JPH08262424A - Liquid crystal display device, liquid crystal display method and diffraction grating medium for liquid crystal display device - Google Patents

Abstract

PURPOSE: To lessen the attenuation of illumination light and to brighten a screen by constituting a diffraction grating media of microdiffraction gratings which form the diffracted light rays of the colors ought to be displayed by corresponding display pixels. CONSTITUTION: A pair of ray sources 14A, 14B are so formed that the entire area of reflection type embossed holograms 20 is illuminated by parallel beams in superposition by a specific incident angle from the right and left of the normal of the front surface of the reflection type embossed holograms 20. In such a case, the reflection type embossed holograms 20 are constituted by arranging the microdiffraction gratings 22A to 22C patterned to vary characteristics in this order in such a manner that the first order diffracted light rays are respectively R, G, B when the holograms are illuminated by the parallel beams from the ray sources 14A, 14B in correspondence to three primary colors R, G, B of a liquid crystal panel. As a result, color display is made without using the color filters.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, a liquid crystal display method and a hologram for a liquid crystal display device.

[0002]

2. Description of the Related Art As a color liquid crystal display device, for example, liquid crystal is held between two substrates having display electrodes, and one substrate side is provided with a plurality of filters for color display corresponding to display pixels. There is one in which color display is performed by controlling the voltage between the counter electrodes to selectively change the light transmission amount of the display section.

[0003]

In the liquid crystal display device using the color filter for color display as described above,
The light transmittance of the color filter is about ⅙, and even an ideal optical system has a limit of ⅓, and there is a problem that the light utilization efficiency is low, that is, the screen becomes dark.

Further, a liquid crystal display device having a color filter has a problem that productivity is low and a yield is low. Particularly, when the size of the liquid crystal screen is large, it is difficult to manufacture and the cost is high. It was

The present invention has been made in view of the above-mentioned problems of the prior art. The utilization efficiency of illumination light is high, the screen is bright, the productivity and the yield can be further improved, and the size is large. An object of the present invention is to provide a liquid crystal display device, a liquid crystal display method, and a diffraction grating medium for a liquid crystal display device that can be easily manufactured at low cost even on a screen.

[0006]

According to the present invention, a liquid crystal is held between two substrates each having a display electrode for each display pixel, and a color display means corresponding to each display pixel is provided outside one substrate. In a liquid crystal display device that is provided and performs color display by controlling the voltage between opposing electrodes to selectively change the light transmission amount of illumination light in the display section, the color display means displays the corresponding display pixel. A liquid crystal display characterized in that a diffraction grating medium is formed by successively patterning at least three kinds of minute diffraction gratings having different characteristics by changing the pitch of grating stripes so as to form diffracted light of the desired color. The device achieves the above object.

According to a second aspect of the present invention, in the first aspect of the present invention, the illumination light source is arranged so that only one illumination light is incident on one minute diffraction grating in the diffraction grating medium. Directional lighting.

According to a third aspect of the present invention, in the second aspect, the light source is composed of a plurality of small light sources that illuminate different regions of the diffraction grating medium at equal incident angles.

According to a fourth aspect of the present invention, in the third aspect of the invention, the plurality of small light sources irradiate at a same angle from two directions which are symmetrical with respect to the normal line of the diffraction grating medium surface and the grating fringes. It was placed in.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the grating pitch of the minute diffraction gratings is circulated in the direction of the adjacent minute diffraction gratings to emit light.
The secondary diffracted light has the same color as the primary diffracted light formed by the adjacent minute diffraction grating.

According to a sixth aspect of the present invention, in the first to fifth aspects, the illumination light source is a linear parallel white light source.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects of the invention, the illumination light is corrected so that a color shift due to a shift of an incident angle of the illumination light is corrected for one of the illumination lights. The grating pitch of the minute diffraction grating on the side far from the light source of
The grating pitch of the minute diffraction grating on the near side is made smaller according to the distance from the light source.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects of the present invention, the minute amount in the diffraction grating medium is corrected so as to correct a color shift due to a change in viewing angle from the front of the diffraction grating medium. The grating pitch of the minute diffraction grating on the central side in the direction orthogonal to the diffraction grating is made larger than the grating pitch of the minute diffraction grating at the end in the orthogonal direction according to the distance from the end.

According to a ninth aspect of the present invention, in the eighth aspect, the light source illuminates a region of the diffraction grating medium, which is divided into two parts in a direction orthogonal to the minute diffraction grating, from different directions at equal incident angles. It is used as a light source.

According to a tenth aspect of the present invention, in any one of the first to seventh aspects of the invention, the color shift due to the shift of the incident angle of the illumination light and the color shift due to the change of the viewing angle of the diffraction grating medium from the front side. The grating pitch of the minute diffraction grating is changed according to the distance from the illumination light and the distance from the center of the diffraction grating medium so as to correct

According to an eleventh aspect of the present invention, in any one of the first to tenth aspects of the present invention, the minute amount in the diffraction grating medium is corrected so as to correct the luminance change due to the change in the viewing angle from the front of the diffraction grating medium. The area of the minute diffraction grating in the central portion in the direction parallel to the diffraction grating is made smaller according to the distance from the end than in the end in the parallel direction.

According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects of the present invention, the fine diffraction grating is arranged such that its grating stripes are in the vertical direction, and the light source of the illumination light is the fine diffraction grating. It is arranged so that the illumination light enters in the direction orthogonal to the lattice stripes.

According to a thirteenth aspect of the present invention, in the first aspect of the present invention, the minute diffraction grating is arranged such that its grating stripes are parallel to a tangent line of a virtual concentric circle centered on the screen center of the display section, The light source of the illumination light is a ring-shaped light source centered on the center of the screen.

According to a fourteenth aspect of the present invention, in the thirteenth aspect of the present invention, the fine diffraction grating has a lattice fringe in a direction orthogonal to virtual radiation extending in eight directions from the center of the screen up and down, left and right, and an intermediate direction thereof. It is arranged as follows.

According to a fifteenth aspect of the present invention, in the above-mentioned thirteenth or fourteenth aspect, the diffraction grating medium is a transmission type,
The illumination light source is a plurality of concentric ring-shaped white light sources that illuminate the diffraction grating medium from the back side.

According to a sixteenth aspect of the present invention, in the first aspect of the present invention, the light source of the illumination light is for each fine diffraction grating of the diffraction grating medium, with respect to a normal line and a grating fringe of the surface of the diffraction grating medium. This is a bidirectional illumination in which light is incident from two symmetrical directions at equal angles and the respective minute diffraction gratings are superimposed and illuminated.

According to a seventeenth aspect of the present invention, in the invention according to any one of the first to sixteenth aspects, the diffraction grating medium is a transmissive type, and the illumination light is a backlight for illuminating the diffraction grating medium from the back surface. is there.

The invention of claim 18 relates to claims 1 to 14,
In any one of the sixteenth inventions, the diffraction grating medium is a reflection type, and the illumination light is used as a backlight of a display pixel by illuminating the diffraction grating medium from the surface.

According to a nineteenth aspect of the present invention, a liquid crystal is held between two substrates each having a display electrode for each display pixel, and a voltage between opposing electrodes is controlled to select a light transmission amount of illumination light in a display section. In a liquid crystal display device for monochromatic display of an image by changing the wavelength of the diffraction grating to form a diffractive grating medium that forms a diffracted light having a wavelength equal to the light to be displayed by the display pixel on the outside of the one substrate. And a liquid crystal display device characterized in that the grating pitch of the minute diffraction grating is changed according to the position.

According to a twentieth aspect of the invention, in the nineteenth aspect of the invention, one illumination light has a minute distance on the side far from the illumination light so as to correct the luminance shift due to the deviation of the incident angle of the illumination light. The grating pitch of the diffraction grating is smaller than the grating pitch of the minute diffraction grating on the near side according to the distance.

The invention of claim 21 is the invention of claim 19 or 20.
In the invention described above, the grating of the minute diffraction grating on the central portion side in the direction orthogonal to the grating fringes of the minute diffraction grating in the diffraction grating medium so as to correct the color shift due to the change in the viewing angle from the front of the diffraction grating medium. The pitch is made larger than the grating pitch of the minute diffraction grating at the end in the orthogonal direction according to the distance from the end.

According to a twenty-second aspect of the present invention, in the nineteenth, twenty-third, or twenty-first aspect, the minute diffraction in the diffraction grating medium is corrected so as to correct a change in luminance due to a change in viewing angle from the front of the diffraction grating medium. The area of the minute diffraction grating in the central portion in the direction parallel to the grating is made smaller according to the distance from the end than in the end in the parallel direction.

The invention of claim 23 is based on claims 19 to 22.
In any one of the inventions, the fine diffraction grating is arranged so that its grating fringes are parallel to the tangents of a virtual concentric circle centered on the screen center in the display unit, and the light source of the illumination light is arranged on the screen center. It is a centered ring light source.

According to a twenty-fourth aspect of the present invention, liquid crystal is held between two substrates provided with a display electrode for each display pixel, and diffracted light of a color to be displayed by the corresponding display pixel is provided outside one substrate. A minute diffraction grating medium formed by patterning at least three types of diffraction gratings having different characteristics by changing the pitch of the grating stripes so as to be formed is arranged for each display pixel, and the voltage between the display electrodes facing each other is controlled. Then, the above object is achieved by a liquid crystal display method in which color display is performed by selectively changing the amount of liquid crystal light transmission between the display electrodes.

According to a twenty-fifth aspect of the present invention, there is provided a diffraction grating medium including a minute diffraction grating arranged so as to form diffracted light in a display pixel direction corresponding to each display pixel in the liquid crystal display device, The diffraction grating is arranged so that the corresponding display pixel forms diffracted light of at least three colors to be displayed.
The above-mentioned object is achieved by a diffraction grating medium for a liquid crystal display device, which is characterized by being patterned into the above types.

According to a twenty-sixth aspect of the present invention, in addition to the twenty-fifth aspect of the present invention, the minute diffraction grating is duplicated by an emboss method.

[0032] The invention of claim 27 is based on claim 25 or 26.
In the invention, the second-order diffracted light emitted by wrapping the grating pitch of the minute diffraction grating in the direction of the adjacent minute diffraction grating has the same color as the first-order diffracted light formed by the adjacent minute diffraction grating. It is a thing.

According to a twenty-eighth aspect of the invention, in the twenty-fifth, twenty-sixth or twenty-seventh aspect of the invention, the minute diffraction in the diffraction grating medium is corrected so as to correct the color shift due to the change in the viewing angle from the front of the diffraction grating medium. The grating pitch of the minute diffraction grating on the central portion side in the direction orthogonal to the grating is made larger than the grating pitch of the minute diffraction grating at the end portion in the orthogonal direction according to the distance from the end portion.

The invention of claim 29 is based on claims 25 to 28.
In any one of the inventions, the grating pitch of the minute diffraction grating is changed from the illumination light so as to correct the color deviation due to the deviation of the incident angle of the illumination light and the color deviation due to the change of the viewing angle from the front of the diffraction grating medium. And the distance from the center of the diffraction grating medium.

[0035] The invention of claim 30 is based on claims 25 to 29.
In any one of the inventions, the fine diffraction grating of the central portion of the diffraction grating medium in the direction parallel to the fine diffraction grating is corrected so as to correct the change in luminance due to the change in the viewing angle from the front of the diffraction grating medium. The area is made smaller in accordance with the distance from the end than in the parallel end.

[0036]

The diffraction grating medium of the liquid crystal display device according to the present invention is
The corresponding display pixel is composed of a minute diffraction grating that forms diffracted light of the color to be displayed, and the illumination light is emitted to the display pixel as diffracted light of a predetermined color without being significantly attenuated. Therefore, since the illumination light is less attenuated, the screen can be significantly brightened as compared with the case where the conventional color filter is used.

Here, if unidirectional illumination is performed so that only one illumination light is incident on one minute diffraction grating, the use of another 1st-order diffracted light or another 2nd-order diffracted light that wraps around the adjacent minute diffraction grating, and pitch, It becomes easy to correct the pattern such as the angle.

If the light sources are a plurality of light sources that illuminate different areas, the light amount balance on the entire screen can be improved.

In particular, a plurality of light sources can be dispersedly arranged along the surface of the diffraction grating medium to make it brighter and to have a good light quantity balance.

By making the grating pitch of the minute diffraction grating have the same color as the color to be formed by the first-order diffracted light of the adjacent minute diffraction grating, the first-order or second-order diffracted light that wraps around from the grating to the adjacent portion is obtained. The screen brightness can be improved.

If the grating pitch of the minute diffraction grating on the side far from the light source of the illumination light is made smaller than that on the side closer to it, the color shift due to the shift of the incident angle of the illumination light can be corrected and accurate color display can be performed. In this case, color misregistration can be corrected even if there is an error in the parallelism of the light from the light source.

Further, in this case, the light source of the illumination light can be corrected even if it is one line light source having a point-shaped cross section and the incident angle of the illumination light varies depending on the position from the light source.

In the liquid crystal display screen, if the grating pitch of the minute diffraction grating at the central portion in the direction orthogonal to the minute diffraction grating is made larger than the end portion, the viewing angle changes depending on whether the screen is viewed from the front or obliquely. Color shift can be corrected.

In this case, if the light source is a pair of light sources that illuminate a region bisected in the direction orthogonal to the minute diffraction grating on the screen from different directions, the screen can be bright and the thickness of the light source can be reduced. .

Further, if the grating pitch of the minute diffraction grating is adjusted so as to simultaneously correct the color shift due to the shift of the incident angle of the illumination light and the color shift due to the change of the viewing angle, both changes cancel out. The amount of change in the grating pitch can be reduced.

Generally, the brightness of the central part of the screen in the direction parallel to the diffraction grating of the diffraction grating medium is higher than that of both ends in the same direction. Therefore, if the area of the minute diffraction grating on the central part side is made smaller than the end part, the screen The brightness of can be made uniform.

Further, when the minute diffraction gratings are arranged with their grating stripes arranged in the vertical direction, indoor illumination light from above the screen and sunlight from the window are not diffracted, so that unevenness of the screen due to ambient light can be prevented. it can.

By arranging in the direction of the minute diffraction grating and in the tangential direction of a concentric circle with the center of the screen and illuminating this with a ring-shaped light source, it is possible to prevent the above-mentioned decrease in brightness due to a change in viewing angle and decrease in brightness in the peripheral portion.

In this case, if the direction of the grating fringes of the minute diffraction grating is arranged orthogonal to the virtual radiation extending in eight directions from the center of the screen, the minute diffraction grating can be easily formed.

Further, in this case, when the transmission type diffraction grating medium is used to illuminate the rear surface with a plurality of concentric ring-shaped light sources, the light quantity balance can be improved and the screen can be brightened.

Further, by superimposing and illuminating each of the minute diffraction gratings from two directions at the same incident angle, it is possible to improve the light amount balance of the screen.

Further, by forming the diffraction grating medium as a transmissive or reflective embossed hologram, it is possible to easily and inexpensively construct a minute diffraction grating.

Further, in a liquid crystal display device for monochrome display, if the grating pitch of the minute diffraction grating is changed according to the position, for example, the grating pitch of the minute diffraction grating on the side far from the light source becomes smaller, the illumination It is possible to correct the color shift due to the shift of the incident angle of light.

Further, in this way, the color shift can be surely corrected even if the light source of the illumination light is one line light source having a point-shaped cross section.

Further, in the liquid crystal display device for monochrome display as described above, by making the grating pitch in the central portion of the screen in the direction orthogonal to the minute diffraction grating larger than the grating pitch at the end portions of the screen, It is possible to correct coloring and uneven brightness.

Further, the area of the fine diffraction grating in the central portion of the screen in the direction parallel to the fine diffraction grating is made smaller than that at the end portion in accordance with the distance from the end portion to correct the change in screen luminance due to the change in viewing angle. As a result, uniform brightness can be obtained.

Further, when the minute diffraction grating is positioned in the tangential direction of the concentric circle with the center of the screen and illuminated by a ring-shaped light source, it is possible to prevent the above-mentioned decrease in brightness due to the change in viewing angle and the decrease in brightness in the peripheral portion. it can.

According to the liquid crystal display method of the present invention, color display can be performed by the liquid crystal without using a color filter, so that the liquid crystal screen can be brightened.

Further, according to the diffraction grating medium for a liquid crystal display device of the present invention, since the diffracted light has a predetermined amount, when this is used for a liquid crystal display device, a color filter is not used, and accordingly, The color in each display pixel can be displayed brightly without attenuating the illumination light. Further, the diffraction grating medium, for example, when using an embossed hologram,
It is easier to manufacture than a color filter, and the manufacturing cost can be reduced.

In the above-mentioned diffraction grating medium for liquid crystal display, the grating pitch of the minute diffraction grating is defined as the color to be formed by the first-order diffracted light of the minute diffraction grating adjacent to the first-order or second-order diffracted light wrapping from the grating to the adjacent portion. By making the colors the same, the brightness of the screen can be improved.

Further, if the grating pitch of the minute diffraction grating in the central portion in the direction orthogonal to the minute diffraction grating is made larger than that of the end portion, the color shift due to the change of the viewing angle when viewed from the front and when viewed obliquely is corrected. be able to.

Further, if the grating pitch of the minute diffraction grating is adjusted so as to simultaneously correct the color deviation due to the deviation of the incident angle of the illumination light and the color deviation due to the change of the viewing angle, both changes cancel each other out, and therefore the grating pitch changes. The amount can be reduced.

In general, the brightness of the central part of the screen in the direction parallel to the diffraction grating of the diffraction grating medium is higher than that of both ends in the same direction. Therefore, if the area of the minute diffraction grating on the central part side is made smaller than that on the end side, The brightness of can be made uniform.

[0064]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a color liquid crystal display device 10 according to the first embodiment of the present invention has a backlight 14 and a color display means 16 composed of a diffraction grating medium on the back side of a liquid crystal panel 12. It is arranged in combination.

This diffraction grating medium can be obtained by drawing a diffraction grating pattern on a predetermined medium using an electron beam on a resin sheet such as vinyl chloride as disclosed in JP-A-6-337315. It is obtained by pressing using a diffraction grating original plate.

However, since the diffraction grating medium of the present application is generally called a hologram, the term hologram is used in the embodiments described below.

The color display means 16 has a reflection type embossed hologram 20 attached on a glass substrate 18, and the reflection type embossed hologram 20 is a transparent embossed hologram film as shown in FIG. Two
A reflective film 20B made of aluminum is attached to the surface of 0A and embossed three-dimensionally.

The reflection type embossed hologram 20
Although the transmission type embossed hologram corresponds to a diffraction grating medium, a sheet obtained by embossing a resin sheet such as vinyl chloride is not necessarily used, and the glass substrate 18 is directly etched to form a diffraction grating. What was formed can also be used. However, the embossing method is preferable in terms of cost.

Like the conventional liquid crystal panel, the liquid crystal panel 12 has a pair of glass substrates 12A and 12B facing each other, a transparent electrode 12C and alignment films 12D and 12E, and a liquid crystal 12F held between them. Yes, glass substrate 12
Polarizing plates 12G and 12H are arranged outside the A and 12B, respectively.

The backlight 14 is adjacent to the outer side between the lower polarizing plate 12H and the reflection type embossed hologram 20 arranged in parallel with the lower polarizing plate 12H in the figure, and is paired left and right in FIG. The line light sources 14A and 14B that emit white parallel light are arranged.

The pair of linear light sources 14A and 14B superimposes the entire area of the reflection type embossed hologram 20 with an incident angle of θ from the left and right with respect to the normal line of the front surface of the reflection type embossed hologram 20 and forms parallel light. It is supposed to illuminate.

As shown in FIG. 2, the reflection-type embossed hologram 20 corresponds to the three primary colors of RGB in the liquid crystal panel 12, and is a first-order diffracted light when illuminated by parallel light from the linear light sources 14A and 14B. Are R and
When the fine diffraction gratings 22A to 22C are patterned to have different characteristics so as to be G and B, they are arranged in this order.

For example, the incident angle .theta. Of the parallel light reflected from the polarization sources 14A and 14B on the reflection type embossed hologram 20A.
= 60 °, the minute diffraction grating 2 in which the first-order diffracted light becomes R
The diffraction grating pitch of 2A is 0.75 μm, the diffraction grating pitch of the minute diffraction grating 22B representing G is 0.63 μm, and the diffraction grating pitch of the minute diffraction grating 22C representing B is 0.46.
μm.

In the reflection type embossed hologram 20, the illumination light incident from above is reflected by the concave portion 23A and scattered by the convex portion 23B, and the reflected light is diffracted.

In this embodiment, since the minute diffraction gratings 22A to 22C for outputting the first order diffracted light of R, G or B are arranged corresponding to RGB of the display pixels in the liquid crystal panel 12, a color filter is used. It is possible to display in color without.

Further, since the light is not attenuated by the color filter, the brightness on the screen of the liquid crystal panel 12 can be greatly improved and the power consumption of the backlight can be reduced.

In terms of manufacturing cost, an embossed hologram can be manufactured for several hundred yen for a liquid crystal panel having a color filter size of about 10,000 yen in the related art.

Further, in the case of a liquid crystal panel using a color filter, if the color filter is defective, it has a great influence on the optical characteristics such as color unevenness, so that the yield in the manufacturing process is low, but in the case of an embossed hologram. Even if some defects such as flaws do not affect the optical characteristics, the yield in the manufacturing process is extremely good. Also, conventional color C
In the case of a shadow mask in RT, convergence color shift is likely to occur, but in the case of this embodiment, since the color filter is replaced with an embossed hologram, color shift does not occur as in the color filter system. .

Next, a second embodiment of the present invention shown in FIG. 4 will be described.

The color liquid crystal display device 24 according to the second embodiment uses the transmissive embossed hologram 26, and the backlight 28 is a backlight arranged on the back side of the glass substrate 30. Light 28
Is composed of a plurality of small light sources 28A and 28B aligned in parallel with the glass substrate 30.

The small light sources 28A and 28B have the same incident angle with respect to the normal line of the glass substrate 30 and have the minute diffraction grating 22.
It is arranged so as to alternately irradiate the irradiated regions equally divided in the direction orthogonal to A to 22C (left and right direction in FIG. 4) from different directions.

Therefore, the small light source 28A is provided in one irradiation area.
Alternatively, parallel light is incident from only one of the two or 28B, and it is a unidirectional illumination for each irradiation area.

In this embodiment, since the small light sources 28A and 28B for emitting parallel rays can be arranged in multiple lamps in close contact with the liquid crystal panel, the color liquid crystal display device 10 in the first embodiment shown in FIG. It is possible to reduce the size of the panel in the thickness direction and to improve the balance of the entire illumination light amount.

In the transmissive embossed hologram 26, as shown in an enlarged view in FIG. 5, light is transmitted by the convex portion 26B of the embossed hologram film 26A and scattered by the concave portion 26C to diffract the transmitted light. It

Next, a third embodiment of the present invention shown in FIG. 6 will be described.

In the transmissive embossed hologram 32 according to the third embodiment, the grating pitch of the minute diffraction gratings constituting the hologram is formed by the adjacent minute diffraction gratings of the secondary diffracted light emitted in the direction of the adjacent minute diffraction gratings. The first-order diffracted light has the same color.

For example, as shown in FIG. 6, minute diffraction gratings 34A to 34 for forming first-order diffracted lights of R, B and G.
When C is arranged in this order, the grating pitch, the incident angle θ of the illumination light, and the diffraction angle α of the first-order diffracted light are set so that the following expressions are satisfied.

[0089]

[Equation 1]

Here, PR, PB and PG are the grating pitches of the minute diffraction gratings 34A to 34C, λR, λB and λG, respectively.
Is the wavelength of the first-order diffracted light of each of the minute diffraction gratings 34A to 34C, λG ^- λG ⁺ is the wavelength of the adjacent first-order diffracted light of the minute diffraction grating 34C, and λR _{2 +} is ₂ of the minute diffraction grating 34A.
Wavelength of diffracted light, .lambda.B _1/2 ^- denote respectively the wavelength of the diffracted light when set to the second-order diffracted light .lambda.B.

In this embodiment, the first-order or second-order diffracted light that wraps around the adjacent minute diffraction grating generated in the case of unidirectional illumination is positively utilized without being blocked, so that the brightness on the screen can be improved. Further, a means for blocking the diffracted light that wraps around is unnecessary.

Next explained is the fourth embodiment of the invention shown in FIG. The embossed hologram 36 according to the fourth embodiment is applied when there is an error in the parallelism of the light source of the backlight and the incident angle of the illumination light on the minute diffraction grating is deviated.

That is, when the embossed hologram 36 is unidirectionally illuminated by a linear light source 38 having a point-shaped cross section, such as a fluorescent lamp, the incident angle of the illumination light is close to that of the linear light source 38 in the embossed hologram 36. On the side, θ ₂ , linear light source 3
At a position farthest from 8, the angle becomes θ ₁ larger than θ ₂ .

The grating pitch P of the minute diffraction grating in the embossed hologram 38 is P sin θ = λ (wavelength of diffracted light), and the grating pitch P of the diffraction grating is such that λ becomes constant.
From the maximum P ₂ = λ / sin θ ₂ to the minimum P ₁ = λ / sin θ
It has been changed to ₁ .

Therefore, the fine diffraction grating on the side closer to the line light source 38 has a coarse pitch, and the grating pitch on the far side is finer, so that the color shift due to the shift of the incident angle of the illumination light from the line light source 38 can be corrected. it can.

Next explained is the fifth embodiment of the invention shown in FIG. The embossed hologram 40 according to the fifth embodiment corrects the viewing angle.

When the embossed hologram 40 has a large face, or when the face is observed close to the face, the line of sight shifts from the vertical direction to cause a color shift or a decrease in brightness as the line of sight moves toward the periphery.

In this embodiment, the pitch of the minute diffraction grating 41 is changed to correct the color misregistration, and in order to reduce the luminance, the opening area of the minute diffraction grating is changed so that the central portion is different from the peripheral portion. The brightness is made uniform by making it dark.

Specifically, in the embossed hologram 40, the central portion of the surface of the embossed hologram 40 in the direction orthogonal to the minute diffraction grating (left and right direction in FIG. 8) so as to correct the color shift due to the change in the viewing angle from the front. The grating pitch of the minute diffraction grating 41A on the side is made larger than the grating pitch of the minute diffraction gratings 41B at both ends in the orthogonal direction according to the distance from the end. When this is expressed in a mathematical expression, the following expression P (sin θ + sin α) = nλ (2)

Here, P is the grating pitch, is the incident angle of the illumination light, α is the diffraction angle, n is the diffraction order, and λ is the wavelength of the diffracted light, and nλ is constant even if the diffraction angle α changes. The grating pitch P is changed so that

Further, in the embossed hologram 40 in this embodiment, the surface of the embossed hologram 40 is corrected so as to correct the change in luminance due to the change in the viewing angle from the front.
The area of the central minute diffraction grating in the direction parallel to the minute diffraction grating is made smaller in the distance from the end than in the parallel direction end.

Specifically, in FIG. 8, the area of the minute diffraction grating 41C in the central portion in the vertical direction is made small and is made larger at both upper and lower ends to compensate for the decrease in the luminance of the peripheral portion due to the change in the vertical viewing angle, and The brightness of is uniform.

In this embodiment, the illumination light is a parallel ray having an incident angle θ equal to the normal line of the hologram surface and the lattice fringes from the left and right, and in FIG. It is supposed to illuminate.

In the fifth embodiment, it is possible to simultaneously correct that the line of sight deviates from the vertical direction as it goes from the front to the peripheral portion and the color shift occurs in the direction orthogonal to the diffraction grating, and the luminance decreases in the parallel direction. .

Here, in the fourth embodiment of FIG. 7, the grating pitch of the minute diffraction grating on the side far from the line light source 38 is made smaller than that on the near side, and conversely in the fifth embodiment of FIG. Although the color gap is corrected by increasing the grating pitch of the minute diffraction grating on the side farther from the light source than that on the side closer to the light source, the light source is a linear light source with a point-shaped cross section such as a fluorescent lamp as in the fourth embodiment. If so, the measures to be taken as described above conflict with each other.
It is also possible to combine two corrections and simultaneously correct both color shifts.

At this time, the incident angle of the illumination light can be selected so that it is not necessary to change the grating pitch (pitch gradient) of the minute diffraction grating as a result.

Further, in addition to the change of the grating pitch for the color misregistration correction, the color misregistration can be suppressed by giving a gradient to the grating opening area of the minute diffraction grating in the vertical direction as in the fifth embodiment of FIG. Correction and brightness homogenization can be achieved at the same time.

Next explained is the sixth embodiment of the invention shown in FIG.

The embossed hologram 44 of the sixth embodiment.
Is the one in which the minute diffraction grating 45 is arranged so that the grating fringes are orthogonal to the virtual radiation 44B extending in eight directions at equal angular intervals of 45 ° from the center 44A of the hologram surface to the upper, lower, left, right, and in the middle thereof.

The backlight for illuminating these minute diffraction gratings 45 is a ring-shaped light source 46 surrounding the embossed hologram 44. This ring-shaped light source 46
For example, a modified elliptical fluorescent lamp (such as a circle) is used. Instead of the ring-shaped light source 46, a light source (not shown) that linearly illuminates from four rectangular points (four directions) of the embossed hologram 44 may be provided.

In the case of the sixth embodiment, since the illumination light is incident on the center 44A over the entire circumference, the brightness of the peripheral portion with respect to the central portion does not decrease. However, the color shift due to the shift of the viewing angle and the color shift due to the shift of the incident angle when the ring-shaped light source 46 is not a parallel light have a gradient in the grating pitch of the minute diffraction grating 45 such that the center 44A side is rough and the outer circumferential side is fine. Can be corrected by giving

In this sixth embodiment, the embossed hologram 4 is used.
The micro-diffraction grating 45 is arranged so that its grating fringes are orthogonal to the virtual radiation 44B extending in eight directions at equal angular intervals of 45 ° from the center 44A of the four surfaces. It suffices to arrange the diffraction grating in the tangential direction of the shared concentric circles so that the grating stripes are parallel to each other. Therefore, the number of virtual radiations 44B is not limited to eight.

The ring-shaped light source 4 in the sixth embodiment of FIG.
6 is arranged so as to surround the outside of the embossed hologram 44 in a plan view, but this is for a reflective embossed hologram, and when a transmissive embossed hologram is used, the seventh embodiment shown in FIG. 10 is used. As described above, a plurality of small ring-shaped light sources 48 arranged concentrically in a state of being overlapped with the embossed hologram 44 in a plan view may be provided to improve the light quantity balance and reduce the panel thickness. In this case, the illumination range of each small ring-shaped light source 48 is the same as that of the small light sources 28A and 28B shown in FIG. 4, for example.

In each of the above-described first to fifth embodiments, the minute diffraction grating is arranged in the vertical direction (vertical stripes) so that the illumination light from the backlight is taken in from the horizontal direction. This is to prevent the indoor illumination light from above and the sunlight from the window from being diffracted.

As described above, if the direction of the minute diffraction grating is in the form of vertical stripes, the disturbance light can be blocked. However, as in the eighth embodiment shown in FIG. By making the direction (horizontal stripe), the interior illumination light may be positively used and the backlight may be omitted.

In the eighth embodiment, the reflection type embossed hologram 50 is arranged on the back side of the liquid crystal panel 52, and a daylighting hood 54 for guiding the room illumination as parallel light to the front surface of the liquid crystal panel 52 is provided.

A louver 54A is provided in the daylighting hood 54 to collimate the room illumination light incident from above at various angles. Reference numeral 56 in the figure denotes a light source for auxiliary illumination provided in the daylighting hood 54. The light source 56 supplementally illuminates the liquid crystal panel 52 when the room illumination is insufficient.

The first to eighth embodiments are all related to the color liquid crystal panel, but the present invention is not limited to this, and if necessary, using a minute diffraction grating, If the diffracted light is configured to pass through the liquid crystal panel, it can be applied to a monochrome liquid crystal display device.

For example, correction of uneven coloring due to deviation of the incident angle of illumination light as in the fourth embodiment of FIG. 7 and uneven coloring due to deviation of viewing angle and reduction of luminance as in the fifth embodiment of FIG. The correction of is also applied to the elimination of the uneven backlight illumination of the monochrome liquid crystal display device as it is.

Although the illumination light source of each of the above-mentioned embodiments has a fixed illumination angle with respect to the surface of the diffraction grating, the present invention is not limited to this, and as shown in FIG. 12, for example. The light source 6 provided with the light source illumination angle fine adjustment mechanism 60
2, the illumination angle of the embossed hologram 64 may be variable. Reference numeral 66 in FIG. 12 indicates a light amount adjustment volume.

According to this light source 62, since the illumination angle can be finely adjusted, there is an advantage that the hue of the diffracted light can be finely adjusted.

[0122]

Since the present invention is constructed as described above,
Compared to the case of using a color filter, there is no light attenuation and a bright screen can be obtained, productivity and yield are improved, cost is reduced, and even in the case of a large-sized liquid crystal panel, it is easily manufactured. It has an excellent effect of being able to.

[Brief description of drawings]

FIG. 1 is an exploded sectional view showing a color liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing the arrangement of minute diffraction gratings of the embossed hologram and the relationship with the illumination light source in the first embodiment.

FIG. 3 is an enlarged cross-sectional view showing a reflective embolus hologram in the first embodiment.

FIG. 4 is an enlarged cross-sectional view showing a main part of a color liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is an enlarged sectional view showing a transmission type embossed hologram of the second embodiment.

FIG. 6 is an enlarged sectional view showing an embossed hologram according to a third embodiment of the present invention.

FIG. 7 is an optical layout diagram showing a relationship between illumination light and a diffraction grating pitch in an embossed hologram according to a fourth embodiment of the present invention.

FIG. 8 is a schematic plan view showing an embossed hologram according to a fifth embodiment of the present invention.

FIG. 9 is a schematic plan view showing an embossed hologram and an illumination light source therefor according to a sixth embodiment of the present invention.

FIG. 10 is a schematic plan view showing an embossed hologram and an illumination light source therefor according to a seventh embodiment of the present invention.

FIG. 11 is a schematic sectional view showing a liquid crystal display device according to an eighth embodiment of the present invention.

FIG. 12 is a schematic cross-sectional view showing another aspect of the light source of the illumination light used in each of the embodiments.

[Explanation of symbols]

10, 24 ... Color liquid crystal display device 12, 52 ... Liquid crystal panel 12A, 12B, 18, 30 ... Glass substrate 12C ... Transparent electrode 12F ... Liquid crystal 14, 28 ... Backlight 14A, 14B, 38 ... Line light source 16 ... For color display Means 20, 50 ... Reflective embossed hologram 20A ... Embossed hologram film 20B ... Reflective film 22A, 22C, 34A to 34C, 41, 41A to 41
C, 45 ... Micro-diffraction grating 26, 32 ... Transmissive embossed hologram 28A, 28B ... Small light source 36, 40, 44 ... Embossed hologram 44A ... Center 44B ... Virtual radiation 46 ... Ring light source 49 ... Small ring light source 54 ... Daylight hood

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[Procedure amendment]

[Submission date] March 23, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0099

[Correction method] Change

[Correction content]

Specifically, in the embossed hologram 40, the central portion of the surface of the embossed hologram 40 in the direction orthogonal to the minute diffraction grating (left and right direction in FIG. 8) so as to correct the color shift due to the change in the viewing angle from the front. The grating pitch of the minute diffraction grating 41A on the side is made larger than the grating pitch of the minute diffraction gratings 41B at both ends in the orthogonal direction according to the distance from the end. This can be expressed as
become that way. P (sin θ + sin α) = nλ (2)

Claims (30)

[Claims] 1. A liquid crystal is held between two substrates each having a display electrode for each display pixel, color display means corresponding to each display pixel is provided outside one substrate, and a voltage between counter electrodes is set. In a liquid crystal display device for performing color display by controlling and selectively changing the light transmission amount of illumination light in a display unit, the color display means forms diffracted light of a color to be displayed by a corresponding display pixel. Thus, the liquid crystal display device is characterized in that the diffraction grating medium is formed by successively patterning at least three kinds of minute diffraction gratings having different characteristics by changing the pitch of the grating stripes. 2. The light source of the illumination light according to claim 1,
A unidirectional illumination device in which only one illuminating light is incident on one minute diffraction grating in the diffraction grating medium. 3. The liquid crystal display device according to claim 2, wherein the light source comprises a plurality of small light sources each illuminating different regions of the diffraction grating medium at the same incident angle. 4. The light source according to claim 3, wherein the plurality of small light sources are symmetrical with respect to a normal line of the diffraction grating medium surface and a grating fringe.
A liquid crystal display device, characterized in that the liquid crystal display device is arranged so as to irradiate from one direction at an equal angle. 5. The second-order diffracted light emitted by wrapping around in the direction of the adjacent minute diffraction grating with respect to the grating pitch of the minute diffraction grating is formed by the adjacent minute diffraction grating. A liquid crystal display device characterized by having the same color as the first-order diffracted light. 6. A liquid crystal display device according to claim 1, wherein the illumination light source is a linear parallel white light source. 7. The minute light on the side far from the light source of the illumination light according to any one of claims 1 to 6, so as to correct the color shift due to the deviation of the incident angle of the illumination light for one illumination light. A liquid crystal display device, wherein the grating pitch of the diffraction grating is smaller than the grating pitch of the minute diffraction grating on the near side according to the distance from the light source. 8. The diffraction grating medium according to any one of claims 1 to 7 in a direction orthogonal to the minute diffraction grating in the diffraction grating medium so as to correct a color shift due to a change in viewing angle from the front side of the diffraction grating medium. A liquid crystal display device, characterized in that the grating pitch of the minute diffraction grating on the central side is made larger than the grating pitch of the minute diffraction grating at the end in the orthogonal direction according to the distance from the end. 9. The pair of light sources according to claim 1, wherein the light source is a pair of light sources that illuminate a region of a diffraction grating medium, which is bisected in a direction orthogonal to the minute diffraction grating, from different directions at equal incident angles. A liquid crystal display device characterized by the above. 10. The microdiffraction according to claim 1, wherein a color shift due to a shift of an incident angle of the illumination light and a color shift due to a change of a viewing angle from the front of the diffraction grating medium are corrected. A liquid crystal display device, wherein the grating pitch of the grating is changed according to the distance from the illumination light and the distance from the center of the diffraction grating medium. 11. The method according to any one of claims 1 to 10,
In order to correct the luminance change due to the change of the viewing angle from the front of the diffraction grating medium, the area of the fine diffraction grating in the central portion of the diffraction grating medium in the direction parallel to the fine diffraction grating is set to the end in the parallel direction. A liquid crystal display device characterized in that it is made smaller according to the distance from the end than in the part. 12. The method according to any one of claims 1 to 11,
The liquid crystal is characterized in that the minute diffraction grating is arranged such that its grating stripes are in a vertical direction, and the light source of the illumination light is arranged so that the illumination light is incident in a direction orthogonal to the grating stripes of the minute diffraction grating. Display device. 13. The micro-diffraction grating according to claim 1, wherein the grating fringes are arranged in a direction parallel to a tangent line of a virtual concentric circle centered on the screen center of the display unit, and the illumination light source is the light source. A liquid crystal display device characterized by being a ring-shaped light source centered on the center of the screen. 14. The micro diffraction grating according to claim 13, wherein the grating fringes are arranged so as to be orthogonal to virtual radiation extending in eight directions from the center of the screen in the vertical, horizontal, and intermediate directions. Characteristic liquid crystal display device. 15. The diffraction grating medium according to claim 13 or 14, wherein the diffraction grating medium is transmissive, and the light source of the illumination light is a plurality of concentric ring-shaped white light sources that illuminate the diffraction grating medium from the back surface. Liquid crystal display device characterized by. 16. The light source of the illumination light according to claim 1, is equal from two directions which are symmetric with respect to a normal line of the diffraction grating medium surface and a grating fringe with respect to each minute diffraction grating of the diffraction grating medium. A liquid crystal display device, which is bidirectional illumination that is incident at an angle and illuminates by superimposing each minute diffraction grating. 17. The method according to any one of claims 1 to 16,
A liquid crystal display device, wherein the diffraction grating medium is a transmissive type, and the illumination light illuminates the diffraction grating medium from the back side to serve as a backlight of a display pixel. 18. The backlight of a display pixel according to claim 1, wherein the diffraction grating medium is of a reflection type, and the illumination light illuminates the diffraction grating medium from its surface. A liquid crystal display device characterized by the above. 19. A liquid crystal is held between two substrates each having a display electrode for each display pixel, and a voltage between opposing electrodes is controlled to selectively change a light transmission amount of illumination light in a display portion. Thus, in a liquid crystal display device which performs monochrome display of an image, a diffraction grating medium patterned with a minute diffraction grating that forms diffracted light having a wavelength equal to the light to be displayed by the display pixel is provided outside the one substrate, and A liquid crystal display device characterized in that a grating pitch of a diffraction grating is changed according to a position. 20. The grating pitch of the minute diffraction grating on the side far from the illumination light is corrected so as to correct the brightness shift due to the deviation of the incident angle of the illumination light for one illumination light. A liquid crystal display device characterized by being made smaller than a grating pitch of a minute diffraction grating on the near side according to a distance. 21. The center side of the diffraction grating medium in a direction orthogonal to the minute diffraction grating so as to correct a color shift due to a change in a viewing angle from the front side of the diffraction grating medium. The liquid crystal display device, wherein the grating pitch of the minute diffraction grating is larger than the grating pitch of the minute diffraction grating at the end in the orthogonal direction according to the distance from the end. 22. The center of the diffraction grating medium in a direction parallel to the minute diffraction grating, according to claim 19, 20 or 21, so as to correct a change in luminance due to a change in viewing angle from the front of the diffraction grating medium. The liquid crystal display device is characterized in that the area of the minute diffraction grating of the portion is made smaller in accordance with the distance from the end portion than at the end portion in the parallel direction. 23. The micro-diffraction grating according to any one of claims 19 to 22, wherein the minute diffraction grating is arranged such that its grating stripes are parallel to a tangent line of a virtual concentric circle centered on the screen center of the display section. A liquid crystal display device characterized in that a light source of light is a ring-shaped light source centered on the center of the screen. 24. A liquid crystal is held between two substrates each having a display electrode for each display pixel, and diffracted light of a color to be displayed by a corresponding display pixel is formed outside one substrate. A fine diffraction grating medium formed by patterning at least three kinds of diffraction gratings having different characteristics by changing the pitch of the grating stripes is arranged for each display pixel, and the voltage between the display electrodes facing each other is controlled to control the display electrode. A liquid crystal display method in which color display is performed by selectively changing the light transmission amount of the liquid crystal in between. 25. A liquid crystal display device, comprising a diffraction grating medium composed of a minute diffraction grating arranged so as to form diffracted light in a display pixel direction corresponding to each display pixel, each minute diffraction grating comprising: A diffraction grating medium for a liquid crystal display device, which is patterned into three or more types so that corresponding display pixels form diffracted light of at least three colors to be displayed. 26. The diffraction grating medium for a liquid crystal display device according to claim 25, wherein the minute diffraction grating is duplicated by an embossing method. 27. The second-order diffracted light that emerges by wrapping around in the direction of an adjacent minute diffraction grating with respect to the grating pitch of the minute diffraction grating according to claim 25 or 26, is formed by the adjacent minute diffraction grating. A diffraction grating medium for a liquid crystal display device, which has the same color as the folding light. 28. The center of the diffraction grating medium in the direction orthogonal to the minute diffraction grating so as to correct a color shift due to a change in the viewing angle from the front of the diffraction grating medium according to claim 25, 26 or 27. A diffraction grating medium for a liquid crystal display device, characterized in that the grating pitch of the minute diffraction grating on the side is made larger than the grating pitch of the minute diffraction grating at the end in the orthogonal direction according to the distance from the end. 29. The minute diffraction grating according to claim 25, so as to correct the color deviation due to the deviation of the incident angle of the illumination light and the color deviation due to the change of the viewing angle from the front of the diffraction grating medium. The diffraction grating medium for a liquid crystal display device, wherein the grating pitch is changed according to the distance from the illumination light and the distance from the center of the diffraction grating medium. 30. The diffraction grating medium according to any one of claims 25 to 29, in a direction parallel to the minute diffraction grating in the diffraction grating medium so as to correct a change in luminance due to a change in viewing angle from the front side. A diffraction grating medium for a liquid crystal display device, characterized in that the area of the minute diffraction grating in the central portion is made smaller according to the distance from the end portion than at the end portion in the parallel direction.