US3095194A

US3095194A - Sheet guiding apparatus

Info

Publication number: US3095194A
Application number: US176530A
Authority: US
Inventors: Gordon P Taillie
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1962-03-01
Filing date: 1962-03-01
Publication date: 1963-06-25
Anticipated expiration: 1980-06-25
Also published as: GB1026214A

Description

June 25, 1963 G. P. TAlLLlE 3,095,194.

SHEET GUIDING APPARATUS -Filed March 1, 1962 5 Sheets-Sheet 1 FIG. 1

INVENTOR. GORDON P. TAILLIE A T TORNEY June 25, 1963 G. P. TAILLIE 3,095,194

SHEET GUIDING APPARATUS Filed March 1, 1962 3 Sheets-Sheet 2 INVENTOR. GORDON P. TAILLIE A T TORNE V June 25, 1963 e. P. TAILLIE 3,095,194

SHEET GUIDING APPARATUS I Filed March 1, 1962 3 Sheets-Sheet 3 INVENTOR GORDON P. TAILLIE yaw/Jud A T TOR/VEV i tats atnt 3,t35,194 SHEET GUEDMG AETARATUS Gordon P. Taiilie, Rochester, N321, assignor to Xerox gorgoration, Rochester, NE! a corporation of New Filed Mar. 1, 1962, Ser. No. 176,530 3 Claims. (Cl. 271-7?) This invention relates to paper guide rolls for use in the sheet conveyor mechanism of a Xerographic repro- 1O material to form a powder image of the copy on thi drum. The powder image is then transferred to a sheet of support or transfer material, usually paper.

Thus, in the field of Xerography, an image is developed on a Xerographic plate, the image being secured to the xerographic plate by an electrostatic force only, and within the influence of this electrostatic force the image can very easily be smeared or smudged. In the transfer process, a sheet of support material is brought into contact with the image on the Xerographic plate and the image is then transferred and held electrostatically on the support material. Unlike many types of mechanical forces, the electrostatic forces binding the image body either to the Xerographic plate or later to the support material are comparatively weak in preventing lateral motion of the image body away from the xerographic plate surface or from the surface of the material.

When transfer is to be effected from a moving xerographic plate onto a support material in an automatic xerographic reproducing machine, the support surface must be moved into contact with the xerographic plate for synchronous movement therewith during the transfer process to permit proper registered image transfer from the plate to the support material. If relative movement between the plate and support material is permitted along the areas of transfer contact, smearing or smudging of the images will occur.

One type of conveyor mechanism employed in Xerographic reproducing apparatus for conveying sheet support material from a receiving station into transfer contact with a xerographic plate and then to a delivery station is disclosed in copending application Serial No. 46,463, filed August 1, 1960, in the name of Robert A. Hunt and Gordon P. Taillie. Such an arrangement includes a pair of endless chains, or equivalents, sprockets,

or equivalents, for supporting the chains, and at least one sheet gripper connected to the chains at right angles to their path of movement, for movement through a closed circuit from a receiving station to a delivery station. Heretofore, this type of conveyor mechanism has proved satisfactory for use in Xerographic apparatus, provided the conveyor mechanism is of such a length as to permit a substantially long straight run of sheet material to and from the xerographic plate to ensure a uniform rate of travel of the sheet material.

It is apparent then that the side of the conveyor mechanism of this type governs the size of the Xerographic apparatus; that is, the bigger the sheet of support material conveyed by the conveyor, the longer the length of the conveyor, and therefore, the greater the outside physical dimension of the entire Xerographic apparatus. Furthermore, the greater the length of travel required for a sheet of transfer material, the greater the period of time required for making a Xerographic reproduction on the support material before it is fed from the machine. It is, therefore, an object of this invention to improve paper guide means for use in endless belt type sheet conveyors to permit the overall length of a sheet conveyor to be reduced while still permitting uniform travel of a sheet material conveyed thereby.

Another object of this invention is to improve paper guide rolls to guide sheet material around a turn in a conveyor mechanism at a uniform rate of speed.

It is a further object of this invention to improve paper guide rolls so that a malfunction of the paper guide roll will not interfere with the operation of the sheet conveyor mechanism.

It is a further object of this invention to improve paper guide rolls so that they are economical to produce, reliable in operation, and will fail safe if malfunction occurs.

These and other objects of the invention are attained by means of a guide plate that is freely rotatable to permit passage of a sheet gripper mechanism and biasing means on the guide plate to return the plate to a position supporting the sheet of material received by the gripper mechanism. Failure of the biasing means will leave the guide plate in a position that will not interfere with the path of travel of the next succeeding gripper mechanism. Thus, this arrangement provides a device that, even under failure of one of the parts, will not interfere with the operation of the machine.

The invention is disclosed in the appended drawings, in which:

FIG. 1 is a schematic illustration of a type of Xerographic reproducing machine in which the present invention may advantageously be employed;

FIG. 2 is a perspective view of a sheet conveyor system embodying the present invention;

FIG. 3 is a sectional view of the paper guide roll taken along line 33 of FIG. 2;

FIG. 4 is a sectional view of the paper guide roll of PEG. 3, shown in a deflected position; and,

FIGS. 5 and 6 are sectional views similar to FIGS. 3 and 4, showing an alternate embodiment of the invention.

Referring now to FIG. 1, there is shown a continuous Xerographic reproduction machine of the type disclosed in the above-mentioned copending application in which a paper guide roll may advantageously be employed. The Xerographic apparatus comprises a Xerographic plate 10, including a photoconductive layer of light receiving surface on a conductive backing and formed in the shape of a drum, which is positioned on a shaft *11 journaled in a frame (not shown) to rotate in the direction indicated by the arrow to cause the drum surface sequentially to pass a plurality of Xerographic processing stations.

For the purpose of the present disclosure, several xerographic processing stations in the path of movement on the surface may be described functionally, as follows:

A charging station A, at which a uniform electrostatic charge is deposited on the photoconductive layer of the Xerographic drum;

An exposure station B, at which a light or radiation pattern of copy to be reproduced is projected onto the drum surface to dissipate the drum charge on the exposed areas thereof, and thereby form a latent electrostatic image on the copy to be reproduced;

A developing station C, at which a xerographic developing material including toner particles having an electro static charge opposite to that of the electrostatic latent image are cascaded over the drum surface, whereby the toner particles adhere to the electrostatic image to form a xerograp-hic powder image in the configuration of the copy to be reproduced;

A transfer station D, at which the xerographic powder image is electrostatically transferred from the drum surface to a transfer material or support surface; and,

A drum cleaning and discharge station E, at which the drum surface is brushed to remove residual toner particles remaining on the drum after image transfer, and at which the drum surface is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge thereon.

At charging station A, a corona discharge array 12 of one or more discharge electrodes, that extend transversely across the drum surface and are energized from a high potential source, are substantially enclosed within a shielding member. The charging apparatus may be of the type disclosed in Walkup Patent 2,777,957.

Next subsequent thereto in the path of motion of the xerographic drum is exposure station B, which contains an optical scanning or projection mechanism generally designated 13 and a light shield member 14. The optical scanning mechanism consists of a lamp LMP1 which provides a uniform lighting source of projecting a li ht image of a film 13, or other copy to be reproduced. Projector 14 contains a series of optical lenses which project the image onto an object mirror 16 in light shield 14. Object mirror 16 reflects the image through aperture 17 onto the surface of the rotating xerographic drum. In the commercial form of this machine, a film holder (not shown) is inserted between lamp LMPl and projector 15, and is supported by a movable carriage on the projector. The film holder is arranged for movement in a path to traverse the optical path of the lens whereby the subject image of the film is scanned in timed relation to the movement of the light receiving surface of the xerogr'aphic drum and a [light corresponding to the subject image is transferred to the surface of the xerographic drum.

Adjacent to the exposure station is a developing station in which there is positioned a housing 18 for containing a suitable two component developing apparatus. In this arrangement, a bucket-type conveyor 20 having a suitable driving means (not shown) is used to carry developing material 21 to the upper part of the housing where it is cascaded down over a chute 22 onto the xerographic drum.

As the developing material is cascaded over the xerographic drum, toner particles are pulled away from the carrier component of the developing material and deposited on the drum to form powder images. The carrier components pass off the drum into the lower portion of housing 18, for recycling. As powder images are formed, additional toner material may be supplied to the developing material in proportion to the amount of toner deposited on the drum surface. For thi purpose, there is provided a container 23 for toner '24 to be added to the developing material 'at a rate determined by a control gate 25 After passing developing station C, the xerographic drum rotates past image transfer station D. At the transfer station, a sheet feeding mechanism is adapted to feed sheets of transfer material, usually paper, successively to the xerographic drumin registration with the formed xerographic powder image on the said drum.

In the embodiment shown, the sheet feeding mechanism includes a chain conveyor 26 carrying one or more paper grippers 27 in a circuit between sheet feeding station 79 and a sheet delivery station 71. Means are provided to activate the grippers to cause the grippers to take hold of the front edge of a sheet of support material 28 inserted into the machine at the station '74 and to hold the sheet while traveling to the delivery station and there to release the sheet for removal from the machine. In the embodiment shown, a sheet of transfer material is fed manually by an operator to paper gripper 27 and is forwarded by the paper gripper into contact with a xerographic drum at image transfer station D.

The transfer of a xerographic powder image from the drum surface to the support material is eifected by i means of a corona transfer device 29 located at or immediately after the point of cont-act of the support material and the xerographic drum. The corona transfer device is substantially similar to the corona discharge device 12 that is employed at charging station A, in that it includes an array of one or more corona discharge electrodes that are energized from a suitable high potential source and extend transversely across the drum surface and are substantially enclosed within a shielding member. In operation, the electrostatic field created by the corona discharge device is effective to cause the transfer material to electrostatically adhere to the drum surface, whereby the transfer material moves synchronously with the drum surface in contact therewith. The electrostatic field i also effective to attract the toner particles comprising the powder image from the drum surface and cause them to adhere electrostatically to the surface of the transfer mate'rial.

As the paper gripper is advanced by the chain conveyor it strips the sheet of transfer material from the drum and transports it to a fixing device, such as a heat fuser 30, where the xerognaphic powder images previously transferred to the support surface are permanently fixed thereto. Suitable support rods 31 are provided to guide the trailing edge of the sheet of support material in proper relation to the heat fuser. The heat fuser 34} contains electrical heating elements R1, R2, and R3, which are connected to a suitable source of power (not shown).

After fusing, the finished copy is discharged from the apparatus at a sheet delivery station 71. To accomplish this, there is provided a pair of

delivery rollers

32 and 33 which receive the sheet from a paper gripper and deliver it to a collecting tray 34;

After the image is transferred from the xerographic drum to the support surface, the xerographic drum rotates past the cleaning station E to remove any residual charge and developing material that may remain on the xerographic drum. The corona precleaning device 35, similar to corona charging device 12, is positioned to impose an electrostatic charge of suitable polarity on the drum and powder adherent thereto, to aid in effecting removal of the powder from the drum surface. A rotatable brush 35 is positioned to eifect removal of this residual powder from the drum and a source of light [such as LMPZ floods the drum surface with light to cause dissipation of any residual electric charge remaining on the drum. For collecting the powder particles removed by the brush there is provided a dust hood 37.

For removing dust particles from the brush and dust hood, an exhaust duct 38 is arranged to cover a slot that extends transversely across the hood 37 and is connected to a filter bag 39 in a filter box 49. Motor driven fan units 41 connected to the filter box, produce a flow of air through the filter box drawing air through the area surrounding the xerogr aphic drum and the dust hood, the air entrains powder particles removed from the drum by the brush as the air flows through the dust hood. Powder particles are separated from the air as it flows through the filter bag so that only clean air reaches the motor fan unit.

Any residual electric charge remaining on the Xerographic drum is dissipated by light from fluorescentlamp LMPZ, mounted in lamp housing 42. A suitable power source is provided for energizing the fluorescent lamp.

Operation of the paper conveyor is effected by actuation of a limit switch LS1, upon the insertion of a sheet of transfer material into a paper gripper, and the operation of the paper conveyor is terminated, after a sheet of transfer material has been conveyed from the front of the machine to the delivery rollers, by limit switch LS2 which is actuated by one of a pairof actuators 42 on the paper conveyor. As the paper conveyor is operated, the actuator 42 contacts limit switches LS3 and LS4 which are used to effect the operation of the projection apparatus.

Referring now to FIG. 2, the conveyor chains 26 ar mounted on pairs of

sprockets

43, 44, 45, 46 and 47, which are rotatably mounted on shafts between side frame members 48 and 49. Each gripper bar 27 is mounted on chains 26 and is carried in a continuous path around each of the sprockets back to the original position as shown in FIG. 2. Mounted between the pair of sprockets 46 on shaft 50 which is fastened at its ends in the plates 48 and 49, is a paper guide roll 51 which constitutes the essence of this inventtion. As shown in FIGS. 2 and 3, paper guide roll 51 consists of a guide plate 55 mounted on a pair of spacers 52 which are rigidly secured to shaft 56 by means of set screws 54. Paper guide roll 51 is pivotally mounted on spacers 52 by means of pin 53.

Guide plate 55 is formed with a circular portion covering an arc of approximately 90 and a fiat portion extending from :the circular portion in the direction of the front of the machine. On the end of the flat portion is a counterweight 56 attached by means of rivets 57. Guide plate 55 is freely rotatable on pin 53 and is normally pivoted, by the counterweight 56, which is secured to the underside of the flat portion of guide plate 55, so that the fiat portion extends downward toward the front of the machine. That is, guide plate 55 is in such a position that the flat portion is at an angle to the path of travel of the gripper bar 27, and the circular portion of guide plate 55 is in interference relationship with the gripper bar 27 as it travels in its normal path around sprockets 46.

The freedom of movement of the guide plate 55 on pin 53 permits the gripper bar 27 to deflect the guide plate from its normally biased position and allows gripper bar 27 to pass around sprockets 46, at which point counterweight 56 causes the guide plate 55 to return to its biased position as shown in FIG. 3. The guide plate forms an elongated single guide for a sheet of transfer material, the radius of the peripheral surface of the guide being equal to the pitch radius of the sprockets 46 for the purpose as to be described hereinafter.

While the sheet of transfer material is being pulled at one end by the paper gripper and held back at its other end by the tacking force onto the xerographic drum, the paper guide roll will remain rotated substantially in the position shown in FIG. 4, until the paper gripper 27 passes over sprockets 46, at which point the paper guide roll returns to its normally biased position, as shown in FIG. 3, and provides a guide path for the sheet of transfer material. If the guide roll were not present, the distance between the forward edge of the sheet of material and the contact with the xerographic drum would be shortened as the gripper bar passes around sprockets 46. However, the guide roll provides a surface for the material to pass over and still maintain .the same tension on the support surface by the gripper bar as if the gripper bar were traveling in a straight path away from the xerographic drum.

FIGS. 5 and 6 show another embodiment of the invention. The paper guide roll 58 is formed in the same manner as that described in the preferred embodiment, that is, it includes a segment of a circle and a flat portion extending toward the front of the machine. Spacer plates 59, secured to shaft 50 by means of set screws 60, contain a pin 61 to which guide plate 58 is rotatably attached. A tension spring 62 is secured to spacer 59 and to the end of the flat portion of guide plate 58. Spring 62 causes the guide plate 58 to be held in a normally biased position such that the flat portion is at an angle to the path of travel of gripper bar 27.

In operation, in the same manner as previously described, the gripper bar 27 comes in contact with guide plate 58 and deflects the guide plate into the position shown in FIG. 6. Guide plate 58 is deflected around pin 61 permitting f-ree passage of gripper bar 27 and extending tension spring 62. After the gripper bar passes around sprocket 46, guide plate 58 is free to return to its nor- 6 mally biased position by means of tension spring 62 and provides a surface over which the support material may pass without shortening the distance between the gripper bar and the point of contact with the xerographic drum.

Spacers 59 contain limiting

pins

72 and 63. Limiting pin 72 regulates the normally biased position of guide plate 58 and limiting pin 63 regulates the position of guide plate 58 in the deflected position. Limiting pin 63 is a fail-safe device such that, should tension spring 62 fail, the normal weight of guide plate 63 would cause the plate to come to rest on pin 63. Thus, the guide plate would remain in a position permitting the passage of paper gripper 27. Without pin 63, should the tension spring 62 fail, the guide plate under its normal weight would swing in such a position that the gripper bar would come in contact with the underside of the flat portion of the plate 53 and would jam, causing damage to the machine and possibly stalling the movement of the gripper bar. Continuous movement of the gripper bar is necessary since at this point, a portion of the transfer material is passing under the heat fuser 30. Any restriction in its normal movement would delay the movement of the transfer material and cause excessive heating and possible fire.

In the normal operation of the machine, a microfilm card is placed in projection 15, an image of which is projected by means of LMPl through projector 15, mirror 16 onto xerographic drum 10. A sheet of transfer material or support surface, is inserted into the machine at feeding station 70 and activates limiting switch LS1, so that gripper bar 27 will grip the sheet of transfer material and carry it into contact with the xerographic drum at image transfer station D. The electrostatic image on the drum is developed at developing station C, and transferred to the sheet of transfer material at station D. Gripper bar 27 then carries the sheet of transfer material in spaced relation to the heat fuser 30. After passing under the heat fuser 30, the gripper bar comes into interference contact with guide plate 58 and causes the guide plate to rotate about pin 53. The sheet of transfer material passes between

rollers

32 and 33 at which point the gripper bar releases the sheet of transfer material. Guide plate 55 returns to its normally biased position where it serves as a guide surface for the sheet of transfer material. Roller 33 and idler roller 32 move the transfer material and deposit it in tray 34.

Although the invention, in each of its forms is described as used with a conveyor system of an automatic xerographic reproduction machine, it will be apparent to those skilled in this or related arts that it may readily be applied to any system in which it is required to handle sheets of material by means of a conveyor system. Therefore, since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the specification and drawings be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a sheet conveyor mechanism including a pair of endless chains mounted on parallel pairs of sprockets and a sheet gripper mechanism mounted on said endless chains,

a sheet guide roll means consisting of an arcuate guide plate having a flat segment in interference relation with the path of travel of the gripper mechanism,

said guide plate being pivotably mounted on one or more collars rigidly secured to a shaft between a pair of said parallel sprockets,

and a counterweight positioned on the underneath side of said fiat segment to position the arcuate section coincidental with the pitch circle of said sprockets.

2. In a sheet conveyor system including a sheet gripper mechanism mounted on a pair of endless chains that move in a path around a series of parallel sprockets,

a sheet guide roll consisting of a plurality of collars rigidly mounted on a shaft between a pair of said sprockets, a pin mounted on each of said collars, an arcuate guide plate pivotably mounted on said pins, said guide plate having a curved peripheral section equal to the pitch circle of said sprockets and a flat segment attached to said curved section, and spring means connected to said flat section and to said collars to normally bias said guide plate in a position wherein said curved section is coincidental with the pitch circle of said sprockets and said flat section is in interference relation with the path of 15 2,392,391

travel with said gripper mechanism.

3. The apparatus of claim 2, wherein said collars contain two positioning pins, said pins extending outwardly in interference relationship with the pivotable movement of said guide plate, and said pins positioned on said collar to limit the maximum movement of said guide plate, whereby, upon failure of said spring means, the movement of said guide plate will be limited by, said positioning pins and will not interfere with the movement of said gripper mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 2,198,385 Harrold Apr. 23, 1940 Kaddleland Jan. 8, 1946 2,775,934 Luehrs et a1. Ian. 1, 1957

Claims

1. IN A SHEET CONVEYOR MECHANISM INCLUDING A PAIR OF ENDLESS CHAINS MOUNTED ON PARALLEL PAIRS OF SPROCKETS AND A SHEET GRIPPER MECHANISM MOUNTED ON SAID ENDLESS CHAINS, A SHEET GUIDE ROLL MEANS CONSISTING OF AN ARCUATE GUIDE PLATE HAVING A FLAT SEGMENT IN INTERFERENCE RELATION WITH THE PATH OF TRAVEL OF THE GRIPPER MECHANISM, SAID GUIDE PLATE BEING PIVOTABLY MOUNTED ON ONE OR MORE COLLARS RIGIDLY SECURED TO A SHAFT BETWEEN A PAIR OF SAID PARALLEL SPROCKETS, AND A COUNTERWEIGHT POSITIONED ON THE UNDERNEATH SIDE OF SAID FLAT SEGMENT TO POSITION THE ARCUATE SECTION COINCIDENTAL WITH THE PITCH CIRCLE OF SAID SPROCKETS.