Optical media monitoring device
US4785295A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 20, 1987 |
| Grant date | Nov 15, 1988 |
| Priority date | — |
| Expiry date | Feb 20, 2007 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB65H2557/61
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
In an optical media monitoring device that detects presence of light-interrupting media between a photoemitter component and a photoreceptor component provided to operate in cooperation with each other, the photoemitter component is driven at a variable level of light emission, and a comparator compares the output of the photoreceptor component with a reference signal which is also variable. The driving means is controlled to cause the photoemitter component to emit a level of light lower than normally used for media detection. Dust degradation of the sensor is determined by checking, in a state of no media present and the reduced light emission of the photoemitter component, whether the output of the photoreceptor component is greater than the reference signal level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.