US3838920A

US3838920A - Electrophotographic copying apparatus

Info

Publication number: US3838920A
Application number: US00352454A
Authority: US
Inventors: I Terashima; O Otubo
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1972-04-21
Filing date: 1972-04-18
Publication date: 1974-10-01
Anticipated expiration: 1991-10-01
Also published as: JPS544618B2; AU5483273A; FR2181006B1; FR2181006A1; DE2320095A1; GB1401903A; DE2320095B2; JPS493634A

Abstract

In an electrophotographic copying apparatus, a manuscript fixed on a casing is irradiated by a light source to focus the light reflected from the manuscript on a record paper through an optical system; the record paper is uniformly electrified before exposure; the electrified and exposed record paper is treated for development with at least two different developing agents; and the record paper placed on the proper exposure position is held substantially horizontal while the exposing and developing treatment is performed.

Description

United States Patent Terashima et al. Oct. 1, 1974 [5 ELECTROPHOTOGRAPHIC COPYING 3,536,399 10/1970 Herman 355/10 X PP S 3,637,302 1/l972 Hunt et al 3,705,767 l2/l972 Tamai et al 355/4 [75] Inventors: Isamu Terashima; Osamu Otubo,

both of Hitachi, Japan P E R b P G rimary xaminer 0 ert reiner [73] Asslgnee' Hatachl Tokyo Japan Attorney, Agent, or Firm-Craig & Antonelli [22] Filed: Apr. 18, 1972 [21] Appl. No.: 352,454 ABSTRACT [30] Foreign Application Priority Data In an electrophotographic copying apparatus, a manu- Apr. 12, 1972 Japan 47-39584 Script fixed a Casing is irradiated by a light Source to focus the light reflected from the manuscript on a 52 US. Cl 355/4, 355/10, 355/72, record Paper through an Optical System; the record 96/1 LY, 117/37 LE, g/ G 23, 96/12 paper is uniformly electrified before exposure; the 51 Int. Cl. G03g 15/00, G03g 15/10 electrified and exposed record P p is treated for [58] Field of Search 355/4, 10, 3, 8,72; velopmem with at least two different developing 96/12, 1 7 7 118/D]G 23 agents; and the record paper placed on the proper exposure position is held substantially horizontal while 5 References Cited the exposing and developing treatment is performed. UNITED STATES PATENTS 7 Claims 9 Drawing Figures 3,467,468 /1969 Johnson 355/4 PAIENIEDnm M914 Wmmw 1 19M 3.838.920

SHEET 30$ 6 FIG?) PMEMEMBI H974 sum 5 HF FIG.8

ELECTROPHOTOGRAPHIC COPYING APPARATUS The present invention relates to an electrophotographic copying apparatus and more particularly to a color electrophotographic copying apparatus.

In order to reproduce a color image from a manuscript with high fidelity, it is necessary to decompose the light reflected from the manuscript through filters and to apply in an appropriate thickness developing agents corresponding to decomposed colors to the respective portions of the record paper corresponding to the original image on the manuscript.

Especially, the gradation in the developing thickness is the most important factor in the reproduction of colors of the manuscript through the overlapped application of a plurality of developing agents.

The gradation of the wet type electrophotography is very excellent as compared with that of the other type electrophotography. Namely, if an electrode is disposed in the vicinity of and parallel to the record paper when the developing agents are applied to the exposed surface of the paper, then a developed image having the same gradation and uniformity can be created very rapidly.

In the conventional color electrophotography has been used a record paper comprising a base paper having an appropriate electric resistance and a photoconductive layer formed on the base paper as a photosensitive layer. After the sensitive surface of the record paper has been uniformly electrified, the image on the manuscript is projected on the surface through a first color filter and then a first developing agent is applied to complete the first image production process.

Next, the same record paper is again uniformly electrified, the exposure is perform through a second color filter, and a second developing agent is overlapped on the first color image to complete the second image production process.

After completing such processes as described sequentially several times (usually three to four times), a complete color copy is obtained.

In the reproduction of color images according to this procedure. the proper registration of the different color images must be maintained. However, since in this procedure the record paper is wet after the second process, it can not be rigid enough to be subjected to color registration as in an ordinary color printing.

Therefore, many devices have been proposed which securely hold the record paper at a predetermined position until all the processes have been completed and automatically attach or detach the paper. However, all the proposed devices are very complicated in structure and therefore difficult to handle.

According to the present invention which has been made to eliminate such difficulties as mentioned above, a base is held exactly horizontal so that the record paper transported by a transport belt may have its sensitive surface disposed substantially parallel to the surface of the manuscript and one object of the present invention is to improve the degree of flatness of the record paper and the precision of the formed images.

Another object of the present invention is to make the developing means movable relative to the record paper and to make the base means to hold the transport belthorizontally movable in timing with the movement of the developing means.

A further object of the present invention is to enable the base means to fold with the movement of the developing means and therefore to securely hold the base means and the developing means at their predetermined positions by moving the base means in timing with the movement of the developing means.

An additional object of the present invention is to enable the base drive motor to drive the base drive shaft by connecting the base means with the shaft via a base drive arm.

A yet another object of the present invention is to increase the torque of the base drive motor driving the shaft by connecting a balance weight with the shaft via a balance arm.

Therefore, the present invention is characterized mainly by comprising an electrifier, an exposure means, a developing means, and a base means, the electrifier, the exposure means and the developing means being movable relative to the record paper fixed to a predetermined position and the base means serving to maintain the record paper substantially horizontal and being movable during developing process relative to the record paper in timing with the movement of the developing means.

Now, the present invention will be described by reference to the attached drawings, in which FIG. I is a vertical cross section of the device as a whole, according to the present invention;

FIG. 2 is a vertical cross section of the base drive section, partially enlarged, of the device shown in FIG. 1;

FIG. 3 is a side view of the base drive section shown in FIG. 2;

FIG. 4 is a diagrammatic representation of the movement of the base;

FIG. 5 is a control circuit for a pinion driven by a base drive motor;

FIGS. 6 to 9 show on enlarged scales base drive sections as other embodiments of the present invention.

Reference should first be made to FIG. 1. In this figure. a casing I which serves to block the external lights and also serves as an outer cover, has in its upper surface a transparent plate 3 on which a manuscript 2 to be copied is placed. An exposure means 4 serves to turn the light emitted from a lamp 5 and reflected from the copying surface of the manuscript 2 onto a record paper 6. An clectrifier 7 serves to uniformly charge the light-receiving surface of the record paper 6, the electrifier 7 being fixed to the exposure means 4 so as to be reversibly movable with the exposure means 4 within the internal defined between the extremities A and A.

A developing means 8 for developing the exposed record paper in accordance with an image forming process comprises at least two developing troughs 9 filled respectively with different developing agents for different colors, the developing means 8 being mounted on rails 10 with wheels 11 therebetween so that the means 8 may be reversibly translated between the extremities B and B. A transport belt 12 is supported on a plurality of roller 13a 13d and serves to automatically feed the record paper 6 stored in a roll to the place where it is exposed. The transport belt 12 is driven via a roller 14 equipped in the developing means 8 by a belt drive motor 15. A movable base 16 is made of an electric conductor and has inhalation holes 17 in its upper surface and a suction fan (not shown) on its lower surface. The movable base 16 and an auxiliary base 18 having almost the same structure are arranged under the transport belt 12 to convey the record paper 6. These

bases

16 and 18 are coupled to each other by means of a coupling mechanism 19 so that the surfaces of the

bases

16 and 18 brought into contact with the surface of the belt 12 may be in the same plane. As shown with alternatelong-and-two-short-dash line in FIG. 1, the

bases

16 and 18 can fold at the coupling mechanism 19 by means of a link 20 and a pin 21.

The auxiliary base 18 has an arm 22 rigidly fixed to the end most remote from the coupling mechanism 19, which arm is swingably supported on a connecting pin 23 provided in a portion of the side wall of the developing means 8 while the end of the movable base 16 most remote from the coupling mechanism 19 is provided with an arm 24 mechanically coupled to a base drive shaft 25.

As shown in FIGS. 2 and 3, the base drive shaft 25 has on one end thereof a partially cogged or toothed disc 27, that is, a disc only a portion of whose circumference is provided with cogs or teeth 26, and on the other hand a balance weight 29 with a balance arm 28.

A base drive motor 30 is fixedly mounted on a side plate 31 by means of a metal piece 32 and the shaft 33 of the motor 30 is provided with a sprocket 34 mechanically coupled by means of chain 35 to a sprocket 37 provided on an electromagnetic clutch 36.

A pinion 38 is engaged with the cogs 26 of the partially cogged disc 27 and the drive power of the motor 30 is transmitted via the pinion 38 to the disc 27 by means of the clutch 36.

A cam 39 is fixed to the partially cogged disc 27 and serves to render a cam switch 40 off which is being turned on while the movable base 16 shifts and rotates by means of the cam 39 from its horizontal position to its another position of angle 6 (shown in FIG. 1), so that the current conduction through the electromagnetic clutch 36 may be controlled. The rotation of the partially cogged disc 27 is limited in such a manner that the movable base 16 and the auxiliary base 18 may maintain their horizontal positions by means of a stopper 41.

A paper fixer 42 serves to fix one end of the record paper 6 so as to maintain the paper 6 exactly on the place where it is irradiated by the exposure light.

FIG. shows a circuit for controlling the pinion 38 driven by the base drive motor 30. As seen in FIG. 5, the motor 30 is so connected with a power source 44 through a switch 43 that it may be rotated reversibly or in both the forward and backward directions, and the electromagnetic clutch 36 is connected through the cam switch 40 with a dc. source 45. Therefore. the drive force of the motor 30 is transmitted through the clutch 36 to the pinion 38.

Now, the operation of the above described structure will be considered. First, the starting switch provided externally (not shown) is rendered on. then the belt drive motor starts rotating and the transport belt 12 is rotated clockwise by means of the roller 14 (see FIG. 1). At this time. the surfaces of the movable and

auxiliary bases

16 and 18 brought into contact with the transport belt 12 are maintained almost horizontal so that the record paper 6, supplied from the roll and cut in an appropriate size, is fed by means of the transport belt 12 onto the exposure position, where one end of the paper 6 is rigidly clamped by the paper fixer 42.

When the record paper 6 is fixed on a predetermined position of the transport belt 12, the clectrifier 7. which is opposite to the upper sensitive surface of the paper 6 with a slight space therebetween is energized and translated rightward in FIG. 1 (from A to A) so as to uniformly charge the exposure surface of the record paper 6. As soon as the electrifier 7 has reached the position A. the current through the electrifier 7 is interrupted and simultaneously the exposure means 4 moves toward the position A. Then. the lamp 4 is lit to irradiate the manuscript 2 and the record paper 6 is appropriately exposed to the light reflected from the manuscript 2.

If the belt drive motor 15 is rotated while the transport belt 12 is fixed at the guide roller 13a. then the belt 12 is drawn to the roller 14 due to the mechanism between them with the result that the developing means 8 to which the roller 14 is attached tends to move from the point P to the point P in FIG. 4. However. the developing means 8 is prevented from moving by the movable base 16 and the auxiliary base 18 in horizontal positions. At this time. the cam switch 40 is closed so that the electromagnetic clutch 36 is energized by the dc. source and the rotating torque of the base drive motor 30 is transmitted through the electromagnetic clutch 36 to the pinion 38.

Accordingly. the pinion 38 is engaged with the cogs 26 of the partially cogged disc 27 to cause the base drive shaft 25 to rotate clockwise in FIG. 2. Therefore. the movable base 16 resting in the horizontal position rotates clockwise about the base drive shaft 25 and simultaneously the developing means 8 also starts moving toward the position P that is. toward the position B in FIG. 1.

As the developing means 8 moves a distance of! in FIG. 1, the movable base 16 rotates through an angle of 0 from its resting horizontal position. As a result of this, the pinion 38 is disengaged from the cogs 26 of the disc 27 to open the cam switch 40 so that the rotating torque of the base drive motor 30 is no longer transmitted to the pinion 38. The drive motor 30 then continues a non-load performance. The developing means 8 still continues to move toward the position P, due to the action of the motor 15 so that the movable base 16 and the auxiliary base 18 will move to the extent that they are folded together, suspending almost vertically as shown in FIG. 4. Accordingly. the record paper 6 whose one end is fixed on a belt 12 is conveyed into the developing trough 9 of the developing means 8 by means of the guide rollers 13s and 13f to develop the record paper which developing trough has a first developing agent therein 12.

As soon as the developing means 8 has reached the position P in FIG. 4, the belt drive motor 15 starts rotating inversely to cause the means 8 to return to the initial position P... At this time. the base drive motor 30 as well as the belt drive motor 15 is switched over to assume reverse rotation by a change-over switch 44 and they are in no-load performance since the cam switch 40 is now open.

The developing means 8 continues to be driven by the belt drive motor 15 until it has reached the point P, spaced apart by I from the point P and when it has reached the point P the weights of the movable and

auxiliary bases

16 and 18 are added to the load of the belt drive motor 15 driving the developing means 8. Consequently, the load on the belt drive motor 15 increases in inverse proportion to the sine of the angle 0, Le. sin6, subtended by the movable base 16 with respect to its horizontal position so that it is impossible to restore the developing means 8 together with the

bases

16 and 18 to their initial positions solely with the power of the belt drive motor 15.

However, as soon as the developing means 8 has reached the point P,, the cam switch 40 is closed to energize the electromagnetic clutch 36 so that the torque of the base drive motor 30 is transmitted through the electromagnetic clutch 36 to the pinion 38. Accordingly, the torque of the base drive motor 30 transmitted to the cogs 26 of the partially cogged disc 27 engaged with the pinion 38 and the torque of the base drive shaft'25 due to the balance weight 29 connected via the balance arm 28 with the shaft 25, act on the base drive shaft 25 so that the torque output of the belt drive motor is increased to restore the

bases

16 and 18 to the initial positions and the developing means 8 to the position P Thereafter, the base drive motor 30 and the electromagnetic clutch 36 are energized continuously to further drive the base drive shaft and then the rotation of the partially cogged disc 27 is stopped by the stopper 41 provided corresponding to the horizontal positions of the

bases

16 and 18 when the cogs 26 of the disc 27 butts against the stopper 41, so that the movable base 16 and the auxiliary base 18 coupled thereto are brought and held substantially in their horizontal positions. The balance weight 29 serves to relax the constrained condition of the base drive motor and also to add to the output torque of the base drive motor 30.

When the movable and

auxiliary bases

16 and 18 are thus restored to the resting position, the electrifier 7 is again energized, moves to the position A, and charges the record paper 6 uniformly. Then, the exposure means 4 moves toward the position A and the record paper 6 is subjected to exposure. After the exposure step has been completed, the belt drive motor 15 and the base drive motor 30 are again inversely rotated to perform the next step of development immediately in which the record paper is conveyed into a developing trough 9 having a second developing agent therein.

With the structure as described above, the developing treatment can be performed with the record paper 6 fixed on the transport belt 2, and moreover in the steps of electrification and exposure the record paper can be in an exact flat surface so that the preciseness in the focussed image on the record paper can be improved.

FIG. 6 shows a second embodiment of the present invention, in which one end of the movable base 16 is swingably supported by a pin rod 50, a slide plate 52 having slit 51 is attached to the lower end portion of the base 16 and a slider 53 urged by means of a spring 54 locked to a pin 55 is inserted in the slit 51.

With this constitution, in the steps of electrification and exposure the slider 53 is in the right end of the slit 51 of the slide plate 52 and the restoring force of the spring 54 bears the weights of the movable base 16 and the auxiliary base 18 linked therewith to hold both the bases in their horizontal position. After the completion of the step of exposure, the slider 53 moves in the slit 51 of the slide plate 52 to the left of the pin rod 50 of the movable base 16 and the movable and

auxiliary bases

16 and 18 assume such a state as shown in FIG.

7 due to the restoring force of the spring 54 locked at one end to the pin rod 50 so that the developing means 8 mechanically coupled by mean of the pin 23 to the auxiliary base 18 moves leftward to develop the record paper 6.

FIG. 8 shows a third embodiment of the present invention, in which a long slit 56 is cut longitudinally in the movable base 16 and a slide pin 57 is set in the slit 56 so that the movable base 16 and the developing means 8 coupled thereto can move horizontally. guided by the slide pin 57.

FIG. 9 shows a fourth embodiment of the present invention. In this embodiment, the one end of the movable base 16 is supported swingably on the pin rod 50 while to the other end of the base 16 is fastened a length of wire 58 which is wound about a rotating shaft 59 provided in the developing means 8. With this structure, the movable base 16 rotates about the pin rod 50 according to the movement of the developing means 8 and the wire 58 is wound up or unwound by the rotating shaft 59 in timing with the rotation of the movable base 16.

It should be noted in the end of the description of the invention that the present invention has hitheto been described only by way of embodiments but that the invention is not limited to the described embodiments alone but resticted solely by the appended claims.

What we claim is:

1. An electrophotographic copying apparatus comprising exposure means for illuminating with a light source a manuscript placed on a casing and causing a record paper located at a predetermined exposure position to be exposed through an optical system to light reflected from said manuscript, transport means for transporting a record paper to said exposure'position. electrifier means for uniformly charging the sensitive surface of the record paper placed at said exposure position, movable developing means for moving with respect to the exposed record paper to develop the exposed record paper in accordance with an imageforming process, and base means for movement in response to the movement of said developing means to develop the exposed record paper from a first position where said base means serves for holding the transported record paper at said exposure position during charging by said electrifier means and exposure by said exposure means to a second position outside the path of the movement of said developing means.

2. An electrophotographic copying apparatus as claimed in claim 1, further comprising a drive shaft connected to said base means and also to a base drive motor for transmitting the rotating torque of said drive motor to said base means, and a balance arm mounted to said drive shaft and provided at one end thereof with a balance weight, said balance weight aiding the rotation of said drive shaft.

3. An electrophotographic copying apparatus as claimed in claim 2, wherein said base means has one end thereof connected to said drive shaft through a rotatable base drive arm, and said drive shaft is provided with a disc having teeth extending partially about the circumference thereof, and a pinion member driven by said drive motor engages the teeth of said disc for driv- I ing said disc.

4. An electrophotographic copying apparatus as claimed in claim 3, wherein said drive motor is connected with an electric power source for rotation both in forward and backward directions and further comprising an electromagnetic clutch for drivingly connecting said drive motor and said pinion member. said electromagnetic clutch being energized through a cam switch which is maintained in the closed condition during the rotation of said base drive arm from the first position of said base means through a predetermined angle 0.

5. An electrophotographic copying apparatus as claimed in claim 1, wherein said developing means includes a plurality of developing troughs, each trough containing a different developing agent.

together when said developing means moves.

Claims

1. An electrophotographic copying apparatus comprising exposure means for illuminating with a light source a manuscript placed on a casing and causing a record paper located at a predetermined exposure position to be exposed through an optical system to light reflected from said manuscript, transport means for transporting a record paper to said exposure position, electrifier Means for uniformly charging the sensitive surface of the record paper placed at said exposure position, movable developing means for moving with respect to the exposed record paper to develop the exposed record paper in accordance with an image-forming process, and base means for movement in response to the movement of said developing means to develop the exposed record paper from a first position where said base means serves for holding the transported record paper at said exposure position during charging by said electrifier means and exposure by said exposure means to a second position outside the path of the movement of said developing means.

3. An electrophotographic copying apparatus as claimed in claim 2, wherein said base means has one end thereof connected to said drive shaft through a rotatable base drive arm, and said drive shaft is provided with a disc having teeth extending partially about the circumference thereof, and a pinion member driven by said drive motor engages the teeth of said disc for driving said disc.

4. An electrophotographic copying apparatus as claimed in claim 3, wherein said drive motor is connected with an electric power source for rotation both in forward and backward directions and further comprising an electromagnetic clutch for drivingly connecting said drive motor and said pinion member, said electromagnetic clutch being energized through a cam switch which is maintained in the closed condition during the rotation of said base drive arm from the first position of said base means through a predetermined angle theta .

6. An electrophotographic copying apparatus as claimed in claim 1, wherein said base means in the first position is disposed substantially in contact with the undersurface of a transport belt of said transport means for transporting the record paper.

7. An electrophotographic copying apparatus as claimed in claim 1, wherein said base means comprises a movable base and an auxiliary base coupled mechanically to said movable base by means of a coupling mechanism which enables both the bases to be folded together when said developing means moves.