RU2158434C1 - Display - Google Patents

Abstract

FIELD: optical systems, which use holograms as optical members. SUBSTANCE: device has flat liquid-crystal panel, which has multiple liquid-crystal cells, which are located between back and front surfaces of parallel . In addition device has flat optical waveguide, which is connected to back side of liquid-crystal panel to produce integral assembly, hologram, which is designed as integral to optical waveguide, and light source, which is optically connected to optical waveguide. Back side of liquid-crystal panel and optical waveguide are separated by means of space, which is filled with transparent material, which refraction index is less than refraction index of material of optical waveguide. Said insertion material is designed as adhesion for connection of liquid-crystal panel and optical waveguide into integral assembly. EFFECT: improved quality of color image, monolithic display design with increased stability against mechanical load and protection against dirt inside. 11 cl, 5 dwg

Description

 The invention relates to optical systems using holograms as optical elements, and more particularly to liquid crystal displays using holograms to form a color image.

BACKGROUND OF THE INVENTION
Displays are known comprising a liquid crystal panel having a front surface, a back surface and a plurality of liquid crystal cells located between the front and back surfaces of the panel, means for illuminating the liquid crystal cells from the back surface of the liquid crystal panel, including an optical waveguide and a light source optically coupled to optical waveguide, and a hologram located behind the back surface of the panel between it and the optical waveguide and intended for dividing the holographic white light into red, green, and blue components aimed at the liquid crystal cells (US-A N 5506701, 1996, class IPC (6) G 02 B 5/32, class NKI 359/15; 359/22 ; 359/53, priority JP-A NN 5-012170; 5-014572; 5-097517, 1993).

 In this display (Figs. 14-16 and their description), the optical waveguide is located at a distance from the hologram, and the means for illuminating the liquid crystal cells is provided with a mask located between the optical waveguide and the hologram and having a plurality of holes located opposite the respective liquid crystal cells of the panel and microlenses located opposite each opening of the mask and designed to convert diverging rays of light coming out of the holes of the mask into parallel rays directed to the hologram.

 In such a display, when it is operated through the hologram, liquid crystal cells of the panel, in addition to the color components, pass partially undiffracted light, which degrades the image quality. In addition, for the proper functioning of such a display, it is necessary to orient the mask holes, microlenses, corresponding sections of the hologram and liquid crystal cells of the panel in a very precise way, which can cause certain problems in the manufacture of the display.

SUMMARY OF THE INVENTION
The basis of this invention was the task of creating a display with high quality created by him color image with a relatively simple design and manufacturing technology of the display itself.

 This problem is solved in that in a display containing a liquid crystal panel having a front surface, a rear surface substantially equidistant to said front surface and located at a distance from it, and a plurality of liquid crystal cells located between said front and back surfaces, a hologram located behind said back surface of said liquid crystal panel, and means for illuminating said liquid crystal cells from said back surface of the decree a liquid crystal panel including an optical waveguide having a first side surface substantially equidistant to said rear surface of said liquid crystal panel, and a second side surface substantially equidistant to said first side surface and located at a distance from it, and a light source, optically coupled to said optical waveguide, according to the invention, a hologram is made integrally with said optical waveguide, and said liquid crystal panel and said optical waveguide are interconnected into a single unit.

 This embodiment of the display improves the quality of the color image it creates - brightness, clarity and color reproduction due to the reduction of radiation losses between the light source and the liquid crystal cells, due to the reduction of chromatic distortions when dividing white light into color components and due to the possibility of increasing the accuracy of hologram orientation relative to other display elements , and also simplifies the display by eliminating a number of elements from it.

 The hologram can be made on the first specified side surface of the optical waveguide or on the second specified side surface of the optical waveguide, or on both side surfaces of the optical waveguide, or inside the optical waveguide equidistant to its side surfaces.

 Between the back surface of the liquid crystal panel and the first side surface, a gap can be made filled with an optically transparent material having a refractive index lower than the refractive index of the material of the optical waveguide.

 It is advisable that the size of the specified gap was less than the distance between the side surfaces of the optical waveguide.

 It is advisable that the optically transparent material is an adhesive material connecting the liquid crystal panel and the optical waveguide in a single unit.

 This embodiment provides a monolithic display with increased resistance to mechanical stress and protected from internal pollution.

 The light source can be polychromatic and can be equipped with three emitters of red, green and blue, respectively.

 It is advisable to each of these emitters to perform in the form of an LED.

 This embodiment improves the accuracy of color reproduction and eliminates chromatic distortion by separately controlling the radiation intensity of each emitter.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-sectional view of a display in accordance with the invention (aspect ratio shown conditionally without respecting proportions).

 FIG. 2 shows place A in FIG. 1 on an enlarged scale (the aspect ratio is shown conditionally without respecting the proportions).

 FIG. 3 shows another embodiment of location A in FIG. 1 on an enlarged scale (the aspect ratio is shown conditionally without proportions).

 FIG. 4 shows another embodiment of location A in FIG. 1 on an enlarged scale (the aspect ratio is shown conditionally without proportions).

 FIG. 5 shows another embodiment of location A in FIG. 1 on an enlarged scale (the aspect ratio is shown conditionally without proportions).

DETAILED DESCRIPTION OF BEST MODES FOR CARRYING OUT THE INVENTION
As shown in FIG. 1, the display comprises a liquid crystal panel 1, an optical waveguide 2, with which the hologram 3a (Fig. 1 - 2) (3b, 3c - 3d, 3f, Fig. 3, 4, 5), and a light source 4 (Fig. 1), optically coupled to an optical waveguide 2. The liquid crystal panel 1 (Figs. 1 to 5) is a plate having a front surface 5, a rear surface 6 substantially equidistant to the front surface 5 and spaced apart from it, and a plurality of liquid crystal cells 7 ', 7'',7''', located between the front surface 5 and the back surface 6 (in FIG. 1 - 5 one group of three cells is shown and marked, the remaining cells are not shown and are not marked). The front surface 5 and the back surface 6 of the liquid crystal panel 1 may be flat, as shown in FIG. 1 - 5, or may be non-planar (not shown in the drawings). The liquid crystal cells 7 ', 7'',7''' are arranged in parallel rows in the first and second mutually intersecting, mostly at right angles, directions (not shown in the drawings) in such a way that they form a matrix between the front surface 5 and the back surface 6 of the liquid crystal panels 1. In the liquid crystal panel 1, a first row of parallel electrodes 8 is made (an electrode is shown and marked in Figs. 1-5). The electrodes 8 are aligned with parallel rows of liquid crystal cells 7 ′, 7 ″, 7 ″ ”extending in the first direction. A second row of parallel electrodes 9 is also made in the liquid crystal panel 1, located mainly at right angles to the electrodes 8 (in FIGS. 1-5, one electrode 9 is shown and marked, conventionally passing in the same direction as electrode 8, although in reality the electrodes 8, 9 are made crossing in two different planes). The electrodes 9 are aligned with parallel rows of liquid crystal cells 7 ', 7'',7''' extending in the second direction and intersecting with parallel rows extending in the first direction, so that the electrodes 8, 9 form a grid aligned with the rows of liquid crystal cells 7 ', 7``, 7'''. The electrodes 8, 9 are electrically connected to the control unit 10 (Fig. 1). The optical waveguide 2 and the light source 4 form the daylight illumination of the liquid crystal cells 7 ', 7'',7''' from the back surface 6 of the liquid crystal panel 1.

 The optical waveguide 2 (Fig. 1) is a plate of optically transparent material having a polished first side surface 11, an equidistant back surface 6 of the liquid crystal panel 1, a polished second side surface 12, equidistant to the first side surface 11 and located at a distance from it ( Fig. 2 - 5), and opposite ends 13, 14 (Fig. 1). Between the back surface 6 of the liquid crystal panel 1 and the first side surface 11 of the optical waveguide 2 (FIGS. 2-5), a gap 15 is made, the value of b of which is less than the distance a. The gap 15 is filled with an optically transparent material (not indicated) having a refractive index lower than the refractive index of the material of the optical waveguide 2. The optically transparent material filling the gap 15 is an adhesive material connecting the liquid crystal panel 1 and the optical waveguide 2 into a single assembly, so that The display is more resistant to mechanical stress and is protected from contamination.

 The light source 4 (FIG. 1) may be equipped with an incandescent lamp (not shown in the drawings), a fluorescent lamp (not shown in the drawings), or, as shown in FIG. 1, - three light emitters - LEDs 16, 17, 18, respectively, red, green and blue. Such a light source is polychromatic. Between the light source 4 and the end face 13 of the optical waveguide 2, an adapter 19 of an optically transparent material is installed.

 The hologram 3a (Fig. 1 - 2) (3b, 3c - 3d, 3f, Fig. 3, 4, 5) is located behind the back surface 6 of the liquid crystal panel 1. In one embodiment of the display (Fig. 2), the hologram 3a is made in part the first side surface 11 of the optical waveguide 2. In another embodiment of the display (Fig. 3), the hologram 3b is made in part of the second side surface 12 of the optical waveguide 2. In another embodiment of the display (Fig. 4), the hologram 3c - 3d is made as in part the first side surface 11, and on the part of the second side surface 12 of the optical wave oestrus 2. In another embodiment, the display (Fig. 5) 3f hologram is formed inside the optical waveguide 2 equidistantly its first side surface 11 and the second side surface 12 and at a distance from them. Each hologram 3a, 3b, 3c, 3d, 3f has an inhomogeneous diffraction efficiency, increasing from the end face 13 to the end face 14 of the optical waveguide 2.

 The light source 4 (Fig. 1) has a separate voltage regulation device (not shown) supplied to the LEDs 16, 17, 18.

 The described display operates as follows.

 When voltage is applied to the LEDs 16, 17, 18, the latter emit red, green, and blue colors, respectively. White light obtained by mixing red, green and blue light through an adapter 19 enters the optical waveguide 2 through its end 13. Due to the separate regulation of the voltage supplied to the LEDs 16, 17, 18, i.e. separate regulation of the radiation intensity of each LED, it is possible to increase the accuracy of color rendering settings and eliminate chromatic distortion of the image created by the display.

 Due to the effect of total internal reflection from the side surfaces 11, 12 of the optical waveguide 2, white light, as shown in FIG. 2 - 5 by dash-dotted lines with arrows (not marked), propagates in the optical waveguide 2 and diffracts on the hologram 3a, 3b, 3c - 3d or 3f. Diffracted light exits the optical waveguide 2, as shown in FIG. 2 to 5 by dashed lines with arrows (not indicated), through its lateral surface 11 and the gap 15 in the direction of the cells 7 ', 7' '. 7 '' 'of the liquid crystal panel 1 from the side of its back surface 6. Light that is not diffracted on the hologram 3a, 3b, 3c - 3d or 3f remains inside the waveguide 2 and, repeatedly reflected from the side surfaces 11, 12, again enters other areas holograms 3a, 3b, 3c — 3d or 3f, diffracts again and leaves the waveguide 2 in the direction of the liquid crystal panel 1.

 Thus, due to the fact that the hologram 3a, 3b, 3c - 3d, 3f is made integrally with the optical waveguide 2, the radiation losses are reduced and, in fact, the power of the light entering the optical waveguide 2 is completely utilized (with the exception of losses in the material the optical waveguide itself 2), for illumination of the liquid crystal panel 1.

 The hologram 3a, 3b, 3c - 3d, 3f is recorded in such a way that it generates red, green and blue beams directed to the respective cells 7 ', 7' ', 7' '' of the liquid crystal panel 1, so that in each cell 7 ' , 7``, 7 '' 'receives light from one of the indicated colors without chromatic distortion.

 Due to the fact that the liquid crystal panel 1 and the optical waveguide 2 are connected to each other in a single node, and the hologram 3a, 3b, 3c - 3d, 3f is embedded with the optical waveguide 2, the accuracy of orientation and focusing of these light rays with respect to the corresponding cells 7 'is increased, 7``, 7 '' 'LCD panel 1.

 Due to the inhomogeneous diffraction efficiency of each hologram 3a, 3b, 3c - 3d, 3f, increasing from end 13 to end 14 of the optical waveguide 2, uniform illumination of all cells 7 ', 7' ', 7' '' of the liquid crystal panel 1 is ensured.

 The control unit 10 supplies voltage to the specified electrodes 8, 9 and, thereby, changes the transparency of the cells 7 ', 7' ', 7' '' of the liquid crystal panel 1. In this case, each cell 7 ', 7' ', 7' '' in transmits a beam of one of the indicated colors in a transparent state, and a color image is formed on the front surface 5 of the liquid crystal panel 1, having a high quality - brightness, sharpness and color reproduction, including white.

INDUSTRIAL APPLICABILITY
The described display can be used in computer monitors, in television receivers, in various devices, in demo screens and displays.

Claims (11)

 1. A display comprising a liquid crystal panel having a front surface, a back surface substantially equidistant to said front surface and located at a distance from it, and a plurality of liquid crystal cells located between said front and back surfaces, a hologram located behind said back surface of said liquid crystal panels, and means for illuminating said liquid crystal cells from the side of said back surface of said liquid crystal a panel including an optical waveguide having a first side surface substantially equidistant to said rear surface of said liquid crystal panel and a second side surface substantially equidistant to said first side surface and spaced apart from it, and a light source optically coupled with said optical waveguide, characterized in that said hologram is made integrally with said optical waveguide and said liquid crystal panel and said optical The waveguide is interconnected into a single unit.  2. The display according to claim 1, wherein said hologram is made at least on a portion of a first specified side surface of said optical waveguide.  3. The display according to claim 1, in which the specified hologram is made at least in part of the second specified side surface of the specified optical waveguide.  4. The display according to claim 1, wherein said hologram is made at least on a part of a first specified side surface of said optical waveguide and at least on a part of a second specified side surface of said optical waveguide.  5. The display according to claim 1, in which the hologram is made inside the specified optical waveguide, essentially equidistant to the first specified side surface and the second specified side surface and at a distance from the specified first and second side surfaces.  6. The display according to any one of claims 1 to 5, in which a gap is filled between the indicated back surface of the indicated liquid crystal panel and the indicated first side surface of the specified optical waveguide, having an optically transparent material having a refractive index lower than the refractive index of the material of the specified optical waveguide.  7. The display of claim 6, wherein said gap is smaller than a distance between said first side surface of said optical waveguide and said second side surface of said optical waveguide.  8. The display of claim 6, wherein said optically transparent material is an adhesive material connecting said liquid crystal panel and said optical waveguide into a single assembly.  9. The display according to any one of claims 1 to 8, in which the specified light source is polychromatic.  10. The display of claim 9, wherein said polychromatic light source is provided with at least three emitters of red, green, and blue, respectively.  11. The display of claim 10, in which each of these emitters is made in the form of an LED.

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