JP6938130B2 - Anti-rotation of optical measuring instrument - Google Patents

Description

The present invention relates to a measuring instrument having an optical linear encoder, and relates to a detent that is 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 Patent Document 1. In this publication, in order to obtain a highly reliable and compact linear encoder that can realize a compact actuator, a striped pattern with high reflectance and low reflectance is applied to a flat portion formed at the end of a movable shaft by photolithography. The formed tape-shaped scale portion is attached. Permanent magnets are attached to a plurality of permanent magnets at positions different from the flat portion of the shaft in the circumferential direction, and stators having a three-phase coil are arranged outside the permanent magnets. At a position corresponding to the scale portion of the stator, an optical sensor having a plurality of layers facing the scale portion is arranged. In order to prevent the scale portion from rotating in 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 stator end.

Patent Document 2 discloses a contact type displacement measuring instrument. In this publication, a slide bearing is used for 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 a contact. A coil unit that constitutes a differential transformer is incorporated in the outer cylinder that surrounds the probe at a position corresponding to the core. Further, Patent Document 3 discloses a configuration for preventing rotation of a reciprocating movable member in a reciprocating device used for sucking parts in a semiconductor manufacturing apparatus or the like.

Japanese Unexamined Patent Publication No. 2008-215911 (particularly, paragraph 0021). Japanese Unexamined Patent Publication No. 2012-185019 Japanese Unexamined Patent Publication No. 2008-82512

A small contact sensor that measures displacement by bringing the probe into contact with the object to be measured is used in many applications. Among them, the so-called pencil-type optical measuring instrument has a high degree of freedom in mounting because it is small, and has excellent weather resistance and environmental resistance, so that it can be used as a measuring tool such as an actuator. In Patent Document 1, it is realized as an actuator having an optical linear encoder.

In an optical linear encoder, especially in the case of a pencil type, the sensor generally has a probe formed in a columnar shape because of the ease of mounting the sensor. On the other hand, since the light from the light source is transmitted or reflected on the scale surface and reaches the light receiving portion, it is desirable that the scale surface of the sensor is flat in order to keep the detection intensity constant.

Therefore, in Patent Document 1, a cylindrical probe is detected as a scale surface by flattening a cylindrical surface to form a flat surface and forming a columnar probe that is rotatably formed in the stator without contacting the stator in order to reduce sliding resistance as much as possible. The rotation is regulated by a rectangular hole provided on the stator side so that the part can always maintain the same relationship.

As a result, there is a minute gap between the rectangular hole and the surface drop shape of the scale surface due to insertion and axial movement of the probe, and there is a risk of wear due to mutual contact and friction due to sliding resistance. be.

Although the one described in Patent Document 2 describes a miniaturized linear encoder, since it is an actuating transformer type and not an optical type, the probe can be rotated, so that the scale surface and detection in the optical sensor can be detected. It is not always necessary to maintain the relative relationship of the parts. In the case described in Patent Document 2, in order to maintain the environmental resistance of the linear encoder, a bellows is used to prevent foreign substances such as oil from entering from an external pollution source.

Foreign matter must be avoided because it causes deterioration of the detection part, but if a bellows is used, the internal air will act as a damper as the probe moves, which will contribute to sliding resistance. A method for sealing and rotating a probe with reduced sliding resistance is desired.

Further, in Patent Document 3, a movable magnet and a fixed magnet are arranged so as to face each other along the reciprocating direction of the reciprocating movable member, a return force of the reciprocating movement is generated, and the circumferential movement of the movable member is regulated. .. However, also in the device described in this publication, the detent of the movable member is to physically regulate the rotation by changing the shape of the slide bearing provided at the end of the main body case to a shape different from the circular shape, and the movable member and the bearing. It is not considered that the bearings are worn due to stick slip because they come into contact with each other to prevent rotation.

The present invention has been made in view of the above-mentioned defects of the prior art or matters not considered in the prior art, and an object of the present invention is a small pencil-type optical displacement having a measurement probe basically held in a sleeve in a non-contact manner. In the measuring instrument, the purpose is to suppress the occurrence of friction and wear between the measuring probe and the fixing member including the sleeve due to the reciprocating movement of the measuring probe while always keeping the positional relationship between the measuring probe and the sleeve in the circumferential direction constant. .. Another object of the present invention is, in addition to the above object, to simplify the configuration of a small pencil-type optical displacement measuring instrument to eliminate or reduce the damper action of the air inside the measuring instrument due to the reciprocating movement of the probe. ..

A feature of the present invention that achieves the above object is a rod-shaped movable portion in which a stylus that contacts an object to be measured is arranged on one end side and a scale is arranged on the other end side, and an anti-meterer of the movable portion. Displacement measuring instrument including a cylindrical member for accommodating a side, having a bearing portion for supporting an intermediate portion of the movable portion on one end side, and having a fixed portion having a detection portion disposed opposite to the scale. A movable portion detenting means for preventing the movable portion from rotating around the longitudinal axis thereof with respect to the fixed portion is provided in the movable portion, and a fixed portion detenting means is provided in the fixed portion. Both the movable portion detenting means and the fixed portion detenting means include a magnet means.

In this feature, the movable portion detenting means has an oval or rectangular protrusion provided on the scale side of the bearing portion and a permanent magnet on the peripheral surface of the protrusion and arranged in the longitudinal direction. The fixing portion detenting means has an oval or rectangular groove formed according to the movement range of the protrusion in the longitudinal direction and a permanent magnet arranged on the inner peripheral surface of the groove in the longitudinal direction. It is preferable that the magnetic poles of the permanent magnet on the movable portion side and the permanent magnet on the fixed portion side facing the permanent magnet on the movable portion side are the same pole, and the permanent magnet on the fixed portion side is in the longitudinal direction of the groove. A plurality of magnets are arranged on the inner surface at intervals, 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 on a bearing portion provided on one end side of the fixed portion, and is located on the outer periphery of the movable portion and at a position corresponding to the bearing portion. A plurality of permanent magnets divided in the circumferential direction having a number of magnetic poles corresponding to the permanent magnets of the bearing portion may be arranged, and the scale of the movable portion is such that the reflecting portion and the transmitting portion are regulated in the longitudinal direction. The optical linear scale is formed in large numbers, and the detection unit of the fixed portion may include a photodiode that detects the reflected light or the transmitted light of the light projected on the scale. In addition, a spring is arranged between the detent of the movable portion and the detection portion of the fixing portion, and both end faces of the detent on the longitudinal direction side of the oval or rectangular shape and the oval or rectangular shape of the fixing portion. Permanent magnets may be arranged on both inner end faces in the longitudinal direction of the groove, and the magnetic poles of the facing permanent magnets may be the same pole.

According to the present invention, since the detent for preventing the circumferential displacement of the probe is composed of a permanent magnet, in the optical displacement measuring instrument, the measuring probe is arranged in the detection unit and the measuring unit facing the measuring probe. Since it is possible to maintain a non-contact state with respect to the sleeve containing the measuring probe, it is possible to suppress the occurrence of friction and wear between the measuring probe and the fixing member. In addition, parts such as bellows and springs that have been used in the past can be omitted, the configuration of the displacement measuring instrument is simplified, the compression of air inside the measuring instrument is reduced, and the damper action by the air inside the measuring instrument. Is eliminated or reduced.

It is a figure which shows one Example of the pencil type displacement measuring instrument which concerns on this invention, FIG. It is a perspective view of the movable part side (the figure (a)) and the stationary side (the figure (b)) of the displacement measuring instrument shown in FIG. It is a figure of the rotation stop part of the displacement measuring instrument shown in FIG. 1, FIG. 1A is a top view, and FIG. 1B is a cross-sectional view taken along the line BB of FIG. 1A. It is a figure explaining pitching and rolling in the displacement measuring instrument shown in FIG. It is a figure of another Example of the rotation stop part of the displacement measuring instrument which concerns on this invention, and is the figure corresponding to FIG.

Hereinafter, an embodiment of the small pencil type displacement measuring instrument 100 according to the present invention will be described with reference to the drawings. The small pencil-type displacement measuring instrument 100 is an encoding-type high-precision contact-type digital length measuring machine that employs an optical scale, and is suitable for adjacent multipoint measurement and can accurately perform measurement of various shapes. .. Further, by providing the bellows boot 14 on the stylus 10 side, waterproofness and environmental resistance can be improved, and resistance to general coolant and oil can be provided.

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

In FIG. 1B, the movable portion 20 has a substantially hemispherical contactor 12 that abuts on an object to be measured (not shown) and a stylus 10 that holds the contactor on one end side. A round bar-shaped shaft portion 30 is attached to the counter-contact side of the stylus 10. On the counter-measurer side of the shaft portion 30, there is a detent 80, which is a characteristic configuration of the present invention, the details of which will be described later.

A stepped shaft portion 32 is formed in the movable portion 20, and a detent 80 extending in the axial direction and projecting from the stepped shaft portion 32 to the outer diameter side is provided at one place in the circumferential direction thereof. A holding portion 34 having a diameter smaller than that of the stepped shaft portion 32 is formed on the counter side of the stepped shaft portion 32 in order to wind the coil spring 38 described later. As shown in FIG. 2A, the holding portion 34 has a cylindrical shape (solid shaft shape) from the stepped shaft portion 32 side to the axial intermediate portion, but the holding portion 34 has a cylindrical shape (solid shaft shape) from the intermediate portion to the other shaft end. A cut-off portion 35 having a semicircular cross section cut on a horizontal plane is formed.

On the shaft end side of the cut-off portion 35, a scale mounting portion 36 cut in a horizontal plane from a semicircular shape by the thickness of the optical scale 76 is further formed. That is, when the optical scale 76 is attached to the scale mounting portion 36 using an adhesive or the like, the cutting depth thereof is such that the upper surface of the scale 76 substantially coincides with the upper surface of the cut-off portion 35 and becomes a circular two-divided surface. Is being adjusted.

The optical scale 76 is known as a linear scale. Reflective portions are formed on a transparent substrate such as glass at equal intervals in the longitudinal direction by etching or the like, and the ground portion of the substrate is used as a transmissive portion. There is. The widths of the transmitting portion and the reflecting portion are substantially the same, and the pitch formed by the pair of the transmitting portion and the reflecting portion is, for example, 20 μm. That is, the widths of the transmitting portion and the reflecting portion are each approximately 10 μm.

Reference numeral 40 denotes a bearing (also referred to as a bearing portion) that supports the movement of the movable portion in the left-right direction (X direction) in FIG. 1B with low friction and low contamination, and includes an oil-impregnated bearing and a non-contact type bearing. It is adopted. In one embodiment of the bearing (bearing portion) 40, the bearing 40 has a magnetic bearing composed of a permanent magnet divided into a plurality of pieces in the circumferential direction and alternately arranged with S poles and N poles, and faces the bearing 40. On the outer periphery of the shaft portion 30 of the movable portion 20, the same number of permanent magnets having the same magnetic poles 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 greater than the length of the bearing 40 plus the displacement of the movable portion 20 in the X direction. ..

The bellows boot 14 is airtightly attached between the tip side of the fixed portion 62 (left side in FIG. 1B) and the anticontact end face of the stylus 10, and the movable portion 20 moves with respect to the fixed portion 62. However, external dust such as oil and coolant contained in the surrounding environment of the displacement measuring instrument 100 is prevented from entering the inside of the fixing 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 anti-bellows boot side (on the right side in FIG. 1B) of the fixed portion 62 from the bearing 40, the connection side to the bearing 40 is cylindrical in order to form the outer diameter of the displacement measuring instrument 100 in a substantially cylindrical shape. A case 42 formed in a shape and having many notches, and a thin-walled cylindrical cover 60 along the outer periphery of the cover guide portion 44 of the case 42 are provided. The cover 60 covers almost the entire longitudinal direction of the case 42. At the opposite end on the side where the cover 60 fits into the case 42, a terminal portion 90 to which the signal line 92 and the electric wire 94 extending to the electronic component of the displacement measuring instrument 100 are connected is arranged, and the terminal portion 90 and the terminal portion 90 are arranged. The cover 60 is airtightened by a mechanical sealing means such as an O-ring or a method such as bonding. A cable connected to the controller that controls the displacement measuring device 100 is connected to the terminal unit 90, but the illustration is omitted.

FIG. 2B shows a fixing portion 62 from which the cover 60 and the bearing 40 have been removed. The case 42 and its surroundings will be further described with reference to FIG. 2 (b). The case 42 is formed so as to have a plurality of notches having a complicated shape by wire electric discharge machining or the like. That is, the substantially left half portion of FIG. 2B is formed in a hollow cylindrical shape up to the spring contact portion 45, and has a shape that accepts the movable portion 20. An oval groove 50 is formed on the upper surface, and the detent 80 of the movable portion 20 is a detent groove that can move in the longitudinal direction. A groove edge magnet 82 is attached to the peripheral edge of the groove 50 by adhesion or the like. The detent 80 of the movable portion 20 and the groove edge magnet 82 form the detent portion 84.

A hole 48 is also formed on the lower side and is used for adjustment and the like. The spring contact portion 45 is a wall formed only in the upper half, and holds the coil spring 38 between the spring contact portion 45 and the wall surface of the stepped shaft portion 32 of the movable portion 20. The coil spring 38 is for returning the stylus 10 to the left in the X direction after using the displacement measuring instrument 100. 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 trapezoidal shape on the right side of the spring contact portion 45, and a light receiving portion 72 forming an optical encoder is formed with the substrate receiving portion 56 formed at the end of the anti-bearing portion of the fixed portion 62. The mounted electronic board 70 is mounted. Therefore, both substrate receiving portions 52 and 56 form the same plane, and the substrate receiving portions 56 at the ends are truncated cylinders slightly larger than a semicircle. The electronic board 70 has a light receiving portion 72 and a circuit element 74 mounted on the lower surface thereof and is mounted on the substrate receiving portions 52 and 56, and one end side thereof is a screw hole 52a formed in the substrate receiving portion 52 and a mounting hole formed in the electronic substrate 70. It is fixed with a set screw 78 using 70a. Similarly, the other end side is fixed with the set screw 78 by using the screw hole 56a formed in the substrate receiving portion 56 and the mounting hole 70b formed in the electronic substrate 70. The light receiving unit 72 has a light receiving element such as a photodiode, and the light receiving element detects the reflected light or the transmitted light of the light projected on the reflecting unit and the transmitting unit constituting the linear scale.

With the electronic substrate 70 fixed to the substrate receiving portions 52 and 56, the distance between the lower surface of the light receiving portion 72 and the upper surface of the optical scale 76 attached to the movable portion 20 is an appropriate distance for optical measurement. , The horizontal plane 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 substrate 70 in the fixed portion 62, a semicircular notch portion 59 is formed in the fixed portion, and further, the semicircular notch portion is formed. A notch 58 is formed in the lower portion of the 59 so as to extend in the longitudinal direction for convenience of assembly and the like. As described above, a plurality of signal lines 92 and electric power wires 94 are attached to the electronic board 70 from a terminal portion (not shown) (only one of each is described for convenience in FIG. 1 (b)).

The details of the detent portion 84 of the displacement measuring instrument 100 configured in this way will be described with reference to FIGS. 3 and 4. FIG. 3A is a circumferential development view of the detent portion 84, is a view corresponding to FIG. 1A, and FIG. 3B is a cross-sectional view taken along the line BB of FIG. 3A. FIG. 4 is a diagram for explaining the relative displacement between the movable portion 20 and the fixed portion 62, FIG. 4A is a diagram for explaining the yaw motion and the roll motion, and FIG. 4B is a diagram for explaining the yaw motion and the roll motion, and FIG. The figure which shows the relative displacement of a part 62, FIG.

An oval groove 50 (a part thereof is shown in FIG. 3A) is formed in the longitudinal direction over the cover guide portion 44 and the spring holding portion 46 of the fixing portion 62. On the inner peripheral surface of the groove 50, a permanent magnet (N pole) 822 is laminated on the innermost side and a permanent magnet (S pole) 821 is laminated on the outermost side 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 oval pillar, and a high-rigidity metal fixed shaft 806 with a rectangular cross section is arranged in the center, and a permanent magnet (S pole) 802 and a permanent magnet (N) are arranged around the fixed shaft 806 on the long side in order. Pole) 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 laminated in this 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. The material of each of the above magnets is preferably a material capable of generating a high magnetic force, and for example, neodymium, samarium cobalt, or ferrite magnet, which are rare earth magnets, are used.

Since the magnetic poles of the groove edge magnet 82 composed of the magnets 821 and 822 and arranged on the inner circumference of the groove 50 and the magnets 801 to 804 arranged on the detent 80 are configured in this way, the groove edge magnet 82 can be used. The provided fixed portion 62 and the detent 80 always generate repulsive forces that repel each other, and when the movable portion 20 moves in the longitudinal direction, it rotates (rolls) around its longitudinal axis. Even if a force is applied, a restoring force is generated by the interaction of the magnets 822 and 801 of the detent portion 84, and the position in the rotation direction is kept constant. Therefore, it is possible to prevent the detent 80 from coming into contact with the fixed portion 62, and to prevent the occurrence of contamination due to the movement of the movable portion 20. Further, since the detent 80 is oval and the magnets 801 and 802 also have a predetermined length in the longitudinal direction, displacement (yaw movement) around a certain point of the movable portion 20 can be prevented. Further, 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 stylus 10 is released from the object to be measured after the measurement is completed, the movable portion 20 returns to the initial position due to the restoring force of the coil spring 38, but at that time, the magnet 804 provided on the short side portion of the detent 80 The interaction between the magnet 822 and the magnet 822 on the inner surface of the groove 50 buffers the restoration operation and avoids contact with the arc portion at the end of the groove 50, and in this case as well, the occurrence of contamination can be prevented.

Further, a magnetic spring is generated by the interaction of the magnets 804 and 822, and it is possible to mitigate the influence of the change in the absolute displacement amount of the movable portion 20 at the time of measurement and to apply a substantially constant contact stress to the object to be measured. And the measurement accuracy is improved. Further, the magnetic spring makes it possible to make the contact stress substantially constant even during measurement in an environment without gravity or a vacuum environment without air. Furthermore, due to the airtightness of the bellows boots 14 and the case 54, when the movable part 20 is displaced, the internal air acts as an air spring, which becomes a resistance at the time of measurement. Now the movable portion 20 can be moved in the longitudinal direction (X direction).

As a result of suppressing the roll motion by the interaction between the magnet 822 of the groove 50 and the magnet 801 of the detent, as shown in FIG. 4B, the position of the optical scale 76 attached to the movable portion 20 for some reason is shown by the broken line. Even if it changes to 76a, the position is immediately restored, and the gap between the optical scale 76 and the light receiving unit 72 is returned to the proper gap d, enabling 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 the position 76b as shown in FIG. 4C, the position of the optical scale 76 is due to the above-mentioned interaction of the magnets. Is immediately restored, and the relative positions of the optical scale 76 and the light receiving unit 72 are kept constant.

FIG. 5 shows a modified example of the detent portion 84 according to the present invention. This modification differs from the above embodiment in that the permanent magnets attached to the inner peripheral surface of the groove 50 formed in the fixed portion 62 have a divided shape, the divided magnets are arranged at predetermined intervals, and between the adjacent magnets. The coil magnet is placed in. The magnet in the arc portion of the groove 50 is not divided and has the same configuration as that of the embodiment shown in FIG.

Specifically, the split magnets 822 and 821 having a predetermined length in the longitudinal direction are laminated on the inner surface of the longitudinal portion of the groove 50 and arranged by adhesion or the like, and the coil magnet 825 is placed 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. The coil 812 is connected to an electronic substrate 70 by an electric wire (not shown). By controlling the current applied to the end of the coil 812, the generated magnetic force is changed. In that case, by controlling the magnitude and flow direction of the applied current for each coil 812, the strength and direction of the magnetic force generated by the coil 812 can be changed according to the longitudinal position of the movable portion 20, and the stylus 10 can be changed. The moving speed of the movable portion 20 can be changed according to the measurement position, and a constant or changing optimum longitudinal moving speed of the movable portion 20 can be obtained. Further, by controlling the direction and direction of the applied current, the measured pressure (pressing pressure) on 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 that measures by contact, permanent magnets are arranged in both the detent of the movable part and the groove of the fixed part. It is possible to avoid contact between the fixed part and the fixed part as much as possible, and it is possible to prevent the occurrence of contamination inside the displacement measuring instrument. Further, even if contamination should occur, if it is a magnetic metal powder, it can be attracted to the magnet, and it is possible to prevent adverse effects of deterioration of measurement accuracy due to contamination on the optical displacement measuring unit. Further, since the magnet restores the relative yaw motion and roll motion of the movable portion with respect to the fixed portion, the relative posture of the optical scale and the light receiving portion can be kept constant.

10 ... Stylus, 12 ... Contact, 14 ... Bellows boot, 20 ... Movable part, 30 ... Shaft, 32 ... Stepped shaft, 32a ... Spring contact surface, 34 ... Holding part, 34a ... Spring winding surface , 35 ... cut-off part, 36 ... scale mounting part, 38 ... coil spring, 40 ... bearing (part), 42 ... case, 43 ... case end, 44 ... cover guide part, 45 ... spring contact part, 46 ... spring Holding part, 48 ... hole, 50 ... (for detent) groove, 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 ... (after roll displacement) scale, 76b ... Scale (after yaw displacement), 78 ... Set screw, 80 ... Anti-rotation, 82 ... Groove edge magnet, 84 ... Anti-rotation part, 90 ... Terminal part, 92 ... Signal line, 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 portion having a stylus in contact with an object to be measured on one end side and a scale on the other end side, and a cylindrical member accommodating the counter-measurer side of the movable portion are included. In a displacement measuring instrument having a bearing portion that supports a movable portion on one end side and a fixed portion having a detection portion arranged so as to face the scale.
The movable portion detent means for preventing the movable portion from rotating around the longitudinal axis with respect to the fixed portion is provided in the movable portion, and the fixed portion detent means is provided in the fixed portion, respectively, and the movable portion is provided. Both the detent means and the fixed portion detent means include a magnet means.
The movable portion detenting means has an oval or rectangular protrusion provided on the scale side of the bearing portion and a permanent magnet which is a peripheral surface of the protrusion and is arranged in the longitudinal direction, and the fixed portion. The detent means has an oval or rectangular groove formed according to the movement range of the protrusion in the longitudinal direction and a permanent magnet arranged on the inner peripheral surface of the groove in the longitudinal direction, and is permanent on the movable portion side. The magnetic poles of the magnet and the permanent magnet on the fixed portion side facing the movable portion side permanent magnet are set to the same pole.
A plurality of permanent magnets on the fixed portion side are arranged at intervals on the inner surface in the longitudinal direction of the groove, and a coil magnet is arranged between the permanent magnets at intervals . .. A plurality of permanent magnets divided and formed in the circumferential direction are arranged on the bearing portion provided on one end side of the fixed portion, and the bearing portion is located on the outer periphery of the movable portion and at a position corresponding to the bearing portion. The displacement measuring instrument according to claim 1, wherein a plurality of permanent magnets divided in the circumferential direction having a number of magnetic poles corresponding to the permanent magnets of the above are arranged. The scale of the movable portion is an optical linear scale in which a large number of reflecting portions and transmitting portions are regularly formed in the longitudinal direction, and the detecting portion of the fixed portion is the reflected light or transmitted light of the light projected on the scale. The displacement measuring instrument according to claim 1 or 2 , further comprising a photodiode for detecting light. A spring is arranged between the detent of the movable portion and the detection portion of the fixing portion, and both end faces of the detent on the longitudinal side of the oval or rectangular shape and the oval or rectangular shape of the fixing portion. The displacement measuring instrument according to any one of claims 1 to 3 , wherein permanent magnets are arranged on both inner end faces in the longitudinal direction of the groove, and the magnetic poles of the facing permanent magnets are made the same pole.

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