Abstract:
A media sheet tray includes a first media size sensor, a second media size sensor, a first circuit connected to the first media size sensor, a second circuit connected to the second media size sensor, and a switch within the second circuit. The switch can be in an open position disconnecting a continuity of the second circuit, or in a closed position maintaining the continuity of the second circuit. Media being within the media sheet tray closes the switch. Further, a combination of the first circuit connecting to the first media size sensor and the second circuit being discontinuous indicates that paper is absent from the media sheet tray.

Description:
BACKGROUND 
     Embodiments herein generally relate to printing devices and more particularly to sensing the presence of sheets of media in paper trays of printing devices. 
     In any media feeding system the media must be sensed as being in the tray before feeding can commence. Without a media present sensor, when the feed system tries to feed and is unable because of the lack of media, the next sensor upstream will trip and a paper jam fault will occur. This raises shut down and unscheduled maintenance request rates significantly and upsets customers, because this causes customers to look for paper jams that do not exist. 
     For systems that do include paper present sensors, these sensors and their dedicated wiring and circuitry add cost, and in a system where pricing is important, any cost reduction is critical. More specifically, conventional paper present sensors include a separate photo-reflective sensor, separate wiring connector, flag, and associated wiring harness and separate pins out that eventually connect to the motherboard of the processor, etc. Such additional components add cost, complexity, and material usage. 
     SUMMARY 
     An exemplary printing device herein comprises a processor, a printing engine operatively (directly or indirectly) connected to the processor, and a tray slot comprising a media tray connection. The tray slot is also operatively connected to the processor. A media sheet tray connects to the tray slot. The media sheet tray has an integrated circuit board that, in turn, includes a first media size sensor and a second media size sensor. A first circuit connects the first media size sensor to the media tray connection of the tray slot and a second circuit connects the second media size sensor to the media tray connection of the tray slot. 
     A switch is positioned within the second circuit, the switch can be in an open position disconnecting a continuity of the second circuit, or a closed position maintaining the continuity of the second circuit. The switch is closed by media being within the media sheet tray. The first media size sensor is operatively connected to the processor when the first circuit is connected to the media tray connection. The second media size sensor is operatively connected to the processor when the switch is in the closed position, and the second circuit is connected to the media tray connection. The combination of the first media size sensor being connected to the processor and the second media size sensor being disconnected from the processor indicates to the processor that paper is absent from the media sheet tray. 
     The first media size sensor outputs a first measurement of media within the media sheet tray to the processor when the first circuit is connected to the media tray connection, and the second media size sensor similarly outputs a second measurement of media within the media sheet tray, different than the first measurement, to the processor when the second circuit is connected to the media tray connection and the switch is in the closed position. 
     The media sheet tray can further comprise a media lift plate, and the switch can extend through the media lift plate. The switch can be a pressure switch. Thus, the switch could comprise a conductive rotating member and a conductive contact. The conductive rotating member rotates into a position contacting the conductive contact when pressure from gravitational weight of at least one sheet of media is exerted on the conductive rotating member by the sheet of media is in the media sheet tray. The switch is in the closed position and completes the second circuit when the conductive rotating member is in contact with the conductive contact. 
     These and other features are described in, or are apparent from, the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various exemplary embodiments of the systems and methods are described in detail below, with reference to the attached drawing figures, in which: 
         FIG. 1  is a flow diagram illustrating various embodiments herein; 
         FIG. 2  is a top-view schematic diagram of a device according to embodiments herein; 
         FIG. 3  is a top-view schematic diagram of a device according to embodiments herein; 
         FIG. 4  is a top-view schematic diagram of a device according to embodiments herein; 
         FIG. 5  is a perspective-view schematic diagram of a device according to embodiments herein; 
         FIG. 6  is a schematic wiring diagram of a device according to embodiments herein; 
         FIG. 7  is a schematic wiring diagram of a device according to embodiments herein; and 
         FIG. 8  is a side-view schematic diagram of a device according to embodiments herein. 
     
    
    
     DETAILED DESCRIPTION 
     The devices herein reduce the number of components needed for paper trays by using a size sensing board to determine whether media (paper, transparencies, card stock, etc.) is present in the paper tray. A size sensing board generally has at least two sets of traces (e.g., trace buckets or size sensors) one for lengths and one for widths of paper. The combination of the media location provided by these two traces and the use of a matrix look up table tells the machine the size of the paper used. Therefore, if both traces are contacted by media in the tray, the paper size is determined, if neither trace is contacted the machine can indicate that the tray is not fully inserted into the machine. 
     With the structures herein, the wiring to one of the trace sets is altered, and the electrical path between the trace and the controller is interrupted by a metal pivoting lift plate that needs to be in a certain position to complete the circuit. Therefore, with the structures herein, if the tray is found to be properly inserted (because one trace is contacted) but the other trace (which connects through the pivoting tray) is not contacted, this indicates to the machine that the tray is empty and allows the machine to display the “out of paper” indication on the user interface. This design reduces cost of paper sensing by substituting a single metal contact switch in place of items such as a dedicated paper-present photo reflective sensor, wiring connector, flag, associated wiring harness, and pins out. 
     The flow diagram in  FIG. 1  shows three potential states that the size sensing board could see when the tray is inserted, and the required actions afterwards to allow printing to commence. Beginning, for example, at item  102 , if the paper tray is not fully inserted, none of the traces will be connected and the user interface (UI) of the printer will display a message that the tray is not closed to the user in item  104 . In response, the user can fully close the paper tray, as indicated by item  106 . 
     In item  110 , if some, but less than all, traces are connected to (or sensed by) the processor, this indicates that the tray is fully inserted, but that the pivoting lift plate has interrupted the connection between one of the traces and the processor. This state indicates that there is no media in the paper tray, and therefore a message indicating that the tray is out of paper is provided on the user interface in item  112 . In response, the user will open the paper tray to load paper in item  114  (and, again, items  104  and  106  display a message that the paper tray is not closed). 
     If both traces are complete (are connected to (or sensed by) the processor) in item  120 , the printing machine uses the information from the trace buckets to determine the paper size  122 . In item  124 , the customer can confirm the paper size to allow printing to begin in item  126 . Therefore, as shown in  FIG. 1 , the three states (both traces complete  120 , no traces complete  102 , or less than all traces complete  110 ) provide an indication of whether media is present in the paper tray, as well as the size of the media, all using the same circuitry (with the addition of only a single simple switch connection to complete one of the circuits). 
     As shown in  FIG. 2 , a paper size detection board  200  utilizes at least two sets of traces  202 ,  204  located on a single circuit board. Contact members (that move when the paper guides of the paper tray move) contact the traces  202 ,  204 , and the position of such contact members on the traces  202 ,  204  give the detection board  200  width and length measures that the board  200  provides to the processor of the printing device. One set of traces  202  is used to determine the width bucket for a sheet and the other  204  for the length bucket. Using the combination of these two buckets, the paper size currently loaded in an internal tray can be determined and supplied to the printer&#39;s processor. This board  200  is also used to verify that the tray is fully pushed into the machine; both traces will not connect to the machine processor, and neither will return a signal, if the tray is not fully inserted into the printing machine. 
       FIG. 3  is a top view of a paper tray  33  that uses a metal lift plate  220 . In  FIG. 3 , the paper size detection board is again shown as item  200 , various paper guides (that include contact members  206  that contact, and move on, the traces  202 ,  204 ) are shown as items  222 , a lift tray bar is shown as item  226 , and an electrical connection element (conductive sponge) is shown as item  224 . The ground element  224  provides the electrical power/ground for the traces  202 ,  204  of the paper size detection board  200 . 
     The metal lift plate  220  is grounded to the printing machine by way of the lifting arm  226  and the electrical connection element  224  on the back of the tray  33 . This grounding path is interrupted using a pressure switch  230  that extends through the lift plate  220 , as shown in  FIG. 4 . Therefore, the electrical circuit for the width sensing trace  202  is completed only when the pressure switch is depressed by paper being present in the tray. 
     As would be understood by those ordinarily skilled in the art, the pressure switch  230  could be located in any desired position and, as shown in  FIG. 4 , can be located near the front center of the plate  220  to be able to be actuated for all media sizes. Further, the pressure switch  230  can be located away from location of the edges of paper so any amount of paper, even one sheet, will always actuate the pressure switch  230 . 
       FIG. 5  shows a perspective view of the opposite side of the plate  220  shown in  FIG. 4 . In  FIG. 5 , the conductive pressure switch is again shown as item  230 , a non-conductive pivot housing is shown as item  232 , and a small electrical connection element is shown as item  234 . When paper is on the plate  220 , the paper will make the pressure switch  230  pivot around and contact the electrical connection element  234 , which is attached to the plate  232 . The pivot housing  232  is attached to the underside of the plate  220 , but is non-conductive. When the pressure switch  230  rotates, it completes the electrical path for the width sensing trace  202  in this example. 
     Exemplary electrical connections are shown in schematic form in  FIG. 6 . More specifically in  FIG. 6 , the paper tray is shown as item  33 , the paper tray slot of the printing machine is shown as item  212 , the paper tray slot power/ground connection is shown as item  240 , and the paper tray slot data connection is shown as item  250 . The electrical power and/or ground (referred to herein using the “power/ground” shorthand notation) of the printing machine is shown as item  214 , and the processor of the printing machine is shown as item  60 . Those ordinarily skilled in the art would understand that power could also be supplied through a separate power circuit or through the data connections  250 ,  252 , and that items  214 ,  240 ,  242 , and  244  could represent only grounding elements in certain embodiments. 
     Also in  FIG. 6 , the traces are again shown as items  202  and  204  within the circuit board  200 , and the pressure switch is again shown as item  230 . The power/ground wiring circuit is shown as items  242  and  244 , and the data connection wiring circuit to the traces is shown as items  252 ,  254 . 
     Note that  FIG. 6  illustrates that when the paper tray  33  is fully inserted into the paper tray slot  212  of the printer, the power/ground wiring  242 ,  244  is electrically connected to the printer machine power/ground  214  through the paper tray slot power/ground connection  240 , which connects the traces  202 ,  204  to the printer machine power/ground  214 . Further, when the paper tray  33  is fully inserted into the paper tray slot  212  of the printer, the data wiring circuit  252 ,  254  is electrically connected to the tray slot data connection  250 , which connects the traces  202 ,  204  to the processor  60  to provide paper size data. If the paper tray  33  is not fully inserted into the paper tray slot  212 , the processor  60  will not detect any connection with either trace  202 ,  204 . 
     As shown in  FIG. 6 , the pressure switch  230  connects and disconnects one of the traces  202  to and from the power/ground connection  240  by opening or closing circuit  242  depending upon whether paper is present in the paper tray  33 . While the width trace  202  is shown as being connected to the pressure switch  230 , those ordinarily skilled in the art would understand that in other embodiments, a different trace such as the length trace  204  could be connected to the pressure switch  230  instead. 
     In this schematic, the width and length traces (sensors)  202 ,  204  cannot communicate data electrically with the processor  60  unless the traces  202 ,  204  are electrically connected to power/ground  240 ,  214 . Therefore, when media is on the pressure switch  230 , the pressure switch  230  rotates completing the electrical path  242  between the power/ground  240 ,  214  and the trace  202  and allowing the processor  60  to electrically communicate data with the trace  202  over data line  252 . To the contrary, trace  204  has an unbroken power/ground wire  244  and is always connected to the paper tray power/ground connection  240  (which, when the tray  33  is fully inserted into the printing machine paper tray slot  212 , is in turn connected to the printer machine power/ground  214 ). Therefore, trace  204  can always electrically communicate with the processor  60  whenever the tray  33  is fully inserted into the printer paper tray slot  212 , regardless of whether paper is in the paper tray  33 . 
     Thus, as shown above, with the structures herein, one trace (for this example the length trace  204 , but any trace could be used) is kept with its existing configuration. The other trace (e.g., width trace  202  in this example) however, has its power/ground circuit  242  altered, and the electrical power/ground circuit  242  to complete the circuit is instead run through the pressure switch  230  (that can be, for example, located on the lift plate  220  surface that paper rests on). 
     If paper is not present, the pressure switch  230  does not actuate, the circuit  242  is not completed, and only one of the two traces (the length trace  204  in this example) is recognized by the processor  60  of the printing machine. When the width trace circuit  242  is opened by the pressure switch  230  not having paper pressure, the width trace  202  is not recognized by the processor  60  of the printing machine, and no bucket information from the width trace  202  is received by the processor  60 . When this happens, software logic in the processor  60  then determines that, while the printer tray  33  is fully inserted into the paper tray slot  212  (as is known because the length sensor  204  is in communication with the processor  60 ), the tray lacks paper because the width sensor  202  is not in communication with the processor  60 . Once an operator opens the tray, loads paper, and recloses the tray, both the length and width traces  202 ,  204  will be in communication with the processor  60 . The processor  60  will then know that the tray is fully closed since both traces are complete, that paper is present in the tray, and (using the bucket information from the traces) what size paper is loaded in the machine. 
     Alternatively, the switch  230  and electrically connection element  234  could be included within one of the data wiring circuits  252 ,  254 , as shown in  FIG. 7 . Therefore, in this example, data circuit wiring  252  is connected and disconnected to and from the data connection  250  by the pressure switch  230 . Thus, again, the processor  60  receiving communication from only one of the traces ( 204 , in this example) would indicate that the pressure switch  230  has disconnected the other trace  202 , which the processor  60  interprets as a paper tray empty situation. Note that  FIG. 7  is substantially similar to the structure shown in  FIG. 6 , except that the positions of the power/ground connection  240  and data connection  250  are switched. 
     Thus, the structures herein provide a paper present sensor that utilizes another sensor while not diminishing the status resolution that the printing machine has in any area. The structures herein allow for the use of one sensor board to detect three unique and distinct situations: paper present; size of sheet; and tray open/closed. By using the paper lift tray  220  as the power/ground point to complete the circuit  242  when paper is in the tray, this lowers cost (which is useful to many programs and any cost reduction is important) and reduces wiring pin outs and harness size for each feed head. 
     As shown in to the  FIG. 8  a printing machine  10  is shown that includes an automatic document feeder  20  (ADF) that can be used to scan (at a scanning station  22 ) original documents  11  fed from a tray  19  to a tray  23 . The user may enter the desired printing and finishing instructions through the graphic user interface (GUI) or control panel  17 , or use a job ticket, an electronic print job description from a remote source, etc. The control panel  17  can include one or more processors  60 , power supplies, as well as storage devices  62  storing programs of instructions that are readable by the processors  60  for performing the various functions described herein. The storage devices  62  can comprise, for example, non-volatile storage mediums including magnetic devices, optical devices, capacitor-based devices, etc. 
     An electronic or optical image or an image of an original document or set of documents to be reproduced may be projected or scanned onto a charged surface  13  or a photoreceptor belt  18  to form an electrostatic latent image. The belt photoreceptor  18  here is mounted on a set of rollers  26 . At least one of the rollers is driven to move the photoreceptor in the direction indicated by arrow  21  past the various other known electrostatic processing stations including a charging station  28 , imaging station  24  (for a raster scan laser system  25 ), developing station  30 , and transfer station  32 . 
     Thus, the latent image is developed with developing material to form a toner image corresponding to the latent image. More specifically, a sheet  15  is fed from a selected paper tray supply  33  to a sheet transport  34  for travel to the transfer station  32 . There, the toned image is electrostatically transferred to a final print media material  15 , to which it may be permanently fixed by a fusing device  16 . The sheet is stripped from the photoreceptor  18  and conveyed to a fusing station  36  having fusing device  16  where the toner image is fused to the sheet. A guide can be applied to the substrate  15  to lead it away from the fuser roll. After separating from the fuser roll, the substrate  15  is then transported by a sheet output transport  37  to output trays a multi-function finishing station  50 . 
     Printed sheets  15  from the printer  10  can be accepted at an entry port  38  and directed to multiple paths and output trays  54 ,  55  for printed sheets, corresponding to different desired actions, such as stapling, hole-punching and C or Z-folding. The finisher  50  can also optionally include, for example, a modular booklet maker  40  although those ordinarily skilled in the art would understand that the finisher  50  could comprise any functional unit, and that the modular booklet maker  40  is merely shown as one example. The finished booklets are collected in a stacker  70 . It is to be understood that various rollers and other devices, which contact and handle sheets within finisher module  50  are driven by various motors, solenoids and other electromechanical devices (not shown), under a control system, such as including the microprocessor  60  of the control panel  17  or elsewhere, in a manner generally familiar in the art. 
     Thus, the multi-functional finisher  50  has a top tray  54  and a main tray  55  and a folding and booklet making section  40  that adds stapled and unstapled booklet making, and single sheet C-fold and Z-fold capabilities. The top tray  54  is used as a purge destination, as well as, a destination for the simplest of jobs that require no finishing and no collated stacking. The main tray  55  can have, for example, a pair of pass-through sheet upside down staplers  56  and is used for most jobs that require stacking or stapling 
     As would be understood by those ordinarily skilled in the art, the printing device  10  shown in  FIG. 8  is only one example and the embodiments herein are equally applicable to other types of printing devices that may include fewer components or more components. For example, while a limited number of printing engines and paper paths are illustrated in  FIG. 8 , those ordinarily skilled in the art would understand that many more paper paths and additional printing engines could be included within any printing device used with embodiments herein. 
     Many computerized devices are discussed above. Computerized devices that include chip-based central processing units (CPU&#39;s), input/output devices (including graphic user interfaces (GUI), memories, comparators, processors, etc. are well-known and readily available devices produced by manufacturers such as Dell Computers, Round Rock Tex., USA and Apple Computer Co., Cupertino Calif., USA. Such computerized devices commonly include input/output devices, power supplies, processors, electronic storage memories, wiring, etc., the details of which are omitted herefrom to allow the reader to focus on the salient aspects of the embodiments described herein. Similarly, scanners and other similar peripheral equipment are available from Xerox Corporation, Norwalk, Conn., USA and the details of such devices are not discussed herein for purposes of brevity and reader focus. 
     The terms printer or printing device as used herein encompasses any apparatus, such as a digital copier, bookmaking machine, facsimile machine, multi-function machine, etc., which performs a print outputting function for any purpose. The details of printers, printing engines, etc., are well-known by those ordinarily skilled in the art and are discussed in, for example, U.S. Pat. No. 6,032,004, the complete disclosure of which is fully incorporated herein by reference. The embodiments herein can encompass embodiments that print in color, monochrome, or handle color or monochrome image data. All foregoing embodiments are specifically applicable to electrostatographic and/or xerographic machines and/or processes. 
     In addition, terms such as “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “upper”, “lower”, “under”, “below”, “underlying”, “over”, “overlying”, “parallel”, “perpendicular”, etc., used herein are understood to be relative locations as they are oriented and illustrated in the drawings (unless otherwise indicated). Terms such as “touching”, “on”, “in direct contact”, “abutting”, “directly adjacent to”, etc., mean that at least one element physically contacts another element (without other elements separating the described elements). Further, the terms automated or automatically mean that once a process is started (by a machine or a user), one or more machines perform the process without further input from any user. 
     It will be appreciated that the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. 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. The claims can encompass embodiments in hardware, software, and/or a combination thereof. Unless specifically defined in a specific claim itself, steps or components of the embodiments herein cannot be implied or imported from any above example as limitations to any particular order, number, position, size, shape, angle, color, or material.