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AssigneeVictor Company of Japan, Ltd.
InventorsShigeyoshi Mori, Ryuji Mizuguchi
Estimating the term…
The specification discloses an NRR (Non-Repeatable Run-out) measuring instrument for measuring the NRR of the rotating object motor to be measured without installation of a special attachment such as an encoder. In the NRR measuring instrument of the invention, encoder signals are obtained from back-electromotive forces developed at driving coils of the rotating object motor by removing spike noise thereof by LPF 30U, 30V, 30W and reformed by a wave shaping circuits 32U, 32V, 32W. The encoder signals together with digitized displacement signals generated by noncontact displacement measuring instrument 14 through A/D 28 are inputted to a CPU 34. In the CPU 34, sampled data are acquired from the digitized displacement signals being triggered by the encoder signals and the NRR is calculated based on the sampling data.
An NRR (Non-Repeatable Run-out) measuring instrument for measuring an NRR of a motor having driving coils and a rotor by using displacement data obtained by measuring displacement values produced due to run-out of the rotor of the motor, comprising:
An NRR measuring instrument as claimed in claimed 1, further comprises a driving circuit for driving the driving coils of the motor.
An NRR measuring instrument as claimed in claimed 1, wherein the encoder signal generating means comprises a low-pass filter for removing spike noises from the output of the back-electromotive force and a wave-shaping circuit for shaping a waveform of the back-electromotive force to obtain the encoder signals.
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Driving; Starting; Stopping; Control thereof: turntables, hubs and motors for disk drives; Mounting of motors in the drive
By influencing the self-induction of one or more coils: by movable a non-ferromagnetic conductive element
Devices characterised by the use of electric or magnetic means: for measuring angular speed
Constructional parts, details or accessories not provided for in the other groups of this subclass: indicating arrangements; Warning arrangements
Term ended 8 Apr 2013 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to a Non-Repeatable Run-Out (referred to as NRR hereafter) measuring instrument for a motor and it particularly relates to an NRR measuring instrument suitable for a thin-type HDD (Hard Disc Drive) employing a sensorless motor as a spindle motor.
2. Description of the Related Art
FIGS. 1 (A) through (C) are explanatory figures showing an NRR measuring method of a prior art.
FIG. 2 is a schematic diagram showing another NRR measuring method of the prior art.
FIG. 3 is a construction diagram of an embodiment of the NRR measuring instrument according to the present invention.
An embodiment of NRR measuring instrument of a motor according to the present invention will be described with reference to the drawings, in which identical components to those of the described conventional examples are depicted by identical characters without detailed explanation thereof.
FIG. 3 is a construction diagram of an embodiment of the NRR measuring instrument according to the present invention.
FIG. 4 is a functional block diagram of a CPU shown in FIG. 3.