JP4788453B2 - Liquid crystal device, manufacturing method thereof, and electronic apparatus - Google Patents

Description

  The present invention relates to a liquid crystal device, a manufacturing method thereof, and an electronic apparatus.

A transflective liquid crystal device is widely used as a display device such as a mobile phone or a portable information terminal. By the way, in a transflective liquid crystal device, it is necessary to adjust the phase difference between display modes in order to realize reflective display and transmissive display using a single liquid crystal layer. Therefore, in Patent Document 1 below, appropriate reflective display and transmissive display can be obtained by providing a retardation layer having a phase difference different between the transmissive display area and the reflective display area.
JP 2003-322857 A

According to the liquid crystal device described in Patent Document 1, since the retardation layer is built in the liquid crystal cell, there is no need to provide a λ / 4 retardation plate for adjusting the retardation on the outside of the liquid crystal cell. Therefore, it is possible to reduce the thickness and cost of the liquid crystal device. However, since the retardation layer provided on the inner surface side of the liquid crystal cell is formed using a polymerizable liquid crystal oligomer or cholesteric liquid crystal, the heat resistance is low. On the other hand, the constituent members of the liquid crystal device formed together with the retardation layer include:
Some of them require heating to obtain characteristics such as ITO (indium tin oxide) film. If heating is performed to obtain the characteristics of these constituent members, the retardation of the retardation layer is shifted and desired. The display characteristics may not be obtained.

The present invention has been made in view of the above-described problems of the prior art, and includes a liquid crystal device having a retardation layer having good optical characteristics, excellent display quality, and capable of being manufactured at a high yield. It aims to provide a method.

The liquid crystal device according to the present invention includes a first substrate and a second substrate that are arranged to face each other with a liquid crystal layer interposed therebetween, and a polyimide material having a first baking temperature on the liquid crystal layer side of the first substrate. A first alignment film is formed, a retardation layer is formed on the liquid crystal layer side of the second substrate, and a second alignment film made of a polyimide material having a second baking temperature is formed on the retardation film. The first alignment film and the second alignment film are made of different polyimide materials, and the second baking temperature of the second alignment film is set to be different from that of the first alignment film. not low than 1 of the firing temperature.

Thus, the second alignment film covering the retardation layer uses a polyimide film whose firing temperature is lower than that of the first alignment film, thereby eliminating the need for high-temperature heating at the time of formation, and relatively good alignment regulating power. It is possible to prevent the optical properties of the retardation layer from being impaired. Therefore, according to the present invention, it is possible to provide a liquid crystal device that includes a retardation layer having good optical characteristics, is excellent in display quality, and can be manufactured at a high yield.

On the first substrate, a first electrode and a second electrode that generate an electric field for driving the liquid crystal layer between them.
A configuration in which electrodes are formed is preferable. That is, a liquid crystal device in which no electrode is formed on the second substrate side on which the second alignment film having a low baking temperature is formed is preferable. As the liquid crystal device having such a configuration, an IPS (In-Plane Switching) method or an FFS (Frin)
An example of the liquid crystal device is a horizontal electric field type such as a ge Field Switching type. In a liquid crystal device in which an electrode is formed only on one substrate, a good alignment regulating force is required for the alignment film of the substrate on which the electrode is formed, but for the alignment film on the substrate on which no electrode is formed, Since the necessary alignment regulating force is small, it is suitable as a form of the liquid crystal device of the present invention in which the firing temperature of the second alignment film is low.

A reflective display region for performing reflective display and a transmissive display region for performing transmissive display are provided in one sub-pixel region, and the retardation layer is selectively formed in the reflective display region. You can also. That is, the liquid crystal device of the present invention can be configured as a transflective liquid crystal device.

Further, the thickness of the liquid crystal layer may be different between the reflective display region and the transmissive display region depending on the thickness of the retardation layer. That is, the retardation layer may function as a liquid crystal layer thickness adjusting layer for realizing a multi-gap structure.

In addition, a liquid crystal layer thickness adjusting layer may be formed on the opposite side of the retardation layer from the liquid crystal layer so that the reflective display region and the transmissive display region have different liquid crystal layer thicknesses. it can. A liquid crystal layer thickness adjusting layer in a multi-gap structure can also be provided separately. In such a configuration, in the present invention, a liquid crystal layer thickness adjusting layer is provided between the retardation layer and the second substrate. It is because it can prevent that the optical characteristic of a phase difference layer is impaired by the heating at the time of formation of the liquid-crystal layer thickness adjustment layer comprised with a transparent resin material.

The method for manufacturing a liquid crystal device according to the present invention includes a first substrate and a second substrate arranged to face each other with a liquid crystal layer interposed therebetween, and a first alignment film is formed on the liquid crystal layer side of the first substrate, A method of manufacturing a liquid crystal device in which a retardation layer and a second alignment film covering the retardation layer are formed on the liquid crystal layer side of the second substrate, the step of forming the retardation layer on the second substrate; Applying an alignment film forming material so as to cover the retardation layer, and baking the applied alignment film forming material at a temperature lower than the phase transition temperature of the constituent material of the retardation layer. Mu

According to this manufacturing method, since the second alignment film is heated at a heating temperature lower than the phase transition temperature of the retardation layer, the alignment of the polymer liquid crystal or the like constituting the retardation layer is disturbed and the optical characteristics are impaired. Can be prevented, and a liquid crystal device excellent in display quality can be manufactured.

Soluble polyimide is preferably used as the alignment film forming material. The imidization rate of the polyimide film to be formed is hardly changed by heating, and a desired imidization rate can be easily obtained.
This is because the alignment regulating force of the alignment film is also stabilized. Also, it is advantageous in that the heating temperature can be further lowered depending on the selection of the solvent.

The method of manufacturing a liquid crystal device according to the present invention includes a liquid crystal layer thickness adjusting layer that varies the thickness of the liquid crystal layer on the second substrate in a plane area of the sub-pixels prior to the step of forming the retardation layer. It can also be set as the manufacturing method which has the process of forming. By using such a manufacturing method, the retardation layer can be prevented from being heated, and a multi-gap liquid crystal device including a retardation layer having good optical characteristics can be manufactured.

The method of manufacturing a liquid crystal device according to the present invention includes forming a first electrode and a second electrode that generate an electric field for driving the liquid crystal layer between the first substrate, the first electrode, Forming the first alignment film covering the second electrode; and forming the second alignment film on the first substrate on which the first electrode, the second electrode, and the first alignment film are formed. a step of bonding via the second substrate and the sealant was, that having a. According to this manufacturing method, a lateral electric field type liquid crystal device including a retardation layer having good optical characteristics can be manufactured with a high yield.

Next, an electronic apparatus of the present invention, obtain Bei the liquid crystal device of the present invention described above. According to this configuration, it is possible to provide an electronic apparatus including a display unit that is excellent in display quality and inexpensive.

(First embodiment)
Hereinafter, a liquid crystal device according to a first embodiment of the present invention will be described with reference to the drawings.

The liquid crystal device according to the present embodiment is an FFS (Fringe Field Switchi) among horizontal electric field methods in which an image is displayed by controlling an orientation by applying an electric field (lateral electric field) in the substrate surface direction to liquid crystal.
ng) is a liquid crystal device adopting a method called a method. In addition, a color liquid crystal device having a color filter on a substrate, in which one pixel is composed of three sub-pixels that emit light of each color of R (red), G (green), and B (blue). It has become. Accordingly, a display area which is a minimum unit constituting display is referred to as a “sub-pixel area”, and a display area including a set (R, G, B) of sub-pixels is referred to as a “pixel area”.

FIG. 1 is a circuit configuration diagram of a plurality of sub-pixels formed in a matrix that constitutes the liquid crystal device of the present embodiment. FIG. 2 is a plan configuration diagram of an arbitrary one subpixel of the liquid crystal device 100. FIG. 3 is a partial cross-sectional configuration diagram taken along the line AA ′ of FIG.

As shown in FIG. 3, the liquid crystal device 100 according to the present embodiment includes TFTs arranged to face each other.
An array substrate (first substrate) 10, a counter substrate (second substrate) 20, and a liquid crystal layer 50 sandwiched between these substrates 10 and 20, and a backlight 90 is arranged on the outer surface side of the TFT array substrate 10. This is a transflective liquid crystal device.

In each figure, in order to make each layer and each member recognizable on the drawing,
The scale is different for each layer and each member.

As shown in FIG. 1, a plurality of sub-pixel areas formed in a matrix that form an image display area of the liquid crystal device 100 are respectively connected to a pixel electrode 9 and a pixel electrode 9. The TFT 30 for switching control is formed, and the data line driving circuit 101 is formed.
A data line 6 a extending from the TFT is electrically connected to the source of the TFT 30. The data line driving circuit 101 supplies the image signals S1, S2,..., Sn to each pixel via the data line 6a. The image signals S1 to Sn may be supplied line-sequentially in this order, or may be supplied for each group to a plurality of adjacent data lines 6a.

A scanning line 3 a extending from the scanning line driving circuit 102 is electrically connected to the gate of the TFT 30, and scanning signals G 1 and G 2 supplied in a pulsed manner from the scanning line driving circuit 102 to the scanning line 3 a at a predetermined timing. ,..., Gm are applied to the gate of the TFT 30 in line order in this order. The pixel electrode 9 is electrically connected to the drain of the TFT 30.
Then, the TFT 30 as a switching element is turned on for a certain period by the input of the scanning signals G1, G2,..., Gm, so that the image signals S1, S supplied from the data line 6a are turned on.
2, ..., Sn are written into the pixel electrode 9 at a predetermined timing.

Image signals S1, S2,..., Sn written to the liquid crystal via the pixel electrode 9 are held for a certain period between the common electrode facing the pixel electrode 9 via the liquid crystal. Here, in order to prevent the held image signal from leaking, a storage capacitor 70 is connected in parallel with the liquid crystal capacitor formed between the pixel electrode 9 and the common electrode. The storage capacitor 70 is provided between the drain of the TFT 30 and the capacitor line 3b.

As shown in FIG. 2, in the sub-pixel region of the liquid crystal device 100, a pixel electrode (first electrode) 9 that is substantially ladder-shaped in a plan view and that is long in the Y-axis direction is disposed so as to overlap the pixel electrode 9 in a planar manner. And a substantially flat solid common electrode (second electrode) 19 is provided. A columnar spacer 40 for holding the TFT array substrate 10 and the counter substrate 20 at a predetermined interval is provided at the corner (or the gap between the subpixel regions) at the upper left end of the subpixel region in the figure. It is installed.

The pixel electrode 9 includes a plurality of (15 in the figure) strip-like electrodes 9c extending substantially in the X-axis direction and a substantially rectangular frame-like frame in plan view connected to both ends of the strip-like electrodes 9c in the left-right direction in the figure. Part 9a
The plurality of strip electrodes 9c are arranged in the Y-axis direction at equal intervals in parallel with each other.

The common electrode 19 is formed so as to cover the reflective layer 29 partially provided in the sub-pixel region shown in FIG. In the present embodiment, the common electrode 19 is ITO (indium tin oxide).
The reflective layer 29 is a dielectric in which a light reflective metal film such as aluminum or silver or a dielectric film (SiO ₂ and TiO ₂ or the like) having different refractive indexes is laminated. It consists of a laminated film (dielectric mirror). The liquid crystal device 100 preferably has a function of scattering the reflected light from the reflective layer 29. With this configuration, the visibility of the reflective display can be improved.

The common electrode 19 has a configuration in which the transparent electrode made of a transparent conductive material and a reflective electrode made of a light-reflective metal material are planar in addition to the structure formed so as to cover the reflective layer 29 as in the present embodiment. A transparent electrode arranged corresponding to the reflective display area, and a reflective electrode arranged corresponding to the reflective display area, both electrodes being a transmissive display area and a reflective display Those that are electrically connected to each other between the regions (boundary portions) can also be employed.
In this case, the transparent electrode and the reflective electrode constitute a common electrode that generates an electric field between the pixel electrode 9 and the reflective electrode also functions as a reflective layer in the sub-pixel region.

In the sub-pixel region, a data line 6a extending in the X-axis direction, a scanning line 3a extending in the Y-axis direction, and a capacitor line 3b extending in parallel with the scanning line 3a adjacent to the scanning line 3a are formed. A TFT 30 is provided in the vicinity of the intersection of the data line 6a and the scanning line 3a. T
The FT 30 includes a semiconductor layer 35 made of an island-shaped amorphous silicon film partially formed in a plane region of the scanning line 3a, and a source electrode 6 formed to partially overlap the semiconductor layer 35 in a plane.
b and a drain electrode 132. The scanning line 3 a functions as a gate electrode of the TFT 30 at a position overlapping the semiconductor layer 35 in plan view.

The source electrode 6b of the TFT 30 has a substantially L shape in plan view extending from the data line 6a and extending to the semiconductor layer 35, and the drain electrode 132 extends from above the semiconductor layer 35 to the −Y side and substantially rectangular in plan view. The capacitor electrode 131 having a shape is electrically connected. On the capacitor electrode 131, a contact portion 9b of the pixel electrode 9 is disposed so as to advance from the −Y side, and the capacitor electrode 131 and the pixel are connected via a pixel contact hole 45 provided at a position where they are two-dimensionally overlapped. The electrode 9 is electrically connected. The capacitor electrode 131 is disposed in the plane area of the capacitor line 3b, and the storage capacitor 7 having the capacitor electrode 131 and the capacitor line 3b facing each other in the thickness direction at the position.
0 is formed.

In the cross-sectional structure shown in FIG. 3, the liquid crystal device 100 has a liquid crystal layer 50 sandwiched between a TFT array substrate (first substrate) 10 and a counter substrate (second substrate) 20 that are arranged to face each other. The liquid crystal layer 50 is sealed between the substrates 10 and 20 by a sealing material (not shown) provided along the edge of the region where the TFT array substrate 10 and the counter substrate 20 face each other. ing. A polarizing plate 14 is provided on the outer surface side (the side opposite to the liquid crystal layer) of the TFT array substrate 10, and a polarizing plate 24 is provided on the outer surface side of the counter substrate 20. A backlight (illuminating device) 90 including a light source, a light guide plate 91, and a reflection plate 92 is provided on the back surface side (the lower surface side in the drawing) of the TFT array substrate 10.

The TFT array substrate 10 has a substrate body 10A made of glass, quartz, plastic, or the like as a base, and a scanning line 3a and a capacitor line 3 are provided on the inner surface side (liquid crystal layer 50 side) of the substrate body 10A.
b is formed, and the gate insulating film 11 is formed to cover the scanning line 3a and the capacitor line 3b. A semiconductor layer 35 of amorphous silicon is formed on the gate insulating film 11,
A source electrode 6 b and a drain electrode 132 are formed so as to partially run over the semiconductor layer 35. A capacitor electrode 131 is integrally formed on the right side of the drain electrode 132 in the figure. The semiconductor layer 35 is disposed to face the scanning line 3 a via the gate insulating film 11, and the scanning line 3 a constitutes the gate electrode of the TFT 30 in the facing region. The capacitor electrode 131 is disposed opposite to the capacitor line 3b via the gate insulating film 11, and a storage capacitor 70 using the gate insulating film 11 as a dielectric film is formed in a region where the capacitor electrode 131 and the capacitor line 3b are opposed to each other. Has been.

Covering the semiconductor layer 35, the source electrode 6b, the drain electrode 132, and the capacitor electrode 131,
A first interlayer insulating film 12 is formed, a resin layer 39 is formed on a part of the first interlayer insulating film 12, and a reflective layer 29 is formed on the resin layer 39. A common electrode 19 made of a transparent conductive material such as ITO is formed so as to cover the reflective layer 29 and the first interlayer insulating film 12. The resin layer 39 has a concavo-convex shape on the surface thereof, and the reflection layer 29 formed with a concavo-convex surface following the concavo-convex shape constitutes a light-scattering reflecting means.

In this way, the liquid crystal device 10 of this embodiment in which the reflective layer 29 is partially formed in the sub-pixel region.
In 0, the formation region of the reflective layer 29 in one subpixel region shown in FIG.
Reflective display region R that reflects and modulates light that is incident from outside and transmits through the liquid crystal layer 50.
It has become. In addition, a light transmission region outside the formation region of the reflective layer 29 is a transmission display region T that performs display by modulating light incident from the backlight 90 and transmitted through the liquid crystal layer 50.

A second interlayer insulating film 13 made of silicon oxide or the like is formed so as to cover the common electrode 19. A pixel electrode 9 made of a transparent conductive material such as ITO is formed on the surface of the second interlayer insulating film 13 on the liquid crystal layer side. A first alignment film 18 made of polyimide is formed so as to cover the pixel electrode 9 and the second interlayer insulating film 13.

A pixel contact hole 45 penetrating the first interlayer insulating film 12 and the second interlayer insulating film 13 and reaching the capacitor electrode 131 is formed, and a contact portion 9 b of the pixel electrode 9 is partially embedded in the pixel contact hole 45. Thus, the pixel electrode 9 and the capacitor electrode 131 are electrically connected. The common electrode 19 has an opening corresponding to the region where the pixel contact hole 45 is formed, and the pixel electrode 9 and the capacitor electrode 131 are electrically connected through the opening, and the common electrode 19 19 and the pixel electrode 9 are configured not to be short-circuited.

On the other hand, the counter substrate 20 has a substrate body 20A made of glass, quartz, plastic, or the like as a base, and a color filter that transmits different color light for each sub-pixel is provided on the inner surface side (liquid crystal layer 50 side) of the substrate body 20A. The provided CF layer 22 is formed. The color filter is
It is preferable that the subpixel is divided into two types of color material regions having different chromaticities. Specifically, a first color material region is provided corresponding to the planar region of the transmissive display region T, and a second color material region is provided corresponding to the planar region of the reflective display region R. A configuration in which the chromaticity of one color material region is larger than the chromaticity of the second color material region can be employed. Moreover, it is good also as a structure which provides a non-colored area | region in a part of reflective display area | region R. With this configuration,
It is possible to prevent the chromaticity of the display light from differing between the transmissive display region T where the display light is transmitted only once through the color filter and the reflective display region R where the display light is transmitted twice, thereby improving the appearance of the reflective display and the transmissive display. The display quality can be improved by aligning them. The CF layer 22 can also be formed on the TFT array substrate 10 side.

On the liquid crystal layer 50 side of the CF layer 22, a retardation layer 23 is formed corresponding to the reflective display region R. In the present embodiment, the retardation layer 23 imparts a phase difference of approximately ½ wavelength (λ / 2) to light having a vibration direction parallel to the optical axis direction. This is a so-called inner surface retardation layer provided on the inner surface side of 20A. The retardation layer 23 may be formed by a method in which a polymer liquid crystal (cholesteric liquid crystal or the like) solution or a liquid crystal monomer (or liquid crystal oligomer) solution is applied onto an alignment film and is oriented in a predetermined direction when dried and solidified. it can.

In the present embodiment, the retardation layer 23 also functions as a liquid crystal layer thickness adjusting layer for making the thickness of the liquid crystal layer 50 in the reflective display region R smaller than the thickness of the liquid crystal layer 50 in the transmissive display region T. It has become a thing. In the transflective liquid crystal display device, incident light to the reflective display region R passes through the liquid crystal layer 50 twice, but incident light to the transmissive display region T passes through the liquid crystal layer 50 only once. As a result, if the retardation of the liquid crystal layer 50 is different between the reflective display region R and the transmissive display region T, a difference in light transmittance occurs, and a uniform image display cannot be obtained. Therefore, a so-called multi-gap structure is realized by forming the retardation layer 23 so as to protrude toward the liquid crystal layer 50. Specifically, the layer thickness of the liquid crystal layer 50 in the reflective display region R is set to about half the layer thickness of the liquid crystal layer 50 in the transmissive display region T, and the liquid crystal layer 50 in the reflective display region R and the transmissive display region T The retardation is set substantially the same. Thereby, a uniform image display can be obtained in the reflective display region R and the transmissive display region T.

In the present embodiment, the liquid crystal constituting the liquid crystal layer 50 has a refractive index anisotropy of Δn = 0.1,
Dielectric anisotropy epsilon _// is used one with 10, a positive anisotropy of ε _⊥ = 4. The transmissive display region T has a liquid crystal thickness of 3.5 μm, the reflective display region R has a liquid crystal thickness of 1.4 μm, and the retardation layer 23 has a thickness of 2.1 μm.

In the present embodiment, the retardation layer 23 is selectively formed in the reflective display region R. However, from the viewpoint of the function as the retardation layer, the retardation for the transmitted light in the transmissive display region T and the reflective display region R From the viewpoint of the function as the liquid crystal layer thickness adjusting layer, the reflective display region R protrudes more toward the liquid crystal layer 50 than in the transmissive display region T from the viewpoint of the function as the liquid crystal layer thickness adjusting layer. As long as it is formed, a retardation layer having a different thickness depending on the part may be formed on the CF layer 22. That is, a retardation layer having a thin film thickness and a small phase difference in the transmissive display region T and a thick film thickness and a large phase difference in the reflective display region R may be formed.

A second alignment film 28 made of polyimide is formed so as to cover the retardation layer 23 and the CF layer 22. In the liquid crystal device of this embodiment, the first alignment film 18 of the TFT array substrate 10 and the second alignment film 28 of the counter substrate 20 are both alignment films made of polyimide, but are made of different materials and cured. The firing temperature specific to the material is different. That is,
The firing temperature of the polyimide material constituting the second alignment film 28 formed so as to cover the retardation layer 23 (
The curing temperature) is lower than the firing temperature (curing temperature) of the polyimide material constituting the first alignment film 18 formed so as to cover the pixel electrode 9. In general, the higher the imidization rate, the greater the alignment regulating force on the liquid crystal of the polyimide film can be increased, but in order to obtain a polyimide film with a high imidization rate, a high-temperature heating (firing) step of about 220 to 230 ° C. or higher. Therefore, if such heating is performed after the retardation layer 23 is formed, the orientation of the polymer liquid crystal or the like constituting the retardation layer 23 is disturbed or the polymer liquid crystal itself is altered. In this case, the desired optical characteristics (phase difference) may not be obtained.

Therefore, in the present invention, the second alignment film 28 covering the retardation layer 23 is used for the TFT array substrate 1.
By forming a polyimide film using a polyimide material having a firing temperature lower than the firing temperature of the polyimide material constituting the first alignment film 18 of 0, heating exceeding 200 ° C. is unnecessary, and relatively good The optical properties of the retardation layer 23 are prevented from being impaired while obtaining a good alignment regulating force. The imidation ratio of the second alignment film 28 provided in the liquid crystal device 100 of the present embodiment is preferably about 70% to 80%. A polyimide film having an imidization ratio in such a range can be formed by heating at less than 200 ° C., and a necessary alignment regulating force can be obtained.

In addition, for the first alignment film 18 on the TFT array substrate 10 side where the retardation layer 23 is not formed, a polyimide film having a relatively high baking temperature specific to the material to be cured is used, so that the alignment regulating force on the liquid crystal can be reduced. It is assumed to be good and display quality is prevented from being lowered. In the case of this embodiment, the imidation ratio of the first alignment film 18 is preferably 90% or more.

In a horizontal electric field type liquid crystal device like the liquid crystal device of this embodiment, an electrode is formed only on one substrate, and the liquid crystal is driven by a voltage applied to the electrode. In the first alignment film 18 provided on the TFT array substrate 10 on which the pixel electrode 9 and the common electrode 19) are formed, a good alignment regulating force is required, while on the second substrate 20 provided on the counter substrate 20 on which no electrode is formed. The alignment film 28 has little influence on the display quality even if the alignment regulating force is slightly inferior to that of the first alignment film 18. Therefore, the present invention is a technique that can be suitably used for a horizontal electric field type liquid crystal device in which an electrode for driving liquid crystal is provided only on one substrate.

In addition, the optical axis arrangement | positioning in each optical member in the liquid crystal device of this embodiment can be comprised as follows, for example.

The transmission axis of the polarizing plate 14 on the TFT array substrate 10 side and the transmission axis of the polarizing plate 24 on the counter substrate 20 side are arranged to be orthogonal to each other, and the transmission axis of the polarizing plate 24 is X shown in FIG. It is arranged parallel to the axis. Further, the rubbing direction of the first alignment films 18 and 28 is parallel to the transmission axis of the polarizing plate 24. The rubbing direction of the first alignment films 18 and 28 is not limited to the X-axis direction, but the main direction of the electric field generated between the pixel electrode 9 and the common electrode 19 (the strip electrode 9c).
Direction perpendicular to the extending direction). In the initial state, the liquid crystal aligned in parallel along the rubbing direction is rotated and aligned toward the main direction side of the electric field by applying a voltage between the pixel electrode 9 and the common electrode 19. Bright and dark display is performed based on the difference between the initial alignment state and the alignment state when a voltage is applied.

In each of the above embodiments, a method called an FFS method is adopted, but the same effect can be obtained by an IPS (In Plane Switching) method in which liquid crystal is operated by an electric field in the direction of the substrate surface. The technical scope of the present invention is not limited to a horizontal electric field drive type liquid crystal device typified by an FFS mode or an IPS mode, but includes a TN mode or VAN mode liquid crystal, and a phase difference is provided on the liquid crystal layer side of one substrate. The present invention can also be applied to a liquid crystal device provided with a layer. That is, even in these liquid crystal devices, it is possible to effectively prevent the optical characteristics of the retardation layer from deviating from the design due to the heating during the formation of the alignment film, and the display quality is excellent and the device can be manufactured with a high yield. A liquid crystal device can be realized.

<Method for manufacturing liquid crystal device>
Next, a manufacturing method of the liquid crystal device of this embodiment will be described with reference to FIG. FIG. 4 (a)
FIG. 4C is a cross-sectional process diagram illustrating a manufacturing process of the counter substrate 20 in the liquid crystal device 100.

First, as shown in FIG. 4A, a substrate body 20 which is a transparent substrate made of glass, quartz or the like.
If A is prepared, C is printed on one side (the upper surface in the drawing) of the substrate body 20A using a known printing method or the like.
The F layer 22 is formed. Next, as shown in FIG. 4B, a retardation layer 23 is partially formed on the CF layer 22.

  The retardation layer 23 can be formed by the following method, for example.

First, an alignment film forming material is applied and baked on the CF layer 22 by a spin coating method or a flexographic printing method, and then a rubbing process is performed. Next, a polymer liquid crystal solution is applied onto the alignment film by a spin coating method (for example, at a rotation speed of 700 rpm for 30 seconds). The polymer liquid crystal used here is, for example, an 8% solution of PLC-7023 (trade name, manufactured by Asahi Denka Kogyo Co., Ltd.), and the solvent is a mixed solution of cyclohexanone and methyl ethyl ketone. Next, pre-baking of the applied polymer liquid crystal solution is performed at 80 ° C. for 1 minute, and after heating at 180 ° C. for 30 minutes, which is equal to or higher than the isotropic transition temperature (phase transition temperature) of the polymer liquid crystal layer obtained by baking. The polymer liquid crystal is aligned by gradually cooling. Here, the phase transition temperature is a temperature that changes by causing a phase difference. Next, a resist is patterned on the formed polymer liquid crystal layer on a planar region corresponding to the reflective display region R, and the polymer liquid crystal layer is etched using the resist as a mask. This etching process includes dry etching and N-methyl-
Wet etching using a 2-pyrrolidinone solution can also be applied. Through the above steps, the retardation layer 23 made of a polymer liquid crystal layer can be formed in the region on the CF layer 22 corresponding to the reflective display region R.

In addition, as a formation method of the said phase difference layer 23, after apply | coating the solution of a liquid crystal monomer or a liquid crystal oligomer on a board | substrate, it can apply and expose and polymerize. In this formation method, patterning of the polymer liquid crystal layer is not required because it can be easily patterned by developing after partially exposing the liquid crystal monomer or liquid crystal oligomer coating film. There is an advantage of being.

Next, as shown in FIG. 4C, the second alignment film 28 is formed on the substrate on which the retardation layer 23 is formed.
And an alignment treatment process such as rubbing is performed. As a method of forming the second alignment film 28, a method of forming a polyimide film by dehydrating and ring-closing polyamic acid, or a method of forming a polyimide film by evaporating a solvent of a soluble polyimide solution can be used. . Specifically, after an alignment film forming material containing polyamic acid or soluble polyimide is applied on a substrate using a printing method or a spin coating method, a temporary baking step (heating temperature: 60 ° C. to
A polyimide film is formed through 80 ° C., heating time 30 seconds to 60 seconds) and a main baking step (heating temperature 180 ° C. or less, heating time 1 to 1.5 hours).

In the manufacturing method of the liquid crystal device of the present embodiment, the heating temperature in the polyimide film forming step is set to be lower than the phase transition temperature of the retardation layer 23 (temperature at which the phase difference changes). That is, since the phase transition temperature of the polymer liquid crystal constituting the retardation layer 23 is generally about 150 to 200 ° C., the heating temperature when forming the second alignment film 28 according to the constituent material of the retardation layer 23. Is preferably 180 ° C. or lower. By adopting such a forming method, it is possible to prevent the orientation of the polymer liquid crystal constituting the retardation layer 23 from being lowered by heating in the polyimide film forming step, and the optical characteristics of the retardation layer 23 are impaired. Can be prevented and good display quality can be obtained.

In the manufacturing method according to the present embodiment, it is preferable to use soluble polyimide as the alignment film forming material used for forming the second alignment film 28. Since soluble polyimide uses a material in which polyamic acid is closed in advance as a raw material, the imidization rate of the polyimide film to be formed is hardly changed by heating, and a desired imidization rate can be easily obtained. This is because the orientation regulating force is also stabilized. Further, it is advantageous in that a material having a lower heating temperature (firing temperature) can be used depending on the selection of the solvent.

If the counter substrate 20 is manufactured by the above steps, T manufactured using a known manufacturing method.
The FT array substrate 10 and the counter substrate 20 are bonded together with a sealing material. Then T
A space surrounded by the FT array substrate 10, the counter substrate 20, and the sealing material is filled with liquid crystal and sealed. Then, polarizing plates 14 are respectively provided on the outer surface side of the substrate body 10A and the outer surface side of the substrate body 20A.
, 24, and a backlight 90 on the outer surface side of the TFT array substrate 10,
The liquid crystal device 100 of the above embodiment can be manufactured.

A known manufacturing process may be applied to the process of bonding the TFT array substrate 10 and the counter substrate 20, the process of encapsulating the liquid crystal, the process of disposing the polarizing plates 14 and 24, the process of manufacturing the backlight 90, and the like. it can. In addition, when the TFT array substrate 10 and the counter substrate 20 are bonded together, liquid crystal is arranged in advance on the opposing surfaces of both substrates, and the liquid crystal is sealed using a frame-shaped sealing material that does not have a sealing port. A process may be applied.

As described above, according to the method for manufacturing the liquid crystal device of the present embodiment, in the step of forming the second alignment film 28 after forming the retardation layer 23, the firing temperature of the alignment film forming material is set to the retardation layer 23.
Since the temperature is lower than the phase transition temperature (the temperature at which the phase difference is changed) of the polymer liquid crystal or the like that constitutes the liquid crystal, the optical characteristics of the phase difference layer 23 are prevented from being changed by heating in the process of forming the second alignment film 28 Thus, a liquid crystal device excellent in display quality can be manufactured.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a cross-sectional configuration diagram for explaining the liquid crystal device according to the present embodiment, and corresponds to FIG. 3 in the first embodiment. The liquid crystal device 200 of this embodiment is an FFS transflective liquid crystal device having the same basic configuration as that of the first embodiment. In FIG. 5, the same components as those in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the liquid crystal device 200 of the present embodiment, as shown in FIG. 5, a liquid crystal layer thickness adjustment layer 26 is selectively formed corresponding to the reflective display region R, and a phase difference is formed on the liquid crystal layer thickness adjustment layer 26. It is characterized in that the layer 23 is laminated. The liquid crystal layer thickness adjusting layer 26 is a transparent resin film made of an acrylic resin or the like, and protrudes toward the liquid crystal layer 50 together with the retardation layer 23 formed on the surface thereof. It functions as a thickness smaller than the liquid crystal layer thickness in the transmissive display region T.

In the previous first embodiment, the retardation layer 23 also serves as a liquid crystal layer thickness adjusting layer for realizing a multi-gap structure. However, the retardation layer 23 imparts to the light transmitted through itself. Therefore, if the retardation layer 23 is formed so as to obtain a desired retardation, the film thickness as the liquid crystal layer thickness adjusting layer may be insufficient. Therefore, in this embodiment,
By providing the liquid crystal layer thickness adjusting layer 26 between the retardation layer 23 and the CF layer 22, the reflective display region R
The liquid crystal layer thickness can be adjusted.

As shown in FIG. 5, the liquid crystal layer thickness adjusting layer 26 is preferably formed closer to the substrate body 20 </ b> A than the retardation layer 23. Therefore, it may be formed between the CF layer 22 and the substrate body 20A. As described above, the liquid crystal layer thickness adjusting layer 26 is formed of an acrylic resin or the like, and is typically formed by applying a liquid resin material and then heating and curing the coating film. This is because when the layer thickness adjusting layer 26 is formed on the retardation layer 23, the retardation layer 23 is heated.

When the liquid crystal layer thickness adjusting layer 26 is formed of a photocurable resin material, the retardation layer 23 is not heated more than necessary in the liquid crystal layer thickness adjusting layer 26 forming step. It is also possible to form the liquid crystal layer thickness adjusting layer 26 on the layer 23. In this case, the liquid crystal layer thickness adjusting layer 26
Functions as a protective layer for the retardation layer 23 made of a polymer liquid crystal or the like, so that the retardation layer 23 can be prevented from being altered. In addition, after a polymer liquid crystal layer for forming the retardation layer 23 is formed on the CF layer 22, a liquid crystal layer thickness adjusting layer 26 made of a photocurable resin material is patterned on the polymer liquid crystal layer. The liquid crystal layer thickness adjusting layer 26 can be used as a mask for patterning the polymer liquid crystal layer.

(Electronics)
FIG. 6 is a perspective view showing an example of an electronic apparatus according to the present invention. Mobile phone 130 shown in FIG.
0 includes the liquid crystal device of the present invention as a small-sized display unit 1301 and a plurality of operation buttons 13.
02, an earpiece 1303, and a mouthpiece 1304. Thus, a mobile phone 1300 provided with a display unit that is configured by the liquid crystal device of the present invention and has excellent display quality can be provided.

The liquid crystal display device of each of the above embodiments is not limited to the above mobile phone, but an electronic book, personal computer, digital still camera, liquid crystal television, viewfinder type or monitor direct view type video tape recorder, car navigation device, pager, electronic It can be suitably used as an image display means for devices such as notebooks, calculators, word processors, workstations, videophones, POS terminals, touch panels, etc., and any electronic device can display with high contrast and wide viewing angle. It has become.

FIG. 3 is an equivalent circuit diagram of the liquid crystal device according to the first embodiment. FIG. 3 is a plan configuration diagram of one sub-pixel. FIG. 3 is a cross-sectional configuration diagram taken along line A-A ′ of FIG. 2. Sectional process drawing which shows the manufacturing method of the liquid crystal device which concerns on 1st Embodiment. The cross-sectional block diagram of the liquid crystal device which concerns on 2nd Embodiment. FIG. 11 is a perspective configuration diagram illustrating an example of an electronic device.

Explanation of symbols

100, 200 Liquid crystal device, 10 TFT array substrate (first substrate), 20 Counter substrate (
(Second substrate), 30 TFT (switching element), 9 pixel electrode (first electrode), 19 common electrode (second electrode), 22 CF layer, 23 retardation layer, 26 liquid crystal layer thickness adjusting layer, 29 reflective layer, 39 resin layer, 50 liquid crystal layer, R reflective display area, T transmissive display area

Claims (10)

A first substrate and a second substrate disposed opposite to each other with a liquid crystal layer interposed therebetween;
A first alignment film made of a polyimide material having a first baking temperature is formed on the liquid crystal layer side of the first substrate,
A retardation layer is formed on the liquid crystal layer side of the second substrate, and a second alignment film made of a polyimide material having a second baking temperature is formed so as to cover the retardation layer. The first alignment film and the second alignment film are made of different polyimide materials, and the second baking temperature of the second alignment film is lower than the first baking temperature of the first alignment film.
Liquid crystal devices. A first electrode and a second electrode for generating an electric field for driving the liquid crystal layer are formed between the first substrate and the first substrate.
The liquid crystal device according to claim 1 . A reflective display area for performing reflective display and a transmissive display area for performing transmissive display are provided in one sub-pixel area, and the retardation layer is selectively formed in the reflective display area.
The liquid crystal device according to 請 Motomeko 1 or 2. Depending on the thickness of the retardation layer, the thickness of the liquid crystal layer is different between the reflective display region and the transmissive display region.
The liquid crystal device according to 請 Motomeko 3. A liquid crystal layer thickness adjusting layer is formed on the opposite side of the retardation layer from the liquid crystal layer so that the thickness of the liquid crystal layer varies between the reflective display region and the transmissive display region.
The liquid crystal device according to claim 3 or 4 . A first substrate and a second substrate arranged opposite to each other with a liquid crystal layer interposed therebetween, wherein a first alignment film is formed on the liquid crystal layer side of the first substrate, and a phase difference is formed on the liquid crystal layer side of the second substrate A method for manufacturing a liquid crystal device in which a layer and a second alignment film covering the retardation layer are formed,
A step of forming a retardation layer on the second substrate, a step of applying an alignment film forming material so as to cover the retardation layer, and the applied alignment film forming material of the constituent material of the retardation layer Firing at a temperature lower than the phase transition temperature.
Method of manufacturing a liquid crystal device. Soluble polyimide is used as the alignment film forming material.
Method of manufacturing a liquid crystal device according to 請 Motomeko 6. Prior to the step of forming the retardation layer,
Forming a liquid crystal layer thickness adjusting layer on the second substrate, wherein the thickness of the liquid crystal layer varies within the plane region of the sub-pixel.
Method of manufacturing a liquid crystal device according to 請 Motomeko 6 or 7. Forming a first electrode and a second electrode for generating an electric field for driving the liquid crystal layer between each other on the first substrate; and the first alignment film covering the first electrode and the second electrode And the first substrate on which the first electrode, the second electrode, and the first alignment film are formed, and the second substrate on which the second alignment film is formed and a sealing material. And laminating
Method of manufacturing a liquid crystal device according to any one of 請 Motomeko 6 8. The liquid crystal device according to claim 1 is provided.
Electronic equipment.

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