JP2009186313A - Absolute position measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absolute position measuring device capable of reducing ricketiness between a key and a key groove, and improving measurement accuracy, concerning an absolute position measuring device of a spiral key groove system. <P>SOLUTION: A first key groove 32 and a second key groove 33 having each different lead angle are formed on the outer circumference of a spindle 3. A phase signal transmission means 4 has: a planar stator 40 into which the spindle 3 is inserted; a first cylindrical rotor 50 supported rotatably around the spindle 3, and having a first key 51 to be engaged with the first key groove 32; a second cylindrical rotor 60 supported rotatably around the spindle 3 on the outside of the first rotor 50, and having a second key 61 to be engaged with the second key groove 33; and a coil spring 70 as a pressing means for pressing the first rotor 50 and the second rotor 60 in each opposite rotation direction. <P>COPYRIGHT: (C)2009,JPO&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, for example, a configuration disclosed in Patent Document 1 is known.

FIG. 6 is a diagram showing a conventional absolute position measuring device disclosed in Patent Document 1. As shown in FIG.
This absolute position measuring device is a micrometer head 101, a main body 103 having a through-hole 102, a spindle 104 that is screwed into the through-hole 102 and moves in an axial direction while rotating, and according to the rotation of the spindle 104. Phase signal transmission means 105 for outputting phase signals of different periods.

The phase signal transmitting means 105 has one stator 106 and two rotors 107 and 108 that rotate around the axis of the spindle 104 while facing the stator 106, and two sets of rotary encoders are configured. . The first rotor 107 has a key 110 that engages with the linear first key groove 109 out of the two key grooves formed on the spindle 104, and rotates according to the rotation of the spindle 104. The second rotor 108 has a key 112 that engages with the spiral second key groove 111, and rotates at a speed different from that of the first rotor 107. And the phase signal of a different period according to rotation of each rotor 107,108 is output.
FIG. 7 shows the relationship between the rotational speed of the spindle 104 and the phase signals of the two sets of rotary encoders. As shown in the figure, when a phase change of 100 cycles is obtained from the first rotor 107 within the moving range of the spindle 104, a phase change of 99 cycles is obtained from the second rotor. In this way, by utilizing the fact that the phase difference of the phase signals (difference between θ1 and θ2 in the figure) is always different within the moving range of the spindle 104, the spindle 104 is determined from the number of rotations N of the spindle corresponding to the phase difference. The absolute position in the axial direction is calculated.

Japanese Patent Laying-Open No. 2003-207307 (FIG. 4)

However, in a micrometer in which the rotation of the spindle is transmitted to the rotor by the key and the key groove, a gap (backlash) for smooth sliding is provided between the key and the key groove. Shaking between keyways occurs. This rattling has a problem that the positioning accuracy in the rotational direction of the rotor with respect to the spindle is lowered, and the measurement accuracy of the micrometer is affected.
In particular, in the micrometer head 101 having the two key grooves 109 and 111 including the spiral key groove described in Patent Document 1, the two rotors 107 and 108 are each wobbled. , 108, the phase difference becomes excessive when rattling occurs in the direction in which the decrease in positioning accuracy is intensifying. Then, the spindle rotation speed corresponding to the excessive phase difference may be erroneously detected as N + 1 jumping over the original rotation speed N, so-called ABS jump may occur.

  An object of the present invention is to provide an absolute position measuring device that can reduce shakiness between a key and a key groove and improve measurement accuracy in a spiral keyway type absolute position measuring device. is there.

  The absolute position measuring device according to the present invention includes a main body, a spindle screwed into the main body and rotated around an axis so as to be movable in the axial direction, and changes at different periods depending on the rotation amount of the spindle Phase signal transmitting means for transmitting the two phase signals, and arithmetic processing means for calculating the absolute position of the spindle in the axial direction based on the two phase signals. A first key groove and a second key groove having different angles are formed, and the phase signal transmitting means has a plate-like stator fixed to the main body in a state where the spindle is inserted, and the spindle as a center. And a cylindrical first rotor having a first key that is rotatably supported by the first key groove and engages with the first key groove, and is rotatably supported around the spindle outside the first rotor. A cylindrical second rotor having a second key that engages with the second key groove, the first rotor facing the inner peripheral side portion of the stator, and the outer peripheral side portion of the stator Pressurizing means for pressurizing the second rotor facing the second rotor in opposite directions of rotation.

Here, as the pressurizing means, the first rotor can be pressurized in one rotational direction with respect to the spindle, and the second rotor can be pressurized in the rotational direction opposite to the first rotor with respect to the spindle. Anything is possible.
In this configuration, since the first key of the first rotor is engaged with the first key groove of the spindle, the rotation of the spindle causes the first rotor to rotate. Then, a phase signal that changes in the first period according to the amount of rotation of the spindle is transmitted between the first rotor and the stator. In addition, the rotation of the spindle is also transmitted to the second rotor by the engagement of the second key and the second key groove, and the rotation of the spindle is determined between the second rotor and the stator. A phase signal that changes in the second period is transmitted. At this time, since the lead angle is different between the first key groove and the second key groove, a difference occurs between the rotational speeds of the first rotor and the second rotor, and the phase signal transmitting means changes at different periods. Two phase signals are transmitted. Based on these phase signals, the absolute position of the spindle in the axial direction is calculated.

  According to this configuration, since the pressurizing means is provided to pressurize the first rotor and the second rotor in opposite directions of rotation, the keys of the two rotors are constantly in opposite directions of rotation. When pressed, rattling of the first rotor and the second rotor due to play (backlash) of the first key and the second key can be extremely reduced. Therefore, it is possible to prevent the measurement accuracy from being deteriorated and the ABS skipping.

  In the absolute position measuring apparatus of the present invention, the pressurizing means is an elastic member, and is disposed along the circumferential direction of the spindle on the side opposite to the stator from the first rotor and the second rotor, It is preferable that one end in the circumferential direction is connected to the first rotor and the other end is connected to the second rotor in a state of being elastically deformed in advance.

Here, torsion springs (coil springs or torsion bars) and mainspring springs are suitable as the pressurizing means made of an elastic member that can be arranged along the circumferential direction of the spindle.
According to this configuration, according to the relative rotational movement of the first rotor and the second rotor, the applying means is further elastically deformed, and one end thereof pressurizes the first rotor by the repulsive force of the elastic member, The other end pressurizes the second rotor in the opposite direction to the first rotor. In this way, rattling of each rotor can be suppressed simultaneously by one elastic member, and the number of parts is reduced, so that the configuration of the pressurizing means can be made compact.

Further, since the pressurizing means is arranged along the circumferential direction of the spindle, when an elastic member such as a coil spring or a mainspring spring is used as the pressurizing means, these elastic members are adapted to the shape of the spindle shaft. Can be easily formed and can be compactly accommodated in the space around the axis of the spindle.
In a conventional double-cylinder structure rotor, if the pressurizing means is disposed on the stator side of both rotors or disposed in the gap between the two rotors, the shape of each rotor needs to be largely changed. On the other hand, the pressurizing means of the present invention is arranged on the opposite side of the first rotor and the second rotor, so that the shape of the double cylinder structure rotor is maintained and the phase signal characteristics are secured However, pressure can be applied to both rotors.

  In the absolute position measuring apparatus of the present invention, either one of the first key groove and the second key groove is formed in a straight line, and one of the first key groove and the second key groove The other is formed in a spiral shape that substantially goes around the spindle, and the second rotor has a cylindrical extending portion that extends to the side opposite to the stator from the first rotor. The inner diameter of the portion is set to be substantially equal to the outer diameter of the spindle, and the extending portion is formed with a through-hole penetrating in the axial direction of the spindle, and the through-hole substantially makes a round around the spindle axis. The first rotor has a protruding portion that protrudes to the side opposite to the stator and is inserted into the through hole, and the pressure portion is protruded from the extending portion in the protruding portion. That one end of the means is connected Masui.

According to this configuration, if one of the key grooves is formed in a spiral shape that goes around the outer periphery of the spindle, the phase difference between the two rotors is rotated approximately once (even if the other key groove is formed in a straight line). (About 360 degrees) can be secured, and the processing of the groove portion is easier than when both key grooves are formed in a spiral shape.
In addition, since the extending portion is formed in the second rotor, and the second rotor is rotated around the spindle axis by the extending portion, compared with the case where the second rotor rotates outside the first rotor. Thus, it is possible to make it difficult to cause a shift in a direction perpendicular to the axis of the second rotor during rotation.

  Here, in order to ensure the phase difference of both rotors for approximately one rotation, it is necessary to configure the both ends of the pressurizing means to be relatively movable in the outer peripheral direction of the spindle by approximately one rotation. At that time, the protrusion of the first rotor must also be able to move relative to the extended portion of the second rotor by approximately one revolution. According to the present invention, since the through hole of the extending portion is formed in a C shape around the spindle axis, the protrusion can move along the through hole. Therefore, even if a protrusion is provided, both rotors can be smoothly moved relative to each other. Moreover, since the one end part of the pressurizing means is connected to the protrusion, even if the second rotor has the extending portion, the pressurizing means disposed on the side opposite to the stator from the second rotor. The first rotor can be pressurized.

Hereinafter, an embodiment according to an absolute position measuring apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a configuration of a micrometer head 1 as an embodiment of an absolute position measuring apparatus.

<Description of overall configuration>
The micrometer head 1 includes a main body 2, a spindle 3 that is screwed to the main body 2 and is axially movable by rotation, and two phase signals that change at different periods according to the amount of rotation of the spindle 3. A phase signal transmitting means 4 for transmitting the signal, an arithmetic processing means 5 for calculating the absolute position of the spindle 3 in the axial direction based on these phase signals, and a display means 6 for displaying the calculated absolute position of the spindle 3 Is provided.

  The main body 2 has a cylindrical shape having a through hole 21, and an internal thread 22 that is screwed into the spindle 3 is provided on the inner periphery of the through hole 21. The outer periphery of the front end side (left side in the figure) of the main body 2 is covered with an outer frame 7 indicated by a two-dot chain line.

  The spindle 3 is inserted into the through hole 21 of the main body 2 and is arranged in a state where both ends protrude from the main body. A feed screw 31 screwed to the female screw 22 of the main body 2 is provided on the outer periphery on the rear end side of the spindle 3 and can be moved in the axial direction by a rotating operation. A knob portion 8 for rotating the spindle 3 from the outside of the main body 2 is provided at the rear end of the spindle 3.

  Two key grooves 32 and 33 having different lead angles are provided on the outer periphery of the central portion of the spindle 3, and the first key groove 32 is provided in parallel with the axis of the spindle 3, and the second key groove Reference numeral 33 denotes a spiral with respect to the spindle 3. The positions of the start point and end point of the first key groove 32 and the second key groove 33 are substantially the same in the axial direction of the spindle 3, and the second key groove 33 is a spiral key groove that goes around the spindle 3 substantially. It is.

<Description of configuration of phase signal transmission means>
2 and 3 are a perspective view and an exploded perspective view showing the configuration of the phase signal transmission means 4.
The phase signal transmitting means 4 is disposed on the outer periphery of the spindle 3 on the front end side of the main body 2 and is covered with an outer frame 7 (FIG. 1). The phase signal transmission means 4 has a disk-shaped stator 40 fixed to the front end side of the main body 2 with the spindle 3 inserted, and a first key 51 that engages with the first key groove 32. A cylindrical first rotor 50 provided rotatably around the spindle 3 and a second key 61 engaged with the second key groove 33 are provided, and the spindle 3 outside the first rotor 50. A cylindrical second rotor 60 provided so as to be able to rotate about the rotor, and a coil spring 70 as a pressurizing means that pressurizes the rotors 50 and 60 in opposite directions of rotation.

  The two rotors 50 and 60 are both disposed on the same side (the front end side of the spindle 3 in this embodiment) with respect to the stator 40, and the first rotor 50 faces the inner peripheral side portion 41 of the stator 40, The second rotor 60 is disposed so as to face the outer peripheral side portion 42 of the stator 40. That is, both the rotors 50 and 60 form a double structure with the spindle 3 as the center, the first rotor 50 is disposed just outside the spindle 3, and the second rotor 60 is the first rotor Arranged outside the rotor 50. Such rotors 50 and 60 and the stator 40 constitute two sets of magnetic rotary encoders.

The first rotor 50 includes a first rotor plate 52 (FIG. 3) that faces the stator 40, and a first rotating cylinder 53 that rotatably holds the first rotor plate 52 while facing the stator 40. And a first key 51 engaged with the first key groove 32.
The first rotor plate 52 is a small circular plate having a hole (not shown) through which the spindle 3 is inserted. The first rotating cylinder 53 has a cylindrical shape that is externally fitted to the spindle 3 and is connected to the back surface of the first rotor plate 52 so as to rotatably support the first rotor plate 52. The first rotary cylinder 53 is provided with a first key hole 531 (FIG. 1) formed so as to penetrate in a direction orthogonal to the axis, and the first key 51 is screwed into the first key hole 531. ing.
The first rotating cylinder 53 is formed with a rod-shaped first protrusion 54 (protrusion of the present invention) that protrudes toward the front end side (anti-stator side) of the spindle 3. Is connected to one end 71 of the coil spring 7.

  Similar to the first rotor 50, the second rotor 60 has a second rotor plate 62 that faces the stator 40, and a second rotor plate 62 that rotatably holds the second rotor plate 62 while facing the stator 40. And a second key 61 that engages with the second keyway 33.

The second rotor plate 62 is an annular plate having an inner hole (not shown) enough to loosely fit the first rotor plate 52 inside, and is disposed outside the first rotor plate 52.
The second rotating cylinder 63 is connected to the back surface of the second rotor plate 62 and has a cylindrical shape having a hole 631 (FIG. 1) in which the first rotating cylinder 53 is loosely fitted inside. It is arranged outside. A first long hole 632 having a length in the circumferential direction is formed on the outer periphery of the second rotating cylinder 63. The first long hole 632 is for adjusting the position of the first key 51 of the first rotating cylinder 53 loosely fitted therein.

  The second rotating cylinder 63 is integrally formed with a cylindrical extending portion 64 on the front end side with respect to the first rotating cylinder 53. The extending portion 64 has an inner diameter set substantially equal to the outer diameter of the spindle 3, and the spindle 3 is directly inserted therethrough. The extending portion 64 further has a cylindrical protruding portion 65 formed on the front end side, and a coil spring 70 is disposed on the outer periphery of the protruding portion 65 so as to be rotatable about its axis.

A through hole 641 is formed in the extending portion 64 so as to penetrate in the axial direction of the spindle 3. The through hole 641 communicates from the front end surface of the extended portion 64 to the hole 631 in which the first rotary cylinder 53 is loosely fitted. The through hole 641 is formed as a C-shaped long hole that goes around the axis of the spindle 3 substantially. The projecting portion 54 of the first rotor 50 is inserted into the through hole 641 and can move along the C-shaped long hole.
Further, a rod-like second protrusion 66 protruding to the front end side of the spindle 3 is formed on the extended portion 64, and the other end 72 of the coil spring 70 is connected to the second protrusion 66. ing.
A second key hole 642 is formed through the outer periphery of the extending portion 64 from a direction perpendicular to the axis, and the second key 61 is screwed into the second key hole 642. The second key hole 642 is formed in a portion other than the through hole 641 that is a C-shaped long hole.

The coil spring 70 is disposed in a state where the outer periphery of the overhanging portion 65 is wound a plurality of times along the circumferential direction of the spindle 3 on the front end side of the second rotor 60. The coil spring 70 is elastically deformed in advance, and its one end 71 is locked to the first protrusion 54 of the first rotor 50, and the other end 72 is the second of the second rotor 60. The protrusion 66 is locked.
In this embodiment, the coil spring 70 is used as the pressurizing means. However, as the pressurizing means other than the coil spring 70, for example, a torsion bar or a mainspring spring which is one of torsion springs may be used. In other words, the pressurizing means may be an elastic member that can be arranged along the circumferential direction of the spindle 3.

<Description of micrometer head operation>
In FIG. 1, when the spindle 3 is rotated by the knob portion 8, the spindle 3 moves in the axial direction by screwing between the female screw 22 of the main body 2 and the feed screw 31 of the spindle 3.
2 and 3, when the spindle 3 rotates, the first key 51 of the first rotor 50 is engaged with the first key groove 32 of the spindle 3. The first rotor 50 rotates. Then, a phase signal that changes in the first period according to the amount of rotation of the spindle 3 is transmitted between the first rotor 50 and the stator 40.
Similarly, the rotation of the spindle 3 is also transmitted to the second rotor 60 by the engagement of the second key 61 and the second key groove 33. At this time, since the second rotating cylinder 63 supports the spindle 3 by the extending portion 64, the second rotating cylinder 63 rotates with respect to the spindle 3. Then, a phase signal that changes in the second period according to the amount of rotation of the spindle 3 is transmitted between the second rotor 60 and the stator 40.

  At this time, since the linear first key groove 32 and the spiral second key groove 33 have different lead angles, the first rotating cylinder 53 and the second rotation are rotated when the spindle 3 makes one rotation. The cylinder 63 is rotated at different rotation amounts (rotation phases). When the first and second rotating cylinders 53, 63 are rotated by the rotation of the spindle 3, the first rotor plate 52 is rotated together with the first rotating cylinder 53, and the second rotor together with the second rotating cylinder 63 is rotated. The plate 62 is rotated. In this way, a difference occurs in each rotational phase of the first rotor plate 52 and the second rotor plate 62, and changes at different periods depending on the relative positional relationship between the rotor plates 52 and 62 and the stator 40. Two phase signals are transmitted.

  Here, the first rotating cylinder 53 and the second rotating cylinder 63 are connected via a coil spring 70 and are in a state of being pressurized in opposite rotational directions. That is, the first rotor 50 is pressurized in one rotation direction with respect to the spindle 3 by the coil spring 70, and the second rotor 60 is in the rotation direction opposite to the first rotor 50 with respect to the spindle 3. It is pressurized.

FIG. 4 is a view showing a cross section of the spindle 3 and conceptually shows the positional relationship of the keys 51 and 61 with respect to the key grooves 32 and 33.
In order for the keys 51 and 61 to slide smoothly while being engaged with the key grooves 32 and 33, it is necessary to provide a predetermined play (backlash). As shown in FIG. As a result, the keys 51 and 61 are freely moved around the axis of the spindle 3, and there is a problem that the keys 51 and 61 are rattled due to play while the spindle 3 is rotating.
On the other hand, in the present embodiment, the keys 51 and 61 are constantly urged in the direction indicated by the arrow in FIG. The play with 33 is made difficult to produce rattling.

FIG. 5 is a view of the phase signal generating means 4 as seen from the front end side, and the action of the coil spring 70 will be specifically described based on this figure.
The coil spring 70 has one end 71 connected to the first protrusion 54 and the other end 72 connected to the second protrusion 66 in a state where both ends 71 and 72 of the spring are expanded in the direction in which the coil diameter increases. It is connected to the. As a result, the first rotor 50 and the second rotor 60 are pressurized so as to rotate in a direction in which the diameter of the coil spring 70 contracts (pressurized in the direction of the arrow in the figure).
In this state, when the two rotating cylinders 53 and 63 rotate at different rotational phases, the first protrusion 54 to which the one end 71 of the coil spring 70 is connected is a through-hole that is a C-shaped long hole. 641. At this time, the coil spring 70 constantly pressurizes the two rotating cylinders 53 and 63 in the same rotational direction regardless of the position of the first protrusion 54. Should be set.
In the present embodiment, the case where the coil spring 70 is attached so that the elastic force acts in the direction in which the diameter of the coil spring 70 contracts will be described. On the contrary, the elastic force in the direction in which the diameter of the coil spring 70 increases. The coil spring 70 may be attached so that

In this way, the rotation speed and rotation angle of the spindle 3 are obtained by the arithmetic processing means 5 (FIG. 1) based on the rotation phase of the first rotor plate 52 and the rotation phase of the second rotor plate 62, and the spindle The absolute position of the spindle 3 in the axial direction is calculated by multiplying the number of revolutions 3 by the advance / retreat pitch per revolution of the spindle 3. The absolute position of the spindle 3 is displayed on the display means 6.
With the above operation, the absolute position of the spindle 3 in the axial direction can be calculated.

<Effect of embodiment>
According to this embodiment, the following effects can be achieved.
(1) Since the coil springs 70 that pressurize the first rotor 50 and the second rotor 60 in opposite directions are provided, the keys 51 and 61 of the two rotors 50 and 60 are opposite to each other. The backlash of the first rotor 50 and the second rotor 60 due to the play (backlash) of the keys 51 and 61 can be made extremely small. Therefore, it is possible to prevent the measurement accuracy from being deteriorated and the ABS jump.

(2) The coil spring 70 is further elastically deformed in accordance with the relative rotational movement of the first rotor 50 and the second rotor 60, and the one end portion 71 pressurizes the first rotor 50 by the repulsive force. The other end 72 pressurizes the second rotor 60 in the direction opposite to the first rotor 50. In this way, rattling of the rotors 50 and 60 can be simultaneously suppressed by the single coil spring 70, and the number of parts can be reduced, so that the configuration of the pressurizing means can be made compact.

(3) Since the coil spring 70 is only arranged in a state of being wound a plurality of times along the circumferential direction of the spindle 3, the pressurizing means can be easily formed, and the space around the axis of the spindle 3 can be formed. Can fit in a compact.

(4) In the conventional double-cylinder structure rotor shown in FIG. 6, if the coil spring is arranged on the stator side of both rotors or arranged in the gap between the two rotors, the shape of each rotor needs to be greatly changed. Occurs. On the other hand, in the pressurizing means of the present invention, the coil spring 70 is disposed on the side opposite to the stator 40 of the first rotor 50 and the second rotor. It is possible to apply pressure to the rotors 50 and 60 while maintaining the shape and ensuring the characteristics of the phase signal.

(5) If the second key groove 33 is formed in a spiral shape that substantially goes around the outer periphery of the spindle 3, even if the first key groove 32 is formed in a straight line shape, the phase difference between the rotors 50 and 60 is obtained. Can be secured for approximately one rotation (about 360 degrees), and the processing of the groove portion is facilitated as compared with the case where both the key grooves 32 and 33 are formed in a spiral shape.

(6) The extending portion 64 is formed in the second rotor 60, and the second rotor 60 rotates around the axis of the spindle 3 by the extending portion 64, so that the second rotor 60 is replaced with the first rotor 50. As compared with the case where the outer side is rotated, it is possible to make it difficult to cause a shift in the direction perpendicular to the axis of the second rotor 60 during the rotation.

(7) In order to secure the phase difference between the rotors 50 and 60 by approximately one rotation, both ends of the coil spring 70 can be relatively moved in the outer circumferential direction of the spindle 3 by approximately one rotation, and the protrusion of the first rotor 50 The portion 54 must be configured to move relative to the extending portion 64 of the second rotor 60 by approximately one rotation, but the through hole 641 of the extending portion 64 is C-shaped around the spindle 3 axis. Thus, the protrusion 54 can move along the through hole 641. Therefore, even if the protrusion 54 is provided, both the rotors 50 and 60 can smoothly move relative to each other. In the present embodiment, since one end 71 of the coil spring 70 is connected to the protrusion 54, the anti-stator is more anti-stator than the second rotor 60 even if the second rotor 60 has the extended portion 64. The first rotor 50 can be pressurized by a coil spring 70 disposed on the side.

<Modification of the present invention>
It should be noted that the present invention is not limited to the above-described embodiments, 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 a magnetic rotary encoder is used as a configuration for detecting the rotational phase of the rotors 50 and 60 by the stator 40 in the phase signal transmission means has been described as an example. The detection configuration may be a capacitance encoder, an optical encoder, or the like, and the configuration is not particularly limited.

  The absolute position measuring device of the present invention is not limited to the micrometer head 1 and may be an inner measuring or outer measuring micrometer, and further, a measuring device for detecting the absolute position of the spindle 3 that moves forward and backward by rotation. If it is.

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

Sectional drawing which shows the micrometer head which concerns on one Embodiment of the absolute position measuring apparatus of this invention. The perspective view which shows the phase signal transmission means of the said micrometer head. The disassembled perspective view which shows the phase signal transmission means of the said micrometer head. The figure explaining the direction of the pressurization with respect to the key in the said micrometer head. The figure which looked at the said phase signal generation means from the front end side. Sectional drawing which shows 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.

Explanation of symbols

1 ... Micrometer head (absolute position measuring device)
DESCRIPTION OF SYMBOLS 2 ... Main body 3 ... Spindle 4 ... Phase signal transmission means 5 ... Arithmetic processing means 32 ... 1st keyway 33 ... 2nd keyway 40 Stator 50 1st rotor 51 1st key 54 1st protrusion ( protrusion)
60 Second rotor 61 Second key 64 Extension portion 70 ... Coil spring (pressurizing means)
71 ... One end portion 72 ... The other end portion 641 ... A through hole.

Claims (3)

A main body, a spindle that is screwed to the main body and that rotates around an axis and is movable in the axial direction, and a phase that transmits two phase signals that change at different periods according to the amount of rotation of the spindle. Signal transmission means, and arithmetic processing means for calculating the absolute position of the spindle in the axial direction based on the two phase signals,
The spindle is formed with a first key groove and a second key groove having different lead angles on the outer periphery,
The phase signal transmitting means is
A plate-like stator fixed to the main body in a state where the spindle is inserted;
A cylindrical first rotor having a first key supported rotatably about the spindle and engaged with the first keyway;
A cylindrical second rotor having a second key that is rotatably supported about the spindle outside the first rotor and engages with the second keyway;
Pressurizing means for pressurizing the first rotor facing the inner peripheral portion of the stator and the second rotor facing the outer peripheral portion of the stator in opposite directions of rotation. Absolute position measuring device. The absolute position measuring device according to claim 1,
The pressurizing means is an elastic member, and is arranged along the circumferential direction of the spindle on the side opposite to the stator from the first rotor and the second rotor, and is elastically deformed in advance in the circumferential direction. One end portion is connected to the first rotor and the other end portion is connected to the second rotor. The absolute position measuring device according to claim 2,
Either one of the first key groove and the second key groove is formed in a straight line,
Either one of the first key groove and the second key groove is formed in a spiral shape that substantially goes around the spindle,
The second rotor has a cylindrical extending portion that extends on the side opposite to the stator from the first rotor, and an inner diameter of the extending portion is set substantially equal to an outer diameter of the spindle,
A through-hole penetrating in the axial direction of the spindle is formed in the extending portion, and the through-hole is formed in a C-shape that substantially goes around the spindle axis,
The first rotor has a protruding portion that protrudes toward the anti-stator side and is inserted into the through-hole,
The absolute position measuring device, wherein one end portion of the pressurizing means is connected to a portion of the protruding portion protruding from the extending portion.

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