US3689146A

US3689146A - Electrophotographic copying machine

Info

Publication number: US3689146A
Application number: US33219A
Authority: US
Inventors: Yoshio Ito; Hajime Katayama; Masaru Yamaguchi
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 1969-05-02
Filing date: 1970-04-30
Publication date: 1972-09-05
Anticipated expiration: 1989-09-05
Also published as: FR2047278A5; DE2021427B2; DE2021427A1; NL7006528A; CA953348A; NL169114C; GB1314087A

Abstract

An electrophotographic copier comprises a photosensitive drum including a photoconductive layer and an outer insulative layer. Apparatus for forming and developing an image of an original on the drum surface is selectively supported peripherally thereof as is apparatus for feeding copy material to the drum surface, for transferring developed images to the copy paper and for cleaning the drum surface. The developing, image transfer, fixing, cleaning, and copy separating devices are supported on a single unitary support member which is manually movable into and out of the operative position adjacent to the drum surface. A carrier for supporting the original is arranged for reciprocating movement with respect to the drum. Preferred embodiments of such peripherally supported apparatus are also disclosed.

Description

United States Patent Ito et al.

[ Sept. 5, 1972 [54] ELECTROPHOTOGRAPHIC COPYING MACHINE [72] Inventors: Yoshio Ito, Tokyo; Haiime Katayama, Kawasaki; Masaru Yamaguchi, Tokyo, all of Japan [73] Assignee: Canon Kabushiki Kaisha, Tokyo,

Japan [22] Filed: April 30, 1970 [21] Appl. No.: 33,219

[30] Foreign Application Priority Data May 2, 1969 Japan ..44/34714 Aug. 12, 1969 Japan ..44/63653 [52] US. Cl. ..355/8, 355/3, 355/11 [51] Int. Cl. ..G03g 15/00 [58] Field of Search ..355/3, 8, 13, 14,50, 65, 66

[56] References Cited UNITED STATES PATENTS 3,506,259 4/1970 Caldwell et a1. ..355/3 X 2,959,095 11/1960 Magnusson ..355/11 X 3,399,610 9/1968 Eilhom ..355/14 X 3,418,047 12/1968 Lee et al. ..355/13 X 2,740,895 4/1956 Miller ..355/91 X 3,069,990 12/ 1962 Eisbeing et al ..355/ 103 X 3,309,960 3/1967 Delplanque ..355/3 3,521,950 7/1970 Gardner et a1 ..355/3 Primary Examiner-J0hn M, Horan Assistant Examinew-Kenneth C. Hutchison Attorney-Watson, Leavenworth & Kelton ABSTRACT member which is manually movable into and out of the operative position adjacent to the drum surface. A carrier for supporting the original is arranged for reciprocating movement with respect to the drum. Preferred embodiments of such peripherally supported apparatus are also disclosed.

11 Claims, 18 Drawing Figures PATENTEDSEP 5:912

SHEET 3 [1F 9 PATENIEDSEP 5 m2 sum 5 of 9 PATENTEDsEP Sum 3.689.146

saw 8 0f 9 FIG. l2(2) ELECTROPHOTOGRAPHIC COPYING MACHINE The present invention relates to an improved electrophotographic copying machine and more particularly to an electrophotographic copying machine in which a photosensitive member having a photoconductive layer interposed between a surface insulating layer and a conductive or insulating member is employed so that in image of a sheet-like original or an original having a relatively greater thickness may be automatically,

quickly and economically formed upon an image recording medium such as ordinary paper.

Electrophotographic copying machines for reproducing copies of a sheet-like original as well as an original having a relatively greater thickness are divided into two types, one type employing photosensitive papers and the other type employing no photosensitive paper, that is, the so-called Xerographic type. In the former type photosensitive papers are used so that cost is considerably more than with ordinary paper. In the latter type, inexpensive ordinary paper is used as an image recording medium, but since a photosensitive drum having a photosensitive layer formed by vacuum deposition of selenium is used, the surface of the photosensitive layer tends to be directly mechanically damaged in repetitive use of the drum. Thus, there is a problem regarding durability of the drum with resultant increased cost. Mechanically, the original is held in stationary position while the optical system as well as the photosensitive drum inside the machine are driven in synchronism with each other so that the copying machine must have a highly precise mechanism which is inevitably large in size.

Therefore, one of the objects of the present invention is to provide an improved electrophotographic copying machine compact in size, capable of high speed copying operation, especially capable of reducing the copying or reproduction time required for reproducing a single copy, simple in operation, and inexpensive to manufacture. This object may be attained by employing the above described photosensitive body coated with an insulating layer of a polyester resin having considerable mechanical durability, for example Mylar (Trade Name) and by using as an image recording medium an ordinary paper or the like, so as to reproduce copies from a sheet-like original or an original having a relatively greater thickness which is moved during exposure.

Another object of the present invention is to provide an improved electrophotographic copying machine having a mechanism for separating, from a photosensitive drum, copy paper which is electrostatically attracted thereto.

A feature of the present invention is to provide an improved electrophotographic copying machine having fixing means for fusing and fixing to a copy paper a powder image consisting of thermoplastic resinous toner, said fixing means having a conveyor belt for electrostatically attracting the copy paper thereto and preheating the conveyor belt by air heated by heating elements, which directly heat the conveyor belt, at a position at which the copy paper is loaded upon the conveyor belt, thereby preventing the copy paper from being curled.

According to one aspect of the present invention, an original carrier is disposed at the top of the housing of the electrophotographic copying machine. The original carrier is provided with a pressure plate for holding in stationary position a sheet-like original or an original having a relatively greater thickness. A photosensitive body has a photoconductive layer interposed between a surface insulating layer and a conductive or insulating member. The photosensitive body is disposed around the peripheral surface of a rotary drum, thereby providing a photosensitive drum. The drum is rotated in one direction and first charging means, contemporaneous exposure-corona-discharge means, whole-surface-illuminating means, developing means, third charging means, image transfer means, and cleaning means are disposed, in the order named, peripherally of the photosensitive drum. (These means will be referred to as peripheral means as a whole hereinafter.) The drum is uniformly charged with positive or negative charge by the first charging means, exposed to the light image of an original to be reproduced contemporaneously with application to the drum of a DC charge of polarity opposite to that of the first charging or with AC charge (to be referred to as second charging), and uniformly illuminated by the whole-surface illuminating means. An electrostatic latent image so formed is developed into a positive or negative image with toner. If required, a third charging is made before the image is transferred to a copy paper. In this case, the copy paper is electrostatically attracted by the photosensitive drum so that it is separated by a novel anduseful separating means in accordance with the present invention. The image transferred to the copy paper is fixed to the copy paper.

The present invention will become more apparent from the following description of the preferred embodiment thereof taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of one preferred embodiment of the present invention;

FIG. 2 is a longitudinal sectional view thereof;

FIG. 3 is a sectional view, on enlarged scale, of a photosensitive drum and an original carrier therefor,

FIG. 4 is a longitudinal sectional view 'of the original carrier;

FIG. 5 is a front view illustrating the gear train for driving the photosensitive drum;

FIG. 6 is a perspective view of the original carrier and its reciprocating drive mechanism;

FIG. 7 is a detailed view of an exposure means;

FIG. 8 is a transverse sectional view of developing means;

FIGS. 9(1) and 9(2) and FIG. 10 are detailed views of a developing agent supply-device;

FIGS. 11(1) and 11(2) are detailed views of copy paper feeding means;

FIGS. 12(1) and 12(2) are perspective views illustrating image transfer means and copy paper separating means;

FIG. 13 is a longitudinal sectional view including an illustration of fixing means in accordance with the present invention;

FIG. 14 is a side view of a mechanism for moving toward and away from the photosensitive drum, an image transfer roller, the cleaning means, the developing means and other means in unison with each other; and

FIG. 15 is a perspective view thereof.

FIG. 1 is a perspective view of an electrophotographic apparatus in accordance with the present invention. An original carrier 11 is mounted upon the top of the housing and an original is placed upon the original carrier 11 with its pattern to be reproduced facing downwardly. The original carrier 11 is reciprocated. The copies reproduced are discharged from an outlet to a tray 12. Copy paper sheets P are fed one by one from a feeding station 55.

FIG. 2 is a longitudinal sectional view of the apparatus. A rotary drum 2 has a photosensitive member 3 comprising a photoconductive layer interposed between an outermost insulating (insulative) layer and a conductive or insulating layer whereby a photosensitive drum 1 is constructed. The photosensitive drum 1 rotates in the direction indicated by the arrow and a first charging means 4, contemporaneous exposurecorona-discharge means 5, means 6 for exposing the whole surface of the photosensitive drum 1,developing means 7, third charging means 8, means 9 for transferring an image from-the photosensitive drum to a copy paper and cleaning means 10 are disposed around the periphery of the photosensitive drum 1 in the order named.

The photosensitive member 3 upon the drum 1 is charged with positive or negative charge by DC corona discharge by the first charging means 4. By the contemporaneous exposure-corona-discharge means 5, the photosensitive member 3 receives DC corona discharge of polarity opposite to that of the first charge or AC corona discharge (which will be referred to as second charging contemporaneously with projection of a light or radiation image of the pattern of an original to be reproduced upon the photosensitive drum 1, thereby forming an electrostatic latent image.

Next, the electrostatic latent image thus formed upon the photosensitive member 3 is' uniformly irradiated by the whole-surface illumination means 6, such as a fluorescent lamp, so that the field of the electrostatic latent image external to the drum is intensified, thereby forming upon the surface of the photosensitive drum 1 an electrostatic latent image having high contrast. The latent image thus obtained is developed into a visible image by developing means 7 with toner charged oppositely to the polarity of the electrostatic latent image or with the toner having the same polarity as that of the latent image. Preferably, the magnetic brush method or the fur brush method is used. The third charging means 8 is not necessarily required, but it may be advantageously used with a suitable polarity in order to improve efficiency in transferring the powder image upon the photosensitive member 3 to an image recording medium (which is generally a paper sheet and will be referred to as copy paper hereinafter). The powder image is transferred electrostatically to the copy paper P by the image transfer means 9. The toner still remaining upon'the photosensitive drum 1 is removed by the cleaning means 10, such as a roller.

The copy paper P bearing thereupon the powder image transferred from the photosensitive drum is separated from the drum 1 and the transferred image is fixed by the fixing means. The copy paper bearing the fixed image is discharged through an outlet.

The apparatus in accordance with the present invention includes the above described electrophotographic processing station, the original carrier, drive means for driving the original carrier, exposure means, copy paper feeding means, image transfer and copy paper separation means, fixing means, an operational control system, etc. the arrangement of which characterizes the present invention. The above described means and system will be described in more detail hereinafter.

ORIGINAL CARRIER AND DRIVE MECHANISM As shown in FIG. 3, the original carrier 11 runs horizontally upon an angle rail 13 and a round rail 14 laid between the frames of the main body through a roller 17 and a hand-drum-shaped roller 18 which are rotatably fixed to the channels 16 and 16 (See FIG. 6)

which in turn are securely fixed to the side edges of the under-surface of the inner frame 15 of the original carrier 3. The lateral vibrations of the original carrier 3 are received by the roller 18 and the rail 14 while the vertical vibrations are damped or absorbed by springs 20 through the roller 19 which is vertically movably supported in the channel 16 and is placed in contact with the lower side of the rail 14.

As shown in FIG. 4, a transparent original supporting glass 21 is placed upon the inner frame 15 of the original carrier 3 and an original holder 22 is provided for closely pressing the original M against the original supporting glass 21. The original holder 22 comprises an arm 51 pivotably fixed at 50 to the inner frame 15 for rotation in a plane perpendicular to the original carrier, a retaining member 54 U-shaped in cross section and pivotably fixed by a pin 52 to the arm 51 and a rubber sheet 53 fixedly retained by the retaining member 54. The original holder 22 may be raised depending upon the thickness of the original M as shown by broken lines in FIG. 4 so that even a thick original M may be pressed against the glass 21 in a satisfactory manner without necessity to substantially increase the length of the rubber sheet 52.

A rotary shaft 26 of the photosensitive drum 1 is joumaled by bearings 23 which are securely fixed to the

side plates

1 and 1 of the drum 1 and by a drum supporting member 25 which in turn is securely fixed to the bottom plate 24 of the housing. A drum drive gear G4 is carried by the drum shaft 26 through the bearing 23. The drum side plate 1 is provided with an outwardly extending projection 27 which is fitted into a recess 28 formed in the boss of the gear G4, so that the drum 1 may be mounted upon and detached from the shaft 26 by sliding the former relative to the latter. The drive gear G4 has a control cam 33 (see FIG. 5) formed integrally therewith so as to control switches MS-4 to MS-8, which constitute a control unit. The end remote from the drive gear G4 of the drum shaft 26 is journaled in an auxiliary side plate 29 which is detachably fixed to the bottom plate 24 so that the drum 1 may be readily mounted and detached.

The drum 1 is rotated in one direction by a main motor MT fixed to the drum supporting member 25, through a gear G1, idlers G2 and G3 and the drive gear G4 carried by the drum shaft 26. In exposure, the original carrier 11 is displaced in the direction indicated by the arrow a in FIG. 2 and upon completion of the exposure, the carrier 11 is reversed in the direction indicated by the arrow b and returned to its initial or normal position. As shown in FIG. 6, two belts or wires and 31, each having an end secured to the channel 16 fixed to the undersurface of the original carrier 11, are wrapped in opposite directions around the guide pulleys 30 and 31 and around an original carrier drive pulley 30p carried by the drum shaft 26, and then the other ends of the belts or

wires

30 and 31 are securely fixed to the pulley 30p. The drive pulley 30p is rotated in forward and reverse directions in one cycle of the copying operation, through two clutches C- 1 and C-2 as shown in FIG. 5. In one undirectional or forward stroke of the original carrier 11, the clutch C-2 is actuated so that the driving force from the motor MT is transmitted to the drive pulley 30p integral with the gear G7 through the gears G1, G2, G3, G4 and G5, the clutch C-1 and the gears G6 and G7, so that the drive pulley 30p is rotated in the direction indicated by the arrow in FIG. 6. Therefore, the wire 30 is wound around the drive pulley 30p so that the original carrier 11 is driven in the direction indicated by the arrow a at a predetermined velocity, whereby the original M (See FIG. 4) is exposed through a slit. That is, the light image ofthe original is projected upon the drum 1 through 'the contemporaneous exposure-corona discharge means 5 sothat an electrostatic latent image is formed upon the photosensitive drum 1 which is previously charged by the first charging means 4.

It is to be noted that in the case of the reproduction of copy at a magnification of unity, the peripheral velocity of the drum 1 is equal to the velocity of the original carrier 11 in the forward stroke. When the original carrier 11 reaches the end of the forward stroke, a stroke cam 32 (See FIGS. 3 and 6) fixed to the channel 16, of the original carrier 11 actuates a microswitch MS-l which is securely-fixed to the left end of the frame of the main body so that the clutch O2 is activated while the clutch G1 is deactivated. Thus, the drum 1 continues to rotate in the same direction while the drive pulley 30p is reversed in rotation so that the original carrier 11 is returned to the initial position in the direction b. It is seen that the original carrier 11 may be quickly returned to the initial position by suitably determining the ratio of the number of teeth of the gear G6 for the forward stroke to that of the gear G8 for the return stroke, both of which gears are selectively engaged with the gear G7. Thus, the copying operation can be made at a high speed.

Upon returning of the original carrier 11 to the initial position (at the right end), the stroke cam 32 actuates a rnicroswitch MS-2 (See FIG. 6) fixed to the right end position of the main body so that the main motor MT is temporarily retarded whereby the original carrier is braked. After a suitable time delay, the rnicroswitch MS-3 is deactivated, so that the clutch C-2 for the return stroke is de-energized, thereby precisely retuming the original carrier 11 to the initial position and disconnecting the carrier from its drive mechanism.

On the other hand, the drum 1 is temporarily braked and stopped but the brake is released after a very short time (a few to tens of microseconds), so that even when the original carrier 11 is stopped, the drum 1 continues its rotation and is finally stopped when the home position cam 33 carried by the drum drive gear G4 deactivates the rnicroswitch MS-4. The above two-step operation is for absorbing the inertia of the original carrier in the retum stroke. For this purpose, the stroke of the original carrier 11 is made relatively shorter than the whole stroke of the drum.

EXPOSURE MEANS The illumination system 34 includes a light source for illuminating the original such as a fluorescent lamp 35 with a reflector, a light shielding plate 36 and a cooling fan (not shown) for cooling the lamp 35 so as to prevent reduction in the intensity of light emanating therefrom.

. The cooling air is directed in the longitudinal direction of a chamber defined by the shielding plate 36, the original carrier 11 and an optical unit (black box) 37 so thatthe lamps 35 are effectively cooled over the whole length thereof. .The current in excess of a rated current is maintained in lamp 35 during exposure, thereby increasing the intensity of illuminating light, but during non exposure rated current flows through the lamp so that it is always illuminated. Thus, there is no waiting time in printing operations and the service life of the lamp 35 may be increased.

The light from the lamps 35 illuminates the original supported upon the original carrier 11 and light reflected from the original is transmitted through a transparent, dust proof glass 39 which is held in posi tion upon the black box 37 by retaining members 38. The reflected light is directed away from the drum as shown by a'first mirror 40 which is inclined at about 45 relative to the horizontal, to an in-mirror type lens 41. The in-mirror type lens 41 is a conventional lens divided into two sections along the axis of symmetry and a mirror is positioned at the center. The light reflected by a second mirror 41, passes through the lens 41 again and is projected upon the drum 1 through the contemporaneous exposure-corona discharge means 5 which is fixed to the black box 37 in opposed relation with the drum 1 and has an exposure slit in the longitudinal direction.

The first reflecting mirror 40 is supported upon three embossed projections of a mirror stand 44 and maintained in position by a mirror pressure spring 43 which in turn is securely fixed to the mirror stand 44. The mirror stand 44 is fixed to a stand (not shown) which is only movable in the horizontal direction. A pin 45 is fixed to the mirror stand 44 at the extension of the optical axis so that the mirror stand 44 may rotate about the pin 45. A stopper pin 46 is extended from the center of a stand which in turn is fixed to the carrier (not shown). This pin 46 is externally threaded at 48 so that the pin 46 may be movable. The mirror stand 44 is so biased by a spring 47 that the mirror stand 44 is normally in contact with the pin 46 so that the angle of the mirror relative to the horizontal axis may be adjusted by moving the pin 46. The adjustment of the parallelism relative to the drum 1 and the optical length is made by displacing the carrier in the horizontal direction. A transparent dust proof member 49 is fixed to the optical unit (black box) 37 so as to completely seal the optical unit 37. When a conductive member such as NESA glass is used as the dust proof member, the charging efficiency of the contemporaneous exposure-corona-discharge means 5 may be improved.

ELECTROPHOTOGRAPHIC PROCESSING STATION 'Ihe photosensitive drum 1 is started in response to the depression of a start switch. As described hereinabove, the light image of the original is projected upon the drum 1 simultaneously with charging of the drum 1 by the contemporaneous exposure-corona discharge means 5. Next the drum 1 is uniformly illuminated by light emanating from the lamp 6, whereby an electrostatic latent image having a high contrast may be formed upon the drum 1.

The developing means is of a box-shaped construction as shown in FIG. 8 having side walls 101 and a bottom plate 100, and includes two magnetic brushes 102 and 103 rotatably journaled between the opposing side walls 101, two blades 104 and 105, and

guide rails

108 and 109 upon which rests a hopper 111. Each of the magnetic brushes 102 and 103 is a magnetic roller having a plurality of alternately arranged different poles carried by a non-magnetic shaft. It is to be noted that different poles of the magnetic brushes 102 and 103 are opposed to each other.

A developing agent 1 consists of colored, finely divided powder (toner) and finely divided iron powder (carrier). The toner and the carrier are mixed uniformly by a pair of mixing

rollers

106 and 107 and then moved toward the first magnetic roller 102 to raising the mixture by the blades. Then the developing agent is attracted by the first roll 102 and is transferred to the second roller 103 so that the so-called magnetic brush uniform attraction of developing agent occurs. When the leading portion of the magnetic brush having less magnetic flux contacts the surface of the drum 1 bearing an electrostatic latent image, the leading portion of the magnetic brush is attracted electrostatically by the drum 1 and is finally cut off, so that fog and other undesired stains are formed upon the image. Therefore, in order to eliminate this defect, the blades 104 and 105 are provided for the magnetic brushes so that the brush in excess of a predetermined height may be cut off. The magnetic brushes are rotated in the directions shown in FIG. 8 and the hard or bristle magnetic brush in the space defined intermediate the brushes and the drum 1 is placed in sliding contact with the surface of the drum 1, thereby developing the latent image into a visible image.

The mixing roll 107 serves to uniformly mix the condensed developing agent 112 dropped from the hopper 111 immediately above the mixing roll 107, with the developing agent in the developing means and to supply the developing agent toward the mixing roll 106. The hopper 111 is moved into and away from the developing means along the rails and

guide rails

108, 109 and 120 disposed between the side walls 101 of the developing means. The hopper 111 has a U-shaped main body 113 and guide blocks 114 (See FIG. 10) at both ends of the main body 113. The bottom 116 has a plurality of openings 115 extending laterally and spaced apart from each other in the longitudinal direction by a suitable distance. A moving plate 117 having a plurality of openings 118 having the same dimensions and pitch as those of the openings 115 is interposed between the guide blocks upon the bottom 116 for slidable movement in the longitudinal direction. (See FIG. 10). Normally the moving plate 117 is so biased by a spring that the openings 118 of the moving plate 117 will not register with the openings of the bottom 116. Therefore, only when the developing agent feed button 119 is depressed do the openings 115 register with the openings 1 18 so that the developing agent 112 is dropped into the developing means. Hopper guide rails 120 are fixed to the lower side walls of the main body 113 in such a manner that each lower free end 121 of the guide rail 120 is bent inwardly (See FIG. 8). A control plate 122 for controlling the quantity of developing agent to be dropped has openings or slits having the same dimensions and pitch as those of the

openings

116 and 118 and is interposed between the guide plates 120 and the bottom 1 16 for slidable movement in the longitudinal direction in order to control the quantity of the developing agent to be dropped through the openings 1 15 of the bottom 116. That is, the maximum quantity of developing agent is dropped when the openings of the bottom 116, the moving plate 117 and the control plate 122 coincide with each other. The quantity of the developing agent to be dropped is controlled by the control plate 122.

FIGS. 9(1) and 9(2) illustrate a mechanism for automatically depressing the hopper button 119 of the condensed developing agent feeding hopper. A cam gear G22 is driven by a gear G20 carried by a shaft 123 of the second roller 107 through a clutch gear G21. The cam gear G22 makes one rotation in response to each feeding of a copy paper. The projection 125 of a cam 124 made integral with the gear G22 engages a counter lever 126 so that a counter ratchet wheel 127 rotated by one tooth. That is, the counter ratchet wheel 127 advances by one tooth when each copy paper is fed. A projection 128 extends from one side face of the counter ratchet wheel 127 and engages the clutch releasing lever 129 to push the clutch releasing lever 129 and disengage the lever from a stepped portion 132 of a clutch sleeve 130. Therefore, a spring 130 loaded in the sleeve 130 winds itself around the bosses of the clutch gear G21 and that of the hopper cam 130 so that the gear G21 drives the cam 130 whereby the hopper button 119 is depressed by the cam surface 130 Thus, the openings 118 of the moving plate 117 coincide with those of the bottom 116 thereby supplying the developing agent. The clutch releasing lever 129 actuated by the counter ratchet wheel 127 may be immediately returned to its initial position so that when the clutch sleeve 130 makes one rotation, the leading end 131 of the clutch releasing lever 129 engages with the stepped portion 132 of the sleeve 130, thereby stopping the sleeve 130. Then, the spring clutch is released and the hopper cam is stopped. Unless the counter ratchet wheel 127 is advanced by one tooth as one copy paper is fed so that the projection or pin 128 actuates the clutch releasing lever 129, no developing agent is supplied. The developing means 7 is activated by a signal generated when the copy paper P passes over the microswitch MS-9 between the feed rollers 58 and 59 (See FIG. 2) as will be described in more detail hereinafter so that unless copy paper is feed, reproduction is not commenced even when the machine is driven, and no excessive developing agent 112 is supplied.

COPY PAPER FEEDING STATION As shown in FIG. 2, the feeding station comprises copy paper feeding means 55 and copy paper transporting means 56. The copy papers in the feeding means 55 are fed toward the transporting means 56 one by one by a feed roller 57 which rotates in response to a signal from the control means 33 (See FIG. The transporting means comprises a first, second and third pairs of

rollers

58, 69 and 60. The first roller 58 is intermittently driven in response to the signal from the control means 33 in order to adjust the time when the image upon the drum 1 is transferred to the copy paper P in the transfer means 9 and to ensure the registration of the leading edge of the copy paper P with that of the original M. The second and third feed rollers 59 and 60 are normally driven so as to transport the copy paper P to the transfer means 9. Since the first roller 58 is not driven when a copy paper P is fed from the feeding means 55 by the feed roller 57, the copy paper P is bowed as indicated by the broken line so that the leading edge of the copy paper P is disposed parallel to the axis of the first roller 58. In response to the signal from the control means 33, the first roller 58 is driven so that the copy paper P is transported by the second and third rollers 59 and 60 into the image transfer means 9 in such a manner that the leading edge of the copy paper P is registered with that of the powder image upon the photosensitive drum 1. Thereafter, the powder image upon the drum 1 is transferred to the copy paper P when the latter is pressed against the drum 1 by a pressure or transfer roller 9.

The switch MS-9 is interposed between the first and second rollers 58 and 59 in the path of the copy paper so as to detect the passage thereof, thereby controlling the developing means 7. When no copy paper is transported so that the switch MS-9 is not actuated, the developing means 7 is not activated. Therefore, the electrostatic latent image formed upon the drum 1 will not be developed so that the transfer roller 9 which is normally made in rolling contact with the drum 1 is not stained. No load is applied to the cleaning roller 61 in the cleaning means 10. The copy paper feeding means 55 will be described in more detail with reference to FIGS. 11(1) and 11(2). A copy paper stand 199 is detachably mounted through guide rails or the like upon the main body of the photocopying machine. A pair of L-shaped

guides

200 and 201 are placed upon the stand 199. The right guide 200 is securely fixed to the stand 199 while the left guide 201 may be displaced on a slide pin 202 extending from the undersurface of the left guide 201 and being movable in a guide slot 203 formed in the stand 199 depending upon the sizes of the copy papers. The rear portions of both of the

guide plates

200 and 201 are cut away so as to form notches into which are fitted copy paper pressure members 205 biased inwardly by springs 204. Thus, the copy papers P are held in position with their side edges being held by the pair of right and left

guides

200 and 201 to eliminate undesired resistance, and the separation of the copy papers P is much facilitated.

Separating

levers

207 and 208 are vertically pivotably fixed to the outer side edges of the

guides

200 and 201 by pins 206. At the leading or free end of each of the separating

levers

207 and 208 is formed a separating pawl consisting of a vertically downwardly bent portion 209 for preventing the displacement of the copy papers P and a horizontal portion 210 for holding the comer of the paper from above. The copy paper P advanced by the feed roller 57 is stopped by the vertical portion 209 of the separating pawl, but the center portion of the copy paper P is still advanced so that the leading edge stopped by the separating pawl is buckled, whereby only the uppermost copy paper is disengaged from the pawl and advanced.

A stopper 240 is fixed to the leading end of the stand 199 by a pin 241 in such a manner that the stopper 240 may be normally held in raised position by a spring (not shown). Thus, the stopper 240 may be used as a reference in placing the copy papers upon the stand 199 because the pawls are not used since the separating

levers

207 and 208 then lifted. A pawl releasing lever 213 for raising the separating lever 208 is fixed to the stand 199 outwardly of the movable guide 201 in such a manner that the lower end is extended through the opening formed through the stand 199 and pivotably fixed to the stand 199 by a pin 211. A cam 215 is also carried by the pin 211 in such a manner that when the lever 213 is raised as shown in FIG. 11(1) the cam 215 pushes the rear lower surface of the lever 208 so as to raise-it, thereby permitting the placing of copy papers upon the stand 199.

Another cam 216 is also carried by the pin 211 so that when the lever 213 is raised, pressure acts upon the plate spring 212 bridging the movable guide pins 202. That is, the pressure placed upon the stand 199 from the movable guide 201 is released so that the latter may be displaced. A shaft 222 extends over the stand 199 between bearing

plates

223 and 224 securely fixed to the main body of the photocopying machine outwardly of the stand 199. A tubular shaft 225 is fitted over one half (the lower half in FIG. 11(2)) of the shaft 222 and

bearings

226 and 226 are interposed between the shaft 222 and the tubular shaft 225. A shaft 244 is joumaled in the leading ends of an arm 242 loosely fixed to the shaft 222 and another arm 243 securely fixed to the tubular shaft 225. The copy paper feed rollers 57 are carried by this shaft 222. The

shafts

222 and 244 are drivingly coupled to each other by a chain 245.

A drive clutch gear G31 carried at one end of the shaft 222 is meshed with a normally rotating gear G30 through a clutch C-5 in response to a copy paper feed signal so that the rollers 57 are rotated through the shaft 222, the

sprocket wheels

246 and 247, the chain 245 and the shaft 244. The gear G31 is driven by the chain 220 wrapped around a sprocket wheel 221.

As shown in FIG. 11(2), a boss 227 is securely fixed to the bearing plate 224 coaxially with the shaft 225. A knob 299 is fitted into the boss 227 and a spring 230 is loaded between the knob 229 and the tubular shaft 225. The knob 229 is pulled out of the boss 227 against the spring 230 and rotated through an angle and held in position by the engagement of a suitable projection and recess, thereby pressing the feed rollers 57 against the copy papers through the tubular shaft 225, the arm 243 and the shaft 244 by the spring 230. The pressure acting upon the copy papers may be adjusted by the knob 229, thereby ensuring the smooth feeding of copy papers irrespective of the difference in quality.

As the copy papers upon the stand 199 are used, the positions of the feed rollers 57 are gradually lowered so that the tubular shaft 225 is caused to rotate in the counterclockwise direction. This rotation is detected by a cam 248 carried by the tubular shaft 225 and a microswitch MS-30 securely fixed to the bearing plate 224. That is, the number of copy papers upon the stand 199 may be detected so that when the number of copy papers becomes less than a predetermined number, an alarm device such as a lamp in the control panel is turned on.

IMAGE TRANSFER AND PAPER SEPARATING MEANS The copy paper fed from the feeding means 55 and transported toward the image transfer means by the

rollers

58, 59 and 60 is pressed against the powder image upon the drum 1 by the transfer roller 9. Preferably the transfer roller 9 is made of an electrically conductive material. Separating means generally designated by 300 is disposed in the image transfer means so that the copy paper may be separated from the drum 1 after the powder image has been transferred. That is, as shown in FIGS. 2 and 12, a copy paper separating band 301 is extended forwardly and rearwardly of the powder image transfer position, that is, the line of contact between the transfer roller 9 and the drum 1, around the transfer roller 9. For example, the separating band 301 is a polyester resin film 50 p. in thickness and contacts one side or marginal edge of the copy paper P over at least 10 mm.

The copy paper P is admitted into the nip between the drum 1 and the transfer roller 9 from a guide 250 and one side edge of the copy paper is disposed between the transfer roller 9 and the separating band 301. After passing through the transfer position, the copy paper is guided by the undersurface of the separating band 301 along the transfer roller 9 so that the copy paper may be readily separated from the drum 1 and then fed into the fixing means. The peripheral portion 9, of the transfer roller 9, around which is wrapped the separating band 301 (See FIG. 12(1)) is made of a metal having a smooth surface and has a diameter slightly smaller than that of the transfer roller 9, which is made of an elastic material such as conductive rubber, so that the separating band 301 is not placed in contact with the drum 1, thereby preventing wear of the band 301. When the transfer roller 9 has a stepped metallic roller member 9,, the application of a potential to a conductive transfer roller or grounding thereof may be facilitated. The separating band 301 has its both ends securely fixed by

retainers

303 and 304, but when the separating belt 301 is so positioned around the transfer roller 9 that the belt 301 is not made in contact with the photosensitive drum 1 as described hereinabove, an endless belt may be used. The band 301 is given a suitable tension by a tension pin 306 having a spring 307.

FIXING MEANS The fixing means (FIGS. 2 and 13) comprises infrared lamps or heaters 400, a blower 401 and a conveyor belt 402 which is advanced in the direction indicated by the arrows. The blower 401 blows heated air upon the copy paper P to which is transferred the powder image from the drum 1 so that the powder image is fixed to the copy paper P. The heated air from the blower 401 also ensures positive holding of the copy paper upon the conveyor belt 402 spaced from the heaters 400. The copy paper bearing the fixed image is discharged out of the fixing means outlet 16 through a pair of discharge rollers 403 and 404.

Now referring more particularly to FIG. 13 which illustrates one embodiment of the fixing means in accordancewith the present invention, the conveyor belt 402 is wrapped around the drive roller 482 and a guide roller 483 between the transfer roller 9 and the pair of discharge rollers 403 and 404 and the radiation heating means 471 is disposed above the conveyor belt 402.

Preferably, the conveyor belt unit may be detachably mounted upon the photocopying machine so that the inspection, repairs, etc. may be facilitated. For this purpose, an opening 473, into which may be fitted a side wall 472, is formed through the side wall 600 of the main body of the machine. The conveyor belt unit may be guided by guide rails 474. The conveyor belt 402 may be made of an electrically insulating material having a resistance to heat, such as tetrafluoroethylene containing glass fibers. A charging electrode 475 and a grounding electrode 476 are disposed in the path of the conveyor belt 402 so that charge may be imparted thereto. The charge imparted to the conveyor belt 402 is the same polarity as that of the charge imparted from the third charging means 8. An insulating block 477 for enclosing therein the electrode 475 is so disposed as to move in and out by a guide '477 the bottom plate between the side walls 472 having heat resisting materia] coated or lined upon the inner surface thereof.

The radiation heater means 471 is supported between the side walls 600 by insulating material. In the instant embodiment, a pair of reflectors 478 have mirror surfaces directed toward the conveyor belt 402 and the heating elements 400 are disposed in the reflectors 478 respectively. A duct 479 is formed behind the reflectors 478 and incorporates therein the blower 401 so that the air in a space defined between the reflectors 478 is sucked through an opening 480 and blown against the copy paper P through an opening 481 at the position where thevcopy paper P is loaded upon the conveyor belt 402. A heat insulating chamber 484 is provided in order to prevent the transmission of heat from the heating means 471 to the main body of the photocopying machine.

Since the conveyor belt 402 is imparted with the charge of the polarity opposite to that given by the third charging means 8, by the electrodes 475 and 476, the copy paper P loaded upon the conveyor belt 402 is electrostatically attracted thereby during the transportation. That is, when the polarity of the charge of the powder image is negative while the polarity of the charge imparted from the third charging means 8 is also negative, positive charge is imparted to the copy paper P from the conductive transfer roller 9 which is grounded. Thus, the negative or positive charge, for example, from 3 to 6 KV is imparted to the conveyor belt 402 by the electrodes 47 5 and 476, thereby attracting the copy paper to the belt 402. Since the heat insulating belt 402 is elevated to a temperature of about 200C because it is always heated by the heating means 471, the toner is fused and fixed upon the copy paper P.

The copy paper P upon the conveyor belt 402 is heated not only by the heaters in the reflectors in the radiation heating means 471, but also by the heated air about 150 to 200C from the blower 401. As described hereinabove, the heated air around the heaters is sucked by the blower 401 through the opening 480. That is, the heated air flows upon the copy paper upon the belt 402 and heats the copy paper. Thereafter, the heated air passes through the duct 479 and is then blown through the opening 481 upon the copy paper upon the belt 402. Therefore, the copy paper as well as the powder image thereupon are preheated, thereby preventing curling of the copy paper due to the sudden heating. The heated air from the blower 401 serves to hold the copy paper upon the conveyor belt 402 which is also attracted electrostatically thereby. Since the heated air is circulated, temperature variation may be prevented so that the belt 402, heating means 471 and other parts may be maintained at a uniform temperature and the thermal efficiency may be improved. According to the present invention, the toner may be fixed to the copy paper in a very effective manner by the direct heating of the copy paper as described hereinabove. The toner is prevented from directly contact the heating elements so that complex means for preventing the offset described above is not required. Furthermore, even though the copy paper is transported upon the belt, no curling is produced, whereby jamming of copy paper may be prevented.

CLEANING MEANS The toner remaining upon the drum 1 even after the powder image is transferred to the copy paper may be removed by the cleaning means comprising a cleaning roller 61. The cleaning roller 61 comprises a rotary shaft 500, a roller 501 made of an elastic material and a cloth 502 wrapped around the roller 501. The cleaning roller 61 is rotated in contact with the drum 1 in a direction of rotation opposite to that of the drum 1. The toner attached to the cleaning roller 61 is removed by a brush roller 505 having hard brushes 503 extending from a rotary shaft 504. The removed tonner is dropped into a toner receiving box 506. A partition wall 507 in the box 506 is for preventing the dispersion of the toner from the box 506 to the drum 1. Because of the auxiliary cleaner 508 (See FIG. 2) comprising an elastic body covered with a cloth, even a very small quantity of the toner still remaining upon the drum 1 after it is cleaned by the cleaning roller 61 may be completely removed from the drum. The auxiliary cleaning means 508 is detachably mounted so as to be replaced at a suitable time interval.

OTHER MEANS AND MECHANISMS Since the drum 1 is cleaned by the cleaning means each time one copy is reproduced in the manner described hereinabove, it is necessary to prevent relative deviation and separation of the photosensitive member 3 from the supporting drum 2 due to the pressure applied to the drum 1 by the cleaning roller 61. That is, the photosensitive member 3 must be securely held upon the supporting drum 2. In order to clean all over the peripheral surface of the photosensitive drum 1, the width of the cleaning roller 61 (in the axial direction) must be longer than that of the drum 1, so

that the stronger pressure tends to act upon the side edges of the drum, thereby causing the damage thereto. In order to prevent this, photosensitive member retaining elements 13 (see FIG. 3) having an outer diameter equal to that of the drum 1 are attached to the latter so as to protect the photosensitive member 3, to improve the durability of the drum 1 and to reduce the cost. To remove or detach the drum 1, the auxiliary bearing plate 29 is detached from the bottom plate 24 and then the drum 1 is displaced toward the left in FIG. 3, thereby pulling it out of the shaft 26.

This is necessary for inspection and repair of the various means disposed around the periphery of the drum 1 and for replacement thereof. Thus, it is required that the transfer roller 9, the cleaning roller 502, the developing means 7 and so on must be moved away from the drum 1. Extensive time is required to separately move away from the drum 1 each of the above means and the relative positions of these means will be deviated when they are returned to their normal operative positions. Thus, overall adjustment of the photocopying machine would then be required with resultant time loss, and a complex, tedious operation.

In order to eliminate this, the present invention contemplates arranging these means around the periphery of the drum so as to be moved toward and away from the drum 1 in unison by a link mechanism. As shown in FIGS. 14 and 15, the transfer means 9, the fixing means and the cleaning means are all carried by a common supporting frame 600 while the developing means is carried by a supporting member 602.

In order to move toward and away from the drum 1 these peripheral means, a lever handle 603 is provided. When the lever handle 603 is moved toward the position indicated by the broken lines in FIGS. 14 and 15, a shaft 604 and a guide plate 611 are rotated in the counterclockwise direction. In the guide plate 611 is formed a guide slot 612 in such a manner that the guide slot 612 may approach the shaft 604 as the guide plate 611 is rotated, in the clockwise direction. A pin 614 of an L-shaped lever 613 is fitted into the slot 612 so that the lever 613 rotates about its pin 616 as the guide plate 611 is rotated. A pin 618 of a link 617 is fitted into an elongated slot formed in the forward portion of the lever 613 so that the link 617 lifts a lateral shaft 624 thereby rotating levers 622 about a shaft 621 in the counterclockwise direction. Therefore, a lateral bar 627 and the supporting frames 600 securely fixed thereto at both ends thereof are moved in the direction indicated by the arrow d in FIGS. 14 and 15 since the shaft 625 is connected to the lateral rod 627 through a ring 623, a link 626 and a ring 601. Thus, the transfer roller 9, the fixing means and the cleaning means carried by the supporting plates 600 are moved away in unison from the drum 1.

When the lever 622 and the lateral rod 625 are rotated in the counterclockwise direction, the links 605 connected to the lateral rod 625 are rotated about the shaft 604 in the counterclockwise direction while being guided along the elongated slots 607 so that the lever 629 carried by the shaft 628 is rotated in the clockwise direction through the lateral rod 603, thereby moving the developing means supporting member 602 in the direction indicated by the arrow 0.

It is therefore seen that all of the peripheral means around the drum 1 are moved away therefrom, whereby the drum 1 may be readily detached. Upon returning to the initial position of the lever handle 603, the above described operations are reversed so that all of the peripheral means may be precisely returned to their normal positions relative to the drum 1.

From the foregoing, it is seen that the electrophotographic copying machine in accordance with the present invention is compact in size because the first charging means, the contemporaneous exposuresecond charging means, the whole surface illumination means, the developing means, the third charging means if required, the image transfer means and the cleaning means, all of which are required for electrophotographic processing, are disposed around the drum; the original carrier is disposed above the drum for reciprocal movement; the optical exposure means and the cleaning means are disposed laterally of the original carrier; and the copy paper feeding means, the transfer means and the fixing means are disposed downwardly of the drum.

The optical system is disposed upwardly of the developing means but laterally of the drum and is sealed by an optical unit so that the lens, mirrors, etc. of the optical system may be completely prevented from being contaminated or stained by the toner, dust and so on. The copy paper separating band is interposed between the transfer roller and the drum so as to guide the copy paper awaY from the drum along the separating band, thereby smoothly and positively separating the copy paper from the drum.

The drum is rotatably carried by the main shaft and is drivingly coupled to the drive means through the coupling means disposed at one end of the drum. The cleaning means and the transfer means are supported by the common supporting members so that these means may be moved toward and away from the drum by operating the lever handle, whereby the mounting and detachment of the drum is much facilitated and peripheral means around the drum may be inspected, repaired, and lubricated in a very simple yet positive manner.

What is claimed is:

1. An electrophotographic copier comprising a housing, a shaft supported in said housing, a carrier adapted to receive an original to be reproduced, a photosensitive drum supported for rotation on said shaft, means for projecting a light image of said original onto the surface of said drum, means for developing electrostatic images formed on said drum surface, means for feeding copy material to said drum, means for transferring said developed electrostatic images to said copy material, means for mixing said transferred images on said copy material and means for cleaning said drum surface, support apparatus for supporting each of said means peripherally of said drum surface, said support apparatus including a unitary support member supporting each of said developing means, said transfer means, said fixing means and said cleaning means and operator-controllable to position each said supported means in operative position relative to said drum surface or in inoperative position remote from said drum surface.

2. The copier claimed in claim 1 wherein said carrier comprises a frame supported by said housing for said reciprocating movement, a transparent member in said frame for supporting said original, support arms pivotally supported by said frame and a pressure plate member pivotally supported by said arms for movement into overlying relation with said transparent member.

3. The copier claimed in claim 1 wherein said projecting means comprises a lamp supported in said housing for illuminating said original and thereby providing said original light image, a first mirror for directing said light image away from said drum surface, means for redirecting said light image onto said drum surface and slit exposure means disposed intermediate said image redirecting means and said drum surface, said image redirecting means including a second mirror and a lens having two symmetrical sections.

4. The copier claimed in claim 1 wherein said feeding means includes signal generator means rendered operative on each feeding of copy material to said drum, said developing means being operatively responsive to said signal generator means.

5. The copier claimed in claim 4 wherein said developing means includes a container for developer toner and carrier, a condensed toner supplier and means responsive to said signal generator means for rendering said supplier operative to supply condensed toner to said container.

6. The copier claimed in claim 1 wherein said photosensitive drum comprises a cylindrical base, a photoconductive layer overlying said base, an insulative layer overlying said photoconductive layer and first and second retaining members respectively secured to opposed ends of said base, said retaining members each having a diameter substantially equal to that of said drum.

7. The copier claimed in claim 1 further including means for separating copy material from said drum, said unitary support member supporting each of said developing means, said transfer means, said separating means, said fixing means and said cleaning means and operator-controllable to position each said supported means in operative position relative to said drum surface or in inoperative position remote from said drum surface.

8. The copier claimed in claim 1 wherein said transfer means includes a roller disposed in pressure contact with said drum surface, a strip member intervening opposed marginal portions of said roller and drum, said copy material feeding means incorporating means for positioning a marginal part of each fed copy material intermediate said strip member and said marginal roller portion and for positioning the remaining part of each fed copy material intermediate said roller and said drum.

9. The copier claimed in claim 1 wherein said fixing means comprises a copy material inlet, a copy material outlet, a pair of rollers supported intermediate said inlet and said outlet, a conveyor encircling said rollers and supported for movement thereby, electrode discharge means for applying charge to said conveyor, and means disposed adjacent said conveyor for heating copy material thereby conveyed.

10. The copier claimed in claim 9 wherein said fixing means includes air ducting means having an exhaust port disposed adjacent said inlet for ducting air heated by said heating means against said conveyor.

11. The copier claimed in claim 9 wherein said support means includes a unitary support element for detachably securing said belt, said rollers and said heating means to said housing.

v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Eatent No. 146 l D d September 5, 1972 'Inventor(s) YOShiO ItO et a1.

It is Certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Title page, item [56] "Eilhorn" should read --Eichorn- Y "Eisbeing" should read '--Eisbein- 3, line 32, after "charging" insert v 4, line 39, "52" should read 53'--. Column 6, line 16, "The current" should read -Current flow".

7, line 30, "roll" should read "roller", I 8, line 32, "rotated" should read --advances--. 8, line 61, "feed" should read "fed- I Column 10, line 17, after "208" insert ----are---.

Column 13, lines. 24-25,: "contact" should read "contacting". j Column 13, line 43, "tonner should read "toner", Column 13, line 65, i delete "over"; I

Column 14, line Y 2, delete "the" (second instance) Signed and T sealed this 1st day of May 1973.

(SEAL) Attest: EDWARD M. FLETCHER, JR. ROBERT GOTTSCHALK 4 Attesting Officer g Commissioner of Patents FORM FO-IOSO (10-69) USCOMM-DC 60376-P69 v U.S,.GOVERNMENT PRINTING OFFICE I969 0-366-334 J