US 3625605 A
Description (OCR text may contain errors)
United States Patent  Inventors Gunther Schnalli Herbert Engel, both of Munich; Karl Hartwig, Unterhaching, all of Germany [211 App]. No. 96,938  Filed Dec. 10, 1970  Patented Dec. 7, 1971  Assignee Agfa-Gevaert akliengesellschaft,
Leverkusen, Germany  ELECTROSTATIC COPYING APPARATUS 12 Claims, 3 Drawing Figs.
 US. Cl 355/15, 242/57  Int. Cl 603g 15/00  Field ofSearch 355/3, 15; 242/57  References Cited UNITED STATES PATENTS 3.190.198 6/1965 Eichorn.... 355/15 3,196,766 7/1965 Hansen .t 3,526,457 9/1970 Dimondetal.
Primary Egaminer-John M. Horan Assistant Examiner-Fred L. Braun Attorney-Michael S. Striker ABSTRACT: A carrier is mounted for travel in a first direction and carries a photoconductive layer. A cleaning device is provided including a nip roller which is proximal to the layer and about which an elongated cleaning tape is trained in frictional contact with the nip roller and with the layer. An advancing arrangement is' provided which incrementally advances the cleaning tape in a direction opposite to the direction of travel of the carrier and a biasing member acts upon the nip roller in a sense crossing the same to contact the photoconductive layer on the carrier when no portion of the cleaning tape intervenes. A detecting arrangement detects and becomes activated when the nip roller contacts the carrier and consequently begins to rotate in the aforementioned first direction, and a signal-generating arrangement generates a signal when the detecting device detects such rotation.
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Alla )1 1 ELECTROSTATIC COPYING APPARATUS BACKGROUND OF THE INVENTION The present invention relates generally to a copying apparatus, more particularly to an electrostatic copying apparatus.
Electrostatic copying apparatus is already well known. Therefore it is not believed to be necessary to enter into a detailed discussion of such apparatus. However, to provide some background for the considerations behind the present invention, it is pointed out that such apparatus usually utilizes a drum or a similar carrier which is provided on an exposed surface with a photoconductive layer. To produce the photocopy, pulverulent toner is used which develops the latent electrostatic image produced on the photoconductive layer. Because after the copying'process is completed, some of this pulverulent toner tends to adhere to the photoconductive layer and contaminate the surface thereof, this being undesirable in terms of quality of subsequent copies which can be obtained, it is necessary to remove such contaminants. For this purpose, cleaning devices have been produced which usually utilize a cleaning tape or web, generally consisting of paper or the like, which is pressed into slight frictional contact with the photoconductive layer and removes the surface contaminants therefrom by such frictional contact.
A difficulty with the prior art constructions resides in the fact that there is no way-other than by actual physical inspection-to determine whether the cleaning tape has broken. Also, such cleaning tapes are not endless but instead are final. Consequently, eventually the trailing end of the cleaning tape-which latter is advanced incrementally with reference to the carrier so that always new and clean portions of the cleaning tape come into contact with the photoconductive layer-will have been reached and will pass beyond the carrier so that the photoconductive layer is no longer being cleaned. Here, again, the prior art fails to provide any means for indicating such occurrence so that in this case, as in the case of a breakage of the cleaning tape, the copying apparatus usually continues to be utilized with the operator unaware that a malfunction has occurred, and with the quality of copies being produced constantly deteriorating.
Aside from the speed and convenience of electrostatic copying, one of the major advantages of this type of copying over other known types is the fact that electrostatic copying produces copies of excellent quality-always assuming that the copying apparatus operates properly. Clearly, therefore, it would defeat one of the major advantages of electrostatic copying if the aforementioned types of malfunction were to be allowed to remain undetected with a consequent deterioration in the quality of the copies produced.
SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to overcome these aforementioned disadvantages of the prior art.
More particularly, it is an object of the present invention to provide an improved electrostatic copying apparatus which is not possessed of these disadvantages.
A concomitant object of the invention is to provide such an improved apparatus in which means is provided affording an automatic indication of the aforementioned types of malfunction.
Still a further object of the invention is to provide such an apparatus in which its construction is very simple and inexpensive.
In pursuance of the above objects, and others which will become apparent hereafter, one feature of the invention resides in an electrostatic copying apparatus which, briefly stated, comprises a carrier mounted for travel in a first direction and carrying a photoconductive layer. Cleaning means is provided and includes a nip roller proximal to the layer, an elongated cleaning tape trained about the nip roller in frictional contact with the same and with the layer for frictional removal of surface contaminants from the latter, ad-
vancing means for incrementally advancing the cleaning tape in an opposite second direction, and biassing means for displacing the nip roller into contact with the layer in the absence of intervening increments of the cleaning tape. Detecting means is activatable upon detecting rotation of the nip roller in the first direction due to contact with the layer, and signalgenerating means generates a signal in response to activation of the detecting means.
When the cleaning tapeor rather an increment thereof is interposed between the nip roller and the photoconductive layer on the travelling carrier, then the nip roller will be either stationary or it will turn in a direction opposite to the direction of travel of the carrier as the cleaning tape is advanced increment by increment in this opposite direction. Under no circumstances can the nip roller rotate in the direction of travel of the carrier while an increment of the cleaning tape is located between it and the carrier. If, however, a break occurs in the cleaning tape, or if the trailing end of the cleaning tape moves past the carrier and nip roller, the latter can be displaced into engagement with the photoconductive layer on the travelling carrier by the biassing means provided, and by such contact it will now be rotated by the carrier in the same direction as the carrier rotates. This results, according to the present invention, in the immediate triggering of a signal, which may be used for producing an optical alarm signal, an acoustical alarm signal, both an optical and an acoustical alarm signal, or which may be used (as an alternative or an addition to the production of optical and/or acoustical alarm signals) to shut down the copying apparatus.
The construction according to the present invention can be particularly simple if the nip roller acts upon an actuating member which in turn acts upon a switch in an alarm circuit, with a friction coupling being interposed between the actuating member and the nip roller. It is for instance possible to journal on the shaft on which the nip roller rotates, a friction sleeve which is provided on its outer circumferential surface with an axially extending cam groove and which is surrounded by an outer sleeve mounted against rotation but having freedom of axial displacement relative to the friction sleeve and provided with a cam-follower projection which extends into the groove. The free end of the outer sleeve may be located proximal to the switch in the alarm circuit. When the nip roller then rotates in the same direction as the carrier, indicating the occurrence of one of the aforementioned malfunctions, the consequent rotation of the friction sleeve crosses via the cam groove displacement of the outer sleeve axially of the friction sleeve, urging the free end of the outer sleeve into engagement with the switch in the alarm circuit and activating the switch to thereby act upon the alarm circuit. In this embodiment, in which the direction in which the switch of the alarm circuit is activated coincides with the orientation of the axis about which the roller rotates, the construction can be particularly simple, in that the switch in the alarm circuit can be mounted stationarily on a stationary component of the copying apparatus. Furthermore, in such a construction the entire cleaning means can be constructed as a unit or module which can be inserted into and removed from the copying apparatus in toto, and this is made possible by the fact that with this embodiment, the switch stationarily mounted in the copying apparatus can be readily so located that it can cooperate with the outer sleeve when the cleaning means is inserted as a unit into the copying apparatus.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary somewhat diagrammatic vertical section through one embodiment of the present invention;
FIG. 2 is a section on an enlarged scale, through a detail of the embodimentof FIG. 1 and including the electrical circuitry; and
FIG. 3 is a section taken on line IIIIlI of FIG. 2
DESCRIPTION OF THE PREFERRED EMBODIMENTS from the various components relating to the present invention and necessary for an understanding thereof, only one additional component of the copying apparatus has been shown, namely a drum 2 which rotates in the direction of the arrow A and which constitutes in this embodiment the carrier for a photoconductive layer 211. It is pointed out that the nonillustrated parts and components of the electrostatic copying apparatus, as well as the drum 2 and the photoconductive layer 2a thereof, are all well known to those skilled in the art, and do not in themselves constitute the present invention. Their operation and their construction is not necessary for an understanding of the invention, and therefore it is thought that they can be readily omitted from the illustration and discussron.
The stationary portion 1 of the electrostatic copying apparatus is further provided with guides 3 and 4 along which a cleaning module or unit 5 can be inserted for connection with the copying apparatus, and along which it can be removed. The cleaning means 5 is identified as a unit or module to indicate that it is self-contained and can be inserted or connected and removed or disconnected in toto. A sidewall of the module 5 is provided with an upwardly open slot 5a into which the shaft 6 of a supply roller may be inserted about which supply roller 7 a cleaning tapewhich may in known manner consist of a feltlike paper ribbon or the like-is coiled in form of the coil 7. An additional slot 5b, spaced from the slot 5a, permits the introduction of the shaft 9 of a takeup roller 10 about which the cleaning tape 8 is also convoluted, it being understood that the cleaning tape 8 is to be incrementally withdrawn from the roller 7 and wound onto the roller 10.
An arresting lever 11 is provided which is journaled on a pivot 12 and upon which a tension spring 14 acts, one end of the spring being connected to the lever 11 and the other end to a pin 13 fast with the portion 1. It is the purpose of the lever 11 to retain the shaft 9 in the slot 5b. A gear 15 is mounted on the shaft 9 and, when the unit 5 is inserted into the apparatus along the guides 3 and 4, this gear 15 meshes with a driven gear 16 which is mounted on the stationary portion 1. An additional lever 18 is pivoted on a shaft 17 of the unit 5 and has acting upon it a tension spring 19 one end of which is connected with the lever 18, and the other end of which is connected to a nose or projection 5c of the unit 5. A lever 18 carries a shaft 20 for a nip roller 21, and FIG. 1 shows that the cleaning tape 8 is trained about the nip roller 21 so that an increment of the tape is confined between the nip roller 21 and the layer 2a, being in frictional contact with both when the unit is in operative position. A pair of guide rollers 22 and 23 are also provided in the unit 5, and the tape 8 is trained about these guide rollers also before it reaches the takeup roller 10. The tape 8 is maintained taut in known manner by providing a friction device on the drive of the takeup roller 10 and a braking device, which acts upon the supply roller 7 in a sense retarding the same. The takeup roller 10 is of course driven in rotation by cooperation of the gears 15 and 16, and thus withdraws the tape 8 from the roller 7. While a separate drive could conceivably be provided for the gear 16, it is advantageous to have the gear 16 driven from the main drive of the copying apparatus, and this can be accomplished in entirely known manner so that it is not illustrated herein. It is pointed out for the sake of completeness that because of the desired very slow incremental advancement of the tape 8, the
gear 16 must naturally also turn very slowly so that a stepdown gear must be interposed between it and the main drive of the copying apparatus. The purpose of rotating the gear 16 slowly is, of course, to gradually expose and bring into contact with the layer 2a, constantly new clean increments of the tape 8.
The unit or module 5 must be releasably connected with the copying apparatus, that is with the stationary portion 1 thereof. For this purpose, there is provided a shaft 24 on which an arm 25 is pivoted having a grip 25a located exteriorally of the unit 5 and accessible to an operator. The arm 25 is provided with a cam projection or pin 26 which abuts against a cam track 27 fast with the stationary portion 1 and having as illustrated a radius of curvature which is somewhat smaller than the radius of curvature of the arcuate path which the pin 26 describes when the arm 25 is moved between its full-line upper position and its broken-line lower position in FIG. 1 about the shaft 24. When the unit 5 is not connected with the stationary portion 1, the arm 25 will be in the brokenline lower position shown in FIG. 1. After the unit 5 is inserted to assume the position illustrated in FIG. 1, the arm 25 is raised to its upper full-line position and contact of the pin 26 with the cam track 27 causes the entire unit 5 to be displaced in the direction of the arrow B, that is towards the left in FIG. 1, thereby pressing the nip roller 21 against the action of the spring 19 against the layer 2a, with an increment of the tape 8 being located between them as shown. At the same time, the gears 15 and 16 move into mesh due to this movement in the direction of the arrow B and during the movement ofthe arm 25 from lower to upper position, the pin 26 moves past a deadcenter pointas seen with reference to the direction of the arrow B-so that when the arm 25 is in the full-line upper position, it will be retained in this upper position by the action of the spring 19. Naturally, when the arm 25 is subsequently moved from its full-line upper position to the broken-line lower position in FIG. 1, the pin 26 becomes disengaged from the cam track 27, pivoting the spring to move the nip roller 21 away from the layer 20 and to disengage the gears 15 and 16. Now, the entire cleaning device 5 can be withdrawn via the handle 28 as a module or as a unit from the copying apparatus. The rollers 7 and 10 are now freely accessible for replacing a defective or used-up cleaning tape 8 with a new one.
FIGS. 2 and 3 show how in this construction means is provided for achieving the objects of the present invention. It will be seen that there is journaled on the shaft 20 of the nip roller 21 a friction sleeve 29 which is provided in its circumferential surface with a cam track extending axially and being pitched axially of the sleeve 29; in the illustrated embodiment this cam track is in form of a helically curved axially extending groove 29a. An outer sleeve 30 surrounds the sleeve 29 and carries a follower projection 31here illustrated as a screw threaded through an aperture in the outer sleeve 30 so that it extends in part into the groove 29a. However, of course, the follower 31 could be constituted differently. FIG. 3 shows that a bifurcated member 32 is provided which is secured to the frame or housing of the unit 5 and which prevents the sleeve 30 from rotating with reference to or together with the sleeve 29. This can for instance be achieved by providing transverse recesses in the outer surface of the outer sleeve 30 and having portions of the arms of the bifurcated member 32 extend into them as illustrated in FIG. 3. However, other possibilities will offer themselves readily to those skilled in the art. What is essential, is that the sleeve 30 be prevented from rotation but that it be free to move axially with reference to the shaft 20 and the friction sleeve 29.
A free end portion 30a of the outer sleeve 30 is located proximal to a switch in the alarm circuit, the switch here being illustrated in form of two contacts 33 and 34. The switch is mounted stationarily in the copying apparatus, that is on the stationary portion 1 thereof, and is so located that the free end portion 300 will become juxtaposed with it in the manner illustrated in FIG. 2 when the module 5 is inserted into the copying apparatus to the position shown in FIG. 1. To prevent damage to the switch 33,34 when the module 5 is inserted into the copying apparatus, the outer circumferential surface of the free end portion of the outer sleeve 30 converges conically as indicated at 30b to the free end 30a.
Contact 34 of the alarm switch is conductively connected with the conductor 35 leading to a source of electrical energy. The other contact 33 is connected with the other net-conductor 40 leading to the source of electrical energy, but with conductors 36 and 37, a signal lamp 38, an acoustical signalling device 32 and a magnetic relay 39 being interposed.
As FIG. 2 also shows, the magnetic relay 39 acts upon an arm 41 which is pivoted at 41a and one portion of which normally abuts against a stationary abutment 43 provided, for instance, on the stationary portion 1. This abutment is maintained by the spring 42. A second portion 41b of the arm 41 is so located as to prevent movement of an abutment plate 44a of a starting switch 45 which is diagrammatically illustrated. The plate 44a is actuatable by a push button or the like 44 which acts upon the switch 45 and which is biassed by a spring 46 acting upon the push button 44 and upon the switch 45 in a sense tending to permanently move the latter to open circuitint'errupting position. Switch 45 is interposed in the main energy-supply circuit 47,48 of the apparatus, and we have diagrammatically illustrated that there may be further interposed in this main circuit a main drive motor 49, a projection lamp 50, and a transformer 51 for the Corona discharge device of the electrostatic copying apparatus.
It will be appreciated that as long as an increment of the cleaning tape 8 intervenes between the nip roller 21 and the layer 2a on the travelling carrier 2, the roller 21 is either stationary or-when as a result of rotation of the gears l6,15 the cleaning tape 8 is incrementally advanced from the roller 7 onto the roller 10, the roller 21 will be turned by the cleaning tape 8 in the direction of the arrow C (see FIG. 2)--that is the solid-line arrow associated with the roller 21 in FIG. 1by the cleaning tape and in opposition to the direction of rotation A of the carrier 2. This turning movement of the roller 21 is transmitted to the friction sleeve 29 which attempts to turn via the groove 29a and the projection 31, the sleeve 30 in a direction causing the sleeve 30 to move axially in the direction of the arrow C. This causes the switch 33,34 to be and remain open.
If, however, the cleaning tape 8 either breaks or else if the trailing end of the cleaning tape moves off the roller 7 and past the rollers 2 and 21, so that no increment of cleaning tape is in a position intervening between the rollers 2 and 21, then the latter roller 21 is enabled to move into direct contact with the layer 2a and, as a consequence, is now rotated by the carrier 2 in the direction of the arrow B. For convenience it may be said, therefore, that the roller 21 now rotates in the same direction--i.e., in the same sense-as the roller 2, namely as indicated by the broken-line arrowhead in roller 21 in FIG. 1. When this occurs, the friction sleeve 29 now acts upon the outer sleeve 30 via the portions 29a and 31 in a sense causing the outer sleeve 30 to advance axially in the direction of the arrow F of FIG. 2. In so doing, the free end portion 30a of the sleeve 30 presses against the contact 33 which is moved into engagement with the contact 34, thereby closing the switch and activating the signal lamp 38 to provide an optical signal and the acoustical signal device 52 to provide an acoustical signal. This acoustical signal device 52 may for instance be a buzzer, or the like. In addition, when the switch 33 and 34 is closed, the magnetic relay 39 is energized, to act upon the arm 41 in a sense displacing it in clockwise direction against the force of the spring 42, so that the arm or portion 41b releases the plate 44a. This permits the spring 46 to move the button 44 in upward direction in FIG. 2 and thereby to open the switch 45, interrupting the main-energy supply circuit of the copying apparatus and shutting the apparatus down.
It will be appreciated that it is fully within the concept of the present invention to omit either the lamp 38, the signalling device 52, or both. It is also possible to omit the arrangement which shuts down the main energy supply circuit and to rely only on one or both of the devices 38 and 52. Finally, it is pointed out that the switch 45 can of course be replaced with a relay serving the same purposes, and that either the switch 45 or a relay replacing it, need not shut down the entire machine but could simply shut a circuit of one or several individual electrically operated components of the machine.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.
While the invention has been illustrated and described as embodied in an electrostatic copying apparatus, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
What is claimed as new and desired to be protected by Letters Patent is set forth in the appended:
1. In an electrostatic copying apparatus, in combination, a carrier mounted for travel in a first direction and carrying a photoconductive layer; cleaning means, including a nip roller proximal to said layer, an elongated cleaning tape trained about said nip roller in frictional contact with the same and with said layer for frictional removal of surface contaminants from the latter, advancing means for incrementally advancing said cleaning tape in an opposite second direction, and biasing means for displacing said nip roller into contact with said layer in the absence of intervening increments of said cleaning tape; detecting means activatable upon detecting rotation of said nip roller in said first direction due to contact with said layer; and signal-generating means for generating a signal in response to activation of said detecting means.
2. In a copying apparatus as defined in claim 1, wherein said signal-generating means comprises an electrical circuit, a switch connected in said circuit and changing the status thereof in response to activation of said detecting means, and at least one electrically operable signalling device in said circuit and operable upon changing of the status of said circuit.
3. In a copying apparatus as defined in claim 2, wherein said switch and said circuit are of normally open status, and wherein said signalling device is operable upon closing of said switch and completion of said circuit.
4. In a copying apparatus as defined in claim 2, wherein said signalling device is an optical signalling device.
5. In a copying apparatus as defined in claim 2, wherein said signalling device is an acoustical signalling device.
6. In a copying apparatus as defined in claim 5; and further comprising an additional optical signalling device also in said circuit.
7. In a copying apparatus as defined in claim 2, said detecting means comprising a friction coupling connected with said nip roller, and an actuating element connected with said friction coupling and arranged for displacement by the same in a sense acting upon said switch in response to rotation of said nip roller in said first direction.
8. In a copying apparatus as defined in claim 7, wherein said cam track is a groove, and said cam follower is a projection on said outer sleeve.
9. In a copying apparatus as defined in claim 7, said nip roller comprising a shaft rotatable-with said nip roller, and said friction coupling being a friction sleeve journaled on said shaft and having an outer circumferential surface provided with an axially extending pitched cam track; and wherein said actuating element comprises a nonrotatable outer sleeve having a free end adjacent said switch and surrounding said friction sleeve with freedom of axial movement relative thereto, and a cam follower engaging said cam track so that, in response to requisite rotation of said friction sleeve, said outer sleeve is displaced axially under the influence of the cooperating cam track and follower with concomitant engagement of said free end with said switch and operation of the latter by the former.
10. ln a copying apparatus as defined in claim 9, said outer sleeve having a leading end portion provided with said free end and with a circumferential surface which converges in direction towards said free end.
11. In a copying apparatus as defined in claim 1; further comprising at least one electrically operated component, and a circuit for supplying electric energy to said component; and