JPH08304848A - Reflective color liquid crystal display - Google Patents

Abstract

(57) [Summary] [Structure] A third display element 3 that reflects blue light, a second display element 2 that reflects green light, and a first display element 1 that reflects red light are stacked in order from the light incident side. ing. Each of the display elements 1 to 3 has a multilayer film 6 (6a, 6b, 6c) in which a plurality of liquid crystal layers 4 (4a, 4b, 4c) and polymer material layers 5 (5a, 5b, 65) are laminated. , And a transparent conductive film 8 (8a, 8b ... 8f) is formed via a base film 7, and is sandwiched between a pair of plastic substrates 9 and 9. The multilayer film 6 switches the refractive index of the liquid crystal forming the liquid crystal layer 4 between a reflective state and a transmissive state when a voltage is applied. [Effect] A reflective color liquid crystal display device using a plastic substrate that is lightweight, thin, and has a small parallax, and a reflectance ratio of blue light is as large as that of red light and green light, and a good color balance is achieved. Can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective color liquid crystal display device having a structure in which a plurality of display elements using a plastic substrate are laminated.

[0002]

2. Description of the Related Art FIG. 4 shows a configuration of a conventional reflective color liquid crystal display device disclosed in Japanese Patent Laid-Open No. 4-178624. In this conventional reflective color liquid crystal display device, the first display element 51 and the second display element 5 are provided.
A total of three display elements including the second display element 53 and the third display element 53 are stacked. These first to third display elements 51 to 53
Has a structure in which a multilayer film 56 in which a plurality of liquid crystal layers 54 and polymer material layers 55 are laminated in layers is sandwiched by a glass substrate 59 on which a transparent conductive film 58 is formed via a base film 57.

The above-mentioned first display element 51 and second display element 5
2, the second display element 52 and the third display element 53 are formed by forming the transparent conductive films 58 on both surfaces of the glass substrate 59 so that one glass substrate 59 is shared by the two display elements. . Therefore, the total number of glass substrates 59 used in this reflective color liquid crystal display device is four.

Further, each of the first to third display elements 51
Of the glass substrate 5 of the first display element 51, which is the rearmost from the light incident side, the glass substrate 5 on the opposite side of the light incident side.
9 is a black film 6 between the transparent conductive film 58 and the base film 57.
0 is provided.

The refractive index of the liquid crystal forming the liquid crystal layer 54 in the multilayer film 56 is adapted to change depending on the applied voltage. As a result, when the liquid crystal layer 54 and the polymer material layer 55 have different refractive indexes, the multilayer film 56 functions as an interference filter and reflects light of a specific wavelength according to the thickness of the liquid crystal layer 54. On the other hand, the liquid crystal layer 54 and the polymer material layer 55
Most of the light is transmitted when the refractive indices of the two are substantially equal.

When the respective multilayer films 56 are in the reflective state, the first display element 51 reflects blue light with high reflectance, and the second display element 52 reflects green light with high reflectance. As reflective, the third display elements 52 are each designed to reflect red light with high reflectance. Thereby, in the reflective color liquid crystal display device,
Various colors are developed by the additive color mixture. For example, when all the multilayer films 56 of the first to third display elements 51 to 53 are in the reflective state, most of the incident visible light is reflected and white is displayed. On the other hand, the first to third display elements 51 to 5
When all the multilayer films 56 of No. 3 are in the transmissive state, the transmitted light is absorbed by the black film 60 in the first display element 51,
The black color will be displayed.

However, in the case of such a reflection type color liquid crystal display device, even though the glass substrate 59 is intended to be used in common, it is constructed by stacking four thick and heavy glass substrates 59 in four layers. However, there is a problem that the thickness of the mold color liquid crystal display device itself is increased to make it lighter and thinner. Further, when the thickness increases, there is a problem that parallax occurs due to the thickness and the display quality deteriorates.

Therefore, in order to solve these problems, in the reflection type color liquid crystal display device having the above-mentioned structure, instead of the glass substrate 59, it is lighter than the glass substrate and strong in impact resistance. Plastic substrates, which can be processed thinner than glass substrates, have come into wide use.

[0009]

The plastic substrate is lighter than the glass substrate and can be processed thinner than the glass substrate, but has a lower melting temperature than glass because of its physical properties. Therefore, when the transparent conductive film is formed on the plastic substrate, the transparent conductive film cannot be formed at a high temperature as in the case where the transparent conductive film is formed on the glass substrate. Due to this, the transparent conductive film formed on the plastic substrate is colored yellow.

As shown in FIG. 2, the plastic substrate having such a yellow-colored transparent conductive film has a visible light transmittance different from that of the plastic substrate having no transparent conductive film. That is, the light on the short wavelength side of the visible light region mainly in the vicinity of 500 nm is absorbed by the yellow transparent conductive film, and the transmittance is lower than the transmittance of visible light on the longer wavelength side than the vicinity of 550 nm. Become.

Therefore, in a reflection type color liquid crystal display device using a plastic substrate, a display element which reflects other light is arranged on the light incident side of the display element which reflects light in a wavelength band mainly around 500 nm. , This 5
By the time the film reaches the multilayer film that reflects light in the wavelength band mainly around 00 nm, the transparent conductive film of the display element arranged in front of this absorbs light in the wavelength band mainly around 500 nm. The intensity of this light component becomes weak.

Further, since the reflected light is transmitted through the same number of transparent conductive films as when the light is emitted, the reflected light in the wavelength band mainly around 500 nm is emitted. Also weakens.

For example, in the case of the reflection type color liquid crystal display device shown in FIG. 4 described above, the multilayer film 56 of the first display element 51 which reflects blue which is a display element which reflects light in a wavelength band mainly around 500 nm. By the time the incident light reaches, the blue light component of the incident light will be reflected after passing through a total of five transparent conductive films 58. Further, the blue light reflected by the multilayer film 56 of the first display element 51 includes a total of five transparent conductive films 58.
Will be emitted to the outside of the display device. As a result, in the display device having such a configuration, when a plastic substrate is used instead of the glass substrate 59, the reflectance of blue light is lower than that of red light or green light, the intensity of blue is small, and the color balance is low. There is a problem that it becomes worse.

The present invention has been made to solve the above-mentioned problems, and is a light-weight and thin reflective color liquid crystal display device using a plastic substrate having a small parallax.
An object of the present invention is to provide a reflective color liquid crystal display device in which the reflectance of light in a wavelength band mainly near 0 nm is as large as that of light in wavelengths in other visible light regions and which has a good color balance.

[0015]

In order to solve the above problems, in a reflective color liquid crystal display device according to claim 1 of the present invention, a film which can be switched between a transmissive state and a reflective state depending on a voltage application state. In a reflective color liquid crystal display device in which a plurality of display elements, each of which is sandwiched by a plastic substrate having a transparent conductive layer formed on the surface thereof and reflects light in different wavelength bands, are stacked. Is 5
It is characterized in that the display elements having a high reflectance of light in the wavelength band mainly around 00 nm are laminated so as to be closest to the light incident side.

Further, in the reflection type color liquid crystal display device according to a second aspect of the present invention, in the structure of the first aspect, the light having high reflectance is blue, green and red.
It is characterized in that it is provided with a display element of a kind and these display elements are laminated so that the display element having a high blue reflectance is located on the light incident side most.

[0017]

According to the structure of the above-mentioned claim 1, among the plurality of display elements, the display element having a high reflectance of light in the wavelength band mainly in the vicinity of 500 nm in the visible light region is located on the light incident side most. It is stacked. According to this stacking order, 500
Since the transparent conductive film that transmits incident light is only one layer until reaching a film that can switch between a transmissive state and a reflective state in a display element that reflects light in a wavelength band mainly in the vicinity of 500 nm, a wavelength of around 500 nm A display element that reflects light in a wavelength band mainly in the vicinity of 500 nm as compared with a case where a display element having a high reflectance in a wavelength band mainly in The film reaches the film that can be switched between the transmissive state and the reflective state, and the intensity of the light component reflected here increases.

According to the above construction, the reflected 50
Since the transparent conductive film through which light in the wavelength band mainly in the vicinity of 0 nm passes through until it is emitted from this display device is also one layer, the light in the wavelength band in the vicinity of 500 nm mainly emitted from the display device is The strength also increases.

Moreover, since a plastic substrate is used, it has the advantages of being lightweight and thin and having a small parallax.

According to the structure of claim 2, three layers of display elements having high reflectance of blue, red and green are laminated, and the display element having high reflectance of blue light is provided on the light incident side. A reflective color liquid crystal display device including three layers of display elements having high reflectance for blue, red and green,
The display element that most reflects light in the wavelength band mainly in the vicinity of nm is a display element that reflects blue light.
With the configuration arranged second or rearward from the light incident side, the intensity of the blue light component reaching the blue-reflecting film becomes stronger and the intensity of the blue reflected light reflected from the light incident side also becomes greater. As a result, the reflectance of blue light is not inferior to that of red light or green light, and it is possible to perform display with good color balance in which the light intensities of blue, red, and green are almost equal.

[0021]

【Example】

[Embodiment 1] The following will describe one embodiment of the present invention with reference to FIGS. 1 and 2.

As shown in FIG. 1, the reflective color liquid crystal display device according to the present embodiment is formed by laminating three display elements 1 to 3 which respectively reflect light of different wavelength bands. The stacking order is the third, second, and first order from the light incident direction.

Each of the first to third display elements 1 to 3 has a liquid crystal layer 4 (4a, 4b, 4c) and a polymer material layer 5 respectively.
(5a, 5b, 5c) and a multilayer film 6 (6
a.6b.6c) and the transparent conductive film 8 via the base film 7.
.. 8f is sandwiched between a pair of plastic substrates 9 and 9.

The first display element 1 and the second display element 2, and the second display element 2 and the third display element 3 are formed with transparent conductive films 8 on both surfaces of a plastic substrate 9, respectively.
One plastic substrate 9 is shared by two display elements. Therefore, the total number of plastic substrates 9 used in this reflective color liquid crystal display device is four.

Further, these first to third display elements 1 to 3 are
Of the first display element 1, which is the rearmost from the light incident side, on the plastic substrate 9 on the side opposite to the light incident side, a black film is formed between the transparent conductive film 8a and the base film 7. A black film 10 made of a pigment or a dye is provided.

The multilayer film 6 is adapted to change the refractive index of the liquid crystal forming the liquid crystal layer 4 depending on the voltage applied state. In this embodiment, when a voltage is applied to the liquid crystal layer 4, the refractive index is set to be equal to that of the polymer material layer 5.

As a result, no voltage is applied to the liquid crystal layer 4,
When the liquid crystal layer 4 and the polymer material layer 5 have different refractive indices,
When it acts as an interference filter and reflects light of a specific wavelength according to the thickness of the liquid crystal layer 4, while a voltage is applied to the liquid crystal layer 4 and the refractive indices of the liquid crystal layer 4 and the polymer material layer 5 are substantially the same. Most of the light is transmitted through.

Of the multilayer films 6, the thickness d of the liquid crystal layer 4a of the multilayer film 6a of the first display element 1 arranged at the rearmost side from the light incident side is the liquid crystal layer 4a and the polymer material layer 5a. When the liquid crystal is oriented (acts as an interference filter) so as to have different refractive indices, it is defined by the generally known formula (1) below so as to reflect red light.

D = (2N + 1) · λ / 4n (N = 0, 1, 2, ...) (1) d: Thickness of liquid crystal layer λ: Wavelength of reflected light n: Refractive index In addition, The second arranged between the display elements 1 and 3
The thickness d of the liquid crystal layer 4b of the multi-layered film 6b of the display element 2 is set so as to reflect green light when the liquid crystal is oriented so that the liquid crystal layer 4b and the polymer material layer 5b have different refractive indices. It is defined by the above equation (1).

The thickness d of the liquid crystal layer 4c of the multilayer film 6c of the third display element 3 arranged closest to the light incident side is equal to the liquid crystal layer 4c.
It is defined by the above formula (1) so as to reflect blue light when the liquid crystal is oriented so that the refractive index of c is different from that of the polymer material layer 5c.

As the plastic substrate 9, for example, a cross-linked acrylic substrate is used, and the heat resistant temperature thereof is 160 ° C. in this embodiment. Plastic substrate 9
Since it is stronger in impact resistance than a glass substrate and can be processed thinly, it is possible to improve the display quality by making the reflective color liquid crystal display device lightweight and thin and reducing parallax.

As the base film 7, for example, SiO ₂
A film is used, and in this embodiment, the plastic substrate 9 is heated to about 100 ° C., and SiO _{2 is} deposited by vapor deposition or sputtering.
A film has been deposited. As the transparent conductive film 8, for example, I
A TO (Indium Tin Oxcide) film is used, and in this embodiment, the plastic substrate 9 on which the base film 7 is formed is
The ITO film is formed by heating to 00 to 130 ° C. and vapor deposition or sputtering.

The liquid crystal layer 4 and the polymer material layer 5 constituting the multilayer film 6 are, for example, ZLI-50 manufactured by Merck & Co., Inc.
38-000, a photo-curable polymer material (for example, Light Rack LA0208) is used. The multi-layered film 6 is formed by injecting a mixture of the liquid crystal material to be the liquid crystal layer 4 and the photo-curable polymer material to be the polymer material layer 5 into a space between the pair of plastic substrates 9 and 9. It is formed by irradiating a laser beam from. By irradiating the mixture with laser light, the photo-curable polymer material is cured into the polymer material layer 5 in the portion where the laser light in the mixture strengthens due to interference, and most of the liquid crystal material is present in other portions. Remains to form the liquid crystal layer 4, and a multi-layer structure of the liquid crystal layer 4 and the polymer material layer 5 is obtained. Refractive index (n) of the liquid crystal layer 4 in the present embodiment in the absence of applied voltage
Is 1.6435, and the refractive index (n) of the polymer material layer 5 in the state where no voltage is applied is 1.5.

Next, driving in the reflection type color liquid crystal display device having the above structure will be described.

First, only the first display element 1 is turned off, that is, a pair of transparent conductive films 8a provided on the first display element 1.
The second display element 2 and the third display element 3 are turned on without applying a voltage to 8b, that is, the pair of transparent conductive films 8c and 8d provided on the second display element 2 and the third display element 3 are turned on. A voltage is applied to the pair of transparent conductive films 8e and 8f provided.
By controlling the driving of each of the first to third display elements 1 to 3 in this manner, incident light is emitted from the third display element 3 and the second display element 2.
And red light is reflected by the first display element 1, and the other light is absorbed by the black film 10 of the first display element 1. As a result, red is displayed on the reflective color liquid crystal display device (which may be simply referred to as a display device).

When only the second display element 2 is turned off and the first and third display elements 1 and 3 are turned on, the incident light becomes
Green light is transmitted through the third display element 3 and reflected by the second display element 2, and other light is transmitted through the first display element 2 and absorbed by the black film 10. As a result, green is displayed on the display device.

When only the third display element 3 is turned off and the first and second display elements 1 and 2 are turned on, the incident light becomes
Blue light is reflected by the third display element 3, and other light is sequentially transmitted through the second display element 2 and the first display element 1 and absorbed by the black film 10. As a result, a blue color is displayed on the display device.

Further, only the third display element 3 is turned on, and the first display element 3 is turned on.
When the second display elements 1 and 2 are turned off, the incident light becomes
The green light is transmitted through the third display element 3, the green light is reflected by the second display element 2, the red light is reflected by the first display element 1, and the other light is absorbed by the black film 10. As a result, yellow color is displayed on the display device (state shown in FIG. 1).

Further, only the second display element 2 is turned on, and the first display element 2 is turned on.
And when the third display elements 1 and 3 are turned off, the incident light becomes
Blue light is reflected by the third display element 3, other light is transmitted through the second display element 2, red light is reflected by the first display element 1, and other light is absorbed by the black film 10. It As a result, magenta is displayed on the display device.

Further, only the first display element 1 is turned on, and the second display element 1 is turned on.
When the third display elements 2 and 3 are turned off, the incident light becomes
Blue light is reflected by the third display element 3 and the second display element 2
The green light is reflected at and the other light passes through the first display element 1 and is absorbed by the black film 10. As a result, cyan is displayed on the display device.

When all the first to third display elements 1 to 3 are turned off, incident light is blue light at the third display element 3, green light at the second display element 2, and 1 display element 1
At, each red light is reflected. That is, the first to the third
Most of visible light is reflected by the display elements 1 to 3, and as a result, white color is displayed on the display device.

When all of the first to third display elements 1 to 3 are turned on, the incident light passes through the third display element 3, the second display element 2 and the first display element 1 all. Most of visible light is transmitted through the first to third display elements 1 to 3, and the transmitted light is absorbed by the black film 10 of the first display element 1.
As a result, black is displayed on the display device.

By the way, as in the reflective color liquid crystal display device of this embodiment, the transparent conductive film 8 provided on the plastic substrate 9 absorbs visible light, as shown in FIG. In particular, since it absorbs light in the wavelength band mainly around 500 nm, the transmittance of light with a wavelength near 500 nm is about 90% in the plastic substrate 9 on which the transparent conductive film 8 is not formed. In the plastic substrate 9 on which the transparent conductive film 8 is formed, it is reduced to about 70%.

Therefore, if the display element that most reflects the light in the wavelength band mainly around 500 nm, that is, the third display element 3 that most reflects the blue light in the display apparatus of this embodiment, is shown in FIG. When the blue light component is arranged at the position of the first display element 1 in, the blue light component in the incident light becomes the first and second until the blue light is reflected by the third display element 3.
In total, four layers of transparent conductive films 8a and 8a of the display elements 1 and 2 of FIG.
While being transmitted through b, 8c, 8d and one layer of the transparent conductive film 8f of the first display element 1 itself, it is absorbed in five stages,
The transmittance is reduced.

Further, in such a configuration, the first
The blue light reflected by the display device 1 again has five layers of the transparent conductive film 8 similar to the above before being emitted from the display device.
Is transmitted from the opposite side, and during this time, the light is absorbed again in five steps and the transmittance is reduced.

As a result, of the light emitted from the display device, the intensity of blue light is lower than that of other red and green light,
This causes problems such as poor color balance.

On the other hand, in the reflection type color liquid crystal display device of this embodiment, as described above, the third type which reflects blue light is used.
The display device 3 is arranged closest to the light incident side. Therefore, the incident light only passes through the transparent conductive film 8f of the third display device 3 until it is reflected by the multilayer film 6c of the third display device 3, so that the wavelength band mainly around 500 nm thereof. The rate of decrease of the light is about 70% of the light reaching the surface of the display device, but the transmittance of the light is lower than that of the case where light is incident through the transparent conductive film 8 of 5 layers or 3 layers. The drop is much smaller. Further, since the reflected blue light also passes through only one layer of the transparent conductive film 8f, the absorption of the light here is far more than that when it is emitted through the five or three layers of the transparent conductive film 8. Will be suppressed to.

Therefore, in the reflection type color liquid crystal display device of this embodiment, the display quality can be improved by reducing the weight and thickness and reducing the parallax, and at the same time, the decrease in the intensity of the blue light can be suppressed and the blue light can be suppressed. It is possible to perform display with good color balance in which the intensities of red light and green light are almost equal.

In this embodiment, the photocurable polymer material is used as the material of the polymer material layer 5, but a thermosetting polymer material (eg epoxy resin) may be used.
In that case, in a mixture of thermosetting polymer material and liquid crystal,
When the laser light is radiated and the portions where the laser lights strengthen each other due to interference are at a higher temperature than the non-interference portion, the thermosetting polymer material cures and the layer of thermosetting polymer material, that is, the polymer material layer It becomes 5. In addition, an alignment film may be provided between the transparent conductive film 8 and the multilayer film 6.

[Embodiment 2] Another embodiment of the present invention will be described with reference to FIG.
The explanation is based on the following. For convenience of explanation, members having the same functions as the members shown in the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 3, the reflective color liquid crystal display device according to the present embodiment is a multilayer film 6 (6a, 6b) in which a plurality of liquid crystal layers 4 and polymer material layers 5 of the first embodiment are laminated.・
6c), a cholesteric liquid crystal is used as a film that can be switched between a transmissive state and a reflective state depending on a voltage applied state, and the cholesteric liquid crystal layer 11 (11a, 11b, 1) is used.
The first to third display elements 1 to 3 having 1c) are laminated in three layers. The other plastic substrates 9, the base film 7, the transparent conductive film 8, the black film 10 and the like are the same as those in the above embodiment.

Here, the liquid crystal pitch P of the cholesteric liquid crystal layer 11a of the first display element 1 is P = λ / n (2) P: Pitch λ: Wavelength n = [(n _o ² + n _e ² ). 1/2] ^1/2 n _o: ordinary refractive index o n _e: calculated in extraordinary refractive index, is designed to reflect red light.

The liquid crystal pitch P of the cholesteric liquid crystal layer 11b of the second display element 2 is determined by the above equation (2) and is designed to reflect green light.

Cholesteric liquid crystal layer 1 of the third display element 3.
The liquid crystal pitch P of 1c is obtained by the above equation (2) and is designed to reflect blue light.

As the cholesteric liquid crystal forming the cholesteric liquid crystal layer 11, a cholesteric liquid crystal having a positive dielectric constant is used in this embodiment. Therefore, the cholesteric liquid crystal layer 11 reflects light in the wavelength band obtained from the above mathematical expression (2) when no voltage is applied, and transmits light when voltage is applied.

In the reflection type color liquid crystal display device having the above structure, when no voltage is applied, the cholesteric liquid crystal layer 11a of each of the first to third display elements 1 to 3 is formed.
11b and 11c represent light according to the design, that is, red light in the cholesteric liquid crystal layer 11a in the first display element 1, green light in the cholesteric liquid crystal layer 11b in the second display element 2, and light in the third display element 3. Cholesteric liquid crystal layer 1
At 1c, blue light is reflected respectively.

Therefore, as shown in FIG. 3, for example, only the third display element 3 is turned off, and the second display element 2 and the first display element 3 are turned off.
When the display element 1 is turned on, blue light is reflected from the third display element 3 as incident light, and other light is transmitted through the second display element 2 and the third display element 3, respectively, and the black film 10 is emitted. Be absorbed. As a result, the display device displays blue (state of FIG. 3).

Since the other color displays are the same as those in the above-mentioned embodiment, the description thereof will be omitted here.

Also in this embodiment, similarly to the first embodiment, the third display element 3 which reflects blue light is arranged on the most light incident side. Therefore, until the blue light component of the incident light is reflected by the third display element 3, the incident light is
Since it only transmits through the transparent conductive film 8f of the third display element 3, the reduction rate of the light in the wavelength band mainly around 500 nm is about 70% as compared with the light reaching the surface of the display device. However, as in the case where the third display element 3 is arranged at the position of the first display element 1 in the figure, for example, the light is incident through the five layers of transparent conductive films 8 (8a, 8b, 8c, 8d, 8f). However, the decrease in the transmittance can be suppressed to a much smaller level. Further, since the reflected blue light also passes through only one layer of the transparent conductive film 8f, the absorption of the blue light here is also different from the case of being emitted through the five layers of the transparent conductive film 8 as described above. , Will be significantly reduced.

Therefore, in the reflection type color liquid crystal display device of the present embodiment, the display quality can be improved by making the device lighter and thinner and reducing the parallax, and the decrease in the intensity of the blue light can be suppressed, and the blue light can be suppressed. It is possible to perform display with good color balance in which the intensities of red light and green light are almost equal.

Here, the cholesteric liquid crystal layer 11 (11a, 11b, 11c) using cholesteric liquid crystal is used.
However, instead of this, a chiral agent (for example, S81 manufactured by Merck & Co., Inc.) is used to obtain a predetermined pitch in the nematic liquid crystal.
You may use what added 1).

In this embodiment, the cholesteric liquid crystal having a positive dielectric constant is used, but the liquid crystal may be either positive or negative. However, when a negative one is used, the cholesteric liquid crystal layer 11 reflects light in the wavelength band obtained from the equation (2) when a voltage is applied and transmits light when no voltage is applied.

[0063]

As described above, in the reflective color liquid crystal display device according to claim 1 of the present invention, a film capable of switching between a transmissive state and a reflective state depending on the state of voltage application and a transparent conductive layer on the surface are provided. Display elements that are sandwiched between the formed plastic substrates and that reflect light in different wavelength bands,
In the reflective color liquid crystal display device in which a plurality of layers are stacked, among the plurality of display elements, a display element having a high reflectance of light in a wavelength band mainly around 500 nm is stacked so as to be closest to the light incident side. It is a composition.

Further, in the reflection type color liquid crystal display device according to the second aspect of the present invention, in the structure of the first aspect, the light having high reflectance is blue, green and red.
The display element is provided with some kinds of display elements, and these display elements are laminated such that the display element having a high blue reflectance is located on the light incident side most.

As a result, by using a plastic substrate, in a reflection type color liquid crystal display device which is light and thin and has a small parallax, the reflectance of short wavelength light mainly in the vicinity of 500 nm of the visible light region is high, but the light is high. However, the amount absorbed by the transparent conductive film provided on the plastic substrate can be minimized, and the intensity of light in the wavelength band mainly around 500 nm is not inferior to that in other visible light regions. It is possible to realize a large reflective color liquid crystal display device.

In particular, when three layers of a display element having a high reflectance for blue, a display element having a high reflectance for red, and a display element having a high reflectance for green are laminated in three layers, the blue light is different from the other red light and the green light. As a result, the reflective color liquid crystal display device having a large color strength and a good color balance can be realized.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of the present invention and showing a schematic configuration of a reflective color liquid crystal display device.

FIG. 2 is a graph showing a visible transmission spectrum of a plastic substrate and a plastic having a transparent conductive film formed on the surface thereof.

FIG. 3 shows another embodiment of the present invention and is a schematic cross-sectional view showing a schematic configuration of a reflective color liquid crystal display device.

FIG. 4 is a schematic sectional view showing a schematic configuration of a conventional reflective color liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st display element 2 2nd display element 3 3rd display element 4 Liquid crystal layer 5 Polymer material layer 6 Multilayer film (film which can be switched between a transmission state and a reflection state) 7 Underlayer film 8 Transparent conductive film 9 Plastic substrate 10 Black film 11 Cholesteric liquid crystal layer (film capable of switching between transmissive state and reflective state)

Claims (2)

[Claims] 1. Reflecting light of different wavelength bands, which is formed by sandwiching a film capable of switching between a transmission state and a reflection state depending on a voltage applied state between plastic substrates having a transparent conductive layer formed on the surface thereof. In a reflective color liquid crystal display device in which a plurality of display elements are stacked, in the plurality of display elements, a display element having a high reflectance of light in a wavelength band mainly in the vicinity of 500 nm is the light incident side most. A reflective color liquid crystal display device characterized by being laminated. 2. A display element having three types of blue, green, and red light, each of which has a high reflectance, is provided, and the display element having a high reflectance of blue is the light incident side. The reflective color liquid crystal display device according to claim 1, wherein the reflective color liquid crystal display device is laminated so as to have the following structure.