Dot matrix hologram for hiding a moire pattern

Details Dot matrix hologram for hiding a moire pattern Dot matrix hologram for hiding a moire pattern

1999-09-30

2001-11-13

Chang, Audrey (Department: 2872)

Optical: systems and elements

Holographic system or element

Authentication

C359S001000, C359S569000, C283S086000, C283S072000, C283S083000

Reexamination Certificate

active

06317226

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates a dot matrix hologram for hiding a moire pattern to which a pretended pattern is skillfully added so that the moire pattern can not be identified directly by eyes. Moreover, the appearance of such a dot matrix hologram can be beautified by the addition of a moire pattern. Furthermore, in the present invention, the technology of one-dimensional moire patterns is upgraded to the technology of two-dimensional moire patterns for increasing amount of hiding information and improving the hiding ability of moire patterns.
BACKGROUND OF THE INVENTION
The present invention relates to a moire pattern technology about a dot matrix hologram. For conventional holograms, because the position accuracy of conventional holograms are about 8 millimeters (a position resolution of 3600 dpi)and the dot resolution of a holographic pattern is larger than 60 micrometers (the resolution of basic dots of a pattern is 400 dpi) usually. When the moire pattern foreground areas and the moire pattern background areas are shifted a distance of 8 or 16 micrometers to hide a moire pattern, eyes can not directly see the moire pattern clearly without using a decoding film for the position shifting being much smaller than the size of the resolution. However, for dot matrix holograms, because the resolutions of dot matrix holograms (equal to the size of grating dots) are larger than 20 micrometers (the resolution of basic dots of a holographic pattern is 1300 dpi) usually and the position shifting between the moire pattern foreground areas and the moire pattern background areas are several times of the size of a grating dot, eyes may clearly see the moire pattern without using any decoding film for this purely position shifting case. Thus, the hiding function of the moire pattern is lost. However, the moire patterns of the present invention can overcome the aforesaid phenomenon by a well designed pretended pattern. Moreover, the appearance of such a dot matrix hologram can be beautified simultaneously. Furthermore, in the present invention, the technology of one-dimensional moire patterns is upgraded to a technology of two-dimensional moire patterns.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing.


REFERENCES:
patent: 5396559 (1995-03-01), McGrew
patent: 5999280 (1999-12-01), Huang

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