Optical disc apparatus
First Claim
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1. An optical disk apparatus, comprising:
- a converging means for converging and irradiating a light beam from a light source toward a rotating information carrier;
a focus displacement signal detection means for generating a signal in accordance with a positional displacement of a focus of the light beam with respect to an information surface of the information carrier;
a focus shifting means for shifting the converging means in a direction normal to the information surface of the information carrier;
a focus control means for driving the focus shifting means in accordance with the signal from the focus displacement signal detection means, and performing a control such that the focus of the light beam follows the information surface of the information carrier;
an information surface detection means for detecting whether the focus of the light beam is near the information surface of the information carrier, if the focus control means is in an inoperative state; and
a collision evasion means for generating a driving signal for the focus shifting means such that the converging means is displaced in a direction away from the information carrier if a signal is generated by the information surface detection means.
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Abstract
An optical disk apparatus having a high reliability by evading collision between a condensing lens and an optical disk regardless whether the focus control is in the operative state or in the inoperative state, thereby preventing damage to the condensing lens and the optical disk. When the focus control is in the inoperative state, by using a reflection light amount from the optical disk (1), it is ascertained that the focus of the light beam is in the vicinity of the information surface and the condensing lens (15) is driven to be apart from the optical disk (1).
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Citations
36 Claims
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1. An optical disk apparatus, comprising:
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a converging means for converging and irradiating a light beam from a light source toward a rotating information carrier;
a focus displacement signal detection means for generating a signal in accordance with a positional displacement of a focus of the light beam with respect to an information surface of the information carrier;
a focus shifting means for shifting the converging means in a direction normal to the information surface of the information carrier;
a focus control means for driving the focus shifting means in accordance with the signal from the focus displacement signal detection means, and performing a control such that the focus of the light beam follows the information surface of the information carrier;
an information surface detection means for detecting whether the focus of the light beam is near the information surface of the information carrier, if the focus control means is in an inoperative state; and
a collision evasion means for generating a driving signal for the focus shifting means such that the converging means is displaced in a direction away from the information carrier if a signal is generated by the information surface detection means. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
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2. An optical disk apparatus, comprising:
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a converging means for converging and irradiating a light beam from a light source toward a rotating information carrier;
a focus displacement signal detection means for generating a signal in accordance with a positional displacement of a focus of the light beam with respect to an information surface of the information carrier;
a focus shifting means for shifting the converging means in a direction normal to the information surface of the information carrier;
a focus control means for driving the focus shifting means in accordance with the signal from the focus displacement signal detection means, and performing a control such that the focus of the light beam follows the information surface of the information carrier;
a vibration detection means for detecting a vibration of the apparatus; and
a collision evasion means for generating a driving signal for the focus shifting means such that the converging means is displaced in a direction away from the information carrier if a signal of at least a predetermined value is generated by the vibration detection means.
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10. An optical disk apparatus, comprising:
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a converging means for converging and irradiating a light beam from a light source toward a rotating information carrier;
a focus displacement signal detection means for generating a signal in accordance with a positional displacement of a focus of the light beam with respect to an information surface of the information carrier;
a focus shifting means for shifting the converging means in a direction normal to the information surface of the information carrier;
a focus control means for driving the focus shifting means in accordance with the signal from the focus displacement signal detection means, and performing a control such that the focus of the light beam follows the information surface of the information carrier; and
a collision evasion means for constantly generating a driving signal for the focus shifting means such that the converging means is displaced in a direction away from the information carrier if the focus control means is in an inoperative state.
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11. An optical disk apparatus, comprising:
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a converging means for converging and irradiating a light beam from a light source toward an information carrier having a spiral-shaped track that has a tiny fluctuation in radial direction at a predetermined period;
a focus displacement signal detection means for generating a signal in accordance with a positional displacement of a focus of the light beam with respect to an information surface of the information carrier;
a focus shifting means for shifting the converging means in a direction normal to the information surface of the information carrier;
a focus control means for driving the focus shifting means in accordance with the signal from the focus displacement signal detection means, and performing a control such that the focus of the light beam follows the information surface of the information carrier;
a fluctuation amplitude detection means for detecting an amplitude of the fluctuation of the track; and
an anomaly detection means for judging, from an amplitude change over a predetermined time of a signal from the fluctuation amplitude detection means, whether the operation of the focus control means is anomalous, and generating a driving signal for the focus shifting means such that the converging means is displaced in a direction away from the information carrier. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. An optical disk apparatus, comprising:
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a converging means for converging and irradiating a light beam from a light source toward a rotating information carrier;
a focus displacement signal detection means for generating a signal in accordance with a positional displacement of a focus of the light beam with respect to an information surface of the information carrier;
a focus shifting means for shifting the converging means in a direction normal to the information surface of the information carrier;
a focus control means for driving the focus shifting means in accordance with the signal from the focus displacement signal detection means, and performing a control such that the focus of the light beam follows the information surface of the information carrier; and
an anomaly detection means for judging that the operation of the focus control means is anomalous when a change in the signal from the focus displacement signal detection means over a predetermined time is within a predetermined range, and generating a driving signal for the focus shifting means that is such that the converging means is displaced in a direction away from the information carrier. - View Dependent Claims (19, 20, 21, 22, 23)
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24. An optical disk apparatus, comprising:
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a converging means for converging and irradiating a light beam from a light source toward a rotating information carrier;
a focus displacement signal detection means for generating a signal in accordance with a positional displacement of a focus of the light beam with respect to an information surface of the information carrier;
a focus shifting means for shifting the converging means in a direction normal to the information surface of the information carrier;
a focus control means for driving the focus shifting means in accordance with the signal from the focus displacement signal detection means, and performing a control such that the focus of the light beam follows the information surface of the information carrier;
a focus integration means for integrating the signal from the focus displacement signal detection means when a change of the signal from the focus displacement signal detection means is within a predetermined range;
a clearing means for clearing an integration value of the focus integration means when the change of the signal from the focus displacement signal detection means exceeds the predetermined range; and
an anomaly detection means for judging that the operation of the focus control means is anomalous when the absolute value of the integration value of the focus integration means is at least a predetermined value, and generating a driving signal for the focus shifting means that is such that the converging means is displaced in a direction away from the information carrier. - View Dependent Claims (25, 26, 27, 28)
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29. An optical disk apparatus, comprising:
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a converging means for converging and irradiating a light beam from a light source toward a rotating information carrier;
an optical detection means for partitioning and receiving the light beam reflected by the information carrier;
a focus displacement signal detection means for generating a signal in accordance with a positional displacement of a focus of the light beam with respect to an information surface of the information carrier, by calculating a differential of partitioned regions of the optical detection means;
a focus shifting means for shifting the converging means in a direction normal to the information surface of the information carrier;
an offset application means for applying an offset to the signal from the focus displacement signal detection means;
a focus control means for driving the focus shifting means in accordance with the signal from the focus displacement signal detection means and the offset application means, and performing a control such that the focus of the light beam follows the information surface of the information carrier; and
a vibration detection means for detecting a vibration of the apparatus;
wherein, based on the signals from the vibration detection means, the offset application means applies such an offset that the converging means is displaced in a direction away from the information carrier. - View Dependent Claims (30, 31, 32)
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33. An optical disk apparatus, comprising:
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a converging means for converging and irradiating a light beam from a light source toward a rotating information carrier;
a focus displacement signal detection means for generating a signal in accordance with a positional displacement of a focus of the light beam with respect to an information surface of the information carrier;
a focus shifting means for shifting the converging means in a direction normal to the information surface of the information carrier;
a focus control means for driving the focus shifting means in accordance with the signal from the focus displacement signal detection means, and performing a control such that the focus of the light beam follows the information surface of the information carrier; and
a search means for shifting the converging means such that the light beam is irradiated onto a desired track on the information carrier;
wherein the search means sets the focus control means to an inoperative state when the focus control means is operative. - View Dependent Claims (34, 35, 36)
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Specification