CA2068795A1 - Rotational position sensor - Google Patents
Rotational position sensorInfo
- Publication number
- CA2068795A1 CA2068795A1 CA 2068795 CA2068795A CA2068795A1 CA 2068795 A1 CA2068795 A1 CA 2068795A1 CA 2068795 CA2068795 CA 2068795 CA 2068795 A CA2068795 A CA 2068795A CA 2068795 A1 CA2068795 A1 CA 2068795A1
- Authority
- CA
- Canada
- Prior art keywords
- eddy current
- encoder wheel
- current coil
- probe body
- inspection head
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Landscapes
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A rotational position sensor for determining the rotational position of an inspection head rotatably mounted on a probe body.
The position sensor is formed from a spiral shaped encoder wheel and eddy current coil. The encoder wheel is rotatably mounted in the probe body and is rotated simultaneously with an inspection head. The eddy current coil is mounted in a stationary position in the probe body and radially spaced from the encoder wheel.
During rotation of the encoder wheel the changing air gap between the eddy current coil and encoder wheel produces a variable electrical signal from the eddy current coil that is representative of the rotational angular position of the inspection head.
A rotational position sensor for determining the rotational position of an inspection head rotatably mounted on a probe body.
The position sensor is formed from a spiral shaped encoder wheel and eddy current coil. The encoder wheel is rotatably mounted in the probe body and is rotated simultaneously with an inspection head. The eddy current coil is mounted in a stationary position in the probe body and radially spaced from the encoder wheel.
During rotation of the encoder wheel the changing air gap between the eddy current coil and encoder wheel produces a variable electrical signal from the eddy current coil that is representative of the rotational angular position of the inspection head.
Description
CAS~ 51~1 206879~
ROTATIONAL P08I~ION 8EN80R
BACXGROUND OF THE INVENTION
1. Field of the Invention The present invention is generally related to nondestructive inspection of tubes and more particularly to a rotary position sensing apparatus.
ROTATIONAL P08I~ION 8EN80R
BACXGROUND OF THE INVENTION
1. Field of the Invention The present invention is generally related to nondestructive inspection of tubes and more particularly to a rotary position sensing apparatus.
2. General Background In the commercial nuclear industry steam generators used in energy production are generally of the straight tube or U-tube design. Primary coolant from the nuclear reactor travels through the tubes and transfers heat to the secondary coolant in the steam generator. Due to the serious consequences which can result from a tube leak, the tubes are inspected for defects on a routine basis. To perform such inspections, it is typical to use a pancake eddy current coil mounted in a rotating probe that is caused to travel through each tube being inspected. This results in a helical inspection path for the coil. During inspection, the coil induces eddy currents in the tube wall. Variations in these eddy currents, caused by tube defects, can be sensed by monitoring the coil impedance. Changes in the coil impedance may be used to indicate the presence of defects in the tube. The quality of the inspection results is directly related to the ability to accurately synchronize the eddy current data from the probe head coil with the rotation of the probe head. Patents directed to determining the rotary position of a shaft which applicants are aware of include the following:
C~8E~ 5111 20S879~
U.S. Patent No. 4,746,859 discloses the use of a pair of magnetic sensors and a ferromagnetic shaft. The sensors are placed adjacent to one or two wheels having continuously increasing radial dimensions with radial offsets on the outer surfaces at common points of maximum and minimum radial dimension. The change in the output signals indicate the change in the length of the air gap between the sensors and wheels and the corresponding position of the wheel and a rotor attached to the same axle.
U.S. Patent No. 3,297,940 discloses the use of a shaped magnetic shield on a rotating disc between an oscillating coil and a pick up coil for use as a potentiometer that eliminates the need for a contact slider.
U.S. Patent No. 3,786,459 discloses a position coder for a moving shaft that generates a DC voltage having an amplitude proportional to the magnitude of position shift of the moving shaft with respect to a fixed point and a sign that changes whenever a shift in direction takes place.
U.S. Patent N0. 3,562,741 discloses an electromagnetic pulse generating system utilizing a single transducer and a disc having teeth of various shapes that generate different signals as they move past the transducer during rotation of the disc.
U.S. Patent No. 4,719,419 discloses a noncontact rotary position sensor for measuring the rotary position of a shaft that ' 25 includes a magnetic member mounted for rotation with the shaft ; where the central axis of the magnetic member is eccentric from ' the axis of rotation of the shaft. A Hall effect device spaced from the sha t measures the varying magneti= ~lux density ..
.
~, 2~68795 produced by the magnetic member to determine the position of the shaft.
U.S. Patent No. 4,507,638 discloses a rotatable plate shaped to allow predetermined amounts of magnetic flux to pass from a 5drive coil to a sensing coil as the plate is rotated to determine a selected angle of rotation of the plate.
U.S. Patent No. 4,764,767 discloses a rotor section with a first pattern that repeats change in the circumferential direction with a predetermined pitch and a second pattern that 10has a change of one cycle with respect to one circumference.
Comparison of signals from a detector for each pattern provides a value of the rotational position of the rotor.
', U.S. Patent No. 4,631,510 discloses a harmonically graded air gap reluctance-type rotating electric resolver. A rotor with , 15a single lobe receives magnetic flux as it rotates, with the flux ~ received by the rotor being directly related to the position of v the rotor relative to teeth on a stator.
- U.S. Patent No. 3,819,025 discloses an apparatus for determining the angular position of print on a paper by ' 20determining the angle of rotation of a revolving axis from a s predetermined reference position. A magnetic shield plate in the ; form of a spiral is used to control the degree of magnetic coupling between primary and secondary windings.
, U.S. Patent No. 3,835,373 discloses a rotational position 25sensor where a half cylinder provides a varying signal by varying the air gap between the half cylinder and a C-shaped permanent magnet.
, . .
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_~_ 206879~
Although there are a number o~ electromagnetic methods for determining the circumferential position of a shaft, most tend to be complicated. Devices such as that in U.S. Patent No.
4,746,859 require a pair of a magnetic sensors to be used with a ferromagnetic shaft and circuitry for adding, subtracting, multiplying, and dividing the signal. Magnetic sensors are usually three-wire hall devices that are fabricated using expensive semiconductor technology. This leaves a need for devices capable of accurately determining the circumferential position of a shaft that does not require multiple sensors, will fit into small areas, and can be inexpensively fabricated in small quantities.
SUMMARY OF THE INVENTION
The present invention addresses the above need in a straightforward manner. What is provided is an eddy current encoder that provides circumferential orientation feedbacX to an acquisition computer that registers and aligns the tube inspection data. A probe body assembly used in the examination of tubes has a drive motor mounted therein that drives or rotates an inspection head at one end of the probe body. A spiral shaped encoder wheel is rotatably mounted in the probe body and attached to the drive motor. The encoder wheel is rotated by the drive motor simultaneously with rotation of the inspection head. An eddy current coil is mounted in a stationary position in the probe body and radially spaced from the encoder wheel. The eddy current coil senses the air gap between the encoder wheel and the eddy current coil. This information is used to synchronize the CAS E ~
eddy current data obtained from the eddy current coil with the rotation of the inspection head.
B~IEF DESCRIPTION OF THE D~AWINGS
For a further understanding of the nature and objects of the present invention reference should be made to the following drawings taken in c~njunction with the accompanying description in which like parts are given like reference numerals and, wherein:
Fig. 1 is a perspective view of the invention.
Fig. 2 is a sectional view illustrating the invention in a probe body.
Fig. 3 is an enlarged view taken along lines 3-3 of Fig. 2.
Fig. 4 is an illustration of signals generated by the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, it is seen in Fig. 1 that the invention is generally indicated by the numeral 10. Rotational position sensor 10 is comprised of encoder wheel 12, eddy current ` coil 14, and eddy current instrument 16.
' 20 Encoder wheel 12 has a main body portion 18 that is substantially cylindrical in shape. One end of main body portion ` 18 is adapted to be attached to a drive motor by being provided with slot 20 that extends radially and axially through the end.
, The opposite end of main body portion 18 is provided with axial threaded bore 22 for threaded mounting on an axle. Main body portion 18 is provided with section 26 substantially along its center that has a larger diameter than main body portion 18.
Section 26 is formed in a substantially spiral shape such that it ,, ,, ,.
:
. ~ .
.
206879~
has a continuously increasing radial dimension as measured from the longitudinal axis of main body portion 18. Section 26 is provided with radial offset 28 at the common point of maximum and minimum radial dimension. Eddy current coil 14 ~s mounted on probe body 24 in a stationary position relative ta encoder wheel ; 12. Eddy current coil 14 is connected with eddy current instrument 16 by wiring 30. Electrical signals generated by eddy current coil 14 that indicate the size of the air gap between eddy current coil 14 and spiral section 26 of encoder wheel 12 are received, recorded, and displayed by eddy current instrument 16. As seen in Fig. 4, the signals generated by eddy current coil 14 and displayed on screen 32 and recorded by eddy current instrument 16 are proportional to the air gap or distance between eddy current coil 14 and spiral section 26 of encoder wheel 12.
As an example, point 28A of the signal generated on screen 32 corresponds to the rotational position of encoder wheel 12 where radial offset 28 is at its closest position to eddy current coil 14. It can be seen that the variable electrical signals from eddy ~urrent coil 14 can be used to determine the rotational position of encoder wheel 12. This also allows the rotational position of equipment rotated simultaneously with encoder wheel 12 to be determined.
An example of such a use is illustrated in Fig. 2 and 3.
; Encoder wheel 12 is rotatably mounted inside probe body 24 between a drive motor/gear assembly 38, and a slip ring assembly 40. Axial threaded bore 22 threadably receives the threaded slip ` ring shaft axle 34. At the opposite end, slot 20 receives flats on drive shaft 36 that extend from drive motor 38. The torque of .
,., .,.
., .
2~68795 the motor 38 is transmitted through the encoder wheel 12, slip ring 40, a short flexible drive shaft 47 and an electrical/mechanical connector 45 to probe head 44.
Electrical signals are carried by non-rotating wires 42 to the slip ring 40. Within the slip ring, brushes transmit the electrical signals to the inspection head through rotating wires 43 running through the flexible drive shaft 47. Inspection head 44 is used to inspect tubing walls for defects as probe body 24 is moved through the tubing while inspection head 44 is rotated.
Inspection head 44 may be provided with means 46 for inspecting the tubing such as an eddy current coil. In a manner known in the art, the eddy current coil is used to induce eddy currents and sense the presence of defects in the tubing. It should be noted that although inspection head 44 is generally indicated as one that uses an eddy current coil to detect the presence of defects in the tubing, any of sever~l different types of inspection heads and means for inspecting the tubing known in the art may be used in conjunction with rotational position sensor 10. The rotational position of means 46 relative to the rotational position of encoder wheel 12 is recorded upon installation of inspection head 44. This allows the signals from means 46 on inspection head 44 to be synchronized with the signals from eddy current coil 14 whereby the variable electrical signals from eddy current coil 14 are representative of the rotational angular position of inspection head 44. This provides a means for determining the rotational position of defects in the tubing. This can be useful in diagnosing specific problems in equipment being examined.
CAglZ 5111 In operation, probe body 24 is lnserted into a tube o~ a steam generator or similar type of equipment for examination of the tube. Probe body 24 is inserted and moved through the tube by cable 48 attached to one end of probe body 24. Cable 48 houses wiring from equipment inside probe body 24 such as eddy current coil 14, drive motor 38, and inspection head 44 for ` monitoring and control of the equipment. While probe body 24 is travelling through the tube, drive motor 38 is actuated. This causes simultaneous rotation of encoder wheel 12 and inspection head 44. The changing air gap between eddy current coil 14 and encoder wheel 12 produces a variable electrical signal from eddy current coil 14 that is registered and recorded by eddy current instrument 16. A visual representation of these varying signals may be provided in form of a display on screen 32 such as that in Fig. 4. Signals from inspection head 44 and tube inspection means 46 are recorded and analyzed to determine the presence of i defects in the tube being examined. Since the rotational position of inspection head 44 relative to encoder wheel 12 is known, the variable electrical signal from eddy current coil 14 is representative of the rotational angular position of inspection head 44.
Because many varying and differing embodiments may be made ; within the scope of the inventive concept herein taught and ::
because many modifications may be made in the embodiment herein detailed in accordance with the descriptive requirement of the -~ law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.
,: .
.;.
.,;
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C~8E~ 5111 20S879~
U.S. Patent No. 4,746,859 discloses the use of a pair of magnetic sensors and a ferromagnetic shaft. The sensors are placed adjacent to one or two wheels having continuously increasing radial dimensions with radial offsets on the outer surfaces at common points of maximum and minimum radial dimension. The change in the output signals indicate the change in the length of the air gap between the sensors and wheels and the corresponding position of the wheel and a rotor attached to the same axle.
U.S. Patent No. 3,297,940 discloses the use of a shaped magnetic shield on a rotating disc between an oscillating coil and a pick up coil for use as a potentiometer that eliminates the need for a contact slider.
U.S. Patent No. 3,786,459 discloses a position coder for a moving shaft that generates a DC voltage having an amplitude proportional to the magnitude of position shift of the moving shaft with respect to a fixed point and a sign that changes whenever a shift in direction takes place.
U.S. Patent N0. 3,562,741 discloses an electromagnetic pulse generating system utilizing a single transducer and a disc having teeth of various shapes that generate different signals as they move past the transducer during rotation of the disc.
U.S. Patent No. 4,719,419 discloses a noncontact rotary position sensor for measuring the rotary position of a shaft that ' 25 includes a magnetic member mounted for rotation with the shaft ; where the central axis of the magnetic member is eccentric from ' the axis of rotation of the shaft. A Hall effect device spaced from the sha t measures the varying magneti= ~lux density ..
.
~, 2~68795 produced by the magnetic member to determine the position of the shaft.
U.S. Patent No. 4,507,638 discloses a rotatable plate shaped to allow predetermined amounts of magnetic flux to pass from a 5drive coil to a sensing coil as the plate is rotated to determine a selected angle of rotation of the plate.
U.S. Patent No. 4,764,767 discloses a rotor section with a first pattern that repeats change in the circumferential direction with a predetermined pitch and a second pattern that 10has a change of one cycle with respect to one circumference.
Comparison of signals from a detector for each pattern provides a value of the rotational position of the rotor.
', U.S. Patent No. 4,631,510 discloses a harmonically graded air gap reluctance-type rotating electric resolver. A rotor with , 15a single lobe receives magnetic flux as it rotates, with the flux ~ received by the rotor being directly related to the position of v the rotor relative to teeth on a stator.
- U.S. Patent No. 3,819,025 discloses an apparatus for determining the angular position of print on a paper by ' 20determining the angle of rotation of a revolving axis from a s predetermined reference position. A magnetic shield plate in the ; form of a spiral is used to control the degree of magnetic coupling between primary and secondary windings.
, U.S. Patent No. 3,835,373 discloses a rotational position 25sensor where a half cylinder provides a varying signal by varying the air gap between the half cylinder and a C-shaped permanent magnet.
, . .
~r .
.,~,.
:~'.,' ' - ' /~
.i .
_~_ 206879~
Although there are a number o~ electromagnetic methods for determining the circumferential position of a shaft, most tend to be complicated. Devices such as that in U.S. Patent No.
4,746,859 require a pair of a magnetic sensors to be used with a ferromagnetic shaft and circuitry for adding, subtracting, multiplying, and dividing the signal. Magnetic sensors are usually three-wire hall devices that are fabricated using expensive semiconductor technology. This leaves a need for devices capable of accurately determining the circumferential position of a shaft that does not require multiple sensors, will fit into small areas, and can be inexpensively fabricated in small quantities.
SUMMARY OF THE INVENTION
The present invention addresses the above need in a straightforward manner. What is provided is an eddy current encoder that provides circumferential orientation feedbacX to an acquisition computer that registers and aligns the tube inspection data. A probe body assembly used in the examination of tubes has a drive motor mounted therein that drives or rotates an inspection head at one end of the probe body. A spiral shaped encoder wheel is rotatably mounted in the probe body and attached to the drive motor. The encoder wheel is rotated by the drive motor simultaneously with rotation of the inspection head. An eddy current coil is mounted in a stationary position in the probe body and radially spaced from the encoder wheel. The eddy current coil senses the air gap between the encoder wheel and the eddy current coil. This information is used to synchronize the CAS E ~
eddy current data obtained from the eddy current coil with the rotation of the inspection head.
B~IEF DESCRIPTION OF THE D~AWINGS
For a further understanding of the nature and objects of the present invention reference should be made to the following drawings taken in c~njunction with the accompanying description in which like parts are given like reference numerals and, wherein:
Fig. 1 is a perspective view of the invention.
Fig. 2 is a sectional view illustrating the invention in a probe body.
Fig. 3 is an enlarged view taken along lines 3-3 of Fig. 2.
Fig. 4 is an illustration of signals generated by the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, it is seen in Fig. 1 that the invention is generally indicated by the numeral 10. Rotational position sensor 10 is comprised of encoder wheel 12, eddy current ` coil 14, and eddy current instrument 16.
' 20 Encoder wheel 12 has a main body portion 18 that is substantially cylindrical in shape. One end of main body portion ` 18 is adapted to be attached to a drive motor by being provided with slot 20 that extends radially and axially through the end.
, The opposite end of main body portion 18 is provided with axial threaded bore 22 for threaded mounting on an axle. Main body portion 18 is provided with section 26 substantially along its center that has a larger diameter than main body portion 18.
Section 26 is formed in a substantially spiral shape such that it ,, ,, ,.
:
. ~ .
.
206879~
has a continuously increasing radial dimension as measured from the longitudinal axis of main body portion 18. Section 26 is provided with radial offset 28 at the common point of maximum and minimum radial dimension. Eddy current coil 14 ~s mounted on probe body 24 in a stationary position relative ta encoder wheel ; 12. Eddy current coil 14 is connected with eddy current instrument 16 by wiring 30. Electrical signals generated by eddy current coil 14 that indicate the size of the air gap between eddy current coil 14 and spiral section 26 of encoder wheel 12 are received, recorded, and displayed by eddy current instrument 16. As seen in Fig. 4, the signals generated by eddy current coil 14 and displayed on screen 32 and recorded by eddy current instrument 16 are proportional to the air gap or distance between eddy current coil 14 and spiral section 26 of encoder wheel 12.
As an example, point 28A of the signal generated on screen 32 corresponds to the rotational position of encoder wheel 12 where radial offset 28 is at its closest position to eddy current coil 14. It can be seen that the variable electrical signals from eddy ~urrent coil 14 can be used to determine the rotational position of encoder wheel 12. This also allows the rotational position of equipment rotated simultaneously with encoder wheel 12 to be determined.
An example of such a use is illustrated in Fig. 2 and 3.
; Encoder wheel 12 is rotatably mounted inside probe body 24 between a drive motor/gear assembly 38, and a slip ring assembly 40. Axial threaded bore 22 threadably receives the threaded slip ` ring shaft axle 34. At the opposite end, slot 20 receives flats on drive shaft 36 that extend from drive motor 38. The torque of .
,., .,.
., .
2~68795 the motor 38 is transmitted through the encoder wheel 12, slip ring 40, a short flexible drive shaft 47 and an electrical/mechanical connector 45 to probe head 44.
Electrical signals are carried by non-rotating wires 42 to the slip ring 40. Within the slip ring, brushes transmit the electrical signals to the inspection head through rotating wires 43 running through the flexible drive shaft 47. Inspection head 44 is used to inspect tubing walls for defects as probe body 24 is moved through the tubing while inspection head 44 is rotated.
Inspection head 44 may be provided with means 46 for inspecting the tubing such as an eddy current coil. In a manner known in the art, the eddy current coil is used to induce eddy currents and sense the presence of defects in the tubing. It should be noted that although inspection head 44 is generally indicated as one that uses an eddy current coil to detect the presence of defects in the tubing, any of sever~l different types of inspection heads and means for inspecting the tubing known in the art may be used in conjunction with rotational position sensor 10. The rotational position of means 46 relative to the rotational position of encoder wheel 12 is recorded upon installation of inspection head 44. This allows the signals from means 46 on inspection head 44 to be synchronized with the signals from eddy current coil 14 whereby the variable electrical signals from eddy current coil 14 are representative of the rotational angular position of inspection head 44. This provides a means for determining the rotational position of defects in the tubing. This can be useful in diagnosing specific problems in equipment being examined.
CAglZ 5111 In operation, probe body 24 is lnserted into a tube o~ a steam generator or similar type of equipment for examination of the tube. Probe body 24 is inserted and moved through the tube by cable 48 attached to one end of probe body 24. Cable 48 houses wiring from equipment inside probe body 24 such as eddy current coil 14, drive motor 38, and inspection head 44 for ` monitoring and control of the equipment. While probe body 24 is travelling through the tube, drive motor 38 is actuated. This causes simultaneous rotation of encoder wheel 12 and inspection head 44. The changing air gap between eddy current coil 14 and encoder wheel 12 produces a variable electrical signal from eddy current coil 14 that is registered and recorded by eddy current instrument 16. A visual representation of these varying signals may be provided in form of a display on screen 32 such as that in Fig. 4. Signals from inspection head 44 and tube inspection means 46 are recorded and analyzed to determine the presence of i defects in the tube being examined. Since the rotational position of inspection head 44 relative to encoder wheel 12 is known, the variable electrical signal from eddy current coil 14 is representative of the rotational angular position of inspection head 44.
Because many varying and differing embodiments may be made ; within the scope of the inventive concept herein taught and ::
because many modifications may be made in the embodiment herein detailed in accordance with the descriptive requirement of the -~ law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.
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Claims (2)
1. A rotational position sensor for determining the rotational position of an inspection head rotatably mounted on a probe body, comprising:
a. a spiral shaped encoder wheel rotatably mounted in the probe body and rotated simultaneously with the inspection head; and b. an eddy current coil mounted in a stationary position in the probe body and radially spaced from said encoder wheel whereby the changing air gap between said eddy current coil and said encoder wheel produces a variable electrical signal from said eddy current coil that is representative of the rotational angular position of said inspection head.
a. a spiral shaped encoder wheel rotatably mounted in the probe body and rotated simultaneously with the inspection head; and b. an eddy current coil mounted in a stationary position in the probe body and radially spaced from said encoder wheel whereby the changing air gap between said eddy current coil and said encoder wheel produces a variable electrical signal from said eddy current coil that is representative of the rotational angular position of said inspection head.
2. A method for determining the rotational position of an inspection rotatably head mounted on a probe body as the inspection head is rotated, comprising:
a. simultaneously rotating a spiral shaped encoder wheel with the inspection head;
b. receiving a variable electrical signal from an eddy current coil mounted in a stationary position in the probe body and radially spaced from the spiral encoder wheel where the variable electrical signal is representative of the rotational angular position of the inspecton head.
a. simultaneously rotating a spiral shaped encoder wheel with the inspection head;
b. receiving a variable electrical signal from an eddy current coil mounted in a stationary position in the probe body and radially spaced from the spiral encoder wheel where the variable electrical signal is representative of the rotational angular position of the inspecton head.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US74923891A | 1991-08-23 | 1991-08-23 | |
| US749,238 | 1991-08-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2068795A1 true CA2068795A1 (en) | 1993-02-24 |
Family
ID=25012873
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2068795 Abandoned CA2068795A1 (en) | 1991-08-23 | 1992-05-15 | Rotational position sensor |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH05209711A (en) |
| CA (1) | CA2068795A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9267819B2 (en) | 2014-06-12 | 2016-02-23 | Mitutoyo Corporation | Absolute position encoder scale having plates alternating with varying recesses |
| US9435663B2 (en) | 2014-08-22 | 2016-09-06 | Mitutoyo Corporation | Absolute position encoder scale having layers in a stacked configuration |
| CN112729102A (en) * | 2020-12-30 | 2021-04-30 | 维沃移动通信有限公司 | Electronic equipment and folding angle detection method thereof |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4390348B2 (en) * | 1999-03-15 | 2009-12-24 | 株式会社アミテック | Rotary position detector |
| JP2006023172A (en) * | 2004-07-07 | 2006-01-26 | Ntn Corp | Absolute angle detection rotary sensor and bearing with sensor using the same |
-
1992
- 1992-05-15 CA CA 2068795 patent/CA2068795A1/en not_active Abandoned
- 1992-07-28 JP JP21957892A patent/JPH05209711A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9267819B2 (en) | 2014-06-12 | 2016-02-23 | Mitutoyo Corporation | Absolute position encoder scale having plates alternating with varying recesses |
| US9435663B2 (en) | 2014-08-22 | 2016-09-06 | Mitutoyo Corporation | Absolute position encoder scale having layers in a stacked configuration |
| CN112729102A (en) * | 2020-12-30 | 2021-04-30 | 维沃移动通信有限公司 | Electronic equipment and folding angle detection method thereof |
| CN112729102B (en) * | 2020-12-30 | 2022-05-27 | 维沃移动通信有限公司 | Electronic equipment and folding angle detection method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05209711A (en) | 1993-08-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |