JP2012078274A - Magnetic detection device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve manufacturing efficiency of a rotation sensor.SOLUTION: Magnetoresistive elements 51 are respectively mounted on a plurality of lead frames 30 of a member 70 in which the plurality of lead frames 30 are supported by a supporting member 71. For each of the lead frames 30, the magnetoresistive element 51 and the lead frame 30 are disposed in a space of a permanent magnet 20 having a U-shaped cross section. The permanent magnet 20, the lead frame 30, and the magnetoresistive element 51 are covered by mold resin for each of the lead frames 30. Then, the plurality of lead frames 30 are respectively separated from the supporting member 71 to obtain a plurality of rotation sensors.

Description

  The present invention relates to a magnetic detection device and a method for manufacturing the same, and is suitable as a magnetic detection device, for example, for a rotation sensor that detects rotation of a gear.

  Conventionally, in this type of sensor, a hollow cylindrical permanent magnet that is formed in a cylindrical shape and has one axial side as an N pole and the other axial side as an S pole, and permanent magnetic flux generated from the permanent magnet. Some include a magnetoresistive element arranged near the magnetic flux zero point (magnetic flux 0 point), which is a junction point between the magnetic flux passing through the inside of the magnet and the magnetic flux passing through the outside (see, for example, Patent Document 1).

  In this case, when the spur gear made of a magnetic material arranged on one side in the axial direction of the sensor rotates and the spur gear trough moves away from the sensor and the spur gear crest approaches the sensor, or the spur gear Using the fact that when the peak part moves away from the sensor and the valley part of the spur gear approaches the sensor, the distribution of the magnetic flux density changes, the zero magnetic flux point moves, and the magnetic flux density detected by the magnetoresistive element changes. The rotation of the spur gear is detected.

JP 54-138457 A

  In the patent document 1, the inventor mounts a magnetoresistive element on a lead frame constituting a plurality of electric wirings, and configures the sensor by putting the lead frame into a hollow portion of a permanent magnet together with the magnetoresistive element. It was investigated.

  According to this study, when a member (see FIG. 6) in which a plurality of lead frames are supported by a support member is used to manufacture a plurality of sensors, the lead frame is cut by one piece from this member, It is necessary to put in the hollow part of the permanent magnet a tape that is attached to the lead frame for one piece so that the lead frame is not disassembled into a plurality of electric wires. For this reason, there is a problem in that it takes time and effort to manufacture the sensor and the manufacturing efficiency is low.

  In view of the above points, an object of the present invention is to provide a method of manufacturing a magnetic detection device and a magnetic detection device that improve manufacturing efficiency.

In order to achieve the above object, according to the first aspect of the present invention, a first inner wall surface (in a first direction connecting the N pole and the S pole and a second direction orthogonal to the first direction) 22a, 23a) and a permanent magnet having at least a second inner wall surface (22a, 23a) facing a third direction orthogonal to the first and second directions via a space (24) A magnetic detection element (51) which is disposed in the void (24) of (20) and detects a change in the magnetic field caused by the movement of the detection target (80);
A method of manufacturing a magnetic sensing device in which the void (24) is released in the second direction,
A lead member having a plurality of lead frames (30) and a support member (71) for collectively supporting the plurality of lead frames is prepared, and the lead members out of the lead members (30) are prepared. An element mounting step (S100) for mounting each of the magnetic detection elements (51);
For each lead frame (30), the magnetic detection element (51) mounted on the lead frame is placed in the space (24) of the permanent magnet (20), and the second space where the space is released. A housing step (S130) for housing from the direction;
For each lead frame (30), a molding step (S150) for sealing the permanent magnet (20), the lead frame (30), and the magnetic detection element (51) with a molding resin;
Separating the plurality of lead frames (30) from the support member (71) to obtain a plurality of magnetic detection devices (S160).

  According to the invention, the void (24) is released in the second direction. For this reason, in the second step (S130), in a state where the plurality of lead frames (30) are supported by the support member (71), the magnetic detection element (51) and the lead frame are emptied of permanent magnets for each lead frame. It can be arranged in the location (24) from the second direction. For this reason, in the second step (S130), it is not necessary to cut one piece of the lead frame from a member formed by supporting the plurality of lead frames (30) by the support member (71). Accordingly, it is not necessary to attach the tape to the lead frame for one piece so that the lead frame is not disassembled into a plurality of electric wires. For this reason, labor can be saved in manufacturing the sensor. Therefore, the manufacturing efficiency of the magnetic detection device can be improved.

In the invention according to claim 2, the permanent magnet has the first inner wall surface (22 a) and has a first side portion (22) formed to extend in the first direction; A second side portion (23) having the second inner wall surface (23a) and extending in the first direction; and the first and second side portions (22, 23). And a connecting portion (21) for connecting between the two,
In the second step (S130), the magnetic detection element (51) and the lead frame (30) are placed in the space (24) of the permanent magnet (20) for each lead frame (30). The lead frame (30) is arranged on the connecting portion (21) in such a manner as to be arranged from the direction.

  Thereby, the position of the second direction in the lead frame can be determined by arranging the lead frame on the connecting portion (21).

  In the invention according to claim 3, the connecting portion (21) is formed so as to connect the first and second side portions (22, 23) across the first direction. It is characterized by that.

  According to a fourth aspect of the present invention, the connecting portion (21) is formed to extend in the third direction between the first and second side portions (22, 23). And

  The invention according to claim 5 is characterized in that the support member (71) supports the plurality of lead frames (30) from the first direction. The manufacturing method of the magnetic detection apparatus of description.

In invention of Claim 6, the permanent magnet of Claim 1 is comprised from the 1st, 2nd permanent magnet (22A, 23A),
One of the first and second permanent magnets constitutes one inner wall surface of the first and second inner wall surfaces (22a, 23a), and the other permanent magnet is the other inner wall surface. It is characterized by comprising.

  In the invention according to claim 7, the magnetic detection element (51) includes a magnetic flux generated from the permanent magnet (20) passing through the space (24) and outside the space (24). It is characterized by being arranged at or near the magnetic flux zero part where the passing magnetic flux is joined.

  The invention according to claim 8 is characterized in that the magnetic detection element is disposed at a portion where the center line of the third direction of the permanent magnet intersects the zero magnetic flux portion.

In the invention according to claim 9, with respect to the first inner wall surface (22a, 23a) extending in the first direction and the second direction orthogonal to the first direction, and the first inner wall surface A permanent magnet (20) having at least a second inner wall surface (22a, 23a) facing through a space (24) in a third direction orthogonal to the first and second directions. The permanent magnet (20), wherein one side of the first direction is an N pole, the other side is an S pole, and the void is released in the second direction;
A lead frame (30) disposed in the void (24);
The magnetic flux mounted on the lead frame (30) in the void (24) and passing through the void (24) out of the magnetic flux generated from the permanent magnet (20) and the outside of the void (24). A magnetic detecting element (51) for detecting a change in a magnetic field caused by a motion of a detection target, disposed at or near a magnetic flux zero portion where a magnetic flux passing through
In order to protect the permanent magnet (20), the lead frame (30), and the magnetic detection element (51), the permanent magnet (20), the lead frame (30), and the magnetic detection element (51) The covering member (10) which covers is characterized by the above-mentioned.

  In the invention described in claim 10, the permanent magnet has the first inner wall surface (22a) and has a first side portion (22) formed to extend in the first direction; A second side portion (23) having the second inner wall surface (23a) and extending in the first direction; and the first and second side portions (22, 23). And a connection part (21) for connecting the two.

  In the invention according to claim 11, the connecting portion (21) is formed so as to connect the first and second side portions (22, 23) in the first direction. It is characterized by that.

  The invention according to claim 12 is characterized in that the connecting portion (21) performs positioning in the second direction with respect to the lead frame (30).

  The invention according to claim 13 is characterized in that the connecting portion (21) is formed to extend in the third direction between the first and second side portions (22, 23). And

In invention of Claim 14, the permanent magnet of Claim 1 is comprised from the 1st, 2nd permanent magnet,
One of the first and second permanent magnets constitutes one inner wall surface of the first and second inner wall surfaces (22a, 23a), and the other permanent magnet is the other inner wall surface. It is characterized by comprising.

  In the invention according to claim 15, the zero magnetic flux portion includes a first region where a magnetic flux passing through the void (24) is generated and a second region where a magnetic flux passing outside the void (24) is generated. It is the boundary between.

  The invention according to claim 16 is characterized in that the magnetic detection element is arranged at a portion where the center line of the third direction of the permanent magnet intersects the zero magnetic flux portion.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is the upper side figure and front view of a rotation sensor in one embodiment of the present invention. It is the top view and front view in the state which excluded the plate-shaped coating | coated member among the rotation sensors of FIG. FIG. 3 is a top view and a front view of the permanent magnet alone in FIG. 2. It is the top view and front view which show typically the position of the magnetoresistive element with respect to the permanent magnet of FIG. It is a flowchart which shows the assembly process of the rotation sensor of FIG. It is a figure which shows what is comprised from the some lead frame by the member used by the assembly process of FIG. It is a figure for demonstrating the content of the assembly process of FIG. It is a figure for demonstrating the content of the assembly process of FIG. It is a figure for demonstrating the content of the assembly process of FIG. It is a figure for demonstrating the detection of rotation of the spur gear by the rotation sensor of FIG. It is a graph which shows the relationship between the sensitivity of the magnetoresistive element of FIG. 1, and a detected magnetic flux density. It is a figure which shows the electric circuit structure of the rotation detection circuit 100 for detecting rotation of a spur gear using the rotation sensor of FIG. It is the top view and front view of the permanent magnet of the 1st modification of one Embodiment of this invention. It is the upper side figure and front view of the permanent magnet of the 2nd modification of one Embodiment of this invention.

  Hereinafter, an embodiment of the rotation sensor 1 to which the magnetic detection device of the present invention is applied will be described with reference to FIGS. 1, 2, and 3. FIG. 1A is a top view of the rotation sensor 1, and FIG. 1B is a front view of the rotation sensor 1.

  The rotation sensor 1 of this embodiment is a sensor for detecting the rotation of a spur gear. Specifically, the rotation sensor 1 constitutes a mold IC. As shown in FIGS. 1A and 1B, the rotation sensor 1 includes a rectangular plate-shaped covering member 10 and the plate-shaped covering member 10. It is comprised from the terminal 11, 12, 13, 14 formed so that it may protrude.

  2A and 2B show the rotation sensor 1 excluding the plate-like covering member 10. 2A is a top view corresponding to FIG. 1A, and FIG. 2B is a front view corresponding to FIG.

  The rotation sensor 1 includes a permanent magnet 20, a lead frame 30, capacitors 40 and 41, and an MR element chip 50.

  3 (a) and 3 (b) show a single unit of the permanent magnet 20, FIG. 3 (a) is a top view, and FIG. 3 (b) is a front view.

  As shown in FIGS. 3A and 3B, the permanent magnet 20 is formed in a U-shaped cross section, and includes a plate-shaped bottom portion 21 and side portions 22 and 23. The side parts 22 and 23 are formed in a prismatic shape, and are formed so as to protrude from the upper surface 21a of the bottom part 21, respectively. That is, the permanent magnet 20 has a shape in which the side portions 22 and 23 are connected by the plate-shaped bottom portion (connecting portion) 21 in the first direction.

  The side portions 22 and 23 are each formed to extend in the first direction. The side portion 22 has an inner wall surface 22 a formed so as to be orthogonal to the upper surface 21 a of the plate-like bottom portion 21. The side portion 23 has an inner wall surface 23 a formed so as to be orthogonal to the upper surface 21 a of the plate-like bottom portion 21. The inner wall surfaces 22a and 23a are formed so as to spread in the first and second directions, respectively. The second direction is a direction orthogonal to the first direction.

  The inner wall surface 22a is arranged in the third direction with respect to the inner wall surface 23a, and the inner wall surfaces 22a and 23a are opposed to each other through the space 24 in the first direction (see FIG. 3B). Yes. The third direction is a direction orthogonal to each of the first and second directions. Thus, the inner wall surfaces 22a and 23a constitute an opening that opens from the space 24 in the second direction (see FIG. 3A). That is, the void 24 of the permanent magnet 20 is released in the second direction.

  One side of the side portion 22 in the first direction (upper side in FIG. 3B) is formed with a protruding portion 22b that protrudes toward the inner wall surface 23a in the first direction. One side of the side portion 23 in the first direction (upper side in FIG. 3B) is formed with a protruding portion 23b that protrudes toward the inner wall surface 22a in the first direction. The protrusions 22b and 23b are provided to move a position to be a zero magnetic flux portion to be described later to one side in the first direction (upper side in FIG. 3B).

  In the permanent magnet 20 of this embodiment, one side in the first direction (upper side in FIG. 3) is an N pole, and the other side in the first direction (lower side in FIG. 3) is an S pole.

  The lead frame 30 in FIG. 2 is composed of a thin metal plate member, and is disposed between the inner wall surfaces 22 a and 23 a of the permanent magnet 20. The lead frame 30 is composed of electrical wires 31, 32, 33, 34 and a rectangular support member 35. The support member 35 is disposed between the protruding portion 22 b of the side portion 22 and the protruding portion 23 b of the side portion 23. The electrical wires 31, 32, 33, and 34 are arranged on the other side (lower side in FIG. 2) in the first direction with respect to the support member 35. The other side in the first direction among the electrical wirings 31, 32, 33, 34 protrudes from the space 24 of the permanent magnet 20 to the other side in the first direction. The other side (the lower side in FIG. 3) in the first direction among the electrical wirings 31, 32, 33, and 34 constitutes the terminals 11, 12, 13, and 14 described above. Capacitors 40 and 41 are connected to the lead frame 30 to form a filter circuit. The MR element chip 50 is mounted on the support member 35 of the lead frame 30.

  The MR element chip 50 is a sensor chip in which a magnetoresistive element 51 is disposed on a silicon substrate (not shown). The position of the magnetoresistive element 51 on the silicon substrate is determined in advance. That is, the position of the magnetoresistive element 51 in the MR element chip 50 is determined in advance. The magnetoresistive element 51 constitutes a magnetic detection element that detects a magnetic field, and is an MR element that increases in resistance value as the magnetic flux density increases and decreases in resistance value as the magnetic flux density decreases.

  As shown in FIG. 4, the magnetoresistive element 51 is located in the void 24 of the permanent magnet 20. FIG. 4 schematically shows the position of the magnetoresistive element 51 with respect to the permanent magnet 20, and members other than the permanent magnet 20 and the magnetoresistive element 51 are omitted.

  The magnetoresistive element 51 is disposed at the center of the permanent magnet 20 in the third direction and at the position where the magnetic flux is zero in the open flux state. In the figure, the magnetoresistive element 51 overlaps the center line S of the permanent magnet 20 in the third direction. A thick line H in the figure indicates a portion that becomes a magnetic flux zero in an open flux state. The state of the open flux is a state in which there is no magnetic body around the permanent magnet 20 and the magnetic flux generated from the permanent magnet 20 is measured by the permanent magnet 20 alone. The magnetic flux zero point is a portion where magnetic flux A passing outside the void 24 and magnetic flux B passing inside the void 24 of the magnetic flux generated from the permanent magnet 20 are joined. That is, the magnetic flux zero point is a boundary between the first region where the magnetic flux A is generated and the second region where the magnetic flux B is generated. The MR element chip 50 and the lead frame 30 of this embodiment are connected by a plurality of metal wires 60 as shown in FIG. In the present embodiment, six metal wires 60 are used.

  Next, a specific example of assembling a plurality of rotation sensors 1 will be described as an explanation of the assembly process of the rotation sensor 1 of the present embodiment. FIG. 5 is a flowchart showing an assembly process of the rotation sensor 1.

  First, a plurality of permanent magnets 20, capacitors 40 and 41, and MR element chips 50 are prepared.

  Next, in the process of step S100 in FIG. 5 (element mounting process), as shown in FIG. 6, a member 70 in which a plurality of lead frames 30 are supported by a support member 71 is prepared. The member 70 is a lead member 70 having a support member 71 that collectively supports a plurality of lead frames 30. In the member 70 in FIG. 6, three lead frames 30 arranged in a row are supported by a support member 71 via tie bars 72a, 72b, 72c, 72d, and 72e, respectively. The support member 71 is composed of strip members 71a and 71b. The strip member 71a supports the three lead frames 30 from one side in the first direction (upper side in FIG. 6), and the strip member 71b supports the three lead frames 30 in the other side in the first direction (in FIG. 6). Support from the bottom.

  Further, MR element chips 50 (referred to as chips in the figure) and capacitors 40 and 41 are mounted for each lead frame 30 on a plurality of lead frames 30. That is, the MR element chip 50 and the capacitors 40 and 41 are mounted on the lead frame 30 for each lead frame 30. At this time, the capacitors 40 and 41 and the MR element chip 50 are bonded to the lead frame 30 with a conductive adhesive. Thereafter, in the next step S <b> 110, the conductive adhesive is cured, and the capacitors 40 and 41 and the MR element chip 50 are fixed to the lead frame 30.

  In the next step S120, the MR element chip 50 and the lead frame 30 are joined by wire bonding. FIG. 7 shows an example in which the MR element chip 50 and the lead frame 30 are joined by six metal wires 60.

  In the next step S <b> 130 (accommodating step), the lead frame 30 is mounted on the permanent magnet 20 for each lead frame 30. Specifically, the lead frame 30 is inserted into the space 24 of the permanent magnet 20 for each lead frame 30 from the second direction, and the lead is placed on the upper surface 21a of the bottom 21 of the permanent magnet 20 (see FIG. 2A). The frame 30 is disposed (see FIG. 8). That is, for each lead frame 30, the MR element chip 50 mounted on the lead frame 30 is accommodated in the space 24 of the permanent magnet 20 from the second direction in which the space 24 is released. At this time, the lead frame 30 is arranged so that the MR element chip 50 and the capacitors 40 and 41 are located on the side opposite to the upper surface 21a.

  Here, the position of the magnetoresistive element 51 with respect to the permanent magnet 20 is set to a predetermined position by adjusting the position of the permanent magnet 20 with respect to the lead frame 30 for each lead frame 30. As described above, the predetermined position is a position that is the central portion of the permanent magnet 20 in the second direction and is the magnetic flux zero point in an open flux state. Then, the lead frame 30 is bonded to the upper surface 21a of the permanent magnet 20 for each lead frame 30 with an adhesive. In the next step S140, the adhesive is cured.

In the process of the next step S150 (molding process), the plate-shaped covering member 10 is molded by molding using an epoxy resin for each lead frame 30 (see FIG. 9). That is, for each lead frame 30, the lead frame 30, the permanent magnet 20, and the magnetoresistive element 51 are sealed with epoxy resin (mold resin).
In the next step S160 (separation step), the tie bars 72a, 72b, 72c, 72d, 72e are cut for each lead frame 30. As a result, the plurality of lead frames 30 are separated from the support member 71, and the plurality of rotation sensors 1 are formed. That is, the plurality of lead frames 30 are separated from the support member 71 to obtain the plurality of rotation sensors 1.

  Next, as an operation of the rotation sensor 1 of the present embodiment, a specific example in which the rotation sensor 1 detects the rotation of the spur gear made of a magnetic material will be described with reference to FIG. FIGS. 10A and 10C show specific examples in which a spur gear 80 as a detection target is arranged on one side in the first direction (upper side in the drawing) with respect to the rotation sensor 1. FIG. 10A shows a state where the valley 81 (concave portion) of the spur gear 80 faces the rotation sensor 1.

  FIG. 10B is a graph showing the distribution of magnetic flux density (magnetic force) in the X portion (specifically, the peripheral region of the magnetoresistive element 51) in the rotation sensor 1 in FIG. Reference symbol K indicates the position of the magnetoresistive element 51. The upper end portion (see arrow D) in FIG. 10B corresponds to the end portion 25 (see FIG. 3) on one side in the first direction of the permanent magnet 20, and the left-right direction in FIG. Corresponding to the second direction in (a), the vertical direction in FIG. 10 (b) corresponds to the first direction in FIG. 10 (a), (c).

  When the valley 81 of the spur gear 80 faces the rotation sensor 1 and the depth of the valley 81 (see symbol h in FIG. 10) is sufficiently large, the magnetic flux density (magnetic force) of the X portion in the rotation sensor 1 ) Distribution is substantially the same as the state in which the spur gear 80 does not exist on one side in the first direction with respect to the rotation sensor 1. That is, when the valley portion 81 of the spur gear 80 faces the rotation sensor 1, the position where the magnetic flux is zero (see the thick line F in the figure), the magnetoresistive element 51, and the open flux state as described above. Will overlap. As a result, the magnetic flux density (magnetic force) detected by the magnetoresistive element 51 becomes zero, and the resistance value of the magnetoresistive element 51 becomes zero. Accordingly, the sensitivity of the magnetoresistive element 51 becomes zero (see G in FIG. 11). The sensitivity of the magnetoresistive element 51 is the ratio of the actual resistance value of the magnetoresistive element 51 to the maximum resistance value when the maximum resistance value of the magnetoresistive element 51 is 100% (= {(magnetoresistance Actual resistance value of element 51) / (maximum resistance value of magnetoresistive element 51)} × 100). 11 is a graph in which the vertical axis represents the sensitivity of the magnetoresistive element 51 and the horizontal axis represents the magnetic flux density (magnetic force) of the magnetoresistive element 51.

  Next, when the spur gear 80 rotates and the peak portion 82 of the spur gear 80 faces the rotation sensor 1 as shown in FIG. The distribution of density (magnetic force) is as shown in FIG. In this case, the position where the magnetic flux is zero (see the thick line F in the figure) moves from the position of the magnetoresistive element 51 (see the symbol K in FIG. 10D) to the other side in the first direction (the bottom in the figure). . For this reason, the magnetic flux density (magnetic force) detected by the magnetoresistive element 51 increases, and the resistance value of the magnetoresistive element 51 becomes a value substantially equal to the maximum value. Accordingly, the sensitivity of the magnetoresistive element 51 is about 100% (see H in FIG. 11).

  As the spur gear 80 rotates in this way and the valley portions 81 and the mountain portions 82 alternately face the rotation sensor 1, the resistance value of the magnetoresistive element 51 alternately repeats the maximum value and zero. . Therefore, by detecting such a change in the resistance value of the magnetoresistive element 51, the rotation of the spur gear 80 can be detected without depending on the rotation direction of the spur gear 80.

  10B and 10D, reference numerals a, b, c, and d are regions in which the magnetic flux is directed to the inside of the void 24, and reference numerals e and f are directed to the outer side of the void 24. It is an area. Symbol a is a region where the magnetic flux density is 60 mT to 80 mT, symbol b is a region where the magnetic flux density is 40 mT to 60 mT, symbol c is a region where the magnetic flux density is 20 mT to 40 mT, symbol d is a region where the magnetic flux density is 00 mT to 20 mT, symbol e Is a region where the magnetic flux density is 20 mT to 00 mT, and symbol f is a region where the magnetic flux density is 40 mT to 20 mT.

  Next, the rotation detection circuit 100 for the spur gear 80 using the rotation sensor 1 of the present embodiment will be described. FIG. 12 is a diagram illustrating an electric circuit configuration of the rotation detection circuit 100.

  The rotation detection circuit 100 includes a comparator 90 and resistance elements 91, 92, and 93 in addition to the rotation sensor 1 (indicated by a resistance element symbol in FIG. 12).

  The rotation sensor 1 and the resistance element 91 are connected in series between the power supply device 94 and the ground. A common connection point between the rotation sensor 1 and the resistance element 91 is connected to the inverting input terminal (−) of the comparator 90. As a result, a voltage value V− obtained by dividing the output voltage of the power supply device 94 by the resistance value of the rotation sensor 1 and the resistance value of the resistance element 91 is applied to the inverting input terminal (−) of the comparator 90.

  The resistance element 92 and the resistance element 93 are connected in series between the power supply device 94 and the ground. A common connection point between the resistance element 92 and the resistance element 93 is connected to the non-inverting input terminal (+) of the comparator 90. As a result, a voltage value V + obtained by dividing the output voltage of the power supply device 94 by the resistance value of the resistance element 92 and the resistance value of the resistance element 93 is applied to the non-inverting input terminal (+) of the comparator 90.

  In the rotation detection circuit 100 configured as described above, when the valley portion 81 of the spur gear 80 faces the rotation sensor 1, the resistance value of the magnetoresistive element 51 becomes zero. For this reason, the same voltage value as the output voltage of the power supply device 94 is given to the inverting input terminal (−) of the comparator 90 as the voltage value V−. For this reason, the voltage value V− input to the inverting input terminal (−) becomes larger than the voltage value V + input to the non-inverting input terminal (+). Thereby, the signal level of the output signal of the comparator 90 becomes a low level.

  Next, when the spur gear 80 rotates and the peak portion 82 of the spur gear 80 faces the rotation sensor 1, the resistance value of the magnetoresistive element 51 rises and is applied to the inverting input terminal (−) of the comparator 90. The input voltage value V− decreases. For this reason, the voltage value V− input to the inverting input terminal (−) is smaller than the voltage value V + input to the non-inverting input terminal (+). As a result, the signal level of the output signal of the comparator 90 becomes a high level.

  As the spur gear 80 rotates in this manner and the valley portions 81 and the mountain portions 82 alternately face the rotation sensor 1, the signal level of the output signal of the comparator 90 alternately repeats a low level and a high level. It will be. Therefore, the rotation of the spur gear 80 can be detected by detecting the signal level of the output signal of the comparator 90.

  According to this embodiment described above, the permanent magnet 20 has the inner wall surfaces 22a and 23a formed so as to spread in the first and second directions, and the inner wall surface 22a is in relation to the inner wall surface 23a. The inner wall surfaces 22a and 23a are opposed to each other through the space 24 in the first direction. The permanent magnet 20 is formed such that the space 24 opens in the second direction. Therefore, in the step S130, the MR element chip 50 and the lead frame 30 are emptied of the permanent magnet 20 for each lead frame 30 in a state where the plurality of lead frames 30 are supported by the support member 71 in the member 70 of FIG. It can be stored in the place 24 from the second direction. Therefore, when the lead frame 30 is stored in the space 24 of the permanent magnet 20, it is not necessary to cut the lead frame 30 from the member 70 by one piece. Accordingly, it is not necessary to attach the tape to the lead frame 30 for one piece so that the lead frame 30 is not disassembled. For this reason, labor can be saved in manufacturing the rotation sensor 1. Therefore, the manufacturing efficiency of the rotation sensor 1 can be improved.

  In the present embodiment, the magnetoresistive element 51 is disposed at the center portion in the third direction and at the position where the magnetic flux is zero in the open flux state. For this reason, when the valley portion 81 of the spur gear 80 faces the rotation sensor 1, the sensitivity of the magnetoresistive element 51 becomes zero. When the crest 82 of the spur gear 80 faces the rotation sensor 1, the resistance value of the magnetoresistive element 51 is about the maximum value.

  Here, when the magnetoresistive element 51 is disposed in the space 24 of the permanent magnet 20 at a position where the magnetic flux is zero in an open flux state and at the end in the third direction (for example, on the protruding portion 23b side). The magnetic flux intensity detected by the magnetoresistive element 51 when the peak portion 82 of the spur gear 80 faces the rotation sensor 1 is smaller than that in the present embodiment, and the resistance of the magnetoresistive element 51 is reduced. The value is much smaller than the maximum value.

  On the other hand, in the present embodiment, as described above, when the crest portion 82 of the spur gear 80 faces the rotation sensor 1, the sensitivity of the magnetoresistive element 51 is about the maximum value. For this reason, a change in the resistance value of the magnetoresistive element 51 between the case where the valley portion 81 of the spur gear 80 faces the rotation sensor 1 and the case where the peak portion 82 of the spur gear 80 faces the rotation sensor 1. Becomes larger. Thereby, the rotation of the spur gear 80 can be easily detected by the change in the resistance value of the magnetoresistive element 51.

  In the present embodiment, the permanent magnet 20 is formed such that the void 24 opens in the second direction. For this reason, the lead frame 30 is fitted into the space 24 of the permanent magnet 20 from the third direction, and the operator visually recognizes the position of the lead frame 30 with respect to the permanent magnet 20 while visually recognizing from the second direction. By adjusting every 30, the position of the MR element chip 50 with respect to the permanent magnet 20 is set for each lead frame 30 at a predetermined position. For this reason, the position of the magnetoresistive element 51 with respect to the permanent magnet 20 can be easily determined.

  In the present embodiment, the permanent magnet 20 is formed such that the void 24 is opened in the second direction.

  Here, when a lead frame is fitted into a hollow hollow of a cylindrical permanent magnet to constitute a rotation sensor, it is conceivable to use a positioning cylinder member to determine the position of the lead frame with respect to the permanent magnet. . In the positioning cylinder member, the positioning cylinder member determines the position of the lead frame with respect to the permanent magnet by fitting the permanent magnet into the hollow portion.

  In the present embodiment, the permanent magnet 20 is formed such that the void 24 is opened in the second direction. Therefore, the magnetoresistive element 51 with respect to the permanent magnet 20 in a state where the lead frame 30 is placed in the void 24 of the permanent magnet 20 from the third direction and the lead frame 30 is disposed on the upper surface 21a of the bottom 21 of the permanent magnet 20. Can be determined. For this reason, it is not necessary to use a positioning cylinder member in order to determine the position of the lead frame with respect to the permanent magnet.

  In the present embodiment, in the step S130, the lead frame 30 is inserted into the space 24 of the permanent magnet 20 for each lead frame 30 from the second direction, and the lead frame 30 is placed on the upper surface 21a of the bottom 21 of the permanent magnet 20. Place. For this reason, the lead frame 30 can be positioned in the second direction with respect to the permanent magnet 20. Thereby, the positioning of the magnetoresistive element 51 with respect to the permanent magnet 20 in the second direction can be performed.

(Other embodiments)
In the above-described embodiment, the example in which the U-shaped cross section in which the side portions 22 and 23 are connected by the plate-shaped bottom portion 21 is used as the permanent magnet 20 has been described. You may use the shape shown to 13 (a) and (b). In the permanent magnet 20 shown in FIGS. 13A and 13B, the bottom portion 21 connecting the side portions 22 and 23 is formed in a long plate shape extending in the second direction, and the permanent magnet 20 has the second direction. As seen from above, it is formed in an H shape. Alternatively, the bottom portion 21 is eliminated from the permanent magnets 20 shown in FIGS. 13A and 13B, and the side portions 22 and 23 shown in FIGS. 13A and 13B are used as independent first and second permanent magnets, respectively. It is also possible (see FIGS. 14A and 14B). 14A and 14B, the first and second permanent magnets are 22A and 23A. In this case, an adhesive tape or the like is used to fix the first and second permanent magnets to the lead frame. In these embodiments as well, the rotation sensor is assembled by the assembly process shown in FIG.

  FIG. 13A is a top view of the permanent magnet 20, and FIG. 13B is a front view of the permanent magnet 20. 14A is a top view of the first and second permanent magnets 22A and 23A, and FIG. 14B is a front view of the first and second permanent magnets 22A and 23A.

  In the above-described embodiment, the example in which the magnetoresistive element 51 is arranged at a position where the magnetic flux is zero in the state of the open flux has been described. The element 51 may be disposed.

  In the above-described embodiment, the example in which the magnetoresistive element 51 is disposed at the center portion in the second direction of the permanent magnet 20 has been described. If the change in the magnetic flux density detected by the magnetoresistive element 51 occurs when the peak portion 82 of the spur gear 80 faces the rotation sensor 1, the second direction of the permanent magnet 20 You may arrange | position in parts other than the center part.

  In the above embodiment, the example in which the magnetoresistive element 51 is arranged on the N pole side of the permanent magnet 20 has been described. However, the present invention is not limited thereto, and the magnetoresistive element 51 may be arranged on the S pole side of the permanent magnet 20.

  In the above embodiment, an example in which a magnetoresistive element is used as the magnetic detection element has been described.

  In the above-described embodiment, the example in which the rotation sensor 1 according to the present invention detects the rotation of the spur gear that rotationally moves has been described. However, the present invention is not limited to this, and the rotation sensor 1 according to the present invention moves linearly (linear The movement of the gears may be detected.

  In the above embodiment, an example in which the protruding portion 22b is formed on the side portion 22 and the protruding portion 23b is formed on the side portion 23 will be described, but the present invention is not limited thereto, and the protruding portions 22b and 23b are not limited to this. May not be formed.

In addition, the manufacturing method of above-described embodiment can be expressed also by the following expressions. For example,
The void 24 of the permanent magnet 20 having the first and second inner wall surfaces 22a, 23a facing each other through the void 24 over the A direction (that is, the first direction) connecting the N pole and the S pole. A method of manufacturing a magnetic detection device having a magnetic detection element 51 that is disposed within and detects a change in a magnetic field caused by the movement of a detection target 80,
The permanent magnet 20 has a C direction (that is, a second direction) perpendicular to the B direction (that is, the third direction) and the A direction in which the space 24 connects the first and second inner wall surfaces. Is formed to open,
A first step (S100) of mounting the magnetic detection elements 51 on the plurality of lead frames 30 of the member 70 formed by supporting the plurality of lead frames 30 by the support member 71;
A second step (S130) of arranging the magnetic detection element 51 and the lead frame 30 in the space 24 of the permanent magnet 20 from the C direction for each lead frame 30;
A third step (S140) of covering the permanent magnet 20, the lead frame 30, and the magnetic detection element 51 with a mold resin for each lead frame 30;
And a fourth step (S160) of obtaining a plurality of magnetic detection devices by separating the plurality of lead frames 30 from the support member 71, respectively.

As another expression,
Arranged so as to face each other through the void 24 across the first direction, one side in the A direction (that is, the first direction) is the N pole, and the other side in the A direction is the S pole. A method of manufacturing a magnetic detection device having a magnetic detection element 51 that is disposed in a space 24 between first and second permanent magnets 22A and 23A and detects a change in a magnetic field caused by the movement of a detection target 80. ,
A first step (S100) of mounting the magnetic detection elements 51 on the plurality of lead frames 30 of the member 70 formed by supporting the plurality of lead frames 30 by the support member 71;
A second step (S130) of disposing the magnetic detection element 51 and the lead frame 30 in the space 24 between the first and second permanent magnets 22A and 23A for each lead frame 30;
A third step (S140) of covering the first and second permanent magnets 22A, 23A, the lead frame 30, and the magnetic detection element 51 with a mold resin for each lead frame 30;
And a fourth step (S160) of obtaining a plurality of magnetic detection devices by separating the plurality of lead frames 30 from the support member 71, respectively.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims.

DESCRIPTION OF SYMBOLS 1 Rotation sensor 10 Plate-shaped coating | coated member 11, 12, 13, 14 Terminal 20 Permanent magnet 21 Bottom part 22, 23 Side part 22a, 23a Inner wall surface 30 Lead frame 40, 41 Capacitor 50 MR element chip 51 Magnetoresistive element 60 Metal wire 70 Member 71 Frame member 72a, 72b, 72e Tie bar 72d, 72e Tie bar 80 Spur gear 81 Valley part 82 Mountain part 90 Comparator 91, 92, 93 Resistance element 94 Power supply device 100 Rotation detection circuit

Claims (16)

A first inner wall surface (22a, 23a) extending in a first direction connecting the N pole and the S pole and a second direction orthogonal to the first direction, and the first and second directions. Are disposed in the void (24) of the permanent magnet (20) having at least the second inner wall surface (22a, 23a) facing each other through the void (24) in a third direction orthogonal to each other. A magnetic detection element (51) for detecting a change in the magnetic field caused by the movement of the object (80);
A method of manufacturing a magnetic sensing device in which the void (24) is released in the second direction,
A lead member having a plurality of lead frames (30) and a support member (71) for collectively supporting the plurality of lead frames is prepared, and the lead members out of the lead members (30) are prepared. An element mounting step (S100) for mounting each of the magnetic detection elements (51);
For each lead frame (30), the magnetic detection element (51) mounted on the lead frame is placed in the space (24) of the permanent magnet (20), and the second space where the space is released. A housing step (S130) for housing from the direction;
For each lead frame (30), a molding step (S150) for sealing the permanent magnet (20), the lead frame (30), and the magnetic detection element (51) with a molding resin;
A separation step (S160) of separating the plurality of lead frames (30) from the support member (71) to obtain a plurality of magnetic detection devices, respectively. The permanent magnet has the first inner wall surface (22a) and a first side portion (22) formed to extend in the first direction, and the second inner wall surface (23a). And a connecting portion (21) connecting between the second side portion (23) formed to extend in the first direction and the first and second side portions (22, 23). )
In the accommodating step (S130), the magnetic detection element (51) and the lead frame (30) are placed in the space (24) of the permanent magnet (20) in the second direction for each lead frame (30). The method for manufacturing a magnetic detection device according to claim 1, wherein the lead frame (30) is arranged on the connection portion (21).   The said connection part (21) is formed so that it may connect between the said 1st, 2nd side parts (22, 23) over the said 1st direction. The manufacturing method of the magnetic detection apparatus of description.   The magnetism according to claim 2, wherein the connecting portion (21) is formed to extend in the third direction between the first and second side portions (22, 23). A method for manufacturing a detection device.   The method of manufacturing a magnetic detection device according to claim 3 or 4, wherein the support member (71) supports the plurality of lead frames (30) from the first direction. The permanent magnet according to claim 1 is composed of first and second permanent magnets (22A, 23A),
One of the first and second permanent magnets constitutes one inner wall surface of the first and second inner wall surfaces (22a, 23a), and the other permanent magnet is the other inner wall surface. The method of manufacturing a magnetic detection device according to claim 1, wherein:   The magnetic detection element (51) has a magnetic flux zero where a magnetic flux passing through the space (24) and a magnetic flux passing outside the space (24) are joined out of the magnetic flux generated from the permanent magnet (20). The method of manufacturing a magnetic detection device according to claim 1, wherein the magnetic detection device is arranged at or near a site.   The method of manufacturing a magnetic detection device according to claim 7, wherein the magnetic detection element is disposed at a portion where the center line of the third direction of the permanent magnet intersects the zero magnetic flux portion. . A first inner wall surface (22a, 23a) extending in a first direction and a second direction orthogonal to the first direction, and in the first and second directions with respect to the first inner wall surface A permanent magnet (20) having at least a second inner wall surface (22a, 23a) facing through a void (24) in a third direction orthogonal to the first direction, wherein one side of the first direction is The permanent magnet (20), which is an N pole, the other side is an S pole, and the void is released in the second direction;
A lead frame (30) disposed in the void (24);
The magnetic flux mounted on the lead frame (30) in the void (24) and passing through the void (24) out of the magnetic flux generated from the permanent magnet (20) and the outside of the void (24). A magnetic detecting element (51) for detecting a change in a magnetic field caused by a motion of a detection target, disposed at or near a magnetic flux zero portion where a magnetic flux passing through
In order to protect the permanent magnet (20), the lead frame (30), and the magnetic detection element (51), the permanent magnet (20), the lead frame (30), and the magnetic detection element (51) And a covering member (10) covering the magnetic detection device.   The permanent magnet has the first inner wall surface (22a) and a first side portion (22) formed to extend in the first direction, and the second inner wall surface (23a). And a connecting portion (21) connecting between the second side portion (23) formed to extend in the first direction and the first and second side portions (22, 23). The magnetic detection device according to claim 9, further comprising:   The said connection part (21) is formed so that it may connect between the said 1st, 2nd side parts (22, 23) over the said 1st direction. The magnetic detection apparatus as described.   The magnetic detection device according to claim 11, wherein the connecting portion (21) performs positioning in the second direction with respect to the lead frame (30).   11. The magnetism according to claim 10, wherein the connecting portion (21) is formed to extend in the third direction between the first and second side portions (22, 23). Detection device. The permanent magnet according to claim 9 is composed of first and second permanent magnets,
One of the first and second permanent magnets constitutes one inner wall surface of the first and second inner wall surfaces (22a, 23a), and the other permanent magnet is the other inner wall surface. The magnetic detection device according to claim 9, comprising:   The zero magnetic flux region is a boundary between a first region where a magnetic flux passing through the void (24) is generated and a second region where a magnetic flux passing outside the void (24) is generated. The magnetic detection device according to any one of claims 9 to 14.   16. The magnetic detection element according to claim 9, wherein the magnetic detection element is disposed at a portion where a center line in the third direction of the permanent magnet intersects the magnetic flux zero portion. The magnetic detection apparatus as described.

Images