US3784297A

US3784297A - Photocopying machine

Info

Publication number: US3784297A
Application number: US00120132A
Authority: US
Inventors: Y Ito; H Nitanda; M Yamaguchi
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 1970-03-11
Filing date: 1971-03-02
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08
Also published as: DE2166667B2; DE2167105C2; DE2166669A1; DE2166948B2; DE2166667A1; FR2081850B1; FR2081850A1; DE2166667C3; NL7103059A; DE2166669C3; NL7808013A; CA959114A; GB1352752A; DE2166668A1; DE2111759A1; DE2166948A1; DE2166948C3; DE2166669B2

Abstract

An electrophotographic copying machine of this invention has an original holder reciprocating on the upper surface of an electrophotographic photosensitive member which is rotatably fixed to the supporting device therefor. The charging device is arranged on one side of the photosensitive member. The copying machine further includes optical system for slit exposure, developing device, fixing device and cleaning device, which are arranged on the other side of the photosensitive member. Copy sheet feeding device, image transfer device are also arranged below the photosensitive member.

Description

United States Patent [1 1 Ito et a1.

[ PHOTOCOPYING MACHINE [75] Inventors: Yoshio Ito; I-Iajime Katayama; Hiroshi Nitanda, all of Tokyo;

Masaru Yamaguchi, Yokohama, all of Japan [73] Assignee: Canon Kabushiki Kaisha, Tokyo,

Japan 22 Filed: Mar; 2, 1971 211 Appl. No; 120,132

[30] Foreign Application Priority Data Mar. 11, 1970 Japan 45/20075 Apr. 15, 1970 Japan 45/32112 [52] US. Cl 355/3, 355/8, 118/637, 118/4, 271/57 [51] Int. Cl. 603g 15/08, 603g 15/00 [58] Field of Search 355/3, 8, 1O, 11, 355/14; 271/57; 118/637, 7, 4, 8

[56] References Cited UNITED STATES PATENTS 3,358,637 12/1967 Shearer et a1 118/7 3,438,706 4/1969 Tanaka et al7 355/3 UX 3,606,532 9/1971 Shelffo et a1 355/3 1' Jan. 8, 1974 Sugarman, Jr. 355/11 3,331,592 7/1967 Cassano etal 355/11 X 3,501,236 3/1970 Maloney et al.. 355/14 3,150,873 9/1964 MacGregor 271/57 3,604,796 9/1971 Ogawa 355/14 3,374,348 3/1968 Ostensen 355/3 X FOREIGN PATENTS OR APPLlCATIONS 272,158 4/1966 Australia 355/3 Primary Examiner-Robert P. Greiner Att0rneyWard, McElhannon, Brooks, & Fitzpatrick 5 7] ABSTRACT An electrophotographic copying machine of this invention has an original holder reciprocating on the upper surface of an electrophotographic photosensitive member which is rotatably fixed to the supporting device therefor. The charging device is arranged on one side of the photosensitive member. The copying machine further includes optical system for slit exposure, developing device, fixing device and cleaning device, which are arranged on the other side of the photosensitive member. Copy sheet feeding device, image transfer device are also arranged below the photosensitive member.

7 Claims, 44 Drawing Figures PATENTEI] 8 4 SHEET 010F 16 PATENTEU 74 SHEET 030F 16 FIG. 5

PATENTEU JAN 8 I974 saw on or 16 PAINTED 3.784.297

SHE 070? 16 FIG. I5 F PAIENTED 8W 3.784.297 saw near 16 FIG. I6

PATENTEUJAN 8l974 SHEEI '110F 16 PAIENTED 8'974 3.784.297

SHEET 130! 16 FIG. 27

PATENTEU 8W 3.784.297

sum mar 16 PATENTEU JAN 91974 SHE! 15 0f 16 FIG. 32 5) FIG. 32%

FIG. 35(A) FIG. 35(C) FIG. 35(D) FiG. 35(8) PHOTOCOPYING MACHINE BACKGROUND OF THE INVENTION 1. 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 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 of asheet 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 paper hereinafter in this specification).

2. Description of the Prior Art In general, in the electrophotographic 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 origi-v nal. The reproduction cost is high in the electrophoto graphic copying machine 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 machines 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 means 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 disposed 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 rotation 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 whole-surface 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 apositiveor 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 photocopying machine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view illustrating the outer apperance of a 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 original holder; 7

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

FIG. 5 is a perspective view 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 enlarged 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 inFIGS. l and 16;

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

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

FIG. 21 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 section 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 through 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;

FIG. 35 is for explanation 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 sectional 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. 1 shows a perspective view of an embodiment of the present invention showing its outer apperance. Upon an original holder 11 is placed an original with its surface faced down. The original holder 11 is reciprocated for carrying out 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 radiation 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 increasing 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 developing 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 P 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. I 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 present 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 11 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 11 may be prevented by the roller 18 which has a configuration of a drum as shown in FIG. 3 while the vertical deviation may be prevented by the combination of a roller vertically movably fixed to the channellike 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 18. A transparent plate 21 such as a glass plate is mounted on the inner frame 15 of the original holder 1 1 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

1 and 1 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 31, and 31 fixed to the housingJA 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 1 which is associated with a switch MS-l 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 31, 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 isdriven by an electric motor MT through a gear G an idlerG and the drive gear 6., 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 b 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 6,. When the switch MS-l is actuated by the control member CAM-1 of the gear 6., carried by the sensitive drum 1, the clutch C-l 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 ro- .tates 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 1 1, a stroke cam CAM-2 (See FIG. 4) mounted upon the drive gear G actuates a microswitch MS-3 fixed upon the housing so that the clutch C-l 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 of G G G G the clutch G2, G and G In this case, the original holder 11 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 11 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 1 l returns to its initial position, 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 11. A short time after the original holder 11 has been stopped, the clutch O2 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 of a 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 conductingtransparent 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, whereby the original may be uniformly illuminated regardless of the reduction in light quantity or fall-off of luminance in the peripheral portion of the lens 47. As

Claims

1. In a photocopying machine including apparatus for projecting an image on a photosensitive member, means for developing said image on said photosensitive member, and means for transferring said developed image onto a sheet of copy medium, the improvement comprising means for activating said developing means including first and second sensing means disposed in spaced-apart relation with each other in the path of the copy medium, and means for energizing said developing means from the time the leading side edge of the copy medium reaches said first sensing means to the time the trailing side edge of the copy medium passes said second sensing means.

2. A photocopying machine as defined in claim 1 wherein both of said first and second sensing means are microswitches.

3. A photocopying machine as defined in claim 1 wherein said first and second sensing means each comprises a light source, a pair of mirrors and a photoelectric effect element.

4. In a photocopying machine including a photosensitive drum, illumination light source means for illuminating an object to be copied, a mirror and lens system for projecting a light image of said object on said drum, reflector means surrounding said light source means and having a portion cut away, and shielding means for said light source means having a cut-away portion aligned with said cut-away portion of said reflector and disposed with respect to said mirror and lens system to permit pre-exposure of said drum.

5. An electrophotographic copying machine comprising a housing, an original holder reciprocable upon the upper surface of said housing, driving means for reciprocating said original holder, an electrophotographic photosensitive drum disposed substantially at the center of said housing, supporting means for rotatably mounting said photosensitive drum within said housing, charging means, an optical system, and developing means disposed on one side of said electrophotographic photosensitive drum, fixing means and cleaning means disposed on the side of said electrophotographic photosensitive drum opposed to said one side thereof, for fixing a developed image on a sheet of copy medium and for cleaning said photosensitive drum, respectively, copy medium feeding means, and image transfer means disposed below said electrophotographic photosensitive member, wherein said electrophotographic photosensitive drum and supporting means are removable upwardly of said housing, and wherein said feeding means includes means for intermittently activating said developing means to operate only during a predetermined period of movement of said copy medium; and wherein said feeding means includes a first pair of feed rollers and a pair of guide plates mounted on a fixed portion of said housing and a second pair of feed rollers mounted to a side wall of said housing which may be opened so that the path of the copy medium may be accessible.

6. An electrophotographic copying machine comprising a housing, an original holder reciprocable upon the upper surface of said housing, driving means for reciprocating said original holder, an electrophotographic photosensitive drum disposed substantially at the center of said housing, supporting means for rotatably mounting said photosensitive drum within said housing, charging means, an optical system, and developing means disposed on one side of said electrophotographic photosensitive drum, said optical system including a mirror and lens system for projecting a light image on said drum, illumination light source means, reflector means surrounding said light source means and having a portion cut away, and shielding means for said light source means, wherein said shielding means is mounted for removal from one side of said housing, and has a cut-away portion aligned with said cut-away portion of said reflector to permit pre-exposure of said drum, fixIng means and cleaning means disposed on the side of said electrophotographic photosensitive drum opposed to said one side thereof, for fixing a developed image on a sheet of copy medium and for cleaning said photosensitive drum, respectively, copy medium feeding means, and image transfer means disposed below said electrophotographic photosensitive member, wherein said electrophotographic photosensitive drum and supporting means are removable upwardly of said housing, and wherein said feeding means includes means for intermittently activating said developing means to operate only during a predetermined period of movement of said copy medium.

7. An electrophotographic copying machine comprising a housing, an original holder reciprocable upon the upper surface of said housing, driving means for reciprocating said original holder, an electrophotographic photosensitive drum disposed substantially at the center of said housing, supporting means for rotatably mounting said photosensitive drum within said housing, charging means, an optical system, and developing means disposed on one side of said electrophotographic photosensitive drum, fixing means and cleaning means disposed on the side of said electrophotographic photosensitive drum opposed to said one side thereof, for fixing a developed image on a sheet of copy medium and for cleaning said photosensitive drum, respectively, copy medium feeding means, and image transfer means disposed below said electrophotographic photosensitive member, wherein said electrophotographic photosensitive drum and supporting means are removable upwardly of said housing, and wherein said feeding means includes means for intermittently activating said developing means to operate only during a predetermined period of movement of said copy medium, said means for activating said developing means including first and second sensing means disposed in spaced-apart relation with each other in the path of the copy medium, and means for activating said developing means from the time the leading side edge of the copy medium reaches said first sensing means to the time the trailing side edge of the copy medium passes said second sensing means.