Dual mode stack height and sheet delivery detector

• US 5,033,731 A
• Filed: 03/12/1990
• Issued: 07/23/1991
• Est. Priority Date: 03/12/1990
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Looney, John H.
• Primary Examiner(s): Olszewski, Robert P.
• Assistant Examiner(s): Milef, Boris
• Application Number:
  US07/491,923
• Time in Patent Office: 498 Days
• Field of Search: 271/199, 271/188, 271/207, 271/220, 271/213, 271/215, 271/258, 271/259, 271/176
• US Class Current: 271/176
• CPC Class Codes: B65H 43/06 detecting, or responding to, completion of pile B65H43/08 takes precedence
• CPC Class Codes: B65H 43/08 Photoelectric devices

Abstract

In a sheet stacking control system for a printer or copier in which sheets are sequentially fed by a sheet output for stacking in a stacking tray up to a desired preset maximum stacking level, a plural mode stack height sensing and sheet delivery detection apparatus in which a common sensor with a common actuating member is actuated by a sheet being fed by the sheet output to provide a first intermittent signal, and this same plural mode apparatus is also actuated to provide a second signal in response to the stack of sheets in the tray approaching a desired preset maximum stacking level. The first and second signals from the common sensor are distinguishable signals, so that the first, intermittent, signal is interpreted as a count of the number of sheets being outputted, and the second, continuous, signal is interpreted as a full tray condition or a sheet jam, and this second signal can provides a control signal for stopping the production or outputting of further sheets to that output tray. The actuating member is preferably an elongated light weight pivotal arm normally angularly extending across the sheet output path and down into the stacking tray to normally rest with its outer end on top of the stack of sheets except when pivoted up by another sheet being fed into the tray. Corrugating and downward pressure on the sheet being outputted upstream of the exit rolls cooperatively resists both premature sheet lead edge drooping over the stack and the weight of the actuating arm, which arm weight subsequently provides trail edge sheet settling or knockdown assistance once the trail edge of the sheet is released by the exit rolls.

Claims

1. In a sheet stacking control system for a printer or copier in which sheets are sequentially fed by sheet output means for stacking in a stacking tray up to a desired preset maximum stacking level;

an improved sheet stacking control system comprising a plural mode stack height sensing and sheet delivery detection apparatus in which a common sensing means with a common actuating member is actuated by movement of said actuating member by a sheet being fed by sheet output means to provide a first intermittent signal for sheets being outputted by said sheet output means to be stacked in said stacking tray,

wherein said same plural mode stack height sensing and sheet delivery detection apparatus is also actuated by the position of said actuating member relative to said stacking sheets in said stacking tray to provide a second signal in response to said stacking sheets in said stacking tray approaching said desired preset maximum stacking level,

wherein said common sensing means provides distinguishable signals for said first intermittent signal for sheets being outputted by said sheet output means versus said second signal in response to said stacking sheets in said stacking tray approaching said desired preset maximum stacking level,

wherein said common actuating member is a light weight pivotal but elongated actuating arm angularly extending across the sheet path of said sheet output means and further extending down into said stacking tray to normally rest on top of the stack of sheets being stacked in said stacking tray,

wherein each sheet being fed into said stacking tray can freely temporarily push up said light weight actuating arm towards a raised sheet above said maximum stacking level which causes an extension of said arm to momentarily actuate said common sensing means to provide said intermittent first signal indicative of an incoming sheet,

wherein said second signal is provided in response to said pivotal actuating arm resting on top of the stack of sheets in said stacking tray at a preset pivotal angle corresponding to said desired preset maximum stacking level, at which preset pivotal angle of said pivotal actuating arm said pivotal actuating arm at least semi-continuously actuates said common sensing means to provide said second signal,

and wherein said pivotal actuating arm also functions to assist in the trail edge area stacking of sheets stacking in said stacking tray, by helping to push down towards the top of said stack the trail edge area of a sheet fed by sheet output means to be stacked in said stacking tray, by said actuating arm being biased towards and pivotal towards a trailing edge stacking portion of the bottom of said stacking tray, and by said actuating arm riding with a light downward force on top of a sheet being outputted by said sheet output means at a position slightly downstream of said sheet output means so that when the trail edge of a sheet being outputted by said sheet output means is released by said sheet output means for stacking, said actuating arm provides trail edge sheet settling or knock down assistance, but

wherein said sheet output means partially supports a sheet being fed into said stacking tray until the sheet is fed therethrough and released for stacking by said sheet output means including sheet corrugating means for exerting downward pressure on a sheet being fed into said stacking tray from a position upstream of said sheet output means for cooperatively resisting both premature sheet lead edge drooping over the stack and said light downward force on top of the sheet by said actuating arm until after the trail edge of the sheet is released by said sheet output means for stacking.