Rotation detection device and electric servo steering device that uses this

Abstract

Rotation detection device comprising: at least one first and one second sensor element (601 to 607) each designed to measure a rotation of a detection target (10); a circuit module (610 to 612, 620 to 622) comprising: a first and a second angle-of-rotation calculator, each designed to calculate an angle of rotation of the detection target based on a corresponding first measurement from the first sensor element and a second measurement from the second sensor element; a first and a second speed calculator, each designed to calculate a speed of rotation of the detection target based on a corresponding first measurement from the first sensor element and a second measurement from the second sensor element;and a first and a second communicator, each designed to output a rotation angle signal based on the rotation angle and a speed signal based on the speed to a controller (51, 52); and a package (65, 661, 662) designed to accommodate the first and second sensor elements and the circuit module, the package being mounted on a circuit board (21, 23) separate from the controller.

Description

Technical FieldThe present invention relates to rotation detection devices, and electric power steering devices using the rotation detection devices.BackgroundVarious rotation detection devices are configured to measure magnetic change based on rotation of a motor serving as a detection target and generate information indicating rotation of the motor based on the measured magnetic change.For example, JP 2015-116 964 A discloses a typical one of these devices. Specifically, this JP 2015-116 964 A discloses a control unit for an electric power steering apparatus having a motor that assists a driver in operating a steering wheel.The control unit includes first and second magnetic sensors, which are an example of first and second rotation sensors.The first magnetic sensor measures a magnetic change based on rotation of a motor and outputs first rotation information indicating the measured magnetic change. The second magnetic sensor, which is disposed separately from the first magnetic sensor, measures a magnetic change based on the rotation of the motor and outputs second rotation information indicating the measured magnetic change.The control unit further includes a single monitoring section circuit that calculates, based on the first rotation information and the second rotation information, a rotation angle signal indicating a rotation angle of the motor.The control unit further includes a control section that generates the position of the steering wheel based on the rotation signal calculated by the monitoring section circuit.Furthermore, DE 10 2015 102 161 A1 discloses a rotation detection apparatus which has two sensor elements for measuring a rotation of a detection target and a circuit module having two computers for calculating a rotation angle and a rotational speed of the detection target from the measurement values of the sensor elements.Furthermore, a magnetic field sensor arrangement is known from DE 10 2005 060 713 A1, which has a stack arrangement with two magnetic field sensor bodies, each of which has two parallel main surfaces, wherein a magnetic field-sensitive element is arranged on one of the two main surfaces of each magnetic field sensor body.SummaryTechnical ProblemThe patent literature is configured such that the single monitoring section circuit is arranged for the first and second magnetic sensors. A malfunction in a part of the monitoring section circuit may make it difficult for the malfunction control circuit to calculate the rotation angle signal indicating the rotation angle of the motor based on the first rotation information and the second rotation information. This may lead to difficulties in continuously driving the electric power steering device.In view of the above problem, it is an object of the present invention to provide rotation detection devices and electric power steering devices using the rotation detection devices. The devices are each configured such that a portion of the corresponding device calculates, based on information indicating a rotation of a detection target measured independently of at least first and second sensor elements, a rotation angle signal indicating the rotation angle of the detection target, and a rotation speed signal indicating the number of rotations of the detection target.In particular, each of these devices is capable of continuously calculating the rotation angle signal and the rotation speed signal even when the portion of the corresponding device has malfunctioned.Solution of the ProblemA rotation detection device according to an exemplary aspect of the present invention includes at least first and second sensor elements, a circuit module, and a package. Each of the first and second sensor elements serves to measure rotation of a detection target. The circuit module includes (1) first and second rotation angle calculators each configured to calculate a rotation angle of the detection target based on a corresponding one of a first measurement value of the first sensor element and a second measurement value of the second sensor element. (2) First and second rotational speed calculators each configured to calculate a rotational speed of the detection target based on a corresponding one of a first measurement value of the first sensor element and a second measurement value of the second sensor element. (3) First and second communicators each configured to output a rotation angle signal based on the rotation angle and a rotation speed signal based on the rotation speed to a controller.The package includes the first and second sensor elements and the circuit module and is mounted on a circuit board separately from the regulator.The circuit module of the exemplary aspect includes the first and second rotation angle calculators that each calculate the rotation angle of the detection target, and the first and second rotation speed calculators that each calculate the rotation speed of the detection target.This configuration therefore makes it possible to continuously calculate the rotation angles and the rotation speed even when a malfunction occurs in one of the first and second rotation angle calculators or a malfunction occurs in one of the first and second rotation speed calculators.Brief Description of the DrawingsFIG. 1 is a structural diagram schematically showing a steering system according to the first embodiment of the present invention. FIG. 2 is a circuit diagram schematically showing a driving device shown in FIG. 1. FIG. 3 is a plan view of the driving device shown in FIG. 1. FIG. 4 is a cross-sectional view taken along a line IV-IV of FIG. 3 ; FIG. 5 is a side view of a first circuit board according to the first embodiment of the present invention. FIG. 6 is a side view of a second circuit board according to the first embodiment of the present invention. FIG. 7A is a side view of a rotation detection device according to the first embodiment. FIG. 7B is a side view of a rotation detection device according to a modification of the first embodiment. FIG. 8 is a plan view schematically showing the internal structure of the rotation detection device according to the first embodiment of the present invention. FIG. 9 is a block diagram schematically showing the rotation detection device according to the first embodiment of the present invention. FIG. 10 is a time chart schematically showing an example of how a sensor and a microcomputer thereof communicate with each other according to the first embodiment of the present invention. FIG. 11 is a time chart schematically showing another example of how a sensor and a microcomputer thereof communicate with each other according to the first embodiment of the present invention. FIG. 12 is a block diagram schematically showing a rotation detection device according to the second embodiment of the present invention. FIG. 13A is a plan view schematically showing an example of the internal structure of the rotation detection device according to the second embodiment of the present invention. FIG. 13B is a plan view schematically showing another example of the internal structure of the rotation detection device according to the second embodiment of the present invention. FIG. 14 is a block diagram schematically showing a rotation detection device according to the third embodiment of the present invention. FIG. 15 is a time chart schematically showing how a sensor and a microcomputer thereof communicate with each other. FIG. 16 is a block diagram schematically showing a rotation detection device according to the fourth embodiment of the present invention. FIG. 17 is a block diagram schematically showing a rotation detection device according to the fifth embodiment of the present invention. FIG. 18 is a flowchart schematically showing a rotation information calculation task according to the fifth embodiment of the present invention. FIG. 19 is a block diagram schematically showing a rotation detection device according to the sixth embodiment of the present invention. FIG. 20A is a plan view schematically showing an example of the internal structure of the rotation detection device according to the seventh embodiment of the present invention. FIG. 20B is a plan view schematically showing another example of the internal structure of the rotation detection device according to the seventh embodiment of the present invention. FIG. 21 is a side view of a first circuit board according to the eighth embodiment of the present invention. FIG. 22 is a side view showing a rotation detection device according to the eighth embodiment of the present invention. FIG. 23A is a side view showing an example of the rotation detection device according to the eighth embodiment of the present invention. FIG. 23B is a side view showing another example of the rotation detection device according to the eighth embodiment of the present invention. FIG. 24 is a side view of a circuit board according to the ninth embodiment of the present invention. FIG. 25A is a diagram showing how sensor elements according to a comparative example are arranged. FIG. 25B is a diagram showing how measurement values of the respective sensor elements according to the comparative example change. FIG. 25C is a diagram showing digital conversion values of the respective sensor elements according to the comparative example. FIG. 26A is a diagram showing how sensor elements according to the fifth embodiment of the present invention are arranged. FIG. 26B is a diagram showing how measurement values of the respective sensor elements according to the tenth embodiment of the present invention change. FIG. 26C is a diagram showing digital conversion values of the respective sensor elements according to the tenth embodiment of the present invention. FIG. 27 is a graph showing a relationship between displacement amounts of the sensor elements and measurement errors according to the tenth embodiment of the present invention. FIG. 28 is a view showing variations of how the sensor elements according to the tenth embodiment of the present invention are arranged. FIG. 29 is a time chart showing how a sensor and a microcomputer thereof communicate with each other according to the comparative example. FIG. 30 is a side view of a rotation detection device according to a reference example.DESCRIPTION OF EMBODIMENTSHereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the embodiments, like parts in the embodiments to which like reference numerals are assigned are omitted to avoid redundant description.First EmbodimentNext, the first embodiment of the present invention will be described with reference to Figs. 1 to 11.As shown in FIG. 1, a rotation detection device 1 according to the first embodiment is installed, for example, in a driving device 8 of a steering system 100 including an electronic power steering device 108. The electronic power steering device 108 is installed in a vehicle V. The electronic power steering device 108 serves to assist a steering operation of the driver of a steering wheel of the vehicle V. The drive device 8 includes a motor unit 10 having a shaft 15 and a control module 20 for drive-controlling the motor unit 10; the motor unit 10 and the control module 20 are connected to each other into one unit, thus forming a motor module. FIG. 1 may show the control module 20 as an ECU.Specifically, FIG. 1 schematically shows an example of the overall structure of the steering system 100 including the electronic power steering device 108. The steering system 100 includes, for example, the steering wheel 101 as an operator, a steering shaft 102, a torque sensor 103, a pinion gear 104, a steering linkage 105, wheels 106, and the electronic power steering device 108.The steering shaft 102 includes, for example, first and second end portions. The steering wheel 101 is connected to the first end portion of the steering shaft 102. The torque sensor 103 is fixed to the steering shaft 102; the torque sensor 103 serves to measure a torque based on a steering operation of the driver of the steering shaft 102 as a steering torque. The pinion gear 104 is fixed to the second end portion of the steering shaft 102.The steering linkage 105 includes a rod-shaped rack with which the pinion 104 is engaged. The steering linkage 105 further includes, for example via tie rods, the wheels 106 attached to their respective ends.The driver rotating the steering wheel 101 causes the steering shaft 102 coupled to the steering wheel 101 to rotate. This rotational movement of the steering shaft 102 is converted into a linear movement of the rack of the steering rods 105. This linear movement of the rack of the steering linkages 105 causes the wheels 106 to be driven over the respective tie rods. The steering angle of each of the wheels 106 is determined based on the axial displacement of the rack of the steering links 105.The electric power steering device 108 includes, for example, the drive device 8, a deceleration gear mechanism 109 serving as a power transmission mechanism, and the torque sensor 103. The delay gear mechanism 109 includes, for example, a first gear coupled to the shaft 15 of the motor unit 10 and a second gear engaged with the first gear and fixed to the steering shaft 102. For example, the deceleration gear mechanism 109 is for transmitting the assist torque generated based on the rotation of the shaft 15 of the motor unit 10 to the steering shaft 102 while retarding the rotational speed of the motor unit 10 by a predetermined gear ratio between the first gear and the second gear, i.e., increasing the assist torque generated by the motor unit 10 by the predetermined gear ratio between the first gear and the second gear.Specifically, the electric power steering device 108 is configured such that the control module 20 causes the motor unit 10 to generate an assist torque based on a steering torque measured by the torque sensor 103 and / or vehicle operation state signals. The vehicle operation state signals including, for example, the speed of the vehicle V represent the operation states of the vehicle V and are transmitted from another control unit via an on-board network such as a controller area network (CAN), not shown.Specifically, the electric power steering apparatus 108 according to the first embodiment is configured as a shaft assist system for assisting steering of the steering shaft 102 based on the assist torque generated by the motor unit 10. The electric power steering device 108 according to the first embodiment may be configured as a rack assist system for assisting the axial displacement of the rack of the steering links 105 based on the assist torque generated by the motor unit 10. That is, the first embodiment is configured such that the steering shaft 102 serves as a target to be assisted, but the steering linkage 105 may serve as a target to be assisted.Next, an example of the electrical configuration of the electric power steering device 108 will be described with reference to FIG. 2. Note that, in FIG. 2, connecting wires of the first and second circuit boards 21 and 22 described later and correcting wires between the first and second circuit boards 21 and 22 are respectively illustrated with thinner lines, and some of the connecting wires are omitted to avoid complicated illustration of the electrical configuration of the electric power steering device 108.The motor unit 10 is configured as, for example, a three-phase brushless motor including, for example, a stator 10 a, a rotor 10 b, the shaft 15, and a magnetic field element, not illustrated, such as permanent magnets, a field coil, and the like. The stator 10 aincludes, for example, a not-illustrated stator core, a first coil set 11 of three-phase coils, i.e., U 2, V 2, and W 2 coils, 111, 112, and 113, and a second coil set 12 of three-phase coils, i.e., U 2, V 2, and W 2 coils 121, 122, and 123. The rotor 10 bto which the shaft 15 is fixed is rotatable together with the shaft 15 relative to the stator core.The three-phase coils 111, 112, and 113 of the first coil set 11 and the three-phase coils 121, 122, and 123 of the second coil set 12 are wound in slots of the stator core and around the stator core, for example. The magnetic field element is fixed to the motor 10 bfor generating a magnetic field. That is, the motor unit 10 is configured to rotate the motor 10 bbased on magnetic interactions between the magnetic field generated by the magnetic field element of the motor 10 band a rotating magnetic field generated by the three-phase coils 111, 112, and 113 of the first coil set 11 and the three-phase coils 121, 122, and 123 of the second coil set 12 of the stator 10 a.Note that currents flowing through the respective U1, V1 and W1 phase coils 111, 112 and 113 are referred to as phase currents Iu1, Iv1 and Iw1, and accordingly currents flowing through the respective U2, V2 and W2 coils 121, 122 and 123 are referred to as phase currents Iu2, Iv2 and Iw2.As shown in FIG. 2, the control module 20 includes the first and second circuit boards 21 and 22, the first and second inverters 30 and 40, the first and second current sensors 31 and 41, and the first and second relays 32 and 42.Specifically, the rotation detection device 1 installed in the driving device 8 includes a sensor package 65. the sensor package 65 includes a first sensor 61 and a second sensor 62, each configured to measure rotation of the motor 10 bof the motor unit 10. The first sensor 61 and the second sensor 62 are shown as SENSOR 1 and SENSOR 2, respectively, in FIG. 2.The driving device 8 includes first and second batteries 39 and 49, fuses 38 and 48, and a connector unit 70 (see FIGS. 3 and 4 ). The connector unit 70 includes the first and second power supply connectors 75 and 76, and the first and second signal connectors 77 and 78.The first battery 39 includes a positive pole and a negative pole, and the positive pole of the first battery 39 is connected to the first power supply connector 75 via the fuse 38, and the negative pole of the first battery 39 is connected to the first power supply connector 75. The first battery 39 is connected to the first inverter 30, the first power supply connector 75, the first reactor 35, the first relay 32, the first reverse connection protection relay 33, and the first capacitor 36 via the fuse 38. The first inverter 30 is connected to the three-phase coils 111, 112, and 113 of the first coil set 11.The first inverter 30 includes six switching elements 301 to 306 connected in a bridge configuration.Specifically, the switching elements 301 and 304 are a pair of U-phase upper and lower arm switching elements connected in series with each other, and the switching elements 302 and 305 are a pair of V-phase upper and lower arm switching elements connected in series with each other. Further, the switching elements 303 and 306 are a pair of W-phase upper-and-lower arm switching elements connected in series with each other. Hereinafter, the switching elements are referred to as SW elements.The SW elements 301 to 306 are, for example, semiconductor SW elements such as metal oxide semiconductor field effect transistors (MOSFETs). The first embodiment uses MOSFETs as the respective SW elements 301 to 306, SW elements 401 to 406 described later, and the relays 32, 33, 42, and 43, but other types of SW elements such as insulated gate bipolar transistors (IGBTs) may be used instead of the MOSFETs. That is, any of various types of SW elements such as MOSFETs or IGBTs may be used for each of the SW elements 301 to 306, the SW elements 401 to 406 described later, and the relays 32, 33, 42, and 43.The intrinsic diode of each of the SW elements 301 to 306 formed of the MOSFETs 301 to 306 may serve as a flywheel diode connected in antiparallel to the corresponding one of the SW elements 301 to 306. Further flywheel diodes may be connected in antiparallel with the respective SW elements 301 to 306.Specifically, the SW elements 301 to 303 are arranged on a high potential side, and the SW elements 304 to 306 are arranged on a low potential side. The connection point between the U-phase upper-and-lower arm SW elements 301 and 304, i.e., between the source of the SW element 301 and the drain of the SW element 304, is connected to a first end of the U1phase coil 111. The connection point between the V-phase upper-and-lower arm SW elements 302 and 305, i.e., between the source of the SW element 302 and the drain of the SW element 305, is connected to a first end of the V 1 phase coil 112. Further, the connection point between the W-phase upper-and-lower arm SW elements 303 and 306, i.e., between the source of the SW element 303 and the drain of the SW element 306, is connected to a first end of the W 1 phase coil 113.The drains of the SW elements 301 to 303 are commonly connected to the positive terminal of the first battery 39 via the first reverse connection protection relay 33, the first relay 32, the first reactor 35, the first power supply connector 75, and the fuse 38.Second ends of the U1, V1and W1phase coils, which are opposite to the first ends, are connected to a common node, i.e., a neutral point, in a star configuration, for example.The first current sensor 31 includes current detection elements 311, 312, and 313. For example, each of the current sensing elements 311, 312, and 313 includes a shunt resistor. Each of the current detection elements 311 to 313 has first and second ends that are opposed to each other. The first end of each of the current detection elements 311 to 313 is connected to the source of a corresponding one of the forearm SW elements 304, 305, and 306. The second end of each of the current detection elements 311 to 313 is connected to the negative terminal of the first battery 39 via a common signal ground and the first power supply connector 75. This results in the first series connection of the SW elements 301 and 304 and the current detection element 311, the second series connection of the SW elements 302 and 305 and the current detection element 312, and the third series connection of the SW elements 303 and 306 and the current detection element 313 connected in parallel to the first battery 39.The current detection element 311 measures the phase current Iu 1 flowing through the U 1 phase coil 111, the current detection element 312 measures the phase current Iv 1 flowing through the V 1 phase coil 112, and the current detection element 313 measures the phase current Iw 1 flowing through the W 1 phase coil 113.Other types of current detection elements such as Hall devices may be used as the current detection elements 311 to 313 and 411 to 413 described later.The first inverter 30 is configured to receive the direct current (DC) power supplied from the first battery 39 and convert the direct current into an alternating current (AC) power. Further, the first inverter 30 is configured to supply the alternating current to the three-phase coils 111, 112, and 113 of the first coil set 11.The first power supply relay 32, which is, for example, a MOSFET, is disposed between the first battery 39 and the first inverter 30, and is configured to establish an electrical path therebetween and cut off the electrical path. The first reverse connection protection relay 33, which is a MOSFET, for example, is connected between the first relay 32 and the first inverter 30, wherein the switching direction of the intrinsic diode of the first reverse connection protection relay 33 is opposite to the switching direction of the intrinsic diode of the first power supply relay 32. This would prevent current from flowing from the first inverter 30 to the first battery 39 even when the first battery 39 is reversely connected, so that the positive pole of the first battery 39 would be connected to the common signal ground.The first reactor 35 is connected between the first power supply relay 32 and the first battery 39 and the fuse 38 via the first power supply connector 75. The first capacitor 36 is connected in parallel to the first to third series circuits of the first inverter 30, respectively. The first reactor 35 and the first capacitor 36 constitute a filter circuit that reduces noise transmitted from other devices sharing the first battery 39 and noise transmitted from the driving device 8 to the other devices sharing the first battery 39. The first capacitor 36 serves to store electric charges, thereby assisting the power supply to the first inverter 30.The second battery 49 has a positive pole and a negative pole, and the positive pole of the second battery 49 is connected to the second power supply connector 76 via the fuse 48, and the negative pole of the second battery 49 is connected to the second power supply connector 76. The second battery 49 is connected to the second inverter 40, the second power supply connector 76, the second reactor 45, the second relay 42, the second reverse connection protection relay 43, and the second capacitor 46 via the fuse 48, and the second inverter 40 is connected to the three-phase coils 121, 122, and 123 of the second coil set 12.The second inverter 40 includes six SW elements 401 to 406 connected in a bridge configuration.Specifically, the SW elements 401 and 404 are a pair of U-phase upper-and-lower arm SW elements connected in series with each other, and the SW elements 402 and 405 are a pair of V-phase upper-and-lower arm SW elements connected in series with each other. Further, the SW elements 403 and 406 are a pair of W-phase upper-and-lower arm SW elements connected in series with each other.The intrinsic diode of each of the SW elements 401 to 406 including the MOSFETs 401 to 406 may serve as a flywheel diode connected in antiparallel with the corresponding one of the SW elements 401 to 406. Further flywheel diodes may be connected in antiparallel with the respective SW elements 401 to 406.Specifically, the SW elements 401 to 403 are arranged on the high potential side, and the SW elements 404 to 406 are arranged on the low potential side.The connection point between the U-phase upper-and-lower arm SW elements 401 and 404, i.e., between the source of the SW element 401 and the drain of the SW element 404, is connected to a first end of the U2 phase coil 121, and the connection point between the V-phase upper-and-lower arm SW elements 402 and 405, i.e., between the source of the SW element 402 and the drain of the SW element 405, is connected to a first end of the V2 phase coil 122. Further, the connection point between the W-phase upper-and-lower arm SW elements 403 and 406, i.e., between the source of the SW element 403 and the drain of the SW element 406, is connected to a first end of the W2phase coil 123.The drains of the SW elements 401 to 403 are commonly connected to the positive pole of the second battery 49 via the second reverse connection protection relay 43, the second relay 42, the second choke coil 45, the second power supply connector 76, and the fuse 48. Second ends of the U2, V2 and W2 phase coils opposite to the first ends are connected to a common node, i.e., a neutral point, for example, in a star configuration.The second current sensor 41 includes current detection elements 411, 412, and 413. For example, current sensing elements 411, 412, and 413 include a shunt resistor. Each of the current detection elements 411 to 413 has first and second ends that are opposed to each other. The first end of each of the current detection elements 411 to 413 is connected to the source of a corresponding one of the forearm SW elements 404, 405 and 406. The second end of each of the current detection elements 411 to 413 is connected to the negative terminal of the second battery 49 via a common signal ground and the second power supply connector 76. This results in the first series connection of the SW elements 401 and 404 and the current detection element 411, the second series connection of the SW elements 402 and 405 and the current detection element 412, and the third series connection of the SW elements 403 and 406 and the current detection element 413 connected in parallel to the second battery 49.The current detection element 411 measures the phase current Iu 2 flowing through the U 2 phase coil 121, the current detection element 412 measures the phase current Iv 2 flowing through the V 2 phase coil 122, and the current detection element 413 measures the phase current Iw 2 flowing through the W 2 phase coil 123.The second inverter 40 is configured to convert a direct current supplied from the second battery 49 into an alternating current. Further, the second inverter 40 is configured to supply the alternating current to the three-phase coils 121, 122, and 123 of the second coil set 12.The second power supply relay 42, which is, for example, a MOSFET, is disposed between the second battery 49 and the second inverter 40. The second polarity reversal protection relay 43, which is a MOSFET, for example, is connected between the second relay 42 and the second inverter 40. The second reactor 45 is connected between the second power supply relay 42 and the second battery 49 via the second power supply connector 76 and the fuse 48. The second capacitor 46 is connected in parallel to the first to third series circuits of the second inverter 40, respectively.The detailed structures of the second power supply relay 42, the second reverse connection protection relay 43, the second reactor 45, and the second capacitor 46 are respectively identical to those of the corresponding one of the first power supply relay 32, the first reverse connection protection relay 33, the first reactor 35, and the first capacitor 36. When mechanical relays are used as the first and second relays 32 and 42, respectively, the first and second reverse connection protection relays 33 and 43 may be omitted.The first motor control unit 501, which serves to control how the first coil set 11 is energized, includes a first microcomputer 51 and a first integrated circuit 56 that are communicatively connected to each other. For example, an application specific integrated circuit (ASIC) is used as the first integrated circuit 56, as shown in FIG. 2.The first microcomputer 51, which includes, for example, a CPU and a storage unit including a ROM and a RAM, is communicably connected to the first sensor 61, the first current sensor 31, and the torque sensor 103 (see FIG. 1 ). The first microcomputer 51 is configured to generate control signals based on measurement values, i.e., measurement signals output from the first sensor 61, the first current sensor 31, and the torque sensor 103; the control signals are for controlling on / off operations of the switching elements 301 to 306 of the first inverter 30 and the relays 32 and 33. As another example, the first microcomputer 51 may include a dedicated electronic hardware circuit to implement the operations of the first microcomputer 51 as hardware operations.The first integrated circuit 56 includes, for example, a pre-driver, a signal amplifier, and a regulator. The pre-driver is to generate gate signals for the respective switching elements 301 to 306 based on the control signals for the respective switching elements 301 to 306. The pre-driver is further adapted to output the gate signals to the gates of the respective switching elements 301 to 306 and thus individually control the on / off switching operations of the switching elements 301 to 306. The signal amplifier serves to amplify the measurement signal transmitted from, for example, the first sensor 61 and output the amplified measurement signal to the first microcomputer 51. The regulator is configured as a stabilization circuit that stabilizes an operating voltage applied to, for example, the first microcomputer 51 from, for example, a power supply not shown.The second motor control unit 502, which serves to control how the second coil set 12 is energized, includes a second microcomputer 52 and a second integrated circuit 57 communicatively connected to each other.The second microcomputer 52, which includes, for example, a CPU and a storage unit including a ROM and a RAM, is communicatively connected to the rotation detection device 1, the second current sensor 41, and the torque sensor 103 (see FIG. 1 ). The second microcomputer 52 is configured to generate control signals based on measurement values, i.e., measurement signals transmitted from the rotation detection device 1, the second current sensor 41, and the torque sensor 103; the control signals have been configured to control on / off switching operations of the SW elements 401 to 406 of the second inverter 40 and the relays 42 and 43. For example, the CPU of the second microcomputer 52 may run one or more programs, i.e., program instructions stored in the storage unit, and thus implement the operations of the second microcomputer 52 as software operations. As another example, the second microcomputer 52 may include a dedicated electronic hardware circuit to implement the operations of the second microcomputer 52 as hardware operations.The second integrated circuit 57 includes, for example, a pre-driver, a signal amplifier, and a regulator. The pre-driver is to generate gate signals for the respective SW elements 401 to 406 based on the control signals for the respective SW elements 401 to 406. The pre-driver further serves to output the generated gate signals to the gates of the respective SW elements 401 to 406 and thus individually control the on / off switching operations of the SW elements 401 to 406. The signal amplifier serves to amplify the measurement signal transmitted from, for example, the second sensor 62, and output the amplified measurement signal to the second microcomputer 52. The regulator is configured as a stabilization circuit that stabilizes an operating voltage supplied to, for example, the second microcomputer 52 from, for example, the power supply not shown.As described above, the rotation detection device 1 installed in the driving device 8 includes the sensor package 65 having the first and second sensors 61 and 62. FIG. 2 shows the first and second sensors 61 and 62 as SENSOR 1 and SENSOR 2, respectively. The first and second microcomputers 51 and 52 according to the first embodiment serve as, for example, controllers.Subsequently, at least the first coil set 11, the first inverter 30, and the first motor control unit 501 provided for the first coil set 11 constitute a first motor drive system 901. Also, at least the second coil set 12, the second inverter 40, and the second motor control unit 502 provided for the second coil set 12 constitute a second motor drive system 902. Although the rotation detection device 1 is not included in each of the first and second motor drive systems 901 and 902 in FIG. 2, in order to avoid too much complexity of FIG. 2, the first motor drive system 901 may include the first sensor 61 and the second motor drive system 902 may include the second sensor 62.That is, the drive device 8 according to the first embodiment is configured such that (1) the circuit components including the first inverter 30 and the first motor control unit 501 and required to control the first coil set 11 are provided for the first coil set 11. (2) The circuit components including the second inverter 40 and the second motor control unit 502 required to control the second coil set 12 are provided for the second coil set 12.In other words, the driving device 8 is configured as a dual redundant system including at least the first and second inverters 30 and 40 and the first and second motor control units 501 and 502. This dual-redundant configuration of the drive device 8 enables the motor unit 10 to be continuously driven even when a malfunction occurs in the first inverter 30 or the second inverter 40 or a malfunction occurs in the first motor control unit 501 and the second motor control unit 502.As described above, the driving device 8 as a dual-redundant battery system includes the first battery 39 for the first coil set 11 and the second battery 40 for the second coil set 12. When the rated voltage at the first battery 39 is different from the rated voltage at the second battery 49, a voltage converter may be disposed either between the first battery 39 and the first inverter 30 or between the second battery 49 and the second inverter 40.As shown in FIGS. 2, 4, and 5, driving components including the switching elements 301 to 306 and 401 to 406, the current detection elements 311 to 313 and 411 to 413, the relays 32, 33, 42, and 43, the reactors 35 and 45, and the capacitors 36 and 46 are mounted on the first circuit board 21. As further shown in FIGS. 2, 4, and 5, control components including the microcomputers 51 and 52 and the integrated circuits 56 and 57 are mounted on the second circuit board 22.That is, the driving components are electronic components through which a relatively large current flows, which is similar to the motor currents flowing through the coils 111 to 113 and 121 to 123. The control components are electronic components through which no motor currents flow.The rotation detection device 1 is mounted on the first circuit board 21.The first power supply connector 75 includes a power supply terminal 751 and a ground terminal 752, and the second power supply connector 76 includes a power supply terminal 761 and a ground terminal 762. The first signal connector 77 includes a torque signal terminal 771 and a vehicle signal terminal 772, and the second signal connector 78 includes a torque signal terminal 781 and a vehicle signal terminal 782. The drive device 8 comprises internal signal terminals 717.Triangular output marks show where these terminals are connected to the first circuit board 21 and / or the second circuit board 22. For example, the power supply terminals 751 and 761, the ground terminals 752 and 762, and the internal signal terminals 717 are connected to the first and second circuit boards 21 and 22, respectively. The torque signal terminals 771 and 781 and the vehicle signal terminals 772 and 782 are connected to the second circuit board 22, but not to the first circuit board 21.Note that in FIG. 2, the power supply terminals are respectively denoted as POWER 1 1 and POWER 2, and the ground terminals are respectively denoted as GROUND 1 and GROUND 2. The torque signal terminals are labeled M 1 and M 2, and the vehicle signal terminals are labeled CAN 1 and CAN 2.Even if at least one of the lines each connecting a corresponding one of the terminals and at least one of the first and second circuit boards 21 and 22 is branched, this does not necessarily mean that the corresponding at least one actual terminal actually branches.Next, an example of the structure of the driving device 8 will be described with reference to FIGS. 3 to 6. Specifically, FIG. 3 is a plan view of the driving device 8, and FIG. 4 is a cross-sectional view taken along a line IV-IV of FIG. 3, FIG. 5 is a schematic side view of the first circuit board 21, and FIG. 6 is a schematic side view of the second circuit board 22.As shown in FIG. 4, the motor unit 10 includes the stator 10 a(see FIG. 2 ), the motor 10 b(see FIG. 1 ), and the shaft 15 fixed to the motor 10 b. The motor unit 10 includes a motor housing 17 formed of a substantially cylindrical housing 171, and the stator 10 ais installed in the cylindrical housing 171 of the motor housing 17 on the inner circumferential surface of the cylindrical housing 171 of the motor housing 17. as described above, the motor 10 bis installed in the stator 10 ato be rotatable relative to the stator 10 a, and the motor 10 bincludes a substantially cylindrical rotor core, and the shaft 15 is fixedly attached to a central axis portion of the motor core. Thereby, the shaft 15 and the motor 10b can be rotated as a unit.The cylindrical housing 171 of the motor housing 17 has first and second ends opposing each other in its axial direction. An opening extends through the first axial end of the cylindrical housing 171, and the control module 20 is disposed in the opening of the first axial end of the motor housing 17. The cylindrical housing 171 includes an annular groove 172 formed in its first axial end.The shaft 15 has first and second ends that are opposite to each other in the axial direction thereof. The first end of the shaft 15 is disposed opposite the control module 20. The second end of the shaft 15 not shown in FIG. 4 serves as an output terminal coupled to the delay gear 109 (see FIG. 1 ). This enables transmission of torque generated based on rotation of the motor assembly including the motor 10 band the shaft 15 to the steering shaft 10 via the delay gear 109.The motor unit 10 includes a substantially circular disk-like magnet 16 coaxially fixed to an end surface of the first end of the shaft 15. A virtual line extending from the central axis of the shaft 15 and passing through the center of the magnet 16 is defined as a rotation central line Ac (see, for example, FIG. 8 ).The motor unit 10 further includes a substantially cylindrical frame 18 fixed to the inner circumferential surface of the cylindrical housing 171 so as to be fixed closer to the first axial end of the cylindrical housing 171 while the shaft 15 rotatably extends through the frame 18. For example, the frame 18 is press-fitted to fit into the cylindrical housing 171 of the motor housing 17. The motor housing 17 and the frame 18 constitute a housing member for enclosing the components of the motor unit 10. the frame 18 has an end face 181 facing the control module 20, and a concave recess is formed in the central portion of the end face 181. The magnet 16 is installed in the recess so as to be exposed toward the control module 20.The frame 18 includes first board securing members 185 each having a predetermined first height and further includes second board securing members 186 each having a predetermined second height; the first and second board securing members 185 and 186 are fixed to the end surface 181 of the frame 18 with their height directions directed substantially perpendicular to the end surface 181. The second height of each of the second board securing members 186 is greater than the first height of each of the first board securing members 185. The first circuit board 21 through which through holes extend is fixed on the first board securing members by means of screws 19. The second circuit board 22 is mounted on the second board securing members 186 by means of screws 196. The first and second circuit boards 21 and 22 may also be fixed to the frame 18 such that one of the fixing members is not a screw.The three-phase coils 111, 112 and 113 of the first coil set 11 and the three-phase coils 121, 122 and 123 are connected to respective phase motor lines, not shown; the motor lines extend through axial through holes, not shown, formed through the frame 18 to be led out of the frame 18 toward the control module 20. The guided motor lines are extended to be connected to the first circuit board 21.The control module 20 fixed to the first axial end of the cylindrical housing 171 of the motor housing 17 is fixed in the opening of the first axial end of the cylindrical housing 171 so as to be inside a motor bezel. Note that the motor tube sheet constitutes a virtual area formed by virtually extending the first axial end of the motor housing 17 in the axial direction away from the frame 18.Note that the axial direction and the radial direction of the motor unit 10 serve as the axial direction and the radial direction of the driving device 8, respectively, and the axial direction and the radial direction of the driving device 8 are hereinafter simply described as the axial direction and the radial direction, respectively.As described above, the control module 20 includes, for example, the first circuit board 21, the second circuit board 22, and the connector unit 70. the first and second circuit boards 21 and 22 are each disposed substantially parallel to the end surface 181 of the frame 18. The first and second circuit boards 21 and 22 are further arranged in the order of the first circuit board 21 and the second circuit board 22 from the motor unit 10 side.The first circuit board 21 has first and second main surfaces 211 and 212 that are opposed to each other; the first main surface 211 is located closer to the motor unit 10 than the second main surface 212 (see FIGS. 5 and 6 ). The second circuit board 22 has first and second main surfaces 221 and 222 that are opposed to each other; the first main surface 221 is located closer to the motor unit 10 than the second main surface 222 (see FIGS. 5 and 6 ).As shown in FIGS. 4 and 5, the SW elements 301 to 306 and 401 to 406, the current detection elements 311 to 313 and 411 to 413, and the sensor package 65 are mounted on the first main surface 211 of the first circuit board 21, for example. The inductors 35 and 45 and the capacitors 36 and 46 are mounted on the second main surface 212 of the first circuit board 21, for example.Note that the SW elements 301, 302, 401, and 402 are shown from the viewpoint of FIG. 4. For convenience of illustration, the current detection elements 311 to 313 and 411 to 413 and the choke coils 35 and 45 are not shown in FIGS. 4 and 5.The frame 18 is made of a heat sink material such as a metal, and the SW elements 301 to 306 and 401 to 406 are disposed to be thermally connected to the frame 18 so that heat generated by the SW elements 301 to 306 and 401 to 406 is absorbed by the frame 18, and the absorbed heat is discharged from the driving device 8 via the frame 18 and the motor housing 17. Note that the expression "A is thermally connected to B" includes that (1) A is in direct contact with B (2) A is in indirect contact with B via a heat sink element such as a heat sink gel.In FIG. 4, such heat sink elements are not shown, so that the SW elements 301 to 306 and 401 to 406 are shown separately from the frame 18. The current detection elements 311 to 313 and 411 to 413 other than the SW elements may be thermally connected to the frame 18.That is, the frame 18 serves as a heat sink, that is, both as a case member of the motor unit 10 and a heat sink. This enables downsizing of the drive system 800 and reduction in the number of components of the drive system 800 as compared with a case where an additional heat sink is disposed in the drive device 8. The first embodiment using the frame 18 as a heat sink results in a shortened heat transfer path of the driving device 8 to the outside, whereby heat from the driving device 8 can be highly efficiently dissipated.As shown in FIGS. 4 and 6, the first and second integrated circuits 56 and 57 are mounted on the first main surface 221 of the second circuit board 22, and the first and second microcomputers 51 and 52 are mounted on the second main surface 222 of the second circuit board 22.Specifically, the drive components through which currents to be supplied to the motor unit 10 flow are mounted on the first substrate 21, and the control components for controlling, for example, the SW elements mounted on the first circuit board 21 are mounted on the second substrate 22. In other words, the driving device 8 is configured such that the first circuit board 21 serving as the power circuit board and the second circuit board serving as the control circuit board are electrically and physically separated from each other. This prevents large currents to be supplied to the motor unit 10 from flowing through the second circuit board 22, thereby reducing the adverse effects of the noise caused by the large currents on the control components mounted on the second circuit board 22.The first and second circuit boards 21 and 22 further have spring terminals 26, respectively.As shown in FIGS. 3 and 4, the connector unit 70 includes a cover 71, the first and second power supply connectors 75 and 76, and the first and second signal connectors 77 and 78.The cover 71 includes a substantially cylindrical portion 711 having an openable top and a closed bottom. The bottom of the cylindrical portion 711 serves as a connector base 715. The cylindrical portion 711 has an openable top edge 712, and the edge 712 is filled in the annular groove 172 formed in the first axial end of the cylindrical housing 171 and is fixed thereto by, for example, an adhesive.The connector base 715 has first and second main surfaces that are opposed to each other; the first main surface faces the motor unit 10. The connectors 75 to 78 are disposed in the motor slide. Each of the connectors 75 to 78 is tubular, having an opening top, i.e., a hollow shape into which a not-shown wire harness can be inserted so as to be electrically connected to the connector.As shown in FIGS. 2 to 4, the first power supply connector 75 includes the power supply terminal 751 that connects between the positive pole of the first battery 39 and the first motor drive system 901, and includes the ground terminal 752 that connects between the negative pole of the first battery 39 and the common signal ground of the first motor drive system 901. The second power supply connector 76 includes the power supply terminal 761 that connects the positive pole of the second battery 49 and the second motor drive system 902, and includes the ground terminal 762 that connects the negative pole of the second battery 49 and the common signal ground of the second motor drive system 902.The first signal connector 77 serves to establish a connection between the first motor drive system 901 and the torque sensor 103, and establish a connection between the first motor drive system 901 and the on-board network. Specifically, the torque signal terminal 771 of the first signal connector 77 serves to receive the measurement signal representing the measured torque transmitted from the torque sensor 103 to the first motor drive system 901. The vehicle signal terminal 772 of the first signal connector 77 serves to receive the vehicle operation state signals externally transmitted to the first motor drive system 901 via the on-board network.Similarly, the torque signal terminal 772 of the second signal connector 78 serves to receive the measurement signal representing the measured torque transmitted from the torque sensor 103 to the second motor drive system 902. The vehicle signal terminal 782 of the second signal connector 78 serves to receive the vehicle operating condition signals sent externally over the on-board network to the second motor drive system 902.Duplication of the power supply connectors 75 and 76 provided for the first and second motor drive systems 901 and 902, respectively, might allow the motor unit 10 to be driven continuously even if one of the wires connecting the first power supply connector 75 to the first motor drive system 901 and the wires connecting the second power supply connector 76 to the second motor drive system 902 were disconnected or disconnected. Also, the motor unit 10 could be continuously driven even if one of the wires connecting the second signal connector 76 to the second motor drive system 902 were disconnected or disconnected.On the first main surface of the connector base 715, the internal signal terminals 717 are mounted. The internal signal terminals 717 connect the first and second circuit boards 21 and 22 and allow transmission of signals between the first and second circuit boards 21 and 22, The internal signal terminals 717 are arranged separately from the terminals 751, 752, 761, 762, 771, 772, 781, and 782 of the connectors 75 to 78, and are not connected to the external devices of the drive device 8 such as the batteries 39 and 49, the torque sensor 103, and the on-board network. The internal signal terminals 717 according to the first embodiment are capable of (1) transmitting values measured by the rotation detection device 1 to the electronic components including the first and second microcomputers 51 and 52 mounted on the second circuit board 22, (2) transmitting command signals transmitted from the first and second microcomputers 51 and 52 to the electronic components mounted on the first circuit board 21.The number of terminals in each of the connectors 75 to 78 may be changed, and how the terminals are arranged in each of the connectors 75 to 78 may also be changed. How the terminals are associated with the connectors 75 to 78 may also be changed. The internal signal terminals 717 may be freely arranged at any portions where the internal signal terminals 717 do not interfere with the terminals of the connectors 75 to 78. The number of internal signal terminals 717 can be freely determined.Each of the terminals 751, 752, 761, 762, 771, 772, 781, 782 and 717 is fitted by a corresponding one of the spring terminals 26 of the first circuit board 21 and / or the second circuit board 22. Each of the spring terminals 26 is elastically deformable to abut a corresponding one of the terminals 751, 752, 761, 762, 771, 772, 781, 782, and 717 when a corresponding one of the terminals 751, 752, 761, 762, 771, 772, 781, 782, and 717 is fitted into the spring terminal 26. Thereby, each of the terminals 751, 752, 761, 762, 771, 772, 781, 782, and 717 can be electrically connected to the first circuit board 21 and / or the second circuit board 22.Each of the terminals 751, 752, 761, 762, and 717 connecting the first and second circuit boards 21 and 22 penetrates the second circuit board 22 to protrude through a space between the first and second circuit boards 21 and 22 toward the first circuit board 21 in the axial direction. Each of the terminals 751, 752, 761, 762, and 717 is fitted through a corresponding one of the spring terminals 26 of the first circuit board 21 and a corresponding one of the spring terminals 26 of the second circuit board 22 so as to be connected to the first and second circuit boards 21 and 22.This reduces the length of each of the terminals 751, 752, 761, 762, and 717, and thus prevents the space necessary for arranging the terminals 751, 752, 761, 762, and 717 from increasing due to the redundancy. Each of the terminals 751, 752, 761, 762, and 717 is configured to penetrate the second circuit board 22 substantially linearly to extend to the first circuit board 21. This configuration results in each of the terminals 751, 752, 761, 762, and 717 being shorter, resulting in a decrease in the corresponding wiring impedance.Next, the rotation detection device 1 will be described.As shown in FIGS. 4, 5, and 7 to 9, the rotation detection device 1 serving to detect the rotation of the motor unit 10 includes the first sensor 61, the second sensor 62, the first microcomputer 51, and the second microcomputer 52.The first and second sensors 61 and 62 are installed in the single sensor package 65 mounted on the first circuit board 21. This reduces the area on which the single sensor package 65 is mounted, as compared to a case of single packages each including a corresponding one of the first and second sensors 61 and 62 and mounted on the first circuit board 21.As shown in FIG. 9, the first sensor 61 includes a sensor element 601 and a circuit module 610, and the sensor element 601 and the circuit module 610 are integrated into a single chip 641. In other words, in the chip 641 constituting the circuit module 610, the sensor element 601 is located. The second sensor 62 includes a sensor element 602 and a circuit module 620, and the sensor element 602 and the circuit module 620 are integrated into a single chip 642. In other words, in the chip 642 constituting the circuit module 620, the sensor element 602 is located.As shown in FIGS. 4 and 7A, the sensor package 65 of the rotation detection device 1 is mounted on the first main surface 211 of the first circuit board 21. Mounting the sensor package 65 on the first main surface 211 of the first circuit board 21 results in a shorter distance between the sensor package 65 and the magnet 16, which results in the sensor package 65 detecting the rotation of the motor unit 10 with higher accuracy and the magnet 16 having a smaller thickness and a smaller radius. As shown in FIG. 7B, the sensor package 65 may be mounted on the second main surface 212 of the first circuit board 21. By mounting the sensor package 65 on the second main surface 212 of the first circuit board 21, the first main surface 211 of the first circuit board 21 can be used efficiently. For example, mounting the sensor package 65 on the second main surface 212 of the first circuit board 21 enables electronic components other than the SW elements 301 to 306 and 401 to 406 to be mounted on the first main surface 211 while being thermally connected to the frame 18. For convenience of illustration, electronic components other than the sensor package 65 mounted on the first circuit board 21 are not shown in FIGS. 7A and 7B. Also, electronic components other than the sensor package 65 mounted on the first circuit board 21 are not shown in FIGS. 27, 28A, and 28B.As shown in FIGS. 8 and 9, the sensor package 65 has a substantially rectangular parallelepiped shape. The sensor package 65 includes a pair of longer sides and sensor terminals 67 fixed to the respective longer sides. The sensor terminals 67 include command terminals 671 and 673, output terminals 672 and 674, power supply terminals 675 and 677, and ground terminals 676 and 678.Electric power is supplied from the first and second batteries 39 and 49 to the rotation detection device 1 via a regulator, not shown, and a corresponding one of the power supply terminals 675 and 677.Specifically, the first battery 39 according to the first embodiment supplies electric power to the first sensor 61 via, for example, the power supply terminal 675, and the second battery 49 according to the first embodiment supplies electric power to, for example, the second sensor 62 via the power supply terminal 676.Each of the first embodiment and the other embodiments described below may be configured such that only one of the first and second batteries 39 and 49 supplies electric power to both the first and second sensors 61 and 62.The rotation detection device 10 is connected to the common signal ground via the ground terminals 676 and 678.As shown in FIG. 8, the chip 641 constituting the first sensor 61 and the chip 642 constituting the second sensor 62 are each fixed to a substantially rectangular plate-like lead frame 66 installed in the sensor package 65. The chips 641 and 642 are connected to the sensor terminals 67, respectively, for example, by wires. On the first main surface 211 of the first circuit board 21, a previously designed wiring pattern to which the sensor terminals 67 are connected is formed. This enables connection of the first and second sensors 61 and 62 to the first circuit board 21.The first and second sensors 61 and 62 are each a magnetic sensor for measuring a magnetic change, i.e., a change in magnetic flux, based on rotation of the magnet 16 of the motor unit 10 together with the shaft 15. The motor unit 10, i.e., the magnet 16 that rotates together with the shaft 15, serves as a detection target.The first and second sensors 61 and 62, i.e., the chips 641 and 642, are arranged symmetrically with respect to the point where the rotation center line Ac and the first circuit board 21 intersect each other. Hereinafter, the description that A and B are arranged symmetrically with respect to the point where the rotation center line Ac and the first circuit board 21 intersect with each other will be simply described as "A and B are arranged symmetrically with respect to the rotation center line Ac". The arrangement of the first and second sensors 61 and 62 symmetrically with respect to the rotation center line Ac enables reduction of measurement errors between the first and second sensors 61 and 62.As shown in FIG. 9, the circuit module 610 includes analog-to-digital (A / D) converters 613 and 614, a rotation angle calculator 615, a rotation speed calculator 616, and a communicator 617. The circuit module 620 further includes A / D converters 623 and 624, a rotation angle calculator 625, a rotation speed calculator 626, and a communicator 627.The circuit module 610 is substantially described below, since the structures and functions of the components 623, 624, 625, and 627 of the circuit module 620 are substantially identical to the structures and functions of the respective components 613, 614, 615, and 617 of the circuit module 610.The A / D converter 613 converts a measurement value of the sensor element 601, that is, measurement information indicating magnetic change of the magnet 16, into a digital measurement value, and outputs it to the rotation angle calculator 615. The A / D converter 614 converts the measurement value of the sensor element 601, that is, measurement information indicating magnetic change of the magnet 16, into a digital measurement value, and outputs it to the rotation speed calculator 615. Hereinafter, a digital measurement value after the A / D conversion is simply referred to as a measurement value of a sensor element. Note that the A / D converters 613 and 614 may be omitted as appropriate.The rotation angle calculator 615 calculates a rotation angle θm based on the measurement value of the sensor element 601. A value calculated by the rotation angle calculator 615 is not limited to the rotation angle θm itself, but information related to the rotation angle θm may be calculated as the rotation angle θm; this information enables calculation of the rotation angle θm by the first microcomputer 51 based on the information. For calculation of the rotation angle θm, the above calculations may be modified. Note that a mechanical angle is used as the rotation angle θm, but an electrical rotation angle may also be used.The rotation speed calculator 616 calculates a rotation speed TC based on the measurement value of the sensor element 601. A value calculated by the rotation speed calculator 616 is not limited to the rotation speed TC itself, but information related to the rotation speed TC may also be calculated as the rotation speed TC; this information enables calculation of the rotation speed TC by the first microcomputer 51 based on the information. Calculation of the rotational speed TC may include modification of the above calculations.For example, the first embodiment is configured to divide a rotation, i.e., a 360-degree rotation angle, of the motor unit 10 into three partial rotations, i.e., three 120-degree rotation angle ranges, and determine a predetermined first rotation direction as an up-count direction and a predetermined second rotation direction opposite to the first rotation direction as a down-count direction.The speed calculator 616 includes, for example, a hardware counter or a software counter. That is, the rotation speed calculator 616 is configured to (1) increment the current count value of the counter whenever the rotation angle θm of the motor unit 10 changes from a current rotation angle range to a rotation angle range adjacent in the count-up direction (2) decrement the current count value of the counter whenever the rotation angle θm of the motor unit 10 changes from a current rotation angle range to a rotation angle range adjacent in the count-down direction. (3) Calculate the rotational speed TC of the motor unit 10 based on the present count value of the counter.The count value of the counter itself is included in the concept of the rotational speed TC.Dividing the rotation of the motor unit 10 into three or more partial rotations enables identification of the rotation direction of the motor unit 10. dividing the rotation of the motor unit 10 into five partial rotations enables identification of the rotation direction of the motor unit 10 even when a change in the rotation angle θm of the motor unit 10 from a current rotation angle range to an adjacent rotation angle range is skipped. The rotation speed calculator 616 may be configured to calculate the rotation speed TC based on the rotation angle θm of the motor unit 10.Note that the number of rotations of the motor unit 10 in the present specification does not represent the rotational speed, i.e., the rotations per min, of the motor unit 10, but represents how many times the motor unit 10 rotates. The number of revolutions of the motor unit 10, expressed in U / min, for example, is represented as a rotational speed.The communicator 617 is configured to (1) generate an output signal including a rotation angle signal including the rotation angle θm and a rotation speed signal including the rotation speed TC, (2) output, as a frame, the output signal to the first microcomputer 51 using a predetermined digital communication interface such as a serial peripheral interface (SPI).Specifically, the first microcomputer 51 according to the first embodiment transmits an instruction to the first sensor 61 via a communication line 691 and the command terminal 671. the first sensor 61 outputs, as a frame, the output signal to the first microcomputer 51 via the output terminal 672 and a communication line 692 when receiving the instruction from the first microcomputer 51.Each frame of the output signal to be sent to the first microcomputer 51 includes, in addition to the rotation angle signal related to the rotation angle θm and the rotation speed signal related to the rotation speed TC, a running counter signal and a cyclic redundancy check (CRC) code, i.e., a CRC signal that is used as an error detection signal. In Fig. 10, the run counter signal is omitted. Another error detection signal, such as a checksum signal, may be used instead of the CRC code.The communicator 617 of the second sensor 62 is configured to (1) generate an output signal including a rotation angle signal including the rotation angle θm calculated by the rotation angle calculator 625 and a rotation speed signal including the rotation speed TC calculated by the rotation speed calculator 626 (2) output the output signal to the second microcomputer 52Specifically, the second microcomputer 52 according to the first embodiment transmits an instruction to the second sensor 62 via a communication line 693 and the instruction terminal 673. The second sensor 62 outputs the output signal to the second microcomputer 52 via the output terminal 674 and a communication line 694 when receiving the instruction.Since the first and second microcomputers 51 and 52 are mounted on the second circuit board 22, tracks of a previously designed wiring pattern and the internal signal terminals 717 serve as the communication lines 691 to 694.Note that the first and second microcomputers 51 and 52 each include a run counter whose initial count value is zero and configured to increment the count value by 1 whenever the run counter signal is transmitted thereto from the corresponding one of the first and second sensors 61 and 62. Thereby, the first and second microcomputers 51 and 52 can respectively diagnose whether communications from the corresponding one of the first and second sensors 61 and 62 to the corresponding microcomputer are normally executed.The first microcomputer 51 calculates the rotation angle θm of the motor unit 10 based on the rotation angle signal included in the output signal detected by the first sensor 61. the first microcomputer 51 controls, based on the rotation angle θm of the motor unit 10, on / off operations of the SW elements 301 to 306 of the first inverter 30 and the relays 32 and 33 to control how the motor unit 10 is driven.Further, the first microcomputer 51 calculates a steering angle θs of the steering shaft 102 based on the rotation angle signal and the rotation speed signal included in the output signal. Since the steering shaft 102 is coupled to the shaft 15 of the motor unit 10 via the deceleration gear mechanism 109, the first microcomputer 51 calculates the steering angle θs of the steering shaft 102 as a function of the rotation angle θm, the rotation speed TC, and the gear ratio of the deceleration gear mechanism 109.The second microcomputer 52 is configured to perform the same calculations as the above calculations performed by the first microcomputer 51 based on the rotation angle signal included in the output signal detected by the second sensor 62.Note that the neutral position of the steering wheel 101 is defined as the position of the steering wheel 101 when the vehicle V in which the electronic power steering device 108 is installed travels straight.For example, the first and second microcomputers 51 and 52 are each capable of learning the neutral position of the steering wheel 101 during straight traveling of the vehicle V at constant speed for a predetermined time. The first and second microcomputers 51 and 52 each store the neutral position of the steering wheel 101 therein. That is, the first and second microcomputers 51 and 52 each calculate the steering angle θs of the steering shaft 102 relative to the neutral position of the steering wheel 101 as a function of the rotation angle θm, the rotation speed TC, and the gear ratio of the deceleration gear mechanism 109. This configuration for calculating the steering angle θs of the steering shaft 102 enables steering sensors to be dispensed with.Next, it will be described how the first and second sensors 61 and 62 respectively communicate with a corresponding one of the first and second microcomputers 51 and 52 with reference to reference numerals (A) to (E) in FIG. 10. The reference sign (Y) in FIG. is as follows. X as FIG. XY.FIG. 10A shows the rotation angle θm of the motor unit 10 periodically detected by the first sensor 61, and FIG. 10B shows the rotation speed TC of the motor unit 10 periodically detected by the first sensor 61. FIG. 10C shows the output signal periodically output from the first sensor 61 to the first microcomputer 51, and FIG. 10D shows the command signal periodically transmitted from the first microcomputer 51 to the first sensor 61. FIG. 10E shows how the first microcomputer 51 calculates the rotation angle θm and the steering angle θs.In the following, with reference to FIGS. 10A to 10E, only how the first sensor 61 communicates with the first microcomputer 51 and not how the second sensor 62 communicates with the second microcomputer 52 will be described, because the communication of the second sensor 62 with the second microcomputer 52 substantially proceeds as the communication of the first sensor 61 with the first microcomputer 51.As shown in FIG. 10A, the first microcomputer 51 updates the rotation angle θm in a predetermined update period DRT_sa. FIG. 10A shows pulses at constant intervals each corresponding to the update period DRT_sa; the width of each pulse in FIG. 10A represents the calculation period required by the rotation angle calculator 615 to perform update of the rotation angle θm.Specifically, the width, i.e., the time period, of each pulse in FIG. 10A includes a first half period Px 1 and a second half period Px 2. The A / D converter 613 converts a value measured by the sensor element 601 into a digital measurement value during the first half period, and the rotation angle calculator 615 calculates a value of the rotation angle θm based on the digital measurement value, and thus updates the measurement data for the rotation angle θm during the second half period Px 2. FIG. 10A shows that the measurement data for the rotation angle θm is updated in the order of the values 1A, 2A,..., and 11A. Note that FIG. 10A shows the first and second half periods Px 1 and Px 2 as the calculation period of the data 1A, but they may be applied to each of the other data 2A to 11A.As shown in FIG. 10B, the first microcomputer 51 updates the rotation speed TC of the motor unit 10 in a predetermined update period DRT_sb. The width of each pulse shown in FIG. 10B represents the calculation time period required by the rotation speed calculator 616 to perform an update of the rotation speed TC.Specifically, the width, i.e., the time period, of each pulse of FIG. 10B includes a first half period Py 1 and a second half period Py 2. The A / D converter 614 converts a value measured by the sensor element 601 into a digital measurement value during the first half period Py 1, and the rotation speed calculator 616 calculates a value of the rotation speed TC based on the digital measurement value, and thus updates the measurement data for the rotation speed TC during the second half period Py 2. FIG. 10B shows that the measurement data for the rotational speed TC is updated in the order of the values 1B, 2B,..., and 11B. Note that FIG. 10B shows the first and second half periods Py 1 and Py 2 as the calculation period of the data 1B, but they may be applied to each of the other data 2B to 11B.That is, in each of FIGS. 10A, 11A, 15A, and 29A, each pulse nA (n is an arbitrary natural number) represents the corresponding measurement data for the rotation angle θm and the corresponding rotation angle signal, and in each of FIGS. 10B, 11B, 15B, and 29B, each pulse nB (n is an arbitrary natural number) represents the corresponding measurement data for the rotation speed TC and the corresponding rotation speed signal.FIGS. 10A and 10B show that the update period DRT_sa of the rotation angle θm is equal to the update period DRT_sb of the rotation speed TC and shorter than a calculation period DRT_m of the first microcomputer 51 described later.As shown in FIGS. 10C and 10D, the first microcomputer 51 sends a command signal com 1 to the first sensor 61 at time x 11. the command signal com 1 requests transmission of the output signal at the next transmission time of the next command signal. The communicator 617 transmits, at time x 11, the output signal Sd 10 requested by the immediately previous command signal com 0 (not shown) to the first microcomputer 51; time x 11 represents the reception time of the command signal com 1.That is, the output signal Sd 10 includes the rotation angle θm based on the latest measurement data, the rotation speed TC based on the latest measurement data, and the CRC signal.Specifically, the output signal Sd 10 includes (1) the latest measurement data, i.e., the rotation angle signal, 1A for the rotation angle θm including a predetermined number of bits (2) the latest measurement data, i.e., the rotation speed signal, 1B for the rotation speed TC including a predetermined number of bits (3) the CRC code including a predetermined number of bits calculated based on the latest rotation angle signal 1A of the rotation angle θm and the latest rotation speed signal 1B of the rotation speed TCThe first microcomputer 51 starts, at time x 12, calculation of the rotation angle θm and the steering angle θs based on the rotation angle signal and the rotation speed signal included in the output signal Sd 10. In FIG. 10E, reference numeral [1A, 1B] denotes that the measurement data 1A and the measurement data 1B are used to calculate the rotation angle θm and the steering angle θs. Note that there is no need for the first microcomputer 51 to calculate the steering angle θs every time the output signal is sent to the first microcomputer 51. That is, the first microcomputer 51 calculates the steering angle θs in a predetermined calculation period DRT_m that is longer than the update periods DRT_sa and DRT_sb, but can calculate the steering angle θs at a rate of one calculation per a predetermined number of the calculation periods DRT_m.When the first microcomputer 51 sends a command signal com 2 to the first sensor 61 at time x 13, the first sensor 61 sends the output signal Sd 11 including the rotation angle signal based on the measurement data 4A including the rotation angle θm, the rotation speed signal based on the measurement data 4B including the rotation speed TC, and the CRC signal to the first microcomputer 51. The first microcomputer 51 starts to calculate, at time x 14, a calculation of the rotation angle θm and the steering angle θs based on the rotation angle signal 4A and the rotation speed signal 4B included in the output signal Sd 11.When the first microcomputer 51 sends a command signal com 3 to the first sensor 61 at time x 15, the first sensor 61 sends the output signal Sd 12 including the rotation angle signal based on the measurement data 8A including the rotation angle θm, the rotation speed signal based on the measurement data 8B including the rotation speed TC, and the CRC signal to the first microcomputer 51.FIGS. 11A to 11E corresponding to the respective ones of FIGS. 10A to 10E show how the first and second sensors 61 and 62 communicate with the first and second microcomputers 51 and 52, respectively, when the update periods DRT_sa and DRT_sb are set differently. Specifically, the update period DRT_sb of the rotation speed TC may be set longer than the update period DRT_sa of the rotation angle θm. The update period DRT_sa of the rotation angle θm needs to be sufficiently shorter than the calculation period DRT_m of the first microcomputer 51. In contrast, the update period DRT_sb of the rotation speed TC may be set to an appropriate period depending on the predetermined rotation speed of the motor unit 10; the appropriate period is appropriate to prevent skipping of the detection of each of the divided three rotation angle ranges, because reliable detection of each of the divided three rotation angle ranges enables detection of the rotation speed of the motor unit 10, so that erroneous detection of the rotation speed of the motor unit 10 is prevented. Note that the predetermined rotational speed of the motor unit 10 may be set to the maximum rotational speed of the motor unit 10 or a predetermined value required to count the rotational speed TC.As shown in FIGS. 11C and 11D, at time x 11 like the operation of the first sensor 61, at time x 21, the first sensor 61 transmits the output signal Sd 20 including the rotation angle signal based on the measurement data 1A and the rotation speed signal based on the measurement data 1B to the first microcomputer 51. According to the operation of the first microcomputer 51 at time x 12, the first microcomputer 51 starts calculation of the rotation angle θm and the steering angle θs at time x 22 based on the output signal Sd 20.When the first microcomputer 51 sends the command signal com 2 to the first sensor 61 at time x 23, the first sensor 61 transmits the output signal Sd 21, which includes the rotation angle signal based on the measurement data 4A and the rotation speed signal based on the measurement data 4B, to the first microcomputer 51 at time x 23.According to the operation of the first microcomputer 51 at time x 14, the first microcomputer 51 starts calculation of the rotation angle θm and the steering angle θs at time x 24 based on the output signal Sd 22.When the first microcomputer 51 sends the command signal com 3 to the first sensor 61 at time x 25, the first sensor 61 transmits, to the first microcomputer 51, the output signal Sd 22 including the rotation angle signal based on the measurement data 8A and the rotation speed signal based on the measurement data 4B for the rotation speed TC at time x 25.In contrast, Figs. 29A to 29E corresponding to the respective ones of Figs. 10A to 10E show, as in a comparative example, a rotation angle sensor for detecting the rotation angle of a motor and a rotation speed sensor for detecting the rotation speed of the motor, which are disposed on first and second chips separate therefrom, respectively, with a microcomputer. That is, in this comparative example, the rotation angle sensor, i.e., the first chip, and the rotation speed sensor, i.e., the second chip, alternately output the rotation angle signal and the rotation speed signal. Note that the update period DRT_sa and the update period DRT_sb are set identically to those shown in FIG. 11.As shown in FIGS. 29C and 29D, at time x 91, the rotation angle sensor transmits the output signal Sd 91 including the rotation angle signal based on the measurement data 1A but not including the rotation speed signal in response to a command signal com 0 c, not shown, immediately before the command signal com 1 ctransmitted from the microcomputer.The microcomputer calculates, at time x 92, the rotation angle θm and the steering angle θs on the basis of the measurement data 1A included in the output signal Sd 91 and the measurement data 1B included in the immediately previous output signal Sd 90 (not shown) transmitted at the transmission time of the command signal com 0 c.When the microcomputer sends a command signal com2c to the rotation speed sensor at time x93, the rotation speed sensor transmits the output signal Sd92 including the rotation speed signal based on the measurement data 3B. Further, when the microcomputer sends a command signal com 3 cto the rotation angle sensor at time x 94, the rotation angle sensor transmits the output signal Sd 93 including the rotation angle signal based on the measurement data 8A.The microcomputer calculates the rotation angle θm and the steering angle θs at time x 95 based on the measurement data 8A included in the output signal Sd 93 and the measurement data 3B included in the output signal Sd 92.As described above, this comparative example is configured such that the rotation angle sensor used for detecting the rotation angle θm and the rotation speed sensor used for detecting the rotation speed TC are arranged separately from each other. As a result, the rotation angle signal and the rotation speed signal are individually output to the microcomputer. For this reason, the length Tdc of the period between the detection timing of the rotation angle signal and the detection timing of the rotation speed signal used for calculation at the timing x95, for example, may become longer than the transmission period of the command signals from the microcomputer.That is, this comparative example having the longer period between the individual detection timing of the rotational angle θm and a corresponding detection timing of the rotational speed signal TC may result in an incorrectly calculated steering angle θs.In contrast, the rotation detection device 1 according to the first embodiment is configured such that the rotation angle calculator 614 and the rotation angle calculator 615 are integrated into the single chip 641, and is configured to transmit the output signal including a series of the rotation angle signal and the rotation speed signal from the communicator 617 to the first microcomputer 51.For this reason, as shown in FIGS. 10A to 10E, when the measurement data for the rotation angle θm and the measurement data for the rotation speed TC are periodically acquired in synchronization with each other, the first microcomputer 51 is adapted to calculate the rotation angle θm, the rotation speed TC, and the steering angle θs on the basis of the measurement data for the rotation angle θm and the measurement data for the rotation speed TC in accordance with the measurement values measured simultaneously, i.e., in synchronization.Further, as shown in FIGS. 11A to 11E, even when the update period DRT_sa and the update period DRT_sb are different from each other, the rotation detection device 1 is configured to transmit the set output signal including a sequence of the latest measurement data and the latest measurement data to the first microcomputer 51. This configuration enables the length Td of the period between the acquisition timing of the measurement data for the rotation angle θm and the acquisition timing of the measurement data for the rotation speed TC to be shorter than the command period of the first microcomputer 51. This configuration therefore reduces the time period between the acquisition timing of the measurement data for the rotation angle θm and the acquisition timing of the measurement data for the rotation speed TC, as compared with the comparative example that individually outputs the rotation angle signal based on the rotation angle θm and the rotation speed signal based on the rotation speed TC.The rotation detection device 1 according to the first embodiment is configured to transmit the set output signal including a sequence of the rotation angle signal and the rotation speed signal to the first microcomputer 51 via the single communication line 692. This configuration enables a reduction in the number of communication lines connecting the first microcomputer 51 to the rotation detection device 1, as compared with a case where the rotation angle signal and the rotation speed signal become the first microcomputer 51 individually via separate communication lines.As described above, the driving device 8 according to the first embodiment configured as a dual redundant system as described above is incorporated into the electronic power steering device 108. Since the electronic power steering device 108 controls the steering function of the vehicle V as one of the basic functions of the vehicle V, the dual-redundant configuration of the drive device 8 enables continuous assistance of the driver's operation of the steering wheel 101 even if one of the dual-redundant portions of the drive device 8 does not function properly.Specifically, the rotation detection device 1 includes the duplicated circuit modules 610 and 620 each configured to calculate the rotation angle θm and the rotation speed TC. This configuration enables the assist operations of the electronic power steering device 108 to be continuously performed even when one of the duplicated circuit modules 610 and 620 fails to function properly.Further, the rotation detection device 1 is configured such that the duplicated circuit modules 610 and 620 are each integrated in a corresponding one of the single chips 641 and 642, resulting in downsizing of the rotation detection device 1. This contributes to downsizing of the driving device 8, resulting in enlargement of the passenger compartment in the passenger compartment of the vehicle V and improvement of the fuel economy of the vehicle V.As described above in detail, the rotation detection device 1 of the first embodiment includes the first sensor 61, the second sensor 62, the first microcomputer 51, and the second microcomputer 52.The first sensor 61 includes the sensor element 601 and the circuit module 610, and the second sensor 62 includes the sensor element 602 and the circuit module 620.Each of the sensor elements 601 and 602 is configured to detect rotation of the motor unit 10.The circuit module 610 includes the rotation angle calculator 615, the rotation speed calculator 616, and the communicator 617. The rotation angle calculator 615 calculates the rotation angle θm of the motor unit 10 based on the measurement value of the sensor element 601. The rotation speed calculator 615 calculates the rotation speed TC of the motor based on the measurement value of the sensor element 601. The communicator 617 generates an output signal including a sequence of the rotation angle signal that is a signal related to the rotation angle θm and the rotation speed signal that is a signal related to the rotation speed TC. Subsequently, the communicator 617 transmits the set output signal to the first microcomputer 51.The circuit module 620 includes the rotation angle calculator 625, the rotation speed calculator 626, and the communicator 627. The rotation angle calculator 625 calculates the rotation angles θm of the motor unit 10 based on the measurement value of the sensor element 602. The rotation speed calculator 625 calculates the rotation speed TC of the engine based on the measurement value of the sensor element 602. The communicator 627 generates an output signal including a result of the rotation angle signal that is a signal related to the rotation angle θm and the rotation speed signal that is a signal related to the rotation speed TC. Subsequently, the communicator 627 transmits the set output signal to the second microcomputer 52.The sensor package 65 is configured such that the sensor elements 601 and 602 and the circuit modules 610 and 620 are sealed therein, i.e., housed therein. The sensor package 65 is mounted on the first circuit board 21 separately from the first and second microcomputers 51 and 52.Specifically, the first embodiment provides the circuit modules 610 and 620, each including the function of calculating the rotation angle θm and the function of calculating the rotation speed TC. This enables, even if one of the circuit modules 610 and 620 fails to function properly, the other one of the circuit modules 610 and 620 to continuously calculate the rotation angles θm and the rotation speed TC. The sensor package 65 is configured such that the sensor elements 601 and 602 and the circuit modules 610 and 620 are housed therein separately from the package of the first and second microcomputers 51 and 52. This makes it possible, for example, to mount the first and second microcomputers 51 and 52 on the second circuit board 22 that is separate from the first circuit board 21 on which the rotation detection device 1 is mounted, resulting in greater flexibility in arrangement of the elements on the first and second circuit boards 21 and 22.FIG. 30 schematically shows a rotation detection device 655 as a reference example. The rotation detecting device 655 includes packs 656 and 657 that calculate the rotation angle θm and packs 658 and 659 that calculate the rotation speed TC; the packs 656 to 659 are mounted on the first circuit board 21, the packs 656 and 657 being separated from the packs 658 and 659.Compared with the structure of the rotation detection device 655, the rotation detection device 1 according to the first embodiment is configured to reduce the area of the sensor package 65 on the first substrate 21. This configuration ensures a mounting surface of, for example, the first main surfaces 211 of the first circuit board 21 on which components are to be mounted; among these components, such as the SW elements 301 to 306 and 401 to 406, heat needs to be dissipated. Further, this configuration also enables the first and second sensor elements 601 and 602 to be disposed close to the rotation center line Ac. This arrangement results in downsizing of the magnet 16 and prevents deterioration of the detection accuracy of the rotation detection device 1.The sensor elements 601 and 602 and the circuit modules 610 and 620 are all installed in the single package 65, resulting in downsizing of the rotation detection apparatus 1The first and second sensor elements 601 and 602 are arranged symmetrically with respect to the rotation center line Ac. This arrangement enables reduction of measurement errors between the first and second sensor elements 601 and 602.The sensor element 601 and the circuit module 610 are housed in the same chip 641. Accommodating the sensor element 601 and the circuit module 610 in the same single chip enables further downsizing of the rotation detection apparatus 1.The first circuit board 21 on which the sensor package 65 is mounted and the second circuit board 22 disposed above the first circuit board 21 of the motor unit 10 are connected to each other by the inner connection terminals 717 of the connector unit 70. The first one of the second microcomputers 51 and 52 is mounted on the second circuit board 22. The rotation angle signal and the rotation speed signal measured by the first and second sensors 61 and 62, respectively, are transmitted to the corresponding one of the first and second microcomputers 51 and 52 via the corresponding inner connection ports 717. This enables appropriate transmission of the rotation angle signal and the rotation speed signal transmitted through the first and second sensors 61 and 62, respectively, to the corresponding one of the first and second microcomputers 51 and 52.The communicator 617 transmits an output signal to the first microcomputer 51 in response to the corresponding rotation angle signal and the corresponding rotation speed signal using the single communication line 692. Also, the communicator 617 transmits, to the first microcomputer 51, an output signal including the response to the corresponding rotation angle signal and the corresponding rotation speed signal to the first microcomputer 51 using the single communication line 693.Since the rotation angle signal and the rotation speed signal are included in the output signal, it is possible to output the rotation angle signal and the rotation speed signal calculated by the first and second sensors 61 and 62 by communication to the corresponding one of the first and second microcomputers 51 and 52. This results in a decrease in the deviation between the measurement value of the rotational angle θm and the measurement value of the rotational speed TC. The single communication line 692 enables transmission of the rotation angle signal and the rotation speed signal from the communicator 617 to the first microcomputer 51.These configurations result in a smaller number of communication lines as compared with a case where communication lines are provided for the respective rotation angle signal and rotation speed signal.The electronic power steering device 108 includes the motor unit 10, the rotation detection device 1, and the first and second microcomputers 51 and 52. The first and second microcomputers 51 and 52 are each configured to control the motor unit 10 based on the individual transmitted sets of the rotation angle signal and the rotation speed signal. The sensor elements 601 and 602 each detect rotation of the motor unit 10 as a detection target.The first embodiment provides a single chip by integrating the calculation function of the rotation angle θm and the calculation function of the rotation speed TC, thereby downsizing the rotation detection apparatus 1. This contributes to downsizing of the electronic power steering apparatus 108.The first and second microcomputers 51 and 52 are each configured to calculate the steering angle θs of the steering shaft 102 based on the rotation angle θm and the rotation speed TC included in the corresponding output signal. This configuration enables elimination of a steering sensor for measuring the steering angle θs using, for example, a gear fixed on the steering shaft 102.Second EmbodimentNext, the second embodiment of the present invention will be described with reference to FIGS. 12 and 13. The second embodiment includes a rotation detection device 2 different from the rotation detection device 1 according to the first embodiment in the following points. Hereinafter, substantially the different points will be described, and the parts common in the first and second embodiments will be omitted or simplified.As shown in FIG. 12, the rotation detection device 2 includes a first sensor 261 and a second sensor 262.The first sensor 261 includes a sensor element 603 for measuring the rotation angle of the motor unit 10, a sensor element 604 for measuring the rotation speed of the motor unit 10, and the circuit module 610. The sensor elements 603 and 604 and the circuit module 610 are integrated in the single chip 641.The second sensor 262 includes a sensor element 605 for measuring the rotation angle of the motor unit 10, a sensor element 606 for measuring the rotation speed of the motor unit 10, and the circuit module 620. The sensor elements 605 and 606 and the circuit module 620 are integrated into the single chip 642. As in the third to sixth embodiments described below, the first and second chips 641 and 642 are incorporated in the single sensor package 65.The sensor elements 603 to 606 are each a magnetic measurement device such as a Hall device for measuring a magnetic change, i.e., a change in magnetic flux caused by rotation of the magnet 16.The A / D converter 613 converts a measurement value of the sensor element 603 into a digital measurement value and outputs it to the rotation angle calculator 615. The A / D converter 614 converts the measurement value of the sensor element 604 into a digital measurement value and outputs it to the speed calculator 616.Accordingly, the A / D converter 623 of the second sensor 262 converts a measurement value of the sensor element 605 into a digital measurement value, and thus outputs it to the rotation angle calculator 625. The A / D converter 624 converts the measurement value of the sensor element 606 into a digital measurement value and thus outputs it to the speed calculator 616.Communications between the first sensor 261 and the first microcomputer 51 are performed in the same manner as the communications between the first sensor 61 and the first microcomputer 51 according to the first embodiment. Communications between the second sensor 262 and the second microcomputer 52 are performed in the same manner as the communications between the second sensor 62 and the second microcomputer 52 according to the first embodiment.That is, the sensor elements 603 and 605 for detecting the rotation angle θm and the sensor elements 604 and 606 for detecting the rotation speed TC are separately arranged. This enables selection of a sensor element suitable for measuring the rotation angle θm and a sensor element suitable for measuring the rotational speed TC. For example, a sensor element having higher measurement accuracy may be used for each of the sensor elements 603 and 605 for measuring the rotation angle θm. In contrast, a sensor element that requires lower electric power may be used for each of the sensor elements 604 and 606 to measure the rotational speed TC.FIGS. 13A and 13B each show an example of how the sensor elements 603 to 606 are arranged in the package 65.As shown in FIGS. 13A and 13B, the sensor elements 603 and 605 are arranged symmetrically with respect to the rotation center line Ac. Similarly, the sensor elements 604 and 606 are arranged symmetrically with respect to the rotation center line Ac.Specifically, as shown in FIG. 13A, the sensor element 603 is disposed closer to the rotation center line Ac than the sensor element 604. That is, with respect to the rotation center line Ac, the sensor element 603 is disposed on the inner side of the chip 641, and the sensor element 604 is disposed on the outer side of the chip 641. Also, as shown in FIG. 13A, the sensor element 605 is disposed closer to the rotation center line Ac than the sensor element 606. That is, with respect to the rotation center line Ac, the sensor element 605 is disposed on the inner side of the chip 642, and the sensor element 606 is disposed on the outer side of the chip 642.That is, the sensor elements 603 and 605 for measuring the rotation angle θm requiring higher measurement accuracy are arranged closer to the rotation center line Ac, resulting in reduction of measurement errors. In contrast, the sensor elements 604 and 606 for measuring the rotational speed TC whose measurement accuracy is not as high as that of the sensor elements 603 and 605 are disposed closer to the rotation center line Ac.Further, as shown in FIG. 13B, the sensor elements 603 and 604 may be arranged parallel to the transverse direction of the lead frame 66 so as to face the rotation center line Ac in the chip 641. Also, the sensor elements 605 and 606 are arranged parallel to the transverse direction of the lead frame 66 so as to face the rotation center line Ac in the chip 642. As a result, the sensor elements 603 and 605 for measuring the rotation angle θm are arranged symmetrically to the rotation center line Ac, and the sensor elements 604 and 604 for measuring the rotation speed TC are arranged symmetrically to the rotation center line Ac.Similarly to the first embodiment, the rotation angle calculator 615 calculates the rotation angle θm based on a measurement value measured by the sensor element 603. The rotation speed calculator 616 calculates the rotation speed TC based on a rotation speed TC detected by the sensor element 606. Measured Value. In other words, the rotation angle θm and the rotation speed TC are calculated based on the measurement values measured by the different sensor elements. As a result, the same advantageous effects as those of the first embodiment can be obtained by the second embodiment.Third EmbodimentNext, the third embodiment of the present invention will be described with reference to FIGS. 14 and 15.As shown in FIG. 14, a rotation detection device 3 includes a first sensor 361 and a second sensor 362.The first sensor 361 includes a circuit module 611. The circuit module 611 includes a self-diagnosis unit 618 in addition to the components of the circuit module 610 of the first embodiment. The second sensor 362 includes a circuit module 621. The circuit module 621 includes a self-diagnosis unit 628 in addition to the components of the circuit module 620 of the first embodiment. The sensor element 601 and the circuit module 611 are integrated in the single chip 641, and the sensor element 602 and the circuit module 621 are integrated in the single chip 642. Similar to the second embodiment, different sensor elements can be used for measuring the rotation angle θm and the rotational speed TC, respectively.The self-diagnosis unit 618 is configured to diagnose whether there is a malfunction in the first sensor 361. Specifically, the self-diagnostic unit 618 is configured to monitor whether a power supply fault including a power failure and a ground fault is present in any one of the sensor elements 601, the A / D converters 613 and 614, the rotation angle calculator 615, and the rotation speed calculator 616. Accordingly, the self-diagnosis unit 628 is configured to diagnose whether a malfunction occurs in the second sensor 362. Specifically, the self-diagnostic unit 628 is configured to monitor whether a power supply fault including a power failure and a ground fault is present in any one of the sensor elements 602, the A / D converters 623 and 624, the rotation angle calculator 625, and the rotation speed calculator 626.The self-diagnosis units 618 and 628 are each configured to include, as a status signal, the self-diagnosis result in the corresponding output signal and output the output signal to the corresponding one of the first and second microcomputers 51 and 52. The status signal according to the first embodiment corresponds to a malfunction signal.Figs. 15A to 15E corresponding to Figs. 11A to 11E, respectively, branch how the first sensor 361 communicates with the first microcomputer 51. Since communication timings shown in Figs. 15A to 15E are substantially identical to the communication timings shown in Figs. 11A to 11E, it will be described below how the first sensor 361 changes the output signal which should be transmitted therefrom in response to a command signal sent from the first microcomputer 51.Similarly to the first embodiment, the following describes only how the first sensor 361 communicates with the first microcomputer 51, but does not describe how the second sensor 362 communicates with the second microcomputer 52, because the manner of communicating the second sensor 362 with the second microcomputer 52 is substantially identical to that of the first sensor 361 with the first microcomputer 51.The first sensor 361 according to the first embodiment is configured to change the kinds of information included in the output signal depending on the kind of the command signal transmitted from the first microcomputer 51.When the first microcomputer 51 transmits a command signal com_a at time x 31, the communicator 617 transmits an output signal Sd_a, which is the reception time of a next command signal S_b, to the first microcomputer 51 at time x 32; the output signal Sd_a includes information corresponding to the command signal com_a, i.e., the rotation angle signal, the rotation speed signal, the status signal, and the CRC signal. Note that the command signal transmitted at the output timing of the output signal Sd_a may output an output of any type of signal.When the first microcomputer 51 transmits a command signal com_b at time x 32, the communicator 617 transmits, at time x 33, which is the reception time of a next command signal, the output signal Sd_b corresponding to the command signal com_b to the first microcomputer 51; the output signal Sd_b includes the rotation angle signal, the rotation speed signal, and the CRC signal without the status signal.When the first microcomputer 51 transmits a command signal com_c at time x 33, the communicator 617 transmits, at time x 34 that is the reception time of a next command signal, the output signal Sd_c corresponding to the command signal com_c to the first microcomputer 51; the output signal Sd_c includes the rotation angle signal, the status signal, and the CRC signal without the rotation speed signal and the status signal.When the first microcomputer 51 transmits a command signal com_d at time x 34, the communicator 617 transmits, at time x 35 which is the reception time of a next command signal, the output signal Sd_d corresponding to the command signal com_d to the first microcomputer 51; the output signal Sd_d includes the rotation angle signal and the CRC signal without the rotation speed signal and the status signal.FIGS. 15A to 15E show an example of that the command signals com_a, com_b, com_c, and com_d are sent from the first microcomputer 51 in this order, and the output signals Sd_a, Sd_b, Sd_c, and Sd_d are sent from the first sensor 361 in this order. The order of transmission of the command signals com_a, com_b, com_c, and com_d may be changed, so that the corresponding order of the output signals Sd_a, Sd_b, Sd_c, and Sd_d may also be changed. The first microcomputer 51 may be configured to (1) transmit the command signals com_a, com_b, and com_c in each of the rotation speed transmission periods and in each of the status signal transmission periods, thereby obtaining the rotation speed signal for each of the rotation speed transmission periods and the status signal for each of the status signal transmission periods (2) transmit the command signals com_d at other timings, respectively. The first microcomputer 51 cannot use the command signals com_b and com_c when the rotation speed transmission period and the status signal transmission period are identical.The first microcomputer 51 may be configured to transmit, instead of the command signal com_d, any one of the command signals com_a, com_b, and com_c periodically no longer than when the first microcomputer 51 needs acquisition of the rotation speed TC or the self-diagnosis result in the first sensor 361.In obtaining the output signal, the first microcomputer 51 performs a calculation task defined based on the obtained output signal. FIG. 15E shows that the time periods required to perform the computation tasks are the same. However, they may be set differently from each other.The third embodiment describes an example in which the self-diagnosis unit 618 is provided. However, it is possible to change the kinds of signals included in the output signal depending on the kind of the command signal.Specifically, the first sensor 61 not including the self-diagnostic unit 618 is configured to transmit the output signal Sd_b including the rotation angle signal and the rotation speed signal in response to the command signal com_b and transmit the output signal Sd_d including the rotation angle signal in response to the command signal com_d.Thereby, each of the communicators 617 and 627 can transmit an output signal that satisfies a request from a corresponding one of the first and second microcomputers 51 and 52. The third embodiment further includes the self-diagnostic units 618 and 628. The self-diagnosis units 618 and 628 are each configured to output the malfunction diagnosis result to a corresponding one of the first and second microcomputers 51 and 52. With this configuration, the first microcomputer 51 can prevent calculation based on the output signal when the output signal contains an abnormal self-diagnosis result.Fourth EmbodimentNext, the fourth embodiment of the present invention will be described with reference to FIG. 16.As shown in FIG. 16, a rotation detection device 4 includes a first sensor 461 and a second sensor 462. The sensor element 601, the sensor element 607, and the circuit module 612 are housed in the single chip 641. As with the first sensor 461, the two sensor elements and the circuit module are integrated in the single chip 642.The circuit module 612 of the first sensor 461 includes, in addition to the components of the circuit module 611 of the third embodiment, the sensor element 607, A / D converters 633 and 634, a rotation angle calculator 635, and a rotation speed calculator 636.The sensor element 601, the A / D converters 613 and 614, the rotation angle calculator 615, and the rotation speed calculator 616 constitute a rotation information calculator 951. The sensor element 607, the A / D converters 633 and 634, the rotation angle calculator 635, and the rotation speed calculator 636 constitute a rotation information calculator 952.That is, the first sensor 461 includes a pair of the rotation information calculator 951 and the rotation information calculator 952.Accordingly, the second sensor 462 includes a pair of a rotation information calculator 953 and a rotation information calculator 954. In contrast, the first and second sensors 61 and 62 each include a single rotation information calculator according to the first embodiment, for example.The self-diagnosis unit 618 is configured to detect, in addition to power supply errors including a power failure and a ground fault, an internal fault in the first sensor 461 by comparing first calculation results, i.e., first calculated values obtained by the rotation information calculator 951, with the corresponding second calculation results, i.e., the second calculated values obtained by the rotation information calculator 952. Such an internal error represents an error that occurred even though the first and second calculation results are each in a normal range. For example, an offset error representing the difference between each of the first calculated values and a corresponding one of the second calculated values and exceeding a predetermined range is a typical example of such an internal error.The self-diagnostic unit 618 is configured to include an internal fault in the output signal as the status signal and then transmit the output signal to the first microcomputer 51.Note that, instead of the comparison between the first and second calculated values obtained by the respective rotation information calculators 951 and 952, the rotation angle signal and the rotation speed signal obtained by each of the rotation information calculators 951 and 952 may be transmitted to the first microcomputer 1. Further, the first microcomputer 51 may be configured to compare the first calculated value calculated by the rotation information calculator 951 with the corresponding calculated value calculated by the rotation information calculator 952, thereby determining whether there is an internal fault in the first sensor 461.Similarly to the second embodiment, a sensor element for detecting the rotation angle θm of the motor unit 10 and a sensor element for detecting the rotation speed TC of the motor unit 10 may be separately disposed. In this modification, the number of sensor elements in the first and second sensors 461 and 462 becomes four, respectively, resulting in eight sensor elements arranged in the rotation detection device 4.As described above, the rotation detection device 4 includes the rotation information calculators 951 and 952 for the single communicator 617. This enables detection of an internal error such as an offset error.As a result, the same advantageous effects as those of the first embodiment can be obtained by the fourth embodiment.Fifth EmbodimentNext, the fifth embodiment of the present invention will be described with reference to FIGS. 17 and 18.The electronic power steering device 108 is turned off when a start switch, i.e., an ignition switch, is open. As a result, no current is supplied to the first and second microcomputers 51 and 52, so that the first and second microcomputers 51 and 52 cannot perform computations or communication with other devices.The rotation detection device 1 according to the fifth embodiment is configured such that the first and second batteries 39 and 49 directly supply electric power thereto even when the electronic power steering device 108 is turned off.Specifically, the first battery 39 is configured to directly supply electric power to the first sensor 61 and the second battery 49 is configured to supply electric power to the second sensor 62 while the electronic power steering device 108 is deactivated.This enables the above-described calculations to be continuously performed by the rotation detection device 1 even when the electronic power steering device 108 is stopped.For example, the following describes how the first microcomputer 51 calculates the steering angle θs.As described above, the steering angle θs is calculated as a function of the rotation angle θm, the rotational speed TC, and the gear ratio of the deceleration transmission mechanism 109. While the electronic power steering device 108 is deactivated, an operation of the steering wheel 101 by the driver causes the steering shaft 102 to rotate, so that the motor unit 10 is rotated via the deceleration gear mechanism 109. At this time, if the rotational speed TC were not counted, the steering angle θs could not be calculated until re-learning of the neutral position of the steering wheel 101 was completed. Note that calculation of the steering angle θs requires information on the rotational position of the motor unit 10 corresponding to the rotational angle θm based on the number of rotations of the motor unit 10, so that calculation of the steering angle θs requires an immediate value of the rotational angle θm at the restart of the electronic power steering device 108. For this reason, it is not necessary to continuously calculate the rotation angle θm while the electronic power steering device 108 is deactivated.In view of these circumstances, the rotation detection device 1 according to the fifth embodiment is configured to be directly supplied with electric power from the first and second batteries 39 and 49. Thereby, the rotation detection device 1 can continuously perform at least calculation of the rotational speed TC while the electronic power steering device 108 is deactivated. Note that the fifth embodiment may also be configured such that the rotation detection device 1 can continuously perform calculation of the rotation angle θm of the motor unit 10 while the electronic power steering device 108 is deactivated. Preferably, the rotation detection device 1 is configured to continuously perform calculation of the rotation angle θm while the electronic power steering device 108 is deactivated in terms of power consumption.Note that the rotation detection device 1 stores the counted rotation speed TC therein without communication with the first and second microcomputers 51 and 52 because the first and second microcomputers 51 and 52 are deactivated. Subsequently, after restarting the electronic power steering device 108, the rotation detection device 1 sends, to each of the first and second microcomputers 51 and 52, the output signal including the rotation angle signal and the counted rotation speed TC stored therein in response to the command signal transmitted from the corresponding microcomputer. This enables each of the first and second microcomputers 51 and 52 to calculate the steering angle θs of the steering wheel 101 appropriately upon restarting the electronic power steering device 108 without releaving the neutral position of the steering wheel 101.Note that FIG. 17 describes the fifth embodiment based on the rotation detection device 1 according to the first embodiment as an example. However, it may be described based on any one of the rotation detection devices 2 to 4 according to the second to fourth embodiments. This can be applied to the following sixth embodiment.Next, the rotation information calculation task according to the fifth embodiment will be described in detail with reference to the flowchart of FIG. 18. Although only the rotation information calculation task performed by the first sensor 61 is described below, the same rotation information calculation task may be performed by the second sensor 62.In the first step S 101, the first sensor 61 determines whether the electronic power steering device 108 is operating. In FIG. 18, the electronic power steering apparatus is abbreviated as "EPS". For example, it is possible to determine that the electronic power steering device 108 is not operating when clock signals and / or command signals have not been sent thereto from the first microcomputer 51 during a predetermined period of time.When it is determined that the electronic power steering device 108 is not operating (NO in step S 101), the rotation information calculation task proceeds to step S 104. Otherwise, when it is determined that the electronic power steering device 108 is operating (YES in step S 101), the rotation information calculation task proceeds to step S 102.In step S 102, the first sensor 61 calculates the rotation angle θm and the rotation speed TC.In step S 103, the circuit module 610 outputs the output signal to the first microcomputer 51 in response to the command signal transmitted from the first microcomputer 51. As a result, the first microcomputer 51 calculates, for example, the rotation angle θm and the steering angle θs on the basis of the signals included in the output signal.Otherwise, when it is determined that the electronic power steering device 108 is not operating (NO in step S 101), the first sensor 61 determines whether the motor unit 10 is stopped in step S 104. For example, it is possible to determine that the motor unit 10 is stopped when, for example, the rotational speed of the motor unit 10 is lower than a predetermined threshold value. It is also possible to determine that the motor unit 10 is stopped when the rotation angle θm is not calculated. It is also possible to determine that the motor unit 10 is stopped when the amount of change in the values output from the A / D converter 614, such as the deviation between the currently measured value and the immediately previously measured value or the difference value of the deviation, is less than a predetermined threshold value. Further, when it is provided to increment a count value indicating the number of rotations of the motor unit 10 each time the motor unit 10 continues to rotate by one of the three or more divided rotation angle ranges, it is possible to determine that the motor unit 10 is stopped when the same count value is unchanged for a predetermined period of time.When it is determined that the motor unit 10 is operating (NO in step S 104), the rotation information calculation task proceeds to step S 105. Otherwise, when it is determined that the motor unit 10 is stopped (YES in step S 104), the rotation information calculation task proceeds to step S 106.In step S 105, the rotation speed calculator 616 calculates the rotation speed TC at a first frequency f 1. The first frequency f 1 may be set to prevent skip of the detection of the rotation of the motor.In step S 106, the rotation speed calculator 616 calculates the rotation speed TC at a second frequency f 2 lower than the first frequency f 1, which is expressed as f 1>f 2. Since the rotation number TC remains unchanged while the motor unit 10 is stopped, by a lower frequency for calculating the rotation number TC while the motor unit 10 is stopped to intermittently calculate the rotation number Tc, for example, power consumption can be reduced.Setting the calculation frequency to a frequency equal to or higher than the first frequency f 1 while the electronic power steering device 108 is operating prevents skipping detection of the rotation of the motor unit 10. This enables the calculation frequency of the rotational speed TC while the electronic power steering device 108 is operating to be set to below the first frequency f 1.After the operation in step S 105 or S 106, the first sensor 61 stores therein the rotational speed TC in step S 107. Note that the first sensor 61 may store a latest value of the rotational speed TC whenever the latest value of the rotational speed TC is calculated without storing all the already calculated values of the rotational speed TC.The first sensor 61 transmits the rotation speed signal including the rotation speed TC stored therein and the rotation signal including the rotation angle θm to the first microcomputer 51 when the electronic power steering device 108 is restarted.The fifth embodiment is configured to change the frequency of updating, i.e., calculation, the rotational speed TC by the rotational speed calculators 616 and 626 in accordance with whether the motor unit 10 is operating. Specifically, the fifth embodiment is configured to reduce the frequency of updating the rotational speed TC while the motor unit 10 is stopped, as compared with the frequency of updating the rotational speed TC while the electronic power steering device 108 is deactivated.The fifth embodiment is configured such that the first battery 39 supplies electric power directly to the sensor elements 601 and 602 and the circuit modules 610 and 620, while the electronic power steering device 108 including the motor unit 10 is deactivated. Thereby, electric power is continuously supplied to the rotation detection device 10 while the electronic power steering device 108 is deactivated, whereby it is possible to continuously calculate the rotational speed TC while the electronic power steering device 108 is deactivated. This enables reliable calculation of the steering angle θs at the restart of the electronic power steering device 108 without releaving the neutral position of the steering wheel 101.In addition to the certain advantageous effect, the fifth embodiment achieves the same advantageous effects as the first embodiment.Sixth EmbodimentNext, the sixth embodiment of the present invention will be described with reference to FIG. 19.The sixth embodiment is a modification of the fifth embodiment. A constant voltage circuit 37 is connected in a power supply path extending from the first battery 39 to the first sensor 61. A constant voltage circuit 47 is further connected in a power supply path extending from the second battery 39 to the second sensor 62. When one of the first and second batteries 39 and 49 is configured to supply electric power to the first and second sensors 61 and 62, a common constant voltage regulator or a constant voltage regulator may be provided for the first and second sensors 61 and 62, respectively.The constant voltage circuits 37 and 47 each include, for example, a regulator with low power consumption of about several mA, which can drive the rotation detection device 1. That is, the constant voltage circuits 37 and 47 are respectively disposed separately from the regulators of the first and second integrated circuits 56 and 57, and are capable of supplying electric power to the sensor package 65 even when the driving device 8 is deactivated.The arrangement of the constant voltage circuit 37 between the first battery 39 and the rotation detection device 1 and the constant voltage circuit 47 between the second battery 49 and the rotation detection device 1 eliminates the need to change a withstand voltage construction of the rotation detection device 1 regardless of the voltage across the first and second batteries 39 and 49.The sixth embodiment also achieves the same advantageous effects as the first embodiment.Seventh EmbodimentNext, the seventh embodiment of the present invention will be described with reference to FIG. 20. Each of FIG. 20 is a schematic view corresponding to FIG. 8.The rotation detection device 1 according to the first embodiment is configured such that the sensor element 601 and the circuit module 610 are integrated in the single chip 641, and the sensor element 602 and the circuit module 620 are integrated in the single chip 642.In contrast, a rotation detection device 5 according to the seventh embodiment is configured such that (1) a chip 643 in which the circuit module 610 is accommodated is a chip separate from a chip 644 in which the sensor element 601 is accommodated (2) a chip 645 in which the circuit module 620 is accommodated is a chip separate from a chip 646 in which the sensor element 602 is accommodated.The reference numerals of the sensor element and the circuit included in the individual chips are omitted in FIG. 20.Instead of the circuit module 610, the circuit modules 611 and 612 may be used, and instead of the circuit module 620, the circuit modules 621 and 622 may be used. As in the second embodiment, two sensor elements may be used.As shown in FIG. 20A, the chip 643 including the circuit module 610 is mounted on the lead frame 66, and the chip 644 including the sensor element 601 is mounted on an upper surface of the chip 643. The upper surface of the chip 643 is a surface opposite to the lead frame 66.Similarly, the chip 645 including the circuit module 620 is mounted on the lead frame 66, and the chip 646 including the sensor element 602 is mounted on an upper surface of the chip 645.Mounting the chips 644 and 646 including the respective sensor elements on the respective one of the chips 643 and 645 including the respective circuit module enables downsizing of the mounting area on the lead frame 66, resulting in downsizing of the rotation detection device 5.As another example, as shown in FIG. 20B, the chips 644 and 646 each including the corresponding sensor element are disposed closer to the rotation center line Ac than the chips 643 and 645 each including the corresponding circuit module. In other words, the chips 644 and 646 are disposed on the inner side of the lead frame 66 with respect to the rotation center line Ac, and the chips 643 and 645 are disposed on the outer side of the lead frame 66 with respect to the rotation center line Ac. The chips 644 and 646 are further arranged symmetrically with respect to the rotation center line Ac.Note that the control configuration of the seventh embodiment may be combined with the control configuration of any of the other embodiments.In the seventh embodiment, the sensor element 601 is arranged as a separate chip from the chip 643 including the circuit module 610, and the sensor element 602 is arranged as a separate chip from the chip 645 including the circuit module 620. This enables the use of magnetoresistive (MR) sensor elements that cannot be integrated with the respective circuit modules 610 and 620 as the respective sensor elements 601 and 602.The sensor element 601 is mounted on the upper surface of the chip 643 in which the circuit module 610 is housed, and the sensor element 602 is mounted on the upper surface of the chip 645 in which the circuit module 620 is housed. Mounting the sensor elements 601 and 602 on the upper surfaces of the respective chips 643 and 645 enables downsizing of the rotation detection apparatus 1.The sensor elements 601 and 602 are disposed closer to the rotation center line Ac of the motor unit 10 than the chips 643 and 645 each including the corresponding circuit module. This enables the sensor elements 601 and 602 to be disposed closer to the rotation center line Ac, which increases measurement accuracy.The seventh embodiment also achieves the same advantageous effects as the first embodiment.Eighth EmbodimentNext, the eleventh embodiment of the present invention will be described with reference to Figs. 21 to 23.In each of the above-described embodiments, the corresponding two sensors are installed in the single package 65.In contrast, in a rotation detection device 6 according to the eighth embodiment, the first sensor 61 is installed in a first package 661, and the second sensor 62 is installed in a second package 662. Specifically, the first and second packages 661 and 662 are separately arranged for the first and second sensors 61 and 62, respectively. For example, the configurations of the first and second sensors 61 and 62 may be identical to the corresponding sensors of the first embodiment or a selected one of the second to seventh embodiments.As shown in FIGS. 21 and 22, the first package 661 is mounted on the first main surface 211 of the first circuit board 21, and the second package 662 is mounted on the second main surface 212 of the first circuit board 21. Mounting the first and second packages 661 and 662 as the first and second sensors 61 and 62, respectively, on the first and second major surfaces 211 and 212 of the first circuit board 21 enables a reduction in mounting areas required for the rotation detection device 6 on the first circuit board 21. The first and second packs 661 and 662 are arranged such that the sensor element 601 of the first sensor 61 and the sensor element 602 of the second sensor 62 are arranged on the rotation center line Ac, resulting in higher detection accuracy of the rotation of the motor unit 10.As another example, the first and second packages 661 and 662 are mounted on the first main surface 211 of the first circuit board 21 (see FIG. 23A ). As yet another example, the first and second packages 661 and 662 are mounted on the second major surface 212 of the first circuit board 21 (see FIG. 23B ).The package 661 according to the eighth embodiment is provided for the sensor element 601 and the circuit module 610 using the measurement values of the sensor element 601. Also, the package 662 according to the eighth embodiment is provided for the sensor element 602 and the circuit module 620 using the measurement values of the sensor element 602. In other words, the packages 661 and 662 are provided for the first and second sensors 61 and 62, respectively. The provision of the packages 661 and 662 for the first and second sensors 61 and 62, respectively, results in (1) higher flexibility in the arrangement of the rotation detection device 6(2) avoidance of simultaneous malfunctions of the multiple systems described aboveThat is, even if there is a malfunction in one of the first and second packs 661 and 662, the components further of the first and second packs 661 and 662 enable continuous calculation of the rotation angle θm and the rotational speed TC.The package 661 of the two packages 661 and 662 is mounted on the first main surface 211 of the first circuit board 21; the first main surface 211 is located closer to the motor unit 10; the further package 662 is mounted on the second main surface 212 of the first circuit board 21; the second main surface 212 is arranged opposite the motor unit 10 of the first circuit board 21. This results in the smaller mounting area, which contributes to downsizing of the rotation detection device 1 in its radial direction.The sensor elements 601 and 602 are disposed on the rotation center line Ac of the motor unit 10, resulting in higher detection accuracy.The eighth embodiment achieves the same advantageous effects as the first embodiment.Ninth EmbodimentNext, the ninth embodiment of the present invention will be described with reference to FIG. 24. In FIG. 24, some components such as spring clips are omitted.In all the embodiments, the SW elements 301 to 306 and 401 to 406, capacitors 36 and 46, and the rotation detection device 1 are mounted on the first circuit board 21, for example, and the first and second microcomputers 51 and 52 and the integrated circuits 56 and 57 are mounted on the second circuit board 22, for example.In contrast, as shown in FIG. 24, according to the ninth embodiment, the SW elements 301 to 306, the capacitors 36 and 46, the first and second microcomputers 51 and 52, the integrated circuits 56 and 57, and the rotation detection device 6 are mounted on a single circuit board 23. Specifically, the SW elements 301 to 306 and 401 to 406, the integrated circuits 56 and 56, and the package 661 of the rotation detection device 6 are mounted on the first main surface 231 of the circuit board 23, for example. The capacitors 36 and 46, the first and second microcomputers 51 and 52, and the package 662 of the rotation detection device 6 are mounted on the second main surface 232 opposite to the motor unit 10 of the circuit board 23, for example.As shown in FIG. 24, the packages 661 and 662 for the sensors 61 and 62, respectively, are provided and mounted on the first and second major surfaces 231 and 232, respectively, of the circuit board 23. However, the packages 661 and 662 may also be mounted on one of the first and second major surfaces 231 and 232 of the circuit board 23. The first and second sensors 61 and 62 may be incorporated into a single package. When the first and second sensors 61 and 62 can be incorporated into a single package, the rotation detection device 6 is preferably mounted on the first main surface 231 of the circuit board 23 to achieve higher detection accuracy.Mounting the components connected to the controller of the driving device 8 on the single circuit board 23 results in a reduction in the number of components of the rotation detecting device. As compared with the configuration in which parallel circuit boards are stacked in the axial direction, the configuration of the ninth embodiment results in downsizing of the rotation detection device in the axial direction.The ninth embodiment achieves the same advantageous effects as the first embodiment.Tenth EmbodimentNext, the tenth embodiment of the present invention will be described with reference to Figs. 25 to 28.The following substantially describes how the two sensor elements 601 and 607 provided for the circuit module 612 (see FIG. 16 ) are arranged according to the tenth embodiment. Although in FIG. 16, the sensor elements 601 and 607 and the circuit module 612 are incorporated in the same chip 641, the sensor elements 601 and 607 according to the tenth embodiment are incorporated in separate chips. Hereinafter, the chips of the respective sensor elements 601 and 607 are simply referred to as the sensor elements 601 and 607. Note that, for each of FIGS. 25, 26, and 28, the descriptions of the structures other than the structures of the sensor elements 601 and 607 are omitted.As described above, the sensor elements 601 and 607 are each a magnetic sensor element for measuring a magnetic change based on the rotation of the magnet 16 (see FIG. 4 ), and thus each have a directionality with respect to magnetic sensitivity. For example, FIG. 25 shows the sensor elements 601 and 607 having an identical structure, and the sensor elements 601 and 607 have respective magnetic sensing directions shown by respective arrows. The magnetic detection direction of a sensor element represents a direction determined based on the arrangement direction of Hall elements when a Hall IC is used as the sensor element or the magnetization direction of the pin layer when a TMR sensor device is used as the sensor element.FIG. 25A shows that when the sensor elements 601 and 607 are arranged such that their magnetic detection directions are parallel to each other, the magnetic scanning directions are matched to each other. When the sensor elements 601 and 607 are arranged such that their magnetic detection directions are matched with each other, the measurement values Ap of the sensor element 601 are identical to the measurement values Aq of the sensor element 607 (see FIG. 25B ). Note that each measurement value Ap may be obtained by transforming a corresponding value of a sine signal and a cosine signal output from the sensor element 601 into an angle based on a predetermined transformation function such as the arctangent function. Also, each measurement value Aq may be obtained by transforming a corresponding value of a sine signal and a cosine signal output from the sensor element 607 into an angle based on a predetermined transformation function such as the arctangent function.Also, when the sensor elements 601 and 607 are arranged such that their magnetic detection directions are matched with each other, values of a digital equivalent Dp of the measurement values Ap of the sensor element 601 are identical with values of a digital equivalent Dq of the measurement values Aq of the sensor element 607. For example, when each of the digital equivalent Dp and the digital equivalent Dq can be represented as a value of 14 bits, a value of the digital equivalent Dp and a value of the digital equivalent Dq when the mechanical angle of the motor unit 10 is 0 degrees are respectively expressed as (00000000000000). The number of bits may be set as appropriate.When there is a zero freezing error or zero retention error or zero fixation error such that each of the digital equivalent Dp and the digital equivalent Dq freezes or retains or fixes at (000000000000), it is difficult to determine whether the motor unit 10 is stopped at the mechanical angle of 0 degrees or there is a zero freezing error of both the digital equivalent Dp and the digital equivalent Dq. Note that the tenth embodiment describes an example in which there is a zero freezing error of both the digital equivalent Dp and the digital equivalent Dq, but the tenth embodiment can also be applied to another example in which a malfunction of each of the digital equivalent Dp and the digital equivalent Dq freezes at a different value.From this point of view, the tenth embodiment is configured such that the position of the sensor element 601 and the position of the sensor element 607 are shifted from each other in the rotational direction, thereby shifting the phase change of the measurement values Ap and the phase change of the measurement values Aq from each other. A displacement of one of the position of the sensor element 601 and the position of the sensor element 607 from the other in the rotational direction enables a displacement of the magnetic detection direction of the sensor element 601 from the magnetic detection direction of the sensor element 607 along the rotational direction of the motor unit 10.The feature that the two sensor elements 601 and 607 are arranged such that their magnetic detection directions are shifted from each other shows that the two sensor elements 601 and 607 are arranged such that an angle between their magnetic detection directions is not 0 degrees. The term "displacement amount between the sensor elements" means an angular displacement between the magnetic detection directions of the sensor elements.FIG. 26A shows that the sensor elements 601 and 607 are arranged such that their positions are shifted 180 degrees from each other in the rotational direction, resulting in deviation of the magnetic detection directions of the respective sensor elements 601 and 607 by 180 degrees from each other.The arrangement of the sensor elements 601 and 607 such that their magnetic detection directions are shifted 180 degrees from each other enables the phase change of the measurement values Ap and the phase change of the measurement values Aq to be shifted 180 degrees from each other. As a result, when the mechanical angle of the motor unit 10 is 0 degrees, the value of the digital equivalent Dp becomes (0000000000), and the value of the digital equivalent Dq is expressed as (10000000000000), which are different from each other.In contrast, when there is a zero freeze error of the digital equivalent Dp and the digital equivalent Dq, the digital equivalent Dp and the digital equivalent Dq freeze at (0000000000000), respectively.That is, arranging the sensor elements 601 and 607 such that their magnetic detection directions are shifted from each other enables values of the digital equivalent Dp and the digital equivalent Dq different from each other in the normal state. For this reason, the first microcomputer 51 is configured to determine that a freeze failure occurs when it determines that a value of the digital equivalent Dp is identical to a value of the digital equivalent Dq.A displacement of the magnetic detection directions of the respective sensor elements 601 and 607 with respect to each other by at least an angle d corresponding to a resolution based on the number of bits of the digital equivalents Dp and Dq enables a value of the digital equivalent Dp to be different from a value of the digital equivalent Dq in the normal state, thereby making it possible to determine whether a freeze failure is present.An angular deviation between the measurement values Ap of the sensor element 601 and the measurement values Aq of the sensor element 607 will be described below with reference to FIG. 27. In FIG. 27, the angle deviation based on the sum of the respective measured value Ap and the corresponding measured value Aq is shown as a solid line, and the difference angle deviation based on the difference of the respective measured value Aq from the corresponding measured value Ap is shown as a broken line.For example, when the displacement amount between the magnetic detection directions of the respective sensor elements 601 and 607 is set to 180 degrees, the sum of the respective measurement value Ap and the corresponding measurement value Aq results in cancellation of the angular distance. When the displacement amount between the magnetic detection directions of the respective sensor elements 601 and 607 is set to 0 degree, the difference of the respective measurement value Aq from the corresponding measurement value Ap results in cancellation of the angular distance.The displacement amount range that allows the angular distance to be equal to or less than a reference value B based on the sum or difference of the measurement values is defined from 315°, which is equal to from -45° to 45° inclusive, and from 135° to 225°. Note that the negative sign "-" means a displacement amount in the opposite direction to the rotational direction of the motor unit 10. Note that, as described above, when the displacement amount between the magnetic detection directions is set to 0° corresponding to 360°, each value of the digital equivalent Dp is equal to the corresponding value of the digital equivalent Dq, resulting in difficulty in determining whether there is a freezing error. For this reason, the range of (0±d) degrees is removed from the shift amount range; this removal allows each value of the digital equivalent Dp to be shifted from the corresponding value of the digital equivalent Dq by at least one bit. It is therefore preferable that the sensor elements 601 and 607 are arranged such that the displacement amount between the magnetic detection directions of the respective sensor elements 601 and 607 is arranged in any one of the following ranges: (1) a range R 1 of (0+d)° to 45° inclusive, (2) a range R 2 of 135° to 225° inclusive, (3) a range R 3 of 315° to (360-d)° inclusiveReference numeral (A) in FIG. 28 shows that the displacement amount between the magnetic detection directions of the respective sensor elements 601 and 607 is set to 45°, and reference numeral (B) in FIG. 28 shows that the displacement amount between the magnetic detection directions of the respective sensor elements 601 and 607 is set to 135°. Also, reference numeral (C) in FIG. 28 shows that the displacement amount between the magnetic detection directions of the respective sensor elements 601 and 607 is set to 225°, and reference numeral (D) in FIG. 28 shows that the displacement amount between the magnetic detection directions of the respective sensor elements 601 and 607 is set to 315°.Setting the displacement amount between the magnetic detection directions of the respective sensor elements 601 and 607 to 45°, 135°, 225°, or 315° enables an angle between the sensor elements 601 and 607 to be 45°. The arrangement of the sensor elements 601 and 607 whose magnetic detection directions are shifted with respect to each other is therefore easily visually recognizable during assembly.When the first and second sensors 461 and 462 are arranged as shown in FIG. 16, the sensor elements 601 and 607 provided for the common circuit module 612 may be arranged such that their magnetic detection directions are shifted from each other. The magnetic sensing directions of the sensor elements 601 and 607 of the first sensor 461 may be the same as or different from the magnetic sensing direction of the sensor elements of the second sensor 467, respectively. This can be applied to a case where the first and second sensors 461 and 462 are included in separate packages.The two sensor elements 601 and 607 according to the tenth embodiment are arranged such that their magnetic detection directions are shifted from each other in the rotational direction. A change in the measured values Ap of the first sensor 601 and a change in the measured values Aq of the second sensor 607 so that a phase shift is caused between them results in each value of the digital equivalent Dp deviating from a corresponding value of the digital equivalent Dq in the normal state. This facilitates detection of a malfunction such as a freeze failure of the digital outputs.In particular, an arrangement of the sensor elements 601 and 607 in such a way that their magnetic detection directions are shifted by 180 degrees relative to one another makes it possible for the sum of a respective measured value Ap and the corresponding measured value Aq to cancel the angular distance. When the angle corresponding to the resolution based on the number of bits of the individual rotation angle signals is denoted by the above-mentioned d, the shift amount between the magnetic detection directions of the respective sensor elements 601 and 607 is in one of the following ranges: (1) The range R 1 of (0+d)° to 45° inclusive (2) The range R 2 of 135° to 225° inclusive (3) The range R 3 of 315° to (360-d)° inclusive This makes the angular interval relatively smaller.The first microcomputer 51 is configured to determine that there is a malfunction when it is determined that a value of the digital equivalent Dp of a measurement value Ap of the sensor element 601 is matched with a corresponding value of the digital equivalent Dq of a corresponding measurement value Aq of the sensor element 607 whose magnetic detection directions are shifted from each other in the rotational direction. This configuration enables efficient detection of malfunction of the digital outputs.ModificationsThe rotation detection device according to each of the above embodiments includes the first sensor and the second sensor. However, it may also comprise three or more sensors.The rotation information calculator according to some of the embodiments includes one or two rotation information calculator provided for each of the sensors / s. However, it may also include three or more rotation information calculators provided for each of the sensors.Each of the above-described embodiments uses Hall devices as the respective sensor elements. Other sensor elements capable of measuring rotation of the detection target, such as MR sensor devices, may be used as the respective sensor elements.Each of the above-described embodiments includes one or more sensor elements provided for each of the circuit modules. However, three or more sensor elements may be provided for each of the circuit modules.In the above-described embodiments, the first and second sensor elements and the first and second circuit modules are not limited to only two sensor elements and only two circuit modules, respectively. That is, the term "a first and a second sensor element" means "at least a first and a second sensor element", and the term "a first and a second circuit module" means "at least a first and a second circuit module".In order to shift the magnetic sensing directions of respective plural sensor elements provided for a common circuit module from each other in the rotational direction, the positions of the chips in which the respective sensor elements are accommodated are shifted from each other in the rotational direction. In another embodiment, even if the magnetic detection characteristic of the rotational direction is shifted by using a sensor element whose internal structure is different, such as by changing the magnetization direction or the internal layout, to shift the phase of the detection value.Each of the above-described embodiments is configured such that the command signals transmitted from the microcomputers and the output signals transmitted from the corresponding sensors are transmitted via the respective different communication lines therebetween, but may be transmitted via a single communication line therebetween.Each of the above-described embodiments is configured such that each sensor and the corresponding microcomputer communicate with each other in accordance with the SPI, but also communicate with each other in accordance with predetermined types of communication interfaces such as a single edge nibble transmission (SENT) interface, as long as each type of communication interface may include a sequence of, i.e., a set of, the rotation angle signal and the rotation speed signal as the output signal. A modification of each of the above-described embodiments may be configured to output the rotation angle signal and the rotation speed signal separately to each microcomputer.Each of the above-described embodiments is configured to detect rotation of the motor unit as its detection target, but may also be configured to detect rotation of another detection target.Each of the above-described embodiments uses a brushless three-phase motor as the motor unit, but may also use another type of motor, a power generator, or a motor generator serving as both a motor and a power generator.At least the first embodiment is configured such that the rotation detecting device and the components for driving the motor unit 10 are mounted on the first circuit board, and the components for regulating how the motor unit is driven are mounted on the second circuit board. A modification of each of the above-described embodiments may be configured such that at least a part of the components referred to as control components for controlling how the motor unit is driven may be mounted on the first substrate, and at least a part of the components referred to as drive components for driving the motor unit may be mounted on the second circuit board.For example, the driving components and the control components included in the first motor driving system may be mounted on the first circuit board, and the driving components and the control components included in the second motor driving system may be mounted on the second circuit board. This enables the power steering device to be continuously controllably driven even when one of the first and second circuit boards malfunctions, the driving components and the control components mounted on the first and second circuit boards, respectively.When each of the above-described embodiments uses multiple circuit boards, a heat sink may be disposed between a corresponding at least one adjacent pair of the circuit boards. That is, each heat sink enables heat to be dissipated from the one or more components of one or more of the components from which heat needs to be dissipated and which are mounted on the corresponding adjacent pair of circuit boards.The driving device of each of the embodiments is applied to the electronic power steering device, but may be applied to another device.The present invention is not limited to the embodiments described herein, but may be implemented as various modifications within the scope of the present invention.List of reference characters1 Further, Examples of the disclosure include the following examples: to 6 rotation detection device 10 motor unit (detection target) 51, 52 microcomputer (controller) 601 to 607 sensor elements 610 to 612, 620 to 622 circuit module 615, 625, 635 rotation angle calculator 616, 626, 636 rotation speed calculator 617, 627 communicator 65, 661, 662 package

Claims

A rotation detection device comprising: at least first and second sensor elements (601 to 607) each configured to measure a rotation of a detection target (10); a circuit module (610 to 612, 620 to 622) comprising: first and second rotation angle calculators each configured to calculate a rotation angle of the detection target based on a corresponding one of a first measurement value of the first sensor element and a second measurement value of the second sensor element; first and second rotation speed calculators each configured to calculate a rotation speed of the detection target based on a corresponding one of a first measurement value of the first sensor element and a second measurement value of the second sensor element; and first and second communicators each configured to output, to a controller (51, 52), a rotation angle signal based on the rotation angle and a rotation speed signal based on the rotation speed; and a package (65, 661, 662) configured to house the first and second sensor elements and the circuit module, the package being mounted on a circuit board (21, 23) separate from the controller.The rotation detection device according to claim 1, wherein: the package comprises a single package; and the first sensing element, the second sensing element, and the circuit module are incorporated in the single package (65).The rotation detection device according to claim 1 or 2, wherein: the circuit module comprises a first circuit module and a second circuit module; the first circuit module comprises the first rotation angle calculator, the first rotation speed calculator, and the first communicator; the second circuit module comprises the second rotation angle calculator, the second rotation speed calculator, and the second communicator; and the package (661, 662) comprises at least first and second packages, wherein the first sensor element and the first circuit module are incorporated in the first package, and the second sensor element and the second circuit module are incorporated in the second package.The rotation detection device according to claim 3, wherein: the circuit board comprises a first surface (211) and a second surface (212) opposite to the first surface, and is arranged such that the first surface faces the detection target; the first package is mounted on the first surface (211) of the circuit board; and the second package is mounted on the second surface (212) of the circuit board.The rotation detection device according to claim 4, wherein: the first and second sensor elements are disposed on a rotation center line of the detection target.The rotation detection device according to any one of claims 1 to 4, wherein: the first and second sensor elements are arranged symmetrically with respect to a rotation center line of the detection target.The rotation detection device according to any one of claims 1 to 6, wherein: the circuit module comprises a first circuit module and a second circuit module; the first circuit module comprises the first rotation angle calculator, the first rotation speed calculator, and the first communicator; and the second circuit module comprises the second rotation angle calculator, the second rotation speed calculator, and the second communicator, the rotation detection device further comprises: at least first and second chips (641, 642), wherein the first sensor element and the first circuit module are incorporated in the first chip, and the second sensor element and the second circuit module are incorporated in the second chip.The rotation detection device according to any one of claims 1 to 6, wherein: the circuit module comprises a first circuit module and a second circuit module; the first circuit module comprises the first rotation angle calculator, the first rotation speed calculator, and the first communicator; and the second circuit module comprises the second rotation angle calculator, the second rotation speed calculator, and the second communicator, the rotation detection device further comprises: at least first and fourth chips (643, 644, 645, 646), wherein the first sensor element and the first circuit module are incorporated in the first and second chips, respectively, and the second sensor element and the second circuit module are incorporated in the third and fourth chips, respectively.The rotation detection device according to claim 8, wherein: the first circuit module is mounted on an upper surface of the second chip; the first chip in which the first sensor element is incorporated is disposed on the upper surface of the second chip; the second circuit module is mounted on an upper surface of the fourth chip; and the third chip in which the second sensor element is incorporated is disposed on the upper surface of the fourth chip.The rotation detection device according to claim 8, wherein: the first chip in which the first sensor element is incorporated is disposed closer to a rotation center line of the detection target than the second chip in which the first circuit module is incorporated; and the third chip in which the second sensor element is incorporated is disposed closer to the rotation center line of the detection target than the fourth chip in which the second circuit module is incorporated.The rotation detection device according to any one of claims 1 to 10, wherein: the first and second sensor elements (601, 607) include first and second magnetic detection directions, respectively; and the first and second sensor elements (601, 607) are arranged such that an angle between the first and second magnetic detection directions is a predetermined angle.The rotation detection device according to claim 11, wherein: the first and second sensor elements are arranged such that the angle between the first and second magnetic detection directions is 180 degrees.The rotation detection apparatus according to claim 11, wherein: the rotation angle signal based on the rotation angle comprises a digital signal having a predetermined number of bits; and the angle between the first and second magnetic detection directions is in at least one of the following ranges: a first range of (0 + d) degrees to 45 degrees inclusive; a second range of 135 degrees to 225 degrees inclusive; and a third range of 315 degrees to (360 - d) degrees, wherein d represents an angle corresponding to a resolution based on the number of bits of the digital signal.The rotation detection device according to any one of claims 11 to 13, wherein: the first and second sensor elements are each configured to measure rotation of the detection target and thereby output the corresponding one of the first and second sensor measurement values; and the controller is configured to determine that the rotation detection device is malfunctioning when it is determined that a first digital value and a second digital value are identical, the first digital value is a digital equivalent of the first measurement value of the first sensor element, the second digital value is a digital equivalent of the second measurement value of the second sensor element.The rotation detection device according to any one of claims 1 to 14, further comprising: the circuit board on which the package is mounted, the circuit board being a first circuit board; and a second circuit board on which the regulator is mounted, wherein: the second circuit board is disposed over the first circuit board from the detection target; the first circuit board and the second circuit board are communicatively connected to each other via inner connection terminals (717); and the rotation signal and the rotation speed signal output from each of the first and second communicator are transmitted to the regulator via the inner connection terminals.The rotation detection device according to any one of claims 1 to 15, wherein: the first and second communicators are each configured to transmit an output signal to the controller via a corresponding single communication line (692, 694), the output signal comprising a sequence of the corresponding rotation angle signal and the corresponding rotation speed signal.An electric power steering apparatus comprising: a motor unit (10) configured to provide an assist torque for assisting an operation of a steering shaft by a driver; and the rotation detection device according to any one of claims 1 to 16; and the controller configured to control the motor unit based on the rotation angle signal and the rotation speed signal, wherein the first and second sensor elements are each configured to measure a rotation of the motor unit as the detection target.The electric power steering apparatus according to claim 17, wherein: the controller is configured to calculate a steering angle of the steering shaft based on the rotation angle and the rotation speed.The electric power steering apparatus according to claim 17 or 18, wherein the controller comprises at least a first controller and a second controller; and the circuit module comprises at least first and second circuit modules for the first and second controllers, respectively, wherein: the first and second circuit modules are each configured to output the dehang angle signal and the rotational speed signal to the corresponding one of the first and second controllers.

Images