Redundancy reduction system for facsimile transceivers
US4095248A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 16, 1976 |
| Grant date | Jun 13, 1978 |
| Priority date | — |
| Expiry date | Jun 16, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/17
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A facsimile transmitter-receiver system which is adapted for use over a limited band width transmission path employs a redundancy reduction unit to speed-up transmission time by rapidly sweeping the transmitters single scanning beam in full or partial search passes across proposed data free areas of a source document. In the horizontal direction a transition to partial fast search during a horizontal pass is made beyond a proposed right hand data boundary and is accompanied by a one line space temporary downward deflection or bias of the scanning beam, which facilitates search for new data boundaries and also permits the system to make a slow scan retrace of a line (by eliminating the bias whenever data is actually found in the search pass). Fast search in the vertical direction is effected by two related methods: (1) The use of a wide search pass in which the scanning beam is effectively widened during a horizontal pass, preferably by zigzagging the beam up and down with a simple vertical modulation which is many lines wide and; (2) By thereafter sufficiently increasing the spacings between successive wide search passes of the scanning beam so that each successive wide search pass…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.