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United States Patent m
Shimamune et al.
[li] Patent Number:  Date of Patent:
 IMAGE DISPLAY DEVICE AND ITS MANUFACTURING METHOD
 Inventors: Minora Shimamune, Omihachiman;
Takuo Ito; Takao Negishi, both of
Otsu; Kouzou Takano, Gamou, all of
 Assignee: Toray Industries, Inc., Tokyo, Japan
 Appl. No.: 190,578
 Filed: Feb. 2,1994
Related U.S. Application Data
 Continuation of Ser. No. 856,957, Aug. 10,1992, abandoned.
 Int. Cl.« G02B6/06
 U.S. CI 385/116; 385/119;
 Field of Search 385/115, 116, 117, 119,
385/120, 901, 900, 31, 33; 156/249
 References Cited
U.S. PATENT DOCUMENTS
3,853,658 12/1974 Ney 385/116
4,814,948 3/1989 Hasegawa 362/32
4,925,514 5/1990 Okada et al 385/140
4,983,015 1/1991 Bourguignat et al 385/116
4,986,628 i/1991 Lozhenko et al 385/31
5,073,402 12/1991 Henderson 427/2
5,127,080 6/1992 Duggan, Sr 385/120
5,150,445 9/1992 Toyodaetal 385/116
5,193,526 3/1993 Daikuzono 128/7
FOREIGN PATENT DOCUMENTS 0275061 7/1988 European Pat. Off. G02B 6/06
0357070 3/1990 European Pat. Off. G02B 6/08
50-104646 8/1975 Japan G02B 6/08
61-11782 1/1986 Japan G09F 9/00
63-60111 4/1988 Japan G02B 6/06
2-294684 12/1990 Japan G02B 6/04
4-138403 5/1992 Japan G02B 6/00
Primary Examiner—Frank Gonzalez
Attorney, Agent, or Firm—Fish & Richardson
In the image display device of the present invention, a number of light scattering layers formed on the ends of optical fibers are spotwise distributed on the image display surface, and said scattering layers are comprised of a transparent resin having a granular light scattering material added or very small depressions and projections produced on the surface. Further, the method of manufacturing the image display device according to the present invention is characterized by arranging the end faces of a number of optical fibers to the image display surface, then applying a photosensitive resin onto the image display surface, hardening the resin around the end of the respective optical fibers on the image display surface by the beam of light from the incident surface to form light scattering layers, then removing the unhardened portions. With the image display device thus obtained, an image is transmitted via a number of optical fibers and displayed via a number of light scattering layers, and so a wide angle is provided for the field of vision, and also with the dark colored ground, it is possible to reduce the reflection of the light of disturbance at portions other than the light scattering layers and thus display a clear image of high contrast.
16 Claims, 2 Drawing Sheets
IMAGE DISPLAY DEVICE AND ITS
This application is a continuation of U.S. application 5 Ser. No. 07/856,957, filed Aug. 10, 1992, now abandoned.
This invention relates to a device for transmitting and 10 displaying imagery using optical fibers. More specifically, it relates to a device being adapted for increasing the size of the image, having a broad angle of field and being scarcely affected by the environmental disturbing light and being capable of displaying a distinct image of 15 a high resolution.
BACKGROUND OF THE INVENTION
As a device for transmitting and displaying an image with optical fibers, two types are generally known. One 20 is the so-called image guide or imagescope which displays a full-size image with optical fibers densely bundled in the same arrangement for both incident and image display planes, and the other is an image display device having a function enlargement with a greater 25 clearance of optical fibers provided for the image display plane than for the incident plane to form a large screen of an image size of several feet. In either case, the image display surface (screen surface) is formed by cut end faces of the optical fibers. However, the beams of 30 light coming from the end faces are highly directional, and so the image may be clearly seen in a certain range of angle to the image display surface, that is, in a nearly vertical direction. However, it becomes very difficult to observe the image as that angle to the perpendicular of 35 the image display surface increases. That is, such a device has a shortcoming that the angle of the field of vision is limited. Then, in the case of a large size screen which is particularly intended for a number of persons to see at the same time, some means are required to 40 scatter the outcoming light over a wide range of angles.
The conventional countermeasures to this problem are classified largely into two methods: one is to scatter the light emitted from the optical fibers with a light scattering plate or film pasted on the image display 45 surface (which will be referred to as "screen surface" in the following where a large screen is concerned); and the other to provide a light scattering structure at the end face of optical fiber. According to the former method, the light scattering plate or film reflects the 50 environmental disturbing light, and hence has the disadvantage that the reflected light comingles with the image information displayed thus obscuring the image or, more specifically, reducing the resolution and contrast of the image. As for the latter method of providing 55 a light scattering structure at the portion from which light is emitted, it is practically impossible to work up the end face of each of an optical fiber bundles, especially for a large screen having a hundred thousand of optical fibers present on the screen surface. 60
There has also been proposed a method of laminating the optical fibers in parallel in a tilted condition at a certain angle to the screen surface, that is, forming the screen surface with the end faces of the optical fibers cut at less than a perpendicular angle to the axis of the 65 optical fiber (Patent Publication No. SHO 61-11782). According to this method, however, the rate of enlargement to the plane of incidence and the scattering on the
screen surface or the field angle are simultaneously determined by the extent of tilting in the axial direction of the optical fiber bundles. Thus, it is impossible to independently and separately adjust both elements.
In view of the foregoing shortcomings in the prior art, it is the object of the present invention to provide, by a very simple method, a display device which has a wide angle of the field of vision and which is capable of producing a highly resolved, clear image where the image information is easily recognized.
DISCLOSURE OF THE INVENTION
To resolve the foregoing problems, the present invention is composed of the following.
In an image display device having one end faces and the other end faces of an optical fiber bundle arranged respectively on the image display surface and image incident surface, the image display device of the present invention is characterized in that the image display surface has a number of light scattering layers distributed spotwise, said scattering layer being formed at the end of each of the optical fibers and comprised of a transparent resin having a granular light scattering added or having very small depressions and projections on the surface.
The method of manufacturing the image display device of the invention is characterized by disposing one end faces of an optical fiber bundle onto the image display surface, then applying a photosensitive resin having a granular light scattering agent added over the whole image display surface, having the resin around the end of the respective optical fibers on the image display surface hardened by light from the plane of incidence, and removing any unhardened resin.
FIG. 1 schematically shows an example of the image display device of the invention.
FIG. 2 is an expanded view of the end face of an optical fiber on the screen, and FIG. 3 is a cross-sectional view of the same.
FIG. 4 shows a specific method of forming a scattering microlens in the present invention.
FIG. 5 is a cross-sectional view of the end face of an optical fiber according to another embodiment of the invention.
In the drawings, the numerals represent the following.
1: Optical fiber bundle
2: Image incident surface
3: Image display surface (screen surface)
4: Light scattering layer (microlens)
5: Hardened photosensitive resin
6: Scattering agent
7: Cut end face of optical fiber
8: Optical fiber
9 and 10: Source of light
11: Applied photosensitive resin
12: Support frame
BEST MODE FOR CARRYING OUT THE
The present invention will be described with a large screen having an enlarging function taken as an example.
FIG. 1 is an example of the image display device according to the present invention. In the drawing, numeral 1 shows a bundle of optical fibers transmitting