Agfa Gevaert Nv

Freddy M Librecht

Lucien A De Schamphelaere

Willy F Van Peteghem

Etienne M De Cock

Willy G Verlinden

Werner E De Bondt

Gerard J Boeve

A method is disclosed of adjusting the light-emission of a light-emitting diode to a predetermined output level for a given driving current. The light-emitting diode is irradiated with a laser beam in a manner to burn tiny holes in the light-emitting surface to such an extent that said predetermined output level is obtained. The invention furthermore comprises a method of obtaining a substantially uniform light output of an array of light-emitting diodes.

Method of adjusting the light-emission of a light emitting diode at a

A method of producing toner-developed electrostatic images involving the repetitive performance of a copying cycle comprising the steps of corona charging a photoconductive layer at a determined voltage level, information-wise photo-exposing said charged photoconductive layer, developing the exposed photoconductor with charged toner particles to a toner image, transferring the applied toner image to a receptor, and restoring the photoconductive layer to a rest potential for the next cycle; and between successive copying cycles, maintaining said photoconductor in the dark for a randomly varying time period. The number of performed copying cycles in each series is registered by electronic means and an output signal is generated; the period of time between series that the photoconductor is maintained in the dark is measured and a corresponding output signal is generated. The respective output signals are inputed to electronic control means which (a) based on a relation between the actual surface potential of the photoconductor and the number of copying cycles performed in a series, measures the voltage change in the photoconductor surface from the actual number of cycles in a series, (b) based on a relation between the actual change in surface potential of the photoconductor and the dark recovery duration measures the voltage change in the surface potential after an actual dark recovery period, (c) and then gives a combined control signal indicating the overall change in surface potential from the beginning of one series of cycles to the beginning of the next series. Finally, the corona voltage is regulated substantially according to the combined control signal.

Electrostatic copying method including compensation for photoconductor

Toner dispensing control in a xerographic printer wherein a toner dispenser is controlled in response to a reference magnetic density value that is variable during the running-in period of a fresh toner mixture, thereby to take account of the changing packing density of the mixture during such period.

Toner dispensing control

Toner dispensing control in xerographic printing, wherein a toner dispenser is controlled during a first period of use by means measuring the exposing radiation applied to the photoconductor, and during a further period of use by means responsive to the relative permeability of the toner mixture. Thus, over-tonering during the running-in period of a new toner mixture is avoided.

Toner dispensing control in xerographic printing, wherein a toner dispenser is controlled during the initial period of use of a new toner mixture by a first control unit that is at least predominately responsive to the number of discrete exposures of the photoconductor, and during a further period of use a second control unit that is at least predominately responsive to the relative electrical permeability of the toner mixture. Over-tonering during the running-in of a new toner mixture is thereby avoided.

A recording apparatus for linewise recording information on a moving photoreceptor, comprising a recording head with two staggered rows of pointlike radiation sources, wherein a shortcoming of prior art devices, namely stepwise deformation of a recorded line, caused by an incorrect registering of the even and uneven data dots, as a consequence of speed fluctuations of the photoreceptor upon recording, is overcome by controlling the recording of the data signals as a function of a signal from a speed sensor of the photoreceptor.

Recording apparatus

In a recording apparatus comprising a recording head with a multiplicity of individually addressable and energizable point-like radiation sources arranged in staggered parallel rows for irradiating points across a moving photoreceptor, the driver circuits for the different rows of radiation sources are provided by identical chips. Each chip incorporates delay means capable of holding data-bit signals for a delay period before the signals are transmitted for energizing the associated radiation sources but is formed so that the delay means can be rendered inoperative by selecting one or other of different mode control voltage input points. The control chips for one row of the radiation sources are set in the delay-operative mode to compensate for the distance between the two rows of sources.

A recording device for linearly recording information upon a moving photoreceptor using a recording head that can be manufactured more readily. The recording head is made with a plurality of modules, each module comprising LED chip means having an aggregate length (n) greater than the length (o) of the base plate of the module and projecting exteriorly of the module side edges, and a common integrated control circuit for all the LED's mounted on the base plate of a given module, the outputs of such circuit being connected by wire bonding to the respective LED's on the module.

Recording apparatus with modular LED array of higher production yield

A recording apparatus for linewise recording information on a moving photoreceptor by means of a plurality of chips on each of which parallel sub-rows of uniformly spaced radiation sources are formed, wherein a shortcoming of prior art apparatus, namely the impossibility to use chips on which even one radiation source only is defect, is overcome. The apparatus comprises two parallel rows of radiation sources, each row comprising reserve radiation sources that are arranged with corresponding basic radiation sources of the other group in optical parallelism, and connection circuit means for establishing electrical contact with a basic and/or a reserve radiation source (FIG. 5).

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Boechout, Belgium

Freddy M Librecht