GB2067300A - Copier having fibre optics - Google Patents

Abstract

An electrostatic copier has an illumination system which includes a fibre optics ribbon 24. The intensity of illumination may be adjusted by means of a screen 34 which is located between ribbon 24 and light source 16. The screen 34 may be adjusted manually or photoelectrically. The fibres may be non-uniformly distributed to overcome the effect of the cos 4 factor. As shown, an image of an original 14 is transmitted to a photoconductive drum 18 by an optical system which includes a second fibre optics ribbon 50. The position of this and of a lens 56 may be adjusted by cams 78, 80 to alter magnification. <IMAGE>

Description

SPECIFICATION Copier having fibre optics imaging The primary function of an optical system in a photoelectric copier is to illuminate the document to be copied so that light may be reflected therefrom and to relay the image of the original to a photosensitive surface. This has been accomplished by several schemes in prior copiers, including one-to-one full field imaging, travelling mirror scanning, stationary optical elements in conjunction with a reciprocating platen, and combinations of these methods. These prior optical systems have the disadvantage in that they take up a relatively large volume and add considerable weight to the copier system. These prior schemes do not obtain maximum performance while achieving minimum volume, minimum weight and minimum cost.Examination of copier systems suggest that the optimum optical system, from a functional viewpoint, would have the following elements: a stationary original, a travelling lens and translating photoreceptor. In prior copier imaging systerns, one solution to obtain these three elements has been to employ a double set of moving mirrors, one set moving at full speed and the other set moving at half speed so as to match the image speed to the photoreceptor speed. This has yielded a family of copier designs which are structurally either high and narrow or low and wide. This is because the scanning optics and the photoreceptor are either stacked, thus resulting in a tall copier, or in line, thus resulting in a wide copier.Such a system can be folded about any mirror or set of mirrors to package it, but when it is noted that the width of the mirror usually has to approach or equal the width of the original, this does not help in achieving minimum overall volume.

In an attempt to overcome the above shortcomings and to obtain an optimum copier imaging system that eliminates mirror folds and their mechanical drives, an image is relayed, using a ribbon of coherent glass fibres, from a travelling carriage to a suitable stationary point for final reimaging.

According to the invention, there is provided an electrostatic copier wherein a document to be reproduced is illuminated and the image thereof reflected onto a photoconductive surface, comprising: a housing, a transparent platen supported within the housing, fibre optic means located within the housing for directing light onto an original on the platen, means for receiving light reflected from the original and conveying it to the drum and means located between the light source and the fibre optic means for varying the intensity of light received by said fibre optics.

As particularly disclosed and illustrated herein, the flexing and folding required to minimize the height and width of the copier housing is then controlled by the mechanical properties of the glass fibre ribbon and not by the optical geometry.

The lamp illuminator may also be removed to reduce the height of the travelling package. The illumination fibre ribbon can be combined with the image fibres if packaging them in this way is advantageous. Additionally, variable magnification can be achieved with relative ease by mechanically varying the distance from the lens to the fixed ribbon and the distance from the lens to the drum. The speed of the scanning carriage will also have to vary as the magnification varies.

A features of the invention is that the effect of the cos 40 factor may be overcome by selectively arranging the glass fibres at the faces of the ribbon with a higher concentration of fibres adjacent the lateral ends of the ribbon. Another feature of the invention is the intensity of the light conveyed from the lamp illuminator may be varied through use of a shutter unit located between an end of a fibre optic ribbon and the light source.

The invention will be better understood from the following non-limiting description of examples thereof given with reference to the accompanying drawings in which: Figure 1 shows a diagrammatic longitudinal sectional, view of a copier having a single moving mirror according to one example of the present invention.

Figure 2 is a diagrammatic, longitudinal sectional, view of a copier with a folded mirror package according to a second example of the invention.

Figure 3 is a detailed view of an illumination system that may be used in the copiers shown in Figures 1 and 2 particularly illustrating the face of the fibre ribbon.

Figure 4 is a plan view of a screen unit, taken along the lines fli 4 of Figure 3.

Referring now to the drawing, wherein like parts in Figures 1 and 2 are designated by the same numbers, a copier is shown having a housing 10 that supports a transparent platen 12 upon which an original document 14 to be reproduced may be placed. In the drawing, only the essential parts of the copier that are required to describe the invention are shown, it being appreciated that other components are necessary to produce a copy but are not required for the purpose of describing the invention. A lamp 1 6 is supported within the housing 10. A drum 1 8 is mounted on a shaft 20 and has a light sensitive photoconductive surface, such as zinc oxide, the drum being rotatable as indicated by the arrows in Figures 1 and 2.A frame 22 is movably supported in the housing and has secured thereto a ribbon 24 of optical fibres 26 which ribbon has an expanded end 28. The expanded end 28 has a face 30 that addresses the platen 12, the distribution of the optical fibres 26 being arranged so that more optical fibres are situated along the lateral marginal regions of the face 30 than in the central portion as can be seen in Figure 3. This distribution of fibres 26 is for the purpose of overcoming the cos 40 factor. This factor causes diminution of light on the outer parts of an image.

Reference may be had to "Lenses in Photography" by Rudolf Kingslake, A. S. Barnes and company Roc. (1963) for a discussion of the cos 40 factor.

Intermediate the lamp 16 and the ribbon 24 is a lens 32 that serves the purpose of focusing light emitted from the lamp 24 onto the ribbon.

Intermediate the lens 32 and the ribbon 24 is a screen 34 that has a stub shaft 36 (Fig. 4) extending from one side and an elongated shaft 38 extending from the opposite side. These shafts 36, 38 are journalled within lugs 40 that are supported within the housing 10, the shaft 38 passing rhrough its associated lug and extending outside the housing 10. A lever 42 is secured to the shaft 38 to provide manual means for rotating the screen 34.

Referring now to FIG. 1, a mirror 44 is secured within the frame 22 for movement therewith and a lens 46 is positioned in the path of the mirror such that light reflected from the original 14 will be reflected from the mirror 44 towards the lens 46. An optical fibre ribbon 50 has one end 52 secured to the frame 22 and another end 54 supported within the housing 10, this other end 54 addressing, i.e. facing, the drum 18. The ends 52, 54 are enlarged and of the same general configuration as is the end 28 of the ribbon 24, i.e., the distribution of the optical fibres at its face 30 is controlled to overcome the cos 4H factor.

Located between the end 54 of the ribbon 50 and the drum 18 is a lens 56 that focuses the light emitting from the ribbon 50 onto the photoconductive drum 18. With this construction, the frame 22 may be moved to the left as indicated by the arrow in FIG. 1, and will carry along therewith the ribbon 24, the mirror 44, the lengs 46 and the ribbon 52 so that the original 14 placed upon the platen 12 will have its image reproduced on the photoconductive drum 18 when the same is charged. Means for moving such a frame is well known in the art and will not be described herein as it does not form a part of the present invention.

Referring now to FIG. 2, the frame 22 supports a mirror 58, a double set of mirrors 60 and 62 and a lens 64. In this system the double lens 60, 62 will move to the right as seen in FIG. 2 at half the speed at which the mirror 58 will move. The means for accomplishing this relative movement is well known in the art and will not be described.

An optical fibre ribbon 65 is supported by the frame 22 and has a first segment 66 that addresses the lamp 16. Another segment 68 addresses the platen 12 so that light is tronsmitted from the lamp 1 6 through the ribbon 65 onto the platen 68. Another segment of the ribbon 65 is spaced relative to the lens 64 and the fibres thereof pass through another ribbon segment 72 whose face addresses the drum 18.

Located between the ribbon segment 72 and the drum 18 is a lens 74 which focuses the image upon the drum.

in operation, the lamp 1 6 will emit light that wi be received by the ribbon segment 68 to be directed to an original document 14 placed on the transparent platen 12. The shutter 34 may be rotated so as to control the intensity of the light directed onto the original 14. Such control may be accomplished automatically, as for example through the use of photocells and servo motors, or the same may be accomplished manually through the turning of the handle 42.As light is reflected from the original 14 onto the mirror 58 it is then directed to the double mirrors 60, 62 and to the ribbon segment 70 where the light is directed through ribbon segment 72 to the lens 74 to be directed to the drum 18 thereby producing an image of the original 14 upon the photoreceptive drum 1 8. With the presence of these optical ribbons, it is apparent that the mirrors of the optical system may be located anywhere relative to the drum 1 8 because of the flexibility of the fibre optic ribbons 50, 64. With the use of the expanded end 28 of each of the ribbons the fibre optic illuminator responds to the illumination demands of the copier in a cost effective manner.

Non-uniform illumination can be tailored to any given specification by varying the number of layers at the output end. In this way a cos 40-distribution for the lens could be balanced out.

In addition, magnification may be achieved by varying the location of the ribbon segment 72 as well as varying the location of the lens 74 so that the distances from the ribbon 64 to the lens 74 and from the lens 74 to the drum 18 will be varied equally. With this, the speed of the scanning carriage 22 will also have to vary as the magnification varies. The location of the ribbon segment 72 and the lens 74 may be controlled by any convenient drive system such as a Peltier linkage seen in Fig. 1. Such a linkage includes a shaft 76 having a pair of cams 78 and 80 mounted thereon. Any convenient means (not shown) may be provided for selectively rotating the shaft 76 such as, for example, a stepper motor or a servo mechanism. A linkage 82 provides engagement between the cam 78 and the ribbon end 54, there being a cam follower 84 connected to the linkage and in engagement with the cam 78. Another linkage 86 provides engagement between the cam 80 and the lens 46, then being a cam follower 88 connected to the linkage 86 and in engagement with the cam 80. The cams 78 and 80 and linkage 82 and 86 and constructed in a way such that the ribbon end 54 and lens 46 will move in the same direction upon rotation of the shaft 76 with the ribbon send 54 moving twice the distance of the lens 46.

Claims (13)

1. A copier wherein a document to be reproduced is illuminated and the image thereof reflected onto a photoconductive surface, comprising: a housing, a transparent platen supported within the housing, fibre optic means located within the housing for directing light onto an original on the platen, means for receiving light reflected from the original and conveying it to the drum and means located between the light source and the fibre optic means for varying the intensity of light received by said fibre optics.

2. A copier according to claim 1 wherein the light intensity varying means is a screen, the copier including means for rotating said screen.

3. An electrostatic copier wherein a document to be reproduced is illuminated and the image thereof reflected onto a photoconductive surface, comprising: a housing, a transparent platen supported by the housing, a light source, a fibre optic ribbon located within the housing, the ribbon having a first end addressing the light source and second end addressing the platen for directing light upon a document disposed upon the platen, at least one end of said fibre optic ribbon having a face which has the optic fibre ends of the ribbon distributed in such a way that there is a higher concentration of fibres adjacent the edges of the ribbon and a lower concentration towards the centre thereof to compensate for the cos 40 factor, and means for directing light reflected from the document onto the photo-conductive surface.

4. A copier according to claim 3 including a screen located between said light source and said first end and means for rotating said screen whereby the intensity of light conveyed to said first end may be varied.

5. An electrostatic copier wherein a document to be reproduced is illuminated and the image thereof reflected onto a photoconductive surface, comprising: a housing, a transparent platen supported by the housing, a light source, a first fibre optic ribbon located within the housing between the light source and the platen, mirror means for receiving light from a document disposed upon the platen and reflecting the light to a second fibre optic ribbon which has a first end addressing said mirror means and a second end for directing light onto the photoconductive surface.

6. A copier according to claim 5 wherein said mirror means is movably supported within said housing.

7. A copier according to claim 5 or 6 wherein the end of said first fibre optic means addressing said platen has a distribution of fibre ends arranged to compensate for the cos 40 factor.

8. A copier according to claim 5, 6, or 7 wherein a lens is located intermediate the second end of the second fibre optic ribbon and the photoconductive surface, and including means for moving the second end and the lens as appropriate to the copying cycle.

9. A copier according to claim 8 wherein said moving means is arranged to move the second end twice the distance moved by the said lens.

10. An electrostatic copier wherein a document to be reproduced is illuminated and the image thereof reflected onto a photoconductive surface, comprising: a housing, a platen supported by the housing, fibre optic means located within said housing for directing light upon the platen, means for receiving light reflected from a document disposed upon the platen and directing the light to the photoconductive surface and means for varying the location of said receiving and directing means to vary the magnification of the image directed onto the photoconductor.

11. A copier according to claim 10 including means for varying the intensity of light received by the fibre optic means.

12. A copier substantially as herein described with reference to and as illustrated in Figures 1,3 and 4 of the accompanying drawings.

13. A copier substantially as herein described with reference to and as illustrated in Figures 2, 3 and 4 of the accompanying drawings.