INK JET PRINTING APPARATUS

Abstract: An ink jet printing system comprising a plurality of ink jet printheads (7) each having a matrix of ink jets (J), each jet comprising a nozzle (9) having an orifice (19) therein for ejection of drops of ink, and a plurality of valves (13), one for each jet, each comprising a magnetic reed (47) and an electrical coil (51) for flexing the reed for opening the valve for discharge of a drop of ink.

Description: Ink Jet Printing Apparatus Background of the Invention This invention relates to ink jet printing systems, and more particularly to ink jet printing apparatus for use in a computer-controlled system of this class. The invention is especially concerned with ink jet printing apparatus for printing on moving surfaces, such as on cartons or boxes being fed forward by a conveyor, and is in the same general field as the apparatus shown in U.S. patents 4,002,230 and 4,378,564. Also, cross-reference is made to the copending coas- signed application of Howard H. Barney, Serial No. 527,479, filed August 29, 1983 (attorneys' file 1482). Summary of the Invention Among the several objects of the invention may be noted the provision of ink jet printing apparatus having elec¬ trically actuated valves controlling delivery of ink to the jets of the system, with these valves having a faster response than solenoid valves, for example, and thereby permitting the use of nozzles for the jets of comparatively larger diameter, in turn permitting the use of faster-drying solvent-based inks; and the provision of such apparatus of compact size. In general, ink jet printing apparatus of this in¬ vention comprises a plurality of ink jets and means mounting the jets in a matrix for non-contact printing of patterns of dots to form characters on a target surface moving past the jets, by selective sguirting of ink from the jets. Each jet comprises a tubular member having a nozzle at one end thereof, said nozzle having an orifice for ejection of drops of ink. Each jet has an electrically actuated valve adapted for opera¬ tion for ejection of a drop of ink from the jet nozzle, each valve comprising an elongate tubular member having an ink in¬ let at one end and an ink outlet at the other and normally closed valve means in said tubular member adapted to be opened briefly for supplying ink to the respective jet for discharge of a drop of ink therefrom. Said valve means comprises a valve body in said tubular member forming an ink chamber in said tubular member and having a laterally facing valve seat in said chamber and a passage from the seat to the ink outlet, and a magnetic reed fixed at one end thereof and extending lengthwise in the tubular member \of the valve seat. The reed has a sealing member thereon adjacent its other and free end engageable with the valve seat for closing it, and is biased for closure of the sealing member on the seat. Magnetic coil means surrounding the tubular member acts on energization to flex the reed in the direction away from the valve seat to open the valve seat for delivery of ink through said passage to the respective jet. Other objects and features will be in part apparent and in part pointed out hereinafter. Brief Description of the Drawings Fig. 1 is a semi-diagrammatic view of an ink print¬ ing system in which apparatus of this invention is used; Fig. 2 is a perspective of a printhead of the appar¬ atus Fig. 3 is a view illustrating a matrix of ink jets of the printhead and pattern of dots printed thereby; Fig. 4 is an exploded view showing certain parts of the apparatus; Fig. 5 is a view of a jet mounting block of the ap- paratus and jets mounted on the block, with one of the jets broken away and shown in section; and Fig. 6 is an enlarged longitudinal section of one of the valves -of the apparatus. Corresponding reference characters indicate corres¬ ponding parts throughout the several views of the drawings. Description of the Preferred Embodiment Referring to Fig. 1, there is indicated at 1 a con- veyor for feeding forward one after another at spaced inter¬ vals a succession of objects 3, such as cartons or boxes, on which messages are to be printed by means of the ink jet printing system designated in its entirety by the reference numeral 5. The term "message" is intended to cover any item of information, such as a product code. The ink jet printing system 5 is shown in Fig. 1 to comprise a plurality of ink jet printheads each designated 7 positioned alongside and adjacent the path of the objects to print the messages on the objects as they travel forward along said path (left to right as viewed in Fig. 1) past the print¬ heads. Three printheads 7 are shown in Fig. 1 by way of exam¬ ple. Each of these comprises a plurality of ink jets each generally denoted by the reference character J and, each in¬ cluding an outlet nozzle 9 (see Figs. 2-5) arranged in " a ma- trix and adapted for ejection of drops of ink across a gap be¬ tween the nozzles and an object 3 travelling past them to a surface S of the object (one side of a carton or box) to print dots on said surface in patterns forming selected characters such as letters, numerals and other symbols for said mes- sages. As shown in Figs. 2 and 3, there are nine ink jets J and hence nine nozzles 9 arranged in two side-by-side closely adjacent columns of five nozzles and four nozzles, respective¬ ly, the four nozzles in the four-nozzle column being staggered with respect to the five nozzles in the five-nozzle column. With this nozzle arrangement, various patterns of dots may be printed on surface S. Fig. 3 shows a pattern of dots for the characters "Al" in what is called a "bold" font (large charac¬ ter printing). At 11 is generally indicated means for supply¬ ing ink to the nozzle. A plurality of electrically actuated valve means, one for each jet J, and each designated 13, is provided in each printhead. One of these is shown in Fig. 6. It will be understood that for the nine jets J of each print¬ head 7, there are nine such valve means 13, one for each jet. Each said valve means 13 is adapted for relatively momentary operation electrically for ejection of a drop of ink from the respective jet nozzle 9 (i.e., the nozzle associated there¬ with). Each of the printheads 7 comprises means indicated generally at 15 mounting the jets.J in the stated matrix for the non-contact printing of patterns of dots to form charac¬ ters including letters, numerals and other symbols on the tar¬ get surface S of the objects 3 moving relative to the jets past the jets, by the selective squirting of ink from the jets on the target surface. Each jet comprises an elongate tubular member 17 having secured in one end thereof constituting its outlet end the aforesaid nozzle 9. The nozzle, per se, is a circular jewel, e.g., sapphire, having a circular central ori¬ fice 19 which may have a diameter in the range from about 0.012 to about 0.015 inch (0.3048 to 0.3810 mm), and which is preferably of a diameter of about .0135 to .0140 inch (0.3429 to 0.3556 mm), mounted in the outlet end of the tubular jet member 17 as shown in Fig. 5. The means 15 mounting the jets J in the stated five-by-four matrix comprises a block having openings 21 in which the jets are inserted to the point where the outlet ends of the jets with the nozzles 9 are at the front of the block, the jets extending rearward from the block. The electrically actuated valves 13 are mounted on oppisite sides of a valve mounting block 23. Each of the valves 13 is a miniature valve of a type sold by Reedex Corporation of Watertown, Massachusetts under the trademark REEDAIR, comprising an elongate tubular member or cylinder 25, of non-magnetic material, e.g., plastic, hav- ing an ink inlet 27 at one end and an ink outlet 29 at its other end. In the cylinder 25 is an elongate valve body 31 of non-magnetic material formed to provide an ink chamber 33 in the cylinder in communication with the ink inlet 27 for re¬ ceiving and holding ink under pressure. The valve body 31, which extends from end to end in the cylinder, has a flat side indicated at 35 forming the chamber 33 with a recess 37 in this side. The recess is located toward the outlet end of the valve, terminating somewhat short of the outlet end of the valve body so that the latter has a relatively long flat 39 between its inlet end and the recess end and a relatively short flat 41 at the end of the recess toward the outlet end of the valve body. A valve seat 43 extends up from the bottom of the recess in communication with the ink chamber 33 and with a passage 45 in the body extending to the outlet 29. The orifice in this seat, indicated at 46, may have a diameter of about 0.024 inch. A magnetic leaf spring member or reed 47 is fixed at one end (toward the outlet end of the valve) on the short flat 41 extending lengthwise of the valve body over the recess and over the valve seat. The latter faces laterally toward one side of the cylinder 25. The reed 47 has a sealing member 49 constituted by a small elastomeric disk secured thereto adjacent its free end engageable with the seat 43 for normally closing the sealing member on the seat. Magnetic coil means indicated at 51 surrounds the cylinder 25, and acts on energization thereof to flex the reed 47 in the direction away from the valve seat 43 to open the latter for delivery of ink through the seat to the passage 45 for discharge of a drop of ink from the respective jet J. Opening flexure of the reed 47 is limited by engagement of a downturned tip 53 of the reed with the end of fixed magnetic •reed 55 secured on the long flat 39 and projecting therefrom over the tip 53 of reed. Each valve 13 further comprises a housing 57, more particularly a plastic housing, for the cylinder 25. With regard to the valves being a "miniature" valve, this housing may be generally 13/4 inch long by 9/16 inch square. Five of the nine valves are mounted on one side of the valve mounting block 23 in the printhead 7, the remaining four being mounted on the other side of the block. The valves are mounted on the block by means of screws 61 extending through holes in mount¬ ing flanges 63 at the ends of the housing 57. The valve in¬ lets 27 extend out of the one end of the housing and are sup¬ plied with ink under pressure from an air-pressurized ink sup¬ ply bottle 133 at the ink supply means 11 via a line 141 to a first manifold 67 having four outlets 69 connected by lines 71 to the inlets 27 of the four valves 13 on one side of block 23 and a fifth outlet connected to a second manifold 73 as indi¬ cated at 75, the second manifold having five outlets 77 con¬ nected by lines 79 to the inlets 27 of the five valves 13 on the other side of the block. The outlets 29 of the valves 13 extend through the other ends of the housings 57 and are con¬ nected to the jets J by lines such as indicated at 81. The system 5, apart from the jets J and valves 13, is similar to that shown in the aforesaid Barney application Serial No. , comprising a plurality of control modules or controllers 93, one for each printhead, a controller 99, also referred to as the console or message bank, for the sev¬ eral printhead controllers 93, and a terminal 109 for entering data for messages. Data for a plurality of messages typed by means of keyboard 111 of the terminal is stored in the bank 99. The printhead controller 93 for each printhead 7 is pro¬ grammed for controlling the valves 13 of that printhead to print a selected message by routing the date for that message form the bank 99 to that controller. Start of printing by each printhead is controlled by photocell means indicated at .159 which senses passage of an object 3. In operation, the coils 51 of the valves 13 of a printhead 7 are momentarily energized by the printhead con¬ troller 93 to open the valve seat orifices 46 for ejection of drops of ink form the nozzles 9 on the moving target surface S of each object 3 travelling past the printhead in a sequence to print the pattern of data for the message programmed in the printhead controller. The valves 13, acting via flexing of the reeds 47 on energization of the coils 51, are fast-acting and the fast action permits the use of jet nozzles 9 with jet orifices 19 of relatively large diameter (0.012 to 0.015 inch diameter and preferably 0.0135 to 0.0140 inch) in comparison with usual jets. In view of the above, it will be seen that the sev- eral objects of the invention are " achieved and other advanta¬ geous results attained. As various changes could be made in the above con¬ structions without departing from the scope of the invention, it is intended that all matter contained in the above descrip- tion or shown in the accompanying drawings shall be interpre¬ ted as illustrative and not in a limiting sense.

Claims: Claims WHAT IS CLAIMED IS: 1. Ink jet printing apparatus comprising: a plurality of ink jets, means mounting the jets in a matrix for non-contact printing of patterns of dots to form characters on a target surface moving past the jets, by selective squirting of ink from the jets, each jet comprising a tubular member having a nozzle at one end thereof, said nozzle having an orifice for ejection of drops of ink, a plurality of electrically actuated valves, one for each jet, each adapted for operation for ejection of a drop of ink from the respective nozzle, each valve comprising an elongate tubular member having an ink inlet at one end and an ink outlet at the other, normally closed valve means in said tubular member adapted to be opened briefly for supplying ink to the respective jet for discharge of a drop of ink therefrom, said valve means comprising a valve body in said tubular mem¬ ber forming an ink chamber in said tubular member and having a laterally facing valve seat in said chamber and a passage from the seat to the ink outlet, a magnetic reed fixed at one end thereof and extending length¬ wise in the tubular member over the valve seat. said reed having a sealing member thereon adjacent its other and free end engageable with the valve seat for closing it, said reed being biased for closure of the sealing member on the seat , and magnetic coil means surrounding the tubular member , said mag¬ netic coil means , on energization , acting to flex the reed in the direction away from the valve seat to open the valve seat for delivery of ink through said 'passage to the respective jet . 2. Ink jet printing apparatus as set forth in claim 1 wherein the nozzle orifice has a diameter in the range from about 0.012 to about 0.015 inch. 3. Ink jet pr inting apparatus as set forth in claim 1 wherein the nozzle orifice has a diameter in the range from about 0.0135 to about 0.0140 inch . 4. Ink jet printing apparatus as set forth in claim 1 wherein the nozzle is a jewel having a diameter in the range from about 0.012 to about 0.015 inch. 5. Ink jet pr inting apparatus as set forth in claim 1 wherein the nozzle is a jewel having a diameter in the range from about 0.0135 to about 0.0140 inch.

Inventors: BARNEY HOWARD H, DROIT JAMES L, BARNEY, HOWARD, H., DROIT, JAMES, L.
Applicants: DIAGRAPH CORP, DIAGRAPH CORPORATION
Application year: 1984
Main classification: G01D15
IPC codes: B41J2