JP2011002855A - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display having a uniform cell gap.SOLUTION: The liquid crystal display includes a first substrate, a second substrate opposing to the first substrate, a liquid crystal layer interposed between the first substrate and the second substrate, thin film transistors disposed on one surface of the first substrate, an interlayer insulating film comprising an organic film covering the thin film transistors, a reflection layer having a flat surface provided on the second substrate, a color filter disposed on the reflection layer, an overcoat layer covering the color filter, and a spacer holding the first and the second substrates with a uniform gap therebetween.

Description

  The present invention relates to a reflective and transflective liquid crystal display device.

  Active matrix liquid crystal display devices using semiconductor elements are expanded as direct-view display devices such as mobile computers, video cameras, digital cameras, mobile phones, and head-mounted displays, and with optical systems such as lenses such as front and rear projectors. Development as a projection type display device for display purposes is being actively conducted.

  These are classified into a transflective type having both characteristics, in addition to a reflective type display device that reflects external light for display and a transmissive display device that transmits light source light such as a backlight or metal halide.

  Since the reflective display device does not require a backlight, low power consumption can be achieved and it is advantageous for a portable device. Furthermore, when viewing the display under sunlight, it is easier to see than the backlight.

  On the other hand, there are drawbacks in that it cannot be seen and used in dark places, it is difficult to obtain a bright display due to the use of outside light, and it is difficult to increase the contrast.

  For this reason, a transflective display device is considered to be usable even in a dark place. However, in this case as well, the contrast and brightness are inferior to those of the reflective type, and the display is more severe.

  A conventional reflective active matrix liquid crystal display device will be described below. Here, a pixel electrode that has a reflective action and uses this characteristic is referred to as a reflective pixel electrode.

  FIG. 1A shows a conventional example of a single polarizing plate type direct-view active matrix reflective liquid crystal display device in the case where a reflective pixel electrode is a mirror surface.

  A counter substrate including a color filter layer 101, a black matrix (hereinafter referred to as BM) 102, and a common electrode 103, and an element substrate on which an active matrix circuit formed of a semiconductor element 104 such as a thin film transistor (TFT) is formed.

  A liquid crystal 105 is injected between the two substrates, and electro-optic modulation is performed by controlling the electric field of the common electrode 103 and the reflective pixel electrode 106. In this case, in order to align the liquid crystal 105, an alignment film 107 is formed on the electrodes 103 and 106, and an alignment process such as rubbing is performed.

  Thereafter, a polarizing plate 110 that controls the amount of transmitted light in combination with the liquid crystal 105, a phase difference plate 109, a scattering plate 108, and the like are attached to improve the viewing angle and prevent reflection.

  In this specification, the term “plate” is used at the end of the word, such as a polarizing plate, a scattering plate, a retardation plate, and a λ / 4 plate. It is called. However, in this specification, these do not necessarily have to be plate-shaped. Here, the polarizing plate is defined as a polarizing function, the scattering plate is defined as a forward scattering function, and the retardation plate and the λ / 4 plate are defined as generic names of those having a light modulation function.

  In the direct-view liquid crystal display device that employs the specular reflection pixel electrode 106, in order to make white whiter, it is necessary to scatter light within a range that does not affect adjacent pixels within an arbitrary visual field range. Etc.

  A reflection plate for reflecting external light is formed on the element substrate also serving as the pixel electrode 106. Since it is configured on the data line, the gate line, the TFT portion, and the capacitance forming portion, an electrode area ratio of about 90% can be obtained in the pixel region.

  Further, since the reflection plate 107 is provided on the semiconductor element 104, the amount of light applied to the semiconductor layer is reduced directly or indirectly. This has the effect of preventing light leakage that increases off-current. This is particularly effective for projectors that emit light from a powerful light source.

  In the structure as described above, a normally white mode in which black is displayed when a voltage is applied to the liquid crystal 105 and white is displayed when no voltage is applied is often adopted as the reflective liquid crystal display mode. This is because it is easier to obtain brightness than in the normally black mode.

  However, when the normally white mode is adopted in the liquid crystal display device, light leakage occurs at the boundary between adjacent pixels, which causes deterioration of contrast.

  This is because the influence of the lateral electric field parallel to the substrate surface is more pronounced between the electrodes of each pixel than the electric field applied to the counter substrate, and the liquid crystal molecules present in this part This is because a domain of different liquid crystal alignment states is generated by being influenced. The domain boundary is observed as a disclination on or near the data line and gate line. In the display, not only strong light leakage is observed in this part, but also light leakage is observed in the vicinity thereof.

  In general, in liquid crystal display devices, the generation of residual DC electric fields due to the influence of impurity ions in the liquid crystal and alignment film materials is suppressed, and flicker (flickering) phenomenon in the display is prevented. AC driving is adopted between the pixels. For this reason, electric fields with different polarities exist at the boundary between adjacent pixels, and the electric field is twice as large as the electric field applied between the counter substrate and the (reflective) pixel electrode. It has become.

  As a countermeasure, there is a method of physically concealing this light leakage. A means for concealing the light leakage portion is formed by forming a BM 102 that blocks or absorbs light on the counter substrate.

  This method is simple, but has the disadvantages that a process of forming the BM 102 on the counter substrate is necessary and that a BM region must be secured in consideration of a bonding margin between the counter substrate and the element substrate. For this reason, the effective reflective area of the reflective pixel electrode 106 is considerably reduced.

  In the case of a transmissive liquid crystal display device, a BM can be formed on the element substrate, and the bonding accuracy can be improved to the mask alignment accuracy. However, in a reflection type liquid crystal display device observed from the counter substrate side, it is the actual condition that a BM must be formed on the counter substrate.

  Even if the light leakage width due to disclination is suppressed to 2 μm, if the line width of the data line or gate line is 4 μm, the bonding accuracy between the counter substrate and the element substrate needs to be estimated about ± 2 μm including other margins. The BM width is about 6 μm.

  For this reason, the 2 μm pixel region is shielded from light, so that the effective reflection area of the reflection pixel electrode 106 cannot be utilized.

  As another countermeasure, the cell gap (roughly the distance between the counter electrode and the pixel electrode) of the liquid crystal display device is narrowed to about half of the conventional one, and the vertical electric field between the pixel electrode 106 and the counter substrate is strengthened in the periphery of the pixel. Means are conceivable.

  The cell gap is a factor of an optical parameter in a liquid crystal display device for effectively using light, and is thus limited to the liquid crystal operation mode.

  In addition, the refractive index anisotropy constant of the liquid crystal material itself, which is another optical parameter, needs to be about twice that of the conventional one. However, considering the reliability of the material and the like, this correspondence is considerably limited. It becomes a thing.

  As the definition of data lines and gate lines becomes narrower in the future, the ratio of the bonding margin between the counter substrate and the element substrate increases and the area occupied by the BM 102 increases. For this reason, the problem that the effective area | region of the reflective pixel electrode 106 reduces is anticipated.

  FIG. 1B shows an example in which the reflection pixel electrode itself has a scattering effect, not the combination of the specular reflection pixel electrode and the scattering plate in FIG.

  In this configuration, since the scattering effect is realized in the immediate vicinity of the display unit, there is a feature that blurring at the contour portion of the image is less likely to occur than in the case where the scattering is performed through the thickness of the transparent substrate. Further, there is no light absorption by a scattering plate or the like, and the directivity of reflected scattered light can be controlled, which is advantageous for display luminance and contrast.

  However, in the above structure, it is necessary to form an arbitrary unevenness 111 on the reflective pixel electrode on the element substrate or the underlying film, and a processing step for this is added, which may affect the yield of the substrate. It is also a factor that raises costs.

  Furthermore, since the reflection pixel electrode portion has the unevenness 111, the alignment of the liquid crystal is difficult to make uniform, and depending on the shape of the electrode and the film structure on the upper part, there is a possibility that electric charge that causes burn-in may occur.

  In a reflective liquid crystal display device, improving the brightness is essential for improving display quality such as visibility, contrast, and beauty. For this reason, the adoption of a material with high reflectivity is desired.

At present, materials made of aluminum or aluminum alloys are common. This has a reflectance of 83 to 88% in visible light in actual use, and is selected from etching processing and material stability.
In order to obtain a higher reflectance of 10% or more than current materials mainly composed of aluminum, it is conceivable to employ silver, a silver alloy, a dielectric multilayer film, or the like.

  However, these materials are known to be corroded by oxidation and poor in workability. Silver is easily oxidized and corroded. Furthermore, there are problems such as peeling of the film during processing and the influence of the residue on the liquid crystal.

  For this reason, there have been many problems in reliability and productivity, although some measures have been put into practical use, such as adding impurities to silver to prevent this and coating the surface.

  The dielectric multilayer film can obtain a reflectance closer to 100% by stacking films having different refractive indexes. However, the inorganic dielectric film used for this is remarkably inferior in workability.

  Further, when this film is laminated on the pixel electrode, an arbitrary electric field cannot be applied to the liquid crystal due to the influence of the dielectric constant.

  The mirror-reflective pixel electrode and the reflective pixel electrode formed with textures such as irregularities require processing in units of pixels. For this reason, it was difficult to employ the above materials.

  Here, it is an object to solve the above-mentioned problems, there is no need for an opposing BM, and there is no need to consider the simplification of the process and the reduction of the reflective area due to the alignment accuracy with the opposing substrate. It is an object of the present invention to realize a reflective liquid crystal display device that expands the selection range, has a structure that hardly affects the alignment of liquid crystal, and is easy to produce. As a result, it is possible to provide a means for improving the display quality such as reflection luminance and contrast and providing a highly reliable product at a low price.

  The present invention includes a pixel electrode formed of a transparent conductive film in which liquid crystal is sandwiched between a pair of substrates and arranged in a matrix on one of the pair of substrates, and a semiconductor element connected to the pixel electrode, In the liquid crystal display device in which is formed, the one substrate is a substrate having transparency and insulation, and a common electrode made of a reflective layer and a transparent conductive film is provided on the other substrate.

  The above structure is characterized in that in the reflective or transflective liquid crystal display device, the reflective layer is separated from the pixel electrode and the common electrode, and the reflective layer is provided on the counter substrate side. Here, the reflective layer is a layer having a characteristic that the reflectance in air of a medium composed of a single material or a laminated structure is 30% or more.

  Processing of the reflective layer on the counter substrate side is very simple because there is no need for processing according to a design rule such as a pixel electrode. It is also difficult to receive restrictions on the underlying film during processing. For this reason, the selection range of materials can be expanded. Since the pixel electrode uses ITO, which has established conditions, the conventional process rules may be used.

  As a result, aluminum or a material containing aluminum as a main component has been generally used as an electrode material, but optically suppresses silver and silver oxidation that can provide higher reflectivity, scattering characteristics, and directivity. Application of materials, dielectric multilayers, dichroic mirrors, holograms, and the like becomes easy. By using a material having a high reflectance, the reflection luminance is increased and a brighter display can be obtained.

  It is also possible to realize a direct-view or projection-type liquid crystal display device for color display without reflecting a specific visible light wavelength region with a dichroic mirror or the like and using a color filter.

Further, the reflective layer material can be coated by separating the reflective layer and the electrode.
This not only facilitates a means for preventing the reflection film material such as silver from being oxidized, but also makes it possible to prevent the influence of residues and the like during processing that affect the retention ratio of the liquid crystal.

  Even when a reflective film having a texture shape with scattering properties and directivity is formed, it is only necessary to directly process the counter substrate on the reflective film material or the base film, which degrades the yield of the element substrate. There is nothing.

  In addition, since it is not necessary to form a texture on the pixel electrode or the common electrode itself, the most important cell gap in the liquid crystal can be made uniform, and not only uneven color, but also the orientation is uniform over the entire display area. Therefore, it is possible to prevent alignment defects that cause disclination due to structural factors such as irregularities and steps.

  It can be easily applied to a narrow pixel pitch structure due to high definition of pixels without considering a processing space such as a contact hole.

In addition, as a semiconductor element described in the specification, a thin film transistor (TFT)
However, other elements including MIM (Metal-Insulator-Metal), thin film diodes, varistors, insulated gate field effect transistors, bipolar transistors, and the like may be used.

  In another aspect of the invention, a liquid crystal is sandwiched between a pair of substrates, and pixel electrodes arranged in a matrix on one of the pair of substrates and a semiconductor element connected to the pixel electrodes are formed. In the liquid crystal display device, the one substrate is a substrate having transparency and insulation, and the other substrate has a common electrode composed of a reflective layer and a transparent conductive film, and the reflective layer and the common electrode Are electrically connected.

  By connecting the reflective layer and the common electrode to have the same electric potential, generation of residual DC component due to electrostatic floating charges or impurity ions in a substance between the reflective layer and the common electrode is prevented.

  In another aspect of the invention, a liquid crystal is sandwiched between a pair of substrates, and pixel electrodes arranged in a matrix on one of the pair of substrates and a semiconductor element connected to the pixel electrodes are formed. In the liquid crystal display device, the one substrate is a substrate having transparency and insulation, and has a λ / 4 plate on the back surface of the substrate surface on which the switching element is formed, and is reflected on the other substrate. It has the common electrode which consists of a layer and a transparent conductive film, It is characterized by the above-mentioned.

  The above-described configuration is characterized in that in the reflective or transflective liquid crystal display device, the display observation surface is the back surface of the element substrate, and the λ / 4 plate is disposed on the observation surface of the substrate.

  2A and 2B show the polarization state of output light when linearly polarized light is incident on the λ / 4 plate.

  First, the case of transmission will be described with reference to the optical system in FIG. Here, it is assumed that the incident light 201 is transmitted in the order of the first polarizing plate 202, the first λ / 4 plate 203, the second λ / 4 plate 204, and the second polarizing plate 205. In this optical system, the angle formed by the transmission axis of the first polarizing plate 202 and the slow axis of the first λ / 4 plate 203 is 45 °, and the first λ / 4 plate 203 and the second λ / 4 plate 204 has the same slow axis direction, and the first polarizing plate 202 and the second polarizing plate 205 have the same transmission axis direction.

Incident light 201 passes through the first polarizing plate 202 and is output as linearly polarized light 206 parallel to the transmission axis of the polarizing plate 202. The λ / 4 plate 203 is an optical medium having a different uniaxiality in refractive index between the X axis and the Y axis. When the linearly polarized light 206 enters the optical medium, it is separated into an ordinary light component and an abnormal light component. The light has a phase difference. A λ / 4 plate is such that the phase difference is λ / 4 at the distance (film thickness) that light travels in the optical medium. As a result, the output light from this medium becomes elliptically polarized light.
In particular, circularly polarized light 207 is obtained when linearly polarized light 206 is incident at an angle of 45 ° with the axis of the first λ / 4 plate 203 as shown in this optical system.

  Further, when the circularly polarized light 207 passes through the second λ / 4 plate 204, a phase difference between the ordinary light component and the extraordinary light component is further added by λ / 4 in the optical medium. As a result, the circularly polarized light 207 becomes the linearly polarized light 208, and the linearly polarized light 208 at this time has a 90 ° direction different from that of the linearly polarized light 206 immediately after passing through the polarizing plate 202. That is, the light passing through the first λ / 4 plate 203 and the second λ / 4 plate 204 is equivalent to the light passing through the λ / 2 plate. Since the polarization axis of the linearly polarized light 208 is perpendicular to the transmission axis of the second polarizing plate 205, the linearly polarized light 208 is absorbed by the second polarizing plate. This indicates that the observer recognizes it as black.

  Next, the case of reflection will be described using the optical system of FIG. Here, it is assumed that the incident light 209 is transmitted in the order of the polarizing plate 210 and the λ / 4 plate 211, reflected by the reflection medium 212, and then transmitted in the order of the λ / 4 plate 211 and the polarizing plate 210. In this optical system, it is assumed that the angle formed by the transmission axis of the polarizing plate 210 and the slow axis of the λ / 4 plate 211 is 45 °.

  The incident light 209 passes through the polarizing plate 210, and linearly polarized light 213 parallel to the transmission axis of the polarizing plate is output. This further passes through the λ / 4 plate 211, and the circularly polarized light 214 is output. Is the same as

  The circularly polarized light 214 is reflected by the reflection medium 212 and becomes reflected light 215. The polarization state 216 of the reflected light 215 is the same as that of the circularly polarized light 214. This light 216 is now converted into linearly polarized light 217 by the λ / 4 plate 211. Since the polarization axis of the linearly polarized light 217 is perpendicular to the transmission axis of the polarizing plate 210, the linearly polarized light 217 is absorbed by the polarizing plate. Is done. This indicates that the observer recognizes it as black.

  Here, it is utilized that light does not change its property even if it is transmitted through an optically isotropic medium or reflected at a predetermined angle. Here, the predetermined angle is an angle formed with the normal direction of the reflecting surface of the reflecting layer made of aluminum and is about 12 ° or less.

  When the light is reflected at an angle larger than this, the incident light is separated at a predetermined ratio into two components of the S wave component and the P wave component, which causes a decrease in contrast.

  Definitions of P wave and S wave are shown in FIGS. Here, as shown in FIG. 3A, the polarized light having the incident light displacement vector in the incident plane is P wave, and as shown in FIG. 3B, the polarized light perpendicular to the incident plane is S wave.

  The limitation on the reflection surface and the incident light becomes severe in the projection type liquid crystal display device using a particularly strong incident light source. Usually, the incident angle of light (angle formed with the normal line of the reflecting surface) is usually several degrees or less, preferably 2 degrees or less, so that the above problem does not occur.

  However, the reflective liquid crystal display device uses a wide range of light as incident light. For this reason, it cannot be used within the above restrictions. For this purpose, an experimental substrate was prepared in which a λ / 4 plate was experimentally disposed on the reflector, and a polarizing plate having this axis aligned with the polarization axis at 45 ° was provided. As a result of observation by changing the angle of the incident light, it was confirmed that a black level with no problem in normal use environment was obtained.

  That is, the limitation on the reflection surface and the incident light does not become a significant problem when used in a reflection type liquid crystal display device used with external light or fluorescent light incident light.

  From the above, when a λ / 4 plate and a polarizing plate are arranged on the back surface of the element substrate, the reflected light from the materials used for the semiconductor layer, data line, gate line, capacitor electrode, etc. is absorbed by this polarizing plate, and the element It is recognized as black by an observer from the back side of the substrate.

  The present invention takes advantage of the above-described features and utilizes them as BM.

  The disclination that appears due to the difference in the alignment state of the liquid crystal can be controlled to exist only on the bus line by the pretilt angle, pixel shape, structure, and cell gap. It is possible to hide the light leakage due to disclination. And here, by using a λ / 4 plate and a polarizing plate, the reflected light of these shielding objects themselves can be absorbed and the function as a BM is achieved.

  Here, a polarizing plate is used, but any material that outputs linearly polarized light with a predetermined axial direction component and absorbs or reflects other components with respect to incident light of a random component can be used. Either or both of them may be used.

  Furthermore, since it is not necessary to form the BM on the counter substrate, the bonding margin need not be considered as in the conventional case. The effective area of the reflective electrode can also be applied to a high-definition liquid crystal display device. This is particularly effective in a high-definition liquid crystal display device having a pixel pitch of several tens of μm or less.

  In another aspect of the invention, a liquid crystal is sandwiched between a pair of substrates, and pixel electrodes arranged in a matrix on one of the pair of substrates and a semiconductor element connected to the pixel electrodes are formed. In the liquid crystal display device, the one substrate is a substrate having transparency and insulation, and the other substrate has a common electrode composed of a reflective layer, a color filter layer, and a transparent conductive film, and the reflective layer A color filter layer is disposed between the common electrode and the common electrode.

  As the above configuration, a color filter layer is provided on the reflective layer, and a common electrode is provided thereon to realize color display.

  Here, the material of the color filter may be a material in which an organic resin mainly composed of acrylic or polyimide is filled with a pigment, or may be a material that transmits only a visible light wavelength component in a specific band using an inorganic material.

  In addition, the color filter layer is made of an organic resin film mainly composed of acrylic or polyimide, an inorganic material made of silicon oxide, silicon nitride, etc. on the upper layer made of a color filter material, and is planarized or simultaneously protected and separated. You may form the overcoat layer aiming at.

The liquid crystal display device described in this specification has the following three advantages.
First, since it is not necessary to form a BM on the counter substrate, it is not necessary to consider a bonding margin, so a high aperture ratio can be expected. In addition, the effective area of the reflective electrode can be applied to a high-definition liquid crystal display device. This indicates that it is advantageous not only for a direct-view type reflective liquid crystal display device but also for a small reflective liquid crystal display device used particularly for a projection type liquid crystal display device.

Second, since the reflective electrode is manufactured on the counter substrate side, processing is facilitated, and further, the selection range of the material and configuration of the reflective layer is expected to be widened (silver electrode, dielectric multilayer film, hologram). Thereby, a high reflectance can be obtained as compared with the conventional reflective electrode mainly composed of aluminum. In addition, since the reflective layer and the counter electrode on the counter substrate are separated, the material of the reflective layer can be overcoated, and can be applied to a material (silver electrode or the like) whose reflectivity is deteriorated by oxidation.

Third, when the reflecting electrode itself has a structure having a scattering effect, since it is fabricated on the counter substrate side, this processing is not required for the element substrate, and the yield of the element substrate is not reduced by this process. For this reason, an increase in cost can be suppressed. In addition, when the organic layer is formed on the reflective layer or other upper layers, the common electrode on the counter substrate side and the pixel electrode on the element substrate side both have a flat structure, and the cell gap can be made uniform. . For this reason, the alignment of the liquid crystal is uniform and easy.

It is sectional drawing which shows the reflection type liquid crystal display device used in a prior art. It is a figure which shows a mode that incident light passes a polarizing plate and a (lambda) / 4 board, and a figure which shows the polarization state in each point. It is a figure explaining P wave and S wave. 3 is a cross-sectional view showing a structure of an element substrate used in Example 1 or Example 2. FIG. 1 is a cross-sectional view illustrating a structure of a liquid crystal display device used in Example 1. FIG. 5 is a plan view showing the arrangement of wirings and electrodes of an element substrate used in Example 1 or Example 2. FIG. In Example 1 to Example 4, it is the top view which showed arrangement | positioning of the drive circuit and connection wiring of a liquid crystal display device. In Example 1 to Example 3, it is sectional drawing which showed the example of the structure which can be used as a counter substrate which is one of the components of a liquid crystal display device. In Example 4, it is sectional drawing which showed the example of the structure which can be used as a counter substrate which is one of the components of a liquid crystal display device. 6 is a cross-sectional view showing a structure of a liquid crystal display device used in Example 2. FIG. In Example 2 and Example 3, it is the schematic diagram shown about the influence which the light receives when incident light is introduce | transduced into a liquid crystal display device. In Example 2 and Example 3, it is the schematic diagram shown about the influence which the light receives when incident light is introduce | transduced into a liquid crystal display device. 6 is a cross-sectional view showing a structure of an element substrate used in Example 3 or Example 4. FIG. 6 is a cross-sectional view illustrating a structure of a liquid crystal display device used in Example 3. FIG. 6 is a cross-sectional view illustrating a structure of a liquid crystal display device used in Example 3. FIG. 6 is a plan view showing the arrangement of wirings and electrodes of an element substrate used in Example 3. FIG. 6 is a cross-sectional view showing a structure of a liquid crystal display device used in Example 4. FIG. It is the schematic diagram shown about the structure of the optical system of the liquid crystal display device used in Example 4, and the behavior of the light used for it. It is the figure which showed the whole projection type liquid crystal display device. It is sectional drawing showing the outline | summary of the invention in this specification.

  Examples of the present invention will be described. This embodiment is an example of a direct-view type reflective or transflective liquid crystal display device, which is designed to reduce the number of masks used in the element substrate manufacturing process compared to the conventional structure, thereby reducing process time and cost. State. The details of the element substrate, which is one of the constituent elements of the liquid crystal display device, may be in accordance with the method described in Japanese Patent Application No. 11-191093. First, the structure of the element substrate will be briefly described with reference to FIGS. 4 (a) to 4 (b) and FIG.

 A silicon nitride oxide film 402 was formed over the substrate 401 to serve as a base film for the purpose of preventing impurity diffusion from the substrate 401. A thin film transistor (TFT) 403 is formed at a desired position thereon. The TFT 403 exists in the pixel region and the drive circuit region in the periphery thereof, and includes an active layer 404 made of crystalline silicon, a gate wiring 409 made of a conductive material, and a gate insulating film 408 that insulates the gate wiring 409 from the active layer 404. .

 Further, an n-type or P-type impurity element is added to a desired active layer region at a desired concentration by using an ion doping method in the active layer 404 of the TFT 403. As a result, an LDD region 405, a source region 406, drain regions 407 and 415, and a P-channel TFT (not shown) are formed.

 Among these, the data wiring 412 and the pixel electrode 413 are connected to the source region 406 and the drain region part 407 through the contact holes, respectively. Further, a storage capacitor is formed between the other region 415 of the drain region and the capacitor wiring 414 using the gate insulating film 408 as a dielectric film.

 A protective insulating film 410 made of an inorganic material and an interlayer insulating film 411 made of an organic film are formed on the TFT 403.

 On the interlayer insulating film 411, there are a data wiring 412 made of titanium (Ti) or aluminum (Al) alloy, and a pixel electrode 413 made of indium oxide / tin oxide (ITO). Note that the data wiring 412 and the pixel electrode 413 are arranged at positions that are not electrically connected to each other.

 This configuration optimizes the structure of TFTs and wirings so that an element substrate can be manufactured with a relatively small number of masks. In fact, the element substrate having this configuration can be manufactured with seven masks, and the number of film forming steps, patterning steps, etching steps, resist stripping steps, cleaning steps, drying steps, and the like that accompany these steps are reduced. As a result, it is possible to expect effects such as improvement in yield, reduction in process time, and cost reduction.

 Next, a process for manufacturing the counter substrate 502 will be described with reference to FIGS. This substrate is paired with the above-described element substrate 501 to form a liquid crystal display device.

  In FIG. 5, an alkali-free glass as shown for the substrate 401 described in the element substrate manufacturing process is used for the substrate 503.

A reflective layer 504 is formed over the substrate 503 by a vacuum evaporation method. The reflective layer 504 was formed by laminating 1000 銀 of silver as a main reflective material and 2500 を of SiO ₂ that protects silver.

Here, at the time of vapor deposition of silver, a shadow mask was used to form a film in an area corresponding to the display portion so that the alignment marker or the like was not hidden. After the silver film was formed, SiO ₂ was formed over the entire area of the substrate to form the reflective layer 504.

 After forming the reflective layer, the color filter 505 is applied by spin coating. Thereafter, pre-curing is performed at 80 ° C. for 5 minutes on a hot plate. Then, exposure is performed using a photomask according to a photolithography method. The substrate after this processing is developed by immersing it in a developing solution and swinging it. The developer is a 0.2% aqueous solution of tetramethylammonium hydroxide. After soaking in developer for about 1 minute, wash in running water.

 Note that since the color filter 505 contains a pigment, the pigment may not be removed cleanly only with running water. Therefore, washing is performed by spraying water on high-pressure compressed air.

 When it is confirmed that the pattern of the color filter 505 is formed cleanly, main baking is performed at 250 ° C. for 1 hour in a clean oven. The above process is performed for three color filters of red, blue, and green. Further, the color filter 505 may be formed in any order from any color and finished in any color.

 After the three color filters are formed, an overcoat material 506 is applied from above. In this example, an acrylic overcoat material was used. It is applied to the substrate by spin coating and temporarily cured at 80 ° C. for 3 minutes on a hot plate. Then, main baking is performed at 220 ° C. for 1 hour in a clean oven.

Next, a common electrode 507 made of a transparent conductive film is formed on the substrate. The common electrode 507 was formed with 1000 mm of ITO by sputtering.
After film formation, baking was performed at 250 ° C. for 1 hour in a clean oven to improve the transmittance.

 In this embodiment, a layer formed of the color filter 505 and the overcoat 506 is a color filter layer.

Next, a process for manufacturing an active matrix liquid crystal panel from the element substrate 501 and the counter substrate 502 will be described with reference to FIGS.

 First, an alignment film 508 is formed on the element substrate 501 and the counter substrate 502. Usually, a polyimide resin or a polyamic acid resin is used for the alignment film of the liquid crystal display element. In this example, an alignment film SE7792 made by Nissan Chemical Industries was used. An offset printing method was used for forming the alignment film. After the alignment film 508 was formed, provisional curing was quickly performed at 80 ° C. for 90 seconds, and then main baking was performed at 200 ° C. for 90 minutes in a clean oven. The thickness of the alignment film 508 is about 500 mm after the main baking.

  The two substrates 501 and 502 that have undergone such a process are subjected to a rubbing process so that the liquid crystal molecules are aligned with a certain pretilt angle. The rubbing angle was set so as to form a twist of 55 degrees when a liquid crystal material 510 described later was introduced into the panel. The twist angle is not limited to 55 degrees, and may be set to about 50 to 60 degrees to improve contrast.

  After removing dust generated by rubbing and hair loss of the rubbing cloth by cleaning, a sealant (not shown) is applied to the counter substrate 500. The sealing material is temporarily cured in a clean oven at 90 ° C. for 30 minutes.

  After the temporary curing, spherical spacers 509 are further sprayed. The spacer 509 used in this example is a plastic sphere having a diameter of 4 μm.

  Then, the element substrate 501 on which the pixel portion and the driver circuit are formed and the counter substrate 502 are bonded together with high accuracy. A cylindrical filler (not shown) having a diameter of 4.2 μm is mixed in the sealing material, and the two substrates 501 have a high positional accuracy with a uniform distance between the filler and the spacer 509. Can be pasted together.

  In order to achieve accurate gap control, a pressure of 0.3 to 0.8 kgf / cm2 is applied to the entire surface of the substrate uniformly in a direction perpendicular to the surfaces of the bonded substrates, and at the same time in a clean oven Baked at 160 ° C. for 120 minutes.

  Then, after waiting for the substrate to cool, the bonded substrates were cut to a desired panel size to give a panel shape.

Thereafter, a liquid crystal material 510 was injected into the panel. A liquid crystal prepared by mixing a chiral material S-811 in a material having a refractive index anisotropy Δn of 0.124 and having a helical pitch length of 60 to 80 μm was used. When it is confirmed that the entire inside of the panel is filled with the liquid crystal 510, the panel is completely sealed with a sealant (not shown).
Table 1 shows the configuration specifications of the liquid crystal display device manufactured here.

  FIG. 7 is a top view of the element substrate 700, and is a top view showing the positional relationship between the pixel portion 701, the drive circuit portions 702, 703, and 704 and the sealant 711. FIG. Around the pixel portion 701, a scanning signal driving circuit 702 and an image signal driving circuit 703 are provided as driving circuits.

  Further, a signal processing circuit 704 such as a CPU or a memory may be added. These drive circuits provided in the periphery of the pixel portion are configured based on CMOS circuits. These drive circuits are connected to an external input / output terminal group 706 by a connection wiring group 705. In the pixel portion 701, a gate wiring group 707 extending from the scanning signal driving circuit 702 and a data wiring group 708 extending from the image signal driving circuit 703 intersect to form a pixel, and each pixel has a pixel TFT 709. And a storage capacitor 710 are provided.

  The sealant 711 is formed outside the pixel portion 701 and the scanning signal control circuit 702, the image signal control circuit 703, and other signal processing circuits 704 on the substrate 700 and inside the external input / output terminal 706.

  On the outside of the panel, a flexible printed circuit (FPC) 712 is connected to an external input terminal 706 and used to input an image signal or the like. The connection wiring 705 is connected to each drive circuit.

  The external input / output terminal 706 is formed of a conductive metal film with the same structure as the data wiring 708 or the drain wiring 713. The FPC 712 has a structure in which copper wiring is formed on an organic resin film such as polyimide, and is connected to the external input / output terminal 706 with an anisotropic conductive adhesive.

  The anisotropic conductive adhesive is composed of an adhesive and particles having a conductive surface with a diameter of several tens to several hundreds of μm mixed therein and plated with gold or the like. Electrical contact is formed at this portion by contacting the copper wiring.

  In order to increase the adhesive strength with the substrate 700, the FPC 712 protrudes and adheres to the outside of the external input / output terminal 706, and a resin layer is provided at the end portion to increase the mechanical strength in this portion.

  Next, an arrangement method of optical films having a polarization function and a viewing angle improvement function formed on the display observation surface of the panel, that is, the back surface of the element formation surface of the element substrate will be described with reference to FIG.

  First, the front scattering plate 511 is attached to the display surface side of the panel. When the forward scattering plate 511 having a haze value of 50 to 75% was used, good optical characteristics were obtained.

  The polarizing plate 512 is of a high transmission and high polarization type in order to increase the reflectance at the white level. The material used in this example has a single transmittance of 44% and a degree of polarization of 99.95%.

  Further, depending on the display state of the liquid crystal display device, a process having a role of suppressing reflection of external light in the polarizing plate 512, for example, an anti-reflector process or an anti-glare process may be performed on the polarizing plate 512.

  Through the above process, a reflective liquid crystal display device can be manufactured.

 In this embodiment, as shown in FIG. 8A, the surface of the reflective layer of the counter substrate is made flat to form a so-called specular reflective layer 801, on which a color filter 802 and an overcoat 803 are formed. Although the structure having the common electrode 804 is described, the texture shape 805 having scattering and directivity on the surface of the reflective layer is not limited to this method, as shown in FIG. 8B. You may make it the structure which has. In this case, a front scattering plate becomes unnecessary among the optical films arranged on the display surface side of the panel.

 Alternatively, as shown in FIG. 8C, a diffraction grating structure is basically formed on a conductive metal film 806 made of silver, a silver alloy, aluminum, an aluminum alloy, a dielectric multilayer film, or a combination thereof. A hologram 807 may be formed so that light having a specific wavelength is selectively reflected by the hologram structure.

 Alternatively, instead of the reflective layer 801 formed on the substrate 800, a layer having both reflection characteristics and transmission characteristics, for example, a dielectric multilayer film 808 having a half mirror or a semi-transmission characteristic, is formed. It can also be applied to so-called transflective liquid crystal display devices that can be used for any of the above.

 An embodiment having a liquid crystal specification capable of securing a higher contrast will be described below.

  Production of the element substrate and the counter substrate is in accordance with Example 1.

In FIG. 10, a process for manufacturing an active matrix liquid crystal panel from an element substrate 1001 and a counter substrate 1002 is described.

 First, an alignment film 1003 is formed over the element substrate 1001 and the counter substrate 1002. Usually, a polyimide resin or a polyamic acid resin is used for the alignment film of the liquid crystal display element. In this example, an alignment film SE7792 made by Nissan Chemical Industries was used. An offset printing method was used for forming the alignment film. After the alignment film 1003 was formed, provisional curing was immediately performed at 80 ° C. for 90 seconds, and then main baking was performed at 200 ° C. for 90 minutes in a clean oven. The film thickness of the alignment film 1003 is about 500 mm after the main baking.

  A rubbing process is performed on both the substrates 1001 and 1002 after such a process so that liquid crystal molecules are aligned with a certain pretilt angle. The rubbing angle was set so as to form a twist of 90 degrees when a liquid crystal material 1005 described later was introduced into the panel. The twist angle is not limited to 90 degrees, and may be set to about 75 to 90 degrees to improve the reflectance at the white level.

  After removing dust generated by rubbing and hair loss of the rubbing cloth by cleaning, a sealant (not shown) is applied to the counter substrate 1002. The sealing material is temporarily cured in a clean oven at 90 ° C. for 30 minutes.

  After the temporary curing, spherical spacers 1004 are further sprayed. The spacer 1004 used in this embodiment is a plastic sphere having a diameter of 2.5 μm.

  Then, the element substrate 1001 over which the pixel portion and the driver circuit are formed and the counter substrate 1002 are bonded together with high accuracy. A cylindrical filler (not shown) having a diameter of 2.7 μm is mixed in the sealing material, and the two substrates 1001 and 1002 are positioned with high accuracy by the filler and the spacer 1004 at a uniform interval. Can be pasted together.

  In order to achieve accurate gap control, a pressure of 0.3 to 0.8 kgf / cm2 is applied to the entire surface of the substrate uniformly in a direction perpendicular to the surfaces of the bonded substrates, and at the same time in a clean oven Baked at 160 ° C. for 120 minutes.

  Then, after waiting for the substrate to cool, the bonded substrates were cut to a desired panel size to give a panel shape.

  Thereafter, a liquid crystal material 1005 was injected into the panel. As the liquid crystal material, ZLI4792 manufactured by Merck & Co., Ltd. was mixed with Chiral's chiral material S-811 and the helical pitch length was adjusted to 60 to 80 [mu] m. When it is confirmed that the entire panel is filled with the liquid crystal 1005, it is completely sealed with a sealant (not shown).

  Table 2 shows the configuration specifications of the liquid crystal display device manufactured here.

  Next, a method for arranging optical films having a polarization function and a viewing angle improvement function formed on the display observation surface of the panel, that is, the back surface of the element formation surface of the element substrate will be described with reference to FIG.

  First, as shown in FIG. 10, a front scattering plate 1006 is attached to the display surface side of the panel. If the forward scattering plate 1006 has a haze value of 50 to 75%, good optical characteristics were obtained.

A polarizing plate 1008 and a λ / 4 plate 1007 are pasted thereon. Here, the optical axes of the polarizing plate 1008 and the λ / 4 plate 1007 are arranged such that the slow axis of the λ / 4 plate 1007 and the polarizing axis of the polarizing plate 1008 form an angle of 45 degrees.
Here, the λ / 4 plate 1007 is a broadband film that can be used at a visible light wavelength.

  The broadband λ / 4 plate 1007 may be made by combining a standard λ / 4 plate and a standard λ / 2 plate made of a polycarbonate-based material, or a commercially available broadband λ / 4 plate may be used. However, in order to realize good black, it is necessary to provide wide bandwidth so that each wavelength has a birefringence phase difference of 4/20 to 6/20 in the wavelength region of 380 to 800 nm. Good.

  The polarizing plate 1008 is of a high transmission and high polarization type in order to increase the reflectance at the white level. The material used in this example has a single transmittance of 44% and a degree of polarization of 99.95%.

  In FIG. 10, the directions of the optical axes of the polarizing plate 1008 and the λ / 4 plate 1007 are also important, which is closely related to the twist angle of the liquid crystal 1005. For example, when the twist angle is set to 90 degrees, the polarization axis of the polarizing plate 1008 may be attached so as to form an angle of 90 degrees with respect to the rubbing direction applied to the element substrate 1002.

  Furthermore, depending on the display state of the liquid crystal display device, a process having a role of suppressing reflection of external light in the polarizing plate 1008, for example, an anti-reflector process or an anti-glare process may be performed on the polarizing plate 1008.

  Through the above process, a reflective liquid crystal display device can be manufactured.

The configuration of the optical film as described above has the following merits. As shown in FIGS. 11A to 11C, external light incident on the liquid crystal display device is converted into circularly polarized light by the polarizing plate 1101 and the λ / 4 plate 1102 and introduced into the panel. Of circularly polarized light, light reflected on the back surface (display surface side) of the element substrate 1103 or a reflective film in the element substrate 1103, that is, light that has returned without passing through the liquid crystal layer, The λ / 4 plate 1102 is reconverted into polarized light perpendicular to the polarization axis of the polarizing plate 1101. For this reason, such light is absorbed by the polarizing plate 1101 and does not enter the observer's eyes.

  On the other hand, as shown in FIGS. 12A to 12C, light that has passed through the liquid crystal layer 1203 and whose polarization state has changed passes through the polarizing plate 1201 in accordance with the change state. You will see it. That is, unnecessary light is absorbed by the polarizing plates 1101 and 1201 and only necessary light is transmitted, leading to an improvement in contrast.

  The reflective film in the element substrate 1103 becomes a BM if viewed differently. This is because, as described above, light reflected by a reflective film or the like in the element substrate 1103 does not enter the eyes of the observer after all.

 Since the light-shielding film also serves as a BM, it is arranged so as to hide the so-called disclination, which is caused by the liquid crystal orientation disorder occurring at the edge of each pixel when the liquid crystal display device is driven. Should do. In order to secure the aperture ratio as much as possible, it is desirable that the ratio of the area of the film exhibiting light shielding properties is as small as possible.

 In Example 1 (FIGS. 4 and 5) or this example (FIG. 10), in the pixel regions of the element substrates 501 and 1001, main films exhibiting light shielding properties are an active layer 404 for forming a thin film transistor, a gate line, and the like. (Gate electrode) 409, data line 412, and capacitor wiring 414.

 Of these, the capacitor wiring 414 will be described first. In this embodiment, the storage capacitor is configured such that the capacitor wiring 414 and the drain region 415 of the TFT are both electrodes of the capacitor, and a part of the gate insulating film 408 is a dielectric film between the electrodes.

The dielectric film of the storage capacitor is made of the same material as the gate insulating film 408, and is made of SiO2 or SiON. When a storage capacitor is formed using SiO2 or SiON as a dielectric film, the relative dielectric constant thereof is about 3.8. Therefore, when the dielectric film thickness is 750 mm, the electric capacity per unit area is 0.75 fF / It is about μm ² . On the other hand, in each pixel, the electric capacity required for the pixels is (0.06 to 0.07 [fF / μm ² ]) × (pixel area [μm ² ]) [fF] or more.

  That is, as in this embodiment, when SiO 2 or SiON is used as a dielectric, the capacitor wiring 414 needs to occupy about 10% of the total area of the opening by the pixel electrode 413. As a result, the aperture ratio of the pixel electrode 413 is increased. It can also be a cause of dropping.

  An improvement measure for achieving a higher aperture ratio is described in Example 3.

  In this embodiment, another example of a direct-view type reflective or transflective liquid crystal display device will be described in which a higher aperture ratio can be achieved than in the first and second embodiments.

 Note that the details of the element substrate, which is one of the components of the liquid crystal display device, may follow the method described in Japanese Patent Application No. 11-053424 (Semiconductor Energy Laboratory).

 First, the structure of the element substrate will be briefly described with reference to FIGS.

 A silicon nitride oxide film 1302 was formed over the substrate 1301 to serve as a base film for preventing impurity diffusion from the substrate 1301. A thin film transistor (TFT) 1303 is formed at a desired position thereon.

 The TFT 1303 exists in the pixel region and the drive circuit region in the periphery thereof, and includes an active layer 1304 made of crystalline silicon, a gate wiring 1309 made of a conductive material, and a gate insulating film 1308 that insulates the gate wiring 1309 from the active layer 1304. .

 Further, an n-type or P-type impurity element is added to a desired active layer region and at a desired concentration in the active layer 1304 of the TFT 1303 by using an ion doping method. As a result, an LDD region 1305, a source region 1306, a drain region 1307, and a P-channel TFT (not shown) are formed. Among these, the data wiring 1312 and the drain wiring 1313 are connected to the source region 1306 and the drain region 1307 through contact holes, respectively.

 Over the TFT 1303, a protective insulating film 1310 made of an inorganic material and a first interlayer insulating film 1311 are formed.

 A second interlayer insulating film 1314 is formed on the data wiring 1312, the drain wiring 1313, and the first interlayer insulating film 1311. On this, a capacitor wiring 1315 made of aluminum is formed in a region to be a pixel matrix circuit. The capacitor wiring 1315 is anodized, and therefore an oxide film 1316 made of aluminum oxide is formed on the surface. The thickness of the oxide film 1316 is about 50 nm.

 A pixel electrode 1317 is formed thereon. The pixel electrode 1317 is made of indium oxide / tin oxide (ITO) and is connected to the drain wiring 1313 through the contact hole. The data wiring 1312, the gate wiring 1309, and the capacitor wiring 1315 partially overlap. In particular, the capacitor wiring 1315 forms a storage capacitor using the oxide film 1316 as a dielectric film.

 The structure and process of the counter substrate 1402 and the process for manufacturing a liquid crystal display device from the element substrate 1401 and the counter substrate 1402 are the same as those described in Example 1 or Example 2. In this manner, a liquid crystal display device as shown in FIG. 14 can be manufactured.

 Further, as shown in FIG. 15, the reflective film may be made into a texture structure 1501 to realize scattering. In this case, the front scattering plate is unnecessary.

 FIG. 20 shows the significance of the liquid crystal display device described in this embodiment using a cross-sectional view.

 External light 2002 introduced from the light source 2001 into the liquid crystal display device 2000 reaches the element substrate 2006 through the polarizing plate 2003, the λ / 4 plate 2004, and the forward scattering plate 2005.

 A part (not shown) of the incident light 2002 is reflected on the surface of the element substrate 2006 (an interface between the forward scattering plate 2005 and the element substrate 2006), and a part 2002a is a surface of a reflective film on the element substrate. Reflected. Since such light 2002a is not modulated at all in its polarization state, it is absorbed here by the action of the return λ / 4 plate 2004 and the polarizing plate 2003 and does not enter the observer's eyes 2010. That is, all the reflective films on the element substrate are BM in other words.

 Most other light 2002b passes through the element substrate, passes through the liquid crystal layer 2007 and the color filter layer 2008, and is reflected by the reflective layer 2009. Thereafter, the light 2002b follows a path opposite to the incident. Of such light 2002b, light that has undergone some modulation in its polarization state by liquid crystal has a polarization component that remains parallel to the transmission axis of the polarizing plate 2001 immediately before exiting the liquid crystal display device 2000 depending on how it is received. Thus, the polarizing component enters the observer's eyes 2010 only after passing through the polarizing plate. On the other hand, light that has not undergone any modulation in its polarization state even after passing through the liquid crystal follows exactly the same fate as the light 2002a and does not enter the observer's eyes 2010.

 In this way, among the light 2002 introduced into the liquid crystal display device 2000, unnecessary light 2002a not related to the display is blocked, while the light 2002b involved in the display is selected by the modulation action of the liquid crystal. In other words, a high contrast display can be obtained by outputting to the outside of the liquid crystal display device.

 As described above, the reason why the aperture ratio is low in the first and second embodiments is that the ratio of the capacity wiring area to the pixel electrode area must be increased.

 Therefore, in this embodiment, as shown in FIGS. 13 to 15, a capacitor electrode 1315 made of aluminum is formed on the second interlayer insulating film 1314, and this surface is anodized to thereby form an insulating film made of aluminum oxide. 1316 is obtained, and the pixel electrode 1317 is directly formed thereon. With such a structure, a storage capacitor is formed in which the capacitor wiring 1315 and the pixel electrode 1317 are both electrodes of the capacitor and the insulating film 1316 formed therebetween is a dielectric film.

 Since the relative permittivity of aluminum oxide is as large as 8 and the film thickness can be reduced to 500 mm, a capacity as large as 4 to 5 times the conventional storage capacity can be formed.

 In other words, if the required storage capacity is the same for the structures of the first and second embodiments and the structure employed in the present embodiment, The area of the capacitor wiring 1315 can be reduced to a fraction or less, which is effective for increasing the aperture ratio.

 Further, the structure of the gate line 1309 and the data line 1312 and the arrangement of the capacitor wiring 1315 may be properly used as follows according to the pixel size of the panel.

 As shown in FIG. 16A, when the pixel size is about 50 μm × 150 μm or larger, the gate line 1601 and the data line 1602 are arranged in regions corresponding to the edge portions of the pixel electrodes 1603, respectively. In addition, by increasing the width of one of the gate line 1601 and the data line 1602 to about 3 to 6 μm, a large amount of light leakage (disclination) due to liquid crystal orientation disorder appearing when the liquid crystal display device is driven. It is preferable to serve as a so-called black matrix that hides the portion.

 The capacitor wiring 1604 is arranged so as to overlap with either the gate line 1601 or the data line 1602, and in each pixel region, the capacitor line 1604 cannot be hidden by thickening the gate line 1601 or the data line 1602. If disclination exists, it can be preferentially placed in that part.

 On the other hand, as shown in FIG. 16B, when the pixel size is smaller than about 50 μm × 150 μm, the gate line 1605 and the data line 1606 are arranged in regions corresponding to the edge portions of the pixel electrodes 1607, respectively. In addition, it is preferable to make the width of both wirings as thin as 2 μm or less to increase the aperture ratio. The capacitor wiring 1608 is arranged so as to overlap with both the gate line 1605 and the data line 1606, and the necessary storage capacitance is used here, and further, the capacitor wiring 1608 is arranged so as to cover the edge of each pixel electrode 1607. (In other words, the disclination is almost hidden only by the capacity wiring 1608).

  In this embodiment, a projection type reflective liquid crystal display device will be described with reference to FIG.

  Note that most of the details of the element substrate, which is one of the components of the liquid crystal display device, conform to the methods described in the first to third embodiments.

  However, the difference from the element substrate structure shown in Examples 1 to 3 is that, as shown in FIG. 17, there is a light shield 1701 made of a metal film so as to overlap the TFT element. .

  The light shield 1701 is provided in order to prevent the light introduced from the light source of the projection device to the liquid crystal display device from being directly or indirectly irradiated on the TFT element 1702. This prevents an increase in off-current due to the light of the TFT 1702, and measures against crosstalk and color unevenness of the display image caused by this.

  Next, a counter substrate 1703 which is another component of the liquid crystal display device will be described. In this embodiment, the reflective layer 1707 is mainly made of an aluminum alloy and a dielectric multilayer film. As the substrate, an alkali-free glass substrate or a quartz substrate is used. Here, an alkali-free glass substrate having the same kind of material as the element substrate 1700 is used. Details will be described with reference to FIG.

 As shown in FIG. 9A, an aluminum alloy 903 and a dielectric multilayer film 904 are formed as a reflective layer 902 on a substrate 901. As the aluminum alloy 903, a material containing 1% titanium in aluminum was used. The dielectric multilayer film 904 was formed by laminating eight layers of materials having a refractive index of 1.4 and 2.1 by a vacuum deposition method (up to four layers are shown in the figure) to increase the reflectance. Naturally, these films were formed by adjusting the film thickness so as to reflect broadband light in the visible light region.

After forming the reflective layer, a common electrode 905 made of a transparent conductive film is formed on the substrate.
The common electrode 905 was formed with 1000 mm of ITO by sputtering. After film formation, baking was performed at 250 ° C. for 1 hour in a clean oven to improve the transmittance.

Although the purpose here is to increase the reflectivity by using a dielectric multilayer film, a single-layer film 906 may be used as shown in FIG. 9B, or the reflection may be performed as shown in FIG. 9C. The film may be a dichroic mirror 908, and the electro-optical device itself may be colored. If this structure is used, the peripheral optical system can be miniaturized.

Next, a manufacturing process of a liquid crystal display device using the element substrate 1700 and the counter substrate 1703 will be described with reference to FIGS.

 Usually, a polyimide resin or a polyamic acid resin is used for the alignment film 1704 of the liquid crystal display element. In this example, an alignment film SE7792 made by Nissan Chemical Industries was used.

  The alignment film was formed using an offset printing method. After the alignment film 1704 was formed, temporary curing was immediately performed at 80 ° C. for 90 seconds, and further, main baking was performed at 200 ° C. for 90 minutes in a clean oven. The thickness of the alignment film 1704 after the main baking is about 502 mm.

  The two substrates 1700 and 1703 that have undergone such a process are subjected to a rubbing process so that the liquid crystal molecules are aligned with a certain pretilt angle. The rubbing angle was set so as to make a twist of 45 degrees when a liquid crystal material 1706 described later was introduced into the panel. Note that the twist angle is not limited to 45 degrees, and may be set so as to obtain desired optical characteristics.

  After removing dust generated by rubbing and hair loss of the rubbing cloth by cleaning, a sealing material (not shown) is applied to the counter substrate 1703. The sealing material is temporarily cured in a clean oven at 90 ° C. for 30 minutes.

  After the temporary curing, further spherical spacers 1705 are dispersed. The spacer 1705 used in this example is a plastic sphere having a diameter of 5.0 μm.

  An element substrate 1700 over which a pixel portion and a driver circuit are formed is attached to a counter substrate 1703. A cylindrical filler (not shown) having a diameter of 5.2 μm is mixed in the sealing material, and the two substrates 1700 and 1703 are positioned with high accuracy by the filler and the spacer 1705 at a uniform interval. Can be pasted together.

  In order to achieve more accurate gap control, a pressure of 0.3 to 0.8 kgf / cm2 is applied uniformly in the direction perpendicular to the surface of the bonded substrates and across the entire substrate, and at the same time a clean oven Baked at 160 ° C. for 120 minutes. Then, after waiting for the substrate to cool, the bonded substrates were cut to a desired panel size to give a panel shape.

  Thereafter, a liquid crystal material 1706 was injected into the panel. As the liquid crystal material, ZLI4792 manufactured by Merck & Co., Ltd. was mixed with Chiral's chiral material S-811 and the helical pitch length was adjusted to 60 to 80 [mu] m.

  When it is confirmed that the entire panel is filled with the liquid crystal 1706, it is completely sealed with a sealant (not shown).

  Table 3 shows the configuration specifications of the liquid crystal display device.

    Hereinafter, the matter of attaching an FPC to the external input / output terminal of the liquid crystal panel so that a necessary signal can be sent from the outside to the liquid crystal panel is the same as that described in the first embodiment.

  An example of an apparatus for projecting a reflective liquid crystal panel will be described with reference to FIG. Light 1809 emitted from the light source 1801 of the projection apparatus is introduced into the optical system. This light is first converted into an S wave component 1810 and a P wave component 1811 by a prism type polarization beam splitter (PBS) 1802. Is broken down into

 The PBS 1802 has a property of reflecting only the S-wave component 1810 of light and transmitting the P-wave component 1811 on the reflecting surface in the prism. Therefore, only the S wave component 1810 of light travels to the dichroic prism 1803.

 The dichroic prism 1803 decomposes the incident light 1810 into red, green, and blue components 1812 to 1814 without changing the polarization state thereof, and the red panel 1804, the green panel 1805, and the blue panel, respectively. Light is supplied to 1806.

 Polarized light 1812 to 1814 incident on the three panels 1804 to 1806 are appropriately modulated in each panel according to the director alignment of the liquid crystal. As a result, the respective lights 1812 to 1814 are emitted to the outside of the panels as S wave components and P wave components in the respective panels 1804 to 1806 and returned to the dichroic prism 1803.

 Red, green and blue lights 1815 to 1817 are recombined by the dichroic prism 1803 and reach the PBS 1802. In the PBS 1802, only the P wave component 1818 of the light is transmitted through the reflecting surface of the prism, and this light is projected onto the screen 1808 through the optical lens 1807. In this way, a color projection display is achieved.

 Such an optical system can be incorporated in the main body of a front projector as shown in FIG. 19A and a rear projector as shown in FIG. In this way, a projection-type reflective liquid crystal display device is completed.

Claims (9)

A first substrate;
A second substrate facing the first substrate;
A liquid crystal layer sandwiched between the first substrate and the second substrate;
A thin film transistor provided on one surface of the first substrate;
An interlayer insulating film made of an organic film covering the thin film transistor;
A pixel electrode provided on the interlayer insulating film and electrically connected to the thin film transistor;
A first alignment film provided on the pixel electrode;
A reflective layer having a flat surface provided on the second substrate;
A color filter provided in the reflective layer;
An overcoat layer covering the color filter;
A common electrode provided in the overcoat layer;
A second alignment film provided on the common electrode;
A spacer in contact with the first and second alignment films and holding the first and second substrates at a uniform interval;
A liquid crystal display device comprising: In claim 1,
Having data wiring provided on the interlayer insulating film;
The data wiring is disposed at a position not electrically connected to the pixel electrode,
The data wiring has titanium or aluminum,
The liquid crystal display device, wherein the pixel electrode is made of ITO. In claim 1 or claim 2,
The liquid crystal display device, wherein the spacer is spherical and made of plastic. In any one of Claim 1 thru | or 3,
The first substrate and the second substrate are bonded together with a sealing material,
The liquid crystal display device, wherein the sealing material includes a filler. In claim 4,
The cell gap between the first and second substrates is equal to the size of the spacer,
The liquid crystal display device, wherein a size of the filler is larger than the cell gap. In claim 4 or claim 5,
The liquid crystal display device, wherein the sealant is disposed outside a pixel portion having the thin film transistor, a scanning signal control circuit, and an image signal control circuit and inside an external input / output terminal. In claim 6,
The liquid crystal display device, wherein the external input / output terminal has the same configuration as the data line. In any one of Claims 1 thru | or 7,
The reflective layer is made of silver or a silver alloy,
A liquid crystal display device, wherein a protective film is provided in contact with the reflective layer made of silver. In any one of Claims 1 thru | or 8,
A front scattering plate is provided on the other surface of the first substrate,
A λ / 4 plate is provided in contact with the front scattering plate,
A polarizing plate is provided in contact with the λ / 4 plate,
An angle formed by the slow axis of the λ / 4 plate and the transmission axis of the polarizing plate is 45 degrees.

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