Method and apparatus for providing omnidirectional lighting in a scanning device

• US 8,282,000 B2
• Filed: 11/11/2011
• Issued: 10/09/2012
• Est. Priority Date: 10/24/2003
• Status: Active Grant

• Current Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Original Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Inventors: Gerst, Carl W. III, Equitz, William H, Testa, Justin, Nadahar, Sateesh
• Primary Examiner(s): Trail, Allyson
• Application Number:
  US13/294,285
• Publication Number:
  US 20120118966A1
• Time in Patent Office: 333 Days
• Field of Search: 235/455, 235/642.42, 235/462.01, 235/462.45
• US Class Current: 235/455
• CPC Class Codes: G06K 7/10732 Light sources
• 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 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/146 the method including quality enhancement steps

Abstract

Systems and methods are provided for selectively controlling the illumination, and particularly dark field illumination, applied to a symbol to be decoded, and for determining a suitable or optimized level of lighting for decoding the symbol. A method includes providing a light source comprising a plurality of individually-controllable lighting elements for providing low angle dark field illumination; activating an image sensor for detecting image data reflected from an encoded data symbol when the encoded data symbol is illuminated by the light source; and providing a controller connected to each of the individually-controllable lighting elements, the controller being programmed for: selectively activating the individually-controllable lighting elements to vary the direction of the low angle dark field illumination provided by the light source; and processing the image data detected by the image.

Claims

1. A method for decoding an encoded data symbol, the method comprising:

providing a light source comprising a plurality of individually-controllable lighting elements for providing low angle dark field illumination;

activating an image sensor for detecting image data reflected from an encoded data symbol when the encoded data symbol is illuminated by the light source; and

providing a controller connected to each of the individually-controllable lighting elements, the controller being programmed for;

selectively activating the individually-controllable lighting elements to vary the direction of the low angle dark field illumination provided by the light source;

evaluating the detected image data and determining whether the detected image data is sufficient to decode the encoded data symbol;

varying the low angle dark field illumination provided by the light source until the detected image data is sufficient to decode the encoded data symbol; and

processing the image data detected by the image sensor.

2. The method according to claim 1, wherein the individually controllable lighting elements comprise portions of at least one of a circular ring, an oval ring, a rectangular ring, and an elliptical ring.

3. The method according to claim 1, wherein the individually-controllable lighting elements comprise a plurality of electrically-connected individual light elements.

4. The method according to claim 1, further including the controller evaluating the image data detected by the image sensor and varying the dark field illumination to optimize symbol decoding.

5. The method according to claim 1, wherein the dark field light source comprises a passive light pipe or an active light pipe.

6. The method according to claim 1, further including providing a manual control connected to the controller for manually selecting at least one of the individually-controllable lighting elements to be activated.

7. The method according to claim 1, further including providing a memory component for storing data corresponding to the individually-controllable lighting elements.

8. The method according to claim 1, further including the controller varying an exposure time of the image sensor.

9. The method according to claim 1, further including the controller determining whether the image data detected is sufficient to decode the encoded data symbol based on a statistical analysis of the image data detected.

10. The method according to claim 1, further including the controller determining whether the image data detected is sufficient to decode the encoded data symbol based on an attempt to decode the encoded data symbol.

11. The method according to claim 1, wherein the image sensor is connected to the controller for detecting light reflected from the encoded data symbol and for providing feedback to the controller for varying lighting conditions.

12. The method according to claim 1, wherein the dark field light source is arcuate.

13. The method of claim 1, further including providing a bright field light source for providing bright field illumination;

wherein the controller is connected to the bright field illumination source and programmed for selectively activating the bright field light source.

14. The method according to claim 13, further including providing a handheld enclosure for housing the dark field light source, the bright field light source, and the image sensor.

15. The method according to claim 13, further including providing a fixed mount enclosure for housing the dark field light source, the bright field light source, and the image sensor.

16. A method for decoding an encoded data symbol, the method comprising the steps of:

(a) providing a plurality of individually-controllable lighting elements arranged around the encoded data symbol to provide low-angle dark field illumination;

(b) providing a bright field illuminator directed at the encoded data symbol to provide bright field illumination;

(c) selectively illuminating the encoded data symbol with at least one of the individually-controllable lighting elements;

(d) acquiring an image data set;

(e) evaluating the image data set for determining suitability for decoding;

(f) selectively varying a lighting parameter for varying the light emitted from the individually-controllable lighting elements to vary the direction of the low-angle dark field illumination on the encoded data symbol and selectively activating the bright field illuminator; and

(g) repeating steps (d), (e) and (f) until the image data set is suitable for decoding.

17. The method according to claim 16, further including the step of arranging the individually controllable lighting elements in quadrants.

18. The method according to claim 17, wherein wherein successive occurrences of step (c) further includes sequentially activating at least one combination of the quadrants.

19. The method according to claim 16, further including the step of storing the lighting parameter found to be suitable for decoding the image data set.

20. The method according to claim 16, wherein step (c) further includes retrieving a stored illumination setting.

21. The method according to claim 16, wherein step (a) further includes retrieving default parameters for activating each of the lighting elements.

22. The method according to claim 16, wherein step (e) further includes evaluating the image date set for decoding the encoded data symbol.

23. The method according to claim 16, wherein step (e) further includes evaluating the image data set for evaluating a relative concentration of light and dark pixels.

24. The method according to claim 16, wherein step (f) further includes selectively varying the light emitted by modulating a signal applied to at least one of the individually-controllable lighting elements to vary a brightness of the illumination.

25. The method according to claim 16, wherein step (f) further includes selectively varying an exposure time for illuminating the encoded data symbol.

26. The method according to claim 16, wherein step (f) further includes selectively varying a focus parameter.

27. The method according to claim 16, wherein step (f) further includes selectively activating at least one of the individually-controllable lighting elements.

28. The method according to claim 16, wherein step (a) further includes angling the light emitted from the individually-controllable lighting elements to provide the low angle dark field illumination.

29. A method comprising:

using a ring light source, projecting low angle dark field illumination to an adjacent surface including a symbol to be decoded;

providing a controller connected to the ring light source and using the controller for selectively varying the direction of the low angle dark field illumination provided from the ring light source;

using an image sensor connected to the controller, the image sensor acquiring image data of the symbol, wherein the controller is programmed for;

evaluating the acquired image data and determining whether the image data is sufficient to decode the symbol; and

varying the light projected from the ring light source until the image data is sufficient to decode the symbol.

30. The method according to claim 29, further comprising using a bright field light source, projecting bright field illumination to the adjacent surface, wherein the controller is further programmed for selectively activating the bright field light source to illuminate the symbol.