Photoreceptor drum keeper blade improvement

#This invention relates to solving problems on photoreceptor drum keeper blades used in Xerography and more specifically in the toner cartridge remanufacturing industry. This includes copiers, laser printers and facsimile machines which will be referred to throughout this text as imaging machines. However, it should be noted that the scope of this invention is not limited to imaging machines that use toner cartridges but includes all dry toner copiers, laser printers and facsimile machines.

#CANON has designed an all-in-one cartridge as seen in U.S. Pat. No. 4,975,744, issued Dec. 4, 1990 and assigned to CANON. Several companies have used these cartridges in laser printers, copy machines and facsimile machines, each with the varying printer engines and a different nameplate. Originally, these cartridges were designed to be "disposable". However, after the first all-in-one toner cartridge was introduced, it did not take long before laser cartridge remanufacturers such as myself began remanufacturing these cartridges. These "disposable" cartridges were designed to function for only one cartridge cycle without remanufacturing. The remanufacturers had found certain components that needed replacement on a regular basis. In 1990, the first aftermarket photoreceptor drum became available for use in remanufacturing the all-in-one cartridge of the "SX" engine variety, the most popular printer cartridge from around 1987 through 1994 at the time of this writing. When the long-life photoreceptor drum became available, the entire remanufacturing industry turned around and gained great strength and began a huge growth surge that still continues. In October 1993, HEWLETT-PACKARD, the largest seller of this printer engine using the all-in-one cartridge, entered the cartridge remanufacturing industry with the "OPTIVA" cartridge, further increasing the size as well as credibility of this relatively new industry. However, this relatively new industry grew from the all-in-one cartridge shortly after its debut. Before the introduction of the long-life drum, sometimes called the "superdrum" or "duradrum", the SX cartridge would last for around three cartridge remanufacturing cycles at best, since the actual useful life of the OEM drum was three cycles. However, the long-life drums got their names from the fact that they were designed to last for many remanufacturing cycles or recharges as they are sometimes called. Typically, the long life drum can last for ten or more such cycles, unlike the typical OEM(Original Equipment Manufacturer) drum. With the additional developments of drum coatings, originally designed for OEM drums, the long-life drum may last for many additional cycles. Some coatings, in theory, were designed to be dissolved and removed from over the drum surface every 1-3 cycles, so the drum life of the long-life drum almost seems limitless.

#However, with photoreceptor drums lasting for many cycles, other components of the cartridge have a tendency to require greater durability, a better solution, or a greater life. Also, as the success of these cartridges has skyrocketed, the demand is for cartrides with longer cycles, so component improvements are significant. Therefore, avoiding natural problems with prevention means must also be implemented for cartridges of longer life both in longer cycle times and greater number of cycles. One good example is the keeper blade used in imaging machines. The keeper blade is a blade on the waste toner hopper that rubs on the photoreceptor drum and keeps the toner in. It is essentially a seal to prevent toner leakage. As the photoreceptor drum rotates, after transferring the dry toner image from the drum to the paper, it then in theory should be toner free. However, residual waste toner is left on the drum. As the drum rotates, it rotates with the residual toner on the photoreceptor drum in contact with the keeper blade, forming a perfect seal, however, as it continues to rotate, it then is scraped off by the cutting edge of the wiper blade, and falls into the waste toner hopper. A perfect seal is maintained between the wiper blade and the photoreceptor drum so toner does not leak out of the waste toner hopper. Similarly, a perfect seal is maintained between the keeper blade and the photoreceptor drum so that toner will not leak out of the waste toner hopper.

#This invention, together with other objects, features, aspects, and advantages thereof, will be more clearly understood from the following description, considered in conjunction with the accompanying drawings.

#FIG. 1 shows the waste toner hopper section of a conventional toner cartridge assembly.

#FIG. 2 is a broad illustration of the location of the photoreceptor drum relative to the waste toner hopper.

#FIG. 1 shows a section 1 of a conventional toner cartridge assembly for use in imaging machines such as printers, copiers and facsimile machines. A waste toner hopper 2 is part of the assembly and is located adjacent the photoreceptor drum 3 as illustrated broadly in FIG. 2. After transferring the dry toner image from the drum 3 to the output paper during the printing process, the photoreceptor drum 3 continues its rotation. Residual toner on the drum 3 is in contact with the keeper or recovery blade 4, forming a perfect seal so toner will not leak out, yet allowing the toner to fall into the waste toner hopper 2, "keeping" it in the waste toner hopper 2 so it can't escape. As the drum continues to rotate, the cutting edge 5 of the wiper blade 6 scrapes the residual toner from the photoreceptor drum 3. The toner falls through the slot 7 into the waste toner hopper 2. The scraped-off residual toner cannot leak or penetrate into the rest of the cartridge assembly because of the seal-contact maintained between the edge 5 of the wiper blade 6 and the photoreceptor drum 3. Also, toner, in theory, cannot leak from the waste toner hopper 2 to the remainder of the cartridge assembly because of the seal provided through the keeper blade 4 and the drum 3.

#The keeper blade 4 in prior art is made of either a thin, stiff plastic or a thin resilient rubber material from three to five thousandths of an inch thick. The plastic may be acetate, MYLAR, polycarbonate or other stiff plastic. The rubber material may be urethane, neoprene or other type of rubber.

#Some waste toner hoppers 2 are designed so the keeper blade 4 is very close to the photoreceptor drum 3. The keeper blade 4 may be so close to the drum 3 that as the drum 3 rotates, the keeper blade 4 may inadvertently scrape residual toner off the drum 3 before it is scraped off by the edge 5 of the wiper blade 6 to fall into the waste toner hopper 2. Residual toner prematurely scraped off the drum 3 can leak into the remainder of the toner cartridge assembly, making a mess of other components and affecting the quality of the print on the output paper. Having the keeper blade 4 too close or tight to the drum 3 may also cause excess friction or heat, in turn causing premature wear or warpage of the drum 3 and keeper blade 4.