JP4866653B2 - Absolute position measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absolute position measurement apparatus which is small and easy to manufacture. <P>SOLUTION: The absolute position measurement apparatus comprises a spindle 300 which is screwed into a body 200 and can advance and retract in the axial direction through rotation, and a phase signal transmitting means 400 for transmitting two phase signals having different periods in accordance with the rotation of the spindle 300. Along with the axis, a key groove 330 is provided in the spindle 300. The phase signal transmitting means 400 comprises a first rotary encoder 500 comprising a first rotor plate 520 which integrally rotates with a spindle 300, a first rotation cylinder 530 which integrally rotates with the spindle 300 and has a screw 531 on the outside surface, a gear 611 having gear teeth which engage with the screw 531 of the first rotation cylinder 530, and a second rotary encoder 600 having a second rotor plate 612 which integrally rotates with the gear 611. The rotation period of the first rotor plate 520 and the rotation period of the second rotor plate 612 are different for the rotation of the spindle 300. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

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. 5 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, 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 urged 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. 6 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 of 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 generated by one rotation of the spindle 3, and the spindle calculated as the pitch per rotation of the spindle 3. The spindle absolute position may be calculated by multiplying the number of rotations.

Japanese Patent Laying-Open No. 2003-207307 (FIG. 1, paragraphs (0038) to (0045))

However, in the configuration disclosed in FIG. 5, 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 respectively provided are separated in the axial direction of the spindle 3 (L _{1 in} FIG. 5).

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 the 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 moves forward and backward. 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. Therefore, a gap between the stator 41 and the stator 41 is maintained from both sides. 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.

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

  The absolute position measuring apparatus of the present invention includes a main body, a spindle screwed into the main body and provided so as to be capable of moving forward and backward in the axial direction by rotation, and two phase signals having different periods according to the rotation of the spindle. Phase signal transmitting means for transmitting, and arithmetic processing means for calculating the phase signal and calculating the absolute position of the spindle, wherein the spindle is provided with a keyway along an axis, and the phase signal transmitting means Has a key that engages with the key groove, a first rotary encoder that includes a first rotor plate that rotates integrally with the spindle in a state of being fitted on the spindle, and a key that engages with the key groove. A rotating cylinder that rotates integrally with the spindle while being externally fitted to the spindle and has a screw on the outer surface, and teeth that mesh with the screw of the rotating cylinder And a second rotary encoder having a second rotor plate that rotates integrally with the gear, and the rotation cycle of the first rotor plate and the rotation cycle of the second rotor plate are different with respect to the rotation of the spindle. It is characterized by being.

  In such a configuration, when the spindle is rotated, the spindle advances and retreats with respect to the main body by screwing of the spindle and the main body. A phase signal corresponding to the rotation of the spindle is transmitted from the phase signal transmitting means according to the rotation of the spindle. When the spindle rotates, since the key of the first rotor plate is engaged with the key groove of the spindle, the first rotor plate is rotated integrally with the spindle. The rotation of the first rotor plate is detected and a phase signal is output from the first rotary encoder. Further, when the spindle rotates, since the key of the rotating cylinder is engaged with the key groove of the spindle, the rotating cylinder is rotated integrally with the spindle. Then, the gear teeth meshed with the screw of the rotating cylinder are sent to rotate the gear, and the second rotor plate is rotated integrally with the gear. The rotation of the second rotor plate is detected and a phase signal is output from the second rotary encoder.

  Here, the first rotor plate and the second rotor plate rotate at different rotation periods with respect to the rotation of the spindle, and signals having different phases are output from the first rotary encoder and the second rotary encoder. The rotation phase of the spindle is obtained by the arithmetic processing means based on signals having two different phases, and further, the amount of movement of the spindle, that is, the absolute position of the spindle is calculated based on the relationship between the rotation phase of the spindle and the advance / retreat pitch. The

According to such a configuration, two phase signals can be obtained by the rotation of the first rotor plate and the second rotor plate according to the rotation of the spindle, and the absolute position of the spindle can be obtained from the two phase signals. Can do.
Here, in order to obtain two phase signals having different periods according to the rotation of the spindle, the first rotor plate and the second rotor plate are rotated. The spindle is provided with one key groove, Thus, the first rotor plate and the rotating cylinder are rotated together with the spindle. Then, the second rotor plate is rotated by rotating the gear meshed with the screw of the rotating cylinder. At this time, the rotation angle of the gear with respect to one rotation of the rotating cylinder can be arbitrarily set by adjusting the screw pitch of the rotating cylinder and the number of teeth of the gear. Therefore, the rotation period of the second rotor plate is different from that of the first rotor plate, and phase signals having different periods can be obtained from the first rotor plate and the second rotor plate. As described above, when the two rotor plates are rotated at different rotation cycles, the number of key grooves cut on the spindle is one, so that the processing is simple.

Conventionally, when two rotor plates are rotated at different periods as the spindle rotates, two key grooves having different pitches are machined on the spindle. However, it is difficult to process two grooves with different pitches on the spindle, and the cost is high.
In this respect, in the present invention, since only one groove is required for the spindle, processing is simple.

Moreover, in order to make the rotation of the second rotor plate different from the rotation cycle of the first rotor plate, the screw pitch of the rotating cylinder and the number of gear teeth can be adjusted, so that the setting of the rotation cycle is simple. Since the screw pitch of the rotating cylinder and the gear teeth can be processed with high accuracy, the rotational accuracy of the second rotor plate can be increased and the detection accuracy of the spindle position can be improved.
Conventionally, since a spiral keyway is engraved on the spindle, it is difficult to process and it is difficult to make the pitch of the spiral highly accurate.
In this regard, in the present invention, the accuracy of detecting the spindle position can be easily improved by processing the screw of the rotating cylinder and the gear teeth with high accuracy.

Further, conventionally, since two key grooves are engraved on the spindle, the area for engraving the key groove on the spindle becomes long, and there is a problem that the measuring apparatus as a whole becomes large.
In this regard, in the present invention, only one key groove on the spindle is required, so that the area for engraving the key groove can be shortened to reduce the size of the measuring apparatus as a whole.
And the measuring apparatus of this invention can be reduced in size by making the pitch of the screw | thread of a rotating cylinder and the tooth | gear of a gearwheel fine.

  In the present invention, the first rotary encoder outputs phase signals having different values for different rotation angles within one rotation of the first rotor plate, and the second rotary encoder outputs the second rotor plate. It is preferable that phase signals having different values are output for different rotation angles within one rotation, and the rotation speed of the second rotor plate is within one rotation with respect to the maximum rotation speed of the spindle within the movable range of the spindle. .

  In such a configuration, the first rotor plate and the second rotor plate rotate at different periods as the spindle rotates. At this time, the first rotor plate rotates integrally with the spindle, and the second rotor plate rotates within one rotation while the spindle moves within the movable range. Then, phase signals having different values are output from the first rotary encoder for different rotation angles within one rotation of the first rotor plate. Therefore, the rotation angle within one rotation of the first rotor plate is uniquely determined by the arithmetic processing means based on this phase signal. Since the first rotor plate rotates integrally with the spindle, the rotation angle of the first rotor plate is the rotation angle of the spindle. Further, different phase signals are output from the second rotary encoder for different rotation angles within one rotation of the second rotor plate. Therefore, the rotation angle within one rotation of the second rotor plate is uniquely determined by the arithmetic processing unit based on this phase signal. Further, since the second rotor plate is within one rotation in the movable range of the spindle, the relation between the rotation angle of the second rotor plate and the spindle rotation speed is set in advance, so that the second rotor plate is calculated in the arithmetic processing means. The rotation speed of the spindle can be uniquely determined from the rotation angle of. Then, the total rotation phase of the spindle is calculated from the spindle rotation speed based on the rotation angle within one rotation of the first rotor plate and the rotation angle of the second rotor plate. Based on the total rotation phase of the spindle and the feed pitch of the spindle, the total movement amount of the spindle, that is, the absolute position of the spindle is calculated.

According to such a configuration, rough information such as the spindle rotation speed is acquired based on the rotation angle of the second rotor plate, and a highly accurate rotation phase within one rotation is obtained based on the rotation angle of the first rotor plate. Can be acquired.
Therefore, the absolute spindle position can be obtained with high accuracy.

Here, in principle, it is possible to uniquely determine the absolute position of the spindle only with the second rotor plate that rotates once in the movable range of the spindle.
However, for example, in the second rotor plate having only one rotation per 50 rotations of the spindle, the change in the angle with respect to the movement amount of the spindle is extremely small. Therefore, if the rotation angle cannot be detected with very high resolution, the accurate position of the spindle must be detected. I can't.
And it is very difficult and impractical to make the second rotary encoder high resolution to such an extent that the absolute position of the spindle can be detected only by the second rotor plate.

  In this regard, in the present invention, since the rotation phase within one rotation of the spindle is detected by the first rotor plate, the second rotor plate only needs to have a resolution that can identify the rotation speed of the spindle. Therefore, since a rotary encoder with high resolution is not required, the manufacturing cost can be reduced.

Further, since the rotation of the spindle is transmitted from the rotating cylinder to the second rotor plate via the gear, the rotation accuracy of the second rotor plate depends on the processing accuracy of the screw of the rotating cylinder and the teeth of the gear and the engagement between the screw and the teeth. May be slightly lower.
Even in such a case, the spindle position can be detected with high accuracy by detecting the rotation of the first rotor plate as long as the second rotor plate has a resolution and accuracy sufficient to specify the spindle rotation speed.

  In the present invention, the first rotor plate is preferably supported by the rotating cylinder.

  According to such a configuration, it is possible to reduce the number of parts and reduce the size of the apparatus by using the cylinder that rotatably supports the first rotor plate and the rotating cylinder that transmits the rotation to the second rotor plate in common.

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 includes a main body 200, a spindle 300 that is screwed to the main body 200 and is provided so as to be able to advance and retreat in the axial direction by rotation, and a phase signal transmission means 400 that transmits a phase signal according to the amount of movement of the spindle 300. A transmission / reception control unit 710 that controls transmission / reception of signals to / from the phase signal transmission unit 400, an arithmetic processing unit 720 that performs arithmetic processing on the phase signal to obtain an absolute position of the spindle 300, and displays the calculated absolute position of the spindle 300. Display means 730.

  The main body 200 has a cylindrical shape having a through hole 210, and a female screw 211 is provided on the inner periphery of the through hole 210. In the through hole 210, an intermediate partition plate 213 that partitions the storage space 212 is provided. Further, the outer periphery on the front end side of the main body 200 is covered with an outer frame 220.

The spindle 300 is disposed in a state where both ends protrude from the main body 200 through the through hole 210 of the main body 200. A feed screw 310 that is screwed into the female screw 121 of the main body 200 is provided on the outer periphery of the rear end side of the spindle 300, and can be moved forward and backward in the axial direction by a rotating operation. A knob portion 320 that rotates the spindle 300 from the outside of the main body 200 is provided at the rear end of the spindle 300. A key groove 330 is linearly provided along the axial direction at the center of the spindle 300.
Here, the feed screw 310 of the spindle 300 is engraved with 50 rotations at a feed of 0.5 mm. That is, the movable distance of the spindle 300 is 25 mm.

The phase signal transmission unit 400 will be described.
The phase signal transmission unit 400 is disposed in a state of being fitted on the spindle 300 and has a first rotary encoder 500 having a first rotor 510 that rotates integrally with the spindle 300, and a first rotary encoder 500 that rotates as the first rotor 510 rotates. A second rotary encoder 600 having two rotors 610. Both the first rotary encoder 500 and the second rotary encoder 600 can detect an absolute angle within one rotation of the rotors 510 and 610.

  The first rotary encoder 500 includes a first rotor 510 that rotates integrally with the spindle 300, and a first stator 550 that detects the rotation of the first rotor 510.

  The first rotor 510 supports the rotation of the first rotor plate 520 centered on the spindle 300 and the first rotor plate 520 rotated in a state of being opposed to the first stator 550 in a pair with the first stator 550. A first rotating cylinder 530 and a key 540 that engages with the key groove 330 of the spindle 300 are provided.

  The first rotor plate 520 is a small disk having an insertion hole 521 through which the spindle 300 is inserted. The first rotating cylinder 530 has a cylindrical shape that is fitted on the spindle 300 and is connected to the back surface of the first rotor plate 520 to support the rotation of the first rotor plate 520. A key 540 is screwed into the first rotating cylinder 530, and the tip of the key 540 is engaged with the key groove 330 of the spindle 300. A screw 531 is provided on the outer periphery of the first rotating cylinder 530. Here, when the spindle 300 rotates, since the key 540 is engaged with the key groove 330 of the spindle 300, the first rotating cylinder 530 rotates integrally with the spindle 300. Further, as the first rotating cylinder 530 rotates, the second rotor 610 meshed with the screw 531 of the first rotating cylinder 530 is rotated.

  The first stator 550 has an insertion hole 551 through which the spindle 300 is inserted in the center of the disk, and is fixed to the partition plate 213. The first stator 550 is disposed to face the first rotor 510 and detects an absolute angle within one rotation of the first rotor 510. That is, the first stator 550 outputs a phase signal indicating a change in one cycle per rotation of the first rotor 510. Since the first rotor 510 rotates together with the spindle 300, the phase signal output from the first stator 550 shows a change in one cycle by one rotation of the spindle 300, as shown in FIG. A change of 50 periods is shown while the spindle 300 rotates 50 times.

  The second rotary encoder 600 includes a second rotor 610 that meshes with the screw 531 of the first rotating cylinder 530 and rotates as the first rotating cylinder 530 rotates, and a second stator that detects the rotation phase of the second rotor 610 ( (Not shown).

  The second rotor 610 includes a gear 611 having teeth engaged with the screw 531 of the first rotating cylinder 530 on the outer periphery, and a second rotor plate 612 attached to the gear 611.

The number of teeth provided on the gear 611 is 50, and the teeth of the gear 611 are engaged with the screw 531 of the first rotating cylinder 530. Then, one tooth of the gear 611 is fed when the first rotating cylinder 530 makes one rotation. That is, the gear 611 rotates once while the spindle 300 rotates 50 times.
Note that the rotation axis direction of the gear 611 is three-dimensionally orthogonal to the rotation axis directions of the spindle 300 and the first rotor 510, that is, the rotation axis direction of the spindle 300 is the left-right direction in FIG. The rotation axis direction of the gear 611 is a direction orthogonal to the paper surface of FIG.

  The second rotor plate 612 is attached to the gear 611 and rotates integrally with the gear 611. That is, the second rotor plate 612 rotates once while the spindle 300 rotates 50 times.

  In addition, although illustration is abbreviate | omitted about the 2nd stator, it arrange | positions facing the 2nd rotor board 612. FIG. The second stator detects an absolute rotation angle within one rotation of the second rotor 610. That is, the second stator outputs a phase signal indicating a change in one cycle per rotation of the second rotor 610. Since the second rotor 610 rotates once while the spindle 300 rotates 50 times, the phase signal output from the second stator is increased by 50 rotations of the spindle 300 as shown in FIG. Indicates the change in period.

FIG. 3 is a diagram illustrating configurations of the transmission / reception control unit 710 and the arithmetic processing unit 720.
The transmission / reception control unit 710 includes a first transmission / reception control unit 711 that controls transmission / reception of signals to / from the first stator 550 and a second transmission / reception control unit 714 that controls transmission / reception of signals to / from the second stator.

The first transmission / reception control unit 711 includes a first transmission control unit 712 and a first reception control unit 713. The first transmission control unit 712 transmits a predetermined AC signal to the first stator 550, and the first reception control unit. 713 receives a signal from the first stator 550.
Similarly, the second transmission / reception control unit 714 includes a second transmission control unit 715 and a second reception control unit 716, and the second transmission control unit 715 transmits a predetermined AC signal to the second stator, and receives the second reception. The control unit 716 receives a signal from the second stator.
The first reception control unit 713 and the second reception control unit 716 output the phase signal received from each stator to the arithmetic processing unit 720.
Here, the first reception control unit 713 outputs the phase signal from the first stator 550, and the phase signal from the first reception control unit 713 is one cycle per one rotation of the spindle 300 as shown in FIG. The second reception control unit 716 outputs a phase signal from the second stator, and the phase signal from the second reception control unit 716 is 1 per 50 revolutions of the spindle 300 as shown in FIG. Indicates the change in period.

The arithmetic processing unit 720 will be described.
The arithmetic processing unit 720 calculates the rotation angle θ of the first rotor 510 and the second rotor 610, and the rotation of the first rotor 510 and the second rotor 610 calculated by the rotation angle calculation unit 721. A rotation phase calculation unit 724 that calculates the rotation phase of the spindle 300 based on the angle, and a spindle position calculation unit 727 that calculates the absolute position of the spindle 300 based on the rotation phase of the spindle 300 calculated by the rotation phase calculation unit 724. And comprising.

  The rotation angle calculation unit 721 is based on the first rotation angle calculation unit 722 that calculates the rotation angle of the first rotor 510 based on the signal from the first reception control unit 713 and the signal from the second reception control unit 716. A second rotation angle calculation unit 723 that calculates the rotation angle of the second rotor 610.

  The first rotation angle calculation unit 722 is based on the output signal from the first reception control unit 713 (see FIG. 2A), and the absolute angle within one rotation of the first rotor 510 (0 ° <θ <360 °). Is calculated. In the first rotation angle calculation unit 722, the relationship between the rotation angle of the first rotor 510 and the phase signal is set and stored. As shown in FIG. 2A, the phase signal output from the first reception control unit 713 has a different phase within one rotation of the first rotor 510. Therefore, the first rotor is based on this phase signal. An absolute angle within one revolution of 510 is calculated.

  Also, the second rotation angle calculation unit 723 calculates the rotation angle of the second rotor 610 based on the output signal from the second reception control unit 716 (see FIG. 2B). In the second rotation angle calculation unit 723, the relationship between the rotation angle of the second rotor 610 and the phase signal is set and stored. As shown in FIG. 2B, since the phase signal output from the second reception control unit 716 has a different phase in one rotation of the second rotor 610, the rotation of the second rotor 610 is based on this phase signal. A corner is calculated.

  The rotation phase calculation unit 724 includes a spindle rotation number calculation unit 725 that calculates the rotation number of the spindle 300 based on the rotation angle of the second rotor 610, and the spindle 300 based on the spindle rotation number and the rotation angle of the first rotor 510. A total rotation phase calculation unit 726 that calculates a total rotation phase.

In the spindle rotation speed calculation unit 725, the relationship between the rotation angle of the second rotor 610 and the spindle rotation speed is set. Since the second rotor 610 has a different rotation angle within one rotation while the spindle 300 rotates 50 times, the spindle rotation speed N is uniquely calculated based on the rotation angle of the second rotor 610. In calculating the total rotation phase of the spindle 300, the total rotation phase calculation unit 726 first calculates a phase θ ₂ = 360 ° × N based on the spindle rotation speed based on the spindle rotation speed N. Subsequently, the rotation angle θ ₁ of the first rotor 510 calculated by the first rotation angle calculation unit 722 is added to the phase θ ₂ based on the previously calculated spindle rotation speed. Then, the total rotational phase θ _T (= θ ₁ + θ ₂ ) of the spindle 300 is calculated.

In the spindle position calculation unit 727, a movement pitch (0.5 mm) per rotation of the spindle 300 is set in advance. At spindle position calculator 727, by moving pitch (0.5 mm) and the total rotation phase theta _T is multiplied, the total movement of the spindle 300, i.e., the absolute position of the spindle 300 is calculated.

  The display unit 730 displays the absolute position of the spindle 300 by digital display, for example.

Here, the principle of detecting the rotation angle within one rotation of the rotor by the stator in the phase signal transmission means 400 will be briefly described.
Since the first rotary encoder 500 and the second rotary encoder 600 have the same configuration, the first rotary encoder 500 will be described as an example here.
This phase signal transmitting means 400 is a so-called single-rotation ABS (absolute detection) rotary encoder. FIG. 4 is a diagram illustrating the opposing surfaces of the first stator 550 and the first rotor 510. FIG. 4A is a diagram illustrating one surface of the first stator 550, and FIG. 4B is a diagram illustrating one surface of the first rotor 510.

In the first stator 550, a surface facing the first rotor 510 is provided with an electrode portion that is doubly arranged inside and outside, that is, an inner stator electrode portion 560 is provided on the inner side, and an inner stator electrode portion is provided. An outer stator electrode portion 570 is provided outside 560 (see FIG. 4A).
Stator electrode portions 560 and 570 are connected to first transmission / reception control portion 711.
In the first rotor 510, a surface facing the first stator 550 is provided with an electrode portion that is doubly arranged on the inner side and the outer side, that is, on the inner side, an inner coupling electrode that electromagnetically couples with the inner stator electrode portion 560. A portion 511 is provided, and an outer coupling electrode portion 512 that electromagnetically couples with the outer stator electrode portion 570 is provided on the outer side (see FIG. 4B).

First, the inner stator electrode portion 560 and the outer stator electrode portion 570 will be described with reference to FIG.
The inner stator electrode portion 560 includes an inner transmission electrode portion 561 composed of one electrode wire arranged in a ring shape, and three electrodes that respectively form a rhombus coil continuous at a predetermined pitch inside the inner transmission electrode portion 561. An inner receiving electrode portion 562 that is configured by lines 562A to 562C and arranged in a ring shape as a whole.
Similarly, the outer stator electrode part 570 forms an outer transmission electrode part 571 composed of one electrode wire arranged in a ring shape and a rhombus coil continuous at a predetermined pitch inside the outer transmission electrode part 571 3. An outer receiving electrode portion 572 that is configured by the electrode wires 572A to 572C and arranged in a ring shape as a whole.

Each of the electrode wires (562A to C) constituting the inner receiving electrode portion 562 has nine (9 cycles) rhombuses, and each of the electrode wires (572A to C) constituting the outer receiving electrode portion 572 is 10 in number. Each of the receiving electrode portions 562 and 572 is arranged so that the three electrode lines 562A to 562C and 572A to 572C are shifted in phase and overlap each other.
In FIG. 4A, the portions where the wirings appear to cross each other are separated in a direction perpendicular to the paper surface, and insulation is ensured.

  The inner receiving electrode portion 562 and the outer receiving electrode portion 572 are essentially equivalent to a configuration in which each ring coil is independently connected by one electrode wire, that is, each rhombus coil is one Works the same as a coil.

Here, each electrode line of the transmission electrode units 561 and 571 is connected to the first transmission control unit 712, and a predetermined AC signal is applied to each electrode line from the first transmission control unit 712.
The electrode lines 562A-B and 572A-C of the reception electrode units 562 and 572 are connected to the first reception control unit 713, and the first reception control unit 713 samples the signals of the reception electrode units 562 and 572 at a predetermined sampling period. Is done.

Next, the inner coupling electrode portion 511 and the outer coupling electrode portion 512 will be described with reference to FIG.
The inner coupling electrode portion 511 is configured by electrode wires arranged in a ring shape as a whole while drawing a rectangular wave.
Similarly, the outer coupling electrode portion 512 is configured by an electrode line that is drawn in a rectangular shape and draws a rectangular wave as a whole.
The inner coupling electrode portion 511 is a nine-cycle rectangular wave, and the outer coupling electrode portion 512 is a ten-cycle rectangular wave.
The rectangular waves of the inner coupling electrode portion 511 and the outer coupling electrode portion 512 are originally equivalent to a configuration in which ring coils that are independent of each other are connected by a single electrode wire, that is, each rectangular wave A wave works equally in one coil.

In this configuration, when current (alternating current) (i ₁ ) is supplied from the first transmission control unit 712 to the inner transmission electrode unit 561 and the outer transmission electrode unit 571, the electrode lines of the transmission electrode units 561 and 571 are changed. An induced magnetic field (B ₁ ) is generated around. Since the inner stator electrode portion 560 and the inner coupling electrode portion 511 are electromagnetically coupled and the outer stator electrode portion 570 and the outer coupling electrode portion 512 are electromagnetically coupled, the inner coupling electrode portion 511 and the outer coupling electrode are coupled. An induced current (i ₂ ) is generated in the portion 512 and an induced magnetic field (B ₂ , B ₃ ) is generated by the induced current (i ₂ ).

Further, the inner coupling electrode portion 511 and the inner receiving electrode portion 562 are electromagnetically coupled, and the outer coupling electrode portion 512 and the outer receiving electrode portion 572 are electromagnetically coupled. An induced current (i ₃ ) is generated in the electrode lines 562A-C and 572A-C of the inner receiving electrode portion 562 and the outer receiving electrode portion 572 according to the magnetic field pattern of the coupling electrode portion 512.

Here, the inner coupling electrode portion 511 and the inner receiving electrode portion 562 have nine cycles, whereas the outer coupling electrode portion 512 and the outer receiving electrode portion 572 have ten cycles. On the other hand, the first detection phase by the inner reception electrode unit 562 shows a change of 10 cycles, and the second detection phase by the outer reception electrode unit 572 shows a change of 9 cycles.
Therefore, with respect to the rotation angle θ (0 ° ≦ θ <360 °) of the first rotor 510, the first phase signal φ1 by the inner receiving electrode portion 562 and the second phase signal φ2 by the outer receiving electrode portion 572 are: Unlike each other, while the first rotor 510 makes one rotation, the phase difference Δφ between the first phase signal φ1 and the second phase signal φ2 is different with respect to the rotation angle θ of the different rotor 510.
Therefore, conversely, the rotational phase θ within one rotation of the first rotor 510 is uniquely determined from the phase difference Δφ between the first phase signal φ1 and the second phase signal φ2.

The operation of the first embodiment having such a configuration will be described.
When the spindle 300 is rotated by the knob portion 320, the spindle 300 is advanced and retracted in the axial direction by screwing between the female screw 211 of the main body 200 and the feed screw 310 of the spindle 300. When the spindle 300 rotates, the first rotating cylinder 530 rotates with the spindle 300 by the key 540 engaged with the key groove 330 of the spindle 300.

When the first rotating cylinder 530 rotates, the first rotor plate 520 rotates together with the first rotating cylinder 530. The rotation of the first rotor plate 520 is detected by the first stator 550 and sent to the first reception control unit 713. Subsequently, the first rotation angle calculation unit 722 calculates a rotation angle within one rotation of the first rotor plate 520.
Here, since the first rotor plate 520 rotates integrally with the spindle 300, the rotation angle within one rotation of the first rotor plate 520 is the rotation angle within one rotation of the spindle 300.

When the first rotating cylinder 530 rotates, the gear 611 engaged with the screw 531 of the first rotating cylinder 530 rotates. Then, the second rotor plate 612 rotates with the gear 611. At this time, the tooth of the gear 611 is sent by one rotation of the first rotating cylinder 530, and the second rotor plate 612 rotates once for 50 rotations of the spindle 300.
A phase signal within one rotation of the second rotor plate 612 is detected by the second stator and sent to the second reception control unit 716. Subsequently, the second rotation angle calculation unit 723 calculates a rotation angle within one rotation of the second rotor plate 612. Then, the rotation speed of the spindle 300 is calculated by the spindle rotation speed calculation unit 725 based on the rotation angle of the second rotor plate 612.

  Based on the rotation angle of the first rotor plate 520 calculated by the first rotation angle calculation unit 722 (= the rotation angle within one rotation of the spindle) and the spindle rotation number calculated by the spindle rotation number calculation unit 725. The total rotation phase of the spindle 300 is calculated by the total rotation phase calculation unit 726. Based on the calculated total rotational phase and the feed pitch (0.5 mm) of the spindle 300, the absolute position of the spindle 300 is calculated by the spindle position calculation unit 727. The calculated spindle absolute position is displayed on the display means 730.

According to 1st Embodiment provided with such a structure, there can exist the following effects.
(1) Since two phase signals can be obtained by the rotation of the first rotor plate 520 and the second rotor plate 612 rotating at different periods according to the rotation of the spindle 300, the two phase signals can be used to The absolute position can be determined.

(2) When the first rotor plate 520 and the second rotor plate 612 are rotated to obtain two phase signals having different periods as the spindle 300 rotates, the spindle 300 is provided with a single key groove 330. By engaging with the key groove 330, the first rotor plate 520 and the first rotating cylinder 530 are rotated together with the spindle 300, and the gear 611 engaged with the screw 531 of the first rotating cylinder 530 is rotated. The second rotor plate 612 is rotated. As described above, in the present embodiment, only one groove is required for the spindle 300, so that the processing is simple.

(3) When the rotation of the spindle 300 is transmitted to the second rotor plate 612 via the first rotating cylinder 530 and the gear 611, the screw pitch of the first rotating cylinder 530 and the number of teeth of the gear 611 are adjusted. The rotation angle of the second rotor plate 612 with respect to one rotation of the spindle 300 can be easily set. Therefore, the processing cost can be reduced.

(4) Since the rotation of the spindle 300 is transmitted to the second rotor plate 612 via the first rotating cylinder 530 and the gear 611, the screw pitch of the first rotating cylinder 530 and the teeth of the gear 611 can be processed with high accuracy. The rotation accuracy of the second rotor plate 612 can be increased to improve the detection accuracy of the spindle position.

(5) Since the pitch of the teeth of the screw 531 and the gear 611 of the first rotating cylinder 530 can be finely processed, the micrometer head 100 can be miniaturized.

(6) In calculating the absolute position of the spindle using the first rotary encoder 500 and the second rotary encoder 600, the rotational phase within one rotation of the spindle 300 is detected by the first rotor plate 520. The two-rotor plate 612 only needs to have a resolution that can identify the number of rotations of the spindle 300. Therefore, a rotary encoder with high resolution is not required, and the manufacturing cost can be reduced.

(7) Since the gear 611 meshes with the first rotating cylinder 530 that supports the first rotor plate 520, a cylinder that rotates and supports the first rotor plate 520 and a rotating cylinder that transmits rotation to the second rotor plate 612 are provided. In common, the number of parts can be reduced and the apparatus can be downsized.

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.
In calculating the absolute position of the spindle 300 by obtaining phase signals with different periods, the rotation of the first rotor 510 and the second rotor is performed in 50 rotations in addition to the second rotor plate 612 being within one rotation. There is no particular limitation on the method for obtaining the spindle absolute position from two phase signals having different periods, such as making the phase difference always different.
In the above embodiment, the first rotary encoder and the second rotary encoder share one rotating cylinder so that the rotating cylinder supports the first rotor plate and transmits the rotation to the second rotor plate. Of course, the rotating cylinder may be provided separately from the first rotary encoder.
The absolute position measuring device is not limited to a micrometer head as long as it has a spindle that advances and retreats by rotation.

  The present invention can be used for an absolute position measuring device, for example, a measuring device having a spindle that moves by rotation of a micrometer, a micrometer head, or the like.

Sectional drawing which shows the structure of a micrometer head in 1st Embodiment. The figure which shows the signal output from a 1st rotary encoder and a 2nd rotary encoder in 1st Embodiment. The figure which shows the structure of the transmission / reception control part and the arithmetic processing part in 1st Embodiment. The figure which shows the mutual opposing surface of a 1st stator and a 1st rotor in 1st Embodiment. The figure which shows the structure of a micrometer head in a prior art. The figure which shows the example of the relationship between the rotation speed of a spindle and the phase signal obtained from two rotors in a prior art.

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, 32 ... Knob part, 33 ... Keyway , 34 ... key groove, 41 ... stator, 42 ... first rotor, 43 ... first rotating cylinder, 44 ... key, 45 ... first rotor, 46 ... second rotating cylinder, 47 ... key, 100 ... micrometer head, DESCRIPTION OF SYMBOLS 200 ... Main body, 210 ... Through-hole, 211 ... Female screw, 212 ... Storage space, 213 ... Partition plate, 220 ... Outer frame, 300 ... Spindle, 310 ... Screw, 320 ... Knob part, 330 ... Keyway, 400 ... Phase signal transmitting means, 500 ... first rotary encoder, 510 ... first rotor, 511 ... inner coupling electrode part, 512 ... outer coupling electrode part, 520 ... first rotor plate, 521 ... insertion hole, 30 ... first rotating cylinder, 531 ... screw, 540 ... key, 550 ... first stator, 551 ... insertion hole, 560 ... inner stator electrode part, 561 ... inner transmission electrode part, 562A-C ... electrode wire, 562 ... inner Receiving electrode part, 570 ... Outer stator electrode part, 571 ... Outer transmitting electrode part, 572 ... Outer receiving electrode part, 572A-C ... Electrode wire, 600 ... Second rotary encoder, 610 ... Second rotor, 611 ... Gear, 612 ... second rotor plate, 710 ... transmission / reception controller, 711 ... first transmission / reception controller, 712 ... first transmission controller, 713 ... first reception controller, 714 ... second transmission / reception controller, 715 ... second transmission control , 720 ... second reception control unit, 720 ... calculation processing unit, 721 ... rotation angle calculation unit, 722 ... first rotation angle calculation unit, 723 ... second rotation angle calculation unit, 724 ... rotation phase calculation unit, 725 Spindle speed computing section, 726 ... total rotation phase calculating section, 727 ... spindle position calculator, 730 ... display unit.

Claims (3)

The body,
A spindle screwed into the main body and provided so as to freely advance and retract in the axial direction by rotation;
Phase signal transmitting means for transmitting two phase signals having different periods according to the rotation of the spindle;
Arithmetic processing means for calculating the phase signal and calculating the absolute position of the spindle, and
The spindle is provided with a keyway along the axis,
The phase signal transmitting means is
A first rotary encoder comprising a first rotor plate that has a key that engages with the key groove and rotates integrally with the spindle in a state of being externally fitted to the spindle;
A rotating cylinder having a key that engages with the keyway and rotating integrally with the spindle while being externally fitted to the spindle, and having a screw on the outer surface;
A gear having teeth meshing with the screw of the rotating cylinder and a second rotary encoder having a second rotor plate that rotates integrally with the gear;
The absolute position measuring device, wherein a rotation cycle of the first rotor plate and a rotation cycle of the second rotor plate are different with respect to rotation of the spindle. The absolute position measuring device according to claim 1,
The first rotary encoder outputs phase signals having different values for different rotation angles within one rotation of the first rotor plate;
The second rotary encoder outputs phase signals having different values for different rotation angles within one rotation of the second rotor plate;
The absolute position measuring device, wherein the rotation speed of the second rotor plate is within one rotation with respect to the maximum rotation speed of the spindle within the movable range of the spindle. In the absolute position measuring device according to claim 1 or 2,
The absolute position measuring device, wherein the first rotor plate is supported by the rotating cylinder.

Images