JPH1055543A - Optical information reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information reproducing device capable of uniforming regenerative signals in size and resolution of different types of recording media by changing reproducing power to correspond to each recording medium. SOLUTION: In this optical information reproducing device, a recording medium 1 is irradiated in a prescribed spot with a laser beam generated by an LD 7, and this reflected light is received by a detector 6, and a regenerative signal including a key word is generated by a reproducing circuit 8. Whenever a new recording medium 1 is loaded, its key word is obtained by a controller 13, so that a data for correcting an reproducing light power output due to a specific difference in characteristic and type of a recording medium stored in a ROM 14 is read out in relation to the key work, and hence the reproducing light power of the LD 7 is corrected accordingly.

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 recording / reproducing information by using a laser beam or the like, and more particularly to an optical information recording / reproducing apparatus having improved recording density by eliminating interference between data pits on an optical disk. About.

[0002]

2. Description of the Related Art In recent years, it has been desired to increase the recording density of an optical disc so that more information can be recorded on, for example, an optical disc used as a recording medium of an optical information recording / reproducing apparatus.

As a method of increasing the recording density of an optical disc, a method of forming an optical mask by increasing a medium surface temperature by irradiating reproduction light to reduce interference between data pits,
Data recorded in the data recording layer is transferred to the reproducing layer by the temperature rise of the recording medium surface due to the irradiation of the reproducing light to reduce the interference between the data pits, or a mask is formed by the temperature rise and the recording layer is changed to the reproducing layer. A method has been proposed in which both data transfer to data is performed. These techniques are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 1-143041 and 1-143.
No. 042.

All of these methods use the temperature rise of the recording medium surface due to the irradiation of the reproduction light, and the data reproduction must always be performed under the same temperature condition. Thus, constant reproduction conditions are maintained regardless of the environmental temperature, linear velocity, and recording density.

Further, Japanese Patent Application No. 3-516540 (International Publication No. WO92 / 14244) discloses a type of magneto-optical recording in which recording pits are erased or raised due to a rise in the temperature of a recording medium due to irradiation of reproduction light. There is disclosed a method of reproducing a medium or an optical recording medium whose reflectivity changes with a rise in temperature. The size of the region is kept constant without being affected by temperature changes.

Japanese Patent Application No. 3-516541 (International Publication No. WO92 / 14245) discloses a magneto-optical recording medium of the type in which recording pits are erased or raised due to an increase in the temperature of the medium due to irradiation of reproduction light. Alternatively, a method for reproducing an optical recording medium whose reflectance changes due to a rise in temperature is disclosed. For example, in a state where the medium is rotated at a constant angular velocity, the position of the medium in the radial direction of the reproduction light is detected to detect the reproduction light. By controlling the power or the intensity of the external magnetic field, the size of the substantial reproduction area is kept constant without being affected by the linear velocity change.

Japanese Patent Application No. 3-516542 (International Publication No. WO92 / 15093) discloses a magneto-optical recording medium of a type in which recording pits are erased or raised due to a rise in temperature of the recording medium due to irradiation of reproduction light. Alternatively, a method of reproducing an optical recording medium whose reflectance changes due to a rise in temperature is disclosed. When the linear recording density on the recording medium varies depending on the radial position, for example, the reproduction is performed while the recording medium is rotated at a constant angular velocity. By controlling the power of the reproducing light or the intensity of the external magnetic field by detecting the radial position of the optical medium, the substantial size of the reproducing area is kept constant regardless of the linear recording density. Further, Japanese Patent Application Laid-Open No. Hei 4-11762
Japanese Patent Laid-Open No. 6 (Kokai) No. 6 discloses a method for adjusting the reproduction light power based on the reflectance of a medium.

[0008]

Problems to be Solved by the Invention Japanese Patent Application No. Hei.
No. 16540, Japanese patent application No. 3-516541, Japanese patent application No. 3-
In each of the techniques disclosed in Japanese Patent No. 516542, the size of the substantial reproduction area can be kept constant without being affected by changes in the medium temperature, the linear velocity, and the linear recording density. However, since the material and thickness of the recording / reproducing film differ depending on the recording medium, if the power of the reproducing light is determined only by the medium temperature, the linear velocity, and the linear recording density, the size of the reproducing area differs in different recording media. Would.

[0009] In particular, a remarkable difference occurs because the shape of the groove on the recording surface is different or the recording / reproducing film is formed of a material having a different composition depending on the manufacturer of the recording medium.
However, even in the case of recording media manufactured by the same manufacturer, when compared with commercially available recording media that meet the quality standards, the sensitivity varies by about ± 10% due to a problem at the time of manufacturing.

[0010] Therefore, in a recording medium for high-density recording to be manufactured in the future, the occurrence of such a degree of sensitivity variation must be considered. Thus, in the above-described technique, when the same recording medium is reproduced again later, the same reproduction signal can be obtained.However, when the recording medium is replaced, reproduction signals from different recording media are made the same. I can't.

As described in Japanese Patent Application Laid-Open No. 4-117626, even if the reproducing light power is changed by the medium reflectivity, the size of the optical mask on the recording medium surface and the transfer area from the recording layer to the reproducing layer can be reduced. The size cannot be fixed. SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical information reproducing apparatus in which the reproducing power is changed for each of different types of recording media and the magnitude and resolution of a reproduced signal are made uniform.

[0012]

According to the present invention, there is provided an optical information recording / reproducing apparatus for optically recording / reproducing information on / from a recording medium by using a laser beam. A laser generating means for generating a laser beam for reading data at an arbitrary reproducing light power, and irradiating the laser beam generated by the laser light emitting element to a predetermined location where a keyword capable of identifying a recording medium is recorded , An optical system that captures the reflected laser light, a reproducing unit that receives the reflected light condensed by the optical system, and generates a reproduction signal including a keyword, and a reproduction light power depending on the characteristics and types of recording media in advance. A storage unit for storing data for performing the output correction and a table in which the keywords are associated with each other; and Control means for reading out data for correcting the recording medium and outputting and controlling the corrected reproduction light power value to the laser light emitting element driving means, wherein the control means performs reproduction every time a new recording medium is mounted. Provided is an optical information reproducing apparatus that reads a keyword from a signal and corrects a reproduction light power based on data for correction based on the keyword.

[0013] The optical information reproducing apparatus having the above-described configuration irradiates a laser beam generated by a laser light emitting element to a specific portion of a recording medium, generates a reproduction signal including a keyword from the reflected light, and controls the control means. Each time a new recording medium is mounted, the keyword is obtained, and the data for correcting the output of the reproduction light power due to the difference in the characteristics or type of the recording medium stored in the storage means in association with the keyword is read out. Then, the reproduction light power of the laser light emitting element is corrected.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic configuration example of an optical information reproducing apparatus according to a first embodiment of the present invention, and will be described.

An optical information reproducing apparatus according to the present invention performs recording and reproduction of information on an optical recording medium by using a laser beam. The data pits recorded on the recording layer are transferred to the reproducing layer, or a part of the recording pits is shielded, or both are simultaneously performed, thereby reducing the interference between the data pits and improving the recording density. This is a device that reproduces data from a recording medium, and varies the power of reproduction light with the recording medium to read data optimally with the reproduction light power.

The optical information reproducing apparatus includes a recording medium 1 such as an optical disk which optically records information detachably and optically,
An optical system including an objective lens 2, a beam splitter (BS) 3, a collimating lens 4, and a condenser lens 5, which irradiates the recording medium 1 with laser light generated by a laser diode (LD) 7 and captures the reflected laser light; , Condenser lens 5
Detector 6 that receives the reflected light condensed by the device and performs photoelectric conversion
A reproduction circuit 8 for generating a reproduction signal, a binarization circuit 9 for digitally converting the reproduction signal, and receiving the binarized reproduction signal, and generating a synchronous clock necessary for the controller 13 to read data. A synchronizing circuit 10, a ROM 14 for storing in a table data for performing output correction of reproduction light according to the characteristics and types of recording media in advance, an LD driving circuit 11 for driving the laser diode 7, and an LD driving circuit 1
1 comprises an LD power instruction circuit 12 for instructing the output value of the laser diode 7 and a controller 13 for controlling the LD power instruction circuit 12 based on a synchronous clock signal from the synchronous circuit 10 and correction data from the ROM 14. .

The controller 13 also controls a servo system and a write system (not shown). Each time a new recording medium 1 is mounted, the controller 13 reads predetermined information written in the control track area from the reproduction signal,
The reproduction light power is corrected based on the predetermined information.

The predetermined information to be read includes, for example, the name of the manufacturer of the recording medium. That is, the optimum reproduction light power of the recording medium manufactured by the manufacturer is measured in advance, and the optimum value and the manufacturer name are stored in the ROM 14 as a table. Then, using the name of the manufacturer read from the mounted recording medium as a keyword, the optimum reproducing light power is read from the table of the ROM 14. Of course, even if it is not the manufacturer's name, it is only necessary to determine the attached recording medium functioning as a keyword, and if the recording medium itself has another identifiable keyword such as a model name or an identification number, the keyword is used as the keyword. The table may be stored in the ROM 14 as a table (LD power table) in which the measured reproduction light power is optimally related.

In addition, if the optimum value of the reproducing light power for the recording medium 1 is recorded in the control track of the loaded recording medium 1, the value is read and the reproducing power is set to that value. Things are also possible. Since the data of the control track is recorded as an emboss signal, the magnitude of the reproduction light power is only the magnitude of the reproduction signal, and the reproduction light power until the keyword is read out is a value considered to be appropriate. I don't care. In this embodiment, a ROM is used as a storage element. However, the present invention is not limited to this, and another storage element such as a data rewritable RAM, EPROM, or EEPROM can be used.

Next, with reference to a flow chart shown in FIG. 2, setting of an appropriate reproducing light power in the optical information reproducing apparatus thus configured will be described. First, LD7
Is turned on at a predetermined initial reproduction power (step S1). As described above, the initial reproduction power value is not particularly determined, but may be any value within a range that is normally used. The laser light generated from the LD 7 is applied to the recording surface of the recording medium 1 via the optical system.

Then, the servo is pulled into an appropriate position on the recording surface of the recording medium 1 (step S2). The address is read from the laser beam reflected at that location, and the current position is determined (step S3).

Next, the distance to the control track is calculated, and the control track is moved to the calculated control track (step S4). Then, the manufacturer name of the medium written in the control track area of the recording medium is read (step S5). The read light power value stored in association with the read medium maker name is read from the table of the ROM 14 (step 6), and the controller 13
Is reset to the reproduction light power value (step S
7).

Therefore, by changing the reproducing power for each recording medium, the size of the reproduced signal and the resolution of the reproduced signal can be made uniform even when reproducing different media.

Further, by reading the name of the medium manufacturer recorded on the recording medium in advance, and adjusting the reproduction light power according to the read name of the manufacturer, the reproduction can be performed even when replacing the recording medium between different recording medium manufacturers. By making the size of the reproduction area the same, the size and resolution of the reproduction signal can be made uniform.

Next, FIG. 3 shows a schematic configuration example of an optical information reproducing apparatus according to a second embodiment and will be described. Here, in the components of the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted.

This embodiment has the same basic operation as the first embodiment, but obtains an optimum reproduction light power based on a reproduction signal before digitizing the reproduction signal.

In this optical information reproducing apparatus, an envelope detector 15 and an A / D converter 16 are provided between the reproducing circuit 8 and the controller 13 in parallel with the binarizing circuit 9 and the synchronizing circuit 10. . With these, the envelope of the reproduced signal from the reproducing circuit 8 is detected, the detected signal is digitized, and input to the controller 13.

Therefore, every time a new medium is mounted, the controller 13 reproduces the test track of the recording medium 1 while changing the reproduction light power, and determines the optimum reproduction light power of the recording medium.

In this embodiment, the data written on the test track is the repetition of the shortest recording length data as shown in FIG. 4, and the controller 13 outputs the signal obtained by detecting the envelope of the reproduced signal to the A / D converter 16. Then, the amplitude of the signal is obtained through the interface, and the reproducing light power is determined so that the amplitude value of the shortest recording length data becomes maximum. The test track data may be recorded at the time of formatting or may be written each time the recording medium is mounted.

With reference to the flow chart shown in FIG. 5, the setting of an appropriate reproducing light power in the optical information reproducing apparatus thus configured will be described. First, the LD 7 is turned on with an arbitrary initial reproducing power (step S11), and the generated laser light is irradiated toward the recording surface of the recording medium 1 via the optical system.

Then, the servo is pulled into an appropriate position on the recording surface of the recording medium 1 (step S12). The address is read from the laser beam reflected at that location, and the current position is determined (step S13).

Next, the distance to the test track on the recording medium 1 is calculated, and the apparatus moves to the calculated test track (step S14). Then, the reproduction light power of the LD 7 is set to the lowest power and emitted (step S15),
The envelope value of the reproduction signal of the test track obtained from the reflected light is taken into the controller 13 via the A / D converter (step S16).

Under the control of the controller 13, the LD
7 is increased by a predetermined step amount (step S17). Then, it is determined whether or not the reproduction light power of the LD 7 exceeds the maximum power (Step S).
18). If the maximum power is exceeded in this determination (YE
S), the envelope values at the respective reproduction light powers taken in at step S16 are compared to find the reproduction light power giving the maximum amplitude (step S19). However, if the maximum power is not exceeded (NO), the process returns to step S16,
Increase the step amount.

Next, the reproduction light power of the LD 7 is set to a value giving the found maximum amplitude (step S20). In this embodiment, the amplitude of the signal is obtained by envelope detection as a method of obtaining the optimum reproduction light power from the reproduction signal before binarization. In addition, the center of the reproduction waveform of the shortest recording length data and the longest recording length data It is also conceivable to use another amount that varies depending on the size of the reproduction area, such as a method of obtaining the optimum power from the relationship between the levels at the center of the reproduction waveform.

Next, FIG. 6 shows a schematic configuration example of an optical information reproducing apparatus according to a third embodiment and will be described. Here, in the components of the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted.

The present embodiment has the same basic operation as the first embodiment, but obtains the optimum reproduction light power from the binarized signal. Also in this embodiment, each time a new recording medium is mounted, the controller reproduces the test track while changing the reproduction light power, and determines the optimum reproduction light power in the recording medium.

In this optical information reproducing apparatus, an error rate measuring circuit 17 is provided between the synchronizing circuit 10 and the controller 13, and for example, an error rate is written on a test track of the recording medium 1, for example.
The data of the random pattern as shown in FIG. 7 is read, and the controller 13 sets the value at which the window margin of the reproduced signal is the maximum as the optimum reproduced light power. The measurement of the window margin can be performed by measuring the data error rate by the error rate measuring circuit 17 while changing the clock phase of the synchronous circuit 10 with a signal from the controller 13. The test track data may be recorded at the time of formatting or may be written each time the recording medium 1 is mounted.

With reference to the flowchart shown in FIG. 8, the setting of an appropriate reproducing light power in the optical information reproducing apparatus thus configured will be described. In this setting method, step S1 of the flowchart of FIG.
6, S17 and S19 are different, and the other sequences are the same.

First, the LD 7 is turned on with an arbitrary initial reproduction power, a servo is drawn into an appropriate position on the recording surface of the recording medium 1, the current position is determined from the address, and the LD is moved to a test track, and the reproduction light of the LD 7 is reproduced. The power is set to the lowest power (steps S21 to S25).

The light is emitted to the test track with the reproduction light power having the lowest power value, and the reproduction signal obtained by the reflected light is taken into the controller 13 (step S26). The read data is compared with correct data set in advance by the error rate measurement circuit 17 to determine an error rate, and the error rate is taken into the controller 13 (step S27).

Under the control of the controller 13, the LD
7 is increased by a predetermined step amount (step S28). Then, it is determined whether or not the reproduction light power of the LD 7 exceeds the maximum power (Step S).
29). If the maximum power is exceeded in this determination (YE
S), compare the data error rates at the respective reproduction light powers measured in step S27, and find the reproduction light power giving the maximum amplitude (step S30). However, if the maximum power is not exceeded (NO), the process returns to step S26, and the step amount is increased.

Next, the reproduction light power of the LD 7 is set to a value that gives the found minimum data error rate (step S).
31). Further, for example, when there are a plurality of reproduction powers which give the minimum data error rate, for example, a state in which no error occurs continues within a constant reproduction power width, the value near the center of these is set.

In this embodiment, the data pattern used for the test is not limited to a random pattern. In the present embodiment, the window margin is measured to determine the optimum reproduction power. However, the reproduction power under the condition where the jitter of the binarized data is minimized is determined as the optimum reproduction power. It is also conceivable to use other quantities which vary with.

Furthermore, the aforementioned Japanese Patent Application No. 3-516540.
No., Japanese Patent Application No. 3-516541 and Japanese Patent Application No. 3-5165.
It is also possible to improve the accuracy of the reproduction power by combining with the techniques described in JP-A-42-42.

In particular, in the method of transferring the data of the recording layer to the reproducing layer by the temperature rise due to the reproducing light, the minimum reproducing power at which the data is transferred is obtained by changing the reproducing power while observing the envelope. The power obtained by multiplying or adding a predetermined number to the power is used as the optimum reproduction power.

As described above, according to the optical information reproducing apparatus of the present embodiment, by changing the optimum reproducing light power for each recording medium, it is not affected by the difference between recording media.
By keeping the size of the reproduction area constant, an optimum reproduction signal can always be obtained.

Further, by reading the name of the manufacturer recorded on the recording medium and determining the reproduction light power, the size of the reproduction area is kept constant without being affected by the difference between the manufacturers of the recording medium, and the optimum value is always obtained. The reproduction signal can be obtained.

Further, by reproducing the data written in the test track and determining the reproduction light power, the size of the reproduction area is kept constant regardless of the recording medium, and the optimum reproduction signal can always be obtained. .

Although the recording power has been appropriately changed according to the name of the manufacturer of the recording medium,
For a recording medium such as an MSR in which the size of a reproduction area is controlled by a temperature rise due to reproduction light, even if the recording power is the same, the reproduction signal is different if the reproduction power is different. On the other hand, it is impossible to optimize only the recording power, and it is necessary to optimize both the recording power and the reproducing power for each recording medium.

[0050]

As described above in detail, according to the present invention, it is possible to provide an optical information reproducing apparatus in which the reproducing power is changed for each of different types of recording media to make the magnitude and resolution of the reproduced signal uniform.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration example of an optical information reproducing device according to a first embodiment.

FIG. 2 is a flowchart illustrating setting of an appropriate reproducing light power of the optical information reproducing apparatus according to the first embodiment.

FIG. 3 is a diagram illustrating a schematic configuration example of an optical information reproducing apparatus according to a second embodiment.

FIG. 4 is a diagram showing a relationship between an envelope detection signal and a reproduction signal used for obtaining an appropriate reproduction light power in a second embodiment.

FIG. 5 is a flowchart for describing setting of an appropriate reproducing light power of the optical information reproducing apparatus according to the second embodiment.

FIG. 6 is a diagram illustrating a schematic configuration example of an optical information reproducing apparatus according to a third embodiment.

FIG. 7 is a diagram showing an example of random pattern data written on a test track of a recording medium.

FIG. 8 is a flowchart for explaining setting of an appropriate reproducing light power of the optical information reproducing apparatus according to the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Recording medium 2 ... Objective lens 3 ... Beam splitter (BS) 4 ... Collimating lens 5 ... Condensing lens 6 ... Detector 7 ... Laser diode 8 ... Reproduction circuit 9 ... Binarization circuit 10 ... Synchronization circuit 11 ... LD drive circuit 12 LD power instruction circuit 13 Controller 14 ROM

Claims (3)

[Claims] 1. An optical information recording / reproducing apparatus for optically recording / reproducing information on / from a recording medium using a laser beam, wherein a laser light emitting element is driven and a laser beam for reading data with an arbitrary reproducing light power. A laser generating means for generating a laser light emitted from the laser light emitting element to a predetermined location where a keyword capable of identifying a recording medium is recorded,
An optical system for capturing the reflected laser light, a reproducing means for receiving the reflected light condensed by the optical system and generating a reproduction signal including a keyword, and a reproduction light power depending on the characteristics and types of recording media in advance. Storage means for storing data for performing output correction and the keyword as a table in association with each other; reading out data for correction of a corresponding recording medium from the storage means based on the keyword of the reproduction signal; Control means for controlling the output of the corrected reproduction light power value to the light-emitting element driving means. Each time a new recording medium is mounted, the control means reads a keyword from the reproduction signal and performs correction based on the keyword. An optical information reproducing apparatus, wherein the reproducing optical power is corrected by data for the optical information reproducing apparatus. 2. The method according to claim 1, wherein the keyword is a name of a maker of the recording medium or a unique identification symbol composed of a number or a symbol so that the recording medium can be identified.
2. The optical information reproducing apparatus according to claim 1, wherein the information is recorded on a test track or a desired area of the recording medium by an emboss signal. 3. An optical information recording / reproducing apparatus for optically recording / reproducing information on / from a recording medium by using a laser beam. A laser generating means for generating, a laser light generated by the laser light emitting element is irradiated on a predetermined portion of the recording medium on which a specific random pattern is recorded,
An optical system that captures the reflected laser light, a reproducing unit that receives the reflected light condensed by the optical system, and generates a reproduction signal including data of a specific random pattern, and data of the specific random pattern, An error rate measuring means for comparing reference data and measuring a data error rate; and a reproduction light optimal for the laser generating means, based on the reproduction signal and the data error rate, wherein a value that maximizes a window margin of the reproduction signal is determined. Control means for setting the power as the power, and correcting the reproduction light power to a value that maximizes the window margin based on the data error rate obtained each time a new recording medium is mounted. Optical information reproducing device.