Ink jet printer assembly and alignment of printer components

#The present invention relates to ink jet printers and, more particularly, to a printer configuration which provides simple, accurate assembly and alignment of printer component elements. Ink jet printers of the type to which the present invention is directed generally comprise an orifice plate for forming one or more rows of liquid jets and a charge electrode plate provided with a series of charge electrode openings, aligned with the jets, for selectively charging fluid drops formed by the jets during formation of the drops. Such a printer also typically includes a deflection electrode arrangement for deflecting drops charged by the charge rings, and a catcher arrangement for catching drops which are so deflected. Non-deflected drops are deposited upon a moving print medium which is transported below the printer.

#Ink jet printers of the above described type are inherently capable of high speed, high resolution printing, but have required close tolerance manufacture of printer elements and precise assembly of these elements. After use of such a printer for a substantial period of time, erosion of the orifice plate may occur and contaminants may be deposited in the fluid supply system. Accordingly, it may be necessary to disassemble the printer periodically for refurbishing the fluid supply system and thereafter reassembling the printer with the charge electrode apertures in precise alignment with the jet forming orifices in the orifice plate. Additionally, the deflection electrode arrangement and the catcher configuration may need to be cleaned or refurbished from time to time and these printer elements must thereafter be realigned precisely with the other elements of the printer. In the past, this has been a somewhat tedious process which is difficult for unskilled or semi-skilled operating personnel in a normal printing environment.

#A typical printer arrangement is shown in U.S. Pat. No. 3,701,998, issued Oct. 31, 1972, to Mathis. The Mathis patent discloses a print head providing two rows of jets which is capable of solid print coverage across a print receiving web. Since the Mathis printer contemplates an extremely large number of very small diameter jets, providing a high level of resolution, accurate alignment between the orifice plate and the charge electrode plate in such a printer is critical.

#FIG. 1 is an exploded perspective view, with portions broken away, showing the ink jet printer of the present invention;

#FIG. 2 is an end view of the printer with portions in section as seen looking generally from right to left in FIG. 1;

#FIG. 3 is a front view of the print head means, the charge electrode plate, and the locating plate means, with portions broken away and in section;

#Reference is made to FIG. 1, an exploded perspective view with portions broken away, which illustrates the ink jet printer of the present invention. A locating plate means 20 defines a plate receiving recess 22 and an opening 24 within the recess 22 which extends completely through the plate 20. Charge electrode plate 26 is positioned in locating recess 22 and defines a plurality of electrode openings 28 therethrough which are lined with electrically conductive charge electrodes. Electrode openings 28 are positioned along a pair of parallel rows.

#Print data conductors 30, connected electrically to charge electrodes 28, supply charge control signals to the charge electrodes 28 from print control circuitry 32 which is mounted on circuit boards 34 in cabinets 36. Print data conductors 30 may take the form of flat conductor cables, each of which includes a plurality of conductors. The conductors 30 are connected to associated printed circuit conductors on the charge electrode plate 26, with each printed circuit conductor providing connection to a respective one of the charge electrodes 28. Cabinets 36 are mounted on the exterior of printer cabinet 38, with the conductors 30 extending through slots 40 therein. Baffles 42 cover the conductors 30 as they extend down the inner walls of cabinet 38. Spacer bars 44 extend between the side walls of cabinet 38 and provide structural support therefor.

#A print head means 46 defines a fluid receiving reservoir 48 (FIG. 4) and includes an orifice plate 50 communicating therewith. Orifice plate 50 defines a plurality of orifices 52 which communicate with the reservoir 48 and through which fluid jet drop streams emerge during operation of the printer. As seen in FIG. 5, the orifices 52 are positioned along a pair of parallel rows. When the printer is properly assembled, the rows of orifices 52 are in substantial registration with the rows of electrode openings 28 such that the drops in the jet drop streams emerging from the orifices 52 are selectively charged by the charge control signals applied to the electrodes 28 as the drop streams pass through the respective electrode openings.