Image reader comprising CMOS based image sensor array

• US 8,733,660 B2
• Filed: 03/21/2011
• Issued: 05/27/2014
• 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: Wang, Ynjiun P., Havens, William H.
• Primary Examiner(s): Haupt, Kristy A
• Application Number:
  US13/052,768
• Publication Number:
  US 20110163166A1
• Time in Patent Office: 1,163 Days
• Field of Search: 235/462.45, 235/462.1, 235/462.11, 235/462.25, 235/462.41, 235/462.07
• US Class Current: 235/462.45
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/1439 including a method step for retrieval of the optical code
• CPC Class Codes: H04N 23/54 Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/63 by using electronic viewfinders
• CPC Class Codes: H04N 23/631 Graphical user interfaces [GUI] specially adapted for controlling image capture or setting capture parameters
• CPC Class Codes: H04N 23/667 Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 25/70 SSIS architectures; Circuits associated therewith
• CPC Class Codes: H04N 25/745 Circuitry for generating timing or clock signals
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors
• CPC Class Codes: H04N 25/7795 Circuitry for generating timing or clock signals
• CPC Class Codes: H04N 25/78 Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters

Abstract

The invention features an image reader and a corresponding method for capturing a sharp distortion free image of a target, such as a one or two-dimensional bar code. In one embodiment, the image reader comprises a two-dimensional CMOS based image sensor array, a timing module, an illumination module, and a control module. The time during which the target is illuminated is referred to as the illumination period. The capture of the image by the image sensor array is driven by the timing module that, in one embodiment, is able to simultaneously expose substantially all of the pixels in the array. The time during which the pixels are collectively activated to photo-convert incident light into charge defines the exposure period for the sensor array. In one embodiment, at least a portion of the exposure period occurs during the illumination period.

Claims

1. An image reader for collecting image data from a target, the image reader comprising:

a CMOS based image sensor array, the CMOS based image sensor array comprising a plurality of rows of pixels, each of the pixels of the CMOS based image sensor array being an active pixel comprising a pixel amplifier, a photosensitive region and an opaque shielded data storage region;

wherein the image reader includes a first user selectable mode of operation and a second user selectable mode of operation;

an illumination module configured to illuminate the target during an illumination period;

wherein the image reader is operative so that with the first user selectable mode of operation active, exposure of pixels of a plurality of different rows of said CMOS based image sensor array is initiated sequentially responsively to an initiation of a decode attempt; and

wherein the image reader is operative so that with the second user selectable mode of operation active, exposure of pixels of a plurality of different rows of said CMOS based image sensor array is initiated simultaneously responsively to an initiation of a decode attempt.

2. The image reader according to claim 1, wherein said illumination module for illuminating said target with said second user selectable mode of operation active overdrives a light source of said illumination module.

3. The image reader according to claim 1, wherein said illumination module comprises a light emitting diode.

4. The image reader according to claim 1, wherein with said second mode of operation active an exposure period of said image sensor array is shorter than said illumination period.

5. The image reader according to claim 1, wherein with said second mode of operation active said illumination period is shorter than an exposure period of said image sensor array.

6. The image reader according to claim 1, wherein with said second mode of operation active said illumination period commences before the start of an exposure period of said image sensor array and said illumination period ends before the end of an exposure period.

7. The image reader according to claim 1, wherein with said second mode of operation active said illumination period commences before the start of an exposure period and said illumination period ends after the end of said exposure period.

8. The image reader according to claim 1, wherein with said second mode of operation active said illumination period commences after the start of an exposure period of said image sensor array and said illumination period ends before the end of said exposure period.

9. The image reader according to claim 1, wherein with said second mode of operation active said illumination period commences after the start of an exposure period of said image sensor array and said illumination period ends after the end of said exposure period.

10. The image reader according to claim 1, wherein with said second mode of operation active said illumination period commences before the start of an exposure period of said image sensor array.

11. The image reader according to claim 1, wherein with said second mode of operation active said illumination period commences after the start of an exposure period of said image sensor array.

12. The image reader according to claim 1, wherein with said second mode of operation active said illumination period ends before the end of an exposure period of said image sensor array.

13. The image reader according to claim 1, wherein with said second mode of operation active said illumination period ends after the end of an exposure period of said image sensor array.

14. The image reader of claim 1, wherein the image reader includes a display that displays user selectable menu options corresponding to the first user selectable mode of operation and the second user selectable mode of operation.

15. The image reader of claim 1, wherein the image reader includes a housing encapsulating the image sensor array, and wherein the housing is hand held.

16. An image reader for collecting image data, the image reader comprising:

an integrated circuit including a CMOS based image sensor array, wherein the CMOS based image sensor array comprises pixels that include a photosensitive region, and an opaque shielded region;

an imaging lens directing and focusing reflected radiation;

global electronic shutter control circuitry, the global electronic shutter control circuitry configured to cause exposure of a plurality of pixels of the CMOS based image sensor array during an exposure period;

a light emitting diode;

wherein the image reader is configured so that light emitted by the light emitting diode is directed toward a target during an illumination period;

wherein the image reader is configured so that at least a portion of the illumination period occurs during the exposure period, and wherein said illumination period is less than a frame time of said image reader;

wherein the global electronic shutter control circuitry is capable of controlling said CMOS based image sensor array so that exposure of pixels of a plurality of different rows of said CMOS based image sensor array is initiated simultaneously, the global electronic shutter control circuitry controlling the image sensor array to simultaneously expose the pixels of a plurality of different rows of said CMOS based image sensor array;

wherein the image reader is further configured so that during each frame exposure period of successive first and second frame exposure periods in which the exposure of pixels of a plurality of different rows of the CMOS based image sensor array is initiated simultaneously, there is a corresponding illumination period in which visible light is directed by the light emitting diode toward the target;

wherein the image reader is operative for read out of image data from the CMOS based image sensor array; and

wherein the image reader is further operative for utilizing the image data for attempting to decode a bar code symbol.

17. The image reader of claim 16, wherein the light emitting diode includes a maximum current rating, and wherein the image reader is configured to overdrive the light emitting diode so that a current draw of the light emitting diode during the illumination period is above the maximum current rating.

18. The image reader of claim 17, wherein the image reader is configured to overdrive the light emitting diode so that a current draw of the light emitting diode during the illumination period is more than 150% above the maximum current rating.

19. The image reader of claim 16, wherein the image reader is configured so that during the illumination period the light emitting diode is driven with a strobed illumination control pulse that is pulsed at a strobing rate.

20. The image reader of claim 19, wherein said exposure period is shorter than said illumination period.

21. The image reader of claim 19, wherein the image reader is configured so that the image reader operates in a rolling shutter operating mode intermediate of the successive first and second frame exposure periods in which the exposure of a plurality of different rows of the CMOS based image sensor array is initiated simultaneously.

22. The image reader of claim 19, wherein the image reader is operative to attempt to decode a bar code symbol utilizing image data corresponding to each of the successive first and second frame exposure periods.

23. The image reader of claim 16, wherein the image reader is configured to operate with a frame time of less than 40 ms.

24. An image reader for collecting image data, the image reader comprising:

an integrated circuit including a CMOS based image sensor array, wherein the CMOS based image sensor array comprises pixels that include a photosensitive region, and an opaque shielded region;

an imaging lens directing and focusing reflected radiation;

global electronic shutter control circuitry, the global electronic shutter control circuitry configured to cause exposure of a plurality of pixels of the CMOS based image sensor array during an exposure period;

a light emitting diode;

wherein the image reader is configured so that light emitted by the light emitting diode is directed toward a target during an illumination period, and wherein the light emitting diode includes a maximum current rating;

wherein the image reader is configured to operate with a frame time of less than 40 ms, and is further configured so that at least a portion of the illumination period occurs during the exposure period, wherein said illumination period is less than a frame time of said image reader;

wherein the image reader is further configured to overdrive the light emitting diode so that a current draw of the light emitting diode during the illumination period is above the maximum current rating;

wherein the global electronic shutter control circuitry is capable of controlling said CMOS based image sensor array so that exposure of pixels of a plurality of different rows of said CMOS based image sensor array is initiated simultaneously, the global electronic shutter control circuitry controlling the image sensor array to simultaneously expose the pixels of a plurality of different rows of said CMOS based image sensor array;

wherein the image reader is operative for read out of image data from the CMOS based image sensor array; and

wherein the image reader is further operative for utilizing the image data for attempting to decode a bar code symbol.

25. The image reader of claim 24, wherein the image reader is configured to overdrive the light emitting diode so that a current draw of the light emitting diode during the illumination period is more than 200% above the maximum current rating.

26. The image reader of claim 24, wherein the image reader is configured to overdrive the light emitting diode so that a current draw of the light emitting diode during the illumination period is more than 500% above the maximum current rating.

27. The image reader of claim 24, wherein said illumination period commences before the start of said exposure period.

28. The image reader of claim 24, wherein said illumination period ends after the end of said exposure period.

29. The image reader of claim 24, wherein the image reader is configured to operate with a frame time of less than 30 ms.

30. The image reader of claim 24, wherein the image reader is configured to operate with a frame time of not more than 20 ms.

31. An image reader for collecting image data, the image reader comprising:

a light emitting diode for use in illuminating a target, wherein the image reader controls the light emitting diode to emit light during an illumination period, wherein the image reader is configured so that during the illumination period the light emitting diode is driven with a strobed illumination control pulse that is pulsed at a strobing rate;

an integrated circuit including a CMOS based image sensor array, wherein the CMOS based image sensor array comprises pixels that include a photosensitive region, and an opaque shielded region;

an imaging lens directing and focusing reflected radiation;

a global electronic shutter control circuitry, the global electronic shutter control circuitry configured to cause exposure of a plurality of pixels of the CMOS based image sensor array during an exposure period in which exposure of pixels of a plurality of different rows of said CMOS based image sensor array is initiated simultaneously, the global electronic shutter control circuitry controlling the image sensor array to simultaneously expose the pixels of a plurality of different rows of said CMOS based image sensor array;

wherein the image reader is configured so that at least a portion of the illumination period occurs during the exposure period, and wherein said illumination period is less than a frame time of said image reader;

wherein the image reader is operative for read out of image data from the CMOS based image sensor array; and

wherein the image reader is further operative for utilizing the image data for attempting to decode a bar code symbol.

32. The image reader of claim 31, wherein the strobing rate is more than 1,000 Hz.

33. The image reader of claim 31, wherein the strobing rate is between 1,000 Hz and 10,000 Hz.

34. The image reader of claim 31, wherein said exposure period is shorter than said illumination period.

35. The image reader of claim 31, wherein said illumination period commences before the start of said exposure period and said illumination period ends after the end of said exposure period.

36. The image reader of claim 31, wherein the light emitting diode includes a maximum current rating, and wherein the image reader is configured so that a current draw of the light emitting diode during the illumination period is above the maximum current rating.

37. The image reader of claim 31, wherein the image reader is configured to operate with a frame time of less than 40 ms.

38. The image reader of claim 31, wherein the strobing rate is more than 1,000 Hz, wherein the light emitting diode includes a maximum current rating, wherein the image reader is configured to overdrive the light emitting diode so that a current draw of the light emitting diode during the illumination period is more than 150% above the maximum current rating, and wherein the image reader is configured to operate with a frame time of less than 40 ms.