Image reading apparatus
US4691365A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 25, 1984 |
| Grant date | Sep 1, 1987 |
| Priority date | — |
| Expiry date | May 25, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/401
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image reading apparatus has a CCD for reading an original image, a standard white plate for providing a standard image signal, a control circuit for controlling light amount and temperature of a fluorescent lamp as a light source, a CPU for controlling the operation sequence of the overall apparatus, a RAM for storing a standard image signal corresponding to the standard white plate, a ROM storing a control program for the CPU, and a display for displaying an error. An image signal of an original read by the CCD is corrected in accordance with the standard image signal. For example, an average value of a block of four pixel image signals, for example, is calculated and is compared with an average value of the standard image signals obtained by reading the standard surface a plurality of times. An abnormal pixel signal is replaced with an immediately preceding normal pixel signal or a predetermined signal pattern. An abnormal light amount or temperature of the fluorescent lamp is detected in accordance with the standard signal corresponding to the standard surface exposed by the lamp.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.