US3238921A - Electronic printing apparatus - Google Patents

Description

March 8, 1966 s. E. ENGELSTAD ETAL 3,238,921

ELECTRONIC PRINTING APPARATUS Filed March 14, 1963 5 Sheets-Sheet l 0mm my G0R6 1 [#65]. $740 6/186??? FAELAA I Jon/v CLEYBERGH INVENTORS CJXYM March 1966 G. E. ENGELSTAD ETAL 3,238,921

ELECTRONIC PRINTING APPARATUS 5 Sheets-Sheet 2 Filed March 14, 1963 GEORGE E. E/VGELSTAD GILBERT FAELLAC/ JOHN CLEYBERGH INVENTORS BY; I

Mamh 1966 G. E. ENGELSTAD ETAL 3,233,921

ELECTRONIC PRINT ING APPARATUS Filed March 14. 1963 5 Sheets-Sheet 5 Games A. Emeasmo 6/155 FAELLAC/ JOHN ClEYBERl-l INVENTORS ATT'YS.

March 8, 1966 G. E. ENGELSTAD ETAL 3,233,921

ELECTRONIC PRINTING APPARATUS Filed March 14, 1963 5 Sheets-Sheet 4 GEORGE Eueflsrno GILBERT HusuAc/ JOHN CLEYBERGH INVENTORS A'I'TYs.

March 1966 cs. E. ENGELSTAD ETAL ELECTRONIC PRINTING APPARATUS Filed March 14, 1965 United States Patent 3,238,921 ELECTRONIC PRINTING APPARATUS George E. Engelstad, Skokie, John Cleybergh, Des

Plaines, and Gilbert Faellaci, Niles, Ill., assignors to A. B. Dick Company, Chicago, 111., a corporation of Illinois Filed Mar. 14, 1963, Ser. No. 265,176 7 Claims. (Cl. 118637) This invention relates to an apparatus for use in the development of electrostatic images. In particular, the apparatus of this invention includes a fluid developing system which can be employed for developing the electrostatic images on a continuous or individual basis whereby increase in the efiiciency and economy of producing copy sheets can be realized.

Many systems have previously been employed for developing latent images disposed on a carrier or copy sheet. In the xerox process, an electrostatic image is formed on a selenium plate by exposure of the charged plate to a light pattern. The electrostatic image on the plate is thereafter transferred to a copy sheet and the image is developed through the use of materials in a dry system composed of a pigment of toner mixed with a situable dry carrier.

In a further system known as the Videograph process, an original is scanned to develop an electrostatic signal which is transferred to a cathode ray tube having an array of conductive wires in its face. The electrostatic signal is then imposed on the wires to transmit an electrostatic charge through the tube for deposition onto copy paper advanced past the tube. The electrostatic image is then developed with the use of a dry system similar to the system described above.

The use of a dry process for the development of an electrostatic image has been found to be subject to a number of objections. It has been found difiicult to achieve a desirable uniformity in the distribution of the toner and carrier particles in the developer with the result that variations occur in the intensity of color in the developed image. Background has also been found to be a problem due to the inability to completely remove the developing materials -from non-image areas of the copy sheet. An additional drawback results due to the necessity for fixing .the developer on to the copy sheet as by means of a heating operation. A considerable amount of heat is required to fuse the components in the toner and this heat has effected distillation of some ingredients in the copy sheet which has resulted in condensation upon elements in the developing apparatus. The heat has also been known to damage the copy sheet as by charring. Finally, the fine powder employed in a dry system has been found to condensate the atmosphere as well as the elements making up the developing apparatus.

It is an object of this invention to provide an apparatus for use in the development of electrostatic images on copy sheets which overcomes the drawbacks recognized in developing systems employing dry techniques.

It is a more particular object of this invention to provide a developing apparatus which utilizes a liquid developing system wereby substantial improvements in the economy and efficiency of a developing operation can be realized.

These and other objects of this invention will appear hereinafter and for purposes of illustration but not of limitation, specific embodiments of this invention are shown in the accompanying drawings in which:

FIGURE 1 is a diagrammatic view of the developing apparatus of this invention;

FIGURE 2 is a detail elevational view of the mechanisms employed for applying liquid developer to a copy sheet;

FIGURE 3 is a detail rear elevational view of a portion of the developer applying means;

FIGURE 4 is a side elevational view of the developer applying means;

FIGURE 5 is a side elevational view taken on the opposite side of the developer applying means;

FIGURE 6 is an elevational view partly in section of the drying mechanism for the copy sheet;

FIGURE 7 is an enlarged cross-sectional view taken about the line 7-7 of FIGURE 6; and

FIGURE 8 is an enlarged cross'sectional view taken about the line 88 of FIGURE 6.

The developing apparatus of this invention comprises means which are adapted to support a sheet having a latent electrostatic image disposed thereon. The sheet is moved by its supporting means to a developing means and a source of liquid developer is supplied at this point. The developing means includes mechanisms which are effective to uniformly distribute the developer over the surface of the sheet which holds the latent image. The developer is thereafter dried on the sheet to produce the completed copy.

The means for applying the developer to the copy sheet represent an important phase of the invention since uniformity in application is quite important. In addition, the preferred form of this invention includes a novel drying system which is effective to fix the image on the copy sheet in a highly efiicient manner.

The diagrammatic illustration in FIGURE 1 provides a general description of the operation of the apparatus of this invention. In this apparatus, .a paper tape 20 is fed from a supply roll 22 over a plurality of guide rollers 24 which extend throughout the apparatus. In the embodiment shown, the tape 20 is first fed to an electronic printing tube 36 of the type employed in a Videograph system. After receiving a latent electrostatic image, the tape is transferred to a liquid developing means 38. The liquid developer is uniformly distributed over the tape at this time, and the tape is then fed to a dryer 40. A takeup roll 42 is adapted to receive the tape with a fixed image thereon in systems involving a continuous developing operation. Although the illustrated embodiment provides for the use of a continuous paper tape, it will be understood that the mechanisms of this invention are equally suitable for use in the developing of sheets of a variety of compositions and sizes.

FIGURES 2 through 5 illustrate in detail the structure of the liquid developing means 38 of this invention. The developing means includes a tray 44 through which liquid developer 46 is circulated. The developer is fed to the developing means through a line 48 and the outlet 4% of the tray 44 communicates with the line 50 whereby the developer can be circulated as by means of pump 52 (see FIGURE 1).

The inlet line 48 communicates with a cylindrical member 54 which extends laterally across the tray 44. This cylindrical member includes an internal tube 55 which has openings 57 defined in its lower surface. An elongated slot 56 is defined by the cylindrical member 54, and this slot extends along the length of the cylindrical member for a distance at least sufficient for the distribution of liquid developer on all portions of the tape 20' which receive an electrostatic image. A roller 58 is disposed opposite the slot 56 and the tape 20 is guided in contact with the underside of this roller whereby the tape will continuously move past the slot 55. Roller 59 acts to squeeze some excess developer out of the tape prior to passage to the dryer.

In the operation of the apparatus, liquid developer is fed through line 48 into the tube 55 whereby the developer passes out of the openings 57 into the enclosure defined by the cylindrical member 54. The liquid is then fed through the slot 56 into contact with the surface of the tape which carries the electrostatic image. It will be appreciated that the liquid issuing from the slot 56 will be in the form of a narrow band and since the pump 52 will operate continuously, fresh developing liquid will be continuously moved into contact with the surface of the moving tape. During circulation of the liquid developer, the ingredients thereof which may be depleted can be re plenished so as to further enhance the uniform conditions of the operation.

It will be noted that the cylindrical member 54 has a hook means associated therewith adjacent the coupling 61 with the line 48. This hook means is adapted to engage knob 62 which is threaded into a mounting plate 64. When the knob 62 is loosened, the hook means 60 can be rotated whereby the cylindrical member 54 can be removed for cleaning or replacement.

The association of the cylindrical member with the plate 64 permits adjustment of this member to achieve uniform distribution of developer on to the paper tape. Thus, it will be noted that the plate 64 is secured to the stationary frame member 66 of the apparatus by means of screw 28, and 72. The screws 68 and 70 (see FIGURE 3) permit adjustment of the plate 64 about the bushing 71 whereby the slot 56 can be disposed exactly opposite the lowermost point of the roller 58.

The screw 72 passes through the frame member 66 and is threaded into the plate 64. Movement of this screw tend to pivot the plate 64 whereby the cylindrical member 54 can be swung to locate the slot 56 in a position in parallel with the surface of the roller 58. This adjustment is also desirable in case the pressure of the liquid within the cylindrical member varies from end to end, and, therefore, the uniformity in distribution of the liquid can be achieved by moving the cylindrical member somewhat out of parallel with respect to the roller 58. A spring 74 is fastened on the plate 64 and this spring engages pin 76 whereby the plate 64 and the associated cylindrical member 54 will be held steady within the apparatus.

A pair of projection members 73 extend outwardly from the frame 66 and clamps 79 connected to the tray 44 engage these projecting members. By disconnecting the outlet line 50, the tray 44 can be easily removed for cleaning or replacement.

The drying apparatus 40 illustrated in detail in FIG- URES 6, 7 and 8 includes an air inlet duct 80 located at its upper end. A plurality of guide vanes 82 extend an gularly downwardly from this duct and these vanes define a plurality of passages each of which terminates in a distributor 84. Outlet openings 86 of these distributors are located at a plurality of vertical levels in the apparatus and these openings communicate with the paper tape 24) as it is moved upwardly through the dryer.

A vertical plate 88 is positioned in opposed relationship with respect to the outlet openings 86 and the passage for the tape 29 is defined between this plate and the outlet openings. The plate 88 is fastened to a housing 90 and this housing confines heating elements 92. Terminals 94 extend through the housing whereby power can be trans mitted to the heating elements and whereby heat can be radiated from the plate 88. Adjusting screws 95 hold the elements 92 against the plate 88.

The distributors 84 include baffles 96 within their interiors. Screws 98 are associated With these baffles adjacent the outlet openings 86. By rotating these screws, the spacing between the members 96 and the upper wall of the distributors 534 can be regulated, and, therefore, the passage of drying air into contact with the paper tape can be controlled. Exhaust ducts 1439 are formed adjacent the outlets 86 for removal of the drying air.

In the operation of the drying apparatus, the paper tape is fed from the developing means 38 to the lower end of the drying apparatus where guide rollers 24 direct the tape upwardly between the plate 88 and the outlet openings S6. The drying air is delivered to the surface of the paper tape whereby the liquid developer will be fixed on the surface of the tape in a highly etficient manner. The heating provided by means of the plate 86 will serve to provide a more rapid drying operation and these heating means are particularly desirable in situations where the amount of developer used, the nature of the paper tape, or atmospheric conditions present a particularly wet tape. In this connection, it is also contemplated that the drying air be heated to further accelerate the drying operation. It will be understood, however, that the amount of heat employed is relatively low and does not approach temperatures which would tend to char the paper.

As indicated, the particular drying apparatus is effective to improve the efficiency of operation in the production of copy material provided by means of a liquid developing system. It is contemplated, however, that the devel' oping system be employed with less efficient drying means including the passage of the tape over guide rollers in the apparatus until it dries without the use of accelerating mechanisms. However, the described drying apparatus is particularly suitable for the rapid drying of the tape, under conditions such as high humidity Where the tape will not dry of its own accord, and in situations where it is not desirable to take up undue space for transporting the tape while it dries of its own accord.

In order to provide an efiicient operation for the pro duction of copy sheets while using liquid developing techniques, it is important that a suitable liquid developer be employed. Reference is made to copending application Serial No. 205,690, filed June 27, 1962, and entitled Composition and Method for Developing Latent Electrostatic Images, for a disclosure of suitable developers.

It will be understood that various changes and modi fications can be made in the above described apparatus which provide the characteristics of this invention without departing from the spirit thereof particularly as defined in the following claims.

That which is claimed is:

1. An apparatus for developing a latent image produced on a paper tape by means of an electrostatic technique, said apparatus comprising means for continuously moving said tape to a developing means, a source of liquid developer, and means for drying said tape after application of the developer thereto, said developing means comprising a horizontally disposed enclosure located beneath the path of movement of said tape, an elongated, horizontally disposed slot defined at the top of said enclosure and extending perpendicular to the direction of movement of said tape, feeding means for continuously supplying liquid developer, a tubular member disposed within said enclosure, the length of said tubular member being substantially coextensive with the length of said slot, said tubular member communicating with said feeding means, at least one opening defined by said tubular member whereby liquid developer is adapted to be fed into the tubular member and out of said opening into said enclosure for distribution onto said tape through said slot, a guide roller, said guide roller and said enclosure being maintained in closely spaced apart relationship whereby said tape contacts the upper surface of said enclosure and the bottom side of said roller, and tray means disposed beneath said enclosure for collecting unused developer liquid.

2. An apparatus for developing a latent image produced on a paper tape by means of an electrostatic technique, comprising means for moving said tape to a developing means, a source of liquid developer, and means for drying said tape after application of the developer thereto, said developing means comprising an enclosure which defines an elongated slot extending perpendicular to the direction of movement of said tape, means for feeding said liquid developer into said enclosure whereby it is adapted to pass out through said slot into contact with said tape, said developing means including a guide roller, and wherein said tape is passed continuously through said apparatus and into contact with said roller, the enclosure of said developing means including a cylindrical member positioned in closely spaced relationship with respect to said guide roller whereby said tape is adapted to pass between said cylindrical member and said guide roller, said slot being formed in the upper side of said cylindrical member and said tape passing in contact with the lower surface of said guide roller, an internal tubular member in communication with said source of liquid developer, a pair of openings defined in the lower side of said tubular member at either end thereof for passing said developer into said cylindrical member, and means for continuously supplying said developer whereby the developer continuously moves out of said slot into contact with said paper tape.

3. An apparatus in accordance with claim 2 including means for adjusting the position of said enclosure relative to said tape whereby uniform passage of developer out of said slot into contact with said tape can be achieved.

4. An apparatus for developing a latent image produced on a sheet by means of an electrostatic technique, com prising means for moving said sheet to a developing means, a source of liquid developer, means positioned at said developing means for uniformly distributing said developer over the face of said sheet having said latent image thereon, a drying means including a source of drying air, means for moving said sheet through said drying means, and means for distributing air over the surface of said sheet whereby said developer is fixed on said sheet, said drying means comprising a vertically disposed housing, and an air inlet at the top of said housing, a plurality of guide vanes extending downwardly from said housing and defining passages to said distributing means, said distributing means being located at a plurality of vertical levels in said drying means and means for passing said sheet closely adjacent the outlet openings of said distributing means.

5. An apparatus in accordance with claim 4 including means for adjusting the size of said outlet openings to regulate the passage of drying air therethrough.

6. An apparatus for developing a latent image produced on a paper tape by means of an electrostatic technique, comprising means for moving said tape to a developing means, a source of liquid developer, means positioned at said developing means for uniformly distributing said d veloper over the face of said tape having said latent image thereon, a drying means comprising a vertically disposed housing, means for moving said tape through said drying means, means for supplying drying air to said drying means, an air inlet at the top of said housing for receiving said air, a plurality of guide vanes extending downwardly from said housing and defining passages therebetween, distributing means located in communication with each of said passages, means for adjusting the size of said distributing means to regulate the passage of drying air therethrough, said distributing means being located at a plurality of vertical levels in said drying means and means for passing said tape upwardly through said drying means closely adjacent the outlet openings of said distributing means.

7. An apparatus in accordance with claim 6 including a vertical plate positioned in opposed relationship with respect to said outlet openings whereby the path of movement of said paper tape is defined between said plate and said outlet openings, and including heating means positioned behind said plate for assisting in the drying of said tape.

References Cited by the Examiner UNITED STATES PATENTS 927,995 7/1909 Morrow 34-156 998,206 7/1911 Ross et al 34160 X 1,361,932 12/1920 Van Avermaete 118-410 2,008,230 7/1935 Spooner 34156 X 2,269,169 1/1942 Van Derhoef et al. 118412 X 2,724,907 11/1955 Walter 34160 X 3,012,839 12/1961 Epstein et al 118637 X 3,038,073 6/1962 Johnson 118637 X 3,058,405 10/1962 Limberger 118637 X 3,096,198 7/1963 Schatfert 117111 3,124,484 3/1964 Magnusson 118-259 X 3,168,021 2/1965 Levene 118637 X 3,176,653 4/1965 Hansen l18410 X CHARLES A. WILLMUTH, Primary Examiner. WILLIAM D. MARTIN, Examiner.

Claims (1)

1. AN APPARATUS FOR DEVELOPING A LATENT IMAGE PRODUCED ON A PAPER TAPE BY MEANS OF AN ELECTROSTATIC TECHNIQUE, SAID APPARATUS COMPRISING MEANS FOR CONTINUOUSLY MOVING SAID TAPE TO A DEVELOPING MEANS, A SOURCE OF LIQUID DEVELOPER, AND MEANS FOR DRYING SAID TAPE AFTER APPLICATION OF THE DEVELOPER THERETO, SAID DEVELOPING MEANS COMPRISING A HORIZONTALLY DISPOSED ENCLOSURE LOCATED BENEATH THE PATH OF MOVEMENT OF SAID TAPE, AN ELONGATED, HORIZONTALLY DISPOSED SLOT DEFINED AT THE TOP OF SAID ENCLOSURE AND EXTENDING PERPENDICULAR TO THE DIRECTION OF MOVEMENT OF SAID TAPE, FEEDING MEANS FOR CONTINUOUSLY SUPPLYING LIQUID DEVELOPER, A TUBULAR MEMBER DISPOSED WITHIN SAID ENCLOUSURE, THE LENGTH OF SAID TUBULAR MEMBER BEING SUBSTANTIALLY COEXTENSIVE WITH THE LENGTH OF SAID SLOT, SAID TUBULAR

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