Bar code readers having multifold mirrors

• US 8,505,824 B2
• Filed: 10/03/2008
• Issued: 08/13/2013
• 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.
• Primary Examiner(s): MARSHALL, CHRISTLE I
• Application Number:
  US12/245,111
• Publication Number:
  US 20090026271A1
• Time in Patent Office: 1,775 Days
• Field of Search: 23546201-473
• US Class Current: 235/462.17
• 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;

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

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;

wherein the camera field of view essentially matches the light source field of view; and

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.

2. The bar code reader of claim 1 wherein each of the multiple cameras has an image capture sensor array and light source mounted to a common substrate.

3. 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.

4. 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.

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

6. 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.

7. The bar code reader of claim 6 wherein the processor evaluates less than an entire area of the image capture array to determine a presence of a bar code.

8. 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.

9. 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 for 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 in close proximity 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 essentially only within the illumination field of view;

interpreting images from the camera to determine a bar code;

wherein there are multiple cameras and each camera has associated with it multiple mirrors defining a corresponding fields of view; and

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 one or more fold mirrors.

10. The method of claim 9 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.

11. The method of claim 9 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.