Abstract: An apparatus for determining the dimensions of a stack of sheets in the tray. An optical sensor is arranged so that movement of the sheet guides in a paper tray causes a variably graduated scale to be moved past the sensor. The sensor may either be a transmissive or reflective type analog sensor in which the strength of the signal generated by the sensor is converted into a position of the side guides and as the analog scale is continuously variable, there is no need for separate discrete sensors or switches and sheet sizes of any dimension can be accommodated. A recalibration process is used to prevent contamination of the gauge and the associated change in signal strength by this sensor from causing the size determinations to be inaccurate. Alternatively, a digital sensor in cooperation with a digital bar code or other digital scale can be utilized to determine the variable sheet size, which digital sensor and variable scale are insensitive to contamination by dirt or paper particles, etc.

Abstract: An apparatus for displaying a plurality of two dimensional display regions includes a currently displayed display region on a surface of a visual display. A pointing device generates X and Y coordinate signals corresponding to locations on the display and a Z increment signal, and a pointer is displayed on the display at a location corresponding to a set of the X and Y coordinate signals. A sequence of two dimensional display regions is stored in a memory circuit, and a display region succeeding the currently displayed display region in the sequence or a display region preceding the currently displayed display region in the sequence is selected in response to the Z increment signal irrespective of whether the location at which the pointer is displayed coincides with the selected display region.

Abstract: A thermal ink jet printhead and control arrangement therfor includes a housing defining a plurality of ink receiving and emitting chambers with each chamber extending from an aperture in the ink emitting edge of the housing into the interior thereof. A plurality of heating elements are included, one heating element positioned in each of the chambers. An electrically conductive bus positioned within the housing connects the first terminals of the heating elements together. A power source and control system are also provided. The control system is operable to connect the second terminal of a selected one of the heating elements with the power source while simultaneously connecting the second terminals of the remaining heating elements with an electrical ground so that current from the power source flows through the selected heating element and, thereafter, through the electrically conductive bus and remaining heating elements to electrical ground.

Abstract: An ion projection printing apparatus for printing on one side of a charge receptor sheet including an ion projection means, development means, a back electrode positioned on the opposite side of the sheet from the ion projection means, development means to receive the sheet in intimate contact, and a corotron disposed on the same side of the sheet as the ion projection means and the development means in the vicinity of the point of separation of the paper from the back electrode, the corotron providing a charge source to neutralize the residual electrical charge on said paper.

Abstract: A high speed color reproduction machine comprised of four separate xerographic type processing units, one for each of the primary colors plus black. The multiple processing units are arranged in close nested relationship to one another with the image transfer stations thereof in close succession along the path of movement of the copy substrate material. A combination air flotation type and vacuum based belt transport system is employed to bring copy substrate material from a supply source into transfer relation with the successive processing units. Exposure of the processing unit's photoreceptors is simultaneous. A precise dimensional relationship between photoreceptor length and spacing for each processing unit assures registration of the color images produced with one another. Following transfer of the last color image, the image bearing copy material is brought to a fuser where the image is fixed. The finished copy is thereafter discharged, or returned for a second duplex pass.

Abstract: A binary ink drop printer is disclosed of the type wherein continuously generated drops are electrostatically deflected to intersect either a target or a gutter. The printer includes M.times.N number of nozzles for generating drops and a like number of charging electrodes for charging drops to either a print level for flight to the target or a gutter level for flight to a gutter. A M.times.N matrix is used to couple voltages to the charging electrodes and thereby greatly reduce the number of electrical connections to a substrate carrying the M.times.N number of charging electrodes. Each charging electrode includes two sections. Application of a print voltage to both sections causes the generation of a print drop that goes to the target and application of a gutter voltage to either or both sections of the charging electrode causes the generation of a gutter drop that is collected in the gutter. One two section electrode is made using at least two partial cylinders.

Abstract: A motor speed control system for reducing instantaneous speed variations as a result of hunting in hysteresis synchronous motors utilized to drive optical scanners by controlling the frequency of the drive signal applied to the motor. A laser beam is reflected from the facets of the optical scanner and scans a surface along a scan line, a signal being generated at the start and end of each scan line. A counter is driven by an accurate clock which is started and stopped in accordance with the start and end of scan signals. The resulting count of the counter is thus inversely proportional to the speed of the motor and is converted to an analog input signal and coupled to a voltage controlled oscillator whose frequency is controlled for driving the motor such that undesirable oscillations of the motor are damped out. Additional embodiments for controlling the motor speed are disclosed which utilize only the start of scan signal to both start and stop the counter.