Abstract:
A method is disclosed for raising a base having media thereon. In an example embodiment, the method includes first raising a base having media thereon, ceasing the raising the base upon detecting the media, detecting an absence of the media, and second raising the base upon the detecting the absence of the media.

Description:
BACKGROUND 
   Image forming devices, such as printers, copiers, and the like, are used to form images on media. In the past, advancing media from a media stack to a location of image formation has been problematic in some applications. For example, using encoders to control motion of a stack of media may be expensive in some situations. Moreover, use of damper devices in media handling devices may also be expensive to implement in some situations. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram of an example imaging device in accordance with an embodiment. 
       FIG. 2  is a schematic diagram of an example media handling device in accordance with an embodiment. 
       FIG. 3  is a flowchart illustrating a method in accordance with an example embodiment. 
       FIG. 4  is a flowchart illustrating a method in accordance with an example embodiment. 
   

   DETAILED DESCRIPTION 
     FIG. 1  schematically illustrates an example embodiment of an imaging device  100 . Example embodiments of the imagine device  100  include, but are not limited to, a printer, a copier, a multifunction device, or the like. The imaging device  100  is shown as including a print engine  102 , a media handling device  104 , a controller  106 , and an output  108 . In general, the imaging device  100  receives data, such as a print job at the controller  106 . The controller  106  then controls the media handling device  104  to advance media  110  to a print zone  112  adjacent the print engine  102 . The controller  106  may also control the print engine  102  to image the media  110 . The media  110  may then be advanced, such as by rollers (not shown), to the output  108 , such as an output tray. 
   The print engine  102  may be an ink jet print engine, an electrostatic print engine, or any other suitable print engine. The print engine  102  may be generally controlled by the controller  106  to form images on the media  110 . 
   The controller  106  may comprise a processor unit configured to direct the operation of one or more of the components of device  100 . For purposes of the disclosure, the term “processor unit” shall mean a conventionally known or future developed processing unit that executes sequences of instructions contained in a memory. Execution of the sequences of instructions causes the processing unit to perform steps such as generating control signals. The instructions may be loaded in a random access memory (RAM) for execution by the processing unit from a read only memory (ROM), a mass storage device, or some other persistent storage. In other embodiments, hard wired circuitry may be used in place of or in combination with software instructions to implement the functions described. Controller  106  is not limited to any specific combination of hardware circuitry and software, nor to any particular source for the instructions executed by the processing unit. In some embodiments, the controller  106  includes non-volatile memory for storing imaging device firmware. The controller firmware may comprise algorithms, such as those described herein, that are used by the controller  106  in controlling the print engine  102  and the media handling device  104 . 
   The media handling device  104  may be configured to include an input tray adapted to support a stack of media ( FIG. 2 ). In some example embodiments, the controller  106  may control the media handling device  104  based on the presence of a current print job, the position of the stack of media, the position of a cover ( FIG. 2 ) on the media handling device, or a combination of these. 
     FIG. 2  schematically illustrates components of an example embodiment of the media handling device  104  and controller  106 . As shown, the device  104  includes a motor  202  coupled to a base  204  via cabling  210  for raising and lowering the base  204  under control of the controller  106 . In one embodiment, the cabling  210  comprises multiple cables coupled to different portions of the base  204 . A media stack  208  is shown as being positioned on a top surface of the base  204 . A cover  206  may be provided to limit access to the media stack  208 . 
   Sensors  212  and  214  are coupled to the controller  106 . As discussed below, in some embodiments, the controller  106  drives the motor  202  based on at least one of the sensors  212 ,  214 . The sensor  212  may comprise a media stack sensor for detecting the presence of the media stack  208  at the sensor  212 , or a top surface of the media stack, at the sensor  212 . The sensor  214  may comprise a cover sensor for detecting a current position of the cover  206  (i.e., open position or closed position). In some embodiments, the sensors  212 ,  214  comprise limit switches. 
   The motor  202  may comprise an AC motor, a DC motor, or other suitable motor and has an output shaft  224 , around which the cabling  210  may be wound or unwound, depending on the rotational direction of the output shaft  224 . In an example embodiment, the motor  202  may be a 32 volt DC motor, although different motors may be employed. The cabling  210  passes pulleys  216 ,  218  before connecting to one end of the base  204  and passes pulleys  216 ,  220  before connecting to the other end of the base  204 . As such, as the output shaft  224  rotates in one direction, the cabling  210  lifts the base  204  and as the output shaft  224  rotates in an opposite direction, the cabling  210  lowers the base  204 . In some embodiments, the cabling  210  comprises two cables wrapped around the output shaft  224 . One of the cables extends across pulleys  216 ,  218  and connects at the left-hand side of the base  204  as shown in  FIG. 2 . The other of the cables extends across pulleys  216 ,  218 ,  220 , and connects at the right-hand side of the base  204  as shown in  FIG. 2 . 
   The controller  106  receives control signals from the sensors  212  and  214  via data conduits  230 ,  232 , respectively. The controller  106  sends control signals, power, or both, via conduit  234 . 
     FIG. 3  is a flowchart illustrating an example embodiment of controlling the device  104 . As shown in  FIG. 3 , the method may commence with the device  104  being in state A  302 . In state A, one or more of the following may occur: the controller  106  may cause power to be transmitted to the motor at a first duty cycle, the motor  202  may apply a first torque to the shaft  224 , and the base  204  raises toward the sensor  212 . In some embodiments, the first torque may be approximately an amount of torque sufficient to lift the heaviest expected load on the base  204 . The magnitude of the first torque, may, however, vary from one configuration to another. Consequently, in this embodiment, when the device is in state A  302 , the base  204  is moving toward the sensor  212 . 
   Next, at block  304 , the controller  106  determines whether media is detected at the sensor  212 . If media is detected at the sensor  212 , execution proceeds to block  306 , else execution proceeds to block  308 . That is, if media is detected at the sensor  212 , the base  204  is at a height sufficient for a top sheet of media of the stack of media  208  to be picked by a pick arm (not shown) or other suitable picking device. Hence, in some embodiments, the sensor  212  is positioned such that the sensor  212  detects media when the top sheet of media of the stack  208  is within a range of the pick arm. In particular embodiments, the sensor  212  may be positioned such that the sensor  212  detects the top sheet of the stack  208  when the top sheet is approximately in the middle of the pick arm range. The location of the sensor  212  may, however, vary from configuration to configuration and is not limited to those locations specifically described herein. 
   As mentioned above, if at block  304 , media is not detected at the sensor  212 , execution proceeds to block  308 , wherein the controller  106  determines whether the cover  206  is raised based on the sensor  214 . If the controller  106  determines that the cover  206  is raised, execution proceeds to block  312 , else execution returns to state a  302 . Hence, if the media is not detected at the sensor  212  and the cover is not raised, the device continues to operate in state A. 
   If, however, media is detected at the sensor  212  pursuant to block  304 , execution proceeds to state B  306 . In state B, one or more of the following may occur: the controller  106  may cause power to be transmitted to the motor at a second duty cycle, the motor  202  may apply a second torque to the shaft  224 , and the base  204  maintains the stack at its current position or moves slowly away from the sensor  212 . Here, the second duty cycle may be less than the first duty cycle and the second torque may be less than the first torque. 
   Next, at block  310 , the controller  106  determines whether media is detected at the sensor  212 . If media is detected at the sensor  212 , execution returns to block  306 , else execution proceeds to block  308 . Hence, the device  104  may remain in state B  306  until the controller  106  determines that media is no longer present at the sensor  212 . In some embodiments, media is picked from the stack  208  during state B  306 . 
   If media is not detected at the sensor  212  at either of blocks  304 ,  310 , execution proceeds to block  308 . At block  308  the controller  106  determines whether the cover  206  is raised based on the sensor  214 . If the controller  106  determines that the cover is raised at block  308  execution proceeds to state C  312 . In state C, one or more of the following may occur: the controller  106  may cause power to be transmitted to the motor at a third duty cycle, the motor  202  may apply a third torque to the shaft  224 , and the base  204  lowers or moves slowly away from the sensor  212 . The third duty cycle may be less than the first and second duty cycles. The third duty cycle may be zero or negative. Likewise, the third torque may be lower than the first and the second torques. The third torque may be zero or in a rotational direction opposite the first and second torques. Thus, pursuant to the embodiment of  FIG. 3 , the base  204  lowers when the cover  206  is raised. 
     FIG. 4  is a flowchart illustrating another embodiment of controlling the device  104 . As shown in  FIG. 3 , the method may commence with the device  104  being in state A  402 . In state A, one or more of the following may occur: the controller  106  may cause power to be transmitted to the motor at a first duty cycle, the motor  202  may apply a first torque to the shaft  224 , and the base  204  raises toward the sensor  212 . In some embodiments, the first torque may be approximately an amount of torque sufficient to lift the heaviest expected load on the base  204 . The magnitude of the first torque, may, however, vary from one configuration to another. Consequently, in this embodiment, when the device is in state A  402 , the base  204  is moving the base  204  toward the sensor  212 . 
   Next, at block  404 , the controller  106  determines whether media is detected at the sensor  212 , whether the cover  206  is closed, and whether a print job is present. If these three conditions are present, execution proceeds to state B  406 , else execution proceeds to block  405 . At block  405 , the controller  106  determines whether the cover  206  is closed and whether a print job is present. If the controller  106  determines that the cover  206  is closed and that a print job is present, then execution returns to state A  402 . Else, execution proceeds to state C  412 . 
   The controller  106  determines that a print job is present if the controller  106  has received a print job and the print job has not been cancelled or completed. 
   At block  406 , the device  104  is at state B. In state B, one or more of the following may occur: the controller  106  may cause power to be transmitted to the motor at a second duty cycle, the motor  202  may apply a second torque to the shaft  224 , and the base  204  maintains the stack at its current position or moves slowly away from the sensor  212 . Here, the second duty cycle may be less than the first duty cycle and the second torque may be less than the first torque. Hence, the second duty cycle and second torque, in some embodiments, are of sufficient magnitude and direction to maintain the base  204  at its current position or to permit the base  204  to move slowly downward, away from the sensor  212 . 
   Next, at block  408 , the controller  106  determines whether media is at the sensor  212 , whether the cover  206  is closed, and whether a print job is present. If these three conditions are satisfied, execution returns to state A  402 ; else execution proceeds to block  410 . At block  410 , the controller  106  determines whether the cover  206  is closed and whether a print job is present. If, pursuant to block  410 , the cover is closed and a print job is present, execution returns to state A  402 ; else execution proceeds to state C  412 . 
   In state C, one or more of the following may occur: the controller  106  may cause power to be transmitted to the motor at a third duty cycle, the motor  202  may apply a third torque to the shaft  224 , and the base  204  lowers or moves slowly away from the sensor  212 . The third duty cycle may be less than the first and second duty cycles. The third duty cycle may be zero or negative. Likewise, the third torque may be lower than the first and the second torques. The third torque may be zero or in a rotational direction opposite the first and second torques. Thus, pursuant to the embodiment of  FIG. 4 , the base  204  lowers when the cover  206  is raised. 
   Accordingly, in some embodiments, a method for elevating a media input tray may be employed without use of an encoder, complex gearing, or dampers. Instead, some embodiments employ a media sensor to determine the presence or absence of media in a pick zone (i.e., the zone in which a pick arm may pick a top sheet of media from a stack). Motor power, torque, or both may then be varied based on whether the media is present in the pick zone to move a media input tray in a manner to permit effective picking of media from the tray. 
   The foregoing description of various embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or limiting, and modifications and variations are possible in light of the above teachings or may be acquired from practice. The embodiments were chosen and described in order to explain the principles and application to enable one skilled in the art to utilize the claimed subject matter in various embodiments and with various suitable modifications.