Image recording apparatus and rearview CRT therefor
US5389985A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 15, 1993 |
| Grant date | Feb 14, 1995 |
| Priority date | — |
| Expiry date | Nov 15, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/0404
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An imaging system such as an image recorder or scanner is provided with a rearview cathode ray tube. A transparent viewport of optical quality is provided along an optical axis of the CRT which is perpendicular to the CRT faceplate and generally centered with respect to the image area. The electron beam used for scanning the images is placed off-axis with respect to the CRT screen. A deflection control system compensates for spherical distortion and for the keystone effect that results from the off-axis placement of the electron gun. The structure of the present invention eliminates halation, thereby improving the dynamic range and contrast achievable for imaging and/or scanning purposes. The phosphor layer used in the CRT is made substantially thicker than in conventional CRTs, thereby reducing blemishes and improving uniformity, resolution and light output. The partial sharing of electron beam and optical paths enables more compact imaging and scanning systems to be provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.