PRESSURIZING SYSTEM FOR INK JET PRINTING APPARATUS
REFERENCES OF INTEREST
The following IBM Customer Engineering Manuals are of interest:
"Selectric Printer Instruction Manual", January, 1966, Form No. 241-5032-2.
"Selectric" Typewriter, November, 1970, Form No. 10 241-5615-0.
"Selectric" Typewriter Service Manual Supplement, Form No. 241-5615-0 (Supplement).
BACKGROUND OF THE INVENTION AND PRIOR . * ART
Ink jet printing apparatus prior to this time has ordinarily incorporated nozzle assemblies and pumping and ink supply members as completely separate and independent structures. This has required the use of lengthy 20 conduits or hoses, additional hardware, and more careful control of parameters such as pressure, temperature, and the like.
SUMMARY OF THE INVENTION 25
In accordance with the present case, an ink jet printing apparatus has a nozzle assembly mounted on a carrier for relative movement in relation to a document to be printed. Integrally formed with the carrier are a pump and ink supply that are relatively movable along 30 with the nozzle assembly. The arrangement results in a compact, efficient structure and provides for required adjustments such as those pertaining to the jet stream itself and the relationship of the pressurizing system to the charging coil and deflection plates as well as adjust- 35 ment of stream angle relative to the paper. This insures improved print quality and reduces maintenance requirements. Other aspects of the system are the elimination of flexible hose connctions, facilitation of automatic cleaning of the nozzle orifice and ink pressure 40 chamber without contamination or dilution of ink in the supply tubes, and ability to cut the ink jet stream off and on automatially at the end of each line or after any character in a line, if a delay in printing is expected. An ability to cap and uncap the ink jet nozzle may be pro- 45 vided. The elimination of ink at relatively high pressure in flexible tubes reduces greatly the possibility of ink being sprayed on the operator of the apparatus. It also establishes a more constant pressure since flexible hoses required to flex during carrier movement lead to pressure fluctuations. These in turn affect printing quality.
A primary object of the present invention is to pro- 55 vide a pressurizing system for an ink jet printing apparatus in which all elements of the system are integrated with the ink jet nozzle for a more efficient and reliable operation. 60
The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the preferred embodiment of the invention as illustrated in the accompanying drawings. 65
In the Drawings:
FIG. 1 is a block diagram of an ink jet printing apparatus incorporating pressurizing systems in accordance with the present invention.
FIG. 2 is a perspective view of an ink jet printer incorporating the pressurizing and printing systems on a movable carrier.
FIGS. 3a and 3b when combined as shown in FIG. 3 represent an exploded view of the pump and ink supply structures previously discussed in connection with FIGS. 1 and 2.
FIGS. 4a and 4b respectively represent a top elevation and a side elevation of the nozzle, ink supply, and pressurizing systems in relation to a document platen in the printer of FIG. 2.
FIGS. 5a, Sb, and 5c are elevational views of various kinds, illustrating electromagnetic actuating means and associated linkages for controlling the pumping structures of FIGS. 3a, 3b, 4a, and 4b.
Various elements concerned with the pressurizing system including the pump, ink supply, and nozzzle structures are designated by reference numerals 1-176 in the detailed drawings of FIGS. 3a, 3b, 4a, 4b, Sa-5c. For this reason, reference numerals in FIGS. 1 and 2 are predominately in the "200" Series.
FIG. 1 is a block diagram of an ink jet printing apparatus incorporating a nozzzle assembly 201, a crystal 105, nozzle 115, charge electrode 135, deflection plates 205a and 205b, and having an associated ink supply 55 with pump 208. Nozzle assembly 201 is positioned for formation, propulsion, charging, and deflection of drops in a stream 210 toward a document 212 to be printed. As is known in the art, drops are formed by vibration of crystal 105 under control of crystal driver 213 and are propelled from nozzle 201. Drops are variably charged by charge electrode 135 under control of charge electrode driver 214 which in turn is controlled by the sync control box 216 in accordance with characters from character generator 218. Other elements of the system include the master clock 220 that provides master pulses for determining machine operation, and a machine logic block 221 for controlling the various processes of the apparatus. Following charging of individual drops, they are deflected by means of a potential from terminal 222 applied across plates 205a and 2056 in accordance with the strength of the charge placed on the drops by electrode 135. Any drops not required for printing such as drops 2106 are directed to a gutter 165. Other drops, such as drops 210a required for printing are directed along various paths to document 212. Drops landing in gutter 165 are returned to ink supply 55 and conduit 227 for recirculation through the system.
If desired, currents generated in gutter 165 as a result of the drops passing therethrough can be used to determine synchronization following amplification by amplifier 230 comparision by comparator circuit 231 with a reference voltage from source 232 and application of a correction signal on line 233 to sync control 216.
A printer unit 235 shown in more detail in FIG. 2 includes the customary keyboard 236 and various other controls found in a printer such as the IBM "Selectric" printer described in the various customer engineering manuals referred to previously. Nozzle assembly 201 is mounted adjacent a platen 242 on which document 212 is positioned for printing. Nozzle assembly 201 is