JP2003207634A - Optical element and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust a color tone of a semitransmissive liquid crystal display device only in a transmissive display mode. <P>SOLUTION: In the semitransmissive liquid crystal display device 21, an illumination part 33, an optical element 23, a semitransmissive reflection layer 32, a liquid crystal layer 30 and a first polarizing element 31 are laminated in this order. In the optical element 23 for chromaticity adjustment, a reflective polarizing element 25, an optical retardation plate 26 and a dichroic polarizing element 27 are laminated in this order from the illumination part 33 side. A polarized light transmission axis α1 of the reflective polarizing element 25 is in parallel with a polarized light transmission axis α2 of the dichroic polarizing element 27. Retardation of the optical retardation plate 26 of the optical element 23 is selected so as to be a wavelength of a color to color transmitted light from the optical element 23. Thereby in the liquid crystal display device 21, the chromaticity of a display screen in the transmissive display mode is freely adjusted without spoiling the chromaticity of the display screen in the reflective display mode. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element including a polarizing element and a liquid crystal display device having the optical element.

[0002]

2. Description of the Related Art In recent years, information technology
With the revolutionary development of gy (abbreviated as IT), the amount of information used in mobile information terminals such as mobile phones has significantly increased, and the applications of the mobile information terminals have become diversified. Along with this, the demands of users for display devices (displays) of mobile information terminals are diversifying. The above-mentioned demands are wide-ranging, such as low voltage, high definition, and high distance response. Regarding the display colors of display devices, the number of colors is increasing at an accelerating rate, and at the same time, the demands for brightness and tint are diversifying. Therefore, for example, in a semi-transmissive display device, the brightness and the color desired by the user are displayed both in the reflective display using the external light and in the transmissive display using the light from the back light source (backlight) included in the display device. It is essential to realize the taste at the same time.

At present, a transflective liquid crystal display device is widely used as a display device used in a portable information terminal. The semi-transmissive liquid crystal display device operates as a reflective liquid crystal display device using external light in a bright place, and operates as a transmissive liquid crystal display device using a light source included in the device itself in a dark place. The transflective liquid crystal display device has a reflective layer having translucency. The semi-transmissive reflective layer is
In a dark place, the light from the back light source of the liquid crystal display device is transmitted, and if there is external light, it has the function of both transmission and reflection of reflecting the external light. Further, the transflective liquid crystal display device is provided with a light diffusing layer having a fine concavo-convex structure and made of, for example, a translucent resin in order to improve the light diffusing property of the transflective layer. The semi-transmissive reflective layer is formed on the layer. As a result, the transflective liquid crystal display device improves the diffusivity when light is reflected,
Prevents so-called character blurring and color mixing during color display,
Furthermore, the visibility of the display is improved.

The semi-transmissive reflective layer is composed of a metal thin film formed of a metal material, such as aluminum, which is thin enough to allow a part of light to pass therethrough, or is formed to be capable of reflecting all light. This is realized by a structure in which an opening is provided in the existing metal thin film. In the case of the semi-transmissive reflective layer having the former configuration, the film thickness of the metal thin film is adjusted, and in the semi-transmissive reflective layer having the latter configuration, the area of the opening is adjusted to provide the semi-transmissive reflective layer. The brightness of the display surface during the reflective display and the transmissive display of the transflective liquid crystal display device can be adjusted. However, when the film thickness of the metal thin film or the area of the opening is adjusted, there is a trade-off relationship between the luminance during reflective display and the luminance during transmissive display. It is difficult to satisfy the brightness at the same time.

In order to solve such a problem, a semi-transmissive / semi-reflective polarizing element for improving the brightness of the display surface during transmissive display without impairing the brightness of the display surface during reflective display,
A technique of a semi-transmissive liquid crystal display device using the semi-transmissive / semi-reflective polarizing element is disclosed in Japanese Patent Laid-Open No. 2001-215333. The semi-transmissive / semi-reflective polarizing element is a dichroic polarizing element that is an absorbing polarizing element, and a reflective polarizing element,
It has a semi-transmissive reflective layer, and is laminated so that the polarization transmission axes of the dichroic polarizing element and the reflective polarizing element are parallel to each other. In the semi-transmissive liquid crystal display device, a liquid crystal layer is sandwiched 2
The semi-transmissive-semi-reflective polarizing element is disposed between one of the substrates, which is disposed on the side of the back light source, and the back light source. That is, the dichroic polarizing element, the reflective polarizing element, and the semi-transmissive reflective layer are arranged on the side of the one substrate different from the liquid crystal layer in this order from the side closer to the one substrate.

The light emitted from the back light source first reaches the semi-transmissive reflective layer, and the light transmitted through the semi-transmissive reflective layer reaches the reflective polarizing element. The reflective polarization element has a property of transmitting polarized light in a specific vibration direction and reflecting polarized light orthogonal thereto. The light transmitted through the reflective polarization element is linearly polarized and supplied to the dichroic polarization element which is an absorption polarization element. As a result, the absorption loss of the dichroic polarizing element is prevented and the brightness is improved. In order to further improve the brightness, the polarization component orthogonal to the polarization transmission axis of the reflective polarization element is reflected by the reflective polarization element and returned to the semi-transmissive reflective layer and the back light source for reuse. . As the reflective polarizing element as described above, for example, JP-A-3-
No. 45906, a reflective polarizing element utilizing selective reflection characteristics of cholesteric liquid crystal, and two kinds of polymer films laminated, for example, as disclosed in JP-A-9-506837. Then, a reflective polarizing element that utilizes the anisotropy of reflectance due to the anisotropy of refractive index can be given.

By the way, when a metal thin film is used as the semi-transmissive reflective layer, there is a problem that the transmitted light of the semi-transmissive reflective layer has a unique tint. For example, when an aluminum thin film is used as the semi-transmissive reflective layer, the transmitted light of the semi-transmissive reflective layer becomes bluish, so that white color in the display surface is displayed during transmissive display of a liquid crystal display device including the semi-transmissive reflective layer. There is a problem that the portion to be displayed becomes bluish. It is thought that the reason why the transmitted light has a unique tint is that the metal thin film has a transmitted light characteristic that light on the short wavelength side of the light source easily transmits through the metal thin film, but light on the long wavelength side does not easily transmit. To be
In any case, when the transmitted light of the semi-transmissive reflective layer is bluish, the color purity of the liquid crystal display device including the semi-transmissive reflective layer is lowered during color display.

The color correction of the transmitted light of the semi-transmissive reflective layer is performed by the color filter itself in a liquid crystal display device capable of color display including the semi-transmissive reflective layer. in this case,
In the transmissive display, the transmitted light passes through the color filter once, and in the reflective display, external light is transmitted through the color filter twice before and after being reflected by the semi-transmissive reflective layer. Therefore, the color tone correction for the transmissive display greatly affects the color of the display surface during the reflective display, which lowers the color purity during the reflective display, which is not preferable. Further, in order to correct only the color tone at the time of transmissive display, it is conceivable to attach a color correcting film to the substrate on the back light source side of the liquid crystal display device. In this case, if the liquid crystal display device is stored under high temperature and high humidity conditions, the color of the color correction film is discolored or discolored due to the influence of moisture, which causes a problem in reliability. Further, it is conceivable to color the polarizing element itself in order to correct the color of transmitted light, but there is a problem that the degree of polarization of the polarizing element is lowered and the contrast of the liquid crystal display device is lowered.

In order to solve such a problem, in the transflective liquid crystal display device 1 using the metal thin film 7 as the transflective layer, the light diffusing layer 6 is colored and the transflective layer is used for transmissive display. A technique for performing color correction is disclosed in Japanese Patent Laid-Open No. 2001-1001.
No. 97 publication. Below, JP-A-2001-
The technique of Japanese Patent No. 100197 will be described in detail.

The liquid crystal display device 1 of Japanese Patent Laid-Open No. 2001-100197 is generally composed of a liquid crystal layer 2, a pair of substrates 3 and 4 sandwiching the liquid crystal layer 2, a back light source 5, and a translucent resin. And a light semi-transmissive metal thin film 7 which should function as a semi-transmissive light reflection layer. A pair of substrates 3, 4
A light diffusing layer 6 is arranged on the liquid crystal layer 2 side of the substrate 4 located on the back light source 5 side, and a light semi-transparent metal thin film 7 is formed on the light diffusing layer 6. In order to correct the tint of the transmitted light of the light semi-transmissive metal thin film 7 to white, the light diffusion layer 6
The light-transmissive resin forming is colored in a color complementary to the color of the transmitted light of the metal thin film 7.

Hereinafter, with reference to FIG.
The liquid crystal display device 1 of Japanese Patent Publication No. 0197 will be specifically described.
In the liquid crystal display device 1, the upper substrate 3 and the lower substrate 4 are
They are pressure-bonded to each other via a peripheral sealing material so that a predetermined cell thickness is formed. The liquid crystal layer 2 is sealed inside a cell composed of an upper substrate 3, a lower substrate 4, and a peripheral sealing material.
Transparent electrodes 9 and 10 and alignment films 11 and 12 are laminated between the upper substrate 3 and the lower substrate 4 and the liquid crystal layer 2, respectively. On the surfaces of the upper substrate 3 and the lower substrate 4 opposite to the liquid crystal layer 2, retardation plates 13 and 14 for optical compensation and polarizing elements 15 and 16 are laminated, respectively. A back light source 5 is provided on the side of the lower substrate 4 opposite to the liquid crystal layer 2. On the surface of the lower substrate 4 on the liquid crystal layer 2 side, a light diffusing layer 6 made of a light transmissive resin and a light semi-transparent metal thin film 7 as a light reflecting layer are laminated. Fine irregularities are formed on the surface of the light diffusion layer 6. When aluminum is used as the material of the light semi-transmissive metal thin film 7, since the color of the light transmitted by the light semi-transmissive metal thin film 7 is blue, the color of the transmitted light is corrected, and thus it is a complementary color of blue. The light diffusion layer 6 is colored yellow in advance.

In the semi-transmissive liquid crystal display device 1 of FIG. 5, the light emitted from the back light source 5 passes through the light diffusion layer 6 and the light semi-transmissive metal thin film 7, and the upper substrate on the display surface side. Up to 3. At the time of transmissive display using the light from the back light source 5, the light LB from the back light source 5 is the light semi-transmissive metal thin film 7.
Since the light diffusing layer 6 colored yellow is transmitted first, the light is transmitted through the light-semitransmissive metal thin film 7, color correction is performed in a complementary color relationship, and the display surface is illuminated as almost white light. On the other hand, during reflective display using the external light LF, the external light LF is reflected by the semitransparent metal thin film 7 without passing through the light diffusion layer 6. According to Japanese Patent Laid-Open No. 2001-100197, the difference in color of the display surface of the liquid crystal display device 1 between when the back light source 5 is used and when the external light LF is used is reduced, and a display with no discomfort is obtained. ing.

[0013]

By the way, Japanese Unexamined Patent Application Publication No.
In the transflective liquid crystal display device 1 of JP-A 1-110097, when the transflective metal thin film 7 is used as the transflective layer, the transflective layer can naturally transmit light. During the reflective display using the external light LF, as shown in FIG. After passing through the alignment film 11 on the upper substrate 3 side and the liquid crystal layer 2, it reaches the semi-transparent metal thin film 7. The light LF reaching the semi-transparent metal thin film 7 is decomposed into light L0 reflected on the surface of the semi-transparent metal thin film 7 and light transmitted through the semi-transparent metal thin film 7. The light transmitted through the semi-transparent metal thin film 7 is the first interface 1 which is the interface between the semi-transparent metal thin film 7 and the light diffusion layer 6.
7 is reflected light L1, reflected light L2 at the second interface 18, which is the interface between the light diffusion layer 6 and the member on the lower substrate 4 side, and transmitted light at the second interface 18. Therefore, the light visually recognized on the display surface during the reflective display is the reflected light L0 from the semi-transparent metal thin film 7, the reflected light L1 from the first interface 17, and the second interface 1.
The reflected light L2 at 8 becomes a light of a color combined.

When the light diffusing layer 6 of the liquid crystal display device 1 using the semi-transparent metal thin film 7 is colored, the light diffusing layer 6 effectively works for color correction during the transmissive display, but as described above. In addition, some light colored by the light diffusion layer 6 is reflected during the reflective display. Therefore, the color of the light diffusion layer 6 affects not only the transmissive display but also the chromaticity during the reflective display. Furthermore, when a metal such as aluminum or silver-palladium is used as the material of the semi-transparent metal thin film 7, the transmitted light of the semi-transparent metal thin film 7 is blue, but the reflected light of the semi-transparent metal thin film 7 is Since the complementary color is yellow, the display color on the display surface during reflection display is slightly yellow. Therefore, if the light diffusion layer 6 is colored with a complementary color of the transmitted light of the semi-transparent metal thin film 7, it is the same color as the reflected light of the semi-transparent metal thin film 7. The display color on the display surface becomes more yellowish. As described above, when the color tone during transmissive display is adjusted by coloring the light diffusion layer 6, there is a trade-off problem that the tint during reflective display is impaired.

An object of the present invention is to provide an optical element that freely adjusts only the color tone during transmissive display without impairing the color tone during reflective display of a semi-transmissive liquid crystal display device, and that has a good transmittance. An object of the present invention is to provide a transflective liquid crystal display device using an element.

[0016]

DISCLOSURE OF THE INVENTION The present invention is directed to a reflective polarizing element that transmits polarized light in a predetermined reference vibration direction and reflects polarized light orthogonal to the reference vibration direction, and light that passes through the reflective polarization element. It is arranged on the road so that its polarization transmission axis is parallel to the polarization transmission axis of the reflective polarizing element, and it transmits polarized light in a predetermined reference vibration direction and transmits polarized light orthogonal to the reference vibration direction. An optical element comprising: a dichroic polarizing element that absorbs light; and a retardation plate disposed between the reflective polarizing element and the dichroic polarizing element.

According to the present invention, the optical element has a three-layer structure of a reflective polarizing element, a retardation plate and a dichroic polarizing element. Of the light entering the optical element from the reflective polarization element side, the polarized light in the reference polarization direction of the reflective polarization element is first linearly polarized by passing through the reflective polarization element and supplied to the retardation plate. To be done. The linearly polarized light supplied to the retardation plate is elliptically polarized depending on the retardation of the retardation plate and supplied to the dichroic polarizing element. At this time,
Since there is wavelength dependence in the state of elliptically polarized light that exits the retardation plate, the transmittance of polarized light that passes through the dichroic polarizing element also exhibits wavelength dependence, so it passes through the dichroic polarizing element. The polarized light is colored. Thereby, the optical element can color the external light incident from the reflective polarizing element side in an arbitrary color and emit the external light.

Of the light incident on the optical element from the reflective polarizing element side, the polarized light in the direction orthogonal to the reference polarization direction of the reflective polarizing element is reflected by the reflective polarizing element and returned to the incident direction. . If the light source of the incident light is provided with a reflector or the like, the reflected light is supplied to the optical element again. This makes it possible to effectively use the incident light from the light source. By these, the optical element can color the light transmitted through the entire optical element in an arbitrary color, and can improve the brightness of the light transmitted through the optical element.

Further, the optical element of the present invention is characterized in that the retardation of the retardation plate is selected to a wavelength of light corresponding to a color to be colored.

According to the invention, in the optical element, the light linearly polarized by the reflective polarizing element is elliptically polarized by passing through the retardation plate. If the retardation of the retardation plate is set to the wavelength corresponding to the color to be colored, the light of the color corresponding to the wavelength equal to the retardation of the retardation plate, that is, the light of the color to be colored is the color to be colored. Is less affected by the retardation plate than light of wavelengths corresponding to other colors. Therefore, of the light incident on the retardation plate, the light of the color corresponding to the wavelength equal to the retardation of the retardation plate is converted into the dichroic polarizing element while maintaining the linearly polarized state after the reflection type polarizing element exits. Supplied. Further, of the light incident on the retardation plate, the light of the wavelength corresponding to the other color is elliptically polarized by the retardation plate than the light of the color to be colored, and then the dichroic polarizing element. Is supplied to. As a result, the wavelength dependency is exhibited in the transmittance of the dichroic polarizing element of the light supplied from the retardation plate to the dichroic polarizing element, and the transmittance of the polarized light of the wavelength of the color to be colored is It is relatively higher than the transmittance of polarized light of wavelengths other than the wavelength of the power color. As a result, the optical element emits light that enters from the reflective polarizing element side and exits from the dichroic polarizing element side.
It can be colored to be colored.

Further, the optical element of the present invention is characterized in that the retardation of the retardation plate is selected to a wavelength of 380 nm or more and 440 nm or less.

According to the invention, in the optical element, the retardation of the retardation plate is a value of 380 nm or more and 440 nm or less, that is, a wavelength range of light of a blue color.
The value is selected within the range of 10 nm ± 30 nm. In the optical element, the light linearly polarized by the reflective polarization element is elliptically polarized by passing through the retardation plate. If the retardation of the retardation plate is set to a value within the wavelength range of light of blue color, light of blue color is better than light of wavelength corresponding to other colors other than blue color. ,
Hard to be affected by the retarder. For this reason, of the light that has entered the retardation plate, the light of a blue color is supplied to the dichroic polarizing element while maintaining the linearly polarized state after being emitted from the reflective polarizing element. Further, of the light incident on the retardation plate, the light of a color other than the blue color is supplied to the dichroic polarizing element after being made more elliptically polarized than the light of the blue color by the retardation plate. To be done. As a result of these, the wavelength dependence is exhibited in the transmittance of the dichroic polarizing element of the light supplied from the retardation plate to the dichroic polarizing element, and the transmittance of the polarized light of the wavelength corresponding to the blue color is The transmittance is relatively higher than the transmittance of polarized light of wavelengths corresponding to colors other than blue. This allows the optical element to blueize the light that enters from the reflective polarizing element side and that exits from the dichroic polarizing element side.

Further, the optical element of the present invention is characterized in that the retardation of the retardation plate is selected to a wavelength of 490 nm or more and less than 550 nm.

According to the invention, in the optical element, the retardation of the retardation plate is a value of 490 nm or more and less than 550 nm, that is, a wavelength range of light of a greenish color.
The value is selected within the range of 20 nm ± 30 nm. In the optical element, the light linearly polarized by the reflective polarization element is elliptically polarized by passing through the retardation plate. If the retardation of the retardation plate is set to a value within the wavelength range of the light of the greenish color, the light of the greenish color is better than the light of the wavelength corresponding to other colors other than the greenish color. ,
Hard to be affected by the retarder. For this reason, of the light that has entered the retardation plate, the light of a greenish color is supplied to the dichroic polarizing element while maintaining the linearly polarized state after being emitted from the reflective polarizing element. Further, of the light incident on the retardation plate, light of a color other than green is supplied to the dichroic polarizing element after being made more elliptically polarized than light of a green color by the retardation plate. To be done. As a result of these, wavelength dependence is exhibited in the transmittance of the dichroic polarizing element of the light supplied from the retardation plate to the dichroic polarizing element, and the transmittance of the polarized light of the wavelength corresponding to the greenish color, The transmittance is relatively higher than the transmittance of polarized light of wavelengths corresponding to colors other than green. As a result, the optical element can green the light that enters from the reflective polarizing element side and exits from the dichroic polarizing element side.

Further, the optical element of the present invention is characterized in that the retardation of the retardation plate is selected to be a wavelength of 550 nm or more and less than 610 nm.

According to the present invention, in the optical element, the retardation of the retardation plate is a value of 550 nm or more and less than 610 nm, that is, a wavelength range of yellowish light.
The value is selected within the range of 80 nm ± 30 nm. In the optical element, the light linearly polarized by the reflective polarization element is elliptically polarized by passing through the retardation plate. If the retardation of the retardation plate is set to a value within the wavelength range of light of yellowish color, light of yellowish color will be better than light of wavelengths corresponding to other colors other than yellowish. ,
Hard to be affected by the retarder. Therefore, of the light that has entered the retardation plate, the light of a yellowish color is supplied to the dichroic polarizing element while maintaining the linearly polarized state after being emitted from the reflective polarizing element. Also, of the light incident on the retardation plate, the light of a color other than the yellow color is supplied to the dichroic polarizing element after being made more elliptically polarized than the light of the yellow color by the phase difference plate. To be done. As a result of these, the wavelength dependence is exhibited in the transmittance of the dichroic polarizing element of the light supplied from the retardation plate to the dichroic polarizing element, and the transmittance of the polarized light of the wavelength corresponding to the yellowish color, It is relatively higher than the transmittance of polarized light of wavelengths corresponding to colors other than yellow. As a result, the optical element can yellow the light that enters from the reflective polarizing element side and exits from the dichroic polarizing element side.

Further, the optical element of the present invention is characterized in that the retardation of the retardation plate is selected to a wavelength of 610 nm or more and 670 nm or less.

According to the present invention, in the optical element, the retardation of the retardation plate is a value of 610 nm or more and 670 nm or less, that is, the wavelength range of light of reddish color.
The value is selected within the range of 40 nm ± 30 nm. In the optical element, the light linearly polarized by the reflective polarization element is elliptically polarized by passing through the retardation plate. If the retardation of the retardation plate is set to a value within the wavelength range of the light of the red color, the light of the red color is better than the light of the wavelength corresponding to other colors other than the red color. ,
Hard to be affected by the retarder. Therefore, of the light incident on the retardation plate, the red-colored light is supplied to the dichroic polarizing element while maintaining the linearly polarized state after being emitted from the reflective polarizing element. Also, of the light incident on the retardation plate, the light of a color other than red is supplied to the dichroic polarizing element after being made more elliptically polarized than the light of red by the retardation plate. To be done. As a result of these, the wavelength dependency is exhibited in the transmittance of the dichroic polarizing element of the light supplied from the retardation plate to the dichroic polarizing element, and the transmittance of the polarized light of the wavelength corresponding to the red color is It is relatively higher than the transmittance of polarized light of wavelengths corresponding to colors other than red. As a result, the optical element can make the light incident from the reflective polarizing element side and emitted from the dichroic polarizing element side red.

Further, in the optical element of the present invention, the angle formed by the slow axis of the retardation plate with respect to the polarization transmission axes of the reflective polarizing element and the dichroic polarizing element is such that the transmitted light of the reflective polarizing element is The color of the transmitted light of the dichroic polarizing element with reference to the x and y values of the XYZ color system of the color of the transmitted light of the dichroic polarizing element when directly entering the dichroic polarizing element. Is selected as an angle formed by the slow axis with respect to the polarization transmission axis when the difference between the x value or the y value of the XYZ color system and the reference value is in the range of 0.005 or more and 0.02 or less. It is characterized by

According to the present invention, in the optical element, the angle formed by the slow axis of the retardation plate with respect to the polarization transmission axes of the reflective polarizing element and the dichroic polarizing element in the optical element is the dichroic polarizing element. Of the transmitted light, that is, the color of the transmitted light of the entire optical element, is limited based on the difference between the x value and the y value of the XYZ color system and the reference value. The reference value is x in the XYZ color system of the color of the transmitted light of the dichroic polarizing element when the transmitted light of the reflective polarizing element is directly incident on the dichroic polarizing element.
Value and y value, that is, the x value and the y value of the XYZ color system of the color of the transmitted light of the optical element having no retardation plate. The lower limit of the allowable range of the angle formed by the slow axis with respect to the polarization transmission axis is 0.005 when the difference between the x value and the y value of the color of the transmitted light of the dichroic polarizing element and the reference value is 0.005. Is an angle formed by the slow axis with respect to the polarization transmission axis of. The upper limit of the allowable range is an angle formed by the slow axis with respect to the polarization transmission axis when the difference between the x value and the y value and the reference value is 0.02. By selecting the angle formed by the slow axis with respect to the polarization transmission axis to an angle within such an allowable range, the degree of coloring of light that is incident from the reflective polarization element and transmitted through the dichroic polarization element, It can be controlled to a practically necessary and sufficient level.

The present invention also includes the above-mentioned optical element, a liquid crystal layer disposed on the dichroic polarizing element side of the optical element, and a first polarizing element disposed on the opposite side of the liquid crystal layer from the optical element. A liquid crystal display device comprising: a transflective layer disposed between a dichroic polarizing element of an optical element and a liquid crystal layer; and an illuminating unit disposed on the reflective polarizing element side of the optical element. is there.

According to the present invention, the liquid crystal display device is a semi-transmissive type, and includes illumination means, a reflective polarizing element of an optical element, a retardation plate of the optical element, a dichroic polarizing element of the optical element,
The transflective layer, the liquid crystal layer, and the first polarizing element are laminated in this order. During transmissive display in which light from the illuminating means is used for display, the light emitted from the illuminating means passes through the optical element and reaches the liquid crystal layer, whereby linearly polarized light colored in a desired color is supplied to the liquid crystal layer. Thereby, the chromaticity of the display surface of the liquid crystal display device can be freely adjusted by using the retardation of the retardation plate of the optical element. Further, since the light emitted from the illuminating means and reflected by the reflective polarization element is returned to the illuminating means again, the reflected light can be reused by the illuminating means, so that the liquid crystal display device achieves high transmittance. can do. Furthermore, during reflective display using external light for display, since the optical element for adjusting chromaticity is arranged closer to the illuminating device than the semi-transmissive reflective layer, external light does not reach before reaching the optical element. The light is reflected by the semi-transmissive reflective layer and returned to the first polarizing element side which is the display surface side. As a result, the liquid crystal display device is not affected by the chromaticity adjusting optical element at the time of reflective display, so that the chromaticity at the time of reflective display is not impaired at all. With these, the liquid crystal display device can freely adjust the chromaticity of the display surface during the transmissive display without improving the chromaticity of the display surface during the reflective display, and can improve the transmittance.

[0033]

1 is a sectional view showing a schematic structure of a liquid crystal display device 21 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a schematic configuration of the chromaticity adjusting optical element 23 used in the liquid crystal display device 21 of FIG. 1 and 2 will be described together.

The chromaticity adjusting optical element 23 includes a reflective polarizing element 25, a retardation plate 26 and a dichroic polarizing element 27. The reflective polarization element 25 transmits the polarized light in the predetermined reference vibration direction and reflects the polarized light in the direction orthogonal to the reference vibration direction. The dichroic polarizing element 27 transmits polarized light in a predetermined reference vibration direction and absorbs polarized light orthogonal to the reference vibration direction. The reflective polarization element 25 and the dichroic polarization element 27 are arranged such that the polarization transmission axis α1 of the reflection polarization element 25 and the polarization transmission axis α2 of the dichroic polarization element 27 are parallel to each other. . The retardation plate 26 is arranged between the reflective polarization element 25 and the dichroic polarization element 27. The reflective polarization element 25, the retardation film 26, and the dichroic polarization element 27 are laminated in this order on one optical path from the light incident side to the light emission side. In the present specification, the “polarization transmission axis of the polarizing element” refers to the direction in which the transmittance becomes maximum when polarized light in the reference vibration direction enters from the vertical direction of the polarizing element.

As described above, the optical element 23 of FIG. 2 has a three-layer structure of the reflection type polarizing element 25, the retardation plate 26 and the dichroic polarizing element 27. Of the light that has entered the optical element 23 from the reflective polarization element 25 side, the polarized light in the reference polarization direction of the reflective polarization element 25 is first linearly polarized by passing through the reflective polarization element 25, It is supplied to the phase difference plate 26. The linearly polarized light supplied to the retardation plate 26 is elliptically polarized depending on the retardation of the retardation plate 26, and then supplied to the dichroic polarizing element 27. At this time, since the state of the elliptically polarized light emitted from the retardation plate 26 has wavelength dependency, the transmittance of polarized light transmitted through the dichroic polarizing element 27 also exhibits wavelength dependency. Therefore, the polarized light transmitted through the dichroic polarizing element 27 is colored. by this,
The optical element 23 can color the light incident from the reflective polarizing element 25 side into an arbitrary color and emit the light. Of the light that has entered the optical element 23 from the reflective polarization element 25 side, the polarized light in the direction orthogonal to the reference polarization direction of the reflective polarization element 25 is reflected by the reflective polarization element 25 and returned to the incident direction. Be done. If the light source of the incident light is provided with a reflection plate or the like, the reflected light is supplied to the optical element 23 again. This makes it possible to effectively use the incident light from the light source. With these, the optical element 23 only needs to adjust the retardation of the retardation plate 26.
The light transmitted through the whole can be easily colored, and
The brightness of the light transmitted through the optical element 23 can be improved.

The liquid crystal display device 21 of FIG. 1 equipped with the chromaticity adjusting optical element 23 is basically a liquid crystal layer 30, a first polarizing element 31, and a semi-transmissive element in addition to the optical element 23. The reflective layer 32 and the illumination part 33 are included. The liquid crystal layer 30 is arranged on the dichroic polarizing element 27 side of the optical element 23 on the optical path passing through the optical element 23. The first polarizing element 31 is arranged on the optical path on the opposite side of the liquid crystal layer 30 from the optical element 23. The semi-transmissive reflective layer 32 is arranged between the dichroic polarizing element 27 of the optical element 23 and the liquid crystal layer 30 on the optical path. The illuminating unit 33 is a so-called backlight, and is arranged on the optical path 23 on the reflective polarization element 25 side of the optical element 23.

In the liquid crystal display device 21, the illumination unit 33,
The reflective polarizing element 25 of the optical element 23, the retardation plate 26 of the optical element 23, the dichroic polarizing element 27 of the optical element 23, the semi-transmissive reflective layer 32, the liquid crystal layer 30, and the first polarizing element 31.
Are laminated in this order on one optical path. The liquid crystal display device 21 of FIG. 1 may further include a retardation plate between the liquid crystal layer 30 and the optical element 23. For example, the first polarizing element 31, the first retardation plate, the liquid crystal layer 30, the semi-transmissive reflective layer 32, the second retardation plate, the optical element 23, and the illumination unit 3.
The effect of the present invention is exhibited even in the configuration in which 3 is arranged in this order. In the liquid crystal display device 21 of FIG. 1, the first polarizing element 31 side is the display surface on which the image is displayed closest to the user, and the illumination unit 33 side is the back surface.

As described above, the liquid crystal display device 21 of FIG.
It is a semi-transmissive type. During the transmissive display in which the light from the illumination unit 33 is used for display, the light emitted from the illumination unit 33 is emitted from the optical element 2
By passing through 3 and reaching the liquid crystal layer 30, linearly polarized light colored in a desired color is supplied to the liquid crystal layer 30. Thereby, the chromaticity of the display surface of the liquid crystal display device 21 can be freely adjusted at the time of designing by adjusting the retardation of the retardation plate 26 of the optical element 23. Also,
The light emitted from the illuminating unit 33 and reflected by the reflective polarization element 25 is returned to the illuminating unit 33 again. Therefore, if the reflected light is reflected to the liquid crystal layer 30 side again by using a reflection plate or the like included in the illuminating unit 33. , Light can be reused. Therefore, the liquid crystal display device 21 of FIG. 1 can achieve high transmittance.
Furthermore, during reflection display using external light for display, the optical element 23 for adjusting chromaticity is arranged closer to the illumination unit 33 than the semi-transmissive reflective layer 32, and therefore external light is reflected by the optical element 2.
Before reaching 3, the light is reflected by the semi-transmissive reflective layer 32 and returned to the first polarizing element 31 side which is the display surface side. As a result, the liquid crystal display device 21 is not affected by the chromaticity adjusting optical element 23 at the time of the reflective display, so that the chromaticity of the display surface during the reflective display is not impaired at all. With these, the liquid crystal display device 21 can freely adjust the chromaticity of the display surface during the transmissive display without improving the chromaticity of the display surface during the reflective display, and can improve the transmittance. .

In the example of FIG. 1, the liquid crystal display device 21 is a simple matrix drive type super twisted nematic (Super Tw).
This is realized by an isted Nematic (STN) type liquid crystal display device 21. The liquid crystal display device 21 of FIG. 1 has a first substrate 35, a second substrate 36, a first retardation plate 37, and
Second retardation plate 38, third retardation plate 39, fourth retardation plate 4
0, the light diffusion layer 41, the color filter 42, the protective layer 43,
The first electrode 45, the second electrode 46, the first alignment film 47, and the second alignment film 48 are included.

The transparent first substrate 35 and the transparent second substrate 36 face each other with the liquid crystal layer 30 in between, and each substrate 35,
It is arranged so that one surface of 36 is parallel to each other.
The first polarizing element 31 is arranged on the side of the first substrate 35 opposite to the liquid crystal layer 30. The optical element 23 for chromaticity adjustment is the second
The substrate 36 is arranged on the opposite side of the liquid crystal layer 30. The first retardation plate 37 is arranged between the first substrate 35 and the first polarizing element 31. The second retardation plate 38 is the first retardation plate 37.
And the first polarization element 31. The third retardation plate 39 is arranged between the second substrate 36 and the optical element 23. The fourth retardation plate 40 is arranged between the third retardation plate 39 and the optical element 23. First to fourth retardation plates 37 to 4
Reference numeral 0 is a retardation plate for optical compensation, and two sheets are used as one set in the example of FIG. The illumination unit 33 includes the optical element 23.
Is arranged on the side opposite to the liquid crystal layer 30.

A light diffusing layer 41 made of a colorless and transparent material is provided on one surface of the second substrate 36 on the liquid crystal layer 30 side. The surface of the light diffusion layer 41 on the liquid crystal layer 30 side is provided with, for example, irregularities. Liquid crystal layer 30 of light diffusion layer 41
The semi-transmissive reflective layer 32 is provided on the side. The semi-transmissive reflective layer 32 is formed of a metal material such as aluminum (Al), palladium (Pd), silver (Ag), or an alloy containing at least one of these metals. The surface of the semi-transmissive reflective layer 32 on the liquid crystal layer 30 side is uneven so as to follow the unevenness of the surface of the light diffusion layer 41 on the liquid crystal layer 30 side.

A color filter 42 is provided on the surface of the semi-transmissive reflective layer 32 on the liquid crystal layer 30 side. In the color filter 42, specifically, three colored layers of red (R) green (G) blue (B) are arranged in a predetermined pattern on the surface of the semi-transmissive reflective layer 32 on the liquid crystal layer 30 side. Has been done. The unevenness on the surface of the semi-transmissive reflective layer 32 on the liquid crystal layer 30 side is caused by the color filter 4
2 is flattened. A transparent protective layer 43 is provided on the surface of the color filter 42 on the liquid crystal layer 30 side.

The first electrode 45 and the second electrode 46 are transparent and strip-shaped, and a plurality of them are prepared. The plurality of first electrodes 45 are arranged on one surface of the first substrate 35 on the liquid crystal layer 30 side so that the length directions thereof are parallel to each other and a predetermined space is provided between two adjacent first electrodes 45. Placed on top. The plurality of second electrodes 46 are provided on the surface of the protective layer 43 on the liquid crystal layer 30 side so that the length directions thereof are parallel to each other and a predetermined space is provided between two adjacent second electrodes 46. Will be placed. The length direction of the first electrode 45 is orthogonal to the length direction of the second electrode 46 when viewed from the normal direction of the one surface of the first substrate 35. Inside the liquid crystal display device 21, portions where the first electrode 45 overlaps the second electrode 46 when viewed from the normal direction of the one surface of the first substrate 35 respectively function as pixels of the liquid crystal display device 21.

The first alignment film 47 is disposed between the first substrate 35 and the liquid crystal layer 30, and of the components 45 and 47 disposed between the first substrate 35 and the liquid crystal layer 30. And is closest to the liquid crystal layer 30. The second alignment film 48 is the second
Is disposed between the substrate 36 and the liquid crystal layer 30, and
The component 4 arranged between the second substrate 36 and the liquid crystal layer 30.
The liquid crystal layer 30 among 1, 32, 42, 43, 46, 48
Is the closest to. The first alignment film 47 and the second alignment film 48 are each subjected to an alignment treatment in a predetermined direction by rubbing or the like. The liquid crystal layer 30 includes the first alignment film 4
7 and the second alignment film 48 are formed of nematic liquid crystal. The periphery of the liquid crystal layer 30 is sealed by a frame-shaped seal layer. The first and second alignment films 47 and 48 give the liquid crystal layer 30 a twist angle of 240 degrees or more and 260 degrees or less.

The liquid crystal display device 21 of the present embodiment
Has a basic configuration including the optical element 23, the liquid crystal layer 30, the first polarizing element 31, the semi-transmissive reflective layer 32, and the illumination section 33 as described above, it is difficult to adjust the color birefringence. The present invention is not limited to the STN type liquid crystal display device of the simple matrix type which performs display by, but can be realized by an active matrix type liquid crystal display device, a segment type liquid crystal display device, or another drive type liquid crystal display device. . In the liquid crystal display device 21 of FIG. 1, as the semi-transmissive reflective layer 32 that transmits a part of light and reflects the rest,
Although a semi-transparent metal thin film is used, a metal thin film having an opening may be used. In addition, the liquid crystal display device 2 of FIG.
1, the light diffusion layer 41 is used to improve the diffusivity of the reflected light.
1 can be excluded.

The polarizing element 25 used in the optical element 23 and the liquid crystal display device 21 of the present invention has a property of transmitting polarized light in the reference vibration direction and reflecting polarized light orthogonal to the reference vibration direction. It is an element. As such a reflective polarization element 25, for example, Japanese Patent Laid-Open No. 9-50683 can be used.
A polarizing element utilizing the anisotropy of reflectance due to the anisotropy of refractive index by laminating two kinds of polymer films having different refractive indexes as disclosed in Japanese Patent No. 7 can be used. Further, for example, such a reflective polarization element 2
5, a cholesteric liquid crystal layer 30 and a quarter-wave plate (1) as disclosed in JP-A-3-45906.
A polarizing element utilizing selective reflection by a cholesteric liquid crystal can be used by combining a / 4λ plate) and a mirror.

The dichroic polarizing element 27 used in the optical element 23 and the liquid crystal display device 21 of the present invention is a polarizing element having a property of transmitting polarized light in the reference vibration direction and absorbing polarized light orthogonal thereto. is there. As such a dichroic polarizing element 27, for example, a known dichroic polarizing element realized by an iodine-based polarizing film or the like can be used. The iodine-based polarizing film is a film obtained by adsorbing iodine on a stretched polyvinyl alcohol film.

Liquid crystal layer 30 and retardation plates 26, 37-4
The optical compensation plate represented by 0 and the like is a plate-shaped member having birefringence. The retardation Re of such an optical compensation plate is defined by the product of the refractive index anisotropy Δn of the optical compensation plate and the thickness d of the optical compensation plate as shown in the following equation. Re = d × Δn (1)

The principle of coloring the transmitted light by the chromaticity adjusting optical element 23 shown in FIGS. 1 and 2 will be described below. For convenience of description, the light emitted from the illumination unit 33 is treated as a combined light of wavelengths corresponding to the three colors of red (R), green (G), and blue (B).

The light emitted from the illumination unit 33 first reaches the reflective polarization element 25 of the optical element 23. The reflective polarization element 25 of the optical element 23 transmits polarized light in the reference vibration direction,
The polarized light orthogonal to the reference vibration direction is reflected. Therefore, since only polarized light having an oscillation direction parallel to the polarization transmission axis α1 of the reflective polarization element 25 passes through the reflective polarization element 25, red (R) parallel to the polarization transmission axis α1 of the reflective polarization element 25 is transmitted. Linearly polarized light having wavelengths corresponding to green, green (G), and blue (B) are supplied to the retardation plate 26 of the optical element 23. The linearly polarized lights having wavelengths corresponding to red (R), green (G), and blue (B) supplied to the retardation plate 26 have different elliptically polarized states according to the retardation of the retardation plate 26. In addition, the elliptically polarized state of linearly polarized light having wavelengths corresponding to red (R), green (G), and blue (B) after passing through the retardation plate 26 is not limited to the retardation of the retardation plate 26 as a matter of course. It also depends on the slow axis β direction of the phase plate 26.

Next, the lights of the wavelengths corresponding to red (R), green (G) and blue (B), which are elliptically polarized by the phase difference plate 26, are dichroic polarizing elements 27 of the optical element 23. Is supplied to. Here, red (R) elliptically polarized light, green (G) elliptically polarized light, and blue (B) elliptically polarized light have different polarization states from each other, and when light passes through the dichroic polarizing element 27. The transmissivity of depends on the polarization state of light. Therefore, red (R), green (G), and blue (B) after passing through the dichroic polarizing element 27.
Relative strengths are generated in the light intensity of the wavelengths corresponding to and.

As a result, for example, the dichroic polarizing element 27.
The phase difference is set so that the intensity of light having a wavelength corresponding to red (R) after passing is relatively stronger than the intensity of light having wavelengths corresponding to other green (G) and blue (B), respectively. By selecting the retardation of the plate 26, the light transmitted through the dichroic polarizing element 27 can be colored in red (R). That is, the transmittance of the dichroic polarizing element 27 is higher than that of the light of the wavelength corresponding to red (R) than the intensity of the light of the wavelength corresponding to green (G) and blue (B), respectively. By selecting the retardation of the phase difference plate 26, the light emitted from the optical element 23 can be colored in red. When the transmitted light of the dichroic polarizing element 27 is desired to be colored in green (G) or blue (B), the retardation of the retardation plate 26 is colored as in the case where the transmitted light is colored in red. Just choose the color that suits your needs.

When the light to be colored is supplied to the dichroic polarizing element 27 while keeping the linearly polarized state of the reflection type polarization element 25 of the color of the color to be emitted as much as possible, it is more reflected. Transmission intensity of the light of the color to be colored through the optical element 23 as compared with the case where the light to be colored is supplied to the dichroic polarizing element 27 in a state where the linearly polarized state after being emitted from the type polarization element 25 is broken. Becomes relatively stronger. Therefore, for the retardation of the retardation plate 26, the wavelength corresponding to the color to be colored may be selected as it is.

As described above, the reflective polarizing element 25
It is preferable that the linearly polarized light having the wavelength corresponding to the desired color obtained by the above is supplied to the dichroic polarizing element 27 in a state where the polarization state is maintained even after passing through the retardation plate 26. When the polarization transmission axis α2 and the polarization transmission axis α1 of the reflective polarization element 25 are parallel to each other, the transmittance of the entire optical element 23 is highest. Therefore, the reflective polarization element 2
The polarization transmission axis α1 of 5 and the polarization transmission axis α2 of the dichroic polarizing element 27 are preferably parallel to each other.

Based on the above principle, in the optical element 23, it is preferable that the retardation of the retardation plate 26 is selected to be the wavelength of the light of the color to be colored. Phase plate 26
If the retardation of is set to the wavelength corresponding to the color to be colored, the light of the color corresponding to the wavelength equal to the retardation of the retardation plate 26, that is, the light of the color to be colored is other than the color to be colored. It is less affected by the retardation plate 26 than the light of the wavelength corresponding to another color. Therefore, of the light that has entered the retardation plate 26, the light of the color to be colored passes through the retardation plate 26 while maintaining the linearly polarized state after being emitted from the reflective polarization element 25, and then dichroic. The light of the other color is supplied to the polarization element 27, is made more elliptically polarized than the light of the color to be colored by the retardation plate 26, and then is supplied to the dichroic polarization element 27. As a result, the dichroic polarizing element 2
7 shows wavelength dependency of the transmittance of the light supplied to the dichroic polarizing element 27, and the transmittance of polarized light of the wavelength of the color to be colored is higher than the transmittance of polarized light of the other wavelengths. . As a result, the optical element 23 can color the light that is incident from the reflective polarizing element 25 side and is emitted from the dichroic polarizing element 27 side to a color that should be colored.

In the optical element 23, the retardation plate 26
It is possible to finely adjust the chromaticity of the light transmitted through the entire optical element 23 by selecting the retardation of the above from a value within a predetermined range including the wavelength of the color to be colored. Preferably, by selecting the retardation of the retardation plate 26 within a range of ± 30 nm centering on the wavelength of the color to be colored, the color of the transmitted light of the entire optical element 23 should be colored within a practically sufficient range. It is possible to finely adjust the chromaticity of the transmitted light while coloring almost completely.

Based on these results, in order to make light blue by using the optical element 23, the wavelength of blue light is 410n.
Range of ± 30 nm centered around m (410 nm ± 30 n
It is understood that the retardation of the retardation film 26 may be selected from within m), that is, within the range of 380 nm to 440 nm. Further, in order to make light green by using the optical element 23, the retardation plate is selected from within a range of ± 30 nm (520 nm ± 30 nm) centered around 520 nm which is the wavelength of green light, that is, within a range of 490 nm or more and less than 550 nm. It is understood that 26 retardations should be selected.
Furthermore, in order to make light yellow by using the optical element 23,
± 30n centered around the wavelength of 580nm of yellow light
Within the range of m (580 nm ± 30 nm), that is, 550
It is understood that the retardation of the retardation plate 26 may be selected from the range of not less than nm and less than 610 nm. In order to make light red using the optical element 23, a range of ± 30 nm (64 nm around the wavelength 640 nm of red light)
0 nm ± 30 nm), that is, 610 nm or more and 670
It is understood that the retardation of the retardation film 26 may be selected from the range of nm or less.

In the transflective liquid crystal display device 21 of FIG. 1 equipped with the optical element 23 of FIG. 2, the following five types of experiments and evaluations were conducted on the chromaticity of the display surface during transmissive display and reflective display. It was In the present specification, “transmissive display” means that the liquid crystal layer 3 is transmitted from the back side through the semi-transmissive reflective layer 32.
The light incident on 0 is used for display, and the reflective display is used when the light incident on the liquid crystal layer 30 from the display surface side and reflected by the semitransparent reflective layer 32 is used for display. In the following evaluation, the retardation of the retardation plate 26 of the optical element 23, the polarization transmission axes α1 and α2 of the reflective polarizing element 25 and the dichroic polarizing element 27 of the optical element 23, and the retardation plate 26 of the optical element 23 are evaluated. Two angles θ formed by the slow axis β are used as parameters for evaluation.

A liquid crystal display device 2 having the structure of FIG. 1 used for evaluation.
1 was created by the following procedure. First, the second substrate 36
A film transfer type uncolored light diffusing layer 41 made of an acrylic resin is formed thereon. The thickness of the light diffusion layer 41 is 2.
It is 5 μm. Next, a metal thin film made of an aluminum-palladium compound (Ag-Pd) is formed as the semi-transmissive reflective layer 32 on the light diffusion layer 41 by using the sputtering method. The thickness of the semi-transmissive reflective layer 32 is 40 nm (= 4
00Å).

Next, a color filter 42 including a red (R) colored layer, a green (G) colored layer, and a blue (B) colored layer is formed on the semi-transmissive reflective layer 32, and a protective layer is further formed. 43 is deposited on the color filter 42. The film thickness of the color filter is 0.8 μm. IT is formed on the protective layer 43.
A thin film made of O (Indium Tin Oxide) is formed, and further, as the second electrode 46, IT
The O thin film is patterned into stripes. A second alignment film 48 made of polyimide is formed on the upper surface of the second electrode 46, and the surface of the second alignment film 48 is subjected to alignment treatment by rubbing or the like so as to have a twist of 250 degrees. There is.

Next, a thin film of ITO is formed on the upper surface of the first substrate 35, and further, as the first electrode 45, I
The TO thin film is patterned in a stripe shape. A first alignment film 47 made of polyimide is formed on the upper surface of the first electrode 45.
Is formed, and the surface of the first alignment film 47 is subjected to alignment treatment by rubbing or the like so as to have a twist of 250 degrees.

The first substrate 35 and the second substrate after the respective alignment films are formed.
Plastic beads are scattered on one of the substrates 36 on the side of the alignment film, and a sealing material is applied to the peripheral portion of the alignment film. Next, the first substrate 35 and the second substrate 36 are pressure-sealed in a state where the alignment films are aligned so that they are closest to each other. The cell thickness, which is the distance between the first alignment film 47 and the second alignment film 48 after sealing, is 5 μm. In the gap between the first substrate 35 and the second substrate 36 after sealing, a nematic containing a chiral agent optimized for the configuration of the liquid crystal display device 21 having a twist angle of 250 degrees and a cell thickness of 5 μm. Liquid crystal is injected and sealed. This completes the liquid crystal cell.

After completion of the liquid crystal cell, the liquid crystal layer 3 of the first substrate 35.
On the side opposite to 0, the first and second phase difference plates 3 for optical compensation are provided.
7 and 38 are arranged, and the first polarizing element 31 is arranged on the side of the second retardation plate 38 opposite to the liquid crystal layer 30. Also, the second
Third and fourth retardation plates 39 and 40 for optical compensation are arranged on the side of the substrate 36 opposite to the liquid crystal layer 30. On the opposite side of the fourth retardation plate 40 from the liquid crystal layer 30, the optical element 23 of FIG.
However, the dichroic polarizing element 27, the retardation plate, the reflective polarizing element 2
They are arranged in the order of 5 away from the fourth retardation plate 40. On the side of the optical element 23 opposite to the liquid crystal layer 30, a light source that emits white light is attached as an illumination unit 33. The liquid crystal display device 21 for evaluation is obtained by the above procedure.

The retardation and the axial angle of each retardation plate provided in the five liquid crystal display devices 21 used for the evaluation,
Also, the axis angles of the respective polarization elements are different from each other only in the retardation and the axis angle of the retardation plate 26 of the optical element 23, and the others are common to each other. That is, the first to fourth retardation plates 3
7 to 40, the first polarizing element 31, the dichroic polarizing element 27 of the optical element 23, and the reflective polarizing element 25 of the optical element 23, all of the five types of liquid crystal display devices 21 used in the evaluation were used. , Has the following configuration. In the present specification, the axial angle of each retardation plate and each polarization element is positive in the clockwise direction and positive in the counterclockwise direction, with the alignment direction of the liquid crystal molecules, that is, the rubbing direction of the nearest alignment film as 0 degree. Show as negative. Further, in the present specification, an angle formed by any two axes is shown as positive clockwise and negative counterclockwise unless otherwise specified.

[0065]

[Table 1]

The structures of the retardation plates 37 and 38 and the polarizing element 31 on the first substrate 35 side are as shown in FIG. 3 (A) and Table 1. That is, based on the alignment direction 51 of the liquid crystal molecules closest to the first substrate 35, the axis angle of the slow axis 52 of the first retardation plate 37 is −55 degrees and the slow axis 53 of the second retardation plate 38 is the slow axis 53. The first retardation plate 37 and the second retardation plate 38 have an axial angle of −5 degrees, and a polarization transmission axis 54 of the dichroic polarizing element that is the first polarizing element 31 has an axial angle of 62.5 degrees. And the first polarizing element 31 are attached in this order from the first substrate 35 side. The retardation of the first retardation plate 37 is selected to be 180 nm, the retardation of the second retardation plate 38 is selected to be 670 nm, and the retardation of the liquid crystal layer 30 is selected to be 800 nm.

[0067]

[Table 2]

The structures of the phase difference plates 38 and 39 and the polarizing elements 27 and 25 on the second substrate 36 side are shown in FIG.
As shown in. That is, the axis angle of the slow axis 56 of the third retardation plate 39 is 70 degrees, and the fourth retardation plate 40 is based on the alignment direction 55 of the liquid crystal molecules closest to the second substrate 36.
The slow axis 57 of the optical element 23 has an axis angle of −10 degrees, and the polarization transmission axes α1 and α2 of the reflective polarizing element 25 and the dichroic polarizing element 27 of the optical element 23 have respective axis angles of 0 degree.
The retardation plate 39, the fourth retardation plate 40, the dichroic polarizing element 27 of the optical element 23, the retardation plate 26 of the optical element 23, and the reflective polarizing element 25 of the optical element 23 are attached in this order. The retardation of the third retardation plate 39 is 140.
nm, the retardation of the fourth retardation plate 40 is 2
70 nm is selected.

The first of the following five evaluation examples
-In the 4th example of realization, the 1st-4th phase difference plate 37-40
As an example, "NRF" (trade name) manufactured by Stock Association Morito Co., Ltd. is used. In addition, in the first to fourth examples, the dichroic polarizing element 27 may be the “EG1425” manufactured by Stock Association Nitto Denko.
DU "(trade name) is used. In addition, in the first to fourth examples, as the reflective polarizing element 25, Sumitomo 3M Co., Ltd.
The product "DBEF" (trade name) is used. "DBE
"F" is a constitution in which two kinds of polymer films are laminated,
The anisotropy of reflectance due to the anisotropy of refractive index is used.

In the following evaluation, the chromaticity and the transmittance of the display surface of the liquid crystal display device 21 to be evaluated during the transmissive white display and the reflective white display are used as the evaluation parameters.
The chromaticity is expressed by an XYZ display system, and only the x value and the y value are evaluated. In addition, the x value and the y value of the XYZ display system may be shown as “(x, y) = (p, q)” (p and q are numerical values). FIG. 4 shows a liquid crystal display device 21 to be evaluated in the first to fourth implementation examples described below.
FIG. 3 is an xy chromaticity diagram of the transparent white display of FIG.

In the following evaluation, the chromaticity of the display surface of the liquid crystal display device 21 to be evaluated at the time of displaying the reflective white color was measured using a CM-1000 (C light source 2 degree visual field) manufactured by Minolta, and red, green and blue. The chromaticity of the display surface was measured under the condition that all the pixels were in the ON state. In the following evaluation, the chromaticity of the display surface at the time of displaying the transmissive white of the liquid crystal display device 21 to be evaluated was measured by using BM-5 made by TOPCON, and all the pixels of red, green and blue are in the ON state. Then, the chromaticity of the display surface was measured. In this evaluation experiment, the chromaticity of the display surface of the liquid crystal display device 21 during the transmissive white display and the reflective white display corresponds to the chromaticity of the transmitted light of the optical element 23 in the liquid crystal display device 21.

In the present specification, "transmissive white color display" means a case where all red pixels, green pixels and blue pixels are in the ON state during transparent display. In the present specification, “displaying reflective white color” means a state in which all red pixels, green pixels, and blue pixels are in the ON state during reflective display. In the liquid crystal display device 21, all of the red, green, and blue pixels are displayed when the red pixel, the green pixel, and the blue pixel are all in the ON state regardless of whether the transmissive white display or the reflective white display is performed. Should transmit all light, and the screen color of the entire display surface should be white.

A comparative example will be described below. First,
As a reference for evaluating the chromaticity change at the time of transmissive display by the optical element 23 of FIG. 2, a retardation plate disposed between the dichroic polarizing element 27 and the reflective polarizing element 25 is used as the optical element 23 of FIG. With respect to the liquid crystal display device 21 including the reference optical element having the configuration omitted from the above, chromaticity and transmittance in the XYZ display system during transmission white color display and reflection white color display were evaluated. As a result, the chromaticity of the display surface during transmission white display was (x, y) = (0.310, 0.330). The transmittance was 2.7%. The chromaticity of the display surface during the reflective white display is (x, y) = (0.31
5, 0.339).

The chromaticity of the display surface in the transmissive white display and the reflective white display in the liquid crystal display device 21 of the comparative example is that of the reference optical element including only the dichroic polarizing element 27 and the reflective polarizing element 25. It corresponds to the chromaticity of transmitted light. The first after that
In the fourth implementation example, the x value and the y value of the chromaticity of the display surface during the transmissive white display and the reflective white display measured in the comparative example are calculated as x of the chromaticity during the transmissive white display and the reflective white display. The transmittance measured in the comparative example is used as a reference value of the transmittance and the reference value of the y value is used as a reference value of the transmittance. Further, in the following description, the difference between the measured chromaticity x and y values with respect to the reference values of the chromaticity x and y values described above is referred to as “white chromaticity change of x and y values”. Sometimes.

The first implementation example will be described below. In the first implementation example, an appropriate retardation of the retardation plate 26 of the optical element 23 is selected for the purpose of coloring the color of the transmissive display to blue without changing the chromaticity of the reflective display. The chromaticity change at the time of transmissive display is evaluated using the angle formed by the polarization transmission axes α1 and α2 of the reflective polarization element 25 and the dichroic polarization element 27 of the element 23 and the slow axis 59 of the retardation plate 26 as a parameter. It was

First, the retardation of the retardation film 26 of the optical element 23 was selected to be 410 nm, which corresponds to the wavelength of blue light. Next, an angle θ formed by the slow axis β of the retardation plate 26 of the optical element 23 with respect to the polarization transmission axes α1 and α2 of the reflective polarization element 25 and the dichroic polarization element 27 of the optical element 23.
Is 0 with reference to the polarization transmission axes α1 and α2 as 0 degrees.
It was set in each of four ways: 10 degrees, 20 degrees, and 30 degrees. After that, "the reflective polarization element 2 of the optical element 23
5 and the angle θ formed by the slow axis β of the retardation plate 26 of the optical element 23 with respect to the polarization transmission axes α1 and α2 of the dichroic polarizing element 27 is “the polarization element of the optical element 23-the retardation plate axis angle θ”. Is abbreviated.

[0077]

[Table 3]

In Table 3 (a), in the liquid crystal display device 21 of the first implementation example, when the polarization element-phase difference plate axis angle θ of the optical element 23 is set to the above-mentioned four conditions, the transmission white display and the reflection white display are performed. The results of measurement of chromaticity and transmittance of white display at the time of display are shown. Table 3 (b) shows the difference in chromaticity of Table 3 (a) with respect to the reference value of chromaticity, and the reduction rate of the transmittance of Table 3 (a) with respect to the reference value of transmittance. Table 3
(C) is an optical element 2 of the liquid crystal display device 21 of the first implementation example.
In the liquid crystal display device 21 having a configuration in which the reflective polarization element 25 of No. 3 is replaced with the dichroic polarization element 27, the transmission element displays white when the polarization element-phase difference plate axis angle θ of the optical element 23 is set to the above four conditions. The transmittance is shown. The polygonal line C1 in FIG.
9 shows changes in the x value and the y value of the color of the display surface during the transparent white display of the liquid crystal display device 21 in the first implementation example.

As a result of the evaluation experiment of the first implementation example, Table 3 (a)
And as shown in Table 3 (b), the polarization transmission axis α of the reflective polarizing element 25 of the optical element 23 and the dichroic polarizing element 27.
As the angle θ formed by the slow axis β of the retardation plate 26 of the optical element 23 with respect to 1 and α2 increases, the coloring of the transmitted light becomes stronger, and the chromaticity of the display surface during transmission white display is colored blue. You can see that Furthermore, it can be seen that the chromaticity during the reflective white display does not depend on the presence or absence of the retardation plate 26 of the optical element 23 and the polarization element-retardation plate axis angle θ of the optical element 23 and does not change. Further, as shown in Table 3 (c), under all the conditions of the polarization element-phase difference plate axis angle θ of the optical element 23, a reflective polarization element is used as compared with the case where the dichroic polarization element 27 is replaced. It can be seen that when 25 is used, the transmittance at the time of displaying transparent white is further improved by about 20%.

As described above, by setting the retardation of the retardation plate 26 of the optical element 23 of FIG. 2 to 410 nm, the display surface of the liquid crystal display device 21 of FIG. 1 during transmission white display can be colored blue. . That is, the polarization transmission axes α1 and α2 of the reflective polarization element 25 and the dichroic polarization element 27 are set so that the chromaticity of the display surface during the transmission white display of the liquid crystal display device 21 of FIG. By setting the angle θ formed by the retardation plate 26 of the optical element 23 and the slow axis β, the chromaticity of the display surface during transmissive display can be freely adjusted without impairing the chromaticity of the display surface during reflective display. And high transmittance can be obtained.

Referring to Table 3 (b), the coloring by the retardation plate 26 of the optical element 23 depends on the polarization element of the optical element 23.
When the phase difference plate axis angle θ is in the range of 0 ° to 10 °, the change in chromaticity of the white x value or y value during transmissive display is small and 0.
Since it is about 005 or less, it is difficult to visually identify a change in chromaticity. Further, when the polarization element-phase difference plate axis angle θ of the optical element 23 becomes 20 degrees or more, the chromaticity change of white x value or y value in transmissive display is larger than that in reflective display, which is about 0.02 or more. , The coloring becomes very strong. Therefore, it is desirable that the polarizing element-retarder plate axis angle θ of the optical element 23 during blue coloring is 10 degrees or more and 20 degrees or less.

The second implementation example will be described below. In the second implementation example, the first embodiment is for the purpose of coloring the color in the transmissive display to green without changing the chromaticity in the reflective display.
The evaluation was performed in the same procedure as the implementation example. First, the optical element 2
As the retardation of the retardation film 26 of No. 3, 520 nm corresponding to the wavelength of green light was selected. Next, the polarization element-phase difference plate axis angle θ of the optical element 23 is the same as in the first implementation example.
With the polarization transmission axes α1 and α2 of the reflective polarization element 25 and the dichroic polarization element 27 of the optical element 23 as 0 degrees of the reference,
It was set in each of four ways: 10 degrees, 20 degrees, and 30 degrees.

[0083]

[Table 4]

Table 4 (a) shows that in the liquid crystal display device 21 of the second implementation example, when the polarizing element of the optical element 23 and the retardation plate axis angle θ are set to the above-mentioned four conditions, transmission white display and reflection white. The results of measurement of chromaticity and transmittance of white display at the time of display are shown. Table 4 (b) shows the difference in chromaticity of Table 4 (a) with respect to the reference value of chromaticity, and the reduction rate of the transmittance of Table 4 (a) with respect to the reference value of transmittance. Table 4
(C) is an optical element 2 of the liquid crystal display device 21 of the second implementation example.
In the liquid crystal display device 21 having a configuration in which the reflective polarization element 25 of No. 3 is replaced with the dichroic polarization element 27, the transmission element displays white when the polarization element-phase difference plate axis angle θ of the optical element 23 is set to the above four conditions. The transmittance is shown. The broken line C2 in FIG.
9 shows changes in the x value and the y value of the color of the display surface during transparent white display of the liquid crystal display device 21 in the second implementation example.

As a result of the evaluation experiment of the second implementation example, Table 4 (a)
As shown in Table 4 (b), as the polarization element-phase difference plate axis angle θ of the optical element 23 increases, the transmitted light becomes more colored, and the chromaticity of the display surface during transmission white display becomes green. You can see that it is colored. Furthermore, it can be seen that the chromaticity during the reflective white display does not depend on the presence or absence of the retardation plate 26 of the optical element 23 and the polarization element-retardation plate axis angle θ of the optical element 23 and does not change. In addition, as shown in Table 4 (c), the reflective polarizing element 25 is used more than the case where the dichroic polarizing element 27 is substituted under all the conditions of the polarizing element of the optical element 23 and the retardation plate axis angle θ. It can be seen that in this case, the transmissivity during transmissive white display is improved by about 20%.

As described above, by setting the retardation of the retardation film 26 of the optical element 23 of FIG. 2 to 520 nm, the chromaticity of the display surface of the liquid crystal display device 21 of FIG. can do. That is,
The polarization transmission axes α1 and α2 of the reflective polarizing element 25 and the dichroic polarizing element 27 and the optical element so that the chromaticity of the display surface during the transmission white display of the liquid crystal display device 21 of FIG. 1 becomes a desired chromaticity. By setting the angle θ formed by the slow axis β of the retardation plate 26 of 23, it is possible to freely adjust the chromaticity of the display surface during transmissive display without impairing the chromaticity of the display surface during reflective display. And high transmittance can be obtained.

Referring to Table 4 (b), the coloring by the retardation plate 26 of the optical element 23 depends on the polarizing element of the optical element 23.
When the retardation plate axis angle θ is in the range of 0 ° to 20 °, the change in chromaticity of the white x value or y value during transmissive display is small and 0.
Since it is about 005 or less, it is difficult to visually identify a change in chromaticity. Therefore, it is desirable that the polarization element-phase difference plate axis angle θ of the optical element 23 when green is colored is 20 degrees or more. The upper limit of the polarization element-retarder plate axis angle θ of the optical element 23 at the time of green coloring is, for example, about 0.02 or more in the chromaticity change of white x-value or y-value at the time of transmissive display. It is an angle that becomes stronger.

A third implementation example will be described below. In the third implementation example, the evaluation was performed in the same procedure as in the first implementation example for the purpose of coloring the color in transmissive display to yellow without changing the chromaticity in reflective display. First, the retardation of the retardation film 26 of the optical element 23 was selected to be 580 nm corresponding to the wavelength of yellow light. Next, the optical element 23
The polarization element-retardation plate axis angle θ is set to 0 degrees with reference to the polarization transmission axes α1 and α2 of the reflective polarization element 25 of the optical element 23 and the dichroic polarization element 27, as in the first implementation example. It was set in four ways of 0 degree, 10 degrees, 20 degrees, and 30 degrees, respectively.

[0089]

[Table 5]

Table 5 (a) shows that in the liquid crystal display device 21 of the third implementation example, when the polarization element-phase difference plate axis angle θ of the optical element 23 is set to the above-mentioned four conditions, the display of transmitted white and the reflection white. The results of measurement of chromaticity and transmittance of white display at the time of display are shown. Table 5 (b) shows the difference in chromaticity of Table 5 (a) with respect to the reference value of chromaticity, and the reduction rate of the transmittance of Table 5 (a) with respect to the reference value of transmittance. Table 5
(C) is an optical element 2 of the liquid crystal display device 21 of the third implementation example.
In the liquid crystal display device 21 having a configuration in which the reflective polarization element 25 of No. 3 is replaced with the dichroic polarization element 27, the transmission element displays white when the polarization element-phase difference plate axis angle θ of the optical element 23 is set to the above four conditions. The transmittance is shown. The broken line C3 in FIG.
9 shows changes in the x value and the y value of the color of the display surface of the transmissive white display of the liquid crystal display device 21 in the third implementation example.

As a result of the evaluation experiment of the third implementation example, Table 5 (a)
Further, as shown in Table 5 (b), as the polarization element-phase difference plate axis angle θ of the optical element 23 increases, the transmitted light becomes more colored, and the chromaticity of the display surface during transmission white display becomes yellow. You can see that it is colored. Furthermore, it can be seen that the chromaticity during the reflective white display does not depend on the presence or absence of the retardation plate 26 of the optical element 23 and the polarization element-retardation plate axis angle θ of the optical element 23 and does not change. Also, Table 5 (c)
As shown in, in all the conditions of the polarization element-the phase difference plate axis angle θ of the optical element 23, a transmissive white display is obtained when the reflective polarization element 25 is used as compared with the case where the dichroic polarization element 27 is replaced. It can be seen that the transmittance at that time is further improved by about 20%.

As described above, by setting the retardation of the retardation film 26 of the optical element 23 of FIG. 2 to 580 nm, the chromaticity of the display surface of the liquid crystal display device 21 of FIG. can do. That is,
The polarization transmission axes α1 and α2 of the reflective polarizing element 25 and the dichroic polarizing element 27 and the optical element so that the chromaticity of the display surface during the transmission white display of the liquid crystal display device 21 of FIG. 1 becomes a desired chromaticity. By setting the angle θ formed by the slow axis β of the retardation plate 26 of 23, it is possible to freely adjust the chromaticity of the display surface during transmissive display without impairing the chromaticity of the display surface during reflective display. And high transmittance can be obtained.

Referring to Table 5 (b), the coloring by the retardation plate 26 of the optical element 23 depends on the polarization element of the optical element 23.
When the phase difference plate axis angle θ is in the range of 0 ° to 10 °, the change in chromaticity of the white x value or y value during transmissive display is small and 0.
Since it is about 005 or less, it is difficult to visually identify a change in chromaticity. Further, when the polarization element-retardation plate axis angle θ of the optical element 23 becomes 30 degrees or more, the chromaticity change of the x value or y value of white during transmissive display becomes large, becomes about 0.02 or more, and coloring is extremely high. Become stronger. Therefore, the polarizing element of the optical element 23 at the time of yellow coloring-the retardation plate axis angle θ
Is preferably 10 degrees or more and 30 degrees or less.

The fourth implementation example will be described below. In the fourth example of realization, evaluation was performed in the same procedure as in the first example of realization for the purpose of coloring the color in transmissive display to red without changing the chromaticity in reflective display. First, the retardation of the retardation plate 26 of the optical element 23 was selected to be 610 nm corresponding to the wavelength of yellow light. Next, the optical element 23
The polarization element-retardation plate axis angle θ is set to 0 degrees with reference to the polarization transmission axes α1 and α2 of the reflective polarization element 25 of the optical element 23 and the dichroic polarization element 27, as in the first implementation example. It was set in four ways of 0 degree, 10 degrees, 20 degrees, and 30 degrees, respectively.

[0095]

[Table 6]

Table 6 (a) shows that, in the liquid crystal display device 21 of the fourth implementation example, when the polarization element-phase difference plate axis angle θ of the optical element 23 is set to the above-mentioned four conditions, a transmission white display and a reflection white display are performed. The results of measurement of chromaticity and transmittance of white display at the time of display are shown. Table 6 (b) shows the difference in chromaticity of Table 6 (a) with respect to the reference value of chromaticity, and the reduction rate of the transmittance of Table 6 (a) with respect to the reference value of transmittance. Table 6
(C) is an optical element 2 of the liquid crystal display device 21 of the fourth implementation example.
In the liquid crystal display device 21 having a configuration in which the reflective polarization element 25 of No. 3 is replaced with the dichroic polarization element 27, the transmission element displays white when the polarization element-phase difference plate axis angle θ of the optical element 23 is set to the above four conditions. The transmittance is shown. The broken line C4 in FIG.
9 shows changes in the x value and the y value of the color of the display surface during the transparent white display of the liquid crystal display device 21 in the fourth implementation example.

As a result of the evaluation experiment of the fourth implementation example, Table 6 (a)
Further, as shown in Table 6 (b), as the polarization element-phase difference plate axis angle θ of the optical element 23 increases, the transmitted light becomes more colored, and the chromaticity of the display surface during transmission white display becomes red. You can see that it is colored. Furthermore, it can be seen that the chromaticity during the reflective white display does not depend on the presence or absence of the retardation plate 26 of the optical element 23 and the polarization element-retardation plate axis angle θ of the optical element 23 and does not change. Also, Table 6 (c)
As shown in, in all the conditions of the polarization element-the phase difference plate axis angle θ of the optical element 23, a transmissive white display is obtained when the reflective polarization element 25 is used as compared with the case where the dichroic polarization element 27 is replaced. It can be seen that the transmittance at that time is further improved by about 20%.

As described above, by setting the retardation of the retardation plate 26 of the optical element 23 of FIG. 2 to 610 nm, the chromaticity of the display surface of the liquid crystal display device 21 of FIG. can do. Also, FIG.
The polarization transmission axes α1 and α2 of the reflective polarization element 25 and the dichroic polarization element 27 and the optical element 2 so that the chromaticity of the display surface of the liquid crystal display device 21 of FIG.
By setting the angle θ formed by the slow axis β of the retardation plate 26 of No. 3, it is possible to freely adjust the chromaticity of the display surface during transmissive display without impairing the chromaticity of the display surface during reflective display. And high transmittance can be obtained.

Referring to Table 6 (b), the coloring by the retardation plate 26 of the optical element 23 depends on the polarization element of the optical element 23.
When the phase difference plate axis angle θ is within a range of 0 degrees or less, the chromaticity change of the white x value or y value during transmissive display is small and is about 0.005 or less. Therefore, it is necessary to visually identify the chromaticity change. Is difficult Further, when the polarization element-phase difference plate axis angle θ of the optical element 23 becomes 20 degrees or more, the chromaticity change of the white x value or y value in the transmissive display with respect to the reflective display is large,
It becomes about 0.02 or more, and coloring becomes very strong. Therefore, it is desirable that the polarizing element-retarder plate axis angle θ of the optical element 23 at the time of red coloring is 0 degrees or more and 20 degrees or less.

In the first to fourth examples of realization described above,
The chromaticity of the transmitted light of the optical element 23 of FIG. Can be fine-tuned. First
In the fourth implementation example, as the reflective polarization element 25, a polarization element having a structure in which two kinds of polymer films are laminated and using the anisotropy of reflectance due to the anisotropy of refractive index is used. However, even if the reflective polarizing element 25 using the cholesteric liquid crystal layer 30 and the ¼λ plate is used instead, the same effect can be obtained.

Furthermore, as described in the first to fourth implementation examples, by adjusting the polarization element-phase difference plate axis angle θ of the optical element 23, the liquid crystal display device 21 displays a display surface during transmission display. The color depth, that is, the color intensity of the transmitted light of the optical element 23 can be freely adjusted.
The lower limit of the permissible range in which the practically necessary and sufficient coloring depth of the polarizing element-retarder axis angle θ is obtained is the optical element 2 of FIG.
3 is an angle at which the transmitted light of the whole 3 causes a chromaticity change to the extent that it is difficult to visually distinguish the chromaticity change. The upper limit of the allowable range is an angle that causes a chromaticity change such that the transmitted light of the optical element 23 shown in FIG.

Specifically, the lower limit is the difference between the x value of the XYZ color system of the transmitted light color of the entire optical element 23 of FIG. 2 and the transmitted light with respect to the reference value of the x value of the chromaticity of the transmitted light. Polarizing element-position when at least one of the difference in y value of the XYZ color system of the color of transmitted light of the entire optical element 23 of FIG. It is the phase difference plate axis angle θ. Specifically, the upper limit is the difference between the x value of the XYZ color system of the color of the transmitted light of the entire optical element 23 in FIG. 2 and the chromaticity of the transmitted light with respect to the reference value of the x value of the chromaticity of the transmitted light. XY of the color of the transmitted light of the entire optical element 23 of FIG. 2 with respect to the reference value of the y value of
At least one of the difference in y value of the Z color system is 0.0
It is the polarization element-retarder plate axis angle θ in the case of 2. In this way, the polarization element-position when the difference between the x value or the y value of the XYZ color system of the color of the transmitted light of the entire optical element 23 and the reference value is in the range of 0.005 or more and 0.02 or less. If the retardation plate axis angle θ is adopted for the optical element 23, the degree of coloring of light that is incident from the reflective polarization element and transmitted through the dichroic polarization element should be controlled to a practically necessary and sufficient degree. You can

The optical element 23 and the liquid crystal display device 21 of this embodiment are examples of the optical element and the liquid crystal display device of the present invention, respectively, and can be realized in various other forms as long as the main configurations and operations are the same. can do. Further, the detailed configuration and operation of each component of the liquid crystal display device 21 of FIG. 1 are not limited to the above-described configuration and operation as long as the same effect can be obtained, and may be realized by other configuration and operation. Furthermore, the detailed configuration and operation of each component of the optical element 23 of FIG. 2 are not limited to the above-described configurations and operations as long as the same effect can be obtained, and may be realized by other configurations and operations.

[0104]

As described above, according to the present invention, the optical element for chromaticity adjustment is such that the reflection type polarizing element, the retardation plate and the dichroic polarizing element are laminated on the same optical path and The polarization transmission axis of the type polarization element is arranged to coincide with the polarization transmission axis of the dichroic polarization element. As a result, the optical element
Only by adjusting the retardation of the retardation plate, the light that enters from the reflective polarizing element side and is transmitted to the dichroic polarizing element side can be colored, and high transmittance can be achieved.

Further, according to the present invention, the retardation of the retardation plate of the optical element is selected to be equal to the wavelength of the color to be colored. As a result, the optical element can color the light transmitted through the optical element itself into a color to be colored. Furthermore, according to the present invention, a retardation plate having a retardation of 410 ± 30 nm is used for the optical element. As a result, the optical element can color light passing through the optical element itself into a bluish color. According to the invention, the optical element has a retardation of 520 ± 3.
A 0 nm retardation plate is used. As a result, the optical element can color light passing through the optical element itself into a greenish color. Furthermore, according to the present invention, a retardation plate having a retardation of 580 ± 30 nm is used for the optical element. As a result, the optical element can color the light transmitted through the optical element itself in a yellowish color. Further, according to the present invention, a retardation plate having a retardation of 640 ± 30 nm is used for the optical element.
As a result, the optical element can color the light transmitted through the optical element itself in a reddish color.

Furthermore, according to the present invention, the difference between the x value or the y value of the XYZ color system of the color of the transmitted light of the entire optical element and the reference value is within the range of 0.005 or more and 0.02 or less. In the case, the angle formed by the slow axis of the retardation plate with respect to the polarization transmission axis of the reflective polarizing element and the dichroic polarizing element,
Used in optical elements. This allows the optical element to
It is possible to easily control the degree of coloring of the transmitted light of the entire optical element to the extent necessary and sufficient for practical use.

As described above, according to the present invention, the semi-transmissive liquid crystal display device includes an illumination means, a reflection type polarization element of an optical element, a retardation plate of the optical element, a dichroic polarization element of the optical element, The semi-transmissive reflective layer, the liquid crystal layer, and the first polarizing element are 1
It has a structure in which it is laminated in this order on the optical path of a book. As a result, the liquid crystal display device can independently adjust the chromaticity of the display surface during the transmissive display without impairing the chromaticity of the display surface during the reflective display, and at the same time obtain a high transmittance. it can.

[Brief description of drawings]

FIG. 1 is a liquid crystal display device 21 according to an embodiment of the present invention.
3 is a cross-sectional view showing the schematic configuration of FIG.

2 is a cross-sectional view showing a schematic configuration of a chromaticity adjusting optical element 23 provided in the liquid crystal display device 21 of FIG.

FIG. 3 is a diagram of a comparative example and first to fourth examples of implementation.
Of the liquid crystal display device 21 of the first substrate 35 side retardation plate 37,
38 showing the relationship between the axial angles of the polarizing element 31 and the polarization element 31, and the retardation plates 26, 39, 40 on the second substrate 36 side of the liquid crystal display device 21 of FIG. 1 in the comparative example and the first to fourth implementation examples.
3A and 3B are diagrams showing a relationship between axial angles of polarizing elements 25 and 27.

FIG. 4 is an xy chromaticity diagram of colors on a display surface during transmission white display of the liquid crystal display device 21 of FIG. 1 in first to fourth implementation examples.

FIG. 5 is a cross-sectional view showing a schematic configuration of a conventional liquid crystal display device 1.

[Explanation of symbols]

21 liquid crystal display device 23 optical element 25 reflective polarizing element 26 retardation plate 27 dichroic polarizing element 30 liquid crystal layer 31 first polarizing element 32 semi-transmissive reflective layer 33 illuminating part α1 polarization transmission axis of reflective polarizing element of optical element α 2 The polarization transmission axis of the dichroic polarizing element of the optical element β The slow axis of the retardation plate of the optical element θ The retardation plate of the optical element with respect to the polarization transmission axis of the reflective polarizing element of the optical element and the dichroic polarizing element Angle formed by slow axis

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1335 510 G02F 1/1335 510 1/13363 1/13363 (72) Inventor Hiroshi Fukushima Nagaikecho, Abeno-ku, Osaka-shi, Osaka No.22 No.22 F-term in Sharp Corporation (reference) 2H042 BA03 BA20 DA01 DA02 DA04 DB01 DE00 2H049 BA02 BA06 BA17 BB03 BB62 BC22 2H091 FA02Y FA08X FA08Z FA11X FA11Z FA41Z FD06 GA16 HA10 KA02 LA16 LA30

Claims (8)

[Claims] 1. A reflective polarizing element that transmits polarized light in a predetermined reference vibration direction and reflects polarized light orthogonal to the reference vibration direction, and its own polarization transmission axis on an optical path passing through the reflective polarizing element. Is arranged so as to be parallel to the polarization transmission axis of the reflective polarizing element, and transmits polarized light in a predetermined reference vibration direction,
An optical element comprising: a dichroic polarizing element that absorbs polarized light orthogonal to the reference vibration direction; and a retardation plate disposed between the reflective polarizing element and the dichroic polarizing element. 2. The optical element according to claim 1, wherein the retardation of the retardation plate is selected to a wavelength of light corresponding to a color to be colored. 3. The retardation of the retardation plate is 38.
The optical element according to claim 2, wherein the wavelength is selected to be 0 nm or more and 440 nm or less. 4. The retardation of the retardation plate is 49
The optical element according to claim 2, wherein the wavelength is selected to be 0 nm or more and less than 550 nm. 5. The retardation of the retardation plate is 55.
The optical element according to claim 2, wherein the wavelength is selected to be 0 nm or more and less than 610 nm. 6. The retardation of the retardation plate is 61.
The optical element according to claim 2, wherein the wavelength is selected to be 0 nm or more and 670 nm or less. 7. The angle formed by the slow axis of the retardation plate with respect to the polarization transmission axes of the reflective polarizing element and the dichroic polarizing element is such that the transmitted light of the reflective polarizing element is directly the dichroic polarized light. Using the x and y values of the XYZ color system of the color of the transmitted light of the dichroic polarizing element when entering the element, the XYZ color system of the color of the transmitted light of the dichroic polarizing element is used as a reference value. Difference between x value or y value and reference value is 0.005 or more 0.0
The optical element according to any one of claims 1 to 6, wherein an angle formed by the slow axis with respect to the polarization transmission axis when it is within a range of 2 or less is selected. 8. The optical element according to claim 1, a liquid crystal layer disposed on the dichroic polarizing element side of the optical element, and a side of the liquid crystal layer opposite to the optical element. A first polarizing element, a transflective layer disposed between the dichroic polarizing element of the optical element and the liquid crystal layer, and an illuminating means disposed on the reflective polarizing element side of the optical element. A liquid crystal display device comprising: