US3883240A - Electrophotographic copying machine - Google Patents

Abstract

An electrophotographic copying machine which includes a housing, an original holder reciprocable upon the upper surface of an electrophotographic photosensitive member unit that includes an electrophotographic photosensitive member mounted for rotation at substantially the center of the housing. Charging apparatus is mounted on one side of the electrophotographic photosensitive member and an optical system for effecting exposure through a slit and developing apparatus is provided. Fixing apparatus and cleaning apparatus are disposed on the other side of the electrophotographic photosensitive member. Copy medium feeding elements and image transfer members are disposed below the electrophotosensitive member, and the electrophotosensitive member unit is mounted in the housing so as to be removable upwardly therefrom.

Description

Ito et al. 1 1 May 13, 1975 [541 ELECTROPHOTOGRAPHIC COPYING 3.438.706 4/1969 Tanaka et a]. 3 355 14 x $575,139 4/l97l NuZum .1 .1 118/637 MACHINE 1626.898 l2/l97l Gawron 118/637 [75 1 Invemms' FOREIGN PATENTS OR APPLICATIONS Masaru Yamaguchi Yokohama France 1 v y v 1 r r r r 1 r r of Japan Primary E.ruminer-Richard A. Wintercorn [73] ASS'gnee: Canon Kahush'k' Kalsha Tokyo Armrney, Agent or Firm-Fitzpatrick. Celia. Harper Japan & Scinto [22] Filed: Apr. 5, 1973 [21] Appl. No.; 348,093 [57] P An electrophotographic copying machine wh1ch |n- Relaled pp Dam cludes a housing, an original holder reciprocable upon [62] Division of Ser, N 120,132 M h 2 1971, P r, the upper surface of an electrophotographic photosen- No 3,784,297. sitive member unit that includes an electrophotographic photosensitive member mounted for rotation [30] Foreign Application Priority Data at substantially the center of the housing Charging ap- Man 1] 1970 Japan M 45 20075 paratus is mounted on one side of the electrophoto- Apt |5y [970 japan 45 32| 12 graphic photosensitive member and an optical system for effecting exposure through a slit and developing 52 US. (:1 355/3 on; 117/115; 118/637 apparatus is provided- Fixing apparatus and Cleaning [51] Int. Cl r. G03g 15/00 apparatus are disposfid the Other Side Of the elec- [58] Field of Search 355/3 DD; 118/637; trophowgraphic photosensitive memberpy 17/17 5; mg 1 dium feeding elements and image transfer members are disposed below the electrophotosensitive member, [56] References Ci d and the electrophotosensitive member unit is mounted UNITED STATES PATENTS in the housing so as to be removable upwardly there 3,333 566 8/1967 Kent 355/3 DD from. 3 358.63? 12/1967 Shearer et a1 118/7 5 Claims, 44 Drawing Figures Llll PATENTEUHAY 1 slrs q 883 240 saw near 16 Fh-JENTEU HAY I 31975 3, 883.240

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SHEET lSUF 16 FlG. 35(A) ELECTROPHOTOGRAPIIIC COPYING MACHINE This is a division, of application Ser. No. 120,132, filed 3/2/7l, now U.S. Pat. No. 3,784,297 issued 1/8/74.

BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates to a photocopying machine and more particularly an electrophotographic copying machine of the type in which an original stand is reciprocated, exposure is made through a slit and an electrophotographic photosensitive member is in the form of a rotary drum. More specifically the present invention relates to an electrophotographic copying machine of the type in which an electrophotographic pho tosensitive member consisting of a photoconductive photosensitive member consisting of a photoconductive layer sandwiched between an insulating surface layer and an insulating or conducting member is used and an original in the form ofa sheet or a thick original may be reproduced automatically. rapidly and economically reproduced upon copy media such as sheets of copy paper or the like (to be referred to as copy pa' per" hereinafter in this specification).

2. Description of the Prior Art In general, inthe electrophotographie copying machines available in the market, both of ordinary sheets of paper and photosensitive sheets are used for reproducing an original in the form ofa sheet or a thick original. The reproduction cost is high in the electrophotographic copying macine of the type using photosensitive sheets. Therefore the electrophotographic copying machines of the type using paper sheets are widely used because the cost per copy is very low, However, the electrophotographic photosensitive members which are repetitively used must be replaced when it is damaged. The advantages of the electrophotographic copying machines of the type using paper sheets will be cancelled if the replacement of the electrophotographic photosensitive members is difficult or the readjustment of the electrophotographic copying ma chines is required after the replacement.

SUMMARY OF THE INVENTION One of the objects of the present invention is to provide an improved electrophotographic copying machine (to be referred to as photocopying machine" for brevity hereinafter) which is compact in size because a space required for replacement of an electrophotographic photosensitive member (to be referred to as sensitive member or drum for brevity hereinafter) may be reduced to the minimum and which facilitates the inspection and maintenance of various menas required for the electrophotographic process and disposed around the sensitive drum or member after its removal.

Another object of the present invention is to provide an improved photocopying machine in which various processing means are arranged as units so that the mounting or removal and inspection and maintenance of these various units may be much facilitated.

According to the present invention there is provided an improved photocopying machine in which an original holder upon which is placed an original to be copied is disposed upon the top of the photocopying machine for reciprocal movement and the copy papers are fed one by one by feeding means and discharged after the copying operation.

At the center of the main body of the housing is dis posed a rotary sensitive drum to the peripheral surface of which is applied a lamination consisting of a photoconductive layer sandwiched between an insulating surface layer and an insulating or conducting layer. Around the sensitive drum are disposed first charging means, simultaneous exposure-charging means, whole-surface-illumination means, developing means, third charging means, image transfer means and cleaning means in the order named in the direction of rota tion of the rotary sensitive drum.

The rotary sensitive drum is positively or negatively charged by dc corona discharge generated by the first charging means. The dc corona discharge whose polarity is opposite to that of the dc corona discharge by the first charging means or ac corona discharge is applied to the rotary sensitive drum by the simultaneous exposure-charging means simultaneously when a light or radiation image of the original to be reproduced is exposed or projected upon the rotary sensitive drum. By the wholesurface exposure means, the whole surface of the rotary sensitive drum is uniformly exposed so as to increase the contrast of the image. The electrostatic latent image thus formed may be developed into a positive or negative toner image by the toner which is charged with a polarity opposite to or same as that of the latent image by the developing means. The third charging means is not necessarily required, but may be used with a desired polarity so that the image transfer efficiency may be improved. The toner image thus developed may be transferred by the image transfer means to a copy paper. After the image transfer the toner which still remains upon the rotary sensitive drum is removed or cleaned by the cleaning means. Thus one cycle of copying or reproduction operation is completed as far as the rotary sensitive drum is concerned. The copy paper is separated from the rotary sensitive drum by a separating means and fixed in the fixing means and then discharged out of the photocopy ing machinev BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view illustrating the outer apperance ofa photocopying machine in accordance with the present invention;

FIG. 2 is a longitudinal front view thereof;

FIG. 3 is a transverse sectional view thereof; illustrating a rotary sensitive drum unit and a reciprocable orig inal holder;

FIG. 4 is a top view of the rotary sensitive drum unit;

FIG. 5 is a perspective veiw of the original holder and its reciprocating means,

FIG. 6 is a perspective view illustrating the mounting and removal of the rotary sensitive drum unit;

FIG. 7 is a view illustrating the mounting and removal of means for illuminating the original and charging means unit;

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

FIG. 9 is a perspective view illustrating means for supplying the developing agent to the developing means;

FIG. 10 is a fragmentary front view thereof on en- Iarged scale;

FIG. 11 is a side view thereof;

FIG. 12 is a top view of means for circulating the developing agent in the developing means;

FIG. 13 is a longitudinal front view of another embodiment of means for supplying the developing agent in accordance with the present invention;

FIG. 14 is a side view thereof;

FIGS. 15 and 16 are side views illustrating one embodiment of means for opening or closing a discharge opening of a hopper;

FIGS. 17 and 18 are front view illustrating means for adjusting an angle of rotation of a spiral feed roller disposed in the hopper shown in FIGS. 15 and 16;

FIG. 19 is a perspective view of the opening and closing means shown in FIGS. 15 and 16;

FIG. 20 is a front view of one embodiment of a passage of copy paper;

FIG. 2] is a fragmentary perspective view thereof on enlarged scale;

FIG. 22 is a front view of one embodiment of means for controlling the activation and de-activation of the developing means;

FIG. 23 is an electric circuit diagram thereof.

FIG. 24 is a perspective view of one embodiment of fixing means in accordance with the present invention;

FIG. 25 is a front view thereof;

FIG. 26 is a longitudinal view thereof;

FIG. 27 is a sectional view of one embodiment of cleaning means in accordance with the present invention;

FIG. 28 is a fragmentary top view thereof on enlarged scale;

FIG. 29 is a sectional view of another embodiment of cleaning means in accordance with the present invention;

FIGS. 30, 31, 32(A), 32(8) and 33 are views illustrating brushes used in the cleaning means for removing the developing agent;

FIG. 34 is a view illustrating one embodiment of means for moving the developing agent removed in the cleaning means to a collection box;

FIGS. 35(A) through 35(D) are an illustration of a method for applying on and removing from a roller a cleaning material in accordance with the present invention;

FIG. 36 is a front view illustrating means for controlling the rotation of a cleaning roller;

FIG. 37 is a sectional view thereof;

FIG. 38 is a longitudinal view of one embodiment of charging means in accordance with the present invention;

FIG. 39 is a top view thereof; and

FIG. 40 is a transverse sectional view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. I shows a perspective view of an embodiment of the present invention showing its outer apperance. Upon an original holder 1] is placed an original with its surface faced down. The original holder II is reciprocated for carrying the slit exposure. The sheets of copy paper P are fed one by one by a feeding means, processed by an electrophotographic device and discharged out of an outlet 12.

Referring to FIG. 2, upon the peripheral surface of a drum 2 rotating in the direction indicated by the arrow is formed an electrophotographic sensitive layer 1 consisting ofa photoconductive layer sandwiched between a surface insulating layer and a conducting or insulating layer. Around the rotary drum 2 are disposed in the order named a first charging means 3, a simultaneous exposure-charging means 5, a whole-surface exposure means 6, a developing means 7, a third charging means 8, a transfer means 9 and a cleaning means l0.

The DC corona discharge is imparted by the first charging means 4 to the surface of the rotary sensitive drum 2 so that the sensitive layer 3 may be positively or negatively charged. By the simultaneous exposurecharging means 5 the DC corona discharge having the polarity opposite to that applied by the first charging means 4 or the AC corona discharge is applied to the sensitive layer 3 simultaneously when a light or radia tion image of the original to be copied is projected upon the sensitive layer 3 or drum 1 to produce an electrostatic image.

Thereafter by the whole-surface exposure means 6 such as fluorescent lamp the electrostatic latent image is uniformly illuminated so as to increase the action of the latent image as the external field, thereby increas ing the contrast of the electrostatic latent image. By use of the toner having the polarity opposite to that of the electrostatic latent image. it is developed by the devel oping means 7. Alternatively, the electrostatic latent image may be developed into a negative image by use of the toner having the same polarity as that of the latent image. It is preferable to use the magnet brush or fur brush developing method.

The third charging means 8 is not necessarily required. However. it is used with a suitable polarity so as to improve the efficiency of transferring to the copy paper P the toner image formed upon the sensitive drum 1. The toner image is transferred electrostatically to the copy paper I by the transfer means 9. The toner still remained upon the sensitive drum 1 after the image transfer is wiped off by cleaning rollers in the cleaning means 10.

The copy paper P upon which is transferred the toner image from the sensitive drum 1 is separated from the sensitive drum by a separating means, fixed by the fixing means and discharged out of the photocopying machine from the outlet 12. Since the copy paper P is charged, the electrostatic charge is removed from the copy paper P by an AC charging means 30.

In addition to the means described above, the photocopying machine in accordance with the present invention further includes driving means, exposure means, feeding means. control means and so on and the pres ent invention is characterized by the arrangement thereof and the assembly and disassembly thereof as will be described in more detail hereinafter.

ORIGINAL HOLDER AND DRIVING MEANS As shown in FIG. 3, the original holder II has two rollers 17 and 18. The roller 17 rides on a rail 13 extending between frames of the housing while the roller 18 is enclosed in a channel-like member 16 and rides on a rail 14 mounted between the frames. It is noted that the rail 14 and the roller 18 in the channel like member 16 are disposed below an inner frame 15 of the original holder 11. The deviation in the transverse direction, that is to the right and left of the original holder ll may be prevented by the roller 18 which has a configuration ofa drum as shown in FIG. 3 while the vertical deviation may be prevented by the combination ofa roller vertically movably fixed to the channel- Iike member 16 and made in contact with the undersurface of the rail 14 under the force of a spring 20 loaded between the lower roller 19 and the upper roller I8. A transparent plate 21 such as a glass plate is mounted on the inner frame of the original holder 11 and a pressure plate 22 for pressing the original against the transparent plate 21 is provided.

Still referring to FIG. 3, a shaft 27 of the sensitive drum 1 extending through bearings 23 of end plates I and I is supported by supporting plates 25 and 25 and retained by retaining members 26 and 26 Stays 24 are fixed to the supporting plates 26 and 26 which in turn are fixed to side plates 3I and 31 fixed to the housing. A driving gear 30 is mounted on a boss of the sensitive drum 1. Thus, the sensitive drum unit is constituted.

A drive gear G for driving the sensitive drum unit is provided with a control member CAM l which is associated with a switch MS-I mounted upon the side plate 31 for controlling the original holder, a counter and the toner supply.

Ridges 33 are formed on the supporting plates 25 and 25 while their mating grooves 32 are formed in the side plates 3I, and 31 as shown in FIGS. 4 and 6 so that the drum unit may be easily, rapidly and vertically mounted on or removed out of the side plates 31 and 31 The drum unit may be securely held in position by means of setscrews 34.

The sensitive drum 1 is driven by an electric motor MT through a gear G an idler G and the drive gear G carried by the drum shaft 27. The sensitive drum 1 is always rotated in a predetermined direction in operation.

The original holder 11 is moved in the direction indicated by the arrow a in FIG. 2 when the exposure is made, and upon completion of the exposure the original holder 11 is reversed in the direction of the arrow 1) to the initial position. For this purpose, two belts or wires 35 and 36 are wrapped around a guide pulley R and a drive pulley PL in the opposite directions. One ends of the belts or wires 35 and 36 are fixed to the channel-like member 16 while the other ends to the drive pulley PL. In order to make one reciprocation of the original holder in one cycle operation, two clutches C-1 and C-2 are provided as shown in FIG. 4.

In response to a signal from a start button, the main motor MT starts to rotate the sensitive drum 1 through the gears G G and G When the switch MS-] is actuated by the control member CAM-l of the gear G carried by the sensitive drum 1, the clutch C1 is actuated so as to transmit the power from the main motor MT to a drive gear G,. through the gears G G clutch C-l, and a gear G The drive gear G is carried by a shaft 37 which also carries the pulley PL. Therefore the drive pulley 37 rotates in the direction of the arrow C in FIG. 5, winding the wire 35 while unwinding the wire 36. As a consequence. the original holder 11 is moved in the direction indicated by the arrow a at a predetermined speed, so that the original is exposed through a slit and the light image is continuously projected upon the sensitive drum 1 through the simultaneous exposure-charging means 5. As a consequence, an electrostatic latent image is formed upon the sensitive drum 1 which has been previously charged by the first charging means 4.

The peripheral speed of the sensitive drum 1 relative to the speed of the original holder 11 in the direction of the arrow a is predetermined. Upon completion of the going stroke of the original holder 11, a stroke cam CAM-2 (See FIG. 4) mounted upon the drive gear 0,, actuates a microswitch MS-3 fixed upon the housing so that the clutch O1 is disengaged while the clutch C-2 is engaged. Whereas the sensitive drum 1 rotates in the same direction, the original holder 11 is returned to its initial position in the direction indicated by the arrow b by the gear train ofG G G G the clutch C-2, G and G In this case, the original holder II may be returned quickly when the number of teeth of the gear G which is in mesh with the gear G used in the return stroke of the original holder I1 is less than that of the gear used in the going stroke. Thie quick return stroke permits the high speed copying operation.

When the original holder 11 returns to its initial posi tion, the stroke cam CAM-3 of the drive gear G actuates a microswitch MS-2 (See FIG. 4) so that the main motor MT is temporarily applied with brake so as to stop the original holder II. A short time after the original holder II has been stopped, the clutch C-2 is disengaged so that the original holder 11 is completely disconnected from the main motor MT so that the original holder 11 may be held in its initial position. Simultaneously the sensitive drum 1 is also stopped. The above described two-step operation of first stopping the original holder 11 and then disconnecting it from its driving means is employed to absorb the inertia of the original holder in its return stroke.

EXPOSURE MEANS As shown in FIGS. 2 and 7, an illumination system 40 includes a light source such as fluorescent lamps 41 for illuminating the original, shielding plates 42 and cooling means such as a fan (not shown) which is used for cooling the lamps 41 so as to prevent the decrease of its illumination efficiency.

The cooling air from the fan is directed in the longitudinal direction ofa space defined by the original holder 11, the shielding plates 42 and a black box 43 so that the fluorescent lamps 41 may be cooled along their entire lengths. When the fluorescent lamps 41 are turned on for exposure, a current twice the rated current is supplied to increase the luminous intensity. However, when no exposure is made, the lamps 41 are normally turned on by the rated current so that there may be no warming-up time and that its service life may be increased.

Light reflected by the original passes through a transparent plate 45 retained in position by a retaining member 44 for preventing the dust or the like from entering the black box 43 and is re-directed by a first reflecting mirror 46 inclined at 45 relative to the horizontal line toward an in-mirror type lens 47. The in-mirror type lens 47 has such a construction that the conventional lens is divided into two parts along its symmetrical axis and a mirror 48 is disposed at the center so that light reflected by the second mirror 48 may pass through the lens 47 and a transparent plate 49 for preventing the dust or the like from entering the black box 43 and may be projected upon the sensitive drum 1 through an opening of the simultaneous-exposure-charging means 5. A conducting transparent plate such as NESA glass may be used as the dust-proof transparent plate 49 so that the charging efficiency of the simultaneous exposure-charging means 5 may be improved.

As shown in FIG. 2, a reflector 50 for the lamp 41 is partly cut away so that the intensity of light from a portion of the lamp 41 having no reflector may be reduced,

Claims (5)

1. An electrophotographic copying machine comprising a housing, an original holder reciprocable upon the upper surface of an electrophotographic photosensitive member unit comprising an electrophotographic photosensitive member disposed substantially at the center of said housing and supporting means for rotatably fixing said member, charging means disposed on one side of said electrophotographic photosensitive member, an optical exposure system located to one side of said electrophotographic photosensitive member for effecting an image exposure through a slit, developing means, fixing means, cleaning means, said fixing and cleaning means being disposed on the other side of said electrophotographic photosensitive member, copy medium feeding means, and image transfer means, both of which are disposed below said electrophotographic photosensitive member, said electrophotographic photosensitive member unit being mounted in said housing so as to be removed upwardly therefrom.

2. A photocopying machine as defined in claim 1 wherein said developing means includes a container for storing a developing agent, two magnet brushes rotatably fixed between side plates of said developing means, doctor blades for defining the diameters of said magnet brushes, and two mixing rolls which are disposed one both sides of a partition wall and rotate in the opposite directions so as to transport the developing agent, said mixing rolls being provided with right- and left-handed screws, said partition wall having an opening through which the toner flows, said opening being located in such a position where said right- and left-handed screw threads meet.

3. A photocopying machine as defined in claim 2 wherein said opening is so defined that the flow rate of the toner through said opening is less than the quantity of the toner fed by said mixing rollers.

4. A photocopying machine as defined in claim 2 wherein said developing means further includes means for replenishing the developing agent, said replenishing means includes a hopper at the bottom of which is disposed a feed screw or spiral roller and means for intermittently driving said feed screw, and said hopper further includes a mixing member in engagement with said screw or spiral feed roller for intermittent rotation, and the developing agent is supplied into said developing agent container having a supply opening formed in the top wall thereof.

5. A photocopying machine as defined in claim 4 wherein said opening of said developing agent container is opened and closed in response to opening and closing of a discharge port of said hopper.

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