Capacitive electrostatic stylus writing with counter electrodes
US4424522A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 14, 1980 |
| Grant date | Jan 3, 1984 |
| Priority date | — |
| Expiry date | Nov 14, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/40031
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A capacitive charging mechanism is used in electrostatic stylus recorders having opposed writing nibs and counter electrodes to create electrostatic latent images on electrographic film and other dielectrically coated recording media. To capacitively charge the dielectric surface coating of such a recording medium, a writing voltage is first applied to one or more of the stylii or nibs and another writing voltage pulse is later applied to a counter electrode or electrode segment after a predetermined delay period which is selected to allow the nib voltages to stabilize. The charging of the dielectric surface coating of the recording medium to substantially a predetermined image voltage level occurs on the lead edge of the counter electrode writing voltage pulse. To prevent premature discharge of the charge deposited on the dielectric surface coating, the electrode writing voltage pulse is terminated before or simultaneously with the nib writing voltage pulse. Capacitive charging enables such recorders to print on electrographic film and other recording media having insulative substrates, accomodates increased printing rates, and reduces the sensitivity of the printing process to va…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.