Thin Ink Research Articles

A Study on Cleaning Ability of Oscillating Bubbles Driven by Low-Frequency Ultrasound

In this paper, we demonstrate the cleaning ability of oscillating bubbles, on the basis of optical observations of bubble behaviors and cleaning process using a high-speed video camera. It was shown that a bubble cluster was formed after the collapse of the initial bubble. The bubble cluster consisted of a main bubble and many small bubbles. In addition, optical observations clearly revealed that the oscillations of these microbubbles removed a thin ink film bonded to the surface of a slide glass. From the analysis of the relationship between bubble oscillation and cleaning effect, it was confirmed that the cleaned area increased with an increasing amplitude of bubble oscillation, although there was a poor correlation between cleaned area and bubble oscillation. Moreover, the observed results suggested that a pressure ranging from several tens kPa to MPa was generated on the slide glass by hydrodynamic phenomena; micro jet and secondary wave were emitted by the oscillating bubble. Our experimental results lead to the understanding of the cleaning mechanism in ultrasonic cleaning techniques.

Interaction and Fragmentation of Pulsed Laser Induced Microbubbles in a Narrow Gap

We investigate the interaction dynamics of an existing stable microbubble B1 and another laser induced nearby expanding microbubble B2 in a thin ink sheet between two glass slices. The fast expanding B2 causes anistropic compression of B1 with a forward penetrating jet. In the subsequent expansion stage of B1, the gas associated with jet protrusion to the opposite edge of B1 and the nonuniform surrounding flow field induce necking with transverse inward jetting from the side lobes, which further interact with the axial jet and lead to the final fragmentation into smaller bubbles. At small interbubble distance, the backward interaction from B1 first leads to the pointed pole of the expanding B2 and then a backward jetting during its collapsing. The strong interaction can merge the two bubbles with complicated asymmetric intermediated patterns.

The Fundamentals of HP Indigo's Digital Offset Color Printing Process and How It Rivals Mechanical Offset Printing

In recent print shows, the Indigo Division of HP has introduced new presses based on the new BID development system, the fastest digital color printing products in the industry and with photographic quality capabilities for the high end photo market. “Digital Offset Color” is a process combining HP's unique electrically-responsive ink, “ElectroInk”, with a specially-developed thermal transfer process and a fast color switching technique. These are complemented by an ultra-high performance multi-beam laser scanner and unique image processing software. Pumping through the heart of HP's Indigo digital press is its propriety ElectroInk. ElectroInk enables these liquid electrophotographic printing presses to deliver prints of true offset quality. Only one to two microns in size, charged ElectroInk particles form highly defined characters, line work and halftone dot patterns. The “look and feel” of offset is achieved by a combination of ElectroInk's high saturation and extended color gamut and its unique ability to replicate the surface gloss of the underlying paper stock. The very small particles form extremely thin ink layers, less than one micron thick, enabling both high quality and low cost. Latent image formation, Binary Ink Development, and thermal offset transfer are discussed.

Simultaneous convective heat and mass transfer in impingement ink drying

Effective and economical drying of the ink is essential in the printing, packaging and converting industries. In evaporative drying, high heat and mass transfer rates are commonly achieved by means of high velocity impinging air jets To provide data for dryer designer a programme of research has been implemented to study the heat and mass transfer processes which underlie the drying of thin ink rims The heat transfer situation under impinging air jets is outlined and some experimental results are presented. Optimization of nozzle arrays for impinging air jets is analysed for practical applications. A non-contact infra-red technique for continuously monitoring the ink drying process is described and drying curves for an ink based on a single solvent (4-Methyl-2-pentanol-MIBC) are presented. Heat and mass transfer theory has been used to predict dry ing limes in the constant rate drying period These predictions have been compared with experimentally determined doing times This research has served to confirm the fundamental importance of the dry ing curve as a basis for dryer design.

Direct measurement of tensile stress (‘‘tack’’) in thin ink films

A printing press tackmeter was built by fitting a pressure sensor into the printing cylinder of a laboratory printing press. This tackmeter has been used to measure pressure profiles of thin (3–14 μm) ink films under printing conditions. We define the maximum tensile stress (or negative pressure) that the ink can withstand in the nip exit before splitting to be the tack of the ink. The tack of inks without dissolved polymer appears to be independent of film thickness. The tack of inks with dissolved polymer resin increases strongly with increased amount of ink in the nip, while pigment and dispersant content have a minor effect on ink tack. This suggests that at high speed, ink tack is mainly characterized by the response of polymer molecules toward rapidly applied stress. No universal correlation was found between the tack and viscous flow properties of the ink.

Dynamics of stick-slip jumps

The dynamics of stick-slip jumps on heterogeneous surfaces is analysed with a simple experimental model system. The heterogeneity of the surface is controlled by the application of thin low-energy ink lines on a high-energy glass surface. The liquid spreads completely on the bare glass surface but has a finite contact angle on the ink. The ink lines serve to pin the contact line in a controllable way. The stick-slip jumps from one pinning position to another manifest themselves as “waves” propagating along the contact line with well-defined shapes and constant velocity. The important findings are: (1) the propagation velocity of a stick-slip wave is to first order independent of the wave amplitude, (2) the velocity depends on the instantaneous contact angle, reminiscent of “Tanner's Law”, and (3) above a certain critical width of the pinning line, the waves halt completely.

Monolithic Multicomponents Ceramic (MMC) Substrate

AbstractNew monolithic multicomponents ceramic (MMC) substrates were made using a glass-ceramic material, low firing high dielectric constant ceramic material, metal oxide resistance materials, piezoelectric ceramic material and metal conductors. In the MMC substrate, many passive components, such as capacitors, resistors and wiring conductors can be included. In addition, designed-space can be formed in the substrate with new designed-space forming technology.The new MMC substrates have the following excellent characteristics. 1)A wide range of capacitors can be formed in the substrate.(10pF˜3μF).2)A wide range of resistors can be formed in the substrate.(10Ω/π∼1MΩ/π).3)A plurality of resistor and capacitor elements can be three-dimensionally constructed in the substrate.4)Designed-space can be formed in the substrate.5)Miniaturization and cost reduction can be accomplished in the substrate.The MMC substrates were applied to voltage controlled crystal oscillators (VCXO), CR active filters, memory cards for personal computers, AC thin film electroluminescent (AC TFEL) devices and drop-on demand ink jet heads.These devices using MMC substrate showed good electrical propeties and achieved miniaturization, multifunction and cost reduction. The new monolithic multicomponent ceramic substrate can be applied to many kinds of hybrid microcircuits and electronic components and devices.