Xerox Corporation

Gary A Dir

Werner E Haas

James E Adams

Charles J Urso, Iii

Fred W Schmidlin

William L Lama

Joseph F Stephany

Stephen C Corona

Ned J Seachman

Alain E Perregaux

Joseph P Taillie

John D Sotack

John E Courtney

Donald A McTarnaghan

Douglas W Story

A system for printing gray levels without needing to use halftone cells. An architecture is disclosed for controlling printing elements to deposit a variable amount of toner onto a given area of paper. The architecture includes a pixel memory for determining a gray level for each pixel in a row, and a counter for incrementing a gray level. A comparator compares a memory location corresponding to a certain pixel with the output of the counter, and the comparison result is then applied to a printing element corresponding to the pixel.

Method and apparatus for producing variable width pulses to produce an

A liquid crystal birefringent MTF filter is permanently positioned between lens and array of an image input scanner to reduce image modulation at frequencies where moire occurs, with a source of electric potential and a control switch for selectively applying the potential and switching the filter to or from a filtering state. In a variation of the first embodiment, a two-stage MTF filter is used. In a second embodiment, a tunable liquid crystal scattering MTF filter is combined with a full width sensor array.

Electronically variable MTF filter for image sensor arrays

An electrophotographic reproduction device is described which is capable of forming images of an original document modified by information added to or replacing information of the original. A latent image of the document is formed on a photosensitive surface and a portion of the image, in a first embodiment, is maintained at the original charge level. This fully charged section is subsequently discharged in an image-wise pattern by a compact annotator device. The annotator includes an illumination source, an addressable light modulator device such as a liquid crystal panel and a lens array for forming the modulated light pattern onto the photosensitive surface.

Apparatus for forming composite images

An improved transient state liquid crystal image bar having enhanced contrast with lower required driving voltage. The image bar is of the type having a nematic liquid crystal cell configured as a single array of dot shutters energizable by a single freqency voltage with crossed polarizer and analyzer. The polarizing axis of the polarizer is at 45 degrees with the liquid crystal molecules in their rest state. Thus, when all the image bar shutters are energized, it is in the non-transmission condition. For bursts of light to pass, the voltage to selected dot shutters are interrupted and reapplied. In one embodiment, the improvement is achieved by an optical compensator or thin prism placed between the polarizer and the liquid crystal cell. In another embodiment, a quarterwave plate is placed between the liquid crystal cell and the analyzer, with the analyzer being rotated about the image bar's optical axis a predetermined angle from its initial crossed position with respect to the polarizer, so that there is increased extinction of the light exiting from the liquid crystal cell, when the liquid crystal material is in its normally stable energized state.

Transient state liquid crystal image bar with contrast enhancement

A liquid crystal display device having high extinction ratio polarizers on the input and output sides of a transmissive, twisted nematic liquid crystal cell. The liquid crystal cell incorporating a dichroic dye which is admixed with the liquid crystal material. The high extinction ratio polarizers get the full contrast and density capability from the liquid crystal cell while the dichroic dye prevents the buildup of the contrast limiting orthogonal mode of the polarized light passing therethrough, thus, further increasing the optical contrast and density. Such an arrangement provides optical contrasts of around 150:1 with a 10 micron thick liquid crystal cell.

High contrast liquid crystal display devices

A multicolor display which comprises a high contrast liquid crystal device, light source and a luminance balanced color mask. The liquid crystal device is the transmissive, twisted nematic type having high extinction ratio polarizers on the input and output sides and functions as a light shutter for the display. The liquid crystal material has a dichroic dye admixed therein to prevent buildup of the contrast limiting orthogonal mode electric vector of polarized light. The color mask contains different colored patches with gray surround about them, and each colored patch is luminance balanced in order that each different colored data presented are of substantially equal brightness. during the off-state there is no light bleed through so that the display presents a uniformly dark state or dead front.

Multicolor liquid crystal display with a dead front

Alignment films provided on a supportive substrate in accordance with the Janning technique exhibit birefringence wherein plane polarized light in passing through the alignment film becomes elliptically polarized. Birefringence compensation is provided by depositing a second alignment film on the other side of the supportive substrate in a direction substantially orthogonal to the deposition direction of the first alignment film, the second alignment film having a thickness substantially equal to that of the first alignment film.

Liquid crystal alignment film birefringence compensation

A composition responsive to magnetic fields and comprising a ferrofluid and metal flakes. The metal flakes align with the ferrofluid in response to magnetic lines of force and along the magnetic lines of force. Excellent contrast is provided between portions of the composition wherein the metal flakes are seen along edges or ends and portions of the composition wherein the broad surface area of the flakes are presented to view.

Imaging composition

A mixture of the Grandjean texture and the focal-conic texture of the cholesteric mesophase is created by applying an electrical field to a liquid crystalline material in either the focal-conic or Grandjean texture of the cholesteric mesophase of a magnitude sufficient to transform the liquid crystalline material from the cholesteric mesophase to the nematic mesophase; and, decreasing the magnitude of said electrical field over a period of time effective to transform the liquid crystalline material from the nematic mesophase to a mixture of the Grandjean and focal-conic textures of the cholesteric mesophase.

Mixed liquid crystalline texture formation

A magnetic display comprising, between two magnetic field permeable substrates, a ferrofluid and metal flakes, one of the substrates being provided with one or more selectively energizable electro-magnets.

Magnetic display

A lens is fabricated with a layer of liquid crystalline material between electrodes, wherein the liquid crystalline composition is capable of altering the state of polarization of light when a voltage is applied between the electrodes. A linear polarizer and an analyzer are used in conjunction with the lens, and optionally are incorporated into the lens.

Variable density lens

A magneto-optic cell comprising a composition responsive to magnetic fields. The composition comprises a ferrofluid and metal flakes which align with the ferrofluid in response to magnetic lines of force and along the magnetic lines of force. Detection of the presence of a magnetic field is thereby provided.

Magnetic field detector

An optically addressed light valve is disclosed which is cabable of being read-out at very high light intensities during the write-in cycle without need for an optical blocking layer. The system is based on the combination of a reflective photoconductor and an electro-optically active medium and exploits the characteristics of space charge limited currents in photoconductors of high optical absorption of actinic wavelengths.

Electrooptic-photoconductor sandwich using actinic readout light

Apparatus for viewing latent magnetic images on recorded magnetizable recording members. The apparatus comprises means for advancing a magnetizable recording member bearing a latent magnetic image into a detection station at which a magneto-optic cell provides a visible display of the latent magnetic image. Optionally, a projection system directs light in reflection from the visible display to a back lighted projection screen.

Recorded magnetic member viewing apparatus

A direct current liquid crystal display device for reflection viewing comprises a dielectric mirror having at least one pair of titanium dioxide and silicon dioxide layers, the titanium dioxide layer being in contact with a layer of liquid crystalline composition, between two electrodes.

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Fairport, NY, United States of America

Gary A Dir