Hand held symbology reader illumination diffuser
View Patent ↗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.
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;
a diffuser concentrically aligned with the optical axis, having a first end surrounding the field of view proximate to the lens, and a second end surrounding the field of view proximate to the region of interest;
a dark field illuminating light pipe concentrically aligned with the optical axis and adjacent to the second end of diffuser; and
a dark field illuminator directing illumination into the dark field illuminating light pipe.
2. The apparatus according to claim 1 wherein the diffuser is removably attached.
3. The apparatus according to claim 1 further comprising an illuminator to provide selective illumination of the diffuser.
4. The apparatus according to claim 3 wherein the diffuser has a first color characteristic, the illuminator emits illumination having a color characteristic similar to the first color characteristic, and the dark field illuminator emits illumination having a second color characteristic.
5. The apparatus according to claim 4 wherein the first color characteristic is blue, and the second color characteristic is red.
6. The apparatus according to claim 4 wherein at least one color characteristic is infrared.
7. The apparatus of claim 3 wherein the illuminator further comprises a plurality of selectively actuated illuminators.
8. The apparatus according to claim 1 further comprising: a light absorbing filter applied to the diffuser and disposed between the diffuser and the region of interest.
9. 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 dark field illuminating light pipe having a first end and a second end, the second end surrounding the field of view proximate to the region of interest and configured to emit a dark field illumination toward the object at a low angle;
a diffuser aligned with the optical axis, the diffuser having a first end proximate to the lens, and a second end surrounding the field of view proximate to the object, the second end of the diffuser proximate to the dark field illuminating light pipe; and
an illuminator to provide illumination to the diffuser.
10. The apparatus according to claim 9 wherein the second end of the dark field illuminating light pipe comprises a chamfer configured to reflect the dark field illumination toward the object through an emitting surface on an inner side of the dark field illuminating light pipe.
11. The apparatus according to claim 9 and further comprising dark field illuminators at the first end of the dark field illuminating light pipe.
12. The apparatus according to claim 11 wherein the dark field illuminators and the illuminator are separately actuateable.
13. The apparatus according to claim 9 wherein the illuminator is a color-specific illuminator.
14. 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 diffuser aligned with the optical axis, having a first distal end proximate to the lens, and a second distal end proximate to the region of interest;
an illuminator for illuminating the diffuser comprises a plurality of illuminators;
a dark field illuminating light pipe aligned with the optical axis wherein the diffuser directs light toward the region of interest, through an interior perimeter of the dark field illuminating light pipe; and
a dark field illuminator directing illumination into the dark field illuminating light pipe.
15. The apparatus according to claim 14 wherein the dark field illuminator and the illuminator are separately actuateable.