Method and apparatus for exposing a latent watermark on film
First Claim
1. An apparatus for exposing a latent watermark along a length of photosensitive medium, the apparatus comprising:
- (a) an illumination source for providing an exposure illumination;
(b) a first spatial light modulator for modulating said exposure illumination to form a first exposure pattern according to first image data;
(c) a second spatial light modulator for modulating said exposure illumination to form a second exposure pattern according to second image data;
(d) combining optics providing a single output path for directing said first and second exposure patterns onto the photosensitive medium;
(e) a transport for providing, during exposure, lengthwise displacement of the photosensitive medium with respect to said single output path;
wherein said first and second spatial light modulators cyclically alternate in providing respective first and second exposure patterns to said combining optics, such that during a cycle wherein said first spatial light modulator forms said first exposure pattern, said second spatial light modulator loads the image data for providing said second exposure pattern; and
said first and second exposure patterns thereby forming, lengthwise along the photosensitive medium, said latent image comprising modulated stripes having a predetermined intensity corresponding to said first and second exposure patterns.
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Abstract
A printing method and apparatus (100) for pre-exposing a digital watermark along a length of photosensitive medium at the time of manufacture is disclosed. The printing apparatus has an illumination source (60) for providing an exposure illumination, first and second LCD spatial light modulators (90a, 90b) for modulating the exposure illumination to form first and second exposure patterns according to image data, combining optics providing a single output path for directing both first and second exposure patterns onto the photosensitive medium and transport means for providing, during exposure, lengthwise displacement of the photosensitive medium with respect to the output path. The first and second exposure patterns form, lengthwise along the photosensitive medium, a latent image with modulated stripes having a predetermined intensity corresponding to the exposure patterns.
44 Citations
39 Claims
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1. An apparatus for exposing a latent watermark along a length of photosensitive medium, the apparatus comprising:
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(a) an illumination source for providing an exposure illumination;
(b) a first spatial light modulator for modulating said exposure illumination to form a first exposure pattern according to first image data;
(c) a second spatial light modulator for modulating said exposure illumination to form a second exposure pattern according to second image data;
(d) combining optics providing a single output path for directing said first and second exposure patterns onto the photosensitive medium;
(e) a transport for providing, during exposure, lengthwise displacement of the photosensitive medium with respect to said single output path;
wherein said first and second spatial light modulators cyclically alternate in providing respective first and second exposure patterns to said combining optics, such that during a cycle wherein said first spatial light modulator forms said first exposure pattern, said second spatial light modulator loads the image data for providing said second exposure pattern; and
said first and second exposure patterns thereby forming, lengthwise along the photosensitive medium, said latent image comprising modulated stripes having a predetermined intensity corresponding to said first and second exposure patterns. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An apparatus for exposing a latent watermark as a series of lengthwise stripes along a length of photosensitive medium comprising:
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(a) an illumination source for providing an exposure illumination;
(b) a first spatial light modulator for modulating said exposure illumination to form a first exposure pattern according to image data;
(c) a second spatial light modulator for modulating said exposure illumination to form a second exposure pattern according to image data;
(d) combining optics providing a single output path for directing said first and second exposure patterns onto the photosensitive medium;
(e) transport means for providing, during exposure, lengthwise displacement of the photosensitive medium with respect to said single output path;
wherein said first and second spatial light modulators cyclically alternate in providing respective said first and second exposure patterns to said combining optics, such that during a cycle wherein said first spatial light modulator forms said first exposure pattern, said second spatial light modulator loads the image data for providing said second exposure pattern; and
said first and second exposure patterns thereby forming the latent watermark, wherein each of the lengthwise stripes has a predetermined intensity corresponding to said first and second exposure patterns.
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19. An apparatus for exposing a latent watermark as a series of lengthwise stripes along a length of photosensitive medium, the apparatus comprising:
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(a) an illumination source for providing an exposure illumination;
(b) a spatial light modulator for modulating said exposure illumination to form an exposure pattern according to image data;
(c) a lens for directing said exposure pattern toward the photosensitive medium;
(d) transport means for providing, during exposure, lengthwise displacement of the photosensitive medium with respect to said lens; and
said exposure pattern thereby forming the latent watermark, wherein each of the lengthwise stripes has a predetermined intensity corresponding to said exposure pattern. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A method for exposing a latent watermark along a length of photosensitive medium, the method comprising:
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(a) energizing an illumination source for providing an exposure illumination;
(b) forming a first exposure pattern according to image data by modulating said exposure illumination at a first spatial light modulator;
(c) forming a second exposure pattern according to image data by modulating said exposure illumination at a second spatial light modulator;
(d) directing said first and second exposure patterns onto the photosensitive medium over a single output path;
(e) providing, during exposure, lengthwise displacement of the photosensitive medium with respect to said single output path, exposing a set of lengthwise stripes thereby; and
wherein said first and second spatial light modulators cyclically alternate in forming respective first and second exposure patterns, such that during a cycle wherein said first spatial light modulator forms said first exposure pattern, said second spatial light modulator loads the image data for forming said second exposure pattern. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method for exposing a latent watermark along a length of photosensitive medium, the method comprising:
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(a) energizing an illumination source for providing an exposure illumination;
(b) forming an exposure pattern according to image data by modulating said exposure illumination at a spatial light modulator;
(c) directing said exposure pattern onto the photosensitive medium over an output path; and
(d) providing, during exposure, lengthwise displacement of the photosensitive medium with respect to said output path, exposing a set of lengthwise stripes thereby. - View Dependent Claims (39)
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Specification