Konica Minolta, Inc.

Kazumichi Yoshida

Hiroyuki Yoshikawa

Yuta Tachibana

Yuji Kobayashi

Harumitsu Fujimori

Daichi Suzuki

Yoshihito Sasamoto

Kazutoshi Yoshimura

Satoshi Miyajima

Kouei Cho

Yasuo Koyanagi

A stiffness measuring device includes a holding portion that holds a recording material so that a recording surface of the recording material is substantially parallel to a vertical direction, a pressing portion, and a stiffness acquiring section. The pressing portion presses a measurement point located on a lower side in the vertical direction than the portion of the recording material held by the holding portion. The stiffness acquiring section measures a reaction force obtained when the measurement point is pressed by the pressing portion and acquires the measured reaction force as the stiffness of the recording material.

Stiffness measuring device, image forming system, and stiffness measuring method

A rotation detector includes a motor, a current detector and a hardware processor. The motor includes coils of two or more phases and a rotor. The current detector detects currents flowing in coils of at least two phases among the coils of two or more phases. The hardware processor estimates an initial position of the rotor based on current values of the currents detected by the current detector to start the motor, controls an energization pattern on the phases to rotate and start the motor based on the estimated initial position, and determines whether the rotor stops or is rotating before completing the estimation of the initial position.

Rotation detector and image forming apparatus

A control circuit of a motor control device estimates an initial magnetic pole position of a rotor using an inductive sensing scheme. When estimating the initial magnetic pole position, a drive circuit applies a voltage to a stator winding at each of L electrical angles (L&#x2265;5) while changing the L electrical angles. An absolute value of an electrical angle difference of the voltage applied to the stator winding between an i-th time (2&#x2264;i&#x2264;L) and an i&#x2212;1st time is 180&#x2212;360/L degrees or more and 180+360/L degrees or less. An absolute value of an electrical angle difference of the voltage applied to the stator winding between a 1st time for initial position estimation and a last time before starting initial position estimation is 180&#x2212;360/L degrees or more and 180+360/L degrees or less.

Motor control device, image forming apparatus, and method for estimating initial position of magnetic pole of rotor

In a motor control device that controls a sensorless-type motor, a controller estimates an initial magnetic pole position of a rotor of a motor by an inductive sensing scheme while sequentially setting a plurality of energization angles. At each of the set energization angles, the controller converts peak values of currents flowing through a plurality of phases of a stator winding into a first current component having an electrical angle that is equal to a corresponding one of the set energization angles and a second current component that is different in electrical angle by 90 degrees from the first current component, to correct the first current component based on the second current component. The controller estimates the initial magnetic pole position of the rotor based on the corrected first current component that is obtained at each of the set energization angles.

Motor control device, method of estimating initial position of magnetic pole of rotor, and image forming apparatus

In a motor control device in one embodiment, an initial position estimation unit estimates an initial position of a magnetic pole of a rotor of a motor in an inductive sensing scheme. At each of energization angles, the initial position estimation unit multiplies a &#x3b3;-axis current component I&#x3b3; corresponding to a peak value of a current flowing through a stator winding by each of a cosine value and a sine value of a correction angle obtained by correcting each of the energization angles. The initial position estimation unit estimates the initial position of the magnetic pole of the rotor based on a ratio between an integrated value of a multiplication result about the cosine value and an integrated value of a multiplication result about the sine value.

A motor controller that controls a motor in which a rotor using a permanent magnet is rotated by a rotating magnetic field due to a current flowing through a winding: performs hold control that continuously causes a fixed excitation current to flow through the winding to cause a fixed magnetic field for suppressing rotation of the rotor to be generated in a suspension period in which the motor is stopped; performs hold enhancement control that enhances the fixed magnetic field with input of a timing signal defined in advance as a trigger, in the suspension period; and starts rotational excitation control that generates the rotating magnetic field when a rotation start timing arrives.

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Toyokawa, Japan

Kazumichi Yoshida