Method and apparatus for recognizing meandering of web

Claim 2

A computer implemented method of recognizing meandering of a web, comprising the steps of: receiving signals that represent all pixel addresses and all pixel data of printed matter serving as a reference and determining whether each pixel represents an edge region in which an abrupt change in density occurs as an edge; storing, as reference data, the signals that represent the pixel address and pixel data only of each pixel determined to represent the edge region in which the abrupt change in density occurs as an edge; calculating a difference value signal between the signals that represent the pixel data of test image data obtained from the web on which a test object is printed and the signals that represent the pixel data of the reference data in accordance with the pixel addresses of the reference data in the edge region; comparing the difference value signal with a first predetermined value signal to count the number of edge pixels having difference value signals exceeding the first predetermined value signal in the edge region; recognizing the meandering state of the web when a total number of edge pixels having difference value signals exceeding the first predetermined value signal is not less than a predetermined number; and generating a meandering notification signal when the meandering state of the web is recognized.

Claim 3

A method according to claim 1, further comprising the step of clearing the total number of edge pixels to zero at an end of printing of the test object on the web.

Claim 4

A method according to claim 1, further comprising the step of updating and storing reference data for detecting a defective printed matter when the meandering state of the web is recognized.

Claim 5

A method according to claim 1, further comprising the steps of: accumulating absolute values of all difference values and averaging the absolute values to obtain a difference value in the edge region; and recognizing the meandering state of the web when the difference value exceeds a second predetermined value.

Claim 6

A computer implemented method of recognizing meandering of a web, comprising the steps of: receiving signals that represent all pixel addresses and all pixel data of printed matter serving as a reference and determining whether each pixel represents an edge region in which an abrupt change in density occurs as an edge; storing, as reference data, the signals that represent the pixel address and pixel data only to each pixel determined to represent the edge region in which the abrupt change in density occurs as an edge; calculating a difference value signal between the signals that represent the pixel data of test image data obtained from the web on which a test object is printed and the signals that represent the pixel data of the reference data in accordance with the pixel addresses of the reference data in the edge region; accumulating absolute value signals of all the difference value signals and averaging the absolute value signals to obtain a difference average value signal in the edge region; recognizing the meandering state of the web when the difference average value signals exceeds a predetermined value; and generating a meandering notification signal when the meandering state of the web is recognized.

Claim 7

A computer implemented method of recognizing meandering of a web, comprising the steps of: receiving signals that represent all pixel addresses and all pixel data of printed matter serving as a reference and determining whether each pixel represents an edge region in which an abrupt change in density occurs as an edge; storing, as reference data, the signals that represent the pixel address and pixel data only to each pixel determined to represent the edge region in which the abrupt change in density occurs as an edge; calculating a difference value signal between the signals that represent the pixel data of test image data obtained from the web on which a test object is printed and the signals that represent the pixel data of the reference data in accordance with the pixel addresses of the reference data in the edge region; accumulating absolute value signals of all the difference value signals and averaging the absolute value signals to obtain a difference average value signal in the edge region; recognizing the meandering state of the web when the difference average value signals exceeds a predetermined value; and generating a meandering notification signal when the meandering state of the web is recognized.

Claim 8

A method according to claim 5, further comprising the step of storing and updating, as reference data, the pixel address and pixel data only of each pixel determined to represent the edge region in which the abrupt change in density occurs as an edge when the meandering state of the web is recognized.

Claim 9

A method according to claim 5, further comprising the step of clearing the total number of absolute values of the difference values to zero at an end of printing of a test object on the web.

Claim 10

A method according to claim 5, further comprising the step of updating and storing the reference data for detecting a defective printed matter when the meandering state of the web is recognized.

Claim 13

An apparatus according to claim 9, wherein said meandering recognizing means is further comprised of a difference average calculating means for accumulating absolute values of the difference values and averaging the absolute values to obtain a difference average value, and a second comparing means for recognizing the meandering state of the web when the difference average value exceeds a predetermined value.

Claim 14

An apparatus according to claim 9, further comprising reference data updating means for updating and storing reference data for detecting a defective printed matter when the meandering state of the web is recognized.

Claim 17

An apparatus according to claim 9, wherein the total number of edge pixels is cleared to zero at an end of printing of the test object on the web.

Claim 18

An apparatus according to claim 12, further comprising an edge memory controller for storing and updating the reference data representing the edge when the meandering state of the web is recognized.

Claim 19

An apparatus according to claim 12, wherein the total number of absolute values of the difference values is cleared to zero at an end of printing of a test object on the web.

Claim 20

An apparatus according to claim 12, further comprising reference data updating means for updating and storing reference data for detecting a defective printed matter when the meandering state of the web is recognized.

Claim 21

A defective printed matter detecting apparatus comprising: reference data storing means for storing, as reference pixel data, all pixel data of a printed matter serving as a reference; defective printed matter detecting means for comparing all pixel data of the test image data of a web on which a test object is printed with all pixel data of reference image data stored in said reference data storing means in accordance with pixel addresses of the test image data and the reference image data to detect the defective printed matter; edge determining means for receiving all pixel addresses and all pixel data of the printed matter serving as the reference and determining whether each pixel represents an edge region in which an abrupt change in density occurs as an edge; edge data storing means for storing, as reference data, the pixel address and pixel data only of each pixel determined to represent the edge region in which the change in density occurs as an edge by said edge determining means; difference value calculating means for calculating a difference value between pixel data of the test image data obtained from the web on which a test object is printed and the pixel data of the reference data stored in said edge data storing means in accordance with the pixel addresses of the reference data stored in said edge data storing means; parameter calculating means for calculating a parameter on the basis of each difference value calculated by said difference calculating means; meandering recognizing means for determining whether the parameter calculated by said parameter calculating means exceeds a predetermined value to recognize a meandering state of the web; and a reference data control means for updating and storing data of said reference data storing means when the meandering state of the web is recognized by said meandering recognizing means.

Claim 22

A defective printed matter detecting apparatus comprising: reference data storing means for storing, as reference pixel data, all pixel data of a printed matter serving as a reference; defective printed matter detecting means for comparing all pixel data of the test image data of a web on which a test object is printed with all pixel data of reference image data stored in said reference data storing means in accordance with pixel addresses of the test image data and the reference image data to detect the defective printed matter; edge determining means for receiving all pixel addresses and all pixel data of the printed matter serving as the reference and determining whether each pixel represents an edge region in which an abrupt change in density occurs as an edge; edge data storing means for storing, as reference data, the pixel address and pixel data only of each pixel determined to represent the edge region in which the change in density occurs as an edge by said edge determining means; difference value calculating means for calculating a difference value between pixel data of the test image data obtained from the web on which a test object is printed and the pixel data of the reference data stored in said edge data storing means in accordance with the pixel addresses of the reference data stored in said edge data storing means; parameter calculating means for calculating a parameter on the basis of each difference value calculated by said difference calculating means; meandering recognizing means for determining whether the parameter calculated by said parameter calculating means exceeds a predetermined value to recognize a meandering state of the web; and a reference data control means for updating and storing data of said reference data storing means when the meandering state of the web is recognized by said meandering recognizing means.