JP3738549B2 - Liquid crystal display element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a so-called two-way display type liquid crystal display element having a transflective plate on the back side.
[0002]
[Prior art]
When a sufficiently bright external light (natural light, indoor illumination light, etc.) is obtained, the two-way display type liquid crystal display element reflects the external light incident from the front side by a transflective reflector on the back side. When the external display with sufficient brightness cannot be obtained, the transmissive display using the light of the backlight arranged on the back side of the liquid crystal display element is performed. The two-way type liquid crystal display element includes a pair of front and rear substrates arranged opposite to each other, a plurality of first electrodes provided on the inner surface of one substrate, and at least one second electrode provided on the inner surface of the other substrate. Electrode, a liquid crystal layer provided between the pair of substrates, and a transflective plate provided on the back side.
[0003]
As the liquid crystal display element, a TN (twisted nematic) type in which the liquid crystal molecules of the liquid crystal layer are twisted with a predetermined twist angle between both substrates is often used. In the display element, polarizing plates are arranged on the front surface of the front substrate and the back surface side of the rear substrate (between the transflective plates), respectively, with the transmission axis directed in a predetermined direction.
[0004]
In addition, there are various types of liquid crystal display elements such as an active matrix type and a simple matrix type. For example, an active matrix type liquid crystal display element has a plurality of pixels arranged in a matrix on the inner surface of one substrate. An electrode, a plurality of active elements connected to the pixel electrodes, and a signal line for supplying a signal to the active element, and a counter electrode facing the plurality of pixel electrodes is provided on the inner surface of the other substrate. The plurality of pixel electrodes and the counter electrode are opposed to each other Do Each region is configured as a pixel region.
[0005]
Furthermore, the liquid crystal display element includes a monochrome image display and a color image display. In a liquid crystal display element displaying a multicolor image such as a full color image, the inner surface of the front substrate is A plurality of colored films having different transmission wavelength bands are provided so as to correspond to a plurality of pixel regions in which a plurality of first electrodes (for example, pixel electrodes) and the second electrode (for example, counter electrodes) face each other. ing.
[0006]
This colored film is generally red, green, and blue color filters, and each color filter emits almost all of the light transmitted through the pixel area as colored light with good color purity. It is formed in area.
[0007]
[Problems to be solved by the invention]
However, the two-way display type liquid crystal display element provided with the conventional color filter has a problem that the display is very dark when the reflection type display is performed using external light.
[0008]
This is mainly due to light absorption by the color filter, which transmits light in the wavelength band corresponding to the color of the color filter in the visible light band and absorbs light in other wavelength bands. For this reason, the intensity of the colored light transmitted through the color filter is considerably lower than the intensity of the incident light.
[0009]
In the case of a two-way liquid crystal display element, a decrease in display brightness when performing transmissive display using light from the backlight can be compensated by increasing the luminance of the backlight. However, when a reflective display is performed using external light, incident light with high brightness enough to compensate for light absorption by the color filter cannot be obtained, and light incident on the liquid crystal display element from the front of the element is not obtained. However, since it passes through the color filter twice before being reflected by the transflective member on the back side and emitted forward, the light absorption is further increased, and the display becomes considerably dark.
[0010]
For this reason, it has been conventionally considered to reduce the absorption of light by the color filter to make the display brighter by reducing the thickness of the color filter. As a result, the transmittance of light in the absorption wavelength band is also increased, so that colored light with good color purity cannot be obtained, and the color range of the displayed color image is narrowed.
[0011]
According to the present invention, a bright color image can be displayed when reflective display is performed using external light, and a color image with high contrast can be displayed when transmissive display is performed using backlight light. An object of the present invention is to provide a two-way liquid crystal display element.
[0012]
[Means for Solving the Problems]
The liquid crystal display element according to the present invention includes a pair of front and rear substrates opposed to each other, a plurality of first electrodes provided on the inner surface of one substrate, and at least one second electrode provided on the inner surface of the other substrate. Forming a plurality of pixel regions for controlling light transmission by regions where the plurality of first electrodes and the plurality of first electrodes and the second electrodes face each other, and corresponding to each of the plurality of pixel regions, A plurality of colored films having different transmission wavelength bands provided on the inner surface of the front substrate, a liquid crystal layer provided between the pair of substrates, and a transflective plate provided on the back side,
The colored films of the plurality of colors are each formed to have a size protruding outward from the outer peripheral edge of the pixel region, and an opening for emitting non-colored light is partially formed in the outer periphery of the colored film. A reflective film corresponding to a part of the pixel area and facing the opening of the colored film is provided on the inner surface of the rear substrate, and the reflective film is formed in the reflective area of the pixel area. A portion corresponding to the film forms a light reflection region, and a portion other than the region corresponding to the reflection film forms a light transmission region. It is characterized by that.
[0013]
According to this liquid crystal display element, the plurality of colored films are provided with openings for emitting non-colored light partially corresponding to the respective pixel regions, and the colored film is formed on the inner surface of the rear substrate. Since a reflective film is provided to face the opening, when performing a reflective display using external light, a portion other than the colored film opening of the light incident from the front of the element enters the corresponding region. Only the light is absorbed into the absorption wavelength band by the colored film to become colored light, and the colored light is reflected by the transflective reflector on the back side and emitted forward, and the opening of the colored film corresponds to the light. The light incident on the region is reflected by the reflective film on the inner surface of the rear substrate without being absorbed by the colored film, and is emitted to the front of the device as high-luminance non-colored light.
[0014]
For this reason, in the reflective display, the colored light that is absorbed by the colored film by the colored film and reflected by the transflective plate and absorbed by the colored film is not received from each pixel region. High luminance non-colored light reflected by the reflective film is emitted in front of the element, and the colored light and non-colored light display high luminance color pixels, thereby displaying a sufficiently bright color image. Can do.
[0015]
On the other hand, when performing transmissive display using the light of the backlight, only the light incident on the area corresponding to the portion other than the opening of the colored film among the light incident on each pixel area from the back side of the element However, the colored film absorbs light in the absorption wavelength band to become colored light, and the colored light is emitted in front of the element. In the region corresponding to the opening of the colored film, incident light is reflected on the inner surface of the rear substrate. It is blocked by the film and does not exit in front of the element.
[0016]
For this reason, in transmissive display, only colored light that has absorbed light in the absorption wavelength band by the colored film is emitted to the front of the device, and color pixels with high color purity are displayed by the colored light. A high-quality color image can be displayed.
[0017]
In this transmissive display, the light emitted in front of the element is only the colored light transmitted through the region corresponding to the portion other than the opening of the colored film. In the transmissive display, the light once passes through the colored film. Therefore, the luminance of the colored light emitted in front of the element is higher than that of the colored light emitted twice in the case of the reflective display, and if the luminance of the backlight is increased, the luminance of the emitted light is increased. Since the luminance can be further increased, the display brightness in the transmissive display is sufficient.
[0018]
Therefore, according to this liquid crystal display element, a bright color image is displayed when reflection type display is performed using external light, and black display is excellent when transmission type display is performed using backlight light. A color image with good contrast can be displayed.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the liquid crystal display element of the present invention is provided with openings for emitting non-colored light partially corresponding to each of the colored regions of the plurality of colored films provided on the inner surface of the front substrate, By providing a reflective film on the inner surface of the rear substrate so as to face the opening of the colored film, a bright color image is displayed when reflection type display is performed using external light, and transmission is performed using light from the backlight. When performing mold display, a color image with good contrast can be displayed.
[0020]
The present invention is applied to an active matrix type liquid crystal display device in which the first electrode is a plurality of pixel electrodes arranged in a matrix and the second electrode is a counter electrode facing the plurality of pixel electrodes. A plurality of pixel electrodes, a plurality of active elements respectively connected to the pixel electrodes, and gate lines and data lines for supplying gate signals and data signals to the active elements; It is desirable to provide a capacitor wiring for forming a compensation capacitor between the pixel electrode.
[0021]
In that case, a light reflection region provided with the reflection film and a light transmission region capable of transmitting light may be provided in the plurality of pixel regions, and the gate wiring, data wiring, and capacitor wiring may be provided. A part of at least one of the wirings may correspond to the pixel region, and that part may be used as the reflective film.
[0022]
【Example】
A first embodiment of the present invention will be described below with reference to the drawings. 1 is a front view of a part of the liquid crystal display element, and FIG. 2 is a cross-sectional view taken along line II-II in FIG.
The liquid crystal display element of this embodiment is of an active matrix type having TFTs (thin film transistors) as active elements, and a pair of front and rear substrates (transparent substrates made of glass or the like) 1 and 2 that face each other across the liquid crystal layer 19 Among them, a plurality of transparent pixel electrodes 3 are arranged in a matrix on the inner surface of the rear substrate 2, and active elements (hereinafter referred to as TFTs) 4 respectively corresponding to the pixel electrodes 3. It is arranged.
[0023]
In FIG. 1, among the pixel electrodes 3, (R) is a pixel electrode for displaying a red pixel, (G) is a pixel electrode for displaying a green pixel, and (B) is a pixel for displaying a blue pixel. These pixel electrodes 3 are arranged in a straight line alternately in the row direction (left-right direction of the screen), and pixel electrodes for displaying pixels of the same color in the column direction (up-down direction of the screen). The three are arranged in a zigzag by alternately shifting about 3 pitches in the row direction.
[0024]
The TFT 4 includes a gate electrode 5 formed on the rear substrate 2, a gate insulating film 6 covering the gate electrode 5, and an i formed on the gate insulating film 6 so as to face the gate electrode 5. And a source electrode 8 and a drain electrode 9 formed on both sides of the i-type semiconductor film 7 via an n-type semiconductor film (not shown).
[0025]
On the rear substrate 2, gate wirings 10 for supplying gate signals to the TFTs 4 of the respective rows are provided along one side of the respective pixel electrode rows, and the gate electrodes 5 of the TFTs 4 of the respective rows are provided. Are integrally formed on the gate wiring 10 corresponding to the row.
[0026]
The gate insulating film (transparent film) 6 of the TFT 4 is formed over almost the entire surface of the substrate 2, and the gate wiring 10 is covered with the gate insulating film 6 except for the terminal portion.
[0027]
On the gate insulating film 6, data wirings 11 for supplying data signals to the respective TFTs 4 of the respective columns are provided along one side of the respective pixel electrode columns. Each drain electrode 9 is connected to a data line 11 corresponding to the column.
[0028]
The data wiring 11 is formed in a meandering manner along each pixel electrode column (zigzag pixel electrode column) for displaying pixels of the same color, and the vertical wiring along the side edge of the pixel electrode 3 in each row. The horizontal wiring portion connecting the portions is wired in parallel with the gate wiring 10 between adjacent pixel electrode rows.
[0029]
In this embodiment, the data wiring 11 is wired on the gate insulating film 6, and the drain electrode 9 of the TFT 4 in each column is formed integrally with the data wiring 11 corresponding to that column. The wiring 11 may be formed by covering the TFT 4 with an insulating film and wiring on the insulating film, and connecting to the drain electrode 9 of the TFT 4 in a contact hole provided in the insulating film.
[0030]
The pixel electrode 3 is formed on the gate insulating film 6, and the pixel electrode 3 is connected to the source electrode 9 of the corresponding TFT 4 at the end of one side edge.
[0031]
Furthermore, on the rear substrate 2, there is provided a capacitor wiring 12 corresponding to each pixel electrode row and facing each pixel electrode 3 in that row across the gate insulating film 6. The capacitor wiring 12, the pixel electrode 3, and the gate insulating film 6 between them form a compensation capacitor (storage capacitor) for compensating for a change in potential of the pixel electrode 3 during the non-selection period. The capacitor wiring 12 is formed in parallel with the gate wiring 10 so as to face a portion slightly inward of the pixel electrode from the edge of the pixel electrode 3 opposite to the TFT connection side.
[0032]
The gate wiring 10 and the capacitor wiring 12 are formed of a metal film (for example, an aluminum alloy) having low resistance and high light reflectance, and the data wiring 11 is also formed of a metal film having low resistance and high reflectance. Has been. The surfaces of the gate wiring 10 and the capacitor wiring 12 are anodized in order to increase the withstand voltage between the pixel electrode 3 and the data wiring 11 formed on the gate insulating film 6.
[0033]
An alignment film 13 is provided over the entire pixel electrode array region on the inner surface of the rear substrate 2, that is, on the formation surface of the pixel electrode 3, the TFT 4, the data wiring 11, and the like.
[0034]
On the other hand, on the inner surface of the front substrate 1, colored films of a plurality of colors having different transmission wavelength bands, for example, red, green, and blue color filters 14R, 14G, and 14B are opposed to the array of the pixel electrodes 3. Then, the pixel electrodes 3 are all arranged on the transparent protective film (insulating film) 16 formed so as to cover the color filters 14R, 14G, and 14B. A single-film transparent counter electrode 17 is provided in which each of the regions facing the pixel electrodes 3 forms a pixel region A, and an alignment film 18 is formed thereon. The protective film 16 can be omitted by appropriately selecting the material of the color filters 14R, 14G, and 14B.
[0035]
The front substrate 1 and the rear substrate 2 are bonded to each other at a peripheral portion thereof via a frame-shaped sealing material (not shown), and a liquid crystal layer is formed in a region surrounded by the sealing material between the substrates 1 and 2. 19 is provided.
[0036]
The alignment films 13 and 18 provided on the inner surfaces of the pair of substrates 1 and 2 are each subjected to an alignment process by rubbing the film surfaces in a predetermined direction. The alignment directions of the liquid crystal molecules in the vicinity of the substrates 1 and 2 are regulated by the alignment film 13 of the rear substrate 2 and the alignment film 18 of the front substrate 1, and a predetermined twist angle ( For example, twist orientation is almost 90 °.
[0037]
Further, polarizing plates 21 and 22 are disposed on the outer surfaces of the pair of substrates 1 and 2, respectively, and these polarizing plates 21 and 22 are provided with their transmission axes directed in a predetermined direction. ing.
[0038]
In the liquid crystal display element of this example, the electric field is not applied to the liquid crystal layer 19 (the liquid crystal molecules are aligned in the initial twist alignment state where they are most inclined with respect to the substrates 1 and 2). Is a bright display, and as the liquid crystal molecules rise and align with respect to the surfaces of the substrates 1 and 2 by applying an electric field to the liquid crystal layer 19, the light emission rate decreases and the display becomes dark. For example, when the twist angle of liquid crystal molecules is approximately 90 °, the polarizing plates 21 and 22 are provided with their transmission axes substantially orthogonal to each other. .
[0039]
Further, a transflective plate 23 is disposed behind the liquid crystal display element, that is, behind the rear polarizing plate 22, and a backlight 24 is disposed behind the transflective plate 23. .
[0040]
The red, green, and blue color filters 14R, 14G, and 14B provided on the inner surface of the front substrate 1 of the liquid crystal display element will be further described. The color filters 14R, 14G, and 14B are, for example, filters using a pigment dispersion material. Among these color filters 14R, 14G, and 14B, the red filter 14R corresponds to the pixel region A in which the pixel electrode 3 and the counter electrode 17 of (R) for displaying red pixels are opposed to each other, The green filter 14G corresponds to the pixel region A in which the pixel electrode 3 of (G) for displaying the green pixel and the counter electrode 17 are opposed to each other, and the blue filter 14B is the pixel of (B) for displaying the blue pixel. The electrode 3 and the counter electrode 17 correspond to the pixel region A facing each other.
[0041]
Each of these color filters 14R, 14G, and 14B has a film thickness for obtaining colored light with good color purity, and an opening for emitting non-colored light partially corresponding to the pixel region A. 15 is formed in a shape.
[0042]
In this embodiment, the color filters 14R, 14G, and 14B for each color are formed in a shape in which a vertically long rectangular opening 15 corresponding to the central portion of the pixel region A is provided in the central region, and the color filters 14R, 14R, 14G and 14B are formed so that the outer peripheral edge of the outer periphery protrudes outward from the outer peripheral edge of the pixel region A.
[0043]
Therefore, in this embodiment, the area other than the opening 15 of the color filters 14R, 14G, and 14B corresponds to the area, that is, the area between the surrounding area of the pixel area A and the adjacent pixel area A (hereinafter referred to as the inter-pixel area). Is a colored light emitting region a, and a region corresponding to the opening 15 of the color filters 14R, 14G, 14B, that is, a central region of the pixel region A is a non-colored light emitting region b.
[0044]
The overhang width of each color filter 14R, 14G, 14B from the pixel area A is set to approximately ½ of the width of the area between the adjacent pixel areas A, and the adjacent color filters 14R, 14G. , 14B are in contact with each other without a gap.
[0045]
Each pixel electrode 3 provided on the inner surface of the rear substrate 2 is made of a transparent conductive film such as ITO, and the central region thereof faces the opening 15 of the color filters 14R, 14G, and 14B. A vertically-long rectangular reflective film 3b is provided on the pixel electrode. That is, each pixel area A is composed of a light reflection area in which the reflection film 3b is formed on each pixel electrode 3 and another light transmission area 3a in which the reflection film 3b is not formed. Yes. The reflective film 3b has a light reflectivity such as aluminum or chromium. high It consists of a metal film, and its surface is a scattering reflection surface roughened by oxygen plasma treatment or the like.
[0046]
This liquid crystal display element uses external light by reflecting the external light incident from the front of the element by the transflective reflector 23 on the back side when sufficiently bright external light (natural light, indoor illumination light, etc.) is obtained. When the external display with sufficient brightness is not obtained and the external display with sufficient brightness is not obtained, the display is of the two-way type that performs the transmissive display using the light of the backlight 24 arranged behind the liquid crystal display element. .
[0047]
First, the reflection type display will be described. In this reflection type display, the light incident from the front of the element is absorbed by the front polarizing plate 21 with the polarization component light along the absorption axis, and the polarization component along the transmission axis is absorbed. It becomes linearly polarized light.
[0048]
Of the incident light, a colored light emitting region a (a region surrounding the pixel region A and an inter-pixel region) corresponding to a portion other than the opening 15 of the color filters 14R, 14G, and 14B provided on the inner surface of the front substrate 1. The light incident on the light is absorbed by the color filters 14R, 14G, and 14B and colored in the colors of the color filters 14R, 14G, and 14B, and becomes red, green, and blue colored light. Incident on the liquid crystal layer 19. In the pixel region A, the colored light transmitted through the liquid crystal layer 19 is transmitted through the light transmission region 3a other than the light reflection region and incident on the rear polarizing plate 22, and the rear polarization of the light. Light having a polarization component along the transmission axis of the plate 22 passes through the polarizing plate 22 and is reflected by the semi-transmissive reflecting plate 23, and the rear polarizing plate 22, the liquid crystal layer 19, the color filters 14R, 14G, and 14B and the front side. The light passes through the polarizing plate 21 and is emitted in front of the element.
[0049]
In addition, external light incident on the inter-pixel region from the front of the element passes through the TFT 4 provided in the inter-pixel region, the gate wiring 10 and the data wiring 11 passing through the inter-pixel region, and the pixel region A and the inter-pixel region. The colored light transmitted through the liquid crystal layer 19 in the colored light emitting region a is reflected by the source and drain electrodes 8 and 9 on the surface of the TFT 4 and the wirings 10, 11, and 12 because of the capacitive wiring 12 that traverses. , Rear polarizing plate 22 and transflective plate 23 Without reaching The liquid crystal layer 19, the color filters 14R, 14G, and 14B and the front polarizing plate 21 are sequentially transmitted and emitted forward of the element.
[0050]
The colored light and the non-colored light incident on the liquid crystal layer 19 Through In the process, the optical rotation is caused by the birefringence, and the alignment state of the liquid crystal molecules is changed by the electric field applied between the electrodes 3 and 18, and the intensity of the emitted light is changed. However, the intensity of the emitted light from the inter-pixel region always corresponds to the intensity of the incident external light because the inter-pixel region is always in an electric field-free state and the liquid crystal molecules are always aligned in the initial twist alignment state. It is a certain strength.
[0051]
On the other hand, the light incident on the non-colored light emission region b (the central region of the pixel region A) corresponding to the opening 15 of the color filters 14R, 14G, 14B is not absorbed by the color filters 14R, 14G, 14B. The light enters the liquid crystal layer 19 as high-luminance non-colored light. Reflected by the reflective film 3b provided in the central region of the pixel region A, the liquid crystal layer 19, the color filters 14R, 14G, and 14B, and the front polarizing plate without passing through the rear polarizing plate 22 and the transflective plate 23. 21 are sequentially transmitted, and are emitted in front of the element as high-luminance non-colored light. The intensity of the emitted light from this non-colored light emitting region b changes according to the change in the alignment state of the liquid crystal molecules due to the electric field applied between the electrodes 3 and 18.
[0052]
Thus, when reflective display is performed using external light, portions other than the openings 15 of the color filters 14R, 14G, and 14B in the external light incident from the front of the element are in the corresponding colored light emission regions a. Only the incident light is absorbed by the color filters 14R, 14G, and 14B into light in the absorption wavelength band to become colored light, and the colored light is reflected by the transflective reflector 23 on the back side and emitted forward of the element. The light incident on the non-colored light emission region b corresponding to the opening 15 of the color filters 14R, 14G, and 14B is not absorbed by the color filters 14R, 14G, and 14B, and is applied to the pixel electrode 3 on the inner surface of the rear substrate 2. Is reflected by the reflective film 3b, and is emitted in front of the device as high-luminance non-colored light.
[0053]
For this reason, in the reflective display, the colored light that has been absorbed by the color filters 14R, 14G, and 14B and reflected by the transflective plate 23 from the pixel regions A and the color filters 14R, High luminance non-colored light reflected by the reflective film 3b without being absorbed by 14G and 14B is emitted in front of the element, and the high luminance color pixels are displayed by the colored light and the non-colored light.
[0054]
Therefore, a sufficiently bright color image can be displayed even if the color filters 14R, 14G, and 14B are thick enough to obtain colored light with good color purity.
[0055]
FIG. 3 is a diagram showing an array of pixels and color filters in the reflective display, and each color pixel A ′ is an inter-pixel region between the peripheral region of the pixel region A and the adjacent pixel region A. Colored light a ′ of red R, green G, or blue B, which is emitted from the colored light emitting area a almost in the middle, and the output from the non-colored light emitting area b, which is the central area of the pixel area A Although it is displayed with non-colored light b ′ which is an incident light, it appears to the human eye that the entire pixel A ′ is colored in the color of the colored light, and these red, green and blue color pixels A full color image is displayed by the additive color mixture of A ′.
[0056]
The color pixel A ′ that can be seen by the human eye is a high-brightness pixel in which the color of the colored light is slightly lighter, and the darkness and brightness of the color are the light amounts of the colored light and the non-colored light. Corresponds to the ratio. The color density and brightness of the color pixel A ′ can be arbitrarily set by selecting the area ratio of the openings 15 of the color filters 14R, 14G, and 14B to the area of the pixel region A and the light reflection region. .
[0057]
Next, the transmissive display will be described. In this transmissive display, light from the backlight 24 is incident on the transflective plate 23 from the back side, and the light transmitted through the transflective plate 23 is rear-side polarized light. The light of the polarization component along the absorption axis is absorbed by the plate 22 to become linearly polarized light of the polarization component along the transmission axis.
[0058]
In the colored light emission region a (the peripheral region of the pixel region A and the inter-pixel region), incident light from the back surface of the element passes through the light transmission region 3a that transmits light other than the light reflection region of the pixel region A. In the process of entering the liquid crystal layer 19 and passing through the liquid crystal layer 19, it is rotated by its birefringence, and the light is absorbed by the color filters 14R, 14G, and 14B in the absorption wavelength band, and the color filter 14R. , 14G, and 14B, resulting in red, green, and blue colored light.
[0059]
These colored lights are incident on the front polarizing plate 21, and the light of the polarization component along the transmission axis of the front polarizing plate 21 out of the light passes through the polarizing plate 21 and is emitted in front of the element. The intensity of the emitted light changes according to the change in the alignment state of the liquid crystal molecules due to the electric field applied between the electrodes 3 and 18.
[0060]
On the other hand, in the non-colored light emission region b (the central region of the pixel region A) corresponding to the openings 15 of the color filters 14R, 14G, and 14B, the light incident from the back of the element enters the light reflection region in the pixel region A. Incident light is blocked by the reflective film 3b, and does not exit in front of the element.
[0061]
As described above, when transmissive display is performed using the light of the backlight 24, the colored light emission corresponding to the portions other than the openings 15 of the color filters 14R, 14G, and 14B among the light incident from the back side of the element. Only the light that has entered the region a is absorbed by the color filters 14R, 14G, and 14B and becomes colored light, and the colored light is emitted forward of the element.
[0062]
However, of the light incident on the colored light emitting area a, the light incident on the TFT 4 portion provided on the inner surface of the rear substrate 2 and the portion through which the wirings 10, 11, 12 pass is the TFT 4 and each wiring. Since the light is blocked by 10, 11, and 12 and is not emitted in front of the element, the colored light is emitted from a region other than the portion through which the TFT 4 and the wirings 10, 11, and 12 pass in the colored light emission region a. To do.
[0063]
For this reason, in the transmissive display, only the colored light in which the light in the absorption wavelength band is absorbed by the color filters 14R, 14G, and 14B is emitted from each pixel region A, and the color pixel having high color purity by the colored light. Is displayed, it is possible to display a color image in a wide color range.
[0064]
FIG. 4 is a diagram showing an array of pixels and color filters in the transmissive display, and each color pixel A ′ is an inter-pixel region between the peripheral region of the pixel region A and the adjacent pixel region A. The additive light mixture of the red, green, and blue color pixels A ′ is displayed by one of the red R, green G, and blue B colored light a ′ that is the light emitted from the colored light emitting region a over almost the middle portion. As a result, a full color image is displayed.
[0065]
In FIG. 4, c is a shadow of the reflection film 3b, d is a shadow of the TFT 4, e is a shadow of the gate wiring 10, f is a shadow of the data wiring 11, and g is a shadow of the capacitor wiring 12. Since c, d, e, f, and g appear as a black matrix that separates the color pixels A ′, the color image displayed by the transmissive display is a clear image.
[0066]
In the transmissive display, the light emitted in front of the element is only the colored light transmitted through the colored light emitting region a corresponding to the portions other than the openings 15 of the color filters 14R, 14G, and 14B. In this case, since the light passes through the color filters 14R, 14G, and 14B only once, the luminance of the colored light emitted in front of the element passes through the color filters 14R, 14G, and 14B emitted in the case of the reflective display twice. Since the brightness of the emitted light can be further increased by increasing the brightness of the backlight 24 and the brightness of the backlight 24, the brightness of the display in the transmissive display is sufficient.
[0067]
Therefore, according to the liquid crystal display element, a bright color image is displayed when reflection type display is performed using external light, and a high contrast color is displayed when transmission type display is performed using light of the backlight 24. An image can be displayed.
[0068]
In addition, in the above-described embodiment, the color filters 14R, 14G, and 14B for the respective colors are formed so that the outer peripheral edge portions protrude outward from the outer peripheral edge of the pixel region A, and the color filters 14R, 14G, and 14B are formed. The region corresponding to the portion other than the opening 15 of 14B, that is, the peripheral region of the pixel region A and the inter-pixel region between the adjacent pixel regions are used as the colored light emitting region a, and thus transmits through the inter-pixel region. Since the light emitted in front of the element is also absorbed by the color filters 14R, 14G, and 14B into colored light, leakage of high-intensity non-colored light from the inter-pixel region is eliminated. In particular, since the luminance of the black display state in the transmissive display can be reduced, a good contrast can be obtained.
[0069]
In the first embodiment, the liquid crystal layer 19 side surface of the central region of each pixel electrode 3 provided on the inner surface of the rear substrate 2 is formed in the openings 15 of the color filters 14R, 14G, and 14B of the front substrate 1. Although the opposing reflective film 3 b is provided, the reflective film 3 b may be provided in a layer between the pixel electrode 3 and the rear substrate 2.
[0070]
Further, the reflective film facing the openings 15 of the color filters 14R, 14G, and 14B is formed by at least one of the gate wiring 10 and the data wiring 11 and the capacitor wiring 12 provided on the inner surface of the rear substrate 2. May be.
[0071]
FIG. 5 is a front view of a part of a liquid crystal display device according to a second embodiment of the present invention. This embodiment is a vertically long capacitive electrode facing the capacitive wiring 12 at the center of each pixel electrode 3. Are formed integrally, and these capacitive electrodes are formed as the reflective films 12b facing the openings 15 of the color filters 14R, 14G, and 14B, respectively.
[0072]
When the capacitor wiring 12 is used as the reflection film 12b as in this embodiment, the entire capacitance wiring 12 or the surface of the reflection film (capacitance electrode) 12b portion thereof is roughened by oxygen plasma treatment or the like. It is preferable that at least the reflection film 12b is a scattering reflection surface.
[0073]
In this embodiment, a capacitor electrode facing the center region of the pixel electrode 3 is formed on the capacitor wire 12 and this capacitor electrode is used as the reflective film 12b. However, the capacitor wire 12 itself is formed in the center region of each pixel electrode 3. The portions of the wiring 12 that are bent so as to face each other and facing the openings 15 of the color filters 14R, 14G, and 14B may be used as a reflective film.
[0074]
Further, in the second embodiment, the capacitor wiring 12 is the reflective film 12b. However, the gate wiring 10 or the data wiring 11 may be formed integrally with an extension part corresponding to each pixel region A, or The wirings 10 and 11 themselves may be bent so as to pass through each pixel region A, and the gate wiring 10 or the data wiring 11 may be a reflective film facing the openings 15 of the color filters 14R, 14G, and 14B.
[0075]
In addition, it is desirable that the external dimensions of the reflection films 3b and 12a be larger than or equal to the opening dimension of the opening 15, thereby effectively preventing the transmission of non-colored transmitted light.
[0076]
In the liquid crystal display elements of the first and second embodiments, the pixel electrodes 3 for displaying red, green, and blue pixels are arranged alternately in the row direction and arranged in a straight line, and in the column direction. Is a so-called mosaic arrangement type in which pixel electrodes 3 for displaying pixels of the same color are alternately shifted in the row direction by about 1.5 pitches and arranged in a zigzag manner. The present invention can also be applied to a so-called lattice arrangement type liquid crystal display element in which pixel electrodes 3 for displaying blue pixels are arranged in a straight line both in the row direction and in the column direction.
[0077]
In the liquid crystal display element of the above embodiment, the color filters 14R, 14G, and 14B of the respective colors are provided without gaps between the side edges of the adjacent color filters 14R, 14G, and 14B. You may arrange | position a light shielding film in the boundary with 14R, 14G, 14B. With this light shielding film, light can be prevented from being emitted from a gap without a color filter generated due to the disposition, and the contrast is prevented from being lowered. Further, the light shielding film and the color filters 14R, 14G, and 14B are partially laminated. Therefore, the alignment accuracy when the color filters 14R, 14G, and 14B are arranged is relaxed, and the manufacture becomes easy.
[0078]
In the above-described embodiment, the openings 15 of the color filters 14R, 14G, and 14B and the reflective films 3b and 12a that face the openings 15 are provided corresponding to the center of the pixel region A. However, the color filter 14R , 14G, 14B and the reflective films 3b, 12a may be provided corresponding to a plurality of locations in the pixel region A.
[0079]
Furthermore, in the said Example, although the color filter is used as a colored film, the said colored film is not restricted to a color filter. The liquid crystal display element of the above embodiment displays a full-color image by mixing red, green, and blue light. However, the present invention provides a colored film (for example, a color filter) of magenta, yellow, and cyan. And a liquid crystal display element that displays a full-color image by a mixture of magenta, yellow, and cyan light colored in the color of these colored films.
[0080]
In addition, the present invention is not limited to an active matrix type using TFT as an active element, but an active matrix type liquid crystal display element using MIM as an active element, and a plurality of scanning electrodes along one direction on the inner surface of one substrate. The present invention can also be applied to a simple matrix type liquid crystal display element or the like in which a plurality of signal electrodes are provided in parallel with each other, and a plurality of signal electrodes are provided in parallel with each other on the inner surface of the other substrate.
[0081]
【The invention's effect】
The liquid crystal display element according to the present invention includes a pair of front and rear substrates opposed to each other, a plurality of first electrodes provided on the inner surface of one substrate, and at least one second electrode provided on the inner surface of the other substrate. Forming a plurality of pixel regions for controlling light transmission by regions where the plurality of first electrodes and the plurality of first electrodes and the second electrodes face each other, and corresponding to each of the plurality of pixel regions, A plurality of colored films having different transmission wavelength bands provided on the inner surface of the front substrate, a liquid crystal layer provided between the pair of substrates, and a transflective plate provided on the back side, The colored films of the plurality of colors are each formed to have a size protruding outward from the outer peripheral edge of the pixel region, and an opening for emitting non-colored light is partially formed in the outer periphery of the colored film. A reflective film corresponding to a part of the pixel area and facing the opening of the colored film is provided on the inner surface of the rear substrate, and the reflective film is formed in the reflective area of the pixel area. A portion corresponding to the film forms a light reflection region, and a portion other than the region corresponding to the reflection film forms a light transmission region. According to this liquid crystal display element, when reflective display is performed using external light, a bright color image is displayed, and transmissive display is performed using backlight light. The brightness of the black display can be reduced, and a color image with good contrast can be displayed.
[Brief description of the drawings]
FIG. 1 is a front view of a part of a liquid crystal display device according to a first embodiment of the present invention.
2 is a cross-sectional view taken along line II-II in FIG.
FIG. 3 is a diagram showing an arrangement of pixels and color filters in the reflective display of the liquid crystal display element.
FIG. 4 is a diagram showing an arrangement of pixels and color filters in the transmissive display of the liquid crystal display element.
FIG. 5 is a front view of a part of a liquid crystal display device according to a second embodiment of the present invention.
[Explanation of symbols]
1, 2, ... Board
3. Pixel electrode
3b ... Reflective film
4 ... TFT (active element)
10 ... Gate wiring
11 ... Data wiring
12 ... Capacitive wiring
12b ... reflective film
14R, 14G, 14B ... Color filters
15 ... Opening
18 ... Counter electrode
21, 22 ... Polarizing plate
23. Transflective plate
24 ... Backlight
A ... Pixel area
a ... Colored light emission region
b: Non-colored light emission region

Claims (4)

A pair of front and rear substrates disposed opposite to each other, a plurality of first electrodes provided on an inner surface of one substrate, at least one second electrode provided on an inner surface of the other substrate, and the plurality of first electrodes A plurality of pixel regions for controlling light transmission are formed by regions where one electrode and the second electrode are opposed to each other, and are provided on the inner surface of the front substrate so as to correspond to each of the plurality of pixel regions. A plurality of colored films having different transmission wavelength bands, a liquid crystal layer provided between the pair of substrates, and a transflective plate provided on the back side,
The colored films of the plurality of colors are each formed to have a size protruding outward from the outer peripheral edge of the pixel region, and an opening for emitting non-colored light is partially formed in the outer periphery of the colored film. A reflective film corresponding to a part of the pixel area and facing the opening of the colored film is provided on the inner surface of the rear substrate. A portion corresponding to the film forms a light reflection region, and a portion other than the region corresponding to the reflection film forms a light transmission region .   The first electrode is a plurality of pixel electrodes arranged in a matrix, the second electrode is a counter electrode facing the plurality of pixel electrodes, and the plurality of pixel electrodes are formed on an inner surface of the rear substrate. A plurality of active elements respectively connected to the pixel electrodes, a gate wiring and a data wiring for supplying a gate signal and a data signal to the active elements, and a capacitance wiring for forming a compensation capacitor between the pixel electrodes The liquid crystal display element according to claim 1, wherein:   3. The liquid crystal display element according to claim 2, wherein the plurality of pixel electrodes include a light reflection region formed of the reflection film and a light transmission region formed of a transparent conductive film.   3. A part of at least one of the gate wiring, the data wiring, and the capacitor wiring corresponds to the pixel region, and the part serves as the reflective film. The liquid crystal display element as described.

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