Method and apparatus for gray scale printing with a thermal ink jet pen
US4982199A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 4, 1989 |
| Grant date | Jan 1, 1991 |
| Priority date | — |
| Expiry date | Oct 4, 2009 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41J2/2128
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The firing resistor in a thermal ink jet pen is driven by two signals in sequence. The first signal is a warming signal, tailored to transfer a desired quantity of thermal energy to the ink in the firing nozzle. The second signal is a firing pulse tailored to vaporize ink adjacent the resistor and thereby eject a bubble of ink from the nozzle. The prewarming of the ink achieved by the warming pulse increases the volume of the vapor bubble produced by the firing pulse, thereby yielding a commensurately larger ink droplet. By varying the degree of prewarming, the droplets ejected by the firing pulse can be varied in volume, thereby effecting gray scale printing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.