Thermal drop-on-demand ink jet print head

A thermal drop-on-demand ink jet print heat comprising;

• an electrically insulating substrate member;
• an array of first electrical connection members formed on a first surface of said substrate member:
• a common electrical connection member on said first surface of said substrate member;
• an array of heating means on said first surface of said substrate member, said heating means being positioned on said substrate member so that each of said heating means are connected in an electrical circuit between one of said first electrical connection members and said common electrical connection member, each of said heating means comprising a plurality of elongated portions spaced by a predetermined distance which enclose an elongated opening within said heating means;
• and
• a nozzle plate fixedly mounted adjacent to said substrate member and having a nozzle therein disposed adjacent to each of said heating means whereby, upon connection of an electrical signal to a selected one of said first electrical connection members, a bubble is formed at each of said plurality of portions of said heating means, said predetermined distance being chosen so that all of said bubbles coalesce to form a single pillow-shaped bubble and a drop of ink is ejected from the adjacent nozzle.