JP2002074843A - Reference signal detection circuit for magneto-optical disk recorder-reproducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical disk recorder-reproducer which can record signals on a disk by means of the laser irradiated from an optical head. SOLUTION: The upper and lower peak levels are held about an S curve signal that is obtained by reproducing the reference signal recorded on a magneto-optical disk with an optical pickup. Meanwhile, the upper and lower slice levels are set for detecting the reference signal from the held signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk recording / reproducing apparatus configured to record a signal on a magneto-optical disk by a laser irradiated from an optical head and a magnetic field applied from a magnetic head, and in particular, to a magneto-optical disk recording / reproducing apparatus. The present invention relates to a reference signal detection circuit for detecting a reference signal recorded on a magneto-optical disk.

[0002]

2. Description of the Related Art When the temperature is locally increased by irradiating radiant energy such as a laser beam onto a magneto-optical disk, the coercive force of the magnetic field is reduced, and the magnetic domains are formed in accordance with the direction of the magnetic field acting on this area. 2. Description of the Related Art A magneto-optical disk recording / reproducing apparatus configured to perform a signal recording / reproducing operation by utilizing the arrangement has been commercialized.

[0003]

Some magneto-optical disk recording / reproducing devices divide a recording area of a magneto-optical disk into a plurality of bands, control the disk rotation speed for each band, and perform signal recording / reproducing operations. There is something to do. Such a device sets a laser output value suitable for the characteristic of each band by recording and reproducing a signal in a test writing area provided in each band before performing a signal recording operation, and sets the output value as a data. It is configured to be stored in a storage memory. Such a device is configured to set a laser output based on a laser output value stored in the data storage memory, and perform a signal recording / reproducing operation based on the laser output.

In a magneto-optical disk used in such a magneto-optical disk recording / reproducing apparatus, portions called lands and portions called grooves are provided alternately in the radial direction of the magneto-optical disk. It is configured so that a signal can be recorded in the groove. Such a magneto-optical disk has FCM (Fine Cl).
ok Mark) is recorded,
This signal is reproduced, and a recording reference signal used for performing a recording operation based on the reproduced signal is generated.

In order to accurately generate the recording reference signal described above, it is necessary to accurately perform an FCM reproduction detection operation. Such an FCM detection operation is performed by a signal reproduced by an optical pickup as an S-curve signal. Is extracted in comparison with a predetermined slice level. However, there is a problem that the detection operation cannot be performed accurately due to the influence of surface deflection due to rotation of the magneto-optical disk and tilt of the magneto-optical disk.

An object of the present invention is to provide a reference signal detection circuit for a magneto-optical disk recording / reproducing apparatus which solves the above problem.

[0007]

According to the present invention, an upper peak level and a lower peak level of an S-curve signal obtained by reproducing a reference signal recorded on a magneto-optical disk by an optical pickup are held. The upper and lower slice levels for detecting the reference signal from the held signal are set.

[0008]

FIG. 1 is a block circuit diagram showing an embodiment of a reference signal detection circuit according to the present invention, and FIG. 2 is a signal waveform diagram for explaining the operation of the present invention.

In FIG. 1, reference numeral 1 denotes a signal obtained from an optical pickup for reproducing a signal recorded on a magneto-optical disk having a signal recording area provided as a plurality of bands and lands and grooves. And outputs a reference signal called FCM recorded on the magneto-optical disk as an S-curve signal.

Reference numeral 2 denotes a variable gain amplifier circuit to which the S-curve signal output from the pickup signal output circuit 1 is input and amplifies the signal, and the gain is changed by a control signal applied to a control terminal 2C. It is configured as follows. Reference numeral 3 denotes a filter circuit which receives a signal output from the variable gain amplifier circuit 2 and removes a high frequency component which is a noise signal.
Input terminal 4A to which the output signal of
The first comparison signal input terminal 4B to which the upper slice level signal to be compared with the signal input to the first input terminal 4B and the lower slice level signal to be compared with the signal input to the input terminal 4A are input. 2 is a comparison circuit provided with a comparison signal input terminal 4C, and outputs an H (high) level signal when the input signal level is higher than the upper slice level and when the input signal level is lower than the lower slice level. It is configured to output to 4D.

An upper peak 5 receives the S curve signal amplified by the variable gain amplifier circuit 2 and holds a peak voltage above a center voltage VR which is a reference voltage for detecting a zero cross point of the S curve signal. The hold circuit 6 is a first non-inverting amplifier circuit to which the output signal of the upper peak hold circuit 5 is inputted and which amplifies the signal smoothly. The signal input terminal 4B is connected so as to be inputted as an upper slice level signal.

Reference numeral 7 denotes a lower part which receives the S curve signal amplified by the variable gain amplifier circuit 2 and holds a peak voltage below a center voltage VR which is a reference voltage for detecting a zero cross point of the S curve signal. The side peak hold circuit 8 is a second non-inverting amplifier circuit which receives the output signal of the lower peak hold circuit 7 and amplifies the signal smoothly. The output signal is provided to the comparison circuit 4. The second comparison signal input terminal 4C is connected so as to be input as a lower slice level signal.

Reference numeral 9 denotes an input of the S curve signal obtained from the filter circuit 3 and the like,
R, a zero-crossing detecting circuit for detecting a zero-crossing point by comparing with the output terminal 4D of the comparing circuit 4.
A control circuit for generating a recording reference signal used when recording a signal on a magneto-optical disk based on a signal output from the zero-cross detection circuit 9 and a signal output from the zero-cross detection circuit 9. A switching signal output terminal 10A is provided which outputs an H-level signal when the signal is in the state and outputs an L (low) level signal when the signal is being recorded in the groove.

Reference numeral 11 denotes a switch provided with a first input terminal 11A and a second input terminal 11B and a control terminal 11C connected to a switching signal output terminal 10A provided in the control circuit 10. A circuit that outputs a signal input to a first input terminal 11A to an output terminal 11D when an H level signal is applied to the control terminal 11C, and outputs an L signal to the control terminal 11C.
When the level signal is applied, the signal input to the second input terminal 11B is output to the output terminal 11D. And the output terminal 11D
Is connected to a control terminal 2C provided in the variable gain amplifier circuit 2.

A first inverting amplifier circuit 12 receives a signal held by the upper peak hold circuit 5 and inverts the signal, and has an output terminal connected to a first input terminal 11A of the switching circuit 11. Have been. A second inverting amplifier 13 receives a signal held by the lower peak hold circuit 7 and inverts the signal, and has an output terminal connected to a first input terminal 11A of the switching circuit 11. I have.

In such a configuration, the variable gain amplifier circuit 2 is configured such that the gain increases when the level of the control signal applied to the control terminal 2C increases, and the gain decreases when the level of the control signal decreases. I have.

Although the present invention is configured as described above, its operation will now be described with reference to the signal waveform diagram shown in FIG. FIG. 2A shows an S-curve signal obtained when a reference signal recorded on the magneto-optical disk is reproduced when a land provided on the magneto-optical disk is used, and FIG. FIG. 7 shows an S-curve signal obtained when a reference signal recorded on a magneto-optical disk is reproduced when a groove provided on the magneto-optical disk is used.

As is apparent from these drawings, there is a relationship in which the phase of the S-curve is inverted between when the land is used and when the groove is used. First, the case of using the land shown in FIG. 2A will be described. As shown in FIG. 2A, when the land is used, the S curve signal reproduced earlier is above the center voltage VR, and the peak level of the signal above this is held by the upper peak hold circuit 5. Will be done. Further, the peak level of the lower signal constituting the S curve is held by the lower peak hold circuit 7.

The signal held by the upper peak hold circuit 5 is smoothed and amplified by a first non-inverting amplifier circuit 6, and then input to a first comparison signal input terminal 4B provided in the comparator circuit 4 as an upper slice level VA. And
The signal held by the lower peak hold circuit 7 is smoothed and amplified by the second non-inverting amplifier circuit 8, and then input to the second comparison signal input terminal 4C provided in the comparator circuit 4 as the lower slice level VB. You.

FIGS. 2B and 2D show the signals output to the output terminal 4D of the comparison circuit 4, and show the period of the S curve larger than the upper slice level VA and the lower slice level VB. An H level signal is output during a small S curve period. FIG. 2C shows the timing detected by the zero-cross detection circuit 9, and the TL point is the zero-cross point.

When a signal output from the output terminal 4D of the comparison circuit 4 and a signal output from the zero-cross detection circuit 9 are input to the control circuit 10, a signal is recorded on a magneto-optical disk based on these signals. Is generated. The operation of generating such a recording reference signal includes:
After detecting the preceding S-curve, that is, the upper signal,
When a zero-cross point is detected, a predetermined pulse signal is generated from the zero-cross point.
When the pulse signal shown in FIG. 2B is input to the control circuit 10, the control circuit 10 can recognize that the reference signal recorded on the magneto-optical disk has been detected. A recording reference signal can be generated based on the detected zero cross signal. By using the recording reference signal generated in this manner, a signal recording operation on a magneto-optical disk can be performed.

As described above, the detection operation of the reference signal when the land is used is performed, but the operation when the upper level or the lower level of the S curve fluctuates due to the influence of the surface deflection of the magneto-optical disk will be described. I do. When the upper level of the S curve fluctuates, the upper peak hold circuit 5
The level held by the upper peak hold circuit 5 also changes, but when the level held by the upper peak hold circuit 5 changes, the output of the first non-inverting amplifier circuit 6 that smoothes and amplifies the signal held by the upper peak hold circuit 5 The signal, ie, the upper slice level VA will also fluctuate.

When the level of the signal held by the upper peak hold circuit 5 increases, the upper slice level VA also increases. When the level of the signal held by the upper peak hold circuit 5 decreases, the upper slice level VA also increases. Since the signal becomes smaller, the detection signal shown in FIG. 2B is output to the output terminal 4D of the comparison circuit 4.

Similarly, when the lower level of the S curve fluctuates, the level held by the lower peak hold circuit 7 also fluctuates. When the signal fluctuates, the output signal of the second non-inverting amplifier 8, which smoothes and amplifies the signal held by the lower peak hold circuit 7, that is, the lower slice level VB also fluctuates.

When the level of the signal held by the lower peak hold circuit 7 increases, the lower slice level VB also increases. When the level of the signal held by the lower peak hold circuit 7 decreases, the lower slice level VB decreases. Since the slice level VB is also reduced, the detection signal shown in FIG. 2D is output to the output terminal 4D of the comparison circuit 4.

As described above, the operation of detecting the reference signal when using the land is performed. Next, the operation when using the groove will be described. As shown in FIG. 2E, when the groove is used, the S-curve signal reproduced earlier is
The peak level of the signal located below the center voltage VR and located below the center voltage VR is held by the lower peak hold circuit 7. The peak level of the upper signal constituting the S-curve is determined by the upper peak hold circuit 5.
Will be held.

The signal held by the upper peak hold circuit 5 is smoothed and amplified by the first non-inverting amplifier circuit 6, and then input to the first comparison signal input terminal 4B provided in the comparison circuit 4 as the upper slice level VA. And
The signal held by the lower peak hold circuit 7 is smoothed and amplified by the second non-inverting amplifier circuit 8, and then input to the second comparison signal input terminal 4C provided in the comparator circuit 4 as the lower slice level VB. You.

FIGS. 2 (F) and 2 (H) show signals output to the output terminal 4D of the comparison circuit 4, which are S-curve periods higher than the upper slice level VA and lower than the lower slice level VB. An H level signal is output during a small S curve period. FIG. 2G shows the timing detected by the zero-cross detection circuit 9, and the TG point is the zero-cross point.

When a signal output from the output terminal 4D of the comparison circuit 4 and a signal output from the zero-cross detection circuit 9 are input to the control circuit 10, a signal is recorded on a magneto-optical disk based on these signals. Is generated. The operation of generating such a recording reference signal includes:
After detecting the preceding S-curve, that is, the lower signal,
When a zero-cross point is detected, a predetermined pulse signal is generated from the zero-cross point.
When the pulse signal shown in FIG. 2H is input to the control circuit 10, the control circuit 10 can recognize that the reference signal recorded on the magneto-optical disk has been detected. A recording reference signal can be generated based on the detected zero cross signal. By using the recording reference signal generated in this manner, a signal recording operation on a magneto-optical disk can be performed.

As described above, the operation of detecting the reference signal at the time of using the groove is performed. The operation when the upper level and the lower level of the S curve fluctuate due to the influence of the surface deflection of the magneto-optical disk will be described. I do. When the level on the upper side of the S curve changes, the level held by the upper peak hold circuit 5 also changes, but when the level held by the upper peak hold circuit 5 changes, the level is held by the upper peak hold circuit 5. The output signal of the first non-inverting amplifier 6, which smoothes the amplified signal, that is, the upper slice level VA also fluctuates.

When the level of the signal held by the upper peak hold circuit 5 increases, the upper slice level VA also increases. When the level of the signal held by the upper peak hold circuit 5 decreases, the upper slice level VA also decreases. Since the value becomes smaller, the detection signal shown in FIG. 2F is output to the output terminal 4D of the comparison circuit 4.

Similarly, when the level on the lower side of the S curve fluctuates, the level held by the lower peak hold circuit 7 also fluctuates. When the signal fluctuates, the output signal of the second non-inverting amplifier 8, which smoothes and amplifies the signal held by the lower peak hold circuit 7, that is, the lower slice level VB also fluctuates.

When the level of the signal held by the lower peak hold circuit 7 increases, the lower slice level VB also increases. When the level of the signal held by the lower peak hold circuit 7 decreases, the lower slice level VB decreases. Since the slice level VB is also reduced, the detection signal shown in FIG. 2H is output to the output terminal 4D of the comparison circuit 4.

As described above, the operation is performed when the signal level of the S curve fluctuates. Next, the operation when the signal waveform of the S curve becomes asymmetric will be described.
That is, if the signal waveform of the S-curve becomes asymmetric, the zero-cross point shifts, so that an accurate recording reference signal cannot be generated.

When the above-described operation is being performed, the signal held by the upper peak hold circuit 5 is inverted and amplified by the first inverting amplifier circuit 12, and then input to the first input terminal 11A of the switching circuit 11. In this state, the signal held by the lower peak hold circuit 7 is inverted and amplified by the second inverting amplifier circuit 13 and is then input to the second input terminal 11B of the switching circuit 11.

When the land is used, the control circuit 10
The H level signal is output to the switching signal output terminal 10A provided in the switching circuit 11, and the H level signal is input to the control terminal 11C of the switching circuit 11. Therefore, in such a case, the first input terminal 11 of the switching circuit 11
The signal input to A, that is, the output signal of the first inverting amplifier circuit 12 is applied to the control terminal 2C of the variable gain amplifier circuit 2.

As described above, when the land is used, since the output signal of the first inverting amplifier circuit 12 is applied to the control terminal 2C of the variable gain amplifier circuit 2, the gain of the variable gain amplifier circuit 2 becomes higher than the upper peak. It is controlled by a signal held by the hold circuit 5. The reason why the gain control operation of the variable gain amplifier circuit 2 is performed based on the signal held by the upper peak hold circuit 5 is that the signal is used for performing the operation of generating the recording reference signal, that is, the signal that is used earlier. This is because the signal of the S curve exists on the upper side.

In such a state, when the level of the signal held by the upper peak hold circuit 5 increases, the level of the signal inverted by the first inverting amplifier circuit 12 decreases, and the control terminal of the variable gain amplifier circuit 2 2
The level of the control signal applied to C decreases. As a result, the gain of the variable gain amplifier circuit 2 is reduced, and the level of the signal on the upper side of the S curve is reduced. Conversely, when the level of the signal held by the upper peak hold circuit 5 decreases, the level of the signal inverted by the first inverting amplifier circuit 12 increases, and the control signal applied to the control terminal 2C of the variable gain amplifier circuit 2 Level increases. As a result, the gain of the variable gain amplifier circuit 2 increases, and the level of the signal on the upper side of the S curve increases.

When the level of the upper signal on the S curve changes when the land is used, the gain of the variable gain amplifier circuit 2 changes in a direction to suppress the level change, so that the level change of the upper signal on the S curve is suppressed. I can do it. Therefore, the deviation of the zero cross point of the S curve signal can be suppressed, and the operation of generating the recording reference signal when using the land can be performed accurately.

The operation when the land is used is performed as described above. Next, the operation when the groove is used will be described. When the groove is used, an L-level signal is output to the switching signal output terminal 10A provided in the control circuit 10, and the L-level signal is input to the control terminal 11C of the switching circuit 11. Therefore, in such a case, the signal input to the second input terminal 11B of the switching circuit 11, that is, the output signal of the second inverting amplifier circuit 13 is applied to the control terminal 2C of the variable gain amplifier circuit 2. is there.

As described above, when the groove is used, the output signal of the second inverting amplifier 13 is applied to the control terminal 2C of the variable gain amplifier 2, so that the gain of the variable gain amplifier 2 becomes lower. It is controlled by a signal held by the peak hold circuit 7. The reason why the gain control operation of the variable gain amplifier circuit 2 is performed based on the signal held by the lower peak hold circuit 5 is that the signal used for generating the recording reference signal, This is because the signal of the S curve below exists on the lower side.

In such a state, when the level of the signal held by the lower peak hold circuit 7 increases, the level of the signal inverted by the second inverting amplifier 13 decreases, and the control of the variable gain amplifier 2 is performed. Terminal 2
The level of the control signal applied to C decreases. As a result, the gain of the variable gain amplifier circuit 2 is reduced, and the level of the lower signal of the S curve is reduced. Conversely, when the level of the signal held by the lower peak hold circuit 7 decreases, the level of the signal inverted by the second inverting amplifier circuit 13 increases, and the control applied to the control terminal 2C of the variable gain amplifier circuit 2 increases. The signal level increases. As a result, the gain of the variable gain amplifier circuit 2 is increased, and the level of the signal below the S curve is increased.

When the level of the lower signal of the S curve changes when the groove is used, the gain of the variable gain amplifier circuit 2 changes in a direction to suppress the level change. Can be suppressed. Therefore, the deviation of the zero cross point of the S curve signal can be suppressed, and the operation of generating the recording reference signal when the groove is used can be performed accurately.

In this embodiment, the case where the preceding S-curve signal when using the land is on the upper side and the preceding S-curve signal when using the groove is on the lower side has been described. By changing it, it is possible to change the preceding S-curve signal from the upper side to the lower side and vice versa.

[0045]

According to the present invention, the upper peak level and the lower peak level of the S curve signal obtained by reproducing the reference signal recorded on the magneto-optical disk by the optical pickup are held and held. Since the upper and lower slice levels for detecting the reference signal from the signal are set, even if the level of the S-curve changes due to the runout of the magneto-optical disk or the like, the slice level changes corresponding to the change. As a result, the operation of detecting the reference signal can be reliably performed.

Further, according to the present invention, there is provided a variable gain amplifying circuit capable of amplifying an S-curve signal and varying a gain, and controlling a gain control operation of the variable gain amplifying circuit based on a signal held by a peak hold circuit. When the S curve changes asymmetrically, the shift of the zero-cross point can be suppressed by operating the variable gain amplifier circuit in a direction to suppress the change, thereby generating an accurate recording reference signal. Can be done.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing one embodiment of a reference signal detection circuit of the present invention.

FIG. 2 is a signal waveform diagram for explaining the operation of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 pickup signal output circuit 2 variable gain amplifier circuit 4 comparison circuit 5 upper peak hold circuit 6 first non-inverting amplifier circuit 7 lower side peak hold circuit 8 second non-inverting amplifier circuit 9 zero cross detection circuit 10 control circuit 12 first inverting amplifier Circuit 13 Second inverting amplifier circuit

Claims (4)

[Claims] 1. A magneto-optical disk recording / reproducing apparatus using a magneto-optical disk having lands and grooves and recording a reference signal, wherein the reference signal recorded on the magneto-optical disk is optically picked up. Holding the upper peak level and the lower peak level of the S-curve signal obtained by the reproduction, and setting the upper and lower slice levels for detecting the reference signal from the held signal. Reference signal detection circuit of a magneto-optical disk recording / reproducing apparatus. 2. A variable gain amplifier circuit for amplifying an S-curve signal and having a variable gain, wherein a peak level of a signal output from the variable gain amplifier circuit is held. 2. The reference signal detection circuit according to 1. 3. The reference signal detection circuit according to claim 2, wherein the gain control operation of the variable gain amplifier circuit is performed based on the held signal. 4. The reference signal detection circuit according to claim 3, wherein a gain control operation is performed with a signal that holds the peak level of the preceding S curve signal.