US 12,456,394 B2
Tamper-evident device with optically transparent layer and related method
Navin Suyal, Yorkshire (GB)
Assigned to OPTRICAL LIMITED, Yorkshire (GB)
Appl. No. 17/055,668
Filed by OPTRICAL LIMITED, Yorkshire (GB)
PCT Filed May 16, 2019, PCT No. PCT/GB2019/051343
§ 371(c)(1), (2) Date Nov. 16, 2020,
PCT Pub. No. WO2019/220120, PCT Pub. Date Nov. 21, 2019.
Claims priority of application No. 1807979 (GB), filed on May 16, 2018.
Prior Publication US 2021/0241658 A1, Aug. 5, 2021
Int. Cl. G09F 3/00 (2006.01); G09F 3/03 (2006.01); B42D 25/45 (2014.01); B42D 25/47 (2014.01); G02B 3/00 (2006.01); G02B 7/02 (2021.01); G09F 3/02 (2006.01); G09F 3/10 (2006.01)
CPC G09F 3/0292 (2013.01) [G09F 3/0376 (2013.01); B42D 25/45 (2014.10); B42D 25/47 (2014.10); G02B 3/0037 (2013.01); G02B 7/025 (2013.01); G09F 2003/0257 (2013.01); G09F 2003/0277 (2013.01); G09F 3/10 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A tamper-evident security device comprising:
an optically transparent layer including an array of separate optical focusing elements;
an array of separate image elements collectively defining an image viewable through the optically transparent layer when each of the optical focusing elements is positioned to reveal therethrough a view of one or more of said image element(s); and
an optically transparent adhesive layer between the optically transparent layer and the array of separate image elements, in which the optically transparent adhesive layer retains the optical focusing elements so positioned with respect to the image elements thereby in cooperation to reveal the image, a predetermined sub-portion of the optically transparent adhesive layer or the optically transparent layer arranged to undergo a visible color change relative to a remainder of the optically transparent adhesive layer or the optically transparent layer when exposed to air as a result of separating the layers of the device, wherein the predetermined sub-portion is non-detectable before separation, and
wherein the optically transparent layer is mechanically separable from the array of separate image elements by release of the optically transparent adhesive layer to cease said cooperation.