JPH1195211A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel display system adopting a mirror finished surface for a display as a liquid crystal display element display-driven by controlling double refractivity of a liquid crystal layer by impressing a voltage. SOLUTION: On a front side of a liquid crystal cell 10 sandwiching a liquid crystal layer 18 varying in double refractivity according to an applied voltage, a polarizing plate 21 is arranged, and on the back side of the liquid crystal cell 10, an optical sheet 22 with such characteristics as it has a reflection axis and a transmission axis mutually intersecting at approximately right angles and reflects incident light of the polarized light component along the reflection axis and transmits the polarized component along the transmission axis, and also behind this optical sheet 22, a rear face member 23 presenting a predetermined color is provided to display a picture by reflected light of external light and the color presented by the rear face member 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device driven for display by controlling the birefringence of a liquid crystal layer by applying a voltage.

[0002]

2. Description of the Related Art Liquid crystal display elements driven for display by controlling the birefringence of a liquid crystal layer by applying a voltage include a TN (twisted nematic) type, a STN (super twisted nematic) type, and an ECB (multiple twisted nematic) type. (Refraction effect) type, and a ferroelectric liquid crystal display device using a ferroelectric liquid crystal or an antiferroelectric liquid crystal.

[0003] These liquid crystal display elements include a liquid crystal having a liquid crystal layer whose birefringence changes according to a voltage applied between the electrodes, between a pair of front and rear substrates having electrodes formed on opposing surfaces. Polarizing plates are arranged on the front and rear sides of the cell, respectively.

In this liquid crystal display device, the birefringence of the liquid crystal layer is controlled by applying a voltage between the electrodes of the liquid crystal cell, so that the light passes through one of the polarizing plates and the liquid crystal cell and enters the other polarizing plate. The display is driven by changing the polarization state of the light to be emitted according to the birefringence of the liquid crystal layer and controlling the transmittance of the light passing through the other polarizing plate.

There are two types of liquid crystal display devices: a transmissive type that displays by using light from a backlight and a reflective type that displays by using external light such as natural light or indoor illumination light. is there.

[0006]

However, the above-mentioned conventional liquid crystal display device merely changes the light transmittance to display an image in bright and dark. An object of the present invention is to provide a liquid crystal display element having a new display form as a liquid crystal display element driven to display by controlling the birefringence of a liquid crystal layer by applying a voltage.

[0007]

The liquid crystal display device of the present invention has a birefringence between a pair of front and rear substrates having electrodes formed on respective surfaces facing each other in accordance with a voltage applied between the electrodes. A liquid crystal cell sandwiching a changing liquid crystal layer, a polarizing plate disposed on the front side of the liquid crystal cell, and disposed on the rear side of the liquid crystal cell, having a reflection axis and a transmission axis in directions substantially orthogonal to each other, An optical sheet having a property of reflecting incident light of a polarization component along the reflection axis and transmitting incident light of a polarization component along the transmission axis, and a rear member provided behind the optical sheet. It is characterized by having.

This liquid crystal display element is driven for display by controlling the birefringence of the liquid crystal layer by applying a voltage between the electrodes of the liquid crystal cell, and reflects external light incident from the front of the display element on the optical sheet. The image is displayed by the light and the color of the rear surface member.

That is, in this liquid crystal display device,
External light incident from the front surface passes through the polarizing plate and the liquid crystal cell in order, and is incident on the optical sheet. Among the light, light of a polarization component along the reflection axis of the optical sheet is transmitted through the optical sheet. The reflected light of the polarization component along the transmission axis of the optical sheet is transmitted through the optical sheet.

The polarization state of the light incident on the optical sheet changes according to the birefringence of the liquid crystal layer controlled by the application of a voltage, whereby the reflected light intensity of the light incident on the optical sheet is changed. And the transmitted light intensity changes.

Therefore, when the display of each pixel region of the liquid crystal cell is observed from the front side of the liquid crystal display element, the display of these pixel regions is based on the polarization of incident light to the portion corresponding to the pixel region of the optical sheet. It changes depending on the state, and when most of the light incident on the optical sheet is light of a polarization component along the reflection axis, specular reflected light of external light (reflected light on the optical sheet) is visible, and When most of the light is polarized light components along the transmission axis, the color of the rear member provided behind the optical sheet is visible, and the incident light is polarized light components along the reflection axis and polarization components along the transmission axis. When the light includes both, the mirror-reflected light of the external light and the color of the rear member appear to be mixed.

As described above, the liquid crystal display device of the present invention
The liquid crystal display device has a new display form, in which an image is displayed by the specular reflected light of the external light by the optical sheet and the color of the rear surface member. Can be displayed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The liquid crystal display device of the present invention comprises a polarizing plate disposed on the front side of a liquid crystal cell sandwiching a liquid crystal layer whose birefringence changes according to a voltage, as described above. An optical sheet having a property of reflecting incident light of a polarization component along the reflection axis and transmitting incident light of a polarization component along the transmission axis is arranged on the rear surface side, and a rear member behind the optical sheet. A mirror image of external light from the optical sheet and a color of the rear surface member, so that an image having a new observation feeling is displayed.

In the liquid crystal display device according to the present invention, the rear member may be, for example, a scattering reflector or a light absorbing plate, a fluorescent plate that absorbs incident light and emits fluorescence of a predetermined color, or a predetermined spectral intensity distribution. In short, a light-emitting body that emits light that has a different color from the mirror-reflected light from the optical sheet may be used.

The scattering reflector is a white scattering reflector that reflects all light in the visible light band, even if it is a colored scattering reflector that reflects light in a predetermined wavelength band of the visible light band. There may be.

The light absorbing plate may be a colored plate that absorbs light in a predetermined wavelength band of the visible light band, or a black plate that absorbs all light in the visible light band. It may be a white plate that reflects all light in the visible light band.

Further, in this liquid crystal display device, the polarizing plate may be a color polarizing plate of a predetermined color. Further, a colored transparent film of a predetermined color may be provided on one of the front and rear surfaces of the liquid crystal cell.

In the liquid crystal display device of the present invention, a TN type, STN type, ECB type, ferroelectric liquid crystal or antiferroelectric liquid crystal can be used as long as display is performed by controlling the birefringence of a liquid crystal layer by an electric field. A device that operates in any mode, such as a ferroelectric liquid crystal display device using liquid crystal, may be used.

For example, as an embodiment of a TN type liquid crystal display element, a liquid crystal cell in which liquid crystal molecules of a liquid crystal layer are twist-oriented between a pair of substrates is used, and the polarizing plate is provided with a transmission axis. Are arranged in a direction substantially orthogonal to or substantially parallel to the alignment direction of the liquid crystal molecules in the vicinity of the front substrate of the liquid crystal cell, and the reflection axis of the optical sheet is substantially orthogonal or substantially parallel to the transmission axis of the polarizing plate. There is a form of disposing them in different directions.

In one embodiment of the STN-type or ECB-type liquid crystal display device, the liquid crystal cell uses a liquid crystal layer in which liquid crystal molecules of a liquid crystal layer are twisted between a pair of substrates, and uses the polarizing plate. The transmission axis of the liquid crystal cell is arranged in a direction obliquely intersecting with the alignment direction of the liquid crystal molecules in the vicinity of the front substrate of the liquid crystal cell, and the reflection axis of the optical sheet is substantially equal to the transmission axis of the polarizing plate. There is a form of disposing them in a direction orthogonal or substantially parallel.

For example, in the case of the STN type liquid crystal display device, the twist angle of liquid crystal molecules between a pair of substrates of the liquid crystal cell is preferably in a range of 180 ° to 270 °,
In the case of this STN type liquid crystal display device, it is desirable to provide a retardation plate for color compensation between the liquid crystal cell and the polarizing plate.

[0022]

1 to 4 show a first embodiment of the present invention. FIG. 1 is a sectional view of a liquid crystal display device. In the liquid crystal display device of this embodiment, as shown in FIG. 1, a polarizing plate 21 is disposed on the front side of a liquid crystal cell 10 having a liquid crystal layer in which liquid crystal molecules are twist-aligned, and described later on the rear side of the liquid crystal cell 10. An optical sheet 22 having the characteristic of
Behind the optical sheet 22, there is provided, as a rear surface member, a colored plate 23 that absorbs light in a predetermined wavelength band of the visible light band, which is a kind of light absorbing plate. The polarizing plate 21 used in this embodiment is a non-colored polarizing plate generally called a neutral polarizing plate.

The liquid crystal cell 10 has transparent electrodes 13 and 14 formed on opposing surfaces thereof, and alignment films 15 and 16 provided thereon. A liquid crystal layer 18 whose birefringence changes according to a voltage applied to the gaps 13 and 14 is sandwiched between the pair of substrates 11 and 12, which are joined via a frame-shaped sealing material 17. The liquid crystal is used for both substrates 11, 1
It is sealed in a region surrounded by the sealing material 17 between the two. The alignment films 15 and 16 are horizontal alignment films made of polyimide or the like, and the alignment is performed by rubbing the film surfaces in a predetermined direction.

The liquid crystal cell 10 is, for example, of a segment display type driven in a time-division manner, and a transparent electrode 14 provided on one substrate (the rear substrate in this embodiment) 12 has a shape corresponding to each display pixel. The transparent electrode 13 provided on the other substrate (the front substrate in this embodiment) 11 is a divided common electrode facing the plurality of segment electrodes 14.

Next, the optical sheet 22 disposed on the rear surface side of the liquid crystal cell 10 will be described. FIG. 3 is a perspective view of the optical sheet 22, and the optical sheet 22 has a reflection axis in a direction substantially orthogonal to each other. 22s and a transmission axis 22p, and has a characteristic of reflecting incident light of a polarization component along the reflection axis 22s and transmitting incident light of a polarization component along the transmission axis 22p.

That is, as shown in FIG. 3, the optical sheet 22 has a polarization component (hereinafter referred to as an S-polarization component) light s along its reflection axis 22s and a polarization component along the transmission axis 22p. When light including both light p (hereinafter, referred to as P-polarized light component) is incident, the light s of the S-polarized light component along the reflection axis 22s is incident on the optical sheet 2.
2, the light p of the P-polarized component along the transmission axis 22p passes through the optical sheet 22. Although FIG. 3 shows an example in which light is incident on the optical sheet 22 from the front side, the optical sheet 22 exhibits the same characteristics with respect to incident light from the rear side. The optical sheet 22 is a non-colored sheet whose reflection characteristics and transmission characteristics have no wavelength dependence, and the reflected light is glossy specular reflection light.

Although the optical sheet 22 has a structure not shown, for example, a pair of concave and convex surfaces having a shape in which a horizontally long prism-like portion having a minute width is continuously arranged in the width direction and parallel to each other is formed on one surface. The transparent film, the top of the uneven surface of one film and the valley of the uneven surface of the other film are overlapped facing each other, between the uneven surface of both films, a plurality of transparent refractive index different A laminated film in which films are alternately laminated is sandwiched.
U.S. Pat. Nos. 5,422,756 and 5,559,63
No. 4.

The colored plate (rear member) 23 provided behind the optical sheet 22 has a color different from the specular reflection light from the optical sheet 22, and is, for example, red, green, or blue. , Purple, gold or the like.

The colored plate 23 used in this embodiment is a transparent resin film colored in a predetermined color on the back surface (optical sheet 2).
(A surface opposite to the surface opposite to the surface 2) is formed with a reflective film made of a silver or aluminum plating film or a vapor-deposited film.

The colored plate 23 may be provided integrally with the optical sheet 22 by printing a colored transparent paint on the rear surface of the optical sheet 22 and forming a reflective film on the rear surface.
In the case of a colored plate of a metal color such as gold, a metal such as gold may be formed on the rear surface of the optical sheet 22 by plating or vapor deposition. Further, the colored plate 23 may be formed of a colored or colorless scattering surface or a resin film having scattering particles. In this case, a reflective film may not be provided on the back surface of the colored plate 23.

In this embodiment, the liquid crystal cell 1
As 0, a nematic liquid crystal having a positive dielectric anisotropy is sealed, and the liquid crystal molecules of the liquid crystal layer 18 are formed of a pair of substrates
The polarizing plate 21 is twisted with a twist angle of about 90 ° between the two, and the transmission axis of the polarizing plate 21 is substantially parallel to the alignment direction of the liquid crystal molecules in the vicinity of the front substrate 11 of the liquid crystal cell 10. , And the optical sheet 22 is arranged with its reflection axis 22 s oriented in a direction substantially orthogonal to the transmission axis of the polarizing plate 21.

FIG. 2 shows the two substrates 11, 1 of the liquid crystal cell 10.
2 (the alignment films 15 and 1).
6) and the polarizing plate 21
Transmission axis 21a and the reflection axis 22s of the optical sheet 22
And the direction of the transmission axis 22p.

As shown in FIG. 2, the liquid crystal molecule orientation direction 11a in the vicinity of the front substrate 11 of the liquid crystal cell 10 is from the front side (the front side of the liquid crystal display element) with respect to the horizontal axis x of the screen of the liquid crystal display element. The liquid crystal molecule orientation direction 12a in the vicinity of the rear substrate 12 is approximately 45 ° counterclockwise when viewed, and is approximately 45 ° clockwise shifted from the front side with respect to the horizontal axis x. The liquid crystal molecules of the liquid crystal layer 18 of the liquid crystal cell 10 have a twist direction of about 90 ° clockwise from the rear substrate 12 to the front substrate 11 and clockwise as viewed from the front side, as indicated by the dashed arrow in the drawing. And twist-oriented.

The polarizing plate 21 has a transmission axis 2
1a is arranged in a direction deviated counterclockwise by approximately 45 ° with respect to the horizontal axis x from the front side, so that the transmission axis 21a of the polarizing plate 21 is aligned with the front substrate 11 of the liquid crystal cell 10. Is substantially parallel to the liquid crystal molecule alignment direction 11a in the vicinity of.

Further, the optical sheet 22 is arranged such that its reflection axis 22s is displaced approximately 45 ° clockwise with respect to the horizontal axis x when viewed from the front side. The reflection axis 22s of 22 is in a direction substantially orthogonal to the transmission axis 21a of the polarizing plate 21, and the transmission axis 22p is substantially parallel to the transmission axis 21a of the polarizing plate 21.

The liquid crystal display element is driven by controlling the birefringence of the liquid crystal layer 18 by applying a voltage between the electrodes 13 and 14 on both the substrates 11 and 12 of the liquid crystal cell 10, and is driven for display.
The optical sheet 22 for external light incident from the front of the display element
The image is displayed by the specular reflection light of the color plate and the color of the colored plate 23 provided as the rear surface member.

That is, in this liquid crystal display device,
External light incident from the front surface passes through the polarizing plate 21 and the liquid crystal cell 10 in order, and enters the optical sheet 22,
Of the light, the S-polarized light component along the reflection axis 22s of the optical sheet 22 is reflected by the optical sheet 22, and the P-polarized light component p along the transmission axis 22p of the optical sheet 22 passes through the optical sheet. To Penetrate.

The polarization state of the light incident on the optical sheet 22 changes according to the birefringence of the liquid crystal layer 18 which is controlled by applying a voltage.
The ratio between the reflected light intensity and the transmitted light intensity of the light incident on the light source changes.

That is, the birefringence of the liquid crystal layer 18 depends on the initial twist alignment state of the liquid crystal molecules (the liquid crystal molecules are
In the state in which no voltage is applied to the liquid crystal layer in a state where the liquid crystal layer is tilted with the pretilt angles regulated by the alignment films 15 and 16 with respect to the 1st and 12th planes, the liquid crystal molecules maintain the twist alignment state by applying a voltage to the liquid crystal layer. The birefringence decreases as the liquid crystal molecules rise and align at a rising angle corresponding to the applied voltage. When the liquid crystal molecules rise and align almost perpendicularly to the substrates 11 and 12, the birefringence is almost eliminated.

In this embodiment, as shown in FIG. 2, the twist angle of the liquid crystal molecules of the liquid crystal cell 10 is set to approximately 90 degrees.
°, the transmission axis 21a of the polarizing plate 21 is positioned substantially parallel to the liquid crystal molecule orientation direction 11a near the front substrate 11 of the liquid crystal cell 10, and the reflection axis 22s of the optical sheet 22 is set to the transmission axis of the polarizing plate 21. When the liquid crystal molecules are in the initial twist alignment state, the linearly polarized light transmitted through the polarizing plate 21 is substantially orthogonal to the liquid crystal molecules 21a.
In the process of transmitting through the liquid crystal cell 10, the light is rotated by approximately 90 ° due to the birefringence of the liquid crystal layer 18 and is incident on the optical sheet 22 as linearly polarized light along the reflection axis 22s. It is reflected at 22.

Further, when the liquid crystal molecules rise substantially vertically and are aligned (when the birefringence of the liquid crystal layer 18 is almost eliminated), the incident linearly polarized light passes through the liquid crystal cell 10 without being subjected to the optical rotation effect. The optical sheet 22 has its transmission axis 22
The light enters in the state of linearly polarized light along p, and most of the light passes through the optical sheet 22 and enters the colored plate 23 behind it.

Further, when the liquid crystal molecules are aligned obliquely rising while maintaining the twist alignment state, the incident linearly polarized light is different between when the liquid crystal molecules are in the initial twist alignment state and when the liquid crystal molecules are almost vertically rising alignment. , That is, the reflection axis 22s of the optical sheet 22
And a light component including both a polarization component along the transmission axis 22p and the polarization sheet along the transmission axis 22p, and is incident on the optical sheet 22; The light of the polarization component reflected by 22 and transmitted along the transmission axis 22p passes through the optical sheet 22 and enters the colored plate 23.

FIG. 4 is an enlarged sectional view showing a reflection and transmission state of incident light in one pixel region (a region where the segment electrode 14 and the common electrode 13 are opposed) of the liquid crystal display element. When 18a is in the initial twisted state, most of the incident light a is reflected by the optical sheet 22, and the reflected light b is emitted to the front surface of the liquid crystal display element, as shown in FIG.

As described above, the optical sheet 2
Reference numeral 2 denotes a non-colored sheet whose reflection characteristics and transmission characteristics have no wavelength dependency. Therefore, if the incident light a is white light, the reflected light b is also white light.

When the liquid crystal molecules 18a are vertically aligned and vertically aligned, the incident light (white light) a as shown in FIG.
Most of the light passes through the optical sheet 22 and is incident on the colored plate 23. Of the light in the visible light band, light in a wavelength band other than the wavelength band corresponding to the color of the colored plate 23 is absorbed by the colored plate 23, The light in the wavelength band corresponding to the color of the plate 23 is
The colored light c reflected by 3 and colored in the color of the colored plate 23 is emitted to the front surface of the liquid crystal display element.

Further, when the liquid crystal molecules are oriented obliquely rising while maintaining the twisted state, although not shown, the light of the polarization component along the reflection axis 22s of the optical sheet 22 of the incident light is not reflected by the optical sheet 22. The reflected light is emitted to the front surface of the liquid crystal display element, and the light of the polarization component along the transmission axis 22p is transmitted through the optical sheet 22 and the colored plate 23
And is emitted as colored light c colored in the color of the colored plate 23 to the front surface of the liquid crystal display element.

Therefore, when the display of each pixel region of the liquid crystal cell 10 is observed from the front side of the liquid crystal display element, the display of these pixel regions is based on the incident light on the portion of the optical sheet 22 corresponding to the pixel region. When most of the light incident on the optical sheet 22 is light having a polarization component along the reflection axis 22s, the external light is specularly reflected, and most of the incident light is transmitted. When the light is polarized light along the axis 22p, the color of the colored plate 23 provided behind the optical sheet 22 is visible, and the incident light is polarized along the reflection axis 22s and polarized light along the transmission axis 22p. When the light includes both components, both the specular reflected light of the external light and the color of the colored plate 23 appear to be mixed.

The area other than the pixel area is an area where liquid crystal molecules are always in an initial twist alignment state. In this area, incident light is reflected by the optical sheet 22 and mirror light of external light is always reflected. appear.

Therefore, according to the above liquid crystal display device,
In areas other than the pixel area and areas where no voltage is applied in each pixel area, a glossy white background is displayed by the specular reflected light of the external light, and characters or characters colored in the pixel area to which the voltage is applied are displayed. It is possible to display a colored image for displaying a figure or the like, and to change the brightness of the colored display stepwise according to the applied voltage.

The display color of the liquid crystal display element is determined by the color of the colored plate 23. For example, when the colored plate 23 is a red colored plate, characters and figures are displayed in red on a white background. When the colored plate 23 is a gold colored plate, characters, figures, and the like are displayed in gold on a white background.

The color of the colored plate 23 is not limited to the above-mentioned red, green, blue, violet, and gold colors, and may be a black plate that absorbs all light in the visible light band. A white plate that reflects all light may be used. If a black colored plate is used, most of the wavelength light of the light transmitted through the optical sheet 22 is absorbed by the colored plate 23, and a glossy white background is used. Characters and figures are displayed in black inside.

When a white colored plate is used, characters, figures, and the like are displayed in white on a white background. The display is obtained by the reflected light from the colored plate 23. Even in the case of a white plate, each wavelength light is absorbed by the colored plate 23 to some extent, so that the white displayed by the reflected light from the colored plate 23 and the glossy white background have sufficient brightness. Therefore, the display can be sufficiently recognized.

FIG. 5 is a sectional view of a liquid crystal display device according to a second embodiment of the present invention. In this embodiment, the optical sheet 2
A fluorescent member 24 that absorbs light transmitted through the optical sheet 22 and emits fluorescent light of a predetermined color.
The other configuration is the same as that of the first embodiment.

According to the liquid crystal display device of this embodiment, the fluorescent plate 24 absorbs light transmitted through the optical sheet 22 to emit fluorescent light, and the fluorescent light is emitted to the front of the liquid crystal display device. Characters, figures, and the like can be displayed with fluorescent light of a predetermined color on a glossy white background that is displayed by the specular reflected light of the external light reflected by.

FIG. 6 is a sectional view of a liquid crystal display device according to a third embodiment of the present invention. In this embodiment, the optical sheet 2
A plurality of LEs are provided behind a light diffusion plate 26 provided opposite to the rear surface of the optical sheet 22.
LEs in which D (light emitting diodes) 27 are arranged at predetermined intervals
The configuration is the same as that of the first embodiment described above except that the configuration is a D luminous body 25.

FIG. 7 is a sectional view of a liquid crystal display device according to a fourth embodiment of the present invention. In this embodiment, the rear member provided behind the optical sheet 22 is an EL luminous body 28 composed of an EL (electroluminescence) panel, and other configurations are the same as those of the above-described first embodiment.

In the liquid crystal display elements of the third and fourth embodiments, when the LED member 25 or the EL member 28 which is the rear surface member is not turned on, the optical sheet is formed in the same manner as in the first embodiment. In the glossy white background displayed by the specular reflected light of the external light reflected at 22, the color when the LED light-emitting body 25 or the EL light-emitting body 28 is not turned on (the LED light-emitting body 25 or the EL light-emitting body 28). When characters or figures are displayed by the color of the surface reflected light) and the LED luminous body 25 or the EL luminous body 28 is turned on, the reflected light of the external light and the emission of the LED luminous body 25 or the EL luminous body 28 An image is displayed by colors.

According to these liquid crystal display elements, the display of the pixel area where the incident light passes through the optical sheet 22 is performed by the LE.
Since the display is made with the colored light emitted from the D light emitter 25 or the EL light emitter 28, characters, figures, etc., with high brightness colored light are placed in a glossy white background displayed with light reflected by the optical sheet 22. Can be displayed. When the external light is dark or almost nonexistent, the LED
Characters, figures, and the like are displayed by the color of light emitted by the light emitting body 25 or the EL light emitting body 28.

In the liquid crystal display devices of the third and fourth embodiments, the LED luminous body 25 as the rear surface member is used.
Alternatively, a surface light source device including a light source such as an incandescent lamp or a cold cathode tube, a light guide plate, a reflection plate, and a diffusion plate can be used in place of the EL luminous body 28. The same display as the liquid crystal display devices of the third and fourth embodiments can be performed.

FIG. 8 is a sectional view of a liquid crystal display device according to a fifth embodiment of the present invention. In this embodiment, the liquid crystal cell 10
Is a color polarizer 29 of a predetermined color, and the transmission axis of the color polarizer 29 is substantially parallel to the liquid crystal molecule orientation direction 11a near the front substrate 11 of the liquid crystal cell 10. The other configuration is the same as that of the first embodiment.

The liquid crystal display element of this embodiment basically displays an image by the specular reflected light of the external light from the optical sheet 22 and the color of the colored plate 23 as the rear member. Since the polarizer 29 disposed on the front side of the color filter 10 is a color polarizer, the following colored display is possible.

Here, the case where the color polarizing plate 29 is a red polarizing plate and the coloring plate 23 is a black plate will be described. First, the light incident on the liquid crystal cell 10 will be described. The color polarizing plate 29 does not exhibit a polarizing effect on light in the wavelength band of the color, but exerts a polarizing effect only on light in other wavelength bands. For the sake of illustration, when the color polarizer 29 is a red polarizer, light in the red wavelength band of the visible light band is transmitted through the polarizer 29 in a non-polarized state without being substantially polarized, and becomes green. Light in the blue wavelength band is respectively absorbed by light having a polarization component orthogonal to the transmission axis direction of the polarizing plate 29 and becomes linearly polarized light.

Therefore, the red color polarizing plate 29
Of the light that passes through and enters the liquid crystal cell 10, of which light in the red wavelength band (hereinafter, referred to as red light) is unpolarized light, and light in the green and blue wavelength bands (hereinafter, green light and green light). Blue light) is linearly polarized light along the transmission axis of the polarizing plate 29. Since the green light and the blue light are light having only the linearly polarized light component, the light intensity is reduced to approximately half the light intensity of the red light which is the unpolarized light.

The light that has entered the no-voltage application region in which the liquid crystal molecules of the liquid crystal cell 10 are in the initial twist alignment state is rotated by approximately 90 ° by the birefringence of the liquid crystal layer 18 and enters the optical sheet 22.

Therefore, of the light transmitted through the voltage-free area of the liquid crystal cell 10 and incident on the optical sheet 22, green light and blue light are S-polarized light along the reflection axis 22 s of the optical sheet 22. Since the red light includes both the S-polarized light component along the reflection axis 22s of the optical sheet 22 and the P-polarized light component along the transmission axis 22p, most of the green light and the blue light and the red light The S-polarized light component of the light is reflected by the optical sheet 22, and the P-polarized light component of the red light is transmitted through the optical sheet 22. In this example, since the colored plate 23 is a black plate, the P-polarized component red light transmitted through the optical sheet 22 is absorbed by the colored plate 23.

For this reason, the display in the no-voltage application region (the region other than the pixel region and the region where no voltage is applied in the pixel regions) in which the liquid crystal molecules are in the initial twist alignment state is performed by the optical sheet 22. The reflected light is represented by the green light and the S-polarized light of the blue light and the red light. The outgoing light intensities of the red, green, and blue color lights are only S-polarized component light of the incident light to the liquid crystal display element and are substantially equal. There is some white.

Light incident on the voltage application region where the liquid crystal molecules of the liquid crystal cell 10 rise and align substantially vertically passes through the liquid crystal cell 10 without being affected by the birefringence of the liquid crystal layer 18 and enters the optical sheet 22. I do.

Accordingly, of the light transmitted through the voltage application region of the liquid crystal cell 10 and incident on the optical sheet 22, the green light and the blue light are P-polarized light along the transmission axis 22 p of the optical sheet 22. The red light includes the S-polarized component light along the reflection axis 22s of the optical sheet 22 and the transmission axis 22p.
, And most of the green light and the blue light and the light of the P-polarized component of the red light are transmitted through the optical sheet 22 and absorbed by the black colored plate 23. Only the S-polarized light of the red light is reflected by the optical sheet 22.

For this reason, the display of the voltage application region in which the liquid crystal molecules rise almost vertically is aligned with the red light,
It is displayed by the light of the S-polarized light component reflected by the optical sheet 22, so that characters and figures are displayed in red on a glossy white background.

Although the colored plate 23 is a black plate in the above example, the colored plate 23 may be of another color. To give some examples, for example, when the colored plate 23 is a white plate, all the light of each wavelength band transmitted through the optical sheet 22 is reflected by the colored plate 23.

Therefore, the background (display of the no-voltage application region where the liquid crystal molecules are in the initial twist alignment state) is a glossy white light composed of red, green, and blue light reflected by the optical sheet 22. Colored plate 23 transmitted through optical sheet 2
The red light reflected by becomes a glossy red superimposed,
The display in the background (display of the voltage application region where the liquid crystal molecules rise and align) includes the glossy red light reflected by the optical sheet 22, the red light transmitted through the optical sheet 2 and reflected by the colored plate 23, Red light is obtained by superimposing white light composed of green and blue light.

In this example, the background color and the display color are both red, but the white colored plate 23 scatters and absorbs the incident light of each wavelength band, so that the white light reflected by the colored plate 23 is reflected. Is lower than the intensity of the white light reflected by the optical sheet 22. Therefore, the background color is light red with a strong white light intensity, and the display in the background has a weak white light intensity. It is dark red.

Further, the colored plate 23 is replaced with the color polarizing plate 21.
In the case of a red plate having the same color as that of the above, only the red wavelength band light of the light of each wavelength band transmitted through the optical sheet 22 is reflected by the colored plate 23, and the light of other wavelength bands is reflected by the colored plate 23. Absorbed.

For this reason, the background becomes a glossy pale red in which the red light reflected by the colored plate 23 is superimposed on the glossy white light of red, green, and blue light reflected by the optical sheet 22, and The display in the background is rich red in which the red light reflected by the coloring plate 23 is superimposed on the red light reflected by the optical sheet 22.

When the colored plate 23 is a green plate, of the light in each wavelength band transmitted through the optical sheet 22, only the green wavelength band light is reflected by the colored plate 23, and the other wavelength band light is reflected. Light is absorbed by the colored plate 23.

Therefore, the background is changed to white light composed of red, green, and blue light reflected by the optical sheet 22 and the colored plate 23.
The green light reflected from the optical sheet 22 has a superimposed light green color, and the display in the background is yellow in which the green light reflected by the coloring plate 23 is superimposed on the red light reflected by the optical sheet 22.

Further, when the colored plate 23 is a blue plate, of the light of each wavelength band transmitted through the optical sheet 22, only the blue wavelength band light is reflected by the colored plate 23, and the other wavelength band light is reflected. Light is absorbed by the colored plate 23.

Therefore, the background becomes a glossy light blue in which the glossy white light composed of the red, green, and blue lights reflected by the optical sheet 22 and the blue light reflected by the coloring plate 23 are superimposed. The display in the background is purple in which the red light reflected by the optical sheet 22 and the blue light reflected by the colored plate 23 are superimposed.

The above-described display example is based on the color polarizer 2
Although 9 is an example in which a red polarizing plate is used, the color polarizing plate 29 may be a polarizing plate of another color, and a desired combination of the color of the color polarizing plate 29 and the color of the colored plate 23 is obtained. The background color and the display color can be obtained. The colored plate 23 is formed of the fluorescent plate 2 used in the second to fourth embodiments.
4 or an LED luminous body 25 or an EL luminous body 28.

FIG. 9 is a sectional view of a liquid crystal display device according to a sixth embodiment of the present invention. In this embodiment, the liquid crystal cell 10
The non-colored polarizer 21 is a polarizer disposed on the front side of the liquid crystal cell 10. A transparent colored film 30 of a predetermined color is formed on the front side of the liquid crystal cell 10.
Is formed by means such as printing, and the other configuration is the same as that of the first embodiment.

The liquid crystal display element of this embodiment basically displays an image by the mirror reflection of external light from the optical sheet 22 and the color of the colored plate 23 as a rear member. Since the colored film 30 is provided on the front surface of the device 10, the following colored display is possible.

That is, in this liquid crystal display device,
Since the colored film 30 is provided on the front surface of the liquid crystal cell 10, the linearly polarized light colored in the color of the colored film 30
And enters the optical sheet 22. Therefore, the color of the background (display of the no-voltage application region where the liquid crystal molecules are in the initial twist alignment state) displayed by the reflected light from the optical sheet 22 is the glossy color of the color film 30.

The display in the background (display of the voltage application region in which the liquid crystal molecules rise and align) is performed by the optical sheet 2.
2 is displayed in a color corresponding to the spectral intensity distribution of the light reflected by the colored plate 23 among the colored polarized component light transmitted through 2 (polarized component light along the transmission axis 22p of the optical sheet 22).

An example will be described in which the colored film 30 is a red film. When the colored film 30 is a red film, the background color is red, and the color is transmitted through the optical sheet 22 and colored. Light incident on the plate 23 is also red light.

When the colored plate 23 is a black plate, for example, the red light transmitted through the optical sheet 22 and incident on the colored plate 23 is absorbed by the colored plate 23, so that the display in the red background is displayed. Become black.

When the colored plate 23 is a white plate, the red light transmitted through the optical sheet 22 is reflected by the colored plate 23, so that the display in the red background becomes red. The red light reflected by the light 23 is light whose light intensity has been reduced by scattering and absorption at the colored plate 23, and therefore, the red light reflected by the reflected light from the colored plate 23 and the red light reflected by the optical sheet 22. Since the brightness is sufficiently different from the glossy red background displayed by the red light, the display can be sufficiently recognized.

Further, when the colored plate 23 is a red plate having the same color as that of the colored film 30, the display in the red background becomes red. In this case, the red light reflected by the colored plate 23 is used. Is a light whose light intensity has been reduced to some extent by absorption or scattering at the colored plate 23, and further becomes darker red light by the coloring action of the colored plate 23.
3 and the optical sheet 22
The brightness and the density are sufficiently different from the glossy red background displayed by the red light reflected by the, so that the display can be sufficiently recognized.

When the colored plate 23 is a colored plate other than red and other than white and black, for example, a green plate or a blue plate, the red plate transmitted through the optical sheet 22 and incident on the colored plate 23 may be used. Since light is absorbed by the colored plate 23, the display in the red background becomes black.

Although the above-described display example is an example in which the colored film 30 is a red film, the colored film 30 may be a transparent film of another color. 2
By combining the three colors, a desired background color and display color can be obtained.

Further, in the above embodiment, the colored film 30 is provided on the front surface of the liquid crystal cell 10, but the colored film 30 may be provided on any one of the front and rear surfaces of the liquid crystal cell 10.
In addition, the colored plate 23 as a rear member is the same as the fluorescent plate 2 described above.
4 or an LED luminous body 25 or an EL luminous body 28.

In the liquid crystal display devices of the first to fifth embodiments described above, the transmission axes 21a of the polarizing plates 21 and 29 are aligned with the alignment direction 11a of the liquid crystal molecules near the front substrate 11 of the liquid crystal cell 10. Although the polarizing plates 21 and 29 are arranged in a direction substantially orthogonal to each other, the polarizing plates 21 and 29 have their transmission axes 21a.
To the liquid crystal molecule orientation direction 11 near the front substrate 11.
may be arranged in a direction substantially parallel to the direction a. In this case, the color of the background (display of the voltage-free area where the liquid crystal molecules are in the initial twist alignment state) and the display in the background (the liquid crystal molecules are The display color of the voltage application area in the rising orientation) is opposite to the display color in the first to fifth embodiments.

Further, the optical sheet 22 has its reflection axis 2
2s may be arranged in a direction substantially parallel to the transmission axis 21a of the polarizing plates 21 and 29. In this case, the color of the background and the color of the display in the background are changed from the first to the second. The display color is opposite to that of the fifth embodiment.

In the liquid crystal display devices of the first to fifth embodiments, the polarizing plates 21 and 29 are arranged such that their transmission axes 21a are oriented with respect to the liquid crystal molecule orientation direction 11a near the front substrate 11 of the liquid crystal cell 10. Although it is a TN type operation mode arranged in a direction substantially orthogonal or substantially parallel, the present invention can be applied to a liquid crystal display element of an STN type or ECB type operation mode, for example.

FIG. 10 shows a seventh embodiment of the present invention, in which the alignment directions 11a and 12a of liquid crystal molecules near both substrates 11 and 12 of the liquid crystal cell 10, the transmission axis 21a of the polarizing plate 21, and FIG. 3 is a diagram showing the directions of a reflection axis 22s and a transmission axis 22p of the optical sheet 22, and this embodiment is an example applied to an ECB type liquid crystal display device.

This liquid crystal display element uses a non-colored polarizing plate 21, and the transmission axis 21 a of the polarizing plate 21 is aligned with the liquid crystal molecule orientation direction 11 near the front substrate 11 of the liquid crystal cell 10.
a of the liquid crystal cell 1 in a direction obliquely intersecting
In addition to the optical sheet 22 having the above-described characteristics, the reflection axis 22s is oriented in a direction substantially orthogonal to or substantially parallel to the transmission axis 21a of the polarizing plate 21 on the rear side of the liquid crystal cell 10 while being disposed on the front side of the liquid crystal cell 10. Although not shown, a colored plate is provided as a rear member behind the optical sheet 22.

In this embodiment, as shown in FIG.
As the liquid crystal cell 10, a liquid crystal cell 10 in which the liquid crystal molecule orientation directions 11a and 12a near the two substrates 11 and 12 are set to be the same as in the first embodiment and the twist angle of the liquid crystal molecules is approximately 90 ° is used. The polarizing plate 21 is moved to its transmission axis 2
1a is directed in a direction (direction substantially parallel to the horizontal axis x of the screen of the liquid crystal display element) which is displaced from the liquid crystal molecule orientation direction 11a in the vicinity of the front substrate 11 of the liquid crystal cell 10 by approximately 45 ° in the twist direction of the liquid crystal molecules. The optical sheet 22
To the transmission axis 21a of the polarizing plate 21
It is arranged in a direction substantially orthogonal to.

The liquid crystal display device of this embodiment basically displays an image by the mirror reflection of external light from the optical sheet 22 and the color of a colored plate (not shown) provided as a rear member. The polarizing plate 21 has its transmission axis 2
Since 1a is arranged in a direction obliquely intersecting with the liquid crystal molecule orientation direction 11a in the vicinity of the front substrate 11 of the liquid crystal cell 10, the following colored display is possible.

That is, in this liquid crystal display device,
The transmission axis 21a of the polarizing plate 21 is
, The liquid crystal cell 10 is obliquely shifted with respect to the liquid crystal molecule alignment direction 11a, so that when the liquid crystal molecules are in the twist alignment state, the linearly polarized light transmitted through the polarizing plate 21 and incident on the liquid crystal cell 10 In the process of transmission, the liquid crystal layer 1
Due to the birefringence of No. 8, each wavelength light becomes a light in a different polarization state (elliptically polarized light, circularly polarized light, or linearly polarized light whose vibration plane is rotated), and the light is converted to the optical sheet 22.
Incident on.

The optical sheet 22 reflects the incident light of the polarized light component along the reflection axis 22s and transmits the incident light of the polarized light component along the transmission axis 22p. Since the light is polarized light as described above, the light reflected by the optical sheet 22 is:
The light intensity for each wavelength light in the visible light band is different from each other, and the light transmitted through the optical sheet 22 is also the light having different light intensity for each wavelength light in the visible light band.

Therefore, the light reflected by the optical sheet 22 is colored light having a color according to the spectral intensity distribution of the light, and the light transmitted through the optical sheet 22 is also a color light according to the spectral intensity distribution. It is colored light.

The color of the reflected light and the color of the transmitted light have a complementary color relationship with each other.
d (the product of the birefringence Δn of the liquid crystal and the thickness d of the liquid crystal layer), the twist angle of the liquid crystal molecules, the direction of the transmission axis 21 a of the polarizing plate 21, the reflection axis 22 s and the transmission axis 22 of the optical sheet 22.
It depends on the direction of p.

The color of the reflected light and the color of the transmitted light change as the liquid crystal molecules rise and align while maintaining the twisted state by applying a voltage between the electrodes of the liquid crystal cell 10.

In this embodiment, the optical sheet 2
2, the direction of the reflection axis 22s and the direction of the transmission axis 22p
Is almost parallel to the direction substantially perpendicular to the transmission axis 21 a of the liquid crystal cell 10, the liquid crystal molecules of the liquid crystal cell 10 rise and align almost vertically, the birefringence of the liquid crystal layer is almost eliminated, and the light has passed through the polarizing plate 21. When the linearly polarized light passes through the liquid crystal cell 10 and hardly changes the polarization state and enters the optical sheet 22, the reflected light and the transmitted light become uncolored light (white light). Is reflected by the liquid crystal display element, and the light transmitted through the optical sheet 22 is absorbed or reflected in accordance with the color of the colored plate behind it.

That is, for example, when the colored plate is black, all the wavelength light transmitted through the optical sheet 22 is absorbed, and when the colored plate is white, the wavelength light transmitted through the optical sheet 22 is absorbed. Everything is reflected. When the colored plate is of another color, the light of the wavelength band of the color of the colored plate of the wavelength light transmitted through the optical sheet 22 is reflected, and the light of the other wavelength band is absorbed.

Therefore, when the colored plate is black, the background is displayed by the light reflected by the optical sheet 22 when the liquid crystal molecules are in the initial twisted state, and the display in the background is displayed by the liquid crystal molecules. Are displayed by the specular reflection light from the optical sheet 22 when the light is oriented upward.

When the colored plate is white or another color, the background transmits the light reflected by the optical sheet 22 when the liquid crystal molecules are in the initial twisted state. The light reflected by the colored plate is displayed in a superimposed color, and the display in the background is colored by transmitting the light reflected by the optical sheet 22 when the liquid crystal molecules rise and align through the optical sheet 22. The light reflected by the plate is displayed in a superimposed color.

In this embodiment, a colored plate is used as a rear member. However, the rear member may be a fluorescent plate, a light-emitting member such as an LED light-emitting member or an EL light-emitting member. However, the light reflected by the optical sheet 22 when the liquid crystal molecules are in the initial twisted state is displayed in a color in which the light emitted from the fluorescent plate or the luminous body is superimposed, and the display in the background is such that the liquid crystal molecules are aligned in the rising orientation The light reflected by the optical sheet 22 at this time is displayed in a color in which the light emitted from the fluorescent plate or the luminous body is superimposed.

Further, in the above embodiment, the liquid crystal cell 10
In this case, the liquid crystal molecules are twisted at a twist angle of about 90 °, but in the case of an ECB type liquid crystal display element, the liquid crystal cell 10 is twisted at another twist angle. Or an alignment state other than the twist alignment state such as a homogeneous alignment state.

FIG. 11 and FIG. 12 show an eighth embodiment of the present invention. This embodiment is an example applied to an STN type liquid crystal display device. FIG. 11 is a cross-sectional view of a liquid crystal display device. In the liquid crystal display device of this embodiment, the liquid crystal molecules 10 are polarized on the front side of a liquid crystal cell 10 having a liquid crystal layer 18 in which the liquid crystal layer 18 is twisted at a twist angle of 180 ° to 270 °. A plate 21 is arranged, and an optical sheet 22 is arranged on the rear surface side of the liquid crystal cell 10. A scattering reflector 31 is provided as a rear member behind the optical sheet 22. A phase difference plate 32 for color compensation is provided between the polarizing plate 21 and the polarizing plate 21.

Note that the liquid crystal cell 10 used in this embodiment was
Although the twist angle of the liquid crystal molecules 10 is different, the other configuration is the same as that used in each of the above-described embodiments.

The polarizing plate 21 is a non-colored polarizing plate, and the scattering reflector 31 is a colored reflector that reflects light in a predetermined wavelength band of the visible light band and absorbs light in another wavelength band. It is.

FIG. 12 shows both substrates 1 of the liquid crystal cell 10.
Orientation directions 11a, 1 of liquid crystal molecules in the vicinity of
2A, the transmission axis 21a of the polarizing plate 21, the slow axis 32a of the retardation plate 32, and the directions of the reflection axis 22s and the transmission axis 22p of the optical sheet 22.

In this embodiment, as shown in FIG. 12, the liquid crystal molecule orientation direction 11a in the vicinity of the front substrate 11 of the liquid crystal cell 10 is set in front of the horizontal axis x of the screen of the liquid crystal display device. 30 ° clockwise when viewed from the front) side
The shifted direction, the liquid crystal molecule alignment direction 12a in the vicinity of the rear substrate 12 is set to a direction shifted approximately 30 ° counterclockwise as viewed from the front side with respect to the horizontal axis x.
The liquid crystal molecules of the liquid crystal layer 18 of the liquid crystal cell 10 have a twist direction from the rear substrate 12 to the front substrate 11 as shown by the broken arrow in the figure, and approximately two clockwise as viewed from the front.
It is twist-oriented at a twist angle of 40 °.

The polarizing plate 21 has its transmission axis 2
1a is disposed in a direction deviated substantially 100 ° counterclockwise with respect to the horizontal axis x from the front side, and the retardation plate 32 has its slow axis 32a Are arranged in a direction deviated approximately 50 ° counterclockwise when viewed from the front side.

That is, the transmission axis 21a of the polarizing plate 21
Is approximately 130 ° counterclockwise as viewed from the front side with respect to the liquid crystal molecule alignment direction 11 a in the vicinity of the front substrate 11 of the liquid crystal cell 10.
a is deviated clockwise approximately 80 ° from the transmission axis 21a of the polarizing plate 21 when viewed from the front side.

Further, the optical sheet 22 is arranged so that its reflection axis 22s is displaced clockwise by about 20 ° with respect to the horizontal axis x when viewed from the front side. That is, the reflection axis 22s of the optical sheet 22 is displaced approximately 120 ° clockwise from the transmission axis 21a of the polarizing plate 21 when viewed from the front side, and the transmission axis 22p is
One transmission axis 21a is displaced clockwise by approximately 30 ° from the front side.

In the liquid crystal display device of this embodiment, basically, an image is formed by the specular reflection light of the external light from the optical sheet 22 and the color of the scattering reflection plate 31 (color of the reflection light) provided as a rear member. For display, the liquid crystal display element 1
The liquid crystal molecules having a twist angle of 180 ° to 270 ° (FIG. 1)
2 is almost 240 °), the change in the light transmittance with respect to the change in the alignment state of the liquid crystal molecules due to the application of a voltage is steep, and therefore, the twist of the liquid crystal molecules of the liquid crystal cell 10 Compared to the TN type having an angle of about 90 °, time-division driving with a higher duty is possible, and a larger screen can be achieved.

Further, in this embodiment, the phase difference plate 3 is provided between the front surface of the liquid crystal display device 10 and the polarizing plate 21.
2, the display band color which is a problem in the STN type liquid crystal display element can be almost eliminated.

That is, when the phase difference plate 32 is not provided,
In the STN type liquid crystal display device as in this embodiment, since the transmission axis 21a of the polarizing plate 21 is obliquely shifted with respect to the liquid crystal molecule orientation direction 11a in the vicinity of the front substrate 11 of the liquid crystal cell 10, the polarizing plate In the process of passing through the liquid crystal cell 10, the linearly polarized light that has passed through the liquid crystal 21 becomes elliptically polarized light in which each wavelength light has a different polarization state due to the birefringence of the liquid crystal layer 18. The light enters the sheet 22.

The optical sheet 22 reflects the incident light of the polarized light component along the reflection axis 22s and transmits the incident light of the polarized light component along the transmission axis 22p. Since the light is in the above-mentioned polarization state, the light reflected by the optical sheet 22 is also
The light transmitted through the optical sheet 22 also has a different light intensity for each wavelength light in the visible light band, and is colored in a color according to the spectral intensity distribution of the light. The light transmitted through the optical sheet 22 is absorbed or reflected according to the color of the scattering reflector 31 behind it.

Therefore, when there is no phase difference plate 32, ST
In an N-type liquid crystal display device, light emitted to the front of the liquid crystal display device is colored light having a certain color, and it is difficult to obtain good black and white display.

However, in this embodiment, the phase difference plate 3 is provided between the front surface of the liquid crystal display device 10 and the polarizing plate 21.
2, the coloring of the light is compensated for by the birefringence of the retardation plate 32, and the band color of the display can be almost eliminated.

For example, as described above, the twist angle of the liquid crystal molecules of the liquid crystal cell 10 is set to approximately 240 °, and the orientation directions 11a and 12a of the liquid crystal molecules in the vicinity of both the substrates 11 and 12 of the liquid crystal cell 10 are FIG. 12 shows the transmission axis 21 a of the polarizing plate 21, the slow axis 32 a of the phase difference plate 32, and the directions of the reflection axis 22 s and the transmission axis 22 p of the optical sheet 22.
In the case of setting as follows, the retardation value Re of the retardation plate 32 that can effectively eliminate the banding of the display is, for example, the value of Δnd of the liquid crystal cell 10 is Δnd = about 850 nm
In this case, Re = about 570 nm.

Further, the STN type liquid crystal display element of this embodiment displays a glossy background by the specular reflection light of the external light from the optical sheet 22. Talk is less noticeable in a shiny background, and good display quality is obtained.

In the eighth embodiment, the colored scattering reflector 31 is used for the rear member disposed behind the optical sheet 22. However, the scattering reflector 31 is used for all the visible light bands. A white scattering reflector that reflects light may be used. Even in this case, the brightness of the scattered light reflected by the white scattering reflector and the specular reflection light of the optical sheet 22 are sufficiently different. Therefore, the display can be sufficiently recognized.

Further, the rear member is made of red, green, blue, purple, or the like, similar to the colored plate 23 used in the first embodiment.
It may be a gold or black or white colored plate, or may be a fluorescent plate, or a luminous body such as an LED luminous body or an EL luminous body.

As in the first to eighth embodiments described above, the liquid crystal display element of the present invention has a reflection axis 22s and a transmission axis 22p in directions substantially orthogonal to each other, and the reflection axis 22s
Incident light of a polarization component along the transmission axis 22 is reflected.
An optical sheet 22 having a property of transmitting incident light of a polarization component along p is provided. Specular reflected light of external light by the optical sheet 22 and a rear member (a light absorbing plate such as a colored plate 23,
It is a novel display method of displaying an image by a light emitting body such as the fluorescent plate 24, the LED light emitting body 25 or the EL light emitting body 28, or the color of the scattering reflector 31).
According to this liquid crystal display device, the electrodes 13 of the liquid crystal cell 10,
By controlling the birefringence of the liquid crystal layer 18 by applying a voltage between the light-receiving layers 14 and changing the polarization state of light incident on portions of the optical sheet 22 corresponding to the respective pixel regions, the conventional display device has An image of a new observation feeling that cannot be obtained can be displayed.

In the liquid crystal display device of the present invention, the optical sheet 22 is used for obtaining glossy specular reflection light, but the optical sheet 22 is also used for other liquid crystal display devices. can do.

FIGS. 13 and 14 show an example of a liquid crystal display device using the optical sheet 22. Here, FIG.
1 shows a TN-type reflective liquid crystal display device including two ordinary polarizing plates.

FIG. 13 is a cross-sectional view of a liquid crystal display element. This liquid crystal display element has a liquid crystal cell 1 having a liquid crystal layer 18 in which liquid crystal molecules 10 are twisted at a twist angle of about 90 °.
0, a pair of front and rear polarizers (both uncolored polarizers) 41 and 42 interposed between the liquid crystal cells 10, and an optical sheet 22 disposed on the rear side of the rear polarizer 42. And a reflection plate 43 disposed behind the optical sheet 22.

The liquid crystal cell 10 has the same structure as that used in the liquid crystal display device of the first embodiment, and the optical sheet 22 is the same as that used in each of the above embodiments. Since they are the same, the same description will be given the same reference numerals in the drawings and will be omitted.

The reflection plate 43 is used to eliminate the so-called reflection of the outside scene, which is the appearance of the display observer's face and its background on the reflection surface, and to increase the viewing angle of the display. A scattering reflector is used. This scattering reflection plate is a non-colored reflection plate obtained by roughening a metal film having a high reflectance such as aluminum.

FIG. 14 shows both substrates 1 of the liquid crystal cell 10.
Orientation directions 11a, 1 of liquid crystal molecules in the vicinity of
2a and transmission axes 41a, 42 of a pair of polarizing plates 41, 42.
a, the reflection axis 22s and the transmission axis 22p of the optical sheet 22
FIG.

As shown in FIG. 14, the liquid crystal molecule orientation direction 11a in the vicinity of the front substrate 11 of the liquid crystal cell 10 is:
The direction deviated approximately 45 ° counterclockwise from the front side with respect to the horizontal axis x of the screen of the liquid crystal display element, and the liquid crystal molecule orientation direction 12a near the rear substrate 12 is from the front side with respect to the horizontal axis x. The liquid crystal molecules in the liquid crystal layer 18 of the liquid crystal cell 10 are directed from the rear substrate 12 to the front substrate 11 in the twist direction as indicated by the broken arrows in the figure. , Almost 90 ° clockwise when viewed from the front
At a twist angle of.

The front polarizing plate 41 of the pair of polarizing plates 41, 42 has its transmission axis 41a set to the horizontal axis x.
The rear polarizing plate 42 is disposed so as to face a direction deviated substantially 45 ° counterclockwise when viewed from the front side.
a is approximately 4 clockwise with respect to the horizontal axis x when viewed from the front side.
They are arranged in a direction shifted by 5 °.

That is, this liquid crystal display element is of a display system generally called a normally white mode in which a pair of polarizing plates 41 and 42 are arranged with their transmission axes 41a and 42a substantially orthogonal to each other.

In this liquid crystal display device, the optical sheet 22 is disposed so that the transmission axis 22p thereof is oriented clockwise by approximately 45 ° with respect to the horizontal axis x when viewed from the front side. Therefore, the transmission axis 22p of the optical sheet 22 is substantially parallel to the transmission axis 42a of the rear polarizing plate 42, and the reflection axis 22s is substantially orthogonal to the transmission axis 42a of the rear polarizing plate 42.

In this liquid crystal display element, external light incident from the front side is reflected by the scattering reflection plate 43 on the rear side to perform a reflection type display. The light is transmitted, becomes linearly polarized light, and enters the liquid crystal cell 10.

Then, both substrates 11 and 12 of the liquid crystal cell 10 are
When no voltage is applied between the electrodes 13 and 14, ie, when the liquid crystal molecules are in the initial twisted state (when the liquid crystal molecules are
1 and 12), the linearly polarized light incident on the liquid crystal cell 10 from the front surface thereof is applied to the liquid crystal layer 1.
The liquid crystal cell 10 is rotated about 90 ° by the birefringence of
The light exits from the rear surface, passes through the rear polarizing plate 42, and enters the optical sheet 22.

Since the transmission axis 42a of the rear polarizing plate 42 and the transmission axis 22p of the optical sheet 22 are substantially parallel to each other, most of the light transmitted through the rear polarizing plate 42 is almost parallel to the optical sheet 22. 22, is reflected by a scattering reflector 43 behind it, and the reflected light is transmitted through the optical sheet 22, the rear polarizer 42, the liquid crystal cell 10, and the front polarizer 41.
Are sequentially transmitted and emitted to the front of the liquid crystal display element, and the display in that area becomes bright.

At this time, since the light reflected by the scattering reflector 43 is scattered light, the reflected light includes
There is also light having a component along the reflection axis 22s of the optical sheet 22, and the light does not pass through the optical sheet 22.

However, the light is reflected by the rear surface of the optical sheet 22 and is again scattered and reflected by the scattering reflector 43. Therefore, the light is repeatedly reflected between the scattering reflector 43 and the rear surface of the optical sheet 22. The direction is changed, and eventually the light becomes a component light along the transmission axis 22p of the optical sheet 22 and enters the optical sheet 22. Therefore, most of the light incident on the scattering reflection plate 43 and scattered and reflected passes through the optical sheet 22 and exits to the front surface thereof.

The transmission axis 22p of the optical sheet 22
And the transmission axis 42a of the rear polarizing plate 42 are substantially parallel, so that most of the reflected light transmitted through the optical sheet 22 passes through the rear polarizing plate 42, and the liquid crystal cell 10 and the front polarizing plate 41 In order to be emitted to the front of the liquid crystal display element.

Therefore, when the liquid crystal molecules are in the initial twist alignment state, they are incident on the liquid crystal display element from the front surface and sequentially pass through the front polarizing plate 41, the liquid crystal cell 10, the rear polarizing plate 42, and the optical sheet 22. Then, the light reflected by the scattering reflection plate 43 passes through the optical sheet 22 and the rear polarizing plate 42 again and causes the liquid crystal cell 10 to enter the liquid crystal cell 10 from the rear surface with almost no loss. Since the light passes through the polarizing plate 41 and is emitted to the front of the liquid crystal display element, the reflected light can be emitted with high efficiency, and a bright display with sufficient brightness can be obtained.

On the other hand, when the voltage is applied between the electrodes 13 and 14 of the two substrates 11 and 12 of the liquid crystal cell 10 to cause the liquid crystal molecules to rise almost vertically and align (when the birefringence of the liquid crystal layer 18 is almost eliminated). Indicates that the linearly polarized light incident on the liquid crystal cell 10 from its front surface is not affected by the optical rotation effect,
0 is transmitted to the rear-side polarizing plate 42, and most of the light is absorbed by the rear-side polarizing plate 42, and the display in that region becomes a dark display (black).

As described above, the reflection type liquid crystal display device has
By using the optical sheet 22, the light reflected by the scattering reflector 43 is emitted with high efficiency, and a voltage non-applied region (a region where liquid crystal molecules are in an initial twist alignment state).
Is sufficiently bright, and characters and figures are displayed by absorbing light by the rear polarizer 42 in the voltage application region in a bright background. According to this liquid crystal display device, As compared with the reflection type liquid crystal display element, a display with a brighter screen and a higher contrast can be obtained.

That is, the conventional reflection type display element has a configuration in which a pair of front and rear polarizing plates are arranged with a liquid crystal cell interposed therebetween, and a scattering reflection plate is arranged on the rear surface side of the rear polarizing plate. However, in this liquid crystal display device, the efficiency of emitting reflected light from the scattering reflector is poor, and a bright display with sufficient brightness cannot be obtained.

This is because the light reflected by the scattering reflector is scattered light, and among the reflected light, there is light having a component along the absorption axis of the rear polarizing plate. This is because the light is absorbed by the side polarizing plate.

On the other hand, the reflection type liquid crystal display element has a reflection axis 22s and a transmission axis 22p between the rear polarizer 42 and the scattering reflector 43 in directions substantially orthogonal to each other. The optical sheet 22 having the characteristic of reflecting incident light of the polarization component along the axis 22s and transmitting the incident light of the polarization component along the transmission axis 22p is connected to the transmission axis 2
2p is disposed substantially parallel to the transmission axis 42a of the rear polarizing plate 42, and most of the light transmitted through the rear polarizing plate 42 among the light incident from the front side of the liquid crystal display element is the same as that of FIG. The scattered reflection plate 43 transmitted through the optical sheet 22
Therefore, the incident rate of external light incident on the liquid crystal display element from the front surface thereof to the scattering reflector 43 is almost the same as that of the conventional liquid crystal display element.

In this liquid crystal display device, of the scattered reflected light reflected by the scattered reflected light, light having a component along the transmission axis 22p of the optical sheet 22 passes through the optical sheet 22 as it is. The light of the component along the reflection axis 22s is transmitted through the transmission axis 22 of the optical sheet 22 by repeating the reflection between the optical sheet 22 and the scattering reflector 43.
In addition to passing through the optical sheet 22 as light having a component along p, most of the reflected light that has passed through the optical sheet 22 passes through the rear polarizer 42, and the liquid crystal cell 10
And the light passes through the front polarizing plate 41 in order and is emitted to the front surface of the liquid crystal display element.

Therefore, in this liquid crystal display device, the emission efficiency of the light reflected by the scattering reflector 43 is much higher than that of the conventional liquid crystal display device, and a display with a bright screen and high contrast can be obtained.

The above liquid crystal display element is of a display system called a normally white mode. A pair of polarizing plates sandwiching a liquid crystal cell are arranged with their transmission axes substantially parallel to each other. Also in a reflective liquid crystal display element of a display system called a normally black mode, the optical sheet 22 is disposed between the rear polarizing plate and the scattering reflector, and the transmission axis 22p of the optical sheet 22 is set to the transmission axis of the rear polarizing plate. If they are arranged almost in parallel, reflected light can be emitted with high efficiency, and a display with a bright screen and high contrast can be obtained.

The liquid crystal display element is of the TN type, and a pair of polarizing plates is formed by sandwiching a pair of polarizing plates between liquid crystal cells in which liquid crystal molecules are twisted at a twist angle of, for example, 180 ° to 270 °. Also arranged in a predetermined direction, even in the STN-type reflective liquid crystal display element in which a scattering reflector is arranged on the rear side of the rear polarizing plate, between the rear polarizing plate and the scattering reflector, If the optical sheet 22 is disposed with its transmission axis 22p substantially parallel to the transmission axis of the rear polarizing plate, the reflected light can be emitted with high efficiency, and a bright screen and high contrast display can be obtained. Can be.

In the reflection type liquid crystal display device,
If the intensity of the reflected light emitted to the front surface is too high and the display looks glaring, for example, the front surface of the front polarizing plate is roughened, or a light scattering sheet is arranged on the front surface, and the display is glazed. What is necessary is just to suppress sticking.

This is also true of the liquid crystal display devices of the above-described embodiments of the present invention. In the case of the liquid crystal display devices of these embodiments, the specular reflected light of the external light by the optical sheet 22 is reflected on the front surface. However, if the front surface of the front polarizing plate 21 is roughened or a light scattering sheet is arranged on the front surface, the display glare is suppressed. be able to.

The liquid crystal display device of the present invention can be widely used for various electronic devices such as an electronic wristwatch, an electronic clock, a calculator, an electronic organizer, a mobile phone, a desk phone, a notebook personal computer, and a portable small personal computer.

Further, the liquid crystal display device of each of the above embodiments has a T
Any of N type, STN type, ECB type
The present invention relates to a liquid crystal display using a liquid crystal cell in which a liquid crystal layer whose birefringence changes according to a voltage applied between electrodes is sandwiched between substrates, such as a device using a ferroelectric liquid crystal or an antiferroelectric liquid crystal. It can be widely applied to devices.

In addition, the liquid crystal cell 10 used in each of the above embodiments was used.
Is a segment display type.
0 may be a dot matrix liquid crystal cell of a simple matrix type or an active matrix type. In this case, the color of each display pixel is changed to the above-described background color and the display color in the background, and each pixel area of the liquid crystal cell is changed. By changing the display color by controlling the voltage applied to the display device, a colored image having a gradation can be displayed.

[0159]

According to the liquid crystal display device of the present invention, a polarizing plate is disposed on the front side of a liquid crystal cell sandwiching a liquid crystal layer whose birefringence changes in accordance with a voltage, and substantially behind each other on the rear side of the liquid crystal cell. An optical sheet having a reflection axis and a transmission axis in a direction orthogonal to each other, reflecting incident light of a polarization component along the reflection axis, and having a property of transmitting incident light of a polarization component along the transmission axis is disposed. With, behind this optical sheet,
A rear surface member of a predetermined color is provided, and an image is displayed by the mirror reflection light of the external light by the optical sheet and the color exhibited by the rear surface member, so that it cannot be obtained by a conventional display element. An image with a new observation feeling can be displayed.

In the liquid crystal display device according to the present invention, the rear member may be, for example, a scattering reflector or a light absorbing plate, a fluorescent plate that absorbs incident light and emits fluorescent light of a predetermined color, or has a predetermined spectral intensity distribution. In other words, if the light-emitting body that emits light has a color different from the specular reflection light by the optical sheet, an image is displayed by the reflected light of the external light and the color presented by the colored plate. be able to.

If the rear member is a fluorescent plate that absorbs light transmitted through the optical sheet and emits fluorescent light of a predetermined color or a light emitter that emits colored light of a predetermined color, the color of the rear member can be improved. Can be used to brighten the display.

If the polarizing plate is a color polarizing plate of a predetermined color, or if a colored transparent film of a predetermined color is provided on one of the front and rear surfaces of the liquid crystal cell, the light is reflected by the optical sheet. The light can be colored light.

Further, in the liquid crystal display device according to the present invention, the liquid crystal cell in which liquid crystal molecules of a liquid crystal layer are twisted between a pair of substrates is used, and the polarizing plate is connected to the liquid crystal cell. The optical sheet is arranged in a direction substantially parallel or substantially perpendicular to the orientation direction of the liquid crystal molecules in the vicinity of the front substrate, and the reflection axis of the optical sheet is oriented in a direction substantially parallel or substantially perpendicular to the transmission axis of the polarizing plate. With such arrangement, it is possible to display white and black or a color in which the color of the rear surface member is superimposed on white, depending on the combination with the color of the rear surface member.

Further, a liquid crystal cell in which liquid crystal molecules of a liquid crystal layer are twist-oriented between a pair of substrates is used, and the polarizing plate has a transmission axis near the front substrate of the liquid crystal cell. May be arranged in a direction obliquely intersecting the alignment direction of the optical sheet, and the optical sheet may be arranged with its reflection axis oriented in a direction substantially parallel to or substantially orthogonal to the transmission axis of the polarizing plate.

As an example, there are STN-type and ECB-type liquid crystal display devices. For example, in the case of an ECB-type liquid crystal display device, light reflected by the optical sheet and light transmitted through the optical sheet are used. Colored light can be displayed by using the reflected light and the transmitted light, respectively, and the color of the rear surface member.

In the case of, for example, an STN type liquid crystal display device, the twist angle of liquid crystal molecules between a pair of substrates of the liquid crystal cell is preferably in the range of 180 ° to 270 °. It is desirable to provide a retardation plate for color compensation between the plate and the plate.

In the case of this STN type liquid crystal display device, time-division driving with a higher duty is possible as compared with the TN type liquid crystal display device in which the twist angle of liquid crystal molecules is almost 90 °, and a large screen is required. In addition to the above, it is possible to eliminate the banding of the display by providing the banding compensation phase difference plate.

The STN type liquid crystal display element has
Since the glossy background is displayed by the specular reflection light of the external light from the optical sheet, crosstalk hardly occurs in the glossy background even when driven in a high time division manner.

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the orientation directions of liquid crystal molecules in the vicinity of both substrates of a liquid crystal cell, the transmission axis of a polarizing plate, and the directions of the reflection axis and the transmission axis of an optical sheet in the liquid crystal display device of the first embodiment.

FIG. 3 is a perspective view of an optical sheet 22.

FIG. 4 is an enlarged sectional view showing a reflection and transmission state of incident light in one pixel region of the liquid crystal display element of the first embodiment.

FIG. 5 is a sectional view of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 7 is a sectional view of a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view of a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 9 is a sectional view of a liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 10 is a view showing an orientation direction of liquid crystal molecules near both substrates of a liquid crystal cell, a transmission axis of a polarizing plate, and directions of a reflection axis and a transmission axis of an optical sheet according to a seventh embodiment of the present invention. .

FIG. 11 is a sectional view of a liquid crystal display device according to an eighth embodiment of the present invention.

FIG. 12 is a view illustrating an alignment direction of liquid crystal molecules in the vicinity of both substrates of a liquid crystal cell, a transmission axis of a polarizing plate, a slow axis of a retardation plate, and a reflection axis of an optical sheet in a liquid crystal display device according to an eighth embodiment. FIG. 3 is a diagram showing directions of transmission axes.

FIG. 13 is a cross-sectional view of a reflection type liquid crystal display device using the optical sheet, showing another application example of the optical sheet used in the present invention.

FIG. 14 shows the orientation directions of liquid crystal molecules near both substrates of a liquid crystal cell in the reflective liquid crystal display device shown in FIG.
FIG. 5 is a diagram illustrating the directions of a transmission axis of a pair of polarizing plates and a reflection axis and a transmission axis of an optical sheet.

[Explanation of symbols]

 Reference Signs List 10: liquid crystal cell 11a: alignment direction of liquid crystal molecules near the front substrate 12b: alignment direction of liquid crystal molecules near the rear substrate 18: liquid crystal layer 21: polarizing plate 21a: transmission axis 22: optical sheet 22s: reflection axis 22p Transmission axis 23: Colored plate (rear member) 24: Fluorescent plate (rear member) 25: LED light emitter (rear member) 28: EL light emitter (rear member) 29: Color polarizing plate 30: Colored film 31: Scattering reflector ( Rear member)

Claims (11)

[Claims] 1. A liquid crystal cell having a liquid crystal layer whose birefringence changes according to a voltage applied between said electrodes between a pair of front and rear substrates having electrodes formed on respective surfaces facing each other. A polarizing plate disposed on the front surface side of the liquid crystal cell, and disposed on the rear surface side of the liquid crystal cell, having a reflection axis and a transmission axis in directions substantially orthogonal to each other, and incident light of a polarization component along the reflection axis. A liquid crystal display device comprising: an optical sheet having a characteristic of reflecting and transmitting incident light of a polarization component along the transmission axis; and a rear member provided behind the optical sheet. 2. A liquid crystal display device according to claim 1, wherein said rear surface member is a scattering reflector for scattering and reflecting incident light. 3. The liquid crystal display device according to claim 1, wherein said rear member is a light absorbing plate. 4. The liquid crystal display device according to claim 3, wherein the light absorbing plate is a colored plate that absorbs light in a predetermined wavelength band. 5. The liquid crystal display device according to claim 1, wherein the rear surface member is a fluorescent plate that absorbs incident light and emits fluorescent light of a predetermined color. 6. The light-emitting device according to claim 1, wherein the rear surface member is a luminous body that emits light having a predetermined spectral intensity distribution.
3. The liquid crystal display device according to item 1. 7. The liquid crystal layer of the liquid crystal cell has liquid crystal molecules in a twisted orientation between the pair of substrates, and the polarizing plate has a transmission axis whose direction is aligned with the orientation direction of the liquid crystal molecules in the vicinity of the front substrate of the liquid crystal cell. 2. The optical sheet according to claim 1, wherein the optical sheet is oriented in a direction substantially orthogonal or substantially parallel to the transmission axis of the polarizing plate. 3. The liquid crystal display device according to item 1. 8. The liquid crystal layer of the liquid crystal cell has liquid crystal molecules in a twisted orientation between the pair of substrates, and the polarizing plate has a transmission axis oriented in the direction of orientation of the liquid crystal molecules in the vicinity of the front substrate of the liquid crystal cell. 2. The optical sheet is arranged so as to be obliquely intersecting with the optical sheet, and the optical sheet is arranged so that its reflection axis is oriented substantially perpendicularly or substantially parallel to the transmission axis of the polarizing plate. 3. The liquid crystal display device according to item 1. 9. A liquid crystal cell, wherein a twist angle of liquid crystal molecules between a pair of substrates is in a range of 180 ° to 270 °, and a retardation plate is provided between the liquid crystal cell and the polarizing plate. The liquid crystal display device according to claim 9, wherein: 10. The liquid crystal display device according to claim 1, wherein said polarizing plate is a color polarizing plate of a predetermined color. 11. The liquid crystal cell according to claim 1, wherein a transparent colored film of a predetermined color is provided on one of front and rear surfaces of the liquid crystal cell. Liquid crystal display element.