Thermal printing head and method of making same
US4194108A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 18, 1978 |
| Grant date | Mar 18, 1980 |
| Priority date | — |
| Expiry date | Jan 18, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49099
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A thermal printing head for printing alphanumeric characters on a thermally-responsive medium, the head being faced with a pattern of heat generating "dot" elements electrically insulated from one another and having conductive leads, with means for connecting the leads selectively to a source of electric current. The heat generating elements are formed of a film of boron phosphide. Preferably the leads are also formed of boron phosphide, integral with the elements, but "doped" to secure a high degree of conductivity. The printing head is formed by applying a boron phosphide compound on a substrate, covering the same with a passivation film, removing the passivation film to expose a background area of the compound film defining a central "island" of unexposed area, doping the exposed background area to increase the conductivity thereof, removing the passivation film from the island, and forming grooves in the compound film dividing the island into separate heat generating elements, with the grooves extended into the background area to form pairs of integral conductive leads for the elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.