Gray scale printhead system
US4992807A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 4, 1990 |
| Grant date | Feb 12, 1991 |
| Priority date | — |
| Expiry date | May 4, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/40025
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An electrographic printhead assembly comprises first and second sets of electrodes which define an array of crossing regions for generating packets of electric charge. An RF electrode burst actuates a first electrode to generate charge carriers while a varying extraction potential is developed. A second electrode is then activated with one or more control pulses which are synchronized with the RF burst and with selected portions of the varying extraction potential to gate charge carriers from the printhead. This deposits the desired charge level for each dot on an imaging member. The assembly forms a gray scale latent image for printing, and provides enhanced range without requiring higher frequency or longer duration RF bursts.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.