Printing machine control system

Abstract: A printing machine includes a member (202) for storing a latent image thereon of a document and produces a printed copy of the document on a substrate. The apparatus for such a machine adjusts the printed copy output rate. The apparatus includes a latent image generating device (210) for generating the latent image of the document. The latent image generating device has a switch (212) for initiating the generating the latent image of the document. The apparatus further includes an adjustable timer (214) for setting an elapsed time between sequential generations of the latent image of the document and a controller (100) for controlling the printed copy output rate of the printing machine. The controller (100) is adapted to provide for a plurality of printed copy output rates based on the time elapsed between sequential generations of the latent image of the document.

Description: The present invention relates to an electrophotographic printing machine. More particularly, the invention relates to feeding substrates through a printing machine at variable feed rates. Printing machines include a large quantity of complex components which must be designed to operate as an efficient machine. Design, tooling and manufacturing costs make it desirable for manufacturers of copiers and printing machines to provide several machines based upon common machine components. In fact, to achieve maximum reliability and low cost machines with different printing capacities, a series of printing machines may be provided with very similar components and which utilize similar frames and subassemblies. The throughput or copy output of these machines may be varied to provide a multitude of offerings to the customer based upon need and marketplace considerations. Further, when selecting the copy output rate for a machine compromises are made between throughput of the machine and the optimum velocity and spacing between the adjacent sheets within the copy machine. Spacing between the adjacent sheets, also known as the interdocument gap, may be increased to minimize paper jams but in doing so may reduce the output of the machine. In prior art families of similar machines with different production rates, each of the different capacity machine offerings would require component changes including, for example, gear changes and motor changes to speed up and slow down the speed of the documents and copy substrates through the machines. As an alternative to the gear and motor changes, machines with skipped image frames or pitches may be used to provide various production output rates. The skipped pitches are an intentional skip or interruption of the flow of output sheets through the machine in the stream of sheets. This solution causes a non-uniform flow of sheets through the copy machines and while the production rate is decreased, the benefit to minimizing paper jams is not realized through this method. US-A 4,588,284 discloses the provision of a control system to automatically alter the control of a machine to respond to a different number of pitches or images that the machine can manage at one time. A flag in memory is monitored and in response to the flag, the machine control is adjusted to manage a different number of pitches during the operation of the machine and to provide clock signals for the timed actuation of events in each of the pitches. In accordance with one aspect of the invention, there is provided an apparatus for use in a printing machine including a member for storing a latent image thereon of a document. The printing machine is adapted to produce a printed copy of the document on a substrate. The apparatus adjusts the printed copy output rate thereof. The apparatus includes a latent image generating device for generating the latent image of the document. The apparatus further includes a switch for initiating the generating of the latent image of the document. The apparatus further includes an adjustable timer for setting an elapsed time between sequential generations of the latent image of the document and a controller for controlling the printed copy output rate of the printing machine. The controller is adapted to provide for a plurality of printed copy output rates based on the time elapsed between sequential generations of the latent image of the document. In accordance with another aspect of the present invention, there is provided a printing machine including an apparatus for adjusting the printed copy output rate thereof. The printing machine includes a member for storing a latent image thereon of a document. The printing machine is adapted to produce a printed copy of the document on a substrate. The apparatus is used to adjust the printed copy output rate. The apparatus includes a latent image generating device for generating the latent image of the document. The apparatus further includes a switch for initiating the generating of the latent image of the document. The apparatus further includes an adjustable timer for setting an elapsed time between sequential generations of the latent image of the document and a controller for controlling the printed copy output rate of the printing machine. The controller is adapted to provide for a plurality of printed copy output rates based on the time elapsed between sequential generations of the latent image of the document. In accordance with yet another aspect of the present invention, there is provided a method for providing printed copies of a document from a printing machine at a plurality of printed copy output rates of the printed copies. The method includes the step of inputting a value indicative of one of a plurality of printed copy output rates into a register within the printing machine. The method further includes the steps of generating a first latent image of a first document on a member and advancing the member. The method further includes the step of delaying the generating of a second latent image of one of the first document and a second document on the member for a period of time corresponding to the value indicative of the one of the plurality of printed copy output rates member. The method further includes the step of generating the second latent image, whereby the printed copy output rate is based on the time elapsed between sequential generations of the latent image of the document. A particular embodiment of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1A is a top view of a photoreceptor belt showing exposed and non-exposed areas for a 6 pitch mode of operation; Figure 1B is a top view of a photoreceptor belt showing exposed and non-exposed areas for a 5 pitch mode of operation; Figure 1C is a top view of a photoreceptor belt showing exposed and non-exposed areas for a 4 pitch mode of operation; Figure 2 is a perspective view of the electronic printing system of Figure 1; and Figure 3 is a schematic view illustrating the principal mechanical components and paper path of the printing system incorporating the output rate control system of the present invention; Figure 4 is a schematic view of a flow chart of the method of varying the output of the machine according to the present invention; Figure 5 is a schematic chart of the method of varying the output of the machine according to the present invention; and Figure 6 is a schematic view of an apparatus for use in a printing machine incorporating the output rate control system of the present invention. In Figure 3, there is shown, in schematic form, an exemplary electrophotographic copying system 2 for processing, printing and finishing print jobs in accordance with the teachings of the present invention. For purposes of explanation, the copying system 2 is divided into a xerographic processing or printing section 6, a sheet feeding section 7, and a finishing section 8. The exemplary electrophotographic copying system 2 of Figure 3 incorporates a recirculating document handler (RDH) 20 of a generally known type, which may be found, for example, in the well known Xerox Corporation models "1075", "5090" or "5100" duplicators. Such electrostatographic printing systems are illustrated and described in detail in various patents including US-A-4,961,092. All document handler, xerographic imaging sheet feeding and finishing operations are preferably controlled by a generally conventional programmable controller 100. The controller 100 is additionally programmed with certain novel functions and graphic user interface features for the general operation of the electrostatographic printing system 2 and the dual path paper feeder of the present invention. The controller 100 preferably comprises a known programmable microprocessor system, as exemplified by US-A-4,475,156. for controlling the operation of all of the machine steps and processes described herein, including actuation of the document and copy sheet feeders and inverters, gates, etc. According to the present invention and referring to Figure 6, apparatus 200 is shown which utilizes the electronically controlled printing machine output rate control system of the present invention. The apparatus 200 is utilized in printing machine 2. The printing machine 2 includes a member 13 in the form of a photoconductive belt which stores latent image 202 of a document. 204. The printing machine 2 is adapted to produce a printed copy 206 of the document 204 on a substrate 208. The apparatus 200 is utilized to adjust the printed copy output rate of the printed copy 206. The apparatus 200 includes a latent image generating device 210 for generating the latent image 202 of the document 204. The apparatus 200 further includes a switch 212 for setting an elapsed time between sequential generations of the latent image 202 of the document 204. The apparatus 200 further includes controller 100 for controlling the printed copy output rate of the printing machine 2. The controller 100 is adapted to provide for a plurality of printed copy output rates based on the elapsed time between sequential generations of the latent image 202 of the document 204. The apparatus 200 also includes an adjustable timer 214 for setting an elapsed time between sequential generations of the latent image 202 of the document 204. The controller 100 may be any suitable device capable of storing and processing controlling information for the printing machine 2. The controller 100 may be in the form of a programmable controller or in the form of a computer. The controller 100 may include a plurality of integrated circuits and other electronics necessary to properly control the machine 2. The controller 100 preferably includes a register 216 in the form of an addressable register, i.e. the register 216 may be located within a semiconductor device (not shown) which includes programmable memory. The register 216 preferably is addressable only by the machine logic within the printing machine 200. It should be appreciated that alternatively the register 216 of the controller 100 may be connectable to a control 220 shown in phantom which may be used to select a particular printed copy output rate by selecting one of several buttons on the control 220 or by inputting the printed copy output rate on a touchpad (not shown) located on the control 220. The control 220 may also include a display 222 shown in phantom which will show the current printed copy output rate. The register 216 may include a printer copy output rate 224 and may transmit a signal 226 through conduit 228 to a converter 230 within the controller 100 which converts the printer capacity output rate to a corresponding delay time 232. The time 232 is indicative of the delay time between successive sheets necessary to correspond to the printer copy output rate 224. The converter 230 may send a signal 234 corresponding to the delay time 232 through conduit 236 to adjustable timer 214. The adjustable timer 214 may compare the delay time 232 to an elapsed time 238 indicative of the elapsed time between sequential generations of the latent image of the document. The timer 214 may be any suitable timer capable of calculating the elapsed time 238. The timer 214 may be mechanical, but preferably is an electrical device. The timer 214 may be any suitable device capable of initiating the latent image generating device to generate the latent image. Preferably the timer 214 may utilize pulses 256 from rotary encoder 258 located on motor 254 utilized to drive the photoconductor belt 13. The pulses 256 are sent uniformly with respect to time and serve as clock ticks to time the operation of the machine 2. The pulses 258 are sent by conduit 259 to the timer 214 to be converted into elapsed time 238 in the timer 214 of the controller 100. The switch 212 may be mechanical, but preferably, is an electrical device. Preferably, when the elapsed time 238 equals the delay time 232, a signal 240 is sent to switch 212 either directly from the adjustable timer 214 or through the controller 100 and conduit 241. The signal 240 is used at the switch 212 to initiate the generation of the latent image of the document at the latent image generating device 210. The switch 212 thus sends signal 242 via conduit 244 to the latent image generating device 210 initiating the generation of the latent image 202 of the document 204. The latent image generating device 210 may be any suitable device capable of generating a latent image, i.e. the latent image generating device may be a raster output scanner (ROS) capable of generating a latent image from an electronic signal or in the form of a light lens illuminating device. For example, the latent image generating device 210 may include an illuminating lamp or lamps 245 which cooperate with optic components 246 and platen 248 to generate the latent image 202. The illuminating device may be a diode or any high energy illuminating source capable of rapid illumination or flashing. While the latent image generating device 210 may scan or traverse the document 204, preferably the latent image generating device 210 flash illuminates the entire document 204 instantaneously such that the latent image 202 is exposed totally and simultaneously such that the period of time for the exposing of the latent image 202 is substantially instantaneous. Preferably, the printing machine 2 further includes a document feeder 20 for advancing the document 204 toward the platen 248. The document feeder 20 is shown in greater detail in Figure 3. Referring again to Figure 6, the document feeder 20 preferably has a document feed rate independent of the elapsed time between sequential generations of the latent image 202 of the document 204. The document feeder 20 advances a first document 250 away from the platen 248 and advances a second document 252 toward the platen 248 subsequent to the generation of the latent image 202 of the first document 250. Preferably, the printing machine also includes development unit 6 for developing the latent image 202 with marking particle (not shown) to be transferred onto the substrates 208 to form the printed copy 206. Preferably, the printing machine 2 also includes member driver 254 in the form of a motor for advancing the photoconductive drum 13. The motor 254 preferably has a feed rate independent of the elapsed time between sequential generations of the latent image 202 of the document 204. Referring now to Figure 4, a flow chart is shown which explains the operation of the apparatus 200. The operation of apparatus 200 includes selecting the machine feed rate as shown in block 260. Once the machine feed rate is selected, the machine feed rate is converted to a DT or elapsed time between flashes of the illumination lamp 245 (see Figure 6) as shown in block 262. After the feed rate is converted to an elapsed time between flashes, first document 250 is advanced toward platen 248 (see Figure 6) as shown on block 264. After the first document has been advanced to platen 248, the photoconductor 13 is exposed by flash lamp 245 (see Figure 6) as described at block 266. After the photoconductor has been exposed, the time within the adjustable timer 214 (see Figure 6) is set to zero as described in block 268. After the time is set to zero, the second document 252 (see Figure 6) is advanced toward platen 248 as described in block 270. After the second document 252 is advanced, elapsed time 238 is compared to the delay time 232 in the adjustable timer 214 as shown as decision block 272. When the elapsed time reaches the delay time, the photoreceptor belt 13 is flash exposed by lamp 245 (see Figure 6) as shown at block 274. After the photoconductor 13 is flash exposed, decision block 276 determines whether the printing job is finished. If the printing job is finished, end job block 278 is reached. If the job is not done, the flow chart of Figure 4 shows that a subsequent document is advanced to platen as shown in decision block 270. The flow chart of Figure 4 continues until the job is done. Referring now to Figure 5, a method of controlling a printing machine output rate according to the present invention is described. The method includes first step 280 of inputting a value indicative of one of a plurality of printed copy output rates into a register within the printing machine. After step 280, a first latent image is generated of a first document on a member as shown in step 282. After step 282, the member is advanced as shown in step 284. After step 284 the step of delaying the generation of a second latent image of one of the first document in the second document on the member for a period of time corresponding to the value indicative of the one of the plurality of printed copy output rates is shown as step 286. After step 286, the step of generating the second latent image is performed whereby the printed copy output rate is based on the time elapsed between sequential generations of latent image of the document as shown in step 290. In summary and referring again to Figure 6, the apparatus 200 serves to provide for a printing machine 2 with an adjustable output rate which includes a document handler 20 which has a constant feed rate for any selected output rate of the printing machine. The printing machine 2 also includes a substrate feed system 292 and a copy output feed system 294 which have feed rates independent of the copy output rate selected for the machine. It should be appreciated, however, while the substrate feed system 292 feed rate and the document feeder 20 feed rate remain constant regardless of the copy output rate, the substrate 208 and the document 204 must be fed through the printing machine 2 in a timed relationship such that the document 204 must be presented to the platen 248 in a timed relationship such that the latent image 202 from the document 204 travels past the development unit 6 and toward transfer position 296 such that the substrate 208 may be matched with developed image 298 to form the copy 206. To accomplish this timed relationship, the controller 100 preferably sends signal 300 through conduit 302 to the substrate feed system 292 in a timed relationship to energize substrate feed motor 304 such that the substrate 208 arrives in a timed relationship. Further, the controller 100 sends a document feeder signal 306 through conduit 308 to document feeder motor 310 in a timed relationship such that the motor 310 is energized in the proper timed relationship to send document 204 to the platen 248 in a timed relationship such that the latent image 202 arrives to meet the substrate 208 in a timed relationship. Since the motor 254 rotating the photoconductive belt 13 operates at a constant speed independent of the print copy output rate, the belt 13 travels at a uniform velocity. Since the lamp 245 serves to expose the entire document 204 upon the energizing of the latent image generating device 210, the latent image 202 has a length L independent of the printer copy output rate. Since the consecutive latent images must not overlap, an interdocument gap 312 is positioned between adjacent latent images 202. Since the velocity of the belt 13 remains a constant, the interdocument gap 312 has a length LG which increases as the print copy output rate decreases. Referring now to Figure 1A, the photoreceptor belt 13 is shown in a cut and stretched out configuration. For example, as shown in Figure 1A, the belt 13 has a length BL which includes six pitches or six latent image 202s and six interdocument gaps 312. Thus, the belt 13 has a length BL which is equal to 6 X L + 6 X LG6. While it should be appreciated that the number of pitches or the number of latent images that may be fitted onto a belt does not need to be a whole number, latent image layouts for a 6 pitch, 5 pitch and 4 pitch operation are shown respectively in Figures 1A-1C. Referring to Figures 1A-1C, the length L of the latent images 202 of the belt 13 is identical for the 4, 5, and 6 pitch operations. It should be appreciated that the interdocument gap length LG5 of the 5 pitch operation of Figure 1B is greater than the interdocument gap length LG6 of the 6 pitch operation. Furthermore, the interdocument gap length LG4 of the 4 pitch operation is even greater than the length LG5 of the 5 pitch operation. Referring to Figures 1A through 1C, it is easy to understand that as the printing machine is slowed from the six pitch operation of Figure 1A through the four pitch operation of Figure 1C, the interdocument gap 312 becomes increasingly wider. Thus, the space between adjacent sheets in the copy feed system 294 becomes increasingly larger. Thus, as the machine is operated at slower output rates, the interdocument gap becomes larger reducing the occurrence of jams within the printing machine. Also by referring to Figures 1A through 1C, it is clear that the time between adjacent output sheets remains the same as the interdocument gap within the 4, 5 and 6 pitch operations is constant. By providing an electronically controlled printing machine output rate control system, the throughput of the printing machine may be modified without the need for gears or motors. By providing an electronically controlled printing machine output rate which provides for varying the interdocument gap and even uniform flow of sheets from the printing machine may be had at a variety of throughput rates. By providing an electronically controlled printing machine output rate control system which provides for varying the interdocument gap at various feed rates skip pitches otherwise utilized to adjust the throughput may be avoided. By providing an electronically controlled printing machine output rate control system whereby the interdocument gap may be varied in a virtually infinitely variable output rate may be provided for the machine. By providing an electronically controlled printing machine output rate control system for a printing machine, the printing machine output rate may be modified without requiring any hardware or mechanical changes to the machine.

Claims: An apparatus for adjusting the printed copy output rate for use in a printing machine including a member (13) for storing a latent image (202) thereon of a document, and being adapted to produce a printed copy of the document on a substrate (208), said apparatus comprising: a latent image generating device (210) for generating the latent image of the document; a switch (212) for initiating the generation of the latent image of the document; an adjustable timer (214) for setting a time (238) elapsed between sequential generations of the latent image of the document; and, a controller (100) for controlling the printed copy output rate of the printing machine, said controller (100) adapted to provide for a plurality of printed copy output rates based on the time (238) elapsed between sequential generations of the latent image of the document. An apparatus according to claim 1, wherein at least two of the plurality of printed copy output rates have relative ratios thereof corresponding to the number of latent images stored on the member. An apparatus according to claim 1 or 2, wherein: the time elapsed between sequential generations of the latent image of the document is substantially constant; and, the latent images (202) are spaced apart substantially equally along the member (13). An apparatus according to any one of the preceding claims, further comprising an addressable register (216) operably associated with said controller (100) and said timer (214), said register adapted for selecting one of the plurality of printed copy output rates. An apparatus according to claim 4, wherein said controller includes a semiconductor device having programmable memory; and wherein said register is located within said semiconductor device. An apparatus according to any one of the preceding claims, wherein said latent image generating device (210) is adapted to generate the latent image of the document substantially instantaneously so that the printed copy output rate is substantially based solely on the elapsed time between sequential generations of the latent image of the document. A printing machine including an apparatus for adjusting the printed copy output rate in accordance with any one of the preceding claims, and a member (13) for storing a latent image thereon of a document, the printing machine being adapted to produce a printed copy of the document on a substrate. A method of providing printed copies of a document from a printing machine at a plurality of printed copy output rates of the printed copies, the method comprising the steps of : inputting a value indicative of one of a plurality of printed copy output rates into a register within the printing machine. generating a first latent image of a first document on a member; advancing the member; delaying the generating of a second latent image of one of the first document and a second document on the member for a period of time corresponding to the value indicative of the one of the plurality of printed copy output rates; and generating the second latent image, whereby the printed copy output rate is based on the time elapsed between sequential generations of the latent image of the document. A method according to claim 8, wherein said latent image generating step generates the latent image of the document substantially instantaneously so that the printed copy output rate is substantially based solely on the elapsed time between sequential generations of the latent image of the document. A method according to claim 8 or 9, wherein: the time elapsed between sequential generations of the latent image of the document is substantially constant; and, the latent images are spaced apart substantially equally about the member.

Inventors: PALUMBO STEPHEN A, PALUMBO, STEPHEN A.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1999
Main classification: G03G15
IPC codes: G03G21, G03G15