Integrated illumination assembly for symbology reader

• US 20070090193A1
• Filed: 10/24/2005
• Published: 04/26/2007
• Est. Priority Date: 10/24/2005
• Status: Active Grant

• Current Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Original Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Inventors: Nunnink, Laurens, Equitz, William
• Granted Patent: US 7,874,487 B2
• Time in Patent Office: Days
• US Class Current: 235/473
• CPC Class Codes: G06K 7/10732 Light sources

Abstract

This provides a plurality of novel features that can be applied variously to a reader. In one embodiment, the light pipe is constructed from durable polycarbonate for increased shock resistance and can define a rectangular cross section. The chamfered end of the light pipe is textured or frosted to further diffuse refracted light passing through the end so as to present a more even effect. The conical/tapered diffuser within the light pipe is illuminated by a reflector with a white textured surface that reflects a plurality of rearward-directed illumination sources back into the diffuser. The reflector can define a predetermined cross section that directs further light into the forwardmost, remote regions of the diffuser to generate a better spread of light and alleviate spotting effects. The textured surface on the chamfered light pipe end can be employed to better project indicator light. The illumination sources are arranged in a ring at the inner end of the pipe, and can be multi-colored sources that respond to the controller to project and appropriate color and/or blink in an appropriate pattern to indicate various conditions, such as read success or failure. The controller is adapted to provide indications between image acquisitions. 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 (quadrants, for example) at a given time. Different quadrants may be simultaneously illuminated in different colors in one example

Claims

1. An illumination assembly for a mark reader comprising:

a light pipe having a distal end, defining chamfered end along an outer surface, the chamfered end projecting, through an interior wall, internally reflected light onto a surface as dark field illumination and refracted light onto the surface as direct bright field illumination, the distal end including an outer surface having a diffusive surface texture.

2. The illumination assembly as set forth in claim 1 wherein the light pipe is constructed from polycarbonate.

3. The illumination assembly as set forth in claim 1 further comprising a plurality of illumination sources arranged in a ring in optical communication with the light pipe, the illumination sources being interconnected with a controller that is adapted to project illumination from the illumination sources so as to indicate a predetermined status of the reader in times between instances of illumination of the surface in which an image of the surface is acquired.

4. The illumination assembly as set forth in claim 3 wherein the illumination sources comprise multi-colored LEDs that selectively project each of a plurality of colors at predetermined times to indicate the predetermined status.

5. The illumination assembly as set forth in claim 4 wherein the controller is adapted to project at least two colors on each of adjacent sections of the light pipe simultaneously SO as to indicate the predetermined status.

6. The illumination assembly as set forth in claim 4 wherein the controller is adapted to cause the illumination sources to blink so as to indicate the predetermined status.

7. The illumination assembly as set forth in claim 1 further comprising a tapered diffuser located within an interior perimeter of the light pipe, the tapered diffuser being in optical communication with a reflector that receives light from a plurality of rearward-directed illumination sources that project in a direction opposite a direction toward which light from the chamfered end projects toward the surface.

8. The illumination assembly as set forth in claim 7 wherein the reflector includes a surface profile adapted to direct light to a remote region of the diffuser proximate the chamfered end.

9. The illumination assembly as set forth in claim 8 wherein the reflector includes a plurality of steps, at least one of the steps focusing a portion of the light toward the remote region.

10. The illumination assembly as set forth in claim 7 wherein the rearward-directed illumination sources project light through the diffuser onto the surface in a color that differs from a color projected from the chamfered end to illuminate the surface during image acquisition.

11. The illumination assembly as set forth in claim 10 further comprising a filter that allows the color from the diffuser to pass and that prevents the color from the chamfered end from being retransmitted by the diffuser.

12. The illumination assembly as set forth in claim 1 wherein at least one of the interior wall and the chamfered end includes a diffusive surface texture to reduce spotting by discrete illumination sources.

13. An illumination assembly for a mark reader comprising:

a light pipe in optical communication with a ring of illumination sources, the light pipe projecting light in a forward direction from a forward end of the light pipe; and

a tapered diffuser located within an interior perimeter of the light pipe, the tapered diffuser being in optical communication with a reflector that receives light from a plurality of rearward-directed illumination sources that project in a direction opposite the forward direction.

14. The illumination assembly as set forth in claim 13 wherein the reflector includes a surface profile adapted to direct light to a remote region of the diffuser proximate the chamfered end.

15. The illumination assembly as set forth in claim 14 wherein the reflector includes a plurality of steps, at least one of the steps focusing a portion of the light toward the remote region.

16. The illumination assembly as set forth in claim 13 wherein the rearward-directed illumination sources project light through the diffuser onto the surface in a color that differs from a color projected from the chamfered end to illuminate the surface during image acquisition.

17. The illumination assembly as set forth in claim 16 further comprising a filter that allows the color from the diffuser to pass and that prevents the color from the chamfered end from being retransmitted by the diffuser.

18. An illumination assembly for a mark reader comprising:

a light pipe that projects light from a ring of illumination sources onto a surface, the light pipe including a passage through which an imager views the surface having the mark; and

wherein the illumination sources are interconnected with a controller that is adapted to project illumination from the illumination sources so as to indicate a predetermined status of the reader in times between instances of illumination of the surface in which an image of the surface is acquired.

19. The illumination assembly as set forth in claim 18 wherein the illumination sources comprise multi-colored LEDs that selectively project each of a plurality of colors at predetermined times to indicate the predetermined status.

20. The illumination assembly as set forth in claim 19 wherein the controller is adapted to project at least two colors on each of adjacent sections of the light pipe simultaneously so as to indicate the predetermined status.

21. The illumination assembly as set forth in claim 20 wherein the controller is adapted to cause the illumination sources to blink so as to indicate the predetermined status.

22. The illumination assembly as set forth in claim 18 wherein a distal end of the light pipe includes a chamfered end and at least one of the chamfered end and an interior wall of the light pipe opposite the chamfered end includes a diffusive surface texture to reduce spotting by the ring illumination sources.

23. An illumination assembly for a mark reader disposed along an optical viewing axis comprising:

a light pipe defined by at least four adjacent sides including a first opposing pair of sides and a second opposing pair of sides, the light pipe including a chamfered edge at a distal end that directs light from a ring light source at the proximal end onto a surface as dark field; and

wherein a first spacing between the first opposing pair of the sides has a length different than length of a second spacing between the second opposing pair of the sides.

24. The illumination assembly as set forth in claim 23 wherein the light pipe includes a diffuser positioned within an interior defined by the light pipe that projects direct diffuse illumination.

25. The illumination assembly as set forth in claim 23 wherein at least one of the chamfered edge and an interior edge of the light pipe opposite the chamfered edge includes a diffusive surface thereon.

26. The illumination assembly as set forth in claim 25 further comprising an illumination controller adapted to project illumination in at least a first color from the ring so as to provide a first status signal at the chamfered edge.

27. The illumination assembly as set forth in claim 26 wherein the controller is adapted to project illumination in a second color, different than the first color from the ring so as to provide a second status signal at the chamfered edge.

28. The illumination assembly as set forth in claim 23 wherein the first opposing pair of sides and the second opposing pair of sides define collectively an approximate shape of an ellipse.

29. The illumination assembly as set forth in claim 23 wherein the first opposing pair of sides and the second opposing pair of sides collectively define a rectangle having corners between adjacent sides.