System and method for reading and comparing two-dimensional images

• US 6,385,352 B1
• Filed: 10/26/1994
• Issued: 05/07/2002
• Est. Priority Date: 10/26/1994
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Roustaei, Alexander
• Primary Examiner(s): Johns, Andrew W.
• Application Number:
  US08/329,257
• Time in Patent Office: 2,750 Days
• Field of Search: 235/472, 235/454, 235/456, 235/462.01, 235/462.08, 235/462.09, 235/462.1, 235/462.11, 235/462.2, 235/462.21, 235/462.41, 235/462.42, 382/115, 382/124, 382/312, 382/313, 382/317, 382/321, 382/324
• US Class Current: 382/324
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions
• CPC Class Codes: G06K 7/10811 Focalisation

Abstract

A system and method for reading a two-dimensional image, and for comparing the two-dimensional image to stored data representative of a known image. The optical scanning device comprises a sensor for capturing the two-dimensional image, which sensor includes an LED array for projecting an emitted light towards the two-dimensional image. The sensor also includes a lens disposed forward of the LED array for focussing the emitted light and thereby framing the two-dimensional image. The sensor further includes an optical assembly for focussing an ambient light reflected from the framed two-dimensional image. And the sensor includes a CMOS (or CCD) detector for detecting the focussed ambient light, the CMOS detector including a photodiode array for sensing the focussed ambient light and a processor for processing the ambient light to obtain an electrical image signal. The optical scanning device also compresses the electrical image signal. Finally, the optical scanning device decodes the compressed image signal to obtain image data representative of the two-dimensional image. The image data can be compared to the stored data to determine if the two-dimensional image matches the known image.

Claims

1. A method for reading a two-dimensional image located within a field of view having a plurality of edges bordering said field of view, said field of view being disposed within a field of ambient light, the method comprising capturing said two-dimensional image, including the following substeps:

projecting an emitted light towards said two-dimensional image by an LED array, said LED array including at least two LEDs,

first focussing said emitted light toward at least two of said plurality of edges of said field of view and thereby forming a stationary partial frame for locating said two-dimensional image within said field of view;

second focussing a reflected ambient light reflected from said framed two-dimensional image to obtain a focussed ambient light;

first detecting at least a portion of said focussed ambient light using a CMOS detector, said detecting step including sensing said ambient light to obtain a sensed two-dimensional image, and processing said sensed two-dimensional image to obtain an electrical image signal;

compressing said electrical image signal to obtain a compressed image signal; and

decoding said compressed image signal to obtain image data representative of said two-dimensional image.

2. The method recited in claim 1, further comprising converting the image data into a barcode symbol.

3. The method recited in claim 2, further comprising displaying the barcode symbol.

4. The method recited in claim 2, further comprising printing the barcode symbol.

5. The method recited in claim 1, further comprising contrasting the two-dimensional image using a coated glass.

6. The method recited in claim 1, further comprising amplifying the electrical image signal when a gain level of the electrical image signal falls below a threshold gain level.

7. The method recited in claim 1, further comprising calibrating a video dark level of the electrical image signal.

8. The method recited in claim 1 wherein the LED array includes a pair of LEDs, and wherein the first focussing step is forming a pair of vertical light beams from the emitted light using a pair of cylindrical lenses disposed forward of said pair of LEDs, each of said pair of vertical light beams corresponding to one of said pair of LEDs and being formed by one of said pair of cylindrical lenses.

9. The method recited in claim 8, further comprising separating the emitted light from each of the pair of LEDs by a barrier.

10. An optical scanning device for reading a two-dimensional image disposed within a field of view at least partially illuminated with an ambient light, said field of view having a plurality of edges corresponding to its borders, said optical scanning device comprising:

a sensor for capturing said two-dimensional image, said sensor including;

an LED array for projecting an emitted light towards said two-dimensional image, said LED array including a plurality of LEDs,

a lens disposed forward of said LED array for focussing said emitted light toward at least two of said plurality of edges of said field of view and for forming at least a partial stationary frame for locating said two-dimensional image within said field of view;

an optical assembly for focussing a reflected light reflected from said framed two-dimensional image to obtain a focussed reflected light, and

a CMOS detector for detecting at least a portion of said focussed reflected light, said CMOS detector including a photodiode array for sensing said focussed reflected light to obtain a sensed two-dimensional image, and a processor for processing said sensed two-dimensional image to obtain an electrical image signal;

a compressor for compressing said electrical image signal, said compressor employing a compression algorithm to obtain a compressed image signal; and

a decoder for decoding said compressed image signal to obtain image data representative of said two-dimensional image.

11. The optical scanning device recited in claim 10, further comprising a converter for converting the image data into a barcode symbol.

12. The optical scanning device recited in claim 11, further comprising a display unit for displaying the barcode symbol.

13. The optical scanning device recited in claim 11, further comprising a printer for printing the barcode symbol.

14. The optical scanning device recited in claim 10, further comprising a coated glass for contrasting the two-dimensional image.

15. The optical scanning device recited in claim 10, further comprising an automatic gain controller for amplifying the electrical image signal when a gain level of the electrical image signal falls below a threshold gain level.

16. The optical scanning device recited in claim 10, further comprising an automatic dark-level calibrator for calibrating a video dark level of the electrical image signal.

17. The optical scanning device recited in claim 10 wherein the optical assembly comprises fixed focus optics.

18. The optical scanning device recited in claim 10 wherein the LED array includes a pair of LEDs, and wherein the lens comprises a pair of cylindrical lenses, disposed forward of said pair of LEDs, for forming a pair of vertical light beams from the emitted light, each of said pair of pair of vertical light beams corresponding to one of said pair of LEDs and being formed by one of said pair of cylindrical lenses.

19. The optical scanning device recited in claim 18, further comprising a barrier for separating the respective emitted light produced by each of the pair of LEDs.

20. A method for comparing a new two-dimensional image located within a field of view having a plurality of edges bordering said field of view, said field of view being disposed within a field of ambient light, to stored data representative of a known two-dimensional image, comprising:

capturing said new two-dimensional image, including the following substeps;

projecting an emitted light towards said new two-dimensional image by an LED array, said LED array including a plurality of LEDs,

first focussing said emitted light toward at least two of said plurality of edges of said field of view to form at least two stationary lines for locating said two-dimensional image within said field of view;

second focussing a reflected light reflected from said framed two dimensional image to obtain a focussed reflected light;

detecting at least a portion of said focussed reflected light from said new two-dimensional image using a CMOS detector, including sensing said focussed reflected light to obtain a sensed new two-dimensional image, and processing said sensed new two-dimensional image to obtain a new electrical image signal;

compressing said new electrical image signal using a compression algorithm to obtain a compressed new image signal;

decoding said compressed new image signal to obtain new image data representative of said new two-dimensional image; and

comparing said new image data to said stored data to determine if said new image data substantially matches said stored data.

21. The method recited in claim 20, further comprising scanning the known two-dimensional image to obtain a scanned known two-dimensional image;

and decoding said scanned known two-dimensional image to obtain the stored data.

22. The method recited in claim 20 wherein the new two-dimensional image comprises a fingerprint and the known two-dimensional image comprises a barcode symbol.

23. The method recited in claim 22, further comprising contrasting the fingerprint using a coated glass.

24. The method recited in claim 20 wherein the first focussing step includes using a pair of cylindrical lenses, each lens having a holographic pattern disposed upon a surface of the lens.

25. The method recited in claim 20 wherein the LED array includes a pair of LEDs, and wherein the first focussing step includes forming a pair of vertical light beams from the emitted light using a pair of cylindrical lenses disposed forward of said pair of LEDs, each of said pair of vertical light beams corresponding to one of said pair of LEDs and being formed by one of said pair of cylindrical lenses.

26. The method recited in claim 20 wherein the second focussing step includes using a lens assembly having a fixed focus.

27. A system for comparing a new two-dimensional image disposed within a field of view at least partially illuminated with an ambient light, to stored data representative of a known two-dimensional image, wherein said field of view has a plurality of edges corresponding to its borders, the system comprising:

a sensor for capturing said new two-dimensional image, said sensor including;

an LED array for projecting an emitted light towards said two-dimensional image, said LED array including a plurality of LEDs,

a lens disposed forward of said LED array for focussing said emitted light toward said field of view and to form at least two stationary lines for locating said two-dimensional image within said field of view;

an optical assembly for focussing a reflected light reflected from said framed two-dimensional image to obtain a focussed reflected light, and

a CMOS detector for detecting at least a portion of said focussed reflected light, said CMOS detector including a photodiode array for sensing said focussed reflected light to obtain a sensed new two-dimensional image, and a processor for processing said sensed new two-dimensional image to obtain new electrical image data;

a compressor for compressing said new electrical image data to obtain a compressed new image date, said compressor employing a compression algorithm;

a decoder for decoding said compressed new image data to obtain new image data representative of said new two-dimensional image; and

a second processor for comparing said new image data to said stored data to determine if said new image data substantially matches said stored data.

28. The system recited in claim 27, further comprising a scanner for scanning the known two-dimensional image to obtain a scanned known two-dimensional image, and for decoding said scanned known two-dimensional image to obtain the stored data.

29. The system recited in claim 27 wherein the new two-dimensional image comprises a fingerprint and the known two-dimensional image comprises a barcode symbol.

30. The system recited in claim 29, further comprising a coated glass disposed forward of the CMOS detector for contrasting the fingerprint.

31. The system recited in claim 27 where the optical assembly has a fixed focus.

32. The system recited in claim 27 wherein the LED array includes a pair of LEDs, and wherein the lens comprises a pair of cylindrical lenses, disposed forward of said pair of LEDs, for forming a pair of vertical light beams from the emitted light, each of said pair of pair of vertical light beams corresponding to one of said pair of LEDs and being formed by one of said pair of cylindrical lenses.