JP2005241880A - Electrooptical device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deflection of a substrate due to external force without generating air bubbles at the time of low temperature in an electrooptical device with pillar-shaped spacers provided between substrates provided opposite to each other. <P>SOLUTION: The electrooptical device has an opposite substrate 200 and a color filter substrate 300 provided opposite to each other and stuck by a frame-like sealant 110, a liquid crystal layer 165 held between the opposite substrate 200 and the color filter substrate 300 and sectioned into a plurality of pixels 160, and a plurality of pillar-shaped spacers 210 provided by being projected on a surface of the opposite substrate 200 or the color filter substrate 300 and abutted on the other substrate, wherein the pillar-shaped spacers 210 are provided so that summation of cross section of the pillar-shaped spacers 210 per unit area in a cross section in parallel with both substrates becomes larger as approaching from an edge to a center part of the opposite substrate 200 or the color filter substrate 300. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electro-optical device configured by sandwiching an electro-optical material between substrates provided to face each other.

In a liquid crystal display device, a method is known in which columnar spacers are provided by photolithography technology between two substrates constituting a liquid crystal panel, thereby maintaining the size of the gap (cell gap) between the substrates at a desired value. It has been. This columnar spacer has an advantage that the size of the gap can be easily controlled as compared with the conventional method of dispersing spherical spacers between substrates.
Various techniques for controlling the cell gap of a liquid crystal panel using this columnar spacer have been proposed. For example, in the technique described in Patent Document 1, by providing columnar spacers at a higher density than the display area at the peripheral edge of the substrate (non-display area), a cell gap is provided due to the pressure of the pressing device when the substrates are bonded together. We are trying to prevent it from becoming smaller than the period value.
JP-A-9-73093

By the way, the liquid crystal panel is exposed not only to the pressure in the manufacturing process described above but also to various external forces. For example, when a user uses a liquid crystal display device supplied as a product, the display surface of the liquid crystal panel is often inadvertently pushed. Alternatively, there is a device including a touch panel type user interface means using a liquid crystal panel, and in such a device, a load frequently acts on the display surface. In this case, the substrate on the observation side bends to the other substrate side, and the electrodes provided on both the substrates are short-circuited, which causes image quality failure or failure. In order to avoid such a situation, the coping method of increasing the number of columnar spacers or increasing the thickness of the columnar spacers can be considered. However, when this method is adopted, the rigidity in the direction perpendicular to the plate surface of the liquid crystal panel becomes too high, and it becomes impossible to follow the decrease in the volume of the liquid crystal at a low temperature. As a result, bubbles are generated in the liquid crystal layer, resulting in poor image quality. The technique described in Patent Document 1 cannot cope with such a situation.
The present invention has been made under the above-described background. In an electro-optical device in which columnar spacers are provided between substrates provided to face each other, the substrate is bent by an external force without generating bubbles at low temperatures. The purpose is to provide a technology capable of preventing the above.

In order to solve the above-described problems, the present invention provides a first substrate and a second substrate that are provided facing each other and bonded together by a frame-shaped sealing material, and the first substrate and the second substrate. An electro-optic material layer sandwiched and divided into a plurality of pixels, and a plurality of columnar spacers that protrude from the surface of the first substrate or the second substrate and abut against the other substrate, The spacers are provided such that the sum of the cross-sectional areas of the spacers per unit area in a cross section parallel to both substrates increases as the distance from the edge of the first substrate or the second substrate approaches the center. An electro-optical device is provided.
In this electro-optical device, since the first substrate and the second substrate are bonded together by a frame-shaped sealing material, for example, when a load in the direction of pushing the first substrate toward the second substrate is applied, The deflection of the first substrate increases as the acting position approaches the center of the first substrate. According to the present invention, in the columnar spacer, the sum of the cross-sectional areas of the spacer per unit area in a cross section parallel to both the substrates increases as the distance from the edge of the first substrate or the second substrate approaches the central portion. Therefore, the deflection amount of the counter substrate can be prevented from exceeding a certain value regardless of the position where the load is applied. In addition, since the rigidity in the direction perpendicular to the plate surfaces of the first substrate and the second substrate does not become excessively high, it is possible to prevent the generation of bubbles due to the volume reduction of the electro-optic material at low temperatures.

More specifically, each of the spacers has the same cross-sectional area in a cross section intersecting with the longitudinal direction of the spacer, and the spacer per unit area approaches the central portion from the edge of the first substrate or the second substrate. It is provided so that the number may increase. According to this structure, since the cross-sectional area of a spacer is the same, manufacture is easy.
In another preferred embodiment, each of the spacers is provided so that the number of the spacers per unit area is uniform, and the length of the spacer increases as the distance from the edge of the first substrate or the second substrate approaches the center. The cross section of the cross section that intersects the direction is formed to be large. According to this configuration, the number of spacers can be reduced.

  Preferably, the pixel includes a switching element provided in each of the pixels, and the spacer is provided at a position close to the switching element in a gap between the adjacent pixels. The switching element is often formed to protrude slightly from other components on the substrate on which the switching element is provided, and is most susceptible to stress at the time of contact between the first substrate and the second substrate. It is possible to prevent stress from being applied to the switching element.

In the present invention, the second substrate is provided on a surface facing the first substrate, and reflects the incident light from the first substrate side to the first substrate side. A reflection layer that divides each of the pixels into an opening that transmits incident light from the substrate side to the first substrate side; and a thickness of an electro-optic material layer in the reflection portion provided to cover the reflection portion And a step forming layer that makes the electro-optic material layer different in thickness in the opening, and the spacer is preferably provided on the surface of the first substrate. According to this configuration, since the spacer is provided on the surface where the step forming layer is not formed, it is easy to control the film pressure when the photosensitive material is applied. In addition, since the first substrate has fewer components other than the spacers, the manufacturing steps of the first substrate and the second substrate can be averaged.
An electronic apparatus according to the present invention includes any one of the above electro-optical devices.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In the drawings used in the following description, the size ratio, aspect ratio, and the like of each component are drawn appropriately different from actual ones for easy understanding.
FIG. 1 is a diagram illustrating a configuration of an electro-optical device 10 according to the present embodiment. As shown in the figure, the electro-optical device 10 includes a liquid crystal panel 100, a control circuit 600, and a power supply circuit 900. The liquid crystal panel 100 includes a plurality of data lines 150 extending in the column direction (Y direction) and a plurality of scanning lines 140 extending in the row direction (X direction). A pixel 160 is formed at each point where the data line 150 and the scanning line 140 intersect. The pixel 160 includes a TFD (Thin Film Diode) that is a two-terminal switching element and a liquid crystal capacitor connected in series to the TFD. The liquid crystal capacitor includes a scanning line 140 that is a strip-shaped transparent electrode and a pixel that will be described later. A liquid crystal, which is an electro-optical material, is sandwiched between the electrodes.

The scanning line driving circuit 400 selects the scanning lines 140 one by one, and supplies a selection voltage to the selected scanning lines 140 and a non-selection voltage to the other scanning lines 140. The data line driving circuit 500 sends a data signal corresponding to the gradation represented by the gradation data to the pixels 160 for one row corresponding to the scanning line 140 selected by the scanning line driving circuit 400 via the data line 150. Supply.
The control circuit 600 supplies various signals such as a scanning signal and a clock signal for performing vertical scanning and horizontal scanning of the liquid crystal panel 100 to the scanning line driving circuit 400 and the data line driving circuit 500. The control circuit 600 supplies gradation data representing the gradation of the pixel 160 to the data line driving circuit 500 in synchronization with vertical scanning and horizontal scanning. The power supply circuit 900 supplies power to the scanning line driving circuit 400 and the data line driving circuit 500.

  FIG. 2 is a cross-sectional view of the liquid crystal panel 100 taken along line AA in FIG. In FIG. 2, only three pixels are shown among the large number of pixels 160 provided in the liquid crystal panel 100. As shown in the figure, the liquid crystal panel 100 includes a color filter substrate (second substrate) 300 located on the back side, and a counter substrate (first substrate) 200 facing the color filter substrate 300 on the observation side. . The color filter substrate 300 and the counter substrate 200 are bonded to each other with a sealant 110 while maintaining a certain gap. In a space surrounded by the color filter substrate 300 and the counter substrate 200 and the sealing material 110, for example, TN (Twisted Nematic) type liquid crystal is sealed to form a liquid crystal layer 165. In addition, the liquid crystal panel 100 has both functions of a transmissive display that performs display by transmitting incident light from the back side to the observation side and a reflective display that performs display by reflecting incident light from the observation side. A backlight 950 that uniformly irradiates light is provided on the back side of the color filter substrate 300.

  As shown in FIG. 2, the reflective layer 301, the colored layer 302 </ b> R, the colored layer 302 </ b> G, the colored layer 302 </ b> B, the light shielding layer 302 </ b> K, the protective layer 306, and the scanning line 140 are provided on the surface of the color filter substrate 300 that faces the counter substrate 200. A step forming layer 310 and an alignment film 308 are provided. The reflective layer 301 is provided with an opening 301 a for transmitting incident light from the backlight 950. The colored layer 302R, the colored layer 302G, and the colored layer 302B have light transmittance, and are colored red (R), green (G), and blue (B), respectively. That is, the colored layer 302R selectively transmits light having a wavelength corresponding to red. Similarly, the colored layer 302G and the colored layer 302B selectively transmit light having wavelengths corresponding to green and blue, respectively. The light blocking layer 302K is a black matrix made of metal or resin that blocks light from the backlight 950. In the following description, the colored layer 302R, the colored layer 302G, the colored layer 302B, and the light shielding layer 302K are collectively referred to as the color filter 302. In addition, a portion of the reflective layer 301 that is not covered by the light shielding layer 302K and that excludes the opening 301a is referred to as a reflective portion 301b.

The protective layer 306 is a layer for filling the level difference of the color filter 302 to be flattened and protecting the color filter 302. The scanning line 140 is a strip-shaped transparent electrode extending in the row direction (X direction).
The step forming layer 310 is a layer made of a resin material such as acrylic or epoxy, or an organic material such as polyimide, and is provided so as to overlap the reflective portion 301b when viewed from the direction perpendicular to the plate surface of the counter substrate 200. The opening 301a is provided so as not to overlap. That is, only the light incident on the reflection part 301 b from the observation side and reflected by the reflection part 301 b passes through the step forming layer 310. Here, since the incident light from the observation side passes through the liquid crystal layer 165 twice, the length of the path through which it passes is 2 × Dr. On the other hand, incident light from the backlight 950 passes through the liquid crystal layer 165 only once. If the length of this path is Dt, the step forming layer 310 is formed so as to be approximately Dt = 2 × Dr.
The alignment film 308 is rubbed in a certain direction. A polarizing plate 309 is attached to the outer side (back side) of the color filter substrate 300, and the direction of the absorption axis is selected according to the direction of rubbing treatment on the alignment film 308.

On the other hand, on the surface of the counter substrate 200 facing the color filter substrate 300, a TFD 162 and a pixel electrode 161 that is a rectangular transparent electrode are formed adjacent to the data line 150 extending in the column direction (Y direction). In addition, an alignment film 208 that is rubbed in a certain direction is formed. A polarizing plate 209 is provided on the outer side (observation side) of the counter substrate 200, and the direction of the absorption axis is selected according to the direction of rubbing treatment on the alignment film 208.
Meanwhile, a columnar spacer 210 is provided on the surface of the counter substrate 200 facing the color filter substrate 300, which is a component that characterizes the present invention. The length in the longitudinal direction of the columnar spacer 210 is a length required to keep the cell gap between the color filter substrate 300 and the counter substrate 200 at a desired value. Specifically, the liquid crystal layer 165 of the counter substrate 200 is used. And the distance between the surface facing the liquid crystal layer 165 of the alignment film 308 and the surface facing the liquid crystal layer 165. The cross-sectional areas of the cross-sections that intersect the longitudinal direction of each of the columnar spacers 210 are all the same.

  FIG. 3 is a diagram illustrating a surface of the counter substrate 200 that faces the color filter substrate 300. As shown in the drawing, the columnar spacer 210 is a gap between the pixel electrodes 161 and is provided at a position closest to the TFD 162. The reason why the columnar spacer 210 is provided at a position close to the TFD 162 is as follows. As shown in FIG. 2, the TFD 162 is provided so as to slightly protrude toward the liquid crystal layer 165 side from the pixel electrode 161 and the data line 150 adjacent to the TFD 162. Therefore, when the load in the direction of pressing the counter substrate 200 from the observation side of the counter substrate 200 toward the color filter substrate 300 is applied and the alignment film 208 and the alignment film 308 are in contact with each other, the TFD 162 is most susceptible to stress. Therefore, if the columnar spacer 210 is provided at a position close to the TFD 162, the effect of protecting the TFD 162 is maximized.

The columnar spacer 210 is formed on the counter substrate 200 by a photolithography technique. The first reason is the ease of formation. Since there is a step due to the formation of the step forming layer 310 on the color filter 302 side, if a columnar spacer 210 is further formed thereon, the film thickness when a photosensitive material such as polyimide or acrylic is applied. Is difficult to control. In that respect, the film thickness can be easily controlled on the counter substrate 200 side.
The second reason for forming the columnar spacer 210 on the counter substrate 200 is the number of steps required for manufacturing. As shown in FIG. 2, since the number of components on the color filter substrate 300 is larger than that on the counter substrate 200 except for the columnar spacers 210, the manufacturing process of the color filter substrate 300 is performed. Become a large number. By providing the columnar spacer 210 on the counter substrate 200 side, the number of manufacturing steps of both substrates can be averaged.

  FIG. 4 is a diagram illustrating the installation interval of the columnar spacers 210 in a cross section intersecting the plate surface of the liquid crystal panel 100. As shown in the figure, the columnar spacers 210 are provided such that the interval between the columnar spacers 210 is narrowed as the distance from the edge of the liquid crystal panel 100 to the central portion is approached. FIG. 5 is a diagram showing the installation density (number per unit area) of the columnar spacers 210 in the xy plane. As shown in the figure, the installation density of the columnar spacers 210 increases so as to approach the center from the four edges of the liquid crystal panel 100.

  The reason why the installation density of the columnar spacers 210 increases from the edge of the liquid crystal panel 100 toward the center is as follows. As described above, the counter substrate 200 and the color filter substrate 300 constituting the liquid crystal panel 100 are bonded together by the sealing material 110. Therefore, when a load in the direction of pushing the counter substrate 200 toward the color filter substrate 300 acts on the counter substrate 200, the amount of deflection of the counter substrate 200 varies depending on the position where the load acts. The amount of deflection becomes the largest when the load acts on the central portion of the counter substrate 200. If the applied load is the same, the amount of deflection becomes smaller as the position where the load is applied approaches the edge of the counter substrate 200. Therefore, by increasing the installation density of the columnar spacers 210 from the edge of the liquid crystal panel 100 toward the center, the amount of deflection of the counter substrate 200 does not exceed a certain value regardless of the position where the load acts. can do.

If the columnar spacers 210 are installed over the entire liquid crystal panel 100 at the same installation density as the central portion, the rigidity in the direction perpendicular to the plate surface of the liquid crystal panel 100 becomes too high, resulting in a decrease in liquid crystal volume at low temperatures. It becomes impossible to follow. As a result, bubbles are generated in the liquid crystal layer, resulting in poor image quality. According to this embodiment, since the rigidity in the direction perpendicular to the plate surface of the liquid crystal panel 100 does not become too high, bubbles can be prevented from being generated in the liquid crystal layer at low temperatures.
4 and 5 schematically show the distribution of the installation density of the columnar spacers 210. The actual installation density depends on the amount of deflection of the counter substrate 200 and the state of generation of bubbles at low temperatures. Etc. are determined by experiments and calculations.

As described above, according to the present invention, the columnar spacer has a total cross-sectional area of the spacer per unit area in a cross section parallel to both substrates, from the edge of the first substrate or the second substrate to the center. Since it is provided so as to increase as it approaches, the deflection amount of the counter substrate can be prevented from exceeding a certain value regardless of the position where the load acts. In addition, since the rigidity in the direction perpendicular to the plate surfaces of the first substrate and the second substrate does not become excessively high, it is possible to prevent the generation of bubbles due to the volume reduction of the electro-optic material at low temperatures.
Further, since the cross-sectional areas of the spacers are the same, manufacturing is easy. In addition, since the spacer is provided at a position that is a gap between adjacent pixels and close to the switching element, it is possible to prevent stress from being applied to the switching element.
Further, according to the present invention, in a reflective transflective liquid crystal display device having a step forming layer, the columnar spacer is provided on the surface where the step forming layer is not formed, so that the film pressure is controlled when the photosensitive material is applied. Is easy, and since there are few components other than a spacer, the manufacturing process of both board | substrates can be averaged.

<Modification>
The present invention is not limited to the form described above, and can be implemented in various forms. For example, the embodiment described above can be modified as follows.
In the above-described embodiment, the step forming layer 310 is described using the configuration example provided on the color filter substrate 300 side. However, the step forming layer 310 may be provided on the counter substrate 200 side. Further, the color filter 302 may be provided on the counter substrate 200 side. Further, the columnar spacer 210 may be formed on the substrate on the side where the step forming layer 310 is formed.
The shape of the columnar spacer 210 is not limited to a columnar shape, and may be a prismatic shape, or may be formed in an arbitrary shape such as a columnar shape or a tapered shape of a rectangular column.

In the above-described embodiment, the installation density of the columnar spacers 210 is increased as the distance from the edge of the liquid crystal panel 100 to the center portion is increased. However, the installation density of the columnar spacers 210 is uniform, and the longitudinal direction of the columnar spacers 210 is The cross-sectional area of the cross section intersecting with may be increased from the edge of the liquid crystal panel 100 toward the center. In this way, the number of columnar spacers 210 can be reduced.
In the above-described embodiment, the example of the reflective transflective liquid crystal display device has been described. However, the present invention is also suitable for a reflective liquid crystal display device and a transmissive liquid crystal display device.

  The present invention may be applied to electro-optical devices other than liquid crystal display devices. That is, an apparatus having a structure in which an electro-optic material that converts an electrical action such as supply of current or application of voltage into an optical action such as change in luminance or transmittance is sandwiched between two substrates facing each other. The present invention can be applied. For example, an organic EL display device using organic EL (Electro Luminescence) as an electro-optical material, or an electrophoretic display using microcapsules containing a colored liquid and white particles dispersed in the liquid as an electro-optical material Equipment, twist ball display using twist balls painted in different colors for areas with different polarities as electro-optical material, toner display using black toner as electro-optical material, or high pressure gas such as helium or neon The present invention can be applied to various electro-optical devices such as a plasma display panel used as an electro-optical material.

  In addition to the cellular phone 700 shown in FIG. 6, the electronic apparatus in which the electro-optical device 10 can be used as a display device is a digital still camera, a laptop computer, a liquid crystal television, a viewfinder type (or monitor direct view type) video. Examples include a recorder, a car navigation device, a pager, an electronic notebook, a calculator, a word processor, a workstation, a videophone, a POS terminal, and a device equipped with a touch panel.

1 is a diagram illustrating a configuration of an electro-optical device 10. FIG. 2 is a cross-sectional view of a liquid crystal panel 100. FIG. It is a figure which shows the surface which opposes the color filter substrate 300 of the counter substrate 200. It is a figure which shows the installation space | interval of the columnar spacer. It is a figure which shows the installation density of the columnar spacer 210. FIG. FIG. 11 shows a mobile phone 700.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Electro-optical apparatus, 100 ... Liquid crystal panel, 200 ... Opposite substrate, 300 ... Color filter substrate, 400 ... Scanning line drive circuit, 500 ... Data line drive circuit, 600 ... Control circuit, 900 ... Power supply circuit,
140 ... scanning line, 150 ... data line, 160 ... pixel, 161 ... pixel electrode, 162 ... TFD, 110 ... sealing material, 165 ... liquid crystal layer, 950 ... back light,
302 ... Color filter, 302R ... Colored layer, 302G ... Colored layer, 302B ... Colored layer, 302K ... Light-shielding layer, 306 ... Protective layer, 308 ... Alignment film, 309 ... Polarizer, 208 ... Alignment film, 209 ... Polarizer, 310 ... Step forming layer, 210 ... Columnar spacer, 301 ... Reflective layer, 301a ... Opening, 301b ... Reflective part.

Claims (6)

A first substrate and a second substrate provided opposite to each other and bonded together by a frame-shaped sealing material;
An electro-optic material layer sandwiched between the first substrate and the second substrate and divided into a plurality of pixels;
A plurality of columnar spacers protruding on the surface of the first substrate or the second substrate and contacting the other substrate;
The spacer is provided such that the sum of the cross-sectional areas of the spacer per unit area in a cross section parallel to both substrates increases as the distance from the edge of the first substrate or the second substrate approaches the central portion. An electro-optical device. Each of the spacers has the same cross-sectional area that intersects with the longitudinal direction of the spacer, and the number of the spacers per unit area increases from the edge of the first substrate or the second substrate toward the center. The electro-optical device according to claim 1, wherein the electro-optical device is provided. Each of the spacers is provided so that the number per unit area is uniform, and the cross-sectional area of the cross section that intersects the longitudinal direction of the spacer as it approaches the central portion from the edge of the first substrate or the second substrate. The electro-optical device according to claim 1, wherein the electro-optical device is formed to be large. A switching element provided in each of the pixels;
The electro-optical device according to claim 1, wherein the spacer is provided at a position close to the switching element in a gap between the pixels adjacent to each other. A reflection part provided on a surface of the second substrate that faces the first substrate, and reflects incident light from the first substrate side to the first substrate side, and incident light from the second substrate side A reflective layer that divides each of the pixels into an opening that transmits the light to the first substrate side;
A step forming layer provided so as to cover the reflective portion, and different in thickness between the electro-optic material layer in the reflective portion and the electro-optic material layer in the opening;
The electro-optical device according to claim 1, wherein the spacer is formed on a surface of the first substrate.   An electronic apparatus comprising the electro-optical device according to claim 1.

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