Coordinate measuring method and device with a contact member and light detector

• US 4,583,000 A
• Filed: 03/22/1984
• Issued: 04/15/1986
• Est. Priority Date: 11/14/1980
• Status: Expired due to Term

• Current Assignee: LMI Technologies Inc.
• Original Assignee: Difracto Limited
• Inventors: Pryor, Timothy R.
• Primary Examiner(s): Nelms, David C.
• Application Number:
  US06/592,028
• Time in Patent Office: 754 Days
• Field of Search: 250/560, 250/561, 250/221, 250/216, 250/229, 250/231 R, 250/237 R, 33/125 A, 33/DIG. 3, 33/174 L, 33/169 R, 33/172 E, 33/366, 33/391, 401/47
• US Class Current: 250/559.31
• CPC Class Codes: G01B 11/007 feeler heads therefor

Abstract

A method and device for sensing the presence and location of an object in a reference plane by directing light along a line perpendicular to the plane, defining a ring in that plane encircling said line of light, and sensing, by a change in the condition of the light, the presence of an object on the ring. In a first, non-contacting embodiment, light is directed along a line which is the axis of the ring and directed outwardly and focused at the ring. A circular detector coaxial with the light ring is positioned to sense intrusion onto that ring of an object, and by using a circular diode array detector, one can detect both the presence and location of that object on the ring. According to another contacting embodiment, a disc is placed in the reference plane with the light shining through an opening therein, the disc being movable in any direction in said reference plane. When an object touches the disc at any point and moves it, this changes the location of the aperture through which the light passes. This change is sensed to indicate an object on the ring.

Claims

1. A device for optically sensing the presence of an object in a plane perpendicular to a reference axis, said device comprising:

a disc disposed in said plane and movable in all directions in said plane; and

means for directing light along the reference axis;

detector means for detecting a reference condition of the light when the disc is the rest position thereof, and for detecting a different condition of the light when the position of the disc is changed from said rest position by contact with the object.

2. A device according to claim 1, wherein said disc has a hole therethrough, said light passing through the hole and imaging on said detector means in said rest position.

3. A device according to claim 1, including means for moving the disc along the axis to sense the location of objects in different planes on the axis.

4. A device according to claim 1 wherein said detector means is further responsive to the amount of movement of the disc along said reference axis.

5. A device according to claim 1 wherein said detector means is further capable of detecting the magnitude and direction of said movement of said disc relative to said reference axis.

6. A device according to claim 5 wherein said detector means is a photo detector array.

7. An apparatus as claimed in claim 1 wherein said disc is part of a ball contact member and said apparatus includes means for mounting said ball contact member for movement in a direction orthogonal to said plane.

8. A device according to claim 5 wherein said detector is an analog position sensing detector.

9. A method for optically sensing the position and location of an object in a plane perpendicular to a reference axis, comprising:

locating a disc, in said plane, which is movable in all directions in said plane from a normal rest position,

directing light along the axis across said plane, and

monitoring the light received by a light detector disposed such that said detector senses a reference condition of the light when said disc is in the rest position thereof and senses a different condition of the light when said disc is moved by contact with a said object.

10. A method according to claim 9 further incorporating the step of moving said reference axis until said object presence is determined and reading the position of said axis to determine the coordinate location of said object.

11. A method according to claim 10 wherein said object direction of contact is further determined.

12. A method according to claim 9 further comprising determining the coordinates of said object relative to said reference axis.

13. A device for optically sensing the presence and location of an object, said device comprising

a contact member moveable in at least two dimensions from a normal, rest position thereof;

a light source;

a matrix photodetector array;

means for forming an image on said photodetector array of at least one point of said contact member with said contact member in the rest position thereof; and

means for determining the presence of a said object in contact with said contact member from a change of position of said image relative to said photodetector array and for determining the amount of movement of said contact member relative to the rest position thereof from the output of said photodetector array to thereby determine the relative location of the said object.

14. A device as claimed in claim 13 wherein said determining means comprises further means for determining the position of the said object in a direction orthogonal to the plane of said two dimensions.

15. A device as claimed in claim 13 wherein said determining means includes means for comparing the size of the image of the contact member in a non-rest position thereof with the size of said image for the rest position of said contact member so as to determine the relative position of said contact member in a direction orthogonal to the plane of said photodetector array.

16. A device as claimed in claim 13 wherein said contact member comprises a ball contact and said light source is located within said ball contact.