Low profile illumination for direct part mark readers

• US 8,672,227 B2
• Filed: 10/08/2010
• Issued: 03/18/2014
• Est. Priority Date: 12/21/2004
• Status: Active Grant

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Inventors: Nunnink, Laurens
• Primary Examiner(s): Kim, Ahshik
• Application Number:
  US12/900,605
• Publication Number:
  US 20110024506A1
• Time in Patent Office: 1,257 Days
• Field of Search: 235/472.01, 235/462.25, 235/462.42, 235/462.43
• US Class Current: 235/472.01
• CPC Class Codes: G06K 7/10732 Light sources

Abstract

An industrial reader is provided with an image formation system that is particularly adapted to read bar codes and two-dimensional symbols marked directly on objects. The image formation system includes illumination sources and illumination transmissive components that produce a combination of bright field and dark field illumination.

Claims

1. An integrated optical transmitter for use in a direct part mark reader, the transmitter comprising:

a dark field illumination transmitter that changes the direction of light passing through the dark field illumination transmitter to project dark field illumination at an object, the dark field illumination transmitter including a window adapted to provide a transmission path for reflected illumination in an optical path along an optical axis of a sensor module; and

a plurality of bright field illumination transmitters adjacent to and separate from the dark field illumination transmitter, the bright field illumination transmitters adapted to project bright field illumination at the object, the bright field illumination transmitters being without a window and being offset from the optical axis.

2. The optical transmitter according to claim 1 wherein the bright field illumination transmitters comprise a molded or fabricated lens.

3. The optical transmitter according to claim 2 wherein the lens is adapted to modify the angle or orientation of the bright field illumination.

4. The optical transmitter according to claim 1 wherein the bright field illumination transmitters include optical properties applied to at least one of a front of the optical transmitter and both the front and a rear of the optical transmitter.

5. The optical transmitter according to claim 1 wherein the dark field illumination transmitter includes an angled distal tip, the angled distal tip adapted to cause internal reflection that projects the low-angle dark field illumination in the area directly in front of the reader.

6. The optical transmitter according to claim 1 further including at least one dark field illuminator and at least one bright field illuminator.

7. The optical transmitter according to claim 6 wherein the bright field illumination transmitters are juxtaposed with the dark field illumination transmitter so that when the dark field illumination transmitter is optically aligned with the at least one dark field illuminator, the bright field illumination transmitters are optically aligned with the at least one bright field illuminator and the at least one dark field illuminator is optically misaligned with the at least one bright field illuminator.

8. An identification mark reader comprising:

an illumination transmitter defining an inner lumen through which the image sensor views a subject;

an illumination module including a plurality of illuminators to provide light to the illumination transmitter; and

the illumination transmitter including at least a first light exiting surface and a second light exiting surface, the first light exiting surface being adapted to allow at least a portion of the light from within the illumination transmitter to pass through and out of the first light exiting surface to provide bright field illumination on the subject, and the second light exiting surface being adapted to allow at least a portion of the light to pass through and out of the second light exiting surface to provide dark field illumination on the subject.

9. The mark reader according to claim 8 wherein the illumination transmitter is adapted to allow a different portion of the light from within the illumination transmitter to pass through and out of the illumination transmitter not at the first light exiting surface, the different portion of the light providing bright field illumination.

10. The mark reader according to claim 8 wherein at least one of the first light exiting surface and the second light exiting surface is flat.

11. The mark reader according to claim 8 wherein at least one of the first light exiting surface and the second light exiting surface is angled.

12. The mark reader according to claim 8 wherein at least one of the first light exiting surface and the second light exiting surface is curved.

13. The mark reader according to claim 8 wherein at least one of the first light exiting surface and the second light exiting surface is diffusive.

14. The mark reader according to claim 8 wherein the first light exiting surface is separate from the second light exiting surface.

15. The mark reader according to claim 8 wherein the plurality of illuminators includes at least one dark field illuminator and at least one bright field illuminator.

16. The mark reader according to claim 15 wherein the at least one dark field illuminator and the at least one bright field illuminator are separately actuatable.