Method and apparatus for adjusting focus in a symbology reader
View Patent ↗A symbology reader has an adjustable focus mechanism that permits a plurality of focus settings by rotating a lens assembly threadedly engaged in the symbology reader housing. A focus adjustment collar having a plurality of key slots engage in a key when the cover to the symbology reader is attached. The rotation of the adjustment collar on the lens assembly is limited to not more than a single revolution through the use of cooperative stops that are fixed relation to the lens and housing respectively.
1. A symbology reader comprising:
a housing having an image sensor;
a lens assembly threadedly engaged to the housing, and optically aligned with the image sensor, the lens assembly including a lens;
a first rotation stop in a fixed position relative to the housing;
a second rotation stop in a fixed position relative to the lens, and cooperative with the first rotation stop to limit rotation of the lens to provide a range of focus settings;
a component forming a plurality of key slots in a fixed position relative to the lens; and
a key that engages in one of the plurality of key slots upon rotation of the lens to select a desired focus setting in the range of focus setting.
2. The symbology reader according to claim 1 wherein one of the plurality of key slots will result in the selection of a desired focus setting at an extreme of the range of focus settings.
3. The symbology reader according to claim 2 wherein another of the plurality of key slots will result in the selection of a desired focus setting at another extreme of the range of focus settings.
4. The symbology reader according to claim 1 wherein one of the plurality of key slots will result in the selection of a desired focus setting at a substantially central position in the range of focus settings.
5. The symbology reader according to claim 1 wherein the second rotation stop is cooperative with the first rotation stop to limit rotation of the lens to not more than one revolution.
6. The symbology reader according to claim 1 further comprising a third rotation stop that freely rotates about the lens assembly, and cooperative with the first rotation stop and the second rotation stop to limit rotation of the lens to not more than two revolutions.
7. The symbology reader according to claim 1 further comprising a removable transparent cover, the key positioned on the cover to engage in one of the plurality of key slots when attached to the housing.
8. The symbology reader according to claim 1 wherein the component comprises an adjustment collar fixedly attached to the lens assembly, the adjustment collar bearing the plurality of key slots and the second rotation stop.
9. The symbology reader according to claim 8 wherein the adjustment collar is fixedly attached to the lens assembly using an adhesive.
10. The symbology reader according to claim 8 wherein the adjustment collar is press-fit to the lens assembly.
11. The symbology reader according to claim 1 further comprising a color indicator adjacent to one of the plurality of key slots and visible through the cover when the cover is attached to the housing.
12. The symbology reader according to claim 1 wherein the range of focus settings is a working range substantially between 40 mm and 105 mm.
13. The reader of claim 1 wherein each of the key slots locks the lens to the housing when the key is received therein.
14. The reader of claim 1 wherein the component that forms the plurality of key slots is part of the lens assembly.
15. A method of adjusting the focus setting of an image-based symbology reader of the type that comprises a lens, an imaging sensor, and a housing, the lens threadedly engaged in the housing wherein rotation of the lens results in a change in a focus setting, the method comprising:
removing a cover to expose the lens and a component forming a plurality of key slots in fixed positions relative to the lens;
turning the lens to a rotational position within a range of focus settings limited by a pair of rotation stops, one of the pair of rotation stops fixed relative to the housing, the other of the pair of rotation stops fixed relative to the lens, the pair of rotation stops cooperative to limit rotation of the lens to be less than a full revolution; and
replacing the cover while engaging a key into one of the plurality of key slots.
16. The method of claim 14 wherein each of the key slots locks the lens to the housing when the key is received therein.
17. The method of claim 15 wherein the component that forms the plurality of key slots is part of the lens assembly.