US3502407A - Pneumatic delivery device - Google Patents

Description

March 24, 1910 v ,9, GRANZ' W ,ETAL 3,502,407 'PNEUMAT'IC'DELIVERY- DEVI-CE Filed July 26. 19 67 SIGNAL .SOURCE DA TA United States Patent O 3,502,407 PNEUMATIC DELIVERY DEVICE Daniel B. Granzow, Arlington Heights, and James B.

Ellis, Chicago, Ill., assignors to Addressograph-Multigraph Corporation, Mount Prospect, 11]., a corporation of Delaware Filed July 26, 1967, Ser. No. 656,204

Int. Cl. G03g 15/00 I U.S. Cl. 355--3 4 Claims ABSTRACT OF THE DISCLOSURE A pneumatic delivery device for a fuser unit delivers a copy sheet bearing a developed and fused image into a receiving tray at the fusers exit. An upwardly directed stream of air established by a blower impinges the backside of the copy sheet as it emerges from the exit thereby immediately cooling the sheet and maintaining the general horizontal movement of the sheet as the sheet crosses the span between the exit and tray.

BACKGROUND OF THE INVENTION This invention relates to an improved fuser unit used in the photoelectrostatic copying art and, more particularly, relates to a pneumatic delivery device for fusers which cools a copy sheet as it emerges from the fuser and guides it into a receiving tray.

As is well known in the photoelectrostatic copying art, a copy sheet having a light sensitive photoconductive layer is uniformly charged and then exposed to an intelligible pattern of light and shadow. The photoconductive layer is discharged in the light struck areas resulting in the formation thereon of a latent electrostatic image. This latent image is converted into a visible form by selectively applying to the sheet a heat responsive developer material, generally a pigmented thermoplastic resin. The developer material, which is attracted to the latent image, is then subjected to heat. The material melts and upon cooling is permanently bonded to the copy sheet.

Machines designed to carry out the above described imaging process employ a fuser unit for melting the developer material. Conventional fuser units are equipped with conveyors which feed the sheet past heating elements and out an exit into a receiving tray. Feed rollers and guides located at the exit advance the sheet and guide it into the tray. When the fuser is operated for prolonged periods, the feed rollers and guides become heated. With the rollers and guides in a heated condition, the softened or molten image on the copy sheet, since it does .not have an opportunity to cool as it emerges from the exit, is smeared when it is handled and ollsets onto the rollers and guides. This deposit of developer material on the feed rollers and guides is redeposited on the same or subsequently developed sheets. The deposit on the feed rollers and guides also interferes with smooth passage of the sheets therebetween and tends to cause sheet jamming in the fuser unit. If a sheet is detained in the fuser, it is charred or more likely burned. This not only destroys the sheet, but causes a serious fire hazard. Moreover, when copy sheets are fed through the fuser unit in rapid succession and are stacked in the receiving tray, the molten material image acts as a bonding agent which glues the sheets together as they pile one on top of the other.

SUMMARY OF INVENTION The principle object of this invention is to freely feed a copy sheet from a fuser unit without smearing the developed image thereon or fouling the sheet in the fuser, while simultaneously cooling the developed image. A

related object is to eliminate guides and feed rollers at the fuser exit so that the softened developed image will avoid making physical contact with the rollers and guides and thereby not be offset thereon. Another object of this invention is to provide a safe fuser unit which eliminates or reduces the possibility of fire.

In accordance with this invention there is provided a copy sheet processing device comprising means for heating the copy sheet, said heating means having an exit, means for moving the copy sheet through the heating means'and feeding said sheet out said exit in a generally horizontal direction, means disposed at the exit for receiving the copy sheet as it emerges from the exit, and means at and below the exit for establishing an upwardly directed stream of air that impinges the backside of the copy sheet as it emerges from the exit to cool the sheet and guide it into the receivingmeans.

- The means establishing the air stream are preferably disposed transverse to the direction of movement of the sheet to provide a stream of air that corresponds to the width of the copy sheet. Such an arrangement effectively cools all the heated areas of the sheet immediately as the sheet leaves the fuser unit.

Control means associated with the air stream establishing means regulate the force withwhich the air stream strikes the backside of the sheet so that the generally horizontal movement of the sheet is maintained as the sheet crosses the span between the exit and receiving means.

DESCRIPTION OF DRAWINGS For a better understanding of this'invention as well as further features and objects thereof reference is had to the following detail description to be read in conjunction DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawings, and in particular to FIG- URE 1, there is shown a photoelectrostatic imaging machine 10 embodying the pneumatic delivery device 12 of this invention. The imaging machine 10 is adapted to make prints on photoelectrostatic sheet material such as, for example, a zinc oxide-resin binder mixture coated on a paper base sheet. Light sensitive material of this type supplied by the roll supply 14 and cut into sheets by the cutter 16 is advanced along a predetermined path 18 by a series of spaced feed rollers sequentially past a charging station 22, an exposure station 24, a developing station 26, a fusing station 28, out an exit 30 in the fusing station into a receiving tray 32. The pneumatic delivery device 12 immediately cools the emerging sheet 34 and guides it into the tray 32.

The charging station 22 is of a conventional design and include'sa pair of spaced electrodes 36 and 38 which straddle the path 18. These electrodes 36 and 38 each respectively comprise shields 40 and 42 which partially surround a series of emission wires 44 and 46. The copy sheet is fed into the charging station 22 between the electrodes 36 and 38 with the. photoconductive coating face down. Since this type of coating more readily accepts a negative sensitizing charge, the emission wires 46 are connected to the negative terminal of a high level DC. power supply (not shown) while the emission wires 44 are connected to the positive terminal of the power supply. A charging zone is created between the electrodes 36 and 38 which forms a uniform deposit of negative charge on the photoconductive layer of the copy sheet as it passes between the electrodes.

The sheet is next advanced to the exposure, station 24 where the charged layer is exposed to a pattern of light and shadow. In accordance with one embodiment of the invention a cathode ray tube 48 is employed to expose the copy sheet. However, several different types of exposure systems can be employed which utilize, for example, projection or contact optical devices that cast a light image corresponding to a graphic original onto the copy sheet. The cathode ray tube 48 is connected to a data signal source 50 such as the output of a computer or a long distance communication link. The electrical data signals are converted by the tube 48 into a scanning light beam, which is displayed on the face 52 of the tube 48. As the copy sheet moves past the face 52 of the tube 48 the scanning beam sweeps across a narrow transverse segment of the sheet, discharging the sheet in light struck areas to provide a latent electrostatic image corresponding to the data signals.

After being exposed the copy sheet is fed to the developing station 26 where a heat responsive developer material, such as a pigmented thermoplastic resin, is selectively applied to the exposed photoconductive layer to render the latent image visible. The developing station 26 is of the magnetic brush type which employs a mixture of developer material and a magnetically attracta'ble carrier, such as iron particles. The developer material and carrier particles are formed into a brush like configuration 54 on the periphery of a revolving cylinder 56. As the copy sheet comes into tangential contact with the brush formation 54 the developer material, which has been triboelectrically charged to a positive polarity, is attracted ot the negative image areas on the sheet. Although cascade and liquid developing units can be employed, the preferred developer device is of the type disclosed in U.S. Patent No. 3,003,462.

With the latent image converted to a visible form, the sheet is fed into the fusing station 28. An air blow turn around device 58, intermediate the developing station'26 and the fusing station 28, changes the direction of movement of the sheet while smiultaneously avoiding smearing the unfused developed imagewhich loosely adheres to the surface of the sheet. The exhaust tubes 60 of the turn around device 58 provide a series of air jets which deflect the lead edge of the sheet as it leaves the developing station 26 to change the direction of movement of the sheet and feed the sheet into the nip of the pair of feed rollers 62. The feed rollers 62, as well as roller pairs 64, 66, and 68, each are made of a nap material which triboelectrically is compatible with the developer. The nap material selected is widely separated in the triboelectric series from the location in the series of the developer material. Nylon brush type rollers are preferred. When rollers of this type are'used, offsetting of the developer material on the rollers is reduced or altogether eliminated. For a detail description of the blower turn around device 58' and the rollers 62, reference may be had respectively to U.S. Patents Nos. 3,276,452 and 2,894,744.

The sheet is fed by the rollers 62, 66, and 68 to a conveyor 70 which moves the sheet 34 out the exit 30 in a generally horizontal direction. The conveyor 70 includes an upper endless belt 72 wound about a drive roller 74 and an idler roller 76, and a lower endless belt 78 wound about a drive roller 80 and an idler roller 82. A number of infrared lamps 84, disposed above the path 18 between rollers 74 and 7-6 directly over the surface bearing the developed image, emit radiant energy which is transmitted through the belt 72 and absorbed by the developer material. The belts 72 and 78 are made of a flexible chain mesh which permits the radiant energy to be readily transmitted to the copy sheet. With the absorption of radiation by the developed image, the developer material is softened to the point where it can flow and the overall temperature of the sheet is elevated. The belts 72 and 78 are spaced apart from each other to provide a gap of about of an inch. As a result of the gap the developed surface of the copy sheet 34 does not normally come into contact with the upper belt 72. However, if the sheet 34 curls, the upper belt 72 prevents the sheet from becoming ensnared in the infrared lamps 84. The radiant energy output of the lamps 84 and the speed the sheet 34 is fed through the fusing station 28 are controlled so that charring of the sheet is avoided.

In accordance with the principle feature of this invention, the pneumatic delivery device 12 is provided at the exit 30 so that as the sheet 34 proceeds out the exit in a generally horizontal direction, the air stream established by the device 12 cools the sheet and guides it into the tray 32. The pneumatic delivery device 12 includes a fan 86 mounted below the exit 30 in a position disposed transverse to the direction of movement of the sheet 34, a housing 88 for the fan having a perforated base 90 and a pair of vertical baffle walls 92 and 94 on opposite sides of the fan which form an air duct, a motor 96 (FIGURE 2), and a diffusion control plate 98 having a plurality of holes 100 therein. As best seen in FIGURE 2, the blades 102 of the fan 86 are slightly longer than the width of the copy sheet 34. The fan 86 mounted on a drive shaft 104 is driven by the motor 96. When the motor 96 is turned on the fan 86 is rotated sucking air through the perforations in the base 90 and blowing it upwardly towards the backside of the sheet 34 as it emerges from the exit 30. The air stream provided by the fan 86 serves as a platform over which the emerging copy sheet 34 rides. Since this platform of air extends across the width of the sheet 34, all the heated areas of the sheet are immediately cooled as the sheet leaves the fusing station 28.

The holes 100 in the control plate 98 regulate the force with which the air stream established by the M pneumatic delivery device 12 strikes the emerging copy sheet 34 so that the generally horizontal directional movement of the sheet is maintained for the time it takes the sheet to cross the span between the exit 30 and the tray 32. By varying the number and size of the holes 100 the force of the air stream can be regulated. Alternatively, this force can be controlled by adjusting the rate at which the motor 96 revolves the fan 86. When about 70% of the sheet 34 has emerged from the exit 30, the weight of the leading portion of the sheet causes the sheet to fall into the tray 32. In addition to the cooling and guiding action provided by the air stream at the exit 30, it also cushions the fall of the sheet and suspends the trailing edge of the sheet as it moves past the span between the exit and tray 32.

Although the air stream at the exit 30 is controlled so that it will not substantially alter the direction of movement of the sheet 34, a safety plate 108 mounted at the exit 30 above the path 18 is provided in order to prevent the sheet from becoming fouled at the exit in the event that the pneumatic device 12 has not been properly adjusted for a particular weight of copy sheet.

It is apparent that certain modifications can be made in the copy sheet processing device of this invention without departing from the spirit and scope thereof. Accordingly, the above description and accompanying drawings should be interpreted in an illustrative rather than limiting sense.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In a device for processing a copy sheet bearing a developed image, said image being rendered permanently fixed to the sheet by the application of heat, the combination including a fuser for heating the image on the copy sheet, said fuser having an exit;

feeder means associated with the fuser for moving a copy sheet through the fuser and feeding the sheet out the exit in a generally horizontal direction;

a receiving tray disposed at the exit in a position adapted to receive the copy sheet as it is fed from the fuser;

blower means disposed below the exit in a position transverse to the direction of movement of the copy sheet for establishing an upwardly directed stream of air that provides an air platform which is about as wide as the copy sheet so that as the sheet emerges from the exit substantially all the heated areas of the sheet are immediately cooled; and

control means associated with the blower means for regulating the force the air stream strikes the emerging copy sheet so that the generally horizontal direction of movement of the sheet is maintained as the sheet leaves the exit and moves into the tray.

2. In a machine for imaging a photoelectrostatic copy sheet, the combination including a charging station for applying a uniform electrostatic charge to the sheet;

an exposure station for exposing the charged sheet to a pattern of light and shadow to produce thereon a latent electrostatic image;

a developing station for selectively applying a heat responsive developer material to the sheet in order to convert the latent image into a visible form, said developer material with the application of heat becoming permanently bonded to the sheet;

a fusing station for heating the sheet and thereby permanently fixing the developer material to said sheet, said fusing station having an exit through which the developed sheet is fed;

a receiving means disposed at the exit in a position adapted to receive the sheet as it leaves the fusing station;

means for moving the sheet along a predetermined path through the machine sequentially past said stations and feeding the sheet out the exit in a generally hori- Zontal direction;

and means disposed intermediate the exit and receiving means and below said path for establishing an upwardly directed stream of air which impinges against the copy sheet as it emerges from the exit to immediately cool the sheet inlcuding the image thereon and guide said into the receiving means.

3. The machine as set forth in claim 2 including means associated with the air stream establishing means which regulate the force said stream of air impinges said sheet so that the generally horizontal direction of movement of the sheet is maintained as the sheet moves from the exit to the receiving means.

4. The machine as set forth in claim 2 wherein said air stream establishing means is disposed transverse to the direction of movement of the sheet to provide a stream of air that corresponds substantially to the width of the copy sheet, whereby substantially all the heated areas of the sheet are immediately cooled as the sheet emerges from the exit.

References Cited UNITED STATES PATENTS 3,162,104 12/1964 Medley 355-9 3,345,926 10/1967 Tiger et a1. 3551O 3,382,763 5/1968 Bruning 35510 NORTON ANSHER, Primary Examiner R. A. WINTERCORN, Assistant Examiner US. 01. X.R.

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