Paper sheet stacking apparatus, image forming apparatus, paper sheet processing apparatus, image forming system and method for controlling paper sheet stacking operation

An image forming apparatus, comprising:

• an image forming section to form an image on a paper sheet;
• an ejecting section to eject the paper sheet on which the image is formed;
• a stacking tray to stack the paper sheet, ejected by the ejecting section, thereon;
• an up-and-down driving section to drive the stacking tray in up and down directions corresponding to a height of paper sheets stacked, each of which is the paper sheet;
• a paper-sheet upper surface detecting section to detect an upper-most surface of the paper sheets to be stacked onto the stacking tray;
• a position detecting section to detect a position of the stacking tray by using a plurality of sensors respectively disposed at different positions arranged in a vertical direction, along which the stacking tray moves up and down;
• and
• a control section that controls the up-and-down driving section to drive the stacking tray so as to keep a position of the upper-most surface of the paper sheets, which is to be detected by the paper-sheet upper surface detecting section, constant, and determines whether or not the stacking tray is currently in a full loaded condition, based on the position of the stacking tray, detected by the position detecting section;
• wherein, by employing information in regard to a weight and a thickness of the paper sheet, the control section selects any one of the plurality of sensors as a full-loaded condition position sensor that indicates the full loaded condition of the stacking tray, and determines whether or not the stacking tray is currently in the full loaded condition, based on the position of the stacking tray, which is detected by the full-loaded condition position sensor concerned.

A paper sheet processing apparatus, comprising:

• a paper sheet processing section to apply a paper sheet processing to a paper sheet;
• an ejecting section to eject the paper sheet to which the paper sheet processing is applied;
• a stacking tray to stack the paper sheet, ejected by the ejecting section, thereon;
• an up-and-down driving section to drive the stacking tray in up and down directions corresponding to a height of paper sheets stacked, each of which is the paper sheet;
• a paper-sheet upper surface detecting section to detect an upper-most surface of the paper sheets to be stacked onto the stacking tray;
• a position detecting section to detect a position of the stacking tray by using a plurality of sensors respectively disposed at different positions arranged in a vertical direction, along which the stacking tray moves up and down;
• and
• a control section that controls the up-and-down driving section to drive the stacking tray so as to keep a position of the upper-most surface of the paper sheets, which is to be detected by the paper-sheet upper surface detecting section, constant, and determines whether or not the stacking tray is currently in a full loaded condition, based on the position of the stacking tray, detected by the position detecting section;
• wherein, by employing information in regard to a weight and a thickness of the paper sheet, the control section selects any one of the plurality of sensors as a full-loaded condition position sensor that indicates the full loaded condition of the stacking tray, and determines whether or not the stacking tray is currently in the full loaded condition, based on the position of the stacking tray, which is detected by the full-loaded condition position sensor concerned.

An image forming system, comprising:

• an image forming section to form an image on a paper sheet;
• a paper sheet processing section to apply a paper sheet processing to the paper sheet on which the image is formed;
• an ejecting section to eject the paper sheet to which paper sheet processing is applied;
• a stacking tray to stack the paper sheet, ejected by the ejecting section, thereon;
• an up-and-down driving section to drive the stacking tray in up and down directions corresponding to a height of paper sheets stacked, each of which is the paper sheet;
• a paper-sheet upper surface detecting section to detect an upper-most surface of the paper sheets to be stacked onto the stacking tray;
• a position detecting section to detect a position of the stacking tray by using a plurality of sensors respectively disposed at different positions arranged in a vertical direction, along which the stacking tray moves up and down;
• and
• a control section that controls the up-and-down driving section to drive the stacking tray so as to keep a position of the upper-most surface of the paper sheets, which is to be detected by the paper-sheet upper surface detecting section, constant, and determines whether or not the stacking tray is currently in a full loaded condition, based on the position of the stacking tray, detected by the position detecting section;
• wherein, by employing information in regard to a weight and a thickness of the paper sheet, the control section selects any one of the plurality of sensors as a full-loaded condition position sensor that indicates the full loaded condition of the stacking tray, and determines whether or not the stacking tray is currently in the full loaded condition, based on the position of the stacking tray, which is detected by the full-loaded condition position sensor concerned.

A method for controlling a paper sheet stacking operation, which is to be implemented in a paper sheet stacking apparatus that stacks paper sheets, each of which is ejected outside after an image has been formed thereon and/or a paper sheet processing has been applied thereto, and is provided with:

• a stacking tray to stack the paper sheets, onto each of which an image is formed and/or a paper sheet processing is applied, thereon;
• an up-and-down driving section to drive the stacking tray in up and down directions corresponding to a height of the paper sheets stacked;
• a paper-sheet upper surface detecting section to detect an upper-most surface of the paper sheets to be stacked onto the stacking fray;
• a position detecting section to detect a position of the stacking tray by using a plurality of sensors respectively disposed at different positions arranged in a vertical direction, along which the stacking tray moves up and down;
• and a control section that controls the up-and-down driving section to drive the stacking tray so as to keep a position of the upper-most surface of the paper sheets, which is to be detected by the paper-sheet upper surface detecting section, constant, and determines whether or not the stacking tray is currently in a full loaded condition, based on the position of the stacking tray, detected by the position detecting section, the method comprising:
• selecting any one of the plurality of sensors as a full-loaded condition position sensor that indicates the full loaded condition of the stacking tray, by employing information in regard to a weight and a thickness of each of the paper sheets;
• and
• determining whether or not the stacking tray is currently in the full loaded condition, based on the position of the stacking tray, which is detected by the full-loaded condition position sensor concerned.