US3639051A - Electrostatic copier - Google Patents

Abstract

A dry developer system for applying toner particles to copy material in which a sheet of copy material carrying a latent electrostatic image is conveyed face down past a serrated roller provided with magnetic means for holding particles of magnetic material carrying toner so oriented as to brush the surface of the copy material in a direction opposite to the direction of the advance of the material. The developer system further comprises a clapper for holding the copy material into contact with the particles on the roller.

Description

Unite States atent [151 3,639,05 1

(Iharlap et al. 1 Feb. 1, 1972 [54] ELECTROSTATIC COPIER 3,003,462 10/1961 Streich, Sr. ..l18/637 [72] lnventors: E. Paul Charlap, Scarsdale, N.Y.; Fritz 3088386 5/1963 Sugarman 3,145,122 8/1964 Stre1ch, Sr. mmmga'fem Gesmjfleuchelhem 3,164,074 1/1965 Francis et 31.. Flsche" G'essen Wlesck, 0f 3,176,652 4/1965 Mott et al ..118/637 ux Germany [73] Assignee: Savin Business Machines Corporation, FOREIGN PATENTS OR APPuCATlONS New York, NY. 1,865,366 10/1963 Germany ..117/17.5

[22] Filed: 1969 Primary Examiner-Samuel S. Matthews [21] AppL No.1 823,225 Assistant Examiner-Robert P. Greiner Attorney-Shenier & OConnor Related US. Application Data [62] Division of Ser. No. 379,232, June 30, 1964, Pat. No. [57] ABSTRACT 3,490,841 A dry developer system for applying toner particles to copy material in which a sheet of copy material carrying a latent [52] U.S.Cl ..355/3,117/ 17.5 electrosiatic image is conveyed face down P 3 Serrated [51] int. Cl. ..G03g 15/08 roller Provided with magnetic means for holding Particles of [58 Field ofSearch.. ..117/17.5;355/3; 118/637 magnetic material carrying toner so Oriented as to brush the surface of the copy material in a direction opposite to the 56] References Cited direction of the advance of the material. The developer system further comprises a clapper for holding the copy material into UNITED STATES PATENTS contact with the particles on the roller.

2,786,440 3/1957 Giaimo, Jr ..118/637 UX 4 Claims, 7 Drawing Figures PATENTEUFEB H972 $639,051 sum 3 or 3 f /04 a o O l O INVENTORS .524 5, PAUL, cHARl-fl FRITZ gnu/v! cAm'feN L OTHAR FISCHER BYMXM ATTORNEYS ELECTROSTATIC COPIER This application is a division of our c-opending application Ser. No. 379,232 filed June 30, 1964, now US. Pat. No. 3,490,843.

BACKGROUND OF THE INVENTION heretofore been proposed for using dry developers. Systems wherein developer is sprinkled and the like do not ensure uniform distribution of toner over the face of the sheet to be developed.

We have invented a dry developer system for electrostatic copiers which overcomes the defects of developer systems of the prior art. Our system enables us to avoid the use of liquids in our copying machine. It ensures uniform distribution of particles over the face of the sheet being developed.

SUMMARY OF THE INVENTION One object of our invention is to provide a dry developer system for electrostatic copying machines.

Another object of our invention is to provide a developer system which does not require the use of liquid developers.

A further object of our invention is to provide a dry developer system which ensures even distribution of toner across the face of the sheet being developed.

Other and further objects of our invention will appear from the following description.

In general our invention contemplates the provision of a dry developer system for developing a latent electrostatic image onthe face of a copying sheet in which a clapper moves the sheet into contact with magnetic particles with toner carrying magnetic particles magnetically held in serrations in the surface of a roller which is driven in a direction counter to the movement of the copy sheet.

BRIEF DESCRIPTION OF THE DRAWINGS dicate like parts in the various views:

FIG. 1 is a fragmentary sectional view of aportion of our dry developer system.

FIG. 2 is a side elevation of our dry developer system.

FIG. 3 is an elevational view of our dry developer system with parts broken away and with other parts shown in section.

FIG. 4 is an end elevation of our dry developer system.

FIG. 5 is a top plan view of our dry developer system shown in FIG. 3 with parts broken away and with other parts shown in section.

FIG. 6 is an end elevation of our dry developer system.

FIG. 7 is a fragmentary plan view of our dry developer system.

We have provided a dry developer system comprising a tray 426 supported between developer assembly sideplates 428 and 430 carried by the main sideplates 22 and 24 of the frame.

We dispose a developer roller 432 having a serrated surface 434 for rotary movement in the tray 426. A bushing 436 supported in theplate 428 rotatably carries the shaft 104. We secure an end plate 440 of the toner roller 432 to shaft 104 for rotation therewith so that when the shaft 104 is driven in a manner described in ourcopending application supra, the toner roller 432 is driven. A stationary shaft 444 mounted in the sideplate 430 carries a bushing446 which rotatably supports the other end plate 448 of the roller 432.

One end of a magnet support bracket 450 carries a lug 452 I which we secure to the shaft 444 by any suitable means, such as by a screw 454. A bushing 456 on a portion of the shaft 104 extending inwardly beyond the plate 440 receives a boss 458 on the bracket 450. We dispose a plurality of magnets 460 along the length of the bracket 450. The bracket 450 carries a pair of spaced shield mounted brackets 462 to which we secure a shield 464 by any suitable means, such as screws 466.

From the structure just described, it will be apparent that the magnet and shield assembly is stationary while the developer roller 432 will rotate in response to rotation of the shaft 104.

As will be described in detail hereinafter, in the dry developer form of our machine, tray 426 normally holds a supply of a mixture of a magnetic material such, for example, as iron filings and a toner which may, for example, be a suitably colored resin adapted to be attracted to the charged areas on the copy material and thereafter fluxed to the copy material by the application of heat. In order to ensure that the mixture of the carrier particles and the toner particles is as uniform as is possible, we rotatably mount a pair of agitators 468 and 470 in the sideplates 428 and 430. These agitators are constantly driven to mix the toner particles with the particles of carrier material. We mount a toner supply housing 472 outboard of the sideplate 430 by any suitable means such, for example, as by a screw 474 secured to an extension 476 of the tray 426 into which both of the agitators 468 and 470 extend. Housing 472 carries a shaft 478 which supports an agitator 480 which, in response to rotation of shaft 478, stirs the toner particles within the container 472. We provide the toner adder assembly with a gate 482 normally urged closed by a spring 484 secured to'the sideplate 430. When in a manner to be described hereinafter, the supply of toner in the dry developer has become depleted, a signal is fed to a solenoid 486 to energize the solenoid to draw its armature 488 to the right as viewed in FIG. 4 to permit toner to drop through the bottom of housing 472 into the extension 476 from which it is moved by the agitators 468 and 470 into the tray 426 adjacent the toner roller 432.

A pair of pivot shafts 490 and 492 pivotally support a clapper 494 on the sideplates 428 and 430. We dispose a paper guide 496 below the clapper 494 ahead of the toner roller 432 in the direction of movement of the copy paper. The armature 498 of a solenoid 500 carries a screw 502 which extends upwardly through a bracket 504. A spring 506 on the screw bears between the bracket 504 and the head of the screw normally to urge the armature 498 to its uppermost limit position as shown in FIG. 4. In this position of the screw, a lateral extension 508 on an arm 510 carried by the clapper 494 rests on the head of the screw 502. When a sheet of copy material is fed into the space between the guide 496 and clapper 494, solenoid 500 is energized to move the screw 502 downwardly to permit clapper 494 to fall under the influence of gravity toward the paper being fed to ensure contact between the paper and the material carried by the roller 432. An adjustable screw 512 on arm 510 is adapted to engage a strike plate 514 to limit the downward movement of the clapper.

As has been explained hereinabove, the drive mechanism of our machine comprises the chain 254 which drives a sprocket wheel 274 on shaft 104. Shaft 104 carries a toner roller drive gear 516 which drives an idler gear 518 carried by sidewall 428. Gear 518 drives a gear 520 carried by the toner adder drive shaft-522 which is rotatably supported in the plates 428 and 430. Gear 520 engages respective gears 524 and 526 to rotate the agitators 468 and 470.

The end of shaft 522 outboard of plate 430 carries a gear 528 which. meshes with the gear 530 carried by the shaft 478 of the toner supply. Thus, as the gear 516 rotates, agitator 480 is driven to stir the toner particles within the housing 472. It is to be noted that we provide a window 532 in the underside of .thetray 426 to permit the dry developer to be monitored to We provide our assembly with an iron rod 534 disposed just over the adder as it moves onto the toner roller. This rod is in the fringe of the magnetic field produced by the toner magnets. lt collects any stray particles to prevent them from falling onto the copy material as it moves through the developer system.

The overall operation of one type of machine with which our dry developer system is adapted to be used is set forth in detail in our copending application referred to hereinabove. As is pointed out therein as a sheet of copy paper enters into the space between clapper 494 and a roll disposed thereunder solenoid winding 500 is energized after a short delay to permit the clapper to fall toward the paper being fed to ensure contact between the paper and the developer material on the roll 432. Moreover, the developer concentration sensing system operates on light from source 758 reflected by the developer to the photocell 762. 'As the paper contacts the material in the serrations 434 of roll 432 toner is evenly brushed across the image to cause toner particles to adhere to the charge bearing portions of the image. The rod 534 which is in the fringe of the magnetic field produced by the toner magnets 460 collects in stray particles to prevent them from falling onto the copy material as it moves through the developer system.

It will be seen that we have accomplished the objects of our invention. We have provided a dry developer system for an electrostatic copying machine which overcomes the defects of dry developer systems of the prior art. It produces clean copies. lt ensures that toner particles are evenly distributed across the face of the image bearing copy material. It avoids the necessity for using liquid developers.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of our claims. lt is further obvious that various changes may be made in details within the scope of our claims without departing from the spirit of our invention. It is, therefore, to be understood that our invention is not to be limited to the specific details shown and described.

Having thus described our invention, what we claim is:

1. An electrostatic copier developing system for applying toner particles to copy material carrying a latent electrostatic image including in combination a tray for holding a supply of a mixture of carrier particles of magnetic material and toner particles, A roller, means mounting said roller for rotary movement in said tray, means disposed adjacent said roller for producing a magnetic flux passing through said roller over a predetermined segment of its axis of rotation to cause said flux to adhere said mixture to said roller over said segment, a clapper, means mounting said clapper adjacent said roller for swinging movement from a position relatively remote from the surface of said roller to a position relatively close to the surface of said roller, means for feeding a length of copy material into the space between said clapper and said roller and means responsive to said feeding means for moving said clapper from its remote position to its close position to bring said copy material into contact with said mixture carried by said roller,

2. An electrostatic copier developing system for applying toner particles to copy material carrying a latent electrostatic image including in combination a tray for holding a supply of a mixture of carrier particles of magnetic material and toner particles, a roller, means mounting said roller for rotary movement in said tray, magnetic field producing means disposed adjacent said roller for producing a flux passing through said roller over a predetermined segment of its axis of rotation to cause said flux to adhere said mixture to said roller over said segment, means for bringing copy material carrying on image into contact with said mixture on said roller and a collector of magnetic material mounted in the fringe of said field for collecting stray particles of said mixture.

3. An electrostatic copier developing system for applying toner particles at a developing location to copy material carrying a latent electrostatic image including in combination a tray for holding a supply of a mixture of carrier particles of magnetic material and toner articles, a hollow roller, means mounting said roller ll'l sai tray ad acent said location for rotary movement around an axis, mean comprising an axially elongated magnet of generally regular configuration mounted within said roller in stationary relationship thereto with one pole thereof adjacent to said location and with the other pole thereof adjacent to said axis for producing a magnetic flux passing through said roller, a shield of magnetic material carried by said magnet mounting means and extending over a predetermined minor segment of the axis of rotation of said roller, said segment trailing said one pole with reference to the direction of movement of said roller to cause said flux to adhere said mixture to said roller over the remainder of the surface of said roller and means for bringing copy material carrying an image into contact with said mixture on said roller at said location.

4. An electrostatic copier developing system for applying toner particles to copy material carrying a latent electrostatic image, including in combination a tray for holding a supply of a mixture of carrier particles of magnetic material and toner particles, a roller, means mounting said roller for rotary movement in said tray, means for rotating said roller in a given direction around an axis, said roller having axially extending serrations projecting from its surface, said serrations being forwardly inclined in the direction of rotation of said roller, means disposed adjacent said roller for producing a magnetic flux passing through said roller over a predetermined segment of its axis of rotation to cause said flux to adhere said mixture to said roller over said segment with at least some of said magnetic particles extending in the direction of inclination of said serrations and means for bringing copy material into contact with said mixture on said roller in a direction against the direction of movement of the roller surface to cause said toner to be brushed onto said material.

Claims (4)

1. An electrostatic copier developing system for applying toner particles to copy material carrying a latent electrostatic image including in combination a tray for holding a supply of a mixture of carrier particles of magnetic material and toner particleS, A roller, means mounting said roller for rotary movement in said tray, means disposed adjacent said roller for producing a magnetic flux passing through said roller over a predetermined segment of its axis of rotation to cause said flux to adhere said mixture to said roller over said segment, a clapper, means mounting said clapper adjacent said roller for swinging movement from a position relatively remote from the surface of said roller to a position relatively close to the surface of said roller, means for feeding a length of copy material into the space between said clapper and said roller and means responsive to said feeding means for moving said clapper from its remote position to its close position to bring said copy material into contact with said mixture carried by said roller,

2. An electrostatic copier developing system for applying toner particles to copy material carrying a latent electrostatic image including in combination a tray for holding a supply of a mixture of carrier particles of magnetic material and toner particles, a roller, means mounting said roller for rotary movement in said tray, magnetic field producing means disposed adjacent said roller for producing a flux passing through said roller over a predetermined segment of its axis of rotation to cause said flux to adhere said mixture to said roller over said segment, means for bringing copy material carrying on image into contact with said mixture on said roller and a collector of magnetic material mounted in the fringe of said field for collecting stray particles of said mixture.

3. An electrostatic copier developing system for applying toner particles at a developing location to copy material carrying a latent electrostatic image including in combination a tray for holding a supply of a mixture of carrier particles of magnetic material and toner particles, a hollow roller, means mounting said roller in said tray adjacent said location for rotary movement around an axis, mean comprising an axially elongated magnet of generally regular configuration mounted within said roller in stationary relationship thereto with one pole thereof adjacent to said location and with the other pole thereof adjacent to said axis for producing a magnetic flux passing through said roller, a shield of magnetic material carried by said magnet mounting means and extending over a predetermined minor segment of the axis of rotation of said roller, said segment trailing said one pole with reference to the direction of movement of said roller to cause said flux to adhere said mixture to said roller over the remainder of the surface of said roller and means for bringing copy material carrying an image into contact with said mixture on said roller at said location.

4. An electrostatic copier developing system for applying toner particles to copy material carrying a latent electrostatic image, including in combination a tray for holding a supply of a mixture of carrier particles of magnetic material and toner particles, a roller, means mounting said roller for rotary movement in said tray, means for rotating said roller in a given direction around an axis, said roller having axially extending serrations projecting from its surface, said serrations being forwardly inclined in the direction of rotation of said roller, means disposed adjacent said roller for producing a magnetic flux passing through said roller over a predetermined segment of its axis of rotation to cause said flux to adhere said mixture to said roller over said segment with at least some of said magnetic particles extending in the direction of inclination of said serrations and means for bringing copy material into contact with said mixture on said roller in a direction against the direction of movement of the roller surface to cause said toner to be brushed onto said material.

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