JPH0850515A - Positioning device - Google Patents

Abstract

PURPOSE:To enable exact positioning control by extending the range, in which the magnetic field intensity in the direction perpendicular to the routes of the relative movement of two members is practically linearly changed, at the positioning device for controlling the relative positions of two members. CONSTITUTION:The device is provided with a magnetic field generating means 3 equipped with a part, where the magnetic field intensity leaving to the direction of a weak polar value is practically linearly changed, for generating the magnetic field distribution of inverse polarities for which the absolute polar values of magnetic field intensity perpendicular to the route of relative movement are different, magnetic field coil 6 arranged in the magnetic field and undergoes the force with interaction with a magnetic field by electrification, and magnetism detecting means 7 arranged at the center of a part where the magnetic field intensity is linearly changed and corresponding to a target position signal and the output signal of the magnetism detecting means 7, feedback control means 8 and 9 controls a voltage to be impressed to the magnetic field coil 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device for controlling the relative positions of two members.

[0002]

2. Description of the Related Art A conventional positioning device is disclosed in Japanese Patent Laid-Open No. 59-88.
As described in Japanese Patent No. 602, it is composed of a permanent magnet, a field coil, and a magnetic sensor. In this positioning device, the adjacent magnetizing strengths are equal,
The magnetic field distribution generated by the magnetic field generating means composed of a pair of permanent magnets of opposite polarities has an absolute value in which the magnetic flux density Φ changes substantially linearly in the direction perpendicular to the path of relative movement of the two members. As shown in Fig. 2, the distribution is symmetrical to the left and right around the junction of a pair of permanent magnets. The linear portion of this magnetic field distribution is detected by a magnetic sensor as a position signal, and the voltage applied to the field coil is controlled. To perform positioning control.

[0003]

However, in the above-mentioned conventional example, a pair of permanent magnets of opposite polarities are disposed in contact with each other, and the magnetic flux density in the direction perpendicular to the relative movement path of the two members is substantially reduced. However, there is a problem that the range of linear change is extremely narrow.

Therefore, by arranging the pair of permanent magnets slightly apart from each other, a wider linear range than that of FIG. 14 can be obtained as shown in FIG. As shown in FIG. 17, the phenomenon that the gradient of the magnetic flux density in the central portion becomes small occurs, and the distribution diagram of the magnetic force lines at this time is flat in a wide range in the central portion of the magnetic field generating means as shown in FIG. There was a problem.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the first invention of the present application is to provide a direction perpendicular to a relative movement path of two members. To widen the range in which the magnetic field strength changes substantially linearly to enable accurate positioning control.

A second object of the present invention is to use a pair of permanent magnets having different magnetization strengths to widen the range in which the magnetic field strength in the direction perpendicular to the relative movement path of the two members changes linearly. To reduce parts and assembly costs.

A third object of the present invention is to make the air gap in a magnetic circuit formed by a pair of permanent magnets and a yoke different from each other, and to provide a magnetic field strength perpendicular to the relative movement path of the two members. To widen the range of linear change to reduce the influence of the external magnetic field.

An object of a fourth invention according to the present application is to make the size of the pair of permanent magnets different so as to widen the range in which the magnetic field strength in the direction perpendicular to the relative movement path of the two members changes linearly. To reduce parts and assembly costs.

The fifth object of the present invention is to widen the range in which the magnetic field strength in the direction perpendicular to the relative movement path of the two members is linearly changed by the pair of permanent magnets and yokes having different magnetizing strengths. Then, the influence of the magnetic field from the outside is reduced.

A sixth object of the present invention is to set a range in which a magnetic field strength in a direction perpendicular to a relative movement path of two members is linearly changed by a pair of permanent magnets having different sizes and a yoke. Wider to reduce parts and assembly costs and reduce the effects of external magnetic fields.

[0011]

In order to achieve the above object, the first invention of the present application is supported by a first member and a supporting means so as to be movable relative to the first member. A second member and a part of the first member, which generate a magnetic field distribution of opposite polarity in which absolute values of extreme values of magnetic field strength in a direction perpendicular to a relative movement path are different, A magnetic field generating means having a portion where the magnetic field strength deviated in the direction of weak extremum changes substantially linearly, and a part of the second member, which is arranged in the magnetic field generated by the magnetic field generating means. A field coil that receives a force due to the interaction with the magnetic field due to energization,
A magnetic detecting means which is arranged at the center of a portion where the magnetic field strength changes linearly and is fixed to the second member and which outputs the magnetic field strength as an electric signal; a target position signal and the magnetic detecting means. By providing the feedback control means for controlling the voltage applied to the field coil according to the output signal, the absolute value of the magnetic field extreme value is biased toward the smaller one with respect to the center of the space of the two-pole permanent magnet. It is possible to secure a wide range in which the magnetic field strength changes substantially linearly,
More accurate positioning control is possible within a wider range.

According to a second aspect of the present invention, the magnetic field generating means is composed of a pair of permanent magnets, which are magnetized in directions opposite to each other in a direction perpendicular to a relative movement path arranged with a space therebetween. Since the magnetizing strength of the magnet is weaker than that of the other magnet to generate the magnetic field distribution, the cost of parts and assembly can be reduced.

According to a third invention of the present application, the magnetic field generating means is a pair of permanent magnets which are magnetized with the same strength in directions opposite to each other in a direction perpendicular to a relative movement path arranged with a space. And a ferromagnetic yoke which forms a closed magnetic circuit through the magnetic field lines generated by the permanent magnet, and one of the voids in the magnetic circuit is made wider than the other to generate the magnetic field distribution. Therefore, the magnetic field from the outside (disturbance)
Can be reduced.

According to a fourth invention of the present application, the magnetic field generating means is a pair of permanent magnets magnetized with the same strength in directions opposite to each other in a direction perpendicular to a relative movement path arranged with a space. Since the permanent magnet on one side is made smaller than that on the other side to generate the magnetic field distribution, the cost of parts and assembly can be reduced.

According to a fifth aspect of the present invention, the magnetic field generating means is arranged with a space in between, and a pair of permanent magnets magnetized in directions opposite to each other in a direction perpendicular to the relative movement path,
The magnetic field distribution is generated by a ferromagnetic yoke that forms a closed magnetic circuit through the lines of magnetic force generated by the permanent magnet, and the magnetizing strength of the permanent magnet on one side is weaker than that of the other permanent magnet. As a result, the influence of the magnetic field from the outside can be reduced.

According to a sixth aspect of the present invention, the magnetic field generating means is arranged with a space therebetween, and is a pair of permanent magnets magnetized at the same strength in directions opposite to each other in a direction perpendicular to the path of relative movement. Through a magnet and a magnetic field generated by the permanent magnet, a ferromagnetic yoke that forms a closed magnetic circuit is formed, and the permanent magnet on one side is made smaller than the other to generate the magnetic field distribution. With the configuration in which the parts and the assembly cost are reduced, the influence of the external magnetic field can be reduced.

[0017]

【Example】

First Embodiment FIG. 1 is a drawing of a first embodiment that best represents the features of the present invention. In the drawing, 1 is a first member and 2 is a direction of arrow B with respect to the first member. The second member 3 supported by a support means (not shown) so as to be relatively movable is a pair of permanent magnets 3b, 3c magnetized in a direction perpendicular to the arrow B direction.
The permanent magnet portion is composed of the two permanent magnets 3b and 3c, and has an opening 3a at the center of the contact surface.

Reference numeral 4 denotes a ferromagnetic yoke which forms a closed magnetic circuit by passing magnetic lines of force from the permanent magnet section 3, and 5 is arranged with a space from the permanent magnet section 3 to form a void in the magnetic circuit. It is a magnetic yoke, and the permanent magnet part 3, the yokes 4, 5 are
Are fixed to the first member 1.

[0019]

[Outside 1] Reference numeral 7 denotes a Hall element that is arranged in the field coil 6 and that serves as a magnetic field strength sensor that utilizes the Hall effect that detects the magnetic field strength generated by the permanent magnet unit 3. It is possible to obtain a voltage output proportional to the magnetic field strength. .

Reference numeral 8 is a signal processing circuit for processing the voltage output of the Hall element 7 to obtain a position signal, and 9 is an amplifier circuit for amplifying the difference output between the target position signal and the position signal and applying it to the field coil 6. Feedback control means is constituted by both circuits, and relative positioning of the two members 1 and 2 is possible based on the target position signal.

FIG. 2 shows the planar arrangement of the initial positions of the field coil 6, the permanent magnet section 3, and the Hall element 7 with the yoke 5 removed. FIG. 3 shows a planar arrangement of the permanent magnet portion 3 and the Hall element 7. The permanent magnet portion 3 has a symmetrical magnetizing pattern, and the magnetizing strength of the permanent magnet 3b is weaker than that of the permanent magnet 3c. ing. The Hall element 7 is fixed to the second member 2 with its initial position displaced from the center of the permanent magnet section 3 toward the side of the permanent magnet 3b which is weakly magnetized.

FIG. 4 shows the magnetic flux density in the direction perpendicular to the direction of arrow B, which is the path of relative movement of the first member 1 and the second member 2 in the gap in the magnetic circuit formed by the permanent magnet portion 3 and the yoke 5. In the distribution, the horizontal axis represents the amount of displacement and the vertical axis represents the magnetic flux density (magnetic field strength). Permanent magnet 3 with weak magnetization strength as shown
The absolute value b of the extreme value of the magnetic field strength on the b side is smaller than the absolute value a ′ of the extreme value of the magnetic field strength on the permanent magnet 3b side, which has a strong magnetization strength, and is substantially within the range S indicated by the two-dot chain line. The magnetic field strength changes linearly, and the Hall element 7 is provided at the center position (dashed line position) of this range S.

FIG. 5 shows a signal processing circuit for the hall element 7. The operational amplifier 10 includes resistors 10a, 10b and 10c.
A constant current is supplied to the Hall element 7 in combination with. The output signal of the hall element 7 is the operational amplifier 11 and the resistor 11
It is differentially amplified by a, 11b, 11c and 11d.
The resistor 11e is a variable resistor. By changing the resistance value of the variable resistor 11e, it is possible to change the voltage at the output end of the operational amplifier 11 with respect to the magnetic field strength. By adjusting the output of the Hall element 7 provided at the alternate long and short dash line position shown in FIG. 4 so as to be equal to the reference voltage Vc, the first member 1 and the second member 2 centered at the alternate long and short dash line position. Positive and negative voltage outputs centered on the reference voltage Vc are obtained for the relative position of.

The operational amplifier 12 is combined with the resistors 12a and 12b to invert and amplify the output of the operational amplifier 11 around the reference voltage Vc and change the resistance value of the variable resistor 12b, thereby changing the output voltage with respect to the change in the magnetic field strength. The ratio of is variable.

In this embodiment, since the magnetic flux generated by the pair of permanent magnets 3b and 3c is closed via the two yokes 4 and 5, the magnetic field from the outside (disturbance) is less likely to be affected and stable. Positioning control is possible.

Second Embodiment FIG. 6 is a diagram showing a second embodiment of the present invention, in which 21 is a first member and 22 is a direction of arrow B with respect to the first member 21. A second member 23 supported by a supporting means (not shown) so as to be relatively movable is a pair of permanent magnets 23b, 2b magnetized to have two poles in a direction perpendicular to the arrow B direction.
The permanent magnet portion 3c has a magnetizing strength lower than that of the permanent magnet 23c.

[0027]

[Outside 2] The present embodiment is different from the first embodiment in that the yoke that closes the magnetic flux of the permanent magnet is eliminated, but a magnetic field strength distribution similar to that of the first embodiment is obtained, and positioning is performed by a similar control circuit. It can be controlled. Further, in this embodiment, since the yoke for closing the magnetic circuit is omitted, parts and assembling costs can be reduced.

Third Embodiment FIG. 7 is a diagram showing a third embodiment of the present invention, in which the magnetization patterns of the pair of permanent magnets 33b and 33c constituting the permanent magnet section 33 are changed. As shown in FIG. 8, the permanent magnets 33b and 33c are magnetized with the initial position of the Hall element 7 shown by the alternate long and short dash line in FIG. 4 as a boundary, and as shown in FIG. The shape is symmetrical with respect to the initial position. However, the shape of the permanent magnet portion 33 in the cross section of the Hall element 7 that moves relatively is the same as in the first and second embodiments, and the same positioning control as in each embodiment is possible. In this embodiment, the field coil can be downsized, which is advantageous in saving space.

Fourth Embodiment FIG. 9 is a diagram showing a fourth embodiment of the present invention, in which 41 is a first member and 42 is a direction of arrow B with respect to the first member 41. The second member 43 is supported by a supporting means (not shown) so as to be relatively movable, and 43 is a permanent magnet portion composed of a pair of permanent magnets 43b and 43c magnetized in the direction perpendicular to the arrow B direction with the same magnetic field strength. And has an opening 43a at the center of the contact surface of both permanent magnets 43b and 43c. Reference numeral 44 is a ferromagnetic yoke that forms a closed magnetic circuit through the lines of magnetic force generated by the permanent magnets 43b and 43c. 45 is a ferromagnetic material that is arranged with a space from the permanent magnet portion 43 and forms a gap in the magnetic circuit. The permanent magnet part 43 and the yokes 44 and 45 are fixed to the first member 41.

[0030]

[Outside 3] The yoke 45 has a stepped shape, and the gap in the magnetic circuit formed with the permanent magnet portion 43 is wider on the left side than on the right side. When this gap is widened, the magnetic resistance increases and it becomes difficult for the magnetic flux to pass through. As a result, the absolute value of the extreme value of the magnetic flux density in the direction perpendicular to the relative movement path indicated by arrow B is rightward on the left side in FIG. Smaller,
The magnetic field strength distribution shown in FIG. 4 is obtained.

Fifth Embodiment FIG. 10 shows a fifth embodiment of the present invention. In FIG. 10, 51 is a first member and 52 is a first member 51 in the direction of arrow B. The second member 53 is movably supported by a non-supporting member, and 53 is a pair of permanent magnets 53 magnetized in the direction perpendicular to the arrow B with the same magnetic field strength.
b, 53c, which is a permanent magnet part,
An opening 53a is provided at the center of the contact surface of b and 53c. 5
Reference numeral 4 denotes a yoke having ferromagnetism that forms a closed magnetic path of the magnetic lines of force generated by the permanent magnet portion 53, and 55 is arranged with a space from the permanent magnet portion 53 to provide ferromagnetism for forming an air gap in the magnetic circuit. It is a yoke which has the above-mentioned permanent magnet part 53 and yoke 5.
4, 55 are fixed to the first member 51.

[0032]

[Outside 4] Reference numeral 57 is a Hall element, which outputs a voltage corresponding to the magnetic field strength. As shown in FIG. 10, in the permanent magnet 53, the permanent magnet on the left side of the opening 53a is smaller than that on the right side, and the absolute value of the extreme value of the magnetic flux density in the direction perpendicular to the relative movement path indicated by arrow B is shown. The value is smaller on the left side than on the right side, and the magnetic field intensity distribution as shown in FIG. 4 is obtained.
In this embodiment, the positioning control can be performed by the same control circuit as in the first embodiment.

Sixth Embodiment FIG. 11 is a view showing a sixth embodiment of the present invention, in which 61 is a first member and 62 is a direction of arrow B with respect to the first member 61. A second member 63 supported by a support member (not shown) so as to be relatively movable is a permanent magnet portion composed of a pair of permanent magnets 63b and 63c magnetized in the direction perpendicular to the arrow B direction with the same magnetic field strength. There is an opening 63a at the center of the contact surface between the two permanent magnets 63b and 63c, and the permanent magnet 63b on the left side of the opening 63a is smaller than the right permanent magnet 63c.

[0034]

[Outside 5] The present embodiment has a configuration in which a yoke for closing the magnetic flux of the permanent magnet portion 63 is eliminated, but a magnetic field strength distribution similar to that of the fifth embodiment can be obtained, and positioning control can be performed by a similar control circuit.

In each of the above embodiments, the linear movement of the first member and the second member which move relative to each other has been described, but as shown in FIG. 12, the first member 71,
The second member 72, the permanent magnet 73, the yokes 74 and 75, the field coil 76 and the like are arcs or permanent magnets 81 which also serve as the first member as shown in FIG. 13, a second member 82,
The same applies to the case where the constituent members such as the field coil 83 and the yoke 84 are circular and the relative movement path is an arc. In this case, the intensity of the magnetic field detected by the Hall elements 77, 85 is a magnetic field component perpendicular to the relative movement path, that is, in the radial direction from the center of rotation. The same applies when the permanent magnets, yokes, field coils, and the like have a planar configuration and the relative motion of the first member and the second member is rotation, but can be regarded as a substantially straight line.

It is needless to say that the present invention is not limited to the configurations of the above-mentioned embodiments, and may have any configuration as long as the functions shown in the claims can be achieved.

[0037]

As described above, the first aspect of the present application
According to the invention, the magnetic field distribution generated by the pair of permanent magnets is configured such that one of the absolute values of the extreme values of the magnetic field strength in the direction perpendicular to the relative movement path of the two members is smaller than the other. Therefore, it becomes possible to secure a wide range in which the absolute value of the magnetic field extreme value is biased toward the smaller center of the space of the pair of permanent magnets and the magnetic field strength changes substantially linearly. Allows more accurate positioning control.

According to the second invention of the present application, since the pair of permanent magnets have different magnetizing strengths, the cost of parts and assembly can be reduced, and the magnetic field strength is substantially linear with a simple structure. It is possible to secure a wide range of dynamic changes.

According to the third invention of the present application, since the air gap in the magnetic circuit formed by the pair of permanent magnets and the yoke is made different, it is affected by the external magnetic field (disturbance). Without doing so, a wide range in which the magnetic field strength changes substantially linearly can be secured, and stable positioning control is possible.

According to the fourth invention of the present application, since the size of the pair of permanent magnets is different, the magnetic field strength is substantially linear with a simple structure in which the parts and assembling costs are reduced. It is possible to secure a wide range of dynamic changes.

According to the fifth invention of the present application, a pair of permanent magnets having different magnetizing strengths and a yoke are used, so that the magnetic field strength is substantially not affected by the external magnetic field. It is possible to secure a wide range that changes linearly.

According to the sixth invention of the present application, a pair of permanent magnets of different sizes and yokes are used, so that the magnetic field from the outside can be reduced with a simple structure that reduces the cost of parts and assembly. It is possible to secure a wide range in which the magnetic field strength changes substantially linearly without being affected by.

[Brief description of drawings]

FIG. 1 is a sectional view and a control block diagram illustrating a positioning device according to a first embodiment of the present invention.

FIG. 2 is a plan view illustrating a positioning device according to a first embodiment of the present invention.

FIG. 3 is a plan view with the field coil removed in FIG.

FIG. 4 is a magnetic field strength distribution diagram of a plan view with the field coil removed in FIG.

FIG. 5 is a signal processing circuit diagram of the Hall element in a plan view with the field coil removed in FIG.

FIG. 6 is a sectional view illustrating a positioning device according to a second embodiment of the present invention.

FIG. 7 is a plan view illustrating a positioning device according to a third embodiment of the present invention.

8 is a plan view of FIG. 7 with the field coil removed.

FIG. 9 is a sectional view illustrating a positioning device according to a fourth embodiment of the present invention.

FIG. 10 is a sectional view illustrating a positioning device according to a fifth embodiment of the present invention.

FIG. 11 is a sectional view illustrating a positioning device according to a sixth embodiment of the present invention.

FIG. 12 is a sectional view illustrating a positioning device according to another embodiment of the present invention.

FIG. 13 is a sectional view illustrating a positioning device according to another embodiment of the present invention.

FIG. 14 is a magnetic field strength distribution diagram for explaining a conventional example.

FIG. 15 is a magnetic field strength distribution diagram for explaining a conventional example.

FIG. 16 is a magnetic field strength distribution diagram for explaining a conventional example.

FIG. 17 is a magnetic flux distribution diagram of a pair of permanent magnets.

[Explanation of symbols]

 1 1st member 2 2nd member 3 permanent magnet part (magnetic field generation means) 3b permanent magnet 3c permanent magnet 4 yoke (yoke) 5 yoke (yoke) 6 field coil 7 hall element (magnetic detection means) 8 Signal processing circuit (fieldback control means) 9 Amplifier circuit (fieldback control means)

Claims (6)

[Claims] 1. A first member, a second member supported by a support means so as to be relatively movable with respect to the first member, and a part of the first member. A magnetic field distribution of opposite polarity in which the absolute value of the extreme value of the magnetic field strength in the direction perpendicular to the path is different is generated, and the portion where the magnetic field strength biased in the direction of weaker extreme value changes substantially linearly And a field coil that is a part of the second member and that is disposed in the magnetic field generated by the magnetic field generating means and that receives a force due to interaction with the magnetic field due to energization, and an initial position The magnetic detection means, which is disposed substantially in the center of the portion where the magnetic field strength changes linearly, is fixed to the second member and outputs the magnetic field strength as an electric signal, and the target position signal and the output of the magnetic detection means. A feed bar that controls the voltage applied to the field coil according to a signal. A positioning device comprising: a lock control means. 2. The magnetic field generating means according to claim 1, wherein the magnetic field generating means is composed of a pair of permanent magnets which are magnetized in directions opposite to each other in a direction perpendicular to a path of relative movement arranged with a space therebetween. A positioning device characterized in that the magnetizing strength is made weaker than the other to generate the magnetic field distribution. 3. The pair of permanent magnets according to claim 1, wherein the magnetic field generating means is a pair of permanent magnets, which are magnetized at the same strength in directions opposite to each other in a direction perpendicular to a path of relative movement, which are arranged with a space therebetween. It is made of a ferromagnetic yoke that forms a closed magnetic circuit through the magnetic field lines generated by a permanent magnet, and one of the voids in the magnetic circuit is made wider than the other to generate the magnetic field distribution. Positioning device. 4. The magnetic field generating means according to claim 1, comprising a pair of permanent magnets, which are magnetized with the same strength in directions opposite to each other in a direction perpendicular to a path of relative movement arranged with a space therebetween, A positioning device characterized in that a permanent magnet on one side is made smaller than the other to generate the magnetic field distribution. 5. The pair of permanent magnets according to claim 1, wherein the magnetic field generating means is arranged with a space therebetween and is magnetized in directions opposite to each other in a direction perpendicular to a relative movement path. Through a magnetic field line generated by a magnetic yoke to form a closed magnetic circuit, and the magnetizing strength of the permanent magnet on one side is weaker than that on the other side to generate the magnetic field distribution. Positioning device. 6. A pair of permanent magnets according to claim 1, wherein the magnetic field generating means is arranged with a space between them, and is magnetized in the directions opposite to each other in the direction perpendicular to the path of relative movement and with the same strength. Positioning characterized by comprising a ferromagnetic yoke that forms a closed magnetic circuit through the lines of magnetic force generated by the permanent magnet, and one of the permanent magnets is made smaller than the other to generate the magnetic field distribution. apparatus.