WO2001097203A2

WO2001097203A2 - Fiber optic display screen

Info

Publication number: WO2001097203A2
Application number: PCT/CA2001/000895
Authority: WO
Inventors: Alexander Mantsvetov; Gennadii Ivtsenkov
Original assignee: Light Management Group Inc.
Priority date: 2000-06-15
Filing date: 2001-06-15
Publication date: 2001-12-20
Also published as: WO2001097203A3; AU2001270374A1

Abstract

A fiber optic based display system includes a plurality of optic fibers having an image receiving end and an image display end. The image receiving ends are bundled together and receive a graphic image from a projector. Each optic fiber transmits a piece of the image to its image display end, which is mounted in a display screen. The image display ends are spaced apart and are visible from a front side of the display screen, from which each fiber projects a light signal corresponding to the piece of the image incident on the image receiving end of the that fiber. The spacing between the image display ends is selected such that a typical person cannot resolve the light signal emitted from adjacent fibers. A person viewing the display screen consequently sees a cohesive image corresponding to the graphic image. The projector may be any type of light projector, including a slide or movie projector or a computer controlled projector which individually projects each pixel sequentially into the image receiving ends. In a second embodiment, each optic fiber is split into four optic fibers to reduce the spacing between adjacent image display end in the display screen. Both of these embodiments may be used with a plurality of lenses configured to collimate the light signals transmitted from the display screen to increase the intensity of the projected image. In another embodiment, the display screen is actually formed integrally with a piece of carpet to provide a floor display.

Description

Title: Fiber Optic Display Screen

Field of the Invention This invention relates to display screens capable of displaying still and moving video images. More particularly, the invention relates to a display screen for displaying a graphic image in an array of pixels.

Background of the Invention Video billboards are large display screens capable of displaying full-color still and moving graphic or video images. One type of video billboard includes a plurality of cathode ray tubes (CRT) mounted in an array. For example, 12 CRTs may be mounted in a four column by three row array. The video image to be displayed is divided into one section for each CRT. Each such section is then displayed on one of the CRTs and when observed by a viewer, the array of CRTs appear to be showing a unitary image. This system has several drawbacks. First, the system requires that the CRTs be precisely aligned such that the graphic image displayed appears to be continuous at edges of the CRTs. Second, such a system requires a substantial amount of power as each CRT requires a complete power supply and control system. As is well known, CRT-type display devices require substantial electric power to operate.

Another well-known system has a billboard screen comprising a plurality of pixels arranged in an array. Each pixel consists of three light emitting devices. For example, red, green and blue light bulbs may be used. If the intensity of each bulb can be independently controlled then the pixel can be configured to display any color of light. Although such a device does not have the alignment problems of the CRT-based device, this system does have the drawback that individual pixels may fail and individual light bulbs in each pixel may fail, requiring substantial effort to maintain the billboard in repair, particularly where the billboard is mounted in a location which is difficult to access. Furthermore, such devices may require substantial power input to operate the incandescent or other light emitting devices. Accordingly, there is a need for billboard display system capable displaying a full color still or moving video image without requiring a substantial effort to align the display screen or to ensure each pixel in the display system is operational. Furthermore, it is preferable that the system requires little maintenance to maintain it in proper operation. Particularly, it is preferable that components of the system which are positioned in locations that are difficult to access require little maintenance.

Summary of the Invention

In a first aspect the present invention provides a fiber optic based display system includes a plurality of optic fibers having an image receiving end and an image display end. The image receiving ends are bundled together and receive a graphic image from a projector. Each optic fiber transmits a piece of the image to its image display end, which is mounted in a display screen. The image display ends are spaced apart and are visible from a front side of the display screen, from which each fiber projects a light signal corresponding to the piece of the image incident on the image receiving end of that fiber. The spacing between the image display ends is selected such that a typical person cannot resolve the light signal emitted from adjacent fibers. A person viewing the display screen consequently sees a cohesive image corresponding to the graphic image. The projector may be any type of light projector, including a slide or movie projector or a computer controlled projector which individually projects each pixel sequentially into the image receiving ends.

In a second aspect, each optic fiber is split into four optic fibers to reduce the spacing between adjacent image display end in the display screen.

Both of these aspects may be used with a plurality of lenses configured to collimate the light signals transmitted from the display screen to increase the intensity of the projected image. In another embodiment, the display screen is actually formed integrally with a piece of carpet to provide a floor display.

In another embodiment, the present invention provides a system for displaying a graphic image, said system comprising: a plurality of optic fibers, each of said optic fibers having an image receiving end and an image display end, wherein the image receiving ends of said optic fibers are bundled together for receiving an incident image; and a display screen having a frame for holding the image display ends of said optic fibers such that said image display ends are spaced apart, said display screen having a rear side and a front side and said image display ends being visible from said front side. In another embodiment, the present invention provides apparatus for displaying a graphic image, said display system comprising: a plurality of primary optic fibers, each of said optic fibers having an incident image receiving end and a primary image display end wherein the incident image receiving ends of said primary optic fibers are bundled together to receive an incident image such that the incident image receiving end of each of said primary optic fibers receives a portion of said incident image and wherein each said primary optic fiber transmits a primary light signal to the primary image display end of said primary optic fiber, said primary light signal corresponding to said portion of said incident image received by the incident image receiving end of said primary optic fiber; a plurality of optic splitters, each said optic splitter having an optic input and at least two optic outputs, wherein the optic input of each of said optic splitters is coupled to the primary image display end of one of said primary optic fibers for receiving the primary light signal transmitted by said one primary optic fiber and wherein each said optic splitter is configured to provide a secondary light signal at each optic output of said optic splitter, each said secondary light signal corresponding to said primary light signal; a plurality of secondary optic fibers, each of said secondary optic fibers having a secondary image receiving end and a secondary image display end, wherein the secondary image receiving end of one of said second optic fibers is coupled to each said secondary optic output for receiving said secondary light signal; and a display screen having a frame for holding said secondary image display ends of said secondary optic fibers, such that said secondary image display ends are spaced apart, said display screen having a rear side and a front side, wherein each of said secondary display ends projects a projected light signal corresponding to the secondary light signal received from the front side of display screen.

Brief Description of the Drawings The present invention will now be explained, by way of example only, with reference to the drawings in which: Figure 1 illustrates a first embodiment of a video display system according to the present invention;

Figure 2 is a front elevational view of a display screen of the display system of Figure 1 ; Figure 3 illustrates a second embodiment of a video display system according to the present invention;

Figure 4 is a front elevational view of a display screen of the display system of Figure 3;

Figure 5 illustrates a modified display screen which may be used in conjunction with the embodiments of Figures 1 ;

Figure 6 illustrates a third embodiment of a display system according to the present invention; and

Figure 7 is an enlarged view of a section of Figure 6.

Detailed Description of the Preferred Embodiment

Reference is first made to Figure 1 , which illustrates a first embodiment of a display system 20 according to the present invention. Display system 20 comprises a number of optic fibers 22 and a display screen 24. Each of the optic fibers 22 has an image receiving end 26 and an image display end 28. The image receiving end 26 of each of the optic fibers 22 is arranged in an array 30. Array 30 is a planar lattice consisting of a plurality of rows and columns of the image receiving ends 26 of optic fibers 22.

Display screen 24, which is shown in Figure 1 from its rear side, consists of a frame 32 and a protective screen 34. Frame 24 is divided into a number of square sections 36. Each section 36 has an aperture 38 at its center. Each aperture 38 of each section 36 receives the image display end 28 of one of the optic fibers 22. Apertures 38 are spaced apart by a selected distance 40. The image display ends 28 of the optic fibers 22 are also spaced apart by distance 40. The image display end 28 of each optic fiber 22 extends through frame 32 and is visible from the front side of display screen 24, as shown in Figure 2. The image display end 28 of each optic fiber 22 may be referred to as a pixel 52. Collectively, all of the pixels 52 form a pixel array, the dimensions and spacing of which are configured by the structure of frame 32.

Protective screen 34 is a transparent or translucent sheet that covers the front surface of frame 32. The image display end 28 of each optic fiber 22 is visible through protective screen 34, particularly when protective screen 34 is entirely transparent.

Referring again to Figure 1 , each optic fiber 22 is selected such that a light signal projected onto its image receiving end 26 is transmitted to its image display end 28 and is visible from the front of display screen 24. The color and intensity of light visible at any specific pixel 52 (which is the image display end 28 of an optic fiber 22) corresponds to the color and intensity of the light signal projected onto the image receiving end 26 of corresponding optic fiber 22. The position of the image display end 28 of each optic fiber 22 in frame 32 corresponds to the position of the image receiving end 26 of that optic fiber 22 in array 30. For example, the image receiving end 44 of optic fiber 42 is in the upper right-hand corner (when viewed from the direction of arrow 54, which corresponds to the direction from which a viewer will observe the front of screen 24 as shown in Figure 2) and the image display end 46 of optic fiber 42 is at the upper right-hand corner of display screen 24 (when viewed from the direction of arrow 54).

The position of the image receiving end 26 of any particular optic fiber 22 in array 30 and the position of the fiber's image display end 28 in frame 32 will depend on the structure of a particular embodiment of a display system according to the present invention. This may depend on the characteristics of the graphic image 50 and image projector 48. For example, graphic image 50 may be inverted horizontally, vertically or both. A person skilled in the art will be capable of positioning the image receiving ends 26 of the optic fibers 22 in array 30 and the image display ends 28 of the optic fibers 22 in frame 32 so that a viewer will see the desired image on display screen 24.

In the preferred embodiment of display system 20, array 30 consists of 256 rows and 256 columns such that a 256 x 256 matrix of optic fibers 22 is bundled together to form array 30. Apertures 38 in frame 24 are spaced apart by distance 40 of 11mm thereby providing a square display screen 24 having sides approximately 2.8m long. Typically each optic fiber 22 will have a diameter between 90 μm to 1 mm. If, for example, each optic fiber 22 has a diameter of 200 μm then each side array 30, which consists of the image receiving ends 26 of each of the optic fibers 22 bundled together such that they are touching one another, will have a length of approximately 5.1 cm.

Display system 20 operates as follows. An image projector 48 is used to project a still or moving graphic image 50 onto array 30. Image projector 48 may be any type of projector, including a slide projector or a movie projector. Projector 48 may also be a computer controlled laser-based projector which scans across each optic fiber 22 and projects a single pixel of graphic image 50 into each optic fiber 22. Such a projector is disclosed in co-pending U. S. patent application number 60/183,198, entitled Acousto- Optical Switch for Fiber Optic Lines, which is incorporated herein by this reference.

The image receiving end 26 of each of the optic fibers 22 receives a portion of image 50 corresponding to the position of the particular image receiving end 26 in array 30. For example, fiber 42 receives a portion of image 50 which corresponds to the portion of image 50 projected onto image receiving end 44. Each optic fiber 22 then transmits that portion of image 50 which is received on its image receiving end 26 to its image display end 28, where it is visible as a pixel 52 from the front of screen 24.

Referring to Figure 2, which shows display screen 24 from the direction of arrow 54 (Figure 1). A viewer of screen 24 from this direction will observe pixels 52. The color and intensity of each pixel 52 emitted from the image display end 28 of each optic fiber 22 will correspond to the portion of graphic image 50 received at the image receiving end 26 of the optic fiber 22. The observer will therefore see an array of pixels 52 which correspond to image 50. It has been found that a typical person is capable of resolving points of light which are spaced by an angle of between 1' (in bright daylight) and 30' (in the dark), depending on the ambient condition. On an average evening, where bright street lighting is provided, a typical person cannot resolve two points of light spaced less than 4' apart. From a distance of 10m, a typical person is incapable of clearly resolving two points of light which are 11mm apart in such conditions. Accordingly, an observer standing 10m or more from display screen 24 will observe the points of light emanating from the image display end 28 of optic fibers 22 as a cohesive image which corresponds to image 50.

Display system 20 therefore allows a projector which is capable of displaying an image which is approximately 5 cm² to be used to produce a large format image which is approximately 2.8 m² and which appears as a continuous full color still or moving graphic video image to an observer standing 10m from display screen 24.

Reference is next made to Figure 3 which displays a second embodiment of a display system 120 according to the present invention. Elements of display system 120 which correspond to elements of display system 20 are identified by reference numerals which are 100 greater than the corresponding elements of display system 20.

Display system 120 includes a plurality of optic fibers 122, each of which has an image receiving end 126 and an image display end 128. The image receiving ends 126 of optic fibers 122 are bundled together to form an array 130 onto which a projector 148 projects a graphic image 150. Array 130 consists of a number of columns and rows. Display screen 124 comprises a frame 132 and a protective screen 134. Frame 132 is divided into a number of columns and rows corresponding to the number of columns and rows in array 130 which define section 136. Each section 136 of frame 132 has four apertures 138. Apertures 138 are positioned within each section 136 such that each aperture 138 is equally spaced from its adjacent aperture 138, whether in the same section 136 or in an adjacent section 136. Corresponding apertures 138 in adjacent section 136 are spaced by a distance 140. Adjacent apertures 138 are spaced by a distance 141 which is half of distance 140.

The image display end 128 of each optic fiber 122 is coupled to an optic splitter 156. Optic splitter 156 is coupled to a splitter end 160 of each of four optic fibers 158. A display end 162 of each of the four optic fibers 158 coupled to a single splitter 156 extends through the four apertures 138 in a single section 136 of frame 132. Each optic splitter 156 divides the optic signal received from the image display end 128 of its associated optic fiber 122 into four identical signals which are transmitted by optic fibers 158 to their image display ends 160. Referring to Figure 4, the image display ends 160 of optic fibers 158 are visible from the front surface (as viewed from the direction of arrow 154) of display screen 124. Each image display end 162 appears from the front of screen 124 as a pixel 152.

Display system 120 operates as follows. Projector 148 projects a graphic image 150 onto array 130 which comprises the image receiving ends 126 of optic fibers 122. Each optic fiber 122 transmits a portion of graphic image 150 to a splitter 156. For example, optic fiber 142 transmits the portion of image 150 received at its image receiving end 144 to its associated splitter 164. Each splitter 156 divides the portion of graphic image 150 transmitted by its associated optic fiber 122 into four identical optic signals which are then carried by the associated optic fibers 158 to their display ends 162 and are visible from the front side of frame 124 as pixels 152. Each of these four pixels 152 will have a color and intensity corresponding to the color and intensity of the portion of image 150 received at the image receiving end of the associated optic fiber 122. An observer viewing the front surface of frame 124 will see four identical pixels 152 in each section 136.

In this way, display system 120 provides a display screen 124 in which adjacent pixels 152 are spaced at only half the spacing as that of display screen 24 (Figure 2). Accordingly, an average person will not be able to resolve adjacent points of light from a distance of approximately 5m when viewing display screen 124 on an average evening when bright street lighting is provided. One skilled in the art will recognize that the graphic image displayed on screen 124 of system 120 will appear substantially the same as graphic image displayed on display screen 24 of system 20 when both devices receive the same input from their respective projectors 48, 148. Neglecting optic signal strength losses in splitters 156 the output display power of display screens 24 and 124 will be substantially the same.

If it is desired to increase the optic output power of display screen 24 or display screen 124 an in-line optic amplifier may be installed on each optic fiber 122 (or in the case of display system 120 in each optic fiber 158) to increase the strength of the optic signal transmitted by each optic fiber 22 or 122. This will provide a brighter display image on screen 24 or screen 124. If desired, distance 141 may be increased to 11 mm to provide a display screen 124 which is approximately 5.4 m square, and which appears to show a continuous image to an observer positioned 10 m or further from the display screen. A person skilled in the art will be capable of selecting an appropriate spacing to provide a continuous image in the particular conditions in which display system 120 will be used. Reference is next made to Figure 5, which shows a display screen 224 which may be used with display system 20 in place of display screen 24. Display screen 224 has a frame 232 which is identical to frame 32 of display screen 24. Protective screen 34 of display screen 24 has been replaced with an array 234 of lenses 236. As light representing a portion of image 50 is projected from the display end 28 of an optic fiber 22, it will form a diverging light beam. This diverging light beam will be incident on a lens 236. Lens 236 operates to reduce the divergence of the image incident on it. Collectively, all of the lenses 236 forming lens array 234 operate to reduce the divergence of the portions of light image transmitted by their associated optic fibers 22. This increases the brightness of the graphic image displayed on display screen 224 when it is observed from an angle generally perpendicular to display screen 224. Display screen 224 may be used in conjunction with in-line optic amplifiers to further increase the brightness of the image displayed on display screen 224.

Reference is next made to Figure 6, which illustrates a third embodiment of a display system 320 according to the present invention. Display system 320 comprises a plurality of optic fibers 322, and a carpet 324. Carpet 324 has a backing 331 and a surface layer 332. Each optic fiber 322 has an image receiving end (not shown) which is bundled in an array (not shown), in the same manner as the corresponding components of display system 20. Each optic fiber 322 also has an image display end 328. Each optic fiber 322 is inserted into carpet 324 between backing 331 and surface layer 332. The image display end 328 of each optic fiber 322 is drawn through surface layer 332 so that image display end 328 is visible from the above carpet 324 (when viewed in the direction indicated by arrow 354), and appear as pixels 352. Preferably, the top of image display end 328 is level with the top of surface layer 332. When a projector is used to project an image on the image receiving ends (not shown) of optic fibers 322, the image will be transmitted, in portions, by optic fibers 322 to their image display ends 328, where it will appear on pixels 352. A viewer standing on carpet 324 will be able to observe this image on pixels 325. In general, a viewer will observe carpet 324 from an acute angle. Accordingly, it is preferable to leave the image display ends 328 of optic fibers 322 unpolished so as to increase the dispersion of light from them at such angles. Display system 324 may be used to display a still or moving video image in a movie theatre to display advertising or in an aircraft aisle to indicate emergency exit instructions. Since carpet 324 of display system 320 may be observed by a person looking almost straight down, it may be preferable to space pixels 352 of optic fibers 322 closer than 11 mm, so that the image displayed on them will appear continuous to such an observer. For example, if it desired to make the image appear continuous to a person viewing it from a height of 1 m, then pixels 352 should be spaced no more than 1.1 mm apart. A person skilled in the art will be capable of calculating the appropriate spacing between adjacent pixels 352.

In each of the embodiments of the present invention described above, the display screen (24, 124, 224 or carpet 324) is configured as a square. As noted earlier, the display screen may be configured as a rectangle. In addition, the display screen may be configured in any selected shape, for example, as circle, etc., depending on the information which will be displayed using the display system. Furthermore, it is not necessary that the array formed by the image receiving ends (for example, array 30) of a group of optic fibers have the same shape as the pixels of the display screen (for example, screen 24.) When a projector capable of sequentially projecting a light signal representing a single pixel is used to scan across an array of image receiving ends (i.e. array 30) and project each pixel separately, it is possible to bundle the image receiving ends of the optic fibers in an array with a shape convenient for use with the projector and to organize the image display ends in a frame having any desired shape. In such a case, the projector must be programmed with the correlation between the position of the image receiving end in the array and the corresponding position of the image display end of that fiber in the display screen.

A person skilled in the art will be capable of producing these and other variations of the present invention. Such variations are within the spirit and scope of the present invention, which is limited only by the following claims.

Claims

We claim:

1. A system for displaying a graphic image, said system comprising:

(a) a plurality of optic fibers, each of said optic fibers having an image receiving end and an image display end, wherein the image receiving ends of said optic fibers are bundled together for receiving an incident image; and

(b) a display screen having a frame for holding the image display ends of said optic fibers such that said image display ends are spaced apart, said display screen having a rear side and a front side and said image display ends being visible from said front side.

2. The system of claim 1 wherein said image receiving ends of said optic fibers are arranged in a selected pattern and wherein the image display end of each said optic fiber is held in said frame in a position corresponding to the position of the fiber's image reception end in said selected pattern.

3. The system of claim 2 wherein said selected pattern is an array consisting of at least one row.

4. The system of claim 2 wherein said selected pattern is an array consisting of at least one row and at least one column.

5. The system of claim 1 wherein said display screen further comprises a protective screen coupled to said frame.

6. The system of claim 1 wherein said screen further comprises a plurality of lenses, each of said lenses aligned with the image display end of one of said optic fibers.

7. The system of claim 6 wherein said lenses are spaced apart from said frame.

8. The system of claim 6 wherein each of said lenses is positioned to receive a diverging light signal projected from said one of said optic fibers and is configured to refract said light signal to decrease its angle of divergence.

9. The system of claim 6 wherein said image display ends of said optic fibers are held in said frame in a lattice such that said image display ends are equally spaced from one another.

10. The system of claim 9 wherein each of said lenses are arranged in a lattice such that each of said lenses is aligned with the image display end of one optic fiber selected from said plurality of optic fibers to receive a diverging light signal projected from said image display end of said selected optic fiber.

11. The system of claim 10 wherein each of said lenses is shaped to refract said diverging light signal to reduce the angle of divergence of said diverging light signal.

12. The apparatus of claim 1 wherein said frame is formed of carpet.

13. Apparatus for displaying a graphic image, said display system comprising: (a) a plurality of primary optic fibers, each of said optic fibers having an incident image receiving end and a primary image display end wherein the incident image receiving ends of said primary optic fibers are bundled together to receive an incident image such that the incident image receiving end of each of said primary optic fibers receives a portion of said incident image and wherein each said primary optic fiber transmits a primary light signal to the primary image display end of said primary optic fiber, said primary light signal corresponding to said portion of said incident image received by the incident image receiving end of said primary optic fiber; (b) a plurality of optic splitters, each said optic splitter having an optic input and at least two optic outputs, wherein the optic input of each of said optic splitters is coupled to the primary image display end of one of said primary optic fibers for receiving the primary light signal transmitted by said one primary optic fiber and wherein each said optic splitter is configured to provide a secondary light signal at each optic output of said optic splitter, each said secondary light signal corresponding to said primary light signal;

(c) a plurality of secondary optic fibers, each of said secondary optic fibers having a secondary image receiving end and a secondary image display end, wherein the secondary image receiving end of one of said second optic fibers is coupled to each said secondary optic output for receiving said secondary light signal;

(d) a display screen having a frame for holding said secondary image display ends of said secondary optic fibers, such that said secondary image display ends are spaced apart, said display screen having a rear side and a front side, wherein each of said secondary display ends projects a projected light signal corresponding to the secondary light signal received from the front side of display screen.

14. The apparatus of claim 13 wherein said display screen is divided into a plurality of sections and wherein the secondary display end of every secondary optic fiber coupled to a single said primary optic fiber is held in one of said sections.

15. The apparatus of claim 14 wherein said sections form an array consisting of at least one row.

16. The apparatus of claim 14 wherein said sections from an array consisting of at least one row and one column.

17. The apparatus of claim 16 wherein the incident image receiving ends of said primary optic fibers are bundled together in an array wherein the position of the incident image receiving end of each said primary optic fiber corresponds to the position of the section to which said primary optic fiber is coupled in said display screen.

18. The apparatus of claim 17 wherein said secondary image display ends_, are equally spaced from one another.

19. The apparatus of claim 13 wherein said display screen further comprises a protective screen coupled to said frame.

20. The apparatus of claim 13 wherein said screen further comprises a plurality of lenses, each of said lenses aligned with the image display end of one of said secondary image display ends.

21. The apparatus of claim 20 wherein said lenses are spaced apart from said frame.

22. The apparatus of claim 20 wherein each of said lenses is positioned to receive said projected light signal from said secondary display end with which it is aligned, and wherein said projected light signal is divergent and wherein each said lense is configured to refract said projected light signal to decrease its angle of divergence.

23. The apparatus of claim 13 wherein said frame is made of carpet.