Feasibility study on a contact-less direct thermal printing with electrothermal SPICE simulation

Abstract

A new concept for making contact-less direct thermal printing for facsimile is proposed and evaluated in this article. The concept is based on the fact that air molecules can be a good thermal conduction medium capable of transferring the heat efficiently from a micro-heater to a thermal marking paper, if both in close proximity, The micro-heater can be made of single-crystal silicon by micromachining technology, hence the associated CMOS driving circuits can be fabricated monolithically with the heater to exempt from the tedious work of numerous wire bonding. An illustrative device of integrated micro-heater array in 200 dpi resolution has been fabricated, characterized and evaluated for the new printing application. A thermal model of the device has also been set up and studied of its dynamic behaviors using the existing electrothermal SPICE package. The result of simulations indicates that efficient energy transfer of more than 40%, much better than the conventional performance, can be achieved with a practical 1 mum air gap. This and other additional advantages described in the article indicates that, in principle, the contact-less direct thermal printing is feasible and the monolithic silicon micro-heater array can be an excellent device for this application. (C) 2001 Elsevier Science B.V. All rights reserved.