System and method to automatically focus an image reader

• US 7,611,060 B2
• Filed: 03/11/2005
• Issued: 11/03/2009
• Est. Priority Date: 03/11/2005
• Status: Active Grant

• Current Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Original Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Inventors: Havens, William H., Wang, Ynjiun
• Primary Examiner(s): Lee; Michael G
• Assistant Examiner(s): Haupt; Kristy A
• Application Number:
  US11/077,976
• Publication Number:
  US 20060202038A1
• Time in Patent Office: 1,698 Days
• Field of Search: 235/462.23, 235/462.11, 235/462.24, 235/462.32, 235/462.41
• US Class Current: 235/462.23
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10831 Arrangement of optical elements, e.g. lenses, mirrors, prisms optical elements per se G02B
• CPC Class Codes: H04N 23/689 Motion occurring during a rolling shutter mode

Abstract

The invention features a system and method to automatically focus an image reader using a single frame of image data. The method comprises exposing sequentially a plurality of rows of pixels in the image sensor. The method further comprising varying in incremental steps the focus of the image reader'"'"'s optical system from a first setting where a distinct image of objects located at a first distance from the image reader is formed on the image sensor to a second setting where a distinct image of objects located at a second distance from the image reader is formed on the image sensor. As part of the method, the varying of the focus of the optical system occurs during the exposure of the plurality of rows of pixels.

Claims

1. A bar code reading device for reading a bar code disposed on a target, said bar code reading device comprising:

an integrated circuit including an image sensor array, said image sensor array having a plurality of rows of pixels;

a hand held housing encapsulating said image sensor array;

an imaging lens capable of directing light reflected from a target onto said image sensor array, wherein said imaging lens is capable of first, second and third focus settings, wherein said bar code reading device when said imaging lens is at a first focus setting has a first best focus distance, wherein said bar code reading device when said imaging lens is at said second focus setting has a second best focus distance and wherein said bar code reading device when said imaging lens is at said third focus setting has a third best focus distance;

a trigger for initiating reading of said bar code;

wherein said bar code reading device is adapted so that responsively to said trigger being depressed, said bar code reading device captures a first frame of image data, a subsequent frame of image data, and a further subsequent frame of image data;

wherein said bar code reading device is further adapted so that further responsively to said trigger being depressed said bar code reading device changes a focus setting of said imaging lens in such manner that said first frame of image data represents light incident on said image sensor array when said lens setting is at said first lens focus setting, said subsequent frame of image data represents light incident on said image sensor array when said lens setting is at said second focus setting, and said further subsequent frame of image data represents light incident on said image sensor array when said lens setting is at said third focus setting; and

wherein said bar code reading device is further adapted so that further responsively to said trigger being depressed said bar code reading device subjects each of said first frame of image data, said subsequent frame of image data, and said further subsequent frame of image data to a decode attempt for attempting to decode said bar code.

2. The bar code reading device of claim 1, wherein said image sensor array is capable of global electronic shutter operations wherein each pixel of said plurality of rows of pixels can be exposed simultaneously.

3. The bar code reading device of claim 1, wherein said image sensor array is a CMOS image sensor array capable of global electronic shutter operations wherein each pixel of said plurality of rows of pixels can be exposed simultaneously.

4. The bar code reading device of claim 1, wherein said first frame of image data is a windowed frame of image data.

5. The bar code reading device of claim 1, wherein said first frame of image data, said subsequent frame of image data, and said further subsequent frame of image data are successively captured frames of image data.

6. A bar code reading device for reading a bar code disposed on a target, said bar code reading device comprising:

an integrated circuit including an image sensor array, said image sensor array having a plurality of rows of pixels;

a hand held housing encapsulating said image sensor array;

an imaging lens capable of directing light reflected from a target onto said image sensor array, wherein said imaging lens is capable of first and second focus settings, wherein said bar code reading device when said imaging lens is at a first focus setting has a first best focus distance, and wherein said bar code reading device when said imaging lens is at said second focus setting has a second best focus distance;

a trigger for initiating reading of said bar code;

wherein said bar code reading device is adapted so that responsively to said trigger being depressed, said bar code reading device captures a plurality of frames of image data for processing for determining a read attempt focus setting of said imaging lens;

wherein said bar code reading device is further adapted so that further responsively to said trigger being depressed said bar code reading device changes a focus setting of said imaging lens in such manner that at least one of said plurality of frames of image data represents light incident on said image sensor array when said lens setting is at said first lens focus setting, and at least one of said frames of image data represents light incident on said image sensor array when said lens setting is at said second focus setting;

wherein said bar code reading device is further adapted so that further responsively to said trigger being depressed said bar code reading device processes image data including image data of each of said plurality of frames for determining a focus setting of said imaging lens without decoding any frame of said plurality of frames of image data;

wherein responsively to said processing of image data said bar code reading device determines a read attempt focus setting for said imaging lens; and

wherein responsively to said determination, said bar code reading device attempts to decode said bar code utilizing a frame of image data representing light incident on said image sensor array when said focus setting is at said read attempt focus setting.

7. The bar code reading device of claim 6, wherein said read attempt focus setting is a focus setting other than said first focus setting or said second focus setting.

8. The bar code reading device of claim 6, wherein said bar code reading device in processing said image data assesses a flatness of a frame of image data.

9. The bar code reading device of claim 6, wherein said bar code reading device in processing said image data processes both of said first frame of image data and said subsequent frame of image data.

10. The bar code reading device of claim 6, wherein said bar code reading device in processing said image data assesses a flatness of each of said plurality of frames of image data.

11. The bar code reading device of claim 6, wherein said image sensor array is capable of global electronic shutter operations wherein each pixel of said plurality of rows of pixels can be exposed simultaneously.

12. The bar code reading device of claim 6, wherein said image sensor array is a CMOS image sensor array capable of global electronic shutter operations wherein each pixel of said plurality of rows of pixels can be exposed simultaneously.

13. The bar code reading device of claim 6, wherein each of said plurality of frames of image data for processing for determining a read attempt focus setting are windowed frames of image data having image data corresponding to less than a full frame of image data.

14. The bar code reading device of claim 6, wherein each of said plurality of frames are successively captured frames of image data.

15. The bar code reading device of claim 6, wherein said plurality of frames are windowed frames of image data, and wherein said frame of image data utilized by said bar code reading device when said bar code reading device attempts to decode said bar code symbol is a full frame of image data.

16. The bar code reading device of claim 6, wherein said frame of image data utilized for decoding said bar codes is a frame of image data captured subsequently to a time at which said plurality of frames are captured.

17. A bar code reading device for reading a bar code disposed on a target, said bar code reading device comprising:

an integrated circuit including a two dimensional complementary metal oxide semiconductor (CMOS) image sensor array, said image sensor array having pixels, wherein a plurality of said pixels each have a photosensitive region, an amplifier, and an opaque shielded data storage region;

a global electronic shutter control circuitry, the global electronic control circuitry configured to generate an exposure control timing pulse that is capable of causing simultaneous exposure of all or substantially all of said pixels of said CMOS image sensor array;

a hand held housing encapsulating said image sensor array;

an imaging lens capable of directing light reflected from a target onto said image sensor array, wherein said imaging lens is capable of more than one focus setting, the more than one focus setting including at least first and second focus settings, wherein said bar code reading device has a different best focus distance at each of said first and second focus settings;

a trigger for initiating reading of said bar code;

wherein said bar code reading device is adapted so that responsively to said trigger being depressed, said bar code reading device collects a plurality of frames of image data for subjecting to bar code decoding processing, wherein at least one of said plurality of frames of image data for subjecting to bar code decoding processing represents light incident on said image sensor array with said imaging lens at said first focus setting, and wherein at least one of said plurality of frames of image data for subjecting to bar code decoding processing represents light incident on said image sensor array with said imaging lens at said second focus setting.

18. The bar code reading device of claim 17, wherein said bar code reading device can be controlled to selectively address and read out from said image sensor array image data from a first plurality of said pixels independently of a second plurality of said pixels.

19. The bar code reading device of claim 17, wherein at least one of said plurality of frames of image data subject to bar code decoding processing is a windowed frame of image data.

20. The bar code reading device of claim 17, wherein each of said plurality of frames of image data subject to bar code decoding processing is a windowed frame of image data.

21. The bar code reading device of claim 17, wherein said more than one focus setting includes at least first, second and third focus settings, wherein at least one of said plurality of frames of image data for subjecting to bar code decoding processing represents light incident on said image sensor array with said imaging lens at said first focus setting, wherein at least one of said plurality of frames of image data for subjecting to bar code decoding processing represents light incident on said image sensor array with said imaging lens at said second focus setting, and wherein at least one of said plurality of frames of image data for subjecting to bar code decoding processing represents light incident on said image sensor array with said imaging lens at said third focus setting.