We developed a novel coupler, hydroxyperinone, 2- and/or 5-hydroxy-7H-benz[de]benzimidazo[2,1-a]isoquinoline-7-one and synthesized a bisazo pigment from the novel coupler. The OPC using this bisaszo pigments showed better characteristics in sensitivity and cyclic stability than the OPC using bisazo pigments derived from Naphthol AS. ¹³C NMR spectra of these bisazo pigments indicated that the dominant tautomer of the new bisazo pigment in the solid state was different from those of other bisazo pigments. The difference in tautomers reflects their characteristics. We designed and synthesized a unique highly sensitive unsymmetrical bisazo pigment having a large dipole moment in the excited state, on the basis of the photocarrier generation process model. Thermally stimulated current measurements were applied to elucidate factors for high sensitivity.

“Future Directions of Non-Impact Printing Technologies” was the title of a panel discussion during the “First International Congress on Advances in Non-Impact Printing Technologies” in 1981. The 1981 status of non-impact printing establishes the context for the panelists' predictions. Evolution of the non-impact printing technologies and their applications from 1981 to 2001 are then compared with the panelists' predictions. Despite the fact that these predictions were not intended to cover a 20 year period, many were surprisingly accurate. Only a few differed from reality dramatically. The last section is entitled “Where To From Here?” The first part covers expansion of the present application range plus possible future applications. The second deals with a) technical advances in each non-impact printing technology that could improve performance and cost effectiveness and b) new non-impact processes under development or on the horizon plus basic science and technology areas that could have a significant impact on non-impact printing in the future.

Jobs to be printed may have colors that are specified in many different color spaces. A printing system must convert those colors to the device CMYK of the printer. In complex printing environments, color conversions occur at many places throughout the system. In an Advanced Function Presentation (AFP) printing environment, data is processed on application development tools, in the print server, and in the printer itself. Further, there are different types of data formats, such as PostScript format and AFP Mixed Object Document Content Architecture (MO:DCA-P) format, which require color conversions by different processes. It is particularly important to produce consistent colors across all data paths for both device-dependent and device-independent colors. The system designers must decide which input color spaces to support. For instance, support may be needed for some device-dependent color spaces such as CMYK SWOP, CMYK Euroscale, and SMPTE-C RGB that have become industry “standards”. There may be requirements to support a toner-saving mode. This article will describe some of the work that was done during the development of a high-end, full-color printing system. It will discuss methods used to make the color conversions more consistent and multiple methods that may be used to control color conversions.

Several model ink jet coatings having a broad range of hydrophilicity were imaged on three printers. The gloss of these images was independent of the hydrophilicity of the ink jet coating. However, when the most hydrophobic and hydrophilic systems were coated on top of each other the gloss of printed image areas was dependent on the hydrophobicity of top layer. In experiments having a hydrophilic layer on the top, the gloss of imaged areas was independent of ink load and the ratio between both ink jet coating layers. When a hydrophobic layer was coated on the top hydrophilic layer, drop of 60 points in gloss was observed at a 400% ink load. The gloss reduction can be dependent on a ratio between both ink jet coating layers and ink load. Correlations were found between water absorption, gloss reduction and content of the most hydrophobic component in the coatings. It was shown that the difference in the degree of absorption between the two ink jet coating layers has an effect on the gloss of printed areas.

Charge control agents (CCA's) are frequently added to toners to create a desired charge level and polarity. Triboelectric charging tests on model, CCA-surface-treated toners and carriers indicate that CCA transfer between toner particles and carrier beads can be a controlling factor for the magnitude and polarity of toner charge — in extreme cases, toner polarity can even be reversed as a result of CCA transfer. The tests also indicate that the transfer process, and hence the final charging properties of a toner can be significantly affected by the concentration of the toner in a xerographic developer.

A new measurement method is proposed to separately measure the effect of ink spread and optical dot gain on the MTF (modulation transfer function) of printed images from an ink jet printer. The transmittance and reflectance of the same printed images are captured with two different illuminations: one on the printing surface (for measuring reflectance) and the other through the paper base surface (for measuring transmittance). The MTF of ink image and MTF of print are measured from one-pixel line printed on glossy, matte and uncoated paper. The result shows that the paper type significantly affects the MTF of ink image and the MTF of print. The MTF of paper is also measured by this method and it is shown that optical dot gain considerably affects the MTF of print.

We propose a system to reduce electrophotographic laser printer banding artifacts due to optical photoconductor (OPC) drum velocity fluctuations. The drum velocity fluctuations are sensed with an optical encoder mounted on the drum axis. Based on the line-to-line differential encoder count, we modulate the laser pulse width to compensate fluctuations in development that would otherwise occur. We present an analysis of the system, including the compensation algorithm that determines the desired pulse-width as a function of differential encoder count. Characterization of the system is based on printing, scanning, and processing a special test page that yields information about line-spacing and absorptance fluctuations. This data is synchronized with the encoder count signal that was recorded during the printing of the test page. Finally, we present experimental results for an HP LaserJet 4M printer that demonstrate the effectiveness of the system in reducing banding due to OPC drum velocity fluctuations.

The authors are engaged in developing a novel image acquisition system called Elgraphy, which is a combination of electrophotography and liquid crystal technology. One desirable property that the photosensor used for Elgraphy (Elgraphic photosensor) should have is sensitivity over a wide range of the visible spectrum in order to accurately capture color images. The authors found that, in the Elgraphic photosensor, which exhibits photocurrent amplification, the addition of a special charge transport material (CTM) to the charge transport layer (CTL) has the effect of enhancing the sensitivity in the blue light region. This effect is attributable to the following mechanism: Blue light that has passed through the charge generation layer (CGL) is absorbed by the CTM, where it excites the CTM to fluoresce in the absorption band of the CGL. The CGL absorbs the fluorescence, which induces the generation of photocarriers inside the CGL, thus giving rise to photocurrent amplification similar to the photoconduction mechanism that occurs in the green and red light regions.