Anti-hand-jittering dataform readers and methods

• US 5,691,773 A
• Filed: 09/12/1995
• Issued: 11/25/1997
• Est. Priority Date: 09/12/1995
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Metanetics Corporation
• Inventors: Wang, Ynjiun P., Ye, Angi
• Primary Examiner(s): PITTS, HAROLD I
• Application Number:
  US08/526,868
• Time in Patent Office: 805 Days
• Field of Search: 358/213, 348/699, 348/249, 235/472, 235/494
• US Class Current: 348/249
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03
• CPC Class Codes: G06K 7/10861 sensing of data fields affixed to objects or articles, e.g. coded labels postal sorting B07C3/14, conveying articles B65G47/48
• CPC Class Codes: G06K 7/1093 sensing, after transfer of the image of the data-field to an intermediate store, e.g. storage with cathode ray tube
• CPC Class Codes: G06K 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/1491 the method including a reconstruction step, e.g. stitching two pieces of bar code together to derive the full bar code

Abstract

Dataform readers using two-dimensional sensor array cameras provide image frames comprising successive first and second fields of image data. In hand-held operation, hand jitter results in image offset causing registration errors between fields. Resolution and decoding performance are enhanced by described readers and methods. Decoding is implemented first by use of image data of a first field and the results of such decoding are supplemented by results of decoding of remaining portions of the dataform by use of second field image data. Decoding may also be carried out by first determining the magnitude of a disparity vector extending in the direction of image offset. The disparity vector is then used to provide enhanced decoding by use of first field image data and registration-corrected second field image data.

Claims

1. A dataform reader, configured to reduce effects of image offset causing registration error between sequential fields of image data, comprising:

a sensor array responsive to illumination reflected from a dataform to provide signals representative of illumination levels on first and second groups of sensors respectively representing first and second field images subject to image offset;

a memory coupled to said sensor array to store first field image data representative of said illumination levels on the first group of sensors and to store second field image data representative of said illumination levels on the second group of sensors; and

a processor arranged to access said memory to utilize said first field image data to decode a portion of said dataform and to utilize said second field image data to supplement decoding of said dataform.

2. A dataform reader as in claim 1, wherein said processor is arranged to use said second field image data to decode one or more portions of said dataform when said portions are not decodable by use of said first field image data.

3. A dataform reader as in claim 1, wherein said processor is arranged to use said first field image data to attempt to decode all portions of said dataform, to use said second field image data to attempt to decode all portions of the dataform, and to use decoded results from said second field image data to supplement incomplete decoded results from use of said first field image data.

4. A dataform reader as in claim 1, wherein said processor is arranged to use image data of said first and second fields to determine a magnitude value of a disparity vector representative of an image offset between image data of said fields, said disparity vector value usable to correct offset effects during decoding of said dataform.

5. A dataform reader as in claim 4, wherein said processor is arranged to use the magnitude value of said disparity vector to correct image offset effects to enable combined use of image data of said first and second fields for decoding of said dataform.

6. A dataform reader as in claim 1, wherein said dataform reader is configured for hand-held use and field-to-field hand-held jitter causes said image offset.

7. A dataform reader as in claim 1, wherein said memory comprises a first memory capacity coupled to said sensor array to store said first field image data and a second memory capacity coupled to said sensor array to store said second field image data.

8. A dataform reader as in claim 7, wherein said first and second memory capacities are one of:

two separate field store memories;

first and second sections of a common memory; and

selected address location portions of a common memory.

9. A dataform reader as in claim 1, wherein said processor is a microprocessor operating with appropriate software programming.

10. A dataform reader, configured to reduce effects of image offset causing registration error between sequential fields of image data, comprising:

a sensor array responsive to illumination reflected from a dataform to provide signals representative of illumination levels on first and second groups of sensors respectively representing first and second field images subject to image offset;

a memory coupled to said sensor array to store first field image data representative of said illumination levels on the first group of sensors and to store second field image data representative of said illumination levels on the second group of sensors; and

a processor responsive to image data of said first and second fields to determine the magnitude of at least one disparity vector extending in a direction representative of said image offset, said processor arranged to utilize said disparity vector magnitude to provide enhanced decoding of said dataform by use of image data of both said first and second fields.

11. A dataform reader as in claim 10, wherein said processor utilizes said disparity vector magnitude to enable image data of said first and second fields to be combined with improved registration prior to decoding of said dataform.

12. A dataform reader as in claim 10, wherein said processor utilizes said disparity vector magnitude to provide registration corrections enabling processing of corresponding portions of image data of said first and second fields in decoding of said dataform.

13. A dataform reader as in claim 10, wherein said dataform reader is configured for hand-held use and field-to-field hand-held jitter causes said image offset.

14. A dataform reader as in claim 10, wherein said memory comprises a first memory capacity coupled to said sensor array to store said first field image data and a second memory capacity coupled to said sensor array to store said second field image data.

15. A dataform reader as in claim 14, wherein said first and second memory capacities are one of:

two separate field store memories;

first and second sections of a common memory; and

selected address location portions of a common memory.

16. A dataform reader as in claim 10, wherein said processor is a microprocessor operating with appropriate software programming.

22. A dataform reader as in claim 11, wherein said processor is a microprocessor operating with appropriate software programming.

17. A dataform reader, configured to reduce effects of image offset causing registration error between sequential fields of image data, comprising:

a sensor array responsive to illumination reflected from a dataform to provide signals representative of illumination levels on first and second groups of sensors respectively representing first and second field images subject to image offset;

a memory coupled to said sensor array to store first field image data representative of said illumination levels on the first group of sensors and to store second field image data representative of said illumination levels on the second group of sensors; and

a processor responsive to image data of said first and second fields to determine the magnitude of at least one disparity vector extending in a direction representative of said image offset, said processor arranged to utilize said disparity vector magnitude to provide an enhanced image.

18. A dataform reader as in claim 17, wherein said processor utilizes said disparity vector magnitude to enable image data of said first and second fields to be combined with improved registration to provide said enhanced image.

19. A dataform reader as in claim 17, wherein said dataform reader is configured for hand-held use and field-to-field hand-held jitter causes said image offset.

20. A dataform reader as in claim 17, wherein said memory comprises a first memory capacity coupled to said sensor array to store said first field image data and a second memory capacity coupled to said sensor array to store said second field image data.

21. A dataform reader as in claim 20, wherein said first and second memory capacities are one of:

two separate field store memories;

first and second sections of a common memory; and

selected address location portions of a common memory.