Ultrasonic bonding of security device to a substrate to prevent harvesting
A security document ( 200 ) includes a substrate ( 205 ) having a first surface and a second surface opposite to the first surface, the first surface having a cellulosic material. The security document further includes an optical security device ( 220 ) having optical indicia of authenticity of the security document and a third surface, the third surface having a thermoplastic polymer. The security document also includes an ultrasonic weld ( 225 ) forming a bond between a section of the first surface and a section of the third surface.
1. A security document, comprising:
a substrate comprising a first surface and a second surface opposite to the first surface, the first surface comprising a cellulosic material;
an optical security device comprising:
optical indicia of authenticity of the security document, and
a third surface, the third surface comprising a thermoplastic polymer; and
an ultrasonic weld forming a bond between a section of the first surface and a section of the third surface,
wherein a first portion of the optical security device is embedded in the substrate, forming a bridge region,
wherein a second portion of the optical security device is visibly disposed on the first surface, forming a window region, and
wherein the ultrasonic weld is disposed only in the bridge region.
2. The security document of claim 1 , wherein the ultrasonic weld contacts the second surface of the substrate.
3. The security document of claim 1 , wherein the optical indicia of authenticity is damaged in the bridge region and proximate to the ultrasonic weld.
4. The security document of claim 1 , wherein the optical security device is a micro-optic security device comprising a layer of focusing elements and a layer of image icon elements.
5. The security document of claim 1 , wherein the optical security device comprises:
an effect region, the effect region comprising a layer of focusing elements and a layer of image icon elements; and
a transition region,
wherein the ultrasonic weld is disposed in the transition region.
6. The security document of claim 1 , wherein the optical indicia of authenticity is not damaged in the window region by the ultrasonic weld.
7. A security document, comprising:
a substrate comprising a first surface and a second surface opposite to the first surface, the first surface comprising a cellulosic material;
an optical security device configured as a thin continuous strip, the thin continuous strip woven into the substrate to form a window region and a bridge region, the optical security device comprising:
a first layer including at least one micro-scale structure providing optical indicia of authenticity of the security document, and
a third surface comprising a thermoplastic polymer; and
an ultrasonic weld disposed only in the bridge region and forming a bond between a section of the cellulosic material of the first surface and a section of the thermoplastic polymer of the third surface.
8. The security document of claim 7 , wherein the third surface is:
a seal layer of the at least one micro-scale structure;
a layer of focusing elements;
an image icon layer; or
a substrate which the at least one micro-scale structure is disposed on.
9. The security document of claim 7 , wherein the ultrasonic weld deforms or separates a portion of the optical security device to render the optical security device unfit for re-use.