Pickup movement device for detecting speed using pickup driving coil
AssigneeOlympus Optical Co., Ltd.
InventorShouji Yoshikawa
Life of this patent
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Abstract
A pickup movement device includes a plurality of electromagnetic driving coils for moving a pickup. It supplies a driving signal to these plurality of electromagnetic driving coils for the purpose of accessing a target track. The movement speed of the pickup can be detected by a track error signal during access. This track error signal is monitored at access time to see whether the pickup device is within an allowable range. When it is out of the allowable range, a speed signal is detected by one of the plurality of electromagnetic driving coils, which is used to prevent a runaway of the pickup.
Claims16
A pickup movement device, comprising:
- light beam generating means for generating a convergent light beam;
- an optical pickup having a photo detector for condensing said light beam and irradiating an optical recording medium with said light beam and for receiving light reflected from the optical recording medium;
- first and second electromagnetic driving coils for moving said optical pickup in a direction in which tracks of said optical recording medium are crossed;
- driving signal generation means for supplying a driving signal to said first and second electromagnetic driving coils in order to move said optical pickup;
- abnormality judgment means for determining whether a track error signal deviates from a predetermined allowable range and producing an output signal indicating an abnormality condition;
- control means receiving the output signal of said abnormality judgment means, for controlling the movement of said optical pickup when said abnormality judgment means determines an abnormality condition;
- switching means receiving a signal from said control means for selectively cutting off said driving signal from said first electromagnetic driving coil when said abnormality judgment means determines an abnormality condition;
- and
- speed signal detection means for detecting a speed signal corresponding to the movement speed of said optical pickup from said first electromagnetic driving coil to which said driving signal is not supplied when said abnormality judgment means determines an abnormality condition;
- wherein, during an abnormality condition, said control means for controlling the movement of said optical pickup supplies a control signal based on said speed signal to said second electromagnetic driving coil.
Dependencies are inferred from the claim text.