Electrophotographic Copying System

Abstract

An electrophotographic copying system comprising belt-shaped conveying unit which carries a light-sensitive paper and moves it along a closed path. Above the path is fixed a receptacle on which is placed an original to be copied. Between the receptacle and the light-sensitive paper is positioned a movable unit which houses an optical system and charging means. The unit is moved to provide exposure when the light-sensitive paper remains stationary. Upon termination of the exposure, the conveying unit moves the light-sensitive paper on which a latent image is formed through a developing unit, a transfer station and a cleaner unit in sequence. A transfer paper is supplied to the transfer station to effect the transfer of image from the light-sensitive paper, and is separated therefrom by a separation unit after the transfer paper has an image transferred thereto. The separated transfer paper is passed to a fixing unit in order to fix the transferred image.

Parent Case Text

CROSS RELATED APPLICATION

This application is a continuation of copending application Ser. No. 13,668 filed Feb. 24, 1970 and now abandoned.

Description

The invention relates to an electrophotographic copying system adapted for use in office copying, and has as an object the provision of a system which is convenient in operation and inexpensively manufactured.

According to the invention, there is provided an electrophotographic copying system which comprises a receptacle on which is placed an original to be copied, a belt-shaped conveying unit for a light-sensitive paper, the unit having means for loading the light-sensitive paper thereon, exposure means movable between the light-sensitive paper and said receptacle when the light-sensitive paper remains stationary, for projecting an image of the original onto the light-sensitive paper, a developing unit, an image transfer unit and a cleaner unit arranged in turn along the path of movement of the light-sensitive paper, a transfer paper feeder for feeding a transfer paper to a transfer position in synchronism with said belt-shaped light-sensitive paper conveying unit, a transfer paper separation unit for separating the transfer paper from the light-sensitive paper after the transfer paper has moved past the transfer position, and a fixing unit for fixing the image which the transfer paper carries after it has been separated from the light-sensitive paper.

For better understanding of the invention, an embodiment thereof will be described in detail below with reference to the drawings, in which

FIG. 1 is a schematic illustration of one embodiment of the system according to the invention,

FIG. 2 is a perspective view of part of the system, showing the loading means for the forward end of a light-sensitive paper,

FIG. 3 is a view similar to that of FIG. 2, but showing the loading means for the rear end of the light-sensitive paper,

FIG. 4 is a front view of the loading means for the forward end of the light-sensitive paper,

FIG. 5 is a perspective view of the transfer paper separation unit of the system,

FIG. 6 is a side elevation of a transfer station of the system, illustrating the transfer paper separation unit in its raised position, and

FIG. 7 is a view similar to that of FIG. 6, but showing the transfer paper separation unit in its lowered position.

Referring to the drawings, and more particularly to FIG. 1, the copying system includes an optical system comprising parts designated by numerals 1 to 5. Specifically, numeral 1 denotes a support frame for the optical system, and 2 an in-mirror-lens which comprises a rectangular prism and a lens and which acts to reverse the lateral relationship of an image, that is, bringing the right-hand side to the left-hand side and vice versa. Reference character 3a or 3b denotes a reflecting mirror, 4 a lamp for illuminating an original to be copied, and 5 a diaphragm for controlling the amount of light, the diaphragm 5 being pivoted at 5a. The support frame 1 is attached to movable belts 6. The original to be copied is placed on a receptacle shown at 7 on the top of the system. The support frame 1 also carries a corona discharger 8 in its bottom. A pair of light-sensitive papers 9a and 9b are loaded or mounted on an endless belt 10 which runs around rotatable rollers 11a and 11b, the light-sensitive papers being detachably mounted on the belt 10 as will be described later in further detail. Along the path of movement of the light-sensitive papers are disposed in turn a developing unit 12, a corona discharger 16 for transfer purpose, a transfer paper separation unit 17 and a cleaner unit 25. A stack of transfer papers 13 is stored in a container 14, and a rotatable roller 15 takes out the transfer papers sheet by sheet. The taken out transfer paper is guided by a guide plate 18 and fed by rollers 19a, 19b and 19c to a transfer position, where it is held in contact with the light-sensitive paper as the latter moves with the belt. Thereafter the transfer paper is separated from the light-sensitive paper by the transfer paper separation unit 17, and is fed on feed belts 20 and 21, arranged in cascade, to be displaced out of the system. Above the feed belt 21 is located a fixing unit 22. In the present example, the unit 17 and feed belts 20, 21 are arranged to perform special functions which will be more fully described later.

FIG. 2 shows light-sensitive paper loading means which serves the loading or mounting of the forward end of a light-sensitive paper indicated at 40 on the belt 10. The forward end of the light-sensitive paper 40 is formed with a pocket as indicated at 40a, into which is inserted a core rod 41. Numeral 42 denotes a channel-shaped metal fitting fixedly secured to the belt 10 and which receives and supports the core rod 41. The loading means for the rear end of the light-sensitive paper 40 is shown in FIG. 3. The rear end of the light-sensitive paper 40 is also formed with a pocket as indicated at 40b, into which is inserted another core rod 43. Plate members 44 and 45 are secured to the belt 10. The plate member 45 is formed with an elongate slot 46 therein, and a support plate 47 has a guide pin 48 which extends into the slot 46. The support plate 47 is also provided with a channel-shaped support 49 for carrying the core rod 43. A coiled tension spring 50 extends between the support plate 47 and the plate member 44 for maintaining the light-sensitive paper 40 taut or under tension. Numeral 51 denotes an operating handle secured to the support plate 47 and which is used to operate it when loading or unloading the light-sensitive paper 40.

The loading of the light-sensitive paper onto the belt 10 takes place as follows:

Initially the core rod 41 is inserted into the pocket 40a at the forward end of the light-sensitive paper 40, and is mounted in the channel-shaped metal fitting 42. Then the core rod 43 is inserted into the pocket 40b at the rear end of the light-sensitive paper 40, and while pulling the support plate 47 to the left, as viewed in FIG. 3, against the action of the spring 50 by manually holding the handle 51, the core rod 43 is engaged in place within the channel-shaped metal fitting 49. The loading of the light-sensitive paper must be carried out in a manner such that the light-sensitive paper is always loaded in a definite position which is correctly established relative to other parts of the system. This is achieved by a mechanism shown in FIG. 4.

Referring to FIG. 4, on the belt 10 is secured a plate 52 which is formed with a clicking recess 53. Another plate 54 fixedly attached to a stationary part of the system is formed with a clicking aperture 55 at a position which allows its alignment with the recess 53. In this aperture is placed a clicking ball 57 that is held in position by a leaf spring 56. The mechanism just described constitutes a click device, and operates as a detent to hold the belt 10 against motion momentarily when the light-sensitive paper is loaded onto the belt 10. The belt 10 is provided with a number of perforations which are engaged in turn by sprocket pins (not shown) provided on the rollers 11a and 11b for driving the belt. While loading means for the forward and rear ends of the light-sensitive paper are shown only for one side of the light-sensitive paper, it should be understood that corresponding means are also provided on the other side.

FIGS. 5 to 7 show the detailed construction of the transfer paper separation unit 17. A suction box 70 is formed with several elongate slots 71 (only one being shown) for suction of the air. Several perforated belts 72 extend around the suction box 70 and rollers 73 and 74. The roller 73 is a drive roller, and a tensioning roller 75 is positioned intermediate the rollers 73 and 74. The belts 72 are arranged around the suction box 70 so as to overly the elongate slots 71 therein, and their position is controlled by a plurality of flanges 76 on the roller 73. The suction box 70 and the rollers 73, 74 and 75 are carried at their opposite ends by support plates 77a and 77b which are pivoted at 78 to further support plates 79a and 79b. At their freely movable end, the support plates 77a and 77b are connected to the plates 79a and 79b through springs 80 and are provided with cam followers 81a and 81b, respectively, which cooperate with rotary cams 82a and 82b which are mounted on a shaft extending through the plates 79a and 79b. These cams are driven in synchronism with the belt 10 carrying the light-sensitive paper. A suction duct 83 communicates with the interior of the suction box 70, which is divided by a partition wall 84 into compartments A and B. The communication is such that the duct 83 communicates with the compartment A to a greater degree than with the compartment B, so that the resulting suction through the elongate slots 71 is stronger in the part thereof which is positioned over the compartment A than in the part positioned over the compartment B. The arrangement is such that the transfer paper is subjected to a strong suction while in contact with the light-sensitive paper to provide a satisfactory separation therefrom, and is subsequently subjected to a lesser suction, after separation, to be further conveyed under minor suction.

The feed belt 20 is operated at a speed which is less than the feeding speed of the separation unit 17, and the feed belt 21 is designed to convey the transfer paper at a speed which is even more reduced than that of the belt 20. However, this is not critical, and the feed belt 21 can be operated at a speed which is equal to or greater than that of the belt 20, as far as sufficient fixing can be assured. This is accomplished by connecting their respective drive rollers 23 and 24 with a drive shaft (not shown) through differential gearing ratios, which can be arranged in any conventional manner and therefore is not described here in detail.

The system operates as follows:

The light-sensitive paper 9a is loaded as explained previously. The belt 10 remains stationary while the light-sensitive paper 9a is uniformly charged and then imagewise exposed by the movement of the optical system frame 1 in the direction indicated by the corresponding arrow. The lamp 4 and the corona discharger 8 are energized during this movement. The charging followed by imagewise exposure produces a latent electrostatic image on the light-sensitive paper 9a. The termination of the charging and exposure is indicated by the position of the frame 1 shown in chain lines, nd thereafter the belt 10 starts to move in the direction indicated by the corresponding arrow. During the movement of the belt 10, the light-sensitive paper 9a passes by the developing unit 12, transfer corona discharger 16, separation unit 17 and cleaner unit 25 in sequence. While the belt 10 moves, the frame 1 is moved in the opposite direction to return it to its original position shown in solid lines. A transfer paper 13 is supplied and fed in synchronism with the movement of the belt 10, and is superimposed with the light-sensitive paper 9a at the transfer position. After transfer of the image, the transfer paper is separated from the light-sensitive paper by the separation unit 17, and is conveyed on the belts 20 and 21 to be subjected to the fixation of the transfered image by the fixing unit 22, whereafter it is displaced out of the system.

As mentioned above, the belts 20 and 21 operate at reduced speeds. This means that the movement of the transfer paper is slow in passing through the fixing unit 22. As a result, the transfer paper 13 is exposed to heat over a prolonged period, and hence the fixing unit 22 can operate efficiently. This allows that a fixing unit having a relatively small output as compared with the copying rate can be satisfactorily used to provide sufficient fixing function. This improvement concerning the fixing unit is enabled by the fact that light-sensitive papers 9a and 9b are loaded on the belt 10 with a certain spacing therebetween, a similar spacing being provided between successive transfer papers whereby the copying process can be continuously run without interruption of the movement of the belt 10. Hence, a reduction of the speed of the transfer paper subsequent to the transfer step does not result in an overlapping of successive transfer papers. In one specific example the belt 10 had, for instance, a total length of 1,350 mm, and a pair of light-sensitive papers of B-4 size (364 .times. 257 mm) were loaded lengthwise on this belt at symmetrical positions. The belt 10 was driven at 140 mm/sec. A reduction of the speed of the transfer paper at the fixing unit 22, that is, the speed of movement of the belt 21, to 55 mm/sec. did not produce an overlapping of successive transfer papers in a continuous copying run. In this example, the belt 20 was driven at 90 mm/sec. When the transfer paper moves across the space between the separation unit 17 and the belt 20 or between the belts 20 and 21, it merely slips to accommodate for the differential speeds.

As the forward end of the light-sensitive paper 9a moves over the separation unit 17, the suction box 70 is lowered to the position shown in FIG. 7, thereby allowing the free passage of parts such as core rod 41 of the loading means for the forward end of the light-sensitive paper. This is controlled by the cams 82a and 82b which rotate in synchronism with the belt 10 and which have a raised portion situated so as to move the suction box 70 downward through cam followers 81a and 81b when the forward end of the light-sensitive paper 9a has moved past the transfer position. A similar provision is made for allowing free passage of the rear end of the light-sensitive paper 9a over the separation unit 17. The separation unit 17 is shown in its raised position in FIG. 6.

As described above, the light-sensitive paper is loaded on the belt to be driven thereby and is subjected to a transfer procedure. This reduces the manufacturing cost as compared with the prior art systems used in xerography which employ a master plate in the form of a drum. In addition, the exposure is carried out with the light-sensitive paper stationary, which assures an improved quality and particularly improved resolution of copy obtained. A copy made by the use of the transfer technique can be obtained on a conventional paper which has not been subjected to special treatment, and this represents a further advantage compared with prior art copying systems.

Claims

What is claimed is:

1. An electrophotographic copying system comprising a light sensitive sheet adapted for receiving an electrostatic charge and for forming an electrostatic image upon being exposed to a light image, said sheet being provided with at least one transverse pocket, means including an endless belt to convey said sheet through exposure and developing stations repeatedly and means detachably connecting the sheet to the first said means and including a bar coupled to the belt and extending through said pocket.

2. An electrophotographic copy system comprising a displaceable belt, a light sensitive sheet, means detachably connecting the sheet to said belt, means to give the sheet an electrostatic charge, said belt being adapted to displace the sheet through exposure and transfer stations, means to expose the sheet to an image in said exposure station, means to apply a developing substance to the sheet after the sheet has been exposed and transfer means to apply a transfer sheet to the light sensitive sheet to remove the developing substance from the latter and to transfer the image to the transfer sheet in said transfer station, said means which detachably connects the sheet to the belt comprising means covered by said sheet and extending laterally therefrom for detachable attachment to said belt laterally of the sheet and outside the path of travel thereof.

3. A system as claimed in claim 2 comprising means to drive said belt with intermittent movement, said belt holding the light sensitive sheet stationary for exposure to said image.

4. A system as claimed in claim 2 wherein the transfer means includes at least one endless belt bringing the transfer sheet into engagement with the light sensitive sheet and drawing the transfer sheet away from the light sensitive sheet.

5. A system as claimed in claim 2 wherein the means to give the light sensitive sheet a charge is displaceable along the latter said sheet.

6. A system as claimed in claim 2 wherein the means to apply said developing substance physically engages the light sensitive sheet.

7. A system as claimed in claim 2 comprising fixing means for fixing the developed image on the transfer sheet.

8. An electrophotographic copy system comprising a displaceable belt, a light sensitive sheet, means detachably connecting the sheet to said belt, means to give the sheet an electrostatic charge, said belt being adapted to displace the sheet through exposure and transfer stations, means to expose the sheet to an image in said exposure station, means to apply a developing substance to the sheet after the sheet has been exposed and transfer means to apply a transfer sheet to the light sensitive sheet to remove the developing substance from the latter and to transfer the image to the transfer sheet in said transfer station, said light sensitive sheet being provided with a pocket at each end thereof, said means detachably connecting the sheet to the belt comprising a rod engaged in each pocket and extending laterally therefrom and means for securing said rod to said belt at locations laterally spaced from the sheet and outside the path of travel thereof.

9. A system as claimed in claim 8 wherein the rods are loosely supported in the respective pockets.

10. An electrophotographic copying system comprising a light sensitive sheet adapted for receiving an electrostatic charge and for forming an electrostatic image upon being exposed to a light image, means including an endless belt to convey said sheet through exposure and developing stations repeatedly and means detachably connecting the sheet to the endless belt including means covered by said sheet and extending laterally therefrom for detachable attachment to said belt laterally of the sheet and outside the path of travel thereof.

11. An electrophotographic copying system comprising a light sensitive sheet adapted for receiving an electrostatic charge and for forming an electrostatic image upon being exposed to a light image, said sheet having opposite ends with a pocket at each end, means including an endless belt to convey said sheet through exposure and developing stations repeatedly and means detachably connecting the sheet to the belt including a rod engaged in each pocket and extending laterally therefrom and means for securing said rod to said belt at locations laterally spaced from the sheet and outside the path of travel thereof.

12. A system as claimed in claim 11 wherein the rods are loosely supported in the respective pockets.

13. An electrophotographic copying system comprising a receptacle on which is placed an original to be copied, a belt-shaped conveying unit for holding a light-sensitive paper stationary in a first phase and for displacing the light-sensitive paper along a path in a second phase, the unit including means for detachably loading the light-sensitive paper thereon, a unit for charging the light-sensitive paper with a corona discharge before exposure of the paper, exposure means movable between the light-sensitive paper and said receptacle, with the light-sensitive paper remaining stationary, for projecting an image of the original onto the light-sensitive paper, a developing unit, an image transfer unit and a cleaner unit arranged in sequence along the path of movement of the light-sensitive paper, a transfer paper feeder for feeding a transfer paper to a transfer position in synchronism with said belt-shaped light-sensitive paper conveying unit, a transfer paper separation unit for separating the transfer paper from the light-sensitive paper after the transfer paper has moved past the transfer position, and a fixing unit for fixing the image which the transfer paper carries after it has been separated from the light-sensitive paper, said conveying unit being the form of an endless belt running, at least in part, along a flat path, whereby the light-sensitive paper can be loaded onto the belt in a flat configuration, and in which a pair of light-sensitive papers, including the first said light-sensitive paper, are loaded on the endless belt with a spacing between the papers, said papers being alternatively subjected to said exposure means.

14. An electrophotographic copying system according to claim 13, comprising and in which said separation unit is associated with at least one additional conveyor means on which the transfer paper is carried, said additional conveyor means being adapted to be driven at a selected speed less than the speed at which the transfer paper is conveyed by the separation unit, said selected speed being related to the spacing between the pair of light-sensitive papers loaded on the belt so that the system can be continuously run without causing an overlapping of successive transfer papers to occur on said additional conveyor means.

15. An electrophotographic copying system according to claim 14, in which said additional conveyor means comprises a pair of first and second endless belts arranged in cascade manner from the separation unit, said fixing unit being positioned over the second endless belt, said first endless belt being driven at a first speed which is less than the speed at which the transfer paper is conveyed by the separation unit, said second endless belt being driven at a second speed less than said first speed.

16. An electrophotographic copying system according to claim 14, comprising and in which said separation unit is associated with at least one additional conveyor means, said additional conveyor means being adapted to be driven at a speed which is less than the speed at which the transfer paper is conveyed by the separation unit.

17. A system as claimed in claim 13 wherein said means which detachably connects the light sensitive paper to the belt-shaped conveying unit comprises means covered by said light sensitive paper and extending laterally therefrom for detachable attachment to said unit laterally of the light sensitive paper and outside the path of travel thereof.

18. A system as claimed in claim 17 wherein said light sensitive paper is provided with a pocket at each end thereof, said means detachably connecting the paper to the belt-shaped unit comprising a rod engaged in each pocket and extending laterally therefrom and means for securing said rod to said belt-shaped unit at locations laterally spaced from the paper and outside the path of travel thereof.

19. A system as claimed in clain 18 wherein the rods are loosely supported in the respective pockets.