Method and apparatus for measuring dimensions

• US 4,173,788 A
• Filed: 09/26/1977
• Issued: 11/06/1979
• Est. Priority Date: 09/27/1976
• Status: Expired due to Term

• Current Assignee: Atmospheric Sciences Incorporated
• Original Assignee: Atmospheric Sciences Incorporated
• Inventors: Laliotis, Theodore A.
• Primary Examiner(s): Wise, Edward J.
• Application Number:
  US05/836,615
• Time in Patent Office: 771 Days
• Field of Search: 364/560-564, 250/560, 250/223 R, 250/561, 250/224, 356/108, 356/156, 356/157, 356/158, 356/160, 356/161, 356/168, 356/163, 356/164, 358/107
• US Class Current: 356/625
• CPC Class Codes: G01B 11/043 for measuring length
• CPC Class Codes: G01B 11/105 using photoelectric detection means
• CPC Class Codes: G06T 2207/30108 Industrial image inspection
• CPC Class Codes: G06T 7/62 of area, perimeter, diameter or volume

Abstract

An array of photosensitive imaging sensors connected to a digital computer is utilized to measure selected dimensions of objects upon which the photosensitive array is focused. Two sets of information in the form of analog signals generated by the photosensitive array, both with and without an object in view, are converted to digital form and stored in a memory. The two sets of information contained in the memory are compared to thereby create digital signals indicative of the dimensions of the object. These digital signals are converted to dimensional form and displayed.

Claims

1. Structure comprising:

means for producing one measure of a field of view without an object present and for producing another measure of the field of view with an object present, said means for producing comprising;

photosensitive array means for receiving light representing the field of view without an object present and for producing from said light one set of intermediate signals representative of said field of view without an object present, said one set of intermediate signals comprising said one measure, and for receiving light representing the field of view with an object present and for producing from said light another set of intermediate signals representing said field of view with said object present, said another set of intermediate signals comprising said another measure;

means for controlling said photosensitive array means to produce in sequence said one set of intermediate signals and said another set of intermediate signals; and

means for converting said one set and said another set of intermediate signals produced by said photosensitive array means to one set and another set of digital code words respectively,

means for storing either said one set of digital code words representing said field of view without said object present, or said another set of digital code words representing said field of view with said object present, whichever set of digital code words is produced first in time;

means for processing said one set of digital code words and said another set of digital code words to produce an intermediate set of digital code words indicative of the change of the field of view between the time of producing said one measure and the time of producing said another measure, wherein said intermediate set of digital code words is also indicative of selected characteristics of said object;

means for storing said intermediate set of digital code words;

means for processing said intermediate set of digital code words to obtain a measure of a selected characteristic of said object in said field of view;

means for deriving from either said one set of digital code words or said another set of digital code words, whichever is produced first in time, and said intermediate set of digital code words, both an indication of the presence or absence of an object at a selected time, and a selected dimension of said object; and

means for displaying said selected dimension of said object.

2. Structure as in claim 1 wherein said means for storing includes a programmable read-only memory for controlling the operation of said means for processing.

3. Structure as in claim 2 wherein said means for storing includes static memory interface means for interconnecting said programmable read-only memory and the other memory contained in said means for storing to said means for processing.

4. Structure as in claim 3 including means for interconnecting said means for controlling said photosensitive array means, said means for storing, and said means for processing thereby to allow data to be transmitted between each of said means in accordance with instructions from said programmable read-only-memory means and said means for controlling said photosensitive array means.

5. Structure as in claim 1 wherein said photosensitive array means comprises a line of light sensitive elements for producing said one set of intermediate signals representative of the field of view without said object present and said another set of intermediate signals representative of said field of view with said object present, respectively, and means for ampliyfing the signals produced by said line of light sensitive elements, and

wherein said means for controlling said photosensitive array means comprises means for clearing said photosensitive array means of signals generated prior to a selected time, means for controlling the transfer of signals from the light sensitive elements of said photosensitive array means to said means for amplifying, and means for allowing said photosensitive array means to accumulate in each of said light sensitive elements an amount of charge proportional to the light incident upon said element over a selected time.

6. The method of detecting the presence of an object and of determining a selected dimension of said object which comprises:

(1) deriving a first set of signals representing the state of the field of view of an array of photosensitive elements without the object present;

(2) deriving a second set of signals representing the state of the field of view of said array of photosensitive elements;

(3) comparing said second set of signals to said first set of signals to generate a set of difference signals representing the difference between said second set of signals and said first set of signals;

(4) comparing the set of difference signals to a reference thereby to indicate the presence of an object when said set of difference signals bears a given relation to said reference;

(5) repeating steps (2) through (4) until said set of difference signals bears said given relation to said reference; and

(6) calculating from said set of difference signals, said selected dimension of said object.

7. The method of setting the integration time of each of the light sensitive elements of an array of photosensitive elements comprising:

(1) integrating light incident upon each element in said photosensitive array for a first selected time comprising the integration time thereby to accumulate in each light sensitive element a charge packet proportional to the integral of the incident light on said element;

(2) transferring from each light sensitive element the charge packet accumulated therein during said integration time;

(3) measuring the amplitude of at least one charge packet from at least a selected one of the light sensitive elements and comparing the measured amplitude of said at least one charge packet to a reference amplitude thereby to generate a difference signal;

(4) adjusting the integration time in response to the amplitude of said difference signal provided the absolute value of said difference signal exceeds a minimum difference;

(5) repeating steps (1) through (4) until said measured difference signal has an absolute value within said specified minimum difference; and

(6) selecting as the integration perior that time which was used to achieve a measured difference signal within said specified minimum difference of said reference amplitude.

8. The method of operating a photosensitive array of light sensing elements which comprises:

determining the optimum integration time to ensure that the amplitude of the charge packet accumulated in at least one light sensing element is within a selected magnitude of a given reference amplitude;

accumulating within each photosensitive element a charge packet proportional to the incident light upon said photosensitive element over said integration time;

reading out at the end of said integration time the charge packets accumulated within the photosensitive elements in said photosensitive array;

processing said charge packets thereby to generate in response to each readout of said photosensitive array, a set of signals representative of the field of view seen by said photosensitive array; and

storing selected ones of said sets of signals for further processing for the purposes of detecting the presence of an object in said field of view and for providing information relating to a selected dimension of said object.

9. The method of claim 8 wherein the step of further processing selected sets of signals derived from said photosensitive array comprises:

calculating a set of difference signals from selected sets of signals produced by said photosensitive array;

comparing the set of difference signals to a selected reference to detect the presence of said object when a selected number of said difference signals exceed said reference; and

calculating from said difference signals a selected dimension of said object.

10. The method of claim 9 wherein the step of calculating from said difference signals selected dimensions of said object comprises:

calculating from said difference signals at least one width of said object.