A rotatable operation apparatus includes a rotatable operation member, a magnet having alternately magnetized magnetic poles, first and second magnetic members respectively including first and second teeth, a body frame, and a detector. A magnetized direction of each magnetic pole is parallel to a predetermined axis about which the rotatable operation member rotates. The magnet has a ring shape and is configured to rotate about the predetermined axis as the rotatable operation member rotates. The rotatable operation apparatus generates an operation force according to a change in positions of the magnetic poles, caused by the rotation of the magnet, relative to positions of the first tooth and the second tooth. The magnet, the first magnetic member, and the second magnetic member are housed inside the body frame. When viewed from a thrust direction of the magnet, the detector is disposed at a position that does not overlap with the magnet.

A magnetic field sensor includes a sensor and a processing circuit. The sensor is designed to generate on the basis of a varying magnetic field an oscillation signal that fluctuates around a mean value. The processing circuit is designed to generate an output signal on the basis of the oscillation signal. The processing circuit is designed, in a high-resolution mode different than a low-resolution mode, in each case to generate a mean value crossing pulse in the output signal when the oscillation signal attains the mean value, and to generate in each case a limit value crossing pulse in the output signal when the oscillation signal attains at least one limit value different than the mean value. A pulse width of at least either the mean value crossing pulse or the limit value crossing pulse is set to indicate that the magnetic field sensor is operating in the high-resolution mode.

A magnetic encoder in which a support member and a plastic magnet do not adhere to each other is manufactured using a mold. The plastic magnet has a turning molded portion on the outer circumferential side thereof. The gate of the mold is an inner-diameter-side disk gate and a length L thereof in the axial direction is in a range of 0.2 mm≤L≤0.6 mm. The tensile strength of the material of the plastic magnet is 65 MPa or more and the Young's modulus thereof is 4000 MPa or more and 15000 MPa or less. The method includes a step of opening the mold and placing the support member as an insert object in the mold, and a step of closing the mold and injecting a melted material of the plastic magnet into a cavity through the disk gate.

A magnetic sensor includes a first resistor having a first resistance and a first correction resistor having a second resistance. The first resistor and the first correction resistor are connected in series. The first resistor is configured so that the first resistance changes periodically as strength of a magnetic field component changes periodically. The first correction resistor is configured so that a change in a sum of the first resistance and the second resistance due to a noise magnetic field is smaller than a change in the first resistance due to the noise magnetic field.

A magnetic field sensor includes a sensor and a processing circuit. The sensor is designed to generate on the basis of a varying magnetic field an oscillation signal that fluctuates around a mean value. The processing circuit is designed to generate an output signal on the basis of the oscillation signal. The processing circuit is designed, in a high-resolution mode different than a low-resolution mode, in each case to generate a mean value crossing pulse in the output signal when the oscillation signal attains the mean value, and to generate in each case a limit value crossing pulse in the output signal when the oscillation signal attains at least one limit value different than the mean value. A pulse width of at least either the mean value crossing pulse or the limit value crossing pulse is set to indicate that the magnetic field sensor is operating in the high-resolution mode.

In an example, a circuit includes a first comparator, a second comparator, a pulse counter, a processor, a first ADC, and a second ADC. The first comparator has a first input coupled to a first node, a second input, and an output. The second comparator has a first input coupled to a second node, a second input, and an output. A first DAC is coupled to the second input of the first comparator. A second DAC is coupled to the second input of the second comparator. The pulse counter has a first input coupled to the output of the first comparator and a second input coupled to the output of the second comparator. The first ADC has an input coupled to the first node and an output coupled to the processor. The second ADC has an input coupled to the second node and an output coupled to the processor.

A magnetic linear position detector includes a stator and a mover that is movable along a first direction with respect to the stator. One of the stator and the mover includes a magnetic detector, and the other of the stator and the mover includes a magnet. The magnet has a first face facing the magnetic detector, and the first face is provided alternately with N poles and S poles along the first direction. The magnet includes a first region and a second region provided on each side of the first region along the first direction. In the first region, a length along a second direction perpendicular to the first face is constant. In the second region, a length along the second direction is different from the length in the first region.

A battery-free rotation detecting device includes a rotating carrier, a first magnetic element, a second magnetic element and at least one detection coil set. The rotating carrier can be assembled with a rotating element. The first magnetic element is disposed to the rotating carrier, and the second magnetic element is also disposed to the rotating carrier but spaced from the first magnetic element. The at least one detection coil set is located between the first magnetic element and the second magnetic element. The rotating carrier can be driven by the rotating element so as further to rotate the first magnetic element and the second magnetic element synchronously. The at least one detection coil set generates an electrical signal upon when a change of the magnetic field between the first magnetic element and the second magnetic element is detected.

An angle measuring device includes first and second component groups and a bearing. The first component group includes a scale element having a first graduation. The second component group has a first modular unit, including a position sensor, and a second modular unit, including first, second, and third position transducers, and a compensation coupling. The first and second modular units are connected in a torsionally stiff but axially and radially flexible manner. The angle measuring device is operable in first and second modes. In the first mode, the first graduation is scannable by the position sensor to determine a first angular position. In the second mode, the first graduation or a further graduation situated on the scale element is scannable by the position transducers to determine further angular positions. A corrected relative angular position is determinable based on the first angular position and the further angular positions.

Provided is a rotational positioning device capable of positioning a rotational angle at a target angle position with high precision. A rotational positioning device is provided with: a housing; a rotational member which is rotatable about a rotational member axial line and at least a part of which is accommodated in the housing; and at least one sensor installed in the housing. A graduated scale with a plurality of scale marks is formed integrally with the rotational member along the circumferential direction of the rotational member. The at least one sensor detects an angle change amount due to rotation of the rotational member on the basis of the plurality of scale marks. The rotational member is positioned at the target angle position on the basis of the angle change amount.