Patent Publication Number: US-9427783-B2

Title: Postal matter ejection apparatus with gap setting unit according to postal matter thickness

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/178,489 filed Feb. 12, 2014, which is a divisional of U.S. patent application Ser. No. 13/778,375 filed Feb. 27, 2013, and is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-042104, filed Feb. 28, 2012, the entire contents of all of which are incorporated herein by reference. 
    
    
     FIELD 
     Embodiments described herein relate generally to a sheet ejection apparatus and a sheet processing apparatus. 
     BACKGROUND 
     For example, a sheet processing apparatus such as a mail sorting apparatus comprises a sheet ejection apparatus configured to eject sheets such as postal matters which are processing targets. Much of the sheet processing apparatuses process the sheets ejected by the sheet ejection apparatus while conveying them. However, the sheets having different thicknesses cannot be often conveyed at the same speed, even if a conveying mechanism operates at a constant speed. For example, when the thicknesses of the sheets increase, a conveying speed tends to be slow. If the conveying speed of each sheet is not constant, gaps between preceding and following sheets conveyed in the sheet processing apparatus vary. When the following sheet catches up the preceding sheet, the sheet processing apparatus cannot normally process the sheets, and hence the apparatus discharges both the following sheet and the preceding sheet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is an overall view of a sheet processing apparatus including a sheet ejection apparatus according to an embodiment; 
         FIG. 1B  is an overall view of the sheet processing apparatus including the sheet ejection apparatus according to the embodiment; 
         FIG. 2  is a control system diagram of the sheet processing apparatus depicted in  FIG. 1A  and  FIG. 1B ; 
         FIG. 3  is a view showing a first structural example of an ejection unit; 
         FIG. 4  is a flowchart for explaining ejection processing in the ejection unit according to the first structural example; 
         FIG. 5  is a view showing a second structural example of the ejection unit; and 
         FIG. 6  is a flowchart for explaining ejection processing in the ejection unit according to the second structural example. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, a sheet ejection apparatus includes an ejection unit, a thickness detection unit, a thickness storage unit, a sheet detection unit, an acquisition unit, a setting unit, and an adjustment unit. The ejection unit ejects a sheet that is to be conveyed to a conveyance path. The thickness detection unit measures a thickness of the sheet ejected by the ejection unit. The thickness storage unit stores thickness information detected by the thickness detection unit. The sheet detection unit detects the sheet ejected by the ejection unit. The acquisition unit acquires from the thickness storage unit a thickness of a preceding sheet conveyed to the conveyance path prior to the sheet ejected by the ejection unit. The setting unit sets a gap between the preceding sheet and the sheet ejected by the ejection unit in accordance with the thickness of the preceding sheet acquired by the acquisition unit. The adjustment unit adjusts timing for supplying the sheet detected by the sheet detection unit to the conveyance path in accordance with the gap set by the setting unit. 
     An embodiment will be described hereinafter with reference to the drawings. 
     A sheet processing apparatus according to this embodiment is configured to process respective sheets wile sequentially conveying the sheets. For example, as the sheet processing apparatus, assumed is a mail sorting device or the like that sorts postal matters (postcards, sealed matters, and others) as sheets in accordance with destination information (sorting information), e.g., an address or a postal code and accumulates the sorted sheets. Further, the sheet processing apparatus according to this embodiment comprises an ejection unit as a sheet ejection apparatus that ejects a sheet as a processing target from a supply unit and conveys it to a conveyance path in the sheet processing apparatus. For example, the sheet ejection apparatus according to this embodiment can be used as an ejection unit that ejects a postal matter which is a processing target in the mail sorting device. 
     Furthermore, the mail sorting device as an example of the sheet processing apparatus carries out the following processing as processing for postal matters as sheets. The mail sorting device ejects postal matters one by one and sequentially conveys the postal matters. The mail sorting device reads an image on each postal matter to be conveyed by using a scanner and recognizes destination information such as an address and a postal code from the read image of each sheet. The mail sorting device associates stackers provided in an accumulation unit with various kinds of destination information (sorting information for delivery) in advance and decides a stacker as a sorting destination of each postal matter based on recognition result of the destination information for the read image of each postal matter. The mail sorting device conveys each sheet to the stacker decided as the sorting destination and accumulates it. 
     Each of  FIG. 1A  and  FIG. 1B  shows a structural example of a sheet processing apparatus  1  according to an embodiment.  FIG. 1A  shows a structural example of various modules in the sheet processing apparatus  1 .  FIG. 1B  shows a structural example of appearance when the sheet processing apparatus  1  depicted in  FIG. 1A  is shown from its side surface. As the sheet processing apparatus  1  shown in  FIG. 1A  and  FIG. 1B , assumed is a mail sorting device that sorts each postal matter (e.g., a letter or a sealed matter) as a sheet based on sorting information as destination information, e.g., an address and postal code. 
     In the structural example shown in  FIG. 1A , the sheet processing apparatus  1  comprises processing modules such as an operation panel  10 , a supply unit  11 , an ejection unit  12 , a conveyance unit (conveyance path)  13 , a discharge unit  14 , a pre-barcode read unit  15 , a character recognition unit  16 , a print unit  17 , a verify barcode read unit  18 , a branch unit, and an accumulation unit  20 . Additionally, the sheet processing apparatus  1  has a control system comprising control units that control operations of the respective modules and a control unit that integrally controls the control units of the respective modules. It is to be noted that a structural example of the control system will be described later. 
     The operation panel  10  functions as a user interface. The operation panel  10  has, e.g., an operation unit and a display unit. The operation panel  10  is constituted of, e.g., a display device having a built-in touch panel as the operation unit. Further, the operation panel  10  may be constituted of a keyboard as the operation unit and a display device as the display unit. 
     The operation panel  10  as the operation unit accepts input of various operations performed by an operator. The operation panel  10  transmits a signal indicative of input operation contents to the control unit. The operation panel  10  as the display unit displays a screen generated by the control unit. For example, the operation panel  10  displays various kinds of operation guidance, processing results, and others to the operator. 
     The supply unit  11  stocks the sheets as processing targets. The supply unit  11  is set while having the sheets as sorting processing targets overlapping therein. As each sheet that is a sorting processing target, assumed is a sheet having a character string indicative of a sorting destination written on a first surface thereof. For example, the character string representing a sorting destination may be a character string representing a destination such as an address or a postal code. For example, the sheets are set in the supply unit  11  with their trailing ends being trued up in such a manner that the first surfaces face the same direction. The supply unit  11  sequentially supplies the sheets to the ejection unit  12  installed at an ejecting position. 
     The ejection unit  12  ejects the sheets set in the supply unit  11  one by one at predetermined gaps. The ejection unit  12  functions as a sheet ejection apparatus that ejects postal matters as the sheets which are processing targets. The ejection unit  12  supplies the sheets ejected from the supply unit  11  to a conveyance path of the conveyance unit  13 . The ejection unit  12  has a later-described ejection roller, a delivery roller, various sensors, and others. For example, when the ejection roller installed in contact with a sheet placed at an end portion (the ejecting position) of the supply unit  11  rotates, the ejection unit  12  ejects the sheets set in the supply unit  11  one by one from the end portion of the supply unit  11 . The ejection unit  12  delivers the sheets ejected by the ejection roller to the conveyance unit  13  by using the delivery roller. A structural example of the ejection unit  12  will be described later in detail. 
     The conveyance unit  13  has a conveyance path along which the sheets are conveyed to the respective units in the sheet processing apparatus  1 . The conveyance path as the conveyance unit  13  is constituted of conveyance mechanisms, e.g., a conveyance roller, a conveyance belt, and a drive pulley. The drive pulley is driven by a drive motor, and the conveyance belt is operated by the drive pulley. The conveyance unit  13  conveys the sheets ejected by the ejection unit  12  by operating the conveyance path constituted of the conveyance mechanism, e.g., the conveyance belt at a constant speed. Furthermore, sensors and gates are set respective positions on the conveyance path in the sheet processing apparatus  1 . A control system of the sheet processing apparatus  1  sequentially controls the gates or the like in accordance with a processing result of each module and controls conveyance of the sheets using the conveyance path. 
     The discharge unit  14  is provided on the conveyance unit  13 . The discharge unit  14  detects and discharges each sheet which cannot be subjected to subsequent processing. For example, the discharge unit  14  judges whether the subsequent processing can be performed with respect to each sheet. The discharge unit  14  comprises a non-illustrated discharge and accumulation unit. The discharge and accumulation unit accumulates sheets which have been determined to be inappropriate for the subsequent processing (sheets determined to be discharged). 
     The discharge unit  14  has a length detection unit, a thickness detection unit, and a hardness detection unit. The length detection unit detects a length of each sheet in a conveyance direction. The discharge unit  14  detects each sheet whose length is outside the scope of specifications (which cannot be processed) by using the length detection unit. The thickness detection unit detects a thickness of each sheet. The discharge unit  14  detects each sheet whose thickness is outside the scope of specifications (which cannot be processed) by using the thickness detection unit. The hardness detection unit detects hardness of each sheet. The discharge unit  14  detects each sheet whose hardness is outside the scope of specifications (which cannot be processed) by using the hardness detection unit. The discharge unit  14  discharges each sheet whose length, thickness, or hardness has been detected as being outside the scope of specification. 
     Furthermore, the discharge unit  14  has a foreign substance detection unit, a metal detection unit, a state detection unit, and an overlap detection unit. The foreign substance detection unit detects each sheet containing a foreign substance that may possibly cause inconveniences in subsequent processing. The metal detection unit detects each sheet containing a metal that may possibly cause inconveniences in subsequent processing. The state detection unit detects each sheet which has a shape and a conveyance state that may possibly cause inconveniences in subsequent processing. The overlap detection unit detects sheets that are conveyed in overlapping state. 
     The discharge unit  14  discharges each sheet from which a foreign substance has been detected by the foreign substance detection unit, each sheet from which a metal has been detected by the metal detection unit, each sheet which has been detected to have a non-standard shape by the state detection unit, each sheet which has been detected to be in an abnormal conveyance state by the state detection unit, or each sheet which has been detected to be in an overlapping state by the overlap detection unit. 
     The pre-barcode read unit  15  reads a barcode previously given to each sheet that is conveyed on the conveyance path. The pre-barcode read unit  15  converts the read barcode into information indicative of a sorting destination. The pre-barcode read unit  15  transmits the information indicative of the sorting destination obtained from the read barcode (sorting information) to the control unit. The control unit determines a conveyance destination of the sheet based on the sorting information received from the pre-barcode read unit. The control unit controls each unit to accumulate the sheet on the determined conveyance destination. 
     The character recognition unit  16  recognizes characters written on the first surface of the sheet conveyed on the conveyance path. The character recognition unit  16  reads an image on the first surface of the sheet by using a scanner and recognizes characters from the image read by the scanner. The character recognition unit  16  transmits a character recognition result including the sorting information of the sheet to the control unit. The control unit generates the sorting information based on the character recognition result received from the character recognition unit  16  and determines a sorting destination associated with the sorting information. 
     For example, it is assumed that the sheet is a postal matter having characters representing a destination such as an address or a postal code written on the first surface thereof. In this case, the character recognition unit  16  reads an image on the first surface of the postal matter by using the scanner, the scanned image is subjected to OCR processing, and the destination, e.g., the address and the postal code written on the postal matter is recognized. The character recognition unit  16  transmits a character recognition result, e.g., the address and the postal code to the control unit as destination information. The control unit determines a sorting destination of the postal matter based on the destination information received from the character recognition unit  16 . 
     The print unit  17  prints the sorting information representing the sorting destination on the sheet. The print unit  17  prints a barcode representing the sorting information on the sheet. It is satisfactory for the barcode that is printed on the sheet by the print unit  17  to be readable by the barcode read units  15  and  18 . For example, the print unit  17  prints a barcode representing the sorting information on the sheet with an ink that cannot be recognized by human eyes. It is to be noted that the print unit  17  may be configured to print a two-dimensional code as the barcode that is printed on the sheet. The sorting information is converted into the barcode. 
     The verify barcode read unit  18  reads an image including the barcode that is printed by the print unit  17  from the sheet. The verify barcode read unit  18  converts the image of the read barcode into information. The verify barcode read unit  18  transmits the information acquired from the barcode to the control unit as sorting information. The control unit decides a sorting destination (a stacker in the accumulation unit  20 ) of the sheet based on the sorting information received from the verify barcode read unit  18 . 
     The branch unit  19  distributes each sheet under control of the control system. The branch unit  19  has gates that distribute sheets. Each gate of the branch unit  19  distributes sheets to any one of step paths (which will be described later) leading to the respective stackers of the later-described accumulation unit  20 . That is, the control system of the sheet processing apparatus  1  controls an operation of each gate of the branch unit  19  based on the sorting information of each sheet and thereby sends each sheet to any one of the step paths. 
     The accumulation unit  20  is constituted of modules M (M 1 , M 2 , M 3 , . . . ). Each module M has the stackers that accumulate sheets. For example, each module M has 16 stackers forming four stages and four columns. The number of the stackers in the entire accumulation unit  20  is the number obtained by adding the number of the stackers of all the modules. The sorting information is associated with each stacker. For example, in a mail sorting device, each destination as the sorting information is assigned to each stacker so that postal matters as sheets are aligned in the delivery order. 
     The accumulation unit  20  has step paths configured to convey each sheet distributed by the branch unit  19  to each module M. In the accumulation unit  20 , the respective modules M are coupled in accordance with each step path. The step path is a conveyance path configured to convey each sheets to the respective stackers arranged in a matrix form in each module. 
     Further, the accumulation unit  20  comprises gates. Each gage is provided in association with each stacker. Each gate is a mechanism that takes in each sheet conveyed by the step paths in the accumulation unit  20  into each stacker. The control system drives each gate at timing for taking each sheet into each stacker from the step path. Each gate that has been turned on guides the sheet conveyed through each step path into each corresponding stacker. Each sheet led from each step path by the gate is taken into the stacker by a taking roller or the like. Each sheet that has been taken in is accumulated in each stacker in order. 
     The control system performs control to accumulate each sheet having the determined sorting information into the stacker associated with the sorting information in the accumulation unit  20 . The control system distributes each sheet to each step path configured to convey the sheet to each stacker corresponding to the sorting information by each gate in the branch unit  19 . The control system operates each gate associated with the stacker corresponding to the sorting information in accordance with conveyance timing for the sheet on the step path in the accumulation unit  20 . As a result, the sheet sorted based on the sorting information is accumulated in each stacker in the accumulation unit  20 . A configuration of the control system of the sheet processing apparatus  1  will now be described. 
       FIG. 2  is a block diagram showing a structural example of the control system of the sheet apparatus  1 . 
     The sheet processing apparatus  1  comprises a control unit  101 , a panel control unit  111 , an ejection control unit  121 , a conveyance control unit  131 , a discharge control unit  141 , a determination control unit  151 , a print control unit  171 , and a sorting control unit  191  as structures in the control system. 
     The control unit  101  integrally controls operations of the respective units in the sheet processing apparatus  1 . The control unit  101  comprises a CPU, a buffer memory, a program memory, a nonvolatile memory, and others. The CPU executes various kinds of arithmetic processing. The buffer memory temporarily stores a result of an arithmetic operation executed by the CPU. The program memory and the nonvolatile memory store various programs executed by the CPU, control data, and others. The control unit  101  can perform various kinds of processing when the CPU executes programs stored in the program memory. 
     The panel control unit  111  controls the operation panel  10  that displays a processing status of each sheet or abnormality information of the device. It is to be noted that the operation panel  10  is constituted of, e.g., a display device having a built-in touch panel that can display information and allow input of operations. 
     The ejection control unit  121  controls conveyance of each sheet in and around the ejection unit  12 . The ejection control unit  121  controls operations such as ejection of sheets from the supply unit  11  and delivery of the ejected sheets to the conveyance path. For example, the ejection control unit  121  comprises a CPU  121   a , an RAM  121   b , an ROM (a program memory)  121   c , a nonvolatile memory  121   d , a timer  121   e , a parameter table  121   f , and others. 
     The CPU  121   a  executes various kinds of arithmetic processing. The RAM  121   b  temporarily stores a result of each arithmetic operation executed by the CPU  121   a . For example, a detection result obtained by the sensor that detects a state of each ejected sheet is stored in the RAM  121   b . The ROM  121   c  and the nonvolatile memory  121   d  store various programs executed by the CPU  121   a , control data, and others. The ROM  121   c  is constituted of, e.g., a non-rewritable nonvolatile memory, and the nonvolatile memory  121   d  is constituted of a writable nonvolatile memory. The ejection control unit  121  can realize various control functions by executing programs stored in the ROM  121   c  or the nonvolatile memory  121   d  by using the CPU  121   a . Furthermore, the timer  121   e  measures a time. 
     The parameter table  121   f  may be provided in, e.g., the ROM  121   c  or the nonvolatile memory  121   d  in the ejection control unit  121 . The parameter table  121   f  stores data that is used for setting timing for delivering each sheet ejected from the supply unit  11  to the conveyance path of the conveyance unit  13 . For example, in the parameter table  121   f , as data that should be set to control delivery of each sheet in accordance with a thickness of a preceding sheet (or a relative thickness difference from the preceding sheet), data representing, e.g., rotation timing, a rotation speed, or acceleration time of a delivery roller  127 . 
     Delivery timing of each sheet represented by the data stored in the parameter table  121   f  is used to adjust a conveyance interval (GAP) between a sheet to be delivered and a sheet that has been delivered immediately before the former sheet (a preceding sheet). That is, the ejection control unit  121  controls delivery timing of each sheet ejected from the supply unit  11  based on the data set in the parameter table  121   f  and thereby adjusts the conveyance interval (GAP) between two sheets conveyed in sequence on the conveyance path of the conveyance unit  13 . 
     A drive circuit  122  is connected to the ejection control unit  121 . The drive circuit  122  is a circuit that drives a motor  123 . The motor  123  drives an ejection roller  124  provided in the ejection unit  12 . The ejection roller  124  is a roller configured to eject each sheet from the supply path  11 . That is, the ejection control unit  121  controls the drive circuit  122  and thereby controls ejection of each sheet effected by the ejection roller  124  that is operated by the motor  123 . 
     Moreover, a drive circuit  125  is connected to the ejection control unit  121 . The drive circuit  125  is a circuit that drives a motor  126 . The motor  126  drives a delivery roller  127  provided in the ejection unit  12 . The delivery roller  127  is a roller configured to supply each sheet ejected by the ejection roller  124  to the conveyance path of the conveyance unit  13  in the sheet processing apparatus  1 . The ejection control unit  121  controls the drive circuit  125  and thereby controls delivery of each sheet effected by the delivery roller  127  that is operated by the motor  126 . 
     It is to be noted that the ejection roller  124  driven by the motor  123  may be configured to supply each sheet ejected from the supply unit  11  to the conveyance path of the conveyance unit  13 . In this case, in the ejection unit  12 , the drive circuit  125  and the motor  126  that drive the delivery roller  127  may be omitted, and the ejection control unit  121  may be configured to control timing for supplying each sheet ejected from the supply unit  11  to the conveyance path of the conveyance unit  13  by controlling driving of the ejecting roller  124 . 
     Additionally, each sensor provided in and around the ejection unit  12  is connected to the ejection control unit  121 . For example, a GAP measurement sensor (a detection sensor)  128  configured to detect a leading end and a trailing end of each ejected sheet is connected to the ejection control unit  121 . Further, a thickness measurement sensor  129  configured to detect a thickness of each ejected sheet is connected to the ejection control unit  121 . The thickness measurement sensor  129  measures a thickness of each sheet by using, e.g., a sensor that detects reflection of a laser beam. 
     The conveyance control unit  131  controls the conveyance unit  13 . The conveyance unit  13  conveys each sheet supplied from the ejection unit  12  through the conveyance path in the sheet processing apparatus. The conveyance control unit  131  operates a conveyance mechanism constituting the conveyance path in the sheet processing apparatus at a constant speed and thereby carries out conveyance control for conveying each sheet to each unit. 
     The discharge control unit  141  controls discharge processing of each sheet effected by the discharge unit  14 . The discharge control unit  141  checks whether each sheet should be discharged in accordance with a detection result of each sensor provided in the discharge unit  14 . The discharge control unit  141  executes control for discharging each sheet determined to be discharged. 
     The determination control unit  151  determines sorting information of each sheet (e.g., a destination such as an address and a postal code). The determination control unit  151  supplies the sorting information of each sheet to the control unit  101 . The determination control unit  151  acquires a barcode read result obtained by the pre-barcode read unit  15 , a character recognition result as the sorting information obtained by the character recognition unit  16 , or a barcode read result obtained by the verify barcode read unit  18 . The determination control unit  151  determines the sorting information of each sheet based on information acquired from the pre-barcode read unit  15 , the character recognition unit  16 , or the verify barcode read unit  18 . 
     The determination control unit  151  is connected to a barcode read unit (BCR) communication circuit  152 , a barcode read unit (BCR) communication circuit  153 , and a character recognition unit (OCR) communication circuit  154 . 
     The BCR communication circuit  152  is connected to the pre-barcode read unit  15 . The BCR communication circuit  152  supplies the sorting information based on a barcode read by the pre-barcode read unit  15  to the determination control unit  151 . Additionally, the BCR communication circuit  153  is connected to the verify barcode read unit  18 . The BCR communication circuit  153  supplies the sorting information based on a barcode read by the verify barcode read unit  18  to the determination control unit  151 . Further, the OCR communication circuit  154  is connected to the character recognition unit  16 . The OCR communication circuit  154  supplies to the determination control unit  151  a character recognition result like the sorting information obtained by OCR processing with respect to an image on the sheet read by the character recognition unit  16 . 
     The print control unit  171  controls printing effected by the print unit  17 . The print control unit  171  prints a barcode representing sorting information on the first surface of the sheet by using the print unit  17 . 
     The sorting control unit  191  executes conveyance control over each sheet in the branch unit  19  and the accumulation unit  20 . To the sorting control unit  191  are connected a motor drive mechanism, a gate drive mechanism, respective sensor groups, and others. 
     For example, the sorting control unit  191  controls an operation of each gate as the branch unit  19 . The sorting control unit  191  determines each stacker in which each sheet should be accumulated and operates each gate as the branch unit  19  so that each sheet can be distributed to each step path in the accumulation unit  20  configured to convey each sheet to a stacker that serves as an accumulating position. 
     Furthermore, the sorting control unit  191  controls conveyance of each sheet in the accumulation unit  20  and driving of each gate associated with each stacker. For example, each gate associated with each stacker is provided to each step path of the accumulation unit  20 . Moreover, a sensor that detects presence/absence of a sheet is provided at each position of each step path in the accumulation unit  20 . As a result, the sorting control unit  191  determines a conveyance status, e.g., a position of each sheet on each step path based on a detection signal from each sensor. The sorting control unit  191  controls driving of each gate associated with each stacker that should accumulate each sheet in accordance with, e.g., a conveyance status of each sheet on each step path in the accumulation unit. 
     A configuration of the ejection unit  12  will now be described. 
     A first structural example of the ejection unit  12  will be first explained. 
       FIG. 3  is a view schematically showing an ejection unit  12 A as the first structural example of the ejection unit  12 . 
     The ejection unit  12 A shown in  FIG. 3  is a structural example of the ejection unit  12  in the sheet processing apparatus  1 , and the ejection unit  12 A and the ejection control unit  121  constitute the sheet ejection apparatus. Additionally, the ejection unit  12 A ejects sheets one by one from the supply unit  11  having a supply base in which the sheets as processing targets are collectively set. Further, the ejection unit  12 A supplies the sheets ejected from the supply unit  11  to the conveyance unit  13 . 
     The ejection unit  12 A as the first structural example of the ejection unit  12  depicted in  FIG. 3  comprises the ejection roller  124 , the delivery roller  127 , the GAP measurement sensor (a sheet detection sensor)  128 , a thickness measurement sensor  129  ( 129   a  or  129   b ) for measuring a thickness, guide plates  202 ,  203 , and  204 , pressure rollers  205 ,  206 , and  207  for pressing sheets, and others. 
     Further, in the structural example shown in  FIG. 3 , the supply unit  11  comprises a supply base  11   a  on which sheets are set and an ejection feed belt  11   b  that pushes the sheets on the supply base  11   a  toward the ejection roller  124  side. In the supply unit  11 , sheets (sheets as processing targets) S that are to be taken into the sheet processing apparatus  1  are aligned and stocked on the supply base  11   a . The feed belt  11   a  is provided on the supply base  11   a . The feed belt  11   b  pushes the sheets S stocked on the supply base  11   a  along a direction of an ejection port. 
     In the ejection unit  12 A, the ejection roller  124  ejects the sheets set on the supply base  11   a  of the supply unit  11  one by one from the ejection port side. The ejection roller  124  conveys each sheet ejected from the supply base  11   a  along the conveyance direction. Each sheet ejected by the ejection roller  124  is pressed by the guide plate  202  through the pressure roller  205  and conveyed toward the delivery roller  127  along the guide plate  202  in this state. 
     The delivery roller  127  operates in response to an operating instruction issued by the control system and adjusts a gap (GAP) from a preceding sheet. For example, the delivery roller  127  rotates by the motor  126  driven based on control effected by the ejection control unit  121 , controls delivery timing for each sheet, and thereby functions as a GAP compensation unit that adjusts the gap (GAP) from the preceding sheet. The delivery roller  127  is installed to face the pressure roller  206  for pressing each sheet. The pressure roller  206  is installed to be movable in accordance with a thickness of each sheet that passes between the delivery roller  127  and the pressure roller  207 . As a result, the delivery roller  127  and the pressure roller  206  sandwich each sheet therebetween with appropriate force and send the sheet by using rotation of the delivery roller  127 . Furthermore, the guide plate  203  that leads each sheet supplied from the ejection roller  124  side to a space between the delivery roller  127  and the pressure roller  206  is provided near the delivery roller  127 . 
     Moreover, as a sensor configured to measure the gap (GAP) from a preceding sheet, the GAP measurement sensor (the sheet detection sensor)  128  that determines a contact position of the delivery roller  127  and the pressure roller  206  or the vicinity of this contact position as a detecting position is provided in the ejection unit  12 A. The sheet detection sensor  128  as the GAP measurement sensor supplies a detection signal indicative of whether a sheet is present at the detecting position to the ejection control unit  121 . For example, the conveyance control unit  121  determines that a leading end of a sheet has reached the detecting position when the GAP measurement sensor  128  detected the sheet, and it determines that a trailing end of the sheet has passed the detecting position when the detected sheet is no longer detected. 
     Moreover, as to each sheet ejected by the ejection roller  124 , if its leading end in the conveyance direction has reached the detecting position of the GAP measurement sensor (the sheet detection sensor)  128 , the gap (GAP) from a preceding sheet is adjusted by the delivery roller  127  and the pressure roller  206 . For example, the ejection control unit  121  may temporarily stop the conveyance when the GAP measurement sensor  128  detected the end of the sheet ejected by the ejection roller  124  in the conveyance direction (when the end of the sheet reached the space between the delivery roller  127  and the pressure roller  206 ), operate the delivery roller  127  at desired timing (delivery timing according to the set GAP), and thereby control (adjust) timing for sending the sheet to the conveyance path as the conveyance unit  13  in the sheet processing apparatus  1 . 
     Additionally, the ejection control unit  121  determines the gap (GAP) from the preceding sheet when the GAP measurement sensor  128  detects the end of the sheet. When the ejection control unit  121  has received a detection signal indicating that the end of the sheet was detected from the GAP measurement sensor  128 , it determines the gap based on, e.g., an elapsed time after the trailing end of the sheet sent immediately before the counterpart (the preceding sheet) passed the GAP measurement sensor  128 . For example, the gap from the preceding sheet is determined based on a time required until the leading end of the sheet reaches the GAP measurement sensor  128  after the trailing end of the preceding sheet passes the GAP measurement sensor  128  and a conveyance speed of the conveyance unit  13 . Further, a position of the preceding sheet may be identified by, e.g., a sensor provided on the conveyance path of the conveyance unit  13 , and then a gap between the preceding sheet and the sheet as a processing target may be determined based on the position of the preceding sheet and the detecting position of the GAP measurement sensor  128 . 
     Furthermore, in the ejection unit  12 A according to the first structural example is provided the thickness measurement sensor  129  ( 129   a  or  129   b ) configured to detect a thickness of each sheet before the leading end of the sheet ejected by the ejection roller  124  reaches the contact position of the delivery roller  127  and the pressure roller  206  (the detecting position of the GAP measurement sensor  128 ). The thickness measurement sensor (a thickness sensor)  129  is a sensor that measures a thickness of each sheet by using a reflective sensor or the like. In the structural example depicted in  FIG. 3 , as an installation example of the thickness measurement sensor (the thickness sensor)  129 , the thickness measurement sensors  129   a  and  129   b  are shown. 
     For example, the thickness measurement sensor  129   a  detects a thickness of each sheet that passes above the guide plate  202  by using a reflective sensor provided at a position where it faces a surface of the guide plate  202 . Since the sheet is pressed against the guide plate  202  by the pressure roller  205 , the thickness measurement sensor  129   a  can detect the thickness of the sheet with the surface of the guide plate  202  determined as a reference. Further, the thickness measurement sensor  129   b  detects the thickness of the sheet that passes above the guide plate  203  by using a reflective sensor installed at a position where it faces the surface of the guide plate  203 . Since the sheet is pressed against the guide plate  203  by the pressure roller  206 , the thickness measurement sensor  129   b  can detect the thickness of the sheet with the surface of the guide plate  203  determined as a reference. 
     The ejection control unit  121  stores data representing the thickness of the sheet measured by the thickness measurement sensor  129  (thickness information) in the RAM  121   b . When the GAP measurement sensor  128  has detected a sheet, the ejection control unit  121  determines a gap (GAP) between this sheet and a preceding sheet and reads the thickness information of the preceding sheet from the RAM  121   b . When the gap from the preceding sheet and the thickness of the preceding sheet have been identified, the ejection control unit  121  sets the gap (GAP) associated with the thickness of the preceding sheet by making reference to the parameter table  121   f  and decides delivery timing for the sheet associated with the gap from the preceding sheet. 
     For example, if the preceding sheet has a larger thickness than the sheet to be supplied (if the preceding sheet is a sheet thicker than a predetermined thickness (which may be also referred to a thick matter hereinafter) or if the thickness of the preceding sheet is larger than the thickness of the sheet in question by a predetermined value or a higher value), the ejection control unit  121  sets a thick matter GAP as a gap (GAP) from the preceding sheet and supplies the sheet so that a conveyance (feed) gap from the preceding sheet can be a GAP for the thick matter. 
     The thick matter GAP is a GAP wider than the regular GAP, and it is a GAP that is set to prevent the sheet to be fed from catching up the preceding sheet. Setting information, e.g., the regular GAP and the thick matter GAP is stored in the parameter table  121   f  in advance, and the ejection control unit  121  sets one of the regular GAP and the thick matter GAP based on the setting information stored in the parameter table  121   f . As a result, if delay in conveyance is expected in the sheet processing apparatus  1  due to the thickness of the preceding sheet, adjusting feed timing for the following sheet enables preventing the sheet to be supplied from catching up the preceding sheet. 
     Furthermore, if a difference between the thickness of the preceding sheet and the thickness of the sheet to be supplied is small (if the preceding sheet is not a thick matter or if a difference between the thickness of the preceding sheet and the thickness of the sheet to be supplied is less than a predetermined value), the ejection control unit  121  sets the regular GAP and supplies the sheet in such a manner that the gap (GAP) from the preceding sheet becomes the regular GAP. 
     The ejection control unit  121  controls delivery of the sheet using the delivery roller  127  as the GAP compensation unit so that the gap between the target sheet and the preceding sheet can be the set GAP (the regular GAP or the thick matter GAP). For example, the ejection control unit  121  drives and controls the delivery roller  127  that delivers the sheet based on, e.g., rotation timing, a rotation speed, or an acceleration time of the delivery roller  127  set by using the parameter table  121   f  so that the GAP between the sheet and the preceding sheet can be the set GAP. 
     The delivery roller  127  delivers the sheet in the conveyance direction along the guide plate  203  and the pressure roller  206  under control of the ejection control unit  121 . The sheet delivered by the delivery roller  127  is supplied to the conveyance path in the main body of the sheet processing apparatus  1  as the conveyance unit  13  and conveyed at a constant conveyance speed. In this case, each sheet is supplied to the conveyance path in the main body of the sheet processing apparatus  1  so that the gap set based on the thickness of the preceding sheet and the like can be provided. 
     In the sheet ejection apparatus having the ejection unit  12 A as the first structural example, when the thickness of the preceding sheet is not smaller than the predetermined value (a thick matter) or when a difference from the thickness of the preceding sheet is not smaller than the predetermined value, the conveyance of the sheet can be delayed, and the delivery gap (GAP) between the preceding sheet and the target sheet can be expanded. As a result, in the sheet processing apparatus to which the sheets are sequentially supplied from the sheet ejection apparatus, each following sheet to be conveyed can be prevented from catching up the preceding sheet. 
     Control over the ejection unit  12 A (sheet ejection (delivery) processing) as the first structural example will now be described. 
       FIG. 4  is a flowchart for explaining a flow of sheet ejection (delivery) processing for the ejection unit  12 A as the first structural example. 
     First, to eject out sheets as processing targets (which will be referred to as target sheets hereinafter) from the supply unit  11  one by one, the CPU  121   a  of the ejection control unit  121  drives the ejection roller  124  by using the drive circuit  122  and the motor  123  (a step S 11 ). The ejection roller  124  driven by the motor  123  ejects one sheet from the ejection port side of the supply base  11   a  in the supply unit  11  and supplies the ejected sheet to the delivery roller  127 . 
     After the ejection roller  124  is driven, the CPU  121   a  of the ejection control unit  121  judges whether the leading end of the target sheet has reached the detecting position of the GAP measurement sensor  128  based on a detection signal from the GAP measurement sensor  128  (a step S 12 ). If it is determined that the target sheet has reached the detecting position of the GAP measurement sensor  128  (YES at the step S 12 ), the CPU  121   a  of the ejection control unit  121  determines a gap (GAP) to a sheet that precedes the target sheet (which will be referred to as a preceding sheet hereinafter) (a step S 13 ). For example, in the ejection control unit  121 , a time at which the trailing end of the preceding sheet passed the detecting position of the GAP measurement sensor  128  is stored in the RAM  121   b  in advance, and the CPU  121   a  determines the gap (GAP) to the preceding sheet based on a difference between a time at which the leading end of the target sheet was detected by the GAP measurement sensor  128  and the time at which the trailing end of the preceding sheet passed the detecting position of the GAP measurement sensor  128 . 
     Further, after the ejection roller  124  is driven, the CPU  121   a  of the ejection control unit  121  acquires a detection signal indicative of a thickness of the target sheet from the thickness measurement sensor  129  ( 129   a  or  129   b ). Upon acquiring the detection signal indicative of the thickness of the target sheet from the thickness measurement sensor  129 , the CPU  121   a  determines the thickness of the target sheet (a step S 14 ). When the thickness of the target sheet has been determined, the CPU  121   a  stores information representing the determined thickness of the target sheet in the RAM  121   b  (a step S 15 ). It is to be noted that the CPU  121   a  may acquire the detection signal indicative of the thickness from the thickness measurement sensor  129  as required and determine the thickness, or it may acquire the detection signal from the thickness measurement sensor  129  and determine the thickness when the GAP measurement sensor  128  has detected the leading end of the target sheet. 
     Upon determining the thickness of the target sheet, the CPU  121   a  reads out thickness information representing the thickness of the preceding sheet from the RAM  121   b  (a step S 16 ). The thickness information of the preceding sheet is obtained by measurement effected by the thickness measurement sensor  129  before the preceding sheet passes the detecting position of the GAP measurement sensor  128 , and it is stored in the RAM  121   b.    
     When the thickness information of the preceding sheet has been acquired, the CPU  121   a  judges whether preceding sheet is a thick matter based on the read thickness information of the preceding sheet (a step S 17 ). For example, the CPU  121   a  judges whether the preceding sheet is a thick matter based on whether the thickness of the preceding sheet is higher than a predetermined reference value. If it is determined that the preceding sheet is a thick matter (YES at the step S 17 ), the CPU  121   a  judges whether the target sheet is a thick matter (a step S 18 ). For example, the CPU  121   a  judges whether the target sheet is a thick matter based on whether the thickness of the target sheet determined at the step S 14  is higher than the predetermined reference value. 
     If it is determined that the preceding sheet is not a thick matter (NO at the step S 17 ) and if it is determined that the preceding sheet is a thick matter and the target sheet is also a thick matter (YES at the step S 18 ), the CPU  121   a  sets the regular GAP as a gap (GAP) from the preceding sheet (a step S 19 ). 
     If it is determined that the preceding sheet is a thick matter and the target sheet is not a thick matter (NO at the step S 18 ), the CPU  121   a  sets the thick matter GAP, which is a wider gap than the regular GAP, as the gap (GAP) from the preceding sheet (a step S 20 ). Setting information, e.g., the thick matter GAP and the regular GAP is stored in the parameter table  121   f  in advance. If the preceding sheet is a thick matter and the target sheet is not a thick matter, the CPU  121   a  sets the thick matter GAP based on the setting information stored in the parameter table  121   f.    
     When the GAP (the regular GAP or the thick matter GAP) associated with the thicknesses of the preceding sheet and the target sheet has been set, the CPU  121   a  drives the delivery roller  127  at timing according to the set GAP and delivers the target sheet (a step S 21 ). In case of driving the delivery roller  127  and delivering the target sheet, the CPU  121   a  checks timing which the trailing end of the target sheet passes by using a detection signal from the GAP measurement sensor  128  (a step S 22 ). 
     When the GAP measurement sensor  128  has detected passage of the trailing end of the target sheet (YES at the step S 22 ), the CPU  121   a  stores information representing a time at which the target sheet passed in the RAM  121   b  (a step S 23 ). For example, the CPU  121   a  may store the time at which the target sheet passed the detecting position of the GAP measurement sensor  128  in the RAM  121   b  in association with the information representing the thickness of the target sheet. 
     When the target sheet passes the detecting position (the delivery roller  127 ) of the GAP measurement sensor  128 , the CPU  121   a  confirms whether a subsequent sheet as a processing target is preset in the supply unit  11  (a step S 24 ). If the subsequent sheet as the processing target is present in the supply unit  11  (YES at the step S 24 ), the CPU  121   a  returns to the step S 11  and executes the processing of the steps S 11  to S 24  with respect to the subsequent sheet as the processing target. If the subsequent sheet as the processing target is not present in the supply unit  11  (NO at the step S 24 ), the CPU  121   a  terminates the sheet ejection processing. 
     According to the above-described processing, if the preceding sheet is a thick matter and the target sheet is not a thick matter, the delivery timing for the target sheet from the ejection unit  12  can be adjusted in such a manner that the gap between the preceding sheet and the target sheet becomes the thick matter GAP. As a result, each gap between the sheets sequentially supplied from the sheet ejection apparatus in the conveyance path in the sheet processing apparatus becomes an appropriate gap, and it is possible to avoid an inconvenience that the following sheet catches up the preceding sheet. 
     It is to be noted that, at the steps S 17  and S 18 , if the preceding sheet is a thick matter and the target sheet is not a thick matter (i.e., if the thickness of the preceding sheet is larger than that of the target sheet), the thick matter GAP is set, but the thick matter GAP may be set if the preceding sheet is a thick matter irrespective of the thickness of the target sheet. In this case, a judgment on whether the thick matter GAP should be set can be facilitated. 
     Further, in the above processing example, one of the regular GAP and the thick matter GAP is set as the gap (GAP) for the preceding sheet, GAPs in stages may be set in accordance with a difference between the thickness of the preceding sheet and the thickness of the target sheet. For example, this configuration can be realized by setting GAPs associated with differences in thickness in the parameter table  121   f  in advance and selecting each GAP associated with each difference in thickness. 
     A second structural example of the ejection unit  12  will now be described. 
       FIG. 5  is a view schematically showing a structural example of the ejection unit  12 B as the second structural example of the ejection unit  12 . 
     The ejection unit  12 B shown in  FIG. 5  is a structural example of the ejection unit  12  in the sheet processing apparatus  1 , and the ejection unit  12 B and an ejection control unit  121  constitute a sheet ejection apparatus. Further, the ejection unit  12 B ejects sheets one by one from a supply unit  11  having a supply base  11   a  on which the sheets as processing targets are collectively set. Furthermore, the ejection unit  12 B supplies each sheet ejected from the supply unit  11  to a conveyance unit  13 . 
     As shown in  FIG. 5 , the ejection unit  12 B as the second structural example comprises an ejection roller  124 , a delivery roller  127 , a GAP measurement sensor (a sheet detection sensor)  128 , a thickness measurement sensor  129  ( 129   a  or  129   b ), guide plates  202 ,  203 , and  204 , pressure rollers  205 ,  206 , and  207  for pressing sheets, and others. 
     As shown in  FIG. 5 , in the ejection unit  12 B as the second structural example, the respective physical structures (structures, e.g., the ejection roller  124 , the delivery roller  127 , the GAP measurement sensor (a sheet detection sensor)  128 , the guide plates  202 ,  203 , and  204 , and the pressure rollers  205 ,  206 , and  207  for pressing sheets) other than the arrangement of a thickness measurement sensor  129   c  may be equal to the respective structures in the ejection unit  12  as the first structural example shown in  FIG. 3 . 
     In the second structural example depicted in  FIG. 5 , the thickness measurement sensor  129   c  is provided on the downstream side of the ejection unit  12 B in a conveyance direction of the delivery roller  127 . The thickness measurement sensor  129   c  supplies to the CPU  121   a  a detection signal indicative of a thickness of each sheet delivered from a contact position (a detecting position of the GAP measurement sensor  128 ) of the delivery roller  127  and the pressure roller  206 . The thickness measurement sensor (a thickness sensor)  129   c  measures a thickness of each sheet by using, e.g., a reflective sensor. In the ejection unit  12 B shown in  FIG. 5 , the thickness measurement sensor  129   c  detects a thickness of each sheet that passes above the guide plate  204  by using a reflective sensor installed at a position where it faces a surface of the guide plate  204 . Since each sheet is pressed by the pressure roller  207  and conveyed to the guide plate  204  in this state, the thickness measurement sensor  129   c  can detect a thickness of the sheet with the surface of the guide plate  203  determined as a reference. 
     Moreover, the delivery roller  127  functions as a GAP compensation unit that operates in response to an operating instruction issued by a control system and thereby adjusts a gap (GAP) from a preceding sheet. The ejection control unit  121  sets a gap (GAP) associated with a thickness of the preceding sheet based on setting information in a parameter table  121   f  and drives the delivery roller  127  at delivery timing associated with the set GAP. 
     In the ejection unit  12 B as the second structural example, a detecting position of the thickness measurement sensor  129  is arranged on the downstream side of the delivery roller  127  along the conveyance direction of sheets. Therefore, in the ejection unit  12 B, a thickness of a target sheet cannot be determined when a leading end of the target sheet reached the delivery roller  127  (when the GAP measurement sensor detected the leading end of the target sheet). Therefore, as control cover the ejection unit  12 B, the ejection control unit  121  sets the GAP associated with the thickness of the preceding sheet when the GAP measurement sensor  128  detected the sheet. 
     That is, when the GAP measurement sensor  128  detected the sheet, the ejection control unit  121  reads out the thickness of the preceding sheet from an RAM  121   b , makes reference to the parameter table  121   f , and sets a gap (a regular GAP or a thick matter GAP) from the preceding sheet associated with the thickness of the preceding sheet. The ejection control unit  121  drives and controls the delivery roller  127  that supplies the sheet in accordance with rotation timing, a rotation speed, or an acceleration time of the delivery roller  127  set by the parameter table  121   f  so that the GAP between the sheet and the preceding sheet can be the set GAP. 
     The delivery roller  127  delivers the sheet in the conveyance direction along the guide plate  203  and the pressure roller  206  under control of the ejection unit. The sheet delivered by the delivery roller  127  is supplied to the conveyance path in the main body of the sheet processing apparatus  1  as the conveyance unit  13  and conveyed at a constant conveyance speed. In this case, each sheet is supplied to the conveyance path in the main body of the sheet processing apparatus  1  so that the gap set based on the thickness of the preceding sheet and the like can be provided. 
     In the sheet ejection apparatus having the ejection unit  12 B as the second structural example, when the thickness of the preceding sheet is not smaller than a predetermined value (a thick matter), the conveyance of the sheet can be delayed, and the delivery gap (GAP) between the preceding sheet and the target sheet can be expanded. That is, the ejection unit  12 B as the second structural example can control the delivery timing of the target sheet in accordance with the thickness of the preceding sheet and, in the sheet processing apparatus  1  to which the sheets are sequentially supplied from the ejection unit  12 B, each following sheet can be prevented from catching up the preceding sheet even if a conveyance speed is lowered due to the thickness of the preceding sheet. 
     Control over the ejection unit  12 B (sheet ejection (delivery) processing) as the second structural example will now be described. 
       FIG. 6  is a flowchart for explaining a flow of sheet ejection (delivery) processing with respect to the ejection unit  12 B as the second structural example. 
     First, the CPU  121   a  of the ejection control unit  121  drives the ejection roller  124  (a step S 31 ), ejects one sheet from the supply unit  11 , and supplies the ejected sheet to the delivery roller  127 . After the ejection roller  124  is driven, the CPU  121   a  of the ejection control unit  121  judges whether a leading end of the sheet (which will be referred to as a target sheet hereinafter) ejected by the ejection roller  124  has reached the detecting position of the GAP measurement sensor  128  based on a detection signal from the GAP measurement sensor  128  (a step S 32 ). 
     If it is determined that the target sheet has reached the detecting position of the GAP measurement sensor  128  (YES at the step S 32 ), the CPU  121   a  of the ejection control unit  121  determines a GAP between the target sheet and a sheet that precedes the former (which will be referred to as a preceding sheet hereinafter) (a step S 33 ). For example, the CPU  121   a  determines a gap (GAP) of the preceding sheet based on an elapsed time from a time at which a trailing end of the preceding sheet passed the detecting position of the GAP measurement sensor  128 . 
     Further, after the ejection roller  124  is driven, the CPU  121   a  of the ejection control unit  121  reads out information representing a thickness of the preceding sheet from the RAM  121   b  (a step S 34 ). It is assumed that the thickness information of the preceding sheet was saved in the RAM  121   b  when the ejection processing for the preceding sheet was carried out. Upon acquiring the thickness information of the preceding sheet, the CPU  121   a  judges whether the preceding sheet is a thick matter based on the read thickness information of the preceding sheet (a step S 35 ). For example, the CPU  121   a  judges whether the preceding sheet is a thick matter based on whether the thickness of the preceding sheet is larger than a predetermined reference value. 
     When it is determined that the preceding sheet is not a thick matter (NO at the step S 35 ), the CPU  121   a  sets the regular GAP as the gap (GAP) from the preceding sheet (a step S 36 ). Further, when it is determined that the preceding sheet is a thick matter (YES at the step S 35 ), the CPU  121   a  set the thick matter GAP, which is a wider gap than the regular GAP, as the gap (GAP) from the preceding sheet (a step S 37 ). Data indicative of the thick matter GAP is stored in, e.g., the parameter table  121   f , and the CPU  121   a  makes reference to the parameter table  121   f  and sets the thick matter GAP. 
     When the GAP (the regular GAP or the thick matter GAP) associated with the thickness of the preceding sheet has been set, the CPU  121   a  drives the delivery roller  127  at timing associated with the set GAP and delivers the target sheet (a step S 38 ). After the delivery roller  127  was driven and the target sheet was delivered, the CPU  121   a  of the ejection control unit  121  acquires a detection signal indicative of a thickness of the target sheet from the thickness measurement sensor  129   c.    
     Upon acquiring the detection signal indicative of the thickness of the target sheet from the thickness measurement sensor  129   c , the CPU  121   a  determines the thickness of the target sheet (a step S 39 ). When the thickness of the target sheet has been determined, the CPU  121   a  stores thickness information representing the determined thickness of the target sheet in the RAM  121   b  (a step S 40 ). It is to be noted that the CPU  121   a  may acquire the detection signal indicative of the thickness from the thickness measurement sensor  129   c  as required and determine the thickness, or it may acquire the detection signal from the thickness measurement sensor  129   c  and determine the thickness when the GAP measurement sensor  128  has detected a trailing end of the target sheet. 
     Furthermore, after the delivery roller  127  was driven and the target sheet was delivered, the CPU  121   a  of the ejection control unit  121  checks timing at which the trailing end of the target sheet passes through the delivery roller  127  by using the detection signal from the GAP measurement sensor  128  (a step S 41 ). When the GAP measurement sensor  128  has detected that the trailing end of the target sheet passed (YES at the step S 41 ), the CPU  121   a  stores information representing a time at which the target sheet passed in the RAM  121   b  (a step S 42 ). For example, the CPU  121   a  may store in the RAM  121   b  the time at which the sheet passed the detecting position of the GAP measurement sensor  128  in association with the information representing the thickness of the target sheet. 
     When the target sheet passed the detecting position (the delivery roller  127 ) of the GAP measurement sensor  128 , the CPU  121   a  confirms whether a subsequent sheet as a processing target is present in the supply unit  11  (a step S 43 ). If the subsequent sheet as the processing target is present in the supply unit  11  (YES at the step S 43 ), the CPU  121   a  returns to the step S 31  and executes the processing of the steps S 31  to S 43  with respect to the subsequent sheet as the processing target. If the subsequent sheet as the processing target is not present in the supply unit  11  (NO at the step S 43 ), the CPU  121   a  terminates the sheet ejection processing. 
     According to the ejection processing for the ejection unit  12 B as the second structural example, if the preceding sheet is a thick matter, the sheet ejection apparatus adjusts the timing for delivering the target sheet from the ejection unit  12  so that the gap from the preceding sheet can be the thick matter GAP. As a result, the ejection unit  12 B as the second example can control the timing for delivering the sheet in accordance with the thickness of the preceding sheet, a gap between the respective sheets on the conveyance path becomes an appropriate gap in the main body of the sheet processing apparatus to which the sheets are sequentially supplied from the ejection unit  12 B, and an inconvenience that a following sheet catches up a preceding sheet can be avoided. 
     It is to be noted that one of the regular GAP and the thick matter GAP is set as the gap (GAP) from the preceding sheet in the above processing example, but GAPs in stages may be set in accordance with the thickness of the preceding sheet. For example, this configuration can be realized by setting GAPs associated with thicknesses of the preceding sheets in the parameter table  121   f  in advance, setting each GAP to be selected which is associated with each thickness of the preceding sheet, and adjusting the timing for delivering the target sheet. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.