US Patent 7087265 Image developing device

The invention relates to a device for developing latent or hidden images. The device includes a first substrate containing a hidden or latent image printed on a first surface thereof, wherein the image contains one or more chromogenic compounds. A second substrate having a first surface contains a developer coating for developing the hidden or latent image. The developer coating includes a developer compound, a micro-encapsulated solvent, and an adhesive. Upon sufficient interfacial contact between the first surfaces of the first and second substrates, a visible image is produced. The device enables production of a relatively vibrant, full color images which are substantially non-toxic and relatively inexpensive to make.