Abstract: A charge and bias control system for a liquid-developer electrophotographic copier in which a sensing electrode is disposed in the developing station just upstream of the developing electrodes. Developer liquid fills the space between the sensing electrode and the photoconductor to provide a direct coupling between the two elements. The charge level is adjusted at the beginning of each copy cycle by supplying the control input for the charge-corona power supply with a ramp derived by periodically indexing a counter concurrently with the movement of the photoconductor. When the photoconductor surface potential, as measured by the sensing electrode, reaches a predetermined level, further indexing of the counter is inhibited. The same sensing electrode is used during the scanning phase of the copy cycle to regulate the biasing potential applied to the developing electrodes.

Abstract: An optical scanning system for a variable-magnification electrophotographic copier includes a first scanning carriage reciprocated along a path by endless bands attached to the carriage at transversely spaced locations and driven purely by friction. Pulleys mounted on a second scanning carriage at transversely spaced locations roll between the drive bands and stationary guides to move the second carriage at half the speed of the first carriage. The second carriage may be shifted relative to the first carriage by moving it to a location at which arms lift the pulleys from the guides. A flywheel rotating at the desired scanning speed is coupled to the scanner drive train after the drive train has been smoothly accelerated to the desired scanning speed, and is uncoupled from the scanner drive train before the drive train is decelerated at the end of the scanning stroke.

Abstract: Apparatus for repositioning the lens of a variable-magnification electrophotographic copier to change the image-side path length for a different magnification ratio and for concomitantly adjusting the shutter to compensate for the changed image-side path length. Actuation of a stepper motor rotates a pulley to tension a cable coupled to the lens, pulling the lens to the desired position of a linear track. A portion of the cable extends around a pulley having an axially projecting circumferentially extending ramp on one face. A follower engaging the ramp is coupled to slit-forming members adjacent to the photoconductor so that movement of the cable to reposition the lens produces a concomitant adjustment of the width of the slit to equalize exposure of the photoconductor over a substantially continous range of selected magnifications.

Abstract: An electrophotographic copier for selectively printing in one of a number of different colors in which development takes place at a common station around the periphery of a photoconductive drum to which station a distributor system selectively feeds liquid from one of a number of supply containers and from which the liquid is returned to the container from when it came. Our machine flushes the common portion of the liquid circulating system each time a change in color is made. The processing liquid tanks of our machine are provided with an arrangement for inhibiting settling of toner particles in the tanks.

Abstract: Electrophotographic apparatus capable of being operated in the copying mode and scanning mode and in the printing mode and scanning mode, in which a latent electrostatic image, formed on the photoconductor, is developed. The photoconductor has a light-reflective surface. After the latent electrostatic image is developed, a focused laser beam or focused light beam scans the developed image and specularly reflected light from the photoconductor surface is directed onto a photodetector. The output of the photodetector is encoded and may be transmitted or stored. The developed image is not destroyed, and it can then be transferred to a carrier sheet if desired.

Abstract: Documents are advanced to a registered position along the trailing edge of the exposure platen of an electrophotographic copier by a flat belt supported adjacent to the registration edge by a pulley formed with axially spaced indentations to produce corresponding corrugations in the belt. A registration gate having a blocking position in which transversely spaced fingers extend into the belt corrugations arrest the documents at the registration edge while the normal-diameter portions of the belt pulley press the document downwardly to prevent it from riding over the registration gate. Position pulses from an encoding wheel are counted to determine the position of the document, and drive motor is slowed to one-fifth its normal speed when the document advances within a predetermined distance of the registration edge.

Abstract: Apparatus for registering a copy sheet prior to feeding the sheet to the image-transfer station of an electrophotographic copier. Opposing pairs of relatively rigid feed rollers are arranged on shafts in alternating relationship with opposing pairs of relatively compliant feed rollers, which are of somewhat larger diameter than the rigid rollers so as to form nips of appreciably greater extent in the direction of feed. Registration gates mounted for rotation on one of the roller shafts through slipping couplings are selectively restrained against rotation with the roller shaft either in a non-blocking position out of the feed path or in a blocking position within the nip area of the compliant rollers but upstream of the nip area of the rigid rollers.

Abstract: An electrophotographic copier in which a manually releasable locking mechanism normally locates the machine drum in an operative position in the machine cabinet in which peripheral edge portions of the drum engage a pair of friction rollers positioned adjacent to the image receiving portion of the drum. Upon release of the locking mechanism and without the use of tools the drum automatically moves to a location at which at least a part thereof is clear of the machine housing at an access opening thereof.

Abstract: Reciprocating optics copier in which a mass approximately equal to the mass of a scanning subassembly mounted for movement along a generally horizontal path, is coupled to the subassembly and is driven in a direction opposite to that of the scanning subassembly to counterbalance forces or reaction incident to acceleration of the subassembly.

Abstract: An electrophotocopier for relatively large and valuable originals such as engineering drawings, wherein an electrostatic image is formed by contact exposure using a fluorescent light source and wherein contamination of the original by solid or liquid components of the developer is prevented by a transparent membrane disposed between the photoconductive imaging surface and the original.

Abstract: A copy machine cabinet and lid construction in which the lid is carried by the cabinet for a swinging movement from a position over the cabinet top to a position away from the cabinet top. This lid is provided with a platen adapted to receive an original and with a platen cover which is mounted for a swinging movement between a position over the platen and a position away from the platen. As the lid is moved to a position to permit access to the parts within the cabinet, gravity responsive locks inhibit movement of the platen cover away from the platen.

Abstract: A magnetic recording medium having a coating of magnetic particles deposited thereon by electrophoresis. Magnetic particles are encapsulated by dry milling in a thermoplastic binder which is insoluble at ambient or room temperatures and is softenable at temperatures higher than 70.degree. C. A charge director for producing functional sites in the binder is incorporated in the encapsulating polymer during the dry-milling step. The encapsulated mass is comminuted or pulverized and then wet-milled with a major amount of a low-boiling aliphatic hydrocarbon liquid. A suspension is then formed with additional hydrocarbon liquid. Additional charge director may be added, either during the wet-milling step or during the suspension-forming step. The suspension is then used as a bath from which the coating is deposited by electrophoresis. The magnetic particles are oriented by the application of a magnetic field, either during the depositing step or subsequent thereto.

Abstract: A composition for developing latent electrostatic images comprising an aliphatic hydrocarbon carrier liquid having dispersed therethrough charged pigmented toner particles having a low charge to mass ratio. The composition has an amount of spacer particles having their smallest diameter greater than twenty microns and greatest diameter less than seventy microns disseminated therethrough. The spacer particles are adapted to form an air gap between the developed electrostatic image on a photoconductor, or dielectric support, and the medium to which the developed image is to be transferrred. The population of the spacer particles is such that their interparticle distance on the photoconductor is four millimeters or less. The spacer particles may be formed of any desired material, insoluble in the carrier liquid, and have any desired shape. A tetrahedral pyramidal shape or spherical shape is preferred.

Abstract: An improved toner control system having a pair of matched photosensitive devices connected in series and receiving equal amounts of light, wherein one device responds to light transmitted through the toner-containing developer and the other device responds to light transmitted through an adjustable aperture or attenuator.

Abstract: A braking mechanism for decelerating copy sheets being delivered to a stacking tray of an electrophotographic copier includes pairs of opposing feed rollers disposed at closely adjacent longitudinally spaced locations along the sheet path to the tray. The first pair of rollers are driven at a peripheral velocity equal to that of the upstream portions of the sheet transport assembly, while the second pair of rollers are driven through an overrunning clutch at a peripheral velocity equal to about one-third to one-half the velocity of the first pair of rollers. A copy sheet entering the nip of the second pair of rollers from the first pair of rollers acts as a rigid member to drive the second pair of rollers at the upstream velocity, overrunning the clutch. When the sheet emerges from the upstream nip, frictional drag slows the second pair of rollers down to the slower velocity of their drive source, causing the sheet to be delivered to the copy tray at a relatively low rate of speed to ensure even stacking.

Abstract: Sheet stacking and registration apparatus in which a jogging finger is slidable along an arm which is mounted for movement about a pivot axis between a lowered position and a raised position relatively adjacent the sheets being registered. The jogging finger is resiliently urged away from the stack in the raised position of the arm, while the arm is normally resiliently urged toward its lowered position. Tensioning of a line coupled to the jogging finger first draws the arm to its raised position adjacent the stack and then draws the jogging finger against the adjacent edge of the stack to register the sheets against a remote registration surface. In a preferred embodiment, a common actuating member is used to tension a plurality of such lines to actuate several jogging mechanisms simultaneously.

Abstract: A liquid developed electrophotocopier wherein liquid carrier dispersant transferred to a copy sheet concomitantly with the developed image is catalytically oxidized to provide harmless gaseous oxidation products at temperatures sufficiently elevated to vaporize transferred carrier and to dry and fix the transferred image. The catalytic fixer-dryer is brought rapidly to operating temperature by injecting an atomized spray of carrier liquid. The carrier liquid has a low auto-oxidation temperature; and the fixer-dryer is operated above such temperature to ensure complete oxidation of carrier vapors even though the catalyst may have been largely rendered inactive.

Abstract: An improved heater for electrophotographic copiers wherein a plurality of laterally spaced heaters dry or fix the transferred image along narrow longitudinally extending strips to prevent smearing of the image from subsequent contact with feed wheels or guides.

Abstract: A solar cell in which the essential feature is a thin film of lead-cadmium-sulphide alloy. This alloy is preferably formed by spray pyrolysis from a solution containing the necessary ingredients. The solar cell advantageously takes the form of a homojunction constructed of two layers of lead-cadmium-sulphide alloy, with one of the layers being p-doped and the other of the layers being n-doped. The solar cell may be produced with an intrinsic layer interposed between the p-type layer and the n-type layer. The solar cell may also be made with a semiconductive layer of lead-cadmium-sulphide in contact with a metallic substrate.

Abstract: An automatic control system for the bias on a development electrode in which a plurality of ground-insulated, narrow floating electrodes are spaced along a line adjacent the entrance of a liquid developer applicator unit. The floating electrodes relatively scan image areas of the surface of an organic photoconductor carried by a conductive support moving through the developer unit. Owing to conduction of a charge from the photoconductive surface through the developer liquid to the floating electrodes, they assume potentials each of which is a function of the average potential of the image area subtended by the floating electrode. The potential of each floating electrode is sensed by a high input impedance measuring circuit which selects the potential of the lowest value, amplifies the selected potential and applies the amplified voltage to the biasing electrode or electrodes of the developer system.