JP5248963B2 - Position detection device - Google Patents

Description

  The present invention relates to detection of an absolute position of a movable member driven by a linear drive device.

In Patent Document 1, (a) a stator having a long shape including a plurality of magnets, and (b) a mover provided with a coil so as to be relatively movable in the longitudinal direction of the stator with respect to the stator. And (c) an absolute position detection device that detects an absolute position, which is a relative position of the mover to the stator, is described.
In the stator, each of the plurality of magnets has different axial lengths (both ends are N-pole and S-pole), and the length monotonously increases or decreases in the axial direction. Are arranged in series. The mover is provided with a plurality of magnetic field detectors spaced apart in the axial direction.
When the mover is moved relative to the stator, the output signals of the plurality of magnetic field detectors change in accordance with the magnetic poles of the magnets opposed to the magnetic field detectors. , And the wavelength monotonously increases or decreases with relative movement. Therefore, based on the output signals of the plurality of magnetic field detectors, the absolute position, which is the relative position of the mover to the stator in the axial direction, can be detected.
In Patent Document 2, (a) a pair of long-shaped fixing members each having a plurality of magnets, and (b) a pair of fixing members are disposed so as to be relatively movable in the longitudinal direction of the fixing members. And a movable member having a pair of magnetic field detectors facing the fixed member, and detecting an absolute position that is a relative position of the movable member to the fixed member based on output signals of the magnetic field detectors An apparatus is described. In each of the pair of fixed members, the plurality of magnets are arranged such that when the movable member is relatively moved between the pair of fixed members, the frequency of the output signal of the magnetic field detection unit facing the one fixed member and the other fixed The frequency of the output signal of the magnetic field detection part facing the member is arranged in a state different by one. For example, if one fixing member has N magnets with N poles and S poles at both ends in the axial direction for the entire stroke, N ± 1 magnets are arranged on the other fixing member. Established. In addition, in the case where a total of 2N magnets having N poles and S poles are alternately arranged on one fixed member so as to face the movable member, the other fixed member has a total (2N ± 2) are arranged. On the other hand, the movable member is provided with two magnetic field detectors facing each of the pair of fixed members, each at a position shifted by ¼ phase in the axial direction. When the movable member is relatively moved, one of the two magnetic field detectors facing one fixed member outputs a sin (mθ) signal, the other outputs a cos (mθ) signal, and the other The two magnetic field detectors facing the fixed member output sin {(m ± 1) θ} and cos {(m ± 1) θ} signals. The four output signals are combined to obtain a tan θ signal, and the absolute position is detected based on the tan θ signal and the like.
JP-A 61-292502 JP 2002-310606 A

An object of the present invention is to improve the position detection device.
The position detection device according to claim 1 includes: (i) a plurality of magnets and a longitudinal member extending in the axial direction; and (ii) a plurality of magnetic field detection units, relative to the longitudinal member and the axial direction. and a movable detecting member, said plurality of based on the output signal of the magnetic field detector, a position detecting device for detecting a relative position of the axial relative to the longitudinal member of the detecting member, said longitudinal member The magnetic field detectors are provided at least one at a position facing each of the pair of longitudinal members, and each of the plurality of magnets has a length in the axial direction. In each of the longitudinal members, when it is assumed that the longitudinal member and the detection member are moved relative to each other at equal intervals along the axial direction, along with the relative movement, The axial direction between each magnetic field detector The distance in the direction orthogonal to the phase is a state where the phases are different from each other but change at the same wavelength, and the composite signal of the output signals of the plurality of magnetic field detectors changes in a one-to-one correspondence with the relative position. It is assumed that it is arranged in a state where
In this position detection device, when the stator and the mover are relatively moved by the linear drive device, the relative position between the stator and the mover is detected as an absolute position. Here, the absolute position is not a relative position defined by a distance from the previous stop position but an absolute position defined by a distance from a predetermined reference position.
The drive source of the linear drive device may be a linear motor or a rotary motor. The linear drive device may include a rotary motor and a motion conversion mechanism.
In this position detection apparatus, the longitudinal member is provided with a plurality of magnets, and the plurality of magnets have the same axial length, are equidistant along the axial direction, and are elongated with the detection member. Assuming that the member is relatively moved in the axial direction, the combined signal of the output signals of the plurality of magnetic field detectors is one-to-one with the relative position (hereinafter referred to as absolute position) along with the relative movement. It is arranged in a correspondingly changing state. Therefore, the absolute position of the detection member relative to the longitudinal member can be detected based on the combined signal of the output signals of the plurality of magnetic field detection units.

Patentable invention

In the following, the invention that is claimed to be claimable in the present application (hereinafter referred to as “claimable invention”. The claimable invention is at least the “present invention” to the invention described in the claims. Some aspects of the present invention, including subordinate concept inventions of the present invention, superordinate concepts of the present invention, or inventions of different concepts) will be illustrated and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combinations of the constituent elements constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, the prior art, and the like. The added aspect and the aspect in which the constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

(1) (i) having a plurality of magnets and extending in the axial direction, and (ii) having one or more magnetic field detectors
And a detection member that is relatively movable in the axial direction, and the relative position in the axial direction of the detection member with respect to the longitudinal member is determined based on an output signal of the one or more magnetic field detection units. A position detecting device for detecting,
  When it is assumed that each of the plurality of magnets has the same length in the axial direction, is equally spaced along the axial direction, and the longitudinal member and the detection member are moved relative to each other. In addition, the position detection is characterized in that a combined signal of the output signals of the one or more magnetic field detection units changes in a one-to-one correspondence with the relative position in accordance with the relative movement. apparatus.
  The position detection device may be provided in the linear drive device or may be provided separately from the linear drive device. That is, (a) the longitudinal member of the position detection device, one of the detection members is a stator of the linear drive device,
One of the movers, the other of the longitudinal member and detection member is the other of the stator and mover, or (b) position
One of the longitudinal member and the detection member of the position detection device is a stator and a mover of the linear drive device, and the other of the longitudinal member and the detection member is a member provided separately from the stator and the mover. ) Position detection
Both the longitudinal member and the detection member of the device can be separate members from the stator and mover of the linear drive device.
In addition, when there are a plurality of magnetic field detection units, it is possible to synthesize their output signals, but when there is one magnetic field detection unit, it is not possible to actually synthesize the output signals. However, in the present invention, one output signal is considered to be a special synthesized signal obtained by synthesizing the same plurality of output signals. In the composite signal, (a) while changing sinusoidally according to the change of the magnetic pole,
(B) a signal representing an amplitude obtained by processing two output signals having different phases whose amplitude changes according to a change in absolute position, and (b) a vector sum signal of two signals representing two or more amplitudes (two that's all
(A signal representing the Lissajous curve of the signal representing the amplitude of the signal), (c) periodically changing according to the change in the magnetic pole
However, a signal representing a phase difference obtained by processing two output signals whose wavelengths change separately according to a change in absolute position, and (d) a vector sum of signals representing two or more phase differences. Trust
This is the case.
“The plurality of magnets have the same axial length and are arranged at equal intervals in the axial direction” means that when there is one longitudinal member, the longitudinal member It means that magnets having the same length are arranged at equal intervals. When two longitudinal members (a pair) are provided, in both longitudinal members, the axial lengths of all the magnets are the same. Thus, the intervals between adjacent magnets are all arranged in the same state.
“When a plurality of magnets are arranged in a state in which the combined signal of the output signals of one or more magnetic field detectors changes in a one-to-one correspondence with the relative position of the detection member to the longitudinal member” (a) Magnetic field detection
When there are two or more projecting parts, the combination of the relative positional relationships between each of the magnetic field detecting parts and each of the magnets is arranged in a state corresponding to the absolute position in a one-to-one relationship. (B) Detection Provided on the member
In the case where there is one magnetic field detection unit, the relative positional relationship between the single magnetic field detection unit and the magnet is arranged in a state corresponding to the absolute position on a one-to-one basis. When the combination of the relative positional relationship between each of the magnetic field detection units and each of the magnets corresponds to the absolute position on a one-to-one basis, the combined signal of the output signals of two or more magnetic field detection units is a pair on the absolute position. Corresponds to 1. The detection member is usually provided with two or more magnetic field detection units.
The “magnetic field detection unit” detects the direction of the magnetic field and the magnitude (strength) of the magnetic field.
In the position detection device described in Patent Document 1, the axial lengths of the plurality of magnets provided on the longitudinal member are different from each other. In the position detection device described in Patent Document 2, the length in the axial direction of the plurality of magnets is different or the interval between the magnets is different between the case of one fixing member and the case of the other fixing member. It is. On the other hand, in this position detecting device, a plurality of magnets having the same axial length are arranged at equal intervals in each of the longitudinal members. In this way, if a plurality of magnets having the same axial length are arranged at equal intervals, magnets having different axial lengths may be arranged, or compared to a case where magnets having different axial lengths are arranged at different intervals. Thus, the cost of the position detection device can be reduced.
(2) Assuming that the longitudinal member and the detection member are moved relative to each other, each of the output signals of the one or more magnetic field detection units periodically changes due to a change in the magnetic pole. The plurality of the plurality of magnetic field detection units are changed based on a change in relative positional relationship in at least one of a direction parallel to an axial direction and a direction orthogonal to each other between each of the one or more magnetic field detection units and each of the magnets. The position detection device according to item (1), in which a magnet is provided.
(3) The output signal includes (a) a short-period component that periodically changes due to a change in the magnetic pole, and (b) a long-period component that changes due to a change in the relative positional relationship. And (i) coarse absolute position detection for detecting a first absolute position based on the long-period component of the output signal.
And (ii) a fine absolute position detector that detects a second absolute position based on the first absolute position detected by the coarse absolute position detector and the short period component of the output signal; The position detection device according to item (2), including:
  The output signal of the magnetic field detection unit includes a short period component (vibration component) based on a change in the magnetic pole (the magnetic pole of the magnet whose magnetic field is detected by the magnetic field detection unit, hereinafter the same), and a magnet (its magnetic field detection). This includes a long-period component (position change component) based on a change in relative positional relationship with a magnet whose magnetic field is detected by the unit.
  Based on the long-period component, the first absolute position (hereinafter referred to as “approximate absolute position”) can be detected. “Approximate absolute position” can be used as an absolute position that includes a large error (for example, an error that is at most less than half of the pitch between magnetic poles), and can also be used as an element for detecting “detailed position”. It is also possible to do. The relative positional relationship with the magnetic field detector may be the same within the pitch between the magnetic poles, and the pitch between the magnetic poles may be the minimum unit of “approximate absolute position”.
Yes. In this case, there is a possibility that an error in the pitch between the magnetic poles is included at the maximum.
  Based on the “approximate absolute position” and the short-period component, the “detailed absolute position” can be detected. The “detailed absolute position” is an absolute position determined by “approximate absolute position” and a position within a pitch between magnetic poles defined by a magnet determined by a long period component. For example, the magnet corresponding to the long period component is determined from the “approximately absolute position”, but the absolute position of the magnet is known. Specifically, the starting point of the pitch between the magnetic poles defined by the magnet determined by the long period component {for example, (a) the center point of the N pole, (b) the center point between the N pole and the S pole, (c ) Maximum output signal from magnetic field detector
Or the minimum value or the absolute position of the point that becomes 0} is known (the absolute position of this starting point may be an “approximate absolute position”). Based on the short period component, the distance from the starting point in the pitch between the magnetic poles is determined. Therefore, “detailed absolute position” is detected based on the absolute position of the starting point of the pitch between the magnetic poles of the magnet determined by “approximately absolute position” and the distance from the starting point detected based on the short period component. be able to.
  Hereinafter, an aspect of arrangement of a plurality of magnets for detecting “approximate absolute position” will be described. “The relative positional relationship is determined in a one-to-one relationship with the absolute position” and “the composite signal changes in a one-to-one relationship with the absolute position” is determined in a one-to-one relationship with respect to a desired minimum unit of the absolute position. Means that.
(4) When it is assumed that the plurality of magnets have moved the longitudinal member and the detection member relative to each other, the shaft between the one or more magnetic field detection units is associated with the relative movement. The position detection device according to any one of (1) to (3), wherein the relative positional relationship in at least one of a direction parallel to the direction and a direction orthogonal to the axial direction changes..
  When there is one magnetic field detection unit, the plurality of magnets have a relative positional relationship in at least one of a direction perpendicular to the axial direction between one magnetic field detection unit and the magnet and a direction parallel to the axial direction. Are arranged in a state corresponding to the absolute position on a one-to-one basis.
  In the case where there are two or more magnetic field detection units, the plurality of magnets have a combination of the above-described relative positional relationship between each of the two or more magnetic field detection units and each of the magnets in a pair with the absolute position. 1 in a state corresponding to 1.
(5) The plurality of magnets are disposed in a state of being moved relative to magnets adjacent to each other in a direction orthogonal to the axial direction at the positions disposed at equal intervals. Item 6. The position detection device according to any one of items (4) to (4).
  The movement includes rotation, and the relative movement in the direction orthogonal to the axial direction includes linear relative movement in the direction orthogonal to the axial direction and relative rotation around the axis. The equally spaced state is maintained.
(6) The items (1) to (5), wherein the position of each of the plurality of magnets in a direction orthogonal to the axial direction is determined by the relative position between the longitudinal member and the detection member. The position detection device according to any one of the above.
  The “position in the direction orthogonal to the axial direction” includes a rotational position determined by a phase around the axis.
  When there is one longitudinal member, each of the plurality of magnets is disposed in a state determined in a one-to-one relationship with the absolute position.
  When there are two longitudinal members and two or more magnetic field detectors, a combination of postures determined by the absolute positions of a plurality of magnets is arranged in a state determined in a one-to-one relationship with the absolute positions.
(7) The first and second straight lines that are separated from each other in a direction perpendicular to the axial direction and that are parallel to the axial direction are defined with respect to the longitudinal member, and the longitudinal member and the magnetic field detector are Assuming that the relative movement is made along the first straight line and the second straight line, the change in at least one of the amplitude and the wavelength of the output signal of the magnetic field detection unit accompanying the relative movement is along the first straight line. In any one of the items (1) to (6), the plurality of magnets are disposed in a state different from each other when the relative movement is performed and when the relative movement is performed along the second axis direction. The position detection device (Claim 7).
  The first straight line and the second straight line are parallel to each other in the axial direction and separated from each other in a direction orthogonal to the axial direction. Further, in a plan view or a side view, it may be a straight line that overlaps the longitudinal member or a straight line that does not overlap.
  For example, when it is assumed that the plurality of magnets are moved relative to each other along the first straight line.
In addition, the output signal may be arranged with the same amplitude but with the amplitude changing on the assumption that the output signal is relatively moved along the second straight line. In this case, the absolute position is detected based on the combined signal of the output signals when at least one of the magnetic field detectors is relatively moved along the second straight line.
  Even if it is assumed that the plurality of magnets are relatively moved along the first straight line and the magnetic field detector is relatively moved along the second straight line, the wavelength of the output signal changes. The wavelength change modes can be arranged in different states. In this case, (a) 1
When the absolute position is detected based on the combined signal of the output signals when one or more magnetic field detectors are relatively moved along either the first straight line or the second straight line, (b) the first straight line On the second straight line
When the absolute position is detected based on the combined signal of the output signals when moved relative to each other, (c) relative to the first straight line, the second straight line, the third straight line, the fourth straight line, etc. If moved
In some cases, the absolute position is detected based on the combined signal of the output signals.
  The wavelength refers to the distance between points where the same state is reproduced, and the period refers to the interval at which the same state is reproduced. The period may refer to a time interval, but is not limited thereto. When the period is used to mean that it is not a time interval, it can be considered to be the same as the wavelength. In addition, when the period refers to a time interval, in the entire stroke, when the relative movement speed between the longitudinal member and the detection member is constant, the period is the same when the wavelength is the same, As the wavelength changes, the period changes accordingly. Therefore, when the relative movement speed between the longitudinal member and the detection member is constant, it can be said that the period is the same when the wavelength is the same.
(8) When it is assumed that the plurality of magnets have moved the longitudinal member and the detection member relative to each other, the relative movement between the magnet and the magnetic field detection unit in a direction orthogonal to the axial direction. The position detection device according to any one of items (1) to (7), which is arranged in a state where the distance of the device changes..
  When the distance between the magnetic field detector and the magnet is large, the amplitude of the output signal is smaller than when the distance is small. Therefore, the amplitude obtained by processing the output signals of one or more magnetic field detectors (which is an aspect of the combined signal), the combination of the amplitudes of the output signals of two or more magnetic field detectors (two or more The absolute position of the detection member can be detected based on any one of the combined signals of the signals representing the amplitude).
  When a plurality of magnets are arranged in a state in which a combination of distances in the direction orthogonal to the axial direction between each of the one or more magnetic field detection units and each of the magnets is determined in a one-to-one relationship with the absolute position The “approximate absolute position” is detected based on the combined signal of the output signals of the one or more magnetic field detectors.
(9) When it is assumed that the plurality of magnets move the longitudinal member and the detection member relative to each other in one direction along the axial direction, The position detecting device according to (8), wherein the distance between the terminals is monotonously increased or decreased..
  Assuming a third straight line parallel to the axial direction and spaced from all one end faces of the plurality of magnets, the distance between the third straight line and each one end face of the magnet is 1: 1 with the absolute position. A plurality of magnets are arranged in a corresponding state.
  When the longitudinal member and the detection member are relatively moved, if the magnetic field detection unit is relatively moved along the third straight line, the distance between the magnetic field detection unit and each of the magnets increases monotonously. Or will decrease.
  The plurality of magnets may be provided in a state where the distance from the magnetic field detection unit changes linearly or in a state where the distance changes in a curve. In any case, since the distance does not change periodically, the distance and the absolute position correspond one-to-one.
  The position detection device described in this section is suitable for absolute detection of the relative position between the stator and the mover in the one-side linear motor.
(10) A pair of the longitudinal members is provided in parallel with each other, and in each of the longitudinal members, a third straight line that is parallel to the axial direction and separated from all end faces of the plurality of magnets is assumed.
A distance between the third straight line in one of the longitudinal members and the one end face of each of the magnets, and a third straight line in the other of the longitudinal members and the one end face of each of the magnets. The position according to any one of the items (1) to (8), wherein the plurality of magnets are arranged in a state in which the combination with the distance between them corresponds to the relative position on a one-to-one basis. Detection device.
  In each of the longitudinal members, when the distance between the one end surface of the magnet and the magnetic field detector periodically changes with respect to the change in the absolute position, the distance and the absolute position do not correspond one-to-one. A plurality of sets (magnetic field detection unit and longitudinal member) are provided. Therefore, based on the combined signal of the output signal of the magnetic field detection unit provided opposite to one longitudinal member of the detection member and the output signal of the magnetic field detection unit provided opposite to the other longitudinal member, The position can be detected.
  For example, in one longitudinal member and the other longitudinal member, a plurality of magnets can be provided in a state where the distances change in different patterns (for example, different periodic functions). For example, one longitudinal member varies with the sin function and the other longitudinal member has a saw.
This corresponds to a state that changes in a wave shape.
  Note that the periodic function includes a trigonometric function, a function that changes in a sawtooth waveform, a function that changes in a triangular wave shape, and the like, but does not include a simple function that changes between an ON state and an OFF state. In addition, the periodic function is one in which the entire stroke is one wavelength or less, and does not include the periodic function in which the entire stroke is one wavelength or more. The same applies to items (11) and (12) below.
  The position detection device described in this section is suitable for absolute detection of the relative position between the stator and the movable part in the double-sided linear motor.
(11) When the pair of the longitudinal members are provided in parallel to each other, and each of the longitudinal members is assumed to be a third straight line that is parallel to the axial direction and spaced from all one end surfaces of the plurality of magnets. In the state where the distance between each of the third straight lines and one end face of each of the magnets is different in at least one of the phase and the wavelength with respect to the relative position, but changes with the same periodic function, The position detection device according to any one of items (1) to (8), wherein a plurality of magnets are provided. (12) A pair of the longitudinal members are provided in parallel to each other, and at least one of the magnetic field detection units is provided at a position facing each of the pair of longitudinal members. Assuming that the magnets have moved the longitudinal member and the detection member relative to each other, a distance in a direction perpendicular to the axial direction between each magnetic field detection unit is associated with the relative movement. (1)
The position detection device according to any one of the items (8)Claim 1).
  Assuming a third straight line parallel to the axial direction spaced from all one end faces of the plurality of magnets for each of the longitudinal members, the distance between each of the third straight lines and one end face of each of the magnets is A plurality of magnets are arranged in a state where the phases are different but change at the same wavelength.
  For example, in one longitudinal member, a plurality of magnets are arranged in a state that changes with a sin function,
In the other longitudinal member, it can arrange | position in the state which changes with a cos function.
(13) Each of the plurality of magnets is a rod-like magnet extending in the longitudinal direction, and the dimensions perpendicular to the longitudinal direction are the same as each other. Assuming that the longitudinal member and the detection member are moved relative to each other in a posture orthogonal to the direction, the distance between the one end in the longitudinal direction and the magnetic field detection unit is accompanied by the relative movement. The position detecting device according to any one of the items (1) to (8) and (10) to (12) arranged in a changing state (Claims 2 and 3).
  The magnets may have N and S poles at both ends, or may have N and S poles on both sides. When the longitudinal member is one of the mover and the stator of the linear motor, magnets whose both side surfaces are N-pole and S-pole, respectively, are used.
(14) Assuming a first straight line and a second straight line that are separated from each other in a direction perpendicular to the axial direction with respect to the longitudinal member, the magnetic field detection unit is connected to the first straight line. Assuming that the relative movement is made along the second straight line, the wavelength of the output signal of the magnetic field detection unit is relatively moved along the second straight line when the wavelength of the output signal is relatively moved along the first straight line. If
The position detection device according to any one of (1) to (7), wherein the plurality of magnets are arranged in a state of changing in different modes.
(15) The phase difference of the output signal when the plurality of magnets are moved along the second straight line with respect to the output signal when the magnetic field detection unit is moved along the first straight line is the longitudinal direction. The position detection device according to item (14), wherein the position detection device is disposed in a state of being changed in accordance with a change in a relative position between the member and the detection member.
  The wavelength of the output signal varies in a different manner depending on whether the magnetic field detector is relatively moved along the first straight line or when the magnetic field detector is relatively moved along the second straight line. Therefore, the combination of the wavelength of the output signal (first signal) when moved relatively along the first line and the wavelength of the output signal (second signal) when moved relatively along the second line is When there is a one-to-one correspondence with the absolute position, the absolute position can be detected based on the combined signal of the first signal and the second signal.
  Also, the first signal and the second signal have different wavelengths, and a plurality of magnets are disposed in a state in which these phase differences (which are one aspect of the combined signal) correspond to the absolute position on a one-to-one basis. In some cases, the absolute position can be detected based on the phase difference.
  On the other hand, when the phase difference periodically changes, a magnetic field detector that is relatively moved along the third straight line, the fourth straight line, etc. is provided, and the phase difference between the third signal and the fourth signal is It is desirable to provide a plurality of magnets and to provide a magnetic field detector so that the combination of the phase difference between the first signal and the second signal and the absolute position correspond to each other on a one-to-one basis. In this case, the absolute position can be detected based on a combined signal of the phase difference between the first signal and the second signal and the phase difference between the third signal and the fourth signal.
  This term is suitable for absolute detection of the relative position between the mover and the stator in a cylindrical linear motor.
(16) Each of the plurality of magnets has a cylindrical outer peripheral surface, and both end surfaces are parallel to each other, andFor the center line of the cylinder with the cylindrical surfaceInclinedShapedAnd the shape and dimensions are the same in each of the plurality of magnets,
  Each of the plurality of magnets isWith the center line in a posture parallel to the axial direction,In a state where the relative rotational phase changes by an equal angle in the axial direction,Arranged(14) or (15) position detection device (Claims 4 and 5).
  Each of the plurality of magnets has a cylindrical outer peripheral surface, and both end surfaces are parallel to each other and inclined with respect to the axial direction. Each of the plurality of magnets may be solid or hollow, but have the same shape and dimensions as each other.
  Magnets are arranged at equal intervals and in the same posture, and at that position, the magnets are rotated relative to adjacent magnets by equal angles. For example, first, second, and third magnets are arranged at equal intervals in the same posture, the first magnet is left as it is, the second magnet is rotated by θ, and the third magnet is rotated by 2θ. Rotate in the same direction. The first, second, and third magnets are in a posture that is rotated by θ relative to the adjacent magnets.
  As a result, assuming the first straight line and the second straight line parallel to the axial direction, the change in the case where the distance between the edges of adjacent magnets along the first straight line changes as the absolute position changes. The mode and the mode of change when the distance between the edges of adjacent magnets along the second straight line changes with the change of the absolute position are different from each other. For example, the distance between the edge of the first magnet and the edge of the second magnet along the first straight line is Δ_1a, The distance between the edge of the second magnet and the edge of the third magnet is Δ_1bAnd the distance between the edge of the first magnet and the edge of the second magnet along the second straight line is Δ_2a, The distance between the edge of the second magnet and the edge of the third magnet is Δ_2b(Δ_1a, Δ_1b) And (Δ_2a, Δ_2b) Is different. For example, each distance Δ_1a, Δ_1b, Δ_2a, Δ_2bAre different from each other or the change in distance (Δ_1a-Δ_1b), (Δ_2a-Δ_2b) Is different. On the other hand, both along the first straight line and along the second straight line, the dimensions of the magnets (the axial lengths of the first magnet, the second magnet, and the third magnet) are the same. It is. Therefore, the manner in which the wavelength of the output signal changes differs between when the magnetic field detector is relatively moved along the first straight line and when it is relatively moved along the second straight line.
  In addition, since both end faces of the magnet are inclined with respect to the axial direction and are parallel to each other, the first straight line and the second straight line are assumed to be at positions separated by 180 ° in the circumferential direction. When the magnetic field detector is relatively moved along the straight line, if the wavelength of the output signal is increased, the magnetic field detector is relatively moved along the second straight line.
When moved, the wavelength of the output signal is reduced. That is, one wavelength is larger or smaller than the other in the output signal when relatively moved along the first straight line and the output signal when relatively moved along the second straight line. .
  From this, when the phase difference caused by the wavelength difference between the output signals of the two magnetic field detectors provided at positions 180 ° apart in the circumferential direction corresponds to the absolute position on a one-to-one basis in all strokes. Can detect the absolute position based on the phase difference between the two output signals.
  On the other hand, when the phase difference periodically changes over the entire stroke, a plurality of sets of two straight lines separated from each other by 180 ° are provided, and the plurality of sets of phase differences correspond one-to-one with the absolute position. As described above, if the magnetic field detection unit is provided, the absolute position can be detected based on a plurality of sets of phase differences (a combined signal of signals representing a plurality of phase differences).
(17) It is assumed that a plurality of the magnetic field detection units are provided on the detection member in a direction intersecting the axial direction, and the plurality of magnets move the longitudinal member and the detection member relative to each other. In this case, the relative positional relationship between each of the plurality of magnetic field detection units in a direction parallel to the axial direction changes with the relative movement, and the position detection device is (1) to (8), (14) to (16) including a calculation unit that calculates the relative position between the longitudinal member and the detection member based on a combined signal of output signals from a plurality of magnetic field detection units. ) The position detection device according to any one of (Claim 6).
  For example, the absolute position is determined based on a combined signal of a plurality of output signals such as an output signal of the magnetic field detector that is relatively moved along the first straight line and an output signal of the magnetic field detector that is relatively moved along the second straight line. Detected.

In the next section, the arrangement of magnets for detecting “detailed absolute position” will be described.
(18) The position detection device according to any one of (1) to (17), wherein the detection member includes a plurality of magnetic field detection units separated in a direction parallel to the axial direction .
If a plurality of magnetic field detectors separated in a direction parallel to the axial direction are provided, the output signals of the magnetic field detectors can be regarded as changing at the same wavelength and in different phases. Based on the direction of the phase shift, the direction of movement of the detection member can be acquired.
Further, based on two output signals that change with different phases with substantially the same amplitude and wavelength, it is possible to detect the absolute position within the pitch between the magnetic poles.
In particular, when the phase difference between the two output signals is ¼ phase shift, the Lissajous curve becomes a circle and the calculation for obtaining the absolute position within the pitch between the magnetic poles becomes easy. Can be easily obtained.

(19) The position detection device includes an information processing unit that acquires a combined signal of the one or more magnetic field detection units and detects a relative position of the detection member based on the combined signal. The position detection device according to any one of items 18).
(20) A parallel direction information processing unit that detects the relative position based on a composite signal of output signals of two or more magnetic field detection units provided in a direction parallel to the axial direction. The position detection device according to item (19), including:
In one longitudinal member, when a plurality of magnets are provided in a state where the distance between the third straight line and the magnet corresponds to the absolute position on a one-to-one basis, they are separated in a direction parallel to the axial direction. Both “approximate absolute position” and “detailed absolute position” can be acquired based on the output signals of only two or more magnetic field detectors.
For example, two magnetic field detectors are provided with a 1/4 phase separation in the axial direction, and the output signal changes sinusoidally based on the change of the magnetic pole, while the amplitude changes based on the change of the distance. In the case where the values (magnitudes) of the output signals of the two magnetic field detectors are a and b, the amplitude W of the output signal is
W = √ (a ² + b ² )
It becomes. The “approximate absolute position” is acquired based on the amplitude W.
Next, a magnet is specified based on the amplitude W, and a position within the pitch between magnetic poles determined by the magnet is obtained. Assuming a circle with amplitude W, the central angle θ formed by the coordinates (a, b) and the reference point of the pitch between the magnetic poles is obtained. The center angle θ corresponds to the distance M _X from the reference point when the pitch M between the magnetic poles is 2π. Therefore, the formula M _X = M · θ / (2π)
If this is followed, the distance M _X from the reference point within the pitch M between the magnetic poles can be acquired.
(21) The information processing unit (a) detects a first relative position based on a combined signal of output signals of two or more magnetic field detection units provided in a direction orthogonal to the axial direction. And (b) a magnetic pole of a magnet determined by the first relative position based on a composite signal of output signals of two or more magnetic field detectors provided in a direction parallel to the axial direction. The position detection device according to item (19), further including a sub information processing unit that detects a position within the inter-pitch.
The main information processing unit acquires a composite signal of the long-period component of the output signal, detects an “approximate absolute position” based on the composite signal, and determines the position in the pitch between the magnetic poles acquired by the sub information processing unit. Detected. Based on “approximate absolute position” and “position in the pitch between magnetic poles”, “detailed absolute position” can be detected.
(22) In any one of the above items (1) to (21), the position detection device can detect the relative position without relatively moving the longitudinal member and the detection member. The position detection device described.
In the position detection device described in this section, regardless of the relative position between the longitudinal member and the detection member, the absolute position can be detected based on the output signal of the magnetic field detection unit at that position.
For example, the absolute position can be detected based on the magnitude of the sin signal and the state of change (increase, decrease, no change) with one cycle as the whole stroke. However, the absolute position cannot be detected based only on the magnitude of the sin signal. In other words, the absolute position can be detected by a slight relative movement from that position, but the absolute position cannot be detected based only on the output signal at that position.
On the other hand, the absolute position can be detected based on a signal obtained by combining the magnitude of the sine signal with one cycle as the whole stroke and the magnitude of the cos signal with one cycle as the whole stroke. For example, the sum of the sin signal vector and the cos signal vector (corresponding to the combined signal) moves on a circle with a total stroke of 2π, so if based on the sum vector signal, the angle from the reference point Can be obtained, and the absolute position, which is the position for the entire stroke, can be detected. In this case, the absolute position can be detected without relative movement. In the position detection device described in this section, the “synthetic signal” includes a composite signal of the latter sin signal and the cos signal, and does not include the former sin signal.
In addition, when the longitudinal member and the detection member are moved relative to each other, the output of the magnetic field detection unit at that position can be stored without storing the output signal and the information obtained by processing the output signal. Based on the signal, the absolute position can be detected.
For example, if the absolute position detected last time is stored in an incremental position detection device, the current absolute position when the relative position is moved from that position can be detected. However, if the previous absolute position is not stored, only the distance from the previous absolute position can be detected, and the absolute position cannot be detected. The position detection apparatus described in this section is not an incremental type, and can detect the current absolute position without storing the previous absolute position.

(23) (i) a longitudinal member having a plurality of magnets and extending in the axial direction; and (ii) a detection member having one or more magnetic field detectors and relatively movable in the axial direction with the longitudinal member. A position detection device that detects a relative position of the detection member in the axial direction with respect to the longitudinal member based on an output signal of the one or more magnetic field detection units,
When it is assumed that each of the plurality of magnets has the same length in the axial direction, is equally spaced along the axial direction, and the longitudinal member and the detection member are moved relative to each other. In addition, the relative positional relationship between at least one of the direction parallel to the axial direction and the direction orthogonal to the axial direction changes with the one or more magnetic field detection units in accordance with the relative movement. Arranged position detection device.
The technical features described in any one of the items (1) to (22) can be employed in the position detection device described in this item.
(24) (i) a longitudinal member having a plurality of magnets and extending in the axial direction; and (ii) a detection member having one or more magnetic field detectors and relatively movable in the axial direction with the longitudinal member. A position detection device that detects a relative position of the detection member in the axial direction with respect to the longitudinal member based on an output signal of the one or more magnetic field detection units,
Each of the plurality of magnets has the same length in the axial direction, is equally spaced along the axial direction, and is spaced apart in a direction perpendicular to the axial direction. When it is assumed that a parallel first straight line and a second straight line are defined with respect to the longitudinal member, and the longitudinal member and the magnetic field detecting unit are relatively moved along the first straight line and the second straight line, When at least one of the amplitude and the wavelength of the output signal of the magnetic field detection unit accompanying the relative movement is relatively moved along the first straight line, and when the relative movement is performed along the second axis direction, Position detecting devices arranged in different states.
The technical features described in any one of the items (1) to (22) can be employed in the position detection device described in this item.
(25) The detection member is an armature provided with a coil, and is opposed to the longitudinal member with a gap in a direction orthogonal to the axial direction, and is disposed so as to be relatively movable with respect to the longitudinal member. The armature and the longitudinal member constitute a linear motor, and the position detection device detects a relative position in the axial direction between the longitudinal member and the armature in the linear motor. The position detection device according to any one of items (1) to (24) (claim 8) .
In the linear motor, the longitudinal member is provided with a plurality of magnets. Therefore, the relative position of the armature with respect to the longitudinal member can be detected using the magnet. That is, there is no need to provide a separate position detection device, and the absolute position can be detected by providing a magnetic field detection unit in the armature. As a result, it is possible to reduce the size of the linear motor and suppress an increase in cost.
Further, since the axial lengths of the plurality of magnets are the same as each other, thrust can be stably generated in the linear motor, and the coil current control is the same as that of the conventional linear motor. be able to.
(26) (i) a longitudinal member having a plurality of magnets and extending in the axial direction; (ii) one or more coils;
And (iii) an armature disposed on the longitudinal member with a gap in a direction orthogonal to the axial direction, and (iii) an output signal of the one or more magnetic field detection units A linear motor including a position detection device that detects a relative position of the longitudinal member and the armature in the axial direction based on a composite signal;
When it is assumed that each of the plurality of magnets has the same length in the axial direction, is equally spaced along the axial direction, and the longitudinal member and the armature are relatively moved. In addition, the linear motor is arranged in such a manner that a combined signal of the output signals of the one or more magnetic field detectors changes corresponding to the relative position in a one-to-one relationship with the relative movement. .
In this section, the technical features described in any one of the paragraphs (1) to (25) can be adopted.
The linear motor can be used as a drive source for a transporter that continuously transports articles, or can be used as a drive source for transporting substrates, pulling out trays, and raising and lowering magazines in an electronic circuit component mounting machine. It can be used as a drive source for movement and elevation.

A position detection apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIGS. 1 and 2, the position detection device in the present embodiment detects an absolute position that is a relative position between a mover and a stator in a double-sided (counter electrode) type linear motor. The linear motor is a moving coil type in which the stator has a magnet and the mover has a coil. The absolute position is a position determined by a distance from a predetermined reference position.
The base 10 extends in the axial direction P, and a pair of stators 12 and 14 are fixed in parallel to the axial direction P. The stators 12 and 14 include magnet holding members (housings) 16 and 17, respectively, and a plurality of magnets 18 and 19 held inside the magnet holding members 16 and 17, respectively. The base 10 is provided with a pair of guide rails 20 and 21 extending in the axial direction P in parallel with each other. In the present embodiment, the longitudinal direction corresponds to the axial direction P, and the stators 12 and 14 correspond to the longitudinal members.
A mover 24 is disposed between the pair of stators 12 and 14 with a gap δ therebetween. The mover 24 has engaging portions 26 and 27 that can be engaged with the guide rails 20 and 21, and the engaging portions 26 and 27 are engaged with the guide rails 20 and 21, whereby the stators 12 and 14 are engaged. Is held so as to be relatively movable in the axial direction P. As shown in FIG. 3, the mover 24 includes a plurality of coils 30. When a current is supplied to the coil 30, the mover 24 is driven by a propulsive force generated between the coil 30 and the plurality of magnets 18 and 19. , Moved in the axial direction P. In this embodiment, the pair of stators 12 and 14 and the movable element 24 constitute a double-sided linear motor 32.

Two sensors A, B and C, D are provided on both sides of the mover 24 so as to face the stators 12, 14, respectively. Sensors A, B and C, D are magnetic field detectors composed of Hall elements or the like, and detect the magnetic flux density. Therefore, both the direction and magnitude of the magnetic field can be detected even in a stationary state.
As shown in FIG. 3, the sensors A and B and the sensors C and D are spaced apart from each other at positions where the movable element 24 faces the inside of the upper end surfaces 40 and 41 of the magnets 18 and 19 of the stators 12 and 14. Attached. Even when the mover 24 is relatively moved in the axial direction P over the entire stroke L, the sensors A, B, C, and D are positioned above the upper end surfaces 40 and 41 of all the magnets 18 and 19. It is attached.
In this embodiment, the sensors A and C and the sensors B and D are located at the same position in the axial direction P, and the positions where the sensors A and B and the sensors C and D are separated in a direction parallel to the axial direction P (the output signal is (Position shifted by 1/4 phase). For example, when the sensors A and C are opposed to the N pole of the magnet, the sensors B and D are attached in a state of being positioned between the magnets (between the N pole and the S pole).

In each of the stators 12 and 14, a plurality of magnets 18 and 19 are arranged at equal intervals along the axial direction P as shown in FIGS. 4 (a) and 4 (b), respectively. Further, each of the magnets 18a, b... And the magnets 19a, b,... Has a rod shape, and as shown in FIGS. Z and the dimension X in the width direction are the same. Further, the magnets 18a, b,... And the magnets 19a, b,... Have both side faces 42, 43 as N poles and S poles, respectively, on the inner face (on the side facing the movable part 24). , N poles, and S poles are arranged at equal intervals (Y) so that they appear alternately.
In the stator 12, the magnets 18a, b,... Have a distance ΔH between the upper end surface 40 and the sensors A and B as shown in FIGS. In the stator 14, the magnets 19 a, b,... Are changed in a stepwise manner from a point to a sine wave (−sin), as shown in FIGS. The distance ΔH between the upper end surface 41 and the sensors C and D is provided in a state where the distance ΔH changes stepwise in a sine wave form (cos) (in a state where the distance ΔH changes by ¼ phase with respect to the change of the magnet 18).
In addition, two (magnets 18a, b), (magnets 18c, d), ..., (magnets 19a, b), (magnets 19c, d), ... are paired, and each has a distance ΔH. Are mounted in the same posture.

As will be described later, the pitch M between the magnetic poles is defined by two magnets 18a and 18b adjacent to each other (the same applies to the magnets 19a and 19b), and the minimum unit of "approximate absolute position" is defined.
The pitch M between the magnetic poles is a distance M between the center in the axial direction P of the N-pole magnet 18a (19a) and the center in the axial direction P of the N-pole magnet 18c (19c) adjacent thereto. This distance is the same as the distance between the side surface 44 in the axial direction P of the magnet 18a and the side surface 44 on the same side of the magnet 18c, and the equation M = 2X + 2Y
It becomes the length represented by. This length is a length determined by the dimension X in the width direction of the magnets 18 and 19 and the interval Y, and is determined by the size and arrangement of the pair of magnets 18a and 18b (magnets 19a and 19b).
Further, the amplitude W is the same while the sensor faces the pair of two magnets 18a and 18b (magnets 19a and 19b). On the other hand, since the pitch M between the N poles is a distance between the N poles, the amplitude W is different between the case of facing the magnet 18a (19a) and the case of facing the magnet 18c (18c). However, the difference in amplitude is slight, and the phase affected by the magnetic field of the magnet 18c is small over the entire pitch between the N poles, so even if the amplitude W is considered to be constant at the pitch between the N poles. There is no problem. In addition, the pitch between the N poles is a minimum unit in detecting “approximate absolute position”.
The dimensions X and the distance Y of the magnets 18 and 19 are determined so that the thrust can be output effectively as the linear motor 32 and the absolute position detection accuracy can be satisfied. For absolute position detection, it is desirable that the dimension X and the interval Y are smaller.
5 (a) and 5 (b), the sensors A, B, C, and D pass on the alternate long and short dash line, and the coil 30 is between the broken lines due to the relative movement of the mover 24 to the stators 12 and 14. Are moved relative to the magnets 18 and 19. However, since the length Z of the magnets 18 and 19 is actually longer than the dimension X in the width direction and the interval Y, the region (the region between the broken lines) that the coil 30 can face is shown in FIG. ), Wider than the area shown in (b).

  As shown in FIG. 3, the linear motor 32 is controlled by a motor control device 50 mainly composed of a computer. The motor control device 50 includes an execution unit 52, a storage unit 54, an input / output unit 56, and the like, to which the sensors A, B, C, D, the coil 30, and the like are connected. The motor control device 50 controls the current supplied to the coil 30 and acquires the absolute position based on the output signals of the sensors A, B, C, and D.

As the mover 24 moves relative to each other, the output signals of the sensors A to D periodically change as shown in FIGS.
When the sensors A to D are opposed to the N pole, the output signal is maximized. When the sensors A to D are opposed to the S pole, the output signal is minimized. . The wavelength of the output signal is the pitch M between the N poles of the magnets 18 and 19. The change component of the output signal due to the change of the magnetic pole of the magnet facing the sensor is referred to as a short period component.
Further, the output signals of the sensors B and D change with a ¼ phase shift with respect to the output signals of the sensors A and C.
When the sensor B is moved in the direction of the arrow Q, the output signal of the sensor B advances by ¼ phase with respect to the output signal of the sensor A. Be late. Using this fact, the traveling direction of the mover 24 can be known.

The amplitude W of the output signals of the sensors A to D is smaller when the distance ΔH between the sensors A to D and the upper end surfaces 40 and 41 of the magnets 18 and 19 is large than when the distance ΔH is small.
When the mover 24 is relatively moved in the direction of the arrow Q, the distance ΔH between the sensors A and B and the upper end surface 40 of the magnet 18 increases and then decreases and increases. Therefore, as shown in FIG. 5C, the output signals of the sensors A and B increase after the amplitude W decreases and decrease again. Further, since the distance ΔH is the same within the pitch M between the magnetic poles, the amplitude W is the same while the output signal changes for one period. In this embodiment, a component that changes in a short cycle at the wavelength M of the output signal is referred to as a short cycle component, and a component (amplitude) that changes with the entire stroke L as one wavelength due to a change in the distance ΔH is a long cycle component. Called. The output signals of the sensors A and B obtained by simulation are shown in FIG. The solid line represents the output signal of sensor A, and the broken line represents the output signal of sensor B. The simulation is performed by dividing the magnets 18, 19 and the like by the finite element method (FEM). Since the division elements (sometimes referred to as cells and meshes) used in the finite element method are relatively large, it is considered that the calculation error is large.
The same applies to the output signals of the sensors C and D, and changes as shown in FIG. As the distance ΔH between the sensors C, D and the upper end surface 41 of the magnet 19 increases and then decreases, the amplitude W increases after decreasing. The output signals of the sensors C and D obtained by the simulation are shown in FIG. The solid line represents the output signal of sensor C, and the broken line represents the output signal of sensor D.

FIG. 7A shows a Lissajous curve obtained by synthesizing the output signals of the sensors A and B. The Lissajous curve is a curve indicating a trajectory of two-dimensional motion obtained by synthesizing simple vibrations in directions perpendicular to each other. As described above, the short period components of the output signals of the sensors A and B can be regarded as having the same period and amplitude W, and the phase difference is π / 2 (1/4 wavelength). Is a circle. The short period components of the output signals of the sensors A and B have the same period and amplitude.
In addition, the radius of the Lissajous circle is a size corresponding to the amplitude W. The amplitude W changes as the mover 24 moves, that is, as the absolute position changes, and the radius of the circle changes stepwise as the absolute position changes.
Similarly, a Lissajous curve obtained by combining the output signals of the sensors C and D is shown in FIG. Even in this case, the radius changes as the amplitude changes due to the change in absolute position.

In the entire stroke L, the amplitude obtained from the output signals of the sensors A and B changes sinusoidally (−sin) as shown in FIG. As shown in FIG. 5 (f), the amplitude obtained from the output signals of the sensors C and D changes with a ¼ phase shift (π / 2 shift) with respect to the graph shown in (e) (cosine wave). ). Further, as shown in FIGS. 5E and 5F, the amplitude W changes with the full stroke L as a wavelength (changes with the full stroke L as one cycle).
From this, it is also possible to represent the entire stroke L as 2π, in which case the absolute position of each can be represented as an angle θ.
FIG. 8A shows the relationship between the amplitude and the absolute position obtained by the simulation. The solid line in FIG. 8A represents the relationship between the amplitude obtained from the output signals of the sensors A and B and the absolute position (angle), and the broken line represents the amplitude obtained from the output signals of the sensors C and D and the absolute position (angle). Represents the relationship.
The total stroke L is an area in which the mover 24 is relatively movable and is determined by a stopper (not shown). The absolute position is a distance from a reference position defined by the stopper {eg, 0 point in FIGS. 8A and 8B).

Therefore, the absolute position can be found based on these two amplitudes. That is, the combination of the two amplitudes has a one-to-one correspondence with the absolute position of the movable portion 24 with respect to the stators 12 and 14. One position is always determined.
Specifically, when the amplitude determined by the output signals of the sensors A and B is W _AB and the amplitude determined by the output signals of the sensors C and D is W _CD , the point S _{L in} FIG. 9A is determined. . And in that case, the angle θ
tan θ = − (W _AB0 −W _AB ) / (W _CD0 −W _CD )
θ = arctan {− (W _AB0 −W _AB ) / (W _CD0 −W _CD )}
And the sign of the value of (W _AB0 −W _AB ) and (W _CD0 −W _CD ) (whether it is a positive value or a negative value).
The amplitude W _AB of the output signals of the sensors A and B can be calculated from the values I _A and I _B of the output signals of the sensors A and B by the formula W _AB = √ (I _A ² + I _B ² )
The amplitude W _CD of the output signals of the sensors C and D can be obtained from the values I _C and I _D of the output signals of the sensors C and D using the formula W _CD = √ (I _C ² + I _D ² )
Can be obtained according to.
The values W _AB0 and W _CD0 are intermediate values between the maximum value and the minimum value of the amplitude W, and are obtained after acquiring the Lissajous curve. Further, since it is determined by an intermediate value between the minimum value and the maximum value of the distance ΔH between the sensor and the magnet, it can be obtained and stored in advance.
In the present embodiment, the signal representing the amplitude W _AB is obtained by processing the output signals I _A and I _B of the sensors A and B, and the signal representing the amplitude W _CD is obtained from the output signals I and C of the sensors C and D. _C, represented by treating I _D, by treating these amplitudes W _AB, the W _CD, a signal representing the angle θ is obtained. The signal representing the angle θ is an aspect of the combined signal in the present embodiment.

Thus, if the angle θ is obtained, the formula L _X = θ · L / (2π)
Thus, the absolute position L _X can be obtained.
In this embodiment, the storage unit 54 stores the amplitude W _AB obtained from the output signals of the sensors A and B in the linear motor 32, the amplitude W _CD obtained from the output signals of the sensors C and D, and the absolute position. Is stored in advance. Therefore, based on the amplitudes W _AB and W _CD obtained by processing the signals of the sensors A, B, C, and D in the motor control unit 50 and the relationship stored in advance, as shown in FIG. As described above, the absolute position L _X is detected. The absolute position thus detected is referred to as an approximate absolute position. Since these relationships are affected by the characteristics of the linear motor 32, it is desirable to actually acquire each of the linear motors. Further, in the simulation, the pair of magnets (18a, b) or the pair of magnets (19a, b) is positioned between ¼ of the scale shown in FIG.
Note that the stored relationship can be periodically acquired and modified. This is because these relationships may change due to changes in the coil 30 over time.

On the other hand, the approximate absolute position is detected based on the amplitude W, in other words, based on the long-period component. The amplitude W is detected as a pair of (magnets 18a, 18b) and (magnet 19a) as described above. , B) is constant. Therefore, the approximate absolute position includes an error of the pitch M between the magnetic poles. Therefore, when an absolute position with higher accuracy is required, the absolute position within the pitch M between the magnetic poles is acquired and the detailed absolute position is detected.
For example, based on the approximate absolute distance L _X , the magnets (for example, the magnets 18x and y, which are the same as the magnets 19x and y) that the sensors A and B face at the present time can be known. On the other hand, based on the sensor A, the output signal of the B, located in the inter-pole pitch M, i.e., (distance from the center of the or a magnet 18z) the distance from the center of the magnet 18x M _X is found.
The value of the output signal of the sensor A is I _A, if the value of the output signal of the sensor B is I _B, as shown in FIG. 9 (b), determines the point S _M, tan [phi, the angle φ is Desired.
tanφ =-(I _B / I _A )
φ = arctan {− (I _B / I _A )}
As in the case described above, the angle φ is determined from the value of tan φ and the sign of the output signal values I _A and I _B.
Then, since one round of the circle corresponds to the pitch M between the magnetic poles, the formula M _X = φ · M / (2π)
Accordingly, the absolute position M _X from the center of the magnet 18x can be acquired.
On the other hand, the absolute position of the center of the magnet 18x is a value near L _X , but is known from the structure of the stator 12 (L _X0 ). Therefore, the absolute position L _X of the mover 24 at that time can be obtained as the sum of the distance L _X0 to the center of the magnet 18x and the distance M _X between the magnetic pole pitches M.
L _X = L _X0 + M _X
The absolute position thus obtained is referred to as a detailed absolute position. In this case, the angle φ corresponds to the combined signal of the output signals of the sensors A and B.

As described above, in the present embodiment, in the stators 12 and 14 of the linear motor 32, the magnets 18 and 19 have absolute distances between the upper end surfaces 40 and 41 and the sensors A, B, C, and D. Since it is provided in a state that changes according to the change in position, the absolute position can be detected simply by providing the movable element 24 with the sensors A, B, C, and D. That is, the absolute position can be obtained by utilizing the structure (driving principle) of the linear motor 32. As a result, it is not necessary to separately provide an absolute position detection device, and the cost of the linear motor and the machine tool driven by the linear motor can be reduced.
Further, the magnets 18a, b, c,..., The magnets 19a, b, c,... Have the same dimension X in the width direction and are provided at equal intervals Y. Compared with the case where it is provided with, it is possible to suppress a change in propulsive force due to a change in absolute position. Further, the current supplied to the coil 30 can be controlled in the same manner as in the prior art.
Furthermore, if all of the magnets 18a, b, c,... And the magnets 19a, b, c,... Have the same size and shape, the manufacturing cost of the magnets 18, 19 is reduced. This makes it possible to further reduce costs.
Further, if the output signals of the sensors A to D are detected at any position within the entire stroke, the absolute position can be detected. There is no need to memorize the previous position of the mover 24, or to count the frequency of short cycle components and store the count value. In other words, the absolute position can be detected without moving the mover 24.

As described above, in this embodiment, the magnets 18 and 19 provided on the stators 12 and 14 of the linear motor 32, the sensors A, B, C, and D provided on the mover 24, and the motor control unit. The position detecting device is constituted by 50 absolute position detecting portions. Moreover, the part which detects the absolute position of the motor control apparatus 50 is also a calculation part.
Further, the broken lines in FIGS. 5A and 5B correspond to the first straight line, and the alternate long and short dash line corresponds to the second straight line. The second straight line is also the third straight line.

In the above embodiment, the linear motor 32 is a moving coil type, but it may be a moving magnet type. In a moving magnet type linear motor, a sensor is provided on a stator, and the mover is a longitudinal member.
In addition, the position detection device can be used to detect the relative position of the movable part in a linear drive device having a rotary motor and a motion conversion mechanism such as a ball screw mechanism regardless of the linear motor 32.
Furthermore, when the position within the pitch M between the magnetic poles is obtained, it can be determined based on the output signal of one of the sensor A and the sensor B. That is, instead of obtaining tan θ from the output signal I _A of the sensor _A and the output signal I _{B of the} sensor B and obtaining the angle θ, the larger one of the output signal I _A and the output signal I _B The angle θ is obtained using the value. For example, when the angle θ is near 0 or π, 2π, in other words, when the output signal I _A is a maximum value or a value near the minimum value, and the output signal I _B is a value near 0, The angle θ is obtained from the output signal I _B. When the angle θ takes a value close to 0, π, or 2π, the output signal I _B has a larger change gradient than the output signal I _A, so that the angle θ can be accurately acquired.
I _B / W _AB = cosθ
θ = arccos (I _B / W _AB )
For the same reason, when the angle θ is in the vicinity of π / 2 and 3π / 2, the angle θ can be obtained more accurately based on the output signal I _A.
{−I _A / W _AB } = sinθ
θ = arcsin {− (I _A / W _AB )}
As described above, the values of the two output signals are compared, and the position in the pitch between the magnetic poles can be obtained based on the smaller absolute value.
Further, when obtaining the absolute position within the pitch between the magnetic poles, the actual relationship between the output signals of the sensors A and B and the absolute position is acquired and stored in advance, and based on that, the absolute position within the pitch between the magnetic poles is obtained. The position can also be acquired. Thereby, the value of θ can also be corrected.

Furthermore, the position detection device can also be applied when detecting the absolute position of the mover in a one-sided linear motor.
An embodiment in that case is shown in FIG. The single-sided linear motor shown in FIG. 10 is the same as the double-sided linear motor shown in FIGS.
In the one-sided linear motor 70, the stator 72 extends along the axial direction P, and a plurality of magnets 76 are held in a magnet holding portion (housing) 74 of the stator 72. A movable element 78 is disposed in the plurality of magnets 76 with a gap δ therebetween, and is held so as to be relatively movable. Sensors E and F (see FIG. 11) are provided on the stator 72 side of the mover 78 so as to face the inner side of the upper end surface 79 of the magnet 76. The sensors E and F are provided at positions shifted by ¼ phase in parallel with the axial direction P.

In the stator 72, as shown in FIG. 11A, the plurality of magnets 76 are provided in a state where the position of each upper end surface 79 changes monotonously with a change in absolute position.
In the present embodiment, the distance ΔH between the magnet 76 and the sensors E and F of the mover 78 is provided in a state of monotonously decreasing when the mover 78 is relatively moved in the arrow Q direction. As a result, as shown in FIG. 11B, the output signals of the sensors E and F change sinusoidally with the pitch M between the magnetic poles as the wavelength, and the amplitude W moves in the direction of the arrow Q. (As the distance ΔH becomes smaller). For this reason, the Lissajous curves of the signals of the sensors E and F are composed of multiple circles whose radii increase although illustration is omitted. Further, the relationship between the amplitude W and the absolute position L _X is as shown in FIG. 11C, and the amplitude W has a one-to-one correspondence with the absolute position.
Therefore, based on the amplitude W of the output signals of the sensors E and F, the “approximate absolute position L _X ” can be obtained. In this embodiment, the amplitude W is the output signal of the sensors E and F. Corresponds to the combined signal.
Also, as in the above embodiment, based on the amplitude W, magnets 76x, locates y, as shown in FIG. 12, the sensor when E, F of the output signals I _E, I _F, etc. It gets the angle φ from, it is possible to obtain the distance M _X from position L _X0 magnets 18x.
tanφ =-(I _F / I _E )
φ = artan {− (I _F / I _E )}
M _X = φ · M / (2π)
As a result, "detailed absolute position L _X "
L _X = L _X0 + M _X
Can be obtained as

In the above-described embodiment, the case where the present invention is applied to a one-sided linear motor has been described.
Further, the distance ΔH between the upper end surface 79 of the magnet 76 and the sensors E and F is provided so as to increase when the mover 78 is moved relative to the arrow Q, or it increases or decreases monotonically in a curved line. It can also be provided in such a state.

Furthermore, in the above-described embodiment, the case where the present invention is applied to a double-sided or single-sided linear motor has been described. You can also. An embodiment in that case is shown in FIGS.
The cylindrical linear motor 100 includes a shaft 102 and a mover 104 as stators. The shaft 102 is a longitudinal member extending in the axial direction P, and is held at both ends by a pair of support members 106 provided on the base 105 so as not to be relatively rotatable and relatively unmovable. The shaft 102 has a plurality of magnets 110 arranged in series along the axial direction P.
The mover 104 is fitted to the outside of the shaft 102 and includes a plurality of cylindrical coils 120 disposed in series along the axial direction P. The mover 104 also has engaging portions 124 and 125 that can be engaged with a pair of guide rails 122 and 123 provided in parallel with the axial direction P on the base 105, and engage with the guide rails 122 and 123. By engaging the parts 124 and 125, the parts 124 and 125 are held so as to be relatively movable in the axial direction P. A gap is provided between the inner peripheral surface of the mover 104 and the outer peripheral surface of the shaft 102.
Thus, the cylindrical linear motor 100 in this embodiment is of a moving coil type.

The mover 104 is provided with a total of eight sensors G, H, I, J, G ′, H ′, I ′, and J ′ as magnetic field detection units. These sensors are composed of Hall elements, as in the above embodiment.
As shown in FIG. 15, the four sensors G, H, I, and J are provided at the same position in the axial direction P of the mover 104 at spaced positions in the circumferential direction. Sensors G and H are provided at positions 180 degrees apart, sensors I and J are provided at positions 180 degrees apart, and sensors G and I are provided at positions 90 degrees apart. That is, the four sensors G, I, H, and J are provided at positions separated from each other by 90 °.
In addition, each of the four sensors G ′, H, I, J, and the four sensors G ′, H at positions shifted by ¼ phase in the direction parallel to the axial direction P (positions separated by 90 ° electrical angle), respectively. ', I', J 'are provided. As will be described later, since the wavelength changes with the relative movement of the mover 104, a signal having a phase shift of ¼ phase is not always output in the entire stroke, but the width of the change in wavelength is very large. Therefore, it can be considered that the phase is shifted by 1/4.

In the shaft 102, a plurality of magnets 110 are arranged in series at equal intervals inside a hollow magnet support tube 126, and a spacer 128 made of a magnetic material is provided between adjacent magnets 110. The spacer 128 can avoid repulsion between the magnets 110 and suppress a decrease in magnetic force even when the same magnetic poles face each other. The magnet support tube 126 is made of a nonmagnetic material that transmits the magnetic flux of the magnet 110.
As shown in FIGS. 16A and 16B, each of the magnets 110a, b, c,... Has a cylindrical outer surface, and both end surfaces 130 and 132 are parallel to each other and with respect to the axial direction P. It has an inclined cylindrical shape (solid cylindrical shape), and has the same shape and dimensions. That is, the axial length X, the radius R, and the inclination angles η of the end faces 130 and 132 are the same. Further, one of both end faces 130 and 132 is an N pole, and the other is an S pole.
As shown in FIG. 17A, the magnets 110 are disposed at positions that are spaced apart from each other with an equal interval Y in the axial direction P. At each position, the same magnetic poles face each other between adjacent magnets, and are rotated relative to each other around the axis P by an equal angle. For example, when the reference point K is determined in the magnet 110, the distance between the reference points K in the adjacent magnets 110 is the same. At each position, for example, when the phase of the reference point K on the outer periphery of the magnet 110c is 0, the phase of the reference point K with respect to the axis P of the magnet 110b is −α °, and the phase of the magnet 110d is + α The relative rotation is performed so that
As a result, the relative phases of the two adjacent magnets 110 are the same. Therefore, each of the spacers 128 can have the same shape and size, and are arranged in different phases.
In FIG. 17A, in order to clarify the relative phase of each of the magnets 110, the end surfaces of the magnets 110 are drawn with straight lines, and thus corners are formed. Therefore, the corners are also rounded.
Further, the plurality of magnets 110 and the plurality of spacers 128 are supported inside the magnet support tube 126 in the posture shown in FIG. 17A, but are attracted by the attractive force acting between the magnets 110 and the spacers 128. The magnet 110 and the spacer 128 can be bonded in advance with an adhesive or the like, and can be supported in that state.
Further, the relative phase is such that, in the adjacent magnet 110 and spacer 128, a convex portion is provided at a position separated from the center of one end surface, and a concave portion is provided in a portion corresponding to the convex portion on the other end surface. It can be determined by the combination.
Further, a protrusion extending in the longitudinal direction is provided on the inner peripheral surface of the magnet support cylinder 126, and a recess extending in the axial direction at a position corresponding to the protrusion on each of the outer peripheral surfaces of the magnet 110 and the spacer 128. And the relative phase can be determined by these fittings.

  As shown in FIG. 14, the sensors G, H, I, and J and the sensors G ′, H ′, I ′, and J ′ are connected to a motor control unit 132 mainly composed of a computer. The motor control unit 132 includes an execution unit 134, a storage unit 136, and an input / output unit 138, and controls the current supplied to the coil 120. Further, the absolute position of the movable element 104 with respect to the stator 102 is acquired based on the output signals of the sensors G, H, I, and J and the sensors G ′, H ′, I ′, and J ′.

The output signals of the sensors G, H, I, and J change as shown in FIG.
The output signals of these sensors G, H, I, and J become 0 at the relative position where the sensor faces the center of the magnet 110, and become the maximum or the minimum at the relative position where the sensor faces the center of the spacer 128.
On the other hand, since the plurality of magnets 110 are arranged as shown in FIG. 17A, the relative positions of the sensors G, H, I, and J with respect to the magnets 110 change in the axial direction P. In other words, since the magnets 110 are arranged at equal intervals and are relatively rotated at the positions, the magnets 110 are adjacent to each other at predetermined positions in the circumferential direction (positions of the sensors G, H, I, and J). The distance V between the edges of the magnet 110 changes in different manners with relative movement.
For example, in FIG. 17A, when the mover 104 is moved relative to the stator 102, the straight line through which the sensors G and G ′ pass is the first straight line, and the straight line through which the sensors H and H ′ pass. The second straight line, the straight line that passes through the sensors I and I ′, is the third straight line, and the straight line that passes through the sensors J and J ′ is the fourth straight line. Each of the first to fourth straight lines is parallel to the axis P and is located in a position separated from each other in a direction perpendicular to the axial direction P. The first straight line and the second straight line are at positions 180 degrees apart from each other, the third straight line and the fourth straight line are at positions 180 degrees apart from each other, and the first straight line and the third straight line are 90 degrees apart. It is in a position that is out of phase.
The sensors G and G ′ are relatively moved along the first straight line, but the distance V _G1 between the edge of the magnet 110f and the edge of the magnet 110g along the first straight line, the edge of the magnet 110h, and the magnet 110i. It is different from the distance V _G2 between the edges. Further, a distance V _I1 between the edge of the magnet 110d and the edge of the magnet 110e along the third straight line (sensors I and I ′), and a distance V _I2 between the edge of the magnet 110g and the edge of the magnet 110h Is different, the distance V _H1 between the edge of the magnet 110f and the edge of the magnet 110g along the second straight line (sensors H, H ′), and the distance V _H2 between the edge of the magnet 110h and the edge of the magnet 110i. Is different. Furthermore, the distance V _J1 between the edge of the magnet 110d and the edge of the magnet 110e along the fourth straight line (sensors J, J ′), and the distance V _J2 between the edge of the magnet 110g and the edge of the magnet 110h Is different.
Further, the distance V _I1 along the third straight line between the magnets 110d and e is larger than the distance V _J1 along the fourth straight line, but the distance along the third straight line between the magnets 110g and h. The distance V _J2 along the fourth straight line is larger than V _I2 . That is, when the sensors are relatively moved along two straight lines whose phases are 180 ° apart, if the distance along the straight line that one sensor passes is large, the distance along the straight line that the other sensor passes is small, When the distance of one of them is small, the distance of that of the other is large.
Similarly, the distance V _G1 along the first straight line between the magnets 110f and 110g is larger than the distance V _H1 along the second straight line, and the distance V _G2 along the first straight line between the magnets 110h and i. The distance V _H2 along the second straight line is larger, and there is a relationship that when one is larger, the other is smaller.
Furthermore, the distances V _G , V _H , V _I , and V _J along the first to fourth straight lines are all increased / decreased when it is assumed that the sensor has moved in the axial direction P.

On the other hand, the axial length X of all the magnets 110 is the same.
From this, the output signals of the sensors G, H, I, and J change as shown in FIG. 17 (b), and as the wavelength is relatively moved in the axial direction P, each of them is separately provided. To change. As described above, between the output signals of the sensors G and H and between the output signals of the sensors I and J, there is a relationship in which when one wavelength becomes longer, the other wavelength becomes shorter.
In FIG. 17 (c), the output signals of the sensors G and H are described in an overlapping manner, and in FIG. 17 (d), the output signals of the sensors I and J are described in an overlapping manner. As shown in FIG. 17 (c), when the mover 104 relatively moves in the direction of the arrow Q, the phases of the output signals of the sensors G and H coincide at the absolute positions L ₀ , L ₂ and L ₄ , The phase difference becomes maximum at the absolute positions L ₁ and L ₃ . At the absolute position L ₁ , the output signal of the sensor G advances, and at the absolute position L ₃ , the output signal of the sensor H advances. As shown in FIG. 17D, the phases of the output signals of the sensors I and J coincide at the absolute positions L ₁ and L ₃ , and the phase difference becomes maximum at the absolute positions L ₀ , L ₂ and L ₄ . It can be seen that the output signal of the sensor I advances at the absolute positions L ₀ and L ₄ , and the sensor J advances at the absolute position L ₂ .
As described above, since the wavelengths of the output signal of the sensor G and the output signal of the sensor H change with the relative movement of the movable element 104, the output signal of the sensor G advances or delays with respect to the output signal of the sensor H. These phase differences change sinusoidally. The same applies to the output signals of the sensors I and J, but the phase difference changes with a ¼ phase shift.

In FIG. 17B, only changes in the output signals of the sensors G, H, I, and J are shown. However, the sensors G ′, H ′, I ′, and J ′ each have a ¼ phase shift. The output signals of the sensors G and G ′, the output signals of the sensors H and H ′, the output signals of the sensors I and I ′, and the output signals of the sensors J and J ′ obtained by the simulation are output. 18 (a) to (d).
19A to 19D show the output signals of the sensors G and G ′, the output signals of the sensors H and H ′, the output signals of the sensors I and I ′, and the output signals of the sensors J and J ′. Each Lissajous curve is shown. As shown in FIGS. 19A to 19D, the Lissajous curve is substantially a circle as described above. Since the output signal of the sensor G and the output signal of the sensor G ′ have the same period (wavelength) and amplitude, and are out of phase by ¼, as described above, the Lissajous curve is a circle. is there. Similarly, the Lissajous curves are also circular for the output signals of the sensors H and H ′, the output signals of the sensors I and I ′, and the output signals of the sensors J and J ′.

FIGS. 20 (a) and 20 (b) correspond to FIGS. 17 (c) and 17 (d), respectively, in which the output signals of sensors G and H and the output signals of sensors I and J are overlaid. It is. The phase difference (also referred to as angle difference) actually increases or decreases and changes finely. In FIGS. 20 (a) and 20 (b), the phase shift In order to clarify the state, the phase difference is described larger than the actual phase difference.
Then, the phase difference between the output signals of the sensors G and H and the phase difference between the output signals of the sensors I and J change as shown in FIG. That is, the phase difference between the sensors G and H changes sinusoidally as the relative position of the mover 104 changes as indicated by the solid line, and the phase difference between the sensors I and J changes as indicated by the broken line. It changes with a phase shift of 1/4.
The Lissajous curve of the signal representing the phase difference between the output signals of the sensors G and H and the signal representing the phase difference between the output signals of the sensors I and J represented by broken lines are shown in FIG. It becomes a circle with one round (2π).
As shown in FIG. 24, if the angle θ when the total stroke is 2π is obtained from the phase difference Δα _sin of the output signals of the sensors G and H and the phase difference Δα _cos of the output signals of the sensors I and J. The approximate absolute position can be obtained from the angle θ.
For example, when the phase differences of sensors G and H and sensors I and J are Δα _sin and Δα _cos , respectively,
tanθ = − (Δα _sin / Δα _cos )
θ = arctan {− (Δα _sin / Δα _cos )}
Can be obtained according to the formula L _X = θ · L / (2π)
Accordingly, the “approximate absolute position L _X ” can be acquired. Thus, the phase difference pair and the absolute position correspond one-to-one, and the phase difference pair (in this embodiment, the signal representing the angle θ obtained from the two phase differences corresponds to the combined signal). )), It can be detected as an approximate absolute position.
This is shown in the graph of FIG.
In the present embodiment, the relationship between the phase difference between the output signals of the sensors G and H and the phase difference between the output signals of the sensors I and J and the absolute position shown in FIG. The “approximate absolute position” is acquired from the actually acquired set of phase differences and the stored relationship.
The simulation was performed using the finite element method as in the above-described embodiment.

Further, when acquiring a detailed absolute position, the magnet 110 is specified based on the approximate absolute position, as in the above-described embodiment. Then, with respect to the specified magnet, the position within one pitch is acquired based on the output signals of the pair of sensors G and G ′, and the detailed absolute position is acquired. In the state facing the specified magnet 110, the output signals of the pair of sensors G and G ′ have the same period (wavelength) and amplitude, and are shifted by ¼ phase. Similarly, the position within the pitch between the magnetic poles can be detected. Similarly, it can be acquired based on a set of output signals from the sensors H and H ′, the sensors I and I ′, and the sensors J and J ′.
As described above, the absolute position of the cylindrical linear motor can be detected while avoiding an increase in cost.
In the present embodiment, a magnet 110 provided on the stator, sensors G, H, I, J, G ′, H ′, I ′, J ′, and a portion for detecting the absolute position of the motor control unit 132, The position detection device is configured by the above.

In the above embodiment, the magnet 110 is a solid cylindrical member and is supported inside the hollow cylindrical magnet support portion 126. However, the magnet is a solid cylindrical member and is solid. It can also be made to be supported on the outer peripheral side of the cylindrical support bar. In that case, an engaging protrusion extending in the longitudinal direction is provided on the outer peripheral surface of the support rod, and an engaging recess is provided in a predetermined phase on the inner peripheral surface of the magnet 110 and the spacer 128. Thus, the relative phase can be determined.
Further, the magnet may be arranged such that the outer peripheral side is an N pole or S pole and the inner peripheral side is an S pole or N pole, which are alternately arranged.
Furthermore, a longitudinal member can also be comprised by connecting a some magnet, without providing a supporting member.
Further, the guide rails 122 and 123 and the engaging portions 124 and 125 for holding the mover 104 are not essential. The mover 104 can be held directly on the shaft 102 via a bearing or the like at a position away from the coil 120.

Next, the case where the cylindrical linear motor 100 in the above embodiment is used as a drive source for moving the mounting head in the electronic circuit component mounting machine will be briefly described.
25 and 26, the electronic circuit component mounting machine receives the electronic circuit component from the component supply device 300 that supplies the electronic circuit component, the substrate holding device 302 that holds the circuit board 301, and the circuit board 301. A mounting head 306 to be mounted on 301, a relative movement device 308 for relatively moving the component supply device 300, the substrate holding device 302 and the mounting head 306, and at least the substrate holding device 302, the mounting head 306 and the relative movement device 308 are controlled. And a control device 310 (including a motor control unit 132). The component supply device 300 and the like are provided on a bed 312 provided with a fixed position. The bed 312 constitutes the main body of the electronic circuit component mounting machine. In addition, the electronic circuit component mounting machine includes a mark imaging device that images a reference mark provided on the circuit board 304 and a component imaging device that images the electronic circuit component held by the mounting head 306.

  The relative movement device 308 moves the mounting head 306 in the X-axis direction and the Y-axis direction, which are two directions orthogonal to each other in a horizontal plane that is parallel to the component mounting surface of the circuit board 301 held by the board holding device 302. Mounting head horizontal direction moving device 316 as a mounting head parallel direction moving device to be moved, and mounting as a mounting head orthogonal direction moving device for moving the mounting head 306 in the vertical direction (Z-axis direction) perpendicular to the two directions. A head lifting device 318. The relative movement device 308 moves the mounting head 306 to the component supply device 300 provided with a fixed position, receives the electronic circuit component from the component supply device 300, moves the mounting head 306 to the substrate holding device 302, and holds the substrate. An electronic circuit component is mounted on the circuit board 301 held by the device 302.

The substrate holding device 302 is, for example, a device that supports the circuit board 301 carried in by the substrate transfer device 320 from below and clamps the edge. The mounting head horizontal direction moving device 316 includes an X-axis moving device 322 that moves the mounting head 306 in the X-axis direction, and a Y-axis moving device 324 that moves the mounting head 306 in the Y-axis direction. For example, it is used as a drive source for the X-axis moving device 322 and the Y-axis moving device 324, and moves the X-axis moving member 326 and the Y-axis moving member 328 in the X-axis direction and the Y-axis direction, respectively. The X-axis moving device 322 of the electronic circuit component mounting machine includes a pair of linear motors 100 as shown in FIG. 25, and the Y-axis moving device 324 includes one linear motor 100 as shown in FIG. The electronic circuit component mounting machine also includes a head rotating device that rotates the electronic circuit component held by the component holder 330 by rotating the mounting head 306 about its axis. The electronic circuit component is mounted on the circuit board 301 by the mounting device including the mounting head 306, the relative movement device 308, and the rotating device.
A supply current to the coils 120 (see FIG. 14) of each of the movers 104 of the pair of linear motors 100 included in the X-axis moving device 322 and the linear motor 100 included in the Y-axis moving device 324 is detected by the control device 310. Control is based on absolute positions in the X and Y directions. Note that the supply current to the coil 120 of the mover 104 of the pair of linear motors 100 included in the X-axis moving device 322 is controlled synchronously. Further, it is not always necessary to provide the absolute position detection device in both of the pair of linear motors 100, and it may be provided in either one.

In FIGS. 25 and 26, the case where the cylindrical linear motor 100 is used as a drive source of a moving device that moves the mounting head 306 of the electronic circuit component mounting machine has been described. The single-sided linear motor 70 can be used similarly.
In addition, the linear motor in each of the above embodiments can be used as a drive source used for raising and lowering the mounting head, and also used for transporting boards, pulling out trays, and raising and lowering magazines in electronic circuit component mounting machines. It can also be used as a driving source that is used, or it can be used as a driving valve for a carrier that generally conveys articles.

  While various aspects have been described above, the present invention can be practiced in various modifications and improvements based on the knowledge of those skilled in the art, in addition to the aspects described above.

It is front sectional drawing of the linear motor provided with the position detection apparatus which is one Example of this invention. It is a perspective view of the linear motor. It is a figure which shows notionally the periphery of the motor control part of the said linear motor. It is a perspective view of the stator of the linear motor. (a), (b) It is a figure which shows notionally the arrangement | positioning of the magnet provided in the said stator. (c), (d) It is a figure which shows the change of the output signal of a sensor accompanying the movement of a needle | mover. (e), (f) It is a figure which shows the change of the amplitude of the output signal of a sensor accompanying the movement of a needle | mover. It is a figure which shows the output signal of the sensor accompanying the movement of the needle | mover obtained by simulation. (a) It is a figure which shows the Lissajous curve calculated | required from the output signal of the sensors A and B obtained by simulation. (b) It is a figure which shows the Lissajous curve calculated | required from the output signal of the sensors C and D obtained by simulation. (a) It is a figure which shows the change of the amplitude of the output signal of sensors A and B obtained by simulation, and the change of the amplitude of the output signal of sensors C and D. (b) It is a figure which shows the relationship between the synthetic | combination signal which combined the above-mentioned two amplitude, and an absolute position. (a) It is a figure for demonstrating the principle in the case of calculating | requiring angle (theta) from the amplitude of the output signal of sensors A and B, and the amplitude of the output signal of sensors C and D, and calculating | requiring an absolute position. (b) It is a figure for demonstrating the principle in the case of calculating | requiring angle (phi) from the output signal of sensor A, and the output signal of sensor B, and calculating | requiring the position in the pitch between magnetic poles. It is a front view which shows the linear motor provided with the position detection apparatus which is another one Example of this invention. (a) It is a figure which represents notionally the arrangement | positioning of the magnet provided in the stator of the said linear motor. (b) It is a figure which shows the change of the output signal of sensors A and B. FIG. (c) It is a figure which shows the change of the amplitude of the output signal of sensors A and B. FIG. It is a figure which shows the principle in the case of calculating | requiring an absolute position from the amplitude of the output signal of sensors A and B. It is front sectional drawing of the linear motor provided with the position detection apparatus which is another one Example of this invention. It is a side view (partial sectional view) of the linear motor. It is AA cross section (part) of FIG. (a) It is a perspective view of a magnet. (b) It is a side view of a magnet. (a) It is a figure which shows notionally the state of arrangement | positioning of the magnet in the stator of the said linear motor. (b) It is a figure which shows the change of the output signal of a sensor accompanying the movement of a needle | mover. (c) A diagram in which the output signals of sensors G and H are overwritten. (d) A diagram in which the output signals of sensors I and J are overwritten. It is a figure which shows the change of the output signal of a sensor accompanying the movement of the needle | mover obtained by simulation. (a) It is a figure which shows the Lissajous curve calculated | required from the output signal of sensors G and G 'obtained by simulation. (b) It is a figure which shows the Lissajous curve calculated | required from the output signal of the sensors H and H 'obtained by simulation. (c) It is a figure which shows the Lissajous curve calculated | required from the output signal of sensors I and I 'obtained by simulation. (d) It is a figure which shows the Lissajous curve calculated | required from the output signal of the sensors J and J 'obtained by simulation. (a) It is the figure which accumulated the output signal of sensors G and H obtained by simulation. (b) It is the figure which piled up the output signal of sensors I and J obtained by simulation. It is a figure which shows the phase difference (sin) of the output signal of sensors G and H, and the phase difference (cos) of the output signals of sensors I and J. It is a Lissajous curve calculated | required from the signal showing the two phase differences of FIG. It is a figure showing the relationship between the synthetic | combination vibration of the signal showing the two phase differences of FIG. 21, and an absolute position. It is a figure showing the principle which an absolute position can be acquired from the signal showing the two phase differences of FIG. It is a top view of the electronic circuit component mounting machine with which the said linear motor was mounted. It is a front view of the Y-axis movement apparatus of the said electronic circuit component mounting machine.

Explanation of symbols

  12, 14: Stator 18, 19: Magnet 24: Mover 30: Coil 32: Double-sided linear motor 40, 41: Upper end surface 50: Motor controller 70: One-sided linear motor 72: Stator 76: Magnet 78: Mover 100: Cylindrical linear motor 102: Stator 104: Mover 110: Magnet 128: Spacer 132: Motor control unit Sensors A, B, C, D, E, F, G, H, I, J, G ′ , H ′, I ′, J ′

Claims (8)

(i) a plurality of magnets, comprising a longitudinal member extending in the axial direction, and (ii) has a plurality of magnetic field detecting portion, the elongate member and movable relative to said axis detection member, said plurality A position detection device that detects a relative position of the detection member in the axial direction with respect to the longitudinal member based on an output signal of the magnetic field detection unit;
A pair of the longitudinal members are provided in parallel to each other,
At least one magnetic field detector is provided at a position facing each of the pair of longitudinal members,
Each of the plurality of magnets has the same length in the axial direction. In each of the longitudinal members, the longitudinal member and the detection member are arranged at equal intervals along the axial direction. Assuming the relative movement, the distance in the direction orthogonal to the axial direction between each magnetic field detection unit is different from each other in phase but changes at the same wavelength. , the position detecting device combined signal of the plurality of magnetic field detecting portion of the output signal, characterized in that arranged in a state that changes in accordance with the relative position and the one-to-one. (i) a longitudinal member having a plurality of magnets and extending in the axial direction; and (ii) a plurality of magnetic field detectors, the longitudinal member and a detection member relatively movable in the axial direction. A position detection device that detects a relative position of the detection member in the axial direction with respect to the longitudinal member based on an output signal of the magnetic field detection unit;
Each of the plurality of magnets is a rod-shaped magnet extending in the longitudinal direction, and the dimensions perpendicular to the longitudinal direction are the same as each other, and each of the plurality of magnets has the longitudinal direction orthogonal to the axial direction. And assuming that the longitudinal member and the detection member are moved relative to each other at regular intervals along the axial direction, the one end in the longitudinal direction and the plurality of the plurality of the longitudinal members and the plurality of detection members are moved along with the relative movement . The distance between the magnetic field detection unit is changed , and the combined signal of the output signals of the plurality of magnetic field detection units is arranged in a state of changing in a one-to-one correspondence with the relative position. Position detector. (i) a longitudinal member that includes a plurality of magnets and extends in the axial direction; and (ii) a magnetic field detection unit that includes the longitudinal member and a detection member that is relatively movable in the axial direction. A position detection device that detects a relative position of the detection member in the axial direction with respect to the longitudinal member based on output signals of two magnetic field detection units;
Each of the plurality of magnets is a rod-shaped magnet extending in the longitudinal direction, and the dimensions perpendicular to the longitudinal direction are the same as each other, and each of the plurality of magnets has the longitudinal direction orthogonal to the axial direction. in a posture that, at equal intervals along the axial direction, and, when said the longitudinal member and the detection member is assumed that moving the relative said longitudinal end and the one with its relative movement Position detection characterized in that the distance between the magnetic field detection unit and the output signal of the one magnetic field detection unit is changed in a one-to-one relationship with the relative position. apparatus. (i) a longitudinal member having a plurality of magnets and extending in the axial direction; and (ii) a plurality of magnetic field detectors, the longitudinal member and a detection member relatively movable in the axial direction. A position detection device that detects a relative position of the detection member in the axial direction with respect to the longitudinal member based on an output signal of the magnetic field detection unit;
Each of the plurality of magnets has a shape in which an outer peripheral surface is a cylindrical surface, both end surfaces are parallel to each other, and inclined with respect to a center line of the cylinder having the cylindrical surface , and the shape and The dimensions are the same in each of the plurality of magnets;
Each of the plurality of magnets is equidistant from the longitudinal member along the axial direction, the centerline is parallel to the axial direction, and the relative rotational phase around the axial line is equiangular in the axial direction. Assuming that the longitudinal member and the detection member are moved relative to each other in series in a changing state, the combined signal of the output signals of the plurality of magnetic field detectors with the relative movement Is disposed in a state of changing in a one-to-one correspondence with the relative position . (i) a longitudinal member that includes a plurality of magnets and extends in the axial direction; and (ii) a magnetic field detection unit that includes the longitudinal member and a detection member that is relatively movable in the axial direction. A position detection device that detects a relative position of the detection member in the axial direction with respect to the longitudinal member based on output signals of two magnetic field detection units;
Each of the plurality of magnets has a shape in which an outer peripheral surface is a cylindrical surface, both end surfaces are parallel to each other, and inclined with respect to a center line of the cylinder having the cylindrical surface , and the shape and The dimensions are the same in each of the plurality of magnets;
Each of the plurality of magnets is equidistant from the longitudinal member along the axial direction, the centerline is parallel to the axial direction, and the relative rotational phase around the axial line is equiangular in the axial direction. Assuming that the longitudinal member and the detection member are moved relative to each other in a state where the longitudinal member and the detection member are moved relative to each other, the output signal of the one magnetic field detection unit is associated with the relative movement. A position detecting device, wherein the position detecting device is arranged so as to change in a one-to-one relationship with a relative position . (i) a longitudinal member having a plurality of magnets and extending in the axial direction; and (ii) a plurality of magnetic field detectors, the longitudinal member and a detection member relatively movable in the axial direction. A position detection device that detects a relative position of the detection member in the axial direction with respect to the longitudinal member based on an output signal of the magnetic field detection unit;
Each of the plurality of magnetic field detection units is provided on the detection member in a direction intersecting the axial direction,
When it is assumed that each of the plurality of magnets has the same length in the axial direction, is equally spaced along the axial direction, and the longitudinal member and the detection member are moved relative to each other. In addition, the relative positional relationship in the direction parallel to the axial direction between each of the plurality of magnetic field detection units changes with the relative movement, respectively, and the combined signal of the output signals of the plurality of magnetic field detection units is It is arranged in a state of changing in a one-to-one correspondence with the relative position,
The position detection device includes a calculation unit that calculates the relative position between the longitudinal member and the detection member based on a combined signal of output signals from the plurality of magnetic field detection units. A first straight line and a second straight line that are spaced apart from each other in a direction orthogonal to the axial direction and that are parallel to the axial direction are defined with respect to the longitudinal member, and the longitudinal member and the magnetic field detection section When it is assumed that the relative movement is performed along the straight line and the second straight line, at least one of the change in the amplitude and the wavelength of the output signal of the magnetic field detection unit accompanying the relative movement is relatively moved along the first straight line. The position detection device according to any one of claims 4 to 6 , wherein the plurality of magnets are disposed in a state different from each other in a case where the plurality of magnets are moved relative to each other along the second straight line. The detection member is an armature provided with a coil, and is opposed to the longitudinal member with a gap in a direction orthogonal to the axial direction, and is disposed so as to be relatively movable with respect to the longitudinal member in the axial direction. is configured the linear motor by said those armature longitudinal member, according to claim 1 said position detecting device is for detecting the relative position in the axial direction between the longitudinal member and the armature in the linear motor The position detecting device according to any one of 7 to 7 .

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