JP2010237321A - Optical element and liquid crystal display device equipped with the optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element that prevents leakage of light from the outline of a light intercepting part, and to provide a liquid crystal display device excellent in contrast. <P>SOLUTION: The optical element has in this order: a light transmissive base material; a light intercepting area formed in a pattern in order to section the base material into an opening through which light can pass and the light intercepting part by which passage of light is prevented; at least one intermediate layer; and a phase difference layer. The film thickness D of the intermediate layer is 0.5 μm or greater. When the surface of the base material is vertically viewed from above, the intermediate layer is sectioned into an intermediate layer opening area, which overlaps the opening, and an intermediate layer light intercepting area, which overlaps the light intercepting part. In a cross-section made by cutting one intermediate layer opening area through its middle part, the thickness of the intermediate layer in the area 90% inside a straight line passing through the middle part of the intermediate layer opening area and connecting the adjacent light intercepting parts is 0.9-1.1D with respect to the thickness D of the intermediate layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to an optical element including a retardation layer and a liquid crystal display device using the optical element.

Since the liquid crystal display device has the great advantages of being thin and light and low power consumption, it is proactive in various display devices such as TVs, personal computers and mobile phones, electronic notebooks, terminal devices installed in stores, and vending machines. It is used. These liquid crystal display devices are characterized by enabling image display by switching light using the birefringence of the driving liquid crystal material constituting the liquid crystal layer.

The liquid crystal display device generally has two substrates facing each other and a liquid crystal layer made of a driving liquid crystal material provided between the substrates. Further, in a liquid crystal display device for color display, a colored layer is generally provided on a display side substrate. In addition, the liquid crystal display device has the problem of viewing angle dependency due to the birefringence of the driving liquid crystal material due to the peculiarity of using the birefringence of the driving liquid crystal material (molecule) contained in the liquid crystal layer. In order to solve this problem, a retardation film that compensates for the retardation of light is used. This retardation film is produced by stretching a film of polyacrylate, polycarbonate, triacetyl cellulose or the like, and is usually a liquid crystal cell (hereinafter referred to as a liquid crystal cell) having two substrates facing each other and a liquid crystal layer formed therebetween. , Simply referred to as “liquid crystal cell”).

In recent years, a so-called in-cell type retardation layer in which a retardation layer is formed in an optical element has been developed instead of the retardation film. Unlike the conventional retardation type retardation film, the retardation layer is a layer formed by applying a retardation layer forming material on a substrate surface and fixing the material in a state where the material exhibits a desired orientation. is there. Unlike the retardation film that is attached to the outside of each of the two substrates, the retardation layer can be composed of one layer inside the liquid crystal cell, and the thickness of the layer itself is thin. In addition to being advantageous in that the heat resistance is improved, there is no problem such as an adverse effect caused by the adhesive when the retardation film is attached. As a proposal of an optical element provided with such a retardation layer, for example, there is Patent Document 1 below.

In recent years, from the viewpoint of environmental problems and the like, it is one of important issues to reduce power consumption in a liquid crystal display device. On the other hand, a transflective liquid crystal display device that can also use light from outside light has attracted attention. This transflective liquid crystal display device includes a portion that exhibits a liquid crystal display function using external light (reflection portion) and a portion that exhibits a liquid crystal display function using light from a backlight (transmission portion). It is more energy efficient than those that rely on the backlight alone as the light source. Then, in order to further improve the energy efficiency and increase the brightness of the transflective liquid crystal display device, the retardation layer is selectively formed in the reflective region so as to recycle light from the backlight. A technique has been proposed (for example, Patent Document 2).

Here, in general, the optical element has a mechanism in which a voltage is repeatedly applied to drive the liquid crystal material of the liquid crystal layer. Therefore, the layer formed at a position close to the liquid crystal layer in the optical element must be prevented from being damaged by the influence of the voltage and causing the material to penetrate into the liquid crystal layer, etc. Electrical reliability such as seizure prevention is required. From this point of view, a layer having technical accumulation and high electrical reliability (hereinafter also simply referred to as “conventional layer”) such as a colored layer is provided closer to the liquid crystal layer than the recently developed retardation layer. It is desirable. Specifically, the configuration of an optical element formed by first patterning a light-shielding region on a light-transmitting substrate, then forming a retardation layer, and then forming a conventional layer such as a colored layer is electrically This is desirable from the viewpoint of reliability. When an alignment film is necessary for forming the retardation layer, the alignment film may be formed prior to the retardation layer. The reason why it is desirable to form the light shielding region first on the light-transmitting substrate is that it is formed in a subsequent process by forming an alignment mark on the substrate surface at the same time when the light shielding region is formed. This is because the formation position of the retardation layer and the colored layer can be clarified.

Further, even in the case of an optical element for black and white display, in particular, when a functional layer such as a colored layer is not provided, a light shielding region is formed on a substrate, and then a retardation layer or an alignment film is formed as described above. A configuration in which a retardation layer is formed is possible.

JP 2000-221506 A Japanese Patent Application Laid-Open No. 2006-276697

However, as described above, a light shielding region that is patterned into a transmission portion and a light shielding portion is formed on the base material surface, and then the retardation layer (or alignment film and When the retardation layer is formed, light leakage occurs in the outline portion of the light shielding portion during black display or the like, which is a problem. Further, when a liquid crystal display device is manufactured using such an optical element having a problem of light leakage, the contrast of the liquid crystal display device is lowered, and a high quality image cannot be provided. The problem of the above light leakage is that when the retardation layer forming material constituting the retardation layer is applied to the surface of the base material, the retardation layer applied around the light shielding portion due to the presence of a step in the light shielding portion serving as a convex portion. This is presumably because the forming material is difficult to be parallel to the substrate surface or cannot be oriented in a desired direction.

As a result of earnest research on the above problems, the present inventors formed a retardation layer after forming an intermediate layer having a certain thickness or more, covering the light shielding region formed on the substrate surface. Accordingly, it has been found that the problem of light leakage from the contour portion of the light shielding portion (hereinafter, also simply referred to as “Problem 1”) can be satisfactorily prevented. However, when an intermediate layer having a certain thickness or more is formed so as to cover the light shielding region formed on the base material surface, in this case, in one opening section partitioned by the light shielding portion, a parallel Nicol polarizing plate It was confirmed that a problem (hereinafter, also simply referred to as “Problem 2”) occurs in which the amount of transmitted light is different when observed between. More specifically, when the optical element is configured as described above, there is a tendency that a light transmission amount is different between the central portion and the peripheral portion in one opening. In recent years, in particular, there has been a high demand for providing high-quality liquid crystal image displays, and the amount of light transmitted through one opening in an optical element is made as uniform as possible. As a result, a liquid crystal display device manufactured using the optical element There is a demand for higher contrast. Therefore, it has been desired to solve the above problem 2 which occurs when the above problem 1 is solved.

The present invention has been made in view of the above-described problems. When a light shielding region is formed on a substrate and then a retardation layer is formed prior to a conventional layer, or a functional layer such as a colored layer is formed. Even if the base material, the light shielding region, and the retardation layer form a basic configuration, light leakage does not occur in the contour portion of the light shielding portion, and the light transmission amount in one opening portion is the image. It is an object of the present invention to provide a liquid crystal display device having excellent contrast and an optical element that is made uniform to the extent that no problem occurs in display.

The inventors of the present invention have adopted a means for forming a retardation layer after forming an intermediate layer having a thickness equal to or greater than a certain thickness so as to cover the light shielding region formed on the substrate surface. The inventors have found that light leakage from the contour portion can be satisfactorily prevented and solved the above problem 1. Further, the present inventors have formed one opening by forming the intermediate layer so that the film thickness thereof is substantially uniform in the intermediate layer opening region that overlaps the opening when observed from the direction perpendicular to the substrate surface. The amount of transmitted light in the section can be made substantially uniform, the above problem 2 is solved, and the present invention is completed.

That is, the present invention
(1) a light-transmitting base material, and a light-shielding region that is patterned to partition the base material into an opening through which light can be transmitted and a light-shielding portion that prevents light transmission, and at least one An intermediate layer and a retardation layer are provided in this order, and the thickness D of the intermediate layer is 0.5 μm or more. In a cross-section cut through the central portion of one intermediate layer opening region, the intermediate layer opening region that is a region overlapping with the light shielding portion and the intermediate layer light shielding portion region that is a region overlapping with the light shielding portion, The thickness of the intermediate layer in the 90% area inside the straight line passing through the center of the intermediate layer opening region and connecting between adjacent light shielding portions is 0.9D or more and 1.1D or less with respect to the thickness D of the intermediate layer. An optical element,
(2) The optical element according to (1), wherein the intermediate layer is a transparent resin layer and / or an alignment film,
(3) The optical element according to (1) or (2) above, wherein the surface of the intermediate layer, the surface opposite to the substrate is not flattened,
(4) The optical element according to any one of (1) to (3), wherein the retardation layer is patterned.
(5) The optical element according to any one of (1) to (4), wherein the retardation layer is a positive A plate,
(6) The optical element according to any one of (1) to (5) above, wherein a light-transmitting colored layer is provided directly or indirectly on the retardation layer,
(7) A liquid crystal display device comprising two substrates facing each other, a polarizing plate provided on each outer surface of the two substrates, and a liquid crystal layer made of a driving liquid crystal material provided between the two substrates. Then, as one of the two substrates, a base material having a light transmitting property, and the base material are divided into an opening through which light can be transmitted and a light shielding unit from which light transmission is prevented. Therefore, a light-shielding region to be patterned, at least one intermediate layer, and a retardation layer are provided in this order, and the intermediate layer has a thickness D of 0.5 μm or more, and is perpendicular to the base material surface. When viewed in plan, the intermediate layer is classified into an intermediate layer opening area that is an area that overlaps with the opening and an intermediate layer light shielding area that is an area that overlaps the light shielding part. In the cross section cut through the central part in the part area, The thickness of the intermediate layer in the 90% region inside the straight line passing through the center of the intermediate layer opening region and connecting between the adjacent light shielding portions is 0.9D or more and 1.1D with respect to the thickness D of the intermediate layer. A liquid crystal display device characterized by using an optical element characterized by:
(8) The liquid crystal display device according to (7), wherein the liquid crystal display device is a transflective liquid crystal display device,
Is a summary.

According to the present invention, by forming an intermediate layer having a certain thickness between the light shielding region and the retardation layer, it is possible to satisfactorily prevent light leakage at the contour portion of the light shielding portion, which has been a problem in the past. it can. That is, when viewed in a plan view from the direction perpendicular to the substrate surface, at least one layer of the intermediate layer has a film thickness at the central portion in the partial region of the intermediate layer that overlaps the opening (hereinafter simply referred to as “intermediate layer The above problem 1 was solved by adopting a configuration in which the thickness is also referred to as “film thickness” of 0.5 μm or more.

The intermediate layer may be, for example, a transparent resin layer, an alignment film for forming a retardation layer, or a combination thereof. When the intermediate layer is a transparent resin layer, an increase in cost due to the formation of the intermediate layer can be suppressed by selecting and using a transparent resin having a low cost, which is desirable. In addition, when the intermediate layer is an alignment film, it is possible to play the role of the intermediate layer at the same time only by forming the alignment film thicker than before, so that the number of steps for forming the intermediate layer is not increased. This is very advantageous in that the intended purpose is achieved.

In the intermediate layer in the present invention, the thickness of the intermediate layer in the inner 90% region in the intermediate layer opening region is 0.9D or more and 1.1D or less with respect to the thickness D of the central portion in the intermediate layer opening region. It is specified. This intends to make the film thickness of the intermediate layer in the intermediate opening region substantially uniform except for the edge portion of the intermediate layer opening region which does not substantially affect the image display.
As a result of the configuration as described above, the thickness of the retardation layer formed directly or indirectly on the upper surface of the intermediate layer can be formed to be substantially uniform in the opening region. Therefore, there is no difference in the light phase difference control amount in one opening, and the light transmission amount as designed passes through the opening, so that the problem 2 can be solved satisfactorily.
The inner 90% region means that the intermediate layer overlaps with the light shielding portion and the intermediate layer opening region, which is a region overlapping with the opening when viewed in a plane from the direction perpendicular to the base material surface. It is distinguished from the intermediate layer light-shielding part region which is a matching region, and in the cross section cut through the central part in one intermediate layer opening part region, it passes through the central part of the intermediate layer opening part region, and between adjacent light-shielding parts It means the 90% area inside the connecting straight line.

Further, as described above, the intermediate layer in the present invention is formed to have a thickness of 0.5 μm or more, but the upper limit is not particularly limited. However, in the present invention, the intermediate layer is formed with a thickness sufficiently larger than the thickness of the light-shielding portion, so that the surface of the intermediate layer (the surface opposite to the substrate) is not flattened. Can achieve its intended purpose. In other words, in the present invention, even if irregularities are formed on the surface of the intermediate layer due to the influence of the light shielding portion, a predetermined film thickness is ensured and the intermediate layer has a substantially uniform film thickness in the intermediate layer opening region. It is sufficient that the thickness of the intermediate layer is designed to be equal to or less than the thickness of the light shielding portion. Therefore, according to the present invention, it is not always necessary to form the intermediate layer sufficiently thick enough to completely cover the light-shielding portion and flatten the surface, so that the material constituting the intermediate layer compared to the so-called flattened layer This is advantageous in that the amount used can be reduced. In addition, an intermediate layer that can achieve the intended purpose without increasing the thickness like a so-called flattening layer is desirable from the viewpoint of thinning the optical element.

The present invention can provide an optical element for color display without light leakage by providing a light shielding region, an intermediate layer and a retardation layer in this order on a substrate surface, and further forming a colored layer. The optical element of the present invention can be used as an optical element for transflective liquid crystal display by patterning the retardation layer into a desired pattern.

As described above, if the liquid crystal display device uses the optical element of the present invention having no light leakage as a substrate on one side, in any type of liquid crystal display device of transmissive type, semi-transmissive semi-reflective type, reflective type, A high-quality image with excellent contrast can be provided.

It is a schematic sectional drawing which shows one Embodiment of the optical element of this invention. It is a schematic sectional drawing which shows one Embodiment of the optical element of this invention. It is a schematic sectional drawing which shows one Embodiment of the optical element of this invention. It is a schematic sectional drawing which shows the example of the conventional optical element. It is a schematic sectional drawing of the optical element shown as a comparison of this invention. It is a schematic top view which shows one embodiment of the optical element of this invention for transflective liquid crystal display devices. It is a schematic sectional drawing of the XX cross section of the optical element shown in FIG. It is a schematic sectional drawing of the YY cross section of the optical element shown in FIG. 1 is a schematic exploded perspective view of a transflective liquid crystal display device of the present invention. It is a graph which shows the result of having measured Example 1 with the stylus type film thickness meter. It is a graph which shows the result of having measured the comparative example 3 with the stylus type film thickness meter. It is a graph which shows the result of having measured the comparative example 4 with the stylus type film thickness meter. 2 is a photomicrograph showing the state of light transmission in the light leakage evaluation of Example 1. 3 is a photomicrograph showing the state of light transmission when evaluating phase difference control unevenness in Example 1. FIG. 6 is a photomicrograph showing the state of light transmission in the light leakage evaluation of Comparative Example 1. 10 is a photomicrograph showing the state of light transmission in the light leakage evaluation of Comparative Example 3. 10 is a photomicrograph showing a state of light transmission when evaluating phase difference control unevenness of Comparative Example 3. 10 is a photomicrograph showing the state of light transmission in the light leakage evaluation of Comparative Example 4. 6 is a photomicrograph showing the state of light transmission during evaluation of phase difference control unevenness in Comparative Example 4.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an optical element 1 of the present invention. In the optical element 1, a light-shielding region 3 composed of a light-shielding portion 3a and a light-shielding portion 3b formed in a desired pattern is formed on a light-transmitting substrate 2, and then an intermediate layer 4 and a retardation layer 5 are sequentially formed. Further, a colored layer 9 composed of a red colored region 6, a green colored region 7, and a blue colored region 8 is formed. When the optical element 1 is observed from the direction perpendicular to the base material 2, the intermediate layer 4 is divided into an intermediate layer opening area A that overlaps the opening b and an intermediate layer light shielding area B that overlaps the light shielding part 3a. Differentiated. The intermediate layer 4 is formed so that the thickness D from the upper surface of the base material 2 to the upper surface of the central portion a of the intermediate layer 4 is 0.5 μm or more. Further, the region S shown in FIG. 1 is an inner 90% region excluding the distance of 5% from both ends when the distance between the adjacent light shielding portions 3a is 100% in the intermediate layer opening region A. It is shown. The intermediate layer 4 in the present invention is formed such that the thickness in the inner 90% region indicated by the region S is 0.9D or more and 1.1D or less with respect to the thickness D of the central portion a described above.
FIG. 1 shows a cross section when cut through the central portion a of the intermediate layer opening region A. FIG. For example, in the case of the present invention in which the light-shielding portion is patterned in a lattice pattern in which vertical and horizontal lines are parallel on the substrate surface, and each opening is partitioned into a substantially square or a substantially rectangular shape, It is desirable that the cross section be cut at an angle that is substantially perpendicular to the extending direction of the light shielding portions adjacent to each other in parallel and passing through the central portion in one intermediate layer opening region. Thereby, the film thickness of the intermediate layer in the present invention of the above aspect is better observed. Unless otherwise specified, the cross section of the optical element described below is a cross section cut along the center of the intermediate layer opening region as in FIG.

Another embodiment of the optical element 11 of the present invention is shown in FIG. The optical element 11 is formed in the same manner as the optical element 1 except that the intermediate layer includes a first intermediate layer 12 having an appropriate thickness and a second intermediate layer 13 having a thickness smaller than a predetermined thickness.

Still another embodiment of the optical element 21 of the present invention is shown in FIG. The optical element 21 is provided with a first intermediate layer 22 that is thicker than the light-shielding portion 3 a and completely covers the light-shielding region 3, and then a second intermediate layer that is thinner than a predetermined thickness on the first intermediate layer 22. It is formed in the same manner as the optical element 1 except that the layer 23 is provided. In addition, if the thickness of the intermediate layer is made 1.5 times to 2 times or more thicker than the thickness of the light-shielding portion, or the substrate surface is flattened, the substrate of the intermediate layer (base material) It is possible to flatten the surface opposite to the surface), but in the present invention, the intended purpose of the present invention can be sufficiently achieved without flattening the surface of the intermediate layer. .

As shown in FIGS. 1 to 3, the optical elements 1, 11, and 21 according to the present invention each include at least one film between the light shielding region 3 and the retardation layer 5 formed on the substrate 2. It is important to provide an intermediate layer having a thickness of 0.5 μm or more. Here, the intermediate layer in the present invention is not particularly limited as long as it is an isotropic and light-transmitting layer that can be formed with an appropriate thickness between the light shielding region and the retardation layer. For example, the intermediate layer can be formed of any transparent resin material, or the thickness of the alignment film formed on the substrate surface in advance to form the retardation layer is set to an appropriate thickness. The intermediate layer of the present invention may also function. In the present invention, the light shielding region means a region composed of an opening through which light can be transmitted and a light shielding portion from which light transmission is prevented. Therefore, the intermediate layer opening region described above is actually in direct contact with the base material surface to form the intermediate layer, but the intermediate layer thus formed with the intermediate layer in contact with the base material surface. The intermediate layer in the present invention including the opening region is a layer formed between the light shielding region and the retardation layer.

The embodiment of the present invention will be described more specifically. As an embodiment of the present invention, the intermediate layer may be a single layer as shown in FIG. When the intermediate layer is a single layer, the intermediate layer may be formed with a thickness of 0.5 μm or more. Specifically, the transparent resin layer is formed with a thickness of 0.5 μm or more, or an alignment film May be formed with a thickness of 0.5 μm or more.

As another embodiment of the present invention, the intermediate layer may have two or more layers as shown in FIG. 2 or FIG. When two or more intermediate layers are provided, at least one of them may be formed with a thickness of 0.5 μm or more. For example, the first intermediate layer 12 or 22 can be formed of a transparent resin layer, and a conventionally known alignment film for forming a retardation layer can be formed as the second intermediate layer 13 or 23.

On the other hand, as a comparison with the present invention, a cross-sectional view of a conventional optical element 101 is shown in FIG. In the optical element 101, the light shielding region 3 is formed on the light transmissive substrate 2, and then an alignment film 102 having a thickness of 0.1 μm is provided to form the retardation layer 5, and then the retardation layer 5 is formed. It is formed similarly to the optical element 1 except that it is formed. That is, as exemplified by the optical element 101, the conventional optical element does not have the intermediate layer having a thickness of 0.5 μm or more shown in the present invention, and is directly on the substrate on which the light shielding region is formed. Or an alignment film having a small thickness as shown in FIG. 4 and then a retardation layer. In such a conventional optical element, light leakage has been observed in the contour portion of the light shielding portion as described above. The cause of this light leakage is not clear, but due to the presence of the light shielding portion, the material forming the retardation layer is not oriented in the desired direction around the light shielding portion, resulting in light leakage due to poor alignment. It is guessed that.

In the present invention, whether or not the optical element leaks light is determined by placing the polarizing plates up and down so that the optical axes of the two polarizing plates are 90 ° (crossed Nicols) in the polarizing microscope, and then An optical element is sandwiched between two polarizing plates, the slow axis of the retardation layer of the optical element is aligned with one of the optical axes of the two polarizing plates (extinction position), and the substrate surface from the lower polarizing plate side On the other hand, when light is incident in a substantially vertical direction, it can be determined whether or not light leakage is confirmed around the contour of the light shielding portion.

Further, in order to solve the problem 1 of the present invention, the knowledge obtained by the present inventors as an optical element capable of preventing light leakage will be described with reference to FIG. In the optical element 111 shown in FIG. 5, the intermediate layer 112 formed after the light shielding region 3 is formed on the base material 2 in the optical layer 1 in the optical element 1 shown in FIG. The optical element 1 is the same as the optical element 1 except that it is formed so as to include a region showing a thickness outside the range of 0.9D or more and 1.1D or less with respect to the thickness D of the central portion a in the region S which is the inner 90% region It is formed similarly. As shown in the optical element 111 shown in FIG. 5, the thickness of the intermediate layer in the intermediate layer opening region A is not substantially constant, and the film thickness is significantly larger than the film thickness of the intermediate layer in the central portion a. When the thick region is included, the thickness of the retardation layer 5 formed thereon becomes nonuniform in the opening region (in FIG. 5, the thickness of the retardation layer 5 is the thickness of the central portion a of the intermediate layer 112). The upper part is the thickest, and the thickness decreases as it goes in the left-right direction on the paper surface). Here, the amount of retardation of light is obtained by multiplying the thickness of the retardation layer by the birefringence of the retardation layer, and therefore, as in the optical element 111, the retardation layer 5 has a single opening. When a significant difference occurs in thickness, a difference occurs in the amount of phase difference control of polarized light that passes through the opening, resulting in a difference in the amount of light that passes through the polarizing plate on the viewer side. To do. The present inventors have obtained the knowledge that the problem 2 is caused by the reason as described above, and the thickness of the intermediate layer in the 90% region inside the intermediate layer opening region is determined as follows. Problem 2 was solved by forming the thickness D in the central portion a so as to be not less than 0.9D and not more than 1.1D. In the present specification, as described above, the thickness of the intermediate layer in the 90% region inside the intermediate layer opening region is in the range of 0.9D to 1.1D with respect to the thickness D in the central portion a of the intermediate layer. May be simply expressed as “the thickness of the intermediate layer is substantially equal”.

The thickness D of the intermediate layer in the present invention is a region where the intermediate layer overlaps with the opening when viewed from above in a direction perpendicular to the substrate surface (hereinafter also referred to as “intermediate layer opening region”). It is distinguished from a region overlapping with the light shielding portion (hereinafter also referred to as “intermediate layer light shielding portion region”), and refers to the thickness of the intermediate layer measured at the center of one intermediate layer opening region. When measuring the film thickness D of the intermediate layer in one optical element, the optical element is measured by measuring the film thickness of the central part in the arbitrarily selected five intermediate layer opening regions and calculating the average thereof. The film thickness D of the intermediate layer in FIG. Specifically, for the measurement of the thickness, any five intermediate layer opening regions are selected, and from the light-transmitting substrate surface to the surface of the intermediate layer at the center of each intermediate layer opening region. This is done by measuring the distance and calculating the value indicated by the average value. When measuring the thickness of the intermediate layer from the cross section of the completed optical element, cut the optical element at a cross section including the central portion of the intermediate layer opening region, and observe the electron micrograph (SEM). Can be measured. Further, during the formation of the optical element, it is obtained by actually measuring the thickness of the intermediate layer with a stylus type film thickness meter in a line including the central portion of the intermediate layer opening region. In any measurement, in any one sample, any five intermediate layer opening regions are selected, and the average value of the data measured in the center of each intermediate layer opening region is calculated. A film thickness can be obtained. Examples of the stylus film thickness meter include SURFCORDER ET400L manufactured by Kosaka Laboratory.

The reason why the lower limit of the thickness of the intermediate layer is 0.5 μm or more will be explained in relation to the thickness of the light shielding portion. That is, since the light shielding portion provided in the optical element is an area provided for shielding light transmitted through the optical element, there is an appropriate thickness for achieving the purpose. It is generally understood that an OD value (Optical Density, Absorbance, absorbance) of about 3.0 to 4.0 is necessary for a light shielding part to sufficiently shield light in an optical element. Although it varies depending on the light shielding part forming material used, the above OD value is sufficiently exerted if the light shielding part has a thickness of 0.6 μm or more, preferably 0.7 μm or more, more preferably 1 μm or more. Therefore, the optical element of the present invention is intended for the case where the light-shielding portion is designed with an appropriate thickness, that is, 0.6 μm or more, 0.7 μm or more, and further 1.0 μm or more. The present inventors have studied the thickness of the intermediate layer that can achieve the object, and found that the thickness is 0.5 μm or more.

In addition, the upper limit of the thickness of the intermediate layer in the present invention is not particularly limited in terms of achieving the intended purpose of the present invention. However, it should be noted that making the intermediate layer thicker than necessary may increase the thickness of the optical element unnecessarily or increase the cost by increasing the intermediate layer forming material. Therefore, if the thickness of the intermediate layer is 0.5 μm or more and the film thickness in the intermediate layer opening region is approximately equal, the type of intermediate layer forming material used or formed The thickness may be determined appropriately in consideration of other components such as the thickness of the light shielding portion and the retardation layer forming material.
In the present invention, the thickness of the intermediate layer is made sufficiently thicker than the thickness of the light shielding portion, or the thickness of the intermediate layer is made larger than the thickness of the light shielding portion, and the surface of the intermediate layer ( It is not always necessary to flatten the surface on the side opposite to the substrate. That is, as shown in FIG. 1 or FIG. 2, when the thickness of the intermediate layer is formed to be equal to or less than the thickness of the light shielding portion, or as shown in FIG. 3, the thickness of the intermediate layer is larger than the thickness of the light shielding portion. However, in any case where the surface of the intermediate layer has irregularities, the thickness of the intermediate layer is 0.5 μm or more, and the film thickness in the opening area of the intermediate layer is substantially equal. If so, the above problems 1 and 2 can be solved sufficiently. However, the above description is not intended to exclude an optical element having an intermediate layer whose surface is flattened from the present invention.

In the present invention, the thickness of the light-shielding portion is as described above, in the cross section that appears when cutting at an angle perpendicular to the substrate surface through the central portion in one intermediate layer opening region. Select any five of the plurality of light shielding parts appearing in a convex shape when the direction, respectively, measure the distance from the base material surface to the highest convex part of the selected light shielding part, A value calculated by averaging these values. Since specific measurement can be performed in the same manner as the above-described intermediate layer, the description thereof is omitted in this paragraph.

Below, the detail of the optical element of this invention is demonstrated in order for every structural layer.
[Light transmissive substrate]
The light-transmitting base material used in the present invention may be composed of a single layer by a single substrate forming material, or may be composed of multiple types of substrate forming materials. The light transmittance of the light transmissive substrate can be selected as appropriate. As a specific example of the light-transmitting base material, it is preferable to use an inorganic base material such as glass, silicon, or quartz, but it can also be configured from the organic base materials listed below. Examples of the organic substrate include those made of acrylic such as polymethyl methacrylate, polyamide, polyethylene terephthalate, triacetyl cellulose, polycarbonate, or thermoplastic polyimide, but those made of general plastics can also be used. is there. In particular, when it is planned to be used in a liquid crystal display device, it is preferable to use alkali-free glass as the substrate. The thickness of the light-transmitting substrate is not particularly limited, and for example, a thickness of about 50 μm to several mm is generally used depending on the application.

[Shading area]
The light-shielding region in the present invention is a transfer in which a light-shielding part having a predetermined shape and a predetermined pattern is printed directly or indirectly on the surface of a light-transmitting base material, which is a target surface, using a resin composition containing a black colorant. It can be configured by an opening formed by a method and partitioned by this and the light shielding portion. Or you may form a light-shielding part by performing application | coating, pattern exposure, and image development using the coating-type photosensitive resin composition containing a black coloring agent. A rectangular lattice shape is generally adopted as the formation pattern of the light shielding portion, but the pattern such as a stripe shape or a triangular lattice shape can be appropriately determined by design change. Further, as described above, the thickness of the light shielding portion is desirably 0.6 μm or more, preferably 0.7 μm or more, more preferably 1.0 μm or more in order to exhibit a sufficient OD value in the optical element. The upper limit is not particularly specified, but is generally about 2 μm.

[Middle layer]
As described above, the intermediate layer in the present invention may be an isotropic and light-transmitting layer. Specifically, a conventionally known alignment film can be used for forming a transparent resin layer or a retardation layer. In the case of forming an optical element that is planned to be used as a substrate on one side of a transflective liquid crystal display device, the retardation layer is not formed in the transmissive part region, but selectively in the reflective part region. Therefore, the problem of light leakage and phase difference control non-uniformity, which are problems in the present invention, occurs in the light shielding region overlapping the region where the phase difference layer is formed. Therefore, in such a case, the intermediate layer may be formed at least in a region where the phase difference layer is to be formed, but a light shielding region is formed in order to save labor in the pattern formation process of the intermediate layer. An intermediate layer may be formed on substantially the entire surface of the substrate, and a retardation layer may be patterned on the upper surface.

As described above, the intermediate layer in the present invention needs to be formed to have substantially the same thickness, particularly in the intermediate layer opening region. In the intermediate layer, the method of forming the layer so that the thickness in the intermediate layer opening region is substantially equal is not particularly limited. For example, a high molecular weight material or a material whose viscosity is adjusted to be sufficiently high is used as the intermediate layer forming material. It is possible to form an intermediate layer having a desired thickness by applying this intermediate layer forming material to the base material surface on which the light shielding region is formed to form a coating film. The viscosity of the intermediate forming material is not generally specified depending on the compatibility with the contained material, the light shielding part forming material, and the like, but preferably has a viscosity of 10 cp or more to form a desired intermediate layer. Can do. However, the above does not prohibit the use of an intermediate layer forming material of less than 10 cP when forming the intermediate layer in the present invention.

The transparent resin layer can be formed using a protective layer forming material that is generally used when forming a protective layer in an optical element. For example, it can be formed using a resin composition containing a photosensitive resin. More specifically, a transparent resin layer-forming material containing at least a polymerizable transparent resin material, a photopolymerization initiator, and a solvent, or a transparent resin containing an alkali-soluble polymer, a polyfunctional polymerizable monomer, a photopolymerization initiator, and a solvent. A layer forming material can be mentioned. Examples of the polymerizable transparent resin material include light-transmitting resin materials that can be polymerized by irradiating with ionizing radiation such as acrylic or urethane resins or acrylic or urethane monomers. The photopolymerization initiator is not particularly limited as long as it is a material having a decomposition absorption wavelength at a wavelength of 250 nm to 400 nm and used for a normal resist ink. Moreover, as said solvent, if it is a solvent used for normal resist inks, such as propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, diethylene glycol dimethyl ether, cyclohexanone, it can use without a restriction | limiting in particular. Further, the alkali-soluble polymer is not particularly limited as long as it is an acid-soluble polymer by introducing an acidic group into the side chain, but in general, (meth) acrylic acid and methyl methacrylate, or / and various monomers Are used. Furthermore, as a polyfunctional polymerizable monomer, those having 2 to 6 (meth) acrylate groups are used, and commercially available products include M-208 (manufactured by Toagosei Co., Ltd.) and M-315 (manufactured by Toagosei Co., Ltd.). , M-450 (manufactured by Toagosei Co., Ltd.), SR-399E (manufactured by Nippon Kayaku Co., Ltd.), KAYARAD DPHA (manufactured by Nippon Kayaku Co., Ltd.), and the like.
In the case of using the above-described materials, for example, the viscosity may be adjusted so that the formed layer is appropriately formed as the intermediate layer of the present invention. For example, the above-described material may be adjusted to increase the viscosity by increasing the solid content concentration than the general protective layer forming material concentration or increasing the polymer concentration. The weight average molecular weight of the polymer is preferably 2000-100000, more preferably 5000-50000. As a viscosity adjusting method, there is a method using a solvent having a high viscosity.

Moreover, as another intermediate | middle layer forming material, a polyamic acid and a soluble polyimide can be mentioned. The weight average molecular weight of these materials is preferably 2000-100000, more preferably 5000-50000. Examples of the polyphilic acid and soluble polyimide solvent include N-methylpyrrolidone, γ-butyrolactone, N, N-dimethylacetamide, N, N-dimethylformamide, and the like. Other solvents for the purpose of improving coatability include propylene glycol monoalkyl ethers such as propylene glycol monobutyl ether and ethylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether (butyl cellosolve). These solvents may be used alone or in combination of two or more.

The transparent resin layer is made of a material as described above, and is applied by appropriately selecting a conventionally known method such as a spin coating method, a die coating method, an ink jet method, or flexographic printing on the base material surface on which the light shielding region is formed. When a coating film is formed and then the resin used is a photosensitive resin, the coating film can be exposed to form an intermediate layer. Heat treatment may be performed before and after exposure. In addition, when creating an optical element for a transflective liquid crystal display device, etc., when it is desired to form a pattern on the intermediate layer, the photoresist layer is partially exposed and then developed to remove unnecessary portions. A pattern may be formed.

Further, when an alignment film for forming a retardation layer is formed as an intermediate layer, it can be formed by the same material and the same method as those of conventionally known alignment films except that the thickness is taken into consideration. That is, as the alignment film material, generally, an alignment resin such as polyimide is used. As commercial products known as alignment film materials, the alignment film material (Sunever) manufactured by Nissan Chemical Co., Ltd., the alignment film material (QL, LX series) manufactured by Hitachi Chemical DuPont Microsystems, Inc., manufactured by JSR Corporation Alignment film material (AL series), an alignment agent (Rixon aligner) manufactured by Chisso Corporation.

The alignment film is formed by applying the above-described material to the base surface on which the light-shielding region is formed or the upper surface on which another intermediate layer such as a transparent resin layer is formed by the above-described conventionally known coating method. After forming a coating film and then heating it using a heating device such as an oven, it can be produced by rubbing or photo-aligning the coating film surface. However, the rubbing process and the photo-alignment process may not necessarily be performed. The alignment film can also be formed by obliquely depositing silicon oxide on the alignment film forming substrate surface. In the case where only the alignment film is formed as the intermediate layer, the alignment film needs to be formed with a thickness of 0.5 μm or more. On the other hand, if the alignment film is formed in combination with another intermediate layer such as a transparent resin layer and the other alignment film is formed with a thickness of 0.5 μm or more, the alignment film is conventionally The film may be formed with a thickness generally adopted as the alignment film, for example, about 0.05 μm to 0.15 μm.

[Phase difference layer]
The retardation layer in the present invention is a layer having a function of controlling the phase difference of light transmitted through the optical element, and is formed in the optical element.
The retardation layer in the present invention can be composed of a polymerizable liquid crystal compound capable of thermal polymerization or ionizing radiation polymerization. More specifically, a coating film is formed by applying a retardation layer forming resin composition containing a polymerizable liquid crystal compound to the surface of a base material on which an intermediate layer is formed, and the polymerizable liquid crystal present in the coating film A phase difference layer can be formed by orienting molecules in a desired direction and then immobilizing them by polymerization while maintaining the orientation state. In the present specification, the compound capable of ionizing radiation polymerization means a compound that undergoes a polymerization reaction when irradiated with ionizing radiation. In this specification, the ionizing radiation includes both electromagnetic waves including ultraviolet rays and particle beams having energy quanta that can polymerize molecules including electron beams. Alternatively, the retardation layer in the present invention may be formed using a polymer instead of the polymerizable liquid crystal compound described above. For example, the retardation layer may be formed by applying a highly planar polymer material having a polyimide structure having self-orientation performance to the substrate surface.

The method of applying the resin composition for forming a retardation layer to the substrate surface is the same as a conventionally known application method that can be performed when the resin composition for forming the transparent resin layer is applied to the substrate surface. . In particular, the spin coating method is preferable from the viewpoint that it is easy to apply the liquid crystalline composition uniformly. Before applying the retardation layer, UV cleaning or plasma treatment may be performed depending on the underlayer, and the wettability of the alignment film surface to which the liquid crystal composition liquid is to be applied may be increased in advance.

As described above, after forming the coating film by applying the resin composition for forming the retardation layer to the substrate surface, subsequently heating the coating film together with the substrate, removing the solvent contained in the coating film, The polymerizable liquid crystal compound present in the coating film is heated up to a temperature at which the liquid crystal phase appears and is aligned in a desired direction. The heating temperature and time may vary depending on the characteristics of the liquid crystal compound contained in the liquid crystal composition, but is usually 60 ° C. to 120 ° C. for several minutes to 30 minutes.

Then, while maintaining the liquid crystal compound oriented in a certain direction, the liquid crystal compound is fixed by irradiation with ionizing radiation and polymerization. In general, ultraviolet rays having a wavelength of about 200 to 500 nm are selected as the ionizing radiation, and are irradiated by a high-pressure mercury lamp, a xenon lamp, a metal halide lamp, or the like. At this time, the amount of ultraviolet light irradiation varies depending on the type and composition of the polymerizable liquid crystal compound and the type and amount of the photopolymerization initiator, but is usually in the range of about 10 to 3000 mJ / cm ² .

Moreover, when pattern-forming a phase difference layer, you may form a phase difference layer partially in a base-material surface by the photolithographic method. That is, a resin composition for forming a retardation layer is applied to the substrate surface to form a coating film, and ionizing radiation is irradiated through a photomask formed in a predetermined pattern, so that the polymerization reaction of the liquid crystal compound is sufficient. And a portion where the polymerization reaction of the liquid crystal compound is insufficient. Thereafter, the liquid crystal composition in which the polymerization reaction of the liquid crystal molecules is insufficient and uncured is immersed in a solution that can be dissolved, so that the portion of the coating film where the polymerization reaction of the liquid crystal molecules has not progressed from the substrate surface. By removing (development processing), the retardation layer can be patterned.

The kind of the retardation layer that can be formed by designing the alignment direction of the polymerizable liquid crystal compound constituting the retardation layer to a desired direction is a so-called positive A plate, positive C plate, negative C plate, etc. It is possible to select from. In general, a retardation layer that is selectively patterned in a reflection region in a transflective liquid crystal display device is formed as a so-called positive A plate. In a transmissive liquid crystal display device or the like, the retardation layer formed for optical compensation can be formed as a so-called positive C plate in addition to the positive A plate, for example, or as another aspect. It can also be formed as a so-called negative C plate. Furthermore, a positive A plate, a positive C plate, and a negative C plate can be stacked in any combination in one optical element. It is understood that the positive A plate generally has an optical axis substantially parallel to the substrate surface and has a positive refractive index anisotropy. “Substantially parallel to the material surface” means that the phase difference at 589 nm measured from the front (0 °) is 100 (change the measurement angle along the slow axis of the retardation layer) ± 45 If the difference in phase difference measured from 0 is zero, it is understood that the optical axis is parallel to the substrate, but if the difference in phase difference is about 25, it is acceptable. The positive C plate is generally understood to have an optical axis that is substantially perpendicular to the substrate surface and has a positive refractive index anisotropy. It is understood that the optical axis is substantially perpendicular to the substrate surface and has negative refractive index anisotropy.

As the polymerizable liquid crystal compound used for forming the retardation layer, a rod-like polymerizable liquid crystal compound having a rod-like molecular structure or a so-called discotic polymerizable liquid crystal compound having a disc-like molecular structure is used. it can. In particular, rod-like polymerizable liquid crystal compounds can be preferably used, and for example, those disclosed in JP-T-10-508882 can be used. As a polymerizable nematic liquid crystal molecule shown as an example of a more specific rod-like polymerizable liquid crystal compound, for example, at least one polymerizable group such as a (meth) acryloyl group, an epoxy group, an oxetane group or an isocyanate group is contained in one molecule. Examples thereof include monomers, oligomers, polymers and the like. Further, as such a rod-like polymerizable liquid crystal compound, more specifically, a compound represented by the general formula (1) shown in the following chemical formula 1 or a compound represented by the general formula (2) shown in the following chemical formula 2 Among them, one kind or a mixture of two or more kinds, one kind or a mixture of two or more kinds of compounds shown in Chemical Formula 3 or Chemical Formula 4, or a combination of these can be used.

In the general formula (1) shown in Chemical Formula 1, each of R ¹ and R ² represents hydrogen or a methyl group, but at least R ¹ is required to broaden the temperature range in which the crosslinkable liquid crystal molecules exhibit a liquid crystal phase. And R ² is preferably hydrogen, more preferably both. X in the general formula (1) and Y in the general formula (2) shown in Chemical Formula 2 are any of hydrogen, chlorine, bromine, iodine, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group, or a nitro group. Although it may be, it is preferably a chlorine or methyl group. Further, a and b indicating the chain length of the alkylene group between the (meth) acryloyloxy group and the aromatic ring at both ends of the molecular chain of the general formula (1), and d and e in the general formula (2) are individually Although an arbitrary integer can be taken in the range of 2-12, it is preferable that it is the range of 3-10, and it is further more preferable that it is the range of 4-8. The compound (I) of the general formula (1) in which a = b = 0 or the compound (II) of the general formula (2) in which d = e = 0 has poor stability and is easily hydrolyzed, and the compound (I) or (II) itself has high crystallinity. Further, the compound (I) of the general formula (1) or the compound (II) of the general formula (2) in which a and b or d and e are each 13 or more has a low isotropic phase transition temperature (TI). For this reason, both of these compounds have a narrow temperature range (temperature range for maintaining the liquid crystal phase) that stably exhibits liquid crystallinity, and as liquid crystal compounds contained in the liquid crystal composition of the present invention. It is not preferable to use.

In addition, a conventionally well-known additive can be used suitably as an additive contained in a liquid-crystal composition with the said polymeric liquid crystal compound. More specific examples of the additive include a photopolymerization initiator, a thermal polymerization initiator, a surfactant, a chiral agent, a sensitizer, and a silane coupling agent.

The retardation (retardation) of the retardation layer can be measured using a known retardation measuring device or microspectrophotometer. Specifically, it can be measured by RETS-1250VA (manufactured by Otsuka Electronics Co., Ltd.).
In another method, it can be calculated by a rotational analyzer method using a microspectrophotometer OSP-SP200 manufactured by Olympus and two polarizing plates. Specifically, first, in a microspectrophotometer, the two polarizing plates are arranged one above the other so that the optical axes of the two polarizing plates are parallel, and the retardation layer of the retardation layer is aligned with respect to the optical axis of the polarizing plate. The optical element is sandwiched between two polarizing plates so that the optical axis forms an angle of 45 °, and the spectral transmittance of light that is incident from the lower polarizing plate and transmitted through the upper polarizing plate is measured. Next, by rotating the upper polarizing plate by 90 °, the two polarizing plates are brought into a state where their optical axes cross each other, and the spectral transmittance of light similar to the above is measured. Based on the measurement result, the phase difference for the light passing through each pixel is calculated by the rotational analyzer method.

[Colored layer]
The colored layer in the present invention is a layer formed when providing an optical element used in a liquid crystal display device capable of color display. Therefore, in the case of the present invention which is an optical element for monochrome display, the colored layer is not an essential component. The colored layer is generally a full-colorable colored layer composed of three colored regions of red, green, and blue, but the colored region may be a single color, two colors, or four or more colors. When a colored layer is composed of two or more colored regions, each colored region may be arranged in a strip shape for each color so as to cover the opening region, or a mosaic type or triangle for each opening portion. The pattern may be formed in various arrangements such as a mold.

The colored layer is configured by forming a pattern for each colored region using a resin composition in which a colorant forming each colored region is dissolved or dispersed, preferably a fine pigment is dispersed. More specifically, it is formed by preparing an ink composition colored in a predetermined color and printing for each color pattern, or a paint type photosensitive resin composition containing a colorant of a predetermined color. And formed by photolithography. The colored layer is generally formed with a thickness in the range of about 1 μm to 5 μm.

In the above description, it has been described that a colored layer may be optionally formed after the retardation layer, but in the above description, another layer is formed between the retardation layer and the colored layer in the optical element of the present invention. It is not intended to exclude doing. For example, an isotropic and light-transmitting flattening layer for flattening the substrate surface can be provided on the retardation layer.

Next, a liquid crystal display device manufactured using the optical element of the present invention will be described by taking a transflective liquid crystal display device as an example. 6 to 8 are drawings showing an embodiment of the optical element of the present invention that can be used as a substrate on one side of a transflective liquid crystal display device. FIG. 6 is a top view of the optical element 31 of the present invention that can be used as a substrate on one side of a transflective liquid crystal display device, as observed from the upper surface side in the vertical direction. In addition, the up-down direction in the structure of the optical element 31 means the up-down direction when the light-transmitting base material surface is set to the down direction.

In the optical element 31, a light shielding region 32 that is patterned so as to provide a transmission part 33 and a reflection part 34 is formed on a light-transmitting base material (not shown). Note that both the transmission part 33 and the reflection part 34 are understood as openings in the optical element of the present invention. Then, a transparent resin layer, which is an intermediate layer (not shown), and an alignment film are sequentially formed on substantially the entire surface of the substrate on which the light shielding region 32 is provided, and then a position covering the reflecting portion 34 and in a strip shape in the left-right direction on the paper surface. The retardation layer 35 is patterned, and then the red colored region 36, the green colored region 37, and the blue colored region 38 are formed in parallel in a strip shape in the up and down direction on the paper surface, and the optical element 31 is completed. Note that the red colored region 36, the green colored region 37, and the blue colored region 38 constitute a colored layer.

FIG. 7 is a cross-sectional view taken along line XX of the optical element 31 shown in FIG. As shown in FIG. 7, in the optical element 31, a light shielding region 32 including a light shielding portion 32a and an opening 32b is formed on the upper surface of the light transmissive substrate 39, and the light shielding portion 32a shown in FIG. Any space (that is, the opening 32b) corresponds to the transmission part 34. And the transparent resin layer 40 which is an intermediate | middle layer, and the alignment film 41 are provided in order on the base-material surface in which the light shielding area | region 32 was formed. The transparent resin layer 40 is a layer having a sufficient thickness (that is, a thickness of 0.5 μm or more) as an intermediate layer of the present invention, while the alignment film 41 has the same thickness (that is, 0. About 1 μm).
Further, in the region S which is the inner 90% region in the intermediate layer opening region A overlapping the opening 32b when observed from the vertical direction of the base material 39, the thickness of the intermediate layer is the central portion of the intermediate layer opening region. It is formed so as to be in the range of 0.9D to 1.1D with respect to the thickness D in a.

Since the optical element 31 is an optical element for a transflective liquid crystal display device, the cross-sectional configuration differs from that shown in FIG. 7 when the cutting angle is changed. That is, FIG. 8 is shown as a cross-sectional view of the optical element 31 shown in FIG. As is clear from FIG. 8, in the YY cross section, the transmissive portions 33 and the reflective portions 34 are alternately arranged, and the retardation layer 35 is selectively formed in the reflective portion 34 region. Further, in view of the intended purpose of the present invention, the transparent resin layer 40 and the alignment film 41 that are intermediate layers may be provided at least on the reflecting portion 34 and on the lower surface of the retardation layer 35. In the element 31, an embodiment is adopted in which the transparent resin layer 40 and the alignment film 41 are provided on substantially the entire surface of the base material without pattern formation.

Next, a transflective liquid crystal display device 51 using the optical element 31 shown in FIG. 6 as a substrate on one side will be described with reference to FIG. FIG. 9 is an exploded perspective view for showing the relative positional relationship of each layer, and each component layer in an actual liquid crystal display device is not separated as shown in the figure.

In the transflective liquid crystal display device 51, an optical element 31 used as a display side substrate is used, and on the other hand, a thin film transistor (TFT) is provided as a substrate facing this (a TFT is not shown). On one surface of the base material 62, there is a reflection plate 63 provided in addition to the position of the reflection portion 34 of the optical element 31 (the non-installation area of the reflection plate 63 corresponds to the transmission portion 33 through which light is transmitted. Furthermore, there is a counter substrate 61 in which a transparent electrode (not shown) made of a transparent conductive film such as ITO is laminated, and an alignment film (not shown) is formed so as to cover the transparent electrode. Used. Further, the optical element 31 and the counter substrate 61 are each 135 ° counterclockwise with respect to the direction from the front to the back of the drawing on the surfaces of the base 39 and the base 62 opposite to the surfaces facing each other. A polarizing plate 52a having a light absorption axis in the direction and a polarizing plate 52b having a light absorption axis of 45 ° counterclockwise with respect to the direction from the front to the back of the drawing.

A liquid crystal layer 53 made of a driving liquid crystal material is provided between the optical element 31 and the counter substrate 61 facing each other, and a back surface for providing light transmitted through the transmission portion 33 is provided outside the counter substrate 61. A transflective liquid crystal display device 51 having a light (not shown) and having a driving method of VA (Vertical Aligned) mode is completed. Although not shown, in the case of a VA mode liquid crystal display device, a transparent electrode is further provided between the liquid crystal layer 53 and the colored layer composed of the red colored region 36, the green colored region 37, and the blue colored region 38. A membrane may be provided. Furthermore, a structure made of a resin composition for regulating alignment, driving voltage, and cell gap, and an alignment film may be provided on the transparent electrode. However, the transflective liquid crystal display device 51 described above is only one embodiment of the liquid crystal display device of the present invention, and does not limit the liquid crystal display device of the present invention. The liquid crystal display device of the present invention includes other types of liquid crystal display devices such as a transmissive liquid crystal display device and a reflective liquid crystal display device, and the transflective liquid crystal display device of the present invention has a VA mode. The liquid crystal display device is not limited to the liquid crystal display device, and is appropriately used for a liquid crystal display device that adopts another driving method such as a TN (twisted nematic) mode or an IPS (in plane switching) mode.

In order to carry out Examples and Comparative Examples, a low expansion coefficient non-alkali glass plate (Corning 1737 glass 100 mm × 100 mm, thickness 0.7 mm) was prepared in advance as a light-transmitting substrate and subjected to a cleaning treatment. did. Further, as shown below, a composition for forming a light shielding region (light shielding portion), a colored region, an intermediate layer, and a retardation layer (photoresist) was prepared.

(Preparation of composition for forming light shielding region (light shielding portion), intermediate layer, and retardation layer)
A pigment dispersion type photoresist uses a pigment as a coloring material, adds beads to a dispersion composition (containing a pigment, a dispersant, and a solvent), disperses for 3 hours with a disperser, and then removes the beads. A clear resist composition (containing polymer, monomer, additive, initiator and solvent) is mixed. Its composition is shown below. A paint shaker (manufactured by Asada Tekko Co., Ltd.) was used as the disperser.

The composition of the photoresist for forming the light shielding region (light shielding portion) is as follows.
Black pigment: 14.0 parts by weight (manufactured by Dainichi Seika Kogyo Co., Ltd., TM Black # 95550)
・ Dispersant: 1.2 parts by weight (manufactured by Big Chemie, Dispersic 111)
・ Polymer 2.8 parts by weight (manufactured by Showa Polymer Co., Ltd., (meth) acrylic resin, product number: VR60)
・ Monomer: 3.5 parts by weight (manufactured by Sartomer, polyfunctional acrylate, product number: SR399)
・ Additive (dispersibility improver): 0.7 parts by weight (manufactured by Soken Chemical Co., Ltd., Chemtry L-20)
Initiator: 1.6 parts by weight (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1)
・ Initiator: 0.3 parts by weight (4,4′-diethylaminobenzophenone)
・ Initiator: 0.1 parts by weight (2,4-diethylthioxanthone)
・ Solvent: 75.8 parts by weight (ethylene glycol monobutyl ether)

The composition of the red colored region forming photoresist is as follows.
・ Red pigment (CIPR254) 3.5 parts by weight (Ciba Specialty Chemicals Co., Ltd., Chromophthal DPP Red BP)
・ Yellow pigment (CI PY139): 0.6 part by weight (manufactured by BASF, Paliotor Yellow D1819)
・ Dispersant: 3.0 parts by weight (manufactured by Zeneca Corporation, Solsperse 24000)
-Polymer 1 (see below)-5.0 parts by weight-Monomer-4.0 parts by weight (manufactured by Sartomer, polyfunctional acrylate, product number: SR399)
・ Initiator: 1.4 parts by weight (Ciba Geigy Co., Ltd., Irgacure 907)
Initiator: 0.6 parts by weight (2,2′-bis (o-chlorophenyl) -4,5,4 ′, 5′-tetraphenyl-1,2′-biimidazole)
・ Solvent: 85.4 parts by weight (propylene glycol monomethyl ether acetate)
The polymer 1 contains 2 moles of benzyl methacrylate: styrene: acrylic acid: 2-hydroxyethyl methacrylate = 15.6: 37.0: 30.5: 16.9 (molar ratio) of 100 mol% of the copolymer. -16.9 mol% of methacryloyloxyethyl isocyanate is added, and the weight average molecular weight is 42500. The same applies to the following description.

The composition of the green colored region forming photoresist is the same as that of the red colored region forming photoresist except that the following contents are adopted instead of the red pigment and the yellow pigment in the composition of the red colored region forming photoresist. is there.
Green pigment (C.I.PG7) 3.8 parts by weight (manufactured by Dainichi Seika, Seika Fast Green 5316P)
・ Yellow pigment (CI PY139): 2.2 parts by weight (manufactured by BASF, Paliotor Yellow D1819)

The composition of the blue colored region forming photoresist is a red colored region forming photo, except that the following contents are adopted instead of the red pigment, yellow pigment, and dispersant in the composition of the red colored region forming photoresist. It is the same as the resist.
・ Blue pigment (CI PB15: 6): 4.6 parts by weight (manufactured by BASF, heliogen blue L6700F)
・ Purple pigment (CI PV23): 1.4 parts by weight (manufactured by Clariant, Foster Palm RL-NF)
Pigment derivative: 0.6 parts by weight (Zeneca Co., Ltd., Solsperse 12000)
・ Dispersant: 2.4 parts by weight (manufactured by GENEKA CORPORATION, Solsperse 24000)

The composition of the transparent resin layer forming photoresist 1 as an intermediate layer is as follows. The viscosity of the transparent resin layer forming photoresist 1 having the composition shown below was 11.8 cP. The viscosity of the photoresist was measured with a VISCOMATE MODEL VM-1G viscometer manufactured by YAMAICHI ELECTRONICIS. The viscosity of a photoresist described later is also measured with a similar viscometer.
・ Monomer: 10.0 parts by weight (SR399, manufactured by Sartomer Co., Ltd.)
-Polymer 1 ... 14.0 parts by weight-Initiator ... 2.0 parts by weight (Ciba Geigy Co., Ltd., Irgacure 907)
・ Initiator: 1.0 part by weight (Ciba Geigy Co., Ltd., Irgacure 365)
・ Solvent 1 ... 51.0 parts by weight (N-methylpyrrolidone)
・ Solvent 2 ... 11.0 parts by weight (γ-butyrolactone)
・ Solvent 3 ... 11.0 parts by weight (butyl cellosolve)

The composition of the transparent resin layer forming photoresist 2 as the intermediate layer is as follows. The viscosity of the transparent resin layer forming photoresist 2 having the composition shown below was 4.4 cP.
Monomer: 14.0 parts by weight (SR399, manufactured by Sartomer Co., Ltd.)
-Polymer 1 ... 10.0 parts by weight-Initiator ... 2.0 parts by weight (Ciba Geigy Co., Ltd., Irgacure 907)
・ Initiator: 1.0 part by weight (Ciba Geigy Co., Ltd., Irgacure 365)
・ Solvent: 73.0 parts by weight (propylene glycol monomethyl ether acetate)

The composition of the liquid crystal composition liquid for forming the retardation layer is as follows.
Polymerizable liquid crystal material: 28.75 parts by weight (polymerizable liquid crystal compound in which a and b are 6 and X is CH ₃ in the above chemical formula 2)
Photopolymerization initiator: 1.25 parts by weight (Ciba Geigy Co., Ltd., Irgacure 907)
・ Solvent: 70.0 parts by weight (diethylene glycol dimethyl ether)

[Example 1]
Using the light-transmitting substrate and each composition shown above, as shown below, a light shielding region, a transparent resin layer as an intermediate layer, an alignment film, and a retardation layer are formed in this order to form an optical element. Example 1 was adopted. First, the light-shielding region forming photoresist is applied onto the washed light-transmitting substrate by spin coating, the solvent is reduced by drying under reduced pressure, prebaked at 80 ° C. for 3 minutes, and a photomask is used. Exposure (100 mJ / cm ² ), followed by spray development using a 0.05% KOH aqueous solution for 60 seconds, followed by post-baking at 230 ° C. for 30 minutes. A light-shielding region was formed by the lattice-shaped pattern and the openings partitioned therewith.

Next, the transparent resin layer-forming photoresist 1 is applied by spin coating on the base material surface on which the light-shielding region is formed as described above, and the solvent is reduced by drying under reduced pressure, and prebaking is performed at 80 ° C. for 3 minutes. Then, it was exposed (100 mJ / cm ² ) using a photomask, post-baked at 230 ° C. for 30 minutes, and a transparent resin layer having a thickness of 0.5 μm was formed as an intermediate layer.

Subsequently, a composition for forming an alignment film (ALSR 1254, manufactured by JSR Corporation) was applied to the surface of the intermediate layer using a spin coater, and then heated in an oven at 230 ° C. for 30 minutes. A 1 μm coating film was formed. And the alignment process was performed by rubbing the said coating film surface using the rubbing apparatus, and the alignment film for phase difference layer formation was formed. Thereafter, the liquid crystal composition liquid for forming the retardation layer is applied onto the alignment film using a spin coater to obtain a liquid crystal coating film. After prebaking at 80 ° C. for 3 minutes, exposure (200 mJ / cm ² ). Subsequently, butt development was performed for 5 seconds using methyl methyl ketone (MEK), followed by post-baking at 230 ° C. for 30 minutes to obtain a retardation layer having a thickness of about 1.5 μm. The retardation layer was designed to have a retardation value of about 200 nm (a value smaller than λ / 2). The retardation layers in Examples and Comparative Examples described below were also designed with the same retardation value. As described above, an optical element including a light shielding region, an intermediate layer, an alignment film, and a retardation layer on a light transmissive substrate surface was completed. The butt development was performed in order to match the formation conditions with the retardation layer formed by patterning. In Example 1, the retardation layer was not patterned and formed on substantially the entire surface of the substrate. did.

<Measurement of intermediate layer thickness>
In the formation process of Example 1, after each formation process of the light shielding region, the intermediate layer, and the phase difference layer, in the opening parted by the light shielding part formed in a lattice shape, the central part and the light shielding of the two opposite sides In the line passing through the middle of the part, the thickness of the light shielding part, the thickness of the intermediate layer, and the thickness of the retardation layer were measured with a stylus type thickness meter. Then, select the middle part of the intermediate layer from the line indicating the upper surface height of the light shielding region, the line indicating the upper surface height of the intermediate layer, and the line indicating the upper surface height of the retardation layer, and the film thickness is about It was confirmed that the film was formed at 0.5 μm. Further, the distance between adjacent light shielding portions is 100%, and the film thickness in the inner 90% region is in the range of (0.5 × 0.9) μm to (0.5 × 1.1) μm. Value was confirmed. As the stylus type film thickness meter, SURFCORDER ET400L manufactured by Kosaka Laboratory was used.

For reference, a graph showing the results of measuring Example 1 with a stylus type film thickness meter is shown in FIG. In FIG. 10, as is apparent from the graph shown as the line 103 indicating the upper surface height of the light shielding region, the line 104 indicating the upper surface height of the intermediate layer, and the line 105 indicating the upper surface height of the retardation layer, the intermediate layer is In the central part a, it is confirmed that the film thickness is about 0.5 μm. In the graph shown in FIG. 10, the distance between adjacent light shielding portions is 100%, and the film thickness in the inner 90% region is (1 × 0.9) μm to (1 × 1.1) μm. It is confirmed that the value is within the range. From the graph shown in FIG. 10, the rising of the intermediate layer is confirmed at the upper part of the light shielding part, and the shoulder line from the upper surface to the side surface of the light shielding part is completely covered by the intermediate layer due to the influence of the rising. It is understood.

<Evaluation of light leakage>
About Example 1 obtained as mentioned above, light leakage evaluation was performed as follows. First, in a polarizing microscope, the two polarizing plates are arranged vertically so that the optical axes of the two polarizing plates are 90 ° (crossed Nicols), and then Example 1 is sandwiched between the two polarizing plates. When the slow axis of the retardation layer is aligned with one of the optical axes of the two polarizing plates (quenching position) and light is incident in a direction substantially perpendicular to the substrate surface from the lower polarizing plate side, Example 1 Whether or not light leakage was confirmed in the periphery of the contour portion of the light-shielding portion was determined by microscopic observation. As a result, in Example 1, light leakage was not confirmed. FIG. 13 shows a polarizing microscope photograph showing the state of light transmission in the light leakage evaluation of Example 1. In addition, Olympus Corporation BX50 was used for the polarizing microscope. One pixel of Example 1 is about 100 μm × 300 μm. The same applies to Examples and Comparative Examples described later.

<Evaluation of unevenness in phase difference control>
In order to evaluate whether or not the control unevenness of the retardation layer has occurred, in the polarizing microscope, the optical axes of the two polarizing plates are arranged vertically so as to be parallel, and then the two polarizing plates are placed on the two polarizing plates. When Example 1 was sandwiched so that the slow axis of the retardation layer was 45 °, and light was incident in a direction substantially perpendicular to the substrate surface from the lower polarizing plate side, the light was transmitted through one opening. Whether or not the amount of permeation was equal was observed with the naked eye as follows.
That is, when an optical element having a retardation layer designed to have a retardation value smaller than λ / 2 is observed with a polarizing microscope under the above-described conditions, transmitted light is phase-difference as designed in the retardation layer. If controlled, light is uniformly transmitted through the opening and observed with substantially uniform brightness (evaluated as no phase difference control unevenness). On the other hand, when the designed phase difference control is not performed partially in one opening, particularly when the phase difference is partially small, a portion where the amount of transmitted light is larger than the expected amount occurs. Only such a part is visually recognized more brightly (evaluated as having phase difference control unevenness).
In the above evaluation, in Example 1, uniform brightness was observed in one opening, and it was confirmed that there was no phase difference control unevenness. FIG. 14 shows a polarizing microscope photograph in the phase difference control unevenness evaluation of Example 1.
In addition, when the optical axis of the polarizing plate is parallel and the phase difference is from 0 to λ / 2, the amount of transmitted light monotonously decreases as the phase difference increases. Even when the value of the phase difference exceeds λ / 2, the amount of transmitted light does not decrease monotonously with the increase of the phase difference, and unevenness due to the difference in the amount of light can be confirmed.

[Example 2 and Example 3]
An optical element was produced in the same manner as in Example 1 except that the thickness of the formed intermediate layer was 1.0 μm, and this was designated as Example 2. An optical element was produced in the same manner as in Example 1 except that the thickness of the formed intermediate layer was 2.0 μm, and this was designated as Example 3.

[Example 4]
After forming an optical element in the same manner as in Example 1, a green colored region forming photoresist was applied by spin coating on the substrate surface on which the retardation layer was formed, and the solvent was reduced by drying under reduced pressure. Pre-baked at 3 ° C. for 3 minutes, exposed using a photomask (100 mJ / cm ² ), followed by spray development with 0.05% KOH aqueous solution for 60 seconds, followed by post-processing at 230 ° C. for 30 minutes Baking was performed to form a green colored region having a thickness of 1.2 μm in a strip pattern. Similarly, a red colored region and a blue colored region were formed to form a colored layer composed of three colored regions. Thus, an optical element including a light-shielding region, an intermediate layer, an alignment film, a retardation layer, and a colored layer was completed on the light-transmitting substrate surface, and this was designated as Example 4.

About Example 2 thru | or 4, similarly to Example 1, it measures the film thickness of a light-shielding part, an intermediate | middle layer, and a phase difference layer, and measures the film thickness of the center part of an intermediate | middle layer, and 90% of inner side area | regions It was confirmed that the film thickness of the intermediate layer was in the range of 0.9 to 1.1 times the thickness of the central part (not shown).
For Example 2 and Example 3, light leakage evaluation and phase difference control unevenness evaluation were performed in the same manner as Example 1. The results of evaluation of the film thickness of the intermediate layer, light leakage, and phase difference control unevenness are shown in Table 1.

[Comparative Example 1]
An optical element was produced in the same manner as in Example 1 except that no intermediate layer was formed, and this was designated as Comparative Example 1. When Comparative Example 1 was evaluated for light leakage in the same manner as in Example 1, clear light leakage was confirmed so as to border the outline of the light shielding portion. FIG. 15 shows a polarizing microscope photograph showing the light transmission state in the light leakage evaluation of Comparative Example 1. Moreover, when the phase difference control unevenness of Comparative Example 1 was evaluated in the same manner as in Example 1, no phase difference control unevenness was confirmed.

[Comparative Examples 2 to 5]
The transparent resin layer forming photoresist 2 was used as the intermediate layer forming material instead of the transparent resin layer forming photoresist 1, and the intermediate layer thicknesses were 0.1 μm, 0.2 μm, and 0, respectively. An optical element was prepared in the same manner as in Example 1 except that the thickness was set to 5 μm and 1 μm, and Comparative Example 2 to Comparative Example 5 were obtained.

In Comparative Example 2 to Comparative Example 5, the film thickness was measured with a palpation film thickness meter in the same manner as in Example 1. About the film thickness of the center part of an intermediate | middle layer, it summarizes in Table 1 and shows a result. Further, the film thickness of the intermediate layer in the inner 90% region is the smallest in the central part in any of Comparative Examples 2 to 5, and the film thickness increases as it approaches the light shielding part. There was a portion formed thicker than the range of 0.9 to 1.1 times the thickness. About the comparative example 3 and the comparative example 4, the graph which shows the measurement result of a stylus type film thickness meter was shown as FIG. 11, FIG. 12, respectively.

For Comparative Examples 2 to 5, as in Example 1, light leakage evaluation and evaluation of phase difference control unevenness were performed. Comparative Examples 2 and 3 were slightly inferior to Comparative Example 1 in light leakage evaluation, but light leakage was confirmed so as to border the contour of the light shielding portion. On the other hand, in Comparative Examples 4 to 5, no significant light leakage was confirmed in the light leakage evaluation. For reference, polarization microscope photographs showing the state of light transmission in the light leakage evaluation of Comparative Examples 3 and 4 are shown in FIGS. 16 and 18.

Further, in the evaluation of the phase difference control unevenness, in any of Comparative Examples 2 to 5, the peripheral edge is significantly brighter than the internal area in one opening, and the amount of light transmitted in the peripheral area is larger than that in the internal area. It was confirmed that the phase difference control was uneven. For reference, polarization microscope photographs in the phase difference control unevenness evaluation of Comparative Example 3 and Comparative Example 4 are shown in FIGS. 17 and 19.

As shown above, only Examples 1 to 4 showed good results in both the light leakage evaluation and the phase difference control unevenness evaluation.
In Comparative Example 1, since there was no intermediate layer, the tendency of light leakage was remarkable. In Comparative Example 2 or 3, since the formed intermediate layer was thin, the problem of light leakage was not solved, and a significant difference occurred in the film thickness of the intermediate layer in the opening (intermediate layer opening region). The thickness of the retardation layer formed thereon also varies in thickness within one opening. As a result, phase difference control unevenness occurs, and as a result, the amount of transmitted light is not uniform.
In Comparative Example 4 and Comparative Example 5, since the formed intermediate layer was sufficiently thick, the problem of light leakage was solved. However, for the same reason as Comparative Example 2 or 3, the phase difference control was uneven. Has been confirmed to occur. From the above results, the intermediate layer has a film thickness of 0.5 μm or more, and the film thickness measured in the inner 90% region in the intermediate layer opening region is substantially uniform, that is, the film thickness in the central portion. On the other hand, when it is in the range of 0.9 times or more and 1.1 times or less, it has been shown that occurrence of phase difference control unevenness can be satisfactorily prevented.

Further, as described above, when the liquid crystal display device is manufactured using the optical element of the present invention having no light leakage as one substrate, it is provided as compared with the case of using the conventional optical element shown in the comparative example. It is understood that the contrast of the image to be obtained becomes very high, resulting in a high quality image.

1, 21 and 31 Optical elements 2 and 39 of the present invention Light-transmitting substrates 3 and 32 Light-shielding regions 3a and 32a Light-shielding portions 3b and 32b Openings 4 Intermediate layers 5 and 35 Phase-difference layers 6 and 36 Red colored regions 7 and 37 Green colored region 8, 38 Blue colored region 9 Colored layer 12 First intermediate layer 13 Second intermediate layer 22 First intermediate layer 23 Second intermediate layer 33 Transmitting portion 34 Reflecting portion 40 Transparent resin layer 41 Alignment film 51 Semi-transmitting and semi-reflecting Type liquid crystal display device 52 counter substrate 53 liquid crystal layer 101 conventional optical element 102 alignment films 103, 106, 109 lines 104, 107, 110 indicating the upper surface height of the light shielding region lines 105, 108, indicating the upper surface height of the intermediate layer 111 Line A indicating the height of the top surface of the retardation layer

Claims (8)

A light-transmitting base material, a light-shielding region that is patterned to partition the base material into an opening through which light can be transmitted and a light-shielding portion that prevents light transmission, and at least one intermediate layer; , With the retardation layer in this order,
The intermediate layer has a thickness D of 0.5 μm or more,
When viewed in plan from the direction perpendicular to the base material surface, the intermediate layer includes an intermediate layer opening area that is an area overlapping with the opening, and an intermediate layer light shielding area that is an area overlapping the light shielding area. And in the cross section cut through the central portion in one intermediate layer opening region, the intermediate portion in the 90% region inside the straight line passing through the central portion of the intermediate layer opening region and connecting between the adjacent light shielding portions. The thickness of the layer is 0.9D or more and 1.1D or less with respect to the thickness D of the intermediate layer. The optical element according to claim 1, wherein the intermediate layer is a transparent resin layer and / or an alignment film. 3. The optical element according to claim 1, wherein a surface of the intermediate layer opposite to the base material is not flattened. 4. The optical element according to claim 1, wherein the retardation layer is patterned. The optical element according to claim 1, wherein the retardation layer is a positive A plate. The optical element according to any one of claims 1 to 5, further comprising a light-transmitting colored layer directly or indirectly on the retardation layer. A liquid crystal display device comprising two substrates facing each other, a polarizing plate provided on each outer surface of the two substrates, and a liquid crystal layer made of a driving liquid crystal material provided between the two substrates,
As one of the two substrates,
A light-transmitting base material, a light-shielding region that is patterned to partition the base material into an opening through which light can be transmitted and a light-shielding portion that prevents light transmission, and at least one intermediate layer; , With the retardation layer in this order,
The intermediate layer has a thickness D of 0.5 μm or more,
When viewed in plan from the direction perpendicular to the base material surface, the intermediate layer includes an intermediate layer opening area that is an area overlapping with the opening, and an intermediate layer light shielding area that is an area overlapping the light shielding area. And in the cross section cut through the central portion in one intermediate layer opening region, the intermediate portion in the 90% region inside the straight line passing through the central portion of the intermediate layer opening region and connecting between the adjacent light shielding portions. A liquid crystal display device comprising: an optical element having a layer thickness of 0.9D to 1.1D with respect to the thickness D of the intermediate layer. The liquid crystal display device according to claim 7, wherein the liquid crystal display device is a transflective liquid crystal display device.