JP2008242001A - Optical member having phase difference control function, liquid crystal device for transflective type, and manufacturing method of optical member having phase difference control function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device used for a liquid crystal device for transflective type, the optical device having a phase difference layer comprising an isotropic phase part and a liquid crystal phase part while a level difference of the phase difference layer is flattened, and having a phase difference control function. <P>SOLUTION: The optical device used for the liquid crystal device for transflective type has the phase difference layer comprising the liquid crystal phase part formed directly or indirectly on a top surface of the substrate, the isotropic phase part formed adjacently thereto, and a transmissive flattening layer formed covering top surfaces of both the parts and having a flat surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an optical element that gives a phase difference to transmitted light and a manufacturing method thereof. More specifically, the present invention is incorporated in a transflective liquid crystal display device and has a phase difference corresponding to a transmissive display or a reflective display. The present invention relates to an optical element to be applied and a manufacturing method thereof.

  In recent years, with the miniaturization of liquid crystal display devices, liquid crystal display devices have come to be widely used in mobile phones, PDAs and the like. In such a small liquid crystal display device, in addition to power saving, high brightness and high contrast are important issues. From this point of view, development of reflective or transflective liquid crystal display devices for power saving and optical elements for improving the brightness and contrast of these liquid crystal display devices have been developed.

  As one form of such a transflective liquid crystal display device, a liquid crystal display device has been proposed in which a reflective film in which an opening through which light can be transmitted is formed in a metal film such as aluminum functions as a light transflective film. In such a transflective liquid crystal display device, a liquid crystal layer having a ¼ wavelength phase shift when no voltage is applied is sandwiched between a pair of glass substrates, and an array substrate on the backlight side A transparent electrode made of a transparent conductive film such as a semi-transmissive reflective layer and indium tin oxide (hereinafter also simply referred to as “ITO”) is laminated on the inner surface of the transparent glass substrate constituting the substrate, and is oriented so as to cover the transparent electrode. A film is formed. On the other hand, a transparent electrode made of a transparent conductive film such as ITO is formed on the inner surface of the transparent glass substrate constituting the display substrate on the display surface side, and an alignment film is formed so as to cover the transparent electrode. And, on the outer surface side of the upper glass substrate, a quarter wavelength plate and a polarizing plate are arranged in order from the substrate side, and on the outer surface side of the lower glass substrate, a quarter wavelength plate in order from the substrate side, A polarizing plate is provided. The quarter-wave plate is an optical element having a function capable of converting linearly polarized light into substantially circularly polarized light in a certain wavelength band.

  In the transflective liquid crystal display device having the above-described configuration, out of the light from the backlight, the light reflected by the reflective layer is a quarter wavelength disposed below the reflective layer (backlight side). Since the polarization axis of the plate changes and is absorbed by the polarizing plate installed on the lower side (backlight side) of the quarter-wave plate, light cannot be recycled and sufficient luminance cannot be obtained. In addition, the backlight light that has passed through the opening of the reflective layer and transmitted through the quarter-wave plate is circularly polarized light, and half of the transmitted light is absorbed by the polarizing plate provided on the upper substrate. There was a problem that sufficient brightness and contrast could not be obtained.

  In order to solve the above problem, a transflective liquid crystal display device having a structure in which a cell gap between a transmissive portion and a reflective portion is adjusted and a quarter-wave plate is provided only in a reflective layer portion has been proposed. In this liquid crystal display device, since the pair of retardation layers on the backlight side and the display side can be omitted, the display device can be thinned in addition to high luminance.

  As such a transflective liquid crystal display device, for example, in Patent Document 1 below, a transflective liquid crystal display device having a reflective layer patterned in an arbitrary shape, the retardation layer only in the reflective display region. A liquid crystal display device having a structure provided with a (¼ wavelength plate) is disclosed. According to this liquid crystal display device, light from the backlight reflected by the reflective layer can be recycled without being absorbed by the retardation layer. Further, when no voltage is applied, the phase shift of the liquid crystal layer in the transmissive display region is ½ wavelength, and the phase shift of the liquid crystal layer in the reflective display region is ¼ wavelength. By adjusting the cell gap in the reflective display region, good brightness and contrast are realized.

In Patent Document 2 below, when no voltage is applied, the phase shift of the liquid crystal layer in the transmissive display region is ½ wavelength, and the phase shift of the liquid crystal layer in the reflective display region is ¼ wavelength. A liquid crystal display device having a structure in which a cell gap between a transmissive display region and a reflective display region is adjusted so that a phase difference layer (1/2 wavelength plate) is provided only in a color filter portion in the reflective display region is disclosed. Has been. According to this liquid crystal display device, the angle formed by the slow axis azimuth angle of the retardation layer and the transmission axis of the polarizing plate is 20 degrees or more and 25 degrees or less, or 60 degrees or more and 70 degrees or less, so that the reflective portion liquid crystal layer And the retardation layer together form a wide-band quarter-wave plate, so that good brightness and contrast can be realized.
As described above, in order to provide the retardation layer only in the reflective display region, it is also necessary to pattern the retardation layer in a shape corresponding to the reflective layer patterned in an arbitrary shape.

  However, in the method described in Patent Document 1, since the photolithography method is used for patterning the retardation layer, the manufacturing process is complicated, and as a result, it is difficult to manufacture a liquid crystal display device at low cost. . That is, in the photolithography method, a photosensitive resin layer is provided on a retardation layer, the photosensitive resin layer is first patterned into an arbitrary shape, and then the retardation layer is etched using the photosensitive resin layer as a mask. Since the retardation layer that is patterned in an arbitrary shape is formed by locally leaving the retardation layer, a plurality of steps are required for patterning the retardation layer.

  In order to solve the above problem, the applicant of the present invention nowadays a method for forming a retardation layer having a liquid crystal phase patterned without using a photolithography method (hereinafter also simply referred to as “manufacturing method 1”). It discovered (the following patent document 3). In this method, a liquid crystal composition containing a crosslinkable liquid crystal molecule is used as a material. First, the liquid crystal composition is applied to a substrate surface to form a coating film, and the crosslinkable liquid crystal molecules present in the coating film are formed. After aligning in a desired direction, it is covered with a photomask and subjected to pattern exposure to fix crosslinkable liquid crystal molecules located in the exposed area to form a liquid crystal phase. Subsequently, the coating film is heated by a temperature other than the liquid crystal temperature, and the orientation of the crosslinkable liquid crystal molecules that are not immobilized is set in an isotropic phase and is fixed in that state to form an isotropic phase. This is a method of forming a retardation layer composed of a liquid crystal phase and an isotropic phase. According to the method of the present applicant, the retardation layer can be formed easily and inexpensively as compared with the photolithography method.

In addition, in such a transflective liquid crystal cell having a retardation layer composed of a liquid crystal phase and an isotropic phase, the cell gap between the reflective display region and the transmissive display region is adjusted for the same reason as described above. As an adjustment method, a multi-gap layer made of a transparent thermosetting resin or photo-curing resin is formed on the upper surface of the liquid crystal phase, or the manufacturing conditions are adjusted to adjust the thickness of the liquid crystal phase portion, etc. It can be formed by providing a step in the thickness with the phase portion (here, “thickness” means a dimension in the normal direction to the substrate surface).

Japanese Patent No. 3788421 JP 2005-338256 A Japanese Patent Application Laid-Open No. 2006-276697

  When further research was conducted on an optical element including a retardation layer composed of a liquid crystal phase and an isotropic phase, which was shown by the method of production method 1, it was found that display unevenness may occur only in transmissive display. . The inventors' diligent research has found that there is a step on the upper surface of the isotropic phase portion in the retardation layer, and found that this is the cause of the display unevenness.

  That is, the optical element is a driving liquid crystal layer in which the optical element is used as one substrate and is combined with an opposing substrate so that a certain space is secured between the two substrates and the space is filled with a driving liquid crystal material. The liquid crystal device can be manufactured. At this time, since the top surface of the isotropic phase portion is not flat and there is a step, the distance between the two substrates above the isotropic phase portion, that is, the cell gap is not uniform, and display unevenness occurs. I found out there was a problem.

  When a liquid crystal device is manufactured by combining the two substrates, a columnar body is formed on the retardation layer in order to maintain a constant cell gap, which is the distance between the two substrates. A technique of contacting the opposing substrate surface is employed. However, due to the presence of the step on the upper surface of the isotropic phase region, when the columnar body is formed on the upper surface of the isotropic phase region, the height of the upper surface of the columnar body becomes uneven and the contact state on the opposing substrate surface is As a result, the cell gap cannot be maintained well. Therefore, the columnar body can be provided only on the upper surface of the liquid crystal phase region or the upper surface of the multi-gap layer where there is almost no step, and there is a problem that the design of the columnar body is limited.

Hereinafter, the above-described problem will be described in more detail.
FIG. 4 is a top view showing an example of patterning of the liquid crystal phase part and the isotropic phase part of the optical element produced by the production method 1, wherein an alignment film is formed on the transparent glass substrate, and the upper surface thereof is further shown. FIG. 2 is a top view of an optical element in which a phase difference layer 103 including a plurality of liquid crystal phase parts 101 patterned in a stripe pattern and an isotropic phase part 102 formed so as to surround the liquid crystal phase parts 101 is formed. As shown in the figure, the transparent glass substrate and the alignment film are not shown in the figure).

Next, a liquid crystal cell 100 formed using the optical element 110 formed in the pattern shown in FIG. 4 is shown in FIG. FIG. 5 is a schematic cross-sectional view perpendicular to the longitudinal direction of the liquid crystal phase portion 101. In the optical element 110, the alignment film 105 is first formed on the upper surface of the transparent glass substrate 104, and the liquid crystal phase portion 101 and the isotropic phase portion 102 are formed thereon. A multi-gap layer 106 for adjusting the cell gap of the reflective region is laminated on the upper surface of the liquid crystal phase part 101, and a columnar body 107 for maintaining the cell gap is formed on the upper surface of the multi-gap layer 106, thereby optically Element 110 is formed. The liquid crystal cell 100 is formed by combining the optical element 110 as one substrate and a counter substrate 108 facing it. The space secured between the optical element 110 as one substrate and the counter substrate 108 is a space filled with the driving liquid crystal material, and constitutes the driving liquid crystal layer 109.
In the liquid crystal cell 100, cell gaps secured above the liquid crystal phase region 101 corresponding to the reflective region are indicated by arrows a, a ′ and a ″ (hereinafter, “cell gap a”, “cell gap a ′” and “cell gap”). a ″ ”), the cell gap secured between the isotropic phase portion 102 and the counter substrate 108 is indicated by an arrow b (hereinafter referred to as“ cell gap b ”) and an arrow c (hereinafter referred to as“ cell gap c ”). It showed in.

  As shown in FIG. 5, when observed in a cross-sectional view perpendicular to the longitudinal direction of the liquid crystal phase portion 101 of the optical element 100, the cell gap is as follows: cell gap a≈cell gap a′≈cell gap a ″, cell gap b ≠. The cell gap is c. That is, the upper surface of the liquid crystal phase portion 101 is formed to be substantially flat, and the upper surface of the multi-gap layer 106 formed thereon is also formed to be substantially flat, so that the distance between the upper surface of the multi-gap layer 106 and the counter substrate 108 is increased. A certain cell gap a, a ′, a ″ is formed equally. On the other hand, since the cross section of the isotropic phase portion 102 has a concave shape with a depressed center and a step is formed on the upper surface, the cell gap from the upper surface to the counter substrate 108 is not uniform. For example, the cell gap b and the cell The distance from the gap c is formed differently.

6 is a cross-sectional view taken along the line XX of FIG. In the liquid crystal cell 100 in FIG. 6, the cell gap secured above the liquid crystal phase region 101 corresponding to the reflective display region is indicated by the cell gap a, and the cell gap secured between the isotropic phase region 102 and the counter substrate 108 is indicated by an arrow. d (hereinafter referred to as “cell gap d”) and arrow e (hereinafter referred to as “cell gap e”).
In FIGS. 5 and 6, the aspect ratio is changed with respect to FIG. 4 for convenience. In addition, a part of the columnar body 107 in FIG. 6 is omitted.

  As shown in FIG. 6, when observed in a cross-sectional view perpendicular to the short direction of the liquid crystal phase portion 101 of the liquid crystal cell 100, the cell gap is the distance from the upper surface of the multi-gap layer 106 to the counter substrate 108. Are substantially uniform at any point. On the other hand, the upper surface of the isotropic phase portion 102 is formed in a concave shape, and the relationship is cell gap d ≠ cell gap e.

  As exemplified above, in the retardation layer composed of the liquid crystal phase part and the isotropic phase part, the upper surface of the isotropic phase part is not particularly formed flat. For example, the liquid crystal phase part is formed in a slit shape as shown in FIG. In the optical element, the step may be different between the central portion of the isotropic phase portion and the pattern end portion in both the longitudinal section and the short section of the slit. As shown in FIGS. 5 and 6, this step may not only be formed in a concave shape at the center, but also rise from the center, resulting in a step with the end located at a lower position. Due to the occurrence of such a step, it is difficult to obtain a uniform cell gap, and as a result, display unevenness is generated in the liquid crystal display device.

  The present invention has been made in view of the above problems, and relates to an optical element used in a liquid crystal display device for semi-transmission and semi-reflection, and has a retardation layer including an isotropic phase portion and a liquid crystal phase portion, An object of the present invention is to provide an optical element having a retardation control function in which a step in the retardation layer is flattened, a liquid crystal device using the optical element, and a method of manufacturing the optical element.

  The present invention relates to an isotropic phase portion formed directly or indirectly on the upper surface of a substrate, a liquid crystal phase portion formed adjacent to the isotropic phase portion, and a planarization layer formed so as to cover both portions. A basic feature is that a phase difference layer is provided.

That is, the present invention
(1) An optical element comprising a light-transmitting base material and a retardation layer formed on the base material, wherein the retardation layer is formed directly or indirectly on the substrate. A liquid crystal phase portion in which molecules are fixed in a liquid crystal phase state, an isotropic phase portion in which crosslinkable liquid crystal molecules adjacent to the liquid crystal phase portion are fixed in an isotropic phase state, the liquid crystal phase portion and the liquid crystal phase portion An optical element having a phase difference control function, characterized by comprising a planarizing layer provided to cover the upper surface of the isotropic phase part;
Is the first invention,
The surface step of the planarizing layer may be within 0.2 μm, or
A colored layer comprising light-transmitting colored portions of at least two colors may be laminated between the base material and the retardation layer or directly or indirectly on the retardation layer, or
A columnar body for cell gap control is directly formed on the upper surface of the planarizing layer, and at least a part of the columnar body may be formed in the isotropic phase region in plan view, or ,
A reflective part may be provided between the base material and the retardation layer, and the reflective part may be selectively formed below the liquid crystal phase part.

The present invention also provides
(2) The array substrate and the facing substrate are opposed to each other while maintaining a certain distance, and a driving liquid crystal material is formed on the inner side surface between the substrates to form a driving liquid crystal layer and polarized light is applied to the outer side surfaces of both substrates. A transflective and semi-reflective liquid crystal display device in which a plate is laminated and a sub-pixel includes a reflective display region and a transmissive display region, and is described as the first invention described in (1) as the facing substrate. A transflective liquid crystal device characterized by using any one of the optical elements,
Is the second invention.

The present invention also provides
(3) A manufacturing method for producing an optical element having a retardation control function by forming at least a retardation layer on a light-transmitting substrate, wherein the step of forming the retardation layer comprises at least a crosslinkable liquid crystal A coating film forming step of forming a coating film by directly or indirectly applying a liquid crystal composition containing molecules onto a light-transmitting substrate, and aligning the crosslinkable liquid crystal molecules present in the coating film in a desired direction An alignment step of bringing the liquid crystal phase into a state of cross-linking, and irradiating the coating film with ultraviolet rays or an electron beam through a photomask to polymerize the cross-linkable liquid crystal molecules in a liquid crystal phase state, thereby crosslinking the liquid crystal molecules in the irradiated portion. A liquid crystal phase site forming step for forming a liquid crystal phase site by polymerizing and fixing only the liquid crystal phase site, and heating the substrate on which the coating film is formed to bring the crosslinkable liquid crystal molecules in an uncured state into an isotropic phase state In the heated state Forming an isotropic phase site by polymerizing and fixing the liquid crystal molecules, and a resin composition containing at least a light-transmitting curable resin, the liquid crystal phase site and the isotropic phase A planarization layer forming step of forming a coating film by directly coating on the upper surface of the part, and forming a planarization layer by curing the curable resin contained in the coating film. A method for producing an optical element having a phase difference control function,
Is a third invention.

In the present invention, the “retardation layer” means a layer having a retardation control function capable of optically compensating for a change in retardation of light.

  In addition, in the constituent layers constituting the optical element of the present invention, the expression method meaning the vertical direction such as “upper”, “upper”, “upper surface” or “lower”, “lower”, “lower surface”, etc. When arranged in the orientation of the lower layer, in any constituent layer, the substrate surface side is expressed as the “down” direction, and the side opposite to the substrate surface is expressed as the “up” direction.

Furthermore, in describing the constituent layers of the present invention, “in plan view” means a case of observation from the normal direction of the substrate surface. For example, the phrase “liquid crystal phase part region in plan view” means a region that overlaps with the liquid crystal phase part when observed from the normal direction of the substrate surface.

  The optical element of the present invention has a retardation layer comprising a liquid crystal phase portion and an isotropic phase portion, and a planarizing layer that covers these and flattens the upper surface directly or indirectly on a transparent glass substrate. . Therefore, the surface step observed on the upper surface of the isotropic phase region is eliminated, and the cell gap in the isotropic phase region can be made uniform. Therefore, it is possible to provide a good image without display unevenness in not only the reflective display but also the transmissive display.

  Further, as described above, since the surface of the retardation layer in the present invention is flattened by the flattening layer, the height of the upper surface is uniform not only above the liquid crystal phase part but also above the isotropic phase part. A columnar body can be formed. Therefore, the design of the columnar body can be improved.

  Furthermore, since the liquid crystal phase part or isotropic phase part formed by immobilizing crosslinkable liquid crystal molecules is generally very hard compared to other laminated structure parts, the liquid crystal phase part or isotropic phase part is directly on the upper surface. When the columnar body is formed, in the liquid crystal device combined with the counter substrate facing the columnar body, there is a possibility that the bottom surface of the columnar body sinks into the portion. However, the retardation layer of the present invention is flattened on the upper surface of the liquid crystal phase site and the isotropic phase site composed of the soft crosslinkable liquid crystal molecules by an acrylic curable resin having a hardness higher than that of the crosslinkable liquid crystal molecules. Since the formation layer is formed, there is no concern that the bottom surface of the columnar body will sink into the substrate surface.

  The optical element of the present invention can provide a liquid crystal display device that is easier and less expensive to manufacture than conventional photolithography methods, and that enables good image display without display unevenness.

The best mode for carrying out the phase difference controlling optical member of the present invention will be described below with reference to the drawings.

(About embodiment of the optical element of this invention)
1st and 2nd embodiment of the optical element of this invention is described using Fig.1 (a), (b). As described above, the surface of the isotropic phase portion in the optical element of the present invention has a concave or convex step, and the present invention is characterized in that the step is flattened by a flattening layer. However, in the optical element of the present invention illustrated in the following description, the upper surface of the isotropic phase portion is also illustrated in a flat shape for convenience.

Fig.1 (a) is schematic which shows the cross-section of 1st embodiment of the optical element 1 of this invention. In the optical element 1, an isotropic phase portion 4, a liquid crystal phase portion 5 having a height higher than the isotropic phase portion 4, and a planarizing layer 6 that covers these from the upper surface are formed on the surface of the light-transmitting substrate 2. ing. The isotropic phase region 4, the liquid crystal phase region 5, and the planarizing layer 6 constitute the retardation layer 3.
On the other hand, FIG.1 (b) is schematic which shows the cross-section of optical element 1 'which is 2nd embodiment of this invention. The optical element 1 ′ is formed by forming an isotropic phase portion 4 on the surface of the substrate 2, a liquid crystal phase portion 5 having a lower height, and a flattening layer 6 covering these from the upper surface. The multi-gap layer 7 is formed in the region of the liquid crystal phase region 5 in the upper surface of the planarizing layer and in a plan view, and the columnar body 31 is formed on the multi-gap layer and on the planarizing layer 6. In plan view, the columnar body 32 is formed in the isotropic phase region.
Here, “height” means the thickness in the direction perpendicular to the substrate surface.

FIGS. 1A and 1B show an example of an embodiment of the optical element of the present invention. However, the optical element of the present invention is not limited to this. For example, as a third embodiment, the substrate 2 A colored layer comprising at least two or more types of transparent colored regions, or a patterned light shielding region that partitions the transparent colored region, and at least two or more types of transparent defined by the light shielding region. You may further provide the colored layer which consists of a colored area | region (not shown). According to such an optical element, the liquid crystal display device can be color-displayed by being incorporated in the transflective liquid crystal display device.

  As a fourth embodiment, which is still another aspect, a reflective portion that reflects light can be provided between the base material 2 and the liquid crystal phase portion 5 (not shown). With this configuration, a transflective substrate having a reflective portion can be formed. The region where the reflective portion is provided, that is, the liquid crystal phase portion 5 is provided as a reflective display region and a reflective portion. A region that is not present, that is, the isotropic phase region 4 can be used as a transmissive display region.

In various embodiments such as the first to fourth embodiments described above, the optical element of the present invention may further include a switching circuit on the substrate 2 or the retardation layer 3 (referred to as the fifth embodiment). ). FIG. 2 is a schematic partial plan view showing an example of the optical element of the fifth embodiment.

  In the fifth embodiment shown in FIG. 2, the switching circuit 11 includes a transparent electrode portion 19 and a reflective electrode provided in the transmissive display region (that is, isotropic phase region) and the reflective display region (that is, liquid crystal phase region), respectively. A layered structure is formed on the base material 2a corresponding to the portion 12, and an element substrate is formed as a functional layer together with various elements such as signal lines and scanning lines electrically connected thereto. .

  The switching circuit 11 receives an electric signal supplied from the scanning line 14 and controls the energization state of the signal line 13 and the electrode unit 12. Specific examples of the switching circuit 11 include active elements such as a three-terminal element such as a thin film transistor (TFT) and a two-terminal element such as a MIM (Metal Insulator Metal) diode.

  When the switching circuit 11 is a thin film transistor, the switching circuit 11 includes a drain electrode 15 connected to each pixel electrode 18 including the transparent electrode portion 19 and the reflective electrode portion 12, and a source electrode that receives supply of an electric signal from the signal line 13. 16 and a semiconductor that is interposed between the drain electrode 15 and the source electrode 16 and connects the two electrodes are laminated on the base material 2 and further laminated on the semiconductor via an insulating layer (not shown). The gate electrode 17 is laminated. Note that the gate electrode is connected to the scanning line 14.

As the electrode part 12, a transparent electrode such as an ITO (Indium Tin Oxide) electrode can be preferably used, and it can be formed by laying it on almost the entire region where each pixel is formed. The electrode portion 12 can also be formed by laying a thin transparent electrode on the edge of each pixel region.
Such an optical element can be used by being incorporated in a transflective liquid crystal display device.

  Hereinafter, the basic configuration of the optical element of the present invention will be described in more detail with reference to FIG.

For substrate 2:
The substrate 2 is made of a light-transmitting substrate forming material, and may be composed of a single layer with a single substrate forming material, or may be composed of multiple layers with multiple types of substrate forming materials. The substrate 2 may be partially provided with a light shielding region or the like. The light transmittance of the substrate 2 can be appropriately selected.

The substrate forming material is preferably configured to be optically isotropic. As the substrate forming material, plate-like bodies made of various materials can be appropriately selected in addition to a glass material such as a glass substrate. In particular, when the retardation control member is used for a liquid crystal display, the substrate forming material is preferably alkali-free glass. The base material 2 is, for example, about 5 μm to 3 mm depending on the application.
The light transmittance of the base material 2 can be selected as appropriate. Moreover, the base material 2 may be partially provided with a light-shielding region or the like.

A functional layer having a predetermined function can be further laminated between the substrate 2 and the retardation layer 3 or on the side surface of the substrate 2 opposite to the retardation layer 3. For example, the functional layer is a layer having a function of changing the state of light, and is a layer having a configuration different from that of the retardation layer 3, and is composed of a colored layer and a cholesteric liquid crystal in which liquid crystal orientation is fixed. Specific examples include a layer, a reflecting plate that reflects light, and a polarizing plate. The functional layer may be provided not only on the entire surface of the substrate 2 but also partially on the surface of the substrate 2.
Further, the functional layer may be an alignment film such as a horizontal alignment film for horizontally aligning liquid crystal molecules or a vertical alignment film for vertically aligning liquid crystal molecules.

About alignment film:
The alignment film is formed on the substrate as a layer for regulating the alignment direction desired for the crosslinkable liquid crystal molecules constituting the liquid crystal phase part 5 in the retardation layer 3. As the alignment film, polyimide, polyamide, polyvinyl alcohol or the like is usually used. In addition, when using polyimide as an alignment film, it is preferable that it has a long-chain alkyl group since the thickness of the retardation layer 3 formed in an optical element can be selected in a wide range.

  The alignment film is prepared by preparing a film composition liquid constituting the alignment film, and applying the film composition liquid on the substrate surface by a method such as flexographic printing or spin coating to form a coating film, and further curing the coating film. Can be formed. As the film composition liquid, for example, those containing polyimide include SE-7511 and SE-1211 manufactured by Nissan Chemical Industries, JALS-2021-R2 manufactured by JSR Corporation, and QL manufactured by Hitachi Chemical DuPont Microsystems Co., Ltd. And a series such as LX, or a Lyxon aligner manufactured by Chisso Corporation.

  The alignment film preferably has a thickness in the range of about 0.01-1 μm. If the film thickness of the alignment film is smaller than 0.01 μm, it may be difficult to impart desired alignment to the liquid crystal contained in the liquid crystal phase part of the retardation layer. Further, if the thickness of the alignment film is greater than 1 μm, the alignment film itself may diffusely reflect light and the light transmittance of the optical element may be greatly reduced.

Regarding the retardation layer 3:
The retardation layer 3 includes an isotropic phase portion 4 containing an isotropic liquid crystal, a liquid crystal phase portion 5 containing a liquid crystal phase liquid crystal, and a planarization layer 6 covering these from the top surface. The liquid crystal phase part 5 is connected to the isotropic phase part 4 and is different in thickness from the isotropic phase part 4 continuously connected to the liquid crystal phase part 5 to form a step in the thickness direction of the retardation layer. ing.
Both the liquid crystal phase part 5 and the isotropic phase part 4 are formed by immobilization with a polymerized structure by cross-linking of the common cross-linkable liquid crystal molecules constituting them, and thereby the transmitted light is transmitted. It is possible to control the phase difference. More specifically, the liquid crystal phase portion 5 is a so-called positive C plate, negative C plate, or positive A plate in a state in which the crosslinkable liquid crystal molecules constituting the liquid crystal phase portion 5 exhibit liquid crystal properties such as nematic liquid crystal and smectic liquid crystal. Alternatively, it is immobilized as a hybrid orientation or the like, while the isotropic phase portion 5 is immobilized in a state in which the crosslinkable liquid crystal molecules constituting it exhibit isotropic properties. With this fixed state, it is only possible to control the transmitted light to a desired phase difference by maintaining the desired state of the crosslinkable liquid crystal (that is, whether it is a liquid crystal state or an isotropic phase state). In addition, the liquid crystal phase part 5 and the isotropic phase part 4 have an advantage that they are not easily affected by heat.

: Isotropic phase region and liquid crystal phase region:
When the optical element 1 is incorporated in a transflective liquid crystal display device, the liquid crystal phase part 5 constitutes a reflective display area, while the isotropic phase part 4 constitutes a transmissive display area. From this point of view, it is preferable that the liquid crystal phase part 5 has a thickness that functions as a quarter-wave plate or a half-wave plate with respect to light incident on the optical element 1, and also for obtaining a desired phase difference control function. In addition, it is desirable to adjust the thickness of the isotropic phase portion 4 and the liquid crystal phase portion 5. The reflective display area on the base material 2 refers to the transmission of light incident on the liquid crystal display device when the reflective display is performed when the optical element 1 is incorporated in the transflective liquid crystal display device. Or the area | region on the base material 2 which reflects is shown, and the transmissive display area | region on the base material 2 is when the transmissive display is performed in the case where the optical element 1 is incorporated in a transflective liquid crystal display device. A region on the base material 2 through which light incident on the liquid crystal display device is transmitted is shown.

In order to obtain a desired thickness, the manufacturing conditions of the isotropic phase part 4 and the liquid crystal phase part 5 can be adjusted to adjust their own height. In addition, the thickness of each part in the optical element 1 can be measured using a stylus type step meter or the like, and a commercially available measuring instrument such as DEKTAK (manufactured by Sloan) can be suitably used.

Alternatively, as shown in FIG. 1 (b), after the planarization layer 6 is formed on the upper surfaces of the isotropic phase portion 4 and the liquid crystal phase portion 5, the upper surface of the planar phase layer 6 is a region of the liquid crystal phase portion 5 in plan view. In FIG. 5, by forming the multi-gap layer 7, the thickness of the liquid crystal phase part 5 region can be adjusted, and the required amount of retardation can be imparted to the liquid crystal phase part 5. The multi-gap layer will be described later.

Conventionally, the multi-gap layer for adjusting the height of the liquid crystal phase part was directly formed on the upper surface of the liquid crystal phase part protruding from the isotropic phase part or on the liquid crystal phase part castle surface recessed from the isotropic phase part. . However, in such a configuration, if the multi-gap layer formation position slightly deviates from the upper surface of the liquid crystal phase part, the multi-gap layer may not be formed in a desired shape and height, and a part of the multi-gap layer becomes an isotropic phase part. There was a risk of sticking out. Even if the alignment during the formation of the multi-gap layer is slightly shifted, this slight shift causes the multi-gap layer to be pulled out by the multi-gap layer constituent resin that protrudes the liquid crystal phase region, and the multi-gap layer is deformed in a wide range. It may reach. In a mode in which a light shielding region is formed across both regions at the boundary between the transmissive region and the reflective region, if the amount protruding from the liquid crystal phase region to the isotropic phase region does not exceed the light shielding region, the protruding portion is a liquid crystal. The display is not adversely affected. However, in a mode in which the amount of protrusion is large and extends beyond the light shielding region to the isotropic phase region, or where the light shielding region is not originally provided, the protrusion of the multi-gap layer is undesirably causing liquid crystal display unevenness.
On the other hand, in the optical element of the present invention, since the multi-gap layer is provided on the flattening layer described later, even if the formation position of the multi-gap layer slightly protrudes from the liquid crystal phase region in the plan view, The formation of the multi-gap layer is not easily broken by a slight protrusion, and the shape and height of the multi-gap layer are not disturbed. Therefore, a desired phase difference amount in the liquid crystal phase part can be obtained as designed, which is desirable.

  Further, the birefringence Δn of the liquid crystal phase part 5 in the retardation layer 3 is preferably about 0.03 to 0.20, and more preferably about 0.05 to 0.15.

  The liquid crystal phase part 5 causes a phase difference between the light incident on the liquid crystal phase part 5 and the light that has passed through the liquid crystal phase part 5, and this phase difference is a retardation amount, that is, a compound of the liquid crystal phase part 5. It is determined by the product of the refractive index (Δn) and the thickness. Therefore, in order to obtain a desired phase difference, it is necessary to obtain a retardation amount corresponding to this. When Δn is 0.03 or less, it is necessary to increase the thickness in order to obtain a desired retardation amount, and the orientation of the liquid crystal constituting the liquid crystal phase portion 5 is deteriorated. On the other hand, when Δn exceeds 0.20, it is necessary to extremely reduce the thickness of the liquid crystal phase part 5 and it becomes difficult to control the thickness.

Note that the birefringence (Δn) is determined on the assumption that the X axis is perpendicular to the alignment direction of the liquid crystal molecules and the Y axis is parallel to the alignment direction of the liquid crystal molecules on a plane parallel to the alignment direction of the elongated liquid crystal molecules. shows the difference between the refractive index n _Y in refractive index n _X and Y-axis direction of the X-axis direction. That is, Δn = | n _X −n _Y |.

  The birefringence can be calculated by measuring the retardation value and the thickness of the optical element 1 ′.

  The retardation value can be measured using a commercially available measuring apparatus such as RETS-1250VA (manufactured by Otsuka Electronics Co., Ltd.) or KOBRA-21 (manufactured by Oji Scientific Instruments). The measurement wavelength is preferably in the visible region (380 to 780 nm), and more preferably measured in the vicinity of 550 nm where the relative luminous sensitivity is the highest.

: About crosslinkable liquid crystal molecules:
The liquid crystal molecules constituting the liquid crystal phase portion 5 may be any molecules that can be fixed in the liquid crystal phase state, and the liquid crystal molecules have the property of forming a nematic liquid crystal in the liquid crystal phase state. It is preferable because the orientation can be easily imparted.

  The liquid crystal is preferably a liquid crystal having a polymerizable group in its molecular structure (sometimes referred to as a crosslinkable liquid crystal molecule) that can be fixed by polymerization of liquid crystal molecules. It is more preferable to use at least one that can be three-dimensionally crosslinked in a liquid crystal state.

  As the crosslinkable liquid crystal molecules, any of monomers, oligomers and polymers of the crosslinkable liquid crystal molecules may be used, and these may be used in appropriate combination.

As a liquid crystal material for constituting the retardation layer 3, a liquid crystal material having a positive birefringence anisotropy includes a nematic liquid crystal having a rod-like structure, and a liquid crystal material having a negative birefringence anisotropy. A discotic liquid crystal having a disk-like structure can be used. These liquid crystal materials include liquid crystal monomers, liquid crystal oligomers, or liquid crystal polymers. In the present invention, these liquid crystal materials may be collectively referred to as liquid crystal molecules for convenience.

Polymerizable liquid crystal molecules, particularly those which are crosslinkable liquid crystal molecule monomers, which are cured by polymerization by irradiation with ultraviolet rays, electron beams, etc. in that they can be cured while maintaining the alignment state of the liquid crystal molecules. It is preferable to use it. Since retardation amount and alignment characteristics are determined by the birefringence Δn of the liquid crystal molecules and the thickness of the retardation layer, Δn is preferably about 0.03 to 0.15.

Examples of the crosslinkable liquid crystal molecule monomer contained in the liquid crystal composition used for forming the retardation layer include those disclosed in JP-T-10-508882, and polymerizable chiral agents. For example, those disclosed in JP-A-7-258638 can be used. As a polymerizable nematic liquid crystal molecule shown as a more specific example, for example, a monomer, an oligomer having at least one polymerizable group such as a (meth) acryloyl group, an epoxy group, an oktacene group or an isocyanate group in one molecule, Examples thereof include polymers. More specifically, as such a crosslinkable liquid crystal molecule, one compound (compound (I)) of the compounds represented by the general formula (1) shown in the following chemical formula 1 is used. One of the compounds represented by the general formula (2) shown (compound (II)) or a mixture of two or more, or the compounds shown in chemical formulas 3 and 4 (compound (III)) These compounds, a mixture of two or more kinds, or a mixture 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 at which the crosslinkable liquid crystal molecules exhibit a liquid crystal phase. And R ² is preferably hydrogen, more preferably hydrogen. 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 4-10, and it is more preferable that it is the range of 6-9. 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 these reasons, both of these compounds have a narrow temperature range (temperature range in which the liquid crystal phase is maintained) that stably exhibits liquid crystallinity, and are not preferable for use as the liquid crystal composition of the present invention.

As the crosslinkable liquid crystal molecules blended in the liquid crystal composition, the above-mentioned chemical formula 1, chemical formula 2, chemical formula 3, and chemical formula 4 exemplify monomers of a liquid crystal having a polymerizable property (crosslinkable liquid crystal molecules). An oligomer, a polymer of a crosslinkable liquid crystal molecule, or the like may be used, and for these, a known one such as the above-described oligomer or polymer such as Chemical Formula 1, Chemical Formula 2, Chemical Formula 3, or Chemical Formula 4 may be appropriately selected and used. it can.

: About photoinitiator:
It is preferable that a photopolymerization initiator is further added to the liquid crystal composition containing the crosslinkable liquid crystal molecules described above. As the photopolymerization initiator, a radical polymerizable initiator can be preferably used. The radical polymerizable initiator generates free radicals by energy such as ultraviolet rays. For example, benzyl (also referred to as bibenzoyl), benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate, 4 -Benzoyl-4'-methyldiphenyl sulfide, benzylmethyl ketal, dimethylaminomethylbenzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 3,3'-dimethyl-4-methoxy Benzophenone, methylobenzoyl formate, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morph Linophenyl) -butan-1-one, 1- (4-dodecylphenyl) -2hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane- 1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethyl Examples thereof include thioxanthone, isopropylthioxanthone, 1-chloro-4-propoxythioxanthone and the like. In the present invention, a commercially available photopolymerization initiator can also be used as appropriate. For example, “Irgacure 184 (substance name: 1-hydroxycyclohexyl phenyl ketone)”, “Irgacure 369 (substance name: 2-benzyl-2-dimethylamino-1- (4-morpholino) manufactured by Ciba Specialty Chemicals, Inc. Phenyl) -butan-1-one) ”,“ Irgacure 651 (substance name: 2,2-dimethoxy-1,2-diphenylethane-1-one) ”,“ Irgacure 907 (substance name: 2-methyl-1-) Ketones such as (4- (methylthio) phenyl) -2-morpholinopropan-1-one), “Darocur 1173 (substance name: 2-hydroxy-2-methyl-1-phenylpropan-1-one)” Compounds, 2,2′-bis (o-chlorophenyl) -4,5,4′-tetraphenyl-1,2′biimidazole (Kurokin Kasei Co., Ltd.) Biimidazole compounds such as (manufactured) may be used.

  The photopolymerization initiator is preferably added in a range that does not significantly impair the liquid crystal regularity of the crosslinkable liquid crystal molecules. The addition amount of the photopolymerization initiator is generally in the range of 0.01 to 15% by weight, preferably 0.1 to 12% by weight, more preferably 0.5 to 10% by weight. It can be added to the agent.

: About thermal polymerization initiator:
In addition to the photopolymerization initiator, a thermal polymerization initiator may be added to the liquid crystal composition in place of the photopolymerization initiator. The crosslinkable liquid crystal molecule undergoes a polymerization reaction even when heated, but by containing a thermal polymerization initiator, the crosslinkable liquid crystal molecule is heated to be in an isotropic phase, so that it is in an isotropic phase. The isotropic phase portion 4 can be easily formed by efficient polymerization and curing.

  As the thermal polymerization initiator, a radical polymerizable initiator can be preferably used. For example, 2,2′-azobisisobutylnitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4 -Methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis-1-cyclohexylnitrile, dimethyl-2,2'-azobisisobutyrate, 4,4'-azobis-4-cyanovaleric acid, , 1'-azobis (1-acetoxy-1-phenylethane) and other azo compounds, benzoyl peroxide, lauroyl peroxide, tert-butyl peroxide, 1,1-bis (tert-butylperoxy) cyclohexane and other organic compounds Mention may be made of peroxides.

  The thermal polymerization initiator is preferably added in a range that does not significantly impair the orientation of the crosslinkable liquid crystal molecules. The amount of the thermal polymerization initiator added is generally in the range of 0.01-15 wt%, preferably 0.1-12 wt%, more preferably 0.5-10 wt%. It can be added to the liquid.

: About surfactant:
Moreover, it is preferable that surfactant is added to the liquid crystal composition. By adding a surfactant to the liquid crystal composition, the orientation of liquid crystal molecules at the air interface can be controlled in a coating film formed by applying the surfactant.

  The surfactant is not particularly limited as long as it does not impair the liquid crystal expression of the crosslinkable liquid crystal molecules. For example, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene derivative, polyoxyethylene / polyoxypropylene block polymer, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene fatty acid ester , Nonionic surfactant such as polyoxyethylene alkylamine, fatty acid salt, alkyl sulfate ester salt, alkylbenzene sulfonate, alkyl naphthalene sulfonate, alkyl sulfosuccinate, alkyl diphenyl ether disulfonate, alkyl phosphate, Polyoxyethylene alkyl sulfate ester salt, naphthalenesulfonic acid formalin condensate, special polycarboxylic acid type polymer surfactant, polyoxyethylene Anionic surfactants such as alkyl phosphates.

  The addition amount of the surfactant is generally 0.01-1% by weight, preferably 0.05-0.5% by weight, and can be added to the liquid crystal composition.

  In addition to the above-mentioned additives, other additives such as a sensitizer can be added to the liquid crystal composition as long as the object of the present invention is not impaired.

: About planarization layer:
The planarizing layer 6 is formed by applying a resin composition containing a light-transmitting curable resin over substantially the entire surface of the isotropic phase portion 4 and the liquid crystal phase portion 5 and curing the resin by light irradiation or heat irradiation. Can be formed. The flattening layer 6 is a layer for flattening a step on the upper surface of the isotropic phase portion 4 or a step between the isotropic phase portion 4 and the liquid crystal phase portion 5. The flat surface of the flat surface of the layer 3 is a step in the longitudinal cross section and the short cross section of the isotropic phase portion 4 and a step at the boundary between the isotropic phase portion 4 and the liquid crystal phase portion 5 in plan view. Will be resolved.
That is, in the present invention, the “surface level difference of the planarization layer” means a level difference measured at any two locations of the planarization layer, and in particular, the upper surface of the isotropic phase portion existing on the lower surface of the planarization layer. Even the surface step difference between the liquid crystal phase region and the isotropic phase region can be eliminated on the surface of the retardation layer (the surface of the planarization layer) due to the presence of the planarization layer.

It is desirable that the surface level difference of the planarizing layer be 0.2 μm or less. A liquid crystal display device with excellent image display without display unevenness when a liquid crystal display device is manufactured using such an optical element because the step is within 0.2 μm between any two points on the upper surface of the planarizing layer 6. A display device can be provided.
Further, the level difference is obtained more strictly, and the height of the liquid crystal phase portion is adjusted when manufacturing a liquid crystal display device as long as the level difference is within 0.1 μm in any region on the upper surface of the planarizing layer 6. Therefore, the degree of difficulty in positioning the multi-gap layer formed can be reduced. If the multi-gap layer slightly deviates from the upper surface of the liquid crystal phase part, the multi-gap layer is not formed in the desired shape and height due to the effect of the step formed by the isotropic phase with the liquid crystal phase, and uneven reflection does not occur. Although there is a possibility, if a multi-gap layer is provided on a planarizing layer having a step of 0.1 μm or less, even if the formation position of the multi-gap layer slightly protrudes from the liquid crystal phase region in plan view, Does not disturb the shape and height. Therefore, it is more preferable because a merit that a desired phase difference amount in the liquid crystal phase part can be obtained as designed can be obtained.

  The resin composition used for forming the planarizing layer 6 is not particularly limited as long as it contains at least a light-transmitting curable resin and the step on the upper surface of the planarizing layer 6 can be 0.2 μm or less. It is not something. As the resin composition, an acrylic or urethane resin or a material in which an acrylic or urethane monomer is mixed can be used.

In addition, other additives such as a photopolymerization initiator can be appropriately added to the resin composition as necessary. Moreover, with respect to the commercially available composition containing the said resin, it is a solution state using 1 type, or 2 or more types of solvents, such as propylene glycol monomethyl ether acetate (PEGMA), 3-methoxybutyl acetate (MBA), and diethylene glycol dimethyl ether (DMDG). The isotropic phase region 4 and the liquid crystal phase region 5 can be applied to the upper surface.
Examples of commercially available resin compositions that can be used include IT-MP408, IT-MP406, IT-MP412SC-1, IT-MP412SC-7 manufactured by The Inc. Tech.

About multi-gap layers:
The multi-gap layer is a layer composed of at least a light-transmitting photocurable or thermosetting resin composition, and is formed to satisfy a desired thickness on the upper surface of the liquid crystal phase part. As the resin composition, an acrylic or urethane resin or a material in which an acrylic or urethane monomer is mixed can be used.

About columnar bodies:
The columnar bodies 31 and 32 are cells that are distances between substrates when the optical element 1 ′ of the present invention is used as one substrate constituting a transflective liquid crystal display cell and is combined with an opposing substrate. It is a member for maintaining the gap at a constant distance. The space secured between the two substrates by the columnar body is filled with a driving liquid crystal material, thereby forming a driving liquid crystal layer. FIG. 1B shows a columnar body 31 formed on the upper surface of the multi-gap layer 7 and a columnar body 32 formed on the upper surface of the planarizing layer 6 and in the isotropic phase region 4 in plan view. Although both are illustrated, the columnar body is not necessarily provided in both the liquid crystal phase region and the isotropic phase region in plan view. The design to be patterned can be changed as appropriate depending on other constituent layers constituting the optical element and the configuration of the opposing substrate.

In addition, the retardation layer composed of an isotropic phase portion and a liquid crystal phase portion, which does not have a conventional flattening layer, is composed of crosslinkable liquid crystal molecules, and therefore has low hardness and isotropic phase portion or liquid crystal phase portion. When the columnar body is formed directly on the upper surface, there is a possibility that the columnar body may sink into the retardation layer when an external force in a direction perpendicular to the substrate surface is applied after being combined as a liquid crystal display device. In the optical element of the invention, since the columnar body is formed on the upper surface of the planarizing layer that is sufficiently harder than the isotropic phase portion or the liquid crystal phase portion, there is no fear of the columnar body being depressed as described above.

  As the columnar bodies 31 and 32, generally, a cured product of a photosensitive resin composition can be used. Although not excluding the use of other various materials, it is possible to easily form a columnar body having a preferable hardness, and relatively little heat is applied to the object to be formed when forming the columnar body. From the point of being completed, it is preferable to use the said hardened | cured material. As the photosensitive resin composition, a photosensitive resin having a reactive vinyl group such as an acrylate-based, methacrylate-based, polyvinyl cinnamate-based, or cyclized rubber-based resin can be used, and in particular, an acrylate-based photosensitive resin. Are preferably used.

(About the manufacturing method of the optical element of this invention)
An example of a method for producing the optical element 1 ′ of the present invention will be described below.
First, the base material 2 for laminating the retardation layer 3 is prepared. In order to regulate the desired alignment direction required for the crosslinkable liquid crystal molecules constituting the liquid crystal phase part 5 in advance on the surface of the substrate 2, a treatment for imparting alignment (orientation facilitating step) can be performed. .

About alignment film formation:
As the alignment facilitating step, a conventionally known alignment film forming method for aligning the driving liquid crystal material in a desired direction can be appropriately selected and employed. For example, a uniaxially stretched film or a biaxially stretched film is attached to the upper surface of the substrate 2, or a coating film is formed by applying a polyimide resin composition or the like, and a rubbing treatment is performed to form an alignment film. Can do. Moreover, the surface of the base material 2 can also be processed by irradiating polarized light using a photo-alignment film. Further, when the alignment film surface has high water repellency or oil repellency, the wettability of the alignment film surface is increased in advance by interposing UV cleaning or plasma treatment within a range in which the liquid crystal can be aligned. Also good.

About formation of retardation layer:
: About formation of isotropic phase region and liquid crystal phase region:
Next, a liquid crystal composition containing a crosslinkable liquid crystal molecule is applied directly or indirectly to the upper surface of the substrate 2 to form a coating film (coating film forming step). The liquid crystal composition is desirable because the coating properties can be improved by dissolving or suspending the above-described crosslinkable liquid crystal molecules in an appropriate solvent and using them in a solution state.

The solvent is not particularly limited as long as it can dissolve the crosslinkable liquid crystal molecules, and an organic solvent can be appropriately selected. When a spin coating method is used to form a coating film by applying the liquid crystal composition on the substrate 2, the solvent is preferably 3-methoxybutyl acetate, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, or the like. used.

In the coating film forming step, a known coating method can be used as a coating method of the liquid crystal composition. Specifically, a spin coating method, a die coating method, a slit coating method, a roll coating method, a gravure coating method, The liquid crystal composition can be applied directly or indirectly onto the substrate 2 by each method such as a slide coating method and an immersion method, or a method in which these are appropriately combined. In order to increase the adhesion between the substrate 2 and the coating film, an adhesive layer is provided on the substrate 2 as described in JP-A-8-278491, and further a liquid crystal composition is formed on the adhesive layer. An object may be applied.
The weight ratio of the crosslinkable liquid crystal molecules in the liquid crystal composition is 5% to 50% by weight. If it exceeds 50% by weight, the film thickness distribution of the retardation layer may be increased, and if it is less than 5% by weight, uneven coating may occur. Considering this, the weight ratio of the liquid crystal is preferably 5 to 50 parts by weight, and more preferably 10 to 30 parts by weight.

  After the coating film is formed on the substrate 2 in the coating film forming process, the crosslinkable liquid crystal molecules contained in the coating film are brought into a liquid crystal phase state oriented in a desired direction (referred to as a liquid crystal phase forming process). In this liquid crystal phase forming step, the coating film formed on the substrate 2 is held at a temperature at which the crosslinkable liquid crystal molecules develop a liquid crystal phase, and the crosslinkable liquid crystal molecules contained in the coating film are brought into a liquid crystal phase state. Will be implemented. At this time, a desired liquid crystal state such as a nematic liquid crystal is formed on the coating film according to the type of liquid crystal molecules.

  After the liquid crystal phase forming step, light is selectively irradiated to the liquid crystal phase planned site forming the predetermined liquid crystal phase site 5 in the coating film, and the crosslinkable liquid crystal molecules contained in the liquid crystal phase planned site are in the liquid crystal phase state. To fix the liquid crystal phase part 5 (referred to as a liquid crystal phase part forming step). More specifically, a photomask formed with a pattern is coated on the coating film so that the surface of the liquid crystal phase planned portion can be exposed without exposing the surface of the portion other than the liquid crystal phase planned portion. Irradiate light from the photomask surface. At this time, the light passing through the photomask reaches the coating film, the liquid crystal phase planned site on the coating film is exposed, and the crosslinkable liquid crystal molecules contained in the liquid crystal phase planned site are polymerized and cured. Thus, the liquid crystal contained in the liquid crystal phase planned portion is fixed in a state where a desired orientation is imparted, and the liquid crystal phase portion 5 is formed.

  When the liquid crystal phase site forming step is performed in this manner, the liquid crystal phase site 5 is formed at an arbitrary position of the coating film according to the mask pattern of the photomask. At this time, in the coating film, the liquid crystal contained in the portion other than the liquid crystal phase portion 5, that is, the portion not exposed to light, is not fixed even in the liquid crystal phase.

  In the liquid crystal phase site forming step, the crosslinking reaction proceeds by irradiating light of the photosensitive wavelength of the liquid crystal toward the coating film, and the wavelength of the light irradiated to the coating film is included in this coating film. It is appropriately selected according to the type of liquid crystal. The light applied to the coating film is not limited to monochromatic light, but may be light having a certain wavelength range including the photosensitive wavelength of the liquid crystal.

As the light used for exposure, ultraviolet rays and electron beams are preferable from the magnitude of excitation energy, and the irradiation amount is appropriately selected according to the crosslinkable liquid crystal molecules to be used, but when using ultraviolet rays, the irradiation amount is In general, it is preferable to adjust the exposure amount of the liquid crystal phase planned site to be about 10 to 1000 mJ / cm ² , and the wavelength is preferably about 200 to 450 nm. Moreover, when using an electron beam, it is preferable to irradiate an electron beam of about 50-500 Gy to a liquid crystal phase presumed part, and to make it harden | cure.

  The cross-linking reaction of the liquid crystal is preferably performed while heating the coating film to a temperature 1 to 10 ° C. lower than the temperature at which the cross-linkable liquid crystal molecules transition from the liquid crystal phase to the isotropic phase. By doing so, it is possible to reduce the disorder of the orientation of the liquid crystal during the crosslinking reaction. From this point of view, the temperature at which the crosslinking reaction is carried out is more preferably 3-6 ° C. lower than the temperature at which the liquid crystal transitions from the liquid crystal phase to the isotropic phase.

  After the liquid crystal phase part 5 is formed by the liquid crystal phase part forming step, the liquid crystal contained in the part other than the liquid crystal phase part 5 is made isotropic and isotropically fixed in the isotropic phase. The site | part 4 is formed (isotropic phase site | part formation process). In the isotropic phase region forming step, a temperature at which a crosslinkable liquid crystal contained in a region other than the liquid crystal phase region 5 is not cured and is in a liquid crystal state is called an isotropic phase (referred to as an isotropic phase transition temperature). ) By heating to the above, it is transferred to an isotropic state and polymerized and fixed in an isotropic phase. The method of forming the isotropic phase part only by heating the coating film is preferable from the viewpoint of simplifying the equipment for carrying out this step and suppressing the manufacturing cost of the optical element.

  Here, the isotropic phase transition temperature can be measured by a measuring device such as DSC. In addition, the phase transition from the liquid crystal phase to the isotropic phase can be generally confirmed by a change in the state of the coating film observed with a polarizing microscope. In addition, since the liquid crystal phase part 5 is fixed by polymerizing liquid crystal molecules by light irradiation, the liquid crystal phase of the coating film can be obtained even if the coating film is heated to an isotropic phase transition temperature or higher in the isotropic phase part forming step. The orientation of the liquid crystal formed in the portion 5 is maintained.

  In the isotropic phase region forming step, the thickness of the isotropic phase region 4 changes as the liquid crystal molecules contained in the isotropic phase region are fixed in the isotropic phase state to become the isotropic phase region 4. A step is generated between the liquid crystal phase portion 5 and the surface. The thickness of the isotropic phase portion 4 varies greatly depending on the heating conditions of the isotropic phase forming step, and may be thicker or thinner than the thickness of the liquid crystal phase portion 5. At this time, the orientation of the liquid crystal contained in the liquid crystal phase portion 5 is maintained regardless of the thickness of the isotropic phase portion 4. Therefore, the height of the isotropic phase portion 4 and the step between the isotropic phase portion 4 and the liquid crystal phase portion 5 are adjusted by adjusting the heating conditions in the isotropic phase portion forming step, and the transmissive display area and the reflective display are adjusted. It is possible to design the retardation layer 3 for obtaining a desired amount of retardation in the region.

  However, the present inventor has found that the following problems occur in the isotropic phase part process. That is, when the isotropic phase portion formed through the isotropic phase portion forming step is observed, a step is generated on the upper surface of the isotropic phase portion, and the step is shown in FIGS. As described above, the cross section in the longitudinal direction and the cross section in the lateral direction of the isotropic phase portion were observed. The mechanism of the occurrence of this level difference is not clear, but the crosslinkable liquid crystal molecules once aligned in the liquid crystal phase site forming step are returned to the isotropic phase state by heating again, and when the crosslinking is continued by continuing the heating, It was considered that the liquid crystal molecules flowed slightly but this caused the top surface of the isotropic phase portion to rise or dent.

  The step generated on the upper surface of the isotropic phase portion cannot maintain a good cell gap when an optical element having the isotropic phase portion is incorporated in a liquid crystal display device, resulting in display unevenness. I found out that it was the cause. In order to eliminate this step, a phase difference layer including an isotropic phase portion, a liquid crystal phase portion, and a planarizing layer covering the upper surface with a step difference of 0.2 μm or less is formed, thereby completing the present invention. Is.

The planarizing layer is formed as follows.
First, a coating liquid containing a light-transmitting curable resin is applied on the isotropic phase part 4 and the liquid crystal phase part 5 (flattening layer coating step). As the coating solution, a coating method similar to the retardation layer composition solution in the coating film forming step is selected. Moreover, the weight ratio of a curable resin and a solvent are selected similarly to a phase difference layer composition liquid, and other additives, such as a photoinitiator and a sensitizer, may be added.

After the planarization layer coating step, the solvent is removed by holding the coating film at a predetermined temperature, and heat is applied, or the coating film is heated to cure the coating film to form the planarization layer 6. (Planarization layer curing step). For the light irradiation to the planarizing layer 6, light having a photosensitive wavelength of the coating film is appropriately selected as in the liquid crystal phase forming step. The light used for exposure is also preferably ultraviolet rays or electron beams, as in the liquid crystal phase forming step. When ultraviolet rays are used, the irradiation amount is generally about 10-1000 mJ / cm ^2. The wavelength is preferably adjusted, and the wavelength is preferably about 200 to 450 nm. Alternatively, as a method for curing the flattening layer coating film, a method of irradiating the planarizing layer coating film with an electron beam of about 50 to 500 Gy and curing it may be used.

About forming a multi-gap layer:
Subsequently, the multi-gap layer 7 is formed on the upper surface of the flattening layer 6 in the region of the liquid crystal phase portion in plan view (multi-gap layer forming step). In the multi-gap layer forming step, various known methods such as a photolithography method, a screen printing method, and a transfer method can be used. For example, in the photolithography method, usable components of the multi-gap layer 7 such as the light-transmitting photo-curing or thermosetting resin described above, a solvent, a diluent, or a monomer, if necessary, After mixing with appropriate additives to prepare and use a coating composition or ink composition for forming the multi-gap layer 7, it is applied almost uniformly on the upper surface of the flattening layer 6, dried, and then in plan view The multi-gap layer 7 having a desired pattern can be formed by performing predetermined pattern exposure so as to be formed along the region 5 of the liquid crystal phase portion and then developing the pattern.
In the screen printing method, the multi-gap layer 7 can be formed by overprinting the ink composition at a position where the multi-gap layer 7 is expected to be formed. Furthermore, in the transfer method, a pattern of the multi-gap layer 7 is formed on the printing roll using a resin constituting the multi-gap layer 7, and the printing roll is rotated on the planarizing layer 6 to thereby form the planarizing layer 6. It can be carried out by transferring the pattern of the multi-gap layer 7 thereon.

About columnar body formation:
Next, the columnar bodies 31 and 32 are formed on the upper surface of the planarizing layer 6 and above the isotropic phase portion 4 or on the upper surface of the multi-gap layer 7 (columnar body forming step). In the columnar body forming step, various known methods such as a photolithography method, a screen printing method, and a transfer method can be used as in the multi-gap layer forming step. However, since the columnar body is not particularly required to be transparent, an opaque resin may be used as the photocurable or thermosetting resin used as the constituent resin. For example, as an example of a columnar body forming process employing a photolithography method, the columnar bodies 31 and 32 can be formed according to the method disclosed in Japanese Patent Application Laid-Open No. 2005-3750 previously disclosed. Moreover, as an example of the formation process of the columnar bodies 31 and 32 which employ | adopt the transfer method, Unexamined-Japanese-Patent No. 2006-178427 is mentioned as a conventionally well-known method.

  In general, the height of the columnar body in the present invention (that is, the dimension of the columnar body in the thickness direction of the phase difference controlling optical member) is preferably about 0.5 μm to 10 μm. However, as described above, the columnar body in the present invention is provided for the purpose of securing the size of the cell gap, which means the distance between the opposing substrates, to a predetermined distance, and therefore the height of the columnar body is desired. It can be determined appropriately in consideration of the distance between the substrates to be processed.

  In the liquid crystal cell using the optical element of the present invention, when another configuration for maintaining the cell gap (for example, filling the liquid crystal phase for driving with beads for maintaining the cell gap) is planned. The columnar body is not necessarily provided. In the optical element of the present invention in which the multi-gap layer is not provided, a columnar body can be provided directly on the upper surface of the planarizing layer and in the liquid crystal phase region in plan view. Therefore, the columnar bodies 31 and 32 are not essential components in the optical element of the present invention.

As described above, all parts of the crosslinkable liquid crystal molecules applied on the substrate 2 are cured to form the isotropic phase part 4 and the liquid crystal phase part 5, and then the upper surface of the isotropic phase part 4 or the isotropic phase part 4 is formed. And a liquid crystal phase part 5 is formed, and a flattening layer 6 for flattening a step is formed, and an optical element 1 ′ is obtained by including the multi-gap layer 7 and the columnar bodies 31 and / or 32 as necessary. Can do.

  According to the manufacturing method of the optical element 1 ′ of the present invention, a coating film is formed by applying the retardation layer composition liquid to the substrate 2, and the coating film is included in a portion that is not fixed in the liquid crystal phase state. Fix the liquid crystal in an isotropic phase. At this time, a step is generated on the upper surface of the isotropic phase part 4 depending on the fixing condition. In the present invention, the planarization layer 6 is formed on the liquid crystal phase part 5 and the isotropic phase part 4 to constitute the retardation layer. When the step in the retardation layer is flattened and used in a liquid crystal display device, it is always constant without being affected by the surface step in the isotropic phase portion in the multi-gap layer 7 forming step and the columnar body forming step. It becomes possible to manufacture an optical element 1 ′ in which a gap can be easily formed.

(About the liquid crystal device of the present invention)
Embodiments illustrating the liquid crystal device of the present invention will be described below with reference to the drawings.
3A and 3B are schematic views showing an embodiment of the transflective liquid crystal display device of the present invention. In the following description, a liquid crystal display device in which the optical element 1 ′ of the second embodiment of the present invention shown in FIG. 1B is incorporated in one of the laminated members will be described. However, the columnar body is not shown.

  As shown in FIG. 3A, in the liquid crystal display device 50 (50a), two laminated members 20 (20a, 20b) having optical transparency are arranged to face each other, and the laminated members 20a, 20b are disposed. A driving liquid crystal layer (hereinafter sometimes simply referred to as “liquid crystal layer”) 21 is formed between them, and polarizing plates 23 (23a, 23b) are disposed so as to sandwich the base materials 22a, 22b. .

  In the laminated members 20a and 20b, alignment films 24 (24a and 24b) are formed between the base material 22 (22a and 22b) and the liquid crystal layer 21, respectively. In the meantime, the reflection part 25 is formed in a predetermined pattern and shape, an opening 26 is formed so as to be surrounded by the reflection part 25, and a transflective layer 27 is formed. As the reflecting portion 25, a member that reflects light well is used, and specifically, a metal thin film such as aluminum, silver, or an alloy thereof can be used.

  In the laminated members 20a and 20b, electrode portions 28 are respectively formed between the base material 22 and the alignment film 24. The electrode portions 28 are formed on the pixel electrodes 29 and the pixel electrodes 29 formed for each pixel. And an opposing electrode 30 facing each other. The pixel electrode 29 and the counter electrode 30 are preferably made of a transparent conductive film such as ITO. FIG. 3 illustrates a mode in which the optical member of the present invention is used in a so-called TN liquid crystal device, but the liquid crystal device using the optical member of the present invention is not limited to this. For example, a so-called IPS liquid crystal device can be configured. In such a case, the electrode portions 29 (28) and 30 (28) shown in FIG. 3 may be provided adjacent to each other on one substrate.

  The laminated member 20a has a phase difference between a base material 22a and an alignment film 24a, which includes a liquid crystal phase part 5, an isotropic phase part 4 adjacent thereto, and a planarizing layer 6 formed so as to cover them. Layer 3 is formed. The liquid crystal phase part 5 is arranged at a position substantially opposite to the reflection part 25, and the isotropic phase part 4 is arranged at a position substantially opposite to the opening 26.

  Further, a multi-gap is provided between the alignment film 24 a and the planarizing layer 6 in order to control the gap (thickness) of the liquid crystal layer 21 facing the liquid crystal phase part 5 and the isotropic phase part 4 of the retardation layer 3. Layer 31 is formed. The multi-gap layer 31 is disposed so as to substantially face the formation position of the liquid crystal phase part 5 of the retardation layer 3.

  Here, the region where the reflection portion 25 is formed in the laminated member 20b is a reflection display region as a region that can reflect light that travels in the liquid crystal layer 21 when performing bright / dark display in the reflective display. Correspondingly, the region in which the opening 26 is formed corresponds to a transmissive display region as a region capable of transmitting light that is about to travel through the liquid crystal layer 21 when performing bright and dark display in transmissive display. Further, the laminated member 20a has a reflective display area and a transmissive display at a position facing the reflective portion 25 and the opening 26 of the laminated member 20b in the thickness direction of the laminated member 20b at the interface with the liquid crystal layer 21. Each region is formed.

  As described above, the retardation layer 3 is formed so that the liquid crystal phase part 5 is disposed in the reflective display region and the isotropic phase part 4 is disposed in the transmissive display region. In this case, the liquid crystal display device 50 is formed with the optical element 1 ′ in which the retardation layer 3 is formed directly on the base material 22 a.

  The alignment films 24a and 24b are made of polyimide or the like, and a horizontal alignment film for horizontally aligning the liquid crystal in the liquid crystal layer 21 formed between the laminated members 20, or a vertical alignment for vertically aligning the liquid crystal. It is an alignment film. Whether the horizontal alignment film or the vertical alignment film is used as the alignment film can be appropriately selected.

  The liquid crystal layer 21 is formed by filling a liquid crystal between the laminated members 20a and 20b as shown below. As a liquid crystal filling method, for example, a space is formed by fixing a space between the laminated members 20a and 20b in which a certain distance (cell gap) is secured by a columnar body. The laminated members 20a and 20b are bonded together using a curable resin. By injecting a liquid crystal material into the space, liquid crystal is sealed and a liquid crystal layer 21 is formed. Another method is not limited to means for injecting liquid crystal from the outside when filling the liquid crystal. For example, the liquid crystal is dropped on one of the opposing surfaces of the opposing laminated member in advance, and then the other laminated substrate is attached. The liquid crystal that has been superimposed and dropped can be bonded to form a liquid crystal phase 21 by spreading appropriately between both substrates.

  As the liquid crystal sealed in the liquid crystal layer 21 as the driving liquid crystal layer, a liquid crystal such as a TN (Twisted Nematic) liquid crystal is appropriately selected, and the orientation can be controlled by an external electric field.

  For example, when the liquid crystal sealed in the liquid crystal layer 21 is a TN liquid crystal, when a voltage is applied to the liquid crystal layer 21 (when a voltage is applied), the longitudinal direction of the elongated liquid crystal molecules is along the electric field direction. When the light passes through the liquid crystal layer 21 in this state (between the light before and after passing through the liquid crystal layer 21), the liquid crystal layer 21 is aligned. Thus, the phase shift is almost zero for light passing through either the reflective display region or the transmissive display region.

  On the other hand, when no voltage is applied to the liquid crystal layer 21 (when no voltage is applied), the liquid crystal molecules are aligned so as to be approximately along the plane direction of the laminated member 20 (the laminated member 20 facing the liquid crystal layer 21). A state of sleeping on the surface). In the reflective display area, the liquid crystal molecules in the thickness direction of the liquid crystal layer 21 are arranged in a twisted state.

  When light passes through such a liquid crystal layer 21, a phase difference occurs between the light before and after passing through the liquid crystal layer 21. And this phase difference is about 1/4 wavelength about the light which passes the part of the liquid crystal layer 21 pinched | interposed into the reflective display area | region of laminated member 20a, 20b, and the liquid crystal pinched | interposed into the transmissive display area | region of laminated member 20a, 20b. The refractive index anisotropy Δn and the liquid crystal layer thickness d of the liquid crystal sealed in the liquid crystal layer 21 are designed in advance so that the light passing through the layer 21 has a ½ wavelength, and the retardation layer 3 The thickness of the multi-gap layer disposed so as to face the liquid crystal phase part 5 is set.

  In the retardation layer 3, the thickness of the liquid crystal phase part 5 is set to be a ¼ wavelength plate or a ½ wavelength plate with respect to light transmitted through the liquid crystal phase part 5.

  In this liquid crystal display device 50, the light that travels in the thickness direction of the liquid crystal layer 21 through the liquid crystal layer 21 toward the laminated member 20a, passes through the laminated member 20a, and exits from the liquid crystal display device is perceived by the viewer. Is done.

  In the liquid crystal display device 50, in the reflective display, light (external light) is incident in the direction from the outside of the laminated member 20a toward the liquid crystal layer 21, and when the light passes through the reflective display region of the laminated member 20a, the liquid crystal layer 21, is reflected by the reflecting portion 25 disposed in the reflective display area of the laminated member 20 b, and proceeds from the liquid crystal layer 21 toward the reflective display area of the laminated member 20 a.

Further, in the liquid crystal display device 50, in the transmissive display, light is incident in the direction from the laminated member 20b toward the liquid crystal layer 21, and when this light passes through the transmissive display region of the laminated member 20b, the liquid crystal layer 21 is passed through the laminated member. Proceed toward the transmissive display area 20a.

  The liquid crystal display device includes a light source, a light guide plate that spreads light by directing light emitted from the light source in the direction of the surface of the laminated member 20b, and a light guide plate when light is incident in the direction of the laminated member 20b in transmissive display. The light irradiation part provided with the light reflecting plate which advances the light guide | induced by the laminated member 20b direction may be arrange | positioned, and the light from this light irradiation part may be comprised so that it may inject into the laminated member 20b. .

  In this liquid crystal display device 50, the liquid crystal molecules are aligned in the substantially plane direction of the liquid crystal layer 21 in accordance with the change in the voltage application state to the liquid crystal layer 21 in accordance with the change in the energization state of the electrode portion 28. By aligning the molecules at twisted positions, the liquid crystal sealed in the liquid crystal layer 21 causes a phase difference in the light traveling through the liquid crystal layer 21, or the liquid crystal molecules adjacent in the thickness direction are liquid crystal layers. By being aligned in the thickness direction of 21, almost no phase difference is caused in the light traveling through the liquid crystal layer 21. By controlling the orientation of the liquid crystal in the liquid crystal layer 21 in accordance with the change in the voltage application state to the liquid crystal layer 21, the presence / absence and intensity of light reaching the viewer from the liquid crystal display device 50 is controlled, and the reflective display In addition, the light and dark state in the transmissive display is freely controlled.

  In the liquid crystal display device 50, the light and dark states in the reflective display and the transmissive display are formed as follows. First, the reflective display will be described.

  Light (external light) incident in the direction from the outside of the laminated member 20a toward the liquid crystal layer 21 is transmitted through the polarizing plate 23a to become linearly polarized light having a polarization axis parallel to the transmission axis of the polarizing plate 23a. Pass through the reflective display area. The linearly polarized light is transmitted through the liquid crystal phase part 5 of the retardation layer 3 when a voltage is applied. At this time, when the liquid crystal phase part 5 is a quarter wavelength plate, a quarter wavelength phase difference is imparted. And converted to circularly polarized light. This circularly polarized light is transmitted through the liquid crystal layer 21 while substantially maintaining the state thereof, and further reflected by the reflecting portion 25 of the semi-transmissive reflective layer 27, and its polarization direction is reversed (the rotation direction is reversed). That is, the left and right circularly polarized light are mutually converted. The circularly polarized light that is reflected by the reflecting portion 25 and whose polarization direction is reversed is transmitted through the liquid crystal layer 21 while substantially maintaining the state, and the liquid crystal phase portion 5 is directed in the direction from the liquid crystal layer 21 toward the reflective display region of the laminated member 20a. In this case, a phase difference of ¼ wavelength is given and converted into linearly polarized light. At this time, the polarization axes of the linearly polarized light are substantially perpendicular to the linearly polarized light when traveling from the retardation layer 3 toward the liquid crystal layer 21.

  In addition, when the liquid crystal phase part 5 is a half-wave plate and the angle between the slow axis azimuth and the transmission axis of the polarizing plate is 20 degrees to 25 degrees or 60 degrees to 70 degrees, linearly polarized light is polarized The shaft rotates approximately 45 degrees. Thereafter, the polarized light transmitted through the liquid crystal layer 21 as it is is reflected by the reflecting portion 25 of the semi-transmissive reflective layer 27, and the polarization axis is rotated by 90 degrees. The reflected linearly polarized light further passes through the half-wave plate and moves the polarization axis by about 45 degrees. This linearly polarized light is in a state in which the polarization axes are substantially perpendicular to the linearly polarized light traveling from the retardation layer 3 toward the liquid crystal layer 21.

  And these linearly polarized light permeate | transmits the liquid crystal layer 21, maintaining the state. Since these linearly polarized lights have a polarization axis perpendicular to the transmission axis of the polarizing plate 23a, they are absorbed by the dye constituting the polarizing plate 23a and travel toward the viewer outside the liquid crystal display device. Almost disappears, making the viewer feel the dark display.

  On the other hand, when no voltage is applied, the light that travels in the direction from the laminated member 20a toward the liquid crystal layer 21 and becomes linearly polarized light has a ¼ wavelength phase difference when the liquid crystal phase portion 5 is a ¼ wavelength plate. Is granted. Further, when the liquid crystal layer 21 is transmitted, a phase difference of ¼ wavelength is given. At this time, the light transmitted through the liquid crystal layer 21 becomes a linearly polarized light because a phase difference of ½ wavelength is given to the linearly polarized light that is going to travel toward the liquid crystal phase part 5 from now on. Yes. Then, the linearly polarized light transmitted through the liquid crystal phase part 5 is reflected by the reflecting portion 25 of the semi-transmissive reflective layer 27, and linearly polarized light having the same polarization axis of light is formed.

  Then, the light reflected by the reflecting portion 25 is transmitted through the liquid crystal layer 21 and the liquid crystal phase part 5. At this time, a phase difference of ¼ wavelength is given, so at the position reaching the polarizing plate 23 a after all. A linearly polarized light having a polarization axis parallel to the transmission axis of the polarizing plate 23a is formed by giving a half-wave phase difference, and the linearly polarized light is transmitted through the polarizing plate 23a toward the outside of the liquid crystal display device. proceed.

  When the liquid crystal phase part 5 is a half-wave plate and the angle between the slow axis azimuth and the transmission axis of the polarizing plate is 20 degrees or more and 25 degrees or less, or 60 degrees or more and 70 degrees or less, the liquid crystal layer 21 And the liquid crystal phase part 5 are combined to form a broadband quarter-wave plate, and light that travels in the direction from the laminated member 20 a toward the liquid crystal layer 21 and becomes linearly polarized light passes through the liquid crystal phase part 5 and the liquid crystal layer 21. A phase difference of ¼ wavelength is given and converted into circularly polarized light. This circularly polarized light is reflected by the reflecting portion 25 of the transflective reflection layer 27, and its polarization direction is reversed (the rotation direction is reversed). That is, the left and right circularly polarized light are mutually converted. The circularly polarized light whose polarization direction is reversed by being reflected by the reflecting portion 25 is transmitted through the liquid crystal layer 21 and the liquid crystal phase part 5 in the direction from the liquid crystal layer 21 toward the reflective display region direction of the laminated member 20a. A wavelength phase difference is given and converted into linearly polarized light. At this time, the polarization axes of the linearly polarized light are substantially perpendicular to the linearly polarized light when traveling from the retardation layer 3 toward the liquid crystal layer 21.

  In this way, light comes out from the liquid crystal display device 50, and the light is perceived by the viewer, and the viewer is perceived as a bright display.

Next, transmissive display will be described.
In the transmissive display, light is incident in a direction toward the liquid crystal layer 21 from an outer position of the laminated member 20b. When light is incident, a component horizontal to the light transmission axis of the polarizing plate 23b is transmitted through the polarizing plate 23b to form linearly polarized light, which passes through the laminated member 20b and travels toward the transmissive display region. To the liquid crystal layer 21. This linearly polarized light passes through the liquid crystal layer 21 while maintaining its state substantially at the time of voltage application, that is, while maintaining the polarization axis substantially constant, and proceeds to the isotropic phase portion 4 of the retardation layer 3. At this time, there is almost no phase difference in the linearly polarized light, the state of the linearly polarized light is maintained, and the isotropic phase portion 4 is transmitted.

  Here, the polarizing plates 23a and 23b of the laminated members 21a and 21b are arranged in crossed Nicols, and the polarization axis of the linearly polarized light that has passed through the polarizing plate 23b is kept substantially constant until it reaches the polarizing plate 23a. Therefore, this linearly polarized light is absorbed by the polarizing plate 23a, and there is almost no light traveling toward the viewer, making the viewer feel dark display.

  On the other hand, when no voltage is applied, the linearly polarized light traveling to the liquid crystal layer 21 is given a half-wave phase difference when transmitted through the liquid crystal layer 21 and its polarization axis changes. That is, the polarization axes change so that the polarization axes of light are substantially orthogonal to each other before and after transmission through the liquid crystal layer 21. The polarizing plates 23a and 23b are arranged in crossed Nicols, and the light passing through the liquid crystal layer 21 is in a state in which the polarization axis is substantially parallel to the transmission axis of the polarizing plate 23a of the laminated member 20a. Pass 23a. Accordingly, light travels from the liquid crystal display device toward the viewer, and the viewer can feel the bright display.

  The liquid crystal display device 50 incorporates the optical element 1 by laminating the retardation layer 3 in the laminated member 20a that sandwiches the liquid crystal layer 21, and the quarter wavelength plate or 1 / Since the liquid crystal phase part 5 that exhibits the role of converting the polarization of the two-wave plate is formed, there is no need to separately prepare a quarter-wave plate such as a film material and attach it to the laminated members 20a and 20b. Further, it is not necessary to provide an adhesive layer for pasting, and the thickness can be easily reduced.

  Further, in the conventional liquid crystal display device, when a quarter wavelength plate is attached to the entire surface on the laminated member 20a side, light passing through the transmissive display region also passes through the quarter wavelength plate. Although the quarter-wave plate is also attached to the facing laminated member 20b side, according to the liquid crystal display device 50, the liquid crystal phase that exhibits the role of the quarter-wave plate only in the reflective display region. Since the site | part 5 is formed, installation of such a quarter wavelength plate to the laminated member 20b side can be made unnecessary.

  In the conventional liquid crystal display device, when performing transmissive display, part of the light incident from the laminated member 20b toward the liquid crystal layer 21 passes through the quarter-wave plate and travels toward the reflective display region. In this case, since the quarter-wave plate is attached to the laminated member 20b side, the light cannot be reused, and there is a limit in improving the light use efficiency. 50, it is possible to eliminate the need to install a quarter-wave plate. Therefore, even when the light has traveled toward the reflective display area when performing transmissive display, Since the light after being transmitted can pass through the polarizing plate 23b, the light can be caused to travel toward the transmissive display region, that is, the light can be reused.

  The liquid crystal display device of the present invention is not limited to the case where the optical element 1 ′ is incorporated on the laminated member 20a side in the liquid crystal display device of the first embodiment, and the optical element 1 ′ is incorporated on the laminated member 20b side. It may be (referred to as a liquid crystal display device of the second form) (FIG. 5B).

  In this case, the thickness of the liquid crystal phase part 5 is set so as to be a quarter wavelength plate with respect to the light transmitted through the liquid crystal phase part 5.

  In this liquid crystal display device 50b, a laminated member 20c is formed by removing the retardation layer 3 from the laminated member 20a shown in the description of the liquid crystal display device of the first embodiment.

  Further, in the liquid crystal display device 50b, a laminated member 20d in which the retardation layer 3 is incorporated between the base material 22b and the alignment film 24b in the laminated member 20b shown in the description of the liquid crystal display device of the first embodiment is formed. Has been. In the laminated member 20d, the retardation layer 3 is formed so that the liquid crystal phase part 5 and the isotropic phase part 4 correspond to the reflective display area and the transmissive display area, respectively.

  The liquid crystal display device 50b forms bright and dark states in the reflective display and the transmissive display as will be described below. First, the reflective display will be described.

  Light (external light) incident in the direction from the outside of the laminated member 20c toward the liquid crystal layer 21 passes through the polarizing plate 23a and becomes linearly polarized light having a polarization axis parallel to the transmission axis of the polarizing plate 23a. The liquid crystal layer 21 is transmitted while the state is substantially maintained. The linearly polarized light passes through the reflective display area of the laminated member 20d. The liquid crystal phase part 5 of the phase difference layer 3 is transmitted, and at that time, a phase difference of ¼ wavelength is given and converted into circularly polarized light. This circularly polarized light is reflected by the reflecting portion 25 of the transflective layer 27, and its polarization direction is reversed. The circularly polarized light, which is reflected by the reflecting portion 25 and whose polarization direction is reversed, travels through the liquid crystal phase portion 5 of the retardation layer 3 in the thickness direction toward the liquid crystal layer 21. When transmitted, the circularly polarized light has a quarter wavelength. Is converted into linearly polarized light. The linearly polarized light is transmitted through the liquid crystal layer 21 while maintaining the state. At this time, the polarization axis of the linearly polarized light is substantially perpendicular to the polarization axis of the linearly polarized light when traveling from the polarizing plate 23a toward the retardation layer 53, and the transmission axis of the polarizing plate 23a. It is also in a state perpendicular to. Therefore, the linearly polarized light is absorbed by the dye constituting the polarizing plate 23a and hardly proceeds toward the viewer outside the liquid crystal display device, and makes the viewer feel dark display.

On the other hand, when no voltage is applied, the light that has traveled in the direction from the laminated member 20 c toward the liquid crystal layer 21 and has become linearly polarized light is transmitted through the liquid crystal layer 21 and is given a phase difference of ¼ wavelength. Further, when the liquid crystal phase portion 5 of the retardation layer 3 is transmitted, a phase difference of ¼ wavelength is given. At this time, the light that has passed through the liquid crystal phase part 5 is in a state in which a phase difference of ½ wavelength is given to the light that is about to pass through the liquid crystal layer 21 toward the liquid crystal phase part 5. It is linearly polarized light. The linearly polarized light is reflected by the reflecting portion 25 of the transflective layer 27, and linearly polarized light is formed. At this time, the polarization axes of the linearly polarized light before and after the reflection by the reflecting portion 25 are the same.
Then, the linearly polarized light reflected by the reflecting portion 25 is transmitted through the liquid crystal phase part 5 and the liquid crystal layer 21, and at this time, a phase difference of ¼ wavelength is given, so at the position reaching the polarizing plate 23 a, Eventually, a phase difference of ½ wavelength is given, and linearly polarized light having a polarization axis parallel to the transmission axis of the polarizing plate 23a. Thus, the linearly polarized light can pass through the polarizing plate 23a and travel toward the outside of the liquid crystal display device 50b, and the light emitted from the liquid crystal display device 50b is perceived by the viewer, and the viewer feels a bright display. Get it.

Next, transmissive display will be described.
In the transmissive display, light enters the liquid crystal layer 21 from the outside of the laminated member 20d. When light is incident, a component horizontal to the transmission axis of the polarizing plate 23b of the light is transmitted through the polarizing plate 23b, linearly polarized light is formed, and is transmitted through the isotropic phase portion 4 of the retardation layer 3. Here, there is almost no phase difference in linearly polarized light. The linearly polarized light transmitted through the isotropic phase portion proceeds into the liquid crystal layer 21. When a voltage is applied, this linearly polarized light is transmitted through the liquid crystal layer 21 while maintaining its state substantially, that is, while maintaining the polarization axis substantially constant. The linearly polarized light reaches the position where the polarizing plate 23a of the laminated member 20c is disposed, but has a polarizing axis substantially perpendicular to the transmission axis of the polarizing plate 23a, and therefore cannot pass through the polarizing plate 23a. The viewer can feel the dark display almost without going out of the device 50b.

  On the other hand, when no voltage is applied, the linearly polarized light traveling from the laminated member 20d side toward the liquid crystal layer 21 is given a half-wave phase difference when transmitted through the liquid crystal layer 21, and the polarization axis is changed to change linearly. Polarized light is formed. At this time, the polarization axes of the linearly polarized light before and after transmission through the liquid crystal layer are substantially orthogonal to each other. Since the polarizing plates 23a and 23b are arranged in crossed Nicols, the linearly polarized light that has passed through the liquid crystal layer 21 has a polarization axis substantially parallel to the transmission axis of the polarizing plate 23a, and passes through the polarizing plate 23a. it can. Therefore, the linearly polarized light can travel toward the viewer toward the outside of the liquid crystal display device 50b, and the viewer can perceive a bright display.

  The liquid crystal display device according to the second embodiment has the same effects as the liquid crystal display device according to the first embodiment.

  In the liquid crystal display devices of the first and second embodiments, a colored layer as a functional layer may be incorporated in the laminated member 20. As such a liquid crystal display device, for example, in the liquid crystal display device 50 (a) shown in FIG. 3 (a) as the first embodiment, a shielding region is partitioned and formed on the base material 22a by the patterning, and then the light shielding is performed. A colored layer can be formed by forming a transparent colored region of one color or two or more colors in each section indicated by the region. This can be implemented as an active matrix device.

This liquid crystal display device performs reflective display and transmissive display in the same manner as the liquid crystal display device of the first embodiment, and has the same effects as the liquid crystal display device of the first embodiment.

In the liquid crystal display device 50 (b) shown in FIG. 3 (b) as a second embodiment, a shielding area is formed by patterning on the base material 22a, and then one color or each of the sections indicated by the light shielding area is formed. A colored layer can be formed by forming transparent colored regions of two or more colors. This can be implemented as an active matrix device. This liquid crystal display device performs reflective display and transmissive display in the same manner as the liquid crystal display device of the second embodiment, and has the same effects as the liquid crystal display device of the second embodiment.

  In the liquid crystal display device according to the first embodiment, the second embodiment, or a mode in which a colored layer is further provided, the element substrate layer in which the switching circuit 11 described with reference to FIG. May be incorporated. For example, such a liquid crystal display device can be specifically implemented by forming the element substrate layer by connecting the switching circuit 11 to the pixel electrode 29 constituting the electrode portion 28 of the laminated member 20b or the laminated member 20d. .

Example 1
As shown below, a colored layer and an alignment film were sequentially laminated on a substrate to prepare a base material, and a retardation layer was formed thereon to obtain Example 1 as an optical element of the present invention.

Preparation of Coloring Material Dispersion Used for Formation of Colored Layer A pigment dispersion type photoresist was used as a coloring material dispersion for black matrix (BM) and red (R), green (G), and blue (B) colored pixels. 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. It was obtained by mixing with a clear resist composition (containing polymer, monomer, additive, initiator and solvent). The obtained pigment-dispersed photoresist has the following composition with respect to what is used for forming a reflective display portion in RGB colored pixels. For the formation of the transmissive display part in the colored pixel, an RGB pigment dispersion type photoresist having a doubled amount of pigment contained in the pigment dispersion type photoresist used in the reflection type display part was used. A paint shaker (manufactured by Asada Tekko Co., Ltd.) was used as the disperser.

(Photoresist for black matrix)
Black pigment: 14.0 parts by weight (manufactured by Dainichi Seika Kogyo Co., Ltd., TM Black # 9550)
Dispersant: 1.2 parts by weight (Bic Chemie, Disperbyk 111)
2.8 parts by weight of polymer (Showa Polymer Co., Ltd., VR60)
Monomer: 3.5 parts by weight (manufactured by Sartomer, SR399)
Additives ··· 0.7 parts by weight (L-20 manufactured by Soken Chemical Co., Ltd.)
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)

(Photoresist for red (R) colored pixels)
・ Red pigment ... 5.0 parts by weight (CIPR254 (Ciba Specialty Chemicals, Chromophthal DPP Red BP))
・ Yellow pigment ... 1.0 parts by weight (CI PY139 (manufactured by BASF, Paliotor Yellow D1819))
・ Dispersant ... 3.0 parts by weight (manufactured by Zeneca Corporation, Solsperse 24000)
Monomer: 4.0 parts by weight (manufactured by Sartomer, SR399)
-Polymer 1 ... 5.0 parts by weight initiator ... 1.4 parts by weight (Ciba Geigy, Irgacure 907)
Initiator: 0.6 parts by weight (2,2′-bis (o-chlorophenyl) -4,5,4 ′, 5′-tetraphenyl-1,2′-biimidazole)
Solvent: 80.0 parts by weight (propylene glycol monomethyl ether acetate)

(Photoresist for green (G) colored pixels)
Green pigment: 3.8 parts by weight (CIPG7 (manufactured by Dainichi Seika, Seika Fast Green 5316P))
・ Yellow pigment: 2.2 parts by weight (CI PY139 (manufactured by BASF, Paliotor Yellow D1819))
・ Dispersant ... 3.0 parts by weight (Zeneca Co., Ltd., Solsperse 24000)
Monomer: 4.0 parts by weight (manufactured by Sartomer, SR399)
-Polymer 1 ... 5.0 parts by weight initiator ... 1.4 parts by weight (Ciba Geigy, Irgacure 907)
Initiator: 0.6 parts by weight (2,2'-bis (o-chlorophenyl) -4,5,4 ', 5'-tetraphenyl-1,2'-biimidazole)
Solvent: 80.0 parts by weight (propylene glycol monomethyl ether acetate)

(Blue (B) colored pixel photoresist)
Blue pigment: 4.6 parts by weight (CI PB15: 6 (BASF, Heliogen Blue L6700F))
・ Purple pigment: 1.4 parts by weight (CIPV23 (Clariant, Foster Palm RL-NF))
Pigment derivative: 0.6 part by weight (manufactured by Zeneca Corporation, Solsperse 12000)
Dispersant ··· 2.4 parts by weight (Zeneca Co., Ltd., Solsperse 24000)
Monomer: 4.0 parts by weight (manufactured by Sartomer, SR399)
-Polymer 1 ... 5.0 parts by weight initiator ... 1.4 parts by weight (Ciba Geigy, Irgacure 907)
Initiator: 0.6 parts by weight (2,2'-bis (o-chlorophenyl) -4,5,4 ', 5'-tetraphenyl-1,2'-biimidazole)
Solvent: 80.0 parts by weight (propylene glycol monomethyl ether acetate)

(Photoresist for pillar (CS))
Monomer: 9.0 parts by weight (manufactured by Sartomer, SR399)
-Polymer 1 ... 8.0 parts by weight initiator ... 2.0 parts by weight (Ciba Geigy, Irgacure 907)
Initiator: 1.0 part by weight (Ciba Geigy, Irgacure 365)
・ Solvent: 80.0 parts by weight (propylene glycol monomethyl ether acetate)

  The polymer 1 is based on 100 mol% of a copolymer of benzyl methacrylate: styrene: acrylic acid: 2-hydroxyethyl methacrylate = 15.6: 37.0: 30.5: 16.9 (molar ratio). 2-methacryloyloxyethyl isocyanate was added at 16.9 mol%, and the weight average molecular weight was 42500.

Prepare a borosilicate glass substrate (“Corning Co., Ltd.,“ 1737 material ”) as a substrate that has undergone a cleaning treatment for forming a colored layer. On the top surface of the borosilicate glass substrate, a colored material dispersion for each color as shown below And a colored layer was laminated on the substrate.

First, the BM photoresist prepared above is applied to a glass substrate by spin coating, pre-baked (pre-baked) at 90 ° C. for 3 minutes, and exposed using a mask formed in a predetermined pattern ( 100 mJ / cm ² ), followed by spray development using a 0.05% KOH aqueous solution for 60 seconds, followed by post-baking (baking) at 200 ° C. for 30 minutes to form a BM having a thickness of 1.2 μm A BM substrate was produced.

Next, a red (R) pigment-dispersed photoresist prepared for the reflective display unit is applied onto the BM substrate by spin coating, and pre-baked at 80 ° C. for 3 minutes. Ultraviolet exposure (200 mJ / cm ² ) was performed using a predetermined colored pattern photomask according to the pattern. Further, spray development using a 0.1% KOH aqueous solution was performed for 60 seconds, followed by post-baking (baking) at 200 ° C. for 30 minutes, and a red (R) film having a thickness of 1.2 μm at a predetermined position with respect to the BM pattern. ) A pattern of the reflective display portion in the colored pixel was formed.

  Next, the red (R) pigment-dispersed photoresist prepared for the transmissive display unit is applied in the same manner as the patterning method for the reflective display unit in the red (R) colored pixels, so that the transmissive display is performed. Part patterns were formed.

  Subsequently, reflection is performed for each of the green (G) colored pixels and the blue (B) colored pixels by using a method similar to the pattern forming method of the red (R) colored pixels in the reflective display portion and the transmissive display portion. A pattern of a mold display part and a transmissive display part was formed.

  Thus, a colored layer composed of BM, red colored pixels, green colored pixels, and blue colored pixels is formed on the glass substrate. The number of dots is 160 × (120 × 3 (RGB)), and the pixel size is 240 μm × (80 A base material on which a colored layer was formed so as to be × 3 (RGB) μm and the opening size of the transmissive display unit was 140 μm × 40 μm was obtained. The above (RGB) indicates the same for each colored pixel. For example, the number of dots indicates 160 × 120 for each RGB colored pixel.

Substrate preparation treatment An alignment film was prepared as a functional layer on a substrate on which the color filter was installed to prepare a substrate.

  A film composition liquid having a thickness of 700 mm was prepared by applying AL1254 manufactured by JSR Corporation as a film composition liquid constituting the alignment film and applying the film composition liquid on the substrate surface by flexographic printing.

Preparation of liquid crystal composition solution Polymerizable liquid crystal composition showing a nematic liquid crystal phase containing the above chemical formulas 4 (a) to (d) as crosslinkable liquid crystal molecules constituting the liquid crystal phase site and the isotropic phase site in the retardation layer. RMM34 (Merck), 25 parts by weight of this liquid crystal composition, 1 part by weight of a photopolymerization initiator (Ciba Geigy, “Irgacure 907”), and 74 parts by weight of toluene as a solvent were mixed. A liquid crystal composition solution was prepared.

Application of liquid crystal composition solution The above substrate was placed on a spin coater (product name 1H-360S, manufactured by MIKASA), and the liquid crystal composition solution was spin-coated on the alignment film. A coating film made of a liquid crystal composition solution was prepared on the alignment film.

Formation of the liquid crystal phase part The substrate on which the coating film was formed was heated at 100 ° C. for 5 minutes using a hot plate to substantially remove the solvent remaining in the coating film, and the liquid crystal contained in the coating film was removed from the liquid crystal phase. It was in a state.
Next, similarly to FIG. 4, the liquid crystal phase has a stripe shape with a width of about 100 μm and a length of 30 mm in the longitudinal direction, the interval is 140 μm, and coincides with the reflective portion on the colored layer. A photomask for patterning a plurality of portions was disposed on the substrate surface. Then, ultraviolet light having a wavelength of 365 nm was exposed to the coating film through a photomask at an exposure amount of 600 mJ / cm ² to form a liquid crystal phase site by cross-linking and polymerizing the liquid crystal contained in the liquid crystal phase planned site. .

Formation of the isotropic phase site After the formation of the liquid crystal phase site, the substrate on which the coating film was laminated was heated at 210 ° C. for 30 minutes, and the liquid crystal phase site was not formed in the coating film (isotropic phase) The liquid crystal contained in the predetermined part) was phase-transitioned into the isotropic phase, and the liquid crystal was cross-linked to form an isotropic phase part.

Formation of a flattening layer By spin-coating an overcoat material (IT-MP412SC-7 manufactured by The Inktec Co., Ltd.) as a coating liquid for forming a flattening layer, it is applied to the upper surface of the liquid crystal phase part and isotropic phase part. A coating film was prepared. The substrate on which the coating film was formed was pre-baked at 90 ° C. for 3 minutes using a hot plate, and then exposed to 365 nm ultraviolet light (80 mJ / cm ² ). Further, this base material was post-baked at 230 ° C. for 30 minutes to form a flattening layer having a thickness of 2 μm (the thickness of the flattening layer on the upper surface of the liquid crystal phase part), and Example 1 as an optical element was obtained.

  With respect to Example 1 thus obtained, the amount of step formation on the surface (that is, the upper surface of the planarizing layer) was measured as follows. In addition, measurement is performed for 9 samples in total at three different sampling positions, and the average value of the obtained values is shown as a result. same as below.

Measurement of step formation amount Using a stylus-type step meter (DEKTAK FPD-650 manufactured by Sloan) so that the measurement distance (step distance) is an isotropic phase region-liquid crystal phase region-isotropic phase region. Set, measure the level difference between the isotropic phase part and the liquid crystal phase part with a load of 5 mg and a measurement time of 20 seconds, and use this as the level difference generated on the top surface of the isotropic phase part (the height of the liquid crystal phase part is approximately uniform) Therefore, the step amount of the isotropic phase portion is measured based on the height of the liquid crystal phase portion). The measurement positions were 2 mm and 15 mm (center) from the end in the pattern length direction of FIG. In addition, about the equivalent optical element of the present Example 1, a part of the retardation layer is shaved to the surface of the base material, and this is also 2 mm from the end in the pattern length direction, and the film of the liquid crystal phase portion of the retardation layer at the center position The thickness was measured.

Observation of orientation characteristics Regarding the obtained optical elements, it was determined whether or not the orientation characteristics were good as follows.
Specifically, the polarizing plate is installed so as to be crossed Nicol, and an optical element is disposed between both polarizing plates, and the other polarizing plate is rotated while rotating the optical element in a state where light is irradiated to one of the polarizing plates. The state of transmitted light from the plate was observed using a polarizing microscope. In this observation, when the alignment axis of the optical element coincides with the transmission axis of one of the polarizing plates, a complete black state (dark state) is formed, and the alignment axis of the optical element is set to the transmission axis of the polarizing plate. It was judged by observing whether or not the isotropic phase portion was in a black state and a white state (bright state) was formed only in the liquid crystal phase portion when the optical element was installed at an angle of 45 °.

Example 2
Next, using the optical element of Example 1, a transflective liquid crystal display device was manufactured as Example 2 as shown below. Then, by visually observing the transmissive display and the reflective display, the adaptability to the transflective liquid crystal display device of Example 1 was determined.

  First, using Example 1 which is the optical element obtained above, a process for incorporating into a liquid crystal display device was performed as follows.

Formation of Multi-Gap Layer For Example 1, an OC material (IT-MP408 manufactured by The Inktec Co., Ltd.) was applied on the liquid crystal phase site through a plate having a pattern corresponding to the liquid crystal phase site of the retardation layer by screen printing. Overprinted. Furthermore, after pre-baking at 90 ° C. for 3 minutes and exposing to 365 nm ultraviolet rays (80 mJ / cm ² ), post baking (baking) at 230 ° C. for 30 minutes to form a multi-gap layer having a height of 1.5 μm at a predetermined position. did.
The height of the multi-gap layer is such that the distance from the most concave portion on the upper surface of the isotropic phase part to the upper surface of the multi-gap layer is 1.6 μm (that is, the maximum step amount between the liquid crystal phase part and the isotropic phase part) + The height of the multi-gap layer = 1.6 μm). The same applies to Example 4 and Comparative Example 4 below.

Columnar body formation A column (CS) photoresist prepared for a columnar body is applied to the optical element on which the multi-gap layer is formed by spin coating, and prebaked at 80 ° C. for 3 minutes to form a BM pattern. The film was exposed to ultraviolet rays of 365 nm (200 mJ / cm ² ) using a predetermined column photomask. Further, spray development using a 0.1% KOH aqueous solution was performed for 60 seconds, and then post-baked (baked) at 230 ° C. for 30 minutes to form a column pattern having a height of 1.6 μm at a predetermined position with respect to the BM pattern. Formed.

In addition to Example 1 in which the ITO multi-gap layer and the columnar body were formed, ITO, which is a transparent electrode material, was formed to a thickness of about 1500 mm by a known sputtering method.

Formation of Alignment Film Thereafter, polyimide or the like (SE-7511 made by Nissan Chemical Industries) was formed on the entire surface to form a coating film, and a rubbing treatment was performed to form a horizontal alignment film.

  Example 1 subjected to each of these processes was used as a color filter. Next, an array substrate in which a number of TFTs were arranged in a pattern corresponding to the formation pattern of the colored pixels of the colored layer in Example 1 was prepared as follows.

Preparation of an array substrate A non-alkali glass substrate (Corning Co., Ltd., “7059 material”) was prepared as a substrate subjected to a cleaning treatment, and a gate electrode was formed by forming a film with aluminum. At this time, the gate electrode was formed by patterning using a mask formed so as to correspond to the formation pattern of the colored pixels.

  Next, a gate insulating film such as a silicon nitride film having a thickness of 100 to 200 nm is formed on the substrate surface on which the gate electrode is formed by a plasma CVD method, and an amorphous silicon film having a thickness of 80 nm is further formed on the gate insulating film. A film was formed.

  Next, the substrate surface on which the amorphous silicon film was formed was patterned using a mask formed so as to correspond to the formation pattern of the colored pixels to form an amorphous silicon region. Furthermore, a silicon nitride film was formed on the entire substrate surface on which the amorphous silicon film was formed, and this was also patterned using a mask in the same manner as when the amorphous silicon film was formed to form an etching stopper.

Subsequently, phosphorus ions were implanted into the amorphous silicon film by ion doping at a dose of about 5 × 10 ¹⁵ ions / cm ² to form an N + layer.

  Thereafter, a photosensitive organic resin such as an acrylic resin was formed on the surface of the substrate on which the N + layer and the like were formed by spin coating to form an interlayer insulating film.

  Next, the silicon nitride film forming the gate insulating film and the acrylic resin layer forming the interlayer insulating film were opened to provide an opening, thereby forming a contact hole for connecting the pixel electrode and the TFT forming portion.

  Further, an Al (aluminum) metal thin film was formed to a thickness of about 100 nm by a sputtering method, and then patterned to correspond to the formation pattern of the reflective display portion of the optical element to form a reflective portion. Then, ITO (indium tin oxide), which is a transparent conductive material, is formed to a thickness of about 150 nm by a sputtering method, and then patterned to correspond to the formation pattern of the colored layer of the optical element to form a pixel electrode. did. A known method was used as a sputtering method for forming these metal thin films and pixel electrodes.

Furthermore, after that, a polyimide film is formed on the entire surface of the base material on which the pixel electrodes are formed to form a coating film, and an alignment film is formed by rubbing so as to be 90 ° with respect to the rubbing direction of the color filter. As a result, an array substrate was obtained.

Production of liquid crystal display device Approximately 15 mL of TN liquid crystal (ZLI-4792 manufactured by Merck & Co .; Δn = 0.088) is dropped as a driving liquid crystal on the glass substrate (array substrate) on which the TFT is formed, and the TN liquid crystal is sandwiched. As described above, the color filter of Example 1 obtained as described above is overlaid, and a UV curable resin is used as a sealing material so that the TN liquid crystal does not leak outside, and a pressure of 0.3 kgf / cm ² is applied at room temperature. The array substrate and the color filter were joined by exposure at a dose of 400 mJ / cm ² while being applied, and a cell in which a liquid crystal layer was formed between the array substrate and the color filter was formed. Further, for this cell, two polarizing plates are provided on the outer surfaces of the two array substrates and the color filter, respectively, so that the transmission axes thereof coincide with the rubbing directions of the color filter substrate and the array substrate, respectively. Arranged.

Thus, a liquid crystal display device (cell gap: transmissive display portion: 3.2 μm, reflective display portion: 1.6 μm) using the optical element obtained in Example 1 of the present invention was produced as Example 2. About the produced liquid crystal display device, the display nonuniformity in the transmission / reflection display was observed.

Example 3
An optical element was produced in the same manner as in Example 1 except that IT-MP408 was used as the OC material for the planarization layer, and Example 3 was obtained. And like Example 1, the surface level | step difference was measured and the orientation characteristic was confirmed.

Example 4
The optical element of Example 3 is used instead of the optical element of Example 1, and the height of the multi-gap layer is 1.4 μm in consideration of the step of 0.2 μm in the central portion between the liquid crystal phase part and the isotropic phase part. A liquid crystal display device was produced in the same manner as in Example 2 except that it was set as Example 4. In the same manner as in Example 2, display unevenness in the transmission / reflection display was observed.

Comparative Example 1
An optical element was obtained as Comparative Example 1 in the same manner as in Example 1 except that the retardation layer was formed as follows. First, a liquid crystal composition is applied on the surface of the substrate to form a coating film, which is in a liquid crystal state oriented in a desired direction, and then covered with a photomask showing a pattern expected as a liquid crystal phase part, and then exposed to ultraviolet rays. Mask exposure was performed with an amount of 100 mJ / cm ² , and the crosslinkable liquid crystal molecules constituting the liquid crystal phase site were polymerized and immobilized. Subsequently, the non-liquid crystal phase part (unexposed part) was developed with a solvent, and after development, the substrate was heated at 210 ° C. for 30 minutes to form a retardation layer. No planarization layer was provided on the upper surface of the liquid crystal phase part. The film thickness of the liquid crystal phase part was 1.6 μm.
And like Example 1, the surface level | step difference was measured and the orientation characteristic was confirmed.

Comparative Example 2
A liquid crystal display device was produced in the same manner as in Example 2 except that the optical element of Comparative Example 1 was used instead of the optical element of Example 1 and the multi-gap layer was not provided. As in Example 2, display unevenness in the transmission / reflection display was observed.

Comparative Example 3
An optical element was produced in the same manner as in Example 1 except that the planarizing layer was not formed, and Comparative Example 3 was obtained. The step between the liquid crystal phase part and the isotropic phase part was 0.4 μm at 2 mm from the end of the pattern and 0.9 μm at the center. The liquid crystal phase part had a thickness of 1.6 μm. In addition, the orientation characteristics were confirmed in the same manner as in Example 1.

Comparative Example 4
In addition, the optical element of Comparative Example 3 was used and the height of the multi-gap layer was set to 0.7 μm in consideration of a step difference of 0.9 μm at the central portion between the liquid crystal phase part and the isotropic phase part. A liquid crystal display device was produced in the same manner as in Example 1 and used as Comparative Example 4. The display unevenness in the transmission / reflection display was observed. The above results are shown in Table 1 below.

According to the present invention, an optical element having flatness can be obtained by providing a planarizing layer on the retardation layer, and as shown in Table 1, the optical element obtained by the present invention was used. The liquid crystal display device is more uniform than a liquid crystal display device (Comparative Example 4) using an optical element in which the level difference between the isotropic phase portion and the liquid crystal phase portion is different in the pattern length direction without providing a flattening layer. Is obtained. In addition, display equivalent to that of a liquid crystal display device (Comparative Example 2) manufactured by a conventional method that needs to be developed is possible.
Therefore, according to the present invention, a flat optical element can be obtained, and a liquid crystal display device at a level comparable to that of the conventional method can be obtained more easily than the conventional method.

(A) (b) It is the schematic which shows the cross-section which shows the example of the embodiment of the optical element of this invention. It is a schematic plan view which shows one embodiment of the optical element provided with the switching circuit. (A) (b) It is the schematic which shows the example of the embodiment of the liquid crystal display device of this invention provided with the optical element. It is a top view which shows an example of the patterning design of a liquid crystal phase site | part and an isotropic phase site | part. It is the schematic which shows the cross-section of the conventional liquid crystal cell. It is the schematic of the cross-sectional structure observed from the XX cross section of the liquid crystal cell shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical element 2 Base material 3, 103 Phase difference layer 4, 102 Isotropic phase part 5, 101 Liquid crystal phase part 6 Flattening layer 7, 31, 106 Multigap layer 11 Switching circuit 12 Reflective electrode part 13 Signal line 14 Scan line DESCRIPTION OF SYMBOLS 15 Drain electrode 16 Source electrode 17 Gate electrode 18 Each pixel electrode 19 Transparent electrode part 20, 20a, 20b Laminated member 21, 109 Drive liquid crystal layer (liquid crystal layer)
22, 22a, 22b Substrate 23, 23a, 23b Polarizing plate 24, 24a, 24b, 105 Alignment film 25 Reflecting portion 26 Opening portion 27 Transflective layer 28 Electrode portion 29 Pixel electrode 30 Counter electrode 50, 50a, 50b Liquid crystal display device 100 liquid crystal cell 104 transparent glass substrate 107 columnar body 108 counter substrate

Claims (7)

An optical element comprising a light-transmitting base material and a retardation layer formed on the base material,
The phase difference layer isotropically forms a liquid crystal phase site in which crosslinkable liquid crystal molecules formed directly or indirectly on the substrate are fixed in a liquid crystal phase state, and a crosslinkable liquid crystal molecule adjacent to the liquid crystal phase site. A phase difference control function comprising an isotropic phase portion fixed in a phase state and a flattening layer provided so as to cover an upper surface of the liquid crystal phase portion and the isotropic phase portion. An optical element. The optical element according to claim 1, wherein a surface step of the planarizing layer is within 0.2 μm. A colored layer comprising light-transmitting colored portions of at least two colors is laminated between the base material and the retardation layer, or directly or indirectly on the retardation layer. The optical element according to any one of claims 1 to 3. A columnar body for cell gap control is directly formed on the upper surface of the planarizing layer, and at least a part of the columnar body is formed in the isotropic phase region in plan view. The optical element according to claim 1 to 3. The reflective part is provided between the said base material and the said phase difference layer, and the said reflective part is selectively formed under the said liquid crystal phase site | part, The Claim 1 thru | or 4 characterized by the above-mentioned. An optical element according to 1. The array substrate and the facing substrate are opposed to each other while maintaining a certain distance, and a driving liquid crystal material is formed on the inner side surface between these substrates to form a driving liquid crystal layer, and a polarizing plate is laminated on the outer side surfaces of both substrates. And a transflective liquid crystal display device comprising a reflective display region and a transmissive display region in a sub-pixel,
A transflective liquid crystal device using the optical element according to any one of claims 1 to 5 as the array substrate or the facing substrate. A production method for producing an optical element having a retardation control function by forming at least a retardation layer on a light-transmitting substrate,
Forming the retardation layer comprises:
A coating film forming step of coating a liquid crystal composition containing at least a crosslinkable liquid crystal molecule directly or indirectly on a light-transmitting substrate;
An alignment step of aligning the crosslinkable liquid crystal molecules present in the coating film in a desired direction to form a liquid crystal phase;
The coating film is irradiated with ultraviolet rays or an electron beam through a photomask to polymerize the crosslinkable liquid crystal molecules in a liquid crystal phase, thereby polymerizing and fixing only the crosslinkable liquid crystal molecules in the irradiated portion. A liquid crystal phase site forming step for forming a site;
The substrate on which the coating film is formed is heated to bring the crosslinkable liquid crystal molecules in an uncured state into an isotropic phase state, and the crosslinkable liquid crystal molecules are polymerized and fixed in the heated state to form an isotropic phase. An isotropic phase site forming step for forming a site;
A resin composition containing at least a light-transmitting curable resin is directly applied to the upper surface of the liquid crystal phase part and the isotropic phase part to form a coating film, and the curable resin contained in the coating film A planarization layer forming step of forming a planarization layer by curing
A method of manufacturing an optical element having a phase difference control function, comprising:

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