Method and apparatus for utilizing specular light to image low contrast symbols

• US 6,367,699 B2
• Filed: 09/17/1998
• Issued: 04/09/2002
• Est. Priority Date: 07/11/1996
• Status: Expired due to Term

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Ackley, H. Sprague
• Primary Examiner(s): Frech, Karl D.
• Application Number:
  US09/154,758
• Publication Number:
  US 20010019078A1
• Time in Patent Office: 1,300 Days
• Field of Search: 235/462.45, 235/462.49, 235/462.25, 235/462.29, 235/462.42
• US Class Current: 235/462.49
• CPC Class Codes: G06K 7/10584 Source control
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03

Abstract

An apparatus and method for imaging low contrast one and two-dimensional symbols are provided. A light source directs light onto a target that includes a low contrast symbol. An imaging element receives light reflected off of the target and creates an image of the target therefrom. A light level detector determines the intensity level of the light received by the imaging element, and when the intensity level exceeds a predetermined threshold, a controller causes the image data created by the imaging element to be stored in a data memory. In an embodiment of the invention, a light wand is provided with the light source and imaging element. The light wand is adapted to read low contrast bar code symbols disposed on a substrate material using specular light reflected from the bar code symbols by maintaining the light wand at an optimum angle with respect to the substrate material. A alignment tip may further be utilized with the light wand to ensure that the light wand is maintained at the optimum angle.

Claims

1. An apparatus for reading a low contrast symbol on a target, comprising:

a wand;

a light source disposed in said wand and positioned to illuminate the target when the wand is positioned in proximity to the target, whereby light from said light source is reflected from the target as specular light concentrated along a path;

an imaging element disposed in said wand and positioned to receive the specular light when said wand is in a predetermined orientation with respect to the target; and

means for determining whether an amount of light received by said imaging element exceeds a predetermined threshold indicative of receiving the specular light;

wherein said imaging element is adapted to provide a data signal from the specular light when said predetermined threshold is exceeded, whereby data from the low contrast symbol is encoded in the data signal when the low contrast symbol is illuminated by said light source and said wand is in the predetermined orientation.

2. The apparatus of claim 1, further comprising a processor coupled to said wand for processing image data of the low contrast symbol from the specular light.

3. The apparatus of claim 2, wherein said processor further comprises:

a memory; and

means for causing said image data created by said imaging means to be stored in said memory if said threshold determining means determines that said amount of light received by said imaging element exceeds said predetermined threshold.

4. The apparatus of claim 3, further comprising light amount determining means for determining said amount of light received by said imaging element.

5. The apparatus of claim 4, wherein said threshold determining means comprises program code for instructing a processor to compare said amount of light determined by said light amount determining means with said predetermined threshold.

6. The apparatus of claim 5, wherein said means for causing said image data to be stored in said memory comprises program code for instructing said processor to output a write signal to said memory if said comparison indicates that said amount of light determined by said light amount determining means exceeds said predetermined threshold.

7. The apparatus of claim 1, further comprising means for maintaining said wand in the predetermined orientation.

8. The apparatus of claim 7, wherein said orientation maintaining means further comprises an alignment tip coupled to a distal end portion of said wand, said alignment tip comprising a notched portion adapted to engage an edge of a substrate.

9. A method for imaging a low contrast symbol disposed on a substrate utilizing a light wand comprising a light source and an imaging element, said method comprising:

directing source light from said light source of said light wand onto said symbol, said source light reflecting off of said low contrast symbol as reflected light, said reflected light comprising a specular portion concentrated along a path;

orienting said light wand with respect to said substrate so that said imaging element receives light comprising predominantly said specular portion of said reflected light;

moving said light wand across said symbol;

determining whether an amount of said light received by said imaging element exceeds a predetermined threshold indicative of specular light; and

decoding data of said symbol from said specular portion of said light received by said imaging element.

10. The method of claim 9, further comprising the step of maintaining said light wand in a proper orientation with respect to said substrate.

11. The method of claim 9, further comprising the step of forming said low contrast symbol using a polarity opposite a corresponding polarity of diffuse light reflective symbols.

12. An apparatus for reading low contrast symbols disposed on a substrate, comprising:

a light source positioned to illuminate a low contrast symbol, whereby light from the light source is reflected from the low contrast symbol as specular light concentrated along a path;

an imaging element for receiving light reflected from said low contrast symbol, positioned to receive the specular light when said apparatus is in a predetermined orientation with respect to the low contrast symbol; and

a processor coupled to said imaging element for determining whether an amount of said light received by said imaging element exceeds a predetermined threshold indicative of receiving the specular light, whereby data from the low contrast symbol is encoded by said imaging element from the specular light when the low contrast symbol is illuminated by said light source and said apparatus is in the predetermined orientation.

13. The apparatus of claim 12, further comprising a wand adapted for manipulation by an operator, said wand further comprising said light source and said imaging element.

14. The apparatus of claim 12, further comprising means for maintaining said wand in the predetermined orientation.

15. The apparatus of claim 14, wherein said orientation maintaining means further comprises an alignment tip coupled to a distal end portion of said wand, said alignment tip comprising a notched portion adapted to engage an edge of a substrate.

16. The apparatus of claim 12, further comprising a processor coupled to said imaging element for discriminating between the specular light and diffuse light reflected from the low contrast symbol and to process image data of the low contrast symbol from the specular light.