JP2958931B2 - Disc playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk reproducing apparatus, and more particularly, to a disk reproducing apparatus suitable for detecting missing or scratched information on a disk surface and compensating for a track jump.

[0002]

2. Description of the Related Art Conventionally, many servo loops of a disk reproducing apparatus using an optical pickup are shown in a block diagram of a main part shown in FIG. In FIG. 1, reference numeral 1 denotes a disc on which information signals are recorded. The recording signal of the disc 1 is an optical pickup 2 (hereinafter referred to as an optical pickup 2).
), And the RF modulated signal is supplied to the signal processing circuit 5 via the RF amplifier 4 and reproduced.

Reference numeral 6 denotes a mirror surface missing detection circuit. The mirror surface missing detecting circuit 6 detects that the optical pickup 2 has jumped the recording information track on the disk 1 based on the RF signal and outputs a track jump signal. . Reference numeral 7 denotes an information surface missing detection circuit. The information surface missing detecting circuit 7 detects information missing on a track, controls a servo drive circuit 9 forming a servo loop, and performs tracking servo and focus of the optical pickup 2. Servo is performed.

[0006] The above-mentioned information surface loss detecting circuit 7 of the servo loop of the disk reproducing apparatus thus constructed is, for example, shown in FIG.
The circuit configuration described above was generally used. FIG. 7 is a waveform chart showing the operation of the information plane missing detection circuit 7 shown in FIG.

In FIG. 6, a voltage applied to an input terminal (IN) is applied.
The RF signal (in) is inverted and amplified by a defect amplifier (DEFECT AMP), and this defect amplifier output signal (g) is bottom-held with a long and short two time constants via a diode.
The short time constant bottom hold output signal (m) responds to the lack of the mirror surface (mirror surface) of the disk 1, and the long time constant bottom hold output signal (n) bottom-holds the mirror surface level immediately before the loss. This long and short time constant bottom hold output signal (m),
By comparing (n) with the comparison circuit (DEFECT COPARATOR), the information loss detection signal (p) of the mirror surface was output from the output terminal (OUT).

As described above, the lack of information is detected by the missing information surface detecting circuit 7, and when the detected missing information is detected, the drive of the servo drive circuit 9 of the servo loop is cut off and the optical pickup 2 is turned off.
Was prevented beforehand.

[0007]

However, in the above-described conventional disk reproducing apparatus, the detection function of the information surface loss detecting circuit 7 due to a scratch on the surface of the disk 1 is that the reproduction output of the optical pickup 2 is reduced due to a scratch or the like. Is detected to detect the lack of the information surface, and depending on the shape of the scratches on the disk 1, the scratches may look like a mirror surface and the optical pickup 2
However, there is a drawback that the output of the information becomes large and the information loss cannot be detected.

In order to detect such a flaw, Japanese Patent Laid-Open No. Sho 62-80842 discloses that a mirror surface envelope signal is compared with a predetermined level only during reproduction. However, a configuration that detects a decrease and an increase in the reproduction output of the optical pickup has not been generally used because the circuit configuration becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to detect a decrease and an increase in the reproduction output of an optical pickup and to more reliably detect missing of a disk surface. in order to realize the controls by muting control signal of the audio signal of the first audio reproduction circuit superimposed muting circuit to the output signal of the bottom-hold circuit of the information surface loss detecting means output signal of the mirror surface loss detecting means Thereby, the circuit configuration is simplified by sharing a part of the circuit configuration, and
Another object of the present invention is to reduce the number of control signals of a microcomputer by using control signals used for other purposes.

[0010] A disk reproducing apparatus according to the present invention includes a first bottom hold circuit for bottom-holding a first time constant from an RF signal reproduced by an optical pickup, and a first bottom hold circuit longer than the first time constant from the RF signal. A second bottom hold circuit for bottom holding with a time constant of 2;
A differential circuit for differentiating and level-shifting the output of the bottom hold circuit by capacitor coupling, the differential circuit and the second
A comparator for comparing the output of the bottom hold circuit with the output of the bottom hold circuit, an information surface missing detecting means for detecting information missing on the disc by an output of the comparing circuit, and the optical pickup based on an output of the information surface missing detecting means. Switching control means for interrupting the servo loop, pre-value holding means for holding the servo error signal of the servo loop at a previous value when the servo loop is interrupted by the switching control means, and a mirror on a disk from the RF signal. In a disk reproducing apparatus provided with a mirror surface missing detecting means for detecting a surface, and a mute circuit for muting an output signal of the mirror surface missing detecting means, an output signal of the mirror surface missing detecting means is coupled to the capacitor coupling of the differentiating circuit. Unit, superimposes on the output of the first bottom hold circuit, By controlling the muting circuit by muting control signal of the audio signal reproducing circuit, at the time of normal reproduction or the information surface loss detecting means
Missing information detection signal of the information and the mirror surface missing detecting means
The information loss on the disk is detected by a mirror surface loss detection signal from the CPU, and the mute circuit of the mute circuit is operated except for normal reproduction to detect the information loss on the disk by the information loss detection signal. It is.

[0011]

[0012]

According to the present invention, the mirror output signal of the mirror surface missing detection circuit for detecting the mirror surface missing on the disk by the RF signal reproduced from the optical pickup is added to the information surface missing detecting circuit to detect the information surface missing. The mirror output signal is superimposed on the bottom hold output of the circuit to obtain a defect output from the information surface loss detection circuit.

A switching circuit provided in a servo loop for servo-controlling the optical pickup is controlled by the defect output, and when an information surface loss detecting circuit detects a loss of information and the defect output is set to "H level", The above-mentioned switching circuit can be turned off to interrupt the servo loop.

When the servo loop is interrupted, the servo loop is held at the previous value by the capacitor C1 connected to the servo loop, and the interrupted servo loop is fixed at the previous value hold level to perform servo control of the optical pickup.

As described above, by superimposing the mirror output signal of the mirror surface missing detection circuit on the defect output of the information surface missing detecting circuit, a scratch or the like on the disk forms a mirror surface so that the information is lost. It is possible to accurately detect even a flaw that cannot be detected.

In particular, in order to detect a decrease and an increase in the reproduction output of the optical pickup, an output signal of the mirror surface missing detecting means is superimposed on an output signal of the first bottom hold circuit of the information surface missing detecting means by an audio mute circuit. The adoption of the configuration in which the audio signal of the reproduction circuit is controlled by the muting control signal allows the circuit configuration to be simplified by sharing a part of the circuit configuration, and is used for other purposes. The number of control signals of the microcomputer can be reduced by using the same muting control signal.

When the mute circuit of the audio reproduction circuit of the disk reproduction apparatus is controlled to mute ON, the muting control signal goes to "L level". Is clamped to the ground level and the mirror output is
Control to OFF.

That is, when performing a search operation of the disk reproducing apparatus, the mute circuit is set to ON, and the optical pickup is moved in the radial direction of the disk to perform a track jump to search for recorded information on the disk. As described above, when the optical pickup jumps a track, the servo loop of the optical pickup is interrupted as described above, and the servo control is performed at the previous value hold level. Thereafter, the reproducing operation can be performed accurately and speedily.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a disk reproducing apparatus according to the present invention will be described with reference to FIGS. The same parts as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted. FIG. 1 is a block diagram of a main part, and FIG.
And a circuit diagram showing an embodiment of the information surface missing detection circuit 7,
FIG. 3 is a waveform chart of each part showing the operation of the mirror surface missing detection circuit 6, and FIG. 4 is a waveform diagram of each part showing the operation of the information surface missing detecting circuit 7.

In FIG. 1, reference numeral 8 denotes a switching circuit for interrupting a servo loop. This switching circuit 8 is controlled to be switched by a detection signal of an information surface loss detection circuit 7, and a capacitor C1 is a capacitor forming a previous value hold circuit. . Further, the information surface missing detection circuit 7 is connected as shown in the figure so that the mirror output signal of the mirror surface missing detecting circuit 6 is supplied.

The missing-mirror-surface detection circuit 6 is, for example, as shown in FIG.
1 is generally used, and the operation waveform of each part of the mirror surface missing detection circuit 6 will be described with reference to FIG.

The RF signal (“in” waveform in FIG. 3) applied to the input terminal (IN) of the mirror surface missing detection circuit 6 is applied to a mirror amplifier (M
IRROR AMP) is inverted and amplified, and this mirror amplifier output signal
(a) is peak-held (b) and bottom-held (c) via a diode. The time constant of the peak hold (b) is set so as to follow the traverse, and the time constant of the bottom hold (c) is set so as to follow the envelope fluctuation of the rotation cycle of the disk 1.

The peak and bottom hold signals (b),
In (c), an envelope signal (d) reproduced by DC by the differential amplifier is obtained, and the level of the peak value of the envelope signal (d) is 2/3 of the output signal (e) of the mirror hold amplifier.
And a mirror comparison circuit (MIRROR COMPARATOR), the mirror output signal (f) can be output from the output terminal (OUT).

That is, the mirror output (f) becomes "L level" on the track of the disk 1, and the distance between the tracks (mirror surface)
In this case, the signal is output at "H level". Also, when the lack of the mirror surface is detected, “H level” is output.

As described above, the mirror output signal (f) of the mirror surface missing detection circuit 6 is output as a track jump signal, while the mirror output signal (f) is output from the diode D1 and the resistor D1.
Mirror input terminal (MIR
R IN) as an input signal (k). This mirror input terminal (MIRR IN) is connected to a bottom hold (DEFEC) which operates with a short time constant of the information plane missing detection circuit 7 configured in the same manner as the conventional example.
T BOTTOM HOLD) circuit output is connected to the non-inverting input (+) of the capacitor-coupled comparison circuit (DEFECT COMPARATOR).

That is, by adding the input signal (k) generated from the mirror output signal (f) of the mirror surface missing detection circuit 6 to the short time constant bottom hold output signal (h) of the information surface missing detecting circuit 7. The defect output (DEFECT OUT) of the information surface missing detection circuit 7 compares the composite signal of the bottom hold output signal (h) and the mirror input signal (k) with the long time constant bottom hold output signal (i). COMPARATOR) to output the defect output signal (j) compared.

That is, the information surface missing detection circuit 7
If the mirror output signal (f) goes to "H level" even when the track information loss is not detected, the defect output signal (j) of the information surface loss detection circuit 7 goes to "H level" and is output. .

If the switching circuit 8 is constituted as shown in FIG. 2 by, for example, the transistor Q1 and the FET Q2, when the defect output (j) becomes "H", the transistor Q1 is turned off, and the diode D3 and the resistor R are turned off.
2 also sets the gate of FET Q2 to a negative voltage,
Cut off TQ2. That is, the servo loop of the disk reproducing apparatus is interrupted by the switching circuit 8, and in the state where the servo loop is interrupted, the operating point of the servo drive circuit 9 is determined by the previous value hold circuit of the capacitor C1 which has held the immediately previous operation level. Once set, the servo loop circuit can perform constant servo control.

As described above, since the servo loop is interrupted by the missing information detected by the missing information surface detecting circuit 7 and the detection by the missing mirror surface detecting circuit 6, the focus servo or the tracking servo operation is performed to operate the optical pickup 2.
However, it is possible to prevent such a problem that a large deviation from the track on the disk 1 takes a long time to return the servo operation during reproduction.

If the simulated scratches on the disc or the scratches on the actual disc 1 form a mirror surface and the information missing detection circuit 7 cannot detect missing information, the mirror surface missing detecting circuit 6 detects the information missing. Since the detected lack of the mirror surface is detected and applied to the information surface missing detection circuit 7,
The ability of the optical pickup 2 to detect flaws and the like due to the RF signal is improved, the flaw passing ability is increased, and the servo loop is interrupted.
Since the servo control based on the previous value hold operates, the playability of the reproduction of the disc reproducing apparatus is sufficiently exhibited.

When the disc reproducing apparatus performs an address search operation for recorded data, the optical pickup 2
Is moved in the radial direction to perform a track jump operation on the disk 1. In general, during the search operation, the disk reproducing apparatus controls the mute circuit of the reproducing circuit to turn on the mute.
And muting control is performed.

The mirror input terminal (MI) of the mirror output signal (f) of the output terminal (OUT) of the mirror surface missing detection circuit 6 shown in FIG.
RR IN) is connected to the mute circuit 10 via the diode D2 as shown in the figure. Since the output terminal of the mute circuit 10 is set to “L level” when the reproduction output of the mute ON is shut off, the mirror input terminal (MIRR IN ) Is set to "L level" by the diode D2, the mirror output signal (f) of the mirror surface missing detection circuit 6 is clamped to the ground level, and the output of the mirror output signal (f) is turned off.

That is, since the mirror output signal (f) of the mirror surface missing detection circuit 6 is not superimposed on the defect output of the information surface missing detecting circuit 7, the mirror surface missing due to the track jump at the time of the search operation of the disk reproducing apparatus described above. Is not detected.

As described above, when the disc reproducing apparatus performs the search operation, the servo loop operates normally, the target recording data is searched while operating the tracking servo system, and the search recording information is accurately obtained in the tracked state. Can be played.

On the other hand, when the disk reproducing apparatus is performing the normal reproducing operation, the mute circuit 10 is set to mute OFF, the output terminal of the mute circuit 10 becomes “H level”, and the mirror surface missing detection circuit 6 detects Mirror output signal
(f) is supplied to the missing information surface detection circuit 7, and the servo loop can be cut off as described above.

The above-described mirror surface missing detecting circuit 6 and information surface missing detecting circuit 7 have been described by using the generally used IC: CXA1372 manufactured by Sony. The function of connection with the surface loss detection circuit 7 and the function of controlling the servo loop by providing the switching circuit 8 is not limited to the above-described IC, but can be applied to other ICs or other circuit configurations.

In the disk reproducing apparatus according to the present invention, the output signal of the mirror surface missing detecting means is superimposed on the output signal of the first bottom hold circuit of the information surface missing detecting means , and a mute circuit is provided for muting the audio signal of the audio reproducing circuit. By adopting a configuration controlled by a switching control signal, it is possible to more reliably detect the disc surface loss without increasing the number of control signals of the microcomputer with a simplified circuit configuration.

Moreover, it has excellent features such as a simple structure and an easy implementation because it can be constructed at a low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part showing an embodiment of a disk reproducing apparatus according to the present invention.

FIG. 2 is a circuit diagram showing one embodiment of a mirror surface missing detection circuit and an information surface missing detecting circuit according to the present invention.

FIG. 3 is a waveform diagram showing operation waveforms of various parts of the mirror surface missing detection circuit.

FIG. 4 is a waveform diagram showing operation waveforms of each part of the information surface missing detection circuit.

FIG. 5 is a block diagram of a main part of a conventional example.

FIG. 6 is a circuit diagram of a conventional information surface missing detection circuit.

FIG. 7 is a waveform diagram showing operation waveforms of various parts of a conventional information surface missing detection circuit.

[Explanation of symbols]

 Reference Signs List 1 disc 2 optical pickup 3 spindle motor 4 RF amplifier 5 signal processing circuit 6 missing mirror surface detection circuit 7 missing information surface detection circuit 8 switching circuit 9 servo drive circuit 10 mute circuit

Claims (1)

(57) [Claims] 1. An R pickup reproduced by an optical pickup.
A first bottom hold circuit that bottom-holds the F signal at a first time constant, a second bottom hold circuit that bottom-holds the RF signal at a second time constant longer than the first time constant, A differential circuit for differentiating and level-shifting the output of the first bottom hold circuit by capacitor coupling, and a comparator for comparing the output of the second differential circuit with the output of the second bottom hold circuit. Information surface missing detection means for detecting the above information missing, switching control means for interrupting the servo loop of the optical pickup by an output of the information surface missing detecting means, and when the servo loop is interrupted by the switching control means. A pre-value holding means for pre-holding a servo error signal of the servo loop; A disk reproducing apparatus comprising: a mirror surface missing detecting means for detecting a mirror surface on a disk; and a mute circuit for muting an output signal of the mirror surface missing detecting means. superimposed by the condenser coupling unit to the output of the first bottom hold circuit, by controlling the muting circuit by muting control signal of the audio signal of the audio reproduction circuit, the information surface missing during normal reproduction
Information missing detection signal from the detecting means and the mirror surface missing
Detecting information loss on the disk by detecting a mirror surface loss detection signal from the drop detection means and activating the mute circuit of the mute circuit except for normal reproduction, thereby detecting information loss on the disk by the information loss detection signal. A disk reproducing device characterized by the above-mentioned.