System for automatically reading symbols, such as bar codes, on objects which are placed in the detection zone of a symbol reading unit, such as a bar code scanner
US5237161A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 5, 1991 |
| Grant date | Aug 17, 1993 |
| Priority date | — |
| Expiry date | Jun 5, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2207/1018
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A bar code label is ready by automatically initiated scanning of the bar code symbol by a scanner on a stand. Light is reflected back to the scanner as from the bars of a code being scanned. Initially, the scanner is operated in a pulsed mode with low duty cycle (5%) pulses. These pulses are reflected from a reflective area unless an object is inserted and blocks the beam path. Then (because the beam is not scanning across the code) the reflected pulses (which are detected much like the bars and spaces of the code) are not detected. The ratio of the number of generated pulses to the reflected pulses is computed for a succession of pulses. If this ratio exceeds two (i.e., that the number of effective bars is less than the number of generated pulses during the succession), then the presence of the object is detected. The system, implemented in an application program in the microprocessor controller of the bar code scanner, initiates scanning of the bar code. Upon the detection of the code (a good read) or under conditions where the label is removed before a good read, or is not removed after a good read, the scanning mode is discontinued and the pulsing mode is again initiated. The p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.