544 results about "Hall element" patented technology

The invention discloses a self-decoupling three-dimensional force multi-mode sensing device, system and method based on radial magnetization, the device comprises a flexible magnetic film with radial magnetization, a microstructure layer, an optical waveguide layer, a shell, a Hall element, a PCB, a common camera and an infrared camera, the flexible magnetic film, the microstructure layer, the optical waveguide layer and the shell are stacked in sequence from top to bottom, and the Hall element is arranged in the shell. The PCB, the common camera and the infrared camera are all located on the bottom face of the shell, and the Hall element is installed on the PCB. The system comprises a self-decoupling three-dimensional force multi-mode sensing device and a signal processing device, and the signal processing device can realize three-dimensional force decoupling, infrared distance sensing and force application position measurement according to data of a PCB, a common camera and an infrared camera. According to the invention, the resolution is high, three-dimensional force decoupling can be realized, and multi-modal sensing can be realized.

A Hall joystick is disclosed, including: a main body having a first side surface and a second side surface; a first side cap and a second cap that are respectively fixed to the first side surface and the second side surface; a first rotating member and a second rotating member that are rotatably connected to the first side cap and the second side cap, where each of the first and the second rotating member has a magnet; a stick partly received in the main body and having a lower end rotatably connected to the main body; a transmission member movably arranged in the main body and used to transmit a rotational motion from the stick to the first rotating member and the second rotating member; and a first Hall element arranged within the first side cap, and a second Hall element arranged within the second side cap.

The three-axis Hall magnetic sensing chip comprises a magnet gathering body, a first Hall element group and a second Hall element group, the first Hall element group and the second Hall element group are arranged in a plane at intervals, the magnet gathering body is arranged on Hall elements, and the orthographic projection of the magnet gathering body on a Hall plane has a first direction symmetry axis and a second direction symmetry axis which are orthogonal. The first Hall element group comprises two first Hall elements which are connected in a contrast difference mode, wherein the magnetic induction centers of the two first Hall elements are located on a first-direction symmetric axis and are symmetrically arranged relative to a second-direction symmetric axis. The second Hall element group comprises two second Hall elements which are located on the same side of the first direction symmetry axis and are symmetrically arranged relative to the second direction symmetry axis, and the magnetic induction centers of the two second Hall elements are perpendicular to the connecting line between the orthogonal intersection points of the first direction symmetry axis and the second direction symmetry axis; the magnetism gathering body is located on one side of the connecting line of the two magnetic induction centers. According to the invention, a high inter-axis signal rejection ratio is realized, and the Z-axis signal can be directly output.

The invention relates to the technical field of motor control, in particular to a harmonic gear motor based on double encoders and a control method thereof, which comprises the following steps: processing linear Hall element signals output by a rotor shaft encoder, including high-frequency noise suppression, direct-current bias calibration, amplitude normalization and phase difference calibration, to obtain accurate orthogonal signals; a double-dq rotating coordinate system phase-locked loop algorithm is adopted, the calibrated orthogonal signals are processed, and the high-precision real-time angle of the motor rotor is obtained through calculation; based on a signal of an output shaft encoder, matching with a preset angle partition of the harmonic reducer, and identifying an absolute position sector where the current output shaft is located; the rotor angle and the sector angle of the output shaft are fused to generate a high-resolution absolute angle of the output shaft; and based on the fused angle information, a magnetic field orientation control algorithm is adopted to drive a motor, and closed-loop control is achieved.

A Hall joystick includes: a main body having a first side surface and a second side surface; a first side cap and a second cap that are respectively fixed to the first side surface and the second side surface; a first rotating member and a second rotating member that are rotatably connected to the first side cap and the second side cap, each of the first rotating member and the second rotating member having a magnet; a stick partly received in the main body and having a lower end rotatably connected to the main body; a transmission member movably arranged in the main body and configured to transmit a rotational motion from the stick to the first rotating member and the second rotating member; and a first Hall element arranged within the first side cap, and a second Hall element arranged within the second side cap.

The utility model discloses a magnetic shaft with an awakening function, which comprises a base, an upper cover, a guide core, a reset spring, a permanent magnet, a Hall element, a moving plate which is arranged on the side edge of the guide core and is integrally downwards and elastically bent, and a static plate arranged below the moving plate, at least one protruding edge is formed on the side edge of the guide core, the movable piece comprises at least one movable piece supporting arm transversely extending in the direction of the protruding edge, the movable piece supporting arm is driven by the protruding edge to make contact with or be separated from the static piece under the acting force that the guide core is pressed by external force, and the movable piece and the static piece are electrically connected with an external circuit board. According to the wireless keyboard, the mechanical switch is triggered to wake up the Hall element to realize signal transmission when a user presses the wireless keyboard, the mechanical switch and the Hall element do not interfere with each other when the wireless keyboard is not pressed, and the Hall element is dormant, so that the aims of saving electric power and prolonging the service life of the wireless keyboard are fulfilled; and in addition, the mute arm is arranged for buffering the downward pressing impact force, so that the mute function is achieved.

A described example includes: a heat slug coupled to a package substrate, the heat slug configured to conduct a current between terminals of the package substrate; a first magnetic shield mounted to a top surface of the package substrate, the first magnetic shield including a die mount area; a semiconductor die flip chip mounted to the die mount area; a second magnetic shield mounted to the package substrate, the second magnetic shield having a cantilever portion extending over a portion of the semiconductor die including a Hall element; electrical connections of wire bonds or ribbon bonds between bond pads of the semiconductor die and leads on the package substrate; and mold compound covering the electrical connections, the semiconductor die, the first magnetic shield, and the second magnetic shield, while a portion of the heat slug is exposed forming a thermal pad for a semiconductor device package.

The present invention relates to the technical field of encoders, and particularly to a high-performance magnetic ring encoder and a method for detecting the absolute angle of the magnetic ring encoder. The high-performance magnetic ring encoder includes a second multi-pole magnet, a first multi-pole magnet, a single-pole magnetic conductor assembly, a first group of Hall elements, a second group of Hall elements, and a third group of Hall elements; the single-pole magnetic conductor assembly has a toothed portion and a smooth portion, the first group of Hall elements and the second group of Hall elements are respectively arranged adjacent to the first multi-pole magnet and the second multi-pole magnet, the third group of Hall elements is arranged between the toothed portion and the smooth portion, and the three groups of Hall elements output corresponding detection signals according to the pole signals of the corresponding magnets. The present invention calibrates the rotation angle of the magnetic ring encoder by obtaining a mechanical angle with a certain accuracy, thereby greatly improving the measurement accuracy. The present invention is particularly suitable for meeting the actual requirements of angle detection of large-diameter shaft parts.

To provide a Hall element and a current sensor in each of which high accuracy and high sensitivity can be made compatible with each other even when a high magnetic field is applied to the Hall element and the current sensor, the Hall element and the current sensor consuming low power and being suppressed in reliability variation.SOLUTION: The Hall element comprises a substrate 11 including gallium arsenide, an active layer 12 including indium arsenide, formed on the substrate, having a film thickness of 0.63 μm or more and less than 1.45 μm, and an inactive layer 13 formed on the active layer, having a film thickness of 3 nm or more and less than 100 nm. The film thickness ratio of the inactive layer to the active layer is 0.005 or more and less than 0.067. This enables the provision of the Hall element and a current sensor which can achieve both high precision and high sensitivity even under high magnetic fields, have low power consumption, and suppress reliability variations.SELECTED DRAWING: Figure 1

The invention discloses a miniaturized sensor for detecting alternating current and direct current, and belongs to the technical field of current sensors. The device comprises a conductor, the conductor is respectively connected with a zero-sequence coil and a magnetic-core-free Hall element, the zero-sequence coil is connected with an electric leakage detection module and an electric leakage simulation module, the magnetic-core-free Hall element is connected with a current detection module, and the elements and the modules are respectively and electrically connected with an intelligent control system. The problem that in the prior art, a mutual inductor can only measure alternating current and does not have the function of measuring direct current is solved, a magnetic field generated by current is detected through the magnetic-core-free Hall element and converted into an electric signal, the current magnitude is obtained through analysis of the current detection module, and over-current protection is achieved; residual current in the circuit is detected through the zero-sequence coil, and the electric leakage detection module is used for analysis and comparison to realize electric leakage protection; the whole electric leakage system is regularly tested through the simulation electric leakage module, so that the use performance and reliability of the miniaturized sensor are ensured.

A photovoltaic detection assembly includes a magnetic component and a detection component. The magnetic component includes a magnetic ring and a coil winding around the magnetic ring. The magnetic ring is sleeved on the cable and comprises an opening. Two end surfaces of the magnetic ring are disposed on two sides of the opening. The two end surfaces of the magnetic ring are arranged in parallel. The detection component comprises a Hall element, a detection module, a control module, a signal module, and a power module. The Hall element is disposed at the opening. The detection module is electrically connected to the Hall element. The control module is electrically connected to the detection module, the signal module, and the power module respectively. The power module is electrically connected to the coil.

The utility model discloses a Hall sensor magnetic shaft switch, which comprises a base detachably mounted on a keyboard circuit board, a cover covering the base, a reset spring sleeved in the middle of the base, and a guide core of which the upper end penetrates through the cover and the lower end is pressed against the reset spring, the cover plate is arranged at the lower end of the base; the switch circuit board is arranged on the cover plate; the Hall element is arranged on the cover plate and is electrically connected with the switch circuit board; the at least two groups of conduction terminals are electrically connected with the switch circuit board and integrally extend downwards to be conducted with the keyboard circuit board; according to the utility model, the Hall element is arranged inside the key switch, so that the key switch can be freely plugged on the keyboard circuit board and can be freely replaced by other key switches, the adaptation degree of the keyboard is improved, the use of people is facilitated, the requirements of people for different key switches are met, and the use experience of people is ensured.

To provide a vertical hall element in which the spread of the current path of the sensing current flowing through the semiconductor region is suppressed.SOLUTION: A vertical hall element 1 comprises a conductive first semiconductor layer 20 defined on both sides by mutually opposing first and second surfaces 201 and 202, and a first magnetic sensitive layer 301 of conductive semiconductor in the shape of a mesa, located above the first surface 201 of the first semiconductor layer 20, with the bottom surface facing the first surface 201. In at least part of the first magnetic sensitive layer 301 from the bottom surface to the top surface opposite the bottom surface, the cross-section parallel to the bottom surface is divided into a first region 321 and a second region 322 that is less conductive than the first region 321.SELECTED DRAWING: Figure 1

A Hall current sensor, comprising: a magnetic core (10), wherein an air gap (11) is formed in one side of the magnetic core (10); a Hall element (12), wherein the Hall element (12) is disposed in the air gap (11); and a ferrite structure, wherein the ferrite structure is disposed in the air gap (11), and the ferrite structure clamps the Hall element (12) in the air gap (11), so as to reduce the air gap of a magnetic circuit and keep the Hall element (12) perpendicular to the direction of a magnetic induction line in the air gap (11). The Hall current sensor can significantly improve the detection precision, anti-interference capability and position error resistance capability of open-loop and closed-loop magnetic sensors in leakage current, small current and other weak magnetic scenarios, thereby realizing low-cost, high-precision and fast-response current sensing.

The utility model discloses a double-shaft Hall rocker comprising a pedestal, a circuit board is installed in the pedestal, and a Hall element is arranged on the circuit board; the upper cover is mounted above the base; the transmission rod is rotatably mounted in the base, penetrates through the upper cover and extends into the base, a permanent magnet is fixed at the bottom end of the transmission rod, and the permanent magnet is matched with the Hall element; and the double-shaft mechanism is rotationally installed in the base and connected with the transmission rod, and the double-shaft mechanism and the upper cover jointly limit the rotation range of the transmission rod. According to the utility model, the non-contact Hall element is taken as a core, high-precision double-shaft control is realized, automatic reset and sealing dustproof design are combined, the long service life and stability are ensured, the anti-interference capability is enhanced by the aluminum alloy material, the overall design is simple, and the maintenance is easy.

The invention relates to the technical field of current sensors, in particular to a current sensor device for motor control, which comprises a PCB (printed circuit board), a Hall element is vertically fixed in front of the PCB, two supports are symmetrically arranged on two sides of the Hall element, the two supports are fixed on the PCB, the front ends of the two supports are provided with clamping openings, and the clamping openings are fixed on the PCB. A magnetic core is fixed to the two supports through the clamping opening, an induction opening is formed in the upper portion of the magnetic core, the two supports are symmetrically arranged on the two sides of the induction opening, the Hall element is arranged in the middle of the induction opening, a front end cover is arranged on the front side of the PCB, and a first assembly structure is arranged in the front end cover. During assembly, the Hall element, the magnetic core and the PCB are ensured not to deflect, the Hall element is ensured to be located in the induction port of the magnetic core, when a magnetic field induces a signal, the signal precision is ensured, and the product quality is improved.

The utility model provides a prism anti-shake assembly which is installed in a prism cabin and comprises a control circuit board, a rotating frame which can swing left and right and is installed in the prism cabin, and a prism assembly which can swing in a pitching mode and is installed in the rotating frame. Driving magnetic steel and sensing magnetic steel are arranged on the rotating frame; the control circuit board is provided with a gyroscope, an outer driving coil which is opposite to the driving magnetic steel up and down, and an outer Hall element which is opposite to the sensing magnetic steel up and down; the prism assembly is provided with an inner shaft circuit board, and the inner shaft circuit board is provided with an inner drive coil vertically opposite to the drive magnetic steel and an inner Hall element vertically opposite to the sensing magnetic steel. According to the utility model, independent magnetic steel is respectively adopted for driving and detecting the prism, so that the mutual interference of signals is reduced, the output noise of the Hall element is reduced, the anti-shake precision of the device is improved, and meanwhile, the device has the advantages of small overall appearance, high modularization degree, convenience in assembly and debugging and high cost performance.

The application relates to the technical field of conveying devices, and discloses a roller motor, which comprises a roller and a driving piece, the driving piece is used for driving the roller to rotate, and the roller motor further comprises: a first detection assembly, which comprises a first magnet and a first Hall element, the first magnet is fixedly connected to the rear end of an output shaft of the driving piece, the roller is fixedly connected to the front end of the output shaft of the driving piece, and the first Hall element is used for sensing the magnetic field change of the first magnet to detect the rotating speed of the output shaft; and a second detection assembly, which comprises a second magnet and a second Hall element, the second magnet is fixedly connected to the roller, and the second Hall element is used for sensing the magnetic field change of the second magnet to detect the rotating speed of the roller. The roller motor can detect the rotating speeds of the driving piece and the roller simultaneously, and the control precision of the rotating speed of the roller can be improved in combination with a control mechanism.

The utility model is suitable for the field of beauty instruments, and provides a storage box and a beauty instrument assembly. According to the storage box provided by the utility model, the Hall element, the control unit, the disinfection assembly and the position sensing piece used for sensing that the beauty instrument is placed in the storage position on the main body are arranged in the shell of the main body, and the Hall element, the position sensing piece and the disinfection assembly are all electrically connected with the control unit; and an induction magnetic piece corresponding to the Hall element is arranged on the cover body. Therefore, whether the cover body covers the shell of the main body or not can be sensed through the Hall element, and whether the beauty instrument is accommodated in the accommodating position or not can be sensed through the position sensing piece; in this way, the control unit can control the disinfection assembly to disinfect the working head of the beauty instrument through double signal feedback of the position sensing part and the Hall element after the beauty instrument is placed in the storage box and the cover body covers the storage box, so that timely disinfection can be guaranteed, and the control unit can cut off the disinfection assembly when it is not detected that the beauty instrument is placed in the storage position; and the safety is higher.

A magnetic sensor according to the present invention is capable of measuring a small magnetic field with high accuracy by eliminating 1 / f noise. The magnetic sensor comprises a variable magnetic field detection unit that includes a Hall element having a magnetism-sensing direction giving rise to an anomalous Hall effect and a magnetic field control unit for controlling the Hall element so that a magnetic field having a component in a non-sensing direction orthogonal to the magnetism-sensing direction is generated in the Hall element. The magnetic sensor may further comprise a magnetic field calculation unit that calculates a measurement magnetic field on the basis of a first output and a second output, the first output including a measurement result obtained when the variable magnetic field detection unit measures a measurement magnetic field along the magnetism-sensing direction in a first state in which the direction of the magnetic field generated in the Hall element is not controlled by the magnetic field control unit, the second output including a measurement result obtained when the variable magnetic field detection unit measures the measurement magnetic field in a second state in which the direction of the magnetic field generated in the Hall element is controlled by the magnetic field control unit.

The invention provides a double-magnetic-wheel Hall sensor and an absolute angle jump correction method and system. The absolute angle jump correction method comprises the steps that S1, a first angle signal, measured by a first Hall element, of a driving wheel is acquired; the second Hall element measures a second angle signal of the driving wheel; calculating a difference value between the first angle signal and the second angle signal, and calculating an absolute angle of rotation of the driving wheel by using a vernier algorithm; s2, judging whether the calculated absolute rotation angle of the driving wheel jumps or not; when the absolute rotation angle of the driving wheel does not jump, the absolute rotation angle of the driving wheel is output; when the absolute rotation angle of the driving wheel jumps, the step S3 is executed; s3, selecting an angle signal which does not cause jumping of the absolute angle of the rotation of the driving wheel, and correcting the absolute angle of the rotation of the driving wheel which jumps; and S4, outputting the corrected absolute rotation angle of the driving wheel. According to the invention, the stability and robustness of the double-magnet-wheel Hall sensor are improved.

The invention provides a high-sensitivity temperature compensation Hall switch device. The high-sensitivity temperature compensation Hall switch device comprises a Hall switch module, a temperature compensation module, a signal processing module and a power management module. The Hall switch module comprises a Hall element, a pre-amplifier and a comparator and is used for detecting and amplifying an external magnetic field signal; the temperature compensation module comprises a temperature sensor, a compensation controller and a compensation element and is used for realizing accurate temperature compensation; the signal processing module comprises a filter and a logic control unit, and is used for filtering noise and generating a final switch control signal; the power management module comprises a main power supply and a standby power supply to ensure stable power supply. The device can improve the temperature compensation precision, enhance the switch sensitivity, reduce the power consumption, and meet the high-precision and high-reliability requirements of modern electronic equipment.

A power module includes a first substrate including a sensing target portion in which a current path is formed in a first direction, a second substrate spaced from the first substrate in a second direction crossing the first substrate, and a Hall element disposed between the first substrate and the second substrate to face the sensing target portion with an interval with the sensing target portion, and electrically connected to the outside of the power module, and configured to generate voltage according to a magnetic field occurring due to a current flowing in the sensing target portion.

A waterproof oral irrigator including an oral irrigator housing which is provided with a sliding recess on an outer wall thereof; a push switch slidably fitted with the sliding recess and provided with a magnetic element; and a control circuit board arranged inside the oral irrigator housing and being provided with a plurality of Hall elements. A plurality of Hall elements are sequentially disposed at intervals along a sliding direction of a push switch. When the push switch slides along the sliding recess, the magnetic element can be driven to move to positions sensed by the plurality of Hall elements in sequence. Since the outer wall of the oral irrigator housing is provided with the sliding recess, and the sliding recess is not communicated with the interior of the oral irrigator, so that the waterproof performance of the oral irrigator can be greatly improved.

The invention relates to the technical field of magnetic sensing, in particular to a three-axis Hall sensing structure, which comprises a plurality of first Hall elements arranged in pairs and is used for detecting a planar two-dimensional magnetic field by a differential detection method. Part of the first Hall elements are arranged at intervals in pairs in the first direction, part of the first Hall elements are arranged at intervals in pairs in the second direction, the first direction and the second direction are orthogonal, and a reserved space is formed in the middle of a preset pattern formed by the first Hall elements; the at least one second Hall element is used for responding to a magnetic field in a third direction, the third direction is orthogonal to the plane, and an induction area of the second Hall element is located in the middle of the reserved space; and the first magnetic gathering layer is stacked on the plurality of first Hall elements, the orthographic projection of the first magnetic gathering layer on the plane at least partially covers the area of the preset pattern, and the first magnetic gathering layer is provided with an open hole for exposing the second Hall element. The device has the advantages of integration, miniaturization, low cost, interference resistance, high inter-axis isolation degree and the like.

The utility model discloses a keyboard which comprises a shell, a fixing layer, a plurality of key structures and a cut-off piece. The fixing layer is connected to the shell; the key structure is installed on the fixing layer, the key structure comprises a shaft body and a reset piece, the shaft body can slide relative to the fixing layer, and the reset piece is used for resetting the shaft body; according to the scheme, when the key structure is pressed down, the shaft body moves downwards till abutting against the cut-off piece, the key shaft and the cut-off piece collide to generate vibration, a vibration source and the fixing layer are spaced, the influence of the vibration on the fixing layer is small, and when the keyboard is knocked at high frequency, the key shaft and the cut-off piece are separated from each other. The fixing layer can be kept stable, the service life of the fixing layer is effectively prolonged, and the risk of mistaken touch caused by the fact that the key structure installed on the fixing layer is affected by vibration is avoided. In addition, when the magnetic part is driven by the key shaft to move, the Hall element induces the change of a surrounding magnetic field and generates an induction signal.

The utility model provides an anti-shake assembly and a telescope, and the assembly comprises a circuit board, a movable installation plate connected with the circuit board, a lens disposed on the movable installation plate, two pieces of driving magnetic steel which are orthogonally distributed on the movable installation plate, and two pieces of sensing magnetic steel which are orthogonally distributed on the movable installation plate. The two pieces of driving magnetic steel are arranged on the circuit board, the two pieces of sensing magnetic steel are arranged on the circuit board, the two driving coils are arranged on the circuit board and correspond to the two pieces of driving magnetic steel in a one-to-one mode, the two Hall elements are arranged on the circuit board and correspond to the two pieces of sensing magnetic steel in a one-to-one mode, and the gyroscope is arranged on the circuit board. According to the utility model, the driving coil, the Hall element, the gyroscope and other electronic components are directly installed on the circuit board, so that the structural layout is optimized, the electronic components do not need to be led out by a flat cable to be connected with the circuit board, the processing complexity and cost are reduced, and the working stability is improved.

The invention discloses a small-sized high-integration deepwater motor with a built-in magnetic encoder, which is characterized in that a motor stator and rotor assembly is connected with a motor rotating shaft in a motor shell, a motor rear end cover is mounted on the motor shell through shape limiting, and an encoder static part is connected with the motor rear end cover; an encoder rotor of the magnetic encoder is installed on a motor rotating shaft in the axial direction, the inner diameter of the encoder rotor is in tolerance fit with the motor rotating shaft, a harmonic reducer is connected to the front side of a motor shell, a motor output shaft is connected to the harmonic reducer, a slender rotating shaft is connected with the motor output shaft, and an output shaft magnetic ring is fixed to one end of the slender rotating shaft. The thin and long rotating shaft penetrates through the hollow motor rotating shaft to transmit an output end signal to an output end Hall element of a motor controller center, the structure is simplified, the waterproof performance is improved by adopting multiple sealing, and high-precision control in a deep water environment is realized while the reliability is ensured.

The invention provides a Hall circuit and a Hall chip, which are applied to the technical field of electromagnetic signals. According to the invention, the switch module can be in a continuous opening state, so that the magnetic induction intensity of a surrounding magnetic field can be detected and the working state of the linear Hall sensor can be controlled in real time; as the switch module only needs to realize the functions of detecting the magnetic induction intensity of the surrounding magnetic field in real time and starting the linear Hall sensor switch, the resistance value of the magnetoresistive sensor of the switch module can be set to be large, and the purpose of reducing the quiescent current and power consumption of the Hall circuit can be achieved; secondly, the linear Hall sensor can be used for carrying out high-precision detection on the key stroke of the magnetic axis keyboard, so that the resistance value of a Hall element of the linear Hall sensor can be set to be small, and the detection precision of the linear Hall sensor meets the requirement; moreover, seamless linkage between the press stroke of the key and the brightness of the load LED lamp can be realized by using the load driving module, so that the user experience is enhanced, and software intervention is not needed.

The invention discloses a novel motor type on-line automatic balancing device with a positionable counterweight disc. The novel motor type on-line automatic balancing device comprises a rotating part, a gear part, a static part, a conductive slip ring and a connecting bearing, the connecting bearing comprises two moving ring bearings and two static ring bearings; the rotating part and the gear part are connected through two moving ring bearings, and the gear part and the static part are connected through two static ring bearings; the rotating component mainly comprises a moving ring, two ultrasonic motors and a reference magnet; the gear component comprises two groups of planet gears and gear rings which are meshed with each other, two counterweight plates, two counterweight blocks, a positioning magnet I and a positioning magnet II; the static part mainly comprises a static ring, an aviation plug frame, a first side end cover, a second side end cover, a first positioning Hall element, a second positioning Hall element and a reference Hall element, according to the invention, a dynamic and static ring structure is adopted, and the positions of the reference magnet and the positioning magnet I and the positioning magnet II at the corresponding positions are sensed through the reference Hall element, the positioning Hall element I and the positioning Hall element II, so that the specific phases of the two counterweight discs are detected, and the counterweight discs are positioned.