WO1983001692A1

WO1983001692A1 - Improvements in and relating to document copiers

Info

Publication number: WO1983001692A1
Application number: PCT/GB1982/000309
Authority: WO
Inventors: John Michael Payne
Original assignee: John Michael Payne
Priority date: 1981-10-29
Filing date: 1982-10-28
Publication date: 1983-05-11
Also published as: EP0091937A1; IT8249396A0; GB8315501D0; IT1189405B; JPS58501841A; GB2118729A

Abstract

A portable photocopier comprises an elongate housing (10) accomodating a roll of sensitised paper (25) and a feed mechanism for feeding the paper from the roll passed a corona wire (39) for electrostatically charging the paper to a location (13) for illuminating the charged sheet in contact with a document to be copied and then to a device (28) for applying toner to the charged exposed paper and for fixing the toner. The copier is traversed across the surface of the document to be copied by the movement of the paper.

Description

Improvements in and relating to document copiers

DESCRIPTION Field of Invention

This invention concerns document copiers and in particular .a photocopying device for copying papers and documents. Background to the Invention

Conventional photocopies normally remain generally stationary while the document to be copied may itself remain stationary while it is optically scanned to produce an image of the text thereon or the document is itself moved relative to the copier so as to provide for the- necessary relative movement to achieve a scanning of the document. Hitherto document copiers have, therefore, tended to be relatively large pieces of equipment at least as large in area as the largest document which is intended to be copied by the machine.

Since prior art photocopies have normally been associated with office use there has been no attempt to miniaturise the copier below a size slightly larger than the largest document which is to be copied by the copier.

It is an object of the present invention to ^'provide a copier which whilst it can still be used in an office or similar environment is primarily intended to be of a portable nature and can be carried about the person or in a brief case,. to be used as and when required for copying items of text, letters, pages from books etc.. The concept behind the present invention is that the photocopier shall be taken to the document to be copied rather than vice versa as has convention¬ ally been the case. Summary of the Invention

According to the broadest aspect of the present invention, a copier for producing a photocopy of a document comprises a portable elongate housing con¬ taining:- a roll of sensitised paper, means for electrostatically charging the paper, means for illu¬ minating the paper and forming an electrostatic image thereon, means for applying toner to the paper so as to cause toner to adhere to those areas of the sensi¬ tised paper on which a charge remains after illumina- tion and exposure to the document to be copied, and an exit slot from which a photocopy of a document will pass as it is exposed and developed, the housing further comprising drive means to cause the paper to move relative to the housing and out through the exit slit, and further means for generating a high voltage electrical discharge and for causing the source of illumination to operate. The charging and the illumination may be syn¬ chronised with the movement of the paper so that a uniform charge pattern and related lumen exposure rate is achieved .

The invention lends itself to a hand-held photocopier unit which can be located over a document or book page or the like and can be guided thereover by hand so as to illuminate successive regions of the document and produce a photocopy thereof.

Alternatively,, the invention may be fitted with a base plate to define an entry and exit gap through which a document bearing photocopyable material such as printing can pass for illumination and exposure to the sensitised paper. In this arrange¬ ment, the housing can remain static so that the only movement is of a document as it moves through the housing between the underside thereof above the 'base plate.

Drive for the paper and related facilities within the photocopier housing may be obtained by a friction drive from one or more rollers protruding below the underside of the housing which when the latter is advanced across a flat surface such as a table top or document caus rotation of appropriate members within the housing and produce relative move¬ ment of the sensitised paper and other facilities within the housing. Alternatively, the device may be actively driven across the document to be copied by wheels or rollers or other tracking devices independently of the movement of the sensitised paper, the speed of the sensitised paper moving through the device- being matched to the movement of the housing across the document. The force necessary to advance the device across a document to be copied may be provided by the operator, for example through a hand crank or rotata¬ ble knob. Alternatively, the power may be supplied by motors and batteries or even from a flying lead with or without transformer for connection to the elec¬ tricity supply mains. ,here the device is used in a stationary mode with the base plate previously referred to, drive means would be required to feed the paper through the slit between the device and the base plate.

The invention is applicable to a so-called reflex copying arrangement in which a reverse image is first formed on a first photocopier which is then sub¬ sequently re-imaged by the same apparatus to form a second photocopy, the first one being discarded, and is also applicable to a single stage reflex copying process in which appropriate paper and toner are used so that a single stage of exposure and development is required to provide a correctly handed image without ^"'the need for a preliminary photocopy which then has to be discarded.

Alternatively, single stage photocopying process could be used in which an optical system which may include a lens or lens/mirror, fibre optic imaging system, a micro-lens array and erecting prism is em¬ ployed so as to produce a correctly handed image on the sensitised paper as the copier is traversed across the document.

Where the speed of travel of the photocopier relative to the document to be copied is not necessa¬ rily constant, the charging rate, illumination rate and toning rate may, with advantage, all be carefully matched to the speed of the machine travel in order to achieve a uniform copy. This can be done mechani¬ cally using gears and -pulleys together with electrical switching. In one embodiment of the invention, the high voltage required to charge the photocopying paper is generated by a piezo-electric crystal and means is provided for repetitively stressing the crystal to generate the high voltage needed to produce the charg- ing voltage. In this arrangement, the stressing mechanism is linked mechanically to a drive mechanism for the photocopier so that irrespective of the speed of the photocopying device over the document to be copied, a high tension pulse will always be applied to he corona wire or other charging device at a pre¬ determined pitch relative to the linear movement over the document so that the sensitised paper is charged relatively uniformly.

The repetition rate at which the crystal is stressed and therefore the pitch at which the charging voltages occur is such that bands of charge along the sensitised paper join up to give a uniform overall charge.

Alternatively, the sensitised paper may be charged to saturation in which case linking is not necessary. Alternatively, the high voltage may be genera¬ ted by a suitable electronic unit, or, where the copier is powered from a mains supply, a high voltage transformer may be used.

The width of- the machine from front to back is governed by the space required to fit in the various components such as a roll of paper, a charging device for applying high voltage to the paper, an illumina¬ tion device such as a lamp and a toning station con¬ taining toner typically in the form of a finely divided powder or a liquid suspension.

Whilst charging of the sensitised paper will normally be effected before illumination, it may be preferred to employ simultaneously charging and illumination. ^•• The means for causing the toner to adhere to to the paper preferably comprises a roller that is traversed to and fro across the paper at right angles

QM to the direction of movement of the paper through the machine. The roller may be rotatably mounted upon a carriage that is guided for movement across the paper by guides that may include an arrangement for urging the roller against the paper to cause the toner to adhere to the paper.

Preferably, the carriage also supports a hopper containing toner which is transferred to the paper by means of a magnetic transfer device. Movement of the paper, after exposure, to the toner fixing roller may be controlled by an intermittently operating indexing mechanism, for example a geneva wheel. Alternatively, the paper may be allowed to form a "loop" during the periods when the roller is traversing across the paper. Yet again, a swinging roller device may be employed to take up and release "slack" in the paper upstream of the roller. In a further alternative, the paper may be advanced to the roller by an elastic roller drive for example a stretching belt drive.

The length of the machine, i.e. from left to^' right, is governed by the width of the sensitised paper which is to be made available for copying on. In addition, the width of the machine must accommo- date such components as are required at each end for supporting the roll of paper and providing drive therefor .'. Typically the side regions of the appara- tus also include the piezo electric crystal, the stressing unit and drive gear associated therewith. It may be necessary to ensure that during copying ambient light does not enter the apparatus or pass underneath to the sensitised zinc oxide paper. To this end, according to a further subsidiary feature of the invention, the lower peripheral region of the apparatus, and particularly the periphery around the opening which defines the viewing window, includes a flexible light-proofing such as velvet covered foam plastic or a dense brush material or the like.

However, if the degree of illumination is sufficiently intense with respect to ambient light, such light proofing is normally unnecessary unless very sensitive paper is used.

The present invention is essentially based on the concept that it is not necessary to simultaneously illuminate the whole of the document which is to be reproduced and that small portions of the document can be illuminated successively and viewed and exposed in succession so enabling the apparatus to be contained in a much smaller housing than has hitherto been consi¬ dered the case. Thus, a photocopier constructed in accordance with the present invention will only view a s ma 11 portion of an original document at any instant in time during the photocopying process or where the document actually passes through the apparatus, will

oι only contain a small region of the document within the apparatus at any instant in time during the photo¬ copying process. Introduction of Drawings By way of example only, an embodiment of the invention will now be described in greater detail with reference to the accompanying drawings of which:

Fig. 1 is a perspective view of the embodiment partly in diagrammatic form and with certain parts shown cut away, and,

Fig. 2 is a section on the line II-II of Fig. 1 on an enlarged scale. Detailed description of Drawings

A generally elongate housing 10 is formed from _ a main structural member 11 that extends between end walls 12. The member 11 incorporates an illumination chamber 13 that extends for the full length of the member and a charging chamber 14.

The illumination chamber 13 is of inverted channel form with walls 15, 16 contoured at their lower (as seen in the drawings) ends to receive a transparent screen or window 17 releasably secured to the walls by means not shown.

Extending forwardly from wall 15 in a substan- tially horizontal direction is a wall 18 that bounds the upper part of the charging chamber and whose extremity is separated from the lower end of the adjacent wall 15 by a gap 19 across which is located a charge bed 19a_ (Fig. 2) .

Rotatably mounted between the end walls 12 across the lower edge of the gap 19 is an elongate roller 20 that extends across from one end wall to the other.

A second elongate roller 21, also rotatably mounted between the end walls .12, lies on the other side of the illumination chamber 13 from roller 20 as can be seen from Fig. 2. Roller 21 is carried by a shaft one end of which extends through the right- hand (as viewed in Fig. 1) end wall 12 and is rotata-. ble by an electric drive motor 22 via a suitable drive shown in Fig. 1 as a gear train 23. The motor 22 is mounted upon the right-hand end wall 12 and is powered by batteries shown diagrammatically at 24 and supported between the end walls 12.

As can be seen from Fig. 1, the lower face of the transparent screen 17 viewed end-on lies approxi¬ mately tangential to the rollers 20, 21 although the latter project very slightly beyond the lower face to enable the copier to be advanced across a surface as will be described in more detail below. ^"" The end walls 12 are also formed to receive a shaft on which is mounted a roll 25 of sensitised paper of which more detail is given below. Supported between the end walls 12, is a toner applicator and fixing device comprising spaced rails 26, 27 between which a carriage 28 is traversed to and fro by means of a drive (not shown) from the motor 22. At both ends, the rails pan through the end walls 12 and, on the remote side of the latter walls, the rails 26, 27 are coupled together by pairs of levers of which the pair at one end only are shown in Fig. 1. The pair comprises right-angled levers 29, 30 pivoted at 31 to rail 27 and carrying between them a roller 32 that bears on rail 26 as shown. An adjustable spring 33 located between an abutment surface 34jaon rail 27 and projecting ends of the longer arm of the levers 29, 30. There is a somewhat similar linkage at the other ends of the rails 26, 27, the arrangement being such that, assuming rail 27 to be fixed, rail 26 is movable to a limited extent towards and away from rail 27 yet main¬ tains a parallel position with respect to rail 27.

The carriage 28 is guided for movement along rail 26 by guide wheel (not shown) and has rotatably mounted upon it a roller 34 urged towards rail 27 by rail 26 and the action of spring 33.

Also carried by the carriage is a removable hopper 35 for toner powder and a powder transfer device (not shown) consisting of multiple pole magnet rotatably mounted within a cylindrical brass or aluminium housing.

C_,ι I The drive to the carriage is such that the ^' latter is traversed to and fro between set limits along the rails 26, 27.

More details of the carriage and the drive therefor are given in U.K. Patent Specification No. 82.22451. A further example of a traversing carriage system is found in U.S. Patent Specification No. 4,305,330 although in this case the carriage does not incorporate a toner hopper with a toner applicator. Also powered from the battery 24 are electric bulbs 36 mounted as shown in the wall 15 of the illumination chamber 13. The bulbs ^'36 are so spaced that, in conjunction with reflectors 37 even illumina¬ tion of the screen 17 is obtained. On its outside face, the right-hand wall 12 supports an electronic EHT unit, shown schematically as block 38, that converts the output of the battery 24 into a high potential suitable for charging the sensi¬ tised paper. Stretched along the charging chamber 14 is a corona wire 39 joined to the high potential output of the electronic unit.

Associated with roller 26 is a pinch roller 40, rotatably supported between the end walls 12 and is biassed against roller 21 by resilient means (not ^"shown).

As can be seen from Fig. 2, rail 27 has a lateral flange 41 that extends for the full length of the rail and projects downwardly and is aligned with the nip between rollers 21 and 40. A further nip roller 42 positioned as shown in Fig. 2 is resiliently urged towards the flange 41. The end walls 12 have detachably secured to them end covers 43 whilst extending between the end walls are side cover plates 44, the lower edges of which terminate adjacent the respective rollers 20 and 21 as shown and are fitted with rows of bristles 45. A top cover plate 46 is hinged to the forward side plate at46a giving access to components described above for example to enable a user to insert a roll of paper, to remove and replace the batteries and to remove and replenish the. hopper of the carriage 28. The embodiment just described is suitable for copying documents of A4 size and below and is sized accordingly. The EHT unit is capable of delivery to the corona wire 39 a current within the range of from about 20-4OμA at 8Kv. The bulbs 36 are of fwatt rating. The motor is geared down by the gear train 23 to rotate roller 21 at a speed sufficient to allow the machine to advance across a surface at a speed of about 2 cm per second.

The copier described is also intended to pro- ^" duce a right reading copy so sensitised paper of the right reading reflex type is required. Paper of that type is described in European Patent Specification No. 82.300091.4. Such paper comprises basically a sub¬ strate of a light-transmitting material coated on one face by a directly applied layer of photoconductive mat¬ erial. A further layer of electrically insulating mat- erial may be applied to the other face of the substrate. The substrate may be that known under the Trade Name GLASSINE a preferred type being the so-called bleached GLASSINE type N802,

The photoconductive material may be zinc oxide. Before using a user loads the copier with a roll of sensitised paper, the sensitised layer being on the inside face and threads the paper passed over the inside face of the charge bed 19a, round the roller 20, underneath the screen 17, through the nip of rollers 21 and 40 and between roller 42 and the surface of flange 41 and out of the machine through a gap between the edge of the cover 43 and the adjacent side plate 44.

A document to be copied is then placed on a level surface and the copier is then located adjacent the bottom edge of the document and the motor 22 switched on by a control (not shown). The copier is then allowed to advance, under guidance if necessary from the user, across the surface of the document to be copied. Switching on the motor also energises the bulbs 36 and the EHT unit. In addition, the carriage 28 starts to traverse between the rails 26, 27.

!, On leaving the roll 25 the paper passes over the charging bed 19a where it is charged to a high potential (about 8Kv) by the corona wire 39. The charged paper then passes beneath the screen 17 where it is exposed whilst in contact with a part of the surface of the document to be copied. After passing through the nip of rollers 21 and 40 and then between roller 42 and flange 41, the charged, exposed paper is then toned by toner transferred from the hopper 35 carried by the carriage 28. After being toned, the paper passes beneath the roller 34 as the latter moves to and fro. The pressure exerted on the toned paper by the roller 34 fixes the toner.

When the copier has moved along the entire length of the paper, the copy can be torn off by pull¬ ing the paper across a knife edge 47 and the motor is switched off.

In Fig. 1, the path of the paper is shown by a dotted line but in Fig. 2 it is indicated by the full line 48.

Movement of the paper through the copier is effected by roller 21 that is driven by the motor and acts in conjunction with the nip roller 40. Movement of the paper over the document to be copied advances the copier along that document.

It will be observed that the paper is advanced at a constant rate up to roller 42 but thereafter is advanced intermittently at the end of each traverse of roller 34 across the paper. At the end of each tra¬ verse the roller 34 moves off the paper and the latter is fed forward. The roller 34 is traversed at a rate that ensures complete coverage of the paper. During the periods that the roller is in contact with the paper a "loop" 49 tends to build up between rollers 21, 40 and roller 42.

The bristles 45 help to reduce the ingress of ambient light into the machine and this helps to ensure a good copy.

Other means of progressing the paper passed the carriage 28 may be employed. For example, an indexing geneva wheel drive may be included between the rollers 21, 40 to advance the paper positively at the end of each traverse of the roller 34 across the paper.

Yet again, a swinging roller to allow looping of the paper and pay-out thereof may be used or an elastic drive for example a stretching belt drive that stretches while the paper is stationary and contracts to advance the paper at the appropriate time.

In another embodiment of the invention, the charging potential is obtained from one or more piezo¬ electric crystals instead electronically as described above. Preferably, a pair of crystals is used to pro¬ duce a balanced assembly, one crystal being loaded as the other is relieved. The crystals may be loaded by cams driven by the motor 22 or a manual drive opera¬ ted by the user may be adopted. In the latter case, the manual* drive will also drive the roller 21 to progress the paper through the copier and the latter across the surface of a document to be copied.

The crystals are loaded and relaxed in syn¬ chronism with the rate of advance of the copier to give uniform charging of the paper as it passes across the charging bed 19a_. A suitable piezo-electric crystal unit is described in U.K. Patent Specification No. 82.23656.

The copier may alternatively operate by simul¬ taneous charging and exposure of the paper by incor¬ porating a charging wire in the illumination chamber. This method may require a conductive layer on the sensitised paper as is described above.

In another embodiment, an illumination chamber is employed having a window at one end across which the charged paper is passed and on to which is focussed an image of the respective part of the document to be copied. Focussing is achieved by a suitable optical- system which may take one or other of the forms des¬ cribed above so arranged to produce a "positive" image on the charged paper. ^•

Claims

Claims :

1. A copier for producing a copy of a docu¬ ment comprising a portable elongate housing containing a roll of sensitised paper, means for electrostatically

5 charging the paper, means for illuminating the charged paper and forming an electrostatic image thereon, means for applying toner to the charged, exposed paper and for fixing the toner after application, and an exit slot from which the copy emerges.

10 2. A copier as claimed in claim 1 in which the housing also contains drive means for advancing paper from the roll passed the charging means, the illuminating means, the toner applying and fixing means to the exit slot.

15 3. A copier as claimed in claim 1 or 2 in which the copier is advanced across the surface of the document to be copied by the paper advancing from the roll to the exit slot.

4. A copier as claimed in claim 1, 2 or 3 in 20 which the illuminating means comprises an illuminating chamber having in one wall thereof an elongate window through which, in use, is visible a part of the document to be copied.

5. A copier as claimed in claim 1, 2, 3 or 4 „ 25 .in which the housing includes an entry and an exit gap through which a document to be copied is, in use, fed.

6. A copier as claimed in claim 1 or 2 in which the drive means also advances the copier across the surface of a document to be copied.

7. A copier as'claimed in any one of the preceding claims in which the housing provides accommo- dation for an electric power unit to power the drive means.

8. A copier-as claimed in claim 7 in which the power unit comprises batteries and an electric motor and in whi ch the batteries alos power the illumination means.

9. A copier as claimed in claim 1 in which the charging means comprises a corona wire charged by a high tension unit powered from the batteries.

10. A copier as claimed in claim 6 in which the charging means comprises a corona wire charged from piezo-electric crystal means, and in which the dirve means is powered by a hand-operated drive that also actuates the piezo-electric crystal means.

11. A copier as claimed in claim 7 in which the charging means comprises a corona wire charged from piezo-electric crystal means, and in which the ^" latter is actuated by the electric motor.

12. A copier^' as claimed in any one of the preceding claims in which the toner applying toner comprises a hopper, means for traversing the hopper across the paper and an arrangement for transferring toner from the hopper to the paper.

13. A copier as claimed in claim 12 in which the hopper is mounted upon a carriage which also carries a roller that is rolled across the toned paper to fix the toner.

14. A copier as claimed in claim 13 when appended to claim 6 and in which the carriage is traversed across the paper by. the drive means.

15. A copier as claimed in claim 1 in which the housing includes means for rotatably supporting the roll of paper with its rotational axis disposed along the housing, and in which the charging means is located beneath the roll and is adjacent the illumina¬ tion means, the toner applying and fixing means being positioned adjacent the roll and above the illumination means.

16. A copier substantially as herein described with reference to and as illustrated by the accompany¬ ing drawings.