JPH0917357A - Display device - Google Patents

Abstract

PURPOSE: To compensate a performance limit in spatial resolution and the image screen size, and attain size reduction, high definition and a large image screen by installing an optical system composed of plural light waveguide passages on a display image screen of a display device. CONSTITUTION: The respective display light of respective picture elements 3 of a display image screen of a display device 1 are made incident on at least a single light waveguide passage of the display image screen constituted in a reduced optical system 2, and are introduced to respective picture elements 4 on the display image screen after the size is reduced, and spatial resolution is improved. In that case, when the light waveguide passages are used, an increase in a depth of the whole display device is sufficiently restrained. Since the image screen size is reduced, brightness is also increased. When a combination of the respective light waveguide passages and the respective picture elements 3 is already known, a wave length characteristic can be optimized as a display color of the picture elements, and a color reproducing range of the display device can be expanded in a color space on which both aspects of a chromaticity aspect and the brightness direction are considered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying images, characters and figures, and more particularly to a display device in which image quality such as resolution and brightness is improved by converting the display size of the display device.

[0002]

2. Description of the Related Art Recently, there is a great demand for miniaturization and high definition of display devices such as computer graphic displays and televisions, and the thinning and high resolution of the display devices used for them have been advanced. As a conventional example of a flat-panel type display device that responds to this, Japanese Patent Laid-Open No. 2-301
FIG. 3 shows a part of the structure of the plasma display panel (hereinafter referred to as PDP) disclosed in Japanese Patent No. 934. P shown in FIG.
DP is a front glass plate 8 and a rear glass plate 9 on the display screen side.
The structure is such that the light emission due to the discharge in the space sandwiched between is used for display. Insulating partition wall 10 on the front glass plate 8
The scanning electrodes 12 and 13 covered with the dielectric layer 11 on the back glass plate 9 and the address electrodes 14 on the dielectric layer 11 control the discharge position and the number of discharges to realize the display function. There is. Since the PDP can be manufactured using a thick film printing process, it is applied to a large-screen display device as a flat type such as a 20 inch to 40 inch class.

[0003]

However, since the PDP shown in FIG. 3 as a conventional example uses a thick film printing process, the distance between the insulating partition walls 10 corresponding to the pixel size is several hundreds of μm.
It became larger than the above, and the spatial resolution of the display was kept low. In addition, a flat panel type display device that can have a higher spatial resolution than a PDP is a liquid crystal panel (hereinafter referred to as L
Although a CD panel) is known, it is difficult to make a screen larger than 20 inches. On the other hand, the cathode ray tube which is most popular as a display device has obtained a higher resolution, but when the screen size exceeds 17 inches, the depth of the display device becomes large, and the use on an office desk remains unsatisfactory.

An object of the present invention is to compensate for the performance limit of a display device in terms of spatial resolution and screen size, and to miniaturize and increase the definition of the display device.

[0005]

The object of the present invention is achieved by mounting a reduction optical system or a magnification optical system composed of a plurality of optical waveguides on a display screen of a display device of a display device.

[0006]

In the above-mentioned means of the present invention, the reduction optical system or the expansion optical system composed of a plurality of optical waveguides has a shorter optical path length than a lens optical system utilizing the refractive index ratio of the boundary surface in the optical path. , It is possible to control the path of the display light of the display device. Therefore, by mounting the reduction optical system or the enlargement optical system of the present invention on the display screen of the display device of the display device, the display size can be converted while suppressing an increase in the depth of the display device. In addition, the image quality such as spatial resolution and brightness can be improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing an embodiment in which the characteristics of the display device of the present invention are best shown.
It was attached to the display screen of. In FIG. 1, the display light of each pixel 3 on the display screen of the display device 1 is converted into the reduction optical system 2
The light is incident on at least one optical waveguide configured in the above and is guided to each pixel 4 on the display screen after size reduction, thereby improving the spatial resolution. At this time, the use of the optical waveguide can sufficiently suppress the increase in the depth of the display device as a whole, so that the possibility of being wall-mounted and the feature of the display device 1 that the display device 1 is small can be maintained. . Furthermore, it is possible to expect an increase in brightness by reducing the screen size. As the material of the reduction optical system 2, a resin such as glass, acrylic, or plastic which is transparent or has a wavelength characteristic suitable for attenuation of transmitted light can be considered first. If the combination of each optical waveguide and each pixel 3 is known, the wavelength characteristic can be optimized for the display color of the pixel, and the color reproduction range of the display device is a color space considering both the chromaticity plane and the luminance direction. Can be expanded with. Even when the display device 1 is monochromatic, it is possible to improve the display contrast by compensating for the influence of ambient light of the display device. As a method of manufacturing the reduction optical system 2, casting using a mold or shaving is first considered. However, in order to realize the fine processing required to improve the spatial resolution, for example, it is possible to use a stereolithography method that can directly make a prototype using CAD data. The stereolithography is a processing method of scanning a laser to cure and stack a photocurable resin into a layer to form a high-precision three-dimensional structure. Currently, the materials for modeling are roughly classified into epoxy type, urethane acrylate type, and epoxy acrylate type, but if a reversed mold is made based on the obtained three-dimensional structure, a glass structure or a reverse mold can be obtained. can get. By using the stereolithography method, a highly accurate optical system can be obtained at low cost. If the reduction optical system of the present invention is used, a flat panel cathode ray tube or the like can be applied as a display device. The shape of each pixel 3 on the display screen of the display device 1 is not limited to a stripe shape, but may be an arbitrary shape such as a dot shape, and light from a plurality of pixels 3 may be incident on the optical waveguide. For example, the three primary colors of red, blue and green may be incident on one optical waveguide. In fact, color stripes and color dots of a plurality of colors are also emitted on the scanning line of the color CRT, but since the emission of each color is accurately controlled, it does not have any adverse effect on the display color. Therefore, the cross-sectional shape of the incident surface of the optical waveguide may be arbitrary, and at the same time, it may be the incident area for taking in the display light of the plurality of pixels 3 of the display screen of the display device 1, or conversely The incident area may be so small that only a part of the display light is taken in.

FIG. 2 shows a sectional view of the first embodiment of the reduction optical system 2. In FIG. 2, an optical waveguide is obtained by forming a plurality of wedge-shaped gaps 5 on the display device 1 side of the reduction optical system 2. The wedge-shaped gaps 5 are narrowed and extend to the vicinity of the display screen 6 after the size reduction. On the display screen 6, the wedge-shaped gaps 5 are interrupted and the respective optical waveguides are integrated, or The emission surface of each optical waveguide is joined on a plane. In FIG. 2, each wedge-shaped gap 5 narrows and extends to the vicinity of the display screen 6, but the wedge-shaped gap may conversely narrow and extend to the vicinity of the display device 1. Display device 1
By narrowing in the vicinity of, the light collection rate on each optical waveguide is improved and the brightness on the size conversion display screen is increased. This effect is effective not only in the reduction optical system 2 but also in the expansion optical system. Even when the gap of each optical waveguide on the side of the display device 1 is narrowed, the gap may remain on the display screen 6 side of each optical waveguide, or the gap is interrupted so that each optical waveguide has an integrated structure. May be. A gap is left on the display screen 6 side of each optical waveguide, and the gap is displayed on the display screen 6 side.
When the optical system is formed to have a constant width or a widening shape on the side, the optical system can be manufactured at low cost using a mold. Further, it is not always necessary to provide a gap between the optical waveguides. For example, the region corresponding to the gap may be filled with a material having a refractive index lower than that of the constituent material of the optical path in the optical waveguide. By eliminating the gap in this way, while improving the mechanical strength of the optical system,
The light collection efficiency of the display light of the display device 1 can be maximized. Furthermore, by suppressing the reflectance by coating the entrance surface of this optical system with an interference film or the like, the light collection rate can be almost 100%. Further, the wavelength selective transmission effect of the coating suppresses re-reflection on the display device 1 side of the external light that enters from the emission surface of each optical waveguide, and thus further improvement in display contrast can be expected. The emission surface of each optical waveguide does not need to be smooth, and may be a diffusion surface with irregularities formed to expand the viewing angle of the display device. On the contrary, by separating each optical waveguide having a smooth emitting surface to a position very close to the display screen 6 or forming a concave-convex lens on the emitting surface of each optical waveguide, it is possible for anyone other than the user. It is also possible to provide a narrow viewing angle display device in which the display contents cannot be seen. Further, the incident light on the optical waveguide formed by each wedge-shaped gap 5 has an angle of incidence with the boundary surface with the wedge-shaped gap 5,
If the angle is less than the critical angle in each part of the optical waveguide, it is guided to the display screen 6 by total reflection. However, when the incident angle exceeds the critical angle in an attempt to reduce the depth of the reduction optical system 2 to the maximum, the incident light leaks, and there is a concern that it may have an adverse effect due to leakage into other optical waveguides. In that case,
The surface of the wedge-shaped gap 5 is painted, plated, sputtered, or the like, or the wedge-shaped gap 5
It is necessary to give a reflection characteristic to at least the inner surface of the optical waveguide by filling the material with a reflecting agent. Furthermore, the reduction optical system of the present invention can be made lightweight by forming the optical waveguide while leaving only these reflecting surfaces and reflecting agents.

Another embodiment of the reduction optical system is shown in FIG. In FIG. 4, the reduction optical system 15 includes a plurality of optical fibers 16
It consists of. Optical fiber 16 used in the present invention
The material of is not necessarily glass used for optical communication and the like, and may be resin such as plastic. Furthermore, the optical fiber 16 can be provided with wavelength characteristics for increasing the color purity of incident light. Moreover, since the flexibility of the fiber is large, the depth of the reduction optical system 15 can be significantly shortened. The reduction optical system 15 of the present invention only needs to bundle a plurality of optical fibers 16 on each of the incident surface and the emission surface. Therefore, the arrangement between the entrance surface and the exit surface of the optical fiber 16 is arbitrary. Furthermore, the cross-sectional shape of the optical fiber 16 does not necessarily have to be circular, and in particular, the incident surface and the exit surface have any shape such as a square with rounded corners according to the display device or the pixel shape of the display screen after size reduction. Is possible. The cross-sectional shape between the entrance surface and the exit surface of the optical fiber 16 can be any shape in consideration of the overall structure of the optical system and the fiber material. However, when the optical fiber 16 is bent at an acute angle, the refractive index of the fiber material cannot be made sufficiently high, or the refractive index distribution in the fiber cannot be controlled sufficiently, the same as the optical waveguide shown in FIG. It is necessary to apply coating, plating, sputtering, etc. around the optical fiber 16. FIG. 5 shows the reduction optical system 1.
5 shows a sectional view of a second embodiment of No. 5; In FIG. 5, the diameter of the optical fiber 16 increases toward the display screen side of the display device 1, but the diameter may be constant. Further, similarly to the reduction optical system 2 shown in FIG. 2, the emitting surface of the optical fiber 16 can be made uneven so as to have diffusibility. The present embodiment has other characteristics similar to those of the reduction optical system 2 shown in FIG. 2, such as increased brightness.

Finally, FIG. 6 shows an embodiment of the magnifying optical system of the present invention. The magnifying optical system 17 shown in FIG. 6 can be manufactured by casting, shaving, or stereolithography. In consideration of casting using a mold or the like, an optical waveguide can be formed by providing planar gaps 19 on the display device side on both side surfaces and the upper and lower surfaces of the magnifying optical system 17, as shown in the figure. The width of the planar gap 19 can be easily taken out from the mold or the like by making the display device 1 side slightly wider or having a constant width. Further, similar to the above-described optical waveguide shown in FIG. 2, by applying coating, plating treatment, sputtering treatment or the like to the surface of the planar gap 19,
The magnifying optical system 17 can be sufficiently miniaturized. The exit surface 18 of the optical waveguide can be made uneven so as to have diffusivity. By mounting the magnifying optical system 17 shown in the present embodiment, the screen size of the display device 1 can be magnified.

In the embodiment, the reduction optical system or the enlargement optical system can be applied to any display device such as PDP, LCD panel, cathode ray tube, LED panel and the like.

[0012]

By applying the present invention, the performance limit of the display device in the spatial resolution and the display size can be compensated, and the display device can be miniaturized, high definition and large screen. For example, a 40-inch PDP having a pixel size of 0.6 mm square can be used to form a 20-inch 1M pixel display.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment that best represents the characteristics of a display device of the present invention.

FIG. 2 is a sectional view showing the structure of the reduction optical system according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a part of a conventional plasma display panel.

FIG. 4 is a perspective view showing a second embodiment of the display device of the present invention.

FIG. 5 is a sectional view showing the structure of a reduction optical system according to a second embodiment of the present invention.

FIG. 6 is a perspective view showing a third embodiment of the display device of the present invention.

[Explanation of symbols]

1 ... Display device, 2, 15 ... Reduction optical system, 17 ... Enlargement optical system.

Front page continued (72) Inventor Norio Yatsuda No. 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Stock Development Division, Hitachi, Ltd. multimedia system (72) Inventor Takashi Sasaki 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Hitachi, Ltd. Multimedia System Development Headquarters (72) Inventor Hiro Otaka, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock Company Hitachi Ltd. Multimedia System Development Headquarters

Claims (15)

[Claims] 1. An optical system comprising a plurality of optical waveguides,
A display device which is downsized, has a high definition, or has a large screen by being attached to a display screen of a display device of the display device. 2. The display device according to claim 1, wherein the optical system is formed of glass or an integrated structure of a resin material such as acrylic. 3. The display device according to claim 2, wherein the plurality of optical waveguides are formed by providing a gap in the optical system formed of the glass or a resin material such as acrylic as an integral structure. 4. A video device according to claim 3, wherein the gap provided in the optical system is formed by a combination of flat surfaces to facilitate manufacture. 5. The video device according to claim 3, wherein the gap provided in the optical system is formed in a wedge shape to facilitate manufacture. 6. An image device according to claim 3, wherein the gap provided in the optical system is formed in a flat plate shape in the horizontal direction and the vertical direction, thereby facilitating the manufacture. 7. The display device according to claim 3, wherein a reflection surface is provided on the surface of the gap provided in the optical system. 8. The display device according to claim 1, wherein the optical system comprises a plurality of optical waveguides formed of a reflective material. 9. A display device according to claim 1, wherein the emission surface of each of the optical waveguides is made smooth or is processed into a lens-like concave-convex surface to enable a narrow viewing angle display. 10. The display device according to claim 1, wherein the optical system is formed by using a plurality of optical fibers, and the display screen of the display device is reduced to a smaller screen size to improve the spatial resolution. . 11. The display device according to claim 1, wherein the wavelength characteristics of each of the optical waveguides are optimized by selecting the constituent material of each of the optical waveguides to improve the color reproducibility of the display device. 12. The display device according to claim 1, wherein the incident surface of the optical system is arranged on the display screen of the display device without a gap so that the display brightness is maximized. 13. The display device according to claim 1, wherein at least one of display brightness and contrast is improved by coating an interference film on an incident surface of each of the optical waveguides. 14. A screen size which is difficult to realize with the display device according to claim 2, wherein the optical system is a magnifying optical system having a function of converting a display screen of the display device into a larger screen size. Display device to get. 15. The display device according to claim 2, wherein the optical waveguide is surrounded by an interface between the optical path and a constituent material having a different refractive index.