Patent Publication Number: US-7595912-B2

Title: Image forming system and method

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an image forming system and method, and more particularly to an image forming system and method using an image processing unit to which an optional paper feed unit or an optional paper output unit is connected. 
   2. Description of the Related Art 
   Conventionally, technology of a printer system has been proposed in which an optional paper feed unit or optional paper output unit is connected to an image forming apparatus. In such a system, when useless residual paper is present on a paper conveying path at power-on or before jam recovery, or when residual paper remains over a plurality of units, automatic paper output of the useless residual paper is started by carrying out paper conveyance operation of the individual units. Thus, the residual paper is automatically ejected to the outside of the apparatus accurately without causing undesirable damage to the residual paper (for example, see Japanese Patent Application Laid-open Nos. 09-011559/1997 and 09-104141/1997). 
   In the conventional technology, however, if the residual paper remains at a place where paper detecting sensors on the conveying path of the units cannot detect the residual paper even if it extends over the plurality of units, a condition occurs in which the units cannot start the conveyance operation at the same time. Accordingly, pulling or pushing of the residual paper occurs between the units, which can cause damage to both the residual paper and units. This hinders smooth automatic paper output, thereby presenting a problem in that a user must remove the residual paper to be ejected automatically as jam paper. 
   In addition, the check operation of the residual paper or the start or stop of the automatic paper output is not synchronized between the units. This offers a problem of excessive driving of the conveying path of the units, or of hindering the residual paper from being ejected to the outside without fail. 
   The present invention is implemented to solve the foregoing problems. It is therefore an object of the present invention to improve the usability by reducing the initializing time period of the apparatus by optimizing the detection processing of the residual paper in the apparatus at power-on or jam recovery and the timing of the start and stop processing of the automatic paper output. 
   SUMMARY OF THE INVENTION 
   To accomplish the objects, according to the present invention, there is provided an image forming system including a paper feed unit for supplying a recording medium, and an image forming unit for forming an image on the recording medium, the image forming system comprising: a recording medium detecting section for detecting the recording medium being conveyed through a conveying path of the paper feed unit; an instructing section for instructing the paper feed unit and the image forming unit to start operation to eject the recording medium, when the recording medium detecting section detects the recording medium; a first control section for causing the image forming unit to start recording medium conveyance operation in response to an operation start instruction by the instructing section; and a second control section for causing the paper feed unit to start recording medium conveyance operation in response to an operation start instruction by the instructing section, and for transmitting an operation completion signal of the paper feed unit to the instructing section when the conveyance operation has been completed, wherein the first control section decides completion of the recording medium conveyance operation of the image forming unit in response to the operation completion signal of the paper feed unit transmitted from the instructing section. 
   According to the present invention, there is provided a control method of an image forming system including a paper feed unit for supplying a recording medium, and an image forming unit for forming an image on the recording medium, the control method comprising: a first notification step of notifying an instructing section of the image forming unit of detecting the recording medium on a conveying path of the paper feed unit; an instruction step of causing the instructing section to instruct the paper feed unit and the image forming unit to start operation; a first control step of causing the image forming unit to start recording medium conveyance operation in response to an operation start instruction; a second control step of causing the paper feed unit to start recording medium conveyance operation in response to the operation start instruction; a second notification step of sending an operation completion signal to the instructing section when the recording medium conveyance operation of the paper feed unit has been completed; and a decision step of deciding completion of the recording medium conveyance operation of the image forming unit in response to an operation completion signal transmitted from the instructing section. 
   The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a structural diagram illustrating a mechanism of a first embodiment in accordance with the present invention; 
       FIG. 2  is a block diagram illustrating a circuit configuration of the first embodiment in accordance with the present invention; 
       FIG. 3  is a chart illustrating a sequence of the first embodiment in accordance with the present invention; and 
       FIG. 4  is a diagram showing the relationship of  FIGS. 4A and 4B ; 
       FIG. 4A  is a chart illustrating a sequence of a second embodiment in accordance with the present invention; and 
       FIG. 4B  is a chart illustrating a sequence of a second embodiment in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A recording medium decision unit and image forming unit and a method thereof in accordance with the present invention will now be described with reference to the accompanying drawings. 
   First Embodiment 
     FIG. 1  is a schematic diagram showing an image forming unit of a first embodiment in accordance with the present invention. In  FIG. 1 , an optional paper feed unit  101  includes a lower deck  104  and an upper deck  105 , and paper feed rollers  108  and  109  for feeding paper stacked on the decks. Downstream of a conveying roller  110  for supplying the paper from the deck  104  or  105  into a printer  102 , a paper outlet sensor  111  is disposed. 
   The printer  102  includes a lower deck  106  and upper deck  107  having a paper feed roller  112  and paper feed roller  113 , respectively. A paper feed sensor  114  in the printer detects the paper fed from the optional paper feed unit  101 , or the paper fed from the lower deck  106  or upper deck  107 . A paper feed conveying roller  115  for further conveying the paper feeds the paper up to the position at which a prescribed loop is formed by a registration roller  117 . A paper sensor (abbreviated to pre-regist sensor from now on)  116  for detecting the front edge of the paper being conveyed is provided for shaping the loop. The start timing of the rotation of the registration roller  117  is determined with reference to the detection timing of the front edge of the paper by the pre-regist sensor  116 . 
   To transfer the image formed on a photoconductive drum  118  to the paper accurately, the rotation start timing of the registration roller  117  is controlled. The registration roller  117  keeps its undriven state for a predetermined time period after the paper sensor  116  detects the front edge of the paper, in the course of which the paper is conveyed by a prescribed amount, thereby forming the loop of the paper. The registration roller  117  is driven after the predetermined time period so that the image on the photoconductive drum is transferred to the paper during the conveyance of the paper. After that, the paper to which the image is transferred is conveyed through a fixing unit  119  and fixed paper output roller  120 , and is ejected from the printer. A sensor  121 , which is disposed at the lowest position of the paper conveying path of the printer  102 , monitors the conveyance state of the paper to be output. 
   When an inlet sensor  122  detects the paper output from the printer  102 , an optional paper output unit  103  which is a recording medium paper output unit takes in and conveys the paper with a conveying roller  123 , and ejects the paper to the designated one of paper output bin  124 . 
     FIG. 2  is a block diagram illustrating an electric circuit of the image forming unit of an embodiment in accordance with the present invention. The image forming unit of the present embodiment assumes a configuration in which a video controller, which manages an image forming unit that will be described later, controls the operation of the optional paper feed unit  101  and optional paper output unit  103 . Such a configuration offers an advantage in that the processing load is reduced because the printer controller for controlling the image forming operation of the image forming unit need not manage the optional paper feed unit or optional paper output unit. In addition, when a new optional unit is introduced, it can be installed in the image forming unit by changing the control software on the video controller, which offers an advantage of increasing the flexibility of adding an optional unit. 
   In  FIG. 2 , a microcomputer (abbreviated to CPU from now on)  201  installed in the video controller for managing the image forming unit carries out processing of the image data and commands fed from the host, and controls by making communication with a microcomputer  202  (abbreviated to CPU  202  from now on) for controlling the optional paper feed unit  101 . In addition, the CPU  201  controls the individual units by carrying out communication such as serial communication with a microcomputer  203  (abbreviated to CPU  203  from now on) installed in the printer controller for controlling the printer  102  and with a microcomputer  204  (abbreviated to CPU  204  from now on) for controlling the optional paper output unit  103 . 
   A sensor input circuit  205  supplies the CPU  202  with a detection signal output from the outlet sensor  111  in the optional paper feed unit  101  which is a recording medium carrying-in unit. A driving circuit  206  of a motor  216  for rotating the conveying rollers  108 ,  109  and  110  of the optional paper feed unit  101  is controlled by a driving signal output from the CPU  202 . The CPU  202  causes paper to be fed and conveyed from a desired deck by carrying out the paper feed command and conveyance command fed from the CPU  201 . 
   Input circuits  207 ,  208  and  209  supply the CPU  203  with the detection signals of the paper feed sensor  114 , pre-regist sensor  116  and fixed paper output sensor  121  located on the conveying path in the printer. A driving circuit  210  of a main motor  220  that drives all the rollers in the printer and the photoconductive drum is controlled by the driving signal output from the CPU  203 . A driving circuit  211  of a clutch  221  for transmitting the rotation of the main motor  220  to the paper feed conveying roller  115  is controlled by a driving signal output from the CPU  203 . A driving circuit  212  of a clutch  222  for transmitting rotation of the main motor  220  to the registration roller  117  is controlled by a driving signal output from the CPU  203 . The CPU  203  causes the paper to be conveyed to the optional paper output unit  103  in response to a conveyance command fed from the CPU  201 . 
   The sensor input circuit  213  supplies the CPU  204  with a detection signal of the inlet sensor  122  of the optional paper output unit  103 . A driving circuit  214  of a motor  224  for rotating the conveying roller  123  of the optional paper output unit  103  undergoes ON/OFF control of the clutch in response to the driving signal output from the CPU  204 . The CPU  204  causes the paper to be conveyed from the printer  102  in response to the conveyance command fed from the CPU  201 . 
     FIG. 3  is a sequence chart illustrating the control sequence between the CPU  201  and CPU  202 , between the CPU  201  and CPU  203 , between the CPU  201  and CPU  204 , and between the CPU  202 , CPU  203  and CPU  204  at power-on or initialization after jam processing in the present embodiment. 
   The present embodiment is described by way of example in which the image forming unit includes no useless residual paper. 
   In  FIG. 3 , at step S 301 , since none of the conveyance sensors  114 ,  116  and  121  in the printer detect the residual paper, the CPU  203  notifies the CPU  201  that it is in a residual paper check start instruction waiting mode. Likewise, at step S 302 , since the conveying path sensor  111  in the optional paper feed unit  101  does not detect any residual paper, the CPU  202  notifies the CPU  201  that it is in a residual paper check start instruction waiting mode. 
   At step S 303 , since the inlet sensor  122  of the optional paper output unit  103  does not detect any residual paper, the CPU  204  notifies the CPU  201  that it is in a residual paper check start instruction waiting mode. After confirming that all the units are in the residual paper check start waiting mode, the CPU  201  provides a residual paper check start instruction to all the units simultaneously at step S 304 . 
   At step S 305 , the CPU  202 , receiving the residual paper check start instruction, drives the conveying roller  110  for the predetermined time period, and detects the residual paper by conveying it to the paper outlet sensor  111  if it remains upstream of the paper outlet sensor  111 . Unless the paper outlet sensor detects the residual paper even if driving the conveying roller  110  for the predetermined time period, the CPU  202  notifies the CPU  201  of the end of the residual paper check at step S 306 , stops driving the conveying roller  110 , and carries out the initializing processing at S 307 . Then at S 308 , the CPU  202  notifies the CPU  201  of the end of the initialization. The term “Initializing processing” refers to paper feed preparing processing of the paper feed unit such as lift up operation of a lifter (not shown) for holding recording mediums in the lower deck  106  or upper deck  107  in the optional paper feed unit  101 . 
   The CPU  203 , receiving the residual paper check start instruction from the CPU  201 , drives the main motor  220  in order to detect with a downstream sensor the residual paper between the paper outlet sensor  111  of the optional paper feed unit  101  and the paper feed sensor  114  (S 309 ). In addition, the CPU  203  drives the main motor  220  in order to detect with a downstream sensor the residual paper between the lower deck  106  or upper deck  107  and the paper feed sensor  114 , the residual paper between the paper feed sensor  114  and the pre-regist sensor  116 , and the residual paper between the pre-regist sensor  116  and the fixed paper output sensor  121 . Receiving the notification that the residual paper check of the optional paper feed unit  101  has been completed from the CPU  201  at step S 310 , the CPU  203  confirms that no residual paper is detected even by driving the main motor  220  for the predetermined time period, and notifies the CPU  201  of the end of the residual paper check (S 311 ). Following the completion of the residual paper check, the CPU  203  carries out the initializing processing such as starting the fixing unit and initializing the electrophotographic process for carrying out the image forming at step S 312 . 
   At step S 304 , the CPU  204 , receiving the residual paper check start instruction from the CPU  201 , starts the residual paper check for confirming as to whether the residual paper is present or not from the fixed paper output sensor  121  to the inlet sensor  122  at step S 313 . In addition, the CPU  204  drives the conveying roller  123  in order to eject all the residual paper from the inlet sensor  122  to the paper output bin  124  to the paper output bin. 
   Receiving the notification that the residual paper check of the printer  101  has been completed from the CPU  203  at step S 311 , the CPU  201  notifies the CPU  204  in the optional paper output unit  103  at step S 314 . Receiving the notification that the residual paper check of the printer  102  has been completed from the CPU  201  at step S 314 , the CPU  204  confirms that no residual paper is detected even after the predetermined time period has elapsed from the residual paper check start, and notifies the CPU  201  of the end of the residual paper check at step S 315 . In addition, the CPU  204  simultaneously starts the initialization of the paper output bin  124  (such as moving the paper output bin to its home position) at step S 316 . 
   After completing the initializing processing of the paper output bin  124 , the CPU  204  stops the driving of the optional paper output unit  103 , and notifies the CPU  201  of it at step S 317 . After completing the initializing step S 312  of the printer, the CPU  203  stops the driving of the printer, and notifies the CPU  201  of it at step S 318 . When the CPU  201  confirms the completion of the initialization of all the units, it makes a decision that the system is ready, and enables the print operation. 
   Thus, the CPU  201  issues the residual paper check start instruction to the printer  102 , optional paper feed unit  101 , and optional paper output unit  103  all at once. Subsequently, the residual paper check operation is completed in the order of the optional paper feed unit  101 →printer  102 →optional paper output unit  103 . Then, the initializing processing of the individual units is carried out successively after completing the residual paper check operation of the individual units. These operations are performed in response to the instructions from the CPU  201  with recognizing between the individual units that the residual paper check has been completed. As a result, the printer  102 , to which the optional paper feed unit  101  and optional paper output unit  103  are connected, can carry out the residual paper check and initializing operation optimally. This makes it possible to eliminate the useless operation such as driving the motors more than necessary for the residual paper check or initializing operation. 
   In addition, this makes it possible to detect the residual paper properly in shorter time, and to prevent the detected residual paper from being damaged, thereby being able to improve the usability. 
   Second Embodiment 
   The first embodiment is described by way of example in which the image forming unit includes no useless residual paper. The present embodiment will be described by way of example in which automatic paper output is carried out because the paper outlet sensor  111  of the optional paper feed unit detects the residual paper during the initialization at power-on or after jam processing. As for the configuration of the image forming unit in the present embodiment, the schematic view of  FIG. 1  is used as in the first embodiment, and as for the electric circuit of the image forming unit, the block diagram of  FIG. 2  is applicable. Accordingly, description of  FIG. 1  and  FIG. 2  will be omitted here because it is made in the first embodiment. 
     FIG. 4  is a sequence chart illustrating a control sequence of commands and status in communication between the CPU  201  and CPU  202 , between the CPU  201  and CPU  203 , and between the CPU  201  and CPU  204 , and a control flow of the CPU  202 , CPU  203  and CPU  204  at power-on or initialization after jam processing in the present embodiment. 
   In  FIG. 4 , at step S 401 , since none of the conveyance sensors  114 ,  116  and  121  in the printer detect the residual paper, the CPU  203  notifies the CPU  201  that it is in a residual paper check start instruction waiting mode. At step S 402 , detecting the residual paper with the paper outlet sensor  111 , the CPU  202  notifies the CPU  201  that the residual paper to be subjected to the automatic paper output is present. At step S 403 , since no residual paper is present in the optional paper output unit  103 , the CPU  204  notifies the CPU  201  that it is in a residual paper check start instruction waiting mode. 
   After receiving confirmation from all the units that they either include the residual paper to be subjected to the automatic paper output, or are in the residual paper check start waiting mode, the CPU  201  instructs all the units to prepare the automatic paper output simultaneously at step S 404  in order to carry out automatic paper output of the residual paper of the optional paper feed unit  101 . Receiving the automatic paper output preparing instruction at step S 404 , all the units prepare the automatic paper output at step S 405 , and notify the CPU  201  of the completion of the preparation of the automatic paper output at step S 406 , step S 407 , and step S 408  when the preparation has been completed. 
   Confirming that the preparation of the automatic paper output of all the units has been completed, the CPU  201  instructs all the units to start the automatic paper output operation simultaneously at step S 409 . Receiving the automatic paper output start instruction, the CPU  202  starts driving the conveying path roller at step S 410  to convey the residual paper on the paper outlet sensor to the printer  102 . After driving a predetermined time period, and when another predetermined time period has elapsed from the time when the paper present or absent state of the paper outlet sensor  111  changes from the paper presence to paper absence, the CPU  202  makes a decision that the residual paper has been transferred to the printer at the timing at which the rear edge of the paper has passed through the optional paper feed unit. Then, at step S 411 , the CPU  202  notifies the CPU  201  of the completion of the automatic paper output. In addition, simultaneously with the completion of the automatic paper output, the CPU  202  stops the driving of the optional paper feed unit, carries out the initializing processing at step S 412 , and notifies the CPU  201  of the completion of the initialization at step S 413 . The term “initializing processing” refers to paper feed preparing processing of the paper feed unit such as lift up operation of a lifter (not shown) for holding recording mediums in the lower deck  106  and upper deck  107  in the optional paper feed unit  101 . 
   Receiving the automatic paper output start instruction at step S 409 , the CPU  203  starts the automatic paper output by driving the main motor  220  at step S 414 . After receiving the notification that the optional paper feed unit  101  has completed the automatic paper output from the CPU  201  at step S 415 , the CPU  203  considers that the notification indicates that none of the sensors has detected the paper for a predetermined time period continuously. Subsequently, after a predetermined time period has elapsed, the CPU  203  makes a decision that the automatic paper output has been completed, and notifies the CPU  201  of the completion of the automatic paper output at step S 416 . Following it, the CPU  203  carries out the initializing processing such as starting the fixing unit and initializing the electrophotographic process at step S 417 . 
   The CPU  204 , receiving the automatic paper output instruction from the CPU  201  at step S 409 , drives the conveying roller  123  at step S 418  to start the automatic paper output operation. When the inlet sensor continues not detecting the paper for a predetermined time period after the CPU  204  receives the notification that the printer  102  has completed the automatic paper output from the CPU  201  at step S 419 , the CPU  204  makes a decision that the automatic paper output is completed. Then, the CPU  204  notifies the CPU  201  of the completion of the automatic paper output at step S 420 . Following that, the CPU  204  starts the initialization of the optional paper output unit  103  (such as moving the paper output bin to its home position) at step S 421 . 
   Receiving the notification that the automatic paper output has been completed from all the units, the CPU  201  makes a decision that the automatic paper output operation has been completed. After completing initializing step S 421  of the optional paper output unit  103 , the CPU  204  notifies the CPU  201  of the completion of the initialization at step S 422 . When initializing step S 417  of the printer  102  has been completed, the CPU  203  notifies the CPU  201  of the completion of the initialization at step S 423 . When the CPU  201  confirms the completion of the initialization of all the units, it makes a decision that the system is ready, and enables the print operation. 
   Thus, when the residual paper is detected in the optional paper feed unit  101 , for example, the CPU  201  issues the automatic paper output preparing instruction to the printer  102 , optional paper feed unit  101 , and optional paper output unit  103  all at once. Then, recognizing that all the units have completed the preparation of the automatic paper output, the CPU  201  issues the automatic paper output start instruction to all the units all at once, thereby completing the automatic paper output operation in the order of the optional paper feed unit→printer→optional paper output unit. 
   These operations are performed in response to the instructions from the CPU  201  with recognizing between the individual units that the residual paper check has been completed. As a result, the printer, to which the optional paper feed unit and optional paper output unit are connected, can carry out the automatic paper output operation optimally. This makes it possible to eliminate the useless operation such as driving the motors more than necessary for the automatic paper output operation. 
   As described above, according to the present invention, a conveyance control means is provided for sequentially driving each of a plurality of conveyance means along a series of the conveying paths after making a decision as to whether a recording medium remains on the series of the conveying paths with a plurality of recording medium detection means before making the image forming on the recording medium. This enables the optimization of the detection processing of the residual paper in the apparatus, which is carried out at power-on or jam recovery, and of the timing of the start/stop processing of the automatic paper output, thereby being able to improve the usability of the apparatus by reducing the initializing time period of the units. 
   The present invention has been described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspect, and it is the intention, therefore, in the apparent claims to cover all such changes.