Method and apparatus for non-contact reading of a relief pattern

• US 5,677,522 A
• Filed: 02/27/1995
• Issued: 10/14/1997
• Est. Priority Date: 07/21/1993
• Status: Expired due to Fees

• Current Assignee: Traceability Systems, Inc.
• Original Assignee: Sensis Corp (Saab AB)
• Inventors: Viggiano, Marc J., Rice, David A., Valovage, Edward M., Oschmann, Jacobus M.
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): LEE, MICHAEL GUNYOUNG
• Application Number:
  US08/395,420
• Time in Patent Office: 960 Days
• Field of Search: 235/454, 235/470, 235/471, 235/472, 235/462, 235/494, 382/218, 382/291, 382/292
• US Class Current: 235/454
• CPC Class Codes: G06K 19/06028 using bar codes
• CPC Class Codes: G06K 2019/06271 Relief-type marking
• CPC Class Codes: G06K 7/10594 Beam path
• CPC Class Codes: G06K 7/10861 sensing of data fields affixed to objects or articles, e.g. coded labels postal sorting B07C3/14, conveying articles B65G47/48

Abstract

An improved non-contact apparatus and method for reading a surface that has information encoded in a relief pattern thereon, includes an optical transmitter for projecting a line of light onto the relief pattern at a first angle to a normal of the surface; an optical receiver that views the projected line of light at a second angle to the normal of the surface and produces signal data that is representative of an image of the reflection thereon. The image viewed by the receiver has parallactic displacements of the line of illumination that occur at transitions between raised and recessed portions of the relief pattern. The signal data is culled such that only those pixels surrounding the line of light are selected. The culled signal data is then decoded into electrical signals which represent decoded information contained in the relief pattern. The optical receiver can be realized as a plurality of light sensors arranged in a linear, or a two dimensional array, together with suitable focusing optics. The optical transmitter can produce either a fan beam of light or sweep a spot of light across the surface. The optical transmitter, optical receiver, the culling, circuit and the decoding circuit contained within either a portable hand-held unit or a fixed mount unit.

Claims

1. A non-contact apparatus for reading a surface that has information encoded in a relief pattern thereon, the relief pattern having relatively raised and recessed portions and transitions therebetween, the recessed portions having bottom surfaces being aligned in a lengthwise direction, said apparatus comprising:

optical transmitter means for projecting a line of light onto the raised portions of the relief pattern and onto the bottom surfaces of the recessed portions of the relief pattern at a first angle to a normal of the surface;

optical receiver means for viewing said projected line of light on the relief pattern at a second angle to the normal of the surface and for producing signal data that is representative of an image of a reflection of said line of sight whereby said image includes a parallactic displacement of said projected line at a transition between a raised portion and the bottom surface of a recessed portion of the relief pattern therealong;

means for culling said signal data received by said receiver means such that only those pixels substantially constituting the image of the line of light are selected;

whereby said culling means culls within said line by detecting said pixels that exceeds an estimate of a level of a background information and

means for decoding said culled signal data into electrical signals which represent decoded information contained in the relief pattern.

2. The apparatus according to claim 1 further comprising analog processing means for amplifying and shifting the output level of said signal data.

3. The apparatus according to claim 2 further comprising means for digitizing said amplified and shifted signal data.

4. The apparatus according to claim 1 further comprising power management circuitry to enable battery powered operation of said apparatus.

5. The apparatus according to claim 1 wherein said optical receiver means includes an optical axis and an array disposed at a tilt angle φ

with respect to a plane that is normal to said optical axis.

6. The apparatus according to claim 1 further comprising a trigger switch utilized to initiate bar code scanning.

7. The apparatus according to claim 1 wherein said optical transmitter means produces a fan beam of light.

8. The apparatus according to claim 1 further comprising video black clamping means for adjusting a level of a video signal to match a range of an analog to digital converter.

9. The apparatus according to claim 8 wherein said video black clamping means includes a charge or discharge pulse across a capacitor.

10. The apparatus according to claim 8 wherein said video black clamping means includes a digital to analog converter.

11. The apparatus according to claim 1 wherein said optical transmitter means, said optical receiver means, said means for culling, and said means for decoding are contained in a fixed mount unit.

12. The apparatus according to claim 1 wherein said culling means selects pixels to be processed based on an adaptive threshold.

13. The apparatus according to claim 1 wherein said culling means selects pixels to be processed based on a local estimate of a background pixel intensity.

14. The apparatus according to claim 1 wherein said culling means selects pixels to be processed based on a ratio of an estimate of a pixel intensity of said image to an estimate of a local background pixel intensity.

15. A non-contact apparatus for reading a surface that has information encoded in a relief pattern thereon, the relief pattern having relatively raised and recessed portions and transitions therebetween, the recessed portions having bottom surfaces being aligned in a lengthwise direction, said apparatus comprising:

optical transmitter means for projecting a line of light onto the raised portions of the relief pattern and onto the bottom surfaces of the recessed portions of the relief pattern at a first angle to a normal of the surface;

optical receiver means for viewing said projected line of light on the relief pattern at a second angle to the normal of the surface and for producing signal data that is representative of an image of a reflection of said line of sight whereby said image includes a parallactic displacement of said projected line at a transition between a raised portion and the bottom surface of a recessed portion of the relief pattern therealong;

means for culling, said signal data received by said receiver means so that only those pixels substantially constituting the image of the line of light are selected;

means for decoding said culled signal data into electrical signals which represent decoded information contained in the relief pattern;

said optical transmitter means, said optical receiver means, said means for culling and said means for decoding are contained within a portable handheld unit; and

said optical transmitter means and said optical receiver means being at opposite ends of a hand grip of said hand held unit.

16. A non-contact apparatus for reading a surface that has information encoded in a relief pattern thereon, said relief pattern having a relatively raised portion and a relatively recessed portion and a transition therebetween, said recessed portion having a bottom surface aligned in a lengthwise direction, said apparatus comprising:

an optical transmitter effective for projecting a line of light onto said raised portion of said relief pattern and onto said bottom surface of said recessed portion of said relief pattern at a first angle to a normal of said surface;

an optical receiver effective for viewing said projected line of light on said relief pattern at a second angle to said normal of said surface;

said optical receiver producing a plurality of pixels representative of an image of a reflection of said line of sight wherein said image includes a parallactic displacement of said projected line at a transition between said raised portion and said bottom surface of said recessed portion;

a data culling circuit wherein only those pixels substantially constituting the image of the reflection of said line of light are selected, thereby producing culled signal data whereby said culling means culls within said line by detecting said pixels that exceeds an estimate of a level of background information; and

a decoder effective for decoding said culled signal data into electrical signals which represent decoded information contained in said relief pattern.

17. An apparatus according to claim 16, wherein said data culling circuit includes:

a shift register array;

first means for measuring a first sum of a first group of pixels in said shift register array;

second means for measuring a second sum of a second group of pixels of said shift register array;

third means for measuring a third sum of a third group of pixels of said shift register array;

means for averaging said first and second sums to produce an average sum;

means for comparing said second sum to said average sum to detect a peak.

18. A hand-held apparatus for reading a relief pattern on a surface, comprising:

a hand-held housing having first and second ends separated by a hand grip;

optical transmitter means, mounted in said first end, for projecting a line of light onto the surface;

optical receiver means, mounted in said second end, for receiving an image reflected from said surface;

said image including an image of said line of light;

conversion means for converting said image to a plurality of pixels;

culling means, mounted in said hand-held housing, for culling said plurality of pixels such that only those pixels substantially constituting said image of said line of light are selected; and

means for decoding said culled plurality of pixels into electrical signals representing decoded information contained in the relief pattern.