Hand Held Symbology Reader Illumination Diffuser

• US 20100020539A1
• Filed: 10/05/2009
• Published: 01/28/2010
• Est. Priority Date: 12/16/2004
• Status: Active Grant

• Current Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Original Assignee: Cognex Technology & Investment Corporation (Cognex Corporation)
• Inventors: Nunnink, Laurens
• Granted Patent: US 8,286,878 B2
• Time in Patent Office: Days
• US Class Current: 362/235
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10742 including a diffuser for diffusing the light from the light source to create substantially uniform illumination of the target record carrier
• CPC Class Codes: G06K 7/10831 Arrangement of optical elements, e.g. lenses, mirrors, prisms optical elements per se G02B
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners

Abstract

A hand held industrial identification symbol reader projects diffuse illumination onto a region of interest to produce high contrast images of symbols. The diffuse illumination is particularly well suited for producing images of symbols that are marked directly on objects. The diffuse illumination is created through the use of an optically translucent diffuser having a generally tapered shape that distributes diffuse illumination throughout the field of view of the reader. The diffuse illumination can be supplemented with dark field illumination using selectively actuated illumination sources.

Claims

1. An apparatus for imaging a symbol on an object, the apparatus comprising:

a hand held portable imaging system having an imager;

a lens disposed between the imager and a region of interest, the region of interest being the intended position of the symbol on the object, the lens and imager defining a field of view and an optical axis;

an illuminator adjacent to the lens, directing illumination towards the region of interest; and

a tapered translucent diffuser concentrically aligned with the optical axis, having a first distal end surrounding the field of view proximate to the lens, and a second distal end surrounding the field of view proximate to the region of interest.

2. The apparatus according to claim 1 wherein the tapered translucent diffuser is composed of polymethyl methacrylate.

3. The apparatus according to claim 2 wherein the tapered translucent diffuser is fabricated in an injection molding process.

4. The apparatus according to claim 1 wherein the tapered translucent diffuser has a conical shape.

5. The apparatus according to claim 1 wherein the tapered translucent diffuser has a cylindrical shape.

6-18. -18. (canceled)

19. An apparatus for imaging a symbol on an object, the apparatus comprising:

a hand-held portable imaging system having an imager;

a lens disposed between the imager and a region of interest, the region of interest being the intended position of the symbol on the object, the lens and imager defining a field of view and an optical axis;

a first illuminator adjacent to the lens, directing illumination towards the region of interest;

a semi-reflecting mirror disposed in front of the lens aligned with the optical axis configured to direct at least a portion of illumination reflected from the region of interest into the lens;

a second illuminator directing illumination at the semi-reflecting mirror so that at least a portion of the illumination from the second illuminator is directed towards the region of interest;

a first diffuser disposed between the second illuminator and the semi-reflecting mirror; and

a tapered translucent diffuser concentrically aligned with the optical axis, having a first distal end surrounding the field of view proximate to the lens, and a second distal end surrounding the field of view proximate to the region of interest.

20. The apparatus according to claim 19 wherein the first illuminator has a first intensity, and the second illuminator has a second intensity, so as to configure the apparatus to produce a uniform distribution of illumination over the field of view at the region of interest.