Printing Apparatus

Abstract

A printing system wherein the printing element is included in a rotating member and which selectively records, through a suitable material transfer, information onto a suitable medium which is driven past the rotating member. The medium is, preferably, a continuous form which is arranged to conform to at least a portion of the peripheral configuration of the rotating member.

Description

BACKGROUND

There are known in the art many types of printing devices. A printing apparatus or device typically includes a first element which produces the material transfer onto the appropriate medium and another element for positioning the medium. In one type of material transfer or printer such as discussed herein, an ink spritzer or ink sprayer is the device which is utilized to provide the material transfer. In this case, the ink spritzer may be a piezoelectrically controlled jet or the like such as is shown and described in U.S. Pat. No. 2,512,743 to C. W. Hansell entitled "Jet Sprayer Actuated by Supersonic Waves. Many other types of ink spritzers or sprayers or jets or the like are known in the art. The cited patent is only one illustrative reference.

Normally, this type of ink spritzer is positioned adjacent to a rotating drum upon which a suitable medium such as a sheet of paper or the like has been mounted. The drum, with the medium attached, rotates past the ink spritzer within a line, a series of dots or the like is transferred from the spritzer to the paper. That is, the information is printed or recorded on the medium in accordance with emission of ink from the spritzer in response to control signals which are supplied to the spritzer. In addition, the drum and the ink spritzer move relative one to the other in a longitudinal or axial direction. A relatively helical path of transferred ink (or other material) is, thus, produced on the recording medium. In some devices, the ink spritzer is mounted on a lead screw or the like and is driven axially along the length of the cylinder defined by the medium and the drum. Conversely, the ink spritzer may be fixed and the drum may be driven by a lead screw on the axis thereof.

This type of material transfer or non-impact printing technique is becoming more desirable and advantageous in many printing applications. For example, this type of printing is generally significantly quieter than the standard impact printing operation which is encountered in many operations such as computer printers and the like. Moreover, as the techniques for providing ink jets and the controllers for the spritzers are improved, the speed of operation, as well as the definition and resolution of the transferred images, are vastly improved. It should be understood that the material transfer type of printing also includes processes wherein a laser beam is utilized to transfer material to a recording medium. This type of material transfer is described in a U.S. Pat. application entitled "Laser Writing" by R. S. Braudy, bearing Ser. No. 779,865 and assigned to the common assignee.

Also known in the art are many reproduction type machines wherein the recording medium is a continuous strip of material such as a roll of paper which is selectively cut or separated as a part of the operation of the machine. However, in these machines, the apparatus or operation normally utilizes a specially treated paper to which an image is applied on a frame-by-frame (or page-by-page) basis. That is, the paper is moved to a particular position, an image is focused thereupon and the paper is subsequently moved so that another image can be focused on another paper sheet or area. This operation, similar to the operation of the apparatus described supra, is relatively slow insofar as a single sheet must be positioned, imaged, perhaps developed and removed prior to the application of the next image. Thus, the operation of this type of apparatus and device is constrained by the time duration required for manipulating or handling the recording medium.

In other systems, the continuous recording medium (e.g., paper) is formed into a cylindrical shape. However, in these systems, the paper is subjected to undesirable stresses of tension and/or compression unless an extremely long distance is used for the forming procedure. In this condition, the apparatus becomes large and bulky.

SUMMARY OF THE INVENTION

This invention relates to a material transfer or non-impact printing apparatus. A rotating member includes means for causing material to be transferred to a recording medium. The rotating member is adapted to form a cartridge line element in order to be readily maintained or replaced. Control signals for controlling the operation of the material transferring means on the rotating device are supplied thereto. In addition, a continuous recording medium is driven past the rotating device. The recording medium may preferably be shaped to conform with a portion of the peripheral configuration and dimension of the rotating device in order to establish a substantially constant distance between the rotating device and the recording medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of the invention.

FIG. 2 is a top view of a portion of the embodiment shown in FIG. 1.

FIG. 3 is a side view of a portion of the embodiment shown in FIG. 1.

FIG. 4 is a cross-sectional view taken in the direction of the side view shown in FIG. 3 and showing a modification of the embodiment shown therein .

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following description, the same reference numeral is used in conjunction with similar components in each of the drawings.

Referring now to FIG. 1, there is shown a perspective view of one embodiment of the instant invention. This perspective view is partially in block diagram and partially in schematic or symbolic representation. Signal generating device 11 may be any suitable source of electrical signals such as a local or a remote scanner. Alternatively, signal generator device 11 may be a computer or data processing unit which produces synthesized signals. The signals provided by signal generating device 11 may partly represent signals produced by a camera or the like, which signals represent an image which is to be transferred or produced by the subject device.

Signal generator device 11 is connected through suitable means to control means 12. Control means 12 includes electronic (or other suitable) circuitry which operates upon the signals produced by signal generator device 11 and produces output signals which are utilizable by the system. In this embodiment, the output signals from control means 12 are supplied along the output lines to slip rings 21 on a shaft 24 which is associated with a motor or similar drive element 13. A suitable disc 20 is mounted on the free end of shaft 24 and affixed to the shaft by any suitable connection structure. For instance, the connection structure may include cap 22. Cap 22 may be a plug-in unit, integrally formed with disc 20, or a separate cap which mates with shaft 24 in a secure fashion to hold disc 20 at the end of shaft 24. Other suitable connection structures may include a press fitted or threaded connection structure located at the bottom of disc 20. In one embodiment, the connection structure is adapted to allow disc 20 to be readily removed from shaft 24 for eash in maintenance or replacement.

Disc 20 is fabricated of any suitable type material which is a function of the utilization and operation by the user thereof. For example, disc 20 may be a rigid unit or a flexible unit which becomes essentially rigidized as a result of centrifugal action when shaft 24 rotates and drives disc 20 at a high rate of rotation. In one embodiment, an ink reservoir is included within disc 20, in the form, for example, of a suitable cavity 20a in the disc 20 with a suitable communication path. A suitable ink jet 23 or the like is affixed at the outer periphery of circumference of disc 20.

A typical suitable ink jet is described in the aforementioned Hansell patent. In fact, a plurality of similar jets 23 may be arranged around the circumference of the disc 20. An appropriate connection 25 is made to jet 23 for instance through cap 22. This connection 25 permits the signals which are applied to slip rings 21 to be supplied to jet 23 to cause operation or action thereof. Thus, disc 20 represents a cartridge-like element for ease in maintenance or replacement. In the alternative, the jets 23 and associated reservoirs may be replacable as individual units.

As is well known in the art, ink jets of the type that generate ink drops on demand are susceptible to malfunction due to the occurrence of air bubbles near the output orifice 32 of the ink jet 23 resulting from the intake of air after a drop of ink has been ejected. When this occurs, the bubble must be cleared and preferably cleared automatically. There are known in the art ink jet devices which include structure forming a fluidic rectifier placed near the output orifice of the ink jet which tend to prevent the ingestion of air bubbles. Although these fluidic rectifiers are imperfect they mitigate the problem, but generally do not entirely prevent air bubbles to a degree necessary in some printing applications. It will be appreciated by those skilled in the art that air bubbles will not affect the reliable and continuous operation of ink jet 23 according to the present invention because of the advantageous utilization of the inherent pressure gradient established in the ink within cavity 20a by the centrifugal forces acting on the ink as disc 20 is rotationally driven by shaft 24. That is, since the pressure is greater at the periphery 36 of cavity 20a than it is near the center of cavity 20a due to the centrifugal force acting on the ink within cavity 20a, any bubbles that may be formed by the operation of ink jet 23 are urged to the center of cavity 20a and away from ink jet 23. Thus, the inherent pressure gradient due to centrifugal force set up within cavity 20a prevents bubbles from impeding the flow of ink to ink jet 23.

It should be noted that as the ink in cavity 20a is ejected by ink jets 23, a void is created within the ink. The void thus created tends to be established in the center of the disc 20 due to the pressure gradient established by the centrifugal forces acting on the ink. The pressure in the void is low, and in some cases, approaches that of vacuum pressure. As the ink is further depleted, the lowered pressure in the increasing void tends to retard the flow of ink to ink jets 23. To obviate this difficulty, various embodiments of disc 20 are provided so that the pressure of disc 20 can act on the ink within cavity 20a to counteract the retarding effect of the low pressure void. In one such embodiment of disc 20, cap 22 is adapted to act as a valve to allow the pressure external to disc 20 to act on the ink within cavity 20a while preventing the ink from leaking from disc 20.

In another embodiment as shown in FIG. 4, to obviate or prevent the retarding effect of the low pressure void in the ink, the top portion 29 of disc 20 is provided with orifices 27 serving as vents to allow the pressure outside disc 20 to act on the ink within cavity 20a. To prevent the ink from leaking or spilling from disc 20, membrane 28, formed of any suitable material such as a readily flexible plastic material, is provided to cover the ink within cavity 20a. As the ink is depleted through orifice 32 of jet 23, the ambient pressure external to disc 20a acts on the membrane 28, forcing it downward (as indicated in phantom) to thereby urge the ink radially outward toward jets 23. For simplicity of construction top portion 29 of disc 20 may be deleted.

In the embodiment illustrated in FIG. 4, disc 20 is affixed to shaft 24 by a press fitted connection structure 30. Connections 25 are embedded in shaft 24 and the bottom of disc 20 with provisions for making electrical connection at the interface of shaft 24 and disc 20. A suitable passageway 34 is provided preferably positioned at the bottom of the cavity 20a, to provide a communication passage for ink from cavity 20a to jet 23.

It should be appreciated by those skilled in the art that other embodiments, according to the invention, are possible to obviate the retarding effect created by the low pressure void in the ink as the ink is used and the embodiments described are only illustrative and are not intended to limit the scope of the invention.

Paper roll 14 is mounted in case 10 in a suitable mounting arrangement. Drive roller 16 is held in contact with the surface of roll 14 by means of spring 17. A suitable driving device such as a motor 15 drives rollers 16. Motor 15 preferably is a constant speed device and since drive roller 16 is maintained in contact with paper roll 14, paper 19 is driven at a constant velocity. Moreover, paper 19 is driven through "flume" 18 which terminates in edge 18A as described hereinafter. Flume 18 is designed so as to receive paper 19 in a relatively straight line configuration from roll 14 and to curve the paper into an arcuate configuration. That is, adjacent disc 20, flume 18 is essentially arcuate (i.e., generally less than 180.degree.) whereby paper 19 is conformed to this configuration as well. Thus, paper 19 is driven by roller 16 past the circumferential edge of disc 20 in a substantially arcuate configuration. In particular, paper 19 substantially conforms to the circumferential configuration and dimension of at least a portion of disc 20. This configuration of flume 18 causes the paper 19 to be maintained at a constant distance from the periphery of disc 20.

As indicated above, the signals produced by control means 12 are supplied to slip rings 21 and, through a suitable connection, to cap 22. For example, the slip rings may be connected to cap 22 via plated wires or printed conductors on the surface (outside or inside) of shaft 24 which mate with suitable connecting pins or the like in cap 22. Alternatively, shaft 24 may be a nonrotating cylindrical sleeve whereby conductors may be connected directly therealong from control means 12 to cap 22 without slip rings. In this alternative, the shaft for driving disc 20 would be located internally of the cylindrical sleeve member 24 and driven by motor 13. Of course shaft 24 may be substantially eliminated by using an edge-driven disc and motor arrangement.

The signals supplied by control means 12, and applied to ink jet 23 have an appropriate amplitude and duration to effect the operation of the jet and to influence the rate of ink expelled therefrom. For example, if a jet similar to those known in the art is utilized, the signal along line 25 may cause a piezoelectric, electromagnetic or similar element to eject ink or similar fluid or material from jet 23. This ink would be deposited on paper 19 in a controlled fashion and thereby produce an image on paper 19.

For each pass made by jet 23 past paper 19 (i.e., each revolution of disc 20) a line or row of dots of ink or similar transfer occurs as controlled by the signals supplied by control means 12. Meanwhile, drive roller 16 is driving paper 19 past the edge of disc 20 at a constant speed. Consequently, a substantially helical path of ink or ink drops is made on paper 19. It should be apparent that if the speeds of paper 19 and disc 22 are properly selected relative to each other, the ink path on paper 19 will be substantially a straight line to normal visual observation.

Referring now to FIG. 2, there is shown a top view of a portion of the apparatus shown in FIG. 1. Again, cap 22 represents the central portion of disc 20 and is utilized to maintain disc 20 in contact with the drive means (not shown). In the apparatus shown in FIG. 2, a plurality of jets 23 is placed around the circumference of disc 20. Each of the jets is electrically connected to cap 22 via the associated connection line 25. Paper 19 is maintained in the arcuate configuration by flume 18. Flume 18 includes folded over edge members 26 which retain paper 19 within flume 18. It should be noted that in the device shown in FIG. 2, each of the jets 23 may be slightly different from each of the others. That is, each of the jets may have included, in the associated reservoir, suitably formed in separate compartments within cavity 20a, a different color ink (or other liquid or material) which is to be transferred to paper 19. Conversely, each of the jets may have different transferring capabilities. for example the capability of supplying different rates of fluid to paper 19. That is, different line width or density can be produced by jets having different transfer capabilities and capacities. For example, if the jets each have a different size orifice, the lines produced thereby will be of different width or density. This characteristic permits the implementation of extended halftone or gray scale gradations. It will be appreciated that halftone control may be effected in each jet by controlling either the size or spacing of individual ink drops transferred to the recording paper. These gradations are respectively termed "amplitude modulation" (size) and "frequency modulation" (spacing) of the ink transfer control or metering. Thus, by utilizing a suitable member of jets which can be controlled by control means 12, a multicolor image having extensive halftone variations can be relatively easily produced.

Referring to FIG. 3, there is shown a side view of a portion of the device shown in FIGS. 1 and 2. FIG. 3 more clearly shows the relationships between flume 18, paper roll 14 and drive roller 16. That is, in this embodiment, drive roller 16 is maintained in contact with paper roll 14 and drives paper 19 through the flume 18. Also, suggested by the dashed line portion thereof, is the relative position of disc 20 within the arcuate portion of flume 18. Moreover, while not required, the top edge 18A of flume 18 may be relatively sharp or serrated whereby paper 19 may be easily torn off by the user manually pulling the paper across the cutting edge 18A.

Thus, there has been shown and described a system or apparatus for generating full color images with ink on paper in response to electrical signals generated from a suitable control source. This apparatus permits a desirably formed, continuous recording medium to be driven past a controllable material transfer element whereby the inherent advantages of the continuous recording medium are achieved in an extremely small, compact unit. The embodiments shown and described above are intended to be illustrative only and are not limitative of the invention. Changes which occur to those skilled in the art are intended to be included in this description. For example, motor 13 and motor 15 may be replaced by a single drive unit which drives both the disc and the recording medium. The scope of the invention is limited only by the appended claims.

Claims

What is claimed is:

1. A printing apparatus wherein ink is deposited onto a recording medium in response to electrical control signals comprising:

a shaft;

means for rotatably driving said shaft about its axis;

a circular disc member coaxially and replaceably mounted on said shaft to be rotated by said shaft;

an electrically operable metering ink jet mounted at the periphery of said disc member for directing jets of ink drops radially outward from said disc, said ink jet being of the type susceptible to the formation of bubbles;

said disc member being arranged to serve as a replaceable ink cartridge wherein said disc member includes a cavity extending substantially throughout said disc member and located generally radially inward from said ink jet, said cavity forming an ink reservoir for storing said ink within said disc member and adapted to supply ink to said ink jet;

said bubbles being urged radially inward in response to a pressure gradient established by centrifugal forces acting on said ink when said disc member is rotated;

means responsive to said electrical control signals for controlling said ink jets to provide jets of ink drops in accordance with the information manifested by said signals;

a warped surface guide member formed of a warped surface having a straight line portion at one end and a curved line portion at the opposite end, said curved line portion of said guide member being conformed to the circular periphery of said disc member and proximate therefrom;

means for driving said recording medium contiguously through said guide member over said straight line portion to egress over said curved portion conforming said recording medium to the warped surface of said guide member as said recording medium is guided past the circular periphery of said disc member.

2. The printing apparatus recited in claim 1 wherein said ink jet control means includes slip rings mounted on said shaft.

3. The printing apparatus recited in claim 1 wherein said ink jet includes piezoelectric means responsive to said electrical signals for metering said ink.

4. The printing apparatus recited in claim 1 including a plurality of said ink jets, said cavity within said disc member including a plurality of associated ink reservoirs, each reservoir being adapted to supply ink of a different selected color to its associated ink jet.

5. The printing apparatus recited in claim 1 including venting means for equalizing the pressure in said cavity to that of the ambient pressure outside of said cavity.