PRINTING MACHINE WITH ELECTROSTATIC WEB DEVELOPING APPARATUS
United States Patent 3859960
A printing machine wherein a pliable record material wrapped to form a supply roll includes means for recording information upon the record material, an upwardly inclined platen supports and guides the record material upwardly, and means for feeding the material engages same at the lower end of the platen and serves to push the pliable material up the platen. An air stream impinges upon the material while the material is moving upwardly across the platen to maintain the material in a flattened state against the platen preventing buckling thereof during its upward travel. The supply roll is mounted upon a readily removable support providing a modest restraint from within the core of the supply roll. A fountain of developing toner fluid is disposed to contact the recording material immediately upstream of an upwardly extending wiping means for removing excess toner fluid from the web of recording material when drawn thereacross.
US Patent References:
Method and apparatus for coating paper
Martinek - April 1965 - 3179536
Abrasive work back-up to recondition doctor blade
Kuhnel - July 1965 - 3195500
Method and apparatus for liquid development of latent images
Ostensen - August 1965 - 3202526
Fluid applicator apparatus
Johnson et al. - March 1968 - 3371651
Applicator device
Beyer et al. - October 1968 - 3407786
Method and apparatus for coating paper
Martinek - April 1965 - 3179536
Abrasive work back-up to recondition doctor blade
Kuhnel - July 1965 - 3195500
Method and apparatus for liquid development of latent images
Ostensen - August 1965 - 3202526
Fluid applicator apparatus
Johnson et al. - March 1968 - 3371651
Applicator device
Beyer et al. - October 1968 - 3407786
Application Number:
05/335835
Publication Date:
01/14/1975
Filing Date:
02/26/1973
View Patent Images:
Export Citation:
Assignee:
Versatec, Inc. (Cupertino, CA)
Primary Class:
Other Classes:
399/249, 399/247
International Classes:
G03G15/00; G03G15/10; G03G15/32; G03G13/00
Field of Search:
118/104,429,637,DIG.23 117/37LE
US Patent References:
Primary Examiner:
Stein, Mervin
Assistant Examiner:
Millstein, Leo
Attorney, Agent or Firm:
Flehr, Hohbach, Test, Albritton & Herbert
Parent Case Data:
CROSS-REFERENCE TO RELATED APPLICATION
This application is a division of U.S. Ser. No. 93,256, filed Nov. 27, 1970, now U.S. Pat. No. 3,729,123, in the name of WILLIAM A. LLOYD, entitled PRINTING MACHINE AND METHOD, and assigned to VERSATEC, INC., recorded Nov. 27, 1970, Reel 2678, Frames 782-784.
Claims:
I claim
1. In an electrostatic printer of a type using a length of record material wrapped to form a supply roll to be fed along a path as a web through a printing station for electrostatically charging discrete portions of said web, apparatus for developing said portions comprising a supply reservoir of liquid toner material, a first elongate tray having relatively thin upwardly disposed walls extending substantially horizontally across the path of said web and lying beneath same, a second elongate tray containing said first tray and encircling the periphery of said first tray, said second tray having relatively thin upwardly disposed walls extending transversely of said web, said transversely extending walls being spaced well clear of the first named said walls to form a catch basin surrounding the first named tray to receive liquid toner material overflowing into the space defined between the walls of said first and second trays, a pump and connections for recirculating said toner material along a path defined from said reservoir to said first tray then overflowing into said second tray and returning to said reservoir, said first tray being disposed at a level relative to said web to carry the overflowing toner material into contact with said web portions to develop same, a pair of elongate wiper blades disposed in said second tray in spaced relation to each other and downstream of said first tray intermediate the confronting side walls of said first and second named trays, said blades each including a horizontal edge extending transversely across the path of said web and disposed to remove toner from the web and return the toner directly into said second tray, and a pressure member including a plurality of downwardly depending fingers serving to engage the back surface of said web to confine the travel of said web to move along a generally horizontal path while riding lightly across the upper edges of the walls of said first tray and said edges of said blades.
1. In an electrostatic printer of a type using a length of record material wrapped to form a supply roll to be fed along a path as a web through a printing station for electrostatically charging discrete portions of said web, apparatus for developing said portions comprising a supply reservoir of liquid toner material, a first elongate tray having relatively thin upwardly disposed walls extending substantially horizontally across the path of said web and lying beneath same, a second elongate tray containing said first tray and encircling the periphery of said first tray, said second tray having relatively thin upwardly disposed walls extending transversely of said web, said transversely extending walls being spaced well clear of the first named said walls to form a catch basin surrounding the first named tray to receive liquid toner material overflowing into the space defined between the walls of said first and second trays, a pump and connections for recirculating said toner material along a path defined from said reservoir to said first tray then overflowing into said second tray and returning to said reservoir, said first tray being disposed at a level relative to said web to carry the overflowing toner material into contact with said web portions to develop same, a pair of elongate wiper blades disposed in said second tray in spaced relation to each other and downstream of said first tray intermediate the confronting side walls of said first and second named trays, said blades each including a horizontal edge extending transversely across the path of said web and disposed to remove toner from the web and return the toner directly into said second tray, and a pressure member including a plurality of downwardly depending fingers serving to engage the back surface of said web to confine the travel of said web to move along a generally horizontal path while riding lightly across the upper edges of the walls of said first tray and said edges of said blades.
Description:
BACKGROUND OF THE INVENTION
This invention pertains to printing machines and more particularly to a toner fountin feature particularly useful in an electrostatic printer of the type where printing is accomplished electrostatically on a moving web of paper.
In a machine for electrostatically recording upon a web of paper or other recording material, several technologies must be brought together in order to produce a high quality, reliable machine. For example, it is necessary to properly feed or advance the paper web through the machine so that it will provide an even, forward movement past the recording station. The electrostatic recording head must cooperate properly with the paper and the paper must be appropriately tensioned while being fed past the head. In addition, this technology calls for skill in the proper application of liquid or powdered toner material for purposes of developing the paper and, finally, it is quite important that the foregoing skills provide an apparatus which is relatively simple so as to be capable of being easily serviced and operated by office personnel using the machine.
According to the present invention, there has been provided an improved toner application fountain which serves to properly develop the paper web whereby an improved printing machine, particularly useful as an electrostatic printing machine, is provided.
SUMMARY OF THE INVENTION AND OBJECTS
In general, there has been provided a printing machine of a type including a length of pliable record material wrapped to form a supply roll and having means for recording information upon the record material, such as paper.
The printing machine, according to the invention, employs means for guiding the web of recording material across the top of a fountain of liquid toner material for developing electrostatically charged parts of the web.
In general, it is an object of the present invention to provide an improved web developing apparatus for an electrostatic printing machine.
It is another object of the invention to provide an improved printing machine having a particularly improved toner system.
The foregoing and other objects of the invention will become more readily apparent from the following detailed description of a preferred embodiment when considered in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view, partially broken away in section, of a printing machine according to the invention;
FIG. 1A is an enlarged detail view, in perspective, showing a recording head according to the invention;
FIG. 2 is a side elevation in enlarged detail of mechanism for adjusting the recording head of FIG. 1A within the printing machine of FIG. 1;
FIG. 3 is a perspective view similar to FIG. 1 but with the cover removed for clarity;
FIG. 4 is a perspective diagrammatic view in simplified form for demonstrating the opening and closing of the top assemblies of the printing machine according to FIG. 1;
FIG. 5 is a side elevation section view taken along the line 5--5 of FIG. 3;
FIG. 6 is a front elevation view in enlarged detail taken along the line 6--6 of FIG. 5 and further schematically including representations of additional means coupled thereto;
FIG. 7 is an enlarged detail view along the line 7--7 of FIG. 8;
FIG. 8 is an enlarged, detail, perspective view, partially broken away for clarity, of a fountain assembly according to the invention;
FIG. 9 is an enlarged section view taken along the line 9--9 of FIG. 8; and
FIG. 10 is a schematic view in perspective diagrammatically illustrating the provision of an air stream for flattening the paper web against a platen as it is pushed from its lower end.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
A printing machine 10 is formed in general as best disclosed diagrammatically in FIG. 4. Machine 10 in general comprises a support base 11 upon which is mounted a lower frame assembly 12. An upper frame assembly 13 is pivotally hinged to lower frame assembly 12 so that it can be raised through an arc 14 for access to components carried by both assemblies 12 and 13. A top cover 16, pivotally hinged at its rear edge to support base 11, can be moved through the arc 17 independently of the movement of upper frame assembly 13.
Briefly, and continuing to refer to FIG. 4, a supply roll 18 of suitable paper for electrostatic recording is rotatably carried between a pair of supports 19, 21 whereby it may be unwound from the near edge (as seen in FIG. 4).
With reference to FIGS. 1, 3 and 5, it will be readily evident that there has been provided on the lower frame assembly 12 means carried by the lower frame assembly which are adapted to support roll 18 for rotation. Thus, lower frame assembly 12 includes a pair of side plates 22, 23 formed with an angled flange 22a, 22b, respectively, attached to the upper end of support base 11. Support base 11 can, for example, constitute the housing for the machine or other suitable stand.
At each end of roll 18, L-shaped support members 24 are attached, as by screws, through the holes formed in the ends of members 24. Each support member includes a pair of support surfaces 24a, 24b (FIG. 5) disposed to form an angle, such as a right angle, therebetween and which is adapted to receive the protruding ends of an X-shaped support 26.
Roll 18 includes, typically, a hollow cylindrical core formed by the cylindrical core element 27 upon which the paper is wrapped by the manufacturer. X-shaped support 26 provides stationary web-restraining means carried within core 27 which simply consists of a pair of elongated planar elements 26a, 26b (FIG. 5) disposed within core element 27. The planar elements 26a, 26b have a width of the order of the inner diameter of core element 27 and are oriented in substantially mutually perpendicular planes.
Support member 26 protrudes beyond the ends of core element 27 and these substantially mutually perpendicular portions of support member 26 define substantially the same angle as defined between the support surfaces 24a, 24b so as to prevent rotation of the X-shaped support member 26 relative to core element 27 as the web 28 of paper is unwound from roll 18 whereby the stationary portion of support member 26 located within core element 27 rubs against the core element thereby imparting modest tension to the web 28 of paper as it is unwound.
Thus, at least one edge of each element 26a, 26b rubs against the interior of core element 27 during unwinding of the roll.
Means are provided for insuring proper lateral registration of web 28 to insure proper tracking of the web. Thus, it is to be observed that a small cylindrical resilient nylon registration button 29, carried tightly gripped by a bracket 31 (formed as a portion of the L-shaped supports 24), rides against the end of core element 27.
As thus arranged, the bottom of frame assembly 12 serves to support a roll 18 of electrostatic recording paper for proper rotation.
A short stretch 32 or web (FIG. 5) extends between roll 18 and a guide roller 33 whereby upon closure of the upper frame assembly 13, a tension rod 34 extending transversely of frame assembly 13 will engage stretch 32 and move it downwardly thereby tensioning the paper.
Web 28 moves through the machine along a predetermined path next including a recording station 36 comprised of an electrostatic recording head 37 and a back-up assembly 38. Head 37 (FIG. 1A) consists essentially of a pair of opposed fiber glass plates 37a, 37b secured together to embed therebetween an array of evenly spaced conductors 39 arranged to protrude slightly on their upper edge to form conductive nibs 39a.
A number of groups of five conductors 39 is coupled in parallel to recording means whereby upon energization, each of the five conductors in the group will be coupled to a voltage source for recording. However, by means of the potential on sections of the back-up assembly 38, only one of the conductors in any activated group of five will be permitted to record upon web 28.
Thus, in general, a recording control assembly on the other side of, or confronting the other surface of, web 28 opposite to the recording surface extends across the path of web 28 in confronting relation to the head 37. The control assembly includes elongated means disposed on the other side of web 28 from head 37 in electrostatic charging relation to web 28, the elongated means being sub-divided into a plurality of electrically discrete sections each selectively operable to block or permit discrete charging of web 28 by those of the nibs or tips 39a opposed to the sections selected.
Accordingly, with reference to FIG. 5 and FIG. 6, there is shown in confronting relation to head 37 a back-up assembly 38 which includes an elongated insulator mounting bar 41 to which there has been secured a number of flat recording control sections 42. Each section 42 is connected as schematically shown in FIG. 6 to a suitable control means 43 responsive to printing inputs on line 44 whereby only those nibs 39a opposite a selected one of the sections 42 will be permitted to print.
Means adjacent the recording control sections 42 have been arranged for applying a voltage to the web 28 to precondition web 28 so as to permit nibs or tips 39a to apply a predetermined recording charge upon web 28. Accordingly, as best shown in FIG. 5, a so-called guard voltage is applied to the web 28 by connections 46, 47 coupled to elongated, flat conductive bars 48, 49 likewise separated from sections 42 by insulating bars 51.
In general, the guard voltage shown only as a plus (+) sign with respect to connections 46, 47 provides a voltage which rises nearly to the level of the writing potential. Sections 42 are controlled by control means 43 whereby they will either provide a voltage on the order of 200 volts so as to be blocking any writing in their immediate area or switched to a writing potential on the order of 600-700 volts.
As thus arranged, writing can be accomplished by coupling a group of nibs 39a in parallel to ground and controlling those sections 42 which are to be raised to the writing potential of 600-700 volts.
Thus, when the five nibs 39a of a given group are coupled in parallel to a given potential, such as ground, writing will occur at only those nibs 39a where the large potential difference between the nib 39a is being presented in the region of a section 42 which has been coupled to the higher writing voltage mentioned above.
As shown best in FIGS. 5, 8 and 9, means for developing the discrete electrostatically recorded portions of web 28 comprise, in general, a supply reservoir 52 (FIG. 1) of liquid toner material coupled to supply liquid toner directly to an elongated inner tray 53 or fountain via the flow passage 54. The fountain tray 53 extends across the path of web 28 and underlies the web slightly to be disposed at a level which will serve to carry the overflowing toner material into contact with the electrostatically recorded discrete portions prepared on web 28 at recording station 36. A portion of the toner material will adhere to the electrostatically charged discrete portions so as to develop them to form a visible image.
A catch basin tray 56 encircles the periphery of fountain tray 53 so as to catch and return the flow of liquid toner via the flow passages 57 whereby the toner may be circulated back to reservoir 52 by means of the pump 58 and fluid connections 59, 61 (FIG. 1). Fluid connections 59, 61 complete a fluid toner supply path defined directly from reservoir 52 to fountain tray 53 and then overflowing into catch basin tray 56 for returning to reservoir 52.
Flow passage 54 includes diffusion screens 55, 60, 65 whereby the fluid flow of toner via fountain tray 53 will be smoothly flowing and contribute to uniform development of the electrostatic image on web 28.
As shown best in FIG. 8, blade means have been disposed to remove excess toner from web 28 and direct it into the catch basin tray for return to reservoir 52.
Accordingly and more particularly, the blade means comprises a pair of elongated, rigid wiper blades 62, 63, of material such as stainless steel, each formed as an L-shaped member to provide an upper lip 62a, 63a respectively (FIG. 7) whereby the upstream lip 62a is slightly inclined upwardly in the downstream direction and the downstream lip 63a is inclined slightly upwardly in the upstream direction.
The lips 62a, 63a extend across the path of web 28 and in spaced relation in a direction along the path whereby each lip or edge of blades 62, 63 is disposed to engage the web after it has passed through the fountain portion of the developing station.
As thus shown in FIGS. 5 and 9, the upper frame assembly carries means at ground potential for urging web 28 to be pressed lightly into engagement with the upper edges of blades 62, 63 and at a predetermined level through the overflowing portion of fountain tray 53.
Thus, a pressure member 64 (FIG. 5) carried by upper frame assembly 13 by suitable means, such as screws 66 or rivets, is disposed to overlay blades 62, 63 and trays 53, 56. Pressure member 64 may be extruded or molded as desired and extends transversely of the path of web 28.
Pressure member 64 includes a number of downwardly depending fingers 67, 68 and 69 serving to cooperate with the upwardly extending portions of the fountain and wiping assembly therebeneath. Accordingly, the lower tips of fingers 67, 68, 69 serve to confine the travel of web 28 so that it passes in close proximity to the top of fountain tray 53 and rides lightly across the wiping lips 62a, 63a while grounded via lead 70 so as to remove any charge from the back of web 28. Accordingly, high voltages are not required to be handled along with their attendant problems of insulation, etc.
Further downstream from the developing station as described immediately above, web 28 is trained about a drive roller 71 carried by upper frame assembly 13 for cooperation with a pinch roller 72 mounted for rotation in lower frame assembly 12. The ends of pinch roller 72 are of larger diameter than the central portion which has been relieved whereby web 28 will be driven by engagement with drive roller 71 along the marginal portions of web 28.
Thus, upon closure of upper frame assembly 13, as by means of the hold down latches 74 operated by a lever 76 for drawing upper frame assembly 13 firmly down to a lower frame assembly 12 by engagement with the latch pins 77, web 28 will be firmly engaged at its margins between drive roller 71 and the enlarged ends of pinch roller 72 to define the drive nip 73 therebetween.
The relieved portion of roller 72 serves to permit the wet toner carried by web 28 to pass upwardly around drive roller 71 without being smeared.
Drive roller 71 is driven by means of the chain drive 78 powered by motor 79 which is carried conveniently in upper frame assembly 13 by virtue of the design herein disclosed. Upper frame assembly 13 also carries a relatively broad, flat platen 81 disposed in an inclined plane. Web 28 is pushed or driven from behind by the nip 73 defined between drive roller 71 and pinch roller 72 at the lower end of platen 81, operating in conjunction with means forming an air stream directed to impinge upon the material of web 28 while web 28 is moving upwardly across platen 81. As thus arranged, web 28 is maintained in a flattened state against platen 81 to prevent buckling thereof during its upward travel.
Accordingly, a blower 82, preferably of filtered air, is schematically shown in FIG. 1 for supplying air via a relatively thin, elongated, flat duct 83 whereby an air stream 84 will be supplied across substantially the full width of the electrostatically recorded portion of web 28. The air stream 84 moves generally upwardly through duct 83 where it is directed by a portion 86 of the top cover assembly 87 (FIG. 1). Portion 86 (FIG. 5) of cover assembly 87 includes a lip portion 86a which serves to direct air stream 84 downwardly against web 28 so as to flatten it against the inclined plane of platen 81.
Cover assembly 87 includes an open window 88 having a width of the order of, or slightly larger than the width of web 28. Cover assembly 87 further includes a discharge opening 89 through which web 28 is discharged at the upper end of its travel across platen 81. The edges of window 88 provide a slight clearance with respect to the surface of platen 81 whereby air stream 84 may escape through the paths 84a, 84b and 84c.
In general, web 28 is fed upwardly by the method of engaging the opposite surfaces of web 28 between a pair of feed rollers at the lower end of the inclined plane 81 so as to push the material of web 28 upwardly while at the same time directing a stream of air 84 against the upper surface of web 28 to flatten it against the inclined plane. In this manner, the pliable material of web 28 can be fed from behind upwardly across an inclined plane and discharged out through the discharge opening 89 without employing feed rollers to engage the upper end of web 28 thereby simplifying the handling of the web. Further, the leading edge of the web readily finds its way between the edge of cover assembly 87 and platen 81.
Finally, alignment of recording head 37 is readily maintained as by disposing it between a pair of adjustment screws 35 disposed on one side (FIG. 2) and a single adjustment screw 40 disposed on the opposite side whereby screw 40 can serve as a pivot point with respect to adjustment of the plane of head 37. Accordingly, once the plane of head 37 is appropriately established, the degree of projection of head 37 from its mounting can readily be adjusted by means of the elongated screw element 45 or reach rod tapered at its end 45a whereby, upon screwing the reach rod 45 into bracket 50, head 37 will be raised as viewed in FIG. 2.
By providing identical head adjustment assemblies of the type shown in FIG. 2 on each end of head 37, it is possible to adjust head 37 in all directions so as to provide improved control over the quality of electrostatic recording achieved across the length of head 37.
With blower 82 supplying the air stream 84 against the upper surface of web 28, drying of the wet toner will be readily achieved as well as a riffle-free upward feeding of pliable paper across platen 81.
In operation, briefly, loading of supply roll 18 has been described above whereby a length of paper is withdrawn from supply roll 18 and laid across the top of the recording head assembly 36 and fountain assembly, while insuring that sufficient paper has been withdrawn to engage the nip defined between rollers 71, 72. Subsequently, the upper frame assembly 13 is lowered into position so as to cause roller 71 to engage roller 72 and then the top cover can be closed to define the air stream 84 to be directed against web 28 as it passes across platen 81.
Subsequently, motor 79 and blower 82 can be started, along with pump 58, so as to advance the paper through the nip 73 defined between rollers 71, 72. The unwinding movement of web 28 from roll 18 tends to advance the axis of rotation of roll 18 to the left as shown in FIG. 5. However, by virtue of the cooperation of the ends of members 26a and 26b with support surfaces 24a and 24b, the axis of rotation of roll 18 will remain substantially stationary once the left edges (as shown in FIG. 5) of members 26a, 26b engage support surface 24a. At that point, core element 27 will be slightly restrained from rotating by rubbing which occurs at the right hand edges of members 26a, 26b engaging the inner circumference of core element 27. This slight restraint serves to tension web 28 properly for feeding and recording.
From the foregoing, it will be readily evident that there has been provided an improved printing machine wherein a roll of paper can be easily loaded, fed along a path including an improved recording head assembly utilizing techniques of selective activation of different strips disposed across the web, developed by an improved toner fountain assembly and cleared of excess toner by means of improved blade means and then fed simply by pushing the web from one end while flattening the web against the platen or other inclined plane by means of an air stream directed thereagainst so as to minimize problems in tracking the web along its path.
By feeding the web in this manner, the pliable material will remain substantially flutter free as it travels along the platen whereby it can pass readily beneath the upper edge of window 88 so as to be directed out of the discharge opening 89.
This invention pertains to printing machines and more particularly to a toner fountin feature particularly useful in an electrostatic printer of the type where printing is accomplished electrostatically on a moving web of paper.
In a machine for electrostatically recording upon a web of paper or other recording material, several technologies must be brought together in order to produce a high quality, reliable machine. For example, it is necessary to properly feed or advance the paper web through the machine so that it will provide an even, forward movement past the recording station. The electrostatic recording head must cooperate properly with the paper and the paper must be appropriately tensioned while being fed past the head. In addition, this technology calls for skill in the proper application of liquid or powdered toner material for purposes of developing the paper and, finally, it is quite important that the foregoing skills provide an apparatus which is relatively simple so as to be capable of being easily serviced and operated by office personnel using the machine.
According to the present invention, there has been provided an improved toner application fountain which serves to properly develop the paper web whereby an improved printing machine, particularly useful as an electrostatic printing machine, is provided.
SUMMARY OF THE INVENTION AND OBJECTS
In general, there has been provided a printing machine of a type including a length of pliable record material wrapped to form a supply roll and having means for recording information upon the record material, such as paper.
The printing machine, according to the invention, employs means for guiding the web of recording material across the top of a fountain of liquid toner material for developing electrostatically charged parts of the web.
In general, it is an object of the present invention to provide an improved web developing apparatus for an electrostatic printing machine.
It is another object of the invention to provide an improved printing machine having a particularly improved toner system.
The foregoing and other objects of the invention will become more readily apparent from the following detailed description of a preferred embodiment when considered in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view, partially broken away in section, of a printing machine according to the invention;
FIG. 1A is an enlarged detail view, in perspective, showing a recording head according to the invention;
FIG. 2 is a side elevation in enlarged detail of mechanism for adjusting the recording head of FIG. 1A within the printing machine of FIG. 1;
FIG. 3 is a perspective view similar to FIG. 1 but with the cover removed for clarity;
FIG. 4 is a perspective diagrammatic view in simplified form for demonstrating the opening and closing of the top assemblies of the printing machine according to FIG. 1;
FIG. 5 is a side elevation section view taken along the line 5--5 of FIG. 3;
FIG. 6 is a front elevation view in enlarged detail taken along the line 6--6 of FIG. 5 and further schematically including representations of additional means coupled thereto;
FIG. 7 is an enlarged detail view along the line 7--7 of FIG. 8;
FIG. 8 is an enlarged, detail, perspective view, partially broken away for clarity, of a fountain assembly according to the invention;
FIG. 9 is an enlarged section view taken along the line 9--9 of FIG. 8; and
FIG. 10 is a schematic view in perspective diagrammatically illustrating the provision of an air stream for flattening the paper web against a platen as it is pushed from its lower end.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
A printing machine 10 is formed in general as best disclosed diagrammatically in FIG. 4. Machine 10 in general comprises a support base 11 upon which is mounted a lower frame assembly 12. An upper frame assembly 13 is pivotally hinged to lower frame assembly 12 so that it can be raised through an arc 14 for access to components carried by both assemblies 12 and 13. A top cover 16, pivotally hinged at its rear edge to support base 11, can be moved through the arc 17 independently of the movement of upper frame assembly 13.
Briefly, and continuing to refer to FIG. 4, a supply roll 18 of suitable paper for electrostatic recording is rotatably carried between a pair of supports 19, 21 whereby it may be unwound from the near edge (as seen in FIG. 4).
With reference to FIGS. 1, 3 and 5, it will be readily evident that there has been provided on the lower frame assembly 12 means carried by the lower frame assembly which are adapted to support roll 18 for rotation. Thus, lower frame assembly 12 includes a pair of side plates 22, 23 formed with an angled flange 22a, 22b, respectively, attached to the upper end of support base 11. Support base 11 can, for example, constitute the housing for the machine or other suitable stand.
At each end of roll 18, L-shaped support members 24 are attached, as by screws, through the holes formed in the ends of members 24. Each support member includes a pair of support surfaces 24a, 24b (FIG. 5) disposed to form an angle, such as a right angle, therebetween and which is adapted to receive the protruding ends of an X-shaped support 26.
Roll 18 includes, typically, a hollow cylindrical core formed by the cylindrical core element 27 upon which the paper is wrapped by the manufacturer. X-shaped support 26 provides stationary web-restraining means carried within core 27 which simply consists of a pair of elongated planar elements 26a, 26b (FIG. 5) disposed within core element 27. The planar elements 26a, 26b have a width of the order of the inner diameter of core element 27 and are oriented in substantially mutually perpendicular planes.
Support member 26 protrudes beyond the ends of core element 27 and these substantially mutually perpendicular portions of support member 26 define substantially the same angle as defined between the support surfaces 24a, 24b so as to prevent rotation of the X-shaped support member 26 relative to core element 27 as the web 28 of paper is unwound from roll 18 whereby the stationary portion of support member 26 located within core element 27 rubs against the core element thereby imparting modest tension to the web 28 of paper as it is unwound.
Thus, at least one edge of each element 26a, 26b rubs against the interior of core element 27 during unwinding of the roll.
Means are provided for insuring proper lateral registration of web 28 to insure proper tracking of the web. Thus, it is to be observed that a small cylindrical resilient nylon registration button 29, carried tightly gripped by a bracket 31 (formed as a portion of the L-shaped supports 24), rides against the end of core element 27.
As thus arranged, the bottom of frame assembly 12 serves to support a roll 18 of electrostatic recording paper for proper rotation.
A short stretch 32 or web (FIG. 5) extends between roll 18 and a guide roller 33 whereby upon closure of the upper frame assembly 13, a tension rod 34 extending transversely of frame assembly 13 will engage stretch 32 and move it downwardly thereby tensioning the paper.
Web 28 moves through the machine along a predetermined path next including a recording station 36 comprised of an electrostatic recording head 37 and a back-up assembly 38. Head 37 (FIG. 1A) consists essentially of a pair of opposed fiber glass plates 37a, 37b secured together to embed therebetween an array of evenly spaced conductors 39 arranged to protrude slightly on their upper edge to form conductive nibs 39a.
A number of groups of five conductors 39 is coupled in parallel to recording means whereby upon energization, each of the five conductors in the group will be coupled to a voltage source for recording. However, by means of the potential on sections of the back-up assembly 38, only one of the conductors in any activated group of five will be permitted to record upon web 28.
Thus, in general, a recording control assembly on the other side of, or confronting the other surface of, web 28 opposite to the recording surface extends across the path of web 28 in confronting relation to the head 37. The control assembly includes elongated means disposed on the other side of web 28 from head 37 in electrostatic charging relation to web 28, the elongated means being sub-divided into a plurality of electrically discrete sections each selectively operable to block or permit discrete charging of web 28 by those of the nibs or tips 39a opposed to the sections selected.
Accordingly, with reference to FIG. 5 and FIG. 6, there is shown in confronting relation to head 37 a back-up assembly 38 which includes an elongated insulator mounting bar 41 to which there has been secured a number of flat recording control sections 42. Each section 42 is connected as schematically shown in FIG. 6 to a suitable control means 43 responsive to printing inputs on line 44 whereby only those nibs 39a opposite a selected one of the sections 42 will be permitted to print.
Means adjacent the recording control sections 42 have been arranged for applying a voltage to the web 28 to precondition web 28 so as to permit nibs or tips 39a to apply a predetermined recording charge upon web 28. Accordingly, as best shown in FIG. 5, a so-called guard voltage is applied to the web 28 by connections 46, 47 coupled to elongated, flat conductive bars 48, 49 likewise separated from sections 42 by insulating bars 51.
In general, the guard voltage shown only as a plus (+) sign with respect to connections 46, 47 provides a voltage which rises nearly to the level of the writing potential. Sections 42 are controlled by control means 43 whereby they will either provide a voltage on the order of 200 volts so as to be blocking any writing in their immediate area or switched to a writing potential on the order of 600-700 volts.
As thus arranged, writing can be accomplished by coupling a group of nibs 39a in parallel to ground and controlling those sections 42 which are to be raised to the writing potential of 600-700 volts.
Thus, when the five nibs 39a of a given group are coupled in parallel to a given potential, such as ground, writing will occur at only those nibs 39a where the large potential difference between the nib 39a is being presented in the region of a section 42 which has been coupled to the higher writing voltage mentioned above.
As shown best in FIGS. 5, 8 and 9, means for developing the discrete electrostatically recorded portions of web 28 comprise, in general, a supply reservoir 52 (FIG. 1) of liquid toner material coupled to supply liquid toner directly to an elongated inner tray 53 or fountain via the flow passage 54. The fountain tray 53 extends across the path of web 28 and underlies the web slightly to be disposed at a level which will serve to carry the overflowing toner material into contact with the electrostatically recorded discrete portions prepared on web 28 at recording station 36. A portion of the toner material will adhere to the electrostatically charged discrete portions so as to develop them to form a visible image.
A catch basin tray 56 encircles the periphery of fountain tray 53 so as to catch and return the flow of liquid toner via the flow passages 57 whereby the toner may be circulated back to reservoir 52 by means of the pump 58 and fluid connections 59, 61 (FIG. 1). Fluid connections 59, 61 complete a fluid toner supply path defined directly from reservoir 52 to fountain tray 53 and then overflowing into catch basin tray 56 for returning to reservoir 52.
Flow passage 54 includes diffusion screens 55, 60, 65 whereby the fluid flow of toner via fountain tray 53 will be smoothly flowing and contribute to uniform development of the electrostatic image on web 28.
As shown best in FIG. 8, blade means have been disposed to remove excess toner from web 28 and direct it into the catch basin tray for return to reservoir 52.
Accordingly and more particularly, the blade means comprises a pair of elongated, rigid wiper blades 62, 63, of material such as stainless steel, each formed as an L-shaped member to provide an upper lip 62a, 63a respectively (FIG. 7) whereby the upstream lip 62a is slightly inclined upwardly in the downstream direction and the downstream lip 63a is inclined slightly upwardly in the upstream direction.
The lips 62a, 63a extend across the path of web 28 and in spaced relation in a direction along the path whereby each lip or edge of blades 62, 63 is disposed to engage the web after it has passed through the fountain portion of the developing station.
As thus shown in FIGS. 5 and 9, the upper frame assembly carries means at ground potential for urging web 28 to be pressed lightly into engagement with the upper edges of blades 62, 63 and at a predetermined level through the overflowing portion of fountain tray 53.
Thus, a pressure member 64 (FIG. 5) carried by upper frame assembly 13 by suitable means, such as screws 66 or rivets, is disposed to overlay blades 62, 63 and trays 53, 56. Pressure member 64 may be extruded or molded as desired and extends transversely of the path of web 28.
Pressure member 64 includes a number of downwardly depending fingers 67, 68 and 69 serving to cooperate with the upwardly extending portions of the fountain and wiping assembly therebeneath. Accordingly, the lower tips of fingers 67, 68, 69 serve to confine the travel of web 28 so that it passes in close proximity to the top of fountain tray 53 and rides lightly across the wiping lips 62a, 63a while grounded via lead 70 so as to remove any charge from the back of web 28. Accordingly, high voltages are not required to be handled along with their attendant problems of insulation, etc.
Further downstream from the developing station as described immediately above, web 28 is trained about a drive roller 71 carried by upper frame assembly 13 for cooperation with a pinch roller 72 mounted for rotation in lower frame assembly 12. The ends of pinch roller 72 are of larger diameter than the central portion which has been relieved whereby web 28 will be driven by engagement with drive roller 71 along the marginal portions of web 28.
Thus, upon closure of upper frame assembly 13, as by means of the hold down latches 74 operated by a lever 76 for drawing upper frame assembly 13 firmly down to a lower frame assembly 12 by engagement with the latch pins 77, web 28 will be firmly engaged at its margins between drive roller 71 and the enlarged ends of pinch roller 72 to define the drive nip 73 therebetween.
The relieved portion of roller 72 serves to permit the wet toner carried by web 28 to pass upwardly around drive roller 71 without being smeared.
Drive roller 71 is driven by means of the chain drive 78 powered by motor 79 which is carried conveniently in upper frame assembly 13 by virtue of the design herein disclosed. Upper frame assembly 13 also carries a relatively broad, flat platen 81 disposed in an inclined plane. Web 28 is pushed or driven from behind by the nip 73 defined between drive roller 71 and pinch roller 72 at the lower end of platen 81, operating in conjunction with means forming an air stream directed to impinge upon the material of web 28 while web 28 is moving upwardly across platen 81. As thus arranged, web 28 is maintained in a flattened state against platen 81 to prevent buckling thereof during its upward travel.
Accordingly, a blower 82, preferably of filtered air, is schematically shown in FIG. 1 for supplying air via a relatively thin, elongated, flat duct 83 whereby an air stream 84 will be supplied across substantially the full width of the electrostatically recorded portion of web 28. The air stream 84 moves generally upwardly through duct 83 where it is directed by a portion 86 of the top cover assembly 87 (FIG. 1). Portion 86 (FIG. 5) of cover assembly 87 includes a lip portion 86a which serves to direct air stream 84 downwardly against web 28 so as to flatten it against the inclined plane of platen 81.
Cover assembly 87 includes an open window 88 having a width of the order of, or slightly larger than the width of web 28. Cover assembly 87 further includes a discharge opening 89 through which web 28 is discharged at the upper end of its travel across platen 81. The edges of window 88 provide a slight clearance with respect to the surface of platen 81 whereby air stream 84 may escape through the paths 84a, 84b and 84c.
In general, web 28 is fed upwardly by the method of engaging the opposite surfaces of web 28 between a pair of feed rollers at the lower end of the inclined plane 81 so as to push the material of web 28 upwardly while at the same time directing a stream of air 84 against the upper surface of web 28 to flatten it against the inclined plane. In this manner, the pliable material of web 28 can be fed from behind upwardly across an inclined plane and discharged out through the discharge opening 89 without employing feed rollers to engage the upper end of web 28 thereby simplifying the handling of the web. Further, the leading edge of the web readily finds its way between the edge of cover assembly 87 and platen 81.
Finally, alignment of recording head 37 is readily maintained as by disposing it between a pair of adjustment screws 35 disposed on one side (FIG. 2) and a single adjustment screw 40 disposed on the opposite side whereby screw 40 can serve as a pivot point with respect to adjustment of the plane of head 37. Accordingly, once the plane of head 37 is appropriately established, the degree of projection of head 37 from its mounting can readily be adjusted by means of the elongated screw element 45 or reach rod tapered at its end 45a whereby, upon screwing the reach rod 45 into bracket 50, head 37 will be raised as viewed in FIG. 2.
By providing identical head adjustment assemblies of the type shown in FIG. 2 on each end of head 37, it is possible to adjust head 37 in all directions so as to provide improved control over the quality of electrostatic recording achieved across the length of head 37.
With blower 82 supplying the air stream 84 against the upper surface of web 28, drying of the wet toner will be readily achieved as well as a riffle-free upward feeding of pliable paper across platen 81.
In operation, briefly, loading of supply roll 18 has been described above whereby a length of paper is withdrawn from supply roll 18 and laid across the top of the recording head assembly 36 and fountain assembly, while insuring that sufficient paper has been withdrawn to engage the nip defined between rollers 71, 72. Subsequently, the upper frame assembly 13 is lowered into position so as to cause roller 71 to engage roller 72 and then the top cover can be closed to define the air stream 84 to be directed against web 28 as it passes across platen 81.
Subsequently, motor 79 and blower 82 can be started, along with pump 58, so as to advance the paper through the nip 73 defined between rollers 71, 72. The unwinding movement of web 28 from roll 18 tends to advance the axis of rotation of roll 18 to the left as shown in FIG. 5. However, by virtue of the cooperation of the ends of members 26a and 26b with support surfaces 24a and 24b, the axis of rotation of roll 18 will remain substantially stationary once the left edges (as shown in FIG. 5) of members 26a, 26b engage support surface 24a. At that point, core element 27 will be slightly restrained from rotating by rubbing which occurs at the right hand edges of members 26a, 26b engaging the inner circumference of core element 27. This slight restraint serves to tension web 28 properly for feeding and recording.
From the foregoing, it will be readily evident that there has been provided an improved printing machine wherein a roll of paper can be easily loaded, fed along a path including an improved recording head assembly utilizing techniques of selective activation of different strips disposed across the web, developed by an improved toner fountain assembly and cleared of excess toner by means of improved blade means and then fed simply by pushing the web from one end while flattening the web against the platen or other inclined plane by means of an air stream directed thereagainst so as to minimize problems in tracking the web along its path.
By feeding the web in this manner, the pliable material will remain substantially flutter free as it travels along the platen whereby it can pass readily beneath the upper edge of window 88 so as to be directed out of the discharge opening 89.