Patent Publication Number: US-8121505-B2

Title: Hybrid printing system

Description:
The present disclosure relates to electrostatographic image producing machines and, more particularly to a hybrid printing system for producing full process color prints and low cost monochrome prints. 
     BACKGROUND OF THE DISCLOSURE 
     Generally, electrostatographic imaging is performed in cycles by forming a latent image of an original document onto a substantially uniformly charged photoreceptive member. The photoreceptive member has a photoconductive layer. Ordinarily, exposing the charged photoreceptive member with the image discharges areas of the photoconductive layer corresponding to non-image areas of the original document, while maintaining the charge in the image areas or vice versa. In discharge area development, the reverse is true where the image areas are the discharged areas and the non-image areas are the charged areas. Thus in either case, a latent electrostatic image of the original document is created on the photoconductive layer of the photoreceptive member. 
     Charged developing material is subsequently deposited on the photoreceptive member to develop the latent electrostatic image areas. The developing material may be a liquid material or a powder material. The charged developing material is attracted to charged or discharged latent electrostatic image areas on the photoconductive layer. This attraction develops the latent electrostatic image into a visible toner image. The visible toner image is then transferred from the photoreceptive member, either directly or after an intermediate transfer step, to a copy sheet or other support substrate as an unfused toner image which is then heated and permanently affixed to the copy sheet, resulting in a reproduction or copy of the original document. In a final step, the photoconductive surface of the photoreceptive member is cleaned to remove any residual developing material in order to prepare it for successive imaging cycles. 
     In full process color electrostatographic printing, rather than forming a single latent image on the photoconductive surface, separate latent images, corresponding to different color separations, must be created. Each single color latent electrostatic image is developed with a corresponding colored toner. This process is repeated for a plurality of colors. By any one of several processes, each single-color toner image is eventually superimposed over the others and then results in a single full process color toner image on the copy sheet. Thereafter, the full process color toner image is also heated and then permanently fixed to a copy sheet, creating a full-color copy. 
     In a conventional tandem color printing process, four imaging systems are typically used. Photoconductive drum imaging systems are typically employed in tandem color printing due to the compactness of the drums. Although drums are used in the preferred embodiments, a tandem system can alternatively use four photoconductive imaging belts instead of the drums. Each imaging drum or belt system charges the photoconductive surface thereof, forms a latent image thereon, develops it as a toned image and then transfers the toned image to an intermediate belt or to a print medium. In this way, yellow, magenta, cyan, and black single-color toner images are separately formed and transferred. When superimposed, these four toned images can then be fused, and are capable of resulting in a wide variety of colors. 
     In image-on-image color printing, an endless photoreceptor belt, a controller and a series of imaging subassemblies are employed that each include a charging unit, a color separation latent image exposure ROS unit or LED print bar, and a corresponding color toner development unit. As the endless photoreceptor belt moves in an indicated direction, an image frame thereon is charged, exposed and developed, in succession, by each imaging subassembly, with each imaging subassembly thus forming a color separation image corresponding to color separation image input video data from the controller. After the first imaging subassembly forms its color separation toner image, that color separation toner image is then recharged and re-exposed to form a different color separation latent image, and then correspondingly developed by the next imaging subassembly. After the final color separation image is thus formed, the fully developed full process color image is then ready to be transferred from the image frame at transfer station to a print media. 
     Following is a discussion of prior art, incorporated herein by reference, which may bear on the patentability of the present disclosure. In addition to possibly having some relevance to the question of patentability, these references, together with the detailed description to follow, are intended to provide a better understanding and appreciation of the present disclosure. 
     U.S. Pat. No. 5,347,353 issued Sep. 13, 1994 to Fletcher and entitled “Tandem high productivity color architecture using a photoconductive intermediate belt” discloses a system in which tandem, high productivity color images are formed by using a photoconductive belt as an imaging surface and as a transferring device. A full process colored image is produced comprising a plurality of color layers. The apparatus includes a charging device, an image forming device, and a developing device located along a photoconductive belt to form a toned image layer on the belt. Additional color layers may be provided by either photoreceptive imaging drums or additional photoconductive belts. 
     U.S. Pat. No. 5,837,408 issued Nov. 17, 1998 to Parker et al. and entitled “Xerocolography tandem architectures for high speed color printing” discloses a full process color imaging system that uses two xerocolography engines in tandem. Each of the two xerocolography engines is capable of creating three perfectly registered latent images with subsequent development thereof in a spot next to spot manner. Each engine is provided with three developer housing structures containing five different color toners including the three subtractive primary colors of yellow, cyan and magenta. Two of the primary colors plus black are used with one of the engines. The third primary color is used with the second tandem engine which also uses one of the primary colors used with the first engine as well as a fifth color which may be a logo or a gamut extending color. The full process color imaging capability provided is effected without any constraints regarding the capability of the laser imaging device to image through previously developed components of a composite image. Also, the development and cleaning field impracticalities imposed by quad and higher level imaging of the prior art are avoided. Moreover, the number of required image registrations compared to conventional tandem color imaging is minimal. Therefore, only one registration is required compared to three or four by conventional tandem engine imaging systems. 
     U.S. Pat. No. 5,613,176 issued Mar. 18, 1997 to Grace and entitled “Image on image process color with two black development steps” discloses a printing system using a recharge, expose and development image on image process color system in which there is an optional extra black development step. The printing system may be a system where all of the colors are developed in a single pass, or a multi-pass, system where each color is developed in a separate pass. The additional black development step results in optimal color quality with black toner being developed in a first and/or last sequence. Having more than one black development station allows low gloss and high gloss black toner to be applied to the same image, enabling the very desirable combination of low gloss text and high gloss pictorials on the same page. 
     U.S. Pat. No. 5,296,904 issued Mar. 22, 1994 to Jackson and entitled “Three-roll fuser with center pressure roll for black and color application” discloses a three roll fuser system for a xerographic machine includes a reversibly drivable central pressure roll, a first fuser roll located adjacent the central pressure roll forming a first fuser nip with the central roll, and a second fuser roll located adjacent the central pressure roll on a substantially opposite side of the central pressure roll as the first fuser roll forming a second fuser nip with the central roll. Copy sheets having an unfused image on a side thereof are transported from an inlet through one of the first and second nips to fuse the image on the copy sheet and then transported to an outlet. The three roll fuser system is capable of selectively fusing either side of a copy sheet without requiring extra sheet inverting devices. In a preferred embodiment, the fuser rolls have differing physical properties and can be operated under different operating conditions such as fuser temperature and speed. 
     In conventional color printing systems with black only image capability, it is well known that the run cost of the color xerographic print engine is much higher than that of a stand alone monochrome black print engine, even when only black images—are being produced. This higher run cost issue has been identified as one of the barriers to greater and faster color printing systems adoption in the office and in lower-volume production markets where providing both a color and monochrome black engine may not be justifiable. This higher run cost issue is also an annoyance to high-volume production customers because incorporating pages from a stand alone low cost monochrome black engine into a mixed job may be even more expensive than printing black pages at the higher run cost on their color print engine. 
     Conventional printing systems such as those described above can nowadays be found in the office environment as well as in small or entry production environments. The trend by manufacturers however is towards slower color image producing versions that also offer a limited form of “black images” only from the color version. The black image production is limited because color version printers (including the current conventional ones that also offer black images) tend to run at higher run costs per print even when running black images only or in a black mode. The undesirable result is additional wear to the color components as well as higher run costs for each print, color or black. 
     There is therefore a current need for a printing system that can produce color images as well as black images without the current disadvantages of slower speeds and higher costs for the black images. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with the present disclosure, there is provided a hybrid printing system that includes (a) a media path assembly having an image transfer/transport unit for receiving and moving media to a fusing apparatus; (b) a process color image output terminal (IOT) assembly including first imaging components for forming and transferring color images onto the intermediate image receiving member, the color IOT assembly being mounted for forming a first image transfer nip with one of a first side and a second and opposite of the image transfer/transport unit; and (c) a monochrome image output terminal (IOT) assembly mounted opposite the process color image output terminal (IOT) assembly for forming a second image transfer nip with the other of the first side and the second and opposite of the image transfer/transport unit, the monochrome image output terminal (IOT) assembly including a moveable image bearing member and second imaging components for forming monochrome images on the image bearing member. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic elevational view of the hybrid printing system of the present disclosure showing the novel architecture of a full process color image producing module and a black image output terminal in a full process color image output mode; and 
         FIG. 2  is the schematic elevational view of the hybrid printing system of  FIG. 1  showing the novel architecture of the full process color image producing module and the black image output terminal in a monochrome image output mode. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the  FIGS. 1-2 , the hybrid printing system  300  of the present disclosure is illustrated and is suitable for producing full process color prints and low cost monochrome prints. The hybrid printing system  300  includes (a) a machine frame  302 ; (b) a media path assembly  310  mounted within the machine frame and including a media supply source  312 , and an image transfer/transport unit  320  for receiving and moving media  314  to a fusing system  330 ; and (c) a full process color image output terminal (IOT) assembly  200 , which as illustrated includes a moveable intermediate transfer belt or image receiving and carrying member  202 , and a first series of components  210  for forming and transferring full process color images X 1  onto the intermediate image receiving and carrying member  202  for subsequent transfer onto the image transfer/transport unit  320 . Although shown with a moveable intermediate transfer belt or image receiving and carrying member  202 , the full process color image IOT as is well known may equally be an image-on-image architecture, or one that transfers directly to paper such as a re-circulating or tandem escorted sheet architecture. The full process color image IOT assembly  200  is mounted so that the intermediate image receiving and carrying member  202  is capable of forming a first image transfer nip  204  with one of a first (shown as a top) side  322  and a second and opposite (shown as a bottom) side  324  of the image transfer/transport unit  320 . 
     Although shown and described with reference to a top side and a bottom side, the first and second sides  322  and  324  would of course be left and right sides in an having a substantially vertical image transfer/transport unit or paper path  320 . Additionally, although shown with a single, moveable image transfer/transport unit  320 , it should be understood that the hybrid printing system  300  will function equally as well with separate image transfer/transport units (not shown) for the full color module  200  and the monochrome module  100 . 
     The hybrid printing system  300  also includes (d) a monochrome image output terminal (IOT) assembly  100  mounted within the machine frame  302  for forming a second image transfer nip  104  with the other of the top side  322  and the bottom side  324  of the image transfer/transport unit  320 , and so as to be opposite the full process color image output terminal (IOT) assembly  200 . As illustrated, the full process color image output terminal (IOT) assembly  200  is located on the top side  322  of the image transfer/transport unit  320 , but it could equally be located on the bottom side  324  thereof. The monochrome image output terminal (IOT) assembly  100  includes a moveable image bearing member  102  and a second series of components  110  for forming monochrome images X 2  on the image bearing member  102  for subsequent transfer at the second image transfer nip  104  onto the image transfer/transport unit  320 . 
     The hybrid printing system  300  further includes a programmable controller  360  that is connected to the full process color image output terminal (IOT) assembly  200 , to the monochrome image output terminal (IOT) assembly  100 , and to the image transfer/transport unit  320  for controlling various operations thereof. Importantly, the controller  360  includes a full color print engine only mode M 1 , and a monochrome or black print engine only mode M 2 . 
     Additionally, the hybrid printing system  300  also includes a fusing system  330  that is mounted aligned with the image transfer/transport unit  320  for receiving and fusing images X 1 , X 2  on image carrying substrates or media  314 . The fusing system  330  as shown includes a first fusing apparatus  332  forming a first fusing nip  333  for fusing full process color images X 1 , and a second fusing apparatus  342  forming a second fusing nip  343  for fusing monochrome images X 2 . 
     The first fusing apparatus  332  and the second fusing apparatus  342  have a common pressure roller CPR for forming one of the first fusing nip  333  and the second fusing nip  343  at any one time. The first fusing apparatus  332  thus includes the common pressure roller CPR and a heated fusing belt  335  forming the first fusing nip  333 , and the second fusing apparatus  342  shares the common pressure roller CPR with the first fusing apparatus  332  as shown and includes a heated fuser roller  345  forming the second fusing nip  343  with the common pressure roller CPR. The common pressure roller CPR is moveable as shown by the double headed arrow between a first axial position F 1  and a second axial position F 2  for forming the first fusing nip  333  in the first fusing apparatus  332 , and the second fusing nip  343  in the second fusing apparatus  342 . 
     The image transfer/transport unit  320  includes an endless image transfer/transport belt  326  and has a first end  325  for forming both the first image transfer nip  204  and the second image transfer nip  104 . It also has a second end  327  adjacent the fusing system  330 , and the second end  327  thereof is moveable as also shown by a double headed arrow between an upper position P 1  and a lower position P 2  for aligning with the first fusing nip  333  and the second fusing nip  343  respectively. The image transfer/transport unit  320  as shown also includes a biased electrostatic transfer backup roll BTR for assisting image (X 1 , X 2 ) transfer onto a print media  314  that is on the image transfer/transport unit  320  and is within anyone of the first image transfer nip  204  and the second image transfer nip  104 . 
     More specifically as illustrated in  FIGS. 1-2 , the hybrid printing system  300  of the present disclosure includes (a) the machine frame  302 , (b) the media path assembly  310  (that is mounted pre-fuser) and includes the image transfer/transport unit  320  (which is reversible as shown by the various arrows) for receiving and moving media  314 ; (c) the process color image output terminal (IOT) assembly  200  (shown as a typical tandem process color system using an intermediate transfer belt  202 ); and (d) the monochrome image output terminal (IOT) assembly  100  (shown using a drum photoreceptor  102 ). The process color image output terminal (IOT) assembly  200  is arranged and mounted above, and oppositely of the monochrome image output terminal (IOT) assembly  100 , with the media path assembly  310  between them, extending from media source  312  to the fusing system  330 . 
     The reversible image transfer/transport unit  320  for example is a vacuum transport device that in the architectural arrangement of the present disclosure is able to present unfused color images X 1  to the fusing system  330  with the images facing up at the heated fusing belt  335 , and unfused monochrome black images X 2  to the fusing system  330  with the images facing down at the heated fuser roller  345 . The fusing system  330  is thus a three-element fusing system having two fusing nips, namely the first fusing nip  333  and the second fusing nip  343 , with a common center pressure roller CPR. 
     The common center pressure roller CPR advantageously is reversible and permits (i) the use of a dedicated fusing element (the heated fusing belt  335 ) for forming the first fusing nip  333  appropriately suitable for fusing color images X 1 , and (ii) the use of another and different dedicated fusing element (the heated fuser roller  345 ) for forming the second fusing nip  343  that is more suitable for fusing monochrome black images X 2 . The reversible common center pressure roller CPR is additionally moveable as shown by the double headed arrow into a first axial position F 1  (up) for forming the first fusing nip  333 , and into a second axial position F 2  (down) for forming the second fusing nip  343 , depending on which of the image output terminals  200 ,  100  is alternatively being operated. 
     Advantageously, when one of the image output terminals  200 ,  100  and its corresponding first and second fusing nips  333 ,  343  are being used as such, the other and the rest of the elements of the other fusing nip  333 ,  343  can be decammed or inactivated and therefore not suffer any wear and tear. This is important because the costs of service actions and of replacement of elements due to wear and tear are a significant fraction of the cost of running even monochrome black images on a conventional process-plus black color printing system. 
     Looked at alternatively, as illustrated in  FIGS. 1-2 , the hybrid printing system  300  of the present disclosure for example is comprised of (a) an intermediate belt  202  and drum photoreceptor based tandem CMYK color xerographic module  200  and a drum photoreceptor based xerographic black print engine or black image producing module  100  in which each of the modules can be operated alternative to the other and alone. As such, the black image producing module  100  can be operated alone as a low cost stand-alone monochrome black print engine for producing black only images X 2 . The CMYK full color print engine or full process color image producing module  200  includes drum-based CYM image output terminals  212 ,  214 ,  216 , and an included K (black) image output terminal  2118 , and the intermediate transfer belt  202  on which the image output terminals  212 ,  214 ,  216 ,  218  form the full process color image X 1 . As is well known, each image output terminal includes an image bearing member  220 , and a charging device  222 , exposure device  224 , development device  226  and cleaning devices  228  (as the first series of components  210 ) for forming a separate toner image on the image bearing member  220  for transfer onto the intermediate transfer belt or image receiving and carrying member  202 . 
     The CMYK full color print engine or full process color image producing module  200  as such can be operated alone to form process color images X 1 . The media path assembly  310  is also comprised of a media holding and supply module  312  that is coupled to the image transfer/transport unit  320  as shown. The media holding and supply module  312  for example includes and supplies cut sheet media  314 . 
     As pointed out above, the controller  360  includes a full color print engine only mode M 1 , and a monochrome or black print engine only mode M 2 . In the full color print engine only mode M 1  ( FIG. 1 ), (a) the black image producing module  100  is inactivated and the CYMK image output terminals  212 ,  214 ,  216  and  218  of the full process color image producing module  200  are operated to form a full CYMK color image X 1  on the intermediate transfer belt  202  in a conventional manner; (b) the first end  325  of the electrostatic transfer/transport unit  320  under the full process color image producing module  200  is cammed by means  321  into an active or upper position P 2  for creating the first or color module image transfer nip  204  that is required to enable image transfer from the full process color image producing module  200 . 
     In this full color print engine only mode configuration, the black print engine  100  is completely inactive and the electrostatic transfer/transport unit  320  carries print media  314  into the first or color module image transfer nip  204  for receiving the full CYMK color image during image transfer. Thereafter, the electrostatic transfer/transport unit  320  carries the print media  314  (bearing the transferred full CYMK color image facing up) through to the first fusing nip  333  of the fusing system  330 . As already pointed out, while the hybrid printing system  300  is in the process color image producing mode ( FIG. 1 ), the black print engine  100  will be inactive. 
     In the (ii) black engine only mode ( FIG. 2 ), (a) the full process color image producing module  200  is inactivated and the black image output terminal  110  of the black print engine  100  is operated in a monochrome fashion to produce black images on the photoreceptor drum  102  at near monochrome rates (speed and cost); (b) the first end  325  of the electrostatic transfer/transport unit  320  is cammed by means  321  into an active or lower position P 1  for creating the second black image transfer nip  104  that is required to enable image transfer from the photoreceptor drum  102  during black print engine only printing ( FIG. 2 ). 
     Thus the full process color mode control M 1  of the controller  360  is suitable for operating the hybrid printing system  300  as a full process color machine ( FIG. 1 ) during which the black image producing module  100  is turned off, the first end  325  of image transfer/transport unit  320  is moved into the first color image transfer nip  204  with the intermediate transfer member (image receiving and carrying or belt)  202 , and the fusing system  330  is set for fusing with the first fusing nip  333  and transfer/transport unit  320  is aligned with the first fusing nip  333 . The full process color mode control M 1  for example includes a first throughput speed S 1  that is relatively less than a second throughput speed S 2  for operating the hybrid printing system  300  in a black mode control M 2 . 
     The black mode control M 2  is suitable for operating the hybrid printing system  300  as a stand-alone black machine ( FIG. 2 ). During this mode M 2 , the full process color image producing module  200  is turned off, the transfer/transport unit  320  is moved out of the first nip  204  with the intermediate transfer member  202 , and is instead moved into the second nip  104  with the image bearing member  102  of black image output module  100 . 
     To recap, the full process color image output module  200  and a black monochrome image output module  100  are advantageously arranged and mounted architecturally on opposite sides  322 ,  324  of the pre-fuser media path assembly  310  (that includes the reversible image transfer/transport unit  320 ) for delivering finished images X 1 , X 2  to the fusing system  330 . In this architectural arrangement, color images X 1  and monochrome black images X 2  will be delivered to the fusing system  330  with un-fused images oriented oppositely (top/bottom) relative to each other. 
     Accordingly, in this architectural arrangement, the fusing system  330  has a reversible common center pressure roller CPR (and hence separate heated fuser members  335 ,  345 ) for separately fusing color images X 1  and monochrome black images X 2 . This advantageously permits complete separation of all high-cost color consumable and replaceable elements of the full color module  200  from low-cost monochrome black consumable and replaceable elements of the monochrome module  100 . The result is low, stand alone type monochrome black image run costs with minimum additional size and complexity from what is otherwise a hybrid but fully-capable process color printing system. 
     As can be seen, there has been provided a hybrid printing system that includes (a) a media path assembly having an image transfer/transport unit for receiving and moving media to a fusing apparatus; (b) a process color image output terminal (IOT) assembly including first imaging components for forming and transferring color images onto the intermediate image receiving member, the color IOT assembly being mounted for forming a first image transfer nip with one of a first side and a second and opposite of the image transfer/transport unit; and (c) a monochrome image output terminal (IOT) assembly mounted opposite the process color image output terminal (IOT) assembly for forming a second image transfer nip with the other of the first side and the second and opposite of the image transfer/transport unit, the monochrome image output terminal (IOT) assembly including a moveable image bearing member and second imaging components for forming monochrome images on the image bearing member. 
     The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.