Xerox Corporation

Other

Terri A Clingerman

Xing Li

Stuart Alan Schweid

Paul Allen Hosier

Leon C Williams

Roger Lee Triplett

Howard A Mizes

David Jon Metcalfe

Jeng-nan Shiau

Jess Robert Gentner

Raymond J Clark

Gerald L Coy

Nancy R Kelly

James W Stevens

Biruk Gossaye

Ralph H Huedepohl

Mark P Haefner

Ramakanth Desani

A method for dynamically compensating for thermal expansion and contraction of a light emitting diode print bar having first and second light emitting diodes having first and second ideal positions, respectively, the method including: a) determining a first measured position of the first light emitting diode and a second measured position of the second light emitting diode; b) comparing the first measured position and the second measured position to the first ideal position and the second ideal position, respectively; and, c) correcting a first difference between the first measured position and the first ideal position and a second difference between the second measured position and the second ideal position based on results from the step of comparing.

Dynamic control of thermal expansion induced imaging errors from light emitting diode (LED) print bars

A printer compensates for variations in ejected material drop volumes occurring during production of the layers for the formation of an object in a three-dimensional printer. The printer includes an optical sensor that generates topographical and measurement data of each layer of the object after each layer is printed. Differences in height between columns of material being formed by the ejectors in the printhead are identified with reference to the data produced by the sensor and raster data used to operate the printhead are modified adjust the formation of a next layer in the object.

System for compensating for drop volume variation during three-dimensional printing of an object

Systems and methods are provided for aligning a video clock with the raster output scanner start-of-scan signal in printing systems. A system and method is proposed to align the pixel clock to an asynchronous reference signal generated in the raster output scanner. The proposed system and method adjusts a phase for a static phase value while performing a dynamic phase shifting for the start-of-scan signal alignment.

Apparatus for alignment of video clock with the ROS start of scan sensor signal in printing systems

A method for determining a location on an image bearing surface of an image printing system where a toner image is to be printed is provided. The method comprises generating a first signal from a detector that is configured to detect a reference mark on the image bearing surface, and a second signal from a clock system that counts incremental movements of the image bearing surface, determining a first value that correlates the first signal and the second signal, where the first value corresponds to a value of the second signal at a start of characterization of the image bearing surface, and determining a second value using the first value, where the second value provides the location on the image bearing surface where the toner image is to be printed.

Method for accurately finding a physical location on an image bearing surface for toner images for optimal streak correction

Defects in an image forming system may give rise to scratched fiducials, missing fiducial regions, or other defects in an image that can run parallel to the process direction. The present disclosure provides for a fiducial compensation method and system for detecting defects thereby allowing spatial tone reproduction curves to be calculated and applied to a digital image in order to eliminate printed streaks due to a photoreceptor's non-uniformities.

Fiducial artifact detection and compensation algorithm

A document size identification module receives a single scan of a document and detects for at least one of a black to white transition and a white to black transition. The black to white transition may represent a transition from an overscan area of a platen to a document. The white to black transition may represent a transition from the document to the overscan area of the platen. By detecting at least one of the black to white transition and the white to black transition, the document width may be determined. By determining the document width, the document size may be identified.

Method and apparatus for identifying document size

Disclosed methods and systems perform electronic registration of digitally captured images in real-time and performs accurate and robust digital image processing by analyzing the entire digitally captured image.

Document registration and skew detection system

Detecting skew and determining skew angle using the front of a document by determining background-to-document transitions. Incoming scanlines are interval sampled in the fast scan direction every nth pixel. The samples are collected and organized into a two dimension array comprised of scanline based rows and interval based columns. The collected and organized samples are analyzed by intervals to determine a scanline (row) where a specified sampling condition exceeds predetermined threshold. The corresponding row-interval point forms a background-to-medium transition point of the edge of a document. When two or more background-to-medium transition points are found from different intervals the skew angle can be determined using linear regression.

Detecting skew angle in a scanned image

A method and apparatus are provided for determining a weighted average measured reflectance parameter R for pixels in an image for use in integrated cavity effect correction of the image. For each pixel of interest P in the image, an approximate spatial dependent average A , B of video values in a region of W pixels by H scan lines surrounding the pixel of interest P is computed by convolving video values V of the image in the region with a uniform filter. For each pixel of interest P a result of the convolving step is used as the reflectance parameter R . The apparatus includes a video buffer for storing the pixels of the original scanned image, and first and second stage average buffers for storing the computed approximate spatial dependent averages A , B . First and second stage processing circuits respectively generate the first and second stage average values A , B by convolving the video values of the image in a preselected region with a uniform filter.

Method and apparatus for implementing integrated cavity effect correction in scanners

A structure for implementing a plurality of two-dimensional digital filters, such as finite impulse response filters, in an efficient manner. The structure includes a plurality of first stage filters operating in a first dimension in combination with a single second stage filter, operating in a second dimension. The second stage filter being suitable for receiving output from one of the first stage filters. A controller, operating in conjunction with the first and second stage filters is utilized for controlling the operation of all filters, as well as the selection of the input source for the second stage filter.

Method and apparatus for implementing two-dimensional digital filters

Method and apparatus for providing interpolated image data from original image data represented in terms of pixels, each pixel defined in terms of value and position in an original image, includes an original image input receiving original image data from an original image source; a page memory operatively connected to the input for storing a page of original image received; a source of interpolation parameters indicating: a slow scan initial pixel value Xinit, a fast scan initial pixel value Yinit, a fast scan x offset value FSx, a fast scan y offset value FSy, a slow scan x offset value SSx, and a slow scan y offset value SSy; a bilinear sequencer calculating for each new pixel, from the received parameters a reference pixel within the image, and a pair of interpolation coefficients for interpolating new pixel values; a memory controller retrieving to an interpolation calculator from the page memory a set of original image pixels including the pixel at the reference position, and three other pixels whose position is a predetermined function of the position of the reference position pixel for each new pixel; and an interpolation calculator calculating a new pixel value as a function of the set of original pixels directed to it by the bilinear sequencer.

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Palmyra, NY, United States of America

Terri A Clingerman