Method and system for controlling light intensity in a machine vision system
US5753903A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 5, 1996 |
| Grant date | May 19, 1998 |
| Priority date | — |
| Expiry date | Nov 5, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J2001/4247
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The intensity of each lamp which illuminates an object at an inspection station is controlled by controlling driving voltage applied to a power supply which supplies electrical power to the lamp. A phototransistor is used to sense the intensity of the lamp through an optical fiber. The sensor is followed by a digitally-controlled, variable gain circuit whose output is fed to an A-D converter. A microprocessor analyzes the digital signal from the A-D converter and corrects the driving voltage to the power supply to keep the intensity output of the lamp constant, as seen by a camera of a machine vision system. In this way, feedback corrects for a degraded lamp output due to aging. Preferably, the control of the level of lamp intensity can be changed from a remote system console of the machine vision system to reduce the need for access to internal parts, thereby reducing the probability that human error may cause a malfunction. The method and system of the present invention are particularly useful for inspection of digital versatile discs (DVD's) where the illumination must be changed. Also, the method and system are particularly useful in automated production lines where both audio …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.