Method and apparatus for reading machine-readable symbols including color symbol elements

• US 6,375,075 B1
• Filed: 10/18/1999
• Issued: 04/23/2002
• Est. Priority Date: 10/18/1999
• Status: Expired due to Fees

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Penn, Richard Steward, Ackley, H. Sprague
• Primary Examiner(s): Lee, Michael G.
• Assistant Examiner(s): TRAIL, ALLYSON NEEL
• Application Number:
  US09/419,534
• Time in Patent Office: 918 Days
• Field of Search: 235/462.04, 235/462.35, 235/469, 235/462.45, 235/468
• US Class Current: 235/462.04
• CPC Class Codes: G06K 7/10702 Particularities of propagating elements, e.g. lenses, mirrors G06K7/10831 takes precedence
• CPC Class Codes: G06K 7/10831 Arrangement of optical elements, e.g. lenses, mirrors, prisms optical elements per se G02B
• CPC Class Codes: G06K 7/12 using a selected wavelength, e.g. to sense red marks and ignore blue marks

Abstract

A symbol reader employs an optical element having first and second optical axes positioned to image a same portion of a color coded symbol onto two different portions of an image sensor. The reader includes one or more filters to remove different color portions of the light reflected from the symbol to create color separations at the image sensor. Thus, the image sensor detects different intensities of light, corresponding to different color states. A comparator, such as a microprocessor, programmed general purposed computer, or digital logic circuit, can determine the position and color of the various symbol elements based on image data produced by the image sensors, and decode the color coded symbol.

Claims

1. A symbol reader to read machine-readable symbols having more than two different colors, the symbol reader comprising:

a first optical lens having a first optical axis, the first optical lens positionable to image at least a first portion of a symbol at a first time;

a second optical lens having a second optical axis, different from the first optical axis, the second optical lens positionable to image at least the first portion of the symbol at the first time;

an image sensor having at least a first portion aligned with the first optical axis and a second portion aligned with the second optical axis;

a first color filter positioned along the first optical axis before the image sensor to substantially remove a respective color component from light reflected from the at least first portion of the symbol before the light reaches the image sensor; and

a second color filter positioned along the second optical axis before the image sensor to substantially remove a respective color component from light reflected from the at least first portion of the symbol before the light reaches the image sensor.

2. The symbol reader of claim 1, further comprising:

a comparator coupled to receive image data from the first portion of the image sensor and the second portion of the image sensor.

3. The symbol reader of claim 1, further comprising:

a comparator coupled to the image sensor to receive image data corresponding to light passing through the first color filter and image data corresponding to light passing through the second color filter.

4. A symbol reader to read machine-readable symbols having more than two different colors, comprising:

a first optical lens having a first field of view and a first image field;

a second optical lens having a second field of view and a second image field, the second field of view coincident with the first field of view and the second image field different from the first image field;

an image sensor having at least a first portion and a second portion, the first portion aligned with the first image field and the second portion aligned with the second image field;

a first color filter positioned before the image sensor to remove a first color component of light in the first image field; and

a second color filter positioned before the image sensor to remove a second color component of light in the second image field.

5. The symbol reader of claim 4 wherein the image sensor comprises a first linear charge coupled device and a second linear charge coupled device.

6. The symbol reader of claim 4 wherein the first and the second optical lenses comprises a number of corresponding surfaces formed on a single optical component.

7. The symbol reader of claim 4, further comprising:

a processor coupled to receive image data from the first portion of the image sensor and the second portion of the image sensor and programmed to compare the image data from the first and second portions of the image sensor to identify respective colors.

8. A reader to read color symbols, comprising:

an optical element having at least a first optical axis and a second optical axis;

an image sensor having a first portion positioned along the first optical axis and a second portion position along the second optical axis;

a first color filter positioned along the first optical axis to substantially remove a first color of light; and

a second color filter positioned along the second optical axis to substantially remove a second color of light.

9. The reader of claim 8 wherein the optical element includes a first lens and a second lens.

10. The reader of claim 8 wherein the optical element includes a first reflector and a second reflector.

11. The reader of claim 8 wherein the optical element includes a first aperture and a second aperture.

12. The reader of claim 8 wherein the image sensor includes a two-dimensional charge coupled device logically partitioned into the first and the second portions.

13. The reader of claim 8 wherein the first portion of the image sensor includes a first linear charge coupled device and the second portion of the image sensor includes a second linear charge coupled device.

14. The reader of claim 8 wherein the first color filter is positioned between the optical element and the image sensor.

15. The reader of claim 8 wherein the first color filter comprises an optical coating on the optical element.

16. The reader of claim 8 wherein the optical element has a third optical axis and a fourth optical axis, and further comprising:

a third color filter positioned along the third optical axis to substantially remove a third color of light different from the first and the second colors of light.

17. The reader of claim 8, further comprising:

a processor coupled to receive image data from the first portion of the image sensor corresponding to symbol elements other than symbol elements of the first color, and coupled to receive image data from the second portion of the image sensor corresponding to symbol elements including symbol elements of the first color.

18. A reader to read machine-readable symbols, comprising:

a light sensing means having at least a first portion and a second portion for sensing a first color of light reflected from at least a first portion of a symbol and a second color of light reflected from the at least first portion of the symbol, respectively;

optical means for focusing an image of the at least first portion of the symbol onto each of the first portion and the second portion of the light sensing means at a first time;

optical filtering means for substantially optically removing a first color from the image focused on the first portion of the light sensing means without removing the first color from the image focused on the second portion of the light sensing means; and

comparison means for comparing image data from the first portion of the light sensing means with image data from at least the second portion of the light sensing means to identify at least three colors in the symbol.

19. The reader of claim 18 wherein the optical means includes a first lens and a second lens.

20. The reader of claim 18 wherein the light sensing means includes a first linear light sensor array and a second linear light sensor array.

21. The reader of claim 18 wherein the light sensing means includes a two-dimensional light sensor array.

22. A method of operating a reader to read machine-readable symbols, comprising:

directing a first image of at least a first portion of a color machine-readable symbol along a first optical path at a first time;

directing a second image of the at least first portion of the color machine-readable symbol along a second optical path at the first time;

filtering a first color from the first image at the first time;

filtering a second color from the second image at the first time;

converting the filtered first image into a first set of image data;

converting the second image into a second set of image data; and

identifying colors in the color machine-readable symbol based on the first and the second sets of image data.

23. The method of claim 22, further comprising:

directing a third image of at least a first portion of the color machine-readable symbol along a third optical path at the first time;

converting the filtered third image into a third set of image data; and

identifying an additional color in the color machine-readable symbol based on the third set of image data.

24. The method of claim 22 wherein identifying colors in the color machine-readable symbol includes comparing the first set of image data with the second set of image data.

25. The method of claim 22 wherein identifying colors in the color machine-readable symbol includes creating a digital representation in a computer readable memory overlaying the first set of image data and the second set of image data.