Printed heaters

An aqueous ink composition is ejected as droplets onto a plastic medium to form an image on the plastic medium. A method for ejecting the droplets may utilize the vibration of a piezoelectric element, which enables excellent image recording. The plastic medium is then heated to 40-60°C with a print heater of the inlqet recording apparatus and a dryer to dry the deposited aqueous ink composition. 

Thermal printing usually involves passing materials over a full-width array of electronically controlled heaters (a thermal printhead). This marks thousands of spots simultaneously, so pages print relatively quickly. Image data to control the printhead usually come from computer systems. Black-and-white and full-color systems are both practical. Color is slower and more cosdy to purchase and use, primarily because this involves three or four successive printing operations, one for each color used. 

U.S. Consumer Product Safety Commission. (1988). What You Should Know About Kerosene Heaters. Washington, DC U.S. Government Printing Office. 

The heater, the underlayer, the zirconia solid electrolyte and the two electrodes are formed by screen printing and sintering. The sintering condition is at 1,U80°C for 2HR in air. The temperature of sensor surface rises to 600°C with plasma spraying. 

The particles are mixed with colloidal silica, and the mixture is screen-printed (0.15 mm in thickness) on a ceramic substrate (3 x 3 x 0.15 mm3). The thick film heater is printed on the other side of the substrate. 

Figure 12 shows the CTL-based sensor element. The platinum ribbon wire (0.2 mm in width and 0.02 mm in thickness) is spot-welled on the screen-printed substrate as heater lead wires, and the sensor chip is suspended on a plastic frame by the lead wires. In order to measure the catalyst temperature, very thin thermocouple wires are fixed on the substrate using ceramic cement. 

The heater for the reaction chamber and the conductors were printed on the lowest layer and electrically contacted to the pads on the cover layer by vertical metal-filled vias in every intermediate layer. Still some manual work was necessary to shape the reaction channel from the pre-fired tapes. Also the soldering of clamp-type fittings to the cover layer is certainly difficult to automate. However, a manufacturing process for ceramic foil reactors seems to be within reach. 

The screen-printing paste is made up in the manner described in Section 4.2.2 and the patterns printed. The heater element and its leads would typically be platinum and the interdigitated electrodes gold. As illustrated below (Fig. 4.49) the heater might also be a composition based on ruthenium oxide (see Section 4.2.2). The contacting tabs are also screen-printed gold. 

Usually, as the coated web emerges from the last zone of the oven it passes a bank of infra-red heaters (which maintain the temperature) and through a simple direct emboss nip fitted with a plain embossing roller. This treatment helps to smooth minor imperfections in the surface and gives a matt finish preparatory to printing. The roller is of steel with surface grit-blasted or (better) with a sprayed ceramic surface and water-cooled internally. 

Both compact and expanded wallcoverings can exhibit blistering at the embossing stage with the former this is attributable to residues of solvents from printing inks and lacquers, which may evaporate explosively when exposed to the radiant heaters (in bad instances, solvent vapours may accumulate and... 

There are several limitations on the physical properties of UV curable inkjet inks for piezoelectric DOD print heads. The viscosity needs to be fairly low — 8-12 cps at the jetting temperature (most print heads have on-board heaters, capable of reaching up to 70°C in many instances). The surface tension of the inks is also important, and depends on the print head technology being utilized. Some print heads are equipped with a non-wetting faceplate, while others work best with fairly high surface tension fluids (mid 20s to upper 30s, dynes/cm)... 

The print head of standard, color inkjet printers (Cannon, Hewlett-Packard) is composed of a nozzle, heater, manifold chamber, and restrictor. Once the resistive element is heated (300°C) the fluid... 

When a paper display is needed or when textual information is to be printed, as in a report, it is common to use a digital printer such as a laser jet or inkjet printer. These devices are inexpensive and provide 600 to 2400 dots per inch, more than adequate for most applications. The laser jet devices use an electrostatic transfer of black toner material to paper to form the desired image, which is then fused to the paper by passage over a heater. Color versions are available but are more expensive because they require three toner cartridges, one for each of the primary colors. The inkjet printers use movable solid-state heads with many fine holes through which small droplets of ink are ejected by selective localized heating behind the orifices. The ink is drawn by capillary action from a reservoir chamber and, by use of three primary colors, full-color images can be printed at up to 2400 dots per inch. 

The manufacturing process for fabricating rod-shaped heaters is similar to those used in planar technology, because the active heater pattern is typically printed on an alumina tape that is wound around a pre-fired alumina rod or tube. The alumina allows sintering at low 02 pressure and therefore inexpensive tungsten is the typical heater material. However, leaks and the residual porosity of the materials lead to a continuous increase in electrical resistance, caused by slow tungsten oxidization. 

An early example of an integrated gas sensor array is a thick-film implementation developed by Hitachi [49], with six discrete metal oxide sensor areas on an alumina substrate (figure 14.5). The chip is heated to 4(K) °C with a platinum heater printed on the bottom of the substrate. More recently, other Sn02-based arrays have been reported. A low-power, 1.5 mm foursensor array employing Sn02 has been demonstrated for detection of toxic... 

Another technique, used by Figaro Engineering Inc. and others, is to coat an alumina tube with tin oxide in an organic matrix, such as stearic acid, and sinter at 400-700 °C. A porous film results. Electrodes at either end of the tube are printed on or embedded in the sintered oxide and a platinum heater coil is positioned inside the tube. 

Fig. 4 Photographs of p-DAAD production steps, (a) Front side of a 4" silicon wafer populated with etched microreactors 16 p-DAAD are processed in parallel, each consisting of four microreactors. (b) Front-side view of a single p-DAAD (16 x 1 mm ) after bonding a cover plate and dicing. DNA arrays are printed onto the bottom of the microreactor cavities, but carmot be seen in this image because of their small size. Holes of 1 mm in diameter are drilled in the cover glass for the filling of the p-DAAD reactors with reagent, (c) Back-side view of the device with platinum heater coil and thermoresistors placed at the corresponding area of the microreactor. Reproduced from [79] with permission...

Device structures adopted for resistor type sensors in practice, (a) Sintered block, (b) thin alumina tube-coated layer, (c) screen printed thick film, (d) small bead inserted with coil and needle electrodes, (e) small bead inserted with a single coil (heater and electrode), (f) practical sensor element assembling sensor device, metal cap and filter. 

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