Abstract: A controller for a permanent magnet synchronous motor includes an estimating portion configured to determine an estimated value of a rotational speed of the rotor and an estimated value of a position of magnetic poles of the rotor based on a value of the current detected by the current detector and a parameter value indicating an interlinkage magnetic flux caused by the permanent magnet across the winding; a control unit configured to control the drive portion to cause the rotating magnetic field based on the estimated value of the rotational speed and the estimated value of the position of the magnetic poles; and a correction portion configured to correct the parameter value indicating the interlinkage magnetic flux based on correction information, the correction information being determined based on a temperature of the winding and a relationship between the temperature of the winding and a temperature of the permanent magnet.

Abstract: A controller for a permanent magnet synchronous motor includes an estimating portion configured to determine an estimated value of a rotational speed of the rotor and an estimated value of a position of magnetic poles of the rotor based on a value of the current detected by the current detector and a parameter value indicating an interlinkage magnetic flux caused by the permanent magnet across the winding; a control unit configured to control the drive portion to cause the rotating magnetic field based on the estimated value of the rotational speed and the estimated value of the position of the magnetic poles; and a correction portion configured to correct the parameter value indicating the interlinkage magnetic flux based on correction information, the correction information being determined based on a temperature of the winding and a relationship between the temperature of the winding and a temperature of the permanent magnet.

Abstract: An image forming apparatus includes: a photosensitive member rotated in a predetermined direction; a charging unit configured to charge a circumferential surface of the photosensitive member; a developing unit carrying a developer including toner and carriers, and including a developer bearing member configured to apply toner charged in a first polarity to the circumferential surface of the photosensitive member; a first voltage applying unit configured to apply a first voltage of the first polarity to the charging unit; a second voltage applying unit configured to apply a second voltage of the first polarity to the developer bearing member; a first voltage detecting unit configured to detect the first voltage; a second voltage detecting unit configured to detect the second voltage; and a controller, wherein the controller determines whether or not to make a second rate lower than a first rate according to the second voltage at a first timing.

Abstract: A control method for a three-phase DC brushless motor including a rotor that includes a plurality of magnetic poles and that is rotatable, a stator that includes a plurality of magnetic field generation parts to generate a magnetic field to be a driving source of the rotor, and a sensor to detect a magnetic pole of the rotor which pole passes through a first position in the stator is provided, the method including: detecting in which the sensor detects a first magnetic pole of the rotor which pole passes through the first position; estimating, based on a result of the detection of the first magnetic pole, time until the first magnetic pole reaches a second position in the stator; and controlling the plurality of magnetic field generation parts in such a manner that a suitable magnetic field is generated when the first magnetic pole passes through the second position.

Abstract: An image forming apparatus includes: a photosensitive member rotated in a predetermined direction; a charging unit configured to charge a circumferential surface of the photosensitive member; a developing unit carrying a developer including toner and carriers, and including a developer bearing member configured to apply toner charged in a first polarity to the circumferential surface of the photosensitive member; a first voltage applying unit configured to apply a first voltage of the first polarity to the charging unit; a second voltage applying unit configured to apply a second voltage of the first polarity to the developer bearing member; a first voltage detecting unit configured to detect the first voltage; a second voltage detecting unit configured to detect the second voltage; and a controller, wherein the controller determines whether or not to make a second rate lower than a first rate according to the second voltage at a first timing.

Abstract: In a device for controlling a motor mounted on a system with different operation modes, a controller unit calculates an input value for the motor based on an output value of the motor and a target value depending on operation modes of the system, and instructs a driver circuit of the motor to apply the input value to the motor. An estimation unit estimates an amount of rise in temperature of the motor by applying the input value for the motor to a thermal model of the motor. A notification unit compares a value estimated by the estimation unit with a threshold value. When the estimated value exceeds the threshold value, the notification unit sends a request for change of operation mode to the system.

Abstract: An antiferroelectric liquid crystal compound represented by the following general formula (I): ##STR1## wherein R.sup.1 and R.sup.2 are each independently selected from the group consisting of alkyl groups having from 3 to 18 carbon atoms, Rf is a lower alkyl group or a fluorinated lower alkyl group, (A) and (B) are each independently selected from the group consisting of 1,4-phenylene, 4,4'-biphenylene, and 2,6-naphthalene which may be substituted at least with a halogen atom, and * shows an asymmetric carbon atom.