JPH11232663A - Recording/reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect defects and flaws by comparing a peak value of a focus error signal in a state while a focus servo loop is open with a preliminar ily set standard value and adjusting a threshold value on the basis of the compar ison result. SOLUTION: When a p-p value of an actual FE signal is smaller than a design standard value because of characteristic irregularities of an actual optical disk and a pickup 3, a threshold value Vfe2 of a flaw detection level is decreased. When the p-p value is larger, the threshold value Vfe2 is raised. At the reproduction time, the presence/absence of flaws, etc., of the optical disk is judged by the threshold value level Vfe2 set newly at an FE comparison part 7. When the flaws, etc., are not detected, an output of the FE comparison part 7 becomes an L level, an FE switch part 5 is connected to (b) and the FE signal generated at a preamplifier 4 is input directly to a servo amplifier 8. When flaws are detected, the FE switch part 5 is connected to (a), and an FE signal level immediately before the flaws are detected which is held by an FE hold circuit 6 is input to the servo amplifier 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus for reproducing information from an information recording medium, such as an optical disk, on which information is recorded. The present invention relates to a recording / reproducing apparatus for performing focus servo control and tracking servo control.

[0002]

2. Description of the Related Art In an information recording medium such as an optical disk, it is inevitable that scratches and dirt adhere to the surface of the information recording medium to some extent. As a countermeasure against dirt, a tracking error (TE) signal or RF signal is compared with a fixed slice level set in advance at the time of design, and based on the result, the presence or absence of scratches and dirt is detected. The countermeasures such as using the TE signal that has been performed have been taken. This conventional measure will be described with reference to FIGS. In FIG. 11, reference numeral 1 denotes, for example, a compact disk (hereinafter, referred to as a CD) set in the recording / reproducing apparatus.
An optical disk as an information recording medium including: a signal is read from the optical disk 1 by a pickup 3;
This reproduced signal is converted into an RF signal and a tracking error (hereinafter, referred to as a tracking error).
The signals are input to a preamplifier 4 that generates a signal (referred to as TE) and a focus error (hereinafter referred to as FE) signal.

[0003] The RF signal generated by the preamplifier 4 is input to a decoder 14, where it is EFM demodulated and a spindle motor error signal is generated. It is input to the driver circuit 15 and drives the spindle motor 2. The signal decoded from the EFM signal to the NRZ data is subjected to an error correction process in an error correction unit 35, and a digital signal is converted into an analog signal in a D / A converter unit 36, and an audio signal is output. FE made with preamplifier 4
The signals are FE switch unit 5, FE hold circuit 6, and FE
It is input to the comparison unit 7. This FE signal is supplied to the FE comparison unit 7
If no flaw or the like is detected by the comparison with the threshold level Vfe1 set in the above, the output of the FE comparison unit 7 becomes, for example, "L" level, and the FE switch unit 5 is connected to b.
The FE signal generated by the preamplifier 4 is directly input to the servo amplifier 8. Then, the servo amplifier 8 controls this FE
The signal is amplified and equalized, and the output signal is input to a focus driver circuit 9 to drive a focus coil (not shown) in the pickup 3.

When the FE signal is compared with the threshold level Vfe1 by the FE comparator 7 and a flaw is detected due to the FE signal exceeding the level Vfe1, the output of the FE comparator 7 is, for example, "". H level, FE switch 5
Is connected to a, and the FE signal level immediately before a flaw or the like held by the FE hold circuit 6 is detected is input to the servo amplifier 8. If the FE signal is damaged due to scratches,
When the FE signal is input to the servo amplifier 8 as it is, the focus coil cannot be controlled accurately. However, the focus coil can be accurately controlled by switching to the held level immediately before a flaw or the like is detected. Control. In the FE hold circuit 6, the signal immediately before the currently detected FE signal is held while being updated.

On the other hand, the TE signal generated by the preamplifier 4 is supplied to a TE switch section 10, a TE hold circuit 11, and a TE comparison section.
Entered in 12. This TE signal is compared with a threshold level Vte1 set in advance by the TE comparator 12, and if no flaw or the like is detected, the output of the TE comparator 12 becomes, for example, "L" level, and the TE switch 10 sets b And the TE signal generated by the preamplifier 4 is directly input to the servo amplifier 8. Then, the servo amplifier 8 amplifies the TE signal, applies an equalizer thereto, inputs the output signal to a tracking driver circuit 13, and drives a tracking coil (not shown) in the pickup 3.

When the TE comparator 12 compares the TE signal with the threshold level Vte1 and finds that the TE signal exceeds Vte1 and a flaw or the like is detected, the output of the TE comparator 12 is set to, for example, "H". The TE switch section 10 is connected to a, and the TE signal level immediately before the flaw or the like held by the TE hold circuit 11 is detected is input to the servo amplifier 8. As described above, when a flaw or the like is detected, the tracking coil can be accurately controlled by setting the TE signal input to the servo amplifier 8 to the immediately preceding normal signal level. This is the same as the control of the focus coil described above.

[0007]

However, in the conventional method, since the threshold levels Vfe1 and Vte1 for flaw detection of each of the comparators 7 and 12 are fixed to a constant value, the reflectivity of the disk is changed. If the peak values of the FE signal and the TE signal are different, the peak value (peak-to-peak value) of the FE signal when the servo is open and the peak value of the TE signal (peak-to-peak) Value) The detection level of the flaw differs from the TEp-p level, and F
There is a drawback that the timing for holding the E signal or the TE signal is shifted or the detection is failed, and the operation at the time of flaw detection does not work well.

This point will be described with reference to FIGS. FIG. 12 shows a threshold level in the FE comparison unit 7.
This indicates a design standard value of Vfe1 at the time of shipment from the factory. For example, at the time of shipment from the factory, the standard value FEref of the Peak to Peak value (hereinafter referred to as the pp value) of the FE signal when the focus servo loop is open is 2. It is assumed that an amplitude of 0 V is set, and a threshold value Vfe1 for confirming the presence or absence of a flaw or the like is set to an amplitude of 1.0 V. In the figure, pp is Peak to Pe.
Indicates an ak value. That is, when the amplitude of the FE signal during reproduction exceeds the amplitude of 1.0 V and becomes large, it is recognized that a flaw or the like exists.

However, in an actual optical disc, the reflectivity differs individually due to aging or the like, or the reflectivity of the optical disc itself varies, and the standard value (pp value) of the FE signal is 2.0 V. However, there is a case where it becomes smaller than this. Here, even when the actual measurement is performed, the pp value of the FE signal with the focus servo loop open is 2.0 V
If there is any, as shown in FIG. 13A, the amplitude of the FE signal exceeds the range of the amplitude of the threshold value Vfe1 of 1.0 V corresponding to the time when the optical disk is damaged, and the FE comparison unit generates a pulse to generate the damage. Can be recognized, but as described above, p of the measured value of the FE signal when the focus servo loop is in the open state.
When the -p value is lower than 2.0 V, as shown in FIG. 13B, the amplitude of the FE signal when a flaw or the like is present also becomes small and does not reach the threshold value Vfe1, and the presence of a flaw or the like is caused. Could not be detected. For this reason, there has been a problem that the focus control is not sufficiently performed and the reproduction capability is deteriorated. This is a problem that applies not only to focus control but also to tracking control.

[0010] The present invention focuses on the above problems,
The present invention has been made to solve this problem effectively, and an object of the present invention is to provide a recording / reproducing apparatus capable of reliably detecting a scratch or a defect on an information recording medium and responding to the detected defect or defect.

[0011]

According to a first aspect of the present invention, there is provided an apparatus for focusing on an FE (focus error) signal and a TE (tracking error) signal generated based on a reproduction signal from a pickup for scanning an information recording medium. A servo amplifier that forms a servo signal and a tracking servo signal, a focus driver that performs focus control of the pickup by the focusing servo signal, and a tracking driver that performs tracking control of the pickup by the tracking servo signal. An FE hold circuit for holding the FE signal, an FE switch unit for switching between the FE signal and an output value of the FE hold circuit, and an FE switch based on a level comparison between the FE signal and the FE threshold. FE switch part In a recording / reproducing apparatus having at least an FE comparing section for performing switching, an FE peak detecting circuit for detecting a peak value of the FE signal, and a threshold value of the FE comparing section based on an output of the FE peak detecting circuit. And an FE threshold control circuit for controlling the information recording medium.

Thus, when the information recording medium is set in the recording / reproducing apparatus, the FE signal is shaken in the initial operation, and the peak value (pp value) at this time is measured and detected by the FE peak detection circuit. The FE threshold value control circuit determines a new threshold value with reference to the actually measured peak value and the standard value. Then, the determined new threshold value is set in the FE comparison unit. As described above, since the threshold value of the FE comparison unit can be controlled so as to change according to the characteristics of the actual information recording medium, it is possible to reliably detect a flaw, a defect, and the like, and to perform the focus control reliably. Can be.

According to a second aspect of the present invention, there is provided a focus servo signal and a tracking signal based on a FE (focus error) signal and a TE (tracking error) signal generated based on a reproduction signal from a pickup for scanning an information recording medium. A servo amplifier for forming a servo signal for each of the above, a focus driver for performing a focus control of the pickup with the focus servo signal, a tracking driver for performing a tracking control of the pickup with the tracking servo signal, and a TE signal. A TE switch circuit for switching the TE signal and an output value of the TE hold circuit, and a TE switch unit for switching the TE signal and a TE threshold value according to a level comparison result of the TE signal and a TE threshold value. Switch In a recording / reproducing apparatus having at least a TE comparison unit, a TE peak detection circuit for detecting a peak value of the TE signal, and a threshold value of the TE comparison unit is controlled based on an output of the TE peak detection circuit. And a TE threshold value control circuit for recording and reproducing information on and from the information recording medium.

Thus, when the information recording medium is set in the recording / reproducing apparatus, the FE signal is shaken in the initial operation, and the peak value (pp value) at this time is actually measured and detected by the TE peak detection circuit. The TE threshold value control circuit determines a new threshold value with reference to the actually measured peak value and the standard value. Then, the determined new threshold value is set in the TE comparison unit. As described above, since the threshold value of the TE comparison unit can be controlled so as to change depending on the characteristics of the actual information recording medium, it is possible to reliably detect a flaw, a defect, and the like, and to perform tracking control reliably. Can be.

According to a third aspect of the present invention, an RF signal generated based on a reproduction signal from the pickup and an RF signal
R for outputting a comparison result signal obtained by comparing the level with a threshold value
An F comparison unit, an RF peak detection circuit that detects a peak value of the RF signal, an RF threshold control circuit that controls an RF threshold of the RF comparison unit based on an output of the RF peak detection circuit, An OR circuit that performs an OR operation on the output of the RF threshold control circuit and the output of the FE threshold control circuit or the output of the TE threshold control circuit;
The switching of the FE switching unit or the TE switching unit is controlled by the output of the OR circuit.

Thus, the RF signal is also monitored, and as a result, when it is determined that a flaw or a defect exists, the FE switch section and the TE switch section are switched.
It is possible to further improve the detection accuracy of scratches and defects.
In the invention defined in claims 1 to 3, when a flaw or a defect is found on the information recording medium, the signal level immediately before the discovery is held in the hold circuit and transmitted to the subsequent stage by switching by the switch unit. However, in place of the above-described hold circuit as defined in claims 4 to 6, an FE or TE gain up circuit for increasing the servo gain (including the phase) of the FE signal or TE signal for a predetermined time is provided. The output may be switched to the output of this gain-up circuit when a defect or defect is found. Also in this case, it is possible to expect exactly the same operation and effect as described in the first to third aspects.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the recording / reproducing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a first embodiment of the recording / reproducing apparatus of the present invention.
The same parts as those shown in FIG. 11 will be described with the same reference numerals. The device shown in FIG. 1 is different from the device shown in FIG. 11 in that an FE peak detection circuit 20 is added to the FE signal system.
And the FE threshold control circuit 21 are provided.
The point is that an E peak detection circuit 22 and a TE threshold control circuit 23 are provided. That is, reference numeral 3 denotes a pickup for reading or writing information from or on the optical disc 1 as an information recording medium, which can be moved in the radial direction of the optical disc 1 and has a semiconductor laser element (not shown) and a focus inside. An objective lens (not shown) is included.

Reference numeral 4 denotes a preamplifier, which receives a signal from the pickup 3 and performs matrix processing to generate an FE signal, a TE signal, and an RF signal. Reference numeral 6 denotes an FE hold circuit that holds the current FE signal while updating the previous FE signal, and reference numeral 7 denotes an FE comparison unit, which determines the presence or absence of a flaw or defect based on the FE signal. The FE comparison unit 7 has a pp signal which is predicted to take an FE signal at the time of factory shipment.
A standard value (range) and a threshold value for determining the presence or absence of a flaw or the like are set in advance. Reference numeral 11 denotes a TE hold circuit that holds the current immediately preceding TE signal while updating it.
Reference numeral 2 denotes a TE comparison unit that determines whether there is a flaw, defect, or the like based on the TE signal. The TE comparison unit 12 is preset with a pp standard value (range), which is expected to take a TE signal at the time of shipment from the factory, and a threshold value for determining the presence or absence of a flaw or the like. Note that the ranges of these thresholds are variable as described later.

Reference numeral 8 denotes a servo amplifier, which receives the FE signal and the TE signal, amplifies these signals, applies an equalizer thereto, and outputs the amplified signals to the subsequent stage. Reference numeral 9 denotes a focus driver that controls the focus of the pickup 3 by receiving an output from the servo amplifier 8. Reference numeral 13 denotes a tracking driver that controls the pickup 3 by receiving an output from the servo amplifier 8. A decoder 14 receives the RF signal and performs EFM demodulation to form NRZ data and a spindle motor error signal. A spindle motor driver 15 controls the rotation of the spindle motor 2 based on a spindle motor error signal. Reference numeral 35 denotes an error correction unit that performs error correction on NRZ data. Code 36
Denotes a D / A converter, which converts error-corrected data from digital to analog signals to form audio signals.

Reference numeral 20 denotes an FE peak detection circuit which detects a peak-to-peak value which can be taken by an FE signal in an open state of a focus servo loop with respect to an optical disk to be reproduced. Reference numeral 21 indicates a new threshold based on the actually measured pp value obtained above, a standard value (pp value) set at the time of factory shipment, and a preset threshold value. Is transmitted to the FE threshold control circuit 7. Reference numeral 22 denotes a TE peak detection circuit, which detects a pp value that can be taken by a TE signal in an open state of a tracking servo loop for an optical disc to be reproduced. Reference numeral 23 indicates a value based on the actually measured pp value obtained above, a standard value (pp value) set at the time of factory shipment, and a preset threshold value.
A new threshold is obtained, and the new threshold is transmitted to the TE threshold control circuit 12.

Next, the operation of the recording / reproducing apparatus configured as described above will be described with reference to FIGS.
2 is a diagram showing a timing chart of each signal at the time of an initial operation, FIG. 3 is a diagram showing a relationship between a design standard value and a measured value of a focus error (FE) signal, and FIG. 4 is a focus error when detecting a flaw or the like. FIG. 5 is a diagram showing a waveform of a signal, FIG. 5 is a diagram showing a relationship between a design standard value and an actually measured value regarding a tracking error (TE) signal, and FIG. 6 is a diagram showing a waveform of a tracking error signal when a flaw or the like is detected.

First, a signal read from the optical disk 1 by the pickup 3 is input to the preamplifier 4. The RF signal generated by the preamplifier 4 is input to a decoder 14, and when the optical disk is a CD, the signal is EFM demodulated and a spindle motor error signal is generated. The spindle motor error signal is converted to a spindle motor driver 15 Is entered into
The spindle motor 2 is driven. Further, the NRZ data formed by the EFM demodulation is error-corrected by an error correction unit 35, and then converted into an analog signal by a D / A converter unit 36 to output an audio signal.

First, when the optical disk 1 is set in the recording / reproducing apparatus, an initial operation is performed to obtain a new threshold value. That is, when the optical disc 1 is set in the apparatus, as shown in FIG. 2A, the focus drive signal is scanned once to move the focus coil (objective lens) up and down, and the S-shaped signal generated at the focal point is obtained. Output. The FE signal generated by the preamplifier 4 is input to the FE switch section 5, FE hold circuit 6, FE peak detection circuit 20, and FE comparison section 7. Here, by raising and lowering the focus coil, the S-shaped level generated at the focal point is taken into the FE peak detection circuit 20, and the measured value FEp-p of the S-shaped pp value (FIG. 2B) ), And inputs this value to the FE threshold control circuit 21. Then, from this FEP-P value, the standard value F Er set at the time of design is obtained.
ef, and calculates a new threshold level Vfe2 for flaw detection, and inputs this new threshold to the FE comparison unit 7.

For example, as shown in FIG.
Assuming that the standard value (range) FEref of the E signal is 2.0 Vp-p and the threshold level Vfe1 for flaw detection is set in advance to a threshold value of 1 Vp-p from the center of the FE signal, If the range FEp-p of the FE value of the FE signal of the actually reproduced optical disk is 1.5 Vp-p as shown in FIG. 3B, a new threshold (range) Vfe2 is expressed by the following equation. . Vfe2 = 1.5Vp-p / 2.0Vp-p X 1.0Vp-p = 0.75Vp-p In other words, due to variations in the characteristics of the actual optical disk and pickup 3, the peak-to-peak value of the FE signal measured from the design standard value
If the value level is small, the threshold value Vfe2 of the scratch detection level
If the level of the pp value of the actually measured FE signal is higher than the design standard value, the threshold level Vfe2 for flaw detection is raised.

When reproducing the optical disk, the FE
The comparator 7 determines whether or not there is a scratch on the optical disk based on the newly set threshold level Vfe2. If no scratch is detected, the output of the FE comparator 7 becomes, for example, "L" level and the FE switch 5 Is connected to b, and the FE signal generated by the preamplifier 4 is directly input to the servo amplifier 8. This signal is amplified by a servo amplifier 8 and applied with an equalizer. The signal is input to a focus driver 9 and is focused by a focus coil (not shown) in the pickup 3.
To perform focus control.

If a flaw is detected based on the threshold level Vfe2 newly set by the FE comparing section 7, FIG.
As shown in (B), the output of the FE comparison unit 7 becomes, for example, “H” level, and the FE switch unit 5 is connected to a.
The E signal level is input to the servo amplifier 8. Therefore,
Even if the amplitude of the FE signal is increased due to the presence of a flaw or the like, this signal level is not input to the servo amplifier 8 side, but the immediately preceding normal FE signal level is input to the servo amplifier 8. Defocus can be prevented, and appropriate focus control can be performed.

In this case, if the threshold value Vfe1 is fixed to the design standard value of 1.0 Vp-p as in the conventional device shown in FIG. Even if the amplitude increases in the form of a pulse, a flaw or the like cannot be detected because the amplitude is within the range of the threshold value Vfe1, and the pulse-like focus error signal is directly input to the servo amplifier 8. As a result, a large defocus occurs due to the pulse-shaped focus error signal, thereby deteriorating reproduction characteristics. On the other hand, as shown in FIG. 4B, if the threshold value Vfe2 is set to a small value of 0.75 Vp-p, for example, in accordance with the actually measured value, a pulse like the one shown in FIG. When the focus error signal appears, this signal exceeds the new threshold value Vfe2, so that a flaw or the like can be recognized.
As a result, the switching of the FE switch unit 5 causes the servo amplifier 8 to receive a substantially flat focus error signal immediately before the occurrence of a flaw or the like as shown in FIG. Therefore, it is possible to maintain high reproduction characteristics.

On the other hand, the operation of the TE signal is exactly the same as described above, but the initial operation of the TE signal is performed after the initial operation of the FE signal is completed. That is, when the initial operation of the FE signal is completed as described above, the initial operation of the TE signal is performed with the focus of the pickup 3 focused on the optical disk 1 as shown in FIG. The TE signal generated by the preamplifier 4 is transmitted to the TE switch unit 10, T
The signals are input to the E hold circuit 11 and the TE comparison unit 12. In this initial operation, the TE signal is taken into the TE peak detection circuit 22 while the tracking servo loop is kept open,
An actual measurement value TEp-p of the signal pp value is calculated (see FIG. 2C), and this value is input to the TE threshold value control circuit 23.

The TEp-p value is compared with a standard value TEref (see FIG. 5A) set at the time of design, and a new threshold level Vte2 for flaw detection (see FIG. 5B).
Is calculated, and the new threshold value is input to the TE comparison unit 12. For example, as shown in FIG. 5A, while the standard value (range) TEref of the TE signal at the time of design is 2.0 Vp-p, the threshold level Vte1 of flaw detection is set at 0.7 Vp-p from the center of the TE signal. Assuming that the threshold value of the range is set in advance, the range TE of the pp value of the TE signal of the actually reproduced optical disc is assumed.
If pp is 1.5 Vp-p as shown in FIG. 5B, the new threshold (range) Vte2 is represented by the following equation. Vte2 = 1.5Vp-p / 2.0Vp-p X 0.7Vp-p = 0.525Vp-p In other words, the level of the measured pp value of the TE signal is smaller than the design standard value due to variations in the characteristics of the actual optical disk and the pickup 3. For example, the threshold level Vte2 for flaw detection is lowered, and if the level of the actually measured TE signal is higher than the design standard value, the flaw detection level Vte2 is raised.

At the time of reproducing the optical disk, TE
The comparator 12 determines whether or not there is a scratch on the optical disk based on the newly set threshold level Vte2. If no scratch is detected, the output of the TE comparator 7 becomes, for example, "L" level, and the TE switch 10 b, and the TE signal generated by the preamplifier 4 is directly input to the servo amplifier 8. This signal is amplified by a servo amplifier 8 and applied with an equalizer. The signal is input to a tracking driver 13 to drive a tracking coil (not shown) in the pickup 3 to perform tracking control.

If a flaw is detected based on the threshold level Vte2 newly set by the TE comparing unit 12, FIG.
As shown in (B), the output of the TE comparator 12 is, for example, "H".
The TE switch section 10 is connected to a, and the TE signal level immediately before the flaw held by the TE hold circuit 11 is detected is input to the servo amplifier 8. Therefore, even if the amplitude of the TE signal increases due to the presence of a flaw or the like,
This signal level is not input to the servo amplifier 8 side, but the immediately preceding normal TE signal level is input to the servo amplifier 8, so that it is possible to prevent occurrence of tracking loss and to perform appropriate tracking control. it can.

In this case, if the threshold value Vte1 is fixed to the design standard value of 1.0 Vp-p as in the conventional device shown in FIG. Even if the amplitude increases in the form of a pulse, flaws and the like cannot be detected because the amplitude is within the range of the threshold value Vte1, and the pulse-like tracking error signal is directly input to the servo amplifier 8. As a result, a large tracking error occurs due to the pulse-like tracking error signal, thereby deteriorating the reproduction characteristics. On the other hand, as shown in FIG. 6B, if the threshold value Vte2 is set to a small value, for example, 0.525 Vp-p in accordance with the actually measured value, a pulse like the one shown in FIG. When the tracking error signal appears, the signal exceeds the new threshold value Vte2, so that a flaw or the like can be recognized. As a result, the switching of the TE switch unit 10 causes the servo amplifier 8 to input a substantially flat tracking error signal immediately before the occurrence of a flaw or the like, as shown in FIG. Therefore, it is possible to maintain high reproduction characteristics. As described above, according to the present invention, even if the reflectivity of an optical disk is lower than that assumed at the time of design, the threshold level for flaw detection is automatically changed in accordance with the reflectivity. The cas servo and tracking servo control can be performed. Therefore, the reproduction characteristics can be greatly improved.

In the above embodiment, the case where the peak detection circuits 20 and 22 and the threshold control circuits 21 and 23 are provided for both the FE signal system and the TE signal system has been described as an example.
However, the present invention is not limited to this. For example, depending on the optical characteristics of the pickup 3, the FE peak detection circuit 20 and the FE threshold control circuit 21 may be provided, and the other may be omitted. The circuit 22 and the TE threshold control circuit 23 may be provided, and the other may be omitted.
Further, in the present embodiment, the determination of the presence or absence of a flaw, defect, or the like is performed individually by the corresponding FE signal and TE signal. In addition, the signal obtained by monitoring the RF signal also includes: It may be used to determine the presence or absence of a flaw, defect, or the like. Further, in the present embodiment, control is performed when a flaw or the like is detected with respect to focus or tracking. However, determination of a flaw or a defect is made by an RF signal or an FE signal,
The control may be performed on a signal obtained by monitoring the RF signal or the TE signal, and the RF signal may be controlled. This gives R
Overflow of the F signal on the circuit can be prevented.

FIG. 7 shows a second example of such a recording / reproducing apparatus.
It is a block diagram which shows an Example. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. Here, a member newly added to the configuration shown in FIG. 1 will be described. Reference numeral 24 denotes an RF peak detection circuit,
Detects the peak value (pp value) of the signal. Symbol 25 is RF
This is a threshold control circuit, and reference numeral 26 is an RF comparison unit. The RF comparing section 26 determines the presence or absence of a flaw or defect based on the input RF signal and the threshold. R above
The F threshold value control circuit 26 calculates a new threshold value based on the output from the RF peak detection circuit and a preset threshold value in the RF comparison unit 26, and sends the new threshold value to the RF comparison unit 26. introduce.

Reference numerals 27 and 28 denote OR circuits, respectively. The OR circuit 27 calculates the logical sum of the output of the RF comparison unit 26 and the output of the TE comparison unit 12, and the OR circuit 28 controls the RF circuit. The logical sum of the output of the comparing section 26 and the output of the FE comparing section 7 is calculated. In this embodiment, the pp value of the RF signal is obtained while the initial operation of the TE signal described in the first embodiment is being performed. That is,
The RF signal during the rotation of the optical disk fluctuates according to changes in the reflectivity of the optical disk, distortion, surface shake, eccentricity, etc. If the optical disk is rotated several times in a focused state, the pp value of the RF signal of the optical disk Can be obtained. FE signal and T
Since the initial operation of the E signal is the same as that of the first embodiment, the description is omitted here.

First, in the initial state of the reproduction of the optical disk, the RF signal generated by the preamplifier 4 is input to the RF peak detecting circuit 24 and the RF comparing section 26. The RF signal is taken into the RF peak detection circuit 24, and the measured pp value of the RF signal RFp-
An actually measured value of p, for example, 1.5 V (see FIG. 8) is calculated, and this value is input to the RF threshold control circuit 25. Then, from this RFp-p value, a predetermined standard value RFre set at the time of design is obtained.
f, for example, 2.0 V (see FIG. 9A), and calculate a new threshold level Vrf2 for flaw detection, for example, 0.75 V (see FIG. 9B). It is input to the RF comparison unit 26.

Here, the threshold value Vrf1 of the detection level of the flaw of the RF signal at the time of shipment from the factory is 1.0 V (see FIG. 9A). Therefore, the numerical relationship here is the same as in the case of the focus error signal described with reference to FIG.
During the reproduction of the optical disk, if no flaw is detected by the threshold level Vfe2 set by the FE comparison unit 7 of the FE signal, the output of the comparison unit becomes, for example, "L" level. If no flaw is detected due to the threshold level Vrf2 newly set in the above, the output of the RF comparison unit 26 becomes, for example, "L" level, and the OR of these two detection signals is taken by the OR circuit 28, and as a result Is input to the FE switch unit 5, and the FE switch unit 5 is connected to b. Therefore, the FE signal generated by the preamplifier 4 is directly input to the servo amplifier 8.

If a flaw is detected based on the threshold level Vfe2 set by the FE comparison unit 7 for the FE signal or the threshold level Vrf2 newly set by the RF comparison unit 26 for the RF signal, The output of one or both of the comparison units 7 and 26 becomes, for example, “H” level, and
OR is taken by the OR circuit 28 and input to the FE switch unit 5,
Since the FE switch section 5 is connected to a, the FE signal immediately before the flaw held by the FE hold circuit 6 is detected is input to the servo amplifier 8. Further, at the time of reproducing the optical disk, if no flaw is detected by the set threshold level Vte2 in the TE comparator 12 of the TE signal, the output of the TE comparator 12 becomes, for example, "L" level, and the RF signal RF If no flaw is detected by the threshold level Vrf2 newly set by the comparing section 26, the output of the RF comparing section 26 becomes, for example, "L" level, and the OR circuit 27 takes the OR of these two detection signals. The result is input to the TE switch unit 10, and the TE switch unit 10 is connected to b. Therefore, the TE signal generated by the preamplifier 4 is directly input to the servo amplifier 8.

When a flaw is detected based on the threshold level Vte2 set by the TE comparator 12 for the TE signal or the threshold level Vrf2 newly set by the RF comparator 26 for the RF signal, Either or both comparison units 12, 26
Becomes an "H" level, for example. The OR of these two detection signals is taken by the OR circuit 27 and input to the TE switch unit 10. The TE switch unit 10 is connected to a and held by the TE hold circuit 11. The TE signal immediately before the detected flaw is detected is input to the servo amplifier 8. As described above, the presence or absence of a flaw or defect is determined by including the monitoring signal for the RF signal.
It is possible to confirm the presence or absence of a defect or the like on the optical disc even if the type of the F signal is likely to change, such as a flaw such as a fingerprint, and it is possible to detect the presence or absence of the defect with higher accuracy.

Also in this case, the signal indicating the presence or absence of a flaw or the like obtained in the signal system may be supplied to only one of the FE signal system and the TE signal system. . In each of the embodiments described with reference to FIGS. 1 and 7, the case where the hold circuits 6 and 11 are used has been described as an example. Thus, as shown in FIG. 10, an FE gain control circuit 29 and a TE gain control circuit 30 may be provided. The gain control circuits 29 and 30 increase the servo gain (including the phase) of the FE signal or the TE signal for a predetermined time, for example.

FIG. 10 shows gain control circuits 29, 3 in place of the hold circuits 6, 11 in the configuration shown in FIG.
An example of a configuration in which 0 is replaced is shown. In this case, when the switch section 5 or 10 is switched to the gain control circuit 29 or 30, the gain of the servo actuator is increased, for example (the phase margin is also changed). In addition, the followability of the focus or tracking servo is improved, and as a result, the pulse-like amplitude value of the FE signal or TE signal when a flaw or defect is detected is suppressed. Therefore, as described in the previous embodiment, it is possible to detect and respond to scratches and defects with high accuracy, and to improve reproduction characteristics. In the above embodiment, the gain is increased (change in the phase margin) before the servo amplifier 8 is input. However, a detection signal is input to a control CPU (not shown), and the servo CPU 8 May be controlled to increase the gain (change in phase margin). Although not shown here, the RF signal processing system (RF peak detection circuit 24, RF threshold control circuit 2
5, the RF comparator 26) is changed to compare the RF signal output from the preamplifier 4 with a threshold value and output a comparison result signal; and an RF peak detecting the peak value of the RF signal. A detection circuit, an RF threshold control circuit for controlling a threshold value of the RF comparison section based on an output of the RF peak detection circuit, and an RF for updating and holding a value immediately before reproduction of the RF signal A hold circuit,
An RF switch for switching between the RF signal and the output value of the RF hold circuit; an output of the RF threshold control circuit and an output of the FE threshold control circuit 21; An OR circuit for performing an OR operation with an output and an output signal of the OR circuit may be configured to control the RF switch unit. This allows
The RF signal is also monitored, and as a result, when it is determined that a flaw or defect exists, the RF switch unit is switched, so that the detection accuracy of the flaw or defect can be further improved.

[0042]

As described above, according to the recording / reproducing apparatus of the present invention, the following excellent functions and effects can be exhibited. According to the first aspect of the present invention, the peak value FEp-p of the focus error signal when the focus servo loop is open is compared with a preset standard value FEref, Since the threshold value Vfe2 for detecting a defect or a flaw in an information recording medium such as an optical disk is adjusted based on the comparison result, even if the level of various signals of the information recording medium changes due to the influence of the reflectance or the like. Scratches and defects can be reliably detected. Therefore, it is possible to improve the reproduction characteristics by performing the focus control with high accuracy. According to the second aspect of the present invention, the peak value TEp-p of the tracking error signal when the focus servo loop is open is compared with a preset standard value TEref. Threshold Vte2 for detecting defects and scratches on information recording media such as optical disks based on the results
Is adjusted, so that even if the level of various signals of the information recording medium changes due to the influence of the reflectance or the like, a flaw or a defect can be reliably detected. Therefore, it is possible to improve the reproduction characteristics by performing highly accurate tracking control.

According to the third aspect of the present invention, it is difficult to detect the defect or flaw of the information recording medium from the focus error signal or the tracking error signal.
Since the detection result of the RF signal is also added to a defect or a flaw easily detected from the F signal, the presence or absence of the defect can be detected more accurately.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a recording / reproducing apparatus of the present invention.

FIG. 2 is a diagram showing a timing chart of each signal in an initial operation.

FIG. 3 is a diagram illustrating a relationship between a design standard value and a measured value regarding a focus error (FE) signal.

FIG. 4 is a diagram showing a waveform of a focus error signal when a flaw or the like is detected.

FIG. 5 is a diagram illustrating a relationship between a design standard value and a measured value regarding a tracking error (TE) signal.

FIG. 6 is a diagram illustrating a waveform of a tracking error signal when a flaw or the like is detected.

FIG. 7 is a configuration diagram showing a second embodiment of the recording / reproducing apparatus of the present invention.

FIG. 8 is a diagram illustrating a peak value of an RF signal according to the second embodiment.

FIG. 9 is a diagram illustrating a state when a threshold value is adjusted in the second embodiment.

FIG. 10 is a diagram illustrating a peak value of an RF signal according to a third embodiment.

FIG. 11 is a configuration diagram showing a conventional recording / reproducing apparatus.

FIG. 12 is a diagram showing a design standard value at the time of factory shipment of a threshold level in the FE comparison unit 7;

FIG. 13 is an explanatory diagram for explaining a problem of the conventional device.

[Explanation of symbols]

1 ... optical disk (information recording medium), 3 ... pickup,
4: Preamplifier, 5: FE switch section, 6: FE hold section, 7: FE comparison section, 8: Servo amplifier, 9: Focus driver, 10: TE switch section, 11: TE hold circuit, 13: Tracking driver , 14 decoder, 20 FE peak detection circuit, 21 FE threshold control circuit, 22 TE peak detection circuit, 23 TE threshold control circuit, 24 RF peak detection circuit, 25 R
F threshold value control circuit, 26 ... RF comparison section, 27, 28 ...
OR circuit, 29 ... FE gain control circuit, 30 ...
TE gain control circuit.

Claims (3)

[Claims] 1. A servo amplifier for forming a focus servo signal and a tracking servo signal based on a FE (focus error) signal and a TE (tracking error) signal generated based on a reproduction signal from a pickup for scanning an information recording medium. A focusing driver for performing focus control of the pickup by the focusing servo signal; a tracking driver for performing tracking control of the pickup by the tracking servo signal; an FE hold circuit for holding the FE signal; At least an FE switch unit that switches between an FE signal and an output value of the FE hold circuit, and an FE comparison unit that switches the FE switch unit according to a comparison result of level comparison between the FE signal and an FE threshold value Yes Recording / reproducing apparatus,
An FE peak detection circuit that detects a peak value of the E signal; and an FE threshold control circuit that controls a threshold value of the FE comparison unit based on an output of the FE peak detection circuit.
A recording / reproducing apparatus for recording / reproducing information on / from the information recording medium. 2. A servo amplifier for forming a focus servo signal and a tracking servo signal based on an FE (focus error) signal and a TE (tracking error) signal generated based on a reproduction signal from a pickup for scanning an information recording medium. A focusing driver that performs focus control of the pickup by the focusing servo signal, a tracking driver that performs tracking control of the pickup by the tracking servo signal, a TE hold circuit that holds the TE signal, At least a TE switch unit for switching a TE signal and an output value of the TE hold circuit, and a TE comparison unit for switching the TE switch unit in accordance with a comparison result of level comparison between the TE signal and a TE threshold value. Yes In the recording / reproducing apparatus,
A TE peak detection circuit that detects a peak value of the E signal; and a TE threshold control circuit that controls a threshold value of the TE comparison unit based on an output of the TE peak detection circuit.
A recording / reproducing apparatus for recording / reproducing information on / from the information recording medium. 3. An RF comparator for outputting a comparison result signal obtained by comparing an RF signal generated based on a reproduction signal from the pickup with an RF threshold value, and an RF peak detecting a peak value of the RF signal. Detection circuit and this RF
Based on the output of the peak detection circuit,
An RF threshold value control circuit for controlling a threshold value;
An OR circuit for performing an OR operation between an output of the threshold control circuit and an output of the FE threshold control circuit or an output of the TE threshold control circuit; 3. The recording / reproducing apparatus according to claim 1, wherein switching is controlled by an output of the OR circuit.