Abstract:
This invention relates to color printing, and more particularly, to color laser printing systems. Such structures of this type, generally, employ a rotatable, carousel type shuttle color printer with a plurality of toner reservoirs such that one of the plurality of toner reservoirs is a high capacity toner reservoir.

Description:
FIELD OF THE INVENTION 
     This invention relates to color printing, and more particularly, to color laser printing systems. Such structures of this type, generally, employ a rotatable, carousel type shuttle color printer with an all in one electrophotographic (EP) cartridge having a high capacity toner reservoir. 
     DESCRIPTION OF THE RELATED ART 
     It is known, in shuttle type color printers to employ a paper drive. Exemplary of such of prior art is commonly assigned U.S. Pat. No. 5,978,642 (&#39;642) to D. J. Arcaro et. al., entitled “Color Printer with Shuttle Type Paper Drive and Method.” While the &#39;642 reference utilizes a toner cartridge which includes four separate colors (magenta, yellow, cyan, and black) located along the outside of a single photoconductor drum, these four separate colors each have a separate toner reservoir. Presently, these toner reservoirs contain approximately the same amount of toner. However, it is well known that the black toner is used more frequently for printing, especially for printing text, and this black toner reservoir requires replacement more frequently than the other three colors. Therefore, while the printer of the (&#39;642) reference is capable of color printing, it is desirable to include a black toner reservoir which can hold more black toner. 
     It is also known, in color image forming apparatus, to employ rotatable image forming units. Exemplary of such prior art is U.S. Pat. No. 5,809,380 (&#39;380) to N. Katakabe et. al., entitled “Color Image Forming Apparatus with Plural Color Units.” While the &#39;380 reference utilizes rotatable image forming units and a laser beam which is traversed through the image forming units, the apparatus also does not employ a high capacity black toner cartridge. Also, the &#39;380 reference employs expensive optics located within the rotatable image forming unit. Consequently, a more advantageous color printer would be presented if a high capacity black toner cartridge could be employed, while avoiding the use of expensive optics located within the rotatable image forming unit. 
     It is apparent from the above that there exists in need in the art for a carousel type shuttle color printer with all in one EP cartridges, which at least equals the printing characteristics of the known color printers, but which at the same time contains a high capacity black toner cartridge and avoids the use of optics in the cartridge. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure. 
     SUMMARY OF THE INVENTION 
     Generally speaking, this invention fulfills these needs by providing a carousel type shuttle color printer, comprising an exposure device including a laser beam periodically emitted from the exposure device and a rotatable color image forming unit having a plurality of different color development stations, wherein one of the plurality of development stations includes a high capacity toner reservoir such that the laser beam from the exposure device can be traversed substantially through the high capacity toner reservoir. 
     In certain preferred embodiments, the high capacity toner reservoir contains approximately twice as much black toner as a conventional black toner reservoir. Also, the carousel type shuttle color printer can print in a simplex or duplex mode. Finally, the printer avoids the use of optics located within the rotatable color image forming unit. 
     In another further preferred embodiment, the high capacity toner cartridge allows the carousel type shuttle color printer to continue printing longer without having to frequently replace the most frequently used toner color, which is usually the black toner. 
     The preferred color printer, according to this invention, offers the following advantages: excellent printing characteristics; ease of assembly and repair; good stability; excellent durability; decreased downtime; and good economy. In fact, in many of the preferred embodiments, these factors of printing characteristics, durability, decreased downtime, and economy are optimized to an extent that is considerably higher than heretofore achieved in prior, known color printers. 
     The above and other features of the present invention, which become more apparent as the description proceeds, are best understood by considering the following detailed description in conjunction with the accompanying drawings wherein like characters represent like parts throughout the views: 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a side plan view of a carousel type shuttle color printer with an all in one EP cartridge having a high capacity toner reservoir, according to the present invention; and 
     FIG. 2 is a cross-sectional view, taken along line A—A of FIG. 1, of a high capacity toner reservoir, according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference first to the FIG. 1, there is illustrated in advantageous environment for use of the concepts of this invention. With respect to the FIG. 1, carousel type shuttle color printer  2  is shown. Printer  2  includes, in part, conventional automatic paper infeed mechanism  4 , conventional manual paper infeed mechanism  6 , conventional paper outfeed mechanism  8 , conventional exposure device  10 , conventional laser beam  12 , paper shuttle path  14 , pinch rollers  16 ,  18 , paper transfer mechanism  20 , rotatable color image forming unit  50 , and duplex mechanism  100 . 
     With respect to paper shuttle path  14 , during the shuttling of the paper (not shown), pinch rollers  16 ,  18  and paper transfer mechanism  20 , operate to move the paper back and forth along paper shuttle path  14  by conventional techniques such as set forth in the above referenced &#39;642 patent. Preferably, paper shuttle path  14  is located adjacent to the sides of color image forming unit  50  and is located along the sides of printer  2  by conventional techniques. 
     With respect to paper transfer mechanism  20 , paper transfer mechanism  20  includes, in part, pinch rollers  22 ,  26 , transfer roller  24 , and transfer belt  28 . It is to be understood that transfer belt  28  contains a grit-like material on its outer side (the side in contact with the paper) in order to more efficiently shuttle the paper. 
     With respect to color image forming unit  50 , color image forming unit  50  includes, in part, photoconductor drum  52 , developer roller  54 , charge roller  56 , foam roller  58 , high capacity toner reservoir  60 , and waste toner reservoir  62 . It is to be understood that while only one of the color development stations of color image forming unit  50  has been described, the other color development stations are constructed in substantially the same manner. In particular, a standard capacity toner reservoir  30  is also illustrated. Preferably, high capacity toner reservoir  60  contains approximately twice as much toner as standard capacity toner reservoir  30 . It is to be understood that this standard capacity toner reservoir  30  interacts with its own separate photoconductor drum, developer roller, charge roller, foam roller, and waste toner reservoir. 
     With respect to duplex mechanism  100 , duplex mechanism  100  includes, in part, paper shuttle path  102  and pinch rollers  104  and  106 . Paper shuttle path  102  is located adjacent to the sides of color image forming unit  50  in the same manner as paper shuttle path  14 . Also, paper shuttle path  102  is similarly located along the sides of printer  2  in the same manner as paper shuttle path  14 . Duplex mechanism  100  allows the paper to be printed by conventional techniques on both sides through the use of paper shuttle path  102 , pinch rollers  104  and  106 , and paper transfer mechanism  20 . 
     As shown in FIG. 2, high capacity toner reservoir  60  is shaped so as to allow laser beam  12  to pass through high capacity toner reservoir  60  and impinge upon photoconductor drum  52 . In this manner, a greater amount of toner can be placed in high capacity toner reservoir  60  without adversely affecting the operating characteristics of printer  2 . 
     During the operation of carousel type color shuttle printer  2 , paper is transferred from automatic paper infeed mechanism  4  or manual paper infeed mechanism  6  by conventional techniques. At this point, printer  2  selects which color is going to be printed upon the paper. If, for example, black is selected as the color to be printed and black toner is located in the high capacity toner reservoir  60 , printer  2  rotates color image forming unit  50  such that the photoconductor drum  52  of the color to be printed is located across from transfer roller  24 , as shown in FIG. 1. A laser beam  12  is emitted from exposure device  10  by conventional techniques. Laser beam  12  traverses through high capacity reservoir  60 . The image to be printed upon the paper is then transferred to photoconductor drum  52  by conventional techniques. The paper is then printed according to conventional techniques such as those set forth in the above referenced &#39;642 patent. It is to be understood that, if another color is selected to be printed, color image forming unit  50  is rotated, along the directions of arrows A, such that one of the other photoconductor drums is located across from transfer roller  24  and laser beam  12  is traversed along the side of standard capacity toner reservoir  30 . 
     As discussed above, if another color needs to be printed upon the paper, the color image forming unit  50  is rotated along the directions of arrows A by conventional techniques. The paper is then shuttled by pinch rollers  16 ,  18 , paper transfer mechanism  20 , and/or duplex mechanism  100 . Color image forming unit  50  is then rotated along the directions of arrows A to locate the new desired color, i.e., the photoconductor drum  52  of the new desired color, across from transfer roller  24 . After the new color i.e., photoconductor drum  52  is located across from transfer roller  24 , the new color is printed on the paper according to conventional techniques. This procedure is implemented until any further desired colors are printed upon the paper. 
     Once given the above disclosure, many other features, modifications or improvements will become apparent to the skilled artisan. Such features, modifications or improvements are, therefore, considered to be a part of this invention, the scope of which is to be determined by the following claims.