Claims
- 1. A device for locating a bar code symbology on a presented surface, the device having a light source for illuminating the surface; a detector for generating a light intensity signal that corresponds to transitions in reflected light from the surface; and a processor for processing the light intensity signal to identify the potential location of the bar code symbology; the processor comprising:a signal generator for generating, from the light intensity signal, a series of counts which identify transitions in the light intensity; a locator for determining a location of each of the counts; a separator for separating the series of counts into alternating odd and even counts; a multiplier for simultaneously multiplying each of the separated counts by a plurality of predetermined values to simultaneously generate a corresponding plurality of odd and even comparison values; a comparator for comparing said plurality of odd comparison values to a subsequent odd count, and said even comparison values to a subsequent even count, determining whether a comparison is a valid match and outputting a valid match indicator for each valid odd/even match; and a combiner for receiving the comparator outputs and, upon detection of consecutive odd/even comparator outputs, generating a potential bar code match indicator; whereby the likelihood of the existence of the bar code symbology at a certain location increases with an increasing frequency of potential bar code match indicators.
- 2. The bar code locating device of claim 1 further comprising an encoder, and whereby said potential bar code match indicator comprises an encoded value corresponding to the width and type of a bar code symbology element.
- 3. The bar code locating device of claim 1 wherein said plurality of predetermined values comprise ¼, ⅓, {fraction (1/2.5)}, ½, 2, 2.5, 3 and 4.
- 4. The bar code locating device of claim 1 wherein higher intensities correspond to areas of higher reflectivity and lower intensities correspond to areas of lower reflectivity.
- 5. The bar code locating device of claim 4 wherein areas of higher reflectivity correspond to spaces and areas of lower reflectivity correspond to bars.
- 6. The bar code locating device of claim 1 wherein said comparator determines a positive odd and even match when said compared values are within a predetermined tolerance from each other.
- 7. The bar code locating device of claim 6 wherein said tolerance is dynamically adjusted for each comparison value.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of application Ser. No. 08/813,917, filed on Mar. 7, 1997 now abandon.
US Referenced Citations (16)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0036950 |
Oct 1981 |
EP |
0667592 |
Jan 1995 |
EP |
Continuations (1)
|
Number |
Date |
Country |
Parent |
08/813917 |
Mar 1997 |
US |
Child |
10/024409 |
|
US |