EP0184907A1 — Web registration measurement system

Claim 1

Independent Claim 128 words

Web register measurement apparatus for use with a travelling web (30) carrying register marks (32, 34) of a predetermined shape and predetermined spacing along the direction of web travel, comprising illuminating means (20, 22, 26, 27) for illuminating a spot on the web, detecting means (45) for detecting light reflected from the spot on the web and producing an output (70, 71, 72) representative of the intensity of the reflected light, characterised in that analysing means (12) are provided for analysing the said output (70, 71, 72) to determine the exact moment of the minimum value (73) of the intensity of the reflected light and for determining the time intervals between the occurrences of such minimum values, lateral and/or longitudinal registration errors being deducible from said time intervals.

Claim 2

Dependent Claim 128 words

Web register measurement apparatus for use with a travelling web (30) carrying register marks (32, 34) of a predetermined shape and predetermined spacing along the direction of web travel, comprising illuminating means (20, 22, 26, 27) for illuminating a spot on the web, detecting means (45) for detecting light reflected from the spot on the web and producing an output (70, 71, 72) representative of the intensity of the reflected light, characterised in that analysing means (12) are provided for analysing the said output (70, 71, 72) to determine the exact moment of the minimum value (73) of the intensity of the reflected light and for determining the time intervals between the occurrences of such minimum values, lateral and/or longitudinal registration errors being deducible from said time intervals.

Claim 3

Dependent Claim 210 words

Web register measurement apparatus for use with a travelling web (30) carrying register marks (32, 34) of a predetermined shape and predetermined spacing along the direction of web travel, comprising illuminating means (20, 22, 26, 27) for illuminating a spot on the web (30) and detecting means (45) for detecting light reflected from the spot on the web (30) and producing an output (70, 71, 72) representative of the intensity of the reflected light, characterised in that a mask (24) is interposed either between the illuminating means (20, 22, 26, 27) and the web (30) or between said web (30) and said detecting means (45), the said mask (24) carrying a pattern consisting of at least one light-transmitting area (25, 125, 225, 325, 425) and non-transmitting area(s), the said pattern being correlated with the said register marks (32, 34) so as to produce a well-defined transition in the magnitude of the said output (70, 71, 72) either when the image of said at least one light-transmitting area (25, 125, 225, 325, 425) falls on a said register mark (32) (or a part thereof) or when the image of said register mark (32) (or a part thereof) falls on said at least one light-transmitting area (25, 125, 225, 325, 425), respectively.

Claim 4

Dependent Claim 210 words

Web register measurement apparatus for use with a travelling web (30) carrying register marks (32, 34) of a predetermined shape and predetermined spacing along the direction of web travel, comprising illuminating means (20, 22, 26, 27) for illuminating a spot on the web (30) and detecting means (45) for detecting light reflected from the spot on the web (30) and producing an output (70, 71, 72) representative of the intensity of the reflected light, characterised in that a mask (24) is interposed either between the illuminating means (20, 22, 26, 27) and the web (30) or between said web (30) and said detecting means (45), the said mask (24) carrying a pattern consisting of at least one light-transmitting area (25, 125, 225, 325, 425) and non-transmitting area(s), the said pattern being correlated with the said register marks (32, 34) so as to produce a well-defined transition in the magnitude of the said output (70, 71, 72) either when the image of said at least one light-transmitting area (25, 125, 225, 325, 425) falls on a said register mark (32) (or a part thereof) or when the image of said register mark (32) (or a part thereof) falls on said at least one light-transmitting area (25, 125, 225, 325, 425), respectively.

Claim 5

Dependent Claim 213 words

For use with web register measuring apparatus that includes means (20, 22, 26, 27) for illuminating a spot on a travelling web (30) and detecting means (45) which are responsive to the reflected brightness of the spot which varies with the passage of register marks (32, 34) of a predetermined shape and spacing applied on the web (30) and which are adapted to provide a corresponding electrical output (70, 71, 72), a mask (24) adapted to be interposed between either the illuminating means (20, 22, 26, 27) and the web (30) or between the web (30) and the detecting means (45), said mask (24) being provided with a pattern of at least one light-transmitting area (25, 125, 225, 325, 425) and at least one non-transmitting area, the said pattern being correlated with the said register marks (32, 34) so as to produce a well-defined transition in the magnitude of the said output (70, 71, 72) either when the image of said at least one light-transmitting area (25, 125, 225, 325, 425) falls on a said register mark (32, 34) (or on a part thereof) or when the image of a said register mark (32, 34) (or a part thereof) falls on said at least one light-transmitting area (25, 125, 225, 325, 425), respectively.

Claim 6

Dependent Claim 213 words

For use with web register measuring apparatus that includes means (20, 22, 26, 27) for illuminating a spot on a travelling web (30) and detecting means (45) which are responsive to the reflected brightness of the spot which varies with the passage of register marks (32, 34) of a predetermined shape and spacing applied on the web (30) and which are adapted to provide a corresponding electrical output (70, 71, 72), a mask (24) adapted to be interposed between either the illuminating means (20, 22, 26, 27) and the web (30) or between the web (30) and the detecting means (45), said mask (24) being provided with a pattern of at least one light-transmitting area (25, 125, 225, 325, 425) and at least one non-transmitting area, the said pattern being correlated with the said register marks (32, 34) so as to produce a well-defined transition in the magnitude of the said output (70, 71, 72) either when the image of said at least one light-transmitting area (25, 125, 225, 325, 425) falls on a said register mark (32, 34) (or on a part thereof) or when the image of a said register mark (32, 34) (or a part thereof) falls on said at least one light-transmitting area (25, 125, 225, 325, 425), respectively.

Claim 7

Dependent Claim 65 words

Apparatus according to claim 2, characterised in that (see Figure 9) the said pattern is generally of diamond shape and contains a plurality of diamond shaped and/or rectangular light-transmitting areas (325); that the correlated register marks (332) are generally chevron-shaped; and that preferably said areas (325) and said register marks (332) extend at substantially 45° to the longitudinal direction of travel of the web (30).

Claim 8

Dependent Claim 21 words

Apparatus according to claim 4, characterised in that the detecting means (45) is responsive to substantially complete extinction of reflected light.

Claim 9

Dependent Claim 142 words

Apparatus according to claim 1, characterised in that a mask (24) is interposed between either the illuminating means (20, 22, 26, 27) and the web (30) or between the web (30) and the detecting means (45), said mask (24) being provided with a pattern of at least one light-transmitting area (25, 125, 225, 325, 425) and non-transmitting area(s), the said pattern being correlated with the said register marks (32, 34) so as to produce a well-defined transition in the magnitude of the said output (70, 71, 72) either when the image of said at least one light-transmitting area (25, 125, 225, 325, 425) falls on a said register mark (32) (or a part thereof) or when the image of a said register mark (32) (or a part thereof) falls on said at least one light-transmitting area (25, 125, 225, 325, 425), respectively.

Claim 10

Dependent Claim 53 words

Apparatus according to claim 1 or 6, characterised in that said detecting means is a photodetector (45) effective to produce at least one electric output pulse (70) for each passage of a register mark (32) and said analysing means includes electronic means (12) effective to find the exact centre (73) of said pulses.

Claim 11

Dependent Claim 38 words

Apparatus according to claim 7, characterised in that the electronic means is a microprocessor or a computer programmed to fit the actual waveforms producted to the corresponding theoretical shapes for the particular mask and registration mark shapes used.

Claim 12

Dependent Claim 65 words

Apparatus according to claim 6 or any claim appendant thereto, characterised in that the mask (24) has a square light-transmitting area (25) and the web register marks (32) are generally chevron or V-shaped, and further characterised in that the included angle between adjacent sides of the square as well as the included angle between the limb of the chevron or V is preferably substantially 90°.

Claim 13

Dependent Claim 76 words

Apparatus according to claim 9, characterised in that the width of each limb of the register mark (32) in the direction of travel of the web (30) equals the apex-to-apex distance of the square-shaped light-transmitting area (25); and in that, optionally, the width of each limb * of the register mark (32), taken in the direction transverse to the direction of travel of the web (30), equals the apex-to-apex distance of the square-shaped light-transmitting area (25).

Claim 14

Dependent Claim 70 words

Apparatus according to any of claims 6 to 10, characterised in that the register marks include an extra mark (34) shaped differently from the remaining register marks (32) and serving both to locate the remaining register marks (32) and to enable a calculation of web travel speed to be made, and further characterised in that the said extra mark (34) is preferably a solid mark of rhomboidal or parallelogram shape.

Claim 15

Dependent Claim 54 words

Apparatus according to claim 6 or claim 7 or 8 when appendant to claim 6, characterised in that the mask (24) has a circular light-transmitting area (125, 225, 425), preferably in the form of an aperture in the mask (24) and the web register marks are also circular (132, 432) or are triangular (232).

Web registration measurement system

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