Symbology reader illumination system

• US 5,504,367 A
• Filed: 03/21/1994
• Issued: 04/02/1996
• Est. Priority Date: 03/21/1994
• Status: Expired due to Term

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec Corporation (Honeywell International Inc.)
• Inventors: Bunce, Steven M., Arackellian, Kevork G., Aragon, Joel T.
• Primary Examiner(s): PITTS, HAROLD I
• Application Number:
  US08/215,853
• Time in Patent Office: 743 Days
• Field of Search: 235/472, 235/462
• US Class Current: 235/462.42
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources

Abstract

A symbology reader employing an area detector and LEDs mounted at various angular orientations on a printed circuit board for illuminating a target object in an object plane. Each of the LEDs is oriented according to a desired beam vector to illuminate a particular area of the object plane so that the sum of the beams produces a desired illumination pattern. In one embodiment, the illumination pattern is selected to be inversely proportional to the sensitivity of the area detector to provide an even response over an entire image area. The individual LEDs are angularly aligned by an alignment board having an alignment aperture for each LED. The LEDs are mounted onto the printed circuit board with their body portions spaced apart from the board and supported by semi-rigid wire leads soldered to the board. Each of the alignment holes of the alignment board is laterally offset slightly from the mounting position of the LED. The LEDs are angularly aligned by moving the alignment board toward the printed circuit board and engaging sidewalls of the alignment holes with the LED body portions to deflect the LEDs toward a desired angular orientation. When the alignment board reaches a selected distance from the printed circuit board with the LEDs deflected to their desired orientation, the alignment board is fixed in place to hold the LEDs in this orientation.

Claims

1. A symbology reader for reading a symbology located within a target area on a target object substantially in an object plane, comprising:

a housing having a reader aperture providing a passageway for light into and out of the housing;

a base mounted within the housing;

at least three illuminating sources mounted to the base for producing light to illuminate the target area, each of the illuminating sources having a body portion, each of the illuminating sources when energized emitting a beam of light along a principal emission vector relative to its body portion, the body portion being oriented to align the principal emission vector with a corresponding desired beam vector toward the object plane, the desired beam vectors being non-parallel and selected to produce the desired illumination pattern when the at least three illuminating sources are energized which simultaneously illuminate the entire symbology within the target area, the desired beam vectors being selected to illuminate at least three different regions of the symbology with at least one illuminating source illuminating each of the regions; and

a detector assembly mounted within the housing and positioned to receive light through the reader aperture from the illuminating sources after being first reflected from the symbology within the target object and wherein the detector assembly has a pattern of sensitivity to light from the object plane wherein the principal emission vectors of the at least three illuminating sources are aligned such that the desired illumination pattern in the object plane is inversely proportional to the pattern of sensitivity of the detector assembly.

3. The symbology reader of claim 1 wherein the detector assembly includes a detector array and imaging optics.

4. The symbology reader of claim 3, further including:

an alignment board mounted within the housing in a fixed position and at a selected distance from the base, between the base and the target object, the alignment board having at least three alignment apertures therethrough, each corresponding to one of the at least three illuminating sources, each of the alignment apertures being defined by a sidewall engaging a corresponding one of the body portions to hold the engaged body portion such that the corresponding principal emission vector is aligned to the corresponding desired beam vector.

5. The symbology reader of claim 4 wherein the alignment board includes a central aperture therethrough, the aperture providing a passageway for light to reach the detector assembly.

6. The symbology reader of claim 5, further comprising a plurality of spacer nuts intermediate the alignment board and the planar base for holding the alignment board at the selected distance from the planar base.

7. The symbology reader of claim 5, further comprising a resilient layer positioned intermediate the alignment board and the base, the resilient layer engaging the illuminating sources to provide mechanical support therefor.

2. The symbology reader of claim wherein the illuminating sources are LEDs.

8. A symbology reader for reading a symbology located on a target object substantially in an object plane, the target area being larger than the symbology, comprising:

a base;

at least three simultaneously energizable, illuminating sources mounted to the base for producing light to illuminate the target area, each of the illuminating sources when energized emitting a beam of light along a principal emission vector relative to the base, the principal emission vector being aligned to a corresponding desired beam vector toward the object plane, the desired beam vectors being non-parallel and selected to produce a desired illumination pattern when the at least three illuminating sources are energized which illuminate the entire target area, the desired beam vectors being selected to illuminate at least three different regions of the target area with at least one illuminating sources illuminating each of the regions; and

an area-type detector, fixedly positioned relative to the base and oriented to receive light from the illuminating sources after being first reflected from a region of the target object at least as large as the symbology the dectector has a pattern of sensitivity to light from the object plane and wherein the principal emission vectors of the at least three illuminating sources are aligned such that the desired illumination pattern in the object plane is inversely proportional to the pattern of sensitivity of the detector array.

9. The symbology reader of claim 8 wherein the illuminating sources are LEDs.

10. The symbology reader of claim 8, further including:

an alignment board mounted in a fixed position and at a selected distance from the base, between the base and the object plane, the alignment board having at least three alignment apertures therethrough, each corresponding to one of the at least three illuminating sources, each of the alignment apertures being defined by a sidewall engaging a body portion of a corresponding one of the illuminating sources to hold the engaged body portion such that the corresponding principal emission vector is aligned to the corresponding desired beam vector.

11. The symbology reader of claim 10, further comprising a resilient layer positioned intermediate the alignment board and the base, the resilient layer engaging the at least three illuminating sources to provide mechanical support therefor.

12. The symbology reader of claim 10 wherein the alignment board includes a central aperture therethrough, the aperture providing a passageway for reflected light to reach the detector.