With the Phaser® 340 color printer, Tektronix commercialized a new high-speed color-printing process. The method and the engine architecture result from the combination of solid ink-jet printing with drum-based offset printing. The benefits of this printing technology are plain-paper printing in full color at multiple pageper- minute speeds and exceptional transparency quality. The basic elements of the engine include proprietary phase-change inks, a page-wide printhead, offset drum, and transfer roller. A review of the engine architecture and its relationship to printer performance is described. Additionally, the characteristics of the core technology components are summarized.

This paper details the development of an ink-jet phase-change ink for a drum-based offset printing process. The offset printing process is based on a page-wide printhead delivering molten ink droplets on demand to a heated intermediate drum surface. The ink is then fused and transferred (transfixed) to the final print medium. The transfixed ink must exhibit sufficient flexibility and durability such that it does not crack or flake off when the print is folded or creased. The ink was formulated to have specific fluidic properties for ink-jet printing. Compression testing was performed on an MTS SINTECH 2/D to tailor the ink formulation for desired compressive and yield stress properties. In addition, dynamic mechanical analyses were carried out to determine the dynamic moduli, glass transition temperature, and tan δ of the ink. The optimized ink represents a formulation customized for high-temperature jetting and an offset printing process.

A method has been developed for dynamically modulating the drop volume created by an array piezoelectric drop-on-demand ink-jet printhead. A 4:1 range of volume modulation has been achieved, resulting in approximately a 4:1 range in printed spot area. The modulation is continuous (i.e., not discrete) over a significant part of the total range, and it is achieved with a minimal decrease in throughput. Optical densities for modulated spots have been measured at 300 and 600 dpi for several printhead configurations. Algorithms have been designed to use a combination of continuous modulation and halftoning (using modulated drops) to produce photorealistic images.

The fluid flow in thermal ink-jet transducers is highly dynamic in the sense that at no time during its operation does the flow reach a steady-state condition. The transient flow is affected by the inertial and viscous effects. These two effects are reflected through the inertance and resistance parameters of the transducer geometry. In this study we present a general background on the inertance and resistance parameters, present a method for calculating these parameters for a given three-dimensional geometry, and briefly outline their role in the ink drop ejection process.

In thermal ink jets a complete understanding of the physical processes in ink-jet firing chambers still requires research. The experimental investigation of these high-speed dynamic processes is difficult due to the extremely short durations of the different phenomena in the ink chamber. For example, the bubble lifetime is approximately 15 μs. A new experimental setup is presented to record phenomena of very short durations, like bubble nucleation, bubble growth, bubble collapse, and the beginning of droplet ejection. This setup allows realcinematographic visualization of such processes with a spatial resolution of less than 1 μm and a time resolution of 10 ns. The apparatus also offers the possibility of studying transient processes such as droplet ejection at high printing frequencies. The essential part of the setup is a new highspeed camera. With an exact evaluation of the digitized images the locus, velocity, and acceleration distributions of the phase interface from liquid to vapor/air can be measured. In addition to experimental work simulation results of a dynamic numerical model with realistic geometric data of the firing chamber and the nozzle of a commercially available printhead are presented. A comparison of experiment and simulation leads to conclusions for pressure propagation in the vapor bubble.

This paper presents data showing the relationship of the jet velocity V_J, the wave velocity V_w = λf, and the droplet velocity V_d of a continuous, stimulated jet emanating from an orifice in a thin, flat plate. The jet velocity measurement is nontrivially derived from the flow rate, as the jet diameter D is a function of V_J due to the presence of a dynamical meniscus at the orifice-jet boundary; λ is the measured wavelength of the surface deformation imposed on the jet at a frequency, f. The droplet velocity is measured in a straightforward fashion. We find good agreement between the measured values for λf and those calculated from the simple velocity potential theory for cylindrical jets for λ/D < π. However, the same theory predicts λf = V_J and V_J > V_d for λ/D > π, which we do not find to be strictly true. A possible factor for this discrepancy is that the surface deformation along the length of the stimulated jet is monotonically increasing in amplitude, culminating in droplet formation and break-off. This finding strongly violates the assumption of a uniform and infinitesimal deformation in the simple theory.

In laser dye transfer printing, the small laser spot provides high resolution, but the printing speed is relatively low compared to that of thermal head printing, in which a large number of dots can be recorded simultaneously. To shorten the printing time, a compact high-power Nd:YAG laser is used for the light source in our printing system. We have developed a practical laser dye transfer printing system with a newly developed Nd:YAG laser and compact optical head. Printing characteristics with a short pulse, of the order of 1 ms, are evaluated in this printing system. As a result, continuous-tone printing with a pulse of 2 μs is feasible when laser power is 1.0 W, indicating a significant advance in printing speeds. The transfer efficiency as a function of pulse width has a peak that can be observed. A thick ink layer produces aximum optical density, although a reduction in efficiency results from increasing the layer thickness. Good halftone printing is also performed using this system.

An electron microscope study of the morphology of the silver particles forming in the image area from the photothermographic process shows that the shape and size of the silver crystals change depending on the method of preparation of the silver halide/silver fatty acid complex system. In the case of the in situ process, silver halide obtained by treating silver stearate with solutions of brominating agents (LiBr, ZnBr₂, or HgBr₂) during the photothermographic process yields silver filaments. In the case where the silver halide is preformed and then added during the preparation of the silver carboxylate, dendritic silver particles result during the photothermographic process.