JPH10228015A - Display device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a monochromatic display with a white background or a high-contrast color display which has high reflected light intensity and is uniform and bright by applying a voltage to a composite multi-layered film formed by laminating films and liquid crystal layers alternately more than once and controlling the light reflection factor. SOLUTION: Liquid crystal layers 8 to 11 and plastic films 5 to 7 are put one over the other alternately to constitute the composite multi-layered film 18. Here, when a liquid crystal material and a film material which have specific refractive indexes are selected, there is no refractive index difference at the borders between the liquid crystal layers 8 to 11 and films 5 to 7 in a voltage application area 14 and incident light 16 is passed as it is. In a voltage nonapplication area 13, on the other hand, the incident light 15 is reflected most intensely to have interference by properly setting the thickness of the liquid crystal layers 8 to 11 and the thickness of films 5 to 7. The more the number of the layers, the larger the intensity of the reflected light 17; and the number of layers is preferably >=10. Consequently, an optical modulating element is formed which passes the incident light 16 at the time of voltage application and reflects the incident light 16 in the absence of the voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a liquid crystal device using a composite multilayer film of a liquid crystal and a film, and a method of manufacturing the same. The present invention also relates to a display device which controls reflection / transmission by the liquid crystal device.

[0002]

2. Description of the Related Art Conventionally, a reflection type liquid crystal display device has been greatly developed and spread as a display device operated with a small amount of electric power, as an information transmission medium for watches, calculators, cellular phones, small portable devices, various home electric appliances and the like. Was. Display mode is also T
Various inventions such as N (twisted nematic) type, STN (super twisted nematic) type, and ferroelectric type have been made. However, these all use a polarizing plate, and in reality, about 60% of the incident light to the liquid crystal element is used.
Is dark because it is absorbed by the polarizing plate, and is far from easy to see, such as an ideal reflective display, for example, a black display on a white background.

In particular, in a reflective type color liquid crystal display device, light is absorbed by both the polarizing plate and the color filter, so that at most 10% or less of the external light incident on the display device is reflected and displayed. It was far inferior to bright, vivid color displays, such as very dark, printed displays.

Recently, as a method of solving the above-mentioned disadvantages and realizing a bright color display without using a polarizing plate,
Conventional example 1 (Japanese Patent Laid-Open No. 6-294952) has been proposed and attracted attention. In this proposal, a mixture of a liquid crystal material and a polymer material made of a photo-curable resin is inserted between a pair of substrates, and laser light is irradiated from two directions, upper and lower, to form a mixture of the two laser lights. By the interference pattern, light intensity stripes are obtained in a mixed layer of liquid crystal and a polymer material. Then, the polymer photo-curable resin is photo-cured in layers according to the strong and weak stripe patterns, and a multilayer film of polymer photo-curable resin layer / liquid crystal layer / polymer photo-curable resin layer / liquid crystal layer /. It realizes interference and reflects light in a specific wavelength range according to the principle of composite multilayer interference reflection. When a voltage is applied to the multilayer film by the electrodes on the inner surfaces of the pair of substrates, the direction of the molecular axis of the liquid crystal molecules in the liquid crystal layer changes, and accordingly, the refractive index of the liquid crystal layer also changes. Therefore, the condition of the interference reflection is deviated, and the intensity of the reflected light also changes. In this manner, light modulation by voltage becomes possible, and functions as a display device.

In the above-described display device, since no polarizing plate is used, a bright color can be obtained, and the interference pitch can be freely selected by changing the wavelength or the irradiation angle of the irradiation laser light, thereby making it possible to freely select the interference pitch. Since the interference pitch can be freely selected, any desired display color can be realized. In particular, the reflection type color display device is superior to the conventional TN type and STN type reflection type color display devices.

However, as a disadvantage of the above-described display device,
For example, Conventional Example 2 (ASIA DISPLAY '95
As shown in P603 to 606), since the layer of the photocurable resin is formed by interference of two laser beams, the interference pitch becomes extremely high, and the wavelength width of the interference reflected light is very narrow. Therefore, although the color is vivid, the reflection type display lacks brightness. Normally, white is most desirable as the background color of the reflective display. For this purpose, it is necessary to satisfy the condition of interference reflection over a wide wavelength range of visible light.
Then, due to the structure, it is extremely difficult to continuously change the interference pitch above and below the layer, and there is a problem in obtaining a bright white display. The second problem is that the interface between the photocurable resin and the liquid crystal layer is preferably flat (flat) in order to increase the intensity of interference reflection. However, as shown in the conventional example 2, the interface has fine irregularities. In contact. Therefore, not all incident light causes interference reflection, but a part of light is transmitted, which is a problem in realizing a brighter reflective display device.

Next, as another conventional example, a conventional example 3 (Japanese Patent Application Laid-Open No. 4-178623) is cited as an example of a bright reflective color display device utilizing interference reflection without using a polarizing plate. In this conventional example, the liquid crystal layer and S
The iO ₂ layers are superposed, the thickness and the refractive index of each layer are set so as to conform to the conditions of interference reflection, and selective reflection of a specific wavelength is caused. When a voltage is applied between the upper and lower electrodes, the refractive index of the liquid crystal layer changes in the same manner as described above, deviating from the interference reflection condition, and the intensity of reflected light changes, so that a display function can be realized. The problem of this conventional example is that the layer causing interference reflection is SiO ₂ film / liquid crystal layer / S
It is composed of only three layers of iO ₂ film, which does not provide sufficient interference reflected light intensity, and transmits most of the incident light and is absorbed by the lower light absorbing layer, so that it has sufficient brightness. A reflective display device cannot be realized. To increase the intensity of reflected light, although the SiO ₂ film / liquid crystal layer / SiO ₂ film film / liquid crystal layer / SiO ₂ film.. At least 10 or more layers of the composite multilayer film is preferable, in this conventional example, the composite multilayer Formation of the film is extremely difficult. In other words, directly on the liquid crystal layer,
_In this case, a spacer layer is once formed on the entire surface, and S
After forming the _i O ₂ film, leaving the spacer periphery only, the other portions are removed by etching, and injecting a liquid crystal into an empty bubble portion which is its removal, to form a liquid crystal layer. It on the liquid crystal layer, in direct S _i O ₂ film that can be no difficulty arising from the reason for forming, it is clear that it is not realistic to produce a composite multi-layer film in this structure 10 or more layers . Further, in this conventional example, since the liquid crystal is injected into the void portion removed by over-etching, the alignment process for aligning the liquid crystal molecular axis direction cannot be performed, and the molecular axis direction of the injected liquid crystal is disjointed in a domain. It is considered to be in a state. Normally, in order to increase the intensity of the interference reflected light, it is important to control the thickness and the refractive index of the liquid crystal layer with high accuracy, and in this conventional example, it is difficult to precisely control the refractive index as described above. Sufficient intensity of interference reflected light was not obtained, and there was a problem in realizing a uniform and bright reflective display device.

[0008]

As described above, in the prior art, it is difficult for a reflection type liquid crystal display device to satisfy the condition of interference reflection in a wide wavelength band of a visible light wavelength range. Not all incident light causes interference reflection, but part of the light is transmitted.There is a problem in realizing a brighter reflective display device, and precise control of the refractive index is difficult. However, there has been a problem in realizing a uniform and bright reflective display device in which sufficient interference reflected light intensity cannot be obtained.

The present invention has been made to solve the above-mentioned problems, and has a uniform and bright display device having high reflected light intensity.
Further, it is possible to realize a monochrome display in which the background is white and a black display, or a display device which is capable of performing a color display with high contrast and which is easy to see.
It is an object of the present invention to provide a method for easily and accurately producing a composite multilayer film having zero or more layers.

[0010]

According to the present invention, in order to solve the above problems, first, a composite multilayer film in which a film and a liquid crystal layer are alternately laminated a plurality of times is sandwiched between a pair of substrates; A voltage is applied to the composite multilayer film to control light reflectance in the composite multilayer film.

Second, light scattering means is arranged outside one of the substrates, and light absorbing means is provided outside the other substrate.

Third, the liquid crystal layer is made of a nematic liquid crystal, a smectic liquid crystal, a nematic liquid crystal, a nematic polymer liquid crystal, a smectic polymer liquid crystal, or a mixture thereof.

Fourth, the liquid crystal layer is made of a discotic liquid crystal or a mixture of a discotic liquid crystal and a nematic liquid crystal.

Fifth, the liquid crystal layer is composed of nematic liquid crystal molecules, and the major axis of the liquid crystal molecules is arranged substantially horizontally with respect to the substrate or the film when no voltage is applied. .

Sixth, the liquid crystal layer is composed of nematic liquid crystal molecules, and the major axis of the liquid crystal molecules is arranged substantially perpendicular to the substrate or the film when no voltage is applied. .

Seventhly, the light absorbing means absorbs light in an arbitrary wavelength band or a wavelength band in a visible light region that passes through the composite multilayer film.

Eighth, a composite multilayer film in which a film and a liquid crystal layer are alternately laminated a plurality of times is sandwiched between a pair of substrates having electrodes on the inner surface, and electrodes are provided on both surfaces in an intermediate portion of the composite multilayer film. One or more intermediate substrates are interposed, and light scattering means is arranged outside one of the substrates, and light absorbing means is arranged outside the other substrate.

Ninth, the thicknesses of the liquid crystal layer and the film are set so that the composite multilayer film reflects light of at least a part of the wavelength of the incident visible light region when no voltage is applied. It is characterized by.

Tenth, the thickness of the liquid crystal layer and the film is set so that the composite multilayer film reflects light having at least a part of the wavelength of the incident visible light region when a voltage is applied. It is characterized by.

Eleventh, the liquid crystal layer is characterized in that at least one of the refractive indices in the major axis and minor axis directions of the liquid crystal molecules is made to substantially match the refractive index of the film.

Twelfth, in each of the composite multilayer films, the layer thickness of the film and the liquid crystal layer are made the same, and between different composite multilayer films, the layer thicknesses of the liquid crystal layer and the film are made different from each other. A plurality of the composite multilayer films are stacked to reflect a plurality of wavelengths of incident light.

Thirteenth, in each of the composite multilayer films, the film thickness and the liquid crystal layer thickness are made the same, and between different composite multilayer films, the liquid crystal layer and the film thickness are made different from each other. The composite liquid crystal layer and the film thickness are set such that the composite multilayer films are stacked, and the composite multilayer films reflect red light, green light, and blue light. I do.

Fourteenth, the invention is characterized in that electrodes for independently applying a voltage are arranged for each of the composite multilayer films.

Fifteenth, the liquid crystal layer is composed of nematic liquid crystal molecules, and is set so as to reflect light having a polarization component substantially in the major axis direction of the nematic liquid crystal molecules or in a direction substantially orthogonal to the major axis direction. At least a composite multilayer film.

Sixteenth, the film is characterized in that it is an optically substantially uniaxial film or a stretched film.

Seventeenth, the composite multilayer film is divided into two blocks, and the liquid crystal molecule long axis direction of the liquid crystal layer of the first block and the liquid crystal molecule long axis direction of the liquid crystal layer of the second block are substantially orthogonal to each other. And at least a composite multilayer film in which the first and second blocks are stacked.

Eighteenth, the invention is characterized in that electrodes for independently applying a voltage are arranged in the first and second blocks.

Nineteenthly, the material of the liquid crystal layer is applied to at least one of the film surfaces, and the film coated with the liquid crystal material is overlaid with a plurality of layer rollers and integrated to form the composite multilayer film. It is characterized by having done.

Twentiethly, the invention is characterized in that when superimposed by the rollers, the liquid crystal layers are integrated while being heated to a predetermined temperature to reduce the viscosity of the liquid crystal layer.

Twenty-first, the film is preliminarily subjected to a uniaxial stretching treatment so as to have an alignment function for aligning liquid crystal molecules.

Twenty-second, the material of the liquid crystal layer is coated on the film surface, the film coated with the liquid crystal material is overlapped with a plurality of layer rollers, integrated, and then stretched with a rolling roller. The composite multilayer film is formed by adjusting the thickness of the film and the thickness of the liquid crystal layer to predetermined values.

Twenty-third is characterized in that the film is made conductive.

Twenty-fourth, the composite multilayer film is characterized by comprising at least ten layers of the liquid crystal layer and the film.

Twenty-fifth, the composite multilayer film is formed by laminating at least 21 layers of the liquid crystal layer and the film.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a diagram showing a basic structure of a display device according to the present invention and a display principle thereof, that is, a diagram showing a basic structure of a light modulation element for controlling reflection / transmission. . 1 and 2 are made of a transparent plastic plate, a transparent plastic film, or a transparent glass plate, and the lower substrate, 3 and 4 are the upper and lower substrates 1, 2
In the transparent electrode layer formed respectively, indium oxide,
It consists of tin oxide or a mixture thereof. 8, 9, 1
Reference numerals 0, 11 denote liquid crystal layers, 5, 6, 7 are plastic films (hereinafter simply referred to as films), and the liquid crystal layers 8, 9, 1,
The films 0, 11 and the films 5, 6, 7 alternately overlap to form a composite multilayer film 18. 12 is the upper and lower substrates 1,
The display device of the present invention is basically configured by the peripheral seal portion for bonding and fixing 2. In the present embodiment, the liquid crystal layers 8, 9, 10, and 11 use nematic liquid crystal having a positive dielectric anisotropy, and the major axis of the liquid crystal molecules is the film 5,
The planes 6 and 7 are oriented substantially horizontally.

FIGS. 2 (a) and 2 (b) show the display principle of the present invention, wherein the films 5, 6, 7 and the liquid crystal layers 8, 9,
10 and 11 are extracted and shown. Accordingly, the drawing numbers correspond to the respective films and the respective liquid crystal layers in FIG. FIG.
FIG. 1A shows a region 13 in FIG. 1, that is, a region where no voltage is applied between the upper and lower electrodes 3 and 4 (specifically, it may be considered to indicate a region where a voltage lower than the threshold voltage of the liquid crystal is applied). Hereinafter, the state where no voltage is applied in each embodiment and each example may be considered to be the same state.) FIG. Here, the liquid crystal molecules are oriented substantially horizontally with respect to the film surface, and the refractive index of the liquid crystal layer in the long axis direction of the liquid crystal molecules is n _LC1 . FIG. 2 ((b)
1 indicates a region 14 in FIG. 1, that is, a region where a voltage is applied between the upper and lower electrodes 3 and 4 (specifically, a region where a saturation voltage of the liquid crystal is applied. And a state of voltage application in each embodiment may be considered to be a similar state.) Here, the liquid crystal molecules are oriented substantially perpendicularly to the film surface, and the refractive index of the liquid crystal layer is the refractive index n in the minor axis direction of the liquid crystal molecules.
_LC2 . Due to the general properties of the nematic liquid crystal, the refractive index of the liquid crystal layer changes depending on whether or not a voltage is applied, and n _LC1 > n _LC2 (1). Therefore, n _LC2 ≒ n _F (n _F is the refractive index of the film) (2) A liquid crystal material and a film material satisfying the expression (2) are selected, and the liquid crystal layers 8, 9, 10, 11 and Film 5,
1 and 2B, in the voltage application region 14, there is no difference in the refractive index at the boundary between the liquid crystal layer and the film, and the incident light 16 is transmitted as it is, as shown in FIGS.

Actually, as described above, the liquid crystal molecules are not arranged vertically to the film surface in all the layers of the liquid crystal layer, and the liquid crystal molecules close to the film surface are horizontal to the film surface. Take an array with directional components. Therefore, the average refractive index of each liquid crystal layer at this time does not become n _LC2 , but is larger than that, _<< n _LC2 >> ( _<< n _{LC2 >>>} n _LC2 ).
Becomes In this case, when the refractive index n _{F of the} film is set to _<< n _LC2 >>, that is, when _<< n _LC2 >> = n _F (2) ', the incident light 16 is transmitted most strongly.

More preferably, the film has a slight birefringence (the refractive index in the X-axis direction is n _F1 and the refractive index in the Y-axis direction is n _F1) .
_F2 . Here, the X axis direction is the major axis direction of the liquid crystal molecules adjacent to the film, and the Y axis direction is the same minor axis direction. ) 《N _LC2 》 = N _F1 ... (2) '' n _LC2 = n _F2 ... (2) '' ′, the incident light 16 is transmitted almost entirely except for reflection loss at the front and back surfaces.

Next, in the voltage non-applied area 13, reference 1 (Applied Optics II, written by Masao Tsuruta, 4-3-3 (II))
As shown in the following formulas (3) and (4), n _LC1 · d _LC = (１ ／ + m / 2) λ ₀ (d _LC is the thickness of the liquid crystal layers 8, 9, 10, and 11, and λ ₀ is the incident light. Wavelengths of 15 and 16; m is 0 or an arbitrary integer) (3) n _F · d _F = (１ ／ + k / 2) λ ₀ (d _F is the thickness of the film 5, 6, 7; k is 0 or any integer) (4) so that the thickness of the liquid crystal layers 8, 9, 10, 11 is satisfied;
If the thickness of the films 5, 6, 7 is set, FIG.
As shown in (a), the incident light 15 having the wavelength λ ₀ is reflected most strongly by interference.

The intensity of the reflected light 17 increases as the number of liquid crystal layers and films increases, in other words, as the number of layers of the composite multilayer film increases. Although only seven layers in total of the film and the liquid crystal layer are illustrated in the drawings of the present embodiment, preferably, ten or more layers are good.

As described above, the nematic liquid crystal material having a positive dielectric anisotropy and the film material are represented by the formula (2) and the formula (2) ′.
Formula (2) ″ and Formula (2) ″ ′ are selected so as to satisfy the formulas, and the thickness of the liquid crystal layer and the thickness of the film are combined so as to satisfy the formulas (3) and (4). If the liquid crystal layer and the film are alternately stacked, preferably 10 layers or more, a light modulation element that transmits incident light when a voltage is applied and reflects the incident light when no voltage is applied is formed, and it can be seen that the light modulation element functions as a display device. Further, it is apparent that the display device described above does not use a polarizing plate that absorbs light, and is a bright display device that effectively utilizes light. Further, since the boundary surface between the film and the liquid crystal layer is flat, it can be seen that the interference reflection intensity is superior in brightness as compared with Conventional Example 1.

In the above-described first embodiment, a nematic liquid crystal material is used for the liquid crystal layer. However, the material has a birefringent property, and the liquid crystal molecules change in the direction of the liquid crystal molecules by an electric field, and the refractive index changes accordingly. Any material can be used.In addition to nematic liquid crystals, materials such as smectic liquid crystals, chiral smectic liquid crystals, polymer liquid crystals in which nematic liquid crystal molecules or smectic liquid crystal molecules are bonded to polymer chains, and mixtures of the above liquid crystals and polymer liquid crystals are also used. Can be used as a layer.

In particular, when the discotic liquid crystal disclosed in Reference 2 (Liquid Crystal, Basic Edition, written by Kouji Okano and Shunsuke Kobayashi, Baifukan, 1.3) is used, birefringence having an optically negative uniaxial property is obtained. Therefore, when the film is oriented substantially horizontally on the film layer, the refractive index with respect to the incident light becomes uniform in all polarization directions, and a stronger multilayer interference reflection is obtained. In this case, the molecular direction of only the discotic liquid crystal itself may be controlled by an electric field, but in particular, when a liquid crystal in which a nematic liquid crystal and a discotic liquid crystal are mixed is used, the viscosity decreases, and the direction of the molecular axis is more easily adjusted according to the electric field. Can be changed.

When this embodiment is used as a reflection type display device, a light absorption layer may be arranged outside the lower substrate 2.
A display device having a wavelength of λ _{0 in a} region where no voltage is applied, and a black display due to absorption of transmitted light in a region where a voltage is applied, and a display device having a high contrast without a polarizing plate can be realized.

(Second Embodiment) Next, a display device according to a second embodiment of the present invention will be described with reference to FIG. 31, 32
Have transparent electrode films 33 and 34 on the upper and lower substrates, respectively, on surfaces facing each other. 23, 24, 25, 26
Are liquid crystal layers, 27, 28 and 29 are films, respectively.
As shown, each liquid crystal layer and each film alternately overlap each other to form a composite multilayer film 30 as a whole. Reference numeral 35 denotes a peripheral seal portion made of epoxy resin or the like and fixing the upper and lower substrates. In the present embodiment, a nematic liquid crystal material having a positive dielectric anisotropy is used for the liquid crystal layers 23, 24, and 2.
Nos. 5 and 26, and are oriented substantially horizontally with respect to each film surface.

The birefringence of the nematic liquid crystal material is represented by n
_LC1 '(Long axis direction of liquid crystal molecules), _nLC2 ' (The short axis direction of the liquid crystal molecules), and n _LC1 ′ > N _LC2 ' Set so that On the other hand, the films 27, 28, and 29 are films having uniaxial birefringence, and the refractive indices are n _F1 ′ in the X-axis direction and n _F2 ′ in the Y-axis direction.
Set so that n _F1 '> n _F2 '. In general, when a film is stretched, it is known that many film materials exhibit a uniaxial birefringence in which the optical axis refractive index in the stretching direction is large and the optical axis refractive index in the direction perpendicular to the stretching direction is small. Have been. In this case, the stretching direction is the X axis, and the direction orthogonal to the X axis is the Y axis. The nematic liquid crystal molecules are arranged horizontally with respect to the respective surfaces of the films 27, 28, and 29, and the molecular major axis direction is arranged in the X-axis direction of the film.

Further, in the present embodiment, conditions are set such that the incident light 36 having the wavelength λ ₀ is transmitted in the no-voltage application region 40. That is, for a wavelength λ ₀ , n _LC2 ′ ・ D _LC '≒ (1/4 + m / 2) λ ₀ ... (6) n _F1 ' · d _F ' ≒ (1/4 + k / 2) λ ₀ (6) ′ (d _LC ′ and d _F ′ Are the liquid crystal layers 23, 24, 2
5, 26 and thickness of film 27, 28, 29, k, m
Is 0 or an arbitrary integer) so that the thickness of each liquid crystal layer (d _LC ') and the thickness of each film (d _F ') are satisfied. ) Is set, the incident light 36 of the wavelength λ ₀ is transmitted in the no-voltage application region 40, and the incident light 37 of the wavelength λ ₀ is reflected in the voltage application region 39 to become a reflected light 38.

As described above, also in this embodiment, in order to increase the intensity of reflected light and obtain a bright display device, the number of liquid crystal layers and films of the composite multilayer film 30 must be at least 10 layers.
It is preferred to have more than one layer. As described above, in the present embodiment, a display device that reflects incident light when a voltage is applied and transmits incident light when a voltage is not applied allows a pattern display reverse to that of the first embodiment.

When the present embodiment is also used as a reflection type display device, a light absorbing layer may be arranged outside the lower substrate 32, and the region where no voltage is applied absorbs the transmitted light to give a black display. In the application region, light of wavelength λ ₀ is displayed, and a display device having a high contrast without a polarizing plate can be realized.

(Third Embodiment) FIG. 4 shows a third embodiment of the present invention. Reference numerals 41 and 42 denote upper and lower substrates, 43 and 44, respectively.
Is a transparent electrode formed on each of the upper and lower substrates 41 and 42 facing each other, and 45 is a peripheral seal portion made of epoxy resin or the like and fixing the upper and lower substrates. 4
6, 47, 48, 49 are liquid crystal layers, and films 50, 5
The composite multilayer film 57 is formed by alternately laminating the composite multilayer films 1 and 52 with each other. In this embodiment, the liquid crystal layers 46, 4
Nematic liquid crystal materials are used for 7, 48 and 49, and the molecular arrangement of the nematic liquid crystal material is such that when no voltage is applied,
Upper and lower substrates 41, 42, and films 50, 51, 52
The major axes of the liquid crystal molecules are aligned substantially perpendicularly (homeotropic alignment) with respect to each surface. If a liquid crystal material having a negative dielectric anisotropy is selected as the nematic liquid crystal, the liquid crystal molecules in the voltage application region 54 where a substantially saturated voltage is applied between the upper and lower electrodes 43 and 44 are applied to the upper and lower substrates 41. , 4
2 and the film 50, 51, 52 are oriented substantially horizontally. The refractive index of the above nematic liquid crystal material in the molecular long axis direction is represented by n _LC1 ″. , The refractive index in the minor axis direction of the molecule is n _LC2 '' (N _LC1 '' > N _LC2 '' ), And n _LC2 ″ for the wavelength λ ₀ of the incident light 55, 56. ≒ n _F1 ″ ≒ n _F2 ″ (7) (n _F1 ″ and n _F2 ″ are films 50, 51,
The refractive index in the X-axis and Y-axis directions of 52) The liquid crystal layers 46, 47, 48,
49 and the materials of the films 50, 51, and 52, the area between the film and the liquid crystal layer in the voltage non-applied area (specifically, the area where the voltage is applied below the threshold voltage of the liquid crystal) 53 The surface has almost no difference in the refractive index, and the incident light 55 having the wavelength λ ₀ is substantially transmitted.

Here, as described above, it is most preferable that the average refractive index _<< n _LC2 ″ >> of the liquid crystal layers 46, 47, 48 and 49 with respect to the incident light 55 and the refractive index of the film coincide with each other. This is effective for obtaining strong transmitted light.

Further, if the liquid crystal layer thickness and the film thickness are set so as to satisfy the following equations (8) and (8) ′ with respect to the incident light wavelength λ ₀ , n _LC1 ″ D _LC ″ ≒ (1/4 + m / 2) λ ₀ ... (8) n _F1 ″ d _F ″ ≒ (1/4 + k / 2) λ ₀ (8) ′ (d _LC ″ and d _F ″ Are the liquid crystal layers 46, 47, respectively.
48, 49 and the thickness of the films 50, 51, 52, k,
m is 0 or any integer), and the wavelength λ
_{The zero} incident light 56 is strongly interference reflected by the composite multilayer film 57. As described above, depending on the presence or absence of the application of the voltage, it is possible to switch the reflection / transmission of the incident light and function as a display device.

When this embodiment is used as a reflection type display device, a light absorbing layer may be provided outside the lower substrate 42.
Then, the transmitted light is absorbed in the no-voltage application region to display black, and in the voltage application region, light of wavelength λ ₀ is displayed. Thus, a display device with a high contrast without a polarizing plate can be realized.

Although three embodiments have been described above, it is desirable that the display device be a bright display device in which the wavelength band of the interference reflection wavelength (λ ₀ ) is widened.

In order to obtain the most desirable white reflected light,
In each wavelength region of each color such as red, green and blue, each composite multilayer film which satisfies the above-mentioned interference reflection condition is prepared, and a multi-composite multilayer film obtained by superposing them is used. Also, a bright display device can be realized by using a composite multilayer film in which the thickness of each of the liquid crystal layer and the film is continuously changed, preferably 100 layers or more. Furthermore, when a discotic liquid crystal is used instead of the nematic liquid crystal used in the above embodiment, a substantially uniform refractive index of the light (refractive for each polarized light of the incident light) can be obtained in a state where the film is oriented substantially horizontally. (Approximately uniform), resulting in a display device having higher light reflectance and higher brightness. In addition, (2), (2) ′, (5),
In Equations (5) ′ and (7), the refractive index of one of the liquid crystal layers and the refractive index of the film are made to match with respect to the wavelength λ ₀ so that incident light is transmitted. It is preferable to realize a refractive index that satisfies each of the above-described formulas. For this purpose, the wavelength dispersion of the refractive index of the film material and the wavelength dispersion of the refractive index of the liquid crystal material are matched as much as possible. It is important for selection. However, it is generally difficult to match the wavelength dispersion of the liquid crystal and the film,
In this case, the film material is fixed, and the refractive index of the liquid crystal material is determined by the component mixing ratio so as to satisfy the expressions (2), (2) ′, (5), (5) ′, and (7) for each interference reflection wavelength. The method of adjustment is realistic.

(Fourth Embodiment) Next, a fourth embodiment of a bright reflective display device according to the present invention will be described with reference to FIG. 148, 149, 150, 151 are liquid crystal layers, 14
5, 146 and 147 are film layers which alternately overlap to form a composite multilayer film 159. The liquid crystal layers 148, 149, 150, 151 and the film 145,
As described in the first embodiment, the refractive indices and thicknesses of the respective layers 146 and 147 are calculated by the equations (1), (2), (2) ′,
The composite multilayer film 159 is set to substantially satisfy (3) and (4). Reference numeral 152 denotes a light scattering portion formed of a light scattering layer or a light scattering plate formed on the upper substrate 142. Fifteen
Reference numeral 3 denotes a light absorbing portion formed of a light absorbing layer or a light absorbing plate formed below the lower substrate 141. The operation of this embodiment is as follows.
First, the light 156 incident on the no-voltage application region 154 is interference-reflected as shown in the first embodiment, and the reflected light becomes scattered light 158 by the light scattering section 152 and is emitted to the outside.
Therefore, the reflected light is not easily reflected light like a mirror surface but is easily scattered reflected light like reflected light from a paper surface. On the other hand, in the voltage application region 155, the incident light 157 is transmitted as it is, reaches the light absorbing portion 153 and is absorbed as described in the first embodiment. Therefore, the color of the light absorbing portion 153 is observed in the voltage application region 155.

In this embodiment, each of the liquid crystal layers 148, 149,
150, 151 are all equal in thickness, and each film 1
Since the thicknesses of 45, 146, and 147 were all set to be equal, voltage control of transmission / reflection could be performed only with light having a limited wavelength λ _0. In order to satisfy the reflection condition, the individual narrow wavelength ranges (λ ₀ , λ ₁ , λ ₂ ,.
.., λ _n ), the composite multilayer film of the above-described embodiment is provided so as to satisfy the interference reflection condition, and n composite multilayer films having different wavelengths for interference reflection are laminated, and each of the liquid crystal layers and the film is formed. The thickness combination may be changed along the light traveling direction to increase the total number of layers. That is, as mentioned above,
In the wavelength ranges of each color such as red, green, and blue, each composite multilayer film satisfying the interference reflection condition is prepared, and a multiple composite multilayer film obtained by superimposing them is used as the composite multilayer film 159.
It is also possible to display black display on a white background (or display white on a black background). In this case, it is needless to say that the light absorbing section 153 needs to be black.

According to the fourth embodiment, a plurality of composite multilayer films satisfying the conditions of interference reflection corresponding to each wavelength range of visible light do not cause light absorption by the polarizing plate unlike the conventional example.
Also, unlike conventional examples 1 and 2, since the boundary surface between the liquid crystal layer and the film layer is flat, a reflective display device having a high interference reflection intensity and a bright white / black display appearance can be provided. Further, a multiple composite multilayer film in which a plurality of composite multilayer films having different interference pitches are stacked can be easily obtained by the above-described method.

(Fifth Embodiment) FIG. 6 shows a fifth embodiment in which characters of many colors such as black, red and blue are placed on a white background.
This is an example of displaying a figure or the like.

Reference numerals 61 and 62 each have a transparent electrode on the inner surface.
The lower substrate 63 is a composite multilayer film in which liquid crystal layers and film layers are alternately stacked as described above, and as described in the fourth embodiment, the combination of the thickness of the liquid crystal layer and the film is a composite multilayer film. 63 are set so as to satisfy the interference reflection condition with respect to the wavelength light in the entire visible light region. Further, the composite multilayer film 63 substantially satisfies the equations (1), (2), ((2) ', (3), and (4) described in the first embodiment. Although only seven layers including the liquid crystal layer and the film layer are shown due to restrictions, in order to perform sufficient interference reflection in the entire visible light wavelength range, a composite multilayer that reflects and reflects multiple wavelengths in the visible light region is required. Since a film is provided for each wavelength to be reflected and is laminated, the total number of layers including the liquid crystal layer and the film layer is at least 100.
It is preferable that the number of layers be equal to or more than the number of layers. Reference numerals 64, 65, and 66 denote light absorbing portions, each of which is formed of a light absorbing layer or a light absorbing plate having different colors of black, red, and green. The light reflection layers 68 may be formed below the black, red, and green filters 64, 65, and 66.
67 is a light scattering part. In this embodiment, in the no-voltage application region, the composite multilayer film 63 interference-reflects light in the visible light wavelength range, and exhibits substantially white W. On the other hand, in the voltage application region, the incident light is transmitted as it is, and the light absorbing portions (filter portions) 64, 6 having different color tones disposed below.
The wavelength bands absorbed at 5, 66, transmitted through this filter section, and reflected by the reflective layer 68 appear as different color indications (red light and green light are reflected in the figure). Since the black light absorbing portion 64 absorbs light transmitted through the multilayer film layer, black display is performed in this portion when a voltage is applied. Therefore, it is possible to display black, red, green, and the like on a white background on the same display surface to express figures / characters. Further, if the light absorbing portions 64, 65, and 66 are replaced with red, blue, and green light absorbing portions for each pixel, it is apparent that a full-color reflective display device can be obtained.

The light absorbing portions may be arranged on the inner surface of the lower substrate as red, blue and green color filters. In this case, the reflective layer may use the electrode of the lower substrate 62 as a reflective electrode, or the reflective layer may be arranged outside the lower substrate.

(Sixth Embodiment) FIG. 7 shows a sixth embodiment of the present invention. Reference numerals 71 and 72 denote upper and lower substrates having a transparent electrode on the inner surface, 74 denotes a light absorbing portion, and 73 denotes a light scattering portion. It is. 80,
Reference numeral 81 denotes a composite multilayer film in which a liquid crystal layer and a film layer are alternately laminated. As described above, the refractive index of each layer is set so as to satisfy the interference reflection condition in a desired wavelength range when no voltage is applied. And the film thickness are set. Reference numeral 77 denotes a film layer, which may have the same material and thickness as those of the films constituting the composite multilayer films 80 and 81, or different materials and thicknesses. The transparent electrode layer 7 is provided on the upper and lower surfaces of the film layer 77, respectively.
8, 79 are formed. Thus, since the upper and lower two composite multilayer films 80 and 81 can be separately applied with a voltage, the driving voltage can be reduced to about half. In the example described above, one film layer 77 having a transparent electrode layer is sandwiched between the intermediate portions.
Obviously, if a plurality of layers are interposed, the driving voltage can be further reduced, and display driving by a semiconductor IC driver having a low withstand voltage is also possible. In the figure, a configuration connected to electrodes 75 and 78,
The configuration connected to the electrodes 76 and 79 indicates a drive circuit (the same applies to the embodiments described later). The two driving circuits may separately drive the two composite multilayer films. If driven separately,
The reflection intensity can be controlled in two stages. Further, more composite multilayer films that are separately driven may be provided, and in this case, the reflection intensity becomes higher and gray scale display becomes possible. The configuration in which an intermediate film having an electrode is interposed between the composite multilayer films as in this embodiment can be combined with all the above-described embodiments.

As described above, in the present invention, since the film layer is used as one of the display functional materials, the electrode layer can be easily inserted into the intermediate portion, and low-voltage driving can be performed. As shown, a reflection type color display device can be easily realized.

(Seventh Embodiment) FIG. 8 shows a seventh embodiment according to the present invention, which is a specific example of a bright reflective color display device. Reference numerals 91 and 92 have transparent electrode films 108 and 109 on the upper and lower substrates facing each other. 93 is a black light absorbing portion, and 94 is a light scattering portion. A composite multilayer film 95 is composed of a composite multilayer film of a liquid crystal layer and a film layer as described above. The refractive index and the layer thickness of each of the liquid crystal layer and the film layer are set so as to selectively reflect and reflect red light when no voltage is applied and transmit when red voltage is applied, according to the method described above. In FIG. 8, the composite multilayer 9
5 is shown as having a three-layer structure, but in fact,
A composite multilayer film 95 having 10 or more layers is preferable for obtaining good interference reflection. Similarly, the composite multilayer films 96 and 97 each have a refractive index and a layer thickness of each of the liquid crystal layer and the film layer so that green and blue are selectively interference-reflected when no voltage is applied and are transmitted when a voltage is applied. Is set. 9
8, 99 are transparent electrodes 100, 101 and 1 on the upper and lower surfaces, respectively.
It is an intermediate film substrate having 02 and 103. In the present embodiment, as described above, the red light selective reflection layer 9
5. Green light selective reflection layer 96, blue light selective reflection layer 97
A multi-composite multi-layer film consisting of two composite multi-layer films is provided, and by applying intermediate film substrates 98 and 99 between the composite multi-layer films of each color, voltage is applied to each of the composite multi-layer films 95, 96 and 97 independently. And display control of red, green, and blue can be freely performed. As shown in FIG.
0, the red light selective reflection layer 95 and the green light selective reflection layer 9
No. 6, no voltage is applied, so that color light interferes and reflects with each other, and since a voltage is applied to the blue light selective reflection layer 97, blue light is transmitted as it is, and the black light absorbing portion 93 in the lower portion. Absorbed. Accordingly, the red and green lights are reflected, and the reflected light 106 is yellow. On the other hand, in the display region 111, a voltage is applied to both the red light selective reflection layer 95 and the green light selective reflection layer 96, and red and green light are transmitted therethrough, light is absorbed by the black light absorbing portion 93, and blue light selective reflection is performed. In the layer 97, blue light is interference-reflected without applying a voltage. Therefore, the display area 111 has a blue color.

As described above, in this embodiment, the red composite multilayer film 95 selectively reflects red light, the green composite multilayer film 96 selectively reflects green light, and the blue composite multilayer film 97 selectively reflects blue light. Are laminated, and the transparent electrode layers 98 and 99 are arranged with each composite multilayer film interposed therebetween, so that the light transmittance / reflectance can be controlled independently for each color. In the present embodiment, a white display is a case in which no voltage is applied to all of the three composite multilayer films 95, 96, and 97, and red, blue, and green light are all reflected and white display is performed. In the case of black display, 3
In this state, a voltage is applied to the two composite reflective films 95, 96, and 97. In this case, incident light is transmitted and absorbed by the light absorbing portion 93 to display black. Accordingly, a bright full-color reflective display device capable of freely expressing not only black on a white background but also red, blue, green or a mixed color thereof on a white background becomes possible. In the above-described example, the composite multilayer film corresponding to red, green, and blue is used, but of course, the combination of colors can be freely selected such as cyan, magenta, and yellow.

(Eighth Embodiment) FIG. 9 shows an eighth embodiment of the present invention.
Lower substrate, 113 is a black light absorbing portion, 114 is a light scattering portion,
Reference numeral 115 denotes a composite multilayer film having a structure in which a nematic liquid crystal layer 123 and a film layer 124 are alternately laminated.
Here, the liquid crystal layer 123 uses a liquid crystal layer in which the major axes of the liquid crystal molecules are aligned when no voltage is applied, and in which the molecular axes are aligned substantially horizontally with the surface of the film layer 124 (homogeneous alignment). As described above, the method of aligning the major axes of liquid crystal molecules and orienting the liquid crystal molecules horizontally to the substrate surface can be easily achieved by a combination of a polyimide resin and a rubbing process, which is a general method for manufacturing an existing liquid crystal display device. In the embodiment, if a film is formed by stretching the film layer 124 as described later, the liquid crystal molecules on the surface have a property that the long axes are aligned in the stretching direction, and the liquid crystal molecules can be aligned without special alignment treatment. A liquid crystal layer having a liquid crystal layer can be realized. In the nematic liquid crystal layer, the refractive index differs between the major axis direction and the minor axis direction of the liquid crystal molecules. Now, in the no-voltage application region 117, when the liquid crystal molecules are oriented so that the major axis is oriented parallel to the plane of the paper, the incident polarization component parallel to the plane of the paper and the incident polarization component perpendicular to the plane of the paper are different from each other. Have different refractive indices. In the present embodiment, the liquid crystal material and the film material are selected such that the refractive index (n _LC1 ) in the major axis direction of the liquid crystal molecules and the refractive index ((n _F ) of the film match. Is
Of the incident light 118, the polarized light component 119 parallel to the paper surface is transmitted through the composite multilayer film 115 and is absorbed by the lower black light absorbing portion 113. On the other hand, the refractive index of the liquid crystal layer 123 is n _LC2 (n _LC1 >
n _LC2 ), which is different from the refractive index (n _F ) of the film layer. Here, the thickness (d _F ) of the film layer and the thickness (d _LC ) of the liquid crystal layer are represented by n _F · d _F {(1/4 + k / 2) λ... (9) n _LC2 · d _LC } (1/4 + m / 2) λ (9) ′ (λ is the wavelength of incident light, k and m are 0 or an arbitrary integer) If (9) and (9) ′ are set to satisfy the equations, , The condition of interference reflection with respect to light having the wavelength λ is satisfied, and the reflected light 127 is reflected. On the other hand, in the voltage application region 116, the liquid crystal molecules of the liquid crystal layer 123 are oriented substantially perpendicular to the surface of the film layer 124, and the refractive index of the liquid crystal layer 124 as viewed from the incident light 125 is equal to all incident polarized light. (N _LC3 ) for the surface. From the general properties of the nematic liquid crystal, n _LC3 ≒ n _LC2 (10) holds, and according to the above equation (9), the incident light 12 of wavelength λ
5 are all reflected and become reflected lights 121 and 122.

The condition of interference reflection described above acts on light having a wavelength of λ, but as described above, a multiple composite multilayer in which a plurality of composite multilayers having different combinations of liquid crystal layer thickness and film layer thickness are stacked. If a film is used instead of the composite multilayer film 115,
A display device having a wide interference reflection wavelength width and a bright white background covering the entire visible light wavelength range can be realized.

(Ninth Embodiment) FIG. 10 shows a ninth embodiment of the present invention.
In the embodiment, 130 and 131 each have a transparent electrode on the inner surface, and a lower substrate. 132 is a black light absorbing portion, 135
Is a light scattering portion. A composite multilayer film 133 has a structure in which a nematic liquid crystal layer 143 having a positive dielectric anisotropy (hereinafter, simply referred to as a nematic liquid crystal layer in the present embodiment) 143 and a film 142 are alternately stacked. Reference numeral 134 denotes a composite multilayer film, which also has a laminated structure of a nematic liquid crystal layer 144 and a film 145.

In this embodiment, when no voltage is applied, the major axis direction of the liquid crystal molecules of the liquid crystal layer 143 is aligned with each film 1.
It is homogeneously oriented so as to be substantially horizontal to the surface 42 and substantially parallel to the paper surface. On the other hand, in the liquid crystal layer 144, also when no voltage is applied, the major axis direction of the liquid crystal molecules is substantially horizontal with respect to the surface of each film 145, but substantially vertical with respect to the paper surface. That is, the above 1
The liquid crystal layer 43 is homogenously aligned in a direction substantially perpendicular to the long axis of the liquid crystal molecules.

The nematic liquid crystal layer has birefringence. The refractive index for polarized light parallel to the major axis of the liquid crystal molecule is n _LC1 , and the refractive index for polarized light perpendicular to the major axis is n _LC1 .
_LC2 .

Further, the refractive indices of the films 142 and 145 are as follows:
The refractive index in the X-axis direction is n _F1 , and the refractive index in the Y-axis direction is n _F2 (n
_F1 ≧ _nF2 ). Here, the X-axis direction is made substantially coincident with the long-axis direction of the adjacent liquid crystal molecules having the homogeneous alignment. Therefore, if the refractive indices n _F1 and n _F2 of the film are set so that n _F2 ≒ n _LC2 (11) n _LC2 ≦ n _F1 <n _LC1 (11) ′, the incident light 141 is a composite multilayer. It passes through the membranes 133 and 134.

As described above, when voltage is applied, the liquid crystal molecules are not aligned perpendicular to the film surface in all of the liquid crystal layers.
Take an array that has horizontal direction components on the film surface. Accordingly, the average refractive index of the liquid crystal layer at this time does not become n _LC2, greater than n _LC2, a value smaller than n _LC1. Therefore, when the refractive index n _{F1 in} the X-axis direction of the film is equal to the average refractive index _<< n _LC2 >> in the X-axis direction when the voltage of the liquid crystal layer is applied to the incident light 141, the incident light 14
1 transmits the most strongly.

Next, as a reflection condition when no voltage is applied, n _LC1 · d _LC ≒ (１ ／ + m / 2) λ (12) n _F1 · d _F ≒ (１ ／ + k / 2) λ ··· (12) ′ (d _LC is the thickness of the liquid crystal layers 143 and 144, d _F is the thickness of the film layers 142 and 145, λ is the wavelength of the incident light 138 and 141, and k and m are 0 or an arbitrary integer) If the refractive indices and thicknesses of the liquid crystal layers 143 and 144 and the refractive indices and thicknesses of the film layers 142 and 145 are set so as to satisfy the expressions (11), (11) ′, (12) and (12) ′, According to the above description, as shown in FIG. 10, in the no-voltage application region 136, the incident light 138 having the wavelength λ reflects the polarization component parallel to the paper surface with the composite multilayer film 133 (the reflected light 13).
9) is done. Then, the polarized light component of the incident light 138 perpendicular to the paper surface passes through the composite multilayer film 133 to satisfy the expression (11) and reaches the composite multilayer film 134, where (12),
From equation (12) ′, the reflected light is reflected after receiving the interference reflection.
It will be 40. Therefore, all the incident light 138 having the wavelength λ is reflected in the no-voltage application region 136. Also as described above, if the number of layers of the composite multilayer films 133 and 134 is increased and a multiple composite multilayer film in which a plurality of composite multilayer films having different combinations of layer thicknesses are overlapped is formed, the wavelength range of reflected light is expanded. , White reflected light can be obtained.

On the other hand, in the voltage application region 137, since the liquid crystal molecules constituting the liquid crystal layers 143 and 144 are nematic liquid crystal materials having a positive dielectric anisotropy, the film 14
The major axes of the liquid crystal molecules are aligned substantially perpendicularly to the surfaces 2 and 145. Therefore, for all polarizations, (11), (1)
1) ′, the incident light 141 is transmitted through the composite multilayer films 133 and 134, and is absorbed by the lower black light absorbing portion 132. Of course, in order to increase the transmittance, it is important to match the refractive indices of the liquid crystal layer and the film layer so as to satisfy the expressions (11) and (11) ′ for all visible light wavelength regions. .

As described above, in this embodiment, almost perfect black display (white display is also possible on a black background) on a white background that scatters and reflects almost all the polarized light of incident light. Can be expressed, and a bright reflective display device, such as a black display on paper, can be realized.

The double composite multilayer film shown in the ninth embodiment, in which two composite multilayer films satisfying the interference reflection condition with respect to the two polarization axes perpendicular to and parallel to the paper surface, respectively, is described above. It can be easily understood that a display device with higher contrast can be realized by using each of the composite multilayer films shown in the first to seventh embodiments instead.

In FIG. 10, as in the sixth embodiment, a film 136 having upper and lower electrode layers 137 and 138 is inserted as an intermediate electrode layer between the composite multilayer films 133 and 134. However, this makes it possible to perform the display operation at a lower voltage.

Although the present invention has been described with reference to the nine embodiments, any film material may be used as long as it is substantially transparent and can be made thin. For example,
It can be selected from resins having various refractive indices, such as polyethylene naphthalate resin, polyester resin, polycarbonate resin, cellulose resin, and polyethersulfone resin. As described above, the liquid crystal material is a nematic liquid crystal,
Any substance can be used as long as the direction of the liquid crystal molecule axis can be changed by applying an electric field, such as a smectic liquid crystal, a polymer liquid crystal containing these liquid crystal molecules, or a mixture of these liquid crystals, thereby changing the refractive index of the liquid crystal layer. However, as mentioned above,
In particular, the discotic liquid crystal has a high interference reflection ability in a state of being oriented parallel to the layer surface, and is more preferable (the discotic liquid crystal may be mixed with the above-described liquid crystal).

Further, in the above-mentioned nine embodiments,
The liquid crystal molecules constituting the liquid crystal layer used in the above description have been described in terms of the displacement in the axial direction of approximately 90 ° with respect to the horizontal / vertical direction depending on whether or not a voltage is applied between the upper and lower substrates. The greater the absolute value of the refractive index difference depending on whether or not a voltage is applied to the liquid crystal layer, the higher the interference reflection ability and the higher the number of layers of the composite multilayer film, and the higher its display performance. However, in practice, a 90 ° molecular axis displacement due to the presence or absence of a voltage applied to the entire liquid crystal molecules is ideal, and depending on the applied voltage, it is presumed that the average displacement is 80 ° or less on average. Is done. However, the gist of the present invention is that if the refractive index of the liquid crystal layer constituting the composite multilayer film changes by applying a voltage, the number of layers of the composite multilayer film is increased even if the molecular axis displacement is 80 ° or less. It is clear that the display performance shown in each embodiment can be obtained because the interference reflected light intensity can be supplemented by the fact.

As described above, the display driving voltage can be obtained by inserting a plurality of substrates having electrodes in the middle of the composite multilayer film and applying a voltage to each of the divided composite multilayer films as a result. Although it is possible to drive the display at a lower voltage, as another method, giving the film layer some degree of conductivity is effective in achieving the purpose of driving the display at a lower voltage. Means.

That is, when a normal non-conductive film is used, the voltage (V) applied to the entire liquid crystal layer is almost as shown in the following equation (13).

V {ε _F / (ε _LC + ε _F )} · V ₀ (13) ε _F : dielectric constant of film ε _LC : dielectric constant of liquid crystal layer V ₀ : applied between upper and lower electrodes Applied voltage Usually, the dielectric constant (ε _LC ) of the liquid crystal layer is 10 to 15, and the dielectric constant of the film layer is 3 to 4. Thus the voltage applied across the liquid crystal layer (V) is, 0.2V ₀ becomes longitudinal, of V ₀ 1 /
It is reduced to around 5. Therefore, as described above, by giving some conductivity to the film layer, V ≒ V ₀
The voltage applied between the upper and lower electrodes is applied to the liquid crystal layer almost as it is. As a method for imparting conductivity to the film, the above effect can be realized by mixing a conductive plastic such as polyacetylene or polyparaphenylene into the film.

Although various embodiments of the present invention have been described above, it goes without saying that the contents described in each embodiment can be implemented in appropriate combinations in other embodiments. Next, a specific method of manufacturing the display device according to the above-described embodiment, particularly, a method of manufacturing the composite multilayer film will be described.

(Embodiment 10) FIG. 11 shows an embodiment of a method for manufacturing the above-mentioned composite multilayer film.
108. Reference numeral 1102 denotes a first roller which rotates in the direction of arrow 1109 and winds up the liquid crystal material 1101 in the rotation direction while uniformly coating the liquid crystal material 1101 on the first roller surface. Reference numeral 1103 denotes a second roller provided to keep the thickness of the coated liquid crystal layer constant, and is attached as necessary. Reference numeral 1105 denotes a plastic film (hereinafter, simply referred to as a film) as a material constituting the composite multilayer film, and includes a first roller 1102 and a third roller 1105.
At the contact point 104, the liquid crystal material 1101
5 is evenly applied. Control of the thickness of the liquid crystal layer
This is possible by adjusting the gap between the first roller 1102 and the third roller 1104. In addition, as a method of controlling the film thickness, precise control of the viscosity of the liquid crystal material is also possible. For this reason, precise control of the liquid crystal layer can also be performed by controlling the temperature of the liquid crystal layer or controlling the viscosity of the mixed system of the liquid crystal material and the solvent. The thickness can be controlled. Of course, in combination with a solvent system, a step of removing the solvent is required after coating the liquid crystal layer.

Next, in a similar manner, the film 1110 also coated with a liquid crystal layer on the surface and the film 110
5 is the fourth roller 1106 and the fifth roller 11
07 to form a composite four-layer film.
Obviously, by repeating the same, a composite multilayer film having 10 or more layers can be easily manufactured.

The above is an example of the basic manufacturing method.
Of course, in order to make the liquid crystal layer thickness uniform, and to avoid trapping air bubbles when laminating films together, further increase the number of rollers or heat with a uniform heat source to reduce the viscosity of the liquid crystal and apply and paste with rollers By taking such measures, a composite multilayer film more suitable for the purpose can be obtained, but it can be easily understood that the existing high-precision multilayer film manufacturing process can be referred to.

Further, in the above-described embodiment, each film constituting the composite multilayer film and each film thickness required for the liquid crystal layer are as follows:
Quarter of the visible light wavelength, that is, 0.1 μm to 0.2 μm
A very thin thickness of about m is required. For this purpose, FIG.
When coating the liquid crystal layer using a film with a thickness of 0.2 μm or less as shown in, the viscosity is lowered at a high temperature, or applied in a state of dissolving in a solvent to make it a low viscosity, and applying an ultra-thin liquid crystal layer. Although it is possible to obtain such a composite multilayer film, the method shown in FIG. 12 is more easily obtained.

(Eleventh Embodiment) FIG. 12 shows another embodiment of the method of manufacturing the above-mentioned composite multilayer film. Reference numeral 1201 denotes a relatively thick film (for example, a film, a single liquid crystal layer) formed by the method of FIG. The composite multilayer film having a thickness of 1 μm or more) is stretched by first-stage rolling rollers 1202 and 1203. The stretched composite multilayer film 1206 is further stretched by the second-stage rolling rollers 1204 and 1205. By performing the stretching process many times in this manner, the initial composite multilayer film 1201 gradually reduces the thickness of the liquid crystal layer and the film,
It is possible to easily obtain a desired thin layer. The composite multilayer film thus formed is cut into a predetermined size, sandwiched between the upper and lower substrates 1 and 2 together with a liquid crystal material as shown in FIG. 1, and the periphery is sealed with an epoxy adhesive or the like. FIG.
A display device having a composite multilayer film as shown in (1) is completed relatively easily.

In each of the embodiments of the present invention, a plastic film (hereinafter simply referred to as a film) coated with a liquid crystal layer is applied as a unit composite film of a composite multilayer film, and the unit composite film is formed by a roller having 10 or more layers. By superimposing them, the composite multilayer film can be realized very easily, and a reflective display device having a flat interface between the film and the liquid crystal layer and high interference reflected light intensity can be provided.

The thickness of the film can be freely selected, and the thickness of the liquid crystal layer can be relatively easily and accurately controlled by the roll coating method and the control of the liquid crystal viscosity by the temperature or the solvent at that time. The reflection wavelength range can be easily set. Further, the film layer, the composite multilayer film in which the thickness of the liquid crystal layer is controlled, it is easy to change the thickness of each layer, it is possible to satisfy the interference reflection conditions in a wide wavelength band, any arbitrary A bright reflective display device having a color and a white background color can be easily realized.

In order for the composite multilayer film to satisfy the interference reflection condition in the visible light wavelength region, each of the film and the liquid crystal layer must have an extremely thin film thickness of 0.2 μm or less.
As a manufacturing method, a relatively thick (1 μm or more) film is used, and a liquid crystal material is coated thereon by a roll coating method or the like, and then the film coated with the liquid crystal material is overlaid with a multilayer, a roller, etc., and compared. After forming a thick composite multilayer film, the composite multilayer film is stretched multiple times by a rolling roller, and a composite multilayer film having a desired thickness can be realized very easily, and precise film thickness control is possible. become. Furthermore, this stretching process has the effect of aligning the molecular axis direction of the film polymer and the alignment direction of the liquid crystal molecules of the liquid crystal layer coated on the film, and the refractive index having the uniform long axis of the liquid crystal molecules. Since a uniform liquid crystal layer can be obtained, the wavelength of interference reflected light can be precisely and easily controlled, and a uniform and bright reflective display device can be obtained. Of course, it is possible to orient the liquid crystal molecules in the desired direction even by applying a conventional rotating brush rubbing method in the conventional manufacturing of liquid crystal displays by applying an alignment material such as polyimide on the film in advance and drying. It is.

Further, since a film is used as one base material of the composite multilayer film, a transparent electrode can be easily formed on the film, and if a film having an electrode layer is inserted into an intermediate portion of the composite multilayer film. , Lower voltage driving becomes possible. Also, if the film having the electrode layer is sandwiched above and below the blocks of each composite multilayer film showing selective interference reflection such as red, green, and blue, and the above blocks are stacked and integrated,
Display driving can be performed independently of each other, and a reflection type full-color display device can be realized.

Next, the relationship between the number of stacked liquid crystal layers and films in the composite multilayer film and the reflectance will be described with reference to the following examples.

(Twelfth Embodiment) FIG. 13 shows an example of a composite multi-layered film that interferes and reflects the wavelength of incident light of 450 nm. FIG. 13A is a diagram schematically illustrating the lamination of the composite multilayer film.
FIG. 13B is a diagram showing the results of measuring the interference reflectance near 450 nm by changing the number of layers. Liquid crystal (refractive index n ₁ = 1.7 in the major axis direction of liquid crystal molecules, refractive index n ₂ = in the minor axis direction)
1.5), a polyethylene resin (refractive index n _F = 1.5) was laminated as a film between the substrates as shown in FIG. When no voltage was applied, the orientation of the liquid crystal molecules was substantially horizontal with respect to the substrate, and the number of liquid crystal layers whose orientation was set perpendicular to the paper surface and the number of liquid crystal layers whose parallel orientation was set were provided so as to be almost the same. The thicknesses of the liquid crystal layer and the film layer were set so as to satisfy the expressions (3) and (4) at a wavelength of 450 nm. In FIG. 13B, the horizontal axis represents the wavelength, and the vertical axis represents the reflectance. A indicates that the composite multilayer film including the liquid crystal layer and the film layer is 21 layers (the odd number means that the liquid crystal layer is disposed on both sides of the composite multilayer film). Is arranged, so that the number of liquid crystal layers is one more than the combination of the liquid crystal layer and the film.The number of the above-mentioned layers is a composite multilayer film having a liquid crystal layer oriented vertically to the paper surface and a horizontally oriented liquid crystal layer. , And the total number of layers is twice that of the composite multilayer film having the liquid crystal layer.
Represents 41 layers, C represents 61 layers, D represents 81 layers, and E represents 101 layers.
It shows the reflectivity for a layer. When no voltage is applied, the liquid crystal molecules of the liquid crystal layer are oriented in a direction parallel to the film surface, and the refractive index is n1 = 1.7, which is different from the film refractive index of 1.5. Interference reflected. As is apparent from the figure, it is preferable that the composite multilayer film has 21 layers or more, more preferably 41 layers or more, and further more preferably 61 layers or more.

(Thirteenth Embodiment) FIG.
This is an example in which composite multilayer films that interfere and reflect wavelengths of incident light of 550 nm, 650 nm, and 750 nm, respectively, are further laminated. FIG. 14A is a diagram schematically illustrating the lamination of the composite multilayer film corresponding to four wavelengths, and FIG. 14B is a diagram showing the result of measuring the interference reflectance near each wavelength by changing the number of laminations. It is. Liquid crystal (refractive index n ₁ = 1.7 in the major axis direction of liquid crystal molecules,
Using a refractive index n ₂ = 1.5 in the minor axis direction and a polyethylene resin (refractive index n _F = 1.5) as the film, FIG.
(A) As shown in FIG. When no voltage was applied, the orientation of the liquid crystal molecules was substantially horizontal with respect to the substrate, and the number of liquid crystal layers whose orientation was set perpendicular to the paper surface and the number of liquid crystal layers whose parallel orientation was set were provided so as to be almost the same. Also, 4
The composite multilayer film corresponding to one wavelength has a thickness of the liquid crystal layer and the film layer of 450 nm, 550 nm, 650 nm.
(3) for a wavelength of 750 nm and a wavelength of 750 nm, respectively.
It was set so as to satisfy the expression (4). In FIG. 14B, the horizontal axis represents wavelength, and the vertical axis represents reflectance. The four composite multilayer films corresponding to the respective wavelengths have a composite multilayer film including a liquid crystal layer whose orientation is set in a direction perpendicular to the paper and a composite multilayer film including a liquid crystal layer whose orientation is set in a horizontal direction, respectively. A in FIG.
E is a composite multilayer film including a liquid crystal layer whose orientation is set in a direction perpendicular to the plane of the drawing and a composite multilayer film including a liquid crystal layer whose orientation is also set in a horizontal direction. Indicates the number of layers. Therefore, the total number of layers is A ~
It is almost eight times the number of layers of E. A is a composite multilayer film composed of a total of a liquid crystal layer and a film layer that interference-reflects each wavelength in 21 layers (the odd number is because the liquid crystal layers are arranged on both sides of the composite multilayer film. In contrast, B represents 41 layers, C represents 61 layers, D represents 81 layers, and E represents reflectance in the case of 101 layers. When no voltage is applied, the liquid crystal molecules in the liquid crystal layer are oriented in a substantially horizontal direction, and the refractive index is n ₁ = 1.7, which is different from the refractive index of the film, 1.5. As is apparent from the figure, in each of the composite multilayer films that interfere and reflect each wavelength, a composite multilayer film including a liquid crystal layer whose orientation is set in the vertical direction to the paper surface and a composite multilayer film including a liquid crystal layer whose orientation is also set in the horizontal direction are used. The number of layers in each of the multilayer films is preferably 21 or more, more preferably 41 or more, and even 6 or more.
It is understood that more than one layer is more preferable.

(Fourteenth Embodiment) Next, the fourteenth to second embodiments will be described.
As one example, the refractive indices of the composite multilayer film and the liquid crystal layer and the relationship between the number of these layers and the reflectance were examined for display devices having various structures.

15A to 15C and FIGS. 16A and B
FIG. 15 is a diagram for explaining a general relationship between an applied voltage and an alignment state of liquid crystal molecules in the display devices according to the fourteenth to twenty-first embodiments, and FIG. 15A, FIG.
A and B represent 0.5 V, 1.0 V, 1.
5 schematically illustrates the alignment state of liquid crystal when 5 V, 2.0 V, and 2.5 V are applied. Fourteenth to twenty-first embodiments
In the embodiment of the present invention, it is assumed that the liquid crystal used for the liquid crystal layer is a nematic liquid crystal having a positive dielectric anisotropy, and the liquid crystal is horizontally aligned (homogeneous alignment) with respect to the film or substrate when no voltage is applied. A simulation of the reflectance of the display element was performed. In the display element having such a structure, as shown in FIGS. 15A to 15C and FIGS. 16A and 16B, as the applied voltage is increased, the liquid crystal gradually tilts. The inclination is not uniform, and the inclination is small near the film or the substrate, and large at the center of the cell. Accordingly, as shown in FIG. 17, the liquid crystal has a refractive index distribution in the cell in the thickness direction according to the applied voltage. In the fourteenth to twenty-first embodiments, the reflectance was simulated assuming that the liquid crystal layer had such a refractive index distribution. Note that the refractive index distribution in FIG. 17 is for a cell having a cell thickness of 0.1 μm.

FIG. 18 is a view for explaining the structure of the display device according to the fourteenth embodiment of the present invention.

In the display device according to the fourteenth embodiment, as shown in FIG.
Four composite multi-layer films for interference reflection of incident lights of m, 650 nm, and 750 nm are laminated.

A composite multilayer film that reflects and reflects light of each wavelength is as follows:
As shown in FIG. 18B, the composite multilayer film 2 for each P wave
00 and a composite multilayer film 300 for S wave. In the P-wave composite multilayer film 200, the film 201 and the liquid crystal layer 211 are alternately laminated. It was assumed to be horizontal and parallel to the paper. In the composite multilayer film 300 for S wave, the film 301 and the liquid crystal layer 311 are alternately laminated, and each liquid crystal layer 3
In No. 11, the orientation direction of the long axis of the liquid crystal molecules when no voltage was applied was substantially horizontal to the film 301 and perpendicular to the paper. In the composite multilayer film that interferes and reflects the light of each wavelength, the number of layers of the film 201 of the composite multilayer film 200 for the P wave and the liquid crystal layer 211 and the composite multilayer film 3 for the S wave
The number of layers of the liquid crystal layer 311 was the same as that of the liquid crystal layer 311. In addition, the film 201 of the composite multilayer film 200 for the P wave is also provided between the composite multilayer films that interfere and reflect light of each wavelength.
The number of layers of the liquid crystal layer 211 and the number of layers of the film 301 and the liquid crystal layer 311 of the composite multilayer film 200 for S wave were set to be the same. The structure of the composite multilayer film for interfering and reflecting light of each wavelength is the same in the fifteenth to twentieth embodiments.

In the fourteenth embodiment, the refractive index in the major axis direction of the liquid crystal molecules is n _LC1 = 1.7, the refractive index in the minor axis direction is n _LC2 = 1.5. The refractive index was n _F1 = 1.7, and the refractive index in the Y-axis direction was n _F2 = 1.5. (Here, the X-axis direction is the major axis direction of the liquid crystal molecules adjacent to the film, and the Y-axis direction is also the minor axis direction.) A composite multilayer film that interferes and reflects light of four wavelengths is a liquid crystal. The thickness of the layer and the film at a wavelength of 450 nm,
The wavelengths of 550 nm, 650 nm, and 750 nm were set to satisfy the equations (3) and (4), respectively.

The refractive index distribution in the thickness direction in the cell when a voltage is applied is as shown in FIG. 19A, and the reflectance of the display device is obtained by assuming that the liquid crystal layer has such a refractive index distribution.
FIGS. 19B and 20B show cases of applied voltages of 0.5 V, 1.0 V, 1.5 V, 2.0 V and 2.5 V, respectively.
A, FIG. 20B, FIG. 21A, and FIG. 21B.

In these figures, the horizontal axis represents wavelength, and the vertical axis represents reflectance. In each of these figures, the number of layers of each composite multilayer film that interferes and reflects light of each wavelength is 21 × 2.
(A), 41 × 2 (B), 61 × 2 (C), 81 × 2
The reflectance is obtained for each of (D) and 101 × 2 (E). Here, for example, in the case of A, 21 × 2 means that the number of layers of the composite multilayer film for the P wave is 21 and the composite multilayer film for the S wave is 21 in each composite multilayer film that interferes and reflects light of each wavelength. This shows that the number of layers of the composite multilayer film is 21. Therefore, in the case of A in this embodiment, the total number of layers is 2
1 × 2 × 4 = 168. The same applies to B, C, D, and E.

For example, in the case of A, the case where the number of layers of the composite multilayer film for P wave or S wave is 21 means that
It shows that the liquid crystal layer is 11 layers and the film is 10 layers for each of waves and S waves. Thus, the total number of the composite multilayer film including the liquid crystal layer and the film is 21 (odd number) because the liquid crystal layer is disposed at both ends of the composite multilayer film.
This is because the number of liquid crystal layers is one more than the combination of the liquid crystal layer and the film. The same applies to B, C, D, and E.

When no voltage is applied, the liquid crystal molecules of the liquid crystal layer are oriented substantially horizontally, and the refractive index (n
₁ ) and the refractive index (n _F1 ) of the film is n ₁ = n _F1 =
1.7, which is a transmission state. Similarly, also in the Y-axis direction, both the refractive index (n ₂ ) of the liquid crystal layer and the refractive index (n _F2 ) of the film are n ₂ = n _F2 = 1.5, which is a transmission state, and all incident light (P wave, S wave) Penetrates the composite multilayer film. As the voltage is applied, the refractive index becomes 1.7 as shown in FIG. 19A.
Therefore, light of each wavelength is selectively reflected by interference.

When the number of layers is increased, the reflectance increases. However, considering that the reflectance is about 70% for ordinary paper and about 80% for high-quality paper, light of each wavelength is reflected by interference. It can be seen that practically sufficient reflectance can be obtained if the number of layers of the P-wave or S-wave composite multilayer film is 21 in each of the composite multilayer films.

(Fifteenth Embodiment) FIG. 22 is a view for explaining the structure of a display device according to a fifteenth embodiment of the present invention. In the display device of the fifteenth embodiment, the wavelength 4
50 nm, 500 nm, 550 nm, 600 nm, 65
Seven composite multilayer films that interfere and reflect incident light of 0 nm, 700 nm, and 750 nm, respectively, are stacked. The structure of each of the seven composite multilayer films is similar to that of the fourteenth embodiment described with reference to FIG. 18B.

In this embodiment, the refractive index n _{1 in} the major axis direction of the liquid crystal molecules is 1.8, and the refractive index n _{2 in the} minor axis direction is 1.5.
2, the refractive index of the film is n _F1 = 1.8, n _F2 = 1.
52. In this case, the relationship between the orientation direction of the liquid crystal molecules and the arrangement of the film is the same as in the case of the fourteenth embodiment.
A composite multilayer film that interferes and reflects light of seven wavelengths,
The thickness of the liquid crystal layer and the film is set to a wavelength of 450 nm, 500 n
m wavelength, 550 nm wavelength, 600 nm, 650 nm
, 700 nm, and 750 nm, respectively, so as to satisfy the expressions (6) and (6) ′.

The refractive index distribution in the thickness direction in the cell when a voltage is applied is as shown in FIG. 23A, and the reflectance of the display device is obtained by assuming that the liquid crystal layer has such a refractive index distribution.
FIGS. 23B and 24 show cases where the applied voltage is 0.5 V, 1.0 V, 1.5 V, 2.0 V, and 2.5 V, respectively.
A, FIG. 24B, FIG. 25A, and FIG. 25B.

In these figures, the horizontal axis represents wavelength, and the vertical axis represents reflectance. In each of these figures, the number of layers of each composite multilayer film that reflects and reflects light of each wavelength is 11 × 2.
(F), 21 × 2 (A), 31 × 2 (G) and 41 ×
The reflectance is obtained for the case of 2 (B).
Here, the contents of the number of layers in each case are the same as in the case of the fourteenth embodiment.

When no voltage is applied, the liquid crystal molecules of the liquid crystal layer are oriented substantially horizontally, and the relationship between the refractive index (n ₁ , n ₂ ) of the liquid crystal layer and the refractive index (n _F1 , n _F2 ) of the film is , N ₁ = n _F1
= 1.8, n ₂ = n _F2 = 1.52, and there is no difference in the refractive index between the P wave and the S wave, so that the transmission state is achieved. As the voltage is applied, as shown in FIG. 23A, the refractive index becomes smaller than 1.8, so that each wavelength is selectively interference-reflected.

In this embodiment, the refractive index of the liquid crystal is 1.8 in the major axis direction and 1.52 in the minor axis direction, and the birefringence is higher than that of the fourteenth embodiment. High reflectivity is obtained. In each composite multilayer film that interferes and reflects light of each wavelength, even if the number of layers of the composite multilayer film for P wave or S wave is 11, a practically sufficient reflectance is obtained,
In the case of 21 layers, it can be seen that a reflectance of 80% or more, which is higher than that of high quality paper, is obtained.

(Sixteenth Embodiment) FIG. 26 is a view for explaining the structure of a display device according to a sixteenth embodiment of the present invention. In the display device of the sixteenth embodiment, the wavelength 4
00 nm, 450 nm, 500 nm, 550 nm, 60
0 nm, 650 nm, 700 nm, 750 nm, 800
Nine composite multilayer films each of which interference-reflects incident light of nm are laminated. The structure of each of the nine composite multilayer films is the same as that of the fourteenth embodiment described with reference to FIG. 18B.

In this embodiment, the refractive index n _{1 in} the major axis direction of the liquid crystal molecules is 1.8, and the refractive index n _{2 in the} minor axis direction is 1.5.
2, the refractive index of the film is n _F1 = 1.8, n _F2 = 1.
52. Here, the relationship between the arrangement direction of the liquid crystal molecules and the arrangement of the film is the same as in the case of the fourteenth embodiment. The composite multilayer film that interference-reflects light of nine wavelengths has a liquid crystal layer and a film thickness of 400 nm, a wavelength of 450 nm,
500 nm wavelength, 550 nm wavelength, 600 nm, 6
(3) and (4) for a wavelength of 50 nm, a wavelength of 700 nm, a wavelength of 750 nm, and a wavelength of 800 nm, respectively.
It was set to satisfy the formula.

The refractive index distribution in the thickness direction in the cell when a voltage is applied is as shown in FIG. 27A, and the reflectance of the display device is obtained by assuming that the liquid crystal layer has such a refractive index distribution.
FIGS. 27B and 28 show the cases where the applied voltages are 0.5 V, 1.0 V, 1.5 V, 2.0 V and 2.5 V, respectively.
A, FIG. 28B, FIG. 29A, and FIG. 29B.

In these figures, the horizontal axis represents the wavelength, and the vertical axis represents the reflectance. In each of these figures, the number of layers of each composite multilayer film that reflects and reflects light of each wavelength is 5 × 2.
(H), 11 × 2 (F), 15 × 2 (I) and 21 ×
The reflectance is obtained for the case of 2 (A).
Here, the contents of the number of layers in each case are the same as in the case of the fourteenth embodiment.

When no voltage is applied, the refractive index (n ₁ ,
n ₂ ) and the refractive index of the film (n _F1 , n _F2 ) are n
_{1 = n F1 = 1.8, n} 2 = n F2 = 1.52 next P-wave,
There is no difference in the refractive index between the S wave and the S wave, so that the S wave is in a transmission state. As the voltage is applied, the refractive index becomes 1.8 as shown in FIG. 27A.
, And each wavelength is selectively reflected by interference.

(Seventeenth Embodiment) FIG. 30 is a view for explaining the structure of a display device according to a seventeenth embodiment of the present invention. In the display device of the seventeenth embodiment, the wavelength 4
Four composite multi-layer films for interfering and reflecting incident light of 50 nm, 550 nm, 650 nm, and 750 nm are laminated. The structure of each of the four composite multilayer films is shown in FIG.
This is the same as the case of the fourteenth embodiment described with reference to FIG. 8B.

In this embodiment, the refractive index n ₁ = 1.8 in the major axis direction of the liquid crystal molecules and n ₂ = 1.5 in the minor axis direction.
2, the refractive index of the film is n _F1 = 1.8, n _F2 = 1.
52. In this case, the relationship between the orientation direction of the liquid crystal molecules and the arrangement of the film is the same as in the case of the fourteenth embodiment.
A composite multilayer film that reflects and reflects light of four wavelengths,
The thickness of the liquid crystal layer and the film is adjusted to a wavelength of 450 nm,
The wavelengths of m, 650 nm, and 750 nm were set to satisfy the equations (3) and (4), respectively.

The refractive index distribution in the thickness direction in the cell when a voltage is applied is as shown in FIG. 31A, and the reflectance of the display device is obtained by assuming that the liquid crystal layer has such a refractive index distribution.
FIGS. 31B and 32B show cases of applied voltages of 0.5 V, 1.0 V, 1.5 V, 2.0 V and 2.5 V, respectively.
A, FIG. 32B, FIG. 33A, and FIG. 33B.

In these figures, the horizontal axis represents wavelength, and the vertical axis represents reflectance. In each of these figures, the number of layers of each composite multilayer film that reflects and reflects light of each wavelength is 5 × 2.
(H), 11 × 2 (F), 15 × 2 (I) and 21 ×
The reflectance is obtained for the case of 2 (A).
Here, the contents of the number of layers in each case are the same as in the case of the fourteenth embodiment.

When no voltage is applied, the refractive index of the liquid crystal layer (n ₁ ,
n ₂ ) and the refractive index of the film (n _F1 , n _F2 )
n ₁ = n _F1 = 1.8, n ₂ = n _F2 = 1.52, and P
There is no difference in the refractive index between the wave and the S wave, so that the wave is in a transmission state. As the voltage is applied, as shown in FIG. 31A, the refractive index becomes smaller than 1.8, so that each wavelength is selectively interference-reflected.

(Eighteenth Embodiment) FIG. 34 is a view for explaining the structure of a display device according to the eighteenth embodiment of the present invention. In the display device of the eighteenth embodiment, the wavelength 4
50 nm, 500 nm, 550 nm, 600 nm, 65
Seven composite multilayer films that interfere and reflect incident light of 0 nm, 700 nm, and 750 nm, respectively, are stacked. The structure of each of the seven composite multilayer films is similar to that of the fourteenth embodiment described with reference to FIG. 18B.

In this embodiment, the refractive index n ₁ = 1.8 in the major axis direction of the liquid crystal molecules and n ₂ = 1.5 in the minor axis direction.
2, and the refractive index of the film was n _F1 = n _F2 = 1.52. The composite multilayer film that interference-reflects light of each of the seven wavelengths has a liquid crystal layer and a film thickness of 450 nm at a wavelength of 50 nm.
0 nm wavelength, 550 nm wavelength, 600 nm, 650
The wavelengths of nm, 700 nm, and 750 nm were set so as to satisfy Equations (3) and (4), respectively. There are many types of films having a refractive index of about 1.5 as in this embodiment, and for example, polyethylene, polyester, polycarbonate and the like are preferably used.

The refractive index distribution in the thickness direction in the cell when a voltage is applied is as shown in FIG. 35A, and the reflectance of the display device is obtained by assuming that the liquid crystal layer has such a refractive index distribution.
FIGS. 35B and 36 show the cases where the applied voltages are 0.5 V, 1.0 V, 1.5 V, 2.0 V and 2.5 V, respectively.
A, FIG. 36B, FIG. 37A, and FIG. 37B.

In these figures, the horizontal axis represents wavelength, and the vertical axis represents reflectance. In each of these figures, the number of layers of each composite multilayer film that reflects and reflects light of each wavelength is 11 × 2.
(F), 21 × 2 (A), 31 × 2 (G), 41 × 2
The reflectances are obtained for the cases of (B) and 51 × 2 (J). Here, the contents of the number of layers in each case are the same as in the case of the fourteenth embodiment.

When no voltage is applied, the liquid crystal molecules of the liquid crystal layer are oriented in a substantially horizontal direction, and the refractive index is n ₁ = 1.8. Interference reflected. As the voltage is applied, as shown in FIG. 35A, the refractive index becomes smaller than 1.8, so that the degree of interference reflection of each wavelength gradually decreases, and the transmittance increases. , Even if the voltage is applied to 2.0V and 2.5V,
The reflectance does not become zero. This is because, as shown in FIG. 35A, the refractive index of the liquid crystal when a voltage is applied is not equal to the refractive index of the liquid crystal in the minor axis direction.

(Nineteenth Embodiment) FIG. 38 is a view for explaining the structure of a display device according to a nineteenth embodiment of the present invention. In the display device of the nineteenth embodiment, the wavelength 4
50 nm, 500 nm, 550 nm, 600 nm, 65
Seven composite multilayer films that interfere and reflect incident light of 0 nm, 700 nm, and 750 nm, respectively, are stacked. The structure of each of the seven composite multilayer films is similar to that of the fourteenth embodiment described with reference to FIG. 18B.

In this embodiment, the refractive index n ₁ = 1.8 in the major axis direction of the liquid crystal molecules and n ₂ = 1.5 in the minor axis direction.
2, and the refractive index of the film was n _F1 = n _F2 = 1.58. The composite multilayer film that interference-reflects light of each of the seven wavelengths has a liquid crystal layer and a film thickness of 450 nm at a wavelength of 50 nm.
0 nm wavelength, 550 nm wavelength, 600 nm, 650
The wavelengths of nm, 700 nm, and 750 nm were set so as to satisfy Equations (3) and (4), respectively.

FIG. 39A shows the refractive index distribution in the thickness direction in the cell when a voltage is applied. The liquid crystal layer is determined to have such a refractive index distribution, and the reflectance of the display device is obtained.
FIGS. 39B and 40B show cases of applied voltages of 0.5 V, 1.0 V, 1.5 V, 2.0 V and 2.5 V, respectively.
A, FIG. 40B, FIG. 41A, and FIG. 42B.

In these figures, the horizontal axis represents the wavelength, and the vertical axis represents the reflectance. In each of these figures, the number of layers of each composite multilayer film that interferes with each wavelength is 11 × 2 (F),
The reflectance is obtained for the cases of 21 × 2 (A), 31 × 2 (G), 41 × 2 (B), and 51 × 2 (J). Here, the contents of the number of layers in each case are described in the first section.
This is the same as in the fourth embodiment.

When no voltage is applied, the liquid crystal molecules in the liquid crystal layer are oriented in a substantially horizontal direction, and the refractive index is n ₁ = 1.8. Interference reflected. As the voltage is applied, as shown in FIG. 39A, the refractive index becomes smaller than 1.8, so that the degree of interference reflection of each wavelength gradually decreases, and the transmittance increases. When a voltage of 2.5 V is applied, the reflectance becomes almost zero. As shown in FIG.
This is because when V is applied, the average refractive index of the liquid crystal layer becomes almost equal to the refractive index of the film, 1.58.

(Twentieth Embodiment) FIG. 42 is a view for explaining the structure of a display device according to a twentieth embodiment of the present invention. In the display device of the twentieth embodiment, the wavelength 4
50 nm, 500 nm, 550 nm, 600 nm, 65
Seven composite multilayer films that interfere and reflect incident light of 0 nm, 700 nm, and 750 nm, respectively, are stacked. The structure of each of the seven composite multilayer films is the same as that of the twentieth embodiment described with reference to FIG. 18B.

In the present embodiment, the refractive index n ₁ = 1.8 in the major axis direction of the liquid crystal molecules and the refractive index n ₂ = 1.5 in the minor axis direction.
2, and the refractive index of the film was n _F1 = n _F2 = 1.6. The composite multilayer film that interference-reflects light of each of the seven wavelengths has a liquid crystal layer and a film thickness of 450 nm at a wavelength of 50 nm.
0 nm wavelength, 550 nm wavelength, 600 nm, 650
The wavelengths of nm, 700 nm, and 750 nm were set to satisfy the equations (3) and (4), respectively.

FIG. 43A shows the refractive index distribution in the thickness direction in the cell when a voltage is applied. The reflectance of the display device is obtained by assuming that the liquid crystal layer has such a refractive index distribution.
FIGS. 43B and 44B show cases of applied voltages of 0.5 V, 1.0 V, 1.5 V, 2.0 V and 2.5 V, respectively.
A, FIG. 44B, FIG. 45A, and FIG. 45B.

In these figures, the horizontal axis represents wavelength, and the vertical axis represents reflectance. In each of these figures, the number of layers of each composite multilayer film that interferes and reflects each wavelength is 11 × 2.
(F), 21 × 2 (A), 31 × 2 (G), 41 × 2
The reflectances are obtained for the cases of (B) and 51 × 2 (J). Here, the contents of the number of layers in each case are the same as in the case of the fourteenth embodiment.

When no voltage is applied, the liquid crystal molecules of the liquid crystal layer are oriented in a substantially horizontal direction, and the refractive index is n ₁ = 1.8. Interference reflected. As the voltage is applied, as shown in FIG. 43A, the refractive index becomes smaller than 1.8, so that the degree of interference reflection at each wavelength gradually decreases, and the transmittance increases.
When the applied voltage is 2.0 V, the reflectance is almost 0. When the applied voltage is further increased to 2.5 V, the reflectance increases in reverse. As shown in FIG. 43A, when a voltage of 2.0 V is applied, the average refractive index of the liquid crystal layer becomes almost equal to 1.6 of the refractive index of the film, so that the reflectance becomes almost 0 and the voltage becomes 2 When a voltage of 0.5 V is applied, the average refractive index of the liquid crystal layer becomes smaller than the refractive index of the film, 1.6, and the reflectance increases. In this embodiment, since the refractive index of the film is closer to the refractive index in the major axis direction of the liquid crystal than in the case of the nineteenth example, the driving voltage can be reduced.

When the refractive index of the film is made substantially equal to the average refractive index of the liquid crystal determined by the applied voltage, the reflectance at the applied voltage can be reduced.

(Twenty-First Embodiment) FIG. 46 is a view for explaining the structure of a display device according to a twenty-first embodiment of the present invention. In the display device according to the twenty-first embodiment, a composite multilayer film composed of a liquid crystal layer and a film is subjected to interference reflection between adjacent liquid crystal layers and a film while substantially satisfying the equations (3) and (4). Wavelength from 450nm to 750
The display device was constructed by continuously changing the wavelength to nm. In addition,
The composite multilayer film that reflects and reflects light of each wavelength includes a composite multilayer film for P-wave and a composite multilayer film for S-wave, respectively.
In the liquid crystal layer of the composite multilayer film for waves, the orientation direction of the long axis of the liquid crystal molecules when no voltage is applied is almost horizontal to the film and parallel to the paper surface. In the liquid crystal layer, the alignment direction of the major axis of the liquid crystal molecules when no voltage was applied was almost horizontal to the film and perpendicular to the paper. In the composite multilayer film that reflects and reflects light of each wavelength, the number of layers of the P multilayer composite film and the liquid crystal layer and the number of the S multilayer composite film and the liquid crystal layer are the same. did.

[0141] In this embodiment, the refractive index n ₁ of the long axis direction of liquid crystal molecules, the minor axis direction of the refractive index n _2, respectively, n ₁
/ N ₂ = 1.6 / 1.5, 1.55 / 1.4, 1.7 /
1.5, 1.15 / 1.3, and the reflectance distribution of each display device when a voltage is applied is shown in FIGS. 47A, 47B, and 48.
A and 48B respectively. Each of the films uses a birefringent film. The refractive index in the X-axis direction is equal to the refractive index in the long-axis direction of adjacent liquid crystal molecules.
The refractive index in the axial direction is also set to be equal to the refractive index in the minor axis direction of adjacent liquid crystal molecules. In these figures, the horizontal axis represents wavelength, and the vertical axis represents reflectance. In each of these figures, the total number of liquid crystal layers and films in the composite multilayer film that reflects and reflects light from 450 nm to 750 nm is 51 × 2 (a), 101 × 2 (b), and 1 × 2, respectively.
51 × 2 (c), 201 × 2 (d), 251 × 2
(E), 301 × 2 (f), 351 × 2 (g), 401
× 2 (h), 451 × 2 (i) and 501 × 2 (j)
In each case, the reflectance is determined. Here, for example, in the case of a, 51 × 2 means that the number of layers of the composite multilayer film for P wave is 51 and the number of layers of the composite multilayer film for S wave is 5
1 is shown. Therefore, in the case of the present embodiment, the total number of layers is 51 × 2 = 102. The same applies to the cases of b to j.

Birefringence of liquid crystal (= refractive index in long axis direction (n ₁ , n _CL1 ) / refractive index in short axis direction (n ₂ , n
_The greater the _CL2 )) and the greater the number of layers, the higher the reflectance.

FIG. 49 shows the relationship between the total number of layers and the reflectance using the birefringence as a parameter. According to this, when the birefringence is 1.1 or more and the total number of layers is 100 or more, a reflectance higher than that of the conventional TN liquid crystal can be obtained.

In the fourteenth through twenty-first embodiments, the simulation was performed on the assumption that the liquid crystal was horizontally oriented (homogeneous orientation) with respect to the film or substrate when no voltage was applied. The principle is the same even in a structure in which the liquid crystal is oriented almost perpendicularly to the film or the substrate (homeotropic alignment) when added. However, in this case, when the refractive index of the film is close to the refractive index in the long axis direction of the liquid crystal, light is reflected when no voltage is applied, and light is transmitted when a voltage is applied. When the refractive index is close to the above, light transmission occurs when no voltage is applied and light reflection occurs when a voltage is applied.

[0145]

As described above, in the display device according to the present invention, a bright display device can be obtained without using a polarizing plate. In particular, a reflection-type display device can be obtained with a conventional liquid crystal display device. There was no bright white / black display,
A bright reflective color display device is made possible. It is also possible to superimpose liquid crystal-coated film layers in a multi-layer manner, and to further stretch the film layers, whereby a composite multi-layer film having a desired thickness can be easily formed, and the above-mentioned bright reflective display can be relatively easily formed. A device is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a first embodiment of a display device according to the present invention.

FIG. 2 is a diagram for explaining a display principle according to the present invention.

FIG. 3 is a diagram for explaining a second embodiment of the display device according to the present invention.

FIG. 4 is a diagram for explaining a third embodiment of the display device according to the present invention.

FIG. 5 is a diagram for explaining a fourth embodiment of the display device according to the present invention.

FIG. 6 is a diagram for explaining a fifth embodiment of the display device according to the present invention.

FIG. 7 is a diagram for explaining a sixth embodiment of the display device according to the present invention.

FIG. 8 is a diagram for explaining a seventh embodiment of the display device according to the present invention.

FIG. 9 is a diagram for explaining an eighth embodiment of the display device according to the present invention.

FIG. 10 is a view for explaining a ninth embodiment of the display device according to the present invention.

FIG. 11 is a diagram for explaining a method of manufacturing a composite multilayer film used for the display device according to the present invention.

FIG. 12 is a diagram for explaining another method for manufacturing a composite multilayer film used for the display device according to the present invention.

FIG. 13 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the fourteenth embodiment of the display device according to the present invention.

FIG. 14 is a diagram for explaining the relationship between the number of layers of a composite multilayer film and interference reflectance in a fifteenth embodiment of the display device according to the present invention.

FIG. 15 is a diagram for explaining a relationship between an applied voltage and an alignment state of liquid crystal molecules in the fourteenth embodiment to the twenty-first embodiment of the display device according to the present invention.

FIG. 16 is a diagram for explaining the relationship between the applied voltage and the alignment state of the liquid crystal molecules in the fourteenth to twenty-first embodiments of the display device according to the present invention.

FIG. 17 is a diagram for explaining the relationship between the cell thickness direction and the refractive index of the liquid crystal in the fourteenth to twenty-first embodiments of the display device according to the present invention, using an applied voltage as a parameter.

FIG. 18 is a diagram for explaining a structure of a display device according to a fourteenth embodiment of the present invention.

FIG. 19 is a diagram for explaining a display device according to a fourteenth embodiment of the present invention. FIG. 19A shows the relationship between the cell thickness direction and the refractive index of the liquid crystal in the display device according to the fourteenth embodiment. FIG. 1 is a diagram for explaining voltage as a parameter, and FIG.
FIG. 9B is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device of the fourteenth embodiment.

FIG. 20 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the fourteenth embodiment of the present invention.

FIG. 21 is a diagram for explaining the relationship between the number of layers of a composite multilayer film and interference reflectance in a display device according to a fourteenth embodiment of the present invention.

FIG. 22 is a diagram for explaining a structure of a display device according to a fifteenth embodiment of the present invention.

FIG. 23 is a view for explaining a display device according to a fifteenth embodiment of the present invention. FIG. 23A shows the relationship between the cell thickness direction and the refractive index of the liquid crystal in the display device according to the fifteenth embodiment. FIG. 2 is a diagram for explaining voltage as a parameter, and FIG.
FIG. 3B is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device of the fifteenth embodiment.

FIG. 24 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the fifteenth embodiment of the present invention.

FIG. 25 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the fifteenth embodiment of the present invention.

FIG. 26 is a view for explaining a structure of a display device according to a sixteenth embodiment of the present invention.

FIG. 27 is a diagram for explaining a display device according to a sixteenth embodiment of the present invention. FIG. 27A shows the relationship between the cell thickness direction and the refractive index of liquid crystal in the display device according to the sixteenth embodiment. FIG. 2 is a diagram for explaining voltage as a parameter, and FIG.
FIG. 7B is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device of the sixteenth embodiment.

FIG. 28 is a diagram for explaining the relationship between the number of layers of a composite multilayer film and interference reflectance in a display device according to a sixteenth embodiment of the present invention.

FIG. 29 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the sixteenth embodiment of the present invention.

FIG. 30 is a view illustrating a structure of a display device according to a seventeenth embodiment of the present invention.

FIG. 31 is a view for explaining a display device according to a seventeenth embodiment of the present invention. FIG. 31A shows the relationship between the cell thickness direction and the refractive index of the liquid crystal in the display device according to the seventeenth embodiment. FIG. 3 is a diagram for explaining voltage as a parameter, and FIG.
FIG. 1B is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device of the seventeenth embodiment.

FIG. 32 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the seventeenth embodiment of the present invention.

FIG. 33 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the seventeenth embodiment of the present invention.

FIG. 34 is a view for explaining the structure of the display device according to the eighteenth embodiment of the present invention.

FIG. 35 is a view for explaining a display device according to an eighteenth embodiment of the present invention. FIG. 35A shows the relationship between the cell thickness direction and the refractive index of liquid crystal in the display device according to the eighteenth embodiment. FIG. 3 is a diagram for explaining voltage as a parameter, and FIG.
FIG. 5B is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device of the eighteenth embodiment.

FIG. 36 is a view for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the eighteenth embodiment of the present invention.

FIG. 37 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the eighteenth embodiment of the present invention.

FIG. 38 is a view for explaining the structure of the display device according to the nineteenth embodiment of the present invention.

FIG. 39 is a view for explaining a display device according to a nineteenth embodiment of the present invention. FIG. 39A shows the relationship between the cell thickness direction and the refractive index of the liquid crystal in the display device according to the nineteenth embodiment. FIG. 3 is a diagram for explaining voltage as a parameter, and FIG.
FIG. 9B is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device of the nineteenth embodiment.

FIG. 40 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the nineteenth embodiment of the present invention.

FIG. 41 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the nineteenth embodiment of the present invention.

FIG. 42 is a view for explaining the structure of the display device according to the nineteenth embodiment of the present invention;

FIG. 43 is a view for explaining a display device according to a twentieth embodiment of the present invention. FIG. 43A shows the relationship between the cell thickness direction and the refractive index of the liquid crystal in the display device according to the twentieth embodiment. FIG. 4 is a diagram for explaining voltage as a parameter, and FIG.
FIG. 3B is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the twentieth embodiment.

FIG. 44 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the twentieth embodiment of the present invention.

FIG. 45 is a view for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the twentieth embodiment of the present invention.

FIG. 46 is a view illustrating a structure of a display device according to a twenty-first embodiment of the present invention.

FIG. 47 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the twenty-first embodiment of the present invention.

FIG. 48 is a diagram for explaining the relationship between the number of layers of the composite multilayer film and the interference reflectance in the display device according to the twenty-first embodiment of the present invention.

FIG. 49 is a diagram for explaining the relationship between the total number of composite multilayer films and interference reflectance in the display device according to the twenty-first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper substrate 2 Lower substrate 5, 6, 7 Plastic film 8, 9, 10, 11 Liquid crystal layer 13 No-voltage application area 14 Voltage application area 15, 16 Incident light 17 Interference reflected light

Claims (25)

[Claims] 1. A composite multilayer film in which a film and a liquid crystal layer are alternately laminated a plurality of times between a pair of substrates, and a voltage is applied to the composite multilayer film to control light reflectance in the composite multilayer film. A display device characterized by the above-mentioned. 2. The display device according to claim 1, wherein a light scattering means is arranged outside one of the substrates, and a light absorbing means is provided outside the other substrate. 3. The liquid crystal layer according to claim 1, wherein the liquid crystal layer is made of a nematic liquid crystal, a smectic liquid crystal, a nematic liquid crystal, a nematic polymer liquid crystal, a smectic polymer liquid crystal, or a mixture thereof. Display device. 4. The display device according to claim 1, wherein the liquid crystal layer is made of a discotic liquid crystal or a mixture of a discotic liquid crystal and a nematic liquid crystal. 5. The liquid crystal layer according to claim 1, wherein the liquid crystal layer is composed of nematic liquid crystal molecules, and a major axis of the liquid crystal molecules is arranged substantially horizontally with respect to the substrate or the film when no voltage is applied. 3. The display device according to 1 or 2. 6. The liquid crystal layer according to claim 1, wherein the liquid crystal layer is composed of nematic liquid crystal molecules, and a major axis of the liquid crystal molecules is arranged substantially perpendicular to the substrate or the film when no voltage is applied. 3. The display device according to 1 or 2. 7. The display device according to claim 2, wherein the light absorbing means absorbs light in an arbitrary wavelength band or a wavelength band in a visible light region that passes through the composite multilayer film. 8. An intermediate substrate having a composite multilayer film in which a film and a liquid crystal layer are alternately laminated a plurality of times between a pair of substrates having electrodes on the inner surface, and an intermediate substrate having electrodes on both surfaces in an intermediate portion of the composite multilayer film. A light scattering means outside one of the substrates and a light absorbing means outside the other substrate. 9. The layer thickness of the liquid crystal layer and the film is set such that the composite multilayer film reflects light of at least a part of the wavelength of the incident visible light region when no voltage is applied. The display device according to any one of claims 1 to 8, wherein 10. The layer thickness of the liquid crystal layer and the film is set such that, when a voltage is applied, the composite multilayer film reflects light of at least a part of the wavelength of an incident visible light region. The display device according to any one of claims 1 to 8, wherein 11. The liquid crystal layer according to claim 1, wherein at least one of the refractive indices in the major axis and minor axis directions of the liquid crystal molecules in the liquid crystal layer substantially coincides with the refractive index of the film. The display device according to any one of the above. 12. A plurality of composite multilayer films, wherein the thickness of the film and the thickness of the liquid crystal layer are equal to each other and the thickness of the liquid crystal layer and the thickness of the film are different between different composite multilayer films. 12. The display device according to claim 9, wherein the composite multilayer film is laminated to reflect a plurality of wavelengths of incident light. 13. A plurality of composite multi-layer films each having the same layer thickness of the film and the liquid crystal layer, and having different layer thicknesses of the liquid crystal layer and the film between different composite multi-layer films. The thicknesses of the liquid crystal layer and the film are set such that the composite multilayer films are stacked, and the plurality of composite multilayer films reflect red light, green light, and blue light. Item 9, 10 or 1
The display device according to 1. 14. An electrode for applying a voltage independently for each of said composite multilayer films.
3. The display device according to 3. 15. A composite liquid crystal layer comprising nematic liquid crystal molecules, wherein the liquid crystal layer is configured to reflect light having a polarization component substantially in the major axis direction of the nematic liquid crystal molecules or in a direction substantially orthogonal to the major axis direction. The display device according to claim 1, wherein the display device includes at least a multilayer film. 16. The display device according to claim 15, wherein the film is an optically substantially uniaxial film or a stretched film. 17. The composite multilayer film is divided into two blocks, and a liquid crystal molecule long axis direction of a first block liquid crystal layer and a liquid crystal molecule long axis direction of a second block liquid crystal layer are substantially orthogonal to each other, 17. The display device according to claim 15, further comprising at least a composite multilayer film in which the first and second blocks are stacked. 18. An electrode for applying a voltage independently to the first and second blocks is arranged.
7. The display device according to 7. 19. The display device according to claim 1, wherein a material of the liquid crystal layer is applied to at least one surface of the film, and the film on which the liquid crystal material is applied is a multi-layer roller. A method for manufacturing a display device, wherein the composite multilayer film is formed by superimposing and integrating with each other. 20. The display device according to claim 19, wherein the liquid crystal layer is integrated while being heated to a predetermined temperature to reduce the viscosity of the liquid crystal layer when overlapping with the roller. Production method. 21. The display device according to claim 19, wherein the film is preliminarily subjected to a uniaxial stretching treatment to have an alignment function for aligning liquid crystal molecules. 22. The display device according to claim 1, wherein a material of the liquid crystal layer is applied on the film surface, and the film on which the liquid crystal material is applied is overlapped with a plurality of layer rollers. After being integrated, further subjected to a stretching treatment with a rolling roller, the thickness of the film and the thickness of the liquid crystal layer, by adjusting the thickness to a predetermined value, the composite multilayer film was formed by the display device characterized by the above-mentioned Production method. 23. The display device according to claim 1, wherein the film has conductivity. 24. The display device according to claim 1, wherein the composite multilayer film is configured by laminating at least ten layers of the liquid crystal layer and the film. 25. The display device according to claim 1, wherein the composite multilayer film is formed by laminating at least 21 layers of the liquid crystal layer and the film.