Pattern inspection system
US4908871A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 20, 1987 |
| Grant date | Mar 13, 1990 |
| Priority date | — |
| Expiry date | Apr 20, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2207/30141
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A printed wiring board circuit-pattern inspection system including a two-dimensionally movable table on which a reference printed wiring board and a printed wiring board to be inspected are placed one after another; an image pickup unit which picks up an image of a circuit-pattern on a printed wiring board by scanning the circuit-pattern in two dimensions, and converting the image into a video signal, a binary pixel forming unit which transforms the video signal into binary pattern data, synchronous signal generator which generates a synchronous signal in synchronism with the scanning operation, a first buffer memory which stores binary pattern data, compressed pattern data memory which stores compressed binary pattern data of a whole reference printed wiring board, data compander which compresses and expands binary pattern, in accordance with the synchronous signal, a second buffer memory which stores, binary pattern data compressed by the data compander and the binary data retrieved from the compressed pattern data memory, and a comparator which compares the reference binary pattern data retrieved from the first buffer memory with the binary pattern data of the board under inspec…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.