Apparatus for detecting the presence and size of a document
US4929844A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 18, 1988 |
| Grant date | May 29, 1990 |
| Priority date | — |
| Expiry date | Nov 18, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/0422
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The invention relates to a reading apparatus provided with a document table. More particularly, it relates to a reading apparatus which automatically detects the presence or absence of a document and/or the size of a document mounted on the document table. The reading apparatus related to the invention is provided with a light source which illuminates the document table and a means for collecting information about light intensity of the document table. The reading apparatus first gains information about light intensity of the document table when the light source is off and that when it is on, and then by comparing these informations, it detects the presence or absence of a document and/or the size of the document. Accordingly, the reading apparatus correctly detects the presence or absence of a document and/or the size of the document without being affected by external light even when the document cover remains open. Furthermore, the reading apparatus correctly detects the presence or absence of a document and/or the size of the document without taking the open and closed condition of the document cover into account.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.