Color ink sheet for thermal transfer

Claim 2

A color ink sheet for thermal transfer comprising thermal transfer ink layers containing at least three colorants, i.e. yellow magenta and cyan colorants provided on a base substance, characterized in that when the reflection density of the colorants is 1.3 after the transfer onto a recording paper, a spectral reflectance y (%) of the yellow colorant lies in between two diagrams represented by the following formulae (1) and (2), a spectral reflectance y (%) of the magenta colorant lies in between two diagrams represented by the following formulae (3) and (4) and a spectral reflectance y (%) of the cyan colorant lies in between two diagrams represented by the following formulae (5) and (6): wherein x represents a light wavelength (nm).

Claim 3

A color ink sheet for thermal transfer according to claim 1, wherein said yellow colorant comprises said magenta colorant comprises and, said cyan colorant is one selected from the following chemical formula

Claim 4

A color ink sheet for thermal transfer comprising thermal transfer ink layers containing at least three colorants, i.e. yellow, magenta and cyan colorants provided on a base substance, characterized in that when the reflection density of the colorants is 1.3 after the transfer onto a recording paper; as for yellow, a gradient of a spectral reflectance against a light wavelength (nm) in a range of 400 to 500 nm is higher than 1.00 (%/nm); as for magenta, a peak value of a spectral reflectance within a light wavelength range of 400 to 450 nm is at a light wavelength of longer than 415 nm; and as for cyan, a peak value of a spectral reflectance at a light wavelength within 400 to 500 nm is at least 60 %.

Claim 5

A color ink sheet for thermal transfer comprising thermal transfer ink layers containing at least three colorants, i.e. yellow, magenta and cyan colorants provided on a base substance, characterized in that when the reflection density of the colorants is 1.3 after the transfer onto a recording paper; as for yellow, a gradient of a spectral reflectance against a light wavelength (nm) in a range of 400 to 500 nm is higher than 1.00 (%/nm); as for magenta, a peak value of a spectral reflectance within a light wavelength range of 400 to 450 nm is at a light wavelength of longer than 415 nm; and as for cyan, a peak value of a spectral reflectance at a light wavelength within 400 to 500 nm is at least 60 %.

Claim 6

A cartridge comprising; a color ink sheet (15) for thermal transfer having a thermally transferred ink layer, said ink layer being disposed on a base film and binding at least three colorants, i.e. yellow, magenta and cyan with a binder; a pair of bobbins (12a , 12b) connecting respectively one side of said ink sheet (15) and winding said ink sheet (15); a pair of cylindrical protions (13a, 13b) holding rotatively said ink sheet (15) at a predetermined interval; and an ink sheet contacting window (14) for transferring said ink layer onto a recording paper by contact and heat a thermal head with said ink sheet (15); characterized in that when the reflection density of the colorants is 1.3 after the transfer onto the recording paper; as for yellow, a gradient of a spectral reflectance against a light wavelength (nm) in a range of 400 to 530 nm is higher than 1.2 (%/nm); as for magenta, a peak value of a spectral reflectance within a light wavelength range of 400 to 450 nm is at a light wavelength of longer than 420 nm; and as for cyan, a peak value of a spectral reflectance at a light wavelength within 400 to 500 nm is at least 70 %.

Claim 7

A cartridge comprising; a color ink sheet (15) for thermal transfer having a thermally transferred ink layer, said ink layer being disposed on a base film and binding at least three colorants, i.e. yellow, magenta and cyan with a binder; a pair of bobbins (12a , 12b) connecting respectively one side of said ink sheet (15) and winding said ink sheet (15); a pair of cylindrical protions (13a, 13b) holding rotatively said ink sheet (15) at a predetermined interval; and an ink sheet contacting window (14) for transferring said ink layer onto a recording paper by contact and heat a thermal head with said ink sheet (15); characterized in that when the reflection density of the colorants is 1.3 after the transfer onto the recording paper; as for yellow, a gradient of a spectral reflectance against a light wavelength (nm) in a range of 400 to 530 nm is higher than 1.2 (%/nm); as for magenta, a peak value of a spectral reflectance within a light wavelength range of 400 to 450 nm is at a light wavelength of longer than 420 nm; and as for cyan, a peak value of a spectral reflectance at a light wavelength within 400 to 500 nm is at least 70 %.

Claim 8

The invention of any of claims 1 to 4, wherein said colorants comprise subliming dyes.

Claim 9

The invention of any of claims 1 to 5, wherein said base substance comprises a film having 4-10 µm thickness such as a condenser paper or one selected from a high-molecular material of polyester, polyimide and cellulose; said ink layer comprises said colorant and a binder and has a 0.5-2 µm thickness; and an amount of said colorant is 1-70 % by weight.

Claim 10

The invention of claim 6, wherein said binder is one selected from a paraffin wax, a fatty acid ester, and one selected from a high-molecular material of polyester, polyamide, acylic resin and cellulose.