Apparatus and method for reading a coded pattern

• US 6,688,525 B1
• Filed: 09/22/1999
• Issued: 02/10/2004
• Est. Priority Date: 09/22/1999
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Nelson, David J., Cobb, Joshua M.
• Primary Examiner(s): Lee, Michael G.
• Assistant Examiner(s): LE, UYEN CHAU N
• Application Number:
  US09/401,228
• Time in Patent Office: 1,602 Days
• Field of Search: 235/454, 235/462.1, 235/462.21, 235/462.22, 235/462.23, 235/462.45, 235/383, 235/385, 235/472, 235/462.11
• US Class Current: 235/462.21
• CPC Class Codes: G06K 2207/1011 Aiming
• CPC Class Codes: G06K 7/015 Aligning or centering of the sensing device with respect to the record carrier
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/1093 sensing, after transfer of the image of the data-field to an intermediate store, e.g. storage with cathode ray tube
• CPC Class Codes: G06K 7/1452 detecting bar code edges

Abstract

An apparatus and method for reading a coded pattern, symbol or indict such as a barcode. The apparatus and method improves captured resolution with a marker or fiducial input closed loop system. In the present invention, a pre-scan of the pattern, such as a barcode, is performed and fiducials of the barcode are identified. Calculations from these fiducial locations are used to determine the minimum field of view that will substantially capture the fiducials. In an embodiment of the invention, a variable magnification system of the apparatus can be actuated to this minimum field of view and a full resolution final image of the pattern is then captured.

Claims

1. A method for reading a coded pattern, the method comprising the steps of:

using a reader having a variable magnification imaging system set at a widest field of view to perform a pre-scan on the pattern, said pattern having a pre-coded marker arrangement thereon;

identifying the pre-coded marker arrangement on the pattern;

determining a minimum field of view that will substantially capture said pre-coded marker arrangement;

actuating the variable magnification imaging system to said minimum field of view; and

capturing a full resolution final image of the pattern.

2. A method according to claim 1, wherein said pattern is a barcode and said pre-coded marker arrangement comprises at least two corner fiducials of said barcode.

3. A method according to claim 1, wherein said pre-coded marker arrangement comprises fiducials which are made of a retroreflective material.

4. A method according to claim 1, wherein said pre-coded marker arrangement comprises fiducials which are made of a material which absorbs or emits at a different wavelength than that of the pattern.

5. A method according to claim 1, wherein said pre-coded marker arrangement comprises fiducials which are removably attached to said pattern.

6. A method according to claim 1, comprising the further step of centering said pattern prior to said step of capturing a full resolution final image of said pattern.

7. A method according to claim 1, comprising the further step of correcting a skew of said pattern prior to said step of capturing a full resolution final image of said pattern.

8. A method according to claim 1, wherein said step of performing a pre-scan of said pattern comprises performing pre-scan at a resolution which is less than a resolution at a final scan.

9. An apparatus for reading a coded pattern, the apparatus comprising:

an illumination source for illuminating a pattern within a field of view, said pattern having a pre-coded marker arrangement thereon;

a sensor onto which the pattern is imaged;

imaging optics which image the pattern onto said sensor at a first magnification; and

a processing unit adapted to receive a signal from said sensor indicative of the imaged pattern, perform a pre-scan of the imaged pattern with said imaging optics being set at a widest field of view, and locate said pre-coded marker arrangement on the pre-scanned pattern, said processing unit controlling said imaging optics to provide for a minimum field of view that will substantially capture said pre-coded marker arrangement and set a second magnification so as to perform a final scan on said imaged pattern at said second magnification.

10. An apparatus according to claim 9, wherein said pattern is a bar code and said pre-coded marker arrangement comprises fiducials located at least at first and second corners of said barcode.

11. An apparatus according to claim 9, wherein said pre-scan is at a low resolution and said final scan is at a resolution which is higher than said pre-scan resolution.

12. An apparatus according to claim 9, further comprising an actuator which is adapted to receive a signal from said processor and adjust a position of said sensor to correct a skew of said imaged pattern.

13. An apparatus according to claim 9, further comprising an actuator which is adapted to receive a signal from said processor and adjust a position of said sensor to center said imaged pattern.

14. An apparatus according to claim 9, further comprising an image rotating device for optically rotating said imaged pattern to correct a skew of said imaged pattern, said image rotating device being located along an optical axis of said apparatus.

15. An apparatus according to claim 9, further comprising an optical translation device for optically translating said imaged pattern to center the imaged pattern, said optical translation device being located along an optical axis of said apparatus.

16. An apparatus according to claim 9, wherein said pre-coded marker arrangement comprises fiducials which are made of a retroreflective material.

17. An apparatus according to claim 9, wherein said pre-coded marker arrangement comprises fiducials which are made of a material which absorbs or emits at a different wavelength than that of the pattern.

18. An apparatus according to claim 9, wherein said pre-coded marker arrangement comprises fiducials which are removably attached to said barcode.

19. An apparatus according to claim 9, further comprising an indicator which indicates a completion of said final scan to a user.

20. An apparatus according to claim 19, wherein said indicator is a visual indicator.