DUAL FOCUS IMAGING SYSTEM

• US 20090168117A1
• Filed: 12/28/2007
• Published: 07/02/2009
• Est. Priority Date: 12/28/2007
• Status: Active Grant

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: KEARNEY, SEAN P.
• Granted Patent: US 8,152,069 B2
• Time in Patent Office: Days
• US Class Current: 358/474
• CPC Class Codes: G06K 7/10702 Particularities of propagating elements, e.g. lenses, mirrors G06K7/10831 takes precedence

Abstract

A dual focus imaging scanner system and method for reading symbologies such as barcodes. The scanner system includes a light source producing two discrete wavelengths of light for illuminating a symbology target, a lens assembly for collecting a reflected image of the illuminated symbology target, which image preferably comprises the first and second wavelengths of light, and a color separation filter positioned to receive the combined reflected symbology target image from the lens assembly. The filter produces a first symbology image comprised of the first wavelength of light and a separate second symbology image comprised of the second wavelength of light. A first image sensor is positioned for receiving the first image and a second image sensor is positioned for receiving the second image. Preferably, the first and second sensors each have a different local point and focal range to scan near and far symbologies.

Claims

1. A dual focus optical imaging scanner system for reading symbologies comprising:

a first light source producing a first discrete wavelength of light for illuminating a symbology target;

a second light source producing a second discrete wavelength of light for illuminating the symbology target;

a lens assembly for collecting a combined reflected image of the illuminated symbology target that comprises the first and second wavelengths of light;

a color separation filter positioned to receive the combined reflected symbology target image from the lens assembly, the filter being operative to produce a first symbology image comprised of the first wavelength of light and a separate second symbology image comprised of the second wavelength of light;

a first image sensor for receiving the first image comprised of the first wavelength of light from the filter and having an associated first focal point; and

a second image sensor for receiving the second image comprised of the second wavelength of light from the filter and having an associated second focal point different than the first focal point;

wherein the optical imaging scanner system has two different focal points for capturing near and far symbology images.

2. The imaging scanner system of claim 1, wherein the color separation filter is a Dichroic filter.

3. The imaging scanner system of claim 1, wherein the first wavelength of light corresponds to blue light and the second wavelength of light corresponds to red light.

4. The imaging scanner system of claim 1, wherein the first image sensor has a first focal distance range and the second image sensor has a second focal distance range that overlaps the first local distance range.

5. The imaging scanner system of claim 1, wherein the color separation reflects the first image from the filter to the first image sensor and transmits the second image through the filter to the second image sensor.

6. The imaging scanner system of claim 5, wherein the second image sensor is positioned along an optical axis defined by the lens assembly and the first image sensor is positioned off of the optical axis.

7. The imaging scanner system of claim 5, further comprising imaging control circuitry associated with the first and second image sensors, wherein the control circuitry is operative to receive digitized images of the symbology target from the first and second image sensors.

8. The imaging scanner system of claim 1, further comprising control logic implemented by imaging control circuitry and being operative to select one of the first or second images for decoding the symbology target.

9. The imaging scanner system of claim 8, further comprising a microprocessor communicating with the imaging control circuitry for decoding the symbology target.

10. A dual focus optical imaging scanner system for reading symbologies comprising:

a dual wavelength light source producing discrete first and second wavelengths of light for illuminating a symbology target;

a fixed lens assembly for collecting a symbology image reflected from the illuminated target that comprises the first and second wavelengths of light, the lens assembly defining an optical axis; and

a color separation filter positioned along the optical axis to receive the symbology image from the lens assembly, the filter oriented at an angle to the optical axis and being operative to;

(1) reflect a symbology image comprised of the first wavelength of light from the filter to an off-axis image sensor, and to (2) transmit a separate symbology image comprised of the second wavelength of light through the filter to an on-axis image sensor;

wherein the off-axis and on-axis image sensors have different local lengths for capturing near and far symbologies.

11. The imaging scanner system of claim 10, wherein the off-axis image sensor has a substantially planar active light receiving surface aligned parallel to the optical axis.

12. The imaging scanner system of claim 11, wherein the on-axis image sensor has a substantially planar active light receiving surface aligned perpendicular to the optical axis.

13. The imaging scanner system of claim 10, wherein the color separation filter is a Dichroic filter.

14. The imaging scanner system of claim 10, wherein the on-axis image sensor has a first focal distance range and the off-axis image sensor has a second focal distance range that overlaps the first local distance range.

15. The imaging scanner system of claim 10, further comprising imaging control circuitry associated with the image sensors, wherein the control circuitry is operative to receive separate digitized images of the symbology produced by each of the image sensors and to select one of the images for decoding the symbology.

16. A method for resolving a symbology with an imaging scanner system comprising:

illuminating a symbology with two discrete wavelengths of light;

collecting an image of the illuminated symbology comprised of the two wavelengths of light;

separating the collected image into a first symbology image comprised of the first wavelength of light and a second symbology image comprised of the second wavelength of light;

receiving the first symbology image on a first image sensor having a first focal range;

receiving the second symbology image on a second image sensor having a second focal range different than the first focal range; and

resolving at least one of the first or second symbology images for decoding the symbology.

17. The method of claim 16, further comprising the steps of transmitting the first symbology image along an optical axis to the first image sensor and directing the second symbology image at an angle to the optical axis to the second image sensor.

18. The method of claim 16, wherein the first image sensor has a different local range than the second image sensor.

19. The method of claim 16, wherein the separating step is performed with a Dichroic color filter.

20. The method of claim 16, wherein the collecting step is performed with a lens assembly.

21. The method of claim 16, further comprising resolving both of the first and second symbology images.

22. The method of claim 16, further comprising decoding at least one of the first or second resolved symbology images by comparing the image to preprogrammed images stored in a computer-readable medium.