Imaging reader with target proximity sensor
An illuminator illuminates a symbol with a low level of illumination in a detection mode of operation to enable an imager to detect the symbol in a working range and in a field of view of the imager in an imaging reader, and also illuminates the symbol with a high level of illumination in a reading mode of operation to enable the imager to read the symbol.
1. A reader for electro-optically reading indicia in a working range of distances, comprising:
a) a housing having a presentation area;
b) an illuminator for illuminating the indicia with first level illumination light in a detection mode of operation, and for illuminating the indicia with second level illumination light in a reading mode of operation, wherein the light intensity of the first level illumination light is lower than the light intensity of the second level illumination light; and
c) a solid-state imager in the housing and including an array of image sensors for capturing light over a field of view from the indicia through the presentation area in the detection mode to detect whether the indicia are present in the working range and to change the illuminator to the reading mode when the indicia are in the working range, and for capturing light over the field of view from the indicia through the presentation area in the reading mode to read the indicia in the working range.
2. The reader of claim 1 , wherein the illuminator includes an illumination light source for emitting the first level illumination light, and an optical element for optically modifying the first level illumination light emitted by the illumination light source to only partially illuminate the field of view.
3. The reader of claim 2 , wherein the optical element only illuminates outer peripheral margins of the field of view.
4. The reader of claim 2 , wherein the illumination light source includes a light emitting diode (LED).
5. The reader of claim 4 , wherein the LED emits infrared light.
6. The reader of claim 2 , wherein the optical element includes an axicon.
7. The reader of claim 1 , wherein the illuminator includes a plurality of illumination light sources, each operative for emitting the illumination light, and an optical element for optically modifying the first level illumination light emitted by at least one of the illumination light sources to only partially illuminate the field of view.
8. The reader of claim 1 , and a controller for changing the illuminator between the detection mode and the reading mode, and wherein the imager is operatively connected to the controller to enable the controller to change the illuminator to the reading mode when the indicia are in the working range.
9. The reader of claim 8 , wherein the controller is operative for changing the illuminator to the detection mode after the indicia has been read.
10. The reader of claim 1 , wherein the presentation area includes a planar, light-transmissive window.
11. A reader for electro-optically reading indicia in a working range of distances, comprising:
a) housing means having a presentation area;
b) illuminator means for illuminating the indicia with first level illumination light in a detection mode of operation, and for illuminating the indicia with second level illumination light in a reading mode of operation, wherein the light intensity of the first level illumination light is lower than the light intensity of the second level illumination light; and
c) solid-state imager means in the housing means and including an array of image sensors for capturing light over a field of view from the indicia through the presentation area in the detection mode to detect whether the indicia are present in the working range and to change the illuminator means to the reading mode when the indicia are in the working range, and for capturing light over the field of view from the indicia through the presentation area in the reading mode to read the indicia in the working range.
12. A method of electro-optically reading indicia in a working range of distances, comprising the steps of:
a) illuminating the indicia with first level illumination light in a detection mode of operation, and illuminating the indicia with second level illumination light in a reading mode of operation, wherein the light intensity of the first level illumination light is lower than the light intensity of the second level illumination light; and
b) capturing light from the indicia in the detection mode over a field of view of a solid-state imager to detect whether the indicia are present in the working range and changing to the reading mode when the indicia are in the working range, and capturing light from the indicia over the field of view in the reading mode to read the indicia in the working range.
13. The method of claim 12 , wherein the illuminating step is performed by optically modifying the first level illumination light to only partially illuminate the field of view.
14. The method of claim 13 , wherein the illuminating step is performed by only illuminating outer peripheral margins of the field of view.
15. The method of claim 13 , wherein the optically modifying step is performed by an axicon.
16. The method of claim 12 , wherein the illuminating step is performed by a light emitting diode (LED).
17. The method of claim 12 , wherein the illuminating step is performed by emitting infrared light.
18. The method of claim 12 , wherein the illuminating step is performed by a plurality of illumination light sources, each operative for emitting the illumination light, and an optical element for optically modifying the first level illumination light emitted by at least one of the illumination light sources to only partially illuminate the field of view.
19. The method of claim 12 , and changing from the detection mode to the reading mode when the indicia are in the working range.
20. The method of claim 12 , and changing from the reading mode to the detection mode after the indicia has been read.