Integrated illumination assembly for symbology reader

• US 9,405,951 B2
• Filed: 10/08/2010
• Issued: 08/02/2016
• Est. Priority Date: 10/24/2005
• Status: Active Grant

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Inventors: Nunnink, Laurens, Equitz, William H.
• Primary Examiner(s): HESS, DANIEL A
• Application Number:
  US12/900,617
• Publication Number:
  US 20110080729A1
• Time in Patent Office: 2,125 Days
• Field of Search: 235/454, 235/473, 235/462.01, 235/462.22, 235/462.42
• US Class Current: 1/1
• CPC Class Codes: G06K 7/10732 Light sources

Abstract

A light transmitter (e.g., pipe) is constructed from polycarbonate for increased shock resistance and can define a rectangular cross section. A chamfered end of the light pipe is textured or frosted to further diffuse refracted light passing through the end to present a more even effect. A conical/tapered diffuser within the light pipe is illuminated by a reflector that reflects a plurality of rear-ward-directed illumination sources back into the diffuser. The reflector can direct light into the forwardmost, remote regions of the diffuser to generate a better spread of light and alleviate spotting effects. The illumination sources can be multi-colored sources that respond to a controller to project a color and/or blink in a pattern to indicate various conditions. The controller can operate individual portions of the ring so that only corresponding portions of the light pipe perimeter are illuminated in a particular color at a given time. Different quadrants may be simultaneously illuminated in different colors.

Claims

1. An illumination assembly for a mark reader comprising:

a passive light transmitter including an inner lumen through which at least a portion of a mark is detectable, the passive light transmitter having a proximal end and a distal end, the distal end comprising a chamfered surface, the chamfered surface having a diffusive surface texture;

at least one light element positioned adjacent the proximal end and adapted to transmit light into the proximal end, at least a portion of the transmitted light internally reflecting through the light transmitter to the chamfered surface and, at the chamfered surface, reflecting out of the light transmitter through an interior wall of the light transmitter facing the inner lumen as dark field illumination; and

at least a different portion of the transmitted light internally reflecting through the light transmitter to the chamfered surface and being refracted out of the light transmitter and through the diffusive surface texture of the chamfered surface as bright field illumination.

2. The illumination assembly according to claim 1 wherein the light transmitter comprises a flattened ring configuration and positioned generally perpendicular to the first direction.

3. The illumination assembly according to claim 1 wherein the diffuser includes staggered clear portions and diffusive portions.

4. An illumination assembly for a mark reader comprising:

a passive light transmitter including an inner lumen through which at least a portion of a mark is detectable, the passive light transmitter having a proximal end and a distal end;

at least one forward projecting light element positioned adjacent the proximal end and adapted to transmit a first light in a first direction into the proximal end, at least a portion of the transmitted first light internally reflecting through the light transmitter to the distal end and exiting the light transmitter as dark field illumination; and

at least one rearward projecting light element positioned so as to transmit a second light in a second direction so that the second light exits the assembly as direct light onto at least a portion of the mark.

5. The illumination assembly according to claim 4 wherein the direct light exits the assembly as bright field illumination.

6. The illumination assembly according to claim 4 wherein the at least one rearward projecting light element is positioned so as to transmit the second light in the second direction to spread the second light toward a diffuser positioned within the inner lumen, the diffuser diffusing the second light so that the diffused second light exits the diffuser as a spread of diffuse light onto at least a portion of the mark.

7. An illumination assembly for a mark reader comprising:

a passive light transmitter including an inner lumen through which at least a portion of a mark is detectable, the passive light transmitter having a proximal end and a distal end;

at least one forward projecting light element positioned adjacent the proximal end and adapted to transmit a first light in a first direction into the proximal end, at least a portion of the transmitted first light internally reflecting through the light transmitter to the distal end and exiting the light transmitter as dark field illumination;

a tapered diffuser positioned within the inner lumen, the diffuser diffusing a second light so that the diffused second light exits the diffuser as diffuse light onto at least a portion of the mark; and

wherein at least one rearward projecting light element is positioned so as to transmit the second light in a second direction to spread the second light toward the diffuser positioned within the inner lumen, the diffuser diffusing the second light so that the diffused second light exits the diffuser as a diffuse light onto at least a portion of the mark.

8. The illumination assembly according to claim 7 wherein the diffuse light exits the assembly as bright field illumination.

9. The illumination assembly according to claim 7 wherein the diffused second light exits the diffuser as a spread of direct, substantially uniform diffuse light onto the at least a portion of the mark.

10. The illumination assembly according to claim 7 wherein the rearward projecting light element transmits the second light in a second direction toward a reflector, the reflector adapted to spread the reflected second light toward the diffuser positioned within the inner lumen, the diffuser diffusing the reflected second light so that the diffused second light exits the diffuser as a spread of diffuse light onto the at least a portion of the mark.

11. The illumination assembly according to claim 7 wherein the distal end comprises a chamfered surface, the chamfered surface having a diffusive surface texture.

12. The illumination assembly according to claim 11 wherein at least a different portion of the transmitted first light internally reflects through the light transmitter to the chamfered surface and is refracted out of the light transmitter by the diffusive surface texture of the chamfered surface as bright field illumination.

13. A mark reader comprising:

a light transmitter defined by a central axis and including at least a first light transmitter segment and a second light transmitter segment, the first light transmitter segment being spaced further from the central axis than the second light transmitter segment;

at least one light source adjacent a proximal end of the light transmitter;

the light transmitter further including a distal end, the distal end adapted to direct light from the at least one light source onto a surface as dark field illumination; and

the distal end of the first light transmitter segment directing the dark field illumination at a first convergence distance, and the distal end of the second light transmitter segment directing the dark field illumination at a second convergence distance, the second convergence distance being different than the first convergence distance.

14. The mark reader according to claim 13 wherein the light transmitter is constructed from polycarbonate.

15. The mark reader according to claim 13 wherein the light transmitter further defined by at least four adjacent sides including a first opposing pair of sides having a first spacing, and a second opposing pair of sides having a second spacing, the first spacing between the first opposing pair of sides having a length that is different than a length of the second spacing between the second opposing pair of sides.

16. The mark reader according to claim 15 wherein the distal end of the first opposing pair of sides directs the dark field illumination at a first convergence distance, and the distal end of the second opposing pair of sides directs the dark field illumination at a second convergence distance, the second convergence distance being different than the first convergence distance.

17. The mark reader according to claim 13 wherein the light transmitter distal end includes a chamfered surface.

18. The mark reader according to claim 17 wherein the chamfered surface of the light transmitter distal end includes a diffusive texture.

19. An illumination assembly for a mark reader comprising:

a passive light transmitter including an inner lumen through which at least a portion of a mark is detectable, the passive light transmitter having a proximal end and a distal end, the distal end comprising a chamfered surface, the chamfered surface having a diffusive surface texture;

at least one light element positioned adjacent the proximal end and adapted to transmit light into the proximal end, at least a portion of the transmitted light internally reflecting through the light transmitter to the chamfered surface and being refracted out of the light transmitter and through the diffusive surface texture of the chamfered surface as bright field illumination; and

a diffuser positioned within the inner lumen, the diffuser diffusing a different portion of the transmitted light so that the diffused transmitted light exits the diffuser as a spread of diffuse light onto at least a portion of the mark.

20. The illumination assembly according to claim 19 wherein the diffused transmitted light exits the diffuser as diffuse bright field illumination.

21. The illumination assembly according to claim 19 wherein at least an additional different portion of the transmitted light internally reflects through the light transmitter to the chamfered surface and, at the chamfered surface, reflects out of the light transmitter through an interior wall of the light transmitter facing the inner lumen as dark field illumination.

22. A method of illuminating at least a portion of a mark to obtain an image, the method comprising:

providing a passive light transmitter including an inner lumen through which at least a portion of a mark is detectable, the passive light transmitter having a proximal end and a distal end, the distal end comprising a chamfered surface;

illuminating at least one light element positioned adjacent the proximal end;

transmitting light from the at least one light element into the proximal end, at least a portion of the transmitted light internally reflecting through the light transmitter to the chamfered surface and being refracted out of the light transmitter and through the chamfered surface to illuminate at least a portion of the mark with bright field illumination;

obtaining a first image of the at least a portion of the mark with the bright field illumination;

transmitting a different portion of the light from the at least one light element toward a diffuser, the diffuser diffusing the at least a different portion of the light so that the diffused light exits the diffuser to illuminate the at least a portion of the mark as diffuse light; and

obtaining a second image of the at least a portion of the mark with the diffuse light.

23. The method according to 22 wherein the diffused light exits the diffuser as diffuse bright field illumination.

24. The method according to 22 wherein the chamfered surface includes a diffusive surface texture.

25. The method according to 22 wherein the diffuser is positioned within the inner lumen.

26. The method according to 22 wherein the at least one light element includes at least a first light element for transmitting light into the proximal end, and at least a second light element for transmitting light toward the diffuser.

27. The method according to 22 further including internally reflecting at least a different portion of the transmitted light through the light transmitter to the chamfered surface and, at the chamfered surface, reflecting the different portion of the transmitted light out of the light transmitter through an interior wall of the light transmitter facing the inner lumen to illuminate the at least a portion of the mark with dark field illumination.

28. The method according to 27 further including obtaining a third image of the at least a portion of the mark with the dark field illumination.