JP2003172615A - Position detection means and relative movement apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce expansion and contraction due to change in the temperature of a member to be read (a linear scale) of a linear motor as much as possible. <P>SOLUTION: A position detection means 14 comprises a member 14b (linear scale) to be read that is mounted to one member (frame 7) of the relative movement apparatus via a base 15, and a read head 14a for reading the member 14b to be read that is mounted to the other (carriage 11) of the relative movement apparatus. In the position detection means 14, the member 14b to be read is stuck to the base 15 and at the same time follows expansion and contraction in the relative movement direction of the base 15 due to change in temperature. At the same time, the base 15 is fixed to the relative movement direction at one base point and at the same time the base is slidably mounted to one member at least at one movable point in the relative movement direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting means for a relative moving device and a relative moving device provided with the position detecting means, and more particularly to a permanent magnet type which is designed to relatively move a permanent magnet and a coil. The present invention relates to a linear motor and a linear motor including the position detecting means.

[0002]

2. Description of the Related Art Conventionally, a plurality of permanent magnets and a multi-phase coil provided so as to interlink with the magnetic flux generated by the permanent magnet are provided, and a multi-phase coil is supplied with an electric current to make a multi-phase coil. A linear motor is known in which the phase coil is moved relative to the permanent magnet. As such a linear motor, there are a movable coil type that fixes a permanent magnet and moves a coil, and a movable magnet type that fixes a coil and moves a permanent magnet.

Of such linear motors, approximately 10c
As a means for positioning an object within a stroke range of m to about 100 cm, for example, a moving coil type linear motor as disclosed in Japanese Examined Patent Publication No. 58-49100 and Japanese Utility Model Laid-Open No. 63-93783. Is often used. In this linear motor, a plurality of permanent magnets magnetized in the thickness direction are arranged so as to face each other so that the magnetization directions are different, and a magnetic gap formed between the facing permanent magnets (or between the permanent magnet and the yoke). It has a structure in which a movable coil assembly that moves in the direction perpendicular to the magnetic flux is arranged. Furthermore, in this linear motor, the magnetic flux forms a plurality of closed loops in the magnetic air gap so that the magnetic flux does not concentrate in one part of the magnetic path, so a uniform magnetic flux density is generated over the entire stroke. Can be made.

FIG. 15 shows a schematic sectional view of an example of the above linear motor. In FIG. 15, reference numeral 1 denotes a yoke, which is formed of a ferromagnetic material such as an iron plate into a flat plate shape. Reference numeral 2 denotes a permanent magnet, which is magnetized in the thickness direction and is arranged and fixed in the longitudinal direction of the yoke 1 so that NS magnetic poles mutually appear on the surface. A plurality of permanent magnets 2 arranged in the yoke 1 are arranged via a magnetic gap 3 so that the polarities of different magnetic poles face each other. Reference numeral 4 denotes a support plate, which is fixed to both ends of the yoke 1 in the longitudinal direction in order to secure the magnetic gap 3. The supporting plate 4 is preferably made of the same ferromagnetic material as the yoke 1. The yoke 1, the permanent magnets 2, and the support plate 4 constitute a stator 5.

Next, 6 is a multi-phase coil, which is formed by a plurality of flat coils whose winding directions are orthogonal to the magnetic flux in the magnetic gap 3. That is, a plurality of coils are arranged with some displacement in the arrangement direction of the permanent magnet 2 (however, in FIG. 15, only one coil is shown),
The direction of the magnetic pole is detected through a means such as a magnetic field detecting element, and the coil through which the current flows and the direction of the coil can be switched. The multi-phase coil 6 is fixed to a carriage (not shown) via a coil frame (not shown) to form a mover that is integrally supported by a carriage (not shown). It is provided so as to be movable with respect to the stator 5.

With the above structure, when a current is applied to the polyphase coil 6, the polyphase coil 6 receives thrust in the longitudinal direction of the yoke 1 according to Fleming's left-hand rule, so that the polyphase coil 6 is integrally supported. The mover formed by the movement moves in the longitudinal direction of the yoke 1. Next, when a current in the opposite direction to the above is applied to the polyphase coil 6, a thrust in the direction opposite to the above acts on the polyphase coil 6, so that the mover moves in the opposite direction. Therefore, the mover can be moved to a predetermined position by selecting the energization of the polyphase coil 6 and the direction of the current.

FIG. 16 is an example of a cross-sectional view of a main portion of a more specific linear motor of such a conventional linear motor. With reference to FIG. 16 below, a more specific example of the conventional linear motor will be described. explain. The same parts are designated by the same reference numerals as those in FIG.

In the following, with respect to the direction of the cross-sectional view of the main part of the present specification, the upward direction of the drawing sheet is "up", the downward direction of the drawing sheet is "down", the vertical direction of the drawing sheet is "vertical direction", the drawing sheet surface "Thickness" in the left-right direction,
"Inward / Outward" or "Horizontal", "Outside" on the left side of the drawing
The direction orthogonal to the plane of the drawing will be referred to as the "relative movement direction".

A yoke 1 is fixed to the inner surface of the U-shape of a frame 7 made of an aluminum alloy having a U-shaped cross section. The permanent magnet 2 is fixed to the right surface of the yoke 1 on the left side of the drawing sheet, and the permanent magnet 2 is fixed to the left surface of the yoke 1 on the right side of the drawing sheet as well. Face each other. The permanent magnets 2 are arranged so that the adjacent magnetic poles are different from each other and the polarities of the different magnetic poles face each other. The support sliding member 1 is provided on the upper surface of the frame 7.
The carriage 11 is arranged via 0. Frame 7,
The yoke 1, the center yoke 8 and the permanent magnet 2 form a stator 5.

A multi-phase coil 6 arranged in the magnetic gap 3 is fixed to the carriage 11 via a coil frame 12. The carriage 11, the polyphase coil 6 and the coil frame 12 constitute a mover 13. When a current flows through the multiphase coil 6, thrust is generated in the mover 13 based on Fleming's left-hand rule. The mover 13 is disposed on the stator 5 via the support sliding member 10, and moves in the direction orthogonal to the paper surface of FIG. 16 by the thrust. That is, the stator 5 and the mover 13 can relatively move via the support sliding member 10.

In such a linear motor, the mover 13
An optical or magnetic position detecting means 14 for controlling the position of is provided. The position detecting means 14 is composed of a read head 14a and a read member 14b. When the read head 14a moves relative to the read member 14b, the read member 14b emits a number of pulses proportional to the moving distance. The read head 14a detects the pulse and feeds it back to a control device (not shown), and the control device converts the number of pulses into a distance to detect the moving distance. In FIG. 16, the member to be read 14b is arranged on the side surface of the frame 7, and the read head 14a is opposed to the member to be read 14b on the lower surface of the carriage 11 (via the read head holding member 21 if necessary). An example of such arrangement is shown.

There are the following three methods for the properties of the member to be read 14b or the method of attaching the member to be read 14b to the frame 7. <First Method> Even if a thin and flexible member to be read is fixed to the frame 7 by a means such as adhesion, and the linear expansion coefficient of the member to be read is different from the linear expansion coefficient of the frame 7, the temperature to be described later The member to be read can be expanded and contracted according to the expansion and contraction of the frame 7 due to the change. Hereinafter, in this specification, the expansion and contraction of the member to be read fixed to the member as well as the expansion and contraction of the member will be referred to as "tuning". <Second Method> A read member having a linear expansion coefficient smaller than that of the frame 7 is lightly pressed against the frame 7 by a spring or the like so as to be slidable in the relative movement direction, and even if the frame 7 expands or contracts due to temperature change. The member to be read is allowed to slide with respect to the frame 7 so that the member to be read can expand and contract with a small linear expansion coefficient. <Third Method> A read member having a linear expansion coefficient smaller than that of the frame 7 is not fixed to the frame 7 by adhesion, but a tension spring is used to apply a tension tension to at least one end in the longitudinal direction. It is made movable so that the member to be read can expand and contract with a small linear expansion coefficient.

When the mover 13 moves from the reference position to the target position, the pulse number N1 corresponding to the distance from the reference position to the target position is registered as a position command in the position deviation counter in the controller. As it moves, the pulse number N2 detected by the read head 14a is fed back to the position deviation counter and subtracted from the registered position command pulse number N1. When N1-N2 = 0, it is determined that the mover 13 has moved to the target position, and the mover 13 stops. In this way, the moving distance of the mover 13 is detected by detecting the number of pulses of the position detecting means 14.

Since the frame 7 to which the read member 14b is attached has a linear expansion coefficient, it expands and contracts in the longitudinal direction, that is, in the relative movement direction of the movable element 13 due to temperature change, and in the case of the first method, the read member is read. 14b also expands and contracts in synchronization with the frame 7. The expansion and contraction due to the temperature change occurs due to the temperature change of the operating environment, and also due to the temperature increase due to the heat generation from the multiphase coil 6 accompanying the operation of the linear motor or the temperature decrease due to the heat stop due to the operation stop. In this case, when moving by the number of position command pulses N1, the moving distance becomes large or small due to the expansion and contraction. As a countermeasure, the temperature in the vicinity of the member to be read 14b is detected, and the amount of expansion and contraction due to the temperature change is subtracted and corrected. However, since the temperature distribution may vary depending on the position, the detected temperature value indicates the temperature only at the temperature detection sensor position (that is, the local temperature), and is not necessarily (long in the relative movement direction) the read member 14b or the read target. It may not accurately indicate the temperature of the frame 7 to which the member 14b is attached, and there is a time lag between expansion and contraction due to temperature change and correction by the temperature detection, so the expanded and contracted amount is completely corrected. You cannot do it. For this reason, it has been desired to minimize the expansion and contraction of the read member 14b due to the temperature change.

In the second method or the third method, the member 14b to be read is movable with respect to the frame 7, so that the member to be read can be expanded and contracted with a small linear expansion coefficient. . However, since the member to be read having a small linear expansion coefficient is expensive such as quartz glass, there is a problem that the manufacturing cost of the position detecting means or the relative moving device using the same becomes high.

Further, since such a linear motor is often installed in a narrow place, it is desirable to make it as compact as possible. Since the linear motor also increases in size as the thickness of the read member 14b increases, it has been desired to make the read member 14b as thin as possible.

[0017]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above-mentioned problems of the prior art. The object of the present invention is to reduce the manufacturing cost and the linear expansion coefficient of the member to be read, and (EN) A position detecting means having a small thickness and a relative moving device using the position detecting means, particularly a linear motor.

[0018]

As a result of various studies, the present inventors have completed the present invention by solving the above problems by using the following position detecting means and relative moving device. The invention according to claim 1 comprises a member to be read attached to one member of the relative movement device via a base, and a read head for reading the member to be read attached to the other member of the relative movement device. In the position detecting means, the member to be read is fixed to the base, synchronized with expansion and contraction of the base in the relative movement direction due to temperature change, and the base is fixed to the one member in the relative movement direction at one base point. At the same time, the base is attached to the one member so as to be slidable in the relative movement direction at at least one movable point.

The invention according to claim 2 is the position detecting means according to claim 1, wherein the linear expansion coefficient of the base is 5 μm / m / ° C. or less.

A third aspect of the present invention is the position detecting means according to the first or second aspect, wherein the thickness of the member to be read is 200 μm or less.

According to a fourth aspect of the present invention, the member to be read is an optical reflection type.
The position detecting means described in any one of 1.

According to a fifth aspect of the present invention, the relative movement device is
A plurality of permanent magnets arranged in the yoke via magnetic gaps such that adjacent magnetic poles are different from each other and the polarities of the different magnetic poles are opposite to each other, or the adjacent magnetic poles are different from each other. A plurality of permanent magnets arranged on the opposite side of the permanent magnet with a magnetic gap interposed therebetween, and a coil provided inside the magnetic gap via a supporting sliding member, and a current is passed through the coil. The position detecting means according to any one of claims 1 to 4, wherein the linear motor is configured to move the coil relative to the permanent magnet in the longitudinal direction.

The invention according to claim 6 is the position detecting means according to claim 5, wherein the linear motor is a moving coil type.

According to a seventh aspect of the present invention, the member to be read of the position detecting means including the member to be read and a reading head for reading the member to be read is attached to one member of the relative moving device via a base, In the relative movement device in which the read head is attached to the other member of the relative movement device,
The member to be read is fixed to the base, is synchronized with expansion and contraction of the base due to temperature change, and the base is fixed to the one member in a relative movement direction at one base point, and the one member is provided with the above-mentioned member. In the relative movement device, the base is slidably attached at at least one movable point in the relative movement direction.

The invention according to claim 8 is the relative moving apparatus according to claim 7, wherein the linear expansion coefficient of the base is 5 μm / m / ° C. or less.

A ninth aspect of the present invention is the relative moving device according to the seventh or eighth aspect, wherein the thickness of the member to be read is 200 μm or less.

An invention according to claim 10 is the relative moving device according to any one of claims 7 to 9, wherein the member to be read is an optical reflection type.

According to an eleventh aspect of the present invention, in the relative movement device, a plurality of yokes are arranged in the yoke via a magnetic gap so that adjacent magnetic poles are different from each other and polarities of the different magnetic poles are opposite to each other. A permanent magnet, or an opposing yoke arranged via a magnetic gap in a plurality of permanent magnets arranged in the yoke so that adjacent magnetic poles are different from each other, and a supporting sliding member in the magnetic gap. 11. A linear motor comprising a coil provided through the coil, wherein the coil is moved in the longitudinal direction relative to the permanent magnet by passing a current through the coil.
The relative movement device according to any one of 1.

In the present invention, it is desirable that the mechanical strength of the member to be read is made smaller than that of the base so that the member to be read fixed to the base can synchronize with the difference in expansion and contraction due to temperature change. In the present invention, the thickness of the member to be read is preferably 500 μm or less.
If the thickness of the member to be read exceeds 500 μm, it becomes difficult to synchronize with expansion and contraction due to temperature change of the base. The more preferable thickness of the member to be read is 350 μm or less,
An even more preferable thickness is 200 μm or less. In the present invention, the thickness of the base is preferably 2 mm or more and 4 mm or less. If the thickness of the base is less than 2 mm, the mechanical strength will be insufficient and it will be difficult to fix it to one member of the relative movement device at a base point or a movable point described later. If the thickness of the base exceeds 4 mm, the material cost of the base becomes expensive and the linear motor becomes large, which is not preferable. A more preferable thickness of the base is 2.5 mm or more, and 3.
5 mm or less, and an even more preferable thickness is 2.8 mm
The above is 3.2 mm or less. In the present invention, it is desirable that the base has a small linear expansion coefficient of 5 μm.
/ M / ° C or less is preferable. When the linear expansion coefficient of the base is larger than 5 μm / m / ° C., it becomes difficult to subtract the amount of expansion and contraction due to the temperature change to correct it. A more preferable linear expansion coefficient of the base is 4 μm / m / ° C. or less, and an even more preferable linear expansion coefficient is 3.5 μm / m / ° C.
It is the following.

Since the linear expansion coefficient of the read member is different from that of the base, the expansion and contraction of the two will differ due to temperature change unless they are fixed, but as described above, the thin member has a mechanical strength smaller than that of the base. Is fixed to the base, the expansion and contraction of the member to be read synchronizes with the base even if expansion and contraction due to temperature change occur. Since the base is fixed to one member of the relative movement device in the relative movement direction at the base point, there is no displacement between the one member of the relative movement device and the base at the base point, and the base is attached to one member of the relative movement device. Since the movable member is mounted slidably in the relative movement direction, the movable member can expand and contract with a small linear expansion coefficient of the member to be read.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1> FIG. 1 is a sectional view of a main part showing a linear motor according to Embodiment 1 of the present invention, and FIG. 2 is an enlarged view of the vicinity of the position detecting means 14 of FIG. 1, and the clamping block 1 shown in FIG.
7, base point fixing material 18, movable point fixing material 19 and bolt 2
0 is omitted in FIG. FIG. 3 is a view taken along the line AA of FIG. 2 and (a) shows the frame 7 and the base pin 16.
a and the movable point pin 16b, (b) shows the read member 14b, (c) shows the base 15, (d) shows the base point fixing member 18 and the movable point fixing member 19, and (e) shows. The clamp block 17 is shown, and (a) to (e) are shown with their positions in the relative movement direction (left and right direction on the paper surface of the drawing) aligned. The same parts are designated by the same reference numerals as those in FIG. 15 or FIG. The linear motor of this embodiment is shown in FIG.
The conventional linear motor shown in FIG. 6 is the same as the conventional linear motor shown in FIG. 16 except that the mounting method of the member to be read 14b is changed by adding the base 15 and the like. In the present embodiment, the coil is a movable coil type having a mover, but the present invention is not limited to this, and the permanent magnet may be a movable magnet type having a mover. In this embodiment, the magnetic gap 3 is formed so that the permanent magnets face each other.
The present invention is not limited to this, and the permanent magnet and the facing yoke may be formed to face each other. Further, there is no permanent magnet or opposing yoke opposed to each other via the magnetic gap 3, and the coil is linked to the magnetic flux generated by a plurality of permanent magnets arranged in the relative movement direction so that adjacent magnetic poles are different from each other. It may be done.

The position detecting means 14 includes a frame 7 which is one member of the relative moving device and a base 15 which is a low thermal expansion material.
To-be-read member 14b disposed in the vertical direction via the (ie, the detection surface of the position detection means is disposed in the vertical direction)
And a reading head 14a disposed on the carriage 11 which is the other member of the relative moving device so as to face the member to be read 14b. The detection surface of the position detection means is horizontal (that is, horizontal) in an environment where dust or the like is present.
Since dust and the like tend to accumulate on the upward surface in the horizontal direction when it is arranged in the vertical direction, it is arranged in the vertical direction in the present embodiment. They may be arranged in the (that is, horizontal) direction. The read member 14b is adhered to the base 15 over substantially the entire surface.
The fixing means for fixing the member to be read 14b to the base 15 is not limited to the above-mentioned adhesion, and various means such as fusing the member to be read 14b to the base 15 may be used. As the member to be read 14b, for example, a magnetic (or optical) linear scale is used, and the read head 1
As 4a, for example, a magnetic (or optical) reading head is used, but the present invention is not limited to this, and an optimum one may be used. In order to make the thickness dimension of the position detecting means 14 (dimension in the horizontal direction of the paper surface of FIG. 1) as small as possible, in the present embodiment, an optical reflection type or a magnetic linear scale is used instead of the optical transmission type.

A base point pin 16a is projected at one position (hereinafter referred to as "base point") of the frame 7 which serves as a reference for positioning in the relative movement direction, and at least one position away from the base point in the relative movement direction. The movable point pin 16b is provided at the position (hereinafter, referred to as "movable point"). Base pin 1
The base hole 15a is provided at the position of the base 15 corresponding to 6a. In the present embodiment, the base point is located at the center in the relative movement direction and the read member 14b is attached to the base point. Therefore, the base point hole 15a does not penetrate the side on which the read member 14b is attached and does not interfere with the attachment. The base pin 16a
Is to be smaller than the depth of the base hole 15a which is the non-through hole. Base point hole 1
The diameter of 5a is set so that the base pin 16a can be inserted into the base hole 15a without any gap. The movable point hole 15b is provided at the position of the base 15 corresponding to the movable point pin 16b. In the present embodiment, the two movable points are located at both ends in the relative movement direction and do not overlap the member to be read 14b, so the movable point holes 15 are provided.
b may be penetrating or non-penetrating, and in the case of non-penetrating, the dimension of the movable point pin 16b protruding from the frame 7 is smaller than the depth of the movable point hole 15b which is the non-through hole. The movable point hole 15b is an elongated hole, and the dimension in the direction orthogonal to the relative movement direction is such that the movable point pin 16b can be inserted without a gap, and the dimension in the relative movement direction is the movable point pin 16b.
The diameter is set to be larger than the diameter of b so that the difference in contraction in the relative movement direction due to expansion and contraction described later can be absorbed. In this embodiment, the diameter of the base point pin 16a and the diameter of the movable point pin 16b are the same, but may be different. In the present embodiment, the number of movable points is two, but the number of movable points is not limited to three, and three or more movable points are provided, and accordingly, the movable point holes 15b, the movable point pins 16b, the clamp block 17, the movable point fixing material 19, and the bolts 20. May be increased.

When expansion and contraction due to temperature change occurs, since the base point pin 16a is inserted into the base point hole 15a at the base point with substantially no clearance, there is no difference in contraction of the base 15 with respect to the frame 7 in the relative movement direction, and at the movable point. Since the linear expansion coefficient of the base 15 which is a low thermal expansion material is smaller than the linear expansion coefficient of the frame 7, the difference in contraction of the movable point hole 15b with respect to the base point hole 15a in the relative movement direction is different from that of the movable point pin 16b with respect to the base point pin 16a. Although it is smaller, the base is slidably attached to the frame 7 by using the movable point hole 15b as an elongated hole as described above, so that the difference in contraction can be absorbed. Further, since the member to be read 14b adhered to the base 15 is thin as described above, the member to be read 14b can be synchronized with expansion and contraction of the base 15 due to temperature change.

Next, the fixing of the base 15 positioned on the frame 7 as described above will be described. The base point fixing member 18 and the movable point fixing member 19 are leaf springs, and the clamping block 17 is a plate having substantially the same thickness as the base 15.
The clamp block 17 is arranged on the outside of the frame 7 by aligning the position of the bolt through hole 17a of the clamp block 17 with the screw hole 7a of the lower frame 7 of the base pin 16a or 16b. Align the position of the through hole 18b with the bolt through hole 18b of the clamp block 17, arrange the base point fixing material 18 outside the clamp block 17, and insert the bolt 20 through the bolt through hole 18b of the base point fixing material 18. , Clamp block 17
Through the bolt hole 17a, the base point pin 16a is screwed into the screw hole 7a on the lower side, and the base point fixing material 18 and the clamp block 17 are screwed to the frame 7. The clamp block 17 is for aligning the positions of the substantially fixed base point fixing member 18 and the movable point fixing member 19 in the inner and outer directions with the outer side of the base 15, and is a separate component from the frame 7 in the present embodiment. However, a convex portion may be provided on the frame 7 to be integrated with the frame 7.

The base point fixing member 18 and the movable point fixing member 19 are clamped by the bolt 20 as described above.
Is pressed by the frame 7 via the
The bases 8a and 19a press the base 15 by the spring force, and the spring force of the base fixing material 18 is set to a strength capable of fixing the base 15 to the frame 7 at the base. Base 1 at the moving point
If the pressing force of 5 on the frame 7 is too large, the base 15 cannot slide on the frame 7 due to the difference in the contraction in the relative movement direction due to the expansion and contraction described above. The strength is such that the sliding is possible. When the base 15 can be fixed to the frame 7 with the same spring force as that of the movable point fixing member 19, the base fixing member 18 and the movable point fixing member 19 may be the same. The base 15 is fixed to the frame 7 with bolts without using the base fixing material 18.
May be fixed at the base point, or the base 15 may be bonded to the frame 7 at the base point.

<Embodiment 2> FIG. 4 is a sectional view of a main part showing a linear motor according to Embodiment 2 of the present invention, and FIG. 5 is an enlarged view of the vicinity of the position detecting means 214 of FIG. 4, and the clamp shown in FIG. Block 17, base point fixing material 18, movable point fixing material 19
The bolt 20 and the bolt 20 are not shown in FIG. The same parts are designated by the same reference numerals as those in FIGS. The present embodiment is the same as the first embodiment except that the position detecting means 14 is changed in the linear motor of the first embodiment. Here, when the magnetic force on the outside of the member to be read 214b is detected by the read head 214a like a magnetic linear scale, the magnetic force on the outside of the member to be read 214b moves away from the outer surface of the member to be read 214b (that is, the read head 214a and Read target member 2
Since the position detecting means void 214c of 14b becomes weaker as it expands, it is desirable to make the position detecting means void 214c as narrow as possible. In that case, the tip portion 18a or 1
9a is thicker than the member to be read 214b and the tip portion 18a
Is located in the gap between the read head 214a and the base 15, even if the position detecting means gap 214c is narrowed, it cannot be narrowed due to the thick tip portion 18a or 19a. As in the embodiment, the lower end of the base 215 is located below the lower end of the read head 214a so that the tip portion 18a or 1
9a is prevented from being positioned in the gap between the read head 214a and the base 215, so that the position detecting means gap 214 is formed.
c can be narrowed.

<Third Embodiment> FIG. 6 is a sectional view of a main part of a linear motor according to a third embodiment of the present invention. FIG. 7 is an enlarged view of the vicinity of the position detecting means 14 shown in FIG. 6. The clamp shown in FIG. The block 17, the base point fixing member 18, the movable point fixing member 19 and the bolt 20 are not shown in FIG.
FIG. 8 is a view on arrow AA of FIG. 7, (a) is a frame 7,
The base point pin 16a and the movable point pin 16b are shown, (b)
Shows the member to be read 14b, (c) shows the base 315, (d) shows the base point fixing member 18 and the movable point fixing member 19, (e) shows the clamp block 17, and (a).
(E) shows the positions in the relative movement direction (left and right direction on the paper surface of the drawing) in alignment with each other. The same parts are shown in FIGS.
The same reference numerals as 15 and 16 are attached. The present embodiment is the same as the first embodiment except that the bolts 20 are screwed into the screw holes 37a of the frame 37 by changing the base point and the movable point in the linear motor of the first embodiment.

In this embodiment, since the base point is located at one end in the relative movement direction and the member to be read 14b is attached to the base point, the base point hole 315a is non-penetrating on the side to which the member to be read 14b is attached. Make sure there is no problem in pasting,
The dimension of the base point pin 16a protruding from the frame 7 is smaller than the depth of the base point hole 315a which is the non-through hole. Even if the base point pin 16a is shifted from the base point to the left side of the paper surface of FIG. 8 so that it does not overlap the read member 14b, the shift distance is generally much smaller than the maximum moving distance of the mover 13, so the base at the time of expansion and contraction. Since the movable point of 315 is almost the same as that when the base pin 16a is not displaced from the base point, the base pin 16a is displaced from the base point to the left side of the drawing of FIG. 8 so that it does not overlap the read member 14b and penetrates the base hole 315a. It may be a hole. In the present embodiment, the number of movable points is one, but the number of movable points is not limited to this, and the number of movable points may be two or more.
6b, the clamp block 17, the movable point fixing member 19 and the bolt 20 may be increased.

<Fourth Embodiment> FIG. 9 is a cross-sectional view showing a main part of a linear motor according to a fourth embodiment of the present invention, and FIG. 10 is an enlarged view of the vicinity of the position detecting means 14 of FIG. 9, and the clamp shown in FIG. The block 417, the base point fixing member 418, the movable point fixing member 419, and the bolt 20 are omitted in FIG. 9. FIG. 11 is a view taken along the line AA of FIG. 9, and (a) is a frame 47, a base point pin 16a, and a movable point pin 16b.
(B) shows the member to be read 14b, (c) shows the base 15, (d) shows the base point fixing member 418 and the movable point fixing member 419, and (e) shows the clamping block 4.
17 shows (a) to (e) in which the positions in the relative movement direction (the left-right direction on the paper surface of the drawing) are aligned. The same parts are designated by the same reference numerals as those in FIGS. 1 to 8, 15 and 16. The present embodiment is the same as the first embodiment except that the base point fixing member 18 and the movable point fixing member 19 are changed in the linear motor of the first embodiment, and the clamp block 17 and the frame 7 are also changed accordingly. is there.

In this embodiment, the dimension of the base point fixing member 418 and the movable point fixing member 419 in the relative movement direction is increased, and the bolt passing hole 18b of the base point fixing member 18 and the bolt passing hole 19b of the movable point fixing member 19 are formed. The number of base fixing materials 41
8 and the movable point fixing member 419, each having two pieces, and accordingly the clamping block 417 also has a larger dimension in the relative movement direction, and the number of bolt passing holes 417a per one piece of the clamping block 417 is also two. The number of screw holes 47a of the frame 47 is set to two per one of the clamp blocks 417 which come into contact with each other. Base point fixing material 41
In order to increase the fixing force of the base point fixing member 418, the front end portion 418a of No. 8 is provided over the entire length of the base point fixing member 418 in the relative movement direction. Movable point fixing material 4
In order to enable the base 415 to slide with respect to the frame 7 due to the difference in contraction in the relative movement direction due to expansion and contraction, the tip end portion 419a is made smaller than the total length of the base fixing member 419 in the relative movement direction. In the present embodiment, the intermediate portion in the relative movement direction is not provided with the tip portion 419a, and the tip portions 4 are provided at both ends.
Although 19a is provided, the tip portion 419a may be provided in the middle portion and both end portions may not have the tip portion 419a. Alternatively, the movable point fixing member 419 and the clamp block 417 may have a small size in the relative movement direction as in the first embodiment, and the side yoke 49 may be the same as in the first embodiment. Alternatively, the movable point fixing member 419 may have the same shape as the base point fixing member 418, and the spring force may be weaker than that of the base point fixing member 418.

<Example> Next, an example of the present invention will be described below with reference to FIGS. 12 is shown in FIG.
(B) and (c) are shown with dimensions, showing the member to be read 14b and the base 15 of this embodiment, and the same parts are assigned the same reference numerals as in FIG. In this example, the position detection means and the like in the linear motor of the fourth embodiment have the following specifications. The member to be read 14b: optical reflection type linear scale (RGS-S scale manufactured by Renishaw Co.) ... thickness 200 μm, length 800 mm. The main material of the structure is iron, and the scale surface is a laminated structure of nickel, copper, and gold. The score line pitch is 20 μm. Reading head 14a: Optical reflection type read head (RGH24 made by Renishaw) Base 15: Low thermal expansion material (Invar made by Hitachi Metals) ... Linear expansion coefficient 3 μm / m / ° C., thickness 3
mm, length 890 mm. 150 mm from the base point 15a in the left-right direction on the paper surface of FIG.
To the measurement points 14ba and 14bb, and fix the base point fixing member 4
18, the pressing force of the movable point fixing member 419 is 60 N, 15
When the temperature of the base 15 is raised to N and the distance from the base point 15a to the measurement points 14ba and 14bb is measured by the laser length measuring machine, the results are shown by solid lines in FIGS. In addition, the distance value is 0 at the base point 15a,
The side "ba" has a minus sign, and the side having the measurement point 14ba has a plus sign. When the linear expansion coefficient is calculated by the formula of (distance change) / (temperature change) / 150 mm, the measurement point 14ba side is 2.13 μm / m / ° C. from FIG. 13 and the measurement point 14bb side is 2.40 μm / from FIG. m / ° C., which was an extremely small value as compared with Comparative Examples described later. In addition, the member to be read 14b of the present embodiment is the same as the conventional technique
Method, which is less expensive than an expensive member to be read such as quartz glass having a small linear expansion coefficient.
Since the low thermal expansion material is thin, the cost can be reduced, so that the position detecting means 14 can be reduced in price compared to the conventional case.

<Comparative Example> In the linear motor of the embodiment, the base 15 is removed, and the member 14b to be read is directly adhered to the frame 7 to raise the temperature of the frame 7 in the same manner as in the embodiment, from the base point 15a to the measuring point 14ba. , 14bb are measured by a laser length measuring machine, and the results are shown by broken lines in FIGS. The linear expansion coefficient is (distance change) / (temperature change) /
When calculated by the formula of 150 mm, measurement point 1 is obtained from FIG.
21.16 μm / m / ° C. on the 4ba side, and 21.74 μm / m / ° C. on the measurement point 14bb side from FIG.

Although the embodiment or the example of the present invention has been described above, the present invention is not limited to the above-described embodiment or example, and various forms can be made without departing from the spirit of the present invention. Needless to say, it is possible to improve and change the design.

[0045]

According to the present invention, there is provided a position detecting means which has a low manufacturing cost, a small linear expansion coefficient of a member to be read and a thin thickness, and a relative moving device using the position detecting means, particularly a linear motor. be able to.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a first embodiment of the present invention.

2 is an enlarged view of the vicinity of the position detection means 14 of FIG.

FIG. 3 is a view taken along the line AA of FIG.

FIG. 4 is a cross-sectional view of essential parts of a second embodiment of the present invention.

5 is an enlarged view of the vicinity of the position detecting means 214 in FIG.

FIG. 6 is a cross-sectional view of the essential parts of Embodiment 3 of the present invention.

7 is an enlarged view of the vicinity of the position detecting means 14 of FIG.

8 is a view on arrow AA in FIG. 7. FIG.

FIG. 9 is a cross-sectional view of the essential parts of Embodiment 4 of the present invention.

10 is an enlarged view of the vicinity of the position detecting means 14 of FIG.

11 is a view on arrow AA of FIG.

FIG. 12 is a read member 14b and a base 15 of the embodiment.
FIG.

FIG. 13 is a diagram showing the results of measuring the distance from the base point 15a to the measurement point 14ba by raising the temperature of the base 15 in Examples and Comparative Examples.

FIG. 14 is a drawing showing the results of measuring the distance from the base point 15a to the measurement point 14bb by raising the temperature of the base 15 in Examples and Comparative Examples.

FIG. 15 is a view showing a conventional linear motor.

FIG. 16 is a view showing a conventional linear motor.

[Explanation of symbols]

1 yoke 2 permanent magnet 3 magnetic gap 5 stator 6 multi-phase coil 7, 37, 47 frame 7a, 37a, 47a screw hole 8 center yoke 10 support sliding member 11 carriage 12 coil frame 13 mover 14, 214 position detecting means 14a, 214a Read head 14b, 214b Read member 14ba, 14bb Measuring point 15, 315 Base 15a, 315a Base point hole 15b, 315b Movable point hole 16a Base point pin 16b Movable point pin 17, 417 Clamping block 17a, 18b, 19b, 417a 418b and 419
b Bolt through hole 18 Base point fixing material 18a, 19a, 418a, 419a Tip portion 19, 419 Movable point fixing material 20 Bolt 21 Read head holding material 214c Position detecting means void

Continued front page    F term (reference) 2F069 AA02 BB40 DD27 EE02 EE26                       GG04 GG06 GG07 GG11 HH14                       MM04 MM07 MM11                 5H540 BA03 BA06 BB02 BB06 BB08                       EE01 EE05 FA13 FA14 FC07                 5H611 AA01 BB09 PP05 QQ03 RR06                       UA01 UA07 UB00                 5H641 BB06 BB18 GG03 GG07 GG12                       GG26 GG28 GG29 HH02 HH05                       HH06 JA02

Claims (11)

[Claims] 1. A position provided with a read member attached to one member of a relative moving device via a base, and a read head for reading the read member attached to the other member of the relative moving device. In the detection means, the member to be read is fixed to the base and is synchronized with expansion and contraction of the base in the relative movement direction due to temperature change, and the base is fixed to the one member in the relative movement direction at one base point and at least Position detecting means, which is attached so as to be slidable in a relative movement direction at one movable point. 2. The linear expansion coefficient of the base is 5 μm / m /
The position detecting means according to claim 1, wherein the temperature is not higher than ° C. 3. The position detecting means according to claim 1, wherein the thickness of the member to be read is 500 μm or less. 4. The position detecting means according to claim 1, wherein the member to be read is an optical reflection type. 5. The relative movement device includes a plurality of permanent magnets and a multiphase coil provided so as to interlink with a magnetic flux generated by the permanent magnet, and a current is passed through the multiphase coil. The position detecting means according to any one of claims 1 to 4, wherein the linear motor is a linear motor configured to move the polyphase coil relative to the permanent magnet. 6. The position detecting means according to claim 5, wherein the linear motor is a moving coil type. 7. The read member of the position detecting means having a read member and a read head for reading the read member is attached to one member of a relative movement device via a base, and the read head is provided with the read head. In a relative movement device attached to the other member of the relative movement device, the member to be read is fixed to the base and synchronized with expansion and contraction of the base due to temperature change, and the base is relative to the one member at one base point. A relative movement device fixed in the movement direction and slidable in the relative movement direction at at least one movable point. 8. The linear expansion coefficient of the base is 5 μm / m /
The relative movement device according to claim 7, wherein the relative movement device has a temperature of not more than ° C. 9. The relative moving device according to claim 7, wherein the thickness of the member to be read is 500 μm or less. 10. The relative movement device according to claim 7, wherein the member to be read is an optical reflection type. 11. The relative movement device includes a plurality of permanent magnets and a polyphase coil provided so as to interlink with a magnetic flux generated by the permanent magnet, and a current is passed through the polyphase coil. The relative movement device according to any one of claims 7 to 10, wherein the linear motor is a linear motor configured to move the polyphase coil relative to the permanent magnet.