Abstract:
An image forming apparatus comprises a light source, a photosensitive member and a control unit. The light source turns on in response to a driving current supplied based on image data. An electrostatic latent image is formed on the photosensitive member by exposing the photosensitive member to a light beam output from the light source turned on. The control unit controls the value of the driving current supplied to the light source in accordance with a driving state of the light source so that the value of the driving current supplied to the light source differs and changes with the passage of time in accordance with the driving state of the light source prior to the driving current being supplied to the light source.
Abstract:
In one aspect of the invention there is disclosed a multicolor thermal imaging system wherein different heating elements on a thermal print head can print on different color-forming layers of a multicolor thermal imaging member in a single pass. The line-printing time is divided into portions, each of which is divided into a plurality of subintervals. All of the pulses within the portions have the same energy. In one embodiment, every pulse has the same amplitude and duration. Different colors are selected for printing during the different portions by varying the fraction of subintervals that contain pulses. This technique allows multiple colors to be printed using a thermal print head with a single strobe signal line. Pulsing patterns may be chosen to reduce the coincidence of pulses provided to multiple print head elements, thereby reducing the peak power requirements of the print head.
Abstract:
An image forming apparatus records an image on a photosensitive material by controlling a light emission amount from a plurality of light emission elements that each emit light in accordance with a supplied light emission control signal. The apparatus has a control signal generation unit and a first and second signal generation sections and a signal switching section. The control signal generation unit generates a first light amount control signal from a density modulation. The second signal generation section generates an ON/OFF control signal and a second light amount control signal as a pair of signals from a combination of a density modulation and an area modulation. The signal switching section generates a light emission control signal by performing signal switching between the first light amount control signal and the pair of the signals. The exposure by the light emission is overlaid. The second light amount control signal has short pulses having pulse widths shorter than a time constant of the initial rising stage of the light emission.
Abstract:
An electrostatographic reproduction apparatus having a transfer assembly, including an electrically biased transfer roller in nip relation with a dielectric support member, for effecting transfer of a pigmented marking particle image from an image area of a dielectric support member to a receiver member in transfer relation with the dielectric support member in the transfer nip, a mechanism for cleaning the transfer roller including a control for the electrical bias on the transfer roller. The electrical bias control has a power supply generating an electrical output, of a settable polarity, connected to the transfer roller for applying an electrical bias of a set polarity thereto. A timing signal generator produces signals respectively corresponding to the location of a receiver member relative to the transfer nip. A mechanism, responsive to the signal from the timing signal generator, indicating the passing of the trail edge of a receiver member through the transfer nip, reverses the setting of the polarity of the electrical output from the power supply so as to prevent transfer of residual marking particles from the dielectric support member to the transfer roller.
Abstract:
Odd- and even-numbered conductors of recording electrodes, for example, first or second recording electrodes, are divided in the direction in which the conductor at the time of winding are stacked up to form different layers so as to increase the distance between the conductors of the adjoining recording electrodes and reduce the floating electrostatic capacitance.
Abstract:
A power module including an RC circuit is uniquely associated with each of a plurality of electrodes of an electrostatic print head to individually control the rate of charge decay of a voltage disposed thereon. The resistor of the RC circuit is a potentiometer that may be manually adjusted to obtain an optimal decay rate. A paper supply roller and take-up roller accurately position dielectric material, such as a paper web, adjacent to the electrodes of the print head, which is located between the rollers. The electrodes are typically a plurality of wires. The print head moves across the width of paper web to dispose thereon a plurality of charge areas corresponding to a strip of a latent image. Control circuitry synchronizes the movement of the print head and the web to produce a plurality of abutting strips of charge areas, producing a complete latent image. A toner applicator is positioned downstream from the print head to dispose ionized toner particles which adhere to the plurality of charge areas, thereby producing a visible image.
Abstract:
A method and apparatus are provided for "field effect imaging" of moving substrates, such as webs of paper. Non-conductive, non-magnetic toner having approximately a 5-20 micron mean particle size is electrically charged to a level of at least about 8 micro Coulombs/gram and then a first roller with a conductive surface is brought into operative association with the electrically charged toner so that toner particles adhere to the surface. The toner particles are preferably maintained in an electrostatic fluidized bed, and charged by a corona element in the bed. An array of pin or stylus primary electrodes are selectively energized or de-energized to provide no-write or write condition, respectively using a computer to switch the electrodes into or out of operative connection to a source of electrical potential. The toner particles are transferred from the first roller to a substrate either directly (after passing past the primary electrodes), or they are first transferred to a second roller which then brings the toner particles into contact with the substrate. If a second roller is utilized, the primary electrodes can be in association with the first roller, or between the first and second rollers for transferring only "write" toner to the second roller.
Abstract:
In a page or a line printer, a printer head comprises a resilient substrate, as of borosilicate glass, a strain responsive film of a first ferroelectric material, such as lead zirconate titanate, on the substrate, and a voltage responsive film of a second ferroelectric material, such as lead lanthanum zirconate titanate, on the strain responsive film to form a stack. Responsive to a driving signal representative of a pattern, a piezoelectric driving member inverts, into an inverted residual polarization representative of the pattern as a latent image, an initial residual polarization which is preliminarily produced in the voltage responsive film in its thickness direction by application of a driving voltage to the piezoelectric driving electrode member. The signal or the voltage produces in the substrate a travelling elastic wave which gives a strain and an electric voltage in compliance with the strain. The electric voltage gives rise to the residual polarization. Preliminary charged to a polarity opposite to that of the latent image, an electrostatic toner is supplied to a first end of the voltage responsive film and moved towards a second end by a travelling elastic wave produced in the substrate concurrently with supply of the toner to the first end by supplying a signal to the piezoelectric driving electrode member for production of a toner moving travelling elastic wave.
Abstract:
A reproduction method for continuous tone images on an output device having multilevel capabilities is described. The microdots addressable by the output device are arranged into identical tiles. The microdots in a tile get a sequence number, according to a randomised Bayer pattern for which the runlengths of microdots having low sequence numbers are reduced. The sequence is divided into five subsequences. The microdots belonging to the first three subsequences are changed exclusively to higher density levels for decreasing intensity levels, each within a specific intensity range of the input image. The microdots belonging to the last two subsequences are used to more continuously reproduce the image levels. Equivalent microdots within a tile are further differentiated by a second sequence numbering, in order to ensure smooth and precise average density transitions in reproduced continuous tones.
Abstract:
An electrographic writing head capable of placing continuous marks upon a record medium in response to the application of a high voltage to selected writing styluses. The writing head includes a substrate upon which stylus electrodes, multiplexed driver circuitry and active devices are integrally fabricated by thin film deposition techniques. For each stylus, there is provided a high voltage thin film transistor and a latching circuit for holding the state of the high voltage transistor for substantially an entire line writing time.