JPH09288826A - Optical information reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable regenerative signal processing irrespective of size of an amplitude level of a regenerative signal by optimizing a signal level in each area based on an amplitude level of the regenerative signal detected in each area of a recording medium. SOLUTION: In this device, an amplitude level of the regenerative signal read out in real time by a detector 1 is amplified to become a prescribed level with AGC 2 in a preformat area of the recording medium. In a data area, at the time of initial operation, an amplitude level of the regenerative signal is detected from a DMA of the recording medium, and is amplified with a preset fixed gain for this amplitude level by an envelope detector 5 and a CPU 6. Consequently, irrespective of any areas and size of an amplitude level of the regenerative signal, erroneous gain setting by the amplitude of the regenerative signal is prevented, and hence stable signal processing such as binarization processing, etc., is carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information reproducing apparatus for reproducing recorded information from an optical information recording medium such as a magneto-optical disk.

[0002]

2. Description of the Related Art FIG. 8 shows a block diagram of a reproduction signal processing system in a general optical information reproducing apparatus. A reproduction signal processing system in this optical information reproducing apparatus includes a detector 31 for detecting a signal from the optical information recording medium, an amplifier 32 for amplifying the detected signal, and a noise filter 33 for cutting noise in an unnecessary signal band. , A binarization circuit 34 for binarizing a reproduction signal, and a PLL for generating a synchronous clock.
Circuit 35 and discriminator 36 for discriminating whether or not data is present in the detection window obtained by the synchronous clock.
And a decoder 37 that decodes the encoded recording data.

The amplifier 32 is generally AGC (Auto
It has a function called Gain Control). This AGC
Is a variation in the recording sensitivity of optical information recording media, changes in environmental conditions such as temperature, dirt and scratches on media, aging, etc.
The noise filter 33 and the binarization circuit 34 can operate normally by setting the input value into an appropriate range so that the input value does not become too large or too small due to changes in the amplitude of the detection signal that may occur due to various factors. It is something to do.

FIG. 9 shows a general configuration of the AGC circuit. This AGC circuit includes a multiplier 21, a rectifier circuit 22,
It is composed of a differential amplifier 23 and a constant voltage source 24, and the output level range is determined by the voltage of the constant voltage source.

However, in order for the AGC to function properly,
In order to equalize the subsequent processing conditions, it is necessary to have a standard for which part of the read signal is processed.
For example, in Japanese Patent Laid-Open No. 58-73022, for each sector of the optical information recording medium, the amplitude level of the reproduction signal of the VFO portion of the preformatted area is detected for each preformatted area, and the amplitude level is a predetermined value. Adjust and set the gain of the amplifier so that. It proposes a method of amplifying the reproduction signal of the pre-formatted area with a set fixed gain.

Further, for example, in Japanese Unexamined Patent Publication (Kokai) No. 5-62202, an SM section and a VF are provided for each sector of an optical information recording medium.
The amplitude level of the reproduction signal in any one of the predetermined areas such as the O section and the SYNC section is detected, and the gain of the amplifier is adjusted and set so that the amplitude level becomes the predetermined value. And
There has been proposed a method of amplifying a reproduction signal in the sector with a set fixed gain.

[0007]

FIG. 7 shows an example of a sector format of a general optical disk used in the above-mentioned conventional optical information reproducing apparatus. In this example, the sector has a pre-recorded preformatted area 38,
It is divided into a rewritable data area 39. Since the pre-format area 38 is created by the stamper, the amplitude level of the reproduction signal is relatively small between discs and the amplitude value is stable, but the data area 3
In No. 9, the variation in the amplitude level of the reproduction signal becomes large depending on the write power and the sensitivity of the disc.

In the device proposed in Japanese Patent Laid-Open No. 58-73022, many defect patterns exist in the VFO section. Therefore, when detecting the signal level of the reproduction signal, the defect pattern is erroneously detected from the amplifier. When the gain is adjusted, for example, when the amplitude level of the defect pattern is high, the gain of the amplifier is set to a small value, so that a pattern having a small amplitude level such as the ID part may not be readable.

Further, in the information reproducing apparatus proposed in Japanese Patent Laid-Open No. 622022/1993, the SM section, VFO section, SYNC
The gain of the amplifier is set for each section. Therefore, for example, when the gains of the amplifiers of those sectors are set in the preformatted area 38, when the data part of the data area 39 whose amplitude level is smaller than that of the preformatted area 38 is reproduced, the set fixed gain is set. If so, it may become unreadable because it becomes smaller. On the contrary, when the gain of the amplifier of the sector is set in the data area 39, the reproduction signal in the preformat area 38 may be too large to be read.

Therefore, in these devices, an appropriate amplitude level cannot be obtained and the subsequent binarization processing cannot be performed, and the problem that the data cannot be read at one time because the gain of the amplifier is fixed. Occurs. Furthermore, since reading is continued until it becomes unreadable, there is a problem that reading takes time.

Therefore, according to the present invention, the signal level is optimized for each area based on the amplitude level of the reproduced signal detected for each area of the recording medium, and stable reproduced signal processing is performed regardless of the amplitude level of the reproduced signal. It is an object of the present invention to provide an optical information reproducing device for performing.

[0012]

In order to achieve the above object, the present invention reproduces information from an optical information recording medium having a preformatted area in which information is recorded in advance and a rewritable data area. In the optical information reproducing apparatus, when reproducing information from the pre-formatted area, amplification means for applying AGC (Auto Gain Control) so as to amplify the read reproduced signal so as to have a predetermined amplitude level, and the data area. When reproducing information from, the amplitude level of the reproduction signal is detected in the already recorded area provided on the optical information recording medium during the initial operation, and a predetermined gain corresponding to the detected amplitude level is set. A means for amplifying information reproduced from the data area and an optical information reproducing apparatus are provided.

The optical information reproducing apparatus having the above structure detects the amplitude level of the reproduced signal read out in real time in the preformatted area of the recording medium in which the amplitude level of the reproduced signal is relatively small, and determines the predetermined level. The amplitude level of the reproduction signal is detected by detecting the amplitude level of the reproduction signal in the pre-recorded area such as DMA (Defect Management Area) of the recording medium during the initial operation in advance in the data area. By amplifying with a set fixed gain for the set amplitude level, erroneous gain setting due to the amplitude of the playback signal can be prevented regardless of the amplitude level of the pre-format area, data area and playback signal. , Stable 2
Signal processing such as digitization processing is performed.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a schematic configuration of a portion related to a reproducing operation of an optical information reproducing apparatus according to a first embodiment of the present invention, and will be described.

Now, a recorded area (DMA: Defect Management Area) of the recording medium used in this embodiment will be described with reference to the layout diagram of the data zone shown in FIG. The data zone is composed of a user area and a DMA that sandwiches the user area at the front and back. The DMA
Is an area in which the structure of the data zone and the information for defect management are written after the initial operation of the disc. Therefore, from the amplitude level of the DMA, the amplitude level of the reproduction signal of the MO section in the data area, which is a similar rewritable zone, It is possible to predict and set the gain of the amplifier for the reproduction signal of the MO unit.

This optical information reproducing apparatus detects a signal from a recording medium such as an optical pickup, and reproduces a reproduced signal (hereinafter referred to as an ID signal) 7 in a preformat area such as SM or AM shown in FIG. And a detector 1 for outputting a reproduction signal (hereinafter referred to as MO signal) 8 of the data area
An amplifier 2 which has an AGC function and controls in real time so that the amplitude level of the ID signal 7 becomes a predetermined value;
A gain-adjustable amplifier 4 for amplifying the signal 8, an envelope detector 5 for detecting a peak value of a reproduction signal of the MO unit of the DMA amplified by the amplifier 4, and a peak value obtained by the envelope detector 5. Is compared with a predetermined crest value, and when the obtained crest value is not a predetermined value, the gain of the amplifier 4 is changed and the MO signal 8 is amplified by setting the D / A converter 10. CPU6 and the amplifiers 2 and 4 for ID and MO
A binarizing circuit 3 for binarizing the output signals of the reproduction signals, which are amplified so that they have a constant peak value.
It is composed of The peak value detected by the envelope detector 5 is converted into a digital signal by the A / D converter 9 and then sent to the CPU 6.

The operation in the initial state of the optical information reproducing apparatus according to the present embodiment having such a configuration will be described with reference to the flow chart shown in FIG. First, after turning on the power supply, when an optical disc as an optical recording medium is inserted, the optical disc rotates and the laser diode emits light.
Initial operations such as focusing and tracking operations are performed (step S1).

Next, the optical pickup detects D on the optical disk.
It moves to MA (step S2) and reads the information in the ID part (step S3). Then, the reproduction signal of the ID section is added to the AG
C is applied to control in real time so as to obtain a predetermined amplitude level (step S4). Next, the information of the MO section is read (step S5), and the peak value of the reproduced signal of the MO section is detected by the envelope detector 5 (step S5).
6).

Then, the CPU 6 compares the peak value detected by the envelope detector 5 with a predetermined value (step S7), and if the detected peak value does not match the predetermined value 9, the CPU 6 compares the peak value with the predetermined value. (NO), the CPU 6 changes the value of the D / A converter 10, changes the gain of the amplifier 4, and controls so that the detected peak value matches a predetermined value (target value) (step S8). . If the detected peak value matches the predetermined value (YES), the CPU 6
Holds the gain at that time, and also in each of the subsequent sectors, the MO unit amplifies with this fixed gain.

Next explained is the optical information reproducing apparatus according to the second embodiment of the invention. FIG. 3 shows the configuration of the feedback system of the MO signal amplifier 4, and FIG.
4C, a predetermined value to be compared with the peak value of the reproduction signal of the MO unit of DMA is shown and described.

In the present embodiment, the peak value νV of the reproduced signal of the MO section of the DMA detected by the envelope detector 5 is compared with the voltage (A + α) 14 obtained by adding the minute voltage α (V) to the predetermined value A. A comparator 11 for comparing with a voltage (A−α) 15 obtained by subtracting a minute voltage α (V) from a predetermined value A;
AND circuit 13 that outputs the product of the results of 12 and amplifier 4
The switch 16 for lowering the gain of the amplifier 4 and the switch 17 for increasing the gain of the amplifier 4. Here, the predetermined value A is a predetermined target value, and the minute voltage α is a margin with respect to the target value. For example, if the predetermined value A is 500 mV and the minute voltage α is 30 mV, it is sufficient that the peak value ν is between (A + α) and (A−α).

Next, the gain control operation in this embodiment will be described in detail with reference to the flow chart shown in FIG. However, in FIG. 5, since the operations from step S1 to step S6 in the flowchart shown in FIG. 2 described above are the same, the same reference numerals are given, and the detailed description thereof is omitted here. The part will be described.

First, in the comparator 11, as shown in FIG.
A peak voltage ν (V) of the reproduction signal read by the MO unit of the DMA in step S5 as shown in FIG. 4A and a predetermined voltage as shown in FIG. Voltage (A
+ Α) 14 is compared (step S21).

In this comparison, the detected peak value ν <A + α
If not (NO), that is, if the output of the comparator 11 is "L", the switch 16 for reducing the gain of the amplifier 4 is turned on (step S22), and then the process proceeds to step 6.

However, when the detected crest value ν <A + α (YES), the M in the comparator 12 is
The peak value ν (V) of the reproduction signal read by the O section is compared with the voltage (A−α) 15 obtained by subtracting the minute voltage α (V) from the predetermined value (step S23).

In this comparison, the detected peak value ν> A-α
If not (NO), that is, if the output of the comparator 12 is "L", the switch 17 for increasing the gain of the amplifier 4 is turned on (step S24), and then the process proceeds to step 6.

However, when the detected peak value ν> A-α (YES), that is, A-α <ν <A + α,
This is a case where the outputs of the comparators 11 and 12 both become "H", the output of the AND circuit 13 becomes "H", and the gain of the amplifier 4 is held (step S10). The MO unit of each sector thereafter uses the held gain for amplification.

In the present embodiment, MO has been described as an example, but the present invention is not limited to this, and CD-
Of course, it can be easily applied to R and WOROM. As described above, the optical information reproducing apparatus according to the present embodiment performs AGC amplification in the preformatted area of the recording medium so that the amplitude level of the reproduction signal read in real time has a predetermined peak value. In the data area, during the initial operation, the amplitude level of the reproduction signal is detected in the already recorded area DMA of the recording medium, and the amplitude is amplified with the gain set for the detected peak value. By optimizing the gain, erroneous gain setting due to the amplitude level of the reproduction signal can be prevented in both the preformat area and the data area regardless of the amplitude level of the reproduction signal, and stable 2
Signal processing such as digitization processing can be performed.

[0029]

As described above in detail, according to the present invention, the amplitude level of the read signal read out in real time is detected in the preformat area in which the amplitude level of the read signal of the recording medium is relatively small. AGC is applied to amplify the signal so that it has a predetermined amplitude level, and in the data area, the amplitude level of the reproduction signal is detected in the pre-recorded area such as the DMA in advance during the initial operation, and the setting is made for the detected amplitude level. By amplifying with the fixed gain that has been set, erroneous gain setting due to the amplitude of the reproduction signal can be prevented regardless of the amplitude level of the pre-format area, data area and reproduction signal, and stable binarization processing can be performed. It is possible to provide an optical information reproducing device that performs signal processing such as.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a portion related to a reproducing operation of an optical information reproducing device according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the optical information reproducing device in the present embodiment in the initial state.

FIG. 3 is a diagram showing a configuration of a feedback system of an MO signal amplifier of an optical information reproducing device according to a second embodiment.

4 (a) to 4 (c) are diagrams showing a predetermined value to be compared with the peak value of the reproduction signal of the MO unit of DMA.

FIG. 5 is a flowchart for explaining a gain control operation in the second embodiment.

FIG. 6 is a diagram showing an example of a layout of a data zone of an already recorded area (DMA) of the recording medium used in the embodiment of the present invention.

FIG. 7 is a diagram showing an example of a general optical disc sector format used in an optical information reproducing apparatus.

FIG. 8 is a diagram showing a configuration of a reproduction signal processing system in a conventional optical information reproducing apparatus.

FIG. 9 is a diagram showing a configuration example of a general AGC circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Detector 2, 4 ... Amplifier 3 ... Binarization circuit 5 ... Envelope detector 6 ... CPU 7 ... Preformatted area reproduction signal (ID signal) 8 ... Data area reproduction signal (MO signal) 9 ... A / D Converter 10 ... D / A converter 11, 12 ... Comparator 13 ... AND circuit 14 ... A + α 15 ... A−α 16, 17 ... Switch

Claims (3)

[Claims] 1. An optical information reproducing apparatus for reproducing information from an optical information recording medium having a preformatted area in which information is recorded in advance and a rewritable data area, wherein information is reproduced from the preformatted area. When doing
A so that the read playback signal has a predetermined amplitude level.
Amplifying means for applying GC to amplify, and when reproducing information from the data area, at the time of initial operation, detects an amplitude level of a reproduction signal with respect to an already recorded area provided on the optical information recording medium. , Set a predetermined gain corresponding to the detected amplitude level,
An optical information reproducing apparatus comprising: an amplifying unit that amplifies information reproduced from the data area based on the gain. 2. An optical information reproducing apparatus for reproducing information from an optical information recording medium having a preformatted area in which information is recorded in advance and a rewritable data area, wherein information is recorded from the optical information recording medium. Detecting means for detecting as a reproduction signal, when reproducing information from the preformatted area,
So that the read playback signal has a predetermined amplitude level,
First amplification means for amplifying the reproduction signal from the detection means by applying AGC, and arbitrarily set so that the read reproduction signal has a predetermined amplitude level when reproducing information from the data area. Second amplifying means for amplifying a reproduction signal with a gain, and detecting by the detecting means in an already recorded area provided on the optical information recording medium during an initial operation when reproducing information from the data area. Comparing means for comparing the peak value of the reproduced signal with a predetermined value preset in an arbitrary range; and when the peak value of the reproducing signal is out of the range by the comparing means, the gain of the second amplifying means is set. Means for resetting and controlling the crest value to fall within the range. 3. An optical information reproducing apparatus for reproducing information from an optical information recording medium having a preformatted area in which information is recorded in advance and a rewritable data area, wherein information is recorded from the optical information recording medium. Detecting means for detecting as a reproduction signal, when reproducing information from the preformatted area,
So that the read playback signal has a predetermined amplitude level,
First amplification means for amplifying the reproduction signal from the detection means by applying AGC, and arbitrarily set so that the read reproduction signal has a predetermined amplitude level when reproducing information from the data area. Second amplifying means for amplifying a reproduction signal with a gain, and detecting by the detecting means in an already recorded area provided on the optical information recording medium at the time of initial operation when reproducing information from the data area. A first comparison means for comparing the peak value of the reproduced signal with a first voltage obtained by adding a small voltage set arbitrarily to a predetermined value, and the output result of the first comparison means is negative. In this case, a first switching means for reducing the gain of the second amplifying means, a peak value of the reproduction signal, and a second voltage obtained by subtracting the minute voltage from the predetermined value are compared. Two comparison hands A second switch means for increasing the gain of the second amplifying means when the output result of the second comparing means is negative, and the comparing means of the pair 1 and the second comparing means. Gain setting means for multiplying the respective output results and setting the gain of the second amplifying means to a predetermined value when the result of the product becomes positive. Information playback device.