JP7106735B2 - Whirl-stop for optical measuring instruments - Google Patents

Description

TECHNICAL FIELD The present invention relates to a measuring instrument having an optical linear encoder, and more particularly to a detent suitable for use in a pencil-type optical measuring instrument that is used in contact with an object to be measured.

An example of a conventional linear encoder is described in US Pat. In this publication, in order to obtain a highly reliable compact linear encoder that can realize a compact actuator, a flat portion formed at the end of a movable shaft is photolithographically patterned with high reflectance and low reflectance stripe patterns. A formed tape-like scale is attached. Permanent magnets are attached to a plurality of positions in the circumferential direction different from the flat portion of the shaft, and a stator having a three-phase coil is arranged outside the permanent magnets. An optical sensor having a plurality of layers is arranged at a position corresponding to the scale portion of the stator so as to face the scale portion. In order to prevent the scale portion from rotating within the stator, a rectangular opening corresponding to the shape of the flat portion of the shaft is formed in the guide member provided at the end of the stator.

Patent Literature 2 discloses a contact-type displacement measuring instrument. In this publication, a slide bearing is used in the sliding portion of the probe member, and a core constituting a differential transformer is attached to one end of the probe member that moves up and down together with the contactor. An outer cylinder surrounding the probe incorporates a coil unit forming a differential transformer at a position corresponding to the core. Furthermore, Patent Document 3 discloses a configuration for preventing rotation of a reciprocating movable member in a reciprocating device used for picking up parts in a semiconductor manufacturing apparatus or the like.

Japanese Patent Application Laid-Open No. 2008-215911 (particularly its paragraph 0021) JP 2012-185019 A JP 2008-82512 A

2. Description of the Related Art Small contact sensors that measure displacement by bringing a probe into contact with an object to be measured are used in many applications. Among them, the so-called pencil-type optical measuring instrument is compact and has a high degree of mounting flexibility, and is highly resistant to weather and environment. In Patent Document 1, it is realized as an actuator having an optical linear encoder.

In optical linear encoders, particularly in the case of a pencil type encoder, it is common for the sensor to have a cylindrically formed probe for ease of attachment of the sensor. On the other hand, since the light from the light source is transmitted or reflected by the scale surface and reaches the light receiving section, it is desirable that the scale surface of the sensor be flat in order to keep the detection intensity constant.

Therefore, in Patent Document 1, the cylindrical surface is chamfered to form a flat surface, and in order to reduce the sliding resistance as much as possible, a cylindrical probe formed to be rotatable within the stator without contacting the stator is detected as the scale surface. A rectangular hole provided on the stator side regulates the rotation so that the parts can always maintain the same relationship.

As a result, there is a small gap between the rectangular hole and the chamfered shape of the scale surface for insertion and axial movement of the probe, which may cause wear due to mutual contact and friction due to sliding resistance. be.

The one described in Patent Document 2 describes a miniaturized linear encoder, but since it is a working transformer type and not an optical type, the rotation of the probe is allowed, so the scale surface and detection in the optical sensor It is not always necessary to maintain the relative relationship of the parts. In addition, in the apparatus disclosed in Patent Document 2, a bellows is used to prevent foreign matter such as oil from entering from an external contamination source in order to maintain the environmental resistance of the linear encoder.

Contamination with foreign matter causes deterioration of the detection part and must be avoided. A probe sealing and rotational support method with reduced sliding resistance is desired.

In Patent Document 3, a movable magnet and a fixed magnet are arranged to face each other along the reciprocating direction of the reciprocating movable member, thereby generating a return force for the reciprocating motion and restricting the circumferential motion of the movable member. . However, in the device described in this publication as well, the rotation of the movable member is prevented by physically restricting rotation by making the shape of the slide bearing provided at the end of the main body case different from the circular shape. Wear on the bearings due to stick-slip is not taken into account since the contact prevents rotation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above deficiencies or unconsidered considerations of the prior art, and its object is to provide a miniature pencil-type optical displacement sensor having a measurement probe held essentially contactlessly within a sleeve. To suppress the occurrence of friction and wear between fixed members including a measuring probe and a sleeve caused by reciprocating motion of the measuring probe while always maintaining a constant circumferential positional relationship between the measuring probe and the sleeve in a measuring instrument. . Another object of the present invention, in addition to the above object, is to simplify the configuration of a small pencil-type optical displacement measuring instrument and to eliminate or reduce the damping action of the air inside the measuring instrument caused by the reciprocating motion of the probe. .

The present invention for achieving the above object is characterized in that a rod-shaped movable part having a probe contacting an object to be measured arranged on one end side and a scale arranged on the other end side, and a non-measurement probe of the movable part a fixed part having a cylindrical member that accommodates the side, a bearing part that supports the movable part, and a detection part arranged to face the scale, wherein: The movable part has a movable part anti-rotation means for preventing rotation with respect to the fixed part, the fixed part has a fixed part anti-rotation means that engages with the movable part anti-rotation means, The anti-rotation means has a projection formed on the outer peripheral surface of the movable part, the anti-rotation means for the fixed part has a guide part that engages with the projection and guides the movement of the movable part, The projection and the guide section each have a permanent magnet arranged along the movement direction and a permanent magnet arranged facing the movement direction, and the permanent magnet on the movable section side and the magnetic poles of the permanent magnets on the stationary part side facing the permanent magnets on the movable part side are the same.

Further, a plurality of permanent magnets divided in the circumferential direction are arranged in the bearing portion provided in the fixed portion, and the bearing portion is provided at a position corresponding to the bearing portion on the outer circumference of the movable portion. A plurality of permanent magnets divided in the circumferential direction having the number of magnetic poles corresponding to the number of permanent magnets may be arranged.

Further, the scale of the movable part is an optical linear scale in which a large number of reflecting parts and transmitting parts are regularly formed in the moving direction, and the detecting part of the fixed part receives reflected light of light projected on the scale or A photodiode may be included to detect transmitted light.
Also, the guide portion may be a groove.

Further, as another form, a rod-shaped movable part having one end provided with a probe that abuts on the object to be measured and a scale provided at the other end, and the opposite side of the probe to this movable part are accommodated. A displacement measuring instrument comprising a fixed part having a cylindrical member, a bearing part supporting an intermediate part of the movable part on one end side, and a detecting part disposed facing the scale, a movable portion anti-rotation means and a fixed portion anti-rotation means are provided on the movable portion and fixed portion anti-rotation means for preventing the portion from rotating about its longitudinal axis with respect to the fixed portion; The means and said fixed portion anti-rotation means may both comprise magnet means.

In this feature, the movable portion anti-rotation means has an oval or rectangular projection provided closer to the scale than the bearing portion and a permanent magnet arranged on the peripheral surface of the projection in the longitudinal direction. and the fixing portion anti-rotation means has an oval or rectangular groove formed according to the longitudinal movement range of the projection and a permanent magnet disposed on the longitudinal inner peripheral surface of the groove, It is preferable that the magnetic poles of the permanent magnet on the movable part side and the permanent magnet on the fixed part side facing the permanent magnet on the movable part side have the same polarity, and the permanent magnet on the fixed part side is arranged in the longitudinal direction of the groove. A plurality of permanent magnets may be arranged at intervals on the inner surface, and coil magnets may be arranged between the permanent magnets at intervals.

In the above feature, a permanent magnet divided into a plurality of poles in the circumferential direction is arranged in a bearing portion provided on one end side of the fixed portion, and a permanent magnet is provided at a position corresponding to the bearing portion on the outer periphery of the movable portion. , a plurality of circumferentially divided permanent magnets having a number of magnetic poles corresponding to the number of magnetic poles of the permanent magnets of the bearing portion may be arranged, and the scale of the movable portion has a reflective portion and a transmissive portion arranged in the longitudinal direction. The optical linear scale may be formed in large numbers, and the detection section of the fixed section may include a photodiode for detecting reflected light or transmitted light of light projected onto the scale. Further, a spring is provided between the detent of the movable portion and the detection portion of the fixed portion, and both end surfaces of the detent of the detent in the oval or rectangular shape in the longitudinal direction and the oval or rectangular shape of the fixed portion are provided. Permanent magnets may be disposed on both inner end surfaces of the groove in the longitudinal direction, and the magnetic poles of the opposing permanent magnets may be the same.

According to the present invention, the detent for preventing the circumferential displacement of the probe is composed of a permanent magnet. Since it is possible to maintain a non-contact state with respect to the sleeve containing the measurement probe, it is possible to suppress the occurrence of friction and wear between the measurement probe and the fixed member. In addition, it is possible to omit conventionally used parts such as bellows and springs, simplifying the configuration of the displacement measuring instrument and reducing the compression of the air inside the measuring instrument. is eliminated or reduced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows one Example of the pencil type|mold displacement measuring instrument which concerns on this invention, The same figure (a) is A view of the same figure (b), The same figure (b) is a longitudinal cross-sectional view. It is a perspective view of the movable part side (the same figure (a)) and stationary side (the same figure (b)) of the displacement measuring device shown in FIG. FIG. 2A is a top view of the detent part of the displacement measuring device shown in FIG. 1, and FIG. 2 is a diagram for explaining pitching and rolling in the displacement measuring device shown in FIG. 1; FIG. FIG. 4 is a view of another embodiment of the detent part of the displacement measuring instrument according to the present invention, corresponding to FIG. 3;

An embodiment of a small-sized pencil-type displacement measuring instrument 100 according to the present invention will be described below with reference to the drawings. The small pencil-type displacement measuring instrument 100 is an encoded high-precision contact-type digital length measuring instrument that employs an optical scale. . Further, by providing the bellows boot 14 on the stylus 10 side, waterproofness and environmental resistance can be improved, and resistance to common coolants and oils can be imparted.

FIG. 1 shows a vertical cross-sectional view (FIG. 1(b)) and a top view of a portion A thereof (FIG. 1(a)) of a small-sized pencil-type displacement measuring device 100 according to the present invention. The displacement measuring instrument 100 is roughly divided into a movable portion 20 having a probe 10 at one end, and a fixed portion 62 having a substantially cylindrical outer shape and housing a portion of the movable portion 20 . A portion of the movable portion 20 is shown in FIG. 2(a), and a portion of the fixed portion 62 is shown in an exploded perspective view in FIG. 2(b).

In FIG. 1(b), the movable part 20 has, on one end side, a substantially hemispherical contactor 12 that abuts against an object to be measured (not shown) and a probe 10 that holds the contactor. A rod-shaped shaft portion 30 is attached to the side of the probe 10 opposite to the contactor. A detent 80, which is a characteristic structure of the present invention and whose details will be described later, is provided on the side of the shaft 30 opposite to the stylus.

A stepped shaft portion 32 is formed in the movable portion 20 , and a detent 80 extending in the axial direction and protruding radially outward from the stepped shaft portion 32 is provided at one circumferential location. A holding portion 34 having a diameter smaller than that of the stepped shaft portion 32 is formed on the opposite side of the stepped shaft portion 32 so as to wind a coil spring 38, which will be described later. As shown in FIG. 2(a), the holding portion 34 has a columnar shape (solid shaft shape) from the side of the stepped shaft portion 32 to the axial intermediate portion. A cutoff portion 35 having a semicircular cross-section cut along a horizontal plane is formed.

On the axial end side of the cut-off portion 35, a scale mounting portion 36 is formed by horizontally cutting the semicircular shape by the thickness of the optical scale 76. As shown in FIG. That is, when the optical scale 76 is attached to the scale attachment portion 36 using an adhesive or the like, the cut depth is such that the upper surface of the scale 76 substantially coincides with the upper surface of the cut-off portion 35 and forms a bisected surface of a circle. are adjusting.

The optical scale 76 is known as a linear scale. Reflective portions are formed on a transparent substrate of glass or the like at equal intervals in the longitudinal direction by etching or the like. there is The widths of the transmissive portions and the reflective portions are substantially equal, and the pitch between pairs of the transmissive portions and the reflective portions is, for example, 20 μm. That is, the widths of the transmissive portion and the reflective portion are each approximately 10 μm.

Reference numeral 40 denotes a bearing (also referred to as a bearing) that supports the movement of the movable part in the horizontal direction (X direction) in FIG. 1(b) with low friction and low contamination. We are hiring. In one embodiment of the bearing (bearing portion) 40, the bearing 40 has a magnetic bearing composed of a permanent magnet in which the S pole and the N pole are alternately arranged in a plurality of pieces divided in the circumferential direction. On the outer periphery of the shaft portion 30 of the movable portion 20, permanent magnets having the same magnetic poles and the same number of permanent magnets as those formed in the bearing 40 are divided and arranged in the circumferential direction. Since the shaft portion 30 of the movable portion 20 moves in the X direction relative to the bearing 40 , the longitudinal length of the surface of the movable portion 20 facing the bearing 40 is longer than the length of the bearing 40 . Therefore, when the bearing 40 is composed of a permanent magnet, it is desirable that the length of the permanent magnet provided on the shaft portion 30 is equal to or longer than the sum of the length of the bearing 40 and the displacement of the movable portion 20 in the X direction. .

A bellows boot 14 is airtightly attached between the distal end side (left side in FIG. 1(b)) of the fixed part 62 and the opposite contact end surface of the probe 10, and the movable part 20 moves relative to the fixed part 62. Even so, external dust such as oil and coolant contained in the surrounding environment of the displacement measuring instrument 100 is prevented from entering the interior of the fixed portion 62 . The bellows boot 14 is formed with low rigidity so as not to affect the measurement of the stylus 10, and is made of an environment-resistant material.

On the side opposite to the bellows boot from the bearing 40 of the fixing portion 62 (on the right side in FIG. 1(b)), the connection side to the bearing 40 is cylindrical in order to make the outer diameter of the displacement measuring device 100 substantially cylindrical and airtight. A case 42 having a number of notches and a thin cylindrical cover 60 along the outer periphery of the cover guide portion 44 of the case 42 are provided. The cover 60 covers substantially the entire length of the case 42 in the hand direction. A terminal portion 90 to which a signal line 92 and an electric wire 94 extending to the electronic components of the displacement measuring instrument 100 are connected is arranged at the end opposite to the side where the cover 60 is fitted to the case 42 . The cover 60 is hermetically sealed by a mechanical sealing means such as an O-ring or a method such as adhesion. A cable for connecting to a controller for controlling the displacement measuring device 100 is connected to the terminal section 90, but illustration thereof is omitted.

FIG. 2(b) shows the fixed part 62 with the cover 60 and the bearing 40 removed. The case 42 and its surroundings will be further described with reference to FIG. 2(b). The case 42 is formed by wire electric discharge machining or the like so as to have a plurality of complicated-shaped notches. That is, the substantially left half portion of FIG. 2B is formed into a hollow cylindrical shape up to the spring abutting portion 45 and has a shape for receiving the movable portion 20 . An oblong groove 50 is formed on the upper surface, and serves as a rotation prevention groove for allowing the rotation prevention 80 of the movable portion 20 to move in the longitudinal direction. Groove edge magnets 82 are attached to the periphery of the groove 50 by adhesion or the like. The detent 80 of the movable part 20 and the groove edge magnet 82 constitute a detent 84 .

A hole 48 is also formed on the lower side and used for adjustment and the like. The spring abutting portion 45 is a wall formed substantially only on the upper half, and holds the coil spring 38 between it and the wall surface of the stepped shaft portion 32 of the movable portion 20 . The coil spring 38 is for returning the tracing stylus 10 leftward in the X direction after the displacement measuring instrument 100 is used. The inner surface of the cover guide portion 44 and the inner surface of the spring holding portion 46 connected to the spring contact portion 45 hold and guide the coil spring 38 .

A substrate receiving portion 52 is formed in a pedestal shape on the right side of the spring contact portion 45, and together with a substrate receiving portion 56 formed at the end of the fixing portion 62 opposite to the bearing portion, a light receiving portion 72 forming an optical encoder is formed. The mounted electronic board 70 is mounted. Therefore, both board receiving portions 52, 56 form the same plane, and the end board receiving portion 56 is a truncated cylinder slightly larger than a semicircle. The electronic board 70 has a light receiving part 72 and a circuit element 74 mounted on its lower surface and is placed on the board receiving parts 52 and 56 . It is secured with a set screw 78 using 70a. Similarly, the other end is fixed by a set screw 78 using a screw hole 56 a formed in the board receiving portion 56 and a mounting hole 70 b formed in the electronic board 70 . The light receiving section 72 has a light receiving element such as a photodiode, and the light receiving element detects reflected light or transmitted light of light projected on a reflecting section or a transmitting section forming a linear scale.

With the electronic board 70 fixed to the board receiving parts 52 and 56, the distance between the lower surface of the light receiving part 72 and the upper surface of the optical scale 76 attached to the movable part 20 is set to be an appropriate distance for optical measurement. , the horizontal heights of the substrate receiving portions 52 and 56 are set. In order to accommodate the light receiving portion 72 and the circuit element 74 mounted on the electronic board 70 in the fixed portion 62, a semicircular cutout portion 59 is formed in the fixed portion. A cutout portion 58 is formed in the lower portion of 59 so as to extend in the longitudinal direction for ease of assembly and the like. As described above, the electronic board 70 is provided with a plurality of signal lines 92 and electric wires 94 (only one of each is shown for simplicity in FIG. 1B) from a terminal portion (not shown).

Details of the anti-rotation portion 84 of the displacement measuring instrument 100 configured in this way will be described with reference to FIGS. 3 and 4. FIG. FIG. 3(a) is a development view of the anti-rotation portion 84 in the circumferential direction, corresponding to FIG. 1(a), and FIG. 3(b) is a cross-sectional view taken along line BB of FIG. 3(a). 4A and 4B are diagrams for explaining the relative displacement between the movable portion 20 and the fixed portion 62. FIG. 4A is a diagram for explaining yaw movement and roll movement, and FIG. FIG. 4(c) shows the relative displacement of the portion 62 and the relative displacement of the movable portion 20 and the fixed portion 62 due to yaw motion.

An oval groove 50 (part of which is shown in FIG. 3A) is formed in the longitudinal direction across the cover guide portion 44 and the spring holding portion 46 of the fixed portion 62 . On the inner peripheral surface of the groove 50 , the innermost permanent magnet (N pole) 822 and the outer permanent magnet (S pole) 821 are laminated over the entire circumference of the groove 50 . On the other hand, an oval groove is formed in the stepped shaft portion 32 of the movable portion 20, and a detent 80 is fitted in this groove. The detent 80 is an elliptical column, and a high-rigidity metal fixed shaft 806 having a rectangular cross section is arranged in the center. 801 are laminated and attached by adhesion or the like. On the other hand, on the short side of the fixed shaft 806, a permanent magnet (N pole) 803 and a permanent magnet (S pole) 804 are layered in order from the inside and attached by adhesion or the like. The corners of the magnets 801 to 804 are hardened with resin or the like and then rounded to complete the detent 80 . Materials for the above magnets are preferably materials capable of generating a high magnetic force. For example, rare earth magnets such as neodymium, samarium cobalt, and ferrite magnets are used.

Since the groove edge magnet 82 consisting of the magnets 821 and 822 and arranged on the inner periphery of the groove 50 and the magnetic poles of the magnets 801 to 804 arranged in the detent 80 are constructed in this way, the groove edge magnet 82 The fixed part 62 and the anti-rotation 80 provided always generate a repulsive force that repels each other, and when the movable part 20 moves in the longitudinal direction, even if it rotates (rolls) around its longitudinal axis. Even if a force is applied, the interaction of the magnets 822 and 801 of the anti-rotation portion 84 generates a restoring force to keep the position in the rotational direction constant. Therefore, the anti-rotation stopper 80 is also prevented from coming into contact with the fixed portion 62, and the occurrence of contamination due to the movement of the movable portion 20 can be prevented. Moreover, since the detent 80 is oval and the magnets 801 and 802 have a predetermined length in the longitudinal direction, displacement (yaw movement) of the movable portion 20 around a certain point can be prevented. Furthermore, since the corners of the detent 80 are rounded, even if the detent 80 comes into contact with the end of the groove 50, contamination such as dust is prevented.

On the other hand, when the measurement is finished and the probe 10 is released from the object to be measured, the movable part 20 returns to its initial position by the restoring force of the coil spring 38. The interaction between the magnet 822 on the inner surface of the groove 50 and the magnet 822 on the inner surface of the groove 50 buffers the restoring operation and avoids contact with the end arc portion of the groove 50. In this case also, the occurrence of contamination can be prevented.

In addition, a magnetic spring is generated by the interaction of the magnets 804 and 822, and it is possible to reduce the influence of changes in the absolute displacement of the movable part 20 during measurement and to apply a substantially constant contact stress to the object to be measured. and the measurement accuracy is improved. Furthermore, the magnetic spring makes it possible to keep the contact stress substantially constant even when measuring in an environment without gravity or in a vacuum environment without air. Furthermore, since the bellows boot 14 and the case 54 are airtight, when the movable part 20 is displaced, the internal air acts as an air spring, which acts as a resistance during measurement. It becomes possible to move the movable part 20 in the longitudinal direction (X direction).

As a result of the interaction between the magnet 822 of the groove 50 and the anti-rotation magnet 801, the roll movement is suppressed, and as a result, the optical scale 76 attached to the movable part 20 is moved to the position indicated by the broken line for some reason, as shown in FIG. 4(b). Even if the position changes to 76a, the position is immediately restored, and the gap d between the optical scale 76 and the light receiving section 72 is returned to enable highly accurate measurement. Similarly, even if the movable portion 20 is tilted by Δθ from the longitudinal direction for some reason and the optical scale 76 changes to a position 76b as shown in FIG. is immediately restored, and the relative positions of the optical scale 76 and the light receiving section 72 are kept constant.

FIG. 5 shows a modification of the anti-rotation portion 84 according to the present invention. This modification differs from the above-described embodiment in that the permanent magnets attached to the inner peripheral surface of the groove 50 formed in the fixing portion 62 are divided, and the divided magnets are arranged at predetermined intervals so that the adjacent magnets are separated from each other. The reason is that the coil magnet is placed in the The magnet in the arc portion of the groove 50 is not divided and has the same structure as the embodiment shown in FIG.

Specifically, split magnets 822 and 821 each having a predetermined length in the longitudinal direction are laminated on the inner surface of the longitudinal portion of the groove 50 and disposed by adhesion or the like, and a coil magnet 825 is arranged between the adjacent split magnets 822 and 821. are arranged. The coil magnet 825 is a magnet in which a coil 812 is wound around a core 811, and the coil 812 is connected to the electronic board 70 by an electric wire (not shown). By controlling the current applied to the ends of the coil 812, the generated magnetic force is varied. In this case, by controlling the magnitude and direction of the current applied to each coil 812, the strength and direction of the magnetic force generated by the coil 812 can be changed according to the position in the longitudinal direction of the movable part 20. The moving speed of the movable part 20 can be changed according to the measurement position, and an optimum longitudinal moving speed of the movable part 20 which is constant or variable can be obtained. Further, by controlling the direction and direction of the applied current, the measuring pressure (pressing force) applied to the object to be measured by the stylus 10 can be adjusted.

As described above, according to the present embodiment and the modified example, in the pencil-type displacement measuring instrument for contact measurement, permanent magnets are arranged in both the anti-rotation of the movable part and the grooves of the fixed part. Contact with the fixed part can be avoided as much as possible, and the occurrence of contamination inside the displacement measuring instrument can be prevented. In addition, even if contamination occurs, the magnetic metal powder can be attracted to the magnet, thereby preventing adverse effects of deterioration of measurement accuracy due to contamination on the optical displacement measuring unit. Furthermore, since the magnet restores the relative yaw motion and roll motion of the movable portion with respect to the fixed portion, the relative posture between the optical scale and the light receiving portion can be kept constant.

DESCRIPTION OF SYMBOLS 10... Probe, 12... Contactor, 14... Accordion boot, 20... Movable part, 30... Shaft part, 32... Stepped shaft part, 32a... Spring contact surface, 34... Holding part, 34a... Spring winding surface , 35... Cut-off part 36... Scale attachment part 38... Coil spring 40... Bearing (part) 42... Case 43... Case end part 44... Cover guide part 45... Spring contact part 46... Spring Holding part 48 Hole 50 Groove (for anti-rotation) 52 Board receiving part 52a Mounting screw hole 54 Case 56 Board receiving part 56a Mounting screw hole 58, 59 Notch Part 60... Cover 62... Fixed part 70... Electronic board 70a, 70b... Mounting hole 72... Light receiving part 74... Circuit element 76... (Optical) scale 76a... Scale (after roll displacement) 76b... Scale (after yaw displacement), 78... Set screw, 80... Whirl-stop, 82... Groove edge magnet, 84... Whirl-stop part, 90... Terminal part, 92... Signal wire, 94... Electric wire, 100... ( Pencil type) Displacement measuring instrument 801, 803 Permanent magnet (N pole) 802, 804 Permanent magnet (S pole) 806 Fixed shaft 811 Core 812 Coil 821 Permanent magnet (S pole) , 822 Permanent magnet (N pole) 825 Coil magnet d Gap Δθ Yaw displacement amount

Claims (4)

A rod-shaped movable part having a probe contacting an object to be measured arranged on one end side and a scale arranged on the other end side; A displacement measuring instrument comprising: a fixed portion having a bearing portion that supports the movable portion;
the movable part has a movable part anti-rotation means for preventing rotation with respect to the fixed part;
The fixed part has a fixed part anti-rotation means that engages with the movable part anti-rotation means,
the movable portion detent means has a projection formed on the outer peripheral surface of the movable portion;
The fixed portion anti-rotation means has a guide portion that engages with the projection and guides the movement of the movable portion,
The projection and the guide part each have a permanent magnet arranged along the movement direction and a permanent magnet arranged facing the movement direction,
A displacement measuring instrument, wherein the magnetic poles of the permanent magnet on the movable part side and the permanent magnet on the fixed part side facing the permanent magnet on the movable part side are the same. A plurality of permanent magnets divided in the circumferential direction are arranged in the bearing portion provided in the fixed portion, and permanent magnets of the bearing portion are arranged at positions corresponding to the bearing portions on the outer periphery of the movable portion. 2. The displacement measuring instrument according to claim 1, wherein a plurality of circumferentially divided permanent magnets having a number of magnetic poles corresponding to the magnets are arranged. The scale of the movable part is an optical linear scale in which a large number of reflecting parts and transmitting parts are regularly formed in the moving direction. 3. The displacement measuring instrument according to claim 1, further comprising a photodiode for detecting . The displacement measuring instrument according to any one of claims 1 to 3, wherein said guide portion is a groove.

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