JPH0882799A - Liquid crystal element - Google Patents

Abstract

PURPOSE: To provide a liquid crystal element which is bright in a liquid crystal display surface and is high in the contrast of the brightness between on and off by alternately disposing liquid crystals varying in orientation directions without using diffraction gratings. CONSTITUTION: A pair of transparent substrates 12a, 12b facing each other are provided thereon with oriented films 14a, 14b and are arranged apart a spacing T to form a pair. Further, liquid crystals 15 having an ordinary refractive index n0 and extraordinary refractive index ne are encapsulated between a pair of the oriented films 14a and 14b and are arranged alternately with first regions 16a and second regions 16b where the orientation directions of the liquid crystal molecules 15a in the liquid crystals 15 are both parallel with the surfaces of the oriented films 14a, 14b and intersect orthogonally with each other. Further, the liquid crystal element is constituted in such a manner that the relation (ne -n0 )T=λ(2m+1)/2 (m=integer) holds between the spacing T between the oriented films 14a, 14b and the ordinary refractive index n0 and extraordinary refractive index ne of the liquid crystals 15 and the wavelength λof light 17 or the light 17 having a distribution around the wavelength λ.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal element, and more particularly to a liquid crystal element which controls transmission and blocking of light by diffracting light.

A liquid crystal element diffracts incident light in an incident direction or in a direction other than the incident direction to control the light.
It is used for optical display or the like, and usually has a configuration in which liquid crystal is sealed by a sealing member that has been subjected to an alignment treatment.

In the past, a structure was used in which a transparent substrate having a pair of transparent electrodes was used as an encapsulating member, the opposite inner surfaces of the transparent substrate were subjected to an orientation treatment, and this was sandwiched by polarizing plates. However, since the use efficiency of light is poor and the liquid crystal display becomes dark when two polarizing plates are used, various liquid crystal elements that do not use polarizing plates have been studied.

[0004]

2. Description of the Related Art A liquid crystal element using a diffraction grating has been developed as a liquid crystal element which has been developed in order to improve light utilization efficiency and obtain a brighter liquid crystal display.

The structure of a liquid crystal element using this diffraction grating will be described below.

FIGS. 8 (a) and 8 (b) show application publication information,
It is a schematic block diagram of the liquid crystal element which is the prior art example of this invention described in Japanese Unexamined Patent Publication No. 5-15247. FIG. 8A shows the transparent electrodes 3a and 3a of the first transparent substrate 2a and the second transparent substrate 2b.
FIG. 8B shows a state where no voltage is applied to b, and FIG. 8B shows a state where voltage is applied.

In FIG. 8, reference numeral 1 denotes a liquid crystal element using a diffraction grating, and transparent substrates 2a and 2b provided with transparent electrodes 3a and 3b are arranged to face each other with a space therebetween, and the transparent substrate 2a,
A diffraction grating 6 having a refractive index _ng and a thickness T between 2b,
The liquid crystal 5 is enclosed. The hatched diffraction grating 6 is made of a substance having optical isotropy, and a liquid crystal 5 is enclosed between the transparent electrodes 3 a and 3 b and the diffraction grating 6. The alignment direction of the liquid crystal molecules 5a of the liquid crystal 5 is shown in the figure.

Further, light 7 having a wavelength λ which is vertically incident on the transparent substrates 2a and 2b of the liquid crystal element 1 is shown. Light 7
Actually, the entire area of the transparent substrate 3b is irradiated from the direction shown, but only one point is shown for convenience of explanation.

The natural light 7 can be considered by dividing it into polarized light components orthogonal to each other.

Now, the polarized component of the light 7 parallel to the paper surface is
a, and the polarized component in the direction perpendicular to the paper surface is 7b.

The liquid crystal molecules 5a are evenly present in the liquid crystal 5, and are perpendicular to the polarization component 7a and parallel to 7b when no voltage is applied to the liquid crystal element 1 shown in FIG. 8 (a). It shall be oriented. The polarization component 7a in the direction perpendicular to the liquid crystal molecules 5a enters the liquid crystal 5 and behaves according to the ordinary refractive index n ₀ of the liquid crystal. On the other hand, the polarized light component 7b in the direction parallel to the liquid crystal molecules 5a behaves in the liquid crystal 5 according to the extraordinary refractive index n _e of the liquid crystal 5.

When the intensity of incident light is I _O and the intensity of light diffracted by the liquid crystal 5 and extracted in the same direction as the incident light is I, I / I _O is called diffraction efficiency. .

The diffraction efficiency is approximately represented by the following equation (1).

I / I _O ≈ {1 + cos (2πΔnT / λ)} / 2 (1) In the formula (1), T is the thickness of the diffraction grating 6, λ is the wavelength of incident light, or incident light The wavelength is the center of the wavelength distribution.

Δn is the refractive index n _{g of the} substance forming the diffraction grating 6.
And the difference in the refractive index that the polarization component incident on the liquid crystal 5 follows. Therefore, Δn in the polarization component 7a is ( _ng −n
_0), in the polarization component 7b has a different value as (n _g -n _e).

FIG. 8B shows a state in which a voltage is applied between the transparent electrodes 3a and 3b.

The liquid crystal molecules 5a are uniformly oriented in the direction perpendicular to the transparent substrate surface, and at this time, both the polarization components 7a and 7b of the light 7 incident on the liquid crystal 5 have a normal refractive index n _{0 of the} liquid crystal 5. Feel By solving the equation (1), the minimum value of I / I _O value 0
It can be seen that the condition that has is ΔnT = λ (2m + 1) / 2 (2) (m is an integer). When the condition (2) is satisfied, the polarization components 7a, 7 of the light 7 incident on the liquid crystal 5 are
b is transmitted in directions other than the incident direction. Such diffraction is called high-order diffraction. On the other hand, the condition that I / I _O has the maximum value of 1 is Δn = 0 ... (3) from the equation (1). When the condition (3) is satisfied, the polarization components 7a and 7b, which are high-order diffracted lights, become 0, and the light incident on the liquid crystal 5 travels straight in the incident direction. Such diffraction is called zero-order diffraction.

The liquid crystal element 1 utilizes such characteristics of the liquid crystal 5 to perform control such that light incident on the liquid crystal 5 is diffracted in the same direction as the incident direction or diffracted in a direction other than the incident direction. Since the display is performed, the liquid crystal element 1 is required to have characteristics such as a bright display image and a large image contrast when the liquid crystal element 1 is turned on and off.

Brightness of the displayed image means that the absolute amount of I, which is the intensity of light transmitted through the liquid crystal element 1, is large.

Further, ON, and I / I _O value in magnitude ON state of the contrast of the image at OFF, since a value determined by the ratio of the value of I / I _O in the OFF state, the ON state The polarization components 7a and 7b of the incident light are all subjected to the 0th order diffraction that is extracted in the direction of straight advance, and the light that enters the liquid crystal element 1 in the OFF state is all diffracted in a direction other than the incident direction. Is desirable.

In order to satisfy the above conditions in the liquid crystal element 1, the ordinary refractive index n ₀ and the extraordinary refractive index n _e of the liquid crystal 5, the refractive index n _{g of the} members constituting the diffraction grating, the thickness T of the diffraction grating, Condition 1 and Condition 2 described below between the wavelengths λ of the light 7
The liquid crystal element 1 is designed so that any of the above is established and liquid crystal display is performed.

Condition (1) (n _e −n _g ) T = λ / 2 ... (1.1) and Δn = n _g −n ₀ = 0. (1.2) or condition _{(2) (n g -n 0} ) T = λ / 2 ········ (2.1) and _{Δn = n g -n e = 0} ···· .. (2.2) The behaviors of the polarization components 7a and 7b satisfying either the condition (1) or the condition (2) are summarized in FIG.

In FIG. 9, I / I _O = 1 means zero-order diffraction, that is, all incident light is transmitted in the direction of straight travel, and I / I _O = 0 means higher-order diffraction, that is, incident light. It is shown that all of are diffracted in directions other than the incident direction.

In the case of the liquid crystal element 1 satisfying the condition (1), it can be seen that the polarization component 7a is diffracted in the 0th order regardless of the voltage application to the transparent electrodes 3a and 3b. Although the polarization component 7b exhibits the characteristic that can be controlled by applying a voltage, that is, the 0th order diffraction is performed only when a voltage is applied to the transparent electrodes 3a and 3b, and the higher order diffraction is performed when a voltage is not applied,
In the OFF state of the liquid crystal element 1, the polarization component 7a that is diffracted in the 0th order makes the liquid crystal display surface bright, and the contrast with the brightness in the ON state becomes poor.

Next, each polarization component 7 under the condition (2)
As for the behaviors of a and 7b, it can be seen from FIG. 9 that the polarization component 7a is diffracted in higher orders regardless of the application of the voltage to the transparent electrodes 3a and 3b. Polarization component 7b is transparent electrode 3a, 3b
The voltage is not applied to the transparent electrodes 3a and 3b by exhibiting a characteristic that can be controlled by applying a voltage, that is, high-order diffraction is performed only when a voltage is applied, and 0-order diffraction is applied when a voltage is not applied. The state of the liquid crystal element 1 is O
If N and the state applied to the transparent electrodes 3a and 3b are set to OFF, the brightness of the ON state, that is, the brightness of the display surface during liquid crystal display is halved.

A structure for solving the above problem in the liquid crystal element 1 using the diffraction grating 6 is shown in FIGS. 10 (a) and 10 (b).
Shown in

In both FIGS. 10A and 10B, the first liquid crystal element 1a and the second liquid crystal element 1b are prepared and paired, and they are arranged at right angles to each other. Figure 10 (a)
In the example shown in, the first liquid crystal element 1a and the second liquid crystal element 1 are
In FIG. 10B, the transparent substrate 2b of the first liquid crystal element 1a and the transparent substrate 2a of the second liquid crystal element 1b are connected to each other by bonding to each other. The second liquid crystal element 1b is characterized by eliminating the transparent substrate disposed inside.

[0028]

However, in any case, the process of laminating the liquid crystal element 1 is complicated. Further, in the liquid crystal element 1 having such a configuration, the processing accuracy of the diffraction grating 6 is important, and it is usually desirable that the grating pitch is 10 μm or less and the thickness of the diffraction grating is 1 μm or more. It is difficult to accurately form 6 on the transparent substrate.

In view of the above points, it is an object of the present invention to provide a liquid crystal element having a performance equivalent to that of a laminated diffraction grating by a simple process that does not use the diffraction grating.

[0030]

In order to solve the above problems, the present invention has the following configuration.

The liquid crystal device according to the invention of claim 1 is provided with a pair of transparent substrates which face each other, a pair of alignment films which are respectively provided on the pair of transparent substrates and are separated by a space T, and on the substrate. A transparent electrode and a liquid crystal having an ordinary refractive index n ₀ and an extraordinary refractive index n _e enclosed between a pair of alignment films, and the alignment directions of the liquid crystal molecules of the liquid crystal are parallel to the surface of the alignment film. In addition, the first region and the second region which are orthogonal to each other are arranged alternately, and the incident light that has entered the liquid crystal is all zero-order diffracted light when a voltage is applied between the electrodes. It is characterized in that the light is emitted as high-order diffracted light when the light is emitted and no voltage is applied.

A liquid crystal device according to a second aspect of the present invention is provided with a pair of transparent substrates facing each other, a pair of alignment films respectively provided on the pair of transparent substrates and spaced apart by a distance T, and provided on the substrate. A transparent electrode and a liquid crystal having an ordinary refractive index n ₀ and an extraordinary refractive index n _e enclosed between a pair of alignment films, and the alignment directions of the liquid crystal molecules of the liquid crystal are parallel to the surface of the alignment film. In addition, the first region and the second region which are orthogonal to each other are alternately arranged, and the distance T between the alignment films, the ordinary refractive index n _{0 of} the liquid crystal, and the extraordinary refractive index n
_e and the wavelength λ of the incident light incident on the liquid crystal, or the wavelength λ
Between (n _e − n ₀ ) T = λ (2m + 1) / 2 (m
= Integer).

In the liquid crystal element of the third aspect of the present invention, the first region and the second region both have a striped shape and are arranged alternately in one direction on the surface of the alignment film. It is characterized by that.

According to a fourth aspect of the invention, in the liquid crystal element, the first region and the second region both have a rectangular shape, and one direction on the surface of the alignment film and a direction orthogonal to the one direction. It is characterized in that it is arranged alternately.

A liquid crystal device according to a fifth aspect of the present invention is characterized in that only one of the pair of alignment films is subjected to alignment treatment.

The liquid crystal device according to the invention of claim 6 is characterized in that the alignment film is made of a photosensitive resin.

[0037]

According to the invention described in claim 1, the alignment film has a first region and a second region having orthogonal alignment directions, and a first region having orthogonal alignment directions, and By alternately arranging the two regions, the light transmitted through the first region or the second region has a difference in refractive index due to the change of the propagation medium. Since the diffraction direction of light correlates with the difference in refractive index, it is possible to control the diffraction direction of light by controlling the refractive index.

Controlling that all the polarization components of the incident light become 0th order diffracted light when a voltage is applied and all become high order diffracted light when no voltage is applied realizes ideal characteristics in the liquid crystal element. Is possible. According to the invention of claim 2, between the distance T of the alignment film, the ordinary refractive index n _{0 of} liquid crystal, the extraordinary refractive index _ne, and the wavelength λ of light, (n _e −n ₀ ) T = λ ( 2m + 1) / 2, (m =
By satisfying the relationship of (integer), light can be diffracted to a higher order in a state where no voltage is applied to the transparent substrate and the transparent electrode. Therefore, when the liquid crystal element is set to the OFF state when no voltage is applied, it is in a good OFF state in which there is no polarization component diffracted in the incident direction.

According to the third aspect of the invention, the step of alternately arranging the regions where the liquid crystal molecules in the liquid crystal are orthogonal to each other can be easily realized.

According to the invention described in claim 4, the diffraction effect of the liquid crystal element can be further enhanced.

According to the fifth aspect of the invention, the first region and the second region of the alignment film are formed only on one of the pair of transparent substrates, so that the alignment film is formed on the surface of the transparent substrate. The work involved is reduced, the manufacturing process is simplified, and alignment of the alignment film is not necessary when the transparent substrates are combined.

According to the sixth aspect of the invention, since the alignment film is made of a photosensitive resin, damage to the alignment film in the step of providing regions having different alignment directions on the alignment film is reduced.

[0043]

1A and 1B are schematic configuration diagrams of a liquid crystal element 11 according to a first embodiment of the present invention. (A) shows a state where no voltage is applied to the transparent electrodes 13a and 13b,
(B) shows a state where a voltage is applied.

First, the structure of the liquid crystal element 11 is such that the first transparent substrate 12a and the second transparent substrate 12b are formed on the first transparent substrate 12a and the second transparent substrate 12b, respectively.
Transparent electrode 13a and second transparent electrode 13b are formed. Alignment films 14a, 14 on the transparent electrodes 13a, 13b
b is formed. On the alignment films 14a and 14b, regions having different alignment directions are provided and arranged at equal intervals by a process described later. The substrates 12a and 12b having the transparent electrodes 13a and 13b and the alignment films 14a and 14b formed thereon are arranged at intervals T so that the surfaces having the alignment films 14a and 14b face each other, and the liquid crystal 15 is sealed between them. To do.

Light incident on the liquid crystal element 11 is shown as 17. The light 17 is composed of polarized components 17a and 17b.

The alignment directions of the liquid crystal 15 according to the alignment directions of the alignment films 14a and 14b are, as shown by the liquid crystal molecules 15a, orthogonal to each other in adjacent regions.

In the block diagram of this embodiment, liquid crystal molecules 1
A region in which 5a is oriented in a direction parallel to the polarized component 17a is defined as a region 16a, and a region in which 5a is oriented parallel to the polarized component 17b is defined as 16b.

Next, referring to FIG. 1B, the transparent electrode 13
A state in which a voltage is applied to a and 13b will be described.

The structure of the liquid crystal element is the same as that shown in FIG. 1A, but the liquid crystal molecules 15a in the liquid crystals 15 in the regions 16a and 16b are applied by applying a voltage to the sealed liquid crystal molecules 15a. The optical axes of both are transparent electrodes 13a, 13
It is oriented in a direction perpendicular to b. Next, the liquid crystal element 11
A specific method of forming the alignment films 14a and 14b will be described.

2A to 2C show alignment films 14a and 1a.
It is a figure explaining the process of forming 4b. In the present embodiment, the transparent substrates 12a and 12b are substrates that form a projection type display liquid crystal panel. This substrate has a structure already provided with electrodes.

First, in the step described with reference to FIG. 2A, a photosensitive polyimide alignment material is transferred and printed on the transparent electrode 13b, and a film serving as a matrix of the alignment film 14b is formed by the steps of irradiation with ultraviolet rays and baking. . The entire surface of the formed alignment film 14b is rubbed in a fixed direction (for example, the x direction parallel to the paper surface shown in FIG. 2A). Since the rubbing process is a process performed to determine the alignment direction of the alignment film, the alignment film 14b having a constant alignment direction is formed.

Next, as shown in FIG. 2B, the alignment film 14b is formed.
A pattern is formed by the resist 18 on the top. In this example, a striped pattern having a pitch of 5 μm was used. The rubbing process is performed again using the patterned resist 18 as a mask. This rubbing process is performed in a direction orthogonal to the direction of the rubbing process previously performed (for example, the y direction perpendicular to the paper surface shown in FIG. 2B). ).

The orientation of the orientation film is effective after the rubbing treatment, so that the region on the orientation film 14b covered by the resist 18 has the orientation direction shown by x in FIG. 2 (a). However, since the uncovered region on the alignment film 14b has the alignment direction indicated by y in FIG.
When the peeling of No. 8 is performed, 5 having the orientation directions orthogonal to each other are obtained.
The alignment film 14b having stripe regions with a pitch of μm is completed.

In the liquid crystal element 11 of this embodiment, the alignment film 14
By using the photosensitive polyimide alignment material for a and 14b, it is possible to reduce the damage given to the alignment films 14a and 14b by the developer used in the step of developing the resist 18. Finally, as shown in FIG. 2C, the same process as the above process is performed to form the substrate 12a provided with the alignment film 14a in which the regions in which the alignment directions of the liquid crystal molecules are orthogonal to each other are formed at a pitch of 5 μm. The alignment films 14a, 14
b are arranged facing each other.

At this time, it is necessary to align the alignment films 14a and 14b so that regions having the same alignment direction overlap each other.

Through the above steps, the liquid crystal element 11 having the structure shown in FIG. 4 is obtained. FIG. 4 is a perspective view of FIG.

Now, returning to FIGS. 1A and 1B again, the function of the liquid crystal element 11 of this embodiment will be described.

For convenience of explanation, the light source 17 is shown as a point light source.
Is uniformly incident on the entire area of the transparent substrate 12b from the illustrated direction.

In the state where the voltage shown in FIG. 1A is not applied, the liquid crystal molecules 15a are formed in the regions 16a and 16b.
Are directed in different directions, the refractive indices of the polarization components 17a and 17b incident on the region 16a are different. Polarization component 17a
For example, the liquid crystal molecules 15 are polarized relative to the polarization direction.
When incident on the region 16a in which the orientation direction of a is parallel, the polarization component 17a feels an extraordinary refractive index n _e . Also,
When entering the region 16b in which the alignment direction of the liquid crystal molecules 15a is perpendicular to the polarization direction, the ordinary refractive index n ₀ is felt.

The polarized component 17a which has propagated through the medium having different refractive index and is transmitted is diffracted by the liquid crystal 15,
They interfere with each other and are taken out from the transparent substrate 12a.
At this time, as described above, if the relationship of ΔnT = λ (2m + 1) / 2 (2) holds, all the polarization components 17a cause high-order diffraction.

Further, when the condition of Δn = 0 (3) is satisfied, all 17a cause 0th-order diffraction.

Therefore, when the liquid crystal element 11 is designed so as to satisfy the condition (n _e −n ₀ ) T = λ / 2 (4), the polarization component 17a is applied to the transparent electrode 13a by a voltage. In the state where is not applied, higher-order diffraction, that is, diffraction in which the light diffracted in the incident direction becomes 0, occurs.

On the other hand, since the polarization component 17b also causes high-order diffraction like the polarization component 17a when no voltage is applied, in the liquid crystal element 11, the transparent electrodes 13a and 13b are formed.
When the voltage is not applied to 0, the 0th-order diffracted light of all the lights 17 becomes 0.

In the state where the voltage shown in FIG. 1 (b) is applied, the liquid crystal molecules 15a in both the regions 16a and 16b face the direction perpendicular to the transparent electrodes 13a and 13b. Since this direction is perpendicular to both the polarization components 17a and 17b, the value of Δn, which is the difference between the refractive indices of the light incident on the region 16a and the light incident on the region 16b, becomes 0, and (3)
Satisfy the formula.

Therefore, in the liquid crystal element 11 of the present embodiment, all the light 17 is diffracted in the 0th order when the voltage is applied to the transparent electrodes 13a and 13b, and the maximum value of the intensity of the transmitted light is obtained.

The above results are summarized in FIG.

From FIG. 3, when the liquid crystal element 11 is in the ON state, all the incident light is diffracted to the 0th order without weakening the intensity of the light, and all the incident light in the OFF state is subjected to the high order diffraction. To do. This makes it possible to realize a liquid crystal element which has a bright screen when turned on and has a high contrast when turned on and when turned off.

Next, a second embodiment of the present invention will be described.

FIG. 5 is a schematic diagram of the liquid crystal element 21 of the second embodiment.

In the first embodiment, the first region and the second region in which the alignment directions of the liquid crystal molecules are orthogonal to each other are both stripe-shaped on the alignment film and are provided only in one direction. However, the shape and arrangement of the regions are not limited to this example. For example, in the liquid crystal element 21 of the second embodiment, both the first region and the second region have a rectangular shape, Moreover, it is configured to be provided in one direction with respect to the incident direction of light and in a direction orthogonal to the direction.

By forming the regions 16a and 16b in which the alignment directions of the liquid crystal molecules 15a are orthogonal to each other as shown in FIG. 5, it is possible to further enhance the diffraction effect.

In the liquid crystal element 21, as shown in FIG.
The alignment film 14 is formed by a process similar to the process shown in FIG.
The rubbing process is performed on a and 14b.
After the rubbing process on the entire surfaces of the alignment films 14a and 14b shown in (a), a pattern of the resist 18 is formed so that the regions 16a and 16b shown in FIG. 5 can be arranged. That is, in the first embodiment, the pattern of the resist 18 which is striped and arranged only in one straight line direction is made into a rectangular shape and is arranged in the straight line directions orthogonal to each other, and a region masked by the resist 18 and a region not masked are formed. It is realized by alternately arranging the alignment films 14a and 14b on the entire surface and performing a rubbing process in the perpendicular direction.

Next, FIG. 6 shows a schematic block diagram of the third embodiment.

FIG. 6 is a sectional view of the liquid crystal element 31 of the third embodiment. The liquid crystal element 31 of this embodiment is characterized in that the regions 16a and 16b in which the alignment directions of the liquid crystal molecules 15a are orthogonal to each other are provided only on one of the alignment films 14a and 14b. That is, the regions which are orthogonal to each other are provided on the alignment film 14a by the same process as the process described in the liquid crystal element 11 of the first embodiment for the substrate 12a (12b is also possible).
On the other substrate 12a, a photosensitive polyimide alignment material is transferred and printed, and only the ultraviolet irradiation and firing steps are performed, and the subsequent rubbing process is not performed. The alignment film which is not subjected to this rubbing treatment is shown as 14c.

Even if only one of the pair of substrates 12a and 12b is provided and the alignment films 14a are arranged in opposite directions to seal the liquid crystal 15, the liquid crystal molecules 15a are applied to one substrate. Since the alignment treatment is performed, the liquid crystal element 31 having the same effect as that of the first embodiment is obtained.

.. In the third embodiment, since the regions 16a and 16b are provided only on the substrate 12a, the manufacturing process is simpler than that of the liquid crystal element 11 of the first embodiment and the liquid crystal element 21 of the second embodiment, and the substrate is This has the effect of facilitating alignment when arranging 12a and 12b. The method of simplifying the process by subjecting only one alignment film to the labyrinth process of the third embodiment can be applied to both the liquid crystal element 11 of the first embodiment and the second embodiment 21. From the correlation between the wavelength λ of light shown in (1) and (2) and the interval T of the alignment film on the substrate, the interval T of the alignment film on the substrate is calculated.
It is understood that it is possible to control the light of the desired wavelength by changing the.

Therefore, the above-mentioned liquid crystal elements 11, 21,
Whichever of 31 is used, light having different wavelengths of red (R), green (G), and blue (B) is controlled and combined by changing the interval T between the alignment films on the transparent substrate. By doing so, it is possible to create a liquid crystal panel for a projection display.

A schematic structure is shown in FIG. 7 as an example of a liquid crystal panel of this projection type display.

The light emitted from the light source 100 is reflected by the mirrors 108, 1
The liquid crystal elements 103, 104, and 105 pass through 06 and the like, and are combined on the screen 107 to form an image.

In the liquid crystal elements 103, 104 and 105, the intervals between the transparent substrates are designed so as to control the wavelength regions corresponding to the colors of R, G and B, respectively. For example, the refractive index of liquid crystal is as follows: ordinary refractive index n ₀ = 1.5230, extraordinary refractive index n _e = 1.7.
The distance between the alignment films of the liquid crystal element for R display is T = 5.1 μm, and the distance between the alignment films of the liquid crystal element for G display is T = 4.5 μm. The interval T = 3.9 μm.

[0081]

According to the first aspect of the present invention, when the voltage is applied, all the polarization components of the incident light can be made into the 0th order diffracted light, and when the voltage is not applied, all the higher order diffracted light can be obtained. It is possible to obtain an ideal characteristic that is bright and has a high ON / OFF contrast.
According to the second aspect of the invention, between the distance T of the alignment film, ordinary refractive index n ₀ of the liquid crystal, and the extraordinary refractive index n _e, and the wavelength of light _{λ, (n e - n 0} ) T = λ (2m + 1) / 2 (m
= Integer), the darkest OFF state can be realized, and good characteristics with high contrast with the ON state can be obtained.

According to the invention of claim 3, ON, OF
The alignment treatment process of the alignment film of the liquid crystal element having a high F contrast and a bright liquid crystal surface when ON can be easily performed.

According to the invention described in claim 4, it is possible to further enhance the diffraction effect of the liquid crystal element and realize a liquid crystal element of higher performance.

According to the invention described in claim 5, the manufacturing process is simplified, and the alignment film is not required to be aligned when the transparent substrate is combined, so that the process yield is improved and the manufacturing cost of the liquid crystal device is improved. Can be reduced.

According to the sixth aspect of the present invention, damage to the alignment film is reduced in the step of providing regions having different alignment directions on the alignment film, the process is stabilized, and the reliability of the liquid crystal element is further enhanced. You can

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention.
(A) shows a state where no voltage is applied, and (b) shows a state where a voltage is applied.

FIG. 2 shows a manufacturing process of a liquid crystal device according to a first embodiment of the present invention. (A), (b) and (c) show the order of the steps.

FIG. 3 is a diagram summarizing diffraction results performed on incident light by the liquid crystal element according to the first embodiment of the present invention.

FIG. 4 is a perspective view of FIG.

FIG. 5 is a schematic configuration diagram of a second embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a third embodiment of the present invention.

FIG. 7 is a diagram showing a schematic configuration of a TFT liquid crystal panel configured by using the liquid crystal element of the present invention for reference.

FIG. 8 is a schematic configuration diagram of a liquid crystal element using a conventional diffraction grating. (A) shows a state where no voltage is applied, and (b) shows a state where a voltage is applied.

FIG. 9 is a diagram summarizing diffraction results performed on incident light by a liquid crystal element using a conventional diffraction grating.

FIG. 10 is a diagram showing an example of a configuration in which liquid crystal elements using a conventional diffraction grating are laminated.

[Explanation of symbols]

 11, 21, 31 Liquid crystal element 12a, 12b Transparent substrate 13a, 13b Transparent electrode 14a, 14b, 14c Alignment film 15 Liquid crystal 15a Liquid crystal molecule 16a, 16b Alignment film region 17a, 17b Polarization component of incident light 103, 104, 105 Liquid crystal element

Claims (6)

[Claims] 1. A pair of transparent substrates facing each other, a pair of alignment films respectively provided on the pair of transparent substrates with a distance T therebetween, a transparent electrode provided on the substrate, A liquid crystal having an ordinary refractive index n ₀ and an extraordinary refractive index n _e enclosed between a pair of alignment films, and the alignment directions of the liquid crystal molecules of the liquid crystal are both parallel to the surface of the alignment film. , And has a structure in which first regions and second regions that are orthogonal to each other are alternately arranged, and all incident light that has entered the liquid crystal is emitted as 0th-order diffracted light when a voltage is applied between the electrodes. In addition, the liquid crystal element is characterized in that all the light is emitted as high-order diffracted light when no voltage is applied. 2. A pair of transparent substrates facing each other, a pair of alignment films respectively provided on the pair of transparent substrates with a distance T therebetween, a transparent electrode provided on the substrate, A liquid crystal having an ordinary refractive index n ₀ and an extraordinary refractive index n _e enclosed between a pair of alignment films, and the alignment directions of the liquid crystal molecules of the liquid crystal are both parallel to the surface of the alignment film. And the first region and the second region which are orthogonal to each other are alternately arranged, and the distance T between the alignment films, the ordinary refractive index n _{0 of the} liquid crystal, and the extraordinary refractive index n _e , Between the wavelength λ of the incident light entering the liquid crystal and the incident light having a distribution centered around the wavelength λ, (n _e −n ₀ ) T = λ (2m + 1) / 2 (m
= Integer), the liquid crystal element is configured to satisfy the relationship. 3. The first region and the second region both have a striped shape, and are arranged alternately in one direction on the surface of the alignment film. The liquid crystal element according to claim 1 or 2. 4. The first region and the second region both have a rectangular shape and are alternately arranged on the surface of the alignment film in one direction and in a direction orthogonal to the one direction. 3. The liquid crystal device according to claim 1, wherein the liquid crystal device has the above structure. 5. The liquid crystal device according to claim 1, wherein only one of the pair of alignment films is subjected to the alignment treatment. 6. The liquid crystal device according to claim 1, wherein the alignment film is made of a photosensitive resin.