International Business Machines Corporation

Gerald L Smith

John Charles Wilson

James L Bacon

Leland W Ford

Alberto M Ramirez

George G Promis, Jr

Ronald E Gaitten

Dennis J Justus

A continuously variable magnification/reduction scanning optical system for a document copier machine where the lens and total conjugate length adjustment are made prior to the copy operation without use of a special optics positioning motor. Optical component adjustment is achieved through use of the scan drive motor by coupling the scan carriage to the lens carriage during the set-up period and uncoupling the carriages during normal operation.

Means for positioning optical components for a variable

In an electrophotographic copying device having charging, imaging, developing, transferring, precleaning and cleaning facilities, the arrangement being in the conventional sense, but incorporates a combined charging and precleaning unit that is operable to perform either a charging function or a precleaning function at the proper time during a copying/cleaning cycle. A combined precharging/transferring unit is also incorporated to facilitate precharging or transferring at a predetermined time during the copying process.

Photoconductor charging technique

A motor driving system which is particularly useful for driving scanning carriages in a continuously variable reducing electrophotographic copier. The motor driving system produces one of a number of different controlled and repeatable position acceleration and velocity profiles of the scanning carriage with respect to motion of the copier drum; a different position acceleration and velocity profile is produced for each reduction mode in a substantially continuous range of reduction modes. The motor driving arrangement includes a single control loop for driving a servo motor which provides the drive for the scanning carriage. A driving signal source produces a driving signal pulse train, each pulse representing a desired increment of motor travel, and a direction signal representative of the desired direction of travekl. A tachometer is responsive to servo motor motion and produces an output signal representative of the direction of motion; the output signal includes a series of tachometer pulses, each pulse representing a given increment of servo motor movement. A logic circuit couples the output of the tachometer, the driving signal pulse train and the direction signal to an up/down counter which is stepped in one direction for each driving signal pulse, and which is also stepped in another or one direction, respectively, for each tachometer pulse which represents a direction which is the same as or different from the direction of the direction signal. The output of the up/down counter, converted to analog form, provides an input signal to drive the servo motor. In order to control the acceleration, velocity and position profiles of the scanning carriage, the driving signal source produces a train of output pulses whose repetition rate is precisely controlled in relation to the motion of the drum. The driving signal source includes a counter which produces a pulse output each time a predetermined count is reached, the counter is stepped at a rate related to the velocity of the drum, and the repetition rate of the output pulses is controlled by providing a sequence of quantities, from a storage matrix, to alter the modulus of the counter in a predetermined pattern.

Motor driving system

A zero crossing detector provides an optically coupled output signal with a leading edge which occurs in the vicinity of the zero crossing point of an AC voltage waveform but no later than the zero crossing time. The circuit input includes a filter and rectifier. The filtered and rectified voltage is then applied to a complex impedance circuit with an input and an output, which provides an output lagging its input. A switching device, which may be a light emitting diode, is coupled between the output of the impedance circuit and the rectifier. Thus, when the lagging output voltage of the impedance circuit exceeds the output of the rectifier, the switching device conducts, producing the output signal.

Tight tolerance zero crossing detector circuit

A compact and lightweight power supply particularly suited for use as a high voltage supply capable of switching voltage values in short time. The high voltage output is compared against a desired reference value to produce a difference voltage which is integrated. The integrated difference voltage is converted to recurrent pulses having a corresponding width. The pulses are applied alternately to the opposite ends of a centertapped primary winding of a specially wound transformer characterized by a specially wound secondary winding and an air-gapped E-shaped core linking the primary and secondary windings. The secondary voltage is applied to a voltage multiplier circuit to produce the high voltage output of the power supply.

High frequency high voltage power supply

Method and apparatus for enabling measurement of corona drum current in an electrostatic copier as a maintenance aid. A rotatable drum supports a photoconductor with a conductive backing connected to a ground current return path including a slip ring. In the maintenance mode, the ground path is opened allowing drum current to flow through a current measuring circuit including a pair of jacks to which a measurement device may be connected. The current measuring circuit also develops a potential which is representative of whether or not the current return path is grounded. This potential is coupled to a monitoring device where it may be used to drive a display. A method of aligning a corona generator employing the corona current measuring apparatus of the invention is applicable for aligning corona generators in situ in an electrostatic copier. The alignment method includes steps of energizing a selected corona generator, interrupting the normal ground return path, providing a current path from the photoconductor and coupling the current path to a measurement device. For alignment purposes, at least two measurements are made, each measurement is made while different portions of the corona generator are masked. The measurements provide a measure of the corona current generated by two different portions of the generator which is useful in aligning the generator.

Method and apparatus for drum corona current measurement and alignment

A two cycle process electrophotographic copying device having charging, imaging, developing, transferring, and cleaning facilities, the arrangement being in the conventional sense, incorporates a combined charge and preclean corona unit that is operable to perform either a charging function or a precleaning function at the proper time during a copying/cleaning cycle and a combined precharge/transfer corona unit. The combined charge and preclean corona unit includes a dual bay corona which emits negative and positive ions and a common control grid for controlling the ion flow from each bay of the dual bay corona.

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Broomfield, CO, United States of America

Gerald L Smith