Abstract: A method for controlling lateral positioning of a longitudinally moving endless belt having at least two targets aligned with tolerances on a longitudinal fixed reference line, in which belt displacement from the fixed reference line is measured at least two times during each revolution of belt movement to provide a current value of measured displacement and at least one prior value of measured. The current value of measured displacement and the at least one prior value of measured displacement are averaged to provide a current average value of measured displacement and a current average value of measured displacement is calculated for each successive current value of measured displacement to provide a belt steering correction factor used to steer the belt as necessary to reduce the current average value of measured displacement to zero. Each of the targets is preferably an apertured pattern of N-shaped configuration formed in the belt.

Abstract: A method and apparatus for transverse registration of image exposures on photoreceptive belts subject to lateral deviation from linear travel in which targets, corresponding in location to the image areas to be exposed, are used for the detection of lateral belt displacement and to control the transverse location of exposure scan. The targets are of a pattern defining a reference line and a line inclined with respect to the direction of belt travel so that the duration of time between passage of the target lines with respect to a spacially fixed sensing axis will vary with lateral displacement of the belt. The targets may assume a variety of specific patterns and the invention is applicable to single and multi-pass image exposure systems as well as to both modulated laser and light emitting diode types of exposure devices.

Abstract: A non-contact, transmissive energy sensor is utilized for determining the thickness of paper sheets in a feed path. The sensor includes an energy emitting source and an energy detector, the output of the energy detecting source being proportional to the amount of energy received by the energy detector. The signal output level of the detector is utilized in a model to determine the basis weight of paper in the detecting zone of the detector. Heuristic sampling techniques can be utilized to reduce or eliminate the effects of images printed on the paper and flutter of the paper as it moves. An automatic calibration routine utilizing boundary coefficients is used to calibrate the paper basis weight detection system. The paper basis weight determination is utilized to control subsequent operations to which the paper sheet is subjected in order to optimize image quality and sheet handling, and to control finishing operations.

Abstract: A stack height sensor for stacked sheet members includes a switch having an actuator arm positioned adjacent to top edge of the stack at a predetermined level. A flexible "flogger" or "scuffer" element is moved along a path which first contacts the top surface of the sheet members, and then slides off the stack edge in the direction of the switch actuator arm. The switch actuator arm is adjusted such that the deflected path of the flexible flogger or scuffer element intercepts the switch for stack heights less than the predetermined value and "ski jumps" the switch actuator arm for stack heights greater than the predetermined height. The flogger or scuffer elements can be mounted on the disk inverter of a photocopier output section, and the switch output be used to control the position of the stack elevator mechanism. Alternatively a separate hub synchronized for rotation with the disk inverter, can be used to mount the flogger or scuffer elements.

Abstract: Apparatus for feeding sheets from a stack of sheets on a sheet stack supporting tray which includes a sheet transport for feeding sheets from the tray. An air knife is disposed adjacent the front wall of the tray to inject air between the sheet to be separated and the remainder of the stack. The air knife includes at least one elastomeric member attached to its front wall that extends to a point immediately above, below or touching the sheet transport in order to inhibit multifeeding of sheets from the tray.