Optical receiver for area location system

• US 5,355,222 A
• Filed: 05/15/1992
• Issued: 10/11/1994
• Est. Priority Date: 05/15/1992
• Status: Expired due to Term

• Current Assignee: Precision Tracking FM Incorporated
• Original Assignee: Precision Tracking FM Incorporated
• Inventors: Olivier, Philip D., Heller, Alan C., Fox, Christopher W.
• Primary Examiner(s): Housel, James C.
• Assistant Examiner(s): Freed, Rachel
• Application Number:
  US07/884,076
• Time in Patent Office: 879 Days
• Field of Search: 356/373, 356/375, 356/141, 356/152, 250/561
• US Class Current: 356/610
• CPC Class Codes: G01S 3/7835 using coding masks
• CPC Class Codes: G01S 3/784 using a mosaic of detectors

Abstract

An optical location system for locating the position of a moving object in a defined area. An optical transmitter is attached to the moving object. A stationary receiver has a number of sensors for receiving a signal from the transmitter. One sensor has a field of view of the entire area. Other sensors have partially blocked fields of view, with the blocking being accomplished with nonopaque strips of decreasing width. These strips are arranged so that the detection or nondetection of light by the sensors can be digitally coded in a manner that corresponds to sections of the area.

Claims

1. An optical location system for locating the position of a moving object in a defined area, comprising:

an optical transmitter for attachment to the moving object;

a number of optical sensors for receiving a signal from said transmitter,

wherein one of said sensors is a full-view sensor having a field of view of all of said defined area; and

an opaque template for each of said sensors other than said full view sensor,

wherein each of said templates has at least one horizontal or vertical blocking strip for partially blocking the field of view of said sensors other than said full-view sensor, such that each of said sensors other than said full-view sensor is a horizontal or vertical partial view sensor having a field of view of approximately one-half of said defined area, as determined by at least one horizontal or vertical window where said at least one blocking strip does not cover the field of view,

and wherein said blocking strips or said windows vary in size and number with respect to each of said horizontal or vertical partial view sensors, such that the detection or non detection of a signal from said transmitter can be used to form a digital code that represents a resolution of said defined area of 2ⁿ where n is the number of said partial view sensors and having not more than n+1 sensors.

2. The system of claim 1, wherein each said template has alternating blocking strips and windows of equal size, such that for each ith additional partial view sensor, the blocking strips and windows of its template are one-half as wide but twice as many in number as those of the ith-1 sensor, such that said digital code is a binary code.

3. The system of claim 1, wherein each said template has alternating blocking strips and windows, such that for each ith additional sensor, its template has a window or blocking strip that provides that sensor with a field of that overlaps the field of view of the ith-1 sensor, such that said digital code is a gray code.

4. The system of claim 1, wherein said templates comprise a set of templates having vertical blocking strips and a set of templates having horizontal blocking strips.

5. The system of claim 1, wherein said windows are shaped such that each window has a varying width, with wider portions corresponding to the view of closer portions of said area, to compensate for a perspective view of said sensors.

6. The system of claim 5, wherein said windows are truncated.

7. The system of claim 5, wherein said windows are shaped to compensate for a perspective view except where said window defines a perimeter of the field of view of said area.

12. The method of claim 1, and further comprising the step of locating a number of said targets and identifying said targets by means of an optical identification code.

8. A method of locating a moving target in a defined area, comprising the steps of:

attaching an optical transmitter to a target whose movement is within a defined area;

receiving optical signals from said transmitter using a number of sensors;

using one of said sensors to view all of said defined area;

partially blocking the field of view of one or more of said sensors by placing an opaque strip or strips over said one or more of said sensors, such that each is a partial view sensor having a field of view of approximately one-half said defined area, as determined by at least one nonopaque horizontal or vertical window over each of said partial view sensors where said at least one blocking strips does not cover the field of view, and such that said blocking strips or said windows vary in size and number with respect to each of said horizontal or vertical partial view sensors, and such that the detection or non detection of a signal from said transmitter can be used to form a digital code that represents a resolution of said defined area of 2ⁿ where n is the number of said partial view sensors and having not more than n+1 sensors.

9. The method of claim 8, wherein said step of partially blocking is performed such that each said template has alternating blocking strips and windows of equal size, such that for each ith additional partial view sensor, the blocking strips and windows of its template are one-half as wide but twice as many in number as those of the ith-1 sensor, such that said digital code is binary code.

10. The method of claim 8, wherein said step of partially blocking is performed such that each said template has alternating blocking strips and windows, such that for each ith additional sensor, its template has a window or blocking strip that provides that sensor with a field of field that overlaps the field of view of the ith-1 sensor, such that said digital code is gray code.

11. The method of claim 8, wherein said step of partially blocking is performed by shaping each of said windows with a varying width, with wider portions corresponding to closer portions of said area, to compensate for a perspective view of said area.

13. An optical receiver for receiving an optical signal from a moving transmitter in a defined area, and generating digital code indicating the location of said transmitter within said area, comprising:

a number of optical sensors for receiving a signal from said transmitter,

wherein one of said sensors is a full-view sensor having a field of view of all of said defined area; and

a template for each of said sensors other than said full view sensor,

wherein each of said templates has at least one horizontal or vertical blocking strip for partially blocking the field of view of said sensors other than said full-view sensor, such that each of said sensors other than said full-view sensor is a horizontal or vertical partial view sensor having a field of view of approximately one-half of said defined area, as determined by at least one horizontal or vertical window where said at least one blocking strip does not cover the field of view,

and wherein said blocking strips or said windows vary in size and number with respect to each of said horizontal or vertical partial view sensors, such that the detection or non detection of a signal from said transmitter can be used to form a digital code that represents a resolution of said defined area of 2ⁿ where n is the number of said partial view sensors and having not more than n+1 sensors.

14. The receiver of claim 13, wherein each said template has alternating blocking strips and windows of equal size, such that for each ith additional partial view sensor, the blocking strips and windows of its template are one-half as wide but twice as many in number as those of the ith-1 sensor, such that said digital code is a gray code.

15. The receiver of claim 13, wherein each said template has alternating blocking strips and windows, such that for each ith additional sensor, its template has a window or blocking strip that provides that sensor with a field of field that overlaps the field of view of the ith-1 sensor, such that said digital code is a gray code.

16. The receiver of claim 13, wherein said templates comprise a set of templates having vertical blocking strips and a set of templates having horizontal blocking strips.

17. The receiver of claim 13, wherein said windows are shaped such that each window has a varying width, with wider portions corresponding to the view of closer portions of said area, to compensate for a perspective view of said sensors.

18. The receiver of claim 17, wherein said windows are truncated.

19. The receiver of claim 17, wherein said windows are shaped to compensate for a perspective view except where said windows define a perimeter of the field of view of said area.