US3746442A

US3746442A - Electrophotographic imaging apparatus

Info

Publication number: US3746442A
Application number: US00201503A
Authority: US
Inventors: J Davidson
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1971-11-23
Filing date: 1971-11-23
Publication date: 1973-07-17
Anticipated expiration: 1990-07-17
Also published as: NL7213339A

Abstract

Electrophotographic apparatus in which the scanning assembly for providing light reflections from a document to be reproduced onto an electrophotographic recording surface is provided with a light reflective shield which is automatically moved by inertia between the light source and the document holder during the return scan to ensure the reflection of sufficient light onto the recording surface during the return scan and thereby effectively discharge the recording surface.

Description

United States Patent 1 Davidson 1 July 17, 1973 1 ELECTROPHOTOGRAPHIC IMAGING APPARATUS {75] Inventor: James R. Davidson, Rochester, NY.

[73] Assignee: Xerox Corporation, Stamford, Conn.

22 Filed: Nov. 23, 1971 [21] Appl. No.: 201,503

[52] U.S. Cl. 355/3, 355/8 [51] Int. Cl 603g 15/00 [58] Field of Search 355/3, 8

[56] References Cited UNITED STATES PATENTS 3,632,203 1/1972 Kolibas 355/8 3,062,108 11/1962 Mayo 355/8 3,382,360 5/1968 Young et al 355/3 X 2,889,758 6/1959 Bolton 355/8 X OTHER PUBLICATIONS H. C. Medley, Electrophotographic Copier", IBM

Technical Disclosure Bulletin; Vol. 9, No. 11; April, 1967; page 1522.

Primary Examiner-Samuel S. Matthews Assistant Examiner-Kenneth C. Hutchison Attorney-James J. Ralabate, Thomas .1. Wall et :11.

[57] ABSTRACT Electrophotographic apparatus in which the scanning assembly for providing light reflections from a document to be reproduced onto an electrophotographic recording surface is provided with a light reflective shield which is automatically moved by inertia between the light source and the document holder during the return scan to ensure the reflection of sufficient light onto the recording surface during the return scan and thereby effectively discharge the recording surface.

8 Claims, 2 Drawing Figures Pnmwwm 3.746.442

' sum 2 0F ,2

' INVENTOR James R. Davidson ATTORNEYS ELECTROPHOTOGRAPHIC IMAGING APPARATUS BACKGROUND OF THE INVENTION This invention relates to an apparatus for projecting a light image onto a moving surface and more particularly, to an apparatus for reflecting a light image onto an electrophotographic surface.

Electrostatography is exemplified by the basic electrophotographic process taught by C. F. Carlson in U.S. Pat. No. 2,297,691, which involves placing a uniform electrostatic charge on a photoconductive insulating layer, exposing the layer to a light and shadow image to dissipate the charge on the areas of the layer exposed to the light and developing the resulting latent electrostatic image by depositing on the image a f'mely-divided electroscopic material referred to in the art as toner. The toner is normally attracted to those areas of the layer which retain a charge, thereby fonning a toner image correspondingto the latent electrostatic image, which may then be transferred to a support surface, such as paper. The transferred image is generally per manently affixed to the support surface by heating, although other suitable fixing means, such as solvent or overcoating treatment, may be substituted for the heat fixing step. I

In automatic electrophotographic reproducing machines generally used in the art, the recording surface is in the form of a rotating drum which is rotated past a charging station at which a uniform electrostatic charge is placed on the recording surface; an imaging station at which a flowing image is projected onto the recording surface from a stationary original to produce an electrostatic latent image on the recording station; a development station at which the electrostatic latent imageis rendered visible, as a powder image, by the use of a suitable toner; a transfer station at which the powder image is transferred from the recording surface to a suitable support. material; and a cleaning station at which residual powder'is removed from the recording surface. g I l In such machines there is aneed to discharge the-recording surface between imaging cycles in order to prevent the depositof excess toner onto the recording surface which both wastes toner and places a heavy load on the cleaning system.- In machines which employ, at the imaging station, a scanning assembly which scans across a stationary document to be reproduced to provide light reflections from the document which are then focussed onto the recording surface to thereby provide an electrostatic latent image of the document on the recording surface, it has been proposed to keep the lights on during the return scan whereby light reflected onto the recording surface during the return scan of the light source discharges the recording surface. In such an operation, the light available for discharging the recording surfaceis either that reflected from the document, if left in position, or that from the open platen, if the document is removed. In the reproduction of line copy, there may be enough light reflected to provide the required discharge, but in solid area development, the amount of light reflected is generally insufficient to provide for effective discharge of the recording surface.

SUMMARY OF THE INVENTION An object of this invention is to provide for an improved apparatus for projecting a light image onto a moving surface.

Another object of this invention is to provide an improved apparatus for projecting a light image onto a moving electrophographic recording surface.

A further object of this invention is to provide an improved apparatus for projecting a light image onto a movingelectrohpotographic recording surface which effectively discharges the surface between imaging cycles.

These and other objects of the invention should be more readily apparent from reading the following descriptiori thereof.

In brief, the objects of the present invention are accomplished by an apparatus which includes a copy holder for supporting copy, a light receiving surface for receiving light reflectionsfrom the copy holder, a light source, a movable means to transverse back and forth across the surface of the copy holder to provide light reflections from the copy holder onto the light receiving surface during movement thereof and means for providing a reflective surface between the light source and the copy holder during movement of themovable means in one of said back and forth directions, whereby light is reflected from the reflective surface onto the light receiving surface during movement of the movable means in said one of said directions.

The present invention is particularly applicable to an electrophotographic apparatus in which moving light is reflected from subject matter to be reproduced onto an electrophotographic recording surface in that during return movement of the light across the subject matter to be reproduced, light is reflected from a reflective surface onto the recording surface, thereby, ensuring the presence of sufficient light to provide for effective discharge of the recording surface.

More particularly, there is provided a movable car riagewhich moves transverselyacross a document to be reproduced in one direction from a first position to a second position and in the opposite direction from the second position to the first position to cause light from a light source to move transversely across the document. During movement of the carriage from the first to second position, light reflections from the document are focussed onto the recording surface to produce an electrostatic latent image. A light reflective shield is supported by a support means connected to the carriage for movement with and relative to the carriage. The support means supports the shield during movement of the carriage from its first position to its second position for movement with the carriage at a first shield position at which the shield does not interfere with the reflection of light from the document onto the recording surface. Upon the carriage reaching its second position and changing direction for movement from the second position to the first position, the shield continues to move, by inertia, and the support means supports the shield for movement to a second shield position at which the shield is between the light source and the document, whereby light from the light source is reflected from the shield onto the recording surface. The

, support means supports the shield, at the second shield position, for movement with the carriage from its second position to its first position, and upon the carriage manner, the light reflective shield is between the light source and the document during the return scan to ensure reflection of sufficient light onto the recording surface.

The light source may be stationary or may be fixed to the carriage for relative movement therewith. The carriage, if supporting the light source, may or may not be provided with an aperture for directing light from the light source onto the document.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a rear elevation of an electrophotographic machine embodying the present invention; and

FIG. 2 is an elevation view of the scanning device of the machine of FIG. 1.

DESCRIPTION OF AN EMBODIMENT OF THE INVENTION As shown schematically in FIG. 1, the automatic reproducing apparatus comprises an electrophotographic plate 11 including a photoconductive layer or light receiving surface on a conductive backing and formed in the shape of a drum, which is mounted on a shaft journaled in a frame to rotate in the direction indicated by the arrow to cause the drum surface sequentially to pass a plurality of processing stations.

For the purpose of the present disclosure, the several processing stations in the path of movement of the drum surface may be described functionally, as follows:

A charging station, at which a uniform electrostatic charge is deposited on the photoconductive layer of the drum;

An exposure station, at which a light or radiation pattern of copy to be reproduced is projected onto the drum surface to dissipate the drum charge in the exposed areas thereof and thereby form a latent electrostatic image of the copy to be reproduced;

A developing station, at which a developing material including toner particles having an electrostatic charge opposite to that of the electrostatic latent image are cascaded over the drum surface, whereby the toner particles adhere to the electrostatic latent image to form a powdered image in the configuration of the copy being reproduced;

A transfer station, at which the powder image is electrostatically transferred from the drum surface to a transfer material of a support surface; and,

A drum cleaning and discharge station, at which the drum surface is brushed to remove residual toner particles remaining thereon after image transfer.

As shown, the charging station indicated by reference character 18, includes a corona charging device 130 which includes a corona discharge array of one or more corona discharge electrodes that extend trans versely across the drum surface and are energized from a high potential source and are substantially closed within a shielding member, such as disclosed in U.S. Pat. No. 2,778,946.

Position next and adjacent to the charging station is an exposure station generally designated 12.

At the exposure station is a hood or bellows or other shield 21 adapted to protect the recording surface from extraneous light and having a slit 22 at its lower portion adjacent to the surface. The upper end of this shield 21 is open to receive an optical image from a master or original as described hereinafter. Closely adjacent but spaced from the shield and positioned above it is a slotted track 24 on which is mounted a carriage 25 supporting and carrying a lens 26 which is thereby movable above and across the upper end of the shield 21. Spaced above this track 24 is a second track 28, likewise bearing a carriage 29, which carriage has a transverse slit 30 extending thereacross. Preferably, for ease of motion, both of these carriages may be mounted on balls 27 and wheels 31, respectively, or other means or mechanism may be employed to cause these carriages to move or slide easily and smoothly along their track.

Positioned abovethe upper track 28 is a fixed support 20 consisting, for example, of a copy board 33 which may consist of a transparent plane member such, for example, as a glass plate or the like, which is adapted to receive a master or original placed face downward, on its upper surface, in position for having its image projected through the lens onto the sensitive surface of the cylinder 11, and positioned over the copy board 33 is a flexible copy cover 23, made, for example, of plastic, for holding copy flat against the upper surface of the copy board.

In order to provide for correlated motion of the lens carriage 25 and slit-provided carriage 29 in their travel across the

respective tracks

24 and 28, whereby an optical image from the original placed face downwardly on copy board 33 can be projected onto the photosensitive surface of the cylinder 11 in proper coordination with the rotation of the cylinder, there is provided a carriage actuating mechanism. The mechanism includes a a tape 41 for carriage 25 which passes over freely movable wheels 44 positioned in line with track 24 and extending therebeyond to a carriage return mechanism which may, for example, be a weight 45 suspended at the free end of tape 41. In a similar manner a tape 42 for carriage 29 passes over freely movable wheels 46 in line with track 28 and is secured to a return mechanism which likewise may suitably be a weight 47 secured to the free end of tape 42 after it passes over wheel 46. Tapes 41 and 42 in turn are secured by fasteners 48 to

carriages

25 and 29, respectively, whereby linear motion of the tapes draws the carriages along their tracks at a corresponding rate of speed. The tapes 41 and 42, at their other ends (not shown) are secured to the circumference of

pulleys

38 and 39, respectively, which are drivingly connected through a suitable drive mechanism (not shown) to the drum 1 1 to effect movement of the

carriages

25 and 29. The drive mechanism is constructed in a manner such that pulley 39 is driven over a distance equal to the maximum length of copy which is to be produced from the original on copy board 33 and such that carriage 25 is drawn across its track at a speed equal to about onehalf of the surface speed of drum 1| and carriage 29 is drawn across its track at a speed equal to drum ll. Upon completion of the drive motion, the carriage re turn mechanisms; i.e., weights 45 and 47, return the carriages to their original positions in preparation for another cycle of operation. It is apparent, therefore, that during the drive phase of the cycle an optical image from the original placed on copy board 33 is projected through lens 26, such projected image passing through slit 22 onto the surface of cylinder 11 in mirror image relation such that the image received by the moving cylinder surface is a true projected image of the original to be copied.

In the case of slit projection, it is important that uniform lighting be provided during the projection. The

source of light 9, which may be incandescent lamps, as shown, or fluorescent lamps, is suitably located to provide for reflected-back or opaque projection between the lens and the original to be copied. It is desirable to illuminate all areas of the slit uniformly during all parts of the cycle of projection. Accordingly, the lamps or other source of light 9 are preferably connected by brackets with the movable carriage 29 carrying the slit 30 so that movement of the carriage and slit results in corresponding movement of the light, resulting in uniform lighting of the slit at all times.

It is to be noted that the apparatus described herein may be used for reproductions of the same size as the original or for larger or smaller sizes as may be desired. When one-to-one reproductions are to be made, the lens will be positioned halfway between the photographically sensitive moving surface and the original to be copied. When smaller reproductions are desired, then the lens is positioned closer to the photographic surface than to the original. For example, when the lens is located at one-third the distance from the surface to the original, then a reduction in the reproduction to one-half is accomplished. In the opposite way, larger reproductions may be produced.

In the copying machine herein described, when adjustment of the spacing of the lens between the sensitive surface and the original is made, the linear distance of travel of the lens carriage 25 and the carriage 29, provided with a transverse slit, should also be correspondingly adjusted. For example, when the lens is positioned one-third the distance from the plate to the fixed position of the original as when a half-sized repro= duction is desired, the lens should move one-third of the distance that the slit moves through. The rate of speed of the lens to that of the motion of the slit must therefore be adjusted accordingly. In the machine designing of thesize of gear wheels or the

pulleys

38 and 39. Automatic means'controlling the movement of the lens and the slit under these different circumstances may be provided so that simple and expedient means maybe used to produce, respectively, one-to-one reproduction, enlargements and reductions using the slit exposure system shown. As a general rule, the slit should be small with respect to the diameter of the drum. It has been found that, in the case of a to 30 inch diameter drum, the slit may be adjusted up to one inch to achieve proper radiation intensity.

The details of such an exposure station, including the drive mechanism is disclosed in more detail in U.S. Pat. No. 3,062,094, which is hereby incorporated by reference.

Adjacent to the exposure station is a developing station in which there is positioned a developer apparatus 60 including a casing or housing having a lower or sump portion for accumulating developer material. A bucket type conveyor 66 is used to carry the developing material to the upper part of the developer housing where it is cascaded over a hopper chute onto the drum to effect development. A toner dispenser is used to ac-.

curately meter toner to the developing material as toner particles are consumed-during the developing operation. The developing station is provided with a development electrode 67 for enhancing solid area development.

Positioned next and adjacent to the development station is a copy-feeding station provided with suitable scribed, this adjustment may be effected by suitable desheet-feeding mechanism adapted to feed sheets of paper successively to the cylinder 11 in coordination with the presentation of the developed image at the copy-feeding station. This sheet-feeding mechanism includes a sheet source 81 such as a tray for a plurality of sheets 82 of a suitable transfer material that is, typically, sheets of paper or the like and a pair of

feed rollers

83 and 84 adapted to direct the sheet material into contact with the rotating drum at a speed preferably slightly in excess of the rate of travel of the surface of the drum.

Preferably, at the exact point of contact between the sheet material and the rotating drum, a transfer station 16, consisting of a corona discharge electrode, is positioned to effect transfer of the developed image from the cylinder surface to the sheet material. The transfer electrode consists essentially of one or more corona discharge wires 97 and control electrodes 99 positioned and disposed above a ground plate 98 substantially similar to the discharging electrode 18 to be described hereinafter. The sheet-feeding and transfer mechanism are similar to the type disclosed in Mayo et al., U.S. Pat. No. 2,684,902, filed Nov. 23, 1951.

Immediately subsequent to the transfer station 16 are positioned strip fingers 101 which are adapted to be brought into contact with the surface of the cylinder 1 l slightly in advance of the sheet material and to strip the sheet material from the cylinder surface, directing the free sheet material into a fixing mechanism generally designated 105 and further defined in U.S. Pat. No. 2,701,765. The fixing apparatus consists essentially of a heated rotating drum 111 and a corona discharge electrode 112 or the like, spaced closely adjacent thereto and adapted to receive the sheet material'therebetween, whereby the sheet material is secured by electrostatic adhesion to the surface of the heated drum, and the developed and transferred image is fixed thereon by conducting heating from the surface of the drum through the sheet transfer material. Sliding pickoff fingers 116 serve to pick the sheet material from the surface of heated drum 1 1 l and direct it into a tray 1 17 wherein the completed xerographic print is collected and stored.

Positioned next subsequent to the transfer and pickup station-is a cleaning station generally designated 17, at which is disposed cylindrical brush 121 rotatively mounted, for example, on axle 122 and adapted to be driven by a motor 123 operating through belt 124. The entire cleaning section is mounted within a housing 125 with a sub-housing or hood 126 surrounding the cylindrical brush. The cylindrical brush may consist, for example, of rabbit fur secured on the surface of a solid or structural cylinder 127 and be rotated in a direction opposite to the direction of rotation of the cylinder surface at the point of contact, so that the relative motion between the brush surface and the cylinder surface is the sum of the two separate speeds of motion. A filter member 128 may be positioned in one wall of the hood, preferably the lower wall thereof, to permit passage of air therethrough but at the same time to collect dust or electroscopic particles removed from the surface of the cylinder by the brush. The brush fibers, due to the high centrifugal force caused by the rotating motion, extend outwardly until they reach in contact with the cylinder surface and are depressed thereby. Immediately upon release, the brush fibers extend outwardly again from the surface, thus causing a vane-like action which causes a flow of air into the hood area at the space between the hood and the cylinder and out through filter 128. In this manner, a constant flow of air serves to free the brush fibers from electroscopic particles picked up by the cleaning action and thus to maintain absence of dust in the surrounding atmosphere. If desired, this air flow action may be supplemented through the use of a supplemental vacuum flow from an air blower or the like (not shown).

It is believed that the foregoing description is sufficient for the purposes of this application to show the operation of an electrophotographic reproducing apparatus using the subject matter of the present invention. The details of such a machine are further described in the aforementioned U.S. Pat. No. 3,062,094.

Referring now to FIG. 2 which further illustrates the subject matter of the present invention the carriage 29 is provided with a movable light reflective shield 201, having a light reflective surface 201a which is supported beneath the carriage 29 between the lamps 9 and the carriage 29 by a low friction support means in the form of four pairs of longitudinally spaced guide rollers 202 which are suitably journaled in a horizontal plane parallel to the plane of the copy holder 33. The movable light reflective shield is freely supported between each of the two rollers forming the pairs of rollers designated 202 for longitudinal movement between a position in which the shield 201 is completely beneaththe carriage 29 whereby the slit 30 is fully open, and a position in which the shield covers slit 30, whereby light from the lamps 9 is reflected from the shield 201 onto the surface of drum 11. The carriage 29 is further provided with stop means 205 and 206 formed of a suitable energy absorbing material which prevents rebound, the stop means 205 limiting forward movement of the shield 201 and the stop means 206 limiting rearward movement of the shield 201. The size of the shield 201, the spacing of the pairs of rollers 202, and the positioning of the stop means 205 and 206 are coordinated to provide two point support for shield 201 over its entire path of travel, and to ensure that the shield 201, in one of its two positions, covers slit 30 and in the other of its two positions, does not block slit 30.

In operation, as the carriage 29 moves forward (to the right in F 1G. 1 the shield 201, as a result of inertia, remains at rest with respect to carriage 29 supported between the rollers 202 positioned at the rearward end of carriage 29 and moves with carriage 29, whereby the slit 30 remains completely uncovered during forward movement of the carriage 29 and light is reflected from the document on copy holder 33 onto the surface of drum 11. When the carriage 29 reaches the end of its forward path, as a result of inertia, the shield 201 continues to move forward until brought to a complete stop by stop means 205, at which point the shield 201 is supported between the forward roller pairs 202, whereby the slit 30 is covered by shield 201 and light is reflected from the reflective surface of shield 201 onto the surface of drum 11. The shield 20], now at rest against stop means 205, moves with carriage 29 during rearward movement thereof (to the left in FIG. 1), and its reflective surface 201a reflects a maximum amount of light onto the surface of drum 11.

When the carriage 29 reaches the end of its rearward path, as a result of inertia, the shield 201 continues to move rearward, until being stopped by stop means 206 at which point the shield 201 is supported between the rearward roller pairs 202 against stop means 206, whereby the slit 30 is completely uncovered and the carriage 29 can once again scan a document on holder 33 without interference from shield 201.

It should be readily apparent that movement of the shield 201 is completely automatic depending entirely on its own inertia and the direction of motion of the scanning carriage.

Numerous modifications and variations of the hereinabove described embodiment are possible within the spirit and scope of the invention.

Thus, for example, although the embodiment has been particularly described with reference to a light source which moves with the scanning carriage, a fixed light source, as described in US. Pat. No. 3,062,094 may also be employed, with the movable light source being preferred.

As another modification, the shield could be positioned to partially block the portion of light between the light source and copy holder, although complete interference, as shown, is preferred.

As a further modification, the light may be applied to the document to be reproduced without the use of an aperture in the scanning carriage.

Similarly, although the embodiment has been particularly described with reference to a recording surface in the form of a drum, the recording surface may take another form, such as a movable belt.

The embodiment has been particularly described with referemce to cascade development, but other development techniques, such as magnetic brush, fur brush, etc., may also be employed.

These and other modifications should be apparent to those skilled in the art from the teachings herein.

The present invention is particularly advantageous in that the amount of light reflected onto the recording surface during the return scan is not dependent on the document in the copy holder, whereby sufl'lcient light is reflected onto the recording surface during the return scan, even during solid area development. In addition, the light reflective surface is automatically moved between the copy holder and the light source during the return scan without the use of complex equipment.

These and other advantages should be apparent to one skilled in the art from the teachings herein.

Numerous modifications of the present invention are possible in light of the above teachings and, therefore, within the scope of the appended claims the invention may be practiced other than as particularly described.

What is claimed is:

1. An apparatus for projecting a light image onto an electrophotographic recording member, comprising:

a copy holder for supporting an original;

a electrophotographic recording member for receiv' ing light reflections;

a light source;

a movable scanner means for scanning light from the light source across said copy holder in a forward scan direction to reflect light from an original supported on said copy holder onto said electrophotographic member to produce an electrostatic latent image thereon:

a light reflective shield; and

means for supporting said light reflective shield between the light source and the copy holder during return movement of said scanning means to reflect light from said light source onto said electrophotographic member.

2. The apparatus of claim 1 wherein said support means movably supports said light reflective shield on said movable scanning means in first and second shield positions, said support means supporting said light reflective shield on said movable scanning means in the first shield position to permit light to be reflected from an original on said copy holder onto the electrophotographic recording member during movement of said movable scanning means in a forward scan direction and said supporting means supporting said light reflective shield on said movable scanning means in said second shield position between the copy holder and the light source during return movement of said movable scanning means.

3. An apparatus for projecting a light image onto an electrophotographic recording member, comprising:

a movable electrophotographic recording member for receiving light reflections;

a light source;

a copy holder for supporting an original;

a movable scanning means mounted for movement with respect to said copy holder in forward and return scan directions, said scanning means in said forward scan direction reflecting light from an original supported on said copy holder onto said electrophotographic recording member to produce an electrostatic latent image thereon;

a light reflective shield;

support means supporting said light reflective shield 'on said scanning means in both first and second shield positions and for movement between the first and second shield positions, said support means supporting said shield in the first shield position to permit light to be reflected from an original on said copy holder onto the recording member during movement of the scanning means in the forward scan direction, said shield moving to the second shield position at the end of movement of said scanning means in the forward scan direction, said support means supporting said shield in the second shield position between the copy holder and the light source during movement of the scanning means in the return scan direction to relfect light from said light source onto the electrophotographic recording member, said shield moving to the first shield position at the end of movement of said scanning means in the return scan direction.

4. The apparatus of claim 3 wherein the support means comprises a plurality of support rollers journaled to said movable scanning means: said shield being supported on said support rollers in the first and second shield positions and during movement therebetween; and first and second stop members, said first stop member stopping movement of the shield on said rollers at the first shield position and said second stop member stopping movement of the shield on said rollers at the second shield position, said shield, by inertia, remaining at rest at the first shield position for movement with the movable scanning means during movement in forward scan direction, upon the movable scanning means ending travel in said forward scan direction, said shield, by inertia, moving on said support rollers until stopped by said second stop member at the second shield position, said shield, by inertia, remaining at rest at the second shield position for movement with the movable scanning means during movement in the return scan direction and upon the movable scanning means stopping travel in said return scan direction, said shield, by inertia, moving on said support rollers until stopped by said first stop member at the first shield position.

5. An apparatus for projecting a light image onto an electrophotographic recording member, comprising:

a copy holder for supporting an original; a movable electrophotographic recording member; a light source; a movable scanning carriage for scanning light from the light source across said copy holder; means to move said carriage across said copy holder in a first direction from a first carriage position to a second carriage position and in a second direction opposite to the first direction from said second carriage position, to said first carriage position; a light reflective shield, and support means for said shield connected to said carriage, said support means supporting said shield in a first shield position for movement with said carriage from the first carriage position to the second carriage position, said shield in said first shield position permitting light to pass from the light source to said copy holder whereby said carriage scans light across an original on said copy holder to reflect light from an original onto said recording member and produce an electrostatic latent image, said support means supporting said shield for movement, by inertia, from the first shield position to a second shield position upon the carriage reaching the second carriage position, said shield in said second shield position being between the light source and the copy holder whereby light is refelected by the light shield onto the recording member, said support means supporting said shield in said second shield position during movement of the carriage from the second carriage position to the first carriage position, said support means supporting said shield for movement, by inertia, from the second shield position to the first shield position upon the carriage reaching the first carriage position.

6. The apparatus of claim 5 wherein the recording member is an annular member.

7. The apparatus of claim 6 wherein the light source is connected to the carriage for movement therewith.

8. The apparatus of claim 5 wherein the support means comprises a plurality of support rollers journaled to said movable carriage, said shield being supported on said support rollers in the first and second shield positions and during movement therebetween; and first and second stop members, said first stop member stopping movement of the shield on said rollers at the first shield position and said second stop member stopping movement of the shield onsaid rollers at the second shield position, said shield, by inertia, remaining at rest at the first shield position for movement with the movable carriage during movement of the movable carriage in the first direction, upon the movable carriage stopping travel in said first direction at the second carriage position, said shield, by inertia, moving on said support rollers in said first direction until stopped by said second stop member at the second shield position, said shield, by inertia, remaining at rest at the second shield position for movement with the movable carriage during movement of the movable carriage in the second direction and upon the movable carriage stopping travel in said second direction at the first carriage position, said shield, by inertia, moving on said support rollers in said second direction until stopped by said first stop member at the first shield position.

1 t t i Q!

Claims

1. An apparatus for projecting a light image onto an electrophotographic recording member, comprising: a copy holder for supporting an original; a electrophotographic recording member for receivIng light reflections; a light source; a movable scanner means for scanning light from the light source across said copy holder in a forward scan direction to reflect light from an original supported on said copy holder onto said electrophotographic member to produce an electrostatic latent image thereon: a light reflective shield; and means for supporting said light reflective shield between the light source and the copy holder during return movement of said scanning means to reflect light from said light source onto said electrophotographic member.

3. An apparatus for projecting a light image onto an electrophotographic recording member, comprising: a movable electrophotographic recording member for receiving light reflections; a light source; a copy holder for supporting an original; a movable scanning means mounted for movement with respect to said copy holder in forward and return scan directions, said scanning means in said forward scan direction reflecting light from an original supported on said copy holder onto said electrophotographic recording member to produce an electrostatic latent image thereon; a light reflective shield; support means supporting said light reflective shield on said scanning means in both first and second shield positions and for movement between the first and second shield positions, said support means supporting said shield in the first shield position to permit light to be reflected from an original on said copy holder onto the recording member during movement of the scanning means in the forward scan direction, said shield moving to the second shield position at the end of movement of said scanning means in the forward scan direction, said support means supporting said shield in the second shield position between the copy holder and the light source during movement of the scanning means in the return scan direction to relfect light from said light source onto the electrophotographic recording member, said shield moving to the first shield position at the end of movement of said scanning means in the return scan direction.

5. An apparatus for projecting a light image onto an electrophotographic recording member, comprising: a copy holder for supporting an original; a movable electrophotographic recording member; a light source; a movable scanning carriage for scanning light from the light source across said copy holder; means to move said carriage across said copy holder in a first direction from a first carriage position to a second carriage position and in a second direction opposite to the first direction from said second carriage position, to said first carriage position; a light reflective shield, and support means for said shield connected to said carriage, said support means supporting said shield in a first shield position for movement with said carriage from the first carriage position to the second carriage position, said shield in said first shield position permitting light to pass from the light source to said copy holder whereby said carriage scans light across an original on said copy holder to reflect light from an original onto said recording member and produce an electrostatic latent image, said support means supporting said shield for movement, by inertia, from the first shield position to a second shield position upon the carriage reaching the second carriage position, said shield in said second shield position being between the light source and the copy holder whereby light is refelected by the light shield onto the recording member, said support means supporting said shield in said second shield position during movement of the carriage from the second carriage position to the first carriage position, said support means supporting said shield for movement, by inertia, from the second shield position to the first shield position upon the carriage reaching the first carriage position.

6. The apparatus of claim 5 wherein the recording member is an annular member.

8. The apparatus of claim 5 wherein the support means comprises a plurality of support rollers journaled to said movable carriage, said shield being supported on said support rollers in the first and second shield positions and during movement therebetween; and first and second stop members, said first stop member stopping movement of the shield on said rollers at the first shield position and said second stop member stopping movement of the shield on said rollers at the second shield position, said shield, by inertia, remaining at rest at the first shield position for movement with the movable carriage during movement of the movable carriage in the first direction, upon the movable carriage stopping travel in said first direction at the second carriage position, said shield, by inertia, moving on said support rollers in said first direction until stopped by said second stop member at the second shield position, said shield, by inertia, remaining at rest at the second shield position for movement with the movable carriage during movement of the movable carriage in the second direction and upon the movable carriage stopping travel in said second direction at the first carriage position, said shield, by inertia, moving on said support rollers in said second direction until stopped by said first stop member at the first shield position.