This invention relates generally to a folder for use with an electrophotographic printing machine, and more particularly concerns an improved soft stop folder apparatus.
As cut and folded web sections emerge from other press folder operations, they often are given an original or final fold by means of a blade which descends in a chopping motion when a sheet is in position under it. The blade pushes the sheet down between two nip rollers, creating a fold at that point. A knife folder requires deskewed and centered copy over the folding nip rollers or the sheet may be folded off center or crooked. Also, caution in the blade positioning relative to the nip rollers is essential or the sheet may be damaged or acquired too slowly. Also, one method of folding sheets is to move hard stops via a stepper/servo mechanism automatically under software control in response to control panel selection of paper size. This requires large amounts of hardware if one is folding a 36.times.48 inch and requires three fan-folds plus two cross-folds which dictates 5 fold stations with attendant hardware. Accordingly, it is highly desirable to simplify the folding of sheets without damage while at the same time improving the reliability of the folder.
The following disclosures appear relevant:
U.S. Pat. No. 1,124,375, Patentee: Wood, Issued: Jan. 12, 1915. PA1 U.S. Pat. No. 4,508,527, Patentee: Uno et al., Issued: Apr. 2, 1985. PA1 U.S. Pat. No. 4,900,391, Patentee: Mandel et al., Issued: Feb. 13, 1990. PA1 U.S. Pat. No. 4,643,705, Patentee: Bober, Issued: Feb. 17, 1987. PA1 U.S. Pat. No. 3,589,709, Patentee: Huddersfield et al., Issued: Jun. 29, 1971. PA1 U.S. Pat. No. 4,518,380, Patentee: Shimizu et al., Issued: May 21, 1985. PA1 U.S. Pat. No. 4,701,155, Patentee: Ott et al., Issued: Oct. 20, 1987. PA1 U.S. Pat. No. 4,717,134, Patentee: Iida et al., Issued: Jan. 5, 1988. PA1 U.S. Pat. No. 4,834,695, Patentee: Boblit et al., Issued: May 30, 1989. PA1 U.S. Pat. No. 4,850,945, Patentee: Whittenberger, Issued: Jul. 25, 1989. PA1 U.S. Pat. No. 5,076,556, Patentee: Mandel, Issued: Dec. 31, 1991. PA1 Wood discloses a folding and stapling device in which a folder blade drives and creases collected sheets into a receiving head and clips of a arm member. PA1 Uno et al. discloses a method and apparatus for quantitatively dividing zig-zag folded sheets. A sheet of paper having a plurality of linear perforations is continuously transferred vertically through a roller and is folded in zig-zag form by operation of a crank mechanism. PA1 Mandel '391 shows a sheet recirculating, folding and gluing system that folds documents, holds them at a wait station and then inserts them into another sheet which is folder and glued "on-line" to form an envelope. PA1 Bober is directed to a knife folder that includes a blade adapted to collapse a sheet a predetermined amount in order to allow nip rollers to buckle the sheet into a pair of folding cylinders. This apparatus ensures positive paper acquisition while reducing potential for blade damage to the sheet. PA1 Huddersfield et al. discloses a control apparatus for the measurement and folding of flat workpieces. The apparatus comprises a first detector and transmitter for detecting and measuring a dimension of a traveling workpiece and transmitting a signal to a memory. The signal in memory is used to initiate a folding operation. PA1 Shimizu et al. discloses a paper folding device having multiple rollers for forming nips and an adjustable stop. The adjustable stop is manually adjustable to accommodate different sizes of paper. PA1 Ott discloses a buckle chute folder for automatically folding successive sheets of paper. A photosensor senses leading edge positions fed sheets and a solenoid-operated clamp is actuated to clamp the sheets in a proper position during folding. Pulse counting is used to determine incremental paper movement through the folder. PA1 Iida et al. discloses a sheet folding apparatus capable of folding sheets in two-fold, Z-fold, or reverse Z-fold configurations utilizing one four roll assembly with multiple entrance paths. The apparatus uses movable stoppers to accommodate different paper sizes. PA1 Boblit et al. discloses an automatic fold-pan assembly for attachment to a sheet folding machine. The assembly includes at least one fold-controlling paper stop disposed in the assembly. The positioning of the paper stop a predetermined distance from an entrance mouth is controlled by a computer in conjunction with stepper motors. PA1 Whittenberger discloses a gatefold apparatus comprising a sensor for sensing paper movement out of a panfold and a control means, responsive to the sensor, for controlling an actuator which is guided between third and fourth rolls to gatefold a sheet. PA1 Mandel '556 is directed to an apparatus that places two or more folds in a sheet of paper which requires only a single fold position controlling chamber and one pair of fold producing rollers.
The pertinent portions of the foregoing disclosures may be briefly summarized as follows: