FR2517075A1 - OPTICAL FIBER NETWORK FOR TRANSMITTING IMAGES - Google Patents

Abstract

THIS NETWORK INCLUDES AT LEAST ONE ROW OF OPTICAL FIBERS 12 IMAGE TRANSMITTERS. AT THE ENDS OF THE FIBERS ARE PROVIDED PAIRS OF OPPOSED MIRROR SURFACES 16, 18, 20, 22 WHICH ALLOW TO IMPROVE THE LIGHT CAPACITY OF THE NETWORK. APPLICATION TO PHOTOCOPYING MACHINES, IMAGE TRANSFER OPTICS FOR LIGHT DIODE OR CATHODIC RAY TUBE PRINTERS.

Description

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  The present invention relates to a means for transmitting

  image and more particularly a means of increasing the light flow of a linear or point source radiant

  on the axis of a fiber optic system with a refractive index

  progressively maintaining the integrity of the image. The optical fibers transmitting dtimage, such as

  those produced by Nippon Sheet Glass Co, under the name

  Seofoc, are used in many applications, such as copying machines, transfer optics for light-emitting diode printers or

  cathode ray tube scanning and printers

  Selfoc fiber or optical fiber image transmitter is made of glass or synthetic resin having a distribution of

  the refractive index in a cross-section of that

  which varies parabolically outwards from the center

  be of the fiber and is defined by the equation n = no (l-ar)

  o no is the index of refraction in the center, N is the index of refraction

  fraction at a distance r from the center and has a constant positi-

  Proportionality The Selfoc lens and the image transmitter formed by a Selfoc lens bundle are described

in US 3,658,407.

  A practical image transmitter consists of a large number of said image-transmitting optical fibers, which are

  held together in a bundle, according to an agency

  staggered, for example by a synthetic resin or other

  suitable binder, and the opposite ends of which correspond

  These are a receiver surface and an image emitter surface. When an image of a linear source such as can be plotted on a cathode ray tube or a point source such as a light emitting diode is created,

  by an optical grating of refractive index-refractive fibers

  the amount of light collected is maximized by increasing the number of rows of fibers in the network to the point where the limitations imposed by the field of view of the fibers prevent a further improvement.

  two or three rows of fibers provide the greatest

  practical city for capturing light.

  The increase in the number of rows, however,

  also the cost, size and complexity of manufacturing

network.

  The present invention therefore provides a

  positive that can be used to provide a network of

  optical fiber with a gradient refractive index having nearly two to three times the light-catching capacity that a same fiber network conventionally used and is applicable to electrostatic printers where the light source whose image is created is a cathode ray tube (CRT) or

  a light-emitting diode array The invention may also be

  if used in any image transfer system, in which a line of a cathode ray tube or a light emitting diode array is to be represented by an image, such as tube-type photographic recorders

cathode rays.

  The present invention therefore brings about an improvement

  fiber-optic fiber grating in a refractive index fiber optical network.

  gradient arrangement having at least one row of optical fibers

  transmitters, the fibers having

  The improvement consists of a pair of sur-

  opposite mirror faces adjacent to the input and output ends of the fibers of the array, areas that increase the light pickup capability of the optical fiber grating

  gradient refractive index.

  Other features of the invention will appear

  during the description which follows.

  In the attached drawings, given solely as examples

  Fig. 1 is a side view of a linear or point source located on the axis of a single row array of gradient refractive index fibers according to the prior art;

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  Fig 2 is similar to Fig 1 but shows

  in addition to mirror surfaces adjacent to the ends of

  trea and output of the row according to the present invention; FIG. 3 is a perspective view, partially broken away, of a two-row network of gradient refractive index fibers having mirror surfaces adjacent to the inlet and outlet ends of the two rows in accordance with FIG.

present invention.

  In the description of the preferred embodiment

  of the present invention, reference will be made to the drawings, which

  show in Fig. 1 a linear or

  FIG. 10 located on the axis of a single row gradient refractive index fiber array 12 according to the prior art. It can be seen that the image 14 contains light emitted only within the angle a, while all

  the rays beyond this angle are lost.

  Fig. 2 shows how the addition of mirror surfaces placed adjacent to the input and output ends of the row increases the light-catching capacity of the fibers 12 A pair of input mirrors 16 and 18 placed

  as shown in Fig. 2, light sources

  in B and C, whose rays are collected by the

  12 It is important to note that the rays appearing

  B and C would not be captured in the absence of mirror surfaces 16 and 18. A pair of mirrors 20 and 22 are located at the exit end of fiber 12.

  otherwise (ie mirrors 16 and 18 being the only ones

  sents) would form the images in Bt and C 'are broken by the second pair of mirrors 20 and 22 and superimposed at A' Since the image at A 'contains light from A, B and C, the network throughput was because the light from the apparent sources in B and C is not as bright as

  light emanating from the point source of light or

  Neon A, the image at A 'is not three times brighter than it would be without the mirrors 16, 18, 20 and 22, but 2.5 times brighter than it would be without the four mirrors

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  16, 18, 20 and 22 for the single-fiber fiber network 12

shown in Fig 2.

  FIG. 3 shows optical fibers with a refractive index

  gradient fraction 12 arranged in two offset rows 24 and 26 and held together by a synthetic resin or

  Suitable binder 28 On each side of the fibers 12 is

  placed a support block 30, 32 to support the mirrors

  34, 36 and exit mirrors 38, 40 respectively.

  The results of the tests showed that the increase in light flow with the two-row grating, as shown in Fig. 3, is almost the same as with the single-row system shown in Fig. 2 Generally, however, there is a slight decrease in capacity increase

  of light capture from an optical fiber network with indi-

  this gradient refraction, since the number of

  The increase in fiber is increased, but this decrease is very slight.

R E V E N D I C T IO N S

  1 optical fiber grating with refractive index at

  gradient having at least one row of trans-

  image transmitters, said fibers having predetermined ends

  and the output, characterized in that it comprises a pair of opposed mirror surfaces (16, 18, 20, 22) adjacent to the input and output ends of said array fibers (12), which increase in area. the capture capacity of the

light of the network.

  2 network according to claim 1, characterized in that it comprises two rows (24, 26) of optical fibers, said rows being closely held together in

  beam, in an offset arrangement.

  3 Network according to claim 1, characterized

  in that the increase in its capacity to capture light

  is of the order of 1.5 times the capture capacity of the

  light of an optical network not possessing the characteristics

of the invention.