Forgery prevention sheet

A forgery prevention sheet comprising a multi-layer sheet having at least two layers, wherein a bottom of the uppermost layer or a top of the lowermost layer is printed with a fluorescent ink to provide a predetermined print pattern, said fluorescent ink emitting a visible coloring ray when irradiated with an ultraviolet ray, a cross-sectional area from an upper surface of said sheet to said print pattern having opacity of 97% or more, another cross-sectional area from a lower surface of said sheet to said print pattern having opacity of 96% or less, said print pattern being not visible when irradiated with ultraviolet ray from the top but visible when irradiated from the bottom.

A forgery prevention sheet comprising a multi-layered sheet having at least two layers, wherein there are first and second print patterns at different positions in thickness of the sheet, said first print pattern being formed with a first ink including a first fluorescer and said second print pattern which is different from said first print pattern being formed with a second ink including a second fluorescer, a first cross-sectional area from an upper surface of the sheet to said first print pattern having opacity of 92% or less, a second cross-sectional area from the upper surface of the sheet to said second print pattern having opacity of 97% or more, a third cross-sectional area from a lower surface of the sheet to said second print pattern having opacity of 96% or less, whereby said first fluorescer of said first print pattern being solely visible from the upper surface of the sheet when irradiated with an ultraviolet ray from the top, whereas at least said second fluorescer of said second print pattern being visible from the upper surface of the sheet when irradiated with said ultraviolet ray from the bottom.

A forgery prevention sheet comprising a multi-layered sheet having at least an upper layer and a lower layer, wherein a first fluorescer is internally added in said upper layer and a print pattern is formed with an ink including a second fluorescer below said upper layer, a first cross-sectional area from an upper surface of the sheet to the top of said upper layer having opacity of 82% or less, a second cross-sectional area from the upper surface of the sheet to said print pattern having opacity of 97% or more, a third cross-sectional area from a lower surface of the sheet to said print pattern having opacity of 96% or less, whereby said first fluorescer in said upper layer being solely visible from the upper surface of the sheet when irradiated with an ultraviolet ray from the top, whereas at least said second fluorescer of said print pattern being visible from the upper surface of the sheet when irradiated with said ultraviolet ray from the bottom.

A forgery prevention sheet comprising a multi-layered sheet having at least an upper layer and a lower layer, wherein a print pattern is formed with an ink including a first fluorescer above said lower layer and a second fluorescer is internally added in said lower layer, a first cross-sectional area from the upper surface of the sheet to said print pattern having opacity of 92% or less, a second cross-sectional area from the upper surface of the sheet to the top of said lower layer having opacity of 89% or more, a third cross-sectional area from the lower surface of the sheet to the bottom of said lower layer having opacity of 75% or less, whereby said first fluorescer of said print pattern being solely visible from the upper surface of the sheet when irradiated with an ultraviolet ray from the top, whereas at least said second fluorescer in said lower layer being visible from the upper surface of the sheet when irradiated with said ultraviolet ray from the bottom.

A forgery prevention sheet comprising a multi-layered sheet having at least an upper layer and a lower layer, wherein a first fluorescer is internally added in said upper layer and a second fluorescer is internally added in said lower layer, a first cross-sectional area from the upper surface of the sheet to the bottom of said upper layer having opacity of 82% or less, a second cross-sectional area from the upper surface of the sheet to the top of said lower layer having opacity of 89% or more, a third cross-sectional area from the lower surface of the sheet to the bottom of said lower layer having opacity of 75% or less, whereby said first fluorescer in said upper layer being solely visible from the upper surface of the sheet when irradiated with an ultraviolet ray from the top, whereas at least said second fluorescer in said lower layer being visible from the upper surface of the sheet when irradiated with said ultraviolet ray from the bottom.