JP4533165B2 - Absolute position measuring device - Google Patents

Description

  The present invention relates to an absolute position measuring apparatus. For example, the present invention relates to an absolute position measuring apparatus that measures the position of a spindle in an absolute type in a micrometer head, a micrometer, a hall test, or the like.

Conventionally, in a small measuring instrument that measures length, size, angle, etc., for example, a micrometer or a micrometer head, measurement of the measurement target is performed by detecting information on the relative movement amount of the movable member with respect to the fixed member. Is done.
As a configuration for detecting the relative movement amount of the movable member with respect to the fixed member, for example, there is a configuration disclosed in Patent Document 1.

FIG. 6 is a diagram showing an embodiment disclosed in Patent Document 1. As shown in FIG.
This embodiment is a micrometer head 1, and a movable body having a main body 2 having a female screw 22 on the inner periphery of a through hole 21 and a feed screw 31 inserted into the through hole 21 of the main body 2 and screwed into the female screw 22. The absolute position of the spindle 3 is calculated based on the spindle 3 as a member, the phase signal transmission means 4 for outputting phase signals of two different periods according to the movement of the spindle 3, and the output signal from the phase signal transmission means 4 And a display means 6 for displaying the absolute position of the spindle 3 calculated by the arithmetic processing means 5.

The spindle 3 can be moved back and forth. A knob 32 is provided at the rear end of the spindle 3. When the spindle 3 is rotated with respect to the main body 2 by the knob 32, the female screw 22 and the feed screw 31 are provided. The spindle 3 is advanced and retracted in the axial direction by screwing.
The spindle 3 is provided with two key grooves 33, 34, the first key groove 33 is provided in a straight line parallel to the axis of the spindle 3, and the second key groove 34 is located with respect to the spindle 3. It is provided in a spiral.

  The phase signal transmission means 4 is composed of two sets of rotary encoders. One stator 41 fixed to the main body 2 and two sheets disposed on both sides of the stator 41 with the stator 41 in between. And rotors 42 and 45.

  The stator 41 and the rotors 42, 45 have holes through which the spindle 3 is inserted, and the two rotors 42, 45 are provided outside the rotating cylinders 43, 46 that can rotate independently with respect to the spindle 3. Keys 44 and 47 that engage with the key grooves 33 and 34 of the spindle 3 are provided on the inner periphery of the rotary cylinders 43 and 46, respectively. Here, it is assumed that the first rotor 42 is provided in the first rotating cylinder 43, and the key 44 of the first rotating cylinder 43 is engaged with the first key groove 33. The second rotor 45 is provided in the second rotating cylinder 46, and the key 47 of the second rotating cylinder 46 is engaged with the second key groove 34.

  In addition, coil springs (not shown) are disposed between the two rotating cylinders 43 and 46 and the inner wall of the main body 2, and the two rotors 42 and 45 are biased toward the stator 41, whereby the stator 41. And the rotors 42 and 45 are close to each other, and the gap is maintained.

  The two key grooves 33 and 34 are provided so that the difference in rotational phase obtained from the two rotors 42 and 45 in the movable range of the spindle 3 is always different. When a phase change of 100 cycles is obtained from one rotor 42, a phase change of 99 cycles is obtained from the second rotor 45. FIG. 7 shows an example of the relationship between the rotation speed of the spindle 3 and the phase signal obtained from the two rotors 42 and 45.

In such a configuration, when the spindle 3 is rotated, the spindle 3 is advanced and retracted in the axial direction.
At the same time, when the spindle 3 is rotated, the keys 44 and 47 of the two rotating cylinders 43 and 46 are engaged with the key grooves 33 and 34 of the spindle 3, respectively. It is rotated according to the rotation of the grooves 33 and 34. Then, the rotors 42 and 45 are rotated together with the rotating cylinders 43 and 46.
Since the difference between the phase signals obtained from the two rotors 42 and 45 is always different within the movable range of the spindle 3, the absolute position of the spindle 3 is calculated from the phase difference between the two rotors 42 and 45.

  As for the method for calculating the absolute position of the spindle 3 from the phase difference between the two rotors 42 and 45, the arithmetic processing means 5 stores in advance the relationship between the phase difference between the two rotors 42 and 45 and the absolute position of the spindle 3. Alternatively, the absolute position of the spindle 3 may be calculated from the phase difference between the rotors 42 and 45. Alternatively, the rotation speed of the spindle 3 is calculated by dividing the detected phase difference between the two rotors 42 and 45 by the phase difference caused by one rotation of the spindle 3, and the spindle calculated as the pitch per one rotation of the spindle 3. The spindle absolute position may be calculated by multiplying the number of rotations.

FIG. 8 shows another embodiment disclosed in Patent Document 1.
In this embodiment, two stators 41A and 41B are provided, and two rotors 42 and 45 are provided between the two stators 41A and 41B. That is, the first rotor 42 is provided facing the first stator 41A, the second rotor 45 is provided facing the second stator 41B, and the first rotor 42 and the second rotor 45 are connected to the first stator 41A and the first stator 41A. It is provided so as to be sandwiched between the two stators 41B.

JP 2003-207307 A (FIG. 1, FIG. 6, paragraphs (0038) to (0045), paragraph (0057))

However, in the configuration disclosed in FIG. 6, two rotors 42 and 45 are arranged with one stator 41 interposed therebetween, so that the rotating cylinders 43 and 46 are arranged to rotate the rotors 42 and 45. The positions of the two keys 44 and 47 provided respectively are separated in the axial direction of the spindle 3 (L _{1 in} FIG. 6).

Since the two key grooves 33 and 34 that can be engaged with the two keys 44 and 47 that are separated in the spindle axial direction must be cut in the spindle 3 in this way, the starting point of each key groove 33 and 34 is large. will be shifted, range L ₂ engrave keyway 33 consequently becomes possible widespread spindle axis. In order to prevent inconvenience such as dust entering the micrometer head 1, the spindle 3 is covered with a frame 24 so that the key grooves 33 and 34 of the spindle 3 are not exposed to the outside even when the spindle 3 advances and retreats. since there must, correspondingly, the shorter the length L ₃ of the spindle 3 which projects from the frame 24, as a result, a problem that measurement range is narrowed occurs.

  On the other hand, in order to increase the length measurement range, the spindle 3 must be further projected from the frame 24 after the spindle 3 is covered with the frame 24 so that the key grooves 33 and 34 are not exposed. There arises a problem that the head 1 becomes very large.

  Further, in order to urge the two rotors 42 and 45 toward the stator 41, two coil springs (not shown) are required, so that a gap with the stator 41 is maintained from both sides of the single stator 41. Further, it is difficult to energize the two rotors 42 and 45 with two coil springs (not shown), which causes a problem that the assembling work becomes very complicated.

Further, in the configuration disclosed in FIG. 8, since the two rotors 42 and 45 are disposed between the two stators 41A and 41B, the positions of the two rotors 42 and 45 can be brought close to each other. As a result, the positions of the keys 44 and 47 provided on the two rotating cylinders 43 and 46 can be brought close to each other, and the range in which the key grooves 33 and 34 are cut into the spindle 3 can be reduced.
However, since two stators 41A and 41B are required, the number of parts increases, and the assembling work for arranging the two rotors 42 and 45 between the two stators 41A and 41B becomes complicated, resulting in an increase in manufacturing cost. There is a problem that leads to.

  An object of the present invention is to provide an absolute position measuring device that is small in size and easy to assemble.

  An absolute position measuring device of the present invention includes a main body, a spindle screwed to the main body and capable of moving forward and backward in the axial direction by rotation and having a plurality of key grooves with different lead angles on the outer periphery, and Phase signal transmitting means for transmitting a plurality of phase signals having different periods according to the amount of movement; arithmetic processing means for calculating the phase signal to determine the absolute position of the spindle; and display means for displaying the absolute position; The phase signal transmitting means includes a stator fixed to the main body in a state where the spindle is inserted, a key that engages with the key groove, and is rotatable about the spindle. A plurality of rotors opposed to the stator, all of the plurality of rotors being disposed on one side of the stator, and the plurality of rotors being spindles Center are stacked in a direction perpendicular to the axis of the spindle as, a plurality of key grooves is characterized in that it is formed substantially in the same region in the axial direction of the spindle.

In such a configuration, when the spindle is rotated, the spindle is advanced and retracted in the axial direction by screwing with the main body.
At the same time, when the spindle is rotated, the plurality of rotors are rotated by the keys respectively engaged with the plurality of key grooves of the spindle. The rotational phases of the plurality of rotors are detected by the stator, and different phase signals are transmitted according to the rotational phases of the rotors.
These phase signals are arithmetically processed by the arithmetic processing unit, the absolute position of the spindle is calculated based on the rotational phase difference of each rotor, and the calculated spindle absolute position is displayed on the display means.

  Here, since the plurality of rotors are stacked and disposed in a direction perpendicular to the spindle axis with the spindle as the center, the range in which the rotor is disposed in the axial direction of the spindle is provided with one rotor Is very narrow. By providing a plurality of rotors in a narrow range in the spindle axis direction in this way, the positions of the keys provided in the respective rotors can be very close to each other in the spindle axis direction. A plurality of keys can also be provided.

  By providing a plurality of keys close to each other in the spindle axis direction, the start point and the end point of each of the plurality of key grooves provided on the spindle are close to each other. be able to.

  In particular, when there are three or more rotors, if a plurality of rotors are arranged in parallel along the spindle axis as in the prior art, the two rotors can be held close together by two stators. The remaining rotors are arranged at distant positions, and the key positions must be separated in the spindle axial direction, so that the range of the key grooves engraved on the spindle is widened. In this respect, by stacking a plurality of rotors in a direction perpendicular to the axial direction of the spindle as in the present invention, it is possible to reduce the range in which the key groove is engraved on the spindle by bringing all the key positions close to each other.

In this way, the measuring device can be downsized because the range in which the keyway is carved into the spindle can be narrowed.
In addition, the area excluding the part where the keyway is formed from the spindle can be used as the length measurement range, but the range in which the keyway is engraved on the spindle can be narrowed, so the length of the spindle that can be used as the length measurement range is increased. The length measurement range can be widened.

  Further, since a single stator is sufficient for obtaining a plurality of different phase signals, the number of parts can be reduced as compared with the case where the stators are provided in pairs with all the rotors. Since all the rotors are arranged on one side of one stator, the assembling work becomes simpler than when the rotor is urged from both sides of the stator. As a result, component costs and assembly costs can be reduced, and manufacturing costs can be reduced.

  In the present invention, each of the plurality of rotors includes a rotor plate that is paired with the stator and is rotated in a state of facing the stator, and a rotating cylinder that supports rotation of the rotor plate around the spindle. It is preferable that all the rotating cylinders rotate with the outer peripheral surface of the spindle as a reference surface.

  In this configuration, since the spindle is generally formed straight and the outer peripheral surface thereof is finished in a perfect circle, each rotating cylinder rotates with respect to the outer peripheral surface of the spindle as a reference to prevent rotation of the rotating cylinder from rotating. Each rotating cylinder rotates stably. Then, the rotation of the rotor plate supported by the rotating cylinder is also stabilized, so that the rotation amount of the spindle is accurately transmitted to each rotor plate. Then, the absolute position of the spindle is accurately detected by detecting the rotational phase of each rotor plate by the stator.

  In the present invention, as the plurality of rotors, a first rotor having a first rotor plate and a first rotating cylinder, and a second rotor plate and a second rotating cylinder are provided so as to be rotatable outside the first rotor. It is preferable that a second rotor is provided.

  According to such a configuration, the first rotating cylinder of the first rotor can rotate on the basis of the spindle, and the second rotating cylinder also rotates on the basis of the spindle. As a result, the rotation of the first rotor and the second rotor is stabilized, and the rotation amount of the spindle is accurately transmitted to each rotor plate. Then, the absolute position of the spindle is accurately detected by detecting the rotational phase of each rotor plate by the stator.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be illustrated and described with reference to reference numerals attached to respective elements in the drawings.
(First embodiment)
A first embodiment according to the absolute position measuring apparatus of the present invention will be described.
FIG. 1 is a cross-sectional view showing a configuration of a micrometer head as a first embodiment of an absolute position measuring apparatus.
The micrometer head 100 transmits a plurality of phase signals with different periods according to the amount of movement of the main body 110, the spindle 200 that is screwed to the main body 110 and is provided so as to be able to advance and retreat in the axial direction by rotation. A phase signal transmission means 300 for calculating the absolute position of the spindle 200 by calculating the phase signal, and a display means 800 for displaying the calculated absolute position of the spindle 200.

The main body 110 has a cylindrical shape having a through hole 120, and a female screw 121 is provided on the inner periphery of the through hole 120.
In the through hole 120, an intermediate partition plate 122 that partitions the storage space 123 is provided. Further, the outer periphery on the front end side of the main body 110 is covered with an outer frame 130.

  The spindle 200 is disposed in a state where both ends protrude from the main body 110 through the through hole 120 of the main body 110. A feed screw 210 that is screwed into the female screw 121 of the main body 110 is provided on the outer periphery on the rear end side of the spindle 200, and can be advanced and retracted in the axial direction by a rotating operation. A knob portion 220 that rotates the spindle 200 from the outside of the main body 110 is provided at the rear end of the spindle 200.

  Two key grooves 230 and 240 having different lead angles are provided at the center of the spindle 200. The first key groove 230 is provided in a straight line parallel to the axis of the spindle 200, and the second key groove 240 is provided. Is provided spirally with respect to the spindle 200. The positions of the start point and the end point of the first key groove 230 and the second key groove 240 are substantially the same in the axial direction of the spindle 200, that is, the first key groove 230 and the second key groove 240 are in the axis of the spindle 200. They are formed in substantially the same range in the direction.

  When the spindle 200 advances and retreats, the key grooves 230 and 240 come out of the main body 110 together with the spindle 200. However, even when the spindle 200 advances to the maximum extent, the key grooves 230 and 240 are not exposed to the outside. Thus, an outer frame 130 is provided.

The phase signal transmission means 300 will be described.
First, the configuration of the phase signal transmission means 300 will be described.
FIG. 2 is an exploded perspective view of the phase signal transmission means 300.
The phase signal transmission means 300 is disposed in the storage space 123 of the main body 110, the stator 400 fixed to the front end side inner wall 140 of the storage space 123 with the spindle 200 inserted, and the key grooves 230, 240. And two rotors 500 and 600 that have keys 530 and 630 that are engaged with each other and that are rotatable about the spindle 200.

  The two rotors 500 and 600 are both disposed on the same side with respect to the stator 400 and are disposed in a state of facing the stator 400. The two rotors 500 and 600 are stacked in a direction perpendicular to the axis of the spindle 200 with the spindle 200 as the center, the first rotor 500 is disposed just outside the spindle 200, and the second rotor 600 is It is laminated outside the first rotor 500.

The first rotor 500 is a first rotor plate 510 that rotates in a state of being opposed to the stator 400 in a pair with the stator 400, and a first rotating cylinder that supports the rotation of the first rotor plate 510 around the spindle 200. 520 and a first key 530 engaged with the first key groove 230.
The first rotor plate 510 is a small disk having a hole through which the spindle 200 is inserted.
The first rotating cylinder 520 has a cylindrical shape that is externally fitted to the spindle 200 and is connected to the back surface of the first rotor plate 510 to support the rotation of the first rotor plate 510. The first rotating cylinder 520 is provided with two holes penetratingly formed in a direction orthogonal to the axis, and the first key 530 is screwed into the first hole 521. The second hole 522 is formed in a long hole shape having a length in the circumferential direction of the first rotating cylinder 520.

  Similarly to the first rotor 500, the second rotor 600 includes a second rotor plate 610 that is paired with the stator 400 and is rotated in a state of facing the stator 400, and a second rotor plate 610 centered on the spindle 200. A second rotating cylinder 620 that supports the rotation and a second key 630 that engages with the second key groove 240 are provided.

The second rotor plate 610 is an annular plate having an inner hole enough to loosely fit the first rotor plate 510 inside.
The second rotating cylinder 620 is connected to the back surface of the second rotor plate 610 and has a cylindrical shape having a hole in which the first rotating cylinder 520 is loosely fitted.
The second rotating cylinder 620 has a hole 621 formed through from a direction orthogonal to the axis, and the second key 630 is screwed into the hole 621. The second key 630 is engaged with the second key groove 240 through the second hole 522 that is a long hole of the first rotating cylinder 520.

The second rotating cylinder 620 includes a bearing portion 622 that supports the spindle 200 on the opposite side of the stator 400 with the first rotor 500 interposed therebetween.
In the spindle axis direction, the position of the second key 630 is substantially the same as the position of the first key 530 provided on the first rotating cylinder 520.

  Note that a spindle bearing 141 extends slightly toward the rear end side of the stator 400 on the front end side inner wall 140 of the storage space 123 to which the stator 400 is fixed, and the spindle bearing 523 of the first rotating cylinder 520 is provided. The first rotor plate 510 is slightly extended toward the stator 400, and the spindle bearing 523 of the first rotating cylinder 520 contacts the spindle bearing 141 of the main body 110, so that the stator 400 and the first rotor plate 510 are connected. Gaps are appropriately secured.

  In addition, a coil spring (biasing means) (not shown) is interposed between the second rotating cylinder 620 and the partition plate 122 so that the second rotor 600 is biased toward the stator 400 and the first rotor. The first rotor 500 is also biased toward the stator 400 by pressing 500 on the inner wall of the second rotating cylinder 620.

Next, in the phase signal transmission unit 300, a configuration in which the rotation phase of the first rotor 500 and the second rotor 600 is detected by the stator 400 will be briefly described.
FIG. 3 is a diagram showing the opposing surfaces of the stator 400 and the rotor plate (the first rotor plate 510 and the second rotor plate 610).
FIG. 3A is a diagram illustrating one surface of the stator 400, and FIG. 3B is a diagram illustrating one surface of the first rotor plate 510 and the second rotor plate 610.

On the surface of the stator 400 that faces the rotor plate (the first rotor plate 510 and the second rotor plate 610), an electrode portion that is doubled on the inner side and the outer side is provided, that is, the first stator electrode on the inner side. A portion 410 is provided, and a second stator electrode portion 440 is provided outside the first stator electrode portion 410 (see FIG. 3A).
A surface of the first rotor plate 510 that faces the stator 400 is provided with a first coupling electrode portion 511 that electromagnetically couples with the first stator electrode portion 410, and a surface of the second rotor plate 610 that faces the stator 400 has a first surface. A second coupling electrode portion 611 that is electromagnetically coupled to the two stator electrode portions 440 is provided (see FIG. 3B).

  The first stator electrode portion 410 forms a first transmission electrode portion 420 composed of one electrode wire arranged in a ring shape, and a rhombus coil continuous at a predetermined pitch inside the first transmission electrode portion 420 3 And a first receiving electrode portion 430 that is composed of electrode wires 431, 432, and 433 and is arranged in a ring shape as a whole. Similarly, the second stator electrode portion 440 includes a second transmission electrode portion 450 made of one electrode wire arranged in a ring shape, and a diamond coil continuous at a predetermined pitch inside the second transmission electrode portion 450, respectively. And a second receiving electrode portion 460 that is formed of three electrode wires 461, 462, and 463 to be formed and arranged in a ring shape as a whole.

  In such a configuration, when the first rotor 500 and the second rotor 600 are respectively rotated, the respective rotation phases are based on the overlapping pattern of the coupling electrode portions (511, 611) and the receiving electrode portions (430, 460). It is determined by the arithmetic processing in the arithmetic processing means 700.

The operation of the first embodiment having such a configuration will be described.
When the spindle 200 is rotated by the knob portion 220, the spindle 200 is advanced and retracted in the axial direction by screwing between the female screw 121 of the main body 110 and the feed screw 210 of the spindle 200.

  When the spindle 200 is rotated, the first key groove 230 and the second key groove 240 of the spindle 200 are associated with the first key 530 of the first rotating cylinder 520 and the second key 630 of the second rotating cylinder 620, respectively. Thus, the first rotating cylinder 520 and the second rotating cylinder 620 are rotated as the spindle 200 rotates. At this time, since the first rotating cylinder 520 supports the spindle 200 by the spindle bearing 523, the first rotating cylinder 520 rotates with respect to the spindle 200. Further, since the second rotating cylinder 620 supports the spindle 200 by the bearing portion 622, the second rotating cylinder 620 also rotates with respect to the spindle 200.

  Since the first key groove 230 and the second key groove 240 have different lead angles, the first rotating cylinder 520 and the second rotating cylinder 620 have different rotation amounts (rotations) when the spindle 200 makes one rotation. Phase). When the first and second rotating cylinders 520 and 620 are rotated by the rotation of the spindle 200, the first rotor plate 510 is rotated together with the first rotating cylinder 520, and the second rotor plate 610 is rotated together with the second rotating cylinder 620. The

The rotational phases of the first rotor plate 510 and the second rotor plate 610 are detected based on the overlapping pattern of the stator electrode portions 410 and 440 and the coupling electrode portions 511 and 611, and the rotational phase of the first rotor plate 510 is The rotational phase of the second rotor plate 610 is detected as a phase signal.
Based on the rotational phase of the first rotor plate 510 and the rotational phase of the second rotor plate 610, the rotational speed and rotational angle of the spindle 200 are obtained by the arithmetic processing means 700, and the rotational speed of the spindle 200 per rotation of the spindle is calculated. The absolute position of the spindle 200 is calculated by multiplying the advance / retreat pitch. The absolute position of the spindle 200 is displayed on the display means 800.

According to 1st Embodiment provided with such a structure, there can exist the following effects.
(1) Since the first rotor 500 and the second rotor 600 are stacked in a direction perpendicular to the axis of the spindle 200 with the spindle 200 as the center, the rotor (500, 600) is disposed in the axial direction of the spindle 200. Range can be matched. By providing the first rotor 500 and the second rotor 600 in a range that matches in the spindle axis direction, the positions of the keys (530, 630) provided in the respective rotors (500, 600) are matched in the spindle axis direction. Can do. Then, the start point and the end point of the first key groove 230 and the second key groove 240 provided on the spindle 200 are made to coincide with each other, and as a result, the range in which the key groove (230, 240) is cut into the spindle 200 can be narrowed. .

(2) Since the range in which the key groove (the first key groove 230 and the second key groove 240) is cut in the spindle 200 can be narrowed, the outer frame 130 that covers the outside is made small so that the key grooves 230 and 240 are not exposed to the outside. As a result, the micrometer head 100 can be reduced in size. Further, since the length of the spindle 200 that can be used as a length measurement range can be increased except for the portion where the key grooves 230 and 240 are formed, the length measurement range can be widened.

(3) Since the number of stators 400 may be one when obtaining two different phase signals, the number of parts is larger than when a pair of stators 400 is provided for each of the first rotor 500 and the second rotor 600. Can be reduced. Further, since the first rotor 500 and the second rotor 600 are arranged on one side of the single stator 400, the assembling work becomes simpler than when the two rotors are energized from both sides of the stator 400, respectively. . As a result, component costs and assembly costs can be reduced, and manufacturing costs can be reduced.

(4) Since the bearing portion 622 is provided in the second rotating cylinder 620 and not only the first rotating cylinder 520 but also the second rotating cylinder 620 rotates on the basis of the spindle 200, the first rotating cylinder 520 is also the second rotating cylinder. The rotation of 620 is also stable. That is, since the spindle 200 is formed straight and the outer peripheral surface thereof is finished in a perfect circle, each rotating cylinder (520, 620) rotates with respect to the outer peripheral surface of the spindle 200, whereby each rotating cylinder (520, 520, 620) is rotated. 620) is prevented, and each rotating cylinder (520, 620) rotates stably. Then, the rotation of the rotor plates 510 and 610 supported by the rotating cylinders 520 and 620 is also stabilized, so that the rotation amount of the spindle 200 is accurately transmitted to the rotor plates 510 and 610. Then, the absolute position of the spindle 200 is accurately detected by detecting the rotational phase of the rotor plates 510 and 610 by the stator 400.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG.
The basic configuration of the second embodiment is the same as that of the first embodiment, but the position where the second key 630 is provided in the second rotating cylinder 620 is different.

That is, in FIG. 4, the second rotating cylinder 620 has a bearing portion 622 on the opposite side of the stator 400 across the first rotating cylinder 520 loosely fitted inside, and this bearing portion 622 has a second key. 630 is screwed together.
According to this configuration, the same effects as those of the first embodiment can be obtained. Further, since the second key 630 does not pass through the first rotating cylinder 520, it is not necessary to form a long hole (second hole 522) through which the second key 630 is inserted into the first rotating cylinder 520. Manufacturing cost can be reduced.

  In the second embodiment, the position where the second key 630 is provided must be different from the position of the first key 530 of the first rotating cylinder 520. Therefore, the position where the first key 530 is provided and the second key Although the position where the 630 is provided is slightly shifted in the spindle axis direction, the positions of the two keys 530 and 630 are made closer to each other as compared with the case where two rotors are arranged side by side as shown in FIG. 6 (prior art). In addition, the number of parts can be reduced as compared with the case where two stators are used as shown in FIG. 8 (prior art).

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG.
The basic configuration of the third embodiment is the same as that of the first embodiment, except that the second rotating cylinder 620 rotates with reference to the outer periphery of the first rotating cylinder 520 instead of the spindle 200.

  In this configuration, since it is not necessary to provide the bearing portion (622) on the second rotating cylinder 620, it is possible to reduce the processing cost and to the extent that the bearing portion (622) is not provided on the second rotating cylinder 620. The micrometer head can be reduced in size.

In addition, since the 2nd rotation cylinder 620 rotates on the basis of the outer periphery of the 1st rotation cylinder 520 instead of the spindle 200, the rotation precision of the 2nd rotation cylinder 620 may become a little worse.
However, of the two phase signals output from the phase signal transmission means 300 based on the respective rotation amounts of the first rotor 500 and the second rotor 600, whichever phase signal is reflected in the absolute position of the spindle 200. On the other hand, both signals do not necessarily have to be highly accurate.

For example, after calculating the rotation period of the spindle 200 from the difference between the phase of the first rotor 500 and the phase of the second rotor 600 to obtain the rough position of the spindle 200, the spindle is determined based on the phase of the first rotor 500. When calculating 200 fine positions, a slight error is not a problem as long as the rotational phase of the second rotor 600 has an accuracy that can limit the rough rotation period of the spindle 200.
Therefore, when it is not necessary to maintain the rotational accuracy of the second rotating cylinder 620 so high, the second rotating cylinder 620 may be rotated with reference to the first rotating cylinder 520, and the configuration of the third embodiment is used. According to this, the processing cost can be reduced and the micrometer head can be reduced in size.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above-described embodiment, the case where the magnetic rotary encoder is used as the configuration for detecting the rotational phase of the rotor by the stator in the phase signal transmission unit has been described as an example. However, the configuration for detecting the rotational phase of the rotor by the stator is described. The capacitance encoder or the optical encoder may be used, and the configuration is not particularly limited.

  The absolute position measuring device of the present invention is not limited to a micrometer head, and may be an inner measuring or outer measuring micrometer, and may be a measuring device that detects the absolute position of a spindle that moves forward and backward by rotation. That's fine.

In the above embodiment, the case where there are two rotors has been described as an example. However, the number of rotors may be three, four, or more.
In particular, when there are three or more rotors, if a plurality of rotors are arranged in parallel along the spindle axis as in the prior art, the key position must be separated in the spindle axis direction, so that it is engraved on the spindle. The key groove range is widened, but by stacking multiple rotors in a direction perpendicular to the axial direction of the spindle as in the present invention, the key groove is engraved on the spindle by making all the key positions close to each other. can do.

  The present invention can be used for small measuring instruments such as a micrometer head and a micrometer.

The figure which shows 1st Embodiment which concerns on the micrometer head as an absolute position measuring apparatus of this invention. The disassembled perspective view of a phase signal transmission means in the said 1st Embodiment. The figure which shows the opposing surface of the stator and rotor of a phase signal transmission means in the said 1st Embodiment. (A) is a figure which shows one surface of a stator, (B) is a figure which shows one surface of a 1st rotor and a 2nd rotor. The figure which shows 2nd Embodiment which concerns on the micrometer head as an absolute position measuring apparatus of this invention. The figure which shows 3rd Embodiment which concerns on the micrometer head as an absolute position measuring apparatus of this invention. The figure which shows the structure of the conventional absolute position measuring apparatus. The figure which shows the relationship between two phase signals and the position of a spindle in the conventional absolute position measuring apparatus. The figure which shows the other Example of the conventional absolute position measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Micrometer head, 2 ... Main body, 3 ... Spindle, 4 ... Phase signal transmission means, 5 ... Arithmetic processing means, 6 ... Display means, 21 ... Through-hole, 24 ... Frame, 31 ... Feed screw, 32 ... Knob part 33 ... first keyway, 34 ... second keyway, 41 ... stator, 41A ... stator, 41B ... stator, 42 ... first rotor, 43 ... first rotating cylinder, 44 ... key, 45 ... second rotor, 46 ... second rotating cylinder, 47 ... key, 100 ... micrometer head, 110 ... main body, 120 ... through hole, 122 ... partition plate, 123 ... storage space, 130 ... outer frame, 140 ... front end side inner wall, 200 ... Spindle, 210 ... feed screw, 220 ... knob portion, 230 ... first key groove, 240 ... second key groove, 300 ... phase signal transmitting means, 400 ... stator, 410 ... first stator electrode portion, 4 DESCRIPTION OF SYMBOLS 0 ... 1st transmission electrode part, 430 ... 1st reception electrode part, 440 ... 2nd stator electrode part, 450 ... 2nd transmission electrode part, 460 ... 2nd reception electrode part, 500 ... 1st rotor, 510 ... 1st Rotor plate, 511... First coupling electrode portion, 520... First rotating cylinder, 521... First hole, 522 .. second hole, 530... First key, 600. ... second coupling electrode part, 620 ... second rotating cylinder, 622 ... bearing part, 630 ... second key, 700 ... calculation processing means, 800 ... display means.

Claims (3)

A main body, a spindle that is screwed to the main body and is axially movable back and forth by rotation and has a plurality of key grooves with different lead angles on the outer periphery, and a plurality of cycles having different periods according to the amount of movement of the spindle Phase signal transmitting means for transmitting the phase signal, arithmetic processing means for calculating the phase signal and calculating the absolute position of the spindle, and display means for displaying the absolute position,
The phase signal transmitting means is
A stator fixed to the main body in a state where the spindle is inserted;
A plurality of rotors that have a key that engages with the keyway and that can rotate around the spindle and are arranged to face the stator;
All of the plurality of rotors are disposed on one side of the stator, and the plurality of rotors are stacked in a direction perpendicular to the spindle axis with the spindle as the center,
The absolute position measuring device, wherein the plurality of key grooves are formed in substantially the same region in the axial direction of the spindle. The absolute position measuring device according to claim 1,
Each of the plurality of rotors includes a rotor plate that is paired with the stator and rotated in a state of facing the stator, and a rotating cylinder that supports rotation of the rotor plate around the spindle,
All the rotating cylinders rotate with the outer peripheral surface of the spindle as a reference plane. The absolute position measuring device according to claim 2,
As the plurality of rotors, a first rotor having a first rotor plate and a first rotating cylinder, and a second rotor having a second rotor plate and a second rotating cylinder and rotatably provided outside the first rotor. And an absolute position measuring device.

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