JP2006029792A - Anisotropic magnetoresistive element and turning angle detector using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turning angle detector for surely detecting the short-circuiting between adjoining terminals and realizing power saving, for an anisotropic magnetoresistive element used for turning angle detection, etc. on a steering wheel of an automobile, and to provide a turning angle detector that uses the same. <P>SOLUTION: An AMR (anisotropic magnetoresistive) element 25 is formed, by disposing a power terminal or a ground terminal next to output terminals 22F, 22H, 23F, and 23H while structuring the turning angle detector by using the AMR element 25. If adjoining terminals are short-circuited, an output signal at a ground potential or power potential is inputted into a control means 31. Thus, the short-circuiting between the adjoining terminals can be surely detected, and power saving can be realized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an anisotropic magnetoresistive element mainly used for detecting a rotation angle of a rotating body such as an automobile steering, and a rotation angle detection device using the same.

  In recent years, as the functionality of automobiles has increased, an anisotropic magnetoresistive element (hereinafter referred to as an AMR element) that detects the rotation of a magnetic field is used in a rotation angle detection device that detects the rotation angle of a steering wheel for various controls. What was there is increasing.

  Such a conventional AMR element and a rotation angle detection apparatus using the same will be described with reference to FIGS.

  FIG. 6 is a configuration diagram of a conventional AMR element. In FIG. 6, reference numeral 2 denotes a first Wheatstone bridge in which four magnetoresistive elements 1 are connected in a substantially rectangular shape, and 3 denotes the same four magnetoresistive elements 1. A second Wheatstone bridge 3 is connected in a rectangular shape, and the second Wheatstone bridge 3 is disposed in the vicinity of the first Wheatstone bridge 2 with an inclination of 45 degrees.

  The coupling points 2A, 2B, 2C and 2D where the magnetoresistive elements 1 of the Wheatstone bridge 2 are coupled to each other are connected to the ground terminal 2E, the output terminal 2F, the power supply terminal 2G and the output terminal 2H by wire bonding or the like. Yes.

  Further, from the connection points 3A, 3B, 3C, and 3D of the Wheatstone bridge 3, a ground terminal 3E, an output terminal 3F, a power supply terminal 3G, and an output terminal 3H are similarly derived.

  Furthermore, 4 is a mold part made of an insulating resin and covers the Wheatstone bridges 2 and 3 formed on the silicon wafer and a part of the various terminals 2E to 2H and 3E to 3H.

  Then, in order from the upper left side of the outer periphery of the mold part 4, the ground terminals 2E, 3E and the output terminals 3F and 2F extend from the mold part 4 side by side at a predetermined interval, and from the lower left side of the outer periphery of the mold part 4 in order. The output terminals 2H and 3H and the power supply terminals 3G and 2G are arranged so as to extend from the mold portion 4 and are arranged at a predetermined interval to constitute the AMR element 5.

  Next, a rotation angle detection apparatus using such an AMR element 5 will be described.

  FIG. 7 is an exploded perspective view of the rotation angle detecting device. In FIG. 7, reference numeral 6 denotes a rotating body having a spur gear portion 6A formed on the outer periphery, and is connected to a steering shaft (not shown) inserted in the center portion. A mating engagement portion 6B is provided.

  Reference numeral 7 denotes a detection body. The spur gear portion 7A on the outer periphery meshes with the spur gear portion 6A of the rotating body 6, and a substantially cylindrical magnet 8 is attached to the center of the detection body 7 by adhesion or the like. Yes.

  Reference numeral 9 denotes a wiring board disposed substantially in parallel with the lower surface of the detection body 7. A plurality of wiring patterns (not shown) are formed on both surfaces, and the AMR element 5 is mounted on the surface facing the detection body 7. The detecting means 10 is formed by the opposed magnet 8 and the AMR element 5.

  Further, the control means 11 connected to the detection means 10 is formed on the wiring board 9 by electronic parts such as a microcomputer, and the output terminals 2F, 3F, 2H and 3H of the AMR element 5 are connected to the control means 11 with a power supply. The terminals 2G and 3G are connected to a power supply, and the ground terminals 2E and 3E are connected to a ground circuit, respectively, thereby constituting a rotation angle detection device.

  In such a rotation angle detecting device, the control means 11 is connected to an electronic circuit (not shown) of the automobile body through a connector (not shown) or the like, and is connected to the engaging portion 6B in the center of the rotating body 6. The steering shaft (not shown) is inserted through and is mounted on the automobile.

  In the above configuration, during operation, when the steering is rotated with an ignition switch (not shown) turned on, the rotating body 6 rotates accordingly, and the spur gear portion 7A is connected to the spur gear portion 6A on the outer periphery. The meshed detection pair 7 also rotates.

  As the detection body 7 rotates, the magnetic field of the magnet 8 mounted at the center of the detection body 7 changes, and the AMR element 5 detects this changing magnetic field, as shown in the voltage waveform diagram of FIG. In addition, a cosine wave output signal 12 and a sine wave output signal 13 having a voltage in the range of about 2.4 V to 2.6 V are input to the control means 11.

  That is, the output signal 12 of the cosine wave is output from the output terminals 2F and 2H of the Wheatstone bridge 2 in accordance with the magnetic field of the magnet 8 that changes with rotation, and the output terminal of the Wheatstone bridge 3 tilted by 45 degrees relative thereto. From 3F and 3H, a sine wave output signal 13 whose phase is shifted by 45 degrees is output to the control means 11.

  Then, the control means 11 calculates the input output signal 12 and output signal 13 and detects the rotation angle of the rotating steering wheel to constitute the rotation angle detection device.

  In such a rotation angle detection device, conductive foreign matters such as metal powder enter between adjacent terminals 2E to 2H and 3E to 3H extending from the mold part 4 of the AMR element 5. For example, when the output terminals 2H and 3H are short-circuited, the output signal 12 and the output signal 13 change to the output signal 14 as shown in the voltage waveform diagram of FIG. It is determined that some abnormality has occurred in the circuit.

  When the output terminal 3H and the power terminal 3G adjacent to the right are short-circuited, the output terminal 3H has a power supply potential of about 5V, so that an output signal 15 as shown in FIG. When the output terminal 3F and the ground terminal 3E adjacent to the left side are short-circuited, the output terminal 3F has the same potential as the ground potential, so that the 0V output signal 16 is input to the control means 11.

  And since the control means 11 is comprised so that the input voltage of 0.5V or less or 4.5V or more as a threshold value may be determined as abnormal, when the output signals 15 and 16 exceeding such a threshold value are input. In the same manner as described above, it is determined that an abnormality has occurred in the circuit.

  Further, when the short-circuit between the adjacent terminals as described above occurs when the ignition switch is OFF and the power is not supplied to the detection means 10 or the control means 11, not during operation, for example, the output terminal 3H When the power supply terminal 3G or the output terminal 3F and the ground terminal 3E are short-circuited, the ignition switch is turned on and the detection means 10 and the control means 11 are operated. As described above, the output signal 15 of about 5V of the power supply potential or Since the output signal 16 of the ground potential of 0V is output, the control means 11 determines abnormality from these.

  However, when the output terminals 2H and 3H are short-circuited, when the ignition switch is turned on, it is similar to the output signals 12 and 13 within the threshold value range of 0.5V to 4.5V as described above from the beginning. Since the waveform output signal 14 is output, the control means 11 cannot determine this as a waveform in which the output signals 12 and 13 have changed, and erroneously detects the rotation angle.

  Therefore, such a rotation angle detection device normally supplies power intermittently from the battery to the detection means 10 and the control means 11 even when the ignition switch is OFF, and this causes a short circuit between the output terminals as described above. It is configured to always detect whether there is a change in the output signal from the accompanying AMR element 5.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2002-213910 A

  However, in the above conventional rotation angle detection device, since the output terminals 2F and 3F adjacent to the AMR element 5 or the output terminals 2H and 3H are short-circuited, the power is supplied from the battery even when the ignition switch is OFF. Needs to be intermittently supplied to the detection means 10 and the control means 11, and there is a problem that power consumption increases.

  The present invention solves such a conventional problem. An AMR element capable of easily and reliably detecting a short circuit between an output terminal of an AMR element and an adjacent terminal, and saving power, And it aims at providing the rotation angle detection apparatus using the same.

  In order to achieve the above object, the present invention has the following configuration.

  According to the first aspect of the present invention, an anisotropic magnetoresistive element is configured by arranging a power supply terminal or a ground terminal next to an output terminal, and another terminal adjacent to the output terminal is short-circuited. In this case, since the ground potential or power supply potential signal is output from the output terminal of the AMR element, an AMR element capable of reliably detecting a short circuit between the terminals can be obtained.

  According to a second aspect of the present invention, a magnet is disposed at the center of a detection body that rotates in conjunction with the rotating body, and the AMR element according to the first aspect is disposed opposite to the magnet to provide a rotational angle detection device. Since it is configured and short-circuits between terminals can be reliably detected, it is not necessary to supply power to the control means and detection means when the ignition switch is OFF, and a rotation angle detection device that can save power is realized. It has the effect of being able to.

  As described above, according to the present invention, an advantageous effect that an AMR element capable of reliably detecting a short circuit between terminals and saving power and a rotation angle detection device using the AMR element can be realized. Is obtained.

  Embodiments of the present invention will be described below with reference to FIGS.

  In addition, the same code | symbol is attached | subjected to the part of the structure same as the structure demonstrated in the term of background art, and detailed description is simplified.

(Embodiment)
FIG. 1 is a configuration diagram of an AMR element according to an embodiment of the present invention. In FIG. 1, 21 is a magnetoresistive element made of nickel-iron alloy, 22 is a quadrilateral magnetoresistive element 21 on a silicone wafer. A first Wheatstone bridge 23 connected in a shape is a second Wheatstone bridge in which four magnetoresistive elements 21 are connected in a substantially rectangular shape. The second Wheatstone bridge 23 is in the vicinity of the first Wheatstone bridge 22. Are inclined at 45 degrees.

  In FIG. 1, the Wheatstone bridge 22 and the Wheatstone bridge 23 are shown side by side so as to be easily understood, but actually, for example, the Wheatstone bridge 23 is inclined coaxially by 45 degrees above the Wheatstone bridge 22. Is arranged in.

  The coupling points 22A, 22B, 22C, and 22D at which the magnetoresistive elements 21 of the Wheatstone bridge 22 are coupled to each other are each made of a copper alloy and formed of a substantially flat earth terminal 22E, an output terminal 22F, and a power terminal 22G by wire bonding or the like. And the output terminal 22H.

  Similarly, a ground terminal 23E, an output terminal 23F, a power supply terminal 23G, and an output terminal 23H are led out from the connection points 23A, 23B, 23C, and 23D of the Wheatstone bridge 23, respectively.

  Furthermore, 24 is a mold part made of an insulating resin such as an epoxy resin, and covers a silicon wafer, the Wheatstone bridges 22 and 23 formed thereon, and various terminals 22E to 22H and 23E to 23H.

  Then, in order from the upper left side of the outer periphery of the mold part 24, the ground terminal 22E, the output terminal 23F, the ground terminal 23E, and the output terminal 22F extend from the mold part 24 in a line at a predetermined interval. From the lower left side, the output terminal 22H, the power supply terminal 23G, the output terminal 23H, and the power supply terminal 22G are arranged in a predetermined interval so as to extend from the mold portion 24 to constitute the AMR element 25.

  Next, a rotation angle detection apparatus using such an AMR element 25 will be described.

  2 is an exploded perspective view of the rotation angle detection device, and FIG. 3 is a sectional view thereof. In FIG. 2, reference numeral 6 denotes a rotating body having a spur gear portion 6A formed on the outer periphery, and a steering (see FIG. An engaging portion 6B that engages with a shaft (not shown) is provided.

  Reference numeral 7 denotes a detection body. The spur gear portion 7A on the outer periphery meshes with the spur gear portion 6A of the rotating body 6, and a substantially cylindrical magnet 8 is attached to the center of the detection body 7 by adhesion or the like. Yes.

  Reference numeral 29 denotes a wiring board disposed substantially parallel to the upper surface of the detection body 7, and a plurality of wiring patterns (not shown) are formed on both surfaces, and an AMR element 25 is mounted on the surface facing the detection body 7. The detecting means 30 is formed by the magnet 8 and the AMR element 25 facing each other.

  Further, the control means 31 connected to the detection means 30 is formed on the wiring board 29 by electronic components such as a microcomputer, and the output terminals 22F, 23F, 22H and 23H of the AMR element 25 are connected to the control means 31 with a power supply. The terminals 22G and 23G are connected to the power supply, and the ground terminals 22E and 23E are connected to the ground via wiring patterns, respectively, thereby constituting a rotation angle detecting device.

  In such a rotation angle detecting device, the control means 31 is connected to an electronic circuit (not shown) of the automobile body through a connector (not shown) and the like, and the engaging portion 6B at the center of the rotating body 6 is connected. The steering shaft (not shown) is inserted through and is mounted on the automobile.

  In the above configuration, during operation, when the steering is rotated with an ignition switch (not shown) turned on, the rotating body 6 rotates accordingly, and the spur gear portion 7A is connected to the spur gear portion 6A on the outer periphery. The meshed detection body 7 also rotates.

  As the detection body 7 rotates, the magnetic field of the magnet 8 mounted at the center of the detection body 7 changes, and the AMR element 25 detects this changing magnetic field, as shown in the voltage waveform diagram of FIG. In addition, a cosine wave output signal 32 and a sine wave output signal 33 having a voltage in the range of about 2.4 V to 2.6 V are input to the control means 31.

  That is, the output signal 32 of the cosine wave is output from the output terminals 22F and 22H of the Wheatstone bridge 22 in accordance with the magnetic field of the magnet 8 that changes with rotation, and the output terminal of the Wheatstone bridge 23 tilted 45 degrees relative thereto. From 23F and 23H, a sine wave output signal 33 whose phase is shifted by 45 degrees is outputted to the control means 31.

  Then, the control means 31 calculates the input output signal 32 and output signal 33 and detects the rotation angle of the rotating steering wheel to constitute the rotation angle detection device.

  In such a rotation angle detection device, conductive foreign matters such as metal powder enter between adjacent terminals 22E to 22H and 23E to 23H extending from the mold part 24 of the AMR element 25. For example, when the power supply terminal 22G adjacent to the output terminal 23H is short-circuited, the output signal from the output terminal 23H is output from the sine wave output signal 33 to the power supply terminal 22G as shown in the voltage waveform diagram of FIG. It changes to an output signal 35 of about 5V which is the potential of the power supply.

  And since the control means 31 is comprised so that the input electric power of 0.5V or less or 4.5V or more as a threshold value may be determined as abnormality, when the output signal 35 exceeding such a threshold value is input, a circuit is provided. It is determined that some abnormality has occurred.

  In addition, for example, when the ground terminal 23E adjacent to the output terminal 22F is short-circuited, the output signal 36 of 0V that is the ground potential is input from the output terminal 23F to the control means 31, and thus the control means 31 is similarly configured. Determine circuit anomalies.

  Further, when the short-circuit between the adjacent terminals as described above occurs when the ignition switch is OFF and the power is not supplied to the detection means 30 or the control means 31, not during operation, for example, the output terminal 23H When the power supply terminal 22G or the output terminal 22F and the ground terminal 23E are short-circuited, when the ignition switch is turned on and the detection means 30 and the control means 31 are operated, as described above, the output signal 35 of about 5V of the power supply potential or Since the output signal 36 of the ground potential of 0V is output, the control means 31 determines abnormality from these.

  When the output terminal 23H is adjacent to the power supply terminal 23G, or when the output terminal 22H and the power supply terminal 23G are short-circuited, the output signal 35 having a power supply potential of about 5V is similarly applied to the output terminal 23F. 23E, or when the output terminal 23F and the ground terminal 22E are short-circuited, an output signal 36 having a ground potential of 0V is input to the control means 31.

  That is, since the power supply terminal or the ground terminal is arranged next to the output terminals 22F, 22H, 23F, and 23H, when the other terminals adjacent to these output terminals are short-circuited, the power supply is output from the output terminal of the AMR element. The potential output signal 35 or the ground potential output signal 36 is output so that the control means 31 can reliably detect a short circuit between adjacent terminals.

  Therefore, even when the ignition switch is OFF and a short circuit occurs between adjacent terminals, if the ignition switch is turned ON and the detection means 30 and the control means 31 are operated, the output signal 35 and the output signal are immediately output as described above. 36 is output, and the control unit 31 determines abnormality, so that it is not necessary to intermittently supply power from the battery to the detection unit 30 or the control unit 31 when the ignition switch is OFF, thereby saving power. It becomes.

  As described above, according to the present embodiment, the AMR element 25 is formed by arranging the power supply terminal or the ground terminal adjacent to the output terminals 22F, 22H, 23F, and 23H, and the rotation angle is detected using the AMR element 25. By configuring the device, it is possible to reliably detect a short circuit between adjacent terminals, and to obtain an AMR element that can save power and a rotation angle detection device using the same.

  An anisotropic magnetoresistive element and a rotation angle detection device using the same according to the present invention can reliably detect a short-circuit between adjacent terminals, and can achieve power savings. This is useful for detecting the rotation angle.

The block diagram of the anisotropic magnetoresistive element by one embodiment of this invention Exploded perspective view of the rotation angle detector Cross section Same voltage waveform diagram Voltage waveform diagram at the time of abnormality Configuration diagram of conventional anisotropic magnetoresistive element Exploded perspective view of the rotation angle detector Same voltage waveform diagram Voltage waveform diagram at the time of abnormality

Explanation of symbols

6 Rotating body 6A, 7A Spur gear portion 6B Engaging portion 7 Detector 8 Magnet 21 Magnetoresistive element 22 First Wheatstone bridge 23 Second Wheatstone bridge 22A, 22B, 22C, 22D, 23A, 23B, 23C, 23D Coupling Point 22E, 23E Ground terminal 22F, 23F, 22H, 23H Output terminal 22G, 23G Power supply terminal 24 Mold part 25 Anisotropic magnetoresistive element 29 Wiring board 30 Detection means 31 Control means 32, 33, 35, 36 Output signal

Claims (2)

A first Wheatstone bridge in which four magnetoresistive elements are connected in a substantially rectangular shape; a second Wheatstone bridge disposed at an angle of 45 degrees in the vicinity of the first Wheatstone bridge; the first and second A plurality of output terminals derived from a diagonal coupling point of the Wheatstone bridge, a power terminal derived from one of the other coupling points, a ground terminal derived from the diagonal coupling point of the power terminal, An anisotropic magnetoresistive element comprising a molded part covering the first and second Wheatstone bridges, wherein the power supply terminal or the ground terminal is arranged next to the output terminal. A rotating body that rotates in conjunction with a steering, a detection body that rotates in conjunction with the rotation of the rotating body, a magnet that is disposed in the center of the detection body, and a magnet that is disposed opposite to the magnet. A rotation angle detecting device comprising the anisotropic magnetoresistive element described above and control means for detecting the rotation angle of the rotating body based on an output signal from the anisotropic magnetoresistive element.

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