A nondestructive and simple technique for determining the three-dimensional shape of fixed ink dots was developed, and the optimum conditions of laser excitation and filters to detect fluorescence were determined for both dye and pigment inks for ink jet. Most magenta and black dye inks emit fluorescence at around 580 and 667 nm through laser excitations at 543 and 633 nm, respectively. Yellow dye and pigment inks and a magenta pigment ink were also detected under this condition. The cyan dye ink was excited by 405 nm laser radiation, and the fluorescence was observed by bandpass filtering ranging from 510 to 650 nm discriminately from the paper with no fluorescent brightening agent. Cyan and black pigment inks did not emit detectable fluorescence. Fluorescence emitted from the ink jet inks by laser excitation successfully provided three-dimensional ink distributions with the optical slicing function of a confocal laser scanning microscope.
The surface topography and the corresponding microstructure of the print surface have a significant influence on the type and amount of the reflected light, whose distribution influences in turn the final appearance of the printed sample. Surface roughness of glossy coated paper with different amounts of UV coatings was tested by atomic force microscopy and scanning electron microscopy to correlate with the measured corresponding print gloss. To assess the surface topography, surface roughness characterization and fractal analysis were performed. For the overprint coating, three different screen stencils were used to regulate the coating amount applied onto the printed surface. The measurement showed that the amount of the applied coating influenced significantly the surface roughness parameters as well the measured instrumental print gloss.
Toner cloud beam is a novel toner-based printing method that employs a conductive toner. In this method, the toner beam is controlled by applying a pulsed voltage to a pair of aperture electrodes. It is important to determine the pulse control characteristics of the toner beam. Hence, this study experimentally investigates the dependence of dot formation on the electrode voltages and the relationship between the dot size and the pulse duration. An enlarged model with an aperture diameter of 0.5 mm is used to confirm that dots are formed directly on paper in less than 10-4 s. The toner motion is characterized by a toner velocity of ∼1-2 m/s and a toner motion relaxation time of ∼3×10-4 s.
Four different crystals are presented in the present article that are derived from a novel yellow pyrazolyl azo pigment used for ink jet inks. This compound exhibits a good pigmentary performance in light and heat stability but rather poor in solvent fastness. X-ray structure analysis has been carried out in order to improve the present drawback from the structural point of view. The authors have unexpectedly isolated two kinds of five-coordinate bisazo Na complexes of the cis form (space group: C2/c). The formation of the Na complex is found to be caused by NaNO2 used for the preparation of diazo components. Then, the authors tried to eliminate the sodium atom from the Na complex using hydrochloric acid in an attempt to develop a better pigment that assumes a trans configuration. The present Na-free compound in the trans form is found to crystallize in space group P-1 and is characterized by good solvent fastness in addition to the light and heat stability of the original title compound.
The authors have been interested in a sodium-containing bisazo complex of the cis form for application as a yellow ink jet ink pigment. It exhibits good performance with respect to light and heat stability but is rather poor with respect to solvent fastness. Accordingly, an attempt has been made in the present investigation to improve the solvent fastness by eliminating the sodium atom from the Na complex to give a structurally more stable bisazo compound of the trans form (i.e., the title compound). Treatment of the complex with hydrochloric acid removed the sodium atom and also transformed the product from the cis to the trans form, shown by the structural analysis as reported in the companion article. In this article, the authors report electronic characterization which was carried out computationally and experimentally. The absorption maximum in solution appears at about 450 nm and is composed of two electronic transitions with the following configuration interaction (CI) components: (i) HOMO-1→LUMO and HOMO→LUMO+1 and (ii) HOMO→LUMO+1, HOMO→LUMO+2 and HOMO-1→LUMO, where the HOMO, LUMO, and CI stand for the highest occupied or the lowest unoccupied molecular orbitals and the configuration interaction, respectively. The title compound possesses high solvent fastness in addition to the light and heat stability of the original compound.
Every type of color imaging device has its own color reproduction method, providing color characteristic information. Thus, a color management system with an ICC profile is generally used to reproduce colors between two different color imaging devices, for example, from a monitor to a printer. However, once the ICC profile of a device is measured and stored, it usually remains unchanged. Yet, a user can sometimes control the monitor configuration, such as the color temperature, contrast, and brightness, according to their preference, thereby changing the color characteristics of the monitor. In addition, typical end user's viewing condition is not matched to standard environment. In this case, if the user then prints an image on the monitor screen, the color of the printed image will not match the color displayed on the monitor screen, as the color characteristics of the ICC profile provided by the monitor manufacturer will no longer represent the user-configured color characteristics of the monitor. Therefore, this article proposes a method for user-configured monitor-to-printer color reproduction based on an estimation of the monitor characteristics under user's monitor configuration and viewing condition. First, the color characteristics according to change of monitor configuration is measured and modeled for the red-green-blue (RGB) chromaticity and tone curve. Second, to estimate the color characteristics of the user's monitor, color matching between a printed color chart and a reproduced color chart image on the monitor screen by soft proofing is accomplished. The RGB chromaticity and tone curve models are used in a soft proofing process for adjusting the monitor's color characteristics. After color matching, color characteristics of the user's monitor are then obtained. Finally, the monitor to printer color reproduction is evaluated based on the color characteristics obtained for the monitor. Experimental results using the proposed method show that the printed images have almost the same colors as the images on the real user-configured monitor screen.
Recently, projectors have become among the most common display devices not only for presentations at offices and in classes, but also for entertainment at home and in the theater. The use of mobile projectors expands applications to meetings in the field and presentation anywhere. Accordingly, projection is not always guaranteed to occur on a white screen, thereby introducing the possibility of some color distortion. In this article a general color correction method using a still camera as a convenient measuring device is proposed in order to match the colors between projections on white and light colored screens. The color correction is implemented using the proposed matrix which converts the input color to the resulting color appropriate for the colored screen. The proposed color correction matrix is estimated by linear regression using input digital values measured on the white and colored screens, thereby producing the same color on both the white and light colored screens. In addition, the calibration image contains information for nine steps in each color channel, enabling accurate construction of the transform matrix. In experimental results, the proposed method gives better color correction for both the objective and subjective evaluations than does a representative previous method.