Thermal printing apparatus with reference gray scale comparator
US4443121A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 1, 1983 |
| Grant date | Apr 17, 1984 |
| Priority date | — |
| Expiry date | Mar 1, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/40
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A thermal transfer printing head for printing gray scale television frame images is driven by pulse width modulated signals derived without the use of comparators by employing a read only memory in which pulse width modulation data has been stored. The read only memory is addressed by the data signals and a reference gray scale counter to produce pulsed output signals fed to a random access memory. The random access memory is then read out by addressing it with addresses corresponding to gray scale reference signals and cyclical addresses produced by an address counter. The random access memory output signals, representing the pulse width modulated image data, is converted to parallel signals fed to a latch and driver circuit for energizing the individual heat elements of the thermal printing head.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.