Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Reexamination Certificate
1998-07-15
2001-07-10
Hindi, Nabil (Department: 2753)
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
C369S047450, C369S053130, C369S053140, C369S053180
Reexamination Certificate
active
06259661
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to an apparatus for reading a disk, such as CD-ROM, CD-R, DVD-ROM, DVD-RAM, etc., in which digital data have been recorded in a spiral track, and particularly relates to a disk reading apparatus by which the rotary speed of the disk is lowered when vibration is generated due to eccentric center of gravity of the disk.
2. Background of the Related Art
In a disk reading apparatus for reading data from a CD-ROM, in order to shorten the time taken to read data, the CD-ROM is rotated to read the data at a speed higher than a normal speed, for example, at a 8-fold speed, a 16-fold speed, or the like. On the other hand, the specification regarding the eccentric center of gravity of the CD-ROM is set to a value which causes no problem in reading data in the condition that the CD-ROM is rotated at the normal speed. Therefore, when the CD-ROM is rotated at a speed higher than the normal speed, there may be a case where the eccentric center of gravity becomes strongly influential to increase the quantity of vibration to thereby cause a difficulty in data-reading. In the case where a CD-ROM is rotated at a high speed, therefore, it is detected whether vibration is generated or not so that the rotary speed can be lowered to read data when vibration is detected.
To this end, conventionally, Unexamined Japanese Patent Publication No. Hei-4-143928 has proposed a technique in which whether vibration is generated or not is detected when a disk is rotated. That is, in this technique, mechanical vibration of a rotation driving section for rotating a disk is detected by means of a sensor. The output of the sensor is fed to a band-pass filter, while the frequency of the band-pass filter is set to a frequency corresponding to the rotary speed of the disk. Accordingly, only a frequency component corresponding to the rotary speed of the disk is outputted from the band-pass filter. The signal outputted from the band-pass filter is led to a window comparator in which the signal is binarized and supplied to the external section as an abnormal detection signal.
When the above-mentioned configuration is adopted, however, a problem had arisen as follows. That is, when an external impact was given to the reader, strong vibration was generated in the reading apparatus. This strong vibration was detected by the sensor. On the other hand, the attenuation property of the band-pass filter became comparatively gentle so as to be about 6 dB/octave when the circuit configuration was simplified. Therefore, when a frequency component near the pass frequency of the band-pass filter was included in the output of the sensor detecting the vibration caused by the impact, an abnormal detection signal was outputted due to the impact. Therefore, in a situation where a portion of a human body or the like hit against a desk on which the reading apparatus was located to give an impact to the apparatus, an abnormal detection signal was sent out. Accordingly, notwithstanding the capability of being read at a high rotary speed, the disk was read at a low rotary speed so that the reading speed was thus lowered.
SUMMARY OF THE INVENTION
To solve the foregoing problem, therefore, the first object of the present invention, to provide a disk reading apparatus in which a period of a binarized signal is detected, and it is judged that vibration is generated by eccentric center of gravity when the detected period corresponds to the rotary speed of the disk, so that it is possible to prevent erroneous conclusion from occurring in the judgement of vibration due to the eccentric center of gravity.
In addition, the second object of the present invention is to provide a disk reading apparatus wherein it is possible to simplify the configuration of the binarization circuit in which only a frequency component corresponding to the rotary speed of the disk is allowed to pass.
To achieve the first object of the present invention, there is provided a disk reading apparatus for reading data recorded on a disk medium which comprises: a motor for rotating the disk medium; a vibration sensor section for detecting vibrations generating inside the disk reading apparatus and for converting the vibrations into a signal; a binarized signal generation section for extracting only a frequency component corresponding to the rotary speed of the disk medium from the signal outputted from the vibration sensor section, and for outputting a signal in which a binaraization is performed, a vibration judgement section for measuring a period of the binarized signal outputted from the binarized signal generation section and for outputting a vibration detection signal when the period of the binarized signal corresponds to the rotary speed of the disk medium; and a rotation control section for lowering the rotary speed of the disk medium when the vibration detection signal is inputted.
That is, the binarized signal generation section extracts only a frequency component corresponding to the rotary speed of the disk from the output of the vibration sensor section. The binarized signal generation section binarizes the extracted component. Accordingly, a binarized output is sent out from the binarized signal generation section in accordance with the vibration caused by the impact when a frequency component of vibration caused by an external impact includes a component near the frequency corresponding to the rotary speed of the disk. On the other hand, the vibration judgement section sends out a vibration detection output when the period of the binarized output corresponds to the rotary speed of the disk. This means that no vibration detection output is sent out when the period of the binarized output is near the period corresponding to the rotary speed of the disk. Accordingly, no vibration detection output is sent out when vibration is generated by an external impact.
In addition, according to the present invention, the binarized signal generation section includes: an amplifier circuit amplifying the output signal from the vibration sensor section; a transistor binarizing an output of the amplifier circuit; a high-pass filter connected between an output terminal of the amplifier circuit and a base of the transistor, and constituted by a series connection of a capacitor and a resistor; and a low-pass filter constituted by a load resistor connected between a collector of the transistor and a positive power source, and an integrating capacitor connected between the collector and a ground level, and wherein a central frequency of band-pass characteristic constituted by the high-pass filter and the low-pass filter is made to be a frequency corresponding to the rotary speed of the disk medium.
That is, the resistor connected between the output terminal of the amplifier circuit and the base, and the load resistor connected between the collector and the positive power source are elements indispensable to cause the transistor connected to the output of the amplifier circuit to perform binarization. On the other hand, the high-pass filter is connected between the output terminal of the amplifier circuit and the base, and constituted by a series connection of a capacitor and a resistor. The low-pass filter is constituted by a load resistor connected between the collector and the positive power source, and an integrating capacitor connected between the collector and the ground level. That is, the high-pass filter and the low-pass filter are constituted by the resistors which are indispensable elements and the capacitors combined with those resistors. That is, by adding only two capacitors to the indispensable resistors, a required band-pass characteristic can be obtained.
REFERENCES:
patent: 5202872 (1993-04-01), Shinada
patent: 5668789 (1997-09-01), Yokota et al.
patent: 6009053 (1999-12-01), Ota et al.
patent: 6016296 (2000-01-01), Kim
patent: 4-143928 (1992-05-01), None
patent: 7-184386 (1995-07-01), None
patent: 8-106714 (1996-04-01), None
008929 Japan technical evaluation for Utility Model
Funai Electric Co. Ltd.
Hindi Nabil
Lackenbach Siegel Marzullo Aronson & Greenspan
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