JP6494148B2 - Magnetizing apparatus and manufacturing method of magnet for magnetic encoder - Google Patents

Description

  The present invention relates to a magnetizing apparatus and a manufacturing method for a magnet for a magnetic encoder.

  Conventionally, as a method for magnetizing a multipolar magnet for a magnetic rotary encoder, a method using a multipolar magnetized yoke is known.

  FIG. 10 shows an example of such a multipole magnetized yoke. This multipole magnetized yoke 110 is for magnetizing a total of 8 poles, N poles and S poles, on the circumference of the annular magnetic member 2 at an equal pitch. Eight magnetized projecting pieces 110a are formed on the base 110b. Around the surface. A coil for generating a magnetic field from each of the magnetized protrusions 110a is appropriately wound around the multipolar magnetized yoke 110 (not shown). As a magnetization process, the magnetic member 2 is positioned with respect to the multipolar magnetized yoke 110 and then an electric current is supplied to the coil, so that eight magnetic poles are simultaneously magnetized on the magnetic member 2.

  Also, as a different magnetization method from the above, the following Patent Documents 1 and 2 generate a magnetic field in the forward and reverse directions alternately from a magnetizing yoke that locally magnetizes the annular magnetic member, A rotary magnetizing method is described in which N and S poles are alternately formed on a magnetic member by rotating the magnetic member relative to the magnetizing yoke.

Japanese Patent No. 4018313 JP 2002-164213 A

  By the way, the magnetizing method using the multi-pole magnetized yoke as described above is suitable for mass production. However, the arrangement of the magnetized projecting pieces in the multi-pole magnetized yoke and the multi-polar magnet magnetized thereby. Since the correspondence with the arrangement of N poles and S poles is fixed, if you want to obtain a variety of multipole magnets with different arrangements of N poles and S poles, usually multipolar magnetization for each type It is necessary to prepare the yoke.

  In addition, in the rotary magnetizing methods described in Patent Documents 1 and 2, no method has been proposed for magnetizing a magnetic member with a desired magnetizing pattern.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to allow a magnetic member to be magnetized with a desired magnetization pattern in a rotary magnetizing apparatus and a manufacturing method for magnetizing a magnet for a magnetic encoder.

  A magnetizing apparatus for a magnet for a magnetic encoder according to the present invention includes a magnetic member having a predetermined length while alternately generating a magnetic field in a normal direction and a reverse direction in a gap of a magnetized yoke fixedly held. In a magnetizing apparatus for a magnet for a magnetic encoder in which a magnetized region in the forward and reverse directions is alternately formed in the magnetic member by moving on a path set through the gap, the magnetization A power supply unit that supplies power to a coil wound around a yoke, and magnetizing pattern information in which the sizes of a plurality of magnetized regions in the forward and reverse directions are freely specified for the magnetic member are received. In the magnetization pattern information, based on the area setting unit, the position information generation unit that outputs the position information of the magnetic member that is moved on the path, and the position information that the position information generation unit outputs. Corresponds to the magnetized area specified for placement Each site that magnetic members, to receive a magnetic field of the corresponding forward or reverse direction, characterized by comprising a control unit for controlling the power supply unit.

  The control unit, for each magnetization region designated in the magnetization pattern information, based on the width of the magnetization region designated in the magnetization pattern information, You may make it control at least one of intensity | strength.

  Alternatively, the power supply unit supplies current pulses in the forward and reverse directions, and the control unit includes the magnetization pattern information in the magnetization pattern information for each magnetization region designated in the magnetization pattern information. The number of times the current pulse is supplied may be controlled based on the width of the magnetized region designated for the position.

  The magnetization pattern information may specify a magnetization division, a start point, and an end point in each of the magnetization regions in the forward direction or the reverse direction.

  The area setting unit may receive and register the magnetization pattern information from an external device through a medium. At this time, the region setting unit may register a plurality of magnetization pattern information, and may select any one of the plurality of magnetization patterns via the external device.

  The magnetic member may have an annular shape having a predetermined circumference, and the movement on the path may be a rotational movement in a state where the central axis of the magnetic member is fixed.

  The method for manufacturing a magnet for a magnetic encoder according to the present invention includes a magnetic member having a predetermined length while alternately generating a magnetic field in the forward and reverse directions in a gap of a magnetized yoke fixedly held. In the method of manufacturing a magnet for a magnetic encoder, in which a magnetized region in the normal and reverse directions is alternately formed in the magnetic member by moving on a path set through the gap, the magnetic member On the other hand, it receives in advance the magnetization pattern information in which the sizes of the plurality of magnetization areas in the forward and reverse directions are freely arranged, and determines the position of the magnetic member being moved on the path in real time. Based on the determined position information, each of the magnetic member portions corresponding to the magnetized region designated for placement in the magnetized pattern information receives a corresponding forward or reverse magnetic field. Magnetized yoke And wherein the generating a magnetic field in the gap portion.

  In the present invention, it is configured to receive magnetization pattern information in which a desired magnetization region is designated and magnetize the magnetic member based on the information. That is, since the magnetization pattern for the magnetic member is programmable, it is possible to change the width of each of the magnetized areas and the equal pitch magnetized by freely specifying the pitch without changing the device configuration by replacing parts or the like. Magnetization with unequal pitches specified freely is possible. Therefore, it is possible to cope with different types of magnetization patterns with the same device. In addition, in the configuration in which the non-magnetized region can be specified in addition to the magnetized regions in the forward and reverse directions by the magnetizing pattern information, a magnet that outputs a desired waveform as the detection signal of the magnetic sensor can be obtained.

1 is a schematic plan view of a magnetizing apparatus exemplified as a basic embodiment of the present invention. FIG. 2A is a partial sectional view of the magnetizing apparatus shown in FIG. 1, and FIG. 2B is a perspective view of an end portion of the magnetizing yoke. (A) is a table | surface which shows an example of the magnetization pattern information, (b) is a top view which shows the magnetization area | region formed based on the information. (A)-(c) is a top view which shows the other example of the magnet magnetized in the procedure similar to the case of Fig.3 (a), (b). (A) is a partial side view of the magnetic encoder, (b) is a graph showing a time change of a detection signal of the magnetic sensor, and (c) is a graph obtained by digitizing the detection signal of the magnetic sensor. It is a schematic plan view of the magnetizing apparatus illustrated as a more desirable embodiment. (A) is a table | surface which shows an example of the magnetization pattern information, (b) is a top view which shows the magnetization area | region formed based on the information. (A) is a table | surface which shows the other example of the magnetization pattern information, (b), (c) is a top view which shows the magnetization area | region formed in a different aspect based on the information, respectively. (A) is a partial side view of a magnetic encoder composed of magnets magnetized by the magnetizing device shown in FIG. 5, (b) is a graph showing a time change of a detection signal of the magnetic sensor, and (c) is magnetic. It is the graph which digitized the detection signal of the sensor. (A) is a partial side view of a magnetizing device in which both ends of the magnetizing yoke are arranged on the surface side of the magnetic member, and (b) is an end perspective view of the magnetizing yoke constituting the magnetizing device. is there. It is a perspective view which shows the shape of the conventional multipolar magnetizing yoke.

  The magnetizing apparatus according to the present invention allows a magnetic member having a predetermined length to pass through the gap while generating a magnetic field in the forward and reverse directions alternately in the gap of the magnetized yoke that is fixedly held. This is a magnetizing apparatus for a magnet for a magnetic encoder, in which magnetized regions in the forward and reverse directions are alternately formed on a magnetic member by moving on a set path. Here, the length of the magnetic member is in the path direction in which the magnetic member is moved.

  As a main improvement according to the present invention, the magnetizing apparatus is configured to receive magnetizing pattern information in which a desired magnetizing area is designated and magnetize the magnetic member based on the information. That is, in the magnetizing apparatus according to the present invention, the magnetizing pattern for the magnetic member is programmable. Hereinafter, a magnet magnetizing apparatus for a magnetic rotary encoder will be described as an example of the basic embodiment.

  FIG. 1 is a schematic plan view of such a magnetizing device, FIG. 2 (a) is a partial side view of the magnetizing device, and FIG. 2 (b) is a diagram of a magnetizing yoke constituting the magnetizing device. It is an edge part perspective view. Note that FIG. 2A is different in dimensional ratio from FIG. 1 for ease of viewing.

  The magnetic member 2 to be magnetized here is an annular shape having a predetermined circumference, on one surface of a flange surface projecting outward from one end of a cylindrical metal core 2a formed of a soft magnetic metal, The hard magnetic ring 2b is fixed.

  The cylindrical cored bar 2a is made of a soft magnetic metal such as SUS430 or SPCC. However, if the shape of the magnetized yoke 11 is devised, a nonmagnetic metal such as an aluminum alloy, brass, or SUS304 may be used.

  On the other hand, the magnetic ring 2b is a resin molded product containing hard magnetic powder such as alnico, neodymium, samarium, ferrite or the like, or a sintered product of hard magnetic material. If the magnetic encoder is used in a vehicle, a magnetic encoder having a high Curie temperature and impact resistance may be adopted. The method for fixing the cylindrical cored bar 2a and the magnetic ring 2b is not particularly limited.

  As shown in the figure, the magnetizing device 1 includes a mechanical part composed of a spindle device 10 for rotating and moving the magnetic member 2 and a magnetizing yoke 11 for generating a magnetic field, a power supply unit 14 and a control unit 15. The circuit part comprised by these.

  The spindle device 10 uses, for example, a stepping motor 10a as a drive source, and transmits the power by a power transmission mechanism (not shown) provided in the device to rotate the base 10b. The stepping motor 10a incorporates an encoder (not shown) that outputs a pulse indicating speed and a pulse serving as an origin signal. A chuck 10c that holds the magnetic member 2 is provided on the base 10b. The chuck 10c is composed of a double-leaf movable piece having a shape obtained by dividing a cylinder into four equal parts, and the magnetic member 2 is held or released from the inside by moving these movable pieces in the direction of diameter expansion or contraction. It has become. The drive source is not limited to the stepping motor 10a, and any drive source can be used as long as the rotational speed can be accurately controlled and measured.

  The magnetized yoke 11 is generally C-shaped with a gap S in the middle, and is made of, for example, soft magnetic metal such as iron, permalloy, permendur, and SS400. Alternatively, a powder obtained by compacting soft magnetic powder such as Sendust may be used.

  The shape and dimensions of the gap S of the magnetized yoke 11 are appropriately set according to the cross-sectional shape of the magnetic member 2. Basically, each part of the magnetic member 2 penetrates at least the gap S without contact. And just pass through.

  The magnetizing yoke 11 is connected to the positioning means 12 at a portion opposite to the gap S, so that the magnetizing yoke 11 can be positioned with respect to the magnetic member 2 held by the spindle device 10. . The mechanism and configuration of the positioning means 12 are not particularly limited. That is, it is only necessary to adjust the position in the radial direction of the magnetic member 2 with at least one degree of freedom, but it is more preferable to adjust the position in each direction with two or three degrees of freedom. If the magnetizing yoke 11 can be freely positioned in this way, magnetic members having different sizes can be magnetized without any problem.

  A coil 13 made of a copper wire or the like is wound around the magnetized yoke 11 so as to avoid the gap S and the connecting portion with the positioning means 12. The number of turns and the number of coils 13 are not particularly limited.

  As shown in FIG. 2B, the shapes of the end surface 11a and the end surface 11b of the magnetized yoke 11 may be changed as appropriate according to requirements. For example, the end face 11a on the side facing the magnetic member 2 is formed to have a rectangular shape with a short dimension along the moving direction of the magnetic member 2, and the other end face 11b is shorter than the long side of the end face 11a. Further, it may be formed in a square shape having a dimension longer than the short side. Further, the end surface 11a on the side where the magnetized yoke 11 faces the magnetic member 2 has a shorter dimension along the moving direction of the magnetic member 2, and the other end surface 11b is longer than the long side of the end surface 11a. You may form so that it may become a rectangular shape which has a dimension.

  The power supply unit 14 supplies power to the coil 13 wound around the magnetizing yoke 11. In order to generate magnetic fields in the forward and reverse directions in the gap S of the magnetized yoke 11, at least a forward current and a reverse current are selectively supplied.

  The power supply unit 14 needs to supply a large current to the coil 13, but if such a power supply is constituted by a general DC power supply type, it is very costly, and therefore, a capacitor type power supply is often used.

  In the illustrated capacitor type power supply, the capacitor 14c is charged from the power supply circuit 14b in a state where the connection to the coil 13 is cut off by the selection switch 14a, and when the capacitor 14c is sufficiently charged, the capacitor 14b is turned on by the charge switch 14d. By switching the selection switch 14a after being cut off from the circuit 14b, a large current (current pulse) is discharged from the capacitor 14c to the coil 13 at once. The power supply unit 14 has two systems, plus and minus, and selectively supplies forward and backward current pulses. However, the number of current pulses that can be supplied per unit time has an upper limit because the charging time of the capacitor 14c is required.

  The control unit 15 includes a main control unit 15 a that controls the power supply unit 14 and a motor control unit 15 b that controls the drive source of the spindle device 10.

  The main control unit 15a includes a region setting unit 15c that receives magnetization pattern information in which a desired magnetization region is arranged and specified for the magnetic member 2, and position information of the magnetic member 2 that is moving at a constant speed on the path. And a position information generation unit 15d for determining and outputting. As a basic operation, the main control unit 15a, based on the position information output from the position information generating unit 15d, the part of the magnetic member 2 corresponding to the magnetized region designated for placement in the magnetized pattern information. The power supply unit 14 is controlled such that each receives a corresponding forward or reverse magnetic field. That is, the main control unit 15a compares the position information and the magnetization pattern information, and controls the power supply unit 14 so that a magnetic field in the forward or reverse direction based on the magnetization region corresponding to the position information is obtained.

  Magnetization pattern information is used to specify the arrangement of N and S poles in a positive or forward magnetization region, that is, when the magnetic member 2 is viewed from the front side (or from the back side). Information. Since the magnetic member 2 is assumed to be a magnet for a magnetic encoder, N poles and S poles are alternately arranged on the surface of the magnetic member 2. However, according to the present invention, not only an arrangement with an equal pitch of N poles and S poles but also an arrangement with an arbitrary unequal pitch is allowed. For this reason, the format of the magnetization pattern information is not particularly limited, but information sufficient to specify the magnetization direction, the start point, and the end point in the forward direction or the reverse direction of each magnetization region is necessary.

  The area setting unit 15c only needs to have a function of receiving magnetization pattern information via some medium. The configuration is not particularly limited. For example, magnetization pattern information created by an information terminal such as a workstation may be received by a serial cable or the like. Or you may make it comprise as a network communication apparatus and receive a magnetization pattern information from a remote place. Alternatively, it may be configured as a storage medium reader so as to read magnetization pattern information stored in a CD disk, a memory card, a USB memory, or the like.

  The region setting unit 15c registers the received magnetization pattern information in a memory (not shown). Preferably, a plurality of magnetization pattern information can be registered, and any one of them can be selected by a predetermined operation. Good.

  The position information generation unit 15d has a function of outputting position information of the magnetic member 2 on the path. As the position information, it is sufficient to be able to specify which part of the magnetic member 2 is in the gap S of the magnetized yoke 11 at each time point.

  In the case of the present embodiment, position information is generated based on the pulse of the moving speed of the magnetic member 2 and the pulse of the origin signal. In other words, the position information generation unit 15 d determines which part of the magnetic member 2 passes through the gap S of the magnetized yoke 11 based on the time from when the origin signal is obtained until the present time and the moving speed history of the magnetic member 2. It can be calculated in real time.

  In this embodiment, the magnetic member 2 is an annular body, and in this case, any part of the magnetic member 2 is considered to be equivalent, and therefore, any part may be handled as the head of the magnetic member 2. Therefore, for example, the time measurement may be started by measuring the time when the position information generating unit 15d receives the pulse of the origin signal or the time when a predetermined time has elapsed after receiving the pulse of the origin signal. At this time, the position information is determined from the reference position to the gap S of the magnetized yoke 11 at the present time, with the portion of the magnetic member 2 that has passed through the gap S of the magnetized yoke 11 at the start of timing as a reference position. You may show by the rotation angle to the site | part of the magnetic member 2 which has passed.

  The motor control unit 15b is a control circuit for the drive source of the spindle device 10. Basically, the main control unit 16a controls the drive source via the motor control unit 15b, and the motor control unit 15b is uniquely provided. A configuration for controlling the drive source is conceivable.

  In the former case, the main control unit 15a generates a control pulse for rotating the stepping motor 10a at a constant rotation speed, and the motor control unit 15b rotates the stepping motor 10a by one step each time the control pulse is received. You may make it make it. At this time, the position information generation unit 15d may count time by counting the control pulses, and calculate position information based on the time count.

  In the latter case, the motor control unit 15b independently controls the stepping motor 10a so as to have a preset rotation speed, and notifies the main control unit 15a every time the stepping motor 10a is rotated by a predetermined step. Also good. The position information generation unit 15d may count time by counting the notification signal, and calculate position information based on the time count.

  As a basic operation of the magnetizing apparatus 1, first, the magnetic member 2 is fixed to the chuck 10c by manual work or an automatic conveyance device (not shown). Thereafter, the main control unit 15a or the motor control unit 15b controls the drive source of the spindle device 10 to accelerate and rotate the magnetic member 2 to a certain rotation speed.

  When the magnetic member 2 reaches a constant rotational speed, the main control unit 15a controls the power supply to the coil 13 to execute the magnetization process. At this time, the main control unit 15a determines that the position of the magnetic member currently passing through the gap S of the magnetizing yoke 11 in the magnetizing pattern information from the position information output from the position information generating unit 15d every moment. The power source unit 14 is controlled by determining which magnetization region is included. This magnetizing process is terminated by rotating the magnetic member 2 at least once, but may be terminated after exceeding that, that is, after rotating the magnetic member 2 one or more times. By such a magnetization process, the magnetic member 2 is made into a multipolar magnet for a magnetic encoder.

  In order to allow unequal pitch magnetization on the premise that the magnetic member 2 moves at a constant speed, the generation time of the magnetic field is controlled for each magnetized region designated in the magnetizing pattern information. do it. That is, the main control unit 15a controls the generation time of the magnetic field to be longer as the magnetization area designated in the magnetization pattern information is larger, and the magnetization area designated in the magnetization pattern information becomes longer. The smaller the value is, the shorter the generation time of the magnetic field is controlled. For example, assuming that the current pulse supplied by the power supply unit 14 has a constant magnitude, the number of times of supplying the current pulse may be varied for each magnetized region designated for placement in the magnetizing pattern information.

  From the same idea, if the power supply unit 14 is configured as a general DC power supply type and supplies a constant current, current supply is performed for each magnetized region designated for placement in the magnetizing pattern information. Control the time.

  Further, as long as the power supply unit 14 can dynamically control the current, the magnitude of the current may be controlled for each magnetized region whose arrangement is specified in the magnetizing pattern information. As a result, the strength of the magnetic field changes, but when the strength of the magnetic field is high, the spread of the magnetic field in the gap S of the magnetized yoke 11 also increases. Therefore, it is considered possible to adopt an approach in which the generation time of the magnetic field is constant and the area is controlled by changing the intensity of the magnetic field.

  In this embodiment, since the magnetizing device is configured as described above, the magnetizing pattern is programmable, and without changing the device configuration by component replacement or the like for each size magnetic member, It is possible to magnetize at an equal pitch with a freely specified pitch, and to magnetize at an unequal pitch with a freely specified width of each magnetized region. For this reason, the same device can handle different types of magnets.

Below, the basic example of the magnetization process by the said magnetizing apparatus is shown.
FIG. 3A is a table showing an example of magnetization pattern information, and FIG. 3B is a plan view showing a magnetization region formed based on the information.

  In this magnetization pattern information A, as the designation of the arrangement of the magnetization areas, for each of the magnetization areas, the area number of the area, the magnetization classification of the area (N pole in the forward direction, S pole in the reverse direction), The center angle of the area (area width) is specified and related. In the present embodiment, the area number and the magnetization classification are designated in advance, and an arbitrary magnetization area can be designated for each area number. For example, the region of number 1 is designated as a north pole section and a center angle of 67.5 °, and the region of number 2 is designated as a section of south pole and a center angle of 22.5 °. This magnetized pattern is an example of an unequal pitch, and the area of number 1 is designated to be wider than the other areas. Of course, the unequal pitch is not limited to such a mode, and the number of regions and the central angle of each region are arbitrary.

  In the magnet 3 magnetized on the basis of the magnetization pattern information A, a region that is in the gap S of the magnetizing yoke 11 at the start of the magnetizing process is used as a reference point, and the region of number 1 and number Two regions and the like are formed in order. For example, the number 1 region is magnetized to the N pole and its central angle is 67.5 °, and the number 2 region is magnetized to the S pole and the center angle is 22.5 °. (Hereinafter, the region whose surface is magnetized to the N pole is simply called the N pole, and the region magnetized to the S pole is simply called the S pole).

  3A (a) to 3 (c) show other examples of magnets magnetized in the same procedure as described above.

  The magnet 3 in FIG. 3A (a) is magnetized so that N poles and S poles are alternately arranged with the same width. In the magnet 3 of FIG. 3A (b), the N pole and the S pole are magnetized so that they are alternately arranged with unequal widths. 3A (c) is magnetized so that wide N poles and narrow S poles are alternately arranged. These magnets 3 have the same magnetizing process itself, except that the arrangement designation of the magnetized area in the magnetizing pattern information A is different. That is, in the present invention, the magnet 3 corresponding to the arrangement designation can be obtained simply by designating the arrangement of the desired magnetization area in the magnetization pattern information A.

Next, the principle of operation of the magnetic encoder using the magnet magnetized as described above will be described.
FIG. 4 (a) is a partial side view of a magnetic encoder composed of magnets and magnetic sensors magnetized at unequal pitches, FIG. 4 (b) is a graph showing the time change of detection signals of the magnetic sensor, and FIG. c) is a graph obtained by digitizing the detection signal of the magnetic sensor.

  As described above, the magnetic member 2, that is, the magnet 3 here is in an annular shape, but in the figure, for simplicity, the magnetic member 2 is illustrated in a straight line instead of an annular shape. The magnetic sensor 4 is fixedly arranged with respect to the central axis of the magnet 3 so as to be a predetermined distance from the surface of the magnet 3, and the magnet 3 is arbitrarily rotated with the central axis fixed. In the figure, the magnet 3 moves in the direction of the arrow. As the magnetic sensor 4, a Hall element, an MR element, or the like can be adopted. Here, a sensor that detects a vertical component (upward in the drawing) of the strength of the magnetic field is assumed. That is, the magnetic sensor 4 outputs a detection signal in which the vertical component of the magnetic field is a positive value and the reverse component is a negative value.

  The magnetic field generated by the magnet 3 is shown as lines of magnetic force in the figure.

  The magnetic field lines penetrating each of the N poles upward are adjacent to the S poles on both sides of the N poles. Therefore, on the surface side of the magnet 3, the magnets branch to the left and right in the vicinity of the surface of the magnet 3. The magnetic field lines penetrate through the S pole of the bottom. Incidentally, the magnetic field lines are parallel to the surface of the magnet 3 in the vicinity of the boundary between the N pole and the S pole. In addition, since the N pole in the central portion is wide and the S poles are adjacent to both sides thereof, the density of the magnetic field lines is low above the place where the magnetic field lines branch left and right. On the back side of the magnet 3, the magnetic lines of force pass through the cylindrical cored bar 2a made of soft magnetic metal.

  When the magnet 3 with such a magnetic field moves relative to the magnetic sensor 4, the magnetic sensor 4 outputs a detection signal such as a graph G1 shown in FIG. The horizontal axis of the graph G1 is time, but the horizontal position and scale of the graph G1 are adjusted so that they can be compared with the side view of the magnetic member 2 in FIG. For example, the peak at the left end of the graph G1 is due to the magnetic field lines penetrating downward in the S-pole magnetized region immediately below the magnetic sensor 4 in FIG. 4A, and the other peaks are the same.

  The point where the graph G1 crosses zero is a place where the magnetic lines of force are horizontal in FIG. 4A, that is, near the boundary between the N pole and the S pole. In the north pole with a wide central portion, since the density of the magnetic field lines is low above the center, a dip occurs at the center of the corresponding peak of the graph G1.

  In a general usage mode in which the detection signal of the magnetic encoder is digitally processed to calculate the rotation speed and the like, the computer cannot directly handle the analog signal as shown in FIG. 4B, and thus needs to be digitized in advance. However, binary digitization is usually sufficient. As a simple method of digitizing binary values, for example, a threshold value on the plus side and the minus side may be applied to a series of analog values so that a portion exceeding the threshold value is set to 1 and a portion not exceeding the threshold value is set to 0. These threshold values are shown as broken lines in the figure.

  FIG. 4C is a graph when such binary digitization is applied to the detection signal shown in FIG. The horizontal position and scale of this graph G2 are also adjusted in the same manner as in FIG. The detection signal after digitization is a pulse of 1 and 0, and has lost plus and minus information, but it is still possible to know the position and spread of the peak in the graph G1 in FIG. 4B. .

  In particular, in the magnetic member 2, the N pole in the central portion is wider than the other N poles and S poles, and the computer displays a long pulse corresponding to the wide N pole and other N poles in the graph G2. A short pulse corresponding to the pole and the S pole can be distinguished. Therefore, the rotational speed and absolute rotational angle of the magnet 3 can be calculated by counting the short pulses that follow the long pulse as the position starting point. Of course, since the magnet 3 only forms one unique N pole, the rotation direction cannot be determined. However, if a plurality of unique N poles or S poles are formed such that the width is different from the others, the rotational direction can be determined.

  By the way, generally, when a magnet becomes high temperature, the magnetic force tends to decrease. For example, in the case of a ferrite magnet, the magnetic force is reduced to about 94% at 50 ° C. and about 84% at 100 ° C., assuming 20 ° C. as 100. In particular, in a neodymium magnet, once the magnetic force is reduced, the magnetic force may not be completely recovered even if the temperature returns. Therefore, it should be considered that when the magnetic encoder as described above is used in a high temperature environment for a long period of time, the magnetic force of the magnet 3 is reduced and the following problems may occur.

  That is, as shown in the graph G2 in FIG. 4B, when there is a dip at the center of the peak of the detection signal that is the starting point of the position, if the magnetic force of the magnet 3 decreases, the overall level of the detection signal also changes. Since it falls, the peak may be converted into two short pulses instead of one long pulse by binary digitization. In that case, normal processing of the computer becomes difficult.

  Therefore, in the following, a more preferable embodiment capable of providing a magnet that does not cause such a problem will be described with reference to the drawings.

  FIG. 5 is a schematic plan view of a magnetizing apparatus exemplified as a more preferred embodiment. In the figure, elements common to those in FIG.

  In order to cope with the above problem, the magnetizing apparatus 1 receives magnetizing pattern information in which non-magnetized regions are further specified in addition to the magnetized regions in the forward and reverse directions, and based on the information, the magnetic member 2 is magnetized. The non-magnetized region is basically designated at the boundary between adjacent magnetized regions.

  Specifically, in the magnetization pattern information, it is preferable that the non-magnetized region can be specified in the same format as the normal and reverse magnetized regions. In this case, all the areas are specified in the order of a positive direction magnetized area, a non-magnetized area, a reverse direction magnetized area, and a non-magnetized area. Or you may enable it to designate the arrangement | positioning of the magnetization area | region of the forward / reverse direction which included the non-magnetization area | region in each, and the ratio of the non-magnetization area | region in each of this magnetization area | region. At that time, a lower limit may be set for the ratio of the non-magnetized regions so that the non-magnetized regions are always formed at the boundary between the magnetized regions in the forward and reverse directions. In any case, the magnetization pattern information includes information sufficient to specify each magnetization segment, start point, and end point of the magnetized region and each start point and end point of the non-magnetized region. Make it.

  The non-magnetized region is formed by providing a period during which a magnetic field is not generated between the corresponding portions of the magnetic member 2 to receive a magnetic field in the forward direction and the reverse direction, respectively, in order to form a magnetized region in the forward and reverse directions. it can. The width of the non-magnetized region is determined according to the period during which no magnetic field is generated. Thus, when forming a non-magnetized area | region, it is good to demagnetize the magnetic member 2 beforehand, such as heating to the Curie temperature or more.

  The power supply unit 14 has an unwired contact 14d added to the selection switch 14a so that a period in which the magnetic field is not generated can be provided. As a result, the power supply unit 14 can selectively output forward and reverse currents and no-currents. When the power supply unit 14 is a capacitor-type power supply, an operation mode may be adopted in which no current is sandwiched between the forward current pulse and the backward current pulse, like a comb without teeth.

  The area setting unit 15c issues an error warning to magnetization pattern information in which a non-magnetized area is not specified at the boundary between the normal and reverse magnetization areas, and does not accept the magnetization pattern information. It may be.

  The main control unit 15a determines whether or not the magnetization pattern information received by the region setting unit 15c includes an arrangement designation of a non-magnetized region. If the information includes the designation of the non-magnetized region, the main control unit 15a is designated in the magnetization pattern information based on the position information output from the position information generating unit 15d. The power supply unit 14 is controlled so that each part of the magnetic member 2 corresponding to the magnetized region receives a magnetic field in the corresponding forward or reverse direction. Then, the main control unit 15a controls the power supply unit 14 so that each part of the magnetic member 2 corresponding to the non-magnetized region does not receive a magnetic field. Note that the case where the arrangement designation of the non-magnetized region is not included in the magnetization pattern information is the same as in the case of the basic embodiment.

Below, an example of the magnetization process by this magnetizing apparatus 1 is shown.
FIG. 6A is a table showing an example of magnetization pattern information, and FIG. 6B is a plan view showing a magnetization region formed on the magnetic member based on the information.

  In this magnetization pattern information A, as the region designation, for each of the magnetized region and the non-magnetized region, the region number of the region, the magnetization classification of the region (N pole in the forward direction, S pole in the reverse direction) The non-magnetization Z) designates the central angle of the region. For example, the region of number 1 is designated as the N-pole segment, the central angle of 60 °, the region of number 2 is designated as the non-magnetized segment, the central angle of 7.5 °, and the region of region number 3 Designates the division of the south pole and the central angle of 20 °.

  In the magnet 3 magnetized on the basis of the magnetization pattern information A, a region that is in the gap S of the magnetizing yoke 11 at the start of the magnetizing process is used as a reference point, and the region of number 1 and number 2 and 3 are formed. For example, the region of number 1 is magnetized to the N pole and its central angle is 60 °, and the region of region number 2 is non-magnetized and its central angle is 7.5 °. The region of number 3 is magnetized to the S pole, and its central angle is 20 °.

Hereinafter, another example of the magnetizing process by the magnetizing apparatus will be described.
FIG. 7A is a table showing another example of magnetization pattern information, and FIGS. 7B and 7C are plan views showing magnetization regions formed in different modes based on the information.

  In this magnetization pattern information A, as the area designation, for each of the magnetization areas, the area number of the area, the magnetization classification of the area (N pole in the forward direction, S pole in the reverse direction), The center angle and magnetizability are specified. Here, the magnetization rate is a ratio of a part that is actually magnetized in the region, and the remaining part is a non-magnetized region. For example, the region of number 1 is designated with an N-pole section, a center angle of 67.5 °, and a magnetization rate of 90%, and the region of number 2 is an S-pole section, a center angle of 22.5 °, 90 % Magnetization is specified.

  The magnet 3 shown in FIG. 7 (b) is magnetized based on the magnetization pattern information, and the part that was in the gap S of the magnetizing yoke 11 at the start of the magnetizing process is used as a reference point. From there, a number 1 region, a number 2 region, a number 3 region, and the like are formed. For example, the number 1 region has a central angle of 67.5 °, 90% of the leading side is magnetized to the N pole, and the remaining 10% is a non-magnetized region. The number 2 region has a central angle of 22.5 °, 90% of the leading side is magnetized to the S pole, and the remaining 10% is a non-magnetized region. Thus, if the non-magnetized region is set by the ratio, the ratio of the non-magnetized region to the magnetized region can be easily set.

  The magnet 3 shown in FIG. 7 (c) is magnetized based on the magnetization pattern information, but the formation mode of the non-magnetized region is different. That is, the area of No. 1 has a central angle of 67.5 °, 90% of the middle part is magnetized to the N pole, and 5% of the leading and trailing sides are non-magnetized areas, respectively. ing. In the region of No. 2, the central angle is 22.5 °, 90% of the middle part is magnetized to the S pole, and 5% of the leading side and the trailing side are non-magnetized regions, respectively. . The same applies to the other numbered areas.

  For the magnetization pattern shown in FIG. 7 (a), either a magnetization area forming mode as shown in FIG. 7 (b) or a magnetization area forming mode as shown in FIG. 7 (c) is adopted. May be. In short, a non-magnetized region may be formed at the boundary between the N pole and the S pole.

Next, the operation principle of the magnetic encoder using the magnet 3 magnetized as described above will be briefly described.
FIG. 8A is a partial side view of a magnetic encoder composed of a magnet and a magnetic sensor in which such a non-magnetized region is formed, and FIG. 8B is a graph showing a time change of a detection signal of the magnetic sensor. FIG. 8C is a graph obtained by digitizing the detection signal of the magnetic sensor.

  The magnet 3 has an annular shape, but for simplicity, it is described linearly without being an annular shape. The magnetic sensor 4 is the same as that shown in FIG.

  As shown in FIG. 8 (a), in this magnet 3, since there is a non-magnetized region at the boundary between the N pole and the S pole, the lines of magnetic force penetrating each N pole of the magnet 3 upward are shown in FIG. Compared to a), the magnet 3 rises from the surface of the magnet 3 and then separates to the left and right. The same applies to the magnetic field lines penetrating each of the south poles downward.

  When the magnet 3 with such a magnetic field moves relative to the magnetic sensor 4, the magnetic sensor 4 outputs a detection signal as shown in the graph G1 of FIG. The major difference from the case of FIG. 4B is that the dip at the peak corresponding to the N pole formed in the central portion of the magnet 3 has disappeared here. This is an effect due to the formation of the non-magnetized region, and there is no possibility that the above-described problems occur even when the magnetic encoder is used for a long time in a high temperature environment. Also, the fact that the magnetic field lines rise high without spreading to the left and right also means that the magnetic sensor 4 can be arranged far away from the magnet 3. This is also advantageous in preventing damage to the encoder.

  Thus, in this more desirable embodiment, it is possible to provide a magnet that can obtain a good waveform as a detection signal of the magnetic sensor.

  Throughout the above description, the structure (FIGS. 1, 2, and 5) in which the magnetic member passes through the gap of the C-shaped magnetizing yoke has been described. The idea of magnetizing a magnetic member based on the magnetized pattern information can also be applied to a magnetizing apparatus in which the shape of the magnetizing yoke and the positional relationship between the magnetizing yoke and the magnetic member are different. One example will be described below.

  FIG. 9A is a partial side view of a magnetizing device in which both ends of the magnetizing yoke are arranged on the surface side of the magnetic member, and FIG. 9B is an end of the magnetizing yoke constituting the magnetizing device. FIG. In FIG. 9A, the other elements excluding the shape of the magnetizing yoke correspond to those shown in FIGS. Also in the magnetizing apparatus 1, the magnetic member 2 can be magnetized based on the magnetizing pattern information in which a desired magnetizing area is designated.

  The magnetic member 2 may be a member obtained by fixing a hard magnetic ring 2b to a cylindrical cored bar 2a made of a soft magnetic metal. That is, the magnetic member 2 has a two-layer structure of a hard magnetic body and a soft magnetic body. In this case, it is desirable to select a soft magnetic metal as the cylindrical cored bar 2a having a high magnetic permeability. By doing so, the cylindrical cored bar 2a can effectively function as a magnetic field path, and extra magnetization outside the target magnetized region can be prevented.

  As shown in FIG. 9B, the end face 11a of the magnetizing yoke 11 facing the magnetic ring 2b has a shorter dimension along the moving direction of the magnetic member 2 and faces the cored bar. The end face 11b on the side may be formed in a rectangular shape having a dimension longer than the long side of the end face 11a.

  The magnetic member magnetized by the magnetizing apparatus of the present invention is not limited to an annular member, but may be a rectangular member. When the magnetic member 2 is a rectangular parallelepiped, a magnetizing process is executed while linearly moving the gap S of the magnetizing yoke 11 using a magnetizing device including a linear actuator that can linearly move the magnetic member 2. . With such a magnetizing device, a magnet for a linear encoder can be manufactured. When magnetizing the rectangular magnetic member 2, position information is generated based on the movement speed pulse and the origin signal pulse output from the encoder incorporated in the linear actuator, Magnetization processing is performed based on the position information. The position information may indicate the part of the magnetic member 2 that is currently passing through the gap S of the magnetized yoke 11 by the distance from the top of the magnetic member 2.

  Note that the method for generating the position information may be appropriately changed as long as the part of the magnetic member 2 passing through the gap S of the magnetizing yoke 11 can be specified during the magnetizing process. For example, a point of interest is set after the point at which the magnetic member 2 reaches a constant speed on the path, a sensor or the like is arranged there, and time measurement is started when it is detected that the magnetic member 2 has passed the point of interest. By doing so, you may specify the site | part of the magnetic member 2 which passes the space | gap part S of the magnetizing yoke 11. FIG. At this time, the position information passes through the gap S of the magnetized yoke 11 from the reference position to the current position with the position of the magnetic member 2 that has passed through the gap S of the magnetized yoke 11 at the time of starting the timing as a reference position. You may show by the rotation angle or distance to the site | part of the magnetic member 2 which is doing.

  The power supply unit 14 is not limited to a capacitor type power supply. In other words, the power supply unit 14 only needs to be able to selectively supply a forward current and a reverse current to the coil 13, omitting the capacitor 14c and the charge switch 14d, and the power supply circuit 14b to the selection switch 14a. It is good also as a structure connected directly.

  Further, the double-leaf movable piece constituting the chuck 10c is not limited to being divided into four equal parts, for example, may be divided into three equal parts, or may be divided into five equal parts or more.

DESCRIPTION OF SYMBOLS 1 Magnetization apparatus 11 Magnetization yoke 13 Coil 14 Power supply part 15 Control part 15c Area | region setting part 15d Position information generation part 2 Magnetic member 3 Magnet A Magnetization pattern information S Space | gap part

Claims (8)

A magnetic member having a predetermined length is moved along a path set through the gap while generating positive and reverse magnetic fields alternately in the gap of the fixedly held magnetized yoke. In the magnetizing apparatus for the magnetic encoder magnet, in which the magnetized regions in the forward and reverse directions are alternately formed on the magnetic member,
A power supply for supplying power to a coil wound around the magnetized yoke;
An area setting unit that receives magnetization pattern information in which the widths of the plurality of magnetization areas in the forward and reverse directions are freely specified for the magnetic member, and
A position information generation unit that outputs position information of the magnetic member moved on the path;
Based on the position information output by the position information generation unit, each of the magnetic member portions corresponding to the magnetized regions designated for placement in the magnetized pattern information is in the corresponding forward or reverse direction. A magnetizing device for a magnet for a magnetic encoder, comprising: a control unit that controls the power supply unit so as to receive a magnetic field. In claim 1,
The control unit, for each magnetized region that is designated for placement in the magnetized pattern information,
A magnetizing apparatus for a magnet for a magnetic encoder, which controls at least one of the generation time and the strength of a magnetic field based on the width of the magnetized region designated for placement in the magnetized pattern information. In claim 1,
The power supply unit supplies current pulses in the forward and reverse directions,
The control unit, for each magnetized region that is designated for placement in the magnetized pattern information,
A magnetizing apparatus for a magnet for a magnetic encoder, wherein the number of times the current pulse is supplied is controlled based on a size of the magnetized region designated for placement in the magnetized pattern information. In any one of Claims 1-3,
A magnetizing apparatus for a magnet for a magnetic encoder, wherein the magnetizing pattern information specifies a magnetizing section, a starting point, and an ending point in a normal direction or a reverse direction of each magnetizing region. In any one of Claims 1-4,
The region setting section receives and registers the magnetization pattern information from an external device through a medium, and magnetizes the magnetic encoder magnet. In claim 5,
The area setting unit can register a plurality of magnetization pattern information, and can select any one of the plurality of magnetization patterns via the external device. Magnet magnetizing device. In any one of Claims 1-6,
The magnetic member is an annular shape having a predetermined circumference, and the movement on the path is a rotational movement in a state where the central axis of the magnetic member is fixed. Encoder magnet magnetizer. A magnetic member having a predetermined length is moved along a path set through the gap while generating positive and reverse magnetic fields alternately in the gap of the fixedly held magnetized yoke. In the method of manufacturing a magnet for a magnetic encoder in which the magnetized regions in the forward and reverse directions are alternately formed on the magnetic member,
For the magnetic member, preliminarily accepting magnetization pattern information in which the widths of the plurality of magnetization regions in the forward and reverse directions are each freely arranged and designated,
Determine the position of the magnetic member being moved along the path in real time,
Based on the determined position information, each of the magnetic member portions corresponding to the magnetized region designated for placement in the magnetized pattern information is subjected to the corresponding forward or reverse magnetic field. A method for producing a magnet for a magnetic encoder, wherein a magnetic field is generated in a gap portion of a magnetic yoke.

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