BAR CODE READERS HAVING MULTIFOLD MIRRORS

• US 20090026271A1
• Filed: 10/03/2008
• Published: 01/29/2009
• Est. Priority Date: 06/28/2007
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Drzymala, Mark, Barkan, Edward D.
• Granted Patent: US 8,505,824 B2
• Time in Patent Office: Days
• US Class Current: 235/462.420
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10782 Slot readers

Abstract

A multicamera imaging-based bar code reader 10 for imaging a target bar code 30 on a target object 32 features: a housing 20 supporting a plurality of transparent windows H, V and defining an interior region, an imaging system including a plurality of camera assemblies C1-C5 coupled to an image processing system, each camera assembly of the plurality of camera assemblies being positioned within the housing interior. Each camera assembly includes a sensor array. One or more light reflecting fold mirrors M1-M14 define a camera assembly field of view positioned with respect to said light source and the sensor array at locations along a light path to transmit light from light source to the field of view and transmit light that bounces from a target in the field of view back along said light path to the image capture sensor array.

Claims

1. A bar code reader for decoding a target bar code on a target object, the bar code reader comprising:

a housing supporting one or more transparent windows and defining an interior region, a target object being presented in relation to the housing for imaging a target bar code;

an imaging system comprising

a camera having an image capture sensor array positioned within the housing interior region for capturing an image of a bar code within a camera field of view;

a light source for the camera positioned in close proximity to the image capture sensor of said camera; and

one or more light reflecting fold mirrors positioned with respect to said light source and the sensor array for baffling light from the light source to a light source field of view and transmitting light that bounces from a target in the light source field of view back to the image capture sensor array; and

an image processing system comprising a processor having a stored program for identifying a bar code from images captured by the imaging system.

2. The bar code reader of claim 1 wherein the imaging system has multiple cameras and light sources wherein each camera includes at least one light source positioned in close proximity to an associated image capture sensor.

3. The bar code reader of claim 2 wherein each of the multiple cameras has an image capture sensor array and light source mounted to a common substrate.

4. The bar code reader of claim 1 wherein the light source comprises a light emitting diode that is turned on and off at controlled intervals by the processor.

5. The bar code reader of claim 1 wherein the sensor array gathers light from two or more light reflecting fold mirrors that sequentially transmit light from an object back to the camera.

6. The bar code reader of claim 1 wherein the light reflecting fold mirrors have generally planar light reflecting surfaces.

7. The bar code reader of claim 1 wherein the image capture sensor array has a length and width and wherein the one or more mirrors limit the light source field of view to less than a complete area of the sensor array.

8. The bar code reader of claim 7 wherein the processor evaluates less than an entire area of the image capture array to determine a presence of a bar code

9. The bar code reader of claim 1 wherein an in focus depth of field distance is centered about a zone immediately adjacent the housing window from which it exits the housing and extends a distance away from the housing less than a distance of light travel from the source to said housing.

10. The bar code reader of claim 1 wherein a distance between the light source and a last of said fold mirrors positioned closest to the transparent window from which light from the light source exits the housing is at least one half the distance from the light source to said transparent window along a light path of travel.

11. A bar code reader for decoding a target bar code on a target object, the bar code reader comprising:

a housing supporting one or more transparent windows and defining an interior region, a target object being presented in relation to the housing for imaging a target bar code;

an imaging system comprising;

a camera having an image capture sensor array positioned within the housing interior region for capturing an image of a bar code within a camera field of view;

a light source for the camera positioned in close proximity to the image capture sensor of said camera; and

one or more light reflecting fold mirrors positioned with respect to said light source and the sensor array for transmitting light from the light source to at least a portion of a sensor field of view and the one or more light reflecting fold mirrors vignette light that bounces from a target within a desired sensor array field of view back to the image capture sensor array; and

an image processing system comprising a processor having a stored program for identifying a bar code from images captured by the imaging system.

12. The bar code reader of claim 11 wherein the imaging system has multiple cameras and light sources wherein each camera includes at least one light source positioned in close proximity to an associated image capture sensor.

13. The bar code reader of claim 12 wherein each of the multiple cameras has an image capture sensor array and light source mounted to a common substrate.

14. The bar code reader of claim 11 wherein the light source comprises a light emitting diode that is turned on and off at controlled intervals by the processor.

15. The bar code reader of claim 11 wherein the sensor array gathers light from two or more light reflecting fold mirrors that sequentially transmit light from an object back to the camera.

16. The bar code reader of claim 11 wherein the light reflecting fold mirrors have generally planar light reflecting surfaces.

17. The bar code reader of claim 11 wherein the image capture sensor array has a length and width and wherein the one or more mirrors limit the sensor array field of view so that light from the source strikes less than a complete area of the sensor array.

18. The bar code reader of claim 17 wherein the processor evaluates less than an entire area of the image capture array to determine a presence of a bar code

19. The bar code reader of claim 11 wherein a distance between the light source and a last of said fold mirrors positioned closest to the transparent window from which light from the source exits the housing is at least one half the distance from the light source to said transparent window along a light path of travel.

20. A method for imaging a target bar code comprising:

providing a housing having one or more transparent windows that define a region for movement and/or positioning of an object having a bar code;

positioning a camera having a sensor array within the housing for imaging bar codes on objects outside the housing;

illuminating a region outside the housing by activating a light source in said housing positioned next to the sensor array of said camera and deflecting light from the light source off from one or more fold mirrors positioned between the source and the one or more transparent windows to baffle light emitted from the source from reaching an illumination field of view;

imaging a target object having a target bar code in a position within the illumination field of view; and

interpreting images from the camera to determine a bar code.

21. The method of claim 20 wherein there are multiple cameras and each camera has associated with it multiple mirrors defining multiple fields of view, one per camera.

22. The method of claim 20 wherein the light source is a light emitting diode and shielding is provided along a portion of the light path between the light emitting diode and a first of said two or more mirrors.

23. The method of claim 20 wherein the imaging is accomplished by the sensor array gathering light following a return path from the illumination field of view by bouncing off from the fold mirrors to the reach the sensor array.

24. The method of claim 20 wherein images are interpreted by an image processor and the image processor is calibrated by:

positioning a calibration object within the illumination field of view;

determining a subset of pixels of the sensor array that image the calibration object; and

subsequently decoding signals originating from the subset of pixels.

25. A method for imaging a target bar code comprising:

providing a housing having one or more transparent windows that define a region for movement and/or positioning of an object having a bar code;

positioning a camera having a sensor array within the housing for imaging bar codes on objects outside the housing;

illuminating a region outside the housing by activating a light source in said housing positioned next to the sensor array of said camera by reflecting light from the source off from one or more mirrors positioned between the source and the transparent windows to vignette a sensor field of view;

imaging a target object having a target bar code in a position within the camera field of view; and

interpreting images from the camera to determine a bar code.

26. The method of claim 25 wherein there are multiple cameras and each camera has associated with it multiple mirrors defining multiple fields of view, one per camera.

27. The method of claim 25 wherein the light source is a light emitting diode and shielding is provided along a portion of the light path between the light emitting diode and a first of said two or more mirrors.

28. The method of claim 25 wherein images are interpreted by an image processor and the image processor is calibrated by:

positioning a calibration object within the sensor field of view;

determining a subset of pixels of the sensor array that image the calibration object; and

subsequently decoding signals originating from the subset of pixels.

29. An imaging system for use in multi-camera imaging-based bar code reader having a housing supporting a plurality of transparent windows and defining an interior region, a target object being presented to the plurality of windows for imaging a target bar code on a target object, the imaging system comprising:

a plurality of camera assemblies coupled to an image processing system, each camera assembly of the plurality of camera assemblies being positioned within the housing interior position and defining a field of view which is different than a field of view of each other camera assembly of the plurality of camera assemblies, each camera assembly including a sensor array and a light source in close proximity to the sensor array on a common support;

a plurality of mirrors for transmitting light to a camera field of view of each of the camera assemblies and return light bouncing off a target object back to the sensor array of said camera assembly; and

one or more processors for evaluating images captured by said plurality of camera assemblies.

30. The system of claim 29 wherein illumination light from one or more of the camera assemblies bounces off three fold mirrors prior to exiting the housing through one of the transparent windows.

31. An imaging-based bar code reader for imaging a target bar code on a target object, the bar code reader comprising:

a housing supporting one or more transparent windows and defining an interior region, a target object being presented in relation to the housing for imaging a target bar code;

an imaging system comprising

camera means having an image capture sensor array positioned within the housing interior region for capturing an image of a bar code within a camera field of view;

light source means for the camera positioned in close proximity to the image capture sensor of said camera for emitting light; and

light reflecting means for defining a camera field of view including mirrors positioned with respect to said light source and the sensor array along a light path to transmit light from light source to the field of view and transmit light that bounces from a target in the field of view back along said light path to the image capture sensor array; and

image processing means for identifying a bar code from images captured by the imaging system.