PRECISION ANGLE MEASURING DEVICE

• US 3,708,231 A
• Filed: 11/10/1969
• Issued: 01/02/1973
• Est. Priority Date: 11/10/1969
• Status: Expired due to Term

• Current Assignee: Glenn A. Walters
• Original Assignee: Glenn A. Walters
• Inventors: Walters, Glenn A.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US04/870,376
• Time in Patent Office: 1,149 Days
• Field of Search: 356/141,149,150,152,138 250/216,235,22R 33/72
• US Class Current: 356/152.1
• CPC Class Codes: G01C 9/04 Transmission means between sensing element and final indicator for giving an enlarged reading
• CPC Class Codes: G01D 5/30 the beams of light being detected by photocells

Abstract

A device for the precision measuring of angular movements. The device incorporates an optical lever utilizing a predetermined number of reflections to increase the displacement of a light beam to be read out by discrete sensors. Ambiguities resulting from the amplification of displacement are resolved by determining displacement at a plurality of points of reflection and by using periodic logic on the sensor outputs.

Claims

1. A device for measuring angles comprising:

a housing;

first mirror means for rotatably moving an angular amount on said housing proportional to an angle to be measured;

second mirror means;

said first and second mirror means having reflective surfaces means for being opposed one to the other for any angle within the range to be measured;

the angle to be measured relates to the angular displacement between the axis of the two mirrors in the plane of rotation;

the plane of the second mirror is offset from parallel relative to the first mirror in the line of the axis of rotation by a fixed offset angle;

light beam source means for producing a light beam that is reflected between said first and second mirror means a fixed number of times determined by said offset angle;

additional mirror means may be included within the light path, whereby the optical leverage and the instrument configuration may be improved;

sensing means for sensing the linear position of said light beam after said light beam has been reflected between said first and second mirror means, and providing an unambiguous angular reading.

2. The device of claim 1 wherein the number of monitoring sensors required to measure a given number of angular increments are reduced:

said sensing means comprises a photosensitive array of discreet photo sensitive elements of a specified width separating each from the other by said specified width;

the beamwidth of the light beam source as measured along the photosensitive array is half again as wide as said specified width;

wherein the simultaneous monitoring of a beam by two adjacent sensors indicates a beam position between them and the monitoring of a beam by one sensor indicates a coincident beam position;

thus, each sensor is used to sense two discreet angle increments.

3. A device for measuring angles comprising:

a housing;

first multi-surfaced mirror means for rotatable moving an angular amount on said housing proportional to an angle to be measured;

second mirror means;

the multi-surface of the first mirror and second mirror means having reflective surfaces means for being opposed one to the other for any angle within the range to be measured;

the multiple-surfaCes of the first mirror are geometrically arranged to become reflective to the second mirror in a sequential and similar manner;

the angle to be measured relates to the angular displacement between the axis of the two mirrors in the plane of rotation;

the plane of the second mirror is offset from parallel relative to the axis of rotation of the first mirror by a fixed offset angle;

light beam source means for producing a light beam that is reflected between said first and second mirror beams a fixed number of times determined by said fixed offset angle;

additional mirror means may be included within the light path, whereby the optical leverage and the instrument configuration may be improved;

sensing means for sensing the linear position of said light beam after said light beam has been reflected between said first mirror and second mirror means;

a second sensing means for sensing the rotary position of the first mirror to determine which of the multi-surfaces is involved in the light reflective process; and

a means to combine the output from the two sensing means to provide a discreet angle measurement in an unambiguous manner throughout the angular range of the device.

4. A sensing means wherein the number of monitoring sensors required to measure a given number of angular increments are reduced:

said sensing means comprises a photosensitive array of discreet semireflective photosensitive elements lying within the light beam path;

wherein said sensing means derives angular measurements by sensing the number of light reflections and spacing between light reflections along the array.