Detection system and detection method of document size for use in a document reader
US5519483A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 9, 1993 |
| Grant date | May 21, 1996 |
| Priority date | — |
| Expiry date | Jul 9, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G15/607
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A light-emitting elements emits a light beam onto a predetermined sensing position, and a reflected beam from an original is received by a light-receiving element. The light-receiving element, which is a position sensitive detector for detecting a spot position of the reflected beam, releases a pair of currents that vary according to the spot position. A signal processing circuit detects the presence or absence of the original based on the ratio of the currents. The pair of currents released by the light-receiving element fluctuate in response to changes in reflection factor due to the individual color of the original, while the ratio of the pair of currents does not fluctuate even if the reflection factor changes. Thus, detection accuracy is improved, and erroneous detection can be prevented in comparison with an arrangement wherein the presence or absence of the original is detected by detecting and comparing the amount of light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.