JP2003139941A - Filter substrate for liquid crystal display device, method for manufacturing the same and liquid crystal display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the adverse effect of interfacial reflection in a filter substrate for a liquid crystal display device comprising a cholesteric liquid crystal filter and a λ/4 optical retardation plate disposed on the incident side. SOLUTION: The filter substrate 10 for the liquid crystal display device has an optical retardation layer 3 for converting incident linearly polarized light into circularly polarized light and the cholesteric liquid crystal filter 4 with a function to selectively reflect the circularly polarized light converted in the optical retardation layer 3 provided on a transparent substrate 1 in this order. The filter substrate 10 also has a function to transmit part of light inside a selective reflection wavelength band of the cholesteric liquid crystal filter 4, wherein the difference between the average refractive index of the optical retardation layer 3 and that of the cholesteric liquid crystal filter 4 is 0.05 or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter substrate for a liquid crystal display device, a method for manufacturing the same, and a liquid crystal display device using the same, and more particularly, a filter substrate for a liquid crystal display device with reduced unnecessary light, a method for manufacturing the same, and a method thereof. The present invention relates to a liquid crystal display device using.

[0002]

2. Description of the Related Art Hitherto, the use of a cholesteric film in which a cholesteric liquid crystal is dispersed as a color filter has been disclosed in, for example, JP-A-9-318807. This color filter has superior performance in brightness and color purity as compared with a color filter using a conventional pigment or dye. In particular, the wavelength of the selectively reflected light changes depending on the temperature and the ratio of the chiral agent, and further, by using an ultraviolet curable cholesteric liquid crystal that can be cured while maintaining the state of the liquid crystal by ultraviolet irradiation, it is easier to manufacture than conventional products. There is an advantage that you can.

Cholesteric liquid crystal as described above, and
The chiral nematic liquid crystal has a characteristic that, in addition to the long-range orientational order of the liquid crystal molecular axes, the director is spirally spatially changing. That is, in the plane parallel to the liquid crystal molecular axis, the liquid crystal has the same alignment order as in the nematic phase, but when it moves to the adjacent plane, this local alignment direction is slightly rotated, so this continues sequentially. It has a spiral structure.

On the other hand, natural light can be divided into right-handed circularly polarized light and left-handed circularly polarized light. In a cholesteric liquid crystal or a chiral nematic liquid crystal, both right-handed and left-handed light components are incident parallel to the helical axis of the liquid crystal. In this case, there is a characteristic that only the circularly polarized light component in the same rotation direction as the twist direction of the liquid crystal is reflected and the other circularly polarized light component is transmitted.

At this time, since the phase of the reflected light with respect to the incident light does not change, the polarization direction before and after the incident of the reflected light is unchanged, and the wavelength of the reflected light is the twist of the cholesteric liquid crystal or the chiral nematic liquid crystal. It changes according to the pitch. This pitch changes depending on the addition amount of a chiral agent that generates a twisting force in the liquid crystal and an appropriate external field (for example, temperature, electric field, magnetic field, etc.).

Therefore, the above parameters are
By controlling in the visible range, it is possible to form red, green, and blue transmitted light, and the light other than the transmitted light is reflected to the light source side and reused, and the brightness is changed to the conventional color filter. It can be set higher than.

In the present invention, the reflection filter using the liquid crystal having such a spiral structure is hereinafter referred to as a cholesteric liquid crystal filter. The cholesteric liquid crystal filter reflects a specific circularly polarized light in a specific wavelength range and It has the property of transmitting wavelength bands and other circularly polarized light.

By the way, heretofore, as a transmissive color liquid crystal display device using such a cholesteric liquid crystal filter, Japanese Patent Laid-Open No. 8-234196 and 2000-
347179, a circularly polarizing plate for irradiating only right circularly polarized light or left circularly polarized light is arranged on the backlight side,
A cholesteric that transmits light in the R, G, and B wavelength ranges from the backlight side to R (red), G (green), and B (blue) pixels, respectively, and reflects light in other color wavelength ranges. A liquid crystal filter and an absorptive color filter that transmits only light in the R, G, and B wavelength regions and absorbs light in other wavelength regions are disposed on the viewing side of the liquid crystal filter to improve the backlight utilization efficiency. , Those that prevent the influence of outside light have been proposed.

Further, in Japanese Patent Laid-Open No. 2000-193962, a semi-transmissive cholesteric liquid crystal filter, that is, a specific circularly polarized light in a specific wavelength range is configured to be transmitted not by 100% but by a predetermined ratio, for example, 10%. A semi-transmissive cholesteric liquid crystal filter is placed on the side opposite to the viewing side of the liquid crystal layer of the liquid crystal display element, and in the case of a reflective display, a specific circularly polarized component of external light is generated by the semi-transmissive cholesteric liquid crystal. In the case of a transmissive display, it is proposed that the light is reflected by a filter so that only 10% of a specific circularly polarized light component passing through the circularly polarizing plate is transmitted.

Although not directly related to the cholesteric liquid crystal filter, a retardation layer (1/4) used for a circularly polarizing plate is used.
Λ / 2 retardation layer (half wave plate) and λ
Japanese Patent Application Laid-Open No. HEI 10-104, which is composed of a / 4 retardation layer (quarter wave plate) and whose fast axes intersect with each other at 60 ± 10 ° and which can be made into a substantially perfect circularly polarized light regardless of wavelength. -688
No. 16 proposed. In the present invention described below, a quarter-wave plate (hereinafter, referred to as a λ / 4 retardation plate) including the retardation layer having such a configuration is used.

[0011]

In the cholesteric liquid crystal filter used in the liquid crystal display device as described above, a circularly polarizing plate is arranged on the backlight incident side of the cholesteric liquid crystal filter, and a backlight incident on the cholesteric liquid crystal filter is provided. It is restricted to right-handed circularly polarized light or left-handed circularly polarized light. A circularly polarizing plate has a linear polarizing plate on the backlight incident side and a λ / 4 retardation plate on the opposite side. The circular polarizing plate is a transparent substrate on the backlight incident side of a liquid crystal display device. Since the cholesteric liquid crystal filter is disposed on the outside of the transparent substrate and on the inside of the transparent substrate on the incident side of the backlight, the configuration shown in FIG. 5 is obtained. However, in this example, for the sake of clarity, the cholesteric liquid crystal filter is a semi-transmissive cholesteric liquid crystal filter (semi-transmissive liquid crystal filter) that transmits a part of the right-handed circularly polarized light and reflects the rest, while transmitting the left-handed circularly polarized light. C
LC) is used to integrally bond the λ / 4 retardation plate constituting the circularly polarizing plate to the transparent substrate with an adhesive layer.
Further, the transmissive / reflective ratio of the semi-transmissive CLC is set to 3: 7.

Illumination light from the backlight is naturally polarized light, and in the case of FIG. 5, it becomes linearly polarized light having a polarization plane in the plane of the paper by passing through the linearly polarizing plate of the circularly polarizing plate, and the linearly polarized light is λ / 4 position. In the case of FIG. 5, the light passes through the phase difference plate to become right circularly polarized light (R), and the right circularly polarized light (R) is incident on the semi-transmissive CLC through the adhesive layer, the transparent substrate, and the alignment layer, among which 3
Right circularly polarized light (R) of 0% is transmitted, and 70% of the right circularly polarized light (R) is reflected to the backlight side by Bragg reflection. However, a part of the Bragg reflected light of the right-handed circularly polarized light (R) is due to the difference in refractive index, between the transflective CLC and the alignment layer, between the alignment layer and the transparent substrate, and between the transparent substrate and the adhesive layer, respectively. During this period, the light is reflected due to Fresnel reflection between the adhesive layer and the λ / 4 retardation plate, and re-enters the transflective CLC.

The problem here is that the rotation direction of circularly polarized light is reversed due to Fresnel reflection. for that reason,
The Fresnel reflected light at the above interface is now left circularly polarized (L)
And enters the semi-transmissive CLC. Since the semi-transmissive CLC has a property of transmitting left-handed circularly polarized light (L), the Fresnel reflected light thereof passes through the semi-transmissive CLC and becomes unnecessary light.

Particularly, in a liquid crystal display device using a semi-transmissive cholesteric liquid crystal filter (CLC), the light transmitted through the CLC is configured as circularly polarized light in a specific direction (right circularly polarized light in the above case). When the circularly polarized light in the opposite direction (left circularly polarized light in the above case) passes through the CLC, the light does not follow the display mechanism, and the display contrast, color purity, etc. are deteriorated.

The present invention has been made in view of the above problems of the prior art, and an object thereof is a filter substrate for a liquid crystal display device in which a cholesteric liquid crystal filter and a λ / 4 retardation plate are arranged on the incident side thereof. In order to provide a structure for preventing the adverse effect of interface reflection.

[0016]

A filter substrate for a liquid crystal display device of the present invention which achieves the above-mentioned object comprises a retardation layer for converting incident linearly polarized light into circularly polarized light in order on a transparent substrate,
And a cholesteric liquid crystal filter having a function of selectively reflecting the circularly polarized light converted by the retardation layer, wherein the cholesteric liquid crystal filter has a function of transmitting a part of light in the wavelength band selectively reflected, The difference in average refractive index between the retardation layer and the cholesteric liquid crystal filter is 0.05 or less.

In this case, it is preferable that the cholesteric liquid crystal filter contains a crosslinkable nematic liquid crystal and a crosslinkable chiral agent as main components, and the retardation layer contains the nematic liquid crystal as a main component.

Further, the retardation layer may be composed of a λ / 2 retardation layer and a λ / 4 retardation layer, and their fast axes intersect at 60 ± 10 degrees.

A linear polarizing plate may be adhered to the opposite side surface of the transparent substrate.

One of the methods for producing a filter substrate for a liquid crystal display device of the present invention is to crosslink a crosslinkable nematic liquid crystal coated on an alignment film on a transparent substrate to form a film, and then separately prepare a crosslink. It is a method characterized by coating a mixed liquid of a possible nematic liquid crystal and a crosslinkable chiral agent and crosslinking the mixture to form a film.

Another method of manufacturing a filter substrate for a liquid crystal display device according to the present invention comprises cross-linking a cross-linkable nematic liquid crystal coated on an alignment film on a transparent substrate to obtain λ / 2.
As a retardation layer, a crosslinkable nematic liquid crystal is coated on it, crosslinked to form a λ / 4 retardation layer, and a separately prepared mixture liquid of a crosslinkable nematic liquid crystal and a crosslinkable chiral agent is coated thereon. Then, it is crosslinked to form a film.

In the latter case, the surface of the λ / 2 retardation layer is rubbed in an arbitrary direction, and the fast axes intersect each other at 60 ± 10 degrees by using the orientation regulating force of the surface of the λ / 2 retardation layer. Alternatively, the alignment film may be formed on the surface of the λ / 2 retardation layer and then rubbed in an arbitrary direction, and the mutual phase advance may be performed by using the alignment regulating force of the surface of the λ / 2 retardation layer. Axis is 60 ± 10
You may cross at a degree.

In the present invention, a liquid crystal layer for modulating the phase of incident light according to an applied voltage is sandwiched between two transparent substrates, and an electrode and a drive circuit for independently applying a voltage to each pixel are provided in the liquid crystal layer. A liquid crystal display element provided, an illumination light source provided on the side opposite to the observation side thereof, a circular polarization means arranged between the illumination light source and the liquid crystal layer, and an observation side of the liquid crystal display element. In a liquid crystal display device including a circularly polarizing means, a liquid crystal display device characterized in that any one of the above liquid crystal display device filter substrates is arranged as a transparent substrate on the backlight side of the liquid crystal display element. It includes.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A filter substrate for a liquid crystal display device, a method for manufacturing the same, and a liquid crystal display device using the same will be described below based on principles and examples.

FIG. 1 shows the structure of an example of the filter substrate for a liquid crystal display device of the present invention. FIG. 1 shows a substrate 10 on the backlight side of a liquid crystal display device using a semi-transmissive cholesteric liquid crystal filter (semi-transmissive CLC), a linear polarizing plate 11 and a backlight light source 12 arranged on the backlight incident side. FIG. 1 is a diagram showing both of the above, and a filter substrate 10 for a liquid crystal display device of the present invention includes a glass substrate 1, an alignment layer 2 made of a polyimide film integrally formed on the glass substrate 1, and an alignment layer 2 formed thereon. And a retardation layer 3 having a substantially λ / 4 retardation, which is composed of a nematic liquid crystal formed in the above, and a crosslinkable nematic liquid crystal and a crosslinkable chiral agent integrally formed thereon. A linear polarizing plate 11 which is made up of a semi-transparent cholesteric liquid crystal filter layer 4 and which forms a circularly polarizing plate together with the retardation layer 3 is arranged on the incident side of the filter substrate 10 for a liquid crystal display device. Are, also, on the incident side of the linearly polarizing plate 11 backlight 12
Are placed.

Filter substrate 1 for liquid crystal display device of the present invention
Since 0 has such a configuration, the backlight light source 12
In the case of FIG. 1, the naturally polarized illuminating light from the above becomes linearly polarized light having a plane of polarization in the plane of FIG. 1 through the linearly polarizing plate 11, and the linearly polarized light passes through the glass substrate 1 and the orientation layer 2 and the retardation layer. 3 and substantially due to the λ / 4 phase difference in FIG.
In the case of, the light is converted into right circularly polarized light (R) and immediately enters the semi-transmissive cholesteric liquid crystal filter layer 4, for example, 30% of the right circularly polarized light (R) is transmitted as right circularly polarized light (R). 70% goes right circularly polarized (R) due to Bragg reflection
It is reflected to the backlight side as it is. There is only one interface between the cholesteric liquid crystal filter layer 4 and the retardation layer 3, and the refractive index difference between the cholesteric liquid crystal filter layer 4 and the retardation layer 3 is 0.05 or less, preferably 0.
Since it is 01 or less, Fresnel reflection can be ignored at the interface, so that almost all the light reflected by the cholesteric liquid crystal filter layer 4 passes through the retardation layer 3 into linearly polarized light having a polarization plane in the paper surface in the case of FIG. The converted light passes through the alignment layer 2 and the glass substrate 1, passes through the linear polarizing plate 11 and is returned to the backlight light source 12 side, and the returned light is reflected by a reflecting mirror or the like (not shown) of the backlight light source 12 to serve as a backlight again. Used.

Here, there are interfaces between the retardation layer 3 and the alignment layer 2, between the alignment layer 2 and the glass substrate 1, etc., and the light reflected by the cholesteric liquid crystal filter layer 4 at these interfaces can be Fresnel reflected. However, since the plane of polarization of the linearly polarized light does not rotate during the reflection, the light reflected by these interfaces is converted into right circularly polarized light (R) by the retardation layer 3, and the light is reflected by the semi-transparent cholesteric liquid crystal filter layer 4. % Is right circularly polarized light (R)
As it is, 70% is Bragg reflected. Therefore, since the transmitted light is right circularly polarized light (R),
Unlike the case of, it does not become unnecessary light. Therefore, by constructing a liquid crystal display device using the filter substrate 10 for a liquid crystal display device having such a configuration, the efficiency of backlight utilization is improved, and the adverse effects on the contrast, color purity, etc. due to reflection at the substrate interface. Can be prevented.

In FIG. 1, the linear polarizing plate 11 may be integrally provided on the incident side of the glass substrate 1 with an adhesive layer interposed therebetween.

Next, one embodiment of a method of manufacturing such a filter substrate 10 for a liquid crystal display device will be described.

First, the polyimide film 2'on the glass substrate 1.
Is formed (FIG. 2A), and then the polyimide film 2 ′ is subjected to an alignment treatment such as a rubbing treatment to form an alignment layer 2 (FIG. 2B). The thickness of the polyimide film 2 ′ is preferably 0.02 μm or less.

Thereafter, a nematic liquid crystal is applied onto the alignment layer 2 of the glass substrate 1 which has been subjected to the alignment treatment as described above by spin coating or the like, and is cured by using an ultraviolet ray or an electron beam to form a nematic liquid crystal layer. The retardation layer 3 is formed (FIG. 2C). When UV rays are used, a photopolymerization initiator is required. When applying the nematic liquid crystal, it is preferable to apply the nematic liquid crystal in a state of being dissolved in an organic solvent.

Here, as the nematic liquid crystal, Japanese Patent Laid-Open No.
(1) of [Chemical Formula 17] of 001-100045 or [Chemical Formula 1]
A crosslinkable nematic liquid crystal as disclosed in (7) of [8] can be used.

As the organic solvent, toluene, tetrahydrofuran, xylene, acetone, propylene glycol monoethyl ether acetate, 3-methoxybutyl acetate, etc. can be used, and the dilution concentration thereof is adjusted to 5 to 50% ww. It is preferable. In addition,
In addition to spin coating, blade coating, slide coating, die coating and the like can be used as the coating method.

Then, a cholesteric liquid crystal (nematic liquid crystal + chiral agent) is applied on the retardation layer 3 formed on the alignment layer 2 of the glass substrate 1 by spin coating or the like to control the film thickness and then cured. To form a semi-transparent cholesteric liquid crystal filter layer 4 (see FIG. 2).
(D)). The cholesteric liquid crystal is preferably applied and cured by the same method as in the case of the nematic liquid crystal described above. At that time, the same nematic liquid crystal was used, and as the chiral agent, JP-A-2001-1000 was used.
A chiral agent as disclosed in (8) of [Chemical formula 18] or (5) of [Chemical formula 17] of 45 can be used by converting it into an acrylate at the molecular end to be polymerizable.

The amount of the chiral agent added is preferably adjusted appropriately according to the central selective reflection wavelength. The thickness of the cholesteric liquid crystal filter layer 4 is preferably a thickness (for example, 10 μm) necessary for partially reflecting the circularly polarized light component (for example, 70%).

As a result, the filter substrate 10 for a liquid crystal display device, in which the retardation layer 3 made of a nematic liquid crystal layer and the semi-transmissive cholesteric liquid crystal filter layer 4 made of a cholesteric liquid crystal layer are integrally formed on the glass substrate 1, is formed. Manufactured.

In the above description, the semi-transparent cholesteric liquid crystal filter layer 4 formed on the retardation layer 3 uses the alignment regulating force of the surface of the nematic liquid crystal layer of the retardation layer 3 to make the cholesteric liquid crystal filter layer 4 cholesteric. Align the liquid crystal layer.

Of course, another alignment layer (film) may be interposed between the retardation layer 3 and the cholesteric liquid crystal filter layer 4. Further, the surface of the nematic liquid crystal layer of the retardation layer 3 is rubbed to regulate its orientation. The force may be used to orient the cholesteric liquid crystal layer.

Further, the retardation layer 3 having a substantially λ / 4 retardation is formed as described in JP-A-10-68816.
The λ / 2 phase difference layer and the λ / 4 phase difference layer have mutual fast axes of 6
When a film is formed so as to intersect at 0 ± 10 degrees, an alignment layer (film) is provided on the previously formed λ / 2 retardation layer, and λ / 4 is used by using the alignment regulating force. The retardation layer is oriented, or the surface of the previously formed λ / 2 retardation layer is rubbed and the λ / 4 retardation layer is oriented using the orientation regulating force.

Based on the above, a structural example of the filter substrate 10 for a liquid crystal display device according to the present invention is shown in FIG.

FIG. 3A shows a linear polarizing plate 11, an adhesive layer 13, a glass substrate 1, in order from the backlight light source 12 side.
The alignment layer 2, the retardation layer 3 having a λ / 4 retardation, and the semitransparent cholesteric liquid crystal filter layer 4 constitute a filter substrate 10 for a liquid crystal display device. This example is substantially the same as the example of FIG.

FIG. 3B shows a linear polarizing plate 11, an adhesive layer 13, a glass substrate 1, in order from the backlight light source 12 side.
Alignment layer 2, λ / 2 retardation layer 31, λ / 4 retardation layer 32,
The semi-transparent cholesteric liquid crystal filter layer 4 constitutes a filter substrate 10 for a liquid crystal display device. In this example, the retardation layer 3 having the λ / 4 retardation is replaced by the λ / 2 retardation layer 3
1 and a λ / 4 retardation layer 32. The λ / 4 retardation layer 32 on the λ / 2 retardation layer 31 is rubbed on the surface of the λ / 2 retardation layer 31 to regulate its orientation. It is oriented by using force.

FIG. 3C shows a linear polarizing plate 11, an adhesive layer 13, a glass substrate 1, in order from the backlight light source 12 side.
The orientation substrate 2, the λ / 2 retardation layer 31, the orientation layer 33, the λ / 4 retardation layer 32, and the semitransparent cholesteric liquid crystal filter layer 4 constitute the filter substrate 10 for a liquid crystal display device. In this example, the retardation layer 3 having a λ / 4 retardation is set to λ / 2.
This is an example constituted by a retardation layer 31 and a λ / 4 retardation layer 32. An orientation layer 33 is provided on the λ / 2 retardation layer 31, and the λ / 4 retardation layer is oriented by using the orientation regulating force. I am letting you.

Next, one embodiment of a liquid crystal display device using the filter substrate 10 for a liquid crystal display device of the present invention will be described.
FIG. 4 is a sectional view showing the structure of this embodiment.

In FIG. 4, this liquid crystal display device uses, for example, the filter substrate 10 for the liquid crystal display device having the structure shown in FIG. 3A as a backlight side substrate, and together with the glass substrate 20 arranged on the observation side, A liquid crystal layer 21 is sandwiched between the semitransparent cholesteric liquid crystal filter layer 4 side of the liquid crystal display device filter substrate 10 and the glass substrate 20. Here, the semi-transmissive cholesteric liquid crystal filter layer 4 of the liquid crystal display device filter substrate 10 is of a semi-transmissive type for light in all wavelength bands of R (red), G (green), and B (blue). is there.

On the observation side of the observation-side glass substrate 20, there is arranged a circular polarization plate 24 composed of a λ / 4 retardation plate 22 and a linear polarization plate 23, and a filter substrate for a liquid crystal display device. On the incident side of 10, the backlight light source 1
2 and the reflection plate 15 therefor are arranged. It should be noted that the inner surfaces of the substrates 10 and 20 are provided with a pixel electrode that constitutes a pixel and its counter electrode, a TFT (TFD) that controls the voltage applied between the pixel electrode and the counter electrode, an alignment film, etc. Omit it. In this case, the TFT (TFD) may be provided on either side of the substrate 10 or 20, but it is brighter if it is provided on the inner surface of the substrate 10 on the backlight side, especially in the case of a reflection type.

With the above arrangement, in the case of a transmissive display, the naturally polarized white illumination light emitted from the light source 12 is
It becomes linearly polarized light by the linearly polarizing plate 11, the linearly polarized light reaches the retardation layer 3 through the glass substrate 1 and the orientation layer 2, and is converted into, for example, right circularly polarized light (R) by the substantially λ / 4 retardation. Cholesteric liquid crystal filter layer 4 that is semi-transparent immediately
30% of the right-hand circularly polarized light (R) passes through as it is right-handed circularly polarized light (R), and 70% of it remains as right-handed circularly polarized light (R) due to Bragg reflection to the backlight side. To be done.

The white right circularly polarized light (R) of 30% of the transmitted light reaches the liquid crystal layer 21 and remains right circularly polarized light (R) or is converted to left circularly polarized light (L) depending on the modulation state of the pixel. Is
When the light reaches the circularly polarizing plate 24 but remains right circularly polarized (R), it goes through the circularly polarizing plate 24 as linearly polarized light to the observation side to display a bright state. Further, when the light is converted into left circularly polarized light (L), it is left circularly polarized light that is the opposite of the circularly polarized light that the circularly polarizing plate 24 allows to pass therethrough, and is blocked here to display a dark state.

The remaining, for example, 70% of the right circularly polarized light (R) reflected by the semi-transmissive cholesteric liquid crystal filter layer 4 is transmitted through the retardation layer 3 having a λ / 4 retardation in the opposite direction. And returns to linearly polarized light, passes through the linearly polarizing plate 11, and returns to the light source 12 side.

The light reflected by the semi-transmissive cholesteric liquid crystal filter layer 4 and returned to the light source 12 side is reflected and scattered by the reflecting plate 15 and the like and is used again as illumination light, so that the utilization efficiency of the backlight is improved, Bright display is possible.

Next, in the case of a reflection type display by external light, it becomes right circularly polarized light (R) through the circularly polarizing plate 24, and the liquid crystal layer 21 is left circularly polarized light (R) or left circularly polarized light (R). When converted to L) and left circularly polarized light (R) remains, it is reflected by the semi-transmissive cholesteric liquid crystal filter layer 4 by 70%, transmitted through the liquid crystal layer 21 again, and linearly passed through the circularly polarizing plate 24. It goes out to the observation side as polarized light and displays the bright state. When the liquid crystal layer 21 is converted into left-handed circularly polarized light (L), it is transmitted through the semi-transmissive cholesteric liquid crystal filter layer 4 and substantially λ /
The light reaches the retardation layer 3 having four phase differences and is converted into linearly polarized light which is orthogonal to the linearly polarized light that the linearly polarizing plate 11 passes, so that the linearly polarizing plate 11 blocks the light and displays a dark state.

In the above embodiment, the linear polarization plate 11 on the incident side of the backlight absorbs and cuts the other linearly polarized light emitted from the backlight light source 12.
A circularly polarized light selection layer that reflects one of right-handed circularly polarized light and left-handed circularly polarized light and transmits the other, as disclosed in JP-A-10-232313, and a quarter-wave plate are laminated on the incident side. By arranging the circularly polarized light separating film, one circularly polarized light component emitted from the backlight light source 12 is used for illumination and the other circularly polarized light component that cannot be transmitted is reflected, whereby the backlight utilization efficiency is further improved. To do.

Although the filter substrate for a liquid crystal display device, the method for manufacturing the same, and the liquid crystal display device using the same according to the present invention have been described above based on some embodiments, the present invention is not limited to these embodiments. Various modifications are possible.

[0054]

As is apparent from the above description, according to the filter substrate for a liquid crystal display device, the method for manufacturing the same and the liquid crystal display device using the same, the filter substrate for a liquid crystal display device is formed on the transparent substrate. In order, a retardation layer for converting incident linearly polarized light into circularly polarized light and a cholesteric liquid crystal filter having a function of selectively reflecting the circularly polarized light converted by the retardation layer are provided, and a wavelength band selectively reflected by the cholesteric liquid crystal filter. Since it has a function of transmitting a part of the light inside, and the difference in average refractive index between the retardation layer and the cholesteric liquid crystal filter is 0.05 or less, for example, a liquid crystal display capable of reflective and transmissive display. It is possible to improve the backlight utilization efficiency of the device and prevent adverse effects on the contrast, color purity, etc. due to the interface reflection of the backlight side substrate.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an example of a filter substrate for a liquid crystal display device of the present invention.

FIG. 2 is a diagram illustrating a method for manufacturing a filter substrate for a liquid crystal display device of the present invention.

FIG. 3 is a diagram showing a configuration example of a filter substrate for a liquid crystal display device according to the present invention.

FIG. 4 is a cross-sectional view showing a configuration of one embodiment of a liquid crystal display device using the filter substrate for a liquid crystal display device of the present invention.

FIG. 5 is a diagram for explaining a problem of a conventional filter substrate for a liquid crystal display device.

[Explanation of symbols]

1 ... Glass substrate 2 ... Alignment layer 2 '... Polyimide film 3 ... Retardation layer having substantially λ / 4 retardation 4 ... Semi-transparent cholesteric liquid crystal filter layer 10 ... Filter substrate for liquid crystal display device 11 ... Linear polarizing plate 12 ... Backlight light source 13 ... Adhesive layer 15 ... Reflector 20 ... Glass substrate 21 ... Liquid crystal layer 22 ... λ / 4 retardation plate 23 ... Linear polarizing plate 24 ... Circularly polarizing plate 31 ... λ / 2 retardation layer 32 ... λ / 4 retardation layer 33 ... Alignment layer

Claims (9)

[Claims] 1. A transparent substrate is provided with a retardation layer for converting incident linearly polarized light into circularly polarized light and a cholesteric liquid crystal filter having a function of selectively reflecting the circularly polarized light converted by the retardation layer, in order. The cholesteric liquid crystal filter has a function of transmitting a part of the light in the selectively reflected wavelength band, and the difference in average refractive index between the retardation layer and the cholesteric liquid crystal filter is 0.05 or less. A characteristic filter substrate for liquid crystal display devices. 2. The cholesteric liquid crystal filter,
The filter substrate for a liquid crystal display device according to claim 1, wherein a cross-linkable nematic liquid crystal and a cross-linkable chiral agent are main components, and the retardation layer is the nematic liquid crystal main component. 3. The retardation layer comprises a λ / 2 retardation layer and a λ /
The filter substrate for a liquid crystal display device according to claim 1 or 2, wherein the filter substrate comprises four retardation layers, and fast axes of the four retardation layers intersect at 60 ± 10 degrees. 4. The filter substrate for a liquid crystal display device according to claim 1, wherein a linear polarizing plate is attached to the opposite side surface of the transparent substrate. 5. A cross-linkable nematic liquid crystal coated on an alignment film on a transparent substrate is cross-linked to form a film, and a mixture of a separately prepared cross-linkable nematic liquid crystal and a cross-linkable chiral agent is coated thereon. And cross-linked to form a film.
A method for producing a filter substrate for a liquid crystal display device as described above. 6. A crosslinkable nematic liquid crystal coated on an alignment film on a transparent substrate is crosslinked to form a λ / 2 retardation layer, on which a crosslinkable nematic liquid crystal is coated and crosslinked to form a λ / 4 position. 5. A retardation layer, which is coated with a separately prepared liquid mixture of a crosslinkable nematic liquid crystal and a crosslinkable chiral agent and crosslinked to form a film. A method for manufacturing a filter substrate for a liquid crystal display device according to item. 7. The surface of the λ / 2 retardation layer is rubbed in an arbitrary direction, and the fast axes of the λ / 2 retardation layers intersect each other at 60 ± 10 degrees by using the alignment regulating force of the surface of the λ / 2 retardation layer. 7. The method for manufacturing a filter substrate for a liquid crystal display device according to claim 6, wherein. 8. An alignment film is formed on the surface of a λ / 2 retardation layer and then rubbed in an arbitrary direction, and the mutual fast axes are 60 by using the alignment regulating force of the surface of the λ / 2 retardation layer. 7. The method for manufacturing a filter substrate for a liquid crystal display device according to claim 6, wherein the filters intersect at ± 10 degrees. 9. A liquid crystal layer for modulating the phase of incident light according to an applied voltage is sandwiched between two transparent substrates, and an electrode and a drive circuit for independently applying a voltage to each pixel are provided in the liquid crystal layer. A liquid crystal display element, an illumination light source provided on the side opposite to the observation side, a circular polarization means arranged between the illumination light source and the liquid crystal layer, and a circle provided on the observation side of the liquid crystal display element. A liquid crystal display device comprising a polarizing means, wherein the liquid crystal display device filter substrate according to any one of claims 1 to 4 is arranged as a transparent substrate on the backlight side of the liquid crystal display element. Liquid crystal display device.