Xerox Corporation

Sheldon F Raizes

Paul D Hansen

Keith Johnson

Michael D Rumsey

William D Barton

A single tray or multi tray sheet feed system is provided. A sensor is provided to sense the sheets leaving from the single tray or multi tray system. If the paper weight of sheets of paper on a tray fall within a first range of paper weight values, the sensor is designed to have a first given voltage response condition for sensing these sheets and if the paper weight of the sheets falls within a second range of paper weight values the sensor is designed to have a second given voltage response condition for sensing the latter sheets. A current value supplied to the emitter of the sensor can be controlled to provide the desired voltage response or a resistance in a phototransistor collector circuit can be varied to provide the desired voltage response condition. If the first range of paper weight values is lighter than the second range of paper weight values, the sensor, when in the first given voltage response condition, will have a voltage response, when sensing a sheet of a given paper weight, which is higher than the voltage response when the same sensor senses a sheet of the same paper weight, when the sensor is in the second given voltage response condition. A voltage response value sensed by the sensor of the first sheet fed from a tray is stored in memory as the voltage response value for all sheets on that particular tray. The voltage response value sensed by the same sensor of subsequent sheets fed from that particular tray is compared with the voltage response value in memory to detect a multi sheet feed from the tray.

Single tray and multi tray misfeed detector with voltage response

The sheets in each tray of a multi tray sheet feeder are of the same thickness, but the sheets in one tray may be of a different thickness than the sheets in another tray. The sheets are fed from each sheet feeder tray to an intermediate stacker and then to a printer. A first sensor is provided just prior to entry of a sheet into the intermediate stacker and a second sensor is provided to sense a sheet as it is fed from the intermediate stacker. If the paper weight of sheets of paper on a tray fall within a first range of paper weight values, each sensor is designed to have a first given voltage response condition when sensing those sheets and if the paper weight of the sheets falls within a second range of paper weight values each sensor is designed to have a second given voltage response condition sensing the latter sheets. A current value supplied to the emitter of a sensor can be controlled to provide the desired voltage response or a resistance in a phototransistor collector circuit can be varied to provide the desired voltage response condition. If the first range of paper weight values is lighter than the second range of paper weight values, each sensor, when in the first given voltage response condition, will have a voltage response, when sensing a sheet of a given paper weight, which is higher than the voltage response when the same sensor senses a sheet of the same paper weight, when each sensor is in the second given voltage response condition. The first sensor is placed in a proper voltage response condition to sense the thickness of a sheet that has been fed from a particular tray and that thickness value is compared with a single sheet thickness value, sensed by the first sensor when in the same voltage response condition, that has been placed in memory for the sheets on that particular tray to detect a multi sheet feed from the tray. The sheet then enters the intermediate stacker. When the same sheet is fed from the intermediate stacker, it is sensed by the second sensor. The second sensor is placed in the same voltage response condition as the first sensor when it sensed the same sheet and the thickness value sensed by the second sensor is compared with the thickness value sensed of the same sheet by the first sensor to detect a multi sheet feed from the intermediate stacker.

Multi tray and buffer tray misfeed detector with voltage response

The thickness of a first sheet fed from each tray of the multi-tray sheet feeder is detected by a first sensor and a thickness value is placed in memory for that tray. Each sheet subsequently fed from the same tray is detected by the same sensor and the thickness value sensed is placed in memory and compared with the thickness value in memory for that tray. When a tray is reloaded, the thickness value in memory for the sheets previously loaded in the tray is erased and the first sheet fed from the reloaded tray is sensed and a thickness value for that sheet is placed in memory for the reloaded tray. After the thickness value of a sheet is sensed by the first sensor, the sheets enter into the intermediate tray. The thickness value of a sheet is detected by an outlet sensor as it leaves the intermediate sheet tray and that value is compared to the thickness value in memory which was detected for the same sheet by the first sensor. During the comparison steps, if the values match, then only one sheet has passed through a sensor. If the thickness value sensed is more that the thickness value in memory, then that indicates that more than one sheet has passed through the sensor and the system is shut down to enable an operator to correct the situation or the offending sheets can be sent to a purge tray at the printer without shutting down the system.

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Palos Verdes, CA, United States of America

Sheldon F Raizes