Patent Application
20090127767
This invention relates generally to an electronic reprographic printing system, and more particularly concerns a substrate feeding module having increase versatility that can feed one large sized shack of sheets in one mode or two smaller sized shack of sheets in another mode.
In a typical electrostatographic reproduction process machine, a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is imagewise exposed in order to selectively dissipate charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. With the advent of high speed xerography reproduction machines wherein copiers or printers can produce at a rate in excess of three thousand copies per hour, the need for sheet handling system to, for example, feed paper or other media through each process station in a rapid succession in a reliable and dependable manner in order to utilize the full capabilities of the reproduction machine. These sheet handling systems must operate flawlessly to virtually eliminate risk of damaging the recording sheets and generate minimum machine shutdowns due to misfeeds or multifeeds. It is in the initial separation of the individual sheets from the media stack where the greatest number of problems occur which, in some cases, can be due to up curl and down curl in sheets which generally occur randomly in the document stack.
It is also desirable to have a substrate feeding module that enables media versatility from A5 to legal and allows enhance productivity and sheet capacity for letter/A4 size to increase the time before it is necessary to add paper which is simple-to switch from one paper size to another without appreciably increasing the overall feeding module footprint.
There is provided a sheet feeding apparatus for feeding a stack of sheets in a direction of movement to a process station, including: an elevator tray for holding stacks of sheets; a feed head for picking up a sheet from said stack of sheets when a vacuum force; air knife for blowing air between individual sheets in said stack of sheets, said sheet feeding apparatus having a first mode of operation for feeding a single stack of sheets from said sheet tray and a second mode of operation for feeding first stack of sheets and a second stack of sheets from said elevator tray.
There is also provided a substrate feeding module that utilizes one shuttle feed head to feed alternately from two adjacent paper stacks residing in the same paper drawer. This invention makes use of the space normally not utilized when an A3 or larger sized paper drawer is filled with letter size or smaller substrates. It also allows for significantly lower manufacturing cost since one feed head is being shared for two stacks. This invention will enable double sheet capacity for letter/A4 sized (or smaller) substrates when feeding from an A3/11″×17″ or larger paper drawer without appreciably increasing the overall feeding module footprint.
Other features of the present invention will become apparent as the following description proceeds and upon reference to the drawings, in which:
While the present invention will be described in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
Inasmuch as the art of electrophotographic printing is well known, the various processing stations employed in the
Referring initially to
Next, the charged portion of photoconductive surface 12 is advanced through exposure station B. At exposure station B, the ROS 34 lays out the image in a series of horizontal scan lines with each line having a specified number of pixels per inch. The ROS includes a laser and a rotating polygon mirror block associated therewith. The ROS exposes the charged photoconductive surface of the printer.
After the electrostatic latent image has been recorded on photoconductive surface 12, the motion of the belt 10 advances the latent image to development station C as shown in
Again referring to
After transfer, the sheet is advanced by a conveyor (not shown) to fusing station E. Fusing station E includes a heated fuser roller 64 and a back-up roller 66. The sheet passes between fuser roller 64 and back-up roller 66 with the toner powder image contacting fuser roller 64. In this way, the toner powder image is permanently affixed to the sheet. After fusing, the sheet advances through chute 70 to catch tray 72 for subsequent removal from the printing machine by the operator.
After the sheet is separated from photoconductive surface 12 of belt 10, the residual developer material adhering to photoconductive surface 12 is removed therefrom at cleaning station F by a rotatably mounted fibrous brush 74 in contact with photoconductive surface 12. Subsequent to cleaning, a discharge lamp (not shown) floods photoconductive surface 12 with light to dissipate any residual electrostatic charge remaining thereon prior to the charging thereof for the next successive imaging cycle.
It is believed that the foregoing description is sufficient for purposes of the present application to illustrate the general operation of an electrophotographic printing machine incorporating the substrate feeding module of the present disclosure therein.
Further details of the construction and operation of substrate feeding module 200 of the present invention are provided below refer to
Now referring to
The lead edge wall 240 is the guide for stack 251 which is the front wall of the paper drawer or tray. Air knife and fluffer 251 can be located behind the stacks and mounted to the back or inboard wall of the drawer; or pivotally lowered in place from position shown in
When feeding letter sized or smaller substrates, feeder head 220 acquires and transport sheets alternately from stack 236 and stack 235 to take-away-rolls (TAR) 225. By alternating the feeding, the stacks are depleted at the same rate thereby maintaining the proper stack height to feed head distance. A controller 250 is coupled to feed head and varying the speed and acceleration of feed head dependent upon at least one predetermined sheet parameter; and wherein: the printing machine has discrete pitch zones; and the controller includes a displacement/velocity profile for the feed head dependent upon how much time is available to bring the sheet to transport speed in a given pitch zone. The feed head displacement/velocity profile is specific to each of the two stacks without creating any skipped pitches when feeding from either stack.
An advantageous feature of the present disclosure is that it enables full use of the normally empty space that exists in large format paper drawers when letter size or smaller sheets are being fed. The footprint of the feeder module is approximately the same as a traditional module with full format size or universal paper drawers, but provides double the letter sized sheet capacity. Unit manufacturing cost for this module is considerably less expensive than those with dedicated feeders per stack since a large percentage of the feeder components (including the blowers and air valves) are shared by the two stacks. This invention offers the customer the option of turning unused drawer space into an extra capacity feature when small paper is used in the large paper drawer.
It is, therefore, apparent that there has been provided in accordance with the present invention a paper preheat transport module that fully satisfies the aims and advantages herein before set forth. While this invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.
