Rotating recorder with dual encoder arrangement having eccentricity compensation
AssigneeSeagate Technology LLC
InventorsLawrence Bryant, Sundeep Chauhan, David Kuo
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Abstract
A rotating recording device, such as an electron beam recorder, is provided with a dual encoder arrangement. A first encoder is employed as a spindle motor controller and located at a first end of a spindle. A second encoder is mounted at a turntable adjacent to a recording surface and used as a position, velocity or clock source for recording the pattern on the substrate. Eccentricity of the mounting of the second encoder is measured against the more accurately mounted spindle control encoder and compensated by a digital clock generating system using a digital phase locked loop.
Claims20
An electron beam recorder, comprising:
- a spindle motor;
- a spindle driven by the spindle motor, the spindle extending through the spindle motor through the spindle motor and having first and second ends;
- a turntable mounted at the second end of the spindle and having a central axis of rotation;
- a first encoder mounted at the first end of the spindle;
- a second encoder mounted on the turntable;
- and
- a controller coupled to the first and second encoders and the spindle motor and controlling the spindle motor and generating recording clock signals as a function of encoder signals received from the first and second encoders.
A method of controlling a rotating recording device having a spindle, a first encoder mounted on a first end of the spindle, a turntable mounted on a second end of the spindle, a second encoder mounted on the turntable, and a controller coupled to the first and second encoders and controlling the rotating recording device in accordance with signals from the first and second encoders, the method comprising:
- determining an eccentricity of the second encoder with respect to a central axis of rotation of the spindle;
- and
- compensating for the determined eccentricity in the signals from the second encoder.
An electron beam recorder, comprising:
- a turntable and motor arrangement with an encoder mounted at the turntable;
- means for compensating signals from the encoder caused by eccentricity in the mounting of the encoder.
Dependencies are inferred from the claim text.