JP2001356347A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device having a high contrast ratio which makes an easily visible multicolored display possible and which realizes a good dark display state while a voltage is applied on the liquid crystal layer. SOLUTION: The reflection type liquid crystal display device consists of a substrate 4 having a light-reflecting film 7 formed thereon, a substrate 5, a nematic liquid crystal layer 1 having positive dielectric anisotropy held between the substrates 4, 5, optical phase difference compensation plates 8, 9, and a polarizing plate 10, In this device, (1) the retardation of the optical phase difference compensation plates 8, 9 in the normal direction of the substrates, (2) the angle between the transmission or absorption axis of the polarizing plate 10 and the slow phase axis of the optical phase compensation plates 8, 9, (3) the twist angle of the liquid crystal layer 1 and (4) the product of the birefringent difference of the liquid crystal and the layer thickness of the liquid crystal layer 1 are optimized. Further, the optical phase difference compensation plates 8, 9 are controlled according to the varied conditions from the conditions of generating circularly polarized light as the incident light to the liquid crystal layer 1 so as to cancel the residual phase difference produced in while a voltage is applied on the liquid crystal layer 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in office automation (OA) equipment such as word processors and notebook computers, various video equipment and game equipment, etc., and has a structure which does not require a direct-view backlight. The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art At present, as a color display, a liquid crystal display device having features such as thinness and light weight has been put to practical use. Among the color liquid crystal display devices, a particularly widely used one is a transmission type liquid crystal display device using a light source as a background. Due to the above-mentioned features, applications are expanding in various fields.

On the other hand, as compared with the transmissive liquid crystal display device, the reflective liquid crystal display device does not require a backlight for its display, so that the power of the light source can be reduced and the space and weight of the backlight are reduced. It has features such as savings.

[0004] That is, the reflection type liquid crystal display device can reduce power consumption and is suitable for equipment aiming at lightweight and thin. For example, if the device is manufactured so that the operation time of the device is the same, not only the space and weight of the backlight can be saved, but also the power consumption is small, so that a small battery can be used. Weight reduction becomes possible. Alternatively, if the devices are manufactured so as to have the same size or weight, a dramatic increase in operating time can be expected by using a large battery.

In terms of display contrast characteristics, a CRT or the like, which is a light-emitting display device, shows a significant decrease in contrast ratio outdoors in the daytime, or a transmissive liquid crystal display device subjected to low reflection processing. However, if the ambient light such as under direct sunlight is much stronger than the display light, a significant decrease in the contrast ratio cannot be avoided.

On the other hand, the reflection type liquid crystal display device obtains display light proportional to the amount of ambient light, and is particularly suitable for outdoor use such as portable information terminal equipment, digital cameras, and portable video cameras.

While having such a very promising application field, it has a sufficient contrast ratio, reflectance, multi-coloring,
Due to insufficient performance such as high definition display and adaptation to moving images, a reflective color liquid crystal display device having sufficient practicality has not been obtained up to now.

Hereinafter, the reflection type liquid crystal display device will be described in more detail. A conventional twisted nematic (TN) type liquid crystal element has two linear polarizing plates (hereinafter simply referred to as polarizing plates).
Because of the configuration using a single sheet, the contrast ratio and the viewing angle dependency are excellent, but the reflectance is necessarily low. Also,
Since the distance between the liquid crystal modulation layer and the light reflection layer is apart from each other by the thickness of the substrate or the like, parallax occurs due to a shift in the optical path between the time of incidence and reflection of the illumination light. For this reason, in particular, in a configuration used for a normal transmission type liquid crystal display in which a single liquid crystal modulation layer is combined with a color filter having different pixels for each color element, the light traveling direction is inclined from the substrate normal direction. In this case, the color component that passes when ambient light is incident and the color component that passes after reflection are different. In such a case, a problem such as moire occurs, which is not suitable for a color high-resolution and high-definition display device.

For these reasons, a reflective color display using this display mode has not been put to practical use.

On the other hand, a guest-host type liquid crystal element (hereinafter abbreviated as GH) in which a dye is added to liquid crystal without using a polarizing plate or using only one sheet has been developed, but the dye is added. Therefore, there is a problem that reliability is lacking, and a high contrast ratio cannot be obtained because the dichroic ratio of the dye is low.

Among these, the lack of contrast is particularly
In color display using a color filter, it is necessary to combine with a color filter having high color purity in order to greatly reduce color purity. For this reason, there is a problem that the brightness decreases due to the color filter having high color purity, and the advantage of high brightness of the present system due to the absence of the polarizing plate is impaired.

[0012] Against this background, a method using a single polarizing plate (hereinafter referred to as 1) which can be expected to provide high resolution and high contrast display.
(Referred to as a two-layer polarizing plate system).

As one example, a reflection type TN (45 ° twist type) liquid crystal display device using one polarizing plate and a １ ／ wavelength plate is disclosed in Japanese Patent Application Laid-Open No. 55-48733. I have.

In this liquid crystal display device, a liquid crystal layer twisted by 45 ° is used, and by controlling an applied electric field, the plane of polarization of the incident linearly polarized light is set in a state parallel to the optical axis of the quarter-wave plate. ° Black and white display is achieved by realizing two states, different states. The configuration of this liquid crystal cell includes a polarizer, a 45 ° twist liquid crystal cell, a １ ／ wavelength plate, and a reflector from the light incident side.

Further, USP 4,701,028 (Cl
erc et al.) disclose a reflective vertical alignment type liquid crystal display device in which one polarizing plate, a １ ／ wavelength plate, and a vertical alignment liquid crystal cell are combined.

The present inventors have filed an application for a reflective parallel alignment system in which a single polarizing plate, a parallel alignment liquid crystal cell, and an optical retardation compensator are combined (Japanese Patent Laid-Open No. 6-16).
7708).

This reflection type liquid crystal display device comprises a liquid crystal cell comprising liquid crystal layers arranged in a homogeneous (parallel) arrangement, a reflector (disposed inside the liquid crystal cell below the liquid crystal layer), and a polarizing plate (above the liquid crystal cell). Arrangement) and one optical phase difference compensator (arranged between the liquid crystal cell and the polarizing plate). In this display mode, the optical path, together with the incident optical path and the output optical path, passes only twice through the polarizing plate and twice through the transparent electrode on which the absorption on the glass substrate (upper substrate) of the liquid crystal cell is unavoidable. Therefore, with the configuration of the reflection type liquid crystal display device, a high reflectance can be obtained.

Japanese Patent Application Laid-Open No. 2-236523 discloses a configuration in which a twisted nematic liquid crystal layer is disposed between a reflector (located on the inner surface of a liquid crystal cell) and one polarizing plate.

Further, Fourth Asian Symposium on Info
rmation Display (Chung-Kuang Weiet al., Proceedings
of The Fourth Asian Symposium on Information Disp
lay, 1997, p25, hereinafter abbreviated as ASID97)
A configuration is disclosed in which a 90 degree twisted nematic liquid crystal is arranged between a reflector (arranged on the inner surface of the cell) and a quarter-wave plate and a polarizer realizing a wide band.

Further, Japanese Patent Application Laid-Open No. Hei 4-116515 discloses a liquid crystal display device which receives circularly polarized light and uses it for display. As a method for obtaining circularly polarized light in a wide band, Pancharatnam has described Proc.Ind.Acad.Sci.Vol.XLI, No.
4. It is understood that a plurality of optical phase difference compensating plates are used for SecA, p130 and 1955.

[0021] Japanese Unexamined Patent Publication (Kokai) No. 6-167708,
The display principle of the single-plate polarizing plate system as disclosed in JP-A-2-236523, ASID97, and JP-A-4-116515 will be described.

The polarizing plate disposed on the incident side has a function of passing only one direction component of the linear component of the polarized light of the incident light and the exiting light and absorbing the other component in the other direction. Then, the polarization state of the incident light passing through the polarizing plate is changed by an optical phase difference compensating plate such as a λ / 4 plate or the like (Japanese Patent Laid-Open No. 6-1677).
No. 08, ASID97) or as it is (in the case of JP-A-2-236523), the light is incident on the liquid crystal layer, and when passing through the liquid crystal layer, the polarization state further changes and reaches the reflector.

Further, the light that has reached the reflection plate passes through the liquid crystal layer, the λ / 4 plate, etc., while changing the polarization state in the reverse order of the incidence, so that the final transmission azimuth of the polarization plate is changed. The ratio of the polarization component determines the reflectance of the entire liquid crystal layer. In other words, the light is brightest when the polarization state immediately before passing through the polarizing plate at the time of emission is linearly polarized light having the transmission azimuth of the polarizing plate, and darkest when being linearly polarized light having the absorption azimuth of the polarizing plate.

The necessary and sufficient conditions for realizing these states with respect to the light that enters and exits the liquid crystal display device perpendicularly are as follows. For the bright state, the polarization state on the reflector is a straight line of any direction. It is known that the light becomes polarized light, and that the light becomes a right or left circularly polarized light on a reflection plate in a dark state.

On the other hand, in a portable information device, a touch panel is an effective input means in addition to a conventionally used keyboard. In particular, in languages that require input from the keyboard to be converted, for example, in Japanese, etc., with the advancement of information processing capabilities and software development, the touch panel has not been used as a mere pointing device. It has become common to use it as an input device for input or the like.

In the case of such an input mode, the input device is arranged so as to overlap the front surface of the display device. However, in a reflective liquid crystal display device, since reflected light is used for display, the means for low reflection processing of the touch panel must not impair the display of the reflective liquid crystal display device provided below. For example, Japanese Patent Application Laid-Open No. 5-127822 discloses that a タ ッ チ パ ネ ル wavelength plate and a polarizing plate are overlaid on a touch panel to perform low reflection processing.

[0027]

However, among the above-mentioned prior arts, in the liquid crystal display device described in Japanese Patent Application Laid-Open No. 55-48733, it is necessary to provide a quarter-wave plate between the liquid crystal layer and the reflector. However, in principle, it is difficult to form a reflective film inside the liquid crystal cell, and it is not suitable for high resolution and high definition display.

The vertical alignment type liquid crystal display device described in US Pat. No. 4,701,028 has the following problem. First, vertical alignment, particularly tilted vertical alignment, is extremely difficult to control. To realize such control, the configuration becomes complicated, so that it is not suitable for mass production. In addition, the vertical alignment has a disadvantage that the response speed is slow.

In the reflection type parallel alignment method, coloring was caused due to wavelength dispersion between the liquid crystal cell and the optical retardation compensator. As described above, the conventional configuration has a problem that coloring tends to occur in the dark state and black and white cannot be realized.

Further, in the configurations of JP-A-2-236523 and JP-A-4-116515, the reflectance in the bright state is higher than that of the configuration using two polarizing plates.
Excellent black display, in which the transmittance of the dark state greatly depends on the wavelength, has not been realized.

Further, in the display mode disclosed in the above-mentioned ASID 97, black-and-white display is possible, but there is no disclosure of the configuration of a quarter-wave plate manufactured in a wide band in this document.

In addition, according to a report by Pancharatnam, it is not practical because three optical phase difference compensators must be used to obtain good circularly polarized light. Further, no detailed study has been made on combining this with a liquid crystal display device.

On the other hand, in the reflective liquid crystal display device integrated with the touch panel, even if the performance practicable as the reflective liquid crystal display device is realized, there is a problem that the visibility is extremely deteriorated when the touch panel is arranged. .

That is, the decrease in visibility when a touch panel is disposed in a transmissive liquid crystal display device or another light emitting display device causes light reflected from the touch panel to be reflected by a light source (for example, a ceiling light). In contrast, in the reflective display device, the same light source causes reflection of the touch panel, and serves as a display light source of the display device, as compared to that which can be easily solved by removing or changing its direction. The above solution cannot be solved. Therefore, the solution to this decrease in visibility is
Along with the realization of the display device, it holds the key to the realization of a practical low power consumption portable information device.

The configuration of the touch panel disclosed in Japanese Patent Application Laid-Open No. 5-127822 has an effect of preventing reflection by the function of a quarter-wave plate, but it has an ordinary one-touch structure.
The 波長 wavelength plate has an excellent antireflection function for a specific wavelength in the visible region, but a reduction in the antireflection ability at wavelengths around that wavelength is inevitable. Further, the brightness of the display is determined by the extent to which the polarization state of the display device provided below includes the transmitted light component of the circular polarizer obtained by the combination of the 波長 wavelength plate and the polarizing plate.

That is, when a display device having substantially no polarization characteristics (for example, a white tailor type guest-host liquid crystal display device in which a 360-degree twisted liquid crystal is mixed with a dye) is used in the lower portion, the reflection efficiency becomes lower than the front surface of the touch panel. Due to the transmittance of the polarizing plate, it becomes at most half when the touch panel is not used. As another example, the same applies to a case where the lower display device uses linearly polarized light for display (for example, a TN type or STN type liquid crystal display device in which a polarizing plate is further disposed in a gap between a touch panel and a liquid crystal cell). The efficiency is up to half that of the case where no touch panel is used. Further, in the case of this example, since the phase difference of the quarter-wave plate depends on the wavelength of light, the arrangement is such that it is sandwiched between polarizing plates, and the color tone changes. In any case, the brightness is insufficient, and it is not suitable as a combination with a reflective liquid crystal display device having no means for improving the brightness of background light or the like.

From these facts, Japanese Patent Application Laid-Open No. 5-12782 discloses
Further improvement of the anti-reflection function of the touch panel described in Japanese Patent Publication No. 2 is required, and this publication discloses a suitable configuration for utilizing external light incident on such a touch panel for a reflective liquid crystal display device. It has not been.

An object of the present invention is to solve the problems of a single-polarizer-type reflective liquid crystal display device capable of displaying a high resolution, and to provide a color liquid crystal display having a high contrast ratio and excellent visibility so as to be easily viewed. It is to provide a device.

[0039]

In order to achieve the above object, a reflection type liquid crystal display device of the present invention is sandwiched between a first substrate having light reflectivity and a second substrate having light transmittance. It has a liquid crystal layer composed of nematic liquid crystal with a positive dielectric anisotropy and twisted orientation, and a linear polarizer (hereinafter, a polarizer), and selectively transmits approximately circularly polarized light in either right or left direction from natural light. A circularly polarizing means, wherein at least the first substrate, the liquid crystal layer, and the circularly polarizing means are stacked and arranged in this order, and the circular light that emits circularly polarized light when natural light enters the circularly polarizing means. The main surface of the polarizing means is provided on the liquid crystal layer side, and the product of the birefringence difference of the liquid crystal of the liquid crystal layer and the liquid crystal layer thickness is 85 nm or more and 350 nm or less, more preferably 150 nm or more and 350 nm or less, and , The liquid crystal layer Twist angle twist angle of 0 degrees greater than 100 degrees or less in the range of the liquid crystal layer, a configuration and more preferably in a range of 100 degrees from 45 degrees.

The reflection type liquid crystal display device of the present invention is based on a single polarizing plate type reflection type liquid crystal display device which can realize a high resolution display which can be constructed without generating parallax. As a result of various investigations that can electrically switch different polarization states on the reflector necessary for realizing
A good dark state is achieved without requiring high precision in the liquid crystal layer manufacturing process by configuring the liquid crystal display device with a circular polarization means so as to realize the dark state of the liquid crystal display with a voltage applied. I found what was possible.

Further, among those which realize a sufficiently bright state at a low voltage state by using a circularly polarizing means for realizing such a polarization state, the liquid crystal layer is designed as described above, and thus, the above-mentioned conventional technique is improved. Have also found a reflective liquid crystal display device that can be manufactured more easily.

That is, according to the above configuration, the problem in the conventional configuration is solved by adopting the circularly polarizing means and the liquid crystal layer and by arranging them as described above.
A reflection type liquid crystal display device having excellent display characteristics can be realized.

In the reflection type liquid crystal display device having the above structure,
The circularly polarizing means uses an optical phase difference compensating plate, and the optical phase difference compensating plate is in a state where a voltage is applied to the liquid crystal layer from a condition that incident light to the liquid crystal layer is circularly polarized. The dark state may be set by setting a condition changed by an amount to cancel the generated residual phase difference.

That is, the reflection type liquid crystal display device of the present invention is sandwiched between at least a first substrate having a light reflecting means and a second substrate having a light transmitting property, and has a positive dielectric anisotropy and an alignment property. A liquid crystal layer made of a divided nematic liquid crystal, and a circularly polarizing means having at least one linear polarizing plate and selectively transmitting any of substantially circularly polarized light from natural light in the left and right directions, and at least the light reflecting means as described above. , A liquid crystal layer and a circularly polarizing means are stacked and arranged, and a surface for emitting circularly polarized light when natural light is incident on the circularly polarizing means is provided on the liquid crystal layer side. A reflective liquid crystal display device in which the product of the refractive index difference and the thickness of the liquid crystal layer is 150 nm or more and 350 nm or less, and the twist angle of the liquid crystal layer is in a range of 45 degrees to 100 degrees, , Optical phase difference The optical phase difference compensating plate is used for canceling the residual phase difference that occurs when a voltage is applied to the liquid crystal layer from the condition that the incident light on the liquid crystal layer becomes circularly polarized light. It is characterized in that a dark state is set by setting the changed condition.

Further, the reflection type liquid crystal display device of the present invention comprises:
Sandwiched between at least a first substrate having light reflecting means and a second substrate having light transmissivity, and having a positive dielectric anisotropy;
A liquid crystal layer comprising an oriented nematic liquid crystal; and a circularly polarizing means having at least one linearly polarizing plate and selectively transmitting any one of substantially circularly polarized light from natural light to the left and right. Means, a liquid crystal layer, a circularly polarized light means are stacked and arranged, and a surface for emitting circularly polarized light when natural light enters the circularly polarized light means is provided on the liquid crystal layer side, and the liquid crystal of the liquid crystal layer is A reflective liquid crystal display device, wherein the product of the birefringence difference and the thickness of the liquid crystal layer is 85 nm or more and 350 nm or less, and the twist angle of the liquid crystal layer is in a range of more than 0 degree and 100 degrees or less. The polarizing means uses an optical phase difference compensating plate, and the optical phase difference compensating plate has a residual state generated when a voltage is applied to the liquid crystal layer due to a condition that incident light to the liquid crystal layer becomes circularly polarized light. Cancel phase difference It is characterized in that the dark state is set to only the changed condition that minute.

According to each of the above-described structures, the problems in the conventional structure can be solved, and a reflection type liquid crystal display device having excellent display characteristics can be realized. The generated residual phase difference can be canceled, and good dark display can be realized in a state where a voltage is applied to the liquid crystal layer.

In the above-mentioned reflection type liquid crystal display device, the circularly polarizing means is arranged in this order from the liquid crystal layer side.
The retardation in the normal direction of the substrate is 100 nm or more and 180.
a first optical phase difference compensating plate set to not more than nm and a retardation in a direction normal to the substrate being not less than 200 nm and not more than 360 nm.
The optical system comprises a second optical phase difference compensating plate set as follows and a polarizing plate, and an angle between a transmission axis or an absorption axis of the polarizing plate and a slow axis of the first optical phase difference compensating plate is θ1. When the angle between the transmission axis or absorption axis of the polarizing plate and the slow axis of the second optical phase difference compensator is θ2, the value of | 2 × θ2−θ1 | is 35 degrees or more and 55 degrees or less. It is desirable that

In this preferred configuration, a configuration of a polarizing plate and an optical phase difference compensator has been found as a configuration of a circularly polarizing device for realizing the above-mentioned polarization state. Can convert light in a substantially visible wavelength region into circularly polarized light. The transmission axis and the absorption axis of the polarizing plate are orthogonal to each other.

In the above-mentioned reflection type liquid crystal display device, the circularly polarizing means has a retardation in a direction normal to the substrate of 100.
a first optical phase difference compensating plate set to not less than 180 nm and not more than 180 nm, and a retardation in a direction normal to the substrate is 200 nm.
A second optical phase difference compensating plate set to at least 360 nm and a linear polarizing plate, and a transmission axis or absorption axis of the linear polarizing plate and a slow axis of the first optical phase difference compensating plate. When the angle between the transmission axis or absorption axis of the linear polarizing plate and the slow axis of the second optical phase difference compensator is θ2, the value of | 2 × θ2−θ1 | 35
And 55 ° or less, and the retardation of the first optical retardation compensator is such that a voltage is applied to the liquid crystal layer from the retardation capable of giving a phase difference of only a quarter wavelength in the entire visible wavelength region. The retardation of the second optical phase difference compensator is set to a retardation changed by an amount to cancel the residual phase difference generated in the state where the phase difference is generated, and the retardation of the second optical phase difference compensator gives a phase difference of only a half wavelength in the entire visible wavelength region. The retardation that can be set may be set.

In the above-mentioned reflection type liquid crystal display device, the circularly polarizing means comprises: a first optical phase difference compensator having a retardation in a direction normal to the substrate of 100 nm or more and 180 nm or less; 2 retardation
A second optical phase difference compensator set to a value of not less than 00 nm and not more than 360 nm, and a linear polarizer, and a transmission axis or an absorption axis of the linear polarizer and a retardation of the first optical phase difference compensator. The value of | 2 × θ2−θ1 | when the angle between the transmission axis or the absorption axis of the linear polarizing plate and the slow axis of the second optical phase difference compensator is θ2, where θ1 is the angle formed with the axis. Is not less than 35 degrees and not more than 55 degrees, and the direction of the slow axis of the first optical phase difference compensator is parallel to the liquid crystal alignment direction at the center of both end faces in the thickness direction of the liquid crystal layer. The retardation of the optical phase difference compensating plate is set to be 10 nm to 50 nm smaller than the retardation capable of giving a phase difference of only one quarter wavelength in the entire visible wavelength region. The retardation of Alternatively, the retardation may be set such that a phase difference of only a half wavelength can be given in the entire visible wavelength region.

Further, in the above-mentioned reflection type liquid crystal display device, the circularly polarizing means comprises: a first optical phase difference compensator having a retardation in a direction normal to the substrate of 100 nm or more and 180 nm or less; 2 retardation
A second optical phase difference compensator set to a value of not less than 00 nm and not more than 360 nm, and a linear polarizer, and a transmission axis or an absorption axis of the linear polarizer and a retardation of the first optical phase difference compensator. The value of | 2 × θ2−θ1 | when the angle between the transmission axis or the absorption axis of the linear polarizing plate and the slow axis of the second optical phase difference compensator is θ2, where θ1 is the angle formed with the axis. Is not less than 35 degrees and not more than 55 degrees, and the azimuth of the slow axis of the first optical phase difference compensator is orthogonal to the liquid crystal alignment direction at the center of both end faces in the thickness direction of the liquid crystal layer. The retardation of the optical phase difference compensator is set to be 10 nm to 50 nm larger than the retardation capable of giving a phase difference of only a quarter wavelength in the entire visible wavelength region. Retardation is possible 1/2 over the entire visible wavelength range
The retardation may be set so that a phase difference of only the wavelength can be given.

According to each of the above-described structures, the problems of the conventional structure can be solved, and a reflection type liquid crystal display device having excellent display characteristics can be realized. The generated residual phase difference can be canceled by the two optical phase difference compensating plates, and a good dark display can be realized with a voltage applied to the liquid crystal layer.

In the above-mentioned reflection type liquid crystal display device, the twist angle of the liquid crystal layer is in the range of 60 to 100 degrees, and the product of the birefringence difference of the liquid crystal of the liquid crystal layer and the thickness of the liquid crystal layer. 250 nm or more and 330 nm or less, and the angle θ3 between the alignment direction of the liquid crystal molecules near the second substrate and the transmission axis or absorption axis of the polarizing plate is 20 to 70 degrees or 110 to 150 degrees. It is desirable to have a configuration.

According to this configuration, the product of the difference in the birefringence of the liquid crystal in the liquid crystal layer and the thickness of the liquid crystal layer is large, so that the selection range of the liquid crystal material is widened and the thickness of the liquid crystal layer is easily controlled. By setting θ3 as described above, it is possible to realize a reflection type liquid crystal display device with high display quality in which contrast, coloring of white display and coloring of black display are suppressed.

Further, in the above-mentioned reflection type liquid crystal display device, the first substrate having light reflectivity has a light reflection film, and the light reflection film has a smooth and continuously changing uneven shape. It is desirable to have a structure made of a conductive material.

According to this structure, there is no unnecessary scattering, and a disturbing action on polarized light (depolarization) as in the case of a flat mirror surface, so as not to impair the reflectivity modulation method capable of high-resolution display of the reflective liquid crystal display device. As a diffusive reflection plate having no function, a significantly more effective reflection characteristic can be realized as compared with a case where a scattering plate is arranged on the front surface of a display device using a specular reflection plate having no diffusivity. Further, since the light reflecting film is made of a conductive material, the light reflecting film can also function as a voltage applying electrode to the liquid crystal layer in cooperation with the transparent electrode of the second substrate.

Further, it is desirable that the concavo-convex shape provided on the light reflecting film has a different directivity depending on the azimuth in the plane of the substrate.

This desirable structure has been made by finding that the average period of the concave and convex shapes provided on the light reflecting film characterizes the diffusive reflection characteristic, that is, to uniformly diffuse the incident light. The average irregularity period is similarly set for an arbitrary direction in the plane of the reflector, and this period is changed for a specific direction in the plane, so that the illumination light from the specific direction is reflected in the specific direction. This makes it possible to increase the reflectance in the case. This configuration is particularly effective in the reflective liquid crystal display device of the present invention in which a better dark state is realized as compared with the guest-host system, and makes it possible to realize a brighter reflective liquid crystal display device. is there.

In the above-mentioned reflection type liquid crystal display device, at least one third optical phase difference compensating plate for eliminating a residual phase difference of the liquid crystal layer is provided between the circularly polarizing means and the liquid crystal layer. It is desirable to have the configuration provided.

This desirable configuration is such that, when the voltage applied to the liquid crystal layer is finite, even if the maximum voltage is applied to the liquid crystal layer and the display is dark, a slight voltage is applied according to the component parallel to the liquid crystal alignment substrate. A residual phase difference, which is a polarization conversion effect, remains, and it is made in view of eliminating this. Third
Eliminating the residual phase difference by the optical phase difference compensating plate realizes a good black display at a practical maximum voltage. A similar effect can be achieved by adjusting the retardation of the second optical phase difference compensator.

In the above-mentioned reflection type liquid crystal display device, it is preferable that at least one of the third optical phase difference compensating plates provided between the circularly polarizing means and the liquid crystal layer has an inclined optical axis. It is preferable to have a configuration in which a three-dimensionally oriented optical axis having continuously different inclination directions is provided inside.

In a method of realizing a good dark display at the maximum value of the actually driven voltage and thereby obtaining a good display, a method of obtaining a good display by applying a sufficient voltage to the liquid crystal layer is not sufficient. It is effective to compensate for refraction,
For this purpose, the viewing angle can be increased by expanding the observation angle range in which the residual birefringence of the liquid crystal layer can be favorably canceled.

In order to realize this, in this configuration, at least one of the third optical phase difference compensating plates is designed in consideration of the three-dimensional arrangement of the orientation of the liquid crystal, thereby having better display characteristics. A reflective liquid crystal display device can be realized.

In the above-mentioned reflection type liquid crystal display device, the first and second optical phase difference compensating plates each have a refractive index anisotropy Δn (450) for light having a wavelength of 450 nm and a refractive index for light having a wavelength of 650 nm. Rate anisotropy Δn (65
0) and the refractive index anisotropy Δn for light having a wavelength of 550 nm.
(550) is a configuration (first configuration) that satisfies 1 ≦ Δn (450) / Δn (550) ≦ 1.06 0.95 ≦ Δn (650) / Δn (550) ≦ 1. Preferably
More desirably, the configuration (second configuration) satisfies 1 ≦ Δn (450) / Δn (550) ≦ 1.007 0.987 ≦ Δn (650) / Δn (550) ≦ 1.

According to the first configuration, although there is a slight reduction in contrast due to the improvement of the reflectance in the bright state and a slight coloring in the bright state required for the reflection type liquid crystal display device, the contrast 10 that can sufficiently withstand use is obtained. : 1 or more can be achieved.
According to the second configuration, it is possible to further reduce the coloring compared to the first configuration and to achieve a contrast of 15: 1 or more.

In the above-mentioned reflection type liquid crystal display device, the twist angle of the liquid crystal layer is in the range of 65 ° to 90 °, and the product of the birefringence difference of the liquid crystal of the liquid crystal layer and the thickness of the liquid crystal layer. Is not less than 250 nm and not more than 300 nm, and the angle θ formed between the alignment direction of the liquid crystal molecules in the vicinity of the second substrate (in contact with the second substrate) and the transmission axis or the absorption axis of the polarizing plate.
It is desirable that 3 be 110 degrees or more and 150 degrees or less.

According to this configuration, the voltage for driving the liquid crystal layer can be further reduced, and a good white display can be realized.

In the reflection type liquid crystal display device, the angle θ3 between the orientation direction of the liquid crystal molecules near the second substrate and the transmission axis or absorption axis of the polarizing plate is 110 degrees or more and 150 degrees or more.
And the observation direction is desirably set to a direction in a plane including a direction at 90 degrees from the alignment direction of the liquid crystal molecules near the second substrate and a normal line of the display surface.

Similarly, in the above-mentioned reflection type liquid crystal display device, the angle θ3 between the alignment direction of the liquid crystal molecules near the second substrate and the transmission axis or absorption axis of the polarizing plate is from 20 to 70 degrees. It is desirable that the azimuth is set to an azimuth in a plane including the alignment direction of the liquid crystal molecules near the second substrate and the normal to the display surface.

According to these configurations, good visibility can be ensured by setting the observation direction as described above. In other words, good visibility can be obtained by setting θ3 according to the viewing direction of the observer. Further, a member for setting the observation direction of the observer may be provided on the display surface or the like, so that good visibility can be obtained.

Further, in the above-mentioned reflection type liquid crystal display device, the angle θ3 between the alignment direction of the liquid crystal molecules on the second substrate and the transmission axis or absorption axis of the polarizing plate is 110 ° or more and 150 ° or less, The observation azimuth is set to an azimuth in a plane including a direction at 90 degrees from the orientation direction of the liquid crystal molecules near the second substrate and a normal to the display surface, and the observation azimuth is the average irregularity period of the light reflecting film. It is desirable that the orientation is set in a plane including the short orientation and the normal of the display surface among the orientations in different substrate planes.

Similarly, in the reflection type liquid crystal display device described above, the angle θ3 between the alignment direction of the liquid crystal molecules on the second substrate and the transmission axis or absorption axis of the polarizing plate is from 20 degrees to 70 degrees. The azimuth is set to an azimuth in a plane including the alignment direction of the liquid crystal molecules in the vicinity of the second substrate and the normal to the display surface, and the observation azimuth is an azimuth in the plane of the substrate having a different average unevenness period of the light reflection film. Of these, it is preferable to set a configuration in a plane including a short azimuth and a normal to the display surface.

According to these configurations, it is possible to obtain particularly excellent visibility by setting the bright azimuth of the light reflecting film, which is a diffusive reflecting plate, to the favorable azimuth as described above. Become. Although the bright direction of the diffusive reflector generally depends on the direction of the illumination and the direction of the observer, it can be arranged well under various lighting conditions.

In the above-mentioned reflection type liquid crystal display device, the angle θ3 between the alignment direction of the liquid crystal molecules near the second substrate and the transmission axis or absorption axis of the polarizing plate is from 40 degrees to 60 degrees.
And the angle θ4 between the azimuth in a plane including the observation azimuth and the normal to the display surface and the liquid crystal molecules near the second substrate is 0.
It is desirable that the configuration is set to be not less than 30 degrees and not more than 30 degrees or not less than 180 degrees and not more than 210 degrees.

According to the above configuration, good visibility can be secured by setting the observation direction as described above.
In other words, good visibility can be obtained by setting θ3 and θ4 according to the viewing direction of the observer. Further, a member for setting the observation direction of the observer may be provided on the display surface or the like, so that good visibility can be obtained.

Another object of the present invention is to solve the problem of a single-polarizer type reflection type liquid crystal display device capable of high resolution display, and to provide a color display with a high contrast ratio and excellent visibility that is easy to see. It is an object of the present invention to provide a touch panel-integrated reflective liquid crystal display device which is constituted by a reflective liquid crystal display device and does not impair the display even when the pressure sensing input device is arranged.

According to another aspect of the present invention, there is provided a touch panel-integrated reflective liquid crystal display device comprising the above-mentioned reflective liquid crystal display device. A planar pressure-sensitive element having a layered gap and sensing external pressing force is sandwiched between the circularly polarizing means and the second substrate.

In the above-mentioned reflection type liquid crystal display device of the present invention, since the light passing through the circularly polarizing means or the polarizing plate and the two optical phase difference compensating plates is substantially circularly polarized, the light is reflected more than these. Even if there is reflection without disturbing the polarization state on the plate side, the reflected light is absorbed by the polarizing plate at the time of emission. Therefore, reflected light from a pressure-sensitive input device (touch panel) useful as an input device for a portable device does not cause deterioration in visibility.

Further objects, features, and advantages of the present invention will be more fully understood from the following description. Also, the advantages of the present invention will become apparent in the following description with reference to the accompanying drawings.

[0080]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to embodiments and examples, but the present invention is not limited thereto.

[First Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing a main part of a schematic configuration of a reflection type liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 1, this reflection type liquid crystal display device has a positive polarity by a substrate 4 on which an alignment film 2 which has been subjected to an alignment treatment is formed and a substrate 5 on which an alignment film 3 which is similarly subjected to an alignment treatment is formed. The liquid crystal display device includes a liquid crystal layer 1 in which a twisted twisted nematic liquid crystal having dielectric anisotropy is sandwiched. The light reflecting film 7 is disposed on the lower substrate 5, and it is preferable that the reflecting surface of the light reflecting film 7 has a smooth uneven shape so as to maintain the polarization of the reflected light. Further, it is preferable that the smooth uneven shape is a reflecting surface of the light reflecting film 7 having a different uneven period depending on the direction.

On the upper substrate 4, a transparent electrode 6 is formed.
The light reflecting film 7 on the lower substrate 5 is formed of a conductive material and also functions as an electrode.
Thus, a voltage is applied to the liquid crystal layer 1. An active element or the like may be used as a means for applying a voltage to the electrode pair configured as described above, but is not particularly limited. In addition,
When the light reflecting film 7 does not function as an electrode, an electrode may be separately provided on the substrate 5 side.

On the display surface on the substrate 4 side of the liquid crystal driving cell composed of the substrates 4 and 5 and the liquid crystal layer 1 as described above, a circle which selectively transmits any one of left and right circularly polarized light from natural light. Polarizing means 100 is provided. In the present embodiment, the circularly polarizing means 100 includes an optical phase difference compensating plate 8, an optical phase difference compensating plate 9, and a polarizing plate 10 which are stacked and arranged in this order on the display surface on the substrate 4 side.

Hereinafter, the optical characteristics of the optical elements of the optical phase difference compensating plate 8, the optical phase difference compensating plate 9, and the polarizing plate 10 and their functions will be described.

In the reflection type liquid crystal display device of this embodiment, illumination light such as external light is incident on the liquid crystal layer 1 through the polarizing plate 10.
The illumination light is observed from the side of the polarizing plate 10 on which the illumination light is incident. Only the linearly polarized light component in a specific direction is selectively transmitted by the polarizing plate 10, and the polarization state of the incident linearly polarized light is changed by the optical phase difference compensating plates 9 and 8.

Here, the retardation of the optical phase difference compensating plate 8 in the direction normal to the substrate is 100 nm to 180 nm, the retardation of the optical phase difference compensating plate 9 in the direction normal to the substrate is 200 nm to 360 nm, and The angle between the transmission axis or absorption axis of the polarizing plate 10 and the slow axis of the optical phase difference compensating plate 8 is defined as θ1, and the transmission axis or absorption axis of the polarizing plate 10 and the slow axis of the second optical phase difference compensating plate 9 are used. When the value of | 2 × θ2−θ1 | is 35 ° or more and 55 ° or less when the angle between the light beam and θ2 is θ2, the incident light after passing through the optical phase difference compensating plate 8 becomes substantially circularly polarized light. At this time, the left or right circularly polarized light depends on the arrangement of these three optical elements (the optical phase difference compensating plate 8, the optical phase difference compensating plate 9, and the polarizing plate 10).

This will be described in more detail with respect to the case where they are arranged as shown in FIG. 2 as an example. However, in this example, the observation was made from the direction of the incident light of the reflection type liquid crystal display device. As shown in FIG.
The transmission axis of 0 is 11 and the slow axis of the optical phase difference compensator 8 is 1
3, the slow axis of the optical phase difference compensating plate 9 is set to 12, and the polarizing plate 1
The angle between the transmission axis 11 of the optical phase difference compensator 8 and the slow axis 13 of the optical phase difference compensator 8 is θ1, and the angle between the transmission axis 11 of the polarizer 10 and the slow axis 12 of the optical phase difference compensator 9 is θ2. When arranged so that θ1 = 75 ° and θ2 = 15 °, light incident on the liquid crystal display device passes through the polarizing plate 10, the optical phase difference compensating plate 9 and the optical phase difference compensating plate 8, and The incident light becomes a polarized light substantially close to clockwise circularly polarized light.

Then, the incident light incident on the liquid crystal layer 1 is
The polarization state is changed according to the polarization conversion effect of the twisted birefringent medium (liquid crystal) of the liquid crystal layer 1 arranged according to the applied voltage, and reaches the reflector. At this time, the polarization state on the light reflection film 7 is realized to be different depending on the orientation of the liquid crystal molecules.

First, the dark state will be described. When voltage is applied, the alignment state of the liquid crystal molecules is aligned with the voltage application direction, and if the light traveling in the normal direction of the device does not have a polarization conversion effect, the incident light that has been circularly polarized does not change its polarization. Since the light reaches the light reflection film 7 at first, a dark state is realized. If this dark state can be established in the entire visible wavelength range,
Black display is realized.

The present inventors have found that the following conditions are necessary in order to prepare a polarization state close to this in the visible wavelength region. That is, the optical phase difference compensating plate 8 is set to a wavelength from 400 nm, which is the main visible wavelength, to 700 nm.
A phase difference that can give a phase difference of only a quarter wavelength to light of nm, that is, a characteristic of 100 to 180 nm in retardation for light of wavelength 550 nm. The optical phase difference compensator 9 has a phase difference capable of giving a phase difference of only a half wavelength to a visible wavelength in the same range, that is, a characteristic of retardation for light having a wavelength of 550 nm from 200 nm to 360 nm. .

Then, in the arrangement of the polarizing plate 10 and the optical phase difference compensating plates 8 and 9 shown in FIG.
°, θ2 = 15 °, so | 2 × θ2−θ1 | = 4
Since it is 5 °, the condition of the following expression is satisfied.

35 ° ≦ | 2 × θ2−θ1 | ≦ 55 ° (1) It goes without saying that the values of θ1 and θ2 can be changed within a range satisfying this condition. It is desirable that the value be determined by the combination of the wavelength dispersion of the birefringence of the two optical retardation compensators 8 and 9 used. Further, according to the angle setting of the equation (1), the range of the value of | 2 × θ2−θ1 | is 20 degrees, and which value should be taken in this range is further determined by applying a voltage to the liquid crystal layer 1. It depends on the polarization conversion action of the liquid crystal layer 1 when applied. That is, it is desirable to set the optical phase difference compensating plates 8 and 9 and the liquid crystal layer 1 to be circularly polarized light on the light reflecting film 7 including the birefringence. At this time, since the polarization conversion effect of the liquid crystal layer 1 in a state where a voltage is sufficiently applied does not largely depend on the production accuracy of the liquid crystal layer 1, the production and production of the liquid crystal layer 1 are easy.

Next, the operation in the bright state will be described. The optical phase difference compensator 8, which is set as in the above equation (1),
9, a bright state is realized by converting the substantially circularly polarized incident light into linearly polarized light on the light reflecting film 7, and the vibration direction of the optical electric field of the linearly polarized light at this time depends on the light reflecting film 7 Arbitrary in the plane. That is, even if the light of the visible wavelength is in the form of linearly polarized light having a different azimuth depending on the wavelength, or even if the light is all in the same direction, a bright bright state is similarly realized.

Thus, the optical action of the liquid crystal layer 1 is changed so that the light incident on the liquid crystal layer 1 which has been substantially circularly polarized in order to realize the above-mentioned bright state is converted into linearly polarized light having an arbitrary direction in the visible wavelength range. It is important to realize it.

In consideration of the above-mentioned electric drive in which the liquid crystal layer 1 is easily manufactured and manufactured, the dark state is realized by the voltage applied state. Alternatively, the alignment state of the liquid crystal molecules changes depending on the voltage, but it is necessary to realize the liquid crystal molecules in an alignment state that is significantly different from the dark state.

As a result of intensive studies, the present inventors have found that
The range in which the action of the bright state is practically sufficient, that is, the range in which it is possible to secure sufficient brightness in the visible wavelength range and to develop a liquid crystal composition suitable for a liquid crystal display device that can be easily manufactured at a high yield. I found it.

A specific condition is that the twist angle of the twisted nematic liquid crystal of the liquid crystal layer 1 is 45 degrees or more and 100 degrees or less. The Δnd value of the product of the birefringence difference Δn of the liquid crystal and the thickness d of the liquid crystal layer 1 is 150 nm or more and 3
The range is set to 50 nm or less.

Here, more preferably, the twist angle is 6
When the difference Δn between the birefringence index Δn of the liquid crystal of the liquid crystal layer 1 and the thickness d of the liquid crystal layer 1 is equal to or more than 250,
nm or more and 300 nm or less, more preferably, the twist angle is 65 degrees or more and 90 degrees or less, and the Δnd value of the product of the birefringence difference Δn of the liquid crystal of the liquid crystal layer 1 and the thickness d of the liquid crystal layer 1. Is in the range from 250 nm to 300 nm. This more preferable range of conditions is realized by a practical liquid crystal material having Δn of the liquid crystal layer 1 of about 0.0667 even when using the manufacturing conditions of the liquid crystal display device in which the thickness of the liquid crystal layer 1 is set to 4.5 μm. It is possible to manufacture a highly practical liquid crystal display device.

Hereinafter, specific examples according to the present embodiment will be described.

Example 1 First, as Example 1, the inventors of the present application studied the setting of the liquid crystal layer by calculation in order to perform a specific design in consideration of the optical action of the liquid crystal layer. Will be described. First, in optimizing the setting of the liquid crystal layer, the setting of the liquid crystal layer was examined using the evaluation function shown in Expression (2).

[0102]

(Equation 1)

Here, s ₃ is a Stokes parameter for designating the polarization state, and is a Stokes parameter relating to the polarization state on the reflection surface of the light transmitted through the liquid crystal layer only once. The Stokes parameters used here are standardized ones.

When the intensity of light is standardized, the polarization state can be described by the Stokes parameter having three components, and s ₁ and s ₁ represent linear polarizations different from each other by 45 degrees of vibration plane. s ₂ and s ₃ representing a circularly polarized light component. s ₁ , s ₂ , s ₃ are
Takes -1 1 the following values, particularly s ₃ in the case of circular polarization ± 1, in the case of linear polarization 0, in the case of elliptically polarized light takes the value of these intermediate.

That is, the evaluation function f is obtained by squaring s ₃ , irrespective of the rotation direction of the polarized light, depending on the state of polarization on the reflecting surface, f = 0 when circularly polarized light and f = 0 when elliptically polarized light If 0 <f <1, linear polarization can be classified as f = 1.

The inventors of the present application have found that when light is incident on an arbitrary birefringent medium sandwiched between one polarizing plate and a reflecting surface exhibiting specular reflection from the polarizing plate side, f = 0 (circle) on the reflecting plate. In the case of (polarized light), it has been confirmed by analytical analysis that the reflected light is all absorbed by the polarizing plate that has passed at the time of incidence, and when f = 1, it can pass without being absorbed by the polarizing plate. I have. When the evaluation function f takes an intermediate value, a part of the reflected light is absorbed by the polarizing plate, and the remaining reflected light is transmitted through the polarizing plate, and an intermediate reflectance is displayed.

Further, the above evaluation function f is proportional to the reflectivity of a reflection type liquid crystal display device in which incident light is reflected by a reflector using such a single polarizer, and the reflection function of the single polarizer system is used. We find that rate can be evaluated. Therefore, it is possible to evaluate whether or not a good brightness can be obtained in a bright display and whether or not a good dark state can be obtained by the evaluation function f.

As described above, since the display performance can be predicted by the evaluation function f, the liquid crystal display system in which the best performance of the single-polarizer system can be expected has been intensively studied. Next, the specific method will be described.

First, in manufacturing a liquid crystal display device,
A discussion on mass productivity was made. In particular, the precision of holding the thickness of the liquid crystal layer, which determines the optical characteristics of the liquid crystal display device, has a great effect on mass productivity.

As a method of maintaining the thickness of the liquid crystal layer, a method of providing a spherical spacer having a constant particle size between substrates sandwiching the liquid crystal layer has the best balance between accuracy and practicality. However, even with this method, demanding high accuracy in the mass production process causes an increase in mass production cost. From this, it is industrially important to consider a method that does not require the accuracy of the liquid crystal layer thickness.

Further, regarding the display quality of the manufactured liquid crystal display device, it is important to consider human visual characteristics. That is, it is known that human vision has a non-linear characteristic without a proportional relationship between the intensity of light that actually stimulates the retina of the eyeball and the perceived brightness. In other words, for a certain amount of variation in the light intensity of the display device, the intensity of the stimulus applied to the retina at the same time makes it feel like a small brightness variation (in the case of a strong background stimulus), or a large brightness modulation Or when the background is a weak stimulus.
Considering such non-linear characteristics of visual perception, even if the unevenness of the reflectance is almost the same, the deterioration of the display quality is greater in the case of dark display than in the case of bright display. .

Therefore, when there are a state where the unevenness of the reflectance is large and a state where the unevenness of the reflectance is small, it is preferable to assign the state where the unevenness of the reflectance is small to the dark display and the state where the unevenness of the reflectance is large to the bright display. It is desirable from the viewpoint of producing a liquid crystal display element having a high display quality.

Further, when the voltage is sufficiently applied to the liquid crystal layer and the polarization conversion function disappears, the unevenness of the liquid crystal layer thickness hardly causes a large fluctuation of the polarization conversion function.

Considering the above three points, it is considered that good display can be obtained by assigning the orientation state to which voltage is sufficiently applied to dark display. That is, it is desirable to set a state where no voltage is applied to the liquid crystal to a bright display, and to set a state where a voltage is applied to a dark display, that is, a so-called normally white display.

Next, the setting of the optical phase difference compensator and the setting of the liquid crystal layer portion for realizing this setting will be described based on the evaluation function f.

First, when a sufficient voltage is applied to the liquid crystal layer, the liquid crystal layer has no polarization conversion effect. The characteristic required for the optical phase difference compensating plate is a characteristic in which the light is converted into circularly polarized light on the reflector that has passed through such a liquid crystal layer and reached the reflector. Here, the rotation direction of the circularly polarized light may be either.

With the above-described settings for the optical phase difference compensating plate, this characteristic can be realized in a wide wavelength band. At this time, since the polarization conversion function of the liquid crystal has disappeared, the evaluation function f becomes 0, and a good dark state is obtained.

On the other hand, in order to study the conditions for obtaining sufficient reflection brightness when no voltage is applied to the liquid crystal layer, it is necessary to set the evaluation function f Need to be evaluated. The inventors of the present application determined an evaluation function f for an orientation in which the liquid crystal layer was uniformly twisted in a state where no voltage was applied to the liquid crystal layer. As a result, when circularly polarized light is incident on the liquid crystal, it has become clear by analytically calculating s ₃ by the Jones Matrix method that the evaluation function f becomes the equation (3).

[0119]

(Equation 2)

FIG. 3 shows the wavelength at which the visibility is highest (λ = 55).
The value of the evaluation function f at 0 nm) is shown in an iso-diagram with respect to Δnd as a design parameter of the liquid crystal layer and the twist angle. In addition, since f is an even function with respect to the twist angle Φtw, f is described only for a positive value for the twist angle, but it goes without saying that the twist direction of the actual liquid crystal alignment may be left or right. No.

FIG. 3 shows a value at a single wavelength (550 nm), but the same method can be used to evaluate the visible wavelength from 380 nm to 780 nm. That is, 5
For incident light having a wavelength other than 50 nm, it is sufficient to consider that only Δn and λ of the variables of the evaluation function f are changed.

In consideration of the effect that the visual sensitivity varies depending on the wavelength as described above, by taking the overlap integral with f assuming the visual sensitivity and the standard illumination light source, more precise optimization is possible. . That is, using the visibility curve (y _BAR (λ) of the CIE1931 color matching function) and the spectral density S _D65 (λ) of the D65 standard light source in the above equation (3),
It is effective to define the equation (4).

[0123]

(Equation 3)

Here, f (λ) is calculated by the equation (3), and indicates that it has a value dependent on the wavelength λ.

The fvis defined in this way is calculated with respect to Δnd and the twist angle as in FIG.
FIG. Here, the calculation is performed in consideration of the chromatic dispersion of Δn, and Δnd on the vertical axis is a value for light having a wavelength of 550 nm.

Further, the evaluation function f by the equation (2) is displayed.
To show a value proportional to the reflectance of
y_BAR(Λ) is similarly defined in CIE1931.
x_{BA R}(Λ), z_BARBy changing to (λ),
Calculation of chromaticity becomes possible. From this, color with D65 light source
The degree (x, y) is calculated for the same parameters as in FIG.
went. The results are shown in FIGS. 5 and 6 for x and y, respectively.

According to the above examination, a satisfactory hue (x is 0.27 or more and 0.35 or less and y is 0.25 or more) in a white display with a sufficient luminous reflectance (fvis is 0.7 or more).
28 or more and 0.36 or less).
The range of nd and twist color was determined. The result is shown in FIG. From FIG. 7, it can be seen that the region where good white balance and reflectivity are obtained is a region where the twist angle is greater than 0 degree and 100 degrees or less. Also, this good area
It can be seen that the lower limit of Δnd, which is the product of the refractive index difference Δn of the liquid crystal and the thickness d of the liquid crystal layer, is 85 nm or more. Further, it can be seen that in this favorable region, the upper limit of Δnd is 315 nm or less.

As described above, the range of the parameters of the liquid crystal layer necessary for obtaining sufficient lightness and hue is determined. However, the setting of the liquid crystal layer is further restricted by the setting of the liquid crystal material and the thickness of the liquid crystal layer. I do. For this reason, not all of the range shown by oblique lines in FIG. 7 is practical. Good conditions exist even in a range slightly out of this range. This will be described in more detail.

Δn which is an optical property value of the liquid crystal material;
It is known that there is a certain correlation between the usable temperature range of the liquid crystal material. That is, a liquid crystal material used for practical use is generally adjusted to required characteristics by blending a plurality of compounds.
When n is reduced, the temperature range in which the nematic phase can be obtained is narrowed. In such a case, it is difficult to significantly narrow the operating temperature range and the storage temperature range of the liquid crystal display device. That is, the liquid crystal material Δn has a lower limit from the viewpoint of the temperature range in which the nematic phase can be stably obtained. For this reason, Δn at room temperature depends on the required temperature range and the like, but is generally at least 0.05, preferably 0.065.
The above values are required.

Further, the thickness of the liquid crystal layer is limited by the problem of the rate of occurrence of defects due to foreign matter and the like in the manufacturing process of the liquid crystal display device, the manufacturing steps of elements for driving the liquid crystal, the flatness of the substrate used, and the like. There is. Further, when the present invention is used in a part of the configuration of the present invention, there is a limitation in terms of the uneven shape of the uneven diffusion reflector disposed close to the liquid crystal layer.

As the thickness of the liquid crystal layer, in the case of a transmission type liquid crystal display device, a value of about 5 μm is used.
Production technology is established. However, making the thickness of the liquid crystal layer significantly smaller than this involves a great deal of difficulty and is not practical. Accordingly, it is useful to manufacture the liquid crystal layer with a thickness of about 3 μm or more, preferably 4 μm or more.

From the above viewpoint, it is useful to set the lower limit of Δnd, which is the product of the refractive index difference Δn of the liquid crystal and the thickness d of the liquid crystal layer, to 150 nm, preferably 260 nm or more.

Further, in the liquid crystal in the actual driving state of the liquid crystal display device, it is often driven by applying a voltage higher than the vicinity of the threshold value of the liquid crystal exhibiting the threshold characteristic. At this time, the liquid crystal is slightly inclined from the state where no voltage is applied at an applied voltage of about the threshold, and the refractive index difference in the normal direction of the substrate in the slightly inclined state appears in an actual display.

From this, it is clear that Δ is determined by the liquid crystal material.
n is one more than the effective Δn for this tilted liquid crystal.
The value can be as large as about 0%. Since the display below the threshold value of the liquid crystal is also possible, the change of the value of Δnd is
It is appropriate not to apply to the lower limit of d.

As described above, a specific calculation using the actual liquid crystal layer setting is performed. In the single-polarizer reflective liquid crystal display device, Δnd is increased from 150 nm to 350 nm with the upper limit of Δnd set to 350 nm. Twist angle from 45 degrees to 10
It has been found that setting to 0 degrees is effective.

Example 2 In Example 2, a reflective liquid crystal display having the structure shown in FIG. 1 described above was manufactured with the parameters shown in Table 1, and five samples # 2a to # 2
f was obtained.

[0137]

[Table 1]

Table 2 shows an outline of the display results of each sample.

[0139]

[Table 2]

Note that Vth is a threshold voltage at which a change in the orientation of the liquid crystal layer 1 in each sample is observed.
It takes a different value to be set to d.

As described above, the samples {2a,} whose parameters fall within the range of the reflection type liquid crystal display device of the present invention.
In 2b, the display changed from white display to black display at 3.0 × Vth from the voltage actually used, Vth. On the other hand, in the samples # 2c to # 2f whose parameters do not fall within the range of the reflection type liquid crystal display device of the present invention, the display is dark (samples # 2c and # 2c).
f), coloring was observed on the display (samples # 2d, # 2)
e).

The outline of the display shown in Table 2 was changed without changing the relative angles (θ1, θ2) between the polarizing plate 10 and the optical phase difference compensating plates 8, 9 and changing the setting θ3 of the direction with respect to the liquid crystal alignment. Alone, a large characteristic change as observed in the samples # 2a to # 2f was not observed, but rather it was confirmed that the variation was dependent on the setting of the liquid crystal layer 1 portion.

Further, a setting is made such that circularly polarized light in the opposite direction is incident on the liquid crystal (that is, 90 ° is added to θ1 and θ2 in common, or the signs of θ1 and θ2 are both reversed), Another setting that provides circular polarization (that is,
In all combinations such as (inverting sign and adding 90 degrees for both θ1 and θ2), the same display as in Table 2 was obtained.

As described above, the product of the difference between the birefringence of the liquid crystal of the liquid crystal layer 1 and the thickness of the liquid crystal layer is 150 nm or more and 350 nm or less, and the twist angle of the liquid crystal layer is 45 degrees to 100 degrees.
By setting the liquid crystal layer 1 to be in the range of degrees,
It was shown that good display was realized and limited to that range.

Examples in which the conditions for obtaining a more preferable display can be obtained and optimized are shown in the following third and fourth embodiments.

[Embodiment 3] As Embodiment 3, there will be described an example in which one twisted nematic liquid crystal has a twist angle of 90 degrees and one optical phase difference compensator having retardations of 135 nm and 270 nm, respectively.

In Example 3, a reflection type liquid crystal display having the structure shown in FIG. 1 was manufactured. The light reflecting film 7 on the substrate 5 was made of aluminum and used as a light reflecting electrode.
The liquid crystal driving cell is a liquid crystal layer 1 twisted at 90 degrees adjusted so that the thickness of the liquid crystal layer 1 becomes 4.2 μm after the introduction of the liquid crystal, and the introduced liquid crystal material is used in a normal TFT transmission type liquid crystal display. It has the same liquid crystal properties (dielectric anisotropy, elasticity, viscosity, nematic temperature range, voltage holding characteristics) as the liquid crystal used, and only Δn is 0.06
The one adjusted to 5 was used. Here, the product of the thickness of the liquid crystal layer 1 and the birefringence difference of the liquid crystal was set to be 273 nm.

The arrangement of the polarizing plate 10, the optical phase difference compensating plate 8, and the optical phase difference compensating plate 9 in this example was set as shown in FIG. In FIG. 8, 11 is the transmission axis direction of the polarizing plate 10, 12 is the slow axis direction of the optical phase difference compensator 9,
13 is a slow axis direction of the optical phase difference compensating plate 8, and 14 is the substrate 4.
Reference numeral 15 denotes the orientation of the liquid crystal molecules in contact with the alignment film 2 formed thereon, that is, in the vicinity of the alignment film 2, and 15 denotes the orientation of the liquid crystal molecules in contact with the alignment film 3 formed on the substrate 5, ie, in the vicinity of the alignment film 3. The directions are shown, and this figure is observed from the direction of the incident light of the liquid crystal display device.

As shown in FIG. 8, the angle θ1 between the transmission axis azimuth 11 of the polarizing plate 10 and the slow axis azimuth 13 of the optical phase difference compensating plate 8 is 75 ° as shown in FIG. The angle θ2 between the transmission axis azimuth 11 of the optical phase difference compensating plate 9 and the slow axis azimuth 12 of the optical phase difference compensating plate 9 is 15 °, and the alignment direction 14 of the liquid crystal molecules on the substrate 4 and the transmission axis azimuth 11 of the polarizing plate 10 are formed. The angle θ3 is 30 °.

Optical phase difference compensator 8 and optical phase difference compensator 9
The optical retardation compensator 8 has a retardation controlled from 130 nm to 140 nm with respect to transmitted light in the direction of the surface normal at a wavelength of 550 nm. The plate 9 has a controlled phase difference from 265 nm to 275 nm for similar light.

The arrangement of the optical phase difference compensators 8 and 9 is an arrangement for improving the optical characteristics with respect to the front direction of the manufactured liquid crystal display device. It is possible to change the design in consideration of this.
For example, while satisfying the set angle condition of the present embodiment shown in FIG.
Can be designed by changing at least one of the optical phase difference compensating plates 8 and 9 to a biaxial optical phase difference compensating plate. It goes without saying that the angle setting can be changed within the range of the above-described equation (1).

As the polarizing plate 10, a polarizing plate having an AR layer made of a dielectric multilayer film and having an internal transmittance of 45% was used.

FIG. 9 is a graph showing the voltage dependence of the reflectance of the reflection type liquid crystal display device having the above configuration. In order to measure the reflectance, as shown in FIG. 10, while applying a voltage to the reflective liquid crystal display device of this embodiment and driving it, the light from the illumination light source device is applied to the substrate 4 via a half mirror. The light is incident from the side, and the reflected light from the light reflecting film on the substrate 5 is detected by a photodetector. In FIG. 9, the reflectance of 100% was obtained by using the same liquid crystal display device as in the present example except that only the same polarizing plate as that of the device under test was used without using the optical phase difference compensator. It is the reflectance in the state. The luminous luminance rate (Y value) was used as the reflectance.

From the measurement results shown in FIG. 9, it can be seen that a high reflectance was obtained at a low driving voltage of about 1 V or less.

[Embodiment 4] As Embodiment 4, there will be described an example in which one twisted nematic liquid crystal layer is set to have a twist angle of 70 degrees, and one optical phase difference compensator having retardations of 135 nm and 270 nm is used.

In Example 4, a reflective liquid crystal display device having the structure shown in FIG. 1 was manufactured. The light reflecting film 7 on the substrate 5 was made of aluminum and used as a light reflecting electrode.
The liquid crystal driving cell is a liquid crystal layer 1 twisted at 70 degrees adjusted so that the thickness of the liquid crystal layer 1 becomes 4.5 μm (sample # 4a) and 4.2 μm (sample # 4b) after the introduction of the liquid crystal. The introduced liquid crystal material has the same liquid crystal properties (dielectric anisotropy, elasticity, nematic temperature range, and voltage holding characteristic) as those of the liquid crystal used in a normal TFT transmission type liquid crystal display. What was adjusted to 0.06 was used. Here, the product of the thickness of the liquid crystal layer 1 and the birefringence difference of the liquid crystal is 270 nm (sample # 4a) and 2
It was set to be 50 nm (sample # 4b).

The arrangement of the polarizing plate 10, the optical phase difference compensating plate 8, and the optical phase difference compensating plate 9 of this example was set as shown in FIG. In FIG. 11, 11 is the transmission axis direction of the polarizing plate, 12 is the slow axis direction of the optical phase difference compensator 9, 13 is the slow axis direction of the optical phase difference compensator 8, and 14 is formed on the substrate 4. Reference numeral 15 denotes the orientation of the liquid crystal molecules in contact with the aligned alignment film 2, that is, in the vicinity of the alignment film 2, and reference numeral 15 denotes the alignment azimuth of the liquid crystal molecules in contact with the alignment film 3 formed on the substrate 5, that is, in the vicinity of the alignment film 3. This figure is an observation from the direction of the incident light of the liquid crystal display device.

As shown in FIG. 11, the angle θ1 between the transmission axis azimuth 11 of the polarizing plate 10 and the slow axis azimuth 13 of the optical phase difference compensator 8 is 75 °, as shown in FIG. The angle θ2 between the transmission axis direction 11 of 10 and the slow axis direction 12 of the optical phase difference compensator 9 is 15 °, and the angle between the orientation direction 14 of the liquid crystal molecules on the substrate 4 and the transmission axis direction 11 of the polarizing plate 10. θ3 is 45 °.

Optical phase difference compensator 8 and optical phase difference compensator 9
The optical retardation compensator 8 has a retardation controlled from 130 nm to 140 nm with respect to transmitted light in the direction of the surface normal at a wavelength of 550 nm. The plate 9 has a controlled phase difference from 265 nm to 275 nm for similar light.

The arrangement of the optical phase difference compensators 8 and 9 is an arrangement for improving the optical characteristics with respect to the front direction of the manufactured liquid crystal display device. It is possible to change the design in consideration of this. For example, as a design for changing the phase difference of the optical phase difference compensating plates 8 and 9 with respect to the transmitted light in the tilt direction while satisfying the set angle condition of the present embodiment shown in FIG. 9 can be achieved by changing at least one of the plates to a biaxial optical phase difference compensator. It goes without saying that the angle setting can be changed within the range of the above-mentioned equation (1).

As the polarizing plate 10, a polarizing plate having an AR layer made of a dielectric multilayer film and having a single-unit internal transmittance of 45% was used.

The voltage dependence of the reflectance of the reflection type liquid crystal display device having the above configuration was the same as the graph shown in FIG. From this result, it is understood that a high reflectance was obtained at a low driving voltage of about 1 V or less. This reflectance was also measured by the arrangement of the measuring optical system shown in FIG. 10 similarly to the third embodiment, and 100% was measured in the third embodiment.
It was set in the same way.

Table 3 shows the contrast, white coloring and black coloring at each angle θ3 between the transmission axis of the polarizing plate 10 and the alignment direction of the liquid crystal near the upper substrate 4.

[0164]

[Table 3]

From these results, it was confirmed that a reflection type liquid crystal display device having high display quality can be realized by setting θ3 to 20 ° or more and 70 ° or less or 110 ° or more and 150 ° or less.

[Embodiment 5] As Embodiment 5, an example is shown in which one twisted nematic liquid crystal layer is set to have a twist angle of 70 degrees and one optical phase difference compensator having retardations of 135 nm and 270 nm is used.

In Example 5, a reflective liquid crystal display having the structure shown in FIG. 1 was manufactured. The light reflecting film 7 on the substrate 5 was made of aluminum and used as a light reflecting electrode.
The liquid crystal driving cell is a liquid crystal layer 1 twisted at 70 degrees adjusted so that the thickness of the liquid crystal layer 1 becomes 4.5 μm after the liquid crystal is introduced, and the introduced liquid crystal material is used for a normal TFT transmission type liquid crystal display. A liquid crystal having the same liquid crystal properties (dielectric anisotropy, elasticity, viscosity, temperature characteristics, and voltage holding characteristics) as the liquid crystal used and having only Δn adjusted to 0.0667 was used. Here, the product of the thickness of the liquid crystal layer 1 and the birefringence difference of the liquid crystal was set to be 300 nm.

The arrangement of the polarizing plate 10, the optical phase difference compensating plate 8, and the optical phase difference compensating plate 9 in this embodiment is shown in FIG.
As shown in (b), two types of settings were made to produce two types of samples. In FIGS. 12A and 12B, similarly to FIG. 8 described above, 11 is the transmission axis direction of the polarizing plate 10, 12 is the slow axis direction of the optical phase difference compensator 9, and 13 is the optical phase difference. The slow axis azimuth of the compensator 8 is in contact with the alignment film 2 formed on the substrate 4, ie, the alignment azimuth of the liquid crystal molecules in the vicinity of the alignment film 2, and 15 is in the alignment film 3 formed on the substrate 5. The directions of the orientation of the liquid crystal molecules in contact with, ie, in the vicinity of the alignment film 3, are respectively shown.

The arrangement relationship in one sample is as follows:
As shown in FIG. 12A, the transmission axis azimuth 1
1 and the slow axis azimuth 13 of the optical phase difference compensator 8 make an angle θ1 of 75 °, and an angle θ2 between the transmission axis azimuth 11 of the polarizer 10 and the slow axis azimuth 12 of the optical phase difference compensator 9 becomes 75 °. Fifteen
The angle θ3 between the orientation direction 14 of the liquid crystal molecules on the substrate 4 and the transmission axis direction 11 of the polarizing plate 10 was 40 °, and this sample is referred to as sample # 5a.

The arrangement relation in the other sample is shown in FIG.
As shown in (b), the angle θ1 between the transmission axis azimuth 11 of the polarizing plate 10 and the slow axis azimuth 13 of the optical phase difference compensator 8 is 75 °, and the optical phase difference between the transmission axis azimuth 11 of the polarizing plate 10 and the transmission axis azimuth 11 is 75 °. The angle θ2 between the compensator 9 and the slow axis direction 12 is 15 °, and the angle θ3 between the alignment direction 14 of the liquid crystal molecules on the substrate 4 and the transmission axis direction 11 of the polarizer 10 is 130 °. ,
This sample is referred to as sample # 5b. That is, sample # 5a and sample # 5b have different θ3 and θ1
And θ2 are the same.

Note that these samples # 5a, # 5b
In the same manner as in Example 3, the optical retardation compensators 8 and 9 are both made of a stretched film made of polyvinyl alcohol, and the optical retardation compensator 8 is capable of transmitting light having a wavelength of 550 nm in the surface normal direction. The optical phase difference compensator 9 has a phase difference controlled from 265 nm to 275 nm with respect to similar light. Further, as the polarizing plate 10, a polarizing plate having an AR layer made of a dielectric multilayer film and having an internal transmittance of 45% was used.

FIG. 13 is a graph showing the voltage dependence of the reflectance of the reflective liquid crystal display device (samples # 5a and # 5b) having the above-described configuration. In FIG. 13, curve 13-
1 indicates the measurement result of sample # 5a, and curve 13-2 indicates the measurement result of sample # 5b. The reflectance was measured by the arrangement of the measuring optical system shown in FIG. 10 in the same manner as in the third embodiment, and 100% was set in the same manner as in the third embodiment. From the measurement results shown in FIG. 13, it was found that a high reflectance was obtained at a low driving voltage of about 1.5 V or less, and in particular, the sample # 5a shown by the curve 13-1 was obtained.
Has higher reflectivity.

The results of examining the voltage reflectance characteristics of the reflective liquid crystal display device of Example 5 (samples # 5a and # 5b) and the reflective liquid crystal display device of Example 3 described above are shown in Table 1. It is shown in FIG.

[0174]

[Table 4]

From Table 4, it can be seen that sufficient reflectance in the bright state and contrast ratio were achieved in all cases, and that the reflection type liquid crystal display device was also good in visual observation.

In Table 4, the contrast ratio is
It is defined by dividing the reflectance in the bright state by the reflectance in the dark state. Here, as the applied voltage in the bright state, a voltage having the highest reflectance in each embodiment is used, and in the dark state, the applied voltage is 3 V.
Set to.

[Embodiment 6] As Embodiment 6, in the reflection type liquid crystal display device manufactured under the same conditions as in Embodiment 4 described above, the wavelengths of the optical phase difference compensating plates 8 and 9
Anisotropy of refractive index Δn (450) for light of 50 nm and anisotropy of refractive index Δn (65 for light of wavelength 650 nm).
0) and refractive index anisotropy Δn for light having a wavelength of 550 nm
Δn (450) / Δn (55)
0) and Δn (650) / Δn (550) are Δ Δ
n (450) / Δn (550) and Δn (650) / Δn
The combination of (550) is (1,1), (1.003,0.
993), (1.007, 0.987), (1.01,
0.98), (1.03, 0.96), (1.06,
0.95) and (1.1, 0.93). Table 5 shows the measurement results.

[0178]

[Table 5]

From this result, 1 ≦ Δn (450) / Δn
(550) ≦ 1.06, 0.95 ≦ Δn (650) / Δ
By setting so as to satisfy the relationship of n (550) ≦ 1, a reflection type liquid crystal display device having high display quality can be realized, and 1 ≦ Δn (450) / Δn (550) ≦
1.007, 0.987 ≦ Δn (650) / Δn (55
It has been confirmed that by setting the relationship of 0) ≦ 1, a reflective liquid crystal display device with higher display quality can be realized.

[Embodiment 7] As Embodiment 7, in a reflection type liquid crystal display device manufactured under the same conditions as in Embodiment 4 described above, a reflection plane shown in FIG. Orientation 16 and direction 1 of liquid crystal molecules near the second substrate
The brightness, the contrast, the coloring, and the comprehensive evaluation were performed at each angle of the angle θ4 with 4. FIG. 15 shows the evaluation results. From this result, θ4 is 0 degree or more and 30 degrees or less or 18
By setting the angle between 0 degrees and 210 degrees, the brightness,
It has been confirmed that it is possible to realize a reflective liquid crystal display device having high display quality and excellent in contrast and color difference from an achromatic axis.

[Eighth Embodiment] In an eighth embodiment, an example will be described in which a light reflection film having smooth irregularities is used by a driving method based on an active matrix method.

FIG. 16 is a cross-sectional view of a principal part showing the structure of the reflection type liquid crystal display device of this embodiment. As shown in FIG.
The reflection type liquid crystal display device 16 includes a first substrate 5 and a second substrate 4 made of transparent glass, and a TFT element 17 is formed on each pixel as an active element on the first substrate 5. An interlayer insulating film 18 is formed on the TFT element 17 and the driving wiring (not shown), and the drain terminal (not shown) of the TFT element 17 and the light-reflective pixel electrode 19 are electrically connected via a contact hole. Connected to. On the light reflective pixel electrode 19, the alignment film 3 is formed with a thickness of 100 nm.

Here, the light-reflective pixel electrode 19 can be made of a conductive metal material such as aluminum, nickel, chromium, silver or an alloy using the same, and has light reflectivity. The shape of the light-reflective pixel electrode 19 has smooth irregularities except for the portion of the contact hole, and prevents the metal reflection surface from becoming a mirror surface.

Next, the forming method will be described in more detail.

A large number of large projections 20 and a large number of small projections 21 made of a photosensitive resin material were formed on the surface of the substrate 5 on which the TFT element 17 and the driving wiring (not shown) were formed. These large projections 20 and small projections 21 are formed by forming a large number of circular patterns having bottom diameters D1 and D2 (see FIG. 16) by photolithography. D1 and D2 are, for example, 5 μm and 3 μm, respectively.
Is set to The distance D3 is set to at least 2 μm. Further, the height of these projections can be controlled by the film thickness when the photosensitive resin material is formed. In this embodiment, the height is set to 1.5 μm.
Through the firing process, the protrusions were formed into gentle protrusions.

Next, the projections 20 and 21 are covered, and a flat portion between the projections 20 and 21 is filled.
The smoothing film 22 was formed from the same photosensitive resin material. In this way, the surface of the smoothing film 22 was formed into a smooth curved surface under the influence of the projections 20 and 21, and the desired shape was obtained. The contact hole is formed so that neither the protrusion nor the smoothing film 22 is formed.

By manufacturing the TFT element substrate 23 having the above-described structure, the light-reflective pixel electrode 19 is also disposed near the liquid crystal layer 1 also serving as a reflector, so that no parallax is generated, and Light reflective pixel electrode 19 passing through layer 1
The light reflected by the TFT element 17 and the element driving wiring (not shown) is not damaged,
TF of bright reflective liquid crystal display device with high aperture ratio
The T element substrate 23 was realized.

On the other hand, on the other substrate used together with the TFT element substrate 23, a color filter 24 of high brightness was arranged in accordance with the reflection method. The color filter 24 is provided with a black matrix 25 for preventing mixing of colors between the pixels and preventing leakage of reflected light in dark display due to a voltage non-applied portion between pixel electrodes and electric field disturbance. I have.

The light incident on the black matrix 25 has already become substantially circularly polarized light, and the reflected light from the black matrix 25 is again subjected to the action of the optical phase difference compensating plate at the time of emission, and is absorbed by the polarizing plate. Even when a low-cost metal film or the like is used, the black matrix 25 does not generate reflected light and does not deteriorate visibility. It is needless to say that a low-reflection process is further applied to the black matrix 25 for display with higher contrast.

The transparent electrode 6 is provided on the color filter 24.
Then, ITO (Indium Tin Oxide) was deposited as a mask by sputtering to form a counter electrode 6 of a light reflective pixel electrode 19 for driving a TFT element having a desired pattern with a thickness of 140 nm. Then, an alignment film 2 was formed thereon to form a color filter substrate 26.

Even if the thickness of the transparent electrode 6 is other than 140 nm, the light reflected by the incident light without reaching the liquid crystal layer 1 due to the interference effect of the thickness of the transparent electrode 6 can be compensated for by optical phase difference. Since the light is absorbed by the plates 8 and 9 and the polarizing plate 10, the visibility is not impaired without affecting the dark state.

The color filter 24 used at this time is properly designed so as to have a brightness suitable for a high contrast display mode using a polarizing plate. When the aperture ratio of the black matrix 25 is 90%, The transmittance of the color filter substrate 26 was 50% in Y value.

The thus prepared TFT element substrate 23
And the color filter substrate 26 are subjected to an alignment process by a rubbing method, and are disposed in opposition to each other through a process of dispersing a plastic spacer (not shown) for maintaining the thickness of the liquid crystal layer 1 and a seal disposing process at a peripheral edge portion. After alignment, the mixture was cured under pressure and sealed, and a liquid crystal cell for liquid crystal injection was prepared. Then, a liquid crystal material having a positive dielectric anisotropy Δε was introduced into the liquid crystal layer 1 by a vacuum injection method. Hereinafter, the expression of the azimuth of the liquid crystal display device is described as the direction of the clock face in the up, down, left, and right directions of the observer facing the device, and the 12 o'clock direction as the up direction.

On the opposite side of the color filter substrate 26 from the liquid crystal layer 1, there are provided an optical phase compensating plate 8 and an optical phase difference compensating plate 9 made of a stretched film made of polyvinyl alcohol. A polarizing plate 10 is provided.

In this embodiment, the arrangement of the polarizing plate 10, the optical phase difference compensating plate 8, and the optical phase difference compensating plate 9 constituting the circularly polarizing plate 100 was set as shown in FIG. FIG.
In 7, 11 is the transmission axis direction of the polarizing plate 10, 12 is the slow axis direction of the optical phase difference compensator 9, 13 is the slow axis direction of the optical phase difference compensator 8, and 14 is formed on the color filter substrate 26. 15 denotes the orientation of the liquid crystal molecules in contact with the aligned alignment film 2, ie, the orientation of the liquid crystal molecules in the vicinity of the alignment film 2, and 15 denotes the orientation of the orientation of the liquid crystal molecules in the vicinity of the alignment film 3, ie, in the vicinity of the alignment film 3. Are respectively shown. Here, the alignment direction 14 of the alignment film 2 on the color filter substrate 26 is made to be the 3 o'clock direction of the apparatus.

As shown in FIG. 17, the angle θ1 between the transmission axis azimuth 11 of the polarizing plate 10 and the slow axis azimuth 13 of the optical phase difference compensator 8 is 75 °, as shown in FIG. The angle θ2 between the transmission axis azimuth 11 of 10 and the slow axis azimuth 12 of the optical phase difference compensator 9 is 15 °, the orientation direction 14 of the liquid crystal molecules on the color filter substrate 26 and the transmission axis azimuth 11 of the polarizing plate 10 Is set to 130 °.

The liquid crystal layer 1 has a thickness of 4.0 after the introduction of the liquid crystal material.
A liquid crystal layer adjusted to have a layer thickness of about 5.0 μm was used. The liquid crystal used had a Δn of 0.0667, and the product of the liquid crystal layer thickness and the birefringence difference was set to be approximately 300 nm. The thickness of the liquid crystal layer 1 has a different value depending on the position due to the unevenness of the light reflective pixel electrode 19.

Further, a driving circuit was mounted around the liquid crystal display panel manufactured as described above to obtain a reflection type liquid crystal display device.

In the reflection type liquid crystal display device of this embodiment, since the light reflective pixel electrode 19 is arranged near the liquid crystal layer 1, there is no parallax, and a good high resolution display is realized. Due to the uneven shape of the reflected light provided to the light-reflective pixel electrode 19, the face of the observer was not reflected and a good white display was realized. In addition, since a material having a scattering property is not arranged on the front surface of the liquid crystal display device, a good dark state was exhibited, and therefore, a display with a high contrast ratio was obtained.

Further, since the color filter 24 having high brightness is used, sufficient brightness can be ensured even in the display using the polarizing plate, the reflectance in the dark state is low, and the color element selected in the dark state is used. The reflected light due to is observed together with the reflected light of the color element selected in the bright state, and the color purity does not deteriorate. Thereby, despite the low color saturation of the high brightness color filter 24, good color reproducibility without impairing the color reproduction range of the color filter 24 was obtained.

Further, since the voltage applied to each pixel is set to an intermediate state between the dark state and the bright state, there is no problem in reproducing halftones.
There was no problem in expressing the intermediate colors of each color. In addition, it was confirmed that the response speed did not cause any problem in moving image reproduction in actual driving.

As described above, a reflection-type liquid crystal display device capable of displaying multiple gradations and displaying a moving image and having a good color reproduction range was realized by a practical manufacturing method.

Ninth Embodiment As a ninth embodiment, the lightness is improved by forming a light reflecting film having an uneven shape having in-plane anisotropy. An example in which a good azimuth of the inclined viewing angle is directed will be described.

In the ninth embodiment, the unevenness of the light-reflective pixel electrode 19 of the reflective liquid crystal display device manufactured in the eighth embodiment is formed in a different pattern, and the unevenness is formed in the plane on which the reflective electrode is formed. Different ones were made depending on the orientation.

In the present embodiment, as a pattern satisfying the above conditions, as shown in an enlarged plan view of a main part of FIG. 18, a pattern having unevenness is not a circle but an ellipse and has a direction. The reflection characteristics of the light reflecting plate having only the light reflecting film having the uneven shape were measured in a measurement system arrangement as shown in FIG. That is, as shown in FIG.
The incident light was incident from an inclined direction, the reflected light intensity directed toward the normal direction of the light reflecting plate surface was measured, and the anisotropy of reflection was measured by rotating the light source.

The result was as shown in FIG. 20, and it was confirmed that light from a specific direction was efficiently directed to the front of the liquid crystal display device. However, in consideration of the fact that the refractive index of the liquid crystal material is significantly different from that of air, at the time of measurement, immersion oil (matching oil) having a refractive index of 1.516 is dropped on the surface of the light reflecting plate, and a transparent liquid The measurement was performed with a glass plate attached. The measured value is 1
It is obtained by conversion so that 00% is a value obtained when a standard diffusion plate (standard white plate) of MgO is similarly measured. In FIG. 20, a curve 20-1 is a measurement conversion value of the anisotropic diffuse reflector of the present example, and a curve 20-2 is a similar measurement of the same diffuse reflector as used in Example 8. It is a converted value.

As a result, as shown in FIG. 20, the curve 20-1 of the directional reflector in which the average period of the concavo-convex shape of the present embodiment changes in the plane of the reflector is the incident light of the illumination light. As the azimuth φ changes, the reflected lightness (reflected light intensity) changes greatly. On the other hand, in the curve 20-2 by the reflector (Example 8) having no anisotropy in the uneven shape, the change in the reflected lightness (reflected light intensity) accompanying the change in the incident direction φ of the illumination light is so large. Absent.

From these facts, the inventors of the present application consider that in order to increase the reflection brightness, as in the reflector used in the present embodiment, the average period of unevenness changes according to the orientation in the plane of the reflector. It has been found that directionality (anisotropic) is a powerful means. Further, in FIG.
The azimuths of ° and 270 ° are the azimuths with the short average period of the concavo-convex shape. Thus, it has been confirmed that the reflection brightness of the illumination light from the azimuth with the short average period is high.

The alignment films 2 and 3 similar to those of the eighth embodiment are formed on the TFT element substrate 23 having the light reflecting plate having such characteristics and the color filter substrate 26 manufactured in the same manner as in the eighth embodiment. And perform orientation treatment (with a twist angle of 70
°) Four types of samples were produced.

In these samples, the arrangements of the polarizing plate 10, the optical phase difference compensating plate 8, and the optical phase difference compensating plate 9 are different, and the arrangements are as shown in FIGS. 21 (a) to 21 (d). . In addition, in FIGS. 21A to 21D, similarly to FIG. 17 described above, reference numeral 11 denotes the transmission axis direction of the polarizing plate 10;
Reference numeral 12 denotes the slow axis direction of the optical phase difference compensating plate 9, 13 denotes the slow axis direction of the optical phase difference compensating plate 8, and 14 contacts the alignment film 2 formed on the color filter substrate 26, that is, in the vicinity of the alignment film 2. Of the orientation of liquid crystal molecules of the TFT element substrate 15
The orientations of the liquid crystal molecules in contact with the alignment film 3 formed above, that is, in the vicinity of the alignment film 3, are respectively shown. This figure is observed from the direction of the incident light of the liquid crystal display device.

That is, the arrangement relationship in the sample shown in FIG. 21A is such that the angle θ1 between the transmission axis direction 11 of the polarizing plate 10, the optical phase difference compensator 8 and the slow axis direction 13 is 75.
°, transmission axis direction 11 of polarizing plate 10 and optical phase difference compensating plate 9
Of the liquid crystal molecules on the color filter substrate 26 and the polarizer 1
The angle θ3 between the zero transmission axis azimuth 11 and the transmission axis azimuth 11 is 130 °, and this sample is referred to as sample # 9a (similar to the eighth embodiment). The orientation direction 14 of the liquid crystal molecules on the color filter substrate 26 is parallel to the 3 o'clock direction.

The arrangement relationship in the sample shown in FIG. 21B is such that the angle θ1 between the transmission axis direction 11 of the polarizing plate 10 and the slow axis direction 13 of the optical phase difference compensator 8 is 75 °, the polarization The angle θ2 between the transmission axis direction 11 of the plate 10 and the slow axis direction 12 of the optical phase difference compensating plate 9 is 15 °, the orientation direction 14 of the liquid crystal molecules on the color filter substrate 26 and the transmission axis direction 11 of the polarizing plate 10. Is set to 130 °, and this sample is referred to as sample # 9b. Note that the alignment direction 14 of the liquid crystal molecules on the color filter substrate 26 is 1
It is parallel to the 2 o'clock direction.

The arrangement relationship in the sample shown in FIG. 21C is such that the angle θ1 between the transmission axis direction 11 of the polarizing plate 10 and the slow axis direction 13 of the optical phase difference compensator 8 is 75 °, the polarization is The angle θ2 between the transmission axis direction 11 of the plate 10 and the slow axis direction 12 of the optical phase difference compensating plate 9 is 15 °, the orientation direction 14 of the liquid crystal molecules on the color filter substrate 26 and the transmission axis direction 11 of the polarizing plate 10. Is set to 40 °, and this sample is referred to as sample # 9c. The orientation direction 14 of the liquid crystal molecules on the color filter substrate 26 is parallel to the 3 o'clock direction.

The arrangement relationship in the sample shown in FIG. 21D is such that the angle θ1 between the transmission axis direction 11 of the polarizing plate 10 and the slow axis direction 13 of the optical phase difference compensator 8 is 75 °, The angle θ2 between the transmission axis direction 11 of the plate 10 and the slow axis direction 12 of the optical phase difference compensating plate 9 is 15 °, the orientation direction 14 of the liquid crystal molecules on the color filter substrate 26 and the transmission axis direction 11 of the polarizing plate 10. Is set to 40 °, and this sample is referred to as sample # 9d. Note that the alignment direction 14 of the liquid crystal molecules on the color filter substrate 26 is 12
It is parallel to the hour direction.

These samples were prepared in the same manner as in Example 8 except for the step of forming a concave / convex pattern for preparing a light reflecting plate.

When the reflection type liquid crystal display device of each sample having such a light reflection plate having an uneven shape was visually observed,
In each of Samples # 9a to # 9d, when viewed from the front direction more than that of Example 8, a display with higher brightness was realized, and the effect of improving the brightness of the anisotropic unevenness was exhibited. At this time, the reflection lightness was high when the illumination light was incident from the 12 o'clock direction and the 6 o'clock direction. Furthermore, in the case of illuminating from the front direction and observing from the tilt direction, the brightness was similarly high at the 12 o'clock direction and the 6 o'clock direction.

Further, illumination light was made incident on the liquid crystal display devices of these samples from the front direction and observed from various directions inclined at 45 degrees from the front.
The sample a and the sample # 9d have good display at the 6 o'clock and 12 o'clock orientations, which are the tilt orientations with high reflection brightness, and further, display with good contrast is realized at these orientations. No display change due to the inclination was felt. On the other hand, in Sample # 9b and Sample # 9c, deterioration of the contrast ratio was observed in the display at the 6 o'clock direction and the 12 o'clock direction, which are directions with high brightness.

This indicates that the viewing angle azimuth of the liquid crystal display modulation layer (liquid crystal layer 1) having the most excellent visibility is different for different values of θ3. In addition, the sample # 9a and sample # 9d in which the direction with good visibility was matched with the direction with high lightness of the anisotropic uneven shape of the light reflecting plate described above, the polarizing plate of the present invention and the optical phase difference compensating plate were used. And high-quality display utilizing the high contrast ratio of the liquid crystal modulation layer (liquid crystal layer).

The orientation of the anisotropic uneven shape of the light reflecting plate used in the present embodiment can be set to another orientation in accordance with the main use environment of the liquid crystal display device of the present invention. In this case, it is needless to say that the same effect can be obtained by directing the liquid crystal alignment and the set angles of the polarizing plate and the optical phase difference compensator to a direction having a high brightness and a direction having a good tilt viewing angle characteristic.

[Tenth Embodiment] Next, as a tenth embodiment,
An embodiment of a touch panel-integrated reflective liquid crystal display device using a touch panel as information input means in a portable device, which is a main application field of the reflective liquid crystal display device of the present invention, will be described.

First, the schematic structure of the touch panel used in this embodiment is shown in FIG. FIG.
As shown in FIG. 5, the touch panel 31 has a support substrate 28 on which a transparent electrode 30 for detecting a pressed position is formed, and a movable substrate 27 on which a transparent electrode 29 for detecting a pressed position is formed. This is a planar pressure-sensitive element configured by arranging the transparent electrodes 29 and 30 so as to face each other. Note that the movable substrate 27 and the support substrate 28 both have no birefringence.

The schematic structure of this embodiment is shown in the sectional view of the main part in FIG. As shown in FIG. 23, in the touch panel-integrated reflective liquid crystal display device of this embodiment, an optical phase difference compensating plate 8, an optical phase difference compensating plate 9, and a polarizing plate 10 are attached on a movable substrate 27 of a touch panel 31. This is disposed on the display surface side of a liquid crystal drive cell having the same structure as that of the eighth embodiment in which the polarizing plate 10 and the optical phase difference compensating plates 8 and 9 are not attached.

At this time, the orientation of the liquid crystal layer 1 and the polarizing plate 1
The arrangement of 0 and the optical phase difference compensating plates 8 and 9 is the same as that shown in FIG. 17 (Example 8), and the configuration other than the touch panel is the same. It should be noted that a gap 32 is provided in order to provide a pressing force transmission preventing effect by maintaining a constant gap between the support substrate 28 of the touch panel and the color filter substrate 26 of the reflection type liquid crystal display device, and is lightweight without using a pressing force buffer member. Then, the pressing force applied to the touch panel is not transmitted to the color filter substrate 26.

As a comparative example, a touch panel-integrated reflective liquid crystal display device having a structure as shown in the sectional view of the main part of FIG. 24 was manufactured. That is, the structure of the comparative example is such that the touch panel 31 shown in FIG. 22 is arranged above the polarizing plate 10 of the structure of the eighth embodiment. Therefore, the only difference between the present embodiment and the comparative example is the arrangement position of the touch panel 31.

Next, a comparison was made between the embodiment of the present invention and a comparative example. First, in the case of the comparative example, the reflected light component on the touch panel was directly observed, greatly degrading the visibility.
The reflected light was generated not only by the gap sandwiched between the transparent electrodes 29 and 30 for detecting the pressed position, but also by the gap sandwiched between the touch panel support substrate 28 and the polarizing plate 10.

On the other hand, in the case of the present embodiment, the reflected light component generated in the comparative example is not observed at all, and
Very good display was shown as in the case where the touch panel was not used (Example 8). Further, in the case of the present example, unlike the comparative example, there was not observed any one caused by the gap between the transparent electrodes 29 and 30 for detecting the pressed position of the touch panel.

Furthermore, no reflection was observed at the interface between the pressing force transmission preventing gap 32 and the touch panel support substrate 28, or at the interface between the touch panel support substrate 28 and the color filter substrate 26 of the liquid crystal display device. Therefore, Example 1
According to No. 0, a reflection type liquid crystal integrated with an input device (touch panel), which does not require a pressure buffer member and is lightweight, and the display device can effectively use a circularly polarized state by the antireflection means of the input device for display. The display device was realized.

Although details are not shown, the touch panel 3
By omitting the movable substrate 27 and directly disposing the transparent electrode 29 on the liquid crystal layer 1 side of the optical phase difference compensating plate 8, a simpler and lighter configuration was possible.

[Second Embodiment of the Invention] Another embodiment of the present invention will be described below with reference to the drawings.

[0230] For convenience of explanation, members having the same functions as the members described in the above embodiment are denoted by the same reference numerals, and description thereof is omitted.

[0231] So far, in the case where a voltage is sufficiently applied to the liquid crystal layer, an example in which the liquid crystal layer has no polarization conversion effect and good characteristics are obtained under such approximation has been described. In consideration of the fact that the voltage applied to the liquid crystal stays at a finite voltage, it is effective to perform detailed optimization.

That is, referring to FIG. 1 described above, black display is realized at the maximum value of the voltage applied to the liquid crystal. However, at this time, the liquid crystal may be completely oriented in the normal direction of the substrate. In addition, the effect that a component parallel to the substrates 4 and 5 remains in the alignment of the liquid crystal is considered. The dark display condition taking this into consideration is the same as before, and the light incident from the polarizer 10 is applied to the optical phase difference compensators 8 and 9 and the liquid crystal layer 1 in a state where the practical maximum voltage is applied to the liquid crystal. At the stage of passing through both.

At this time, since a practically maximum voltage is applied to the liquid crystal layer 1, almost no polarization conversion action occurs, but a slight amount of light is generated according to the component parallel to the liquid crystal alignment substrate. A polarization conversion effect (hereinafter referred to as a residual phase difference) remains. In accordance with this, the optical phase difference compensating plates 8 and 9 are slightly changed from the conditions so far, so that a good voltage can be obtained at a practical maximum voltage. A dark display is realized.

On the other hand, the conditions for obtaining a good bright display by using the optical phase difference compensators 8 and 9 and the orientation of the liquid crystal layer 1 optimized to realize a good dark display in the same manner are similarly set. The polarization state on the surface of the reflection plate 3 is linearly polarized light.
This is based on the case where a sufficient voltage can be applied so far that the residual birefringence of the liquid crystal can be ignored.

That is, when the optical phase difference compensators 8 and 9 slightly changed according to the residual phase difference of the liquid crystal are used,
The setting of the liquid crystal layer 1 does not largely deviate from the setting of the liquid crystal layer 1 before the change, and the search based on the setting so far can be performed.

FIG. 25 shows a schematic configuration of the reflection type liquid crystal display device of the present embodiment. As shown in FIG. 25, this reflection type liquid crystal display device is different from the reflection type liquid crystal display device of the first embodiment in that a liquid crystal layer is provided between the optical phase difference compensating plate 8 and the substrate 4 in the circularly polarizing plate 100. In this configuration, a third optical phase difference compensating plate 101 is provided to cancel the residual phase difference of No. 1. FIG. 26 shows an example of the arrangement of three optical phase difference compensators 8, 9, and 101 in this reflection type liquid crystal display device.

The residual phase difference of the liquid crystal layer 1 is set to be at the center of the substrates 4 and 5 of the liquid crystal layer 1 when the liquid crystal layer 1 is set near the twist angle of 70 degrees, which is the center of the setting of the twist angle shown in the present invention. A birefringent component having a slow axis parallel to the liquid crystal alignment direction remains. In order to cancel this, it is appropriate to dispose an optical phase difference compensator having a slow axis in the direction orthogonal to the liquid crystal alignment as the third optical phase compensator 101. Although the amount of the retardation depends on the maximum voltage applied to the liquid crystal, the residual retardation of the liquid crystal layer 1 can be canceled by setting the retardation amount to approximately 10 to 50 nm.

Subsequently, a method of improving the viewing angle and realizing a good display with respect to the reflection type liquid crystal display device of FIG. 25 will be further studied.

In the reflection type liquid crystal display device shown in FIG. 25, a good dark display is realized at the maximum value of the actually driven voltage. It is effective to compensate for the residual birefringence of the liquid crystal in the state where is applied.

For this reason, the viewing angle can be expanded by expanding the observation angle range in which the residual birefringence of the liquid crystal layer 1 can be favorably canceled. In order to realize this, it is effective to use an optical retardation compensator in consideration of the three-dimensional configuration of the orientation of the liquid crystal.

FIG. 27 schematically shows the three-dimensional orientation of the liquid crystal layer 1 in the actual driving state. FIG. 27 shows a more accurate alignment of the liquid crystal in the reflective liquid crystal display device of FIG. In this state, for the light passing through the liquid crystal layer 1 in the normal direction of the display surface, the residual birefringence can be canceled by the uniaxial optical phase difference compensator having the slow axis direction in the normal plane. However, with respect to light that passes through the liquid crystal layer 1 while being inclined, it is effective to use an optical phase difference compensator in which the orientation of the liquid crystal layer 1 is further considered.

First, since the liquid crystal is oriented substantially perpendicular to the substrates 4 and 5, the refractive index of the liquid crystal layer 1 has a large component with respect to the electric field in the normal direction of the substrate. In order to cancel this, an optical phase difference compensating plate having such a characteristic that the refractive index of the third optical phase difference compensating plate 101 with respect to the electric field in the layer thickness direction is small is effective.
This is realized by using an optical phase difference compensator that is optically uniaxial and has a smaller refractive index to the electric field in the film thickness direction than in the film surface direction. Further, in order to cancel the residual retardation in the in-plane direction of the liquid crystal layer, an optically biaxial refractive index ellipsoid may be used.

More precisely, it is effective to consider that the liquid crystal alignment is not completely perpendicular to the substrates 4 and 5. In particular, when a reflective liquid crystal display device has a diffusive reflective film or a reflective film that is arranged to be inclined with respect to the display surface, the direction of light is more generally in a direction different from the regular reflection direction with respect to the display surface. When a reflecting surface having a function of changing is used, an optical path from passing through the liquid crystal layer 1 to the light reflecting film 7 and an optical path from the light reflecting film 7 to the light exiting through the liquid crystal layer 1 respectively. On the other hand, canceling the residual birefringence of the liquid crystal is effective for achieving a good viewing angle.

A more detailed description will be given with reference to FIG.
As shown in FIG. 28, the case where the surrounding illumination light A is used for the observer in the front direction of the reflection type liquid crystal display device, and the case where the illumination environment changes when the illumination light B is mainly used. Think.

At this time, the brightness and hue of the dark display change due to changes in the surrounding illumination light, even though the position of the viewer and the liquid crystal display device are fixed. This is because the degree of cancellation of the residual birefringence of the liquid crystal changes depending on the direction of the optical path passing through the liquid crystal layer 1. By preventing this, a better display can be realized.

[Embodiment 11] As Embodiment 11, a reflective liquid crystal display device having the structure shown in FIG. 25 described above was manufactured using the parameters shown in Table 6, and two samples # 11a,
$ 11b was obtained.

[0247]

[Table 6]

FIG. 29 shows voltage reflectance curves of the samples # 11a and # 11b. For comparison, a voltage reflectance curve of the reflective liquid crystal display device of Example 3 is shown.

From this, it can be seen that in the sample # 11a of this embodiment, although the reflectivity of bright display is slightly lowered, good dark display is realized. Further, in sample # 11b, good dark display was realized without a decrease in lightness.

Here, by further reducing the number of optical phase difference compensating plates to be used, an optical phase difference compensating plate 101 is manufactured for the purpose of producing a liquid crystal display device similar to those of the above configuration examples at lower cost. And optical phase difference compensator 8-2
A study was conducted to realize the action of one sheet with one optical phase difference compensator.

At this time, when two optical phase difference compensating plates are stacked with their slow axes arranged in parallel, one optical phase difference compensating plate having the retardation of the sum of the respective retardations is used. Alternatives are possible and 2
When two optical retardation compensators are stacked with their slow axes orthogonal to each other, the optical retardation compensator can be replaced by one optical retardation compensator having retardation of each retardation difference. used.

That is, the optical phase difference compensating plate 8 and the optical phase difference compensating plate 101 in the sample # 11b of this embodiment are
Since they are arranged close to each other and arranged so that the slow axis directions are orthogonal to each other, one optical phase difference compensator having retardation of the difference between the two can be substituted. That is, by changing the retardation of the optical phase difference compensating plate 8, the same effects as those of the samples # 11a and # 11b are exhibited.

To confirm this effect, samples # 11c and # 11d were further manufactured. Each of these samples
11c and # 11d have the same cross-sectional structure as FIG. 1 of the first embodiment. Each sample # 11c, # 11
Table 7 shows the arrangement of the optical phase difference compensators 8 and 9 at d.

[0254]

[Table 7]

The voltage reflectance curves of samples # 11c and # 11d were similar to those of sample # 11b shown in FIG.

Thus, it can be shown that better characteristics can be realized by adding the third optical phase difference compensator for canceling the residual phase difference of the liquid crystal at the practical maximum voltage applied to the liquid crystal. Was done. In addition, 2
It was confirmed that the same effect can be achieved by adjusting the retardation even when using two optical phase difference compensators. That is, it was confirmed that a better black display could be realized by adding or adjusting the optical phase difference compensator in consideration of the actual driving.

[Embodiment 12] In the twelfth embodiment, the liquid crystal layer 1
An optical phase difference compensating plate having an optical axis that is optically uniaxially inclined is arranged as the third optical phase difference compensating plate 101 so that the residual birefringence can be canceled in more directions. A reflective liquid crystal display device having the configuration shown in FIG. 30 was realized, and this was designated as Sample # 12a. Further, a reflection type liquid crystal display device having a configuration shown in FIG. 31 using a biaxial optical phase difference compensating plate as the third optical phase difference compensating plate 101 was realized, and this was used as a sample # 12b.

In this example, the refractive index ellipsoid of the optical phase difference compensating plate 101 is not inclined with respect to the substrate.

Here, although not shown, an uneven metal reflector similar to that of the reflection type liquid crystal display of FIG. 16 is used as the light reflection film 7 so as to have a light diffusing property.

A reflection type liquid crystal display device having the same structure as that of samples # 12a and # 12b, except that a positive uniaxial optical phase difference compensator was used as the optical phase difference compensator 101 as sample # 12c. Produced.

Table 8 shows the arrangement of the optical elements of each of the samples # 12a to # 12c.

[0262]

[Table 8]

Table 9 shows the evaluation results of the viewing angles of the samples # 12a to # 12c.

[0264]

[Table 9]

The optical phase difference compensating plate 101 used in the sample # 12a was manufactured so that the refractive index ellipsoid was inclined by devising the stretching method, and the optical retardation compensating plate 101 was manufactured such that the retardation with respect to the light transmitted in the front direction was about 30 nm. Have been.

As shown in FIG. 30, this film
Only the refractive index for the z component of the electric field exhibits a smaller negative uniaxiality than the refractive index for the other x and y components, and
This z-direction is a flat film optical phase difference compensator 101
The surface is inclined from the normal direction. The z direction is arranged so as to be close to the direction of the liquid crystal alignment at the practical maximum voltage. For light in the front direction of the optical phase difference compensator 101, the x direction acts as a slow axis.

This optical phase difference compensating plate 101 has an optical function
Layer thickness d₁₀₁In the x, y, and z directions shown in FIG.
The refractive index is n_x,n_y,n_zAs (n_y-N_z 
 ) D_{1 01}= (N_x-N_z) D₁₀₁= 300nm
Was.

Further, it is needless to say that a polymer film in which the nematic liquid crystal alignment or the discotic liquid crystal alignment is fixed may be used in order to accurately cancel the three-dimensional alignment of the liquid crystal layer 1.

The optical retardation compensating plate 101 used in the sample # 12b is manufactured so as to have a biaxial refractive index ellipsoid by devising a stretching method. It is manufactured so that the retardation with respect to the optical axis transmitting in the front direction is about 30 nm.

As shown in FIG. 31, this film
The refractive index for each component of the electric field is x component, y component, and z component in descending order. Further, (n _x -n _y) d
₁₀₁ = 30 nm, were _{(n y -n z) d 101} = 300nm.

As shown in Table 9, all of the bright displays were white display, but the dark display was good.
12a, $ 12b, and $ 12c. In addition, the overall evaluation was good, and the samples # 12a, # 12b,
The order was $ 12c. This is because the characteristics fluctuate also in white display, but there is no visual difference.
On the other hand, in the black display, the visual difference is large, affecting the overall evaluation.

As described above, it was confirmed that a liquid crystal display device having a good viewing angle can be realized by devising an optical phase difference compensator in consideration of the three-dimensional orientation of liquid crystal. Furthermore, it has been confirmed that a better dark state can be realized by making the optical phase difference compensators 8 and 9 biaxial.

Also in this embodiment, a retardation film having both functions of the optical retardation compensating plate 8 and the optical retardation compensating plate 101 can be used for cost reduction as in the eleventh embodiment. Needless to say, there is.

As described above, according to the reflection type liquid crystal display device of the present invention, the reflection surface of the light reflection plate such as the light reflection film can be provided on the liquid crystal layer side, and a good dark state is realized. it can. Therefore, it is possible to realize a reflective liquid crystal display device capable of displaying a moving image with high resolution and high contrast without parallax.

According to the touch panel-integrated reflective liquid crystal display device of the present invention, when a touch panel is added to the reflective liquid crystal display device of the present invention, a combination of a polarizing plate and two optical phase difference compensating plates is used. By arranging the touch panel, it is possible to prevent the occurrence of reflected light that adversely affects the display characteristics, and to realize a high-quality touch panel-integrated reflective liquid crystal display device.

[0276]

As described above, according to the reflection type liquid crystal display device of the present invention, the reflection surface of a light reflection plate such as a light reflection film can be provided on the liquid crystal layer side, and a good dark state can be obtained. realizable. Therefore, it is possible to realize a reflective liquid crystal display device capable of displaying a moving image with high resolution and high contrast without parallax.

When a color filter adjusted to high brightness is used in the reflection type liquid crystal display device of the present invention, a color display reflection type liquid crystal display device having good color reproducibility and high display quality can be realized. it can.

Further, according to the reflection type liquid crystal display device of the present invention, as the circularly polarizing means, the residual position generated when the voltage is applied to the liquid crystal layer is changed from the condition that the light incident on the liquid crystal layer becomes circularly polarized light. Since the optical phase difference compensator that has been changed by the amount that cancels the phase difference is used, the residual phase difference that occurs when a voltage is applied to the liquid crystal layer can be canceled, and good darkness can be obtained when the voltage is applied to the liquid crystal layer. Display can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a principal part showing a schematic structure of a reflective liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a setting orientation of an arrangement of a polarizing plate and two optical phase difference compensators according to an embodiment.

FIG. 3 is a calculation result graph in which a numerical value of an evaluation function for predicting the reflectance in the reflection type liquid crystal display device of Example 1 in the case of 550 nm monochromatic light is shown in an isodiagram.

FIG. 4 is a calculation result graph in which a numerical value in consideration of luminosity of an evaluation function for predicting a reflectance in the reflection type liquid crystal display device of Example 1 is shown in an isometric diagram.

FIG. 5 is an isometric diagram showing an evaluation function for predicting a reflectance in the reflective liquid crystal display device of Example 1 and x of CIE1931 chromaticity coordinates calculated by a D65 standard light source spectrum. It is a calculation result graph.

FIG. 6 is an isometric diagram showing an evaluation function for predicting the reflectance in the reflection type liquid crystal display device of Example 1 and y of the CIE1931 chromaticity coordinates calculated by the D65 standard light source spectrum. It is a calculation result graph.

FIG. 7 is a diagram showing a region where good white balance and lightness are both obtained by FIGS. 4, 5 and 6;

FIG. 8 is a diagram illustrating a setting orientation of an arrangement of a polarizing plate and two optical phase difference compensating plates of the reflective liquid crystal display device according to the third embodiment.

FIG. 9 is a diagram illustrating a measured value of the voltage dependence of the reflectance of the reflective liquid crystal display device according to the third embodiment.

FIG. 10 is a layout conceptual diagram illustrating a measurement optical system that measures the voltage dependence of the reflectance of the reflective liquid crystal display device of Example 3.

FIG. 11 is a diagram illustrating a setting orientation of an arrangement of a polarizing plate and two optical phase difference compensating plates of a reflective liquid crystal display device according to a fourth embodiment.

FIGS. 12 (a) and 12 (b) show the arrangement directions of polarizing plates and the arrangement of two optical phase difference compensators for samples # 5a and # 5b of the reflection type liquid crystal display device of Example 5, respectively. FIG. 4 is a diagram illustrating a set direction between a direction and a liquid crystal orientation of a liquid crystal layer.

FIG. 13 is a diagram illustrating a measured value of the voltage dependence of the reflectance of the reflective liquid crystal display device according to the fifth embodiment.

FIG. 14 is a diagram illustrating a setting orientation of an arrangement of a liquid crystal orientation direction near an upper substrate of Example 7 and a plane including an observation orientation.

FIG. 15 is a table showing the result of visual observation of the reflection type liquid crystal display device of Example 7 while changing the value of θ4.

FIG. 16 is a cross-sectional view of a principal part showing a schematic structure of a reflective liquid crystal display device according to an eighth embodiment.

FIG. 17 is a diagram illustrating a setting direction of a polarizing plate arrangement direction, a disposing direction of two optical phase difference compensating plates, and a liquid crystal orientation of a liquid crystal layer of the reflection type liquid crystal display device of Example 8;

FIG. 18 is a partially enlarged plan view showing a concave-convex shape of a light reflection plate used in a reflection type liquid crystal display device of Example 9;

FIG. 19 is a conceptual diagram showing a measurement direction of an optical system for measuring a reflection characteristic of a reflective electrode (light reflecting plate) according to a ninth embodiment.

FIG. 20 is a diagram showing measured values of the reflection characteristics of the reflective electrode (light reflection plate) of Example 9 by the measurement system of FIG. 19;

FIGS. 21 (a) to 21 (d) show samples # 9a and # 9 of a reflection type liquid crystal display device of Example 9, respectively.
FIG. 9B is a diagram illustrating the setting directions of the polarizing plate arrangement direction, the arrangement directions of the two optical retardation compensators, and the liquid crystal alignment of the liquid crystal layer for b, # 9c, and # 9d.

FIG. 22 is a cross-sectional view of a principal part showing a schematic structure of a touch panel used in a touch panel-integrated reflective liquid crystal display device of Example 10;

FIG. 23 is a cross-sectional view of a principal part showing a schematic structure of a touch panel-integrated reflective liquid crystal display device of Example 10;

FIG. 24 is an essential part cross-sectional view showing a schematic structure of a touch panel-integrated reflective liquid crystal display device of a comparative example.

FIG. 25 is a sectional view of a principal part showing a schematic structure of a reflection type liquid crystal display device according to another embodiment of the present invention.

FIG. 26 is a diagram illustrating a setting orientation of an arrangement of a polarizing plate and two optical phase difference compensating plates according to another embodiment.

FIG. 27 is an explanatory diagram showing a difference in alignment of a liquid crystal layer of a reflective liquid crystal display device depending on a voltage.

FIG. 28 is an explanatory diagram showing how the viewing angle changes depending on the relationship between the orientation direction of the liquid crystal layer and the illumination direction of the reflective liquid crystal display device.

FIG. 29 is a diagram showing a measured value of the voltage dependence of the reflectance of the reflective liquid crystal display device of Example 11;

FIG. 30 is a fragmentary cross-sectional view showing a structure of Sample # 12a of Example 12;

FIG. 31 is a fragmentary cross-sectional view showing a structure of Sample # 12b of Example 12.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Liquid crystal layer 2, 3 Orientation film 4, 5 Substrate 6 Transparent electrode 7 Light reflection film 8 Optical phase difference compensator 9 Optical phase difference compensator 10 Polarizer 11 Transmission axis direction of polarizer 12 Delay of optical phase compensator 9 Phase axis direction 13 Slow axis direction of optical retardation compensator 8 14 Orientation of liquid crystal molecules near alignment film formed on color filter 15 Orientation of liquid crystal molecules near alignment film formed on TFT element substrate Orientation 16 reflective liquid crystal display device 19 light-reflective pixel electrode 23 TFT element substrate 26 color filter substrate

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takashi Sato 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 2H042 BA04 BA20 2H049 BA03 BA47 BB03 BB63 BC22 2H091 FA02Y FA08X FA08Z FA11X FA11Z FA41Z HA07 HA08 LA17

Claims (5)

[Claims] A liquid crystal layer sandwiched between at least a first substrate having a light reflecting means and a second substrate having a light transmissivity, the liquid crystal layer comprising a nematic liquid crystal having a positive dielectric anisotropy and being oriented; A circularly polarizing means having at least one linearly polarizing plate and selectively transmitting substantially circularly polarized light in either direction from natural light to the left or right; at least the light reflecting means, the liquid crystal layer, and the circularly polarizing means are stacked and arranged; A surface that emits circularly polarized light when natural light is incident on the circularly polarized light means is provided on the liquid crystal layer side, and a product of a birefringence difference of liquid crystal of the liquid crystal layer and a liquid crystal layer thickness. Is 150 nm or more and 350 nm
A reflective liquid crystal display device wherein the twist angle of the liquid crystal layer is in the range of 45 degrees to 100 degrees, wherein the circularly polarizing means uses an optical retardation compensator; The optical phase difference compensator is set in the dark state by changing the condition that the incident light to the liquid crystal layer becomes circularly polarized light to the condition changed by the amount to cancel the residual phase difference generated when the voltage is applied to the liquid crystal layer. A reflective liquid crystal display device. A liquid crystal layer sandwiched between at least a first substrate having a light reflecting means and a second substrate having a light transmissive property and having a positive dielectric anisotropy and comprising an oriented nematic liquid crystal; A circularly polarizing means having at least one linearly polarizing plate and selectively transmitting substantially circularly polarized light in either direction from natural light to the left or right; at least the light reflecting means, the liquid crystal layer, and the circularly polarizing means are stacked and arranged; A surface that emits circularly polarized light when natural light is incident on the circularly polarized light means is provided on the liquid crystal layer side, and a product of a birefringence difference of liquid crystal of the liquid crystal layer and a liquid crystal layer thickness. Is 85 nm or more and 350 nm or less, and the twist angle of the liquid crystal layer is in a range of more than 0 degree and 100 degrees or less, wherein the circularly polarizing means uses an optical phase difference compensating plate. The above optical The phase difference compensator is set to a dark state by changing the condition that the incident light to the liquid crystal layer becomes circularly polarized light to the condition changed by canceling the residual phase difference generated when the voltage is applied to the liquid crystal layer. A reflective liquid crystal display device, characterized in that: 3. The reflection type liquid crystal display device according to claim 1, wherein said circularly polarizing means has a retardation of 1 in a normal direction of the substrate.
A first optical phase difference compensating plate set at not less than 00 nm and not more than 180 nm, and a retardation in a direction normal to the substrate is 200
a second optical phase difference compensating plate set to at least nm and not more than 360 nm, and a linear polarizing plate, and a transmission axis or an absorption axis of the linear polarizing plate and a slow phase of the first optical phase difference compensating plate. The value of | 2 × θ2−θ1 | when the angle between the transmission axis or the absorption axis of the linear polarizing plate and the slow axis of the second optical phase difference compensator is θ2, where θ1 is the angle formed with the axis. Is not less than 35 degrees and not more than 55 degrees, and the retardation of the first optical phase difference compensating plate is such that a voltage is applied to the liquid crystal layer from a retardation capable of giving a phase difference of only a quarter wavelength in the entire visible wavelength region. The retardation of the second optical phase difference compensator is set to a retardation changed by an amount to cancel the residual phase difference generated in the applied state, and the retardation of the second optical phase difference compensator gives a phase difference of only a half wavelength in the entire visible wavelength region. Preparative reflection type liquid crystal display device, characterized in that it is set to retardation can. 4. The reflection type liquid crystal display device according to claim 1, wherein said circularly polarizing means has a retardation of 1 in a direction normal to the substrate.
A first optical phase difference compensating plate set at not less than 00 nm and not more than 180 nm, and a retardation in a direction normal to the substrate is 200
a second optical phase difference compensating plate set to at least nm and not more than 360 nm, and a linear polarizing plate, and a transmission axis or an absorption axis of the linear polarizing plate and a slow phase of the first optical phase difference compensating plate. The value of | 2 × θ2−θ1 | when the angle between the transmission axis or the absorption axis of the linear polarizing plate and the slow axis of the second optical phase difference compensator is θ2, where θ1 is the angle formed with the axis. Is not less than 35 degrees and not more than 55 degrees, and the direction of the slow axis of the first optical phase difference compensator is parallel to the liquid crystal alignment direction at the center of both end faces in the thickness direction of the liquid crystal layer; The retardation of the optical phase difference compensating plate is 10 to 50 nm higher than the retardation that can give a phase difference of only a quarter wavelength in the entire visible wavelength region.
wherein the retardation of the second optical phase difference compensator is set to a retardation capable of giving a phase difference of only a half wavelength in the entire visible wavelength region. Liquid crystal display device. 5. The reflection type liquid crystal display device according to claim 1, wherein said circularly polarizing means has a retardation of 1 in a direction normal to the substrate.
A first optical phase difference compensating plate set at not less than 00 nm and not more than 180 nm, and a retardation in a direction normal to the substrate is 200
a second optical phase difference compensating plate set to at least nm and not more than 360 nm, and a linear polarizing plate, and a transmission axis or an absorption axis of the linear polarizing plate and a slow phase of the first optical phase difference compensating plate. The value of | 2 × θ2−θ1 | when the angle between the transmission axis or the absorption axis of the linear polarizing plate and the slow axis of the second optical phase difference compensator is θ2, where θ1 is the angle formed with the axis. Is not less than 35 degrees and not more than 55 degrees, and the direction of the slow axis of the first optical phase difference compensator is orthogonal to the liquid crystal alignment direction at the center of both end faces in the thickness direction of the liquid crystal layer; The retardation of the optical phase difference compensator is 10 to 50 nm, which is smaller than the retardation that can give a phase difference of only a quarter wavelength in the entire visible wavelength region.
wherein the retardation of the second optical phase difference compensator is set to a retardation capable of giving a phase difference of only a half wavelength in the entire visible wavelength region. Liquid crystal display device.