Method and apparatus for rewiring corona wire cartridge

#This invention relates to corona wire cartridges of the type used on photocopiers, laser printers and the like, and more particularly, to a method and apparatus for replacing a worn or broken corona wire on such cartridges while utilizing the original equipment cartridge framework.

#Existing corona wire cartridges are disclosed at U.S. Pat. Nos. 4,626,701; 3,499,143; 4,754,305; and 4,864,363. The "701" patent discloses a corona wire cartridge sold under the trademark Canon wherein the corona wire is suspended across an elongate opening in the cartridge and permanently mounted on the opposing ends of the cartridge by rivets. Tension is placed on the corona wire by means of a pair of rollers also mounted on each end of the cartridge which press on the corona wire when installed. The "363" patent discloses a corona wire cartridge sold under the trademark Ricoh, wherein the cartridge includes a post-type mounting and the corona wire includes a metal eyelet at one end which is mounted on one post, and a coil tension spring mounted on the opposing post. A loop end of the coil spring is a retainer for an opposing looped end of the corona wire.

#At the present time, maintenance persons in the field, by and large, replace entire corona wire cartridges when the wire ceases to function properly, that is, when it is corroded or breaks. As an alternative to replacing an entire corona wire cartridge, maintenance repair people have been supplied with coils of tungsten wire which, if they desire and have the sufficient technical knowledge and ability, may be cut to proper lengths and hand fitted to old cartridges. To date, hand made corona wire replacements made from long coils of tungsten wires have, in the main, proven not as satisfactory as replacing the entire corona wire cartridge.

#The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following detailed description taken in conjunction with the accompanying sheets of drawings, in the several features of which like reference numerals identify like elements, and in which:

#FIG. 1 is a bottom plan view of a Canon SX type corona wire cartridge as shown with its roller mountings removed disclosing the permanently mounted original equipment corona wire therein;

#FIG. 2 is a fragmentary detailed view showing the removal of one of the permanent rivets shown in the cartridge of FIG. 1;

#Referring to FIGS. 1 and 2, a corona wire cartridge such as sold under the trademark Canon and model designation SX is shown at 10 and includes a frame 11 having a pair of elongate parallel, spaced frame rails 12, 13, and opposed end mountings 14, 15 which are positioned between the frame rails 12, 13 to define an elongate hollow interior of said cartridge 10.

#Left end mounting 14 includes a boss or solid block 16 having a hole 17 therein in which a rivet 18 is forceably retained. Likewise right end mounting 15 includes a boss or solid block 20 having a hole therein (not shown) in which a rivet 21 is forceably retained. Right side end mounting 15 also includes an electrically conducting contact spring 22 which may be biased against the top of rivet 21 or, in some cases not shown, retained between the head of the rivet and block 20. An original equipment corona wire 23 is forceably retained between each rivet and its mounting boss so as to extend across the middle of the hollow area parallel to and in between the frame rails 12, 13.

#Referring to FIG. 5, a first embodiment of a corona wire retrofit assembly, generally indicated at 30, is shown mounted in a Canon SX cartridge frame 31 which is identical to the frame 11 of FIG. 1. The first embodiment of a retrofit assembly 30 includes opposed terminals 32, 33, each having a base end 34, 35, respectively, an aperture 36, 37, respectively, through which rivets 36a, 37a, respectively, are retained. Each terminal 32, 33 further includes a hook end 38, 39, respectively.