A luminaire includes a luminaire mechanism, a stepper motor, an absolute multi-turn rotational position sensing system, and a control system. The stepper motor moves the luminaire mechanism. The absolute multi-turn rotational position sensing system includes absolute rotational sensors that detect absolute positions of a cam indexer on the motor shaft and an indexer wheel coupled to the cam indexer. The indexer wheel rotates by a predetermined amount in response to one full rotation of the cam indexer. The control system determines an absolute position of the luminaire mechanism based on information from the absolute rotational sensors relating to the positions of the cam indexer and the indexer wheel. The control system receives a commanded position for the luminaire mechanism and causes the stepper motor to move the luminaire mechanism to the commanded position based on the absolute position of the luminaire mechanism.

A luminaire includes a luminaire mechanism, a stepper motor, an absolute multi-turn rotational position sensing system, and a control system. The stepper motor moves the luminaire mechanism. The absolute multi-turn rotational position sensing system includes absolute rotational sensors that detect absolute positions of a cam indexer on the motor shaft and an indexer wheel coupled to the cam indexer. The indexer wheel rotates by a predetermined amount in response to one full rotation of the cam indexer. The control system determines an absolute position of the luminaire mechanism based on information from the absolute rotational sensors relating to the positions of the cam indexer and the indexer wheel. The control system receives a commanded position for the luminaire mechanism and causes the stepper motor to move the luminaire mechanism to the commanded position based on the absolute position of the luminaire mechanism.

The present disclosure is directed to techniques for synchronizing a rotational eccentric mass of a gravitational transducer used for a magnetic resonance elastography acquisition with a corresponding magnetic resonance elastography scan carried out by a magnetic resonance imaging system, wherein the rotation of the eccentric mass is driven by a shaft. The method includes starting the rotation of the eccentric mass at a set vibration frequency and the magnetic resonance elastography scan at a set acquisition frequency; determining the rotational position of the shaft; defining the rotational position as first reference position; calculating further reference positions. At the start time of each subsequent acquisition period, determining the current rotational position of the shaft; comparing the determined current rotational position with the theoretically expected reference position and decreasing or increasing the rotational speed of the rotational eccentric mass based on the comparison.

The present disclosure is directed to techniques for synchronizing a rotational eccentric mass of a gravitational transducer used for a magnetic resonance elastography acquisition with a corresponding magnetic resonance elastography scan carried out by a magnetic resonance imaging system, wherein the rotation of the eccentric mass is driven by a shaft. The method includes starting the rotation of the eccentric mass at a set vibration frequency and the magnetic resonance elastography scan at a set acquisition frequency; determining the rotational position of the shaft; defining the rotational position as first reference position; calculating further reference positions. At the start time of each subsequent acquisition period, determining the current rotational position of the shaft; comparing the determined current rotational position with the theoretically expected reference position and decreasing or increasing the rotational speed of the rotational eccentric mass based on the comparison.

The task of the present invention is to provide a driving circuit capable of outputting information useful to design or control of a system to outside. The present invention relates to a driving circuit and a driving method of a stepping motor, and an electronic machine using the driving circuit of a stepping motor. A counter electromotive force detection circuit detects a counter EMF generated in a coil. A revolution count detection circuit acquires the revolution count of the stepping motor. A load angle estimating portion calculates a load angle according to the counter EMF and the revolution count. An interface circuit is configured to be capable of outputting angle information associated with the load angle to outside, or accessing the angle information from the outside.

The task of the present invention is to provide a driving circuit capable of outputting information useful to design or control of a system to outside. The present invention relates to a driving circuit and a driving method of a stepping motor, and an electronic machine using the driving circuit of a stepping motor. A counter electromotive force detection circuit detects a counter EMF generated in a coil. A revolution count detection circuit acquires the revolution count of the stepping motor. A load angle estimating portion calculates a load angle according to the counter EMF and the revolution count. An interface circuit is configured to be capable of outputting angle information associated with the load angle to outside, or accessing the angle information from the outside.

A luminaire includes a luminaire mechanism, a stepper motor, an absolute multi-turn rotational position sensing system, and a control system. The stepper motor moves the luminaire mechanism. The absolute multi-turn rotational position sensing system includes absolute rotational sensors that detect absolute positions of a cam indexer on the motor shaft and an indexer wheel coupled to the cam indexer. The indexer wheel rotates by a predetermined amount in response to one full rotation of the cam indexer. The control system determines an absolute position of the luminaire mechanism based on information from the absolute rotational sensors relating to the positions of the cam indexer and the indexer wheel. The control system receives a commanded position for the luminaire mechanism and causes the stepper motor to move the luminaire mechanism to the commanded position based on the absolute position of the luminaire mechanism.

A luminaire includes a luminaire mechanism, a stepper motor, an absolute multi-turn rotational position sensing system, and a control system. The stepper motor moves the luminaire mechanism. The absolute multi-turn rotational position sensing system includes absolute rotational sensors that detect absolute positions of a cam indexer on the motor shaft and an indexer wheel coupled to the cam indexer. The indexer wheel rotates by a predetermined amount in response to one full rotation of the cam indexer. The control system determines an absolute position of the luminaire mechanism based on information from the absolute rotational sensors relating to the positions of the cam indexer and the indexer wheel. The control system receives a commanded position for the luminaire mechanism and causes the stepper motor to move the luminaire mechanism to the commanded position based on the absolute position of the luminaire mechanism.

A motor control device according to an embodiment comprises a first signal generator, a second signal generator, a main controller, and a driver. The first signal generator is configured to generate, based on a clock signal indicating a stepping drive cycle of a motor, a first control signal. The second signal generator is configured to generate, based on a command phase indicating a target phase of a rotor of the motor, a second control signal. The main controller is configured to control the first signal generator and the second signal generator to output at least one of the first control signal and the second control signal. The driver is configured to drive the motor based on at least one of the first control signal and the second control signal.

According to one embodiment, a controller of a stepping motor includes a table generating unit and a current controlling unit. The table generating unit generates a data table of a threshold by using values of induced voltage at frequencies of switching signal that changes a set value of a drive current, the threshold being proportional to a frequency of the switching signal within an operation region in which the frequency of the switching signal is lower than a predetermined frequency, the values of the induced voltage including a first induced voltage generated at a first frequency of the switching signal and a second induced voltage generated at a second frequency of the switching signal. The current controlling unit controls a value of the drive current in accordance with a comparison result between the threshold and an induced voltage that is detected at a frequency lower than the predetermined frequency.