Dynamic reflective density measuring and control system for a web printing press
First Claim
1. Apparatus for measuring the reflective density of at least a first color printed on a moving web during operation of a web printing press of the type which has an adjustable ink zone control mechanism for controlling the amount of ink of said first color that is available to be transferred to the web at spaced locations across the width of the press during a printing operation and which has a printing roller which transfers ink to the web, there being a nonprint area that extends in the lateral direction of the web resulting from attachment of printing plates to the printing roller, the press having a color block set on the web generally at each spaced location, the color block set including at least said first color, said apparatus comprising:
- means for acquiring a digitized image of predetermined size of the web, said image being comprised of a plurality of individual pixels, each having an intensity value within a predetermined range;
memory means for storing said digitized images;
strobe means for illuminating at least said predetermined area of the web when said strobe means is fired;
means for calibrating said acquiring means to provide predetermined values for high and low light reflectivity levels of said digitized images;
means for measuring the presence and intensity of printed matter located in an acquired digitized image of at least a portion of one of said color block sets, and generating light scattering compensation signals for compensating for the presence of printed matter that affects the measured reflective density of at least said first color;
processing means for analyzing an acquired digitized image of a uniform surface of a standard stored in said memory means, said processing means analyzing a digitized image to determine the intensity of illumination for a plurality of locations throughout said image acquired during the firing of said strobe means, and generating light discontinuity compensation signals for compensating for uneven illumination among said locations;
said processing means being adapted to analyze the digitized images containing at least said first color and produce a reflective density value thereof, said reflective density value having been corrected by said light scattering compensation signals and said light discontinuity compensation signals.
1 Assignment
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Accused Products
Abstract
A system for use with a web printing press for measuring the reflective density of printed ink in real time during high speed operation. The system digitizes images of color block sets of the web, analyzes the images to determine reflective density of cyan, magenta, yellow and black. The system compensates for light scattering, light discontinuities and strobe intensity variation.
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Citations
59 Claims
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1. Apparatus for measuring the reflective density of at least a first color printed on a moving web during operation of a web printing press of the type which has an adjustable ink zone control mechanism for controlling the amount of ink of said first color that is available to be transferred to the web at spaced locations across the width of the press during a printing operation and which has a printing roller which transfers ink to the web, there being a nonprint area that extends in the lateral direction of the web resulting from attachment of printing plates to the printing roller, the press having a color block set on the web generally at each spaced location, the color block set including at least said first color, said apparatus comprising:
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means for acquiring a digitized image of predetermined size of the web, said image being comprised of a plurality of individual pixels, each having an intensity value within a predetermined range; memory means for storing said digitized images; strobe means for illuminating at least said predetermined area of the web when said strobe means is fired; means for calibrating said acquiring means to provide predetermined values for high and low light reflectivity levels of said digitized images; means for measuring the presence and intensity of printed matter located in an acquired digitized image of at least a portion of one of said color block sets, and generating light scattering compensation signals for compensating for the presence of printed matter that affects the measured reflective density of at least said first color; processing means for analyzing an acquired digitized image of a uniform surface of a standard stored in said memory means, said processing means analyzing a digitized image to determine the intensity of illumination for a plurality of locations throughout said image acquired during the firing of said strobe means, and generating light discontinuity compensation signals for compensating for uneven illumination among said locations; said processing means being adapted to analyze the digitized images containing at least said first color and produce a reflective density value thereof, said reflective density value having been corrected by said light scattering compensation signals and said light discontinuity compensation signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 54)
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42. Apparatus for measuring the reflective density of at least a first color printed on a moving web during operation of a web printing press of the type which has an adjustable ink zone control mechanism for controlling the amount of ink of said first color that is available to be transferred to the web at spaced locations across the width of the press during a printing operation and which has a printing roller which transfers ink to the web, there being a nonprint area that extends in the lateral direction of the web, the nonprint area resulting from attachment of printing plates to the printing roller, the press having a color block set on the web generally at each spaced location, the color block set including at least said first color, said apparatus comprising:
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a multiple CCD matrix sensor for acquiring a matrix image of the web of predetermined size; means for digitizing said image so that it is comprised of a large number of individual pixels, each of which can have an intensity value within a predetermined range, memory means for storing at least one digitized image; strobe means for illuminating the web when said strobe means is fired in response to strobe control signals being applied thereto; carriage means for mounting said CCD matrix sensor and said strobe means and for moving the same across the width of the web for acquiring digitized images of desired areas of the web in response to position control signals being applied thereto; means for calibrating said CCD matrix sensor means and said digitizing means to provide respective predetermined values for high and low light reflectivity levels of said digitized images; means for measuring the presence and intensity of printed matter located in an acquired digitized image of a color block set, and generating a light scattering compensation signal for compensating for the presence of printed matter that affects the measured reflective density of at least said one color; processing means for analyzing said digitized images acquired by said CCD matrix sensor means and stored in said memory means; said processing means analyzing a digitized image of a uniform highly reflective surface produced by the firing of said strobe means to determine the intensity and color of illumination at a plurality of locations throughout said image of predetermined size and generating light discontinuity compensation signals for compensating for discontinuities of illumination at said locations where said intensity is determined; said processing means being adapted to analyze the digitized images of said color block sets and utilizing said light scattering compensation signals and said light discontinuity compensation signals, produce a reflective density value of said at least first color that is compensated for light scattering and light discontinuity. - View Dependent Claims (43)
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44. Apparatus for measuring the reflective density of at least one color block printed on a moving web having a predetermined width during operation of a web printing press of the type which has an adjustable ink zone control mechanism for controlling the amount of ink of said first color that is available to be transferred to the web at spaced locations across the width of the press during a printing operation and which has a printing roller which applies ink on the web, said press having printed a color block set on the web at predetermined locations relative to each ink zone control mechanism spaced location, the color block set at least including the color block of said first color, said apparatus comprising:
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a multiple CCD matrix sensor for acquiring a matrix image of the web of predetermined size; means for digitizing said image so that it is comprised of a large number of individual pixels, each of which can have an intensity value within a predetermined range; memory means for storing at least one digitized image; strobe means for illuminating the web when said strobe means is fired in response to strobe control signals being applied thereto; carriage means for mounting said CCD matrix sensor and said strobe means and for moving the same across the width of the web for acquiring digitized images of desired areas of the web in response to position control signals being applied thereto; means for calibrating said CCD matrix sensor means and said digitizing means to provide predetermined values for high and low light reflectivity levels of said digitized images; means for measuring the presence and intensity of printed matter located in an acquired digitized image of a color block set, and generating a light scattering compensation signal for compensating for the presence of printed matter that affects the measured reflective density of at least said first color; processing means for analyzing said digitized images and stored in said memory means; said processing means being adapted to analyze the digitized images of said color block sets and utilize said light scattering compensation signals to produce a reflective density value of said at least first color that is compensated for light scattering. - View Dependent Claims (45)
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46. A method for determining the reflective density value of ink of at least a color block of a first color printed on a moving web having a predetermined width during operation of a web printing press of the type which has an adjustable ink zone control mechanism for controlling the amount of ink of said first color that is available to be transferred to the web at spaced locations across the width of the press during a printing operation and which has a printing roller which applies ink on the web, there being a nonprint area that extends in the lateral direction of the web resulting from attachment of printing plates to the printing roller, said press having printed a color block set on the web at predetermined locations relative to each ink zone control mechanism spaced location, the color block set including the color block of said first color, said method comprising:
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acquiring a matrix image of the color block set by activating a CCD matrix sensor and a strobe means at a portion of the web containing the color block set; digitizing said matrix image to produce a digitized image, said digitized image being comprised of a large plurality of individual pixels, each pixel having an intensity value within a predetermined range; identifying the pixels of said color block and analyzing a predetermined number of said color block pixels to determine valid pixels, said pixels being valid when their associated intensity values are below a predetermined threshold; adjusting the intensity values of each of said valid pixels to compensate for discontinuities in the total amount of light produced by the strobe means during the acquiring of the image; adjusting the intensity values of each of said valid pixels to compensate for light scattering effects that are influenced by the existence and nature of printed matter within the image adjacent to the color block set; and
,averaging the adjusted intensity values of said predetermined number of valid pixels to produce said reflective density value. - View Dependent Claims (47, 48, 49)
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50. A method for determining the edge of a moving web during operation of a web printing press, said press being of the type which has a printing roller which transfers ink to the web, there being a nonprint area in printing that extends in the lateral direction of the web because of the attachment of a printing plate to the roller, said method comprising the steps of:
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acquiring a digitized image of a portion of the web by moving a CCD matrix sensor means to a location on the web near an edge and activating the CCD matrix sensor means in conjunction with firing a strobe means for illuminating the web during the image acquiring step, the image being comprised of a matrix of individual pixels each having an intensity value within a predetermined large range, with the pixels of an image of unprinted web having a low standard deviation of intensity values, the pixels of an image of the web support roller having a high standard deviation of intensity values, and the pixels of a printed web portion having a standard deviation of intensity values generally comparable to the standard deviation of intensity values of the web support roller; analyzing said image to determine the existence of low standard deviation of intensity value of the pixels and determining the edge of the web by moving in a direction toward one of the edges and detecting the location of where the pixels cease having said low standard deviation of intensity values, thereby locating the edge of the web, acquiring one or more successive new images in the longitudinal direction of the web in the event low standard deviation of intensity value were determined not to exist in each previous image and analyzing the pixels of the new image generally in the longitudinal direction of the web until low standard deviation of intensity value of the pixels are determined to exist, and thereafter determining the edge of the web by moving in a direction toward one of the edges and detecting the location of where the pixels cease having said low standard deviation of intensity values, thereby locating the edge of the web.
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51. A method for determining the edge of a moving web during operation of a web printing press, wherein the web has a plurality of color block sets printed thereon in the lateral direction of the web at predetermined locations, said plurality of color block sets also having been printed at successive locations in the longitudinal direction of the web, the color block sets including a color block of at least a first color, the press being of the type which has a printing roller which transfers ink to the web, there being a nonprint area in printing that extends in the lateral direction of the web because of the attachment of a printing plate to the printing roller, the nonprint area being a predetermined longitudinal distance from said plurality of predetermined color block set locations, said method comprising the steps of:
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acquiring a digitized image of a portion of the web containing a color block set by moving a CCD matrix sensor means to a location on the web where a color block set is located and activating the CCD matrix sensor means in conjunction with firing a strobe means for illuminating the web during the image acquiring step, the image being comprised of a matrix of individual pixels each having a standard deviation of intensity values within a predetermined large range, with the pixels of an image of unprinted web having a low standard deviation of intensity values, the pixels of an image of the web support roller having a standard deviation of intensity values less than that of the unprinted web, and the pixels of a printed web portion having a standard deviation of intensity values generally comparable to the standard deviation of intensity value of the web support roller; analyzing said image to determine the location of a color block set; acquiring a new image longitudinally displaced said predetermined longitudinal distance relative to the prior image containing the color block set and analyzing the pixels of the new image by moving in a direction toward one of the edges and detecting the location of where the pixels cease having said low standard deviation of intensity values, thereby locating the edge of the web.
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52. A method for measuring the reflective density of at least a first color printed on a moving web during operation of a web printing press, said press having printed a color block set on the web, the color block set including a sample of said first color, said method comprising the steps of:
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acquiring a digitized image of a highly reflective standard by moving a CCD matrix sensor means to a location where said highly reflective standard is located, acquiring a matrix image thereof, digitizing the matrix image and generating a predetermined reflectivity value therefor; acquiring a digitized image of a highly nonreflective standard by moving a CCD matrix sensor means to a location where said highly nonreflective standard is located, acquiring a matrix image thereof, digitizing the matrix image and generating a predetermined reflectivity value therefor; analyzing said acquired digitized image of said reflective standard by measuring the pixel values at a plurality of locations throughout said acquired image and generating light discontinuity compensation signals for compensating for discontinuities of illumination at said locations where said values are measured; acquiring a digitized image of a portion of the web by moving a CCD matrix sensor means to a location on the web where the color block set is printed and activating the CCD matrix sensor means in conjunction with firing a strobe means for illuminating the color block set during the image acquiring step, acquiring a matrix image thereof, digitizing the matrix image; storing the digitized images of said color block set in a memory means; measuring the intensity of illumination produced by said strobe means during a firing thereof and producing an intensity signal indicative of the intensity and color measured; measuring the presence and intensity of printed matter located in an acquired digitized image having a color block set, and generating a light scattering compensation signal for compensating for any light scattering effects that are influenced by the presence and nature of printed matter in the image that affects the measured reflective density of at least said first color in the image; analyzing the stored digitized images of said color block sets and producing a reflective density value of at least said first color, said reflective density value having been compensated for by said strobe intensity and color signals, said light scattering compensation signals and said light discontinuity compensation signals.
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53. Apparatus for measuring the reflective density of at least a first color of a color block set printed on a moving web during operation of a web printing press, said apparatus comprising:
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means for acquiring a digitized image of predetermined size of the web, said image being comprised of a plurality of individual pixels; memory means for storing said digitized images; strobe means for illuminating at least said predetermined area of the web when said strobe means is fired; means for calibrating said acquiring means to provide predetermined values for high and low light reflectivity levels of said digitized images; processing means for analyzing said digitized images containing at least said first color and produce a reflective density value thereof.
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55. A printed target pattern for printing on a test print area of an elongated web by a web printing press, said pattern being adapted for use in determining a print contrast value of ink printed on the web, said target pattern comprising:
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a solid print area; a nonsolid generally uniformly screened print area having ink printed thereon which covers a percentage of said nonsolid print area, said percentage being within a predetermined range; wherein said solid print area and said nonsolid print area are positioned adjacent one another substantially in the longitudinal direction of the web. - View Dependent Claims (56)
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57. Apparatus for measuring the reflective density of a block of predetermined size and color printed on a moving web of a web printing press, said apparatus comprising:
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means for acquiring a digitized matrix image of a predetermined size of the moving web including said block, said digitized image being comprised of a plurality of individual pixels having an intensity value within a first predetermined range; means for analyzing said image to determine that said image contains a first predetermined number of pixels of said block to comprise a valid block, said analyzing means analyzing said pixels of said valid block to determine the reflective intensity thereof. - View Dependent Claims (58, 59)
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Specification