conventionally, a liquid crystal cell, which is a liquid crystal display element, is configured by disposing a liquid crystal layer with a predetermined orientation between a pair of substrates, and can maintain a uniform spacing between the substrates, that is, the thickness of the liquid crystal layer. Determine the quality of the image.

  In order to make the thickness of the liquid crystal layer constant, there is a conventional configuration in which a spacer as a gap holding member is used between a pair of substrates. As the spacer, a so-called ball spacer formed in a spherical shape with inorganic particles or organic particles such as silica has been known (for example, see Patent Document 1).

  However, the ball spacer has problems such as being present on the pixel and deteriorating the image quality. Therefore, a configuration is known in which a photo spacer formed by photolithography using a resin composition for a spacer instead of the ball spacer is used (see, for example, Patent Document 2).

  However, the amount of plastic deformation of the photo spacer is large, and when the substrates are pressure-bonded in the assembly process of the liquid crystal cell, the height of the photo spacer varies and the image quality is deteriorated or the load resistance is reduced. Have the following problems.

In this regard, although it is conceivable to increase the hardness of the photo spacer, in this case, for example, when the liquid crystal layer of the liquid crystal cell contracts in an environment where the temperature is low, the photo spacer causes the liquid crystal layer to contract. Inability to follow, low temperature bubbles may occur inside the liquid crystal layer. Therefore, low temperature foam and load bearing capacity are in a trade-off relationship with each other.
Japanese Patent Laid-Open No. 11-64862 JP-A-62-90622

  As described above, there is a demand for a liquid crystal cell capable of ensuring sufficient image quality and supporting sufficient load resistance and low-temperature foam reduction.

  The present invention has been made in view of such a point, and an object thereof is to provide a liquid crystal display element in which low temperature bubbles are reduced while ensuring load resistance.

  The present invention provides a pair of substrates disposed opposite to each other, a liquid crystal layer interposed between the substrates, an elastic layer provided on at least one of the substrates, and the substrate. A plurality of gap holding members for holding gaps between the substrates, and an adhesive layer for fixing the gap holding members at predetermined positions between the substrates.

  Then, an elastic layer is formed on at least one of the substrates, and a gap holding member that holds a gap between the substrates is fixed between the substrates by an adhesive layer at a predetermined position.

  According to the present invention, the load applied to the spacer is uniformly dispersed in the elastic layer, and the applied load is reliably received by the spacer and the elastic layer. The shrinkage follows the shrinkage, and low temperature bubbles can be reduced while ensuring load resistance.

  Hereinafter, the configuration of a liquid crystal display element according to an embodiment of the present invention will be described with reference to FIGS.

  In FIG. 4, 11 is a liquid crystal panel which is a liquid crystal display device as a display device. The liquid crystal panel 11 includes, for example, a substantially rectangular flat liquid crystal display element, that is, a liquid crystal cell 12 which is an LCD (Liquid Crystal Display) cell, The liquid crystal cell 12 is a transmissive type including a backlight 13 which is a planar light source device that irradiates, for example, white planar light on the back side.

  The liquid crystal cell 12 is, for example, an active matrix type capable of color display. An array substrate 16 serving as a substrate and a counter substrate 17 serving as a substrate are arranged to face each other, and light is transmitted between the substrates 16 and 17. A liquid crystal layer 18 as a modulation layer is interposed, and the distance between the substrates 16 and 17 is held by a spacer 19 as a plurality of gap holding members, and a polarizing plate (not shown) is attached to each of the substrates 16 and 17 Then, the substrates 16 and 17 are bonded and fixed to each other by a seal portion 20 as an adhesive portion.

  As shown in FIGS. 1 to 3, the array substrate 16 has a light-transmitting and insulating transparent substrate, ie, a thin film transistor (TFT) 22 as a switching element on the main surface of the glass substrate 21 on the liquid crystal layer 18 side. A colored layer 23, which is a color filter layer formed thereon and having colored portions 23r, 23g, and 23b corresponding to red (R), green (G), and blue (B), is formed in a stripe shape, for example. . Further, pixel electrodes 24 (FIG. 2), which are transparent electrodes made of a transparent conductive material such as ITO (Indium Tin Oxide), are formed on the colored portions 23r, 23g, and 23b, respectively. The pixel electrode 24 is electrically connected to the thin film transistor 22 through a contact hole (not shown) formed in each colored portion 23r, 23g, 23b. Further, an alignment film (not shown) is formed on the coloring portions 23r, 23g, and 23b including the pixel electrode 24 through a planarization film, and an elastic layer 26 is formed on the alignment film. A display area 28 for screen display having pixels 27 in a matrix shape is formed in a square shape depending on the configuration. Further, a black matrix (BM) layer (not shown) that is a light shielding layer constituting the non-display area 29 is formed in a rectangular frame shape in the vicinity of the inner edge of the seal portion 20 that is the outer periphery of the display area 28.

  The thin film transistor 22 has a gate electrode connected to the scanning line 31, a source electrode connected to the signal line 32, and a drain electrode connected to the pixel electrode 24. Switching is controlled by applying a signal to the gate electrode via the scanning line 31, and a voltage is applied to the pixel electrode 24 corresponding to the signal input from the source driver 37, which is a signal line driving circuit, via the signal line 32. By applying the voltage, each pixel 27 is turned on / off independently.

  The scanning line 31 and the signal line 32 are light-shielding portions formed of a predetermined conductive material such as metal, and are formed between the pixels 27.

  The elastic layer 26 is formed in a layer shape having a predetermined thickness from a material such as a resin composition for a photo spacer as described in, for example, Japanese Patent Application Laid-Open No. 2007-206328. It is formed so as to continue along the scanning line 31 on the scanning line 31 which is a position corresponding to the scanning line 31 which is a light-shielding portion where the light is blocked. In addition, it may be formed along a storage capacitor line (not shown) which is a light shielding portion. The elastic layer 26 may be formed intermittently, that is, in an island shape, instead of being formed continuously along the scanning line 31 or the auxiliary capacitance line. The elastic layer 26 is formed after rubbing the alignment film on the array substrate 16 side.

  The counter substrate 17 is a common electrode (transparent electrode) formed of a transparent conductive material such as ITO (Indium Tin Oxide) on one main surface of a transparent substrate having transparency and insulation, that is, a glass substrate 41. A counter electrode (not shown) is formed, an alignment film (not shown) is formed so as to cover the counter electrode, and an elastic layer 44 similar to the elastic layer 26 on the array substrate 16 side is formed on the alignment film.

  That is, the elastic layer 44 is formed into a layer having a predetermined thickness from a material such as a resin composition for a photospacer described in, for example, Japanese Patent Application Laid-Open No. 2007-206328. It is formed in a predetermined position facing each other. In the present embodiment, the elastic layer 44 is formed to be continuous along the scanning line 31 at a position corresponding to the scanning line 31 on the array substrate 16 side. The elastic layer 44 is formed after rubbing the alignment film on the counter substrate 17 side.

  Note that only one of the elastic layers 26 and 44 may be provided.

  The liquid crystal layer 18 is a light modulation layer formed of a predetermined liquid crystal material, and is interposed between the alignment film on the array substrate 16 side and the alignment film on the counter substrate 17 side.

  The spacer 19 is a so-called ball spacer made of, for example, inorganic particles such as silica or organic particles formed in a spherical shape, and is fixed between the elastic layers 26 and 44 via the adhesive layers 47 and 48. . Therefore, the spacer 19 is formed to be harder than the elastic layers 26 and 44.

  The adhesive layers 47 and 48 are made of a material obtained by adding a photosensitizer to a polymer adhesive made of an acrylic resin, for example, at a predetermined position, for example, near the intersection of the scanning line 31 and the signal line 32, that is, from the backlight. At the position between each pixel 27 which is a light shielding portion where the light is shielded, it is patterned into an island shape having a square shape in plan view on each of the array substrate 16 side and the counter substrate 17 side. The adhesive layers 47 and 48 are formed after the alignment films of the substrates 16 and 17 are rubbed.

  Note that only one of the adhesive layers 47 and 48 may be used.

  Next, a method for manufacturing the liquid crystal cell 12 of the above embodiment will be described.

  First, for the array substrate 16, the scanning lines 31, the signal lines 32, the thin film transistors 22, the coloring layer 23, the pixel electrodes 24, and the like are formed on the glass substrate 21, and then an alignment film is formed thereon.

  Next, the alignment film is rubbed, and an elastic layer 26 is formed on the rubbed alignment film and patterned.

  Further, after the adhesive layer 47 is formed on the elastic layer 26 and patterned, the spacers 19 are disposed on the adhesive layers 47. At this time, the spacer 19 is, for example, scattered by a large number on the glass substrate 21 to remove those that have not adhered to the adhesive layer 47, or by a method of hitting only the place where the adhesive layer 47 is formed by an inkjet device or the like Deploy.

  On the other hand, for the counter substrate 17, after the counter electrode and the alignment film are formed on the glass substrate 41, the alignment film is formed thereon.

  Next, the alignment film is rubbed, and an elastic layer 44 is formed on the rubbed alignment film and patterned.

  Further, an adhesive layer 48 is formed on the elastic layer 44 and patterned.

  The spacer 19 may be disposed on the counter substrate 17 side by the above methods.

  Then, a seal member such as a photo-curing resin constituting the seal portion 20 is applied to the array substrate 16 or the counter substrate 17 except for a part to form a liquid crystal injection port, and the array substrate 16 and the counter substrate 17 Are aligned and bonded together, the seal member is cured to form the seal portion 20, and the array substrate 16 and the counter substrate 17 are bonded.

  Thereafter, a liquid crystal material constituting the liquid crystal layer 18 is injected from the liquid crystal injection port, and then the liquid crystal injection port is closed with a seal member or the like to complete the liquid crystal cell 12.

  The liquid crystal layer 18 may be formed by a liquid crystal dropping method, that is, the substrates 16 and 17 are bonded together in a state where a liquid crystal material is previously dropped on the array substrate 16 or the counter substrate 17 coated with a seal member.

  As described above, in the above-described embodiment, the elastic layers 26 and 44 are formed on at least one of the substrates 16 and 17, and the spacer 19 that holds the gap between the substrates 16 and 17 is disposed at the predetermined position. , 48 is fixed between the substrates 16 and 17 by at least one of them.

  For this reason, the load applied to the spacer 19 is evenly distributed in the elastic layers 26 and 44, and the spacer 19 is fixed by the adhesive layers 47 and 48 so that the spacer 19 and the substrates 16 and 17 are not slipped. In addition to being able to be received by more spacers 19 and elastic layers 26 and 44, the elastic layers 26 and 44 also follow the contraction of the liquid crystal layer 18 when the liquid crystal layer 18 contracts in a low temperature environment. The spacer 19 can be placed at a predetermined position while leaving a good part of the photo spacer, and the low temperature bubble is reduced while ensuring the load resistance, that is, the liquid crystal cell 12 that achieves both load resistance and low temperature bubble reduction. Can be obtained.

  Moreover, an elastic layer and an adhesive layer are formed on both substrates 16 and 17, respectively, that is, an elastic layer 26 and an adhesive layer 47 are formed on the array substrate 16, and an elastic layer 44 and an adhesive layer 48 are formed on the counter substrate 17. Thus, the distribution region of the load applied to the spacer 19 is increased, and the respective margins of the low-temperature foam and the load resistance can be further expanded.

  Further, by improving the load resistance, it is possible to obtain the liquid crystal cell 12 in which the thickness of the liquid crystal layer 18 becomes uniform, and the spacer 19 does not pass through the pixel 27 or the like and the image quality is good.

  Moreover, the manufacturing load is small by using a spacer as a ball spacer.

  In the above embodiment, the elastic layers 26 and 44 may be formed below the alignment films of the substrates 16 and 17. That is, only the adhesive layers 47 and 48 may be formed after each alignment film is rubbed.

  As the liquid crystal cell 12, a liquid crystal cell 12 provided with the colored layer 23 on the counter substrate 17 side can also be used.

  Further, as the spacer 19, not only the ball spacer but also a photo spacer can be used.

  And about the Example 1 and Example 2 corresponding to the said one Embodiment, and the comparative example corresponding to a prior art example, the experiment regarding a low-temperature bubble and load resistance was each performed. The results are shown in FIG. 5 and FIG.

  First, in Example 1, only one of the elastic layers 26 and 44 and the adhesive layers 47 and 48 is used.

  In Example 2, all the elastic layers 26 and 44 and the adhesive layers 47 and 48 are provided.

  On the other hand, the comparative example uses, for example, a photo spacer formed of the same material as the elastic layers 26 and 44 instead of the spacer 19 without forming the elastic layers 26 and 44 and the adhesive layers 47 and 48, respectively. .

  Experiments related to low-temperature foams were whether or not bubbles were generated when a metal sphere with a diameter of 1 cm was dropped from a height of 30 cm after each of Examples 1, 2 and Comparative Examples was stored at a specified temperature for 4 hours or more. Is determined.

  In the experiment regarding load resistance, a circular rubber having a diameter of 1 cm was pressed for 10 seconds with a specified load, and it was determined whether or not the unevenness disappeared within 1 minute after the rubber was removed.

Each margin of the low temperature foam and the load resistance depends on the use environment of the liquid crystal cell, etc., but at least −20 ° C. for the low temperature foam and 20 N / cm ² for the load resistance are required. It is desired to satisfy both −30 ° C. for foam and 30 N / cm ² for load resistance.

As shown in the table of FIG. 5, for the low-temperature foam, the comparative example does not satisfy −10 ° C., whereas Example 1 satisfies −20 ° C. and Example 2 satisfies −30 ° C. Further, as shown in the table of FIG. 6, load capacity for heavy resistance, whereas Comparative Examples does not satisfy the 30 N / cm ^2, Example 1 is 30 N / cm ^2, the Example 2 40N / cm ² Satisfies each. Therefore, by providing any one of the elastic layers 26 and 44 and any one of the adhesive layers 47 and 48, the margin between the low-temperature foam and the load resistance is improved as compared with the case of only the photo spacer. Further, it was confirmed that the margin between the low-temperature foam and the load resistance is further expanded by providing all of the elastic layers 26 and 44 and the adhesive layers 47 and 48.

It is explanatory sectional drawing which shows the principal part of the liquid crystal display element of one embodiment of this invention. It is a top view which shows the principal part of a liquid crystal display element same as the above. It is a circuit diagram which shows a liquid crystal display element same as the above. It is explanatory drawing which shows the liquid crystal display device provided with the liquid crystal display element same as the above. It is a table | surface which shows the result of the low temperature bubble experiment about Example 1 and Example 2 corresponding to a liquid crystal display element same as the above, and the comparative example corresponding to a prior art example. It is a table | surface which shows the result of the load resistance experiment about Example 1 and Example 2 corresponding to a liquid crystal display element same as the above, and the comparative example corresponding to a prior art example.

Explanation of symbols

12 Liquid crystal cell as a liquid crystal display element
16 Array substrate as substrate
17 Counter substrate as substrate
18 Liquid crystal layer
19 Spacer as a gap holding member
26, 44 Elastic layer
31 Scanning line that is a light-shielding part
47, 48 adhesive layer

Claims (3)

A pair of opposed substrates;
A liquid crystal layer interposed between these substrates;
An elastic layer having elasticity and provided on at least one of the substrates;
A plurality of gap holding members positioned between the boards and holding gaps between the boards;
A liquid crystal display element comprising: an adhesive layer that fixes the gap holding member at a predetermined position between the substrates. The liquid crystal display element according to claim 1, wherein the elastic layer and the adhesive layer are formed on both of the pair of substrates. The liquid crystal display element according to claim 1, wherein the elastic layer and the adhesive layer are formed along a light shielding portion.

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