Encoder for providing calibrated measurement capability of rotation or linear movement of an object, label medium and an optical identification system

• US 5,471,054 A
• Filed: 09/25/1992
• Issued: 11/28/1995
• Est. Priority Date: 09/30/1991
• Status: Expired due to Fees

• Current Assignee: NF. T&M. Systems, Inc.
• Original Assignee: NF. T&M. Systems, Inc.
• Inventors: Watanabe, Asao
• Primary Examiner(s): Allen, Stephone B.
• Application Number:
  US07/951,221
• Time in Patent Office: 1,159 Days
• Field of Search: 250/231.13, 250/231.18, 250/237 G, 250/231.14, 341/13, 341/31, 356/373, 356/374, 359/529, 359/530, 235/454
• US Class Current: 250/231.13
• CPC Class Codes: G01D 18/001 Calibrating encoders
• CPC Class Codes: G01D 18/008 with calibration coefficients stored in memory
• CPC Class Codes: G01D 5/2449 using hard-stored calibration data
• CPC Class Codes: G01D 5/2451 Incremental encoders G01D5/2454 takes precedence
• CPC Class Codes: G01D 5/347 using displacement encoding scales
• CPC Class Codes: G01P 1/04 Special adaptations of driving means
• CPC Class Codes: G01P 3/486 delivered by photo-electric detectors
• CPC Class Codes: G01P 3/488 delivered by variable reluctance detectors

Abstract

A scale comprising a regular arrangement of optically or magnetically different response characteristics such as light reflection and light diffusion portions or light reflection and absorption portions is attached to a moving object either directly or by way of an intermediate member. The scale can be attached to a motor or the like even after assembling with associated mechanical components, thereby enabling easy measurement of the mode of operation of the motor or similar movable objects. The light beam from the light emitting device is directed to the label media and the reflected light beam is received by a light receiving device to identify the individual object or product based on the label.

Claims

1. An encoder comprising:

a scale to be attached to a rotating object to be measured by way of a mounting member, said scale having a regular arrangement of portions with different optical or magnetic response;

detection means to detect the difference in response of said scale;

measurement means to measure position information of rotating movement of said object to be measured based on the change in time in the response detected by said detection means;

memory means for storing the position information of said scale when said object to be measured is rotated by a known amount; and

calibration means for calibrating the measured position information based upon the stored position information of said scale in said memory means,

wherein said mounting member comprises a first mounting portion adapted to partially surround the rotating object and a second mounting portion adapted to partially surround the rotating object, said first mounting portion having a coupler portion and said second mounting portion having a corresponding mating portion for receiving said coupler portion, thereby securely engaging the first and second mounting portions to one another in surrounding engagement with the rotating object.

2. An encoder of claim 1 wherein said scale includes alternate arrangement of optically reflecting and diffusing portions.

3. An encoder of claim 1 wherein said scale includes alternate arrangement of optically reflecting and absorbing portions.

4. An encoder of claim 1 wherein said scale includes alternate arrangement of optically reflecting portions and corner cube portions.

5. An encoder of claim 1 wherein said scale is formed on the surface of a flexible tape.

6. An encoder of claim 1 wherein the measurements of the position information are calibrated in accordance with stored positions of said scale when said object to be measured is rotated by a known amount.

7. An encoder of claim 1 wherein said object to be measured is a shaft of a rotating object.

8. An encoder of claim 7 wherein said first mounting portion and said second mounting portion are coupled by a hinge for enabling easy installation on the shaft of said rotating object.

9. An encoder of claim 7 wherein said first mounting portion and said second mounting portion are secured to one another by an adhesive.

10. An encoder of claim 7 wherein said scale is attached to the circumferential surface of said mounting member mounted around the shaft of said rotating object.

11. An encoder of claim 10 wherein said mounting member is constructed to have smaller mass in the radial direction.

12. An encoder of claim 10 wherein a notch is formed in the abutting surface between said mounting member and the shaft.

13. An optical identification system characterized in that a label media for indicating a specified information comprising first and second portions arranged in a predetermined relationship, which defines said specified information, with each other is attached to an object, said first portion being configured to have parallel incoming and outgoing light beams and said second portion having an optical response characteristic different from that of said first portion;

and a light beam from a light emitting device is directed to said first and second portions of said label media and the light reflected therefrom is detected by a light receiving device disposed parallel to said light emitting device;

thereby identifying the information defined by the predetermined relationship of said label media in accordance with a change in the light receiving level by said light receiving device,

wherein said object includes a rotating member and said label media is adapted for mounting to the rotating member via a mounting member, said mounting member comprising a first mounting portion adapted to partially surround a portion of the rotating member and a second mounting portion adapted to partially surround a portion of the rotating member, said first mounting portion having a coupler portion and said second mounting portion having a corresponding mating portion for receiving said coupler portion, thereby securely engaging the first and second mounting portions to one another in surrounding engagement with the rotating member.

14. An optical identification system of claim 13 wherein said first mounting portion and said second mounting portion are coupled by a hinge for enabling easy installation on a shaft of said rotating member.

15. An optical identification system of claim 13 wherein said first mounting portion and said second mounting portion are secured to one another by an adhesive.