JP2015059779A - Rotary encoder and micrometer including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary encoder whose structure can be simplified and whose size can be miniaturized.SOLUTION: The rotary encoder includes: a cylindrical rotor 5; and stators 6 arranged at a predetermined interval so as to cover a peripheral surface of the rotor 5. The rotor 5 has patterns 51 disposed so as to be repeated along a circumferential direction at a first cycle λ1 and to be repeated along a shaft direction at a second cycle λ2 different from the first cycle λ1. The stators 6 detect a first signal received at the first cycle λ1 accompanying rotation of the rotor 5 in the circumferential direction, and they detect a second signal received at the second cycle λ2 accompanying advance/retreat movement of the rotor 5 in the shaft direction. Then, the rotary encoder detects an absolute position of a rotational angle of the rotor 5 by synthesizing the first signal and the second signal.

Description

  The present invention relates to an absolute rotary encoder and a micrometer including the same.

2. Description of the Related Art Conventionally, an absolute rotary encoder that includes a rotor that rotates about a central axis in accordance with an input rotation and detects the rotation angle of the rotor is known.
For example, a rotary encoder described in Patent Document 1 includes a disk-shaped first rotor that rotates around a central axis, and a disk that is provided concentrically outside the first rotor and that rotates around the central axis. And a relay gear as rotation transmission means for rotating the first rotor and the second rotor at different speeds according to the input rotation. The rotary encoder detects the absolute position of the input rotation angle based on the difference in rotation speed between the first rotor and the second rotor.

JP 2011-085504 A

  However, since the rotary encoder described in Patent Document 1 rotates the first rotor and the second rotor at different speeds via the relay gear, the structure of the rotary encoder becomes complicated. There is a problem that the size of the rotary encoder is increased.

  An object of the present invention is to provide a rotary encoder capable of simplifying the structure and reducing the size and a micrometer including the rotary encoder.

  A rotary encoder according to the present invention is an absolute rotary encoder that includes a rotor that rotates about a central axis in accordance with an input rotation and detects a rotation angle of the rotor, and has a cylindrical circumferential surface of the rotor The rotor is arranged at a predetermined interval so as to cover the rotor, and the rotor repeats along the circumferential direction in the first cycle and along the axial direction at a second cycle different from the first cycle. Having a pattern provided on its peripheral surface in such a manner that it is configured to advance and retreat along the axial direction as it rotates, and the stator transmits a signal toward the rotor; And a receiver that receives the signal transmitted by the transmitter via a pattern provided on the rotor, and the rotary encoder receives the first cycle as the rotor rotates in the circumferential direction. And the signal, by combining the second signal received by the second period with the advance and retreat in the axial direction of the rotor, and detects the absolute position of the rotation angle of the rotor.

  According to such a configuration, the cylindrical rotor repeats along the circumferential direction in the first cycle, and repeats along the axial direction in the second cycle different from the first cycle. It has a pattern provided on the peripheral surface, and is configured to advance and retreat along the axial direction as it rotates. The stator receives a first signal received at a first period as the rotor rotates in the circumferential direction, and a second signal received at a second period as the rotor advances and retreats in the axial direction. Can be detected respectively. Therefore, the rotary encoder detects the absolute position of the rotation angle of the rotor by synthesizing the first signal and the second signal, so that a new component such as a gear is not required. Can be simplified and the size can be reduced.

  In the present invention, the stator includes a first stator that detects a first signal and a second stator that detects a second signal. The first stator and the second stator are shafts of the rotor. It is preferable that they are provided at different positions.

  According to such a configuration, the first stator that detects the first signal and the second stator that detects the second signal are provided at different positions in the axial direction of the rotor. Interference with the second signal can be suppressed. Therefore, according to the rotary encoder of the present invention, the detection accuracy of the rotation angle of the rotor can be improved.

  In the present invention, each of the first stator and the second stator has a plurality of transmitter and receiver sets, and each of the transmitter and receiver sets in the first stator has a second period. Are provided so as to repeat along the axial direction at different periods, and each of the transmitter and receiver pair in the second stator is repeated along the circumferential direction at a period different from the first period. It is preferable to be provided.

  Here, if each of the pair of the transmitter and the receiver in the first stator is provided so as to repeat along the axial direction in the second period, the transmitter and the receiver are positioned at positions corresponding to the pattern formed on the rotor. If there is a set of machines, a large signal can be obtained by adding the signals detected by the receiver. If a large signal can be obtained, the S / N ratio can be increased, so that the detection accuracy of the rotation angle of the rotor can be further improved.

However, if there is no transmitter / receiver pair at a position corresponding to the pattern formed on the rotor due to the advance / retreat of the rotor in the axial direction, it is large even if the signal detected by the receiver is added. Since the signal cannot be obtained, there is a problem that the strength of the signal varies depending on the position of the rotor in the axial direction.
The same applies to the case where each pair of the transmitter and the receiver in the second stator is provided so as to be repeated along the circumferential direction in the first period, and the signal strength depends on the rotation angle of the rotor. There is a problem that is different.

  According to the present invention, each of the transmitter and receiver pair in the first stator is provided so as to repeat along the axial direction at a period different from the second period, and the transmitter in the second stator. Since each of the receiver sets is provided so as to repeat along the circumferential direction with a period different from the first period, the signal strength corresponding to the axial position of the rotor and the rotation angle of the rotor is set. Variations can be suppressed. Therefore, according to the present invention, it is possible to improve the detection accuracy of the rotary encoder while suppressing fluctuations in the intensity of the signal according to the axial position of the rotor and the rotation angle of the rotor.

  The micrometer of the present invention includes a spindle that rotates around the central axis in accordance with the input rotation and advances and retreats along the axial direction along with this rotation, and by detecting the rotation angle of the spindle, A micrometer for measuring an axial displacement, comprising the rotary encoder described above, wherein the rotor is provided integrally with the spindle.

  According to such a configuration, since the micrometer includes the above-described rotary encoder, the same operational effects as the above-described rotary encoder can be achieved.

  In the present invention, the screw pitch of the spindle is p, the number of patterns provided on the circumferential surface of the rotor so as to repeat along the circumferential direction is B, and the measurement range of the micrometer is an integer n times the fundamental wavelength p / B. When the second period λ is larger than the fundamental wavelength p / B, the second period λ is designed so as to satisfy the relationship of λ = n / (n−1) · p / B. When the second period λ is smaller than the fundamental wavelength p / B, it is preferable to design the second period λ so as to satisfy the relationship of λ = n / (n + 1) · p / B.

According to such a configuration, when the second period λ is larger than the fundamental wavelength p / B, the second period λ is satisfied so as to satisfy the relationship of λ = n / (n−1) · p / B. When designing λ and making the second period λ smaller than the fundamental wavelength p / B, the second period λ is designed so as to satisfy the relationship of λ = n / (n + 1) · p / B. The second period λ can be appropriately designed according to the measurement range of the micrometer.
The first period may be designed based on the rotor diameter and the number B of patterns.

The perspective view which shows the inside of the micrometer which concerns on one Embodiment of this invention. Enlarged perspective view of the rotor Schematic diagram of the rotor and stator deployed in a planar shape The figure which shows the state which provided the 2nd stator with the 1st period. The figure which shows the state which rotated the rotor by the half period of the 1st period in the circumferential direction The figure which shows the state which provided the 2nd stator with the period of 3/2 times the 1st period. The figure which shows the state which rotated the rotor by the half period of the 1st period in the circumferential direction

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing the inside of a micrometer according to an embodiment of the present invention.
As shown in FIG. 1, the micrometer 1 rotates around the central axis according to the input rotation, and accommodates the spindle 2 that advances and retreats along the axial direction along with this rotation, and the spindle 2 inside. And a frame 3. The micrometer 1 measures the axial displacement of the spindle 2 by detecting the rotation angle of the spindle 2, and measures the dimension of the object to be measured sandwiched between the spindle 2 and an anvil (not shown). It is a measuring instrument.
FIG. 1 illustrates only the vicinity of the spindle 2 and exposes the spindle 2 by transmitting a part of the frame 3.

The micrometer 1 includes an absolute rotary encoder 4 that detects the rotation angle of the spindle 2.
The rotary encoder 4 is provided integrally with the spindle 2 so as to rotate around the central axis according to the input rotation, and to advance and retract along the axial direction along with the rotation, And a stator 6 made of a flexible substrate disposed at a predetermined interval so as to cover the peripheral surface of the rotor 5.

FIG. 2 is an enlarged perspective view of the rotor 5.
As shown in FIG. 2, the rotor 5 has a pattern 51 provided on its peripheral surface. In other words, the pattern 51 is formed on the rotor 5 formed of a flexible substrate wound so as to cover the peripheral surface of the spindle 2. Specifically, the pattern 51 is a plurality of rectangular scale coils provided in a lattice shape along the circumferential direction and the axial direction of the rotor 5.

FIG. 3 is a schematic diagram in which the rotor 5 and the stator 6 are developed in a plane. In FIG. 3, the vertical direction of the paper surface is the circumferential direction of the rotor 5 and the stator 6, and the horizontal direction of the paper surface is the axial direction of the rotor 5 and the stator 6.
As shown in FIG. 3, the rotor 5 is provided so as to repeat along the circumferential direction in the first cycle λ1 and to repeat along the axial direction in a second cycle λ2 different from the first cycle λ1. A pattern 51 is provided.
Note that the length in the circumferential direction of the pattern 51 is λ1 / 2, and the length in the axial direction is λ2 / 2.

  Here, in the second period λ2, the screw pitch of the spindle 2 is p, the number of patterns 51 provided on the peripheral surface of the spindle 2 so as to repeat along the circumferential direction is B, and the measurement range of the micrometer 1 Is set to be an integer n times the fundamental wavelength p / B, the second period λ2 is designed so as to satisfy the relationship of the following equation when it is made larger than the fundamental wavelength p / B.

λ2 = n / (n−1) · p / B

  Further, when the second period λ2 is made smaller than the fundamental wavelength p / B, it is designed so as to satisfy the relationship of the following equation.

λ2 = n / (n + 1) · p / B

  In the present embodiment, the number B of patterns 51 provided on the peripheral surface of the rotor 5 is set to 6 so as to repeat along the circumferential direction at the first period λ1. In other words, in the present embodiment, the first period λ1 is 60 degrees. In this embodiment, λ1 <λ2.

  The stator 6 includes a first stator 61 (on the left side of the drawing) that detects a first signal received at a first period λ1 as the rotor 5 rotates in the circumferential direction, and an advance and retreat of the rotor 5 in the axial direction. And a second stator 62 (right side of the drawing) for detecting a second signal received at the second period λ2. That is, the first stator 61 and the second stator 62 are respectively provided at different positions in the axial direction of the rotor 5.

The first stator 61 is provided along its own circumferential direction (up and down direction in the drawing), and is transmitted by four transmitters 61A (61A1 to 61A4) that transmit signals toward the rotor 5 and the transmitter 61A. 4 receivers 61 </ b> B (61 </ b> B <b> 1 to 61 </ b> B <b> 4) that receive the received signal via a pattern 51 provided on the rotor 5.
The second stator 62 is provided along its own axial direction (left and right direction in the drawing), and is transmitted by four transmitters 62A (62A1 to 62A4) that transmit signals toward the rotor 5 and the transmitter 62A. 4 receivers 62 </ b> B (62 </ b> B <b> 1 to 62 </ b> B <b> 4) that receive the received signal via a pattern 51 provided on the rotor 5.
The transmitters 61A and 62A are excitation coils (one-loop coils) formed by winding one winding respectively, and the receivers 61B and 62B are respectively wound by winding one winding. It is a detection coil (twisted pair coil) to be formed.

  Thus, the 1st stator 61 and the 2nd stator 62 have a set of a plurality of transmitters 61A and 62A and receivers 61B and 62B, respectively. For example, when a current is passed through the transmitter 61A1, an electromotive current is generated in the pattern 51 of the rotor 5, and an electromotive current is generated in the receiver 61B1. That is, in this embodiment, the rotary encoder 4 is configured as an electromagnetic induction rotary encoder.

  Here, each of the set of the transmitter 61A and the receiver 61B in the first stator 61 is provided so as to repeat along the axial direction at a period different from the second period λ2. Specifically, each of the set of the transmitter 61A and the receiver 61B in the first stator 61 is provided so as to repeat along the axial direction at a period 3/2 times the second period λ2. . Note that other periods may be adopted as long as the period is different from the second period λ2.

  Each set of the transmitter 62A and the receiver 62B in the second stator 62 is provided so as to repeat along the circumferential direction at a period different from the first period λ1. Specifically, each of the set of the transmitter 62A and the receiver 62B in the second stator 62 is provided so as to repeat along the circumferential direction at a period 3/2 times the first period λ1. . Note that other periods may be adopted as long as the period is different from the first period λ1.

FIG. 4 is a diagram illustrating a state in which each of the set of the transmitter 62A and the receiver 62B in the second stator 62 is provided so as to repeat along the circumferential direction at the first period λ1. In FIG. 4, two sets of transmitters 62A and receivers 62B are shown for explanation. The same applies to the following drawings.
When each of the set of the transmitter 62A and the receiver 62B in the second stator 62 is provided so as to be repeated along the circumferential direction at the first period λ1, a pattern formed on the rotor 5 as shown in FIG. When there is a pair of the transmitter 62A and the receiver 62B at a position corresponding to 51, a large signal can be obtained by adding the signals detected by the receiver 62B.

FIG. 5 is a diagram illustrating a state in which the rotor 5 is rotated in the circumferential direction by a half cycle of the first cycle λ1.
On the other hand, as shown in FIG. 5, the rotor 5 rotates in the circumferential direction by a half period of the first period λ1, so that the transmitter 62A and the position corresponding to the pattern 51 formed on the rotor 5 If there is no set of receivers 62B, a large signal cannot be obtained even if the signals detected by the receiver 62B are added, so that the signal strength varies depending on the circumferential position of the rotor 5. There is a problem that it ends up.

FIG. 6 is a diagram showing a state in which the set of the transmitter 62A and the receiver 62B in the second stator 62 is provided so as to be repeated along the circumferential direction at a period 3/2 times the first period λ1. It is. FIG. 7 is a view showing a state in which the rotor 5 is rotated in the circumferential direction by a half cycle of the first cycle λ1.
In the present embodiment, as shown in FIG. 6, each of the set of the transmitter 62A and the receiver 62B in the second stator 62 repeats along the circumferential direction at a period 3/2 times the first period λ1. As shown in FIG. 7, even if the rotor 5 is rotated by a half cycle of the first cycle λ1 in the circumferential direction, it corresponds to the pattern 51 formed on the rotor 5 as shown in FIG. There may be a pair of a transmitter 62A and a receiver 62B at a position to be transmitted. Specifically, in FIG. 6, the pair of the transmitter 62A and the receiver 62B in the lower part of the figure is in a position corresponding to the pattern 51, and in FIG. 7, the pair of the transmitter 62A and the receiver 62B in the upper part of the figure is It is at a position corresponding to the pattern 51.

  The rotary encoder 4 receives the first signal received at the first period λ1 as the rotor 5 rotates in the circumferential direction and the second signal λ2 as the rotor 5 advances and retreats in the axial direction. The absolute position of the rotation angle of the rotor 5 is detected by combining the second signal. Further, the rotary encoder 4 detects the absolute position of the rotation angle of the rotor 5 and detects the absolute position of the rotation angle of the spindle 2, thereby measuring the axial displacement of the spindle 2 and measuring the dimension of the object to be measured. taking measurement.

According to the present embodiment as described above, the following operations and effects can be achieved.
(1) The cylindrical rotor 5 repeats along the circumferential direction at the first cycle λ1 and repeats along the axial direction at the second cycle λ2 different from the first cycle λ1. It has a pattern 51 provided on the surface, and is configured to advance and retreat along the axial direction as it rotates. The stator 6 is received at the first period λ1 as the rotor 5 rotates in the circumferential direction, and at the second period λ2 as the rotor 5 advances and retreats in the axial direction. Each of the second signals can be detected. Therefore, the rotary encoder 4 detects the absolute position of the rotation angle of the rotor 5 by synthesizing the first signal and the second signal, so that a new component such as a gear is not required. The structure can be simplified and the size can be reduced.

(2) The rotary encoder 4 is provided with the first stator 61 that detects the first signal and the second stator 62 that detects the second signal at different positions in the axial direction of the rotor 5. Interference between the first signal and the second signal can be suppressed. Therefore, according to the rotary encoder 4, the detection accuracy of the rotation angle of the rotor 5 can be improved.
(3) Each of the set of the transmitter 61A and the receiver 61B in the first stator 61 is provided so as to repeat along the axial direction at a period different from the second period λ2, and in the second stator 62 Each of the pair of the transmitter 62A and the receiver 62B is provided so as to repeat along the circumferential direction with a period different from the first period λ1, so that the position of the rotor 5 in the axial direction and the rotation angle of the rotor 5 are set. The fluctuation of the corresponding signal strength can be suppressed. Therefore, according to the rotary encoder 4, it is possible to improve the detection accuracy of the rotary encoder 4 while suppressing fluctuations in the signal strength according to the axial position of the rotor 5 and the rotation angle of the rotor 5.

(4) When the second period λ2 is larger than the fundamental wavelength p / B, the rotary encoder 4 has a second period so as to satisfy the relationship of λ2 = n / (n−1) · p / B. When designing λ2 and making the second period λ2 smaller than the fundamental wavelength p / B, the second period λ2 is designed to satisfy the relationship of λ2 = n / (n + 1) · p / B. The second period λ2 can be appropriately designed according to the measurement range of the micrometer 1.

[Modification of Embodiment]
Note that the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within a scope in which the object of the present invention can be achieved are included in the present invention.
For example, in the above-described embodiment, the rotary encoder 4 is configured as an electromagnetic induction rotary encoder, but may be configured as a capacitive rotary encoder.

  In the embodiment, the stator 6 includes the first stator 61 and the second stator 62, and the first stator 61 and the second stator 62 are respectively provided at different positions in the axial direction of the rotor 5. However, the first stator and the second stator may be provided at the same position in the axial direction of the rotor so as to overlap each other. According to such a configuration, interference between the first signal and the second signal is increased, but the size of the rotary encoder can be reduced.

  In the embodiment described above, each of the set of the transmitter 61A and the receiver 61B in the first stator 61 is provided so as to repeat along the axial direction at a period different from the second period λ2. It may be provided so as to repeat along the axial direction with a period. In the embodiment, each of the pair of the transmitter 62A and the receiver 62B in the second stator 62 is provided so as to repeat along the circumferential direction at a period different from the first period λ1. These may be provided so as to repeat along the circumferential direction at the same cycle.

  In the above embodiment, when the second period λ2 is made larger than the fundamental wavelength p / B, the rotary encoder 4 satisfies the relationship of λ2 = n / (n−1) · p / B. When the second period λ2 is set to be smaller than the fundamental wavelength p / B, the second period λ2 is designed to satisfy the relationship of λ2 = n / (n + 1) · p / B. However, it does not have to be designed in this way. In short, the rotor has a pattern provided on its peripheral surface so as to repeat along the circumferential direction in the first cycle and repeat along the axial direction in a second cycle different from the first cycle. It only has to be.

  In the embodiment, the first stator 61 includes four transmitters 61A and four receivers 61B, and the second stator 62 includes four transmitters 62A and four receivers 62B. Other numbers of transmitters and receivers may be provided. In short, the stator only needs to have a transmitter that transmits a signal toward the rotor and a receiver that receives the signal transmitted by the transmitter via a pattern provided on the rotor.

  In the above embodiment, the rotary encoder 4 is employed in the micrometer 1, but it may be employed in a measuring instrument other than the micrometer or may be employed in other industrial equipment other than the measuring instrument.

  As described above, the present invention can be suitably used for an absolute rotary encoder and a micrometer including the same.

1 Micrometer 2 Spindle 3 Frame 4 Rotary encoder 5 Rotor 6 Stator 51 Pattern 61 First stator 62 Second stator 61A, 62A Transmitter 61B, 62B Receiver λ1 First cycle λ2 Second cycle

Claims (5)

An absolute rotary encoder that includes a rotor that rotates about a central axis in response to an input rotation, and that detects a rotation angle of the rotor;
A stator disposed at a predetermined interval so as to cover the circumferential surface of the rotor formed in a columnar shape;
The rotor has a pattern provided on its peripheral surface so as to repeat along the circumferential direction at a first period and along the axial direction at a second period different from the first period, It is configured to advance and retract along the axial direction with its rotation,
The stator is
A transmitter for transmitting a signal toward the rotor;
A receiver for receiving a signal transmitted by the transmitter via a pattern provided in the rotor;
The rotary encoder receives a first signal received in the first cycle as the rotor rotates in the circumferential direction, and a second signal received in the second cycle as the rotor advances and retreats in the axial direction. A rotary encoder that detects the absolute position of the rotation angle of the rotor by combining the two signals. The rotary encoder according to claim 1,
The stator is
A first stator for detecting the first signal;
A second stator for detecting the second signal;
The rotary encoder, wherein the first stator and the second stator are provided at different positions in the axial direction of the rotor. The rotary encoder according to claim 2, wherein
The first stator and the second stator each have a plurality of sets of the transmitter and the receiver,
Each set of the transmitter and the receiver in the first stator is provided so as to repeat along the axial direction at a period different from the second period, and the transmitter in the second stator Each of the receiver sets is provided so as to repeat along the circumferential direction with a period different from the first period. A spindle that rotates about the central axis according to the input rotation and advances and retreats along the axial direction along with this rotation, and detects the rotation angle of the spindle, thereby detecting the axial displacement of the spindle. A micrometer to measure,
A rotary encoder according to any one of claims 1 to 3, comprising:
The micrometer, wherein the rotor is provided integrally with the spindle. The micrometer according to claim 4, wherein
The screw pitch of the spindle is p, the number of patterns provided on the circumferential surface of the rotor is B along the circumferential direction, and the measurement range of the micrometer is an integer n times the fundamental wavelength p / B. When
When making the second period λ larger than the fundamental wavelength p / B,
λ = n / (n−1) · p / B
The first period λ is designed to satisfy the relationship:
When making the second period λ smaller than the fundamental wavelength p / B,
λ = n / (n + 1) · p / B
The micrometer is characterized in that the second period λ is designed so as to satisfy the following relationship.

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