A forgery prevention medium includes a substrate and a specific invisible material layer directly or indirectly laminated on the substrate, having a specific invisible material reversibly and visually recognized through a predetermined process disposed thereon in a plane shape, and having a part of the specific invisible material inactivated in accordance with a visualized image pattern.

Color change compositions that transition from a first to second color state upon application of an applied stimulus are provided. Also provided are substrates having the compositions on a surface thereof, as well as methods of making and using the compositions.

Formation of a multi-colored image in thermochromic material involves controlling operation of first, second, and third heat sources. The first heat source heats pixels of the thermochromic material to activate the pixels. The second and third heat sources are selectively controlled to heat different sets of pixels using neither, one, or both of the second and third heat sources.

Formation of a multi-colored image in thermochromic material involves controlling operation of first, second, and third heat sources. The first heat source heats pixels of the thermochromic material to activate the pixels. The second and third heat sources are selectively controlled to heat different sets of pixels using neither, one, or both of the second and third heat sources.

A laser device according to one embodiment of the present disclosure includes a light source and a reflection-type polarizer. The light source causes laser light to oscillate. The reflection-type polarizer is disposed on an optical path of the laser light and has a transmission axis coinciding with a polarization direction of the laser light.

An imaging system includes first and second heaters configured to pre-heat a thermochromic coating. The first heater heats at least one of a substrate and the thermochromic coating disposed on the substrate. The second heater heats an ambient environment surrounding the thermochromic coating. The first and second heaters are configured to pre-heat the thermochromic coating to a temperature below a threshold temperature of the thermochromic coating. The system further includes a patterned heater configured to heat the pre-heated thermochromic coating to one or more temperatures above the threshold temperature according to a predetermined pattern.

Formation of a multi-colored image in thermochromic material involves controlling operation of first, second, and third heat sources. The first heat source heats pixels of the thermochromic material to activate the pixels. The second and third heat sources are selectively controlled to heat different sets of pixels using neither, one, or both of the second and third heat sources.

A thermochromic display board is described that includes an array of nanofiber yarns in contact with an electrode. When electrified, the nanofiber yarns generate heat. This heat causes a thermochromic transition in a thermochromic layer. The presence of the nanofiber yarns, which are thermally conductive, can increase the rate at which the thermochromic layer within the di splay board transitions between thermochromic states.

An approach for forming a multi-colored image on a substrate that includes a thermochromic material capable of producing at least two different colors is disclosed. Individually selected pixels of the thermochromic material that correspond to the image are heated to predetermined temperatures. Each predetermined temperature corresponds to a predetermined color shift of the thermochromic material. While the individually selected pixels are being heated, an area that includes the individually selected pixels is flooded with an amount of UV radiation sufficient to at least partially polymerize the thermochromic material. A color of each individually selected pixel is determined by a predetermined temperature to which the pixel is heated and the amount of UV radiation to which the pixel is exposed.

A method of forming a multi-colored image on a substrate that includes a thermochromic material capable of producing at least two different colors is disclosed. The method includes heating individually selected pixels of the thermochromic material that correspond to the image to one or more first temperatures sufficient to activate the selected pixels of the thermochromic material for color shift. The area corresponding to the individually selected pixels is flooded with a first UV radiation dosage sufficient to at least partially polymerize the thermochromic material. The individually selected pixels are heated to one or more second temperatures while the area is flooded with a second UV radiation dosage.