DMD and laser exposure modules are compared with respect to the formation of a single pixel on the photoconductor. Toner development is assumed to neutralize the normal component of the electric field above the photoconductor at the location of the toner about to be developed. This field is produced by bias voltages, the single pixel latent image, and toner already developed. Care is taken in predicting development of the second layer of toner to assume that the latent image is on the surface of the photoconductor and the first layer of toner is above the surface of the photoconductor. The predicted toner development is in accord with the experimental data. The analysis shows that the normal component of the electric field for single pixel development produced by a 600 dpi DMD exposure module is stronger than the corresponding field of an 85 μm wide Gaussian pixel produced by a laser exposure module. Therefore, toner development resulting from the DMD exposure module is more stable, smaller, and more compact on the photoconductor than the toner developed image produced by the corresponding laser exposure module. Comparing theory with experimental data where the exposure of the photoconductor by the DMD exposure module is varied, suggests that toner development only begins after a threshold electric field is reached. Justification for a threshold behavior is given.

Eastman Kodak Company has recently announced breatkthrough nanoparticulate ink technology which represents an improvement in both dye-based and pigment-based inks. These ultrafine pigmented inks exhibit average particle size approximately one order of magnitude smaller than other commercially available pigmented ink jet inks. In this article, we will discuss the effects of colorant particle size on reliability, image quality, and durability in an ink jet printing system. Comparisons will also be made to conventional dye-based inks.

In the ink jet printer industry the stroboscopic visualization method is a standard tool for the charactarization of printheads. However, this method fails for thermal ink jets owing to the existence of satellite droplets which are very critical with respect to print quality. This is also true for the bubble formation inside the ink chamber of the printhead. Detailed studies have shown that the phenomenon of satellite droplets is a nonreproducible dynamic process. Real high-speed cine photomicrography forms the basis of a new test setup that allows the visualization of such highly dynamic nonreproducible phenomena. This new setup has been used to study the ejection, the free flight, and the impact of droplets of an ink jet on print media under real printing conditions.

In thermal ink jet (TIJ) printhead design, in order to satisfy various market demands, it is important to consider how effectively the printhead transfers input energy to ejected drop performance. First, we defined energy efficiency as a ratio of ejected ink drop energy (the sum of kinetic and surface energy) to consuming electric energy in the heater of thermal ink jet printhead. We examined a method for increasing the energy efficiency in terms of printhead design, and we found that it relates with an inertance ratio of the rear fluid pass to the front. We proposed a new side shooter thermal ink jet printhead for improvement of the inertance ratio, and we tried to fabricate channels on silicon wafers by a reactive ion etching (RIE). The printhead achieved higher energy efficiency when compared with the conventional design and it has been proved that high energy efficiency enables low consuming energy or high drop energy, and other good characteristics have been also obtained by the printhead.

With its excellent color and tone reproduction, thermal dye transfer printing produces continuous-tone color images that rival silver halide photography. However, conventional thermal dye transfer images fade easily when subjected to light or heat. To solve this problem, we have studied a chelate compound system and have found that certain sets of azo dyes and transition metal cationproviding compounds produce dye-metal complexes, or “chelate compounds”, that provide exceptionally high image stability.

The color gamut in bi-level digital printers depends on the allocation of the CMY primary ink dots placed in dithering matrices. The typical color mixture model is based on Neugebauer theory, where CMY dots are placed at random, but recent digital printers don't obey that theory. The simplest method used in digital printers is “coaxial” allocation, where the CMY ink dots are placed in the same positions in each color dither matrix. The coaxial model produces sharp edges, but may generate too many secondary colors with unsaturated chromaticities. A mixture of C and M inks may produce a more brilliant bluish color when the C and M dots are placed side-by-side to avoid overlapping. In this article, “min-med”, “min-max” and “min” models with side-byside dot allocation are discussed. These are designed to suppress the occurrence of secondary colors. The corresponding color gamuts are analyzed and compared.

Previous work has shown that the mechanism of color and tone reproduction in halftone imaging systems can be described quantitatively by modeling functions for mean level probability, P_ij, for light scattering from region i to region j, where regions i and j may be, for example, regions of the printed paper covered by different inks in the halftone process. The value of P_ij has been shown to be a function of the area fractions of the regions, f_i and f_j. In the past, the P_ij functions were written empirically to fit observed data or determined by convolution calculations involving the paper point spread function, PSF, and the transmittance geometry of the halftone pattern, T(x,y). In the current work it is shown that characteristics of the P_ij functions can be deduced from symmetry properties of light scattering in paper and symmetry properties of the halftone pattern. This allows some P_ij functions to be derived directly without the need to carry out a convolution with the point spread function of the paper. Models of these symmetry properties and methods for experimental analysis are presented.

Previous work has shown that tone reproduction characteristics of halftone images can be modeled with knowledge of the probability function P₀₀, for light to reflect from the paper between the halftone dots after having entered the paper between thehalftone dots. In the current report, experimental measurements of the micro-reflectance, Rp, of the paper between the dots is measured as a function of dot area fraction, F, and used with the model to calculate experimental values for P₀₀ versus F. It is then shown that the model can be modified to account for inks that have significant scattering. The model is shown to fit data on halftones printed with electrophotography toner which is highly opaque. In addition, the model is further modified to account for the effects of the non-sharpness of the edges of halftone dots. Using both of these effects, the model is shown to fit well with measured data from a variety of AM and FM halftones printed at different resolutions with different colorants. In addition, the model is shown to fit experimental data on the tone reproduction characteristics of a ontinuous tone, electrophotographic, office copy machine.

This report experimentally relates the Yule–Nielsen n parameter for optical dot gain to the scattering and absorption parameters, S and K, of Kubelka–Munk theory. The relationship between the parameters is made through another metric of light scatter, k_p, defined as the inverse of the frequency, ω in cy/mm, at which the MTF of the paper equals 1/2. The value of n is related exponentially to k_p, as shown in earlier work, and the current work indicates that k_p = c/S, where c is a constant equal approximately to 10. However, contrary to some intuition and to previous theoretical projections, the absorption coefficient of the paper, K, has no significant influence on k_p or the MTF of paper.

Five kinds of gelatins were investigated, and varying amount of sodium thiosulfate was added to study the effect of Na₂S₂O₃ on photographic gelatin. The ubiquinone and RS· radicals were detected and the change of their concentrations in photographic gelatins were studied by electron spin resonance (ESR). The concentration of ubiquinone, which was dependent on the equilibrium among the hydroubiquinone, ubiquinone radical and ubiquinone compounds, increased to a maximum value and then decreased with the increasing amount of sodium thiosulfate. The study of the chemical state of iron in gelatin with varying amounts of sodium thiosulfate by x-ray photoelectron spectroscopy (XPS) showed that the state of iron in gelatin was not affected by adding sodium thiosulfate.