Symbology reader illumination system

• US 5,886,338 A
• Filed: 07/10/1997
• Issued: 03/23/1999
• Est. Priority Date: 03/21/1994
• Status: Expired due to Fees

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Bunce, Steven M., Arackellian, Kevork G., Aragon, Joel T.
• Primary Examiner(s): PITTS, HAROLD I
• Application Number:
  US08/891,299
• Time in Patent Office: 621 Days
• Field of Search: 235/472, 235/454
• US Class Current: 235/472.01
• 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 hand-held symbology reader for reading a symbology located within a target area on a target object substantially in an object plane, comprising:

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

a handle mounted to the head portion for grasping by the hand of a user;

a planar base mounted within the head portion;

at least three illuminating sources, each having a body portion with leads connected at a selected location on the planar base with a space between the body portion and the planar base, each of the illuminating sources when energized emitting a beam of light along a principal emission vector relative to its body portion, the leads of each of the body portions of the illuminating sources being bent to align its principal emission vector with a corresponding desired beam vector toward the object plane, the desired beam vectors being nonparallel and selected to produce the desired illumination pattern when the illuminating sources are energized;

an alignment board positioned adjacent to the planar base, between the planar base and the object plane, the alignment board having at least three alignment apertures therethrough, each corresponding to one of the illuminating sources, each alignment aperture being defined by a sidewall conforming substantially to the shape of the body portion of the corresponding illuminating source and being angularly oriented and offset from the selected location of the illuminating source on the planar base to engage the body portion and hold the semi-rigid leads in their bent state to maintain the alignment of the principal emission vector with the desired beam vector for the corresponding illuminating source; and

an area detector mounted within the head portion and positioned to receive light through the reader aperture from the illuminating sources after being first reflected from the target object.

2. The symbology reader of claim 1 wherein the illuminating sources are LEDs.

3. The symbology reader of claim 1 wherein the area detector has a pattern of sensitivity to light from the object plane and wherein the desired beam vectors are selected to produce an illumination pattern in the object plane inversely proportional to the pattern of sensitivity of the area detector.

4. The symbology reader of claim 1, further comprising a resilient layer positioned intermediated the alignment board and the planar base, the resilient layer engaging the illuminating sources to provide mechanical support.

5. The symbology reader of claim 1 wherein the alignment board includes a central aperture therethrough, the aperture providing a passageway for illuminating to reach the area detector.

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

a planar base;

an area detector having a predetermined sensitivity pattern corresponding to positions on the object plane;

at least three light sources, each of the light sources producing a beam of light having a predetermined beam pattern in the object plane, the light sources being oriented so that their beams are directed to illuminate at least three different regions of the target area in the object plane, with a different one of the beams illuminating each region, and to produce an illumination pattern in the object plane substantially inversely proportional to the sensitivity pattern of the area detector.

7. A method of constructing an illuminator for illuminating a target object in an object plane of a symbology reader having a plurality of light sources and an area detector, each of the light sources including a base portion and having a principal emission vector relative to its base portion along which the light source emits a beam of light having a known beam pattern, comprising:

determining a desired illumination pattern in the object plane;

selecting locations on a substantially planar base for the light sources;

selecting an orientation angle for each of the selected locations relative to the base based upon the known beam pattern of the light source to be located at the selected location and the desired illumination pattern in the object plane;

mounting to the base one of the light sources at each of the selected locations; and

after mounting each of the light sources, aligning the principal light emission vector of the light source substantially with the selected orientation angle for the selected location at which the light source is mounted by positioning an alignment board having a plurality of apertures therethrough, with each aperture corresponding to one of the light sources, between the planar base and the object plane in a fixed position, with each of the apertures being laterally offset from its corresponding light source such that a sidewall of the aperture engages and moves the corresponding base portion to angularly orient the principal light emission vector of the corresponding light source in alignment with the selected orientation angle.

8. A method of constructing an illuminator for illuminating a target object in an object plane of a symbology reader having a plurality of light sources and an area detector, each of the light sources including a source body portion and having a principal light emission vector relative to its source body portion along which the light source emits a beam of light having a known beam pattern, comprising:

determining a desired illumination pattern in the object plane;

selecting locations on a substantially planar base for the light sources;

selecting an orientation angle for each of the selected locations relative to the base based upon the known beam pattern of the light source to be located at the selected location and the desired illumination pattern in the object plane;

mounting to the base one of the light sources at each of the selected locations; and

after mounting each of the light sources, aligning the principal light emission vector of the light source substantially with the selected orientation angle for the selected location at which the light source is mounted by selectively adjusting the annular orientation of its source body portion relative to the base,

wherein determining the desired illumination pattern in the object plane comprises;

determining the sensitivity of the area detector to light directed toward the area detector from a plurality of locations in the object plane; and

determining, for each of the plurality of locations in the object plane, an illumination intensity inversely proportional to the sensitivity of the area detector to light from that location.

9. A method of reading a symbology in a target area of a target object in an object plane of a symbology reader having a plurality of light sources and an area detector, each of the light sources having a principal light emission vector along which the light source emits a beam of light having a known beam pattern, comprising:

determining a desired illumination pattern for the target area;

selecting mounting locations on the symbology reader for the light sources;

selecting an orientation angle for each of the selected mounting locations based upon the known beam pattern of the light source to be located at the selected mounting location and the desired illumination pattern for the target area;

mounting to the symbology reader one of the light sources at each of the selected mounting locations and at the selected orientation angle for the selected mounting location;

energizing each of the mounted light sources to produce the desired illumination pattern for the target area; and

detecting, with the area detector, light from the desired illumination pattern reflected from the target area toward the symbology reader, wherein determining the desired illumination pattern for the target area comprises;

determining the sensitivity of the area detector to light directed toward the area detector from a plurality of locations in the object plane; and

calculating for each of the plurality of locations in the object plane, an illumination intensity inversely proportional to the sensitivity of the area detector to light from the location in the object plane; and

wherein selecting the orientation angles for each of the mounting locations comprises selecting the orientation angle to produce the calculated illumination intensity.

10. The method of claim 9 wherein the step of energizing the illuminating light sources comprises providing electrical energy for a brief period of time during which the step of detecting occurs.