CODE READING SYSTEM FOR IDENTIFICATION OF MOVING AND STATIONARY OBJECTS UTILIZING NONCOHERENT OPTICS

• US 3,700,907 A
• Filed: 07/20/1971
• Issued: 10/24/1972
• Est. Priority Date: 07/20/1971
• Status: Expired due to Term

• Current Assignee: John M. Richardson, Jon H. Myer, Thomas R O'Meara
• Original Assignee: John M. Richardson, Jon H. Myer, Thomas R O'Meara
• Inventors: Richardson, John M., Myer, Jon H., O'Meara, Thomas R.
• Primary Examiner(s): Schonberg, David
• Assistant Examiner(s): Stern, Ronald J.
• Application Number:
  US05/164,373
• Time in Patent Office: 462 Days
• Field of Search: 250/216R,22R,219D,219DD,237G 340/173LT,173LM 356/71 350/162SF,162ZP,321
• US Class Current: 250/550
• CPC Class Codes: B61L 25/041 using reflecting tags
• CPC Class Codes: B65G 47/493 by use of light responsive means
• CPC Class Codes: G01D 5/38 by diffraction gratings
• 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

For purposes of material handling and inventory management of railway cars, trucks, crates, packaged and unpackaged goods, and similar objects, markings, comprising a plurality or a composite of coded patterns, on such moving and stationary objects are used for their identification or identification of their contents. To permit such identification, an extended source of spatially incoherent light is modulated by passage through or reflection from the markings to provide input images of the coded patterns. The input images are projected through a pair of plates each having a Fresnel zone thereon for transformation of the input images into output signals corresponding to the optical Fourier transforms of the input images. Since the spatial positions and angular orientations of the output signals are dependent upon the spatial frequencies and orientations of the input images, the coded markings comprise a plurality of distinct patterns of different orientation and spatial frequency which can be correlated to a numerical identification system corresponding to information concerning the objects. The system is designed to operate as close to the geometrical optics limit as is practically feasible.

Claims

1. An optical system for identifying moving and stationary objects in accordance with an identification system utilizing a plurality of separate codes designating individual and different identification information relating to the objects comprising:

input image means secured to the objects and having identification means depicting one or more of the separate codes for transmission of the information contained therein;

an extended source of spatially incoherent light for illuminating said input image means for providing a spatially incoherent light signal modulated in accordance with the information contained in said input image means;

transformer means in the path of the modulated light signal, including a pair of Fresnel zone patterns having a construction such that said patterns negligibly diffract the modulated light signal, for producing an output image which is the optical Fourier transform of said input image, said Fresnel zone patterns in combination being positioned so as to produce the optical Fourier transform of said input image as the modulated spatially incoherent light signal passes through said Fresnel zone patterns; and

detector apparatus placed in the optical path of the output image for selectively detecting the output image and for obtaining the information contained therein.

2. An optical system defined by claim 1 wherein said identification means comprises a plurality of predetermined patterns of light reflective and non-reflective means corresponding to the separate codes.

3. An optical system defined by claim 2 wherein each of said predetermined patterns of light reflective and non-reflective means comprises a graphic multiple parallel bar pattern having a predetermined fundamental spatial frequency and orientation representing a selected one of the separate codes of the identification system.

4. An optical system as in claim 1 wherein said identification means comprises a plurality of bar patterns graphically representing a plurality of alpha-numeric symbols and having a distinct and different angular orientation for each represented alpha-numeric symbol, said plurality of bar patterns being arranged in a sequentially detected linear array.

5. An optical system as in claim 1 wherein said identification means comprises a plurality of bar patterns graphically representing a plurality of alpha-numeric symbols, said bar patterns having a distinct and different angular orientation for each represented alpha-numeric symbol, and having a distinct and different spatial frequency defining the sequential position of the symbols in a parallel simultaneously detected array of said bar patterns.

6. The optical system defined by claim 1 wherein said detector apparatus comprises a plurality of photo-electric detectors situated in close proximity to said output plane.

7. In an optical system for identifying moving and stationary objects having reflective markers arranged thereon in a predetermined manner representing identification information relating to the objects, an optical reader comprising:

means for illuminating said reflective markers to project spatially incoherent electromagnetic wave energy signal of said markers by reflection;

means in the path of the projected signals including a pair of adjacently placed Fresnel zone patterns through which the signal are projected, said Fresnel zone patterns having a construction so as to negligibly diffract the projected signals and being spaced from one another to develop output signals of the optical Fourier transforms of each of said reflective markers by optically transforming the projected signals as the projected signals pass through said Fresnel zone patterns; and

means for detecting each of the output signals corresponding to the optical Fourier transforms to provide further signals representing the identify of the objects.

8. The apparatus defined by claim 7 wherein said reflective markers are provided with reflective and non-reflective areas arranged in a graphic multiple parallel bar pattern the fundamental spatial frequency and orientation of which are representative of a particular unit in a coding scheme identifying the objects.

9. An optical system for identifying moving and stationary objects comprising:

input image means secured to said objects and containing information identifying said objects;

an extended source of spatially incoherent light for illuminating said input image means for providing light signals of spatially incoherent light modulated in accordance with the information contained in said input image means;

transformer means including a pair of Fresnel zone patterns positioned in the path of the modulated, spatially incoherent light signals, said Fresnel zone patterns in combination being positioned so as to produce optical signals of the individual sine and cosine optical Fourier transforms of the input images upon passage of the modulated signals through said Fresnel zone patterns, said transformer means focusing the optical signals in an output plane and said Fresnel zone patterns having a focal length extending beyond the output plane at a distance sufficient to enable detection of the optical signals; and

a detector apparatus positioned at the output plane for receiving and detecting the optical signals and for recognizing the information contained in said input image means.

10. An optical system as in claim 9 wherein said input image means comprises a plurality of bar patterns, each of said bar patterns comprising a plurality of light reflective and non-reflective bars in parallel orientation and of equal width, the orientation of each of said bar patterns having an angular inclination and the width of said bars of each of said bar patterns having a width dimension in accordance with a coding system conforming to the information identifying the objects, whereby the spatially incoherent light signals are modulated in accordance with the specific orientation and spatial frequency of said bar patterns, for transformation by said transformer means into the optical signals comprising conjugate loci in the output plane centered about the axis thereof at distances from and angular dispositions about the axis conforming to the input image configuration.