Security device for security documents such as bank notes and credit cards

A security device comprising an optical device exhibiting an optically variable image, the optically variable device further including a two dimensional array of substantially identical microimages, each of the microimages having a dimension of up to about 250 .mu.m and which, when viewed through a two dimensional array of substantially spherical microlenses having substantially a same pitch as the array of microimages, each microlens having a diameter in the range of substantially 50-250 .mu.m, generate at least one magnified version of one of the microimages when the array of microimages and the array of microlenses are at least partially registered.

A method of preparing a record medium for use in producing a security device, the method comprising imaging an object or image onto the record medium through a regular two dimensional array of substantially spherical microlenses, each of the microlens having a diameter in the range of substantially 50-250 .mu.m, so as to record a two dimensional array of substantially identical microimages, each of the microimages having a dimension of up to about 250 .mu.m and having substantially a same pitch as a pitch of the array of microlenses.

A method of manufacturing a security device, the method comprising:

• printing a regular two dimensional array of substantially identical microimages on a record medium, each of the microimages having a dimension up to about 250 .mu.m;
• and
• securing over the array of microimages, a two dimensional array of substantially spherical microlenses having substantially a same pitch as the array of microimages, each of the microlens having a diameter in the range of substantially 50-250 .mu.m, such that on viewing, at least one magnified version of one of the microimages is visible when the array of microimages and the array of microlenses are at least partially registered.

A security document carrying a security device, the security device comprising a regular two dimensional array of substantially identical printed microimages, each of the microimages having a dimension of up to about 250 .mu.m and which, When viewed through a two dimensional array of substantially spherical microlenses having substantially a same pitch as the array of microimages, each microlens having a diameter in the range of substantially 50-250 .mu.m, generate at least one magnified version of one of the microimages when the array of microimages and the array of microlenses are at least martially registered.

A security document carrying a security device, the security device comprising an optically variable device exhibiting an optically variable image, the optically variable device further including a two dimensional array of substantially identical microimages, each of the microimages having a dimension of up to about 250 .mu.m and which, when viewed through a two dimensional array of substantially spherical microlenses having substantially a same pitch as the array of microimages, each microlens having a diameter in the range of substantially 50-250 .mu.m, generate at least one magnified version of one of the microimages when the array of microimages and the array of microlenses are at least partially registered.

A security document carrying a security device, the security device comprising a record medium, the record medium being prepared by a method comprising imaging an object or image onto the record medium through a regular two dimensional array of substantially spherical microlenses, each of the microlens having a diameter in the range of substantially 50-250 .mu.m, so as to record a two dimensional array of substantially identical microimages, each of the microimages having a dimension of up to about 250 .mu.m and having substantially a same pitch as a pitch of the array of microlenses.

A security document carrying a security device, the security device being manufactured by a method comprising:

• printing a regular two dimensional array of substantially identical microimages on a record medium, each of the microimages having a dimension up to about 230 .mu.m;
• and
• securing over the array of microimages, a two dimensional array of substantially spherical microlenses having substantially a same pitch as the array of microimages, each of the microlens having a diameter in the range of substantially 50-250 .mu.m, such that on viewing, at least one magnified version of one of the microimages is visible when the array of microimages and the array of microlenses are at least partially registered.

A method of authenticating a security device, the security device including a regular two dimensional array of substantially identical printed microimages, each of the microimages having a dimension of up to about 250 .mu.m, the method comprising:

• positioning a two dimensional array of substantially spherical microlenses having substantially a same pitch as a pitch of the array of microimages, each of the microlenses having a diameter in the range of substantially 50-250 .mu.m, over the security device;
• and
• viewing the security device through the array of microlenses.

A method of authenticating a security device, the wherein security device an optically variable device exhibiting an optically variable image, the optically variable device further including a two dimensional array of substantially identical microimages, each of the microimages having a dimension of up to about 250 .mu.m, the method comprising:

• positioning a two dimensional array of substantially spherical microlenses having substantially a same pitch as a pitch of the array of microimages, each of the microlenses having a diameter in the range of substantially 50-250 .mu.m, over the security device;
• and
• viewing the security device through the array of microlenses.

A security device reader comprising:

• a two dimensional array of substantially spherical microlenses, each of the microlenses having a diameter in the range substantially 50-250 .mu.m;
• and
• a security document holder for locating a security document having a security device, the security device comprising a regular two dimensional array of substantially identical printed microimages, each of the microimages having a dimension of up to about 250 .mu.m and which, when viewed through the two dimensional array of substantially spherical microlenses having substantially a same pitch as the array of microimages, generate at least one magnified version of one of the microimages when the array of microimages and the array of microlenses are at least partially registered.