Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – To produce color reproduction
Utility Patent
1999-06-09
2001-01-02
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
To produce color reproduction
C106S420000, C106S499000
Utility Patent
active
06168892
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for forming reflection-type or transmission-type color images.
BACKGROUND OF THE INVENTION
The reflection-type or transmission type images refer to all characters and images having non-luminous object color other than light source color, including prints obtained using letterpress printing, intaglio printing or planographic printing, output by printers (e.g., an ink-jet printer, laser printer, sublimation-type thermal printer, thermal transfer printer, electrostatic printer, etc.), photographic materials, and photocopies. Hereinafter these are denoted as “hard copy”. Image qualities of hard copy depend on gradation, resolution, color reproduction, and sharpness; and its color affected by the color of the image supporting material such as paper or a transparent sheet, color of dyes and composition of inks or toners. To expand the color reproduction range or improve hue or color tone in color images of these hard copies, dyes with high color purity have been explored, that is, attempts to reduce unwanted absorption, have been made, based on chemical structure, but it was proved to be limited in terms of requirements such as light fastness and manufacturing cost. Cited as the use of a fluorescent substance to improve color images is a fluorescent brightening agent. In this case, when a colorless compound having no absorption within the visible light wavelength region is employed as a fluorescent dye, the emission wavelength region is limited only to a blue color, and it effectuate to minimize an unwanted absorption of the dye but it is directed to improvements in yellowish white background. Thus, this technique is not directed to color correction. Various attempts have been made with respect to aggregation of dyes, surfactants as a component of inks or toners and light transmission property of polymers. However, these techniques have not resulted in removal of unwanted absorption of dyes.
U.S. Pat. No. 4,774,181 discloses the use of a coupler capable of releasing a fluorescent compound, in which case the coupler was previously included in a photographic material and the fluorescent compound is formed after processing such as development. On the contrary, according to the present invention, a fluorescent material is imagewise sprayed or transferred onto the color image portions, which is distinctly different from the technique described above. Furthermore, the above-described fluorescent compound-releasing coupler was proved to be inferior in storage stability and commercially unacceptable.
It is also known in the art that a fluorescent substance is included in a hard copy for the purpose of antifalsification, in which case the fluorescent substance exhibits no emission in the visible region under conventional light such as natural light or fluorescent light, and emitting light only under irradiation of UV rays. There is also known an ink emitting fluorescence, causing the resulting images to appear to be excessively vibrant or visually impact on the images.
Along with advancements of digitization, color hue and color reproduction range of hard copy are sought to approach the quality of CRT.
The concept of employing the subtractive color process and additive color process in combination is applied to displays, in which case a fluorescent substance is covered with a filter to remove unwanted emissions, enhancing color purity. Thus, it serves to correct images formed by additive color mixing with subtractive color mixing. However there has not been known any concept of applying the additive color process to images formed through subtractive color mixing to perform imagewise color correction.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a method for forming color images with improved color hue and expanded color reproduction region.
The above object of the present invention is accomplished by the following constitution:
(1) a color image forming method comprising applying additive color mixing to a subtractive color mixture to perform color correction;
(2) the method described in (1) above, wherein a fluorescent substance is used for the additive color mixing;
(3) the method described in (2) above, wherein a fluorescent substance exhibiting emission in the visible light wavelength region is mixed with a compound having an absorption in the visible light wavelength region to form a mixture;
(4) the method described in (3) above, wherein the fluorescent substance is mixed in an amount that gives not less than −0.3 with respect to an absorbance of the mixture;
(5) the method described in (3) or (4) above, wherein the compound having an absorption in the visible region is a colorant;
(6) the method described in any of (3) to (5) above, wherein the fluorescent substance exhibits emission in the wavelength region of an unwanted absorption of the compound having an absorption in the visible region;
(7) the method described in any of (3) to (5) above, wherein the fluorescent substance is so mixed that an absorption in an unwanted absorption wavelength region is reduced to not more than 98% by area;
(8) the method described in any of (3) to (5) above, wherein the compound having an absorption in the visible region has a main absorption peak and an absorption peak in an unwanted wavelength region, and the fluorescent substance is so mixed that the absorption peak in an unwanted wavelength region is reduced to not more than 98% by height;
(9) the method described in any of (3) to (5) above, wherein the compound having an absorption in the visible region has a single absoption peak, including absorption in an unwanted wavelength region, and the fluorescent substance is so mixed that a half-width of the absorption of the compound is reduced to not more than 99.5%;
(10) the method described in any of (3) to (9) above, wherein the exciting light wavelength of the fluorescent substance is in the range of 350 to 420 nm;
(11) the method described in any of (2) to (10) above, wherein the fluorescent substance exhibits an emission having a peak at a wavelength of 400 to 500 nm;
(12) the method described in any of (2) to (10) above, wherein the fluorescent substance exhibits an emission having a peak at a wavelength of 500 to 600 nm;
(13) the method described in any of (2) to (10) above, wherein the fluorescent substance exhibits an emission having a peak at a wavelength of 600 to 700 nm;
(14) the method described in any of (2) to (13) above, wherein the fluorescent substance exhibits an emission having a Stokes shift of not less than 10 nm;
(15) the method described of (11) above, wherein the fluorescent substance exhibits an emission having a Stokes shift of 10 to 100 nm;
(16) the method described of (12) above, wherein the fluorescent substance exhibits an emission having a Stokes shift of 100 to 200 nm;
(17) the method described of (13) above, wherein the fluorescent substance exhibits an emission having a Stokes shift of 200 to 300 nm;
(18) the method described in any of (5) to (10) above, wherein the colorant is yellow, and the fluorescent substance is so mixed that an absorption in the wavelength region of not less than 500 nm is reduced to not more than 98%;
(19) the method described in any of (5) to (10) above, wherein the colorant is magenta, and the fluorescent substance is so mixed that an absorption in the wavelength region except for 500 to 600 nm is reduced to not more than 98%;
(20) the method described in any of (5) to (10) above, wherein the colorant exhibits cyan color, and the fluorescent substance is so mixed that an absorption in the wavelength region of not more than 600 nm is reduced to not more than 98%;
(21) the method described in any of (2) to (20) above, wherein the fluorescent substance is an inorganic phosphor;
(22) the method described in any of (2) to (21) above, wherein the fluorescent substance contains at least an oxygen atom;
(23) a color image forming method comprising forming plural picture elements on a support, wherein the picture elements each compris
Ishibashi Daisuke
Kita Hiroshi
Ohara Noriko
Okada Hisatake
Ushiku Masayuki
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Goodrow John
Konica Corporation
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