JP2002260250A - Information recording/reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the variation of a servo gain even when disk reflectance, the optimum recording laser power, or the like is greatly different, in a recording/reproducing operation using a light source having different wavelengths for an optical recording medium, and to make circuitry therefor simple and common. SOLUTION: Either a photo-detecting signal from a quadripartite photodetector 1 or a photo-detecting signal from a quadripartite photodetector 2 is selected according to a light source selection signal at selectors 3a-3d. Variable gain amplifiers 4a-4d amplify each photo-detecting signal, from which a photo- detecting total sum signal at a total sum signal operational circuit 5, a FE(focus error) signal at a FE signal operational circuit 6, and a TE(tracking error) signal at a TE signal operational circuit 7 are generated. A set gain calculation part 12 calculates and sets the gain of the variable gain amplifiers 4a-4d from the photo-detecting total sum signal. A gain control part 11 automatically controls the gain of the FE signal and the TE signal (servo error signals) on the basis of the photo-detecting total sum signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CD for recording or reproducing data on an information recording medium such as an optical disk.
-ROM drive, CD-R drive, CD-
RW drive device, DVD-ROM drive device, DV
The present invention relates to an information recording / reproducing device such as a DR drive device.

[0002]

2. Description of the Related Art Conventionally, an optical disk apparatus as an information recording / reproducing apparatus has a so-called focus servo mechanism and tracking servo mechanism. The servo error signal used in these mechanisms is, for example, in the case of a tracking servo, the track error signal TE receives the reflected light from the optical disc with, for example, a four-divided photodetector,
Each light receiving output is generated by arithmetic processing. These servo error signals change the laser power to be irradiated depending on the difference in the reflectivity of the optical disk and the various modes such as reproduction, recording, and erasure, so that the received light output greatly changes, and the amplitude of the servo error signal greatly changes. I do. The change in the amplitude of the servo error signal causes a change in the servo gain, which causes a problem that the servo operation becomes unstable or, in the worst case, the servo comes off.

[0003] The difference in the reflectivity of the optical disc described above varies not only with the disc type and the manufacturer, but also with the lot variation and the in-plane variation even for the same disk. Further, the optimum recording laser power at the time of recording differs depending on the disc, and the difference in amplitude of the servo error signal. In particular, in the case of a recording apparatus for a plurality of types of optical discs, for example, in an apparatus capable of recording on both CD-R and CD-RW, the reflectivity and optimum recording power of these optical discs are greatly different. The difference between the amplitudes becomes particularly remarkable.

In order to solve such a problem, a servo error signal generating circuit and an automatic gain control circuit therefor are provided.
An optical disc device has been proposed in which a servo error signal such as a focus error signal or a track error signal is divided by a total signal of light receiving outputs to correct a change in servo gain caused by a change in light receiving output. .

An automatic gain control circuit (hereinafter referred to as AGC (Automatic Gain Controller)
ol) circuit), the gain is automatically adjusted so that the total received light signal becomes a predetermined voltage, the same gain is added to each servo error signal, and the received light output fluctuates due to changes in disk reflectivity and the like. However, an optical disk device that is always controlled so that the servo gain is maintained at a constant level has been put to practical use.

[0006] Such a device will be further described here by taking a focus error signal generated by the astigmatism method as an example. The same applies to other servo error signals.

FIG. 8 is a block diagram showing an example of a configuration of a focus error signal generator of a focus servo mechanism in a conventional optical disk device. The focus error signal generating unit 100 is a four-divided light receiving element that receives light reflected from an optical disk (not shown).
Reference numerals 0a to 100d denote the respective light receiving elements. The outputs of the light receiving elements are denoted by SA to SD. Reference numeral 101 denotes a focus error signal operation circuit that generates a focus error signal FE based on the astigmatism method, 102 denotes a sum signal operation circuit that generates a light reception sum signal SUM, 104 denotes a variable gain amplifier,
Reference numeral 05 denotes a gain control unit which outputs a gain control signal Sgain corresponding to the level of the output SUMn of the 104 and supplies the signal to the 104.

The circuits 104 and 105 constitute an AGC circuit, and the output of the circuit 104 is maintained at a predetermined level even if the light receiving signal fluctuates. Reference numeral 103 denotes a variable gain amplifier having substantially the same characteristics as 104. The variable gain amplifier 103 receives the above-mentioned gain control signal Sgain, and sets its output to FEn. The focus error signal FE and the light receiving sum signal SUM are respectively generated by calculations based on the following equations (1) and (2).

[0009]

FE = (SA + SC)-(SB + SD)

[0010]

## EQU2 ## SUM = (SA + SB + SC + SD)

Further, if the gain given by the gain control signal Sgain is G and the predetermined level of SUMn is k,
It can be seen that FEn is obtained by normalizing the FE signal with the received light sum signal SUM based on the following Expressions 3 and 4.

[0012]

SUMn = G · (SA + SB + SC + SD) = k

[0013]

FEn = G · ((SA + SC) − (SB + SD)) = k ((SA + SC) − (SB + SD)) / (SA + S)
B + SC + SD)

Therefore, if such a servo error signal generation circuit is used, the servo error signal amplitude is kept constant and the servo gain does not fluctuate even if the total light reception signal fluctuates due to fluctuations in the reflectivity of the optical disk. . This method is widely used because it is more suitable for an integrated circuit than the above-mentioned division circuit.

However, in the above-mentioned conventional technique, the disc reflectivity, the optimum recording laser power, etc., are different from those of the prior art, for example, when the present invention is applied to a recording apparatus for a plurality of types of discs such as a CD-R disc and a CD-RW disc. When dealing with a number of discs that are significantly different, the light receiving sum signal and the servo error signal fluctuate extremely greatly. In order to apply the present invention to recording and reproduction of these various kinds of disks, the variable gain amplifier must have a very large variable gain range, which is difficult to realize. Also, since each signal operation circuit handles a signal before AGC in which the signal level fluctuates greatly, it is necessary to increase the dynamic range, and fine adjustment functions and vastness are provided for circuits such as various offset adjustments and balance adjustments. There is a problem that a dynamic range is required, and it is difficult to realize the circuit or the circuit scale becomes very large.

To solve such a problem, there is a technique described in the specification and drawings of Japanese Patent Application No. 2000-84904 filed earlier by the present applicant. In the information recording / reproducing apparatus, each variable gain amplifier amplifies a light receiving signal output from a light receiving element, and an FE signal calculating circuit and a TE signal calculating circuit convert a servo error signal (FE, TE) from each light receiving signal. Is calculated, the received light sum signal calculation circuit generates the received light sum signal (SUM) from the amplified light receiving signals (VA to VD), and the set gain calculation setting unit calculates the gain of each variable gain amplifier from the received light sum signal. The gain of the servo error signal is automatically controlled based on the received light total signal.

That is, the variable gain amplifier amplifies the light receiving signal output from the light receiving element, and the FE signal calculating circuit and the TE signal calculating circuit calculate a servo error signal (FE, TE) from each of the light receiving signals. The received light sum signal calculation circuit generates a received light sum signal (SUM) from the amplified received light signals (VA to VD), and a set gain calculation setting unit calculates and sets the gain of the variable gain amplifier from the received light sum signal, This is to automatically control the gain of the servo error signal based on the received light sum signal. Even with a simple device configuration, the servo gain at the time of recording / reproducing on a variety of information recording media with greatly different reflectivity and optimum recording laser power etc. This ensures that the fluctuation can be corrected.
In recent years, devices for recording and reproducing with light sources having different wavelengths, such as CDs and DVDs, have been put into practical use, and devices capable of recording and reproducing information on both of these information recording media have been developed.

[0018]

However, in the prior art such as the above-mentioned prior application, in the case of a device capable of recording and reproducing with a light source of a different wavelength, for example, in the case of a device capable of recording and reproducing both a CD and a DVD, Depending on the design of the optical pickup, there is a difference in the level of the received light signal received from the disk reflected light when irradiating each light source, and the optimum recording power may be different. Similarly to the above, there is a problem that the realization is difficult or the circuit scale becomes very large. In addition, there is also a problem that providing these circuits individually is disadvantageous in reducing the size and power consumption of the apparatus.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and when recording and reproducing information on and from an information recording medium using light sources of different wavelengths, the disc reflectivity, the optimum recording laser power, and the like are greatly different. Correction of fluctuations in servo gain even during recording / reproducing of various types of information recording media, so that circuit components such as the AGC circuit and each signal operation circuit can be realized simply and in common. With the goal.

[0020]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises two light sources and a light source for receiving reflected light from an information recording medium at the time of light irradiation by one of the two light sources. A plurality of first light receiving means for outputting the received light signal, and receiving the reflected light from the information recording medium at the time of light irradiation by the other of the two light sources, and outputting the received light signal A plurality of second light receiving means,
The light receiving signal output from each of the first light receiving means and the second light receiving means respectively corresponding to each of the first light receiving means according to a light source selection signal indicating which of the two light sources emits light. A plurality of selection means for respectively selecting and outputting any one of the light reception signals output from the plurality of; a plurality of variable gain amplification means for amplifying the light reception signal output from each of the selection means; A servo error signal calculating means for calculating and outputting a servo error signal based on the plurality of light receiving signals output from the variable gain amplifying means; and a light receiving sum signal based on the plurality of light receiving signals output from each of the variable gain amplifying means. The gain of each of the variable gain amplifying means is calculated and set based on the received light sum signal generating means and the received light sum signal generated by the received light sum signal generating means. An information recording device comprising: a gain calculation setting means; and an automatic gain control means for automatically controlling the gain of the servo error signal output from the servo error signal calculation means based on the total light reception signal generated by the total light reception signal generation means. A playback device is provided.

Also, a first light receiving unit comprising two light sources and a plurality of first light receiving units for receiving the reflected light from the information recording medium at the time of light irradiation by one of the two light sources and outputting the light receiving signal. Means, a second light receiving means comprising a plurality of light receiving means for receiving the reflected light from the information recording medium at the time of light irradiation by the other light source of the two light sources and outputting the light receiving signal, The light receiving signal output from each of the first light receiving means and the light receiving signal output from each of the second light receiving means corresponding to each of the first light receiving means according to a light source selection signal indicating which of the light sources emits light. A plurality of selecting means for selecting and outputting one of the received light signals, a plurality of variable gain amplifying means for respectively amplifying the received light signal output from each of the selecting means, and each of the variable gain amplifiers From the means Servo error signal calculating means for calculating and outputting a servo error signal based on the plurality of received light receiving signals, and a light receiving sum signal for generating a light receiving sum signal based on the plurality of light receiving signals output from each of the variable gain amplifying means. Generating means, peak hold means for detecting and outputting the peak level of the received light sum signal generated by the received light sum signal generating means, and each of the variable gains based on the peak level signal output from the peak hold means. Gain calculating and setting means for calculating and setting the gain of the amplifying means; and automatic control for automatically controlling the gain of the servo error signal output from the servo error signal calculating means based on the received light total signal generated by the received light total signal generating means. An information recording / reproducing apparatus having gain control means may be used.

Further, a first light receiving unit comprising two light sources and a plurality of first light receiving units for receiving the reflected light from the information recording medium at the time of light irradiation by one of the two light sources and outputting the received light signal. Means, a second light receiving means comprising a plurality of light receiving means for receiving the reflected light from the information recording medium at the time of light irradiation by the other light source of the two light sources and outputting the light receiving signal, The light receiving signal output from each of the first light receiving means and the light receiving signal output from each of the second light receiving means corresponding to each of the first light receiving means according to a light source selection signal indicating which of the light sources emits light. A plurality of selecting means for selecting and outputting one of the received light signals, a plurality of variable gain amplifying means for respectively amplifying the received light signal output from each of the selecting means, and each of the variable gain amplifiers Means Servo error signal calculating means for calculating and outputting a servo error signal based on the plurality of output light receiving signals; and a total light receiving signal for generating a total light receiving signal based on the plurality of light receiving signals output from each of the variable gain amplifying means. Generating means, adding operation means for adding the light receiving signals output from each of the selecting means and outputting the added signal, and adding signal variable gain amplifying means for amplifying the added signal output from the adding operation means. A peak hold means for detecting and outputting the peak level of the addition signal output from the addition signal variable gain amplification means, and the variable gain amplification means based on the peak level signal output from the peak hold means; Gain calculation setting means for calculating and setting each gain of the addition signal variable gain amplifying means; and Based on the light reception sum signal generated it may be in the information recording and reproducing apparatus having an automatic gain control means for automatically controlling the gain of the servo error signal outputted from the servo error signal calculating means.

In the information recording / reproducing apparatus as described above, the first light receiving means and the second light receiving means are shared, and the light receiving means emits light when any of the two light sources is irradiated. A plurality of light receiving means for receiving the reflected light from the information recording medium and outputting the light receiving signal may be provided, and the light receiving signal output from the light receiving means may be input to each of the variable gain amplifying means. .

Further, in the information recording / reproducing apparatus as described above, the gain calculation setting means calculates the gain at the time of reproduction and the gain at the time of recording, wherein the gain at the time of reproduction and the gain at the time of recording are calculated. It is preferable that the apparatus further comprises gain selection means for selecting a gain in accordance with a recording / reproduction switching signal, and means for performing the setting based on the gain output from the gain selection means.

In the information recording / reproducing apparatus as described above, the peak hold means may be provided with means for changing a discharge time constant according to the light source selection signal and the linear velocity. Further, in the information recording / reproducing apparatus as described above, when calculating the gain based on the peak level signal output from the peak hold means, the signal band of the signal input to the peak hold means is a discharge time constant of the peak hold means. It is preferable to control the linear velocity so as to substantially coincide with a predetermined value determined based on the linear velocity.

In the information recording / reproducing apparatus as described above, the gain calculation setting means detects the value of the peak level of the input signal when the objective lens is moved in the vertical direction of the information recording medium. Means for calculating the gain according to the peak level value may be provided. Further, in the information recording / reproducing apparatus as described above, the gain calculation setting means may include a predetermined gain irradiating light amount for moving the objective lens in the vertical direction of the information recording medium to obtain a peak level of a light receiving signal. The gain is calculated based on the peak level value, and the gain at the time of reproduction and recording is calculated based on the gain, the irradiation light amount for the predetermined gain calculation, and the irradiation light amount at the time of reproduction and recording. A means for calculating may be provided.

In the information recording / reproducing apparatus as described above, the gain calculation setting means is provided with means for calculating the gain at the time of reproduction or recording each time the irradiation light quantity at the time of reproduction or recording is changed. Good. Further, in the information recording / reproducing apparatus as described above, the one light source is C
The light source for D is preferably used, and the other light source is preferably a light source for DVD.

[0028]

Embodiments of the present invention will be specifically described below with reference to the drawings. First, a first embodiment of the present invention will be described. FIG. 1 is a block diagram showing a configuration of a focus error signal generation section and a track error signal generation section of a main part of a focus servo and track servo mechanism in an information recording / reproducing apparatus according to a first embodiment of the present invention. As shown in FIG. 1, the four-divided light receiving element 1 emits an optical disk (for example, a CD-R) when one of two light sources (here, a light source for CD) is irradiated with light.
OM, CD-R, CD-RW and other information recording media), and the four divided light receiving elements 1a, 1b, 1c, and 1d receive light receiving signals SA1, SB1 respectively. , SC1, SD1 are output. That is, it corresponds to the first light receiving means according to the first aspect.

The four-division light receiving element 2 emits an optical disk (for example, DVD-RO) when the other one of the two light sources (here, the light source for DVD) is irradiated with light.
Information recording media such as M, DVD-R, DVD-RAM)
The four divided light receiving elements 2a, 2b, 2c, and 2d output light receiving signals SA2, SB2, SC2, and SD2, respectively. That is, it corresponds to the second light receiving means according to the first aspect.

The selector 3a outputs a light source selection signal SEL indicating which one of the two light sources emits light.
And selectively outputs the light receiving signal SA1 or the light receiving signal SA2. Similarly, the selectors 3b to 3d selectively output the light receiving signals SB1 to SD1 or the light receiving signals SB2 to SD2, respectively. That is, it corresponds to a plurality of selecting means according to the first aspect. One of the light receiving signals of the respective light receiving elements output from the four-divided light receiving element 1 or 2 is made valid by the selectors 3a to 3d, and the subsequent circuits are commonly used.

Variable gain amplifiers 4a, 4b, 4c and 4d
Varies the gain according to the input gain control signal, and amplifies (or attenuates) each of the light receiving signals SA, SB, SC and SD selected by the selectors 3a to 3d.
That is, it corresponds to a plurality of variable gain amplifying means according to the first aspect. The amplification rate (or attenuation rate) is set as an input gain G1, and the light receiving signals output from the respective variable gain amplifiers 4a to 4d are respectively VA, VB, VC, V
Assuming that D, for example, the light receiving signal VA can be obtained by an arithmetic process based on the following Expression 5. Other light receiving signal V
B, VC, and VD can also be obtained by arithmetic processing based on similar numbers.

[0032]

## EQU5 ## VA = G1 · SA

The sum signal operation circuit 5 is provided with light receiving signals VA, VB, VC, V output from the respective variable gain amplifiers 4a to 4d.
It generates and outputs a light receiving sum signal SUM to which D is added.
That is, it corresponds to the light receiving sum signal generating means according to the first aspect. The received light sum signal SUM is generated by an arithmetic process based on the following equation (6).

[0034]

SUM = VA + VB + VC + VD

The focus error signal calculation circuit 6 generates and outputs a focus error signal FE from the light receiving signals VA to VD. Here, it is assumed that both the CD and DVD are generated by the astigmatism method, and the focus error signal FE is generated by an arithmetic processing based on the following equation (7).

[0036]

FE = (VA + VC)-(VB + VD)

The track error signal calculation circuit 7 generates a track error signal TE from the light receiving signals VA to VD.
Here, it is assumed that both the CD and DVD are generated by the push-pull method, and the track error signal TE is generated by the arithmetic processing based on the following equation (8).

[0038]

## EQU8 ## TE = (VA + VB)-(VC + VD)

That is, the focus error signal operation circuit 6 and the track error signal operation circuit 7 fulfill the function of the servo error signal operation means of the first aspect.
The variable gain amplifier 8 amplifies the received light total signal SUM based on the gain control signal Sgain, and outputs SUMn. Assuming that the amplification factor is G2, SUMn is obtained by an arithmetic process based on the following equation (9).

[0040]

SUMn = G2 · SUM

The gain control unit 11 controls the gain of the variable gain amplifier 8 so that the DC component of SUMn always becomes a predetermined value, and outputs a gain control signal Sgain. That is, the variable gain amplifier 8
An AGC circuit is constituted by the gain control unit 11 and performs the function of the gain calculation setting unit according to the first aspect.
Assuming that a predetermined value for controlling the SUMn is k, the gain G2 of each of the variable gain amplifiers 4a to 4d can be obtained by an arithmetic process based on the following equation (10).
The amplification rate (gain) G2 changes with the change of M.

[0042]

G2 = k / SUM = k / (VA + VB + VC + VD)

The variable gain amplifiers 9 and 10 are substantially the same as the variable gain amplifier 8, and each of which controls the focus error signal FE and the track error signal TE to a gain control signal S
Amplify based on gain (each output is FE
n, TEn). Since the amplification factor at this time is G2, which is equivalent to that of the variable gain amplifier 8, FEn and TEn can be obtained by the following Expressions 11 and 12, respectively, and each servo error signal is generated according to the fluctuation of the light receiving sum signal SUM. The gain is automatically controlled.

[0044]

## EQU11 ## FEn = G2.FE = kFE / SUM

[0045]

## EQU12 ## TEn = G2.TE = kTE / SUM

From the above equations (11) and (12), it can be seen that this configuration is equivalent to that of the division circuit. Therefore, the AGC function may be performed by a division circuit instead of the variable gain amplifiers 9 and 10. The setting gain calculator 12 calculates an input gain control signal for setting the gain of the variable gain amplifiers 4a to 4d, and calculates a gain according to the sum signal SUM. That is, it corresponds to the automatic gain control means according to the first aspect.

As described above, the light receiving signal fluctuates greatly due to fluctuations in the reflectivity of the disk. The light reception signal fluctuation factors are roughly classified as follows. (First light receiving signal fluctuation factor) First, the amount of change in disk reflectivity (this coefficient is α), such as disc type, difference in reflectivity by manufacturer, lot variation, in-plane variation, etc. In the case of a recording disk, the unrecorded area and the recorded area are different.

(Second light reception signal variation factor) Secondly, there is a variation component unique to the optical disk device (this coefficient is β). Usually, each parameter of the servo system is not set for each device, but is set according to a predetermined design value.
Therefore, if the device varies from the design value, the servo gain will fluctuate, causing a servo operation to become unstable. This includes variations in the conversion efficiency of the light receiving element, variations in the current-voltage conversion coefficient when converting to a light receiving signal (variations in the normal resistance value), and variations in the return path efficiency until the reflected light from the optical disk enters the light receiving element. is there.

When the reflected light from different light sources is received by different light receiving elements to generate a light receiving signal as in the first embodiment, the conversion efficiency of the light receiving element, the current-voltage conversion coefficient, the return path efficiency Due to such differences, the design center value may be originally different. In some cases, it is possible to design the light receiving signal levels to be substantially equal. However, the degree of freedom in designing is reduced, which may lead to an increase in cost and an increase in the number of information recording / reproducing devices.

(Third light receiving signal variation factor) The third factor is a change in laser power applied to the optical disk (this coefficient is represented by p). Assuming that the light receiving signal changed by each of these fluctuation factors is SA ', SA' = αβp · SA. The same applies to other light receiving signals. Further, assuming that the sum signal of received light changed by each variation factor is SUM ', it can be obtained by the arithmetic processing based on the following equation (3).

[0051]

SUM ′ = αβp · (SA + SB + SC + S
D) = αβp · SUM

At this time, the light receiving signal VA output from the variable gain amplifier 4a is given by VA = G1 · SA ′ = G1 · αβp ·
SA. Here, the gain G1 is αβ which is a variation factor.
The light receiving signal VA is determined to be substantially a predetermined value by absorbing p. Similarly, the light receiving signals VB to VD have substantially the same predetermined value, so that the light receiving sum signal SUM does not depend on various fluctuations. Therefore, even if each of the arithmetic circuits and the AGC circuit in the subsequent stage are shared, the dynamic range can be reduced, and the circuit can be realized with a simple circuit configuration.

The gain G1 is set for the purpose of suppressing the dynamic range of the subsequent stage to be low. Therefore, the gain G1 does not need to be precisely adjusted to a predetermined value, but may be set within a certain range. The gain setting resolution and accuracy of 4a to 4d are not so required, and a simple circuit configuration is sufficient. Further, the variation coefficient β unique to the information recording / reproducing apparatus is substantially fixed during the recording / reproducing operation, and the variation α of the disk reflectance is also substantially fixed for each optical disk, and the in-plane variation is not usually large. Therefore,
Even if the gain G1 is set only once after the disc is inserted, the light receiving signal VA for recording / reproducing on the optical disc is set.
.About.VD do not fluctuate greatly, so that the effects of the present invention can be sufficiently obtained.

Next, the operation of the set gain calculator 12 for setting the input gain G1 will be described. The received light sum signal SUM can be obtained by an arithmetic processing based on the following Expression 14 based on the above Expressions 5 and 6, and the input gain G1 detects a DC component of the received light total signal SUM so that it is within a predetermined range. To decide.

[0055]

SUM = G1 · (SA + SB + SC + SD)
= G1 · Ssum

In the following description, it is assumed that the received light sum signal SUM of Expression 14 is a direct current component of the received light sum signal SUM. Here, the input gain G1 is calculated based on the value at the time when the total light reception signal SUM is in focus. When the input gain G1 is not properly set, the focus servo operation becomes unstable, and the received light total signal SUM at the time of focusing may be incorrectly detected. Is moved in the vertical direction (up and down) of the optical disk, the peak value of the total light reception signal SUM at that time is detected, and the input gain G1 is calculated based on the peak value.

That is, as described in claim 8, the setting gain calculating section 12 detects the value of the peak level of the input signal when the objective lens is moved in the vertical direction of the information recording medium, and detects the peak level. The gain is calculated according to the level value. When detecting the peak value, the input gain G1 may be set to a predetermined value (for example, a minimum gain value), and the input gain may be calculated so that the light reception sum signal SUM becomes a predetermined value. The input gain can be calculated more accurately by setting the input gain G1 calculated in this way, moving the objective lens up and down again, detecting the peak value of the sum signal SUM, and calculating the input gain.

Next, in the case of a recordable optical disk,
An unrecorded area and a recorded area may be mixed. The DC component of the received light sum signal is different between the unrecorded area and the recorded area (the recorded area has a lower level), and in the input gain calculation method in the first embodiment, the input gain calculated value depends on the measurement location. May be different.

Therefore, the second embodiment solves the problem in such a case. FIG. 2 is a block diagram showing a configuration of a focus error signal generator and a track error signal generator according to the second embodiment of the present invention. 1 are given the same reference numerals. As shown in FIG. 2, the focus error signal generator and the track error signal generator further include a peak hold circuit 20 for detecting a peak level value of the light reception sum signal SUM in addition to the components shown in FIG. And the peak hold circuit 20
Hold signal Spk indicating the peak level value from
The input gain G1 is calculated according to the following. That is, the peak hold circuit 20 corresponds to the peak hold means according to the second aspect, and the set gain calculating section 12 shown in FIG. 2 fulfills the function of the gain calculation setting means according to the second aspect.

Here, the peak hold circuit 20 is used when the polarity of the light reception sum signal SUM is high when the light reception amount is large. If the polarity is reversed, a bottom hold circuit may be used instead. Since the peak hold signal Spk of the received light sum signal SUM has almost no difference between the unrecorded area and the recorded area, the input gain is based on the peak hold signal Spk of the received light sum signal SUM as in the second embodiment. If G1 is calculated,
The same input gain can be calculated regardless of the measurement location.

In the second embodiment, the sum signal S
In order to accurately detect the UM peak hold signal Spk, the sum signal operation circuit 5 and the variable gain amplifier 4a
4d need to be a broadband circuit that allows a reproduced signal to pass through, and usually, a wideband circuit requires an increase in circuit scale and an increase in chip size of an integrated circuit. On the other hand, since other servo error signals do not require a wide band signal, it is useless to widen the band only for detecting the peak hold signal Spk.

Then, the third point, which takes the above points into account, will now be described.
An embodiment will be described. FIG. 3 shows a third embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a focus error signal generation unit and a track error signal generation unit according to the embodiment. Figure 1
Alternatively, parts common to those in FIG. 2 are denoted by the same reference numerals. As shown in FIG. 3, the focus error signal generation unit and the track error signal generation unit include, in addition to the components shown in FIG. 1, an addition operation circuit 30 for adding the light receiving signals SA to SD, and an addition operation circuit. A variable gain amplifier 31 for amplifying the addition signal output from the variable gain amplifier 30;
A new peak hold circuit 32 for detecting the peak level value of the added signal output from 1 is newly provided, and the processing in the set gain calculator 12 is different from that described above.

That is, the addition operation circuit 30 fulfills the function of the addition operation means of the third aspect, the variable gain amplifier 31 fulfills the function of the addition signal variable gain amplification means of the third aspect, and Hold circuit 32
Performs the function of the peak hold means of the third aspect. In the third embodiment, the circuits that need to be widened are the addition operation circuit 30 and the variable gain amplifier 31. Usually, the circuits equivalent to the addition operation circuit 30 for generating the reproduction signal are provided. Only a few circuits need to be widened. Further, the variable gain amplifier 31 varies the gain in accordance with the second input gain control signal.

The second input gain control signal may be the same as the input gain control signal for setting the gains of the variable gain amplifiers 4a to 4d, or may have a fixed amount increased or decreased according to the gain of the addition operation circuit 30. Good. Further, as shown in FIG. 4, instead of the addition operation circuit 30, the light receiving signal S
A first addition operation circuit 3 for adding each signal of A1 to SD1
0a, two addition operation circuits of a second addition operation circuit 30b for adding each signal of the light receiving signals SA2 to SD2, and an addition signal or a second signal output from the first addition operation circuit 30a according to the light source selection signal SEL. Addition operation circuit 30b
And a selector 33 that selects and outputs any one of the addition signals output from the selector 33, and the addition signal output from the selector 33 may be input to the variable gain amplifier 31.

That is, as described in claim 5, the addition operation circuit 30 is composed of two addition operation circuits for calculating a gain at the time of reproduction and a gain at the time of recording. It is preferable to include a gain selection unit that selects and outputs one of a gain at the time of reproduction and a gain at the time of recording from the circuit, and a unit that performs the setting based on the gain output from the gain selection unit. . With this configuration, even when an addition operation circuit for generating a reproduction signal is separately provided, the circuit can be effectively shared.

As described in the ninth aspect, the value of the peak level of the light receiving signal when the objective lens is moved in the vertical direction of the information recording medium with the predetermined amount of light for gain calculation is detected. The gain is calculated based on the value of the peak level, and the gain at the time of reproduction and at the time of recording is calculated based on the gain, the irradiation light amount for the predetermined gain calculation, and the irradiation light amount at the time of reproduction and recording. Good.

Next, when the signal band of the reproduction signal is different, such as a CD and a DVD, the discharge time constant of the above-described peak hold circuit 20 or 32 may not be appropriate for one of the reproduction signals. As shown in b), the peak hold signal (peak value) may not be detected accurately. In such a case, the peak hold circuit 20 or 32 is provided with means for changing the discharge time constant according to the light source selection signal and the linear velocity. To change the discharge time constant, for example, the discharge current to the hold capacitor may be changed.

Further, the signal band of the reproduction signal changes according to the reproduction speed (linear speed). Therefore, it is more preferable to change the discharge time constant according to the linear velocity. Further, by changing the linear velocity, the signal band of the reproduced signal can be made substantially the same. That is, as described in claim 7,
When calculating the gain based on the peak level signal output from the peak hold circuit, the linear velocity is set so that the signal band of the signal input to the peak hold circuit substantially matches a predetermined value determined based on the discharge time constant of the peak hold circuit. Take control. For example, in the case of CD and DVD, CD
If the linear velocity is approximately twice as high as that of DVD, the signal band becomes almost the same. When the peak value is detected by the peak hold circuit 20 or 32 for calculating the input gain, if the linear velocity is changed in this way, the peak value can be accurately detected even when the discharge time constant is fixed.

Next, generally, the laser power (reproduction power) irradiated during reproduction and the laser power (recording power) during recording differ greatly. That is, the above-described third light receiving signal variation factor has a large effect. Since the recording laser power differs depending on the optical disk, it is desirable to set the gain for each optical disk. In other words, switching of the conversion gain in the current-to-voltage conversion unit of the light receiving signal which has been conventionally used may not be sufficient. Also,
The fluctuation of the received light signal due to the laser power change at the switching point of reproduction / recording fluctuates more rapidly than other factors, so that the servo gain cannot be stabilized by the AGC circuit and the servo operation becomes unstable. is there.

Therefore, the fourth embodiment solves the problem in such a case. FIG. 5 is a block diagram showing a configuration of a focus error signal generator and a track error signal generator according to the fourth embodiment of the present invention. 1 to 3 are denoted by the same reference numerals. As shown in FIG. 5, the set gain calculator 40 calculates the input gains of the variable gain amplifiers 4a to 4d in accordance with the received light sum signal SUM, similarly to the set gain calculator 12 shown in FIG. A time input gain control signal and a recording input gain control signal are generated and output to the selector 41. That is, the set gain calculating section 40 fulfills the function of the means described in the tenth aspect. The input gain control signal at the time of reproduction may be obtained by calculating the input gain in the same manner as described above, and the input gain control signal at the time of recording is calculated from the input gain at the time of reproduction as described later.

The selector 41 outputs a reproduction / recording switching signal WG
The input gain control signal at the time of reproduction and the input gain control signal at the time of recording are switched in accordance with the following.
Set as an input gain of 4d. Other parts are shown in Fig. 1.
Performs the same function as. Since the input gain is switched instantaneously in the fourth embodiment, the light receiving signal VA
The signals V.about.VD do not change abruptly even at the time of switching between recording and reproduction, and the servo gain is stabilized.

Next, a method of calculating the recording input gain Gw will be described. The input gain Gr during reproduction is calculated in the same manner as the input gain G1 described above. The received light sum signal is proportional to the laser power, and other fluctuation factors such as the disk reflectivity do not depend on the laser power. Therefore, if the laser power during reproduction is Pr and the average laser power during recording is Pw, the following equation is obtained. 15 can be calculated.

[0073]

Gw = Gr · Pr / Pw

Note that, in the second embodiment shown in FIG. 2, the same effects as described above can be obtained by making the same as in FIG.

Up to the above embodiments, the embodiments in which the disc reflected light emitted from the two light sources is received by separate light receiving elements have been described. Next, an embodiment will be described in which the disk reflected light emitted from two light sources is received by one light receiving element. Even when one light receiving element receives the irradiation light of the two types of light sources, there is a large variation due to the above-mentioned fluctuation factors of the light receiving signal. That is, the change in the first disk reflectance varies depending on the disk on which the recording and reproduction are performed, and similarly changes.

Regarding the variation component unique to the second optical disk device, the conversion efficiency and the current-voltage conversion coefficient of the shared light receiving element are common, but the variation component itself exists, and the return path efficiency composes the optical pickup. In many cases, it differs depending on the wavelength dependence of the optical element to be used. Also,
The conversion efficiency of the light receiving element may also vary depending on the wavelength dependence. A change in the laser power applied to the third optical disk also occurs. Therefore, the light receiving signal level may be greatly different, and it may be difficult to realize the signal arithmetic circuit and the AGC circuit in common, as described above, or the circuit scale may become very large.

Then, the fifth point which takes the above points into account is next described.
An embodiment will be described. FIG. 6 shows a fifth embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a focus error signal generation unit and a track error signal generation unit according to the embodiment. Figure 1
3 or FIG. 5 are denoted by the same reference numerals. As shown in FIG. 6, the quadrant light receiving element 50 receives the disk reflected light with respect to the light emitted from both of the two light sources, and outputs respective light receiving signals SA to SD. The variable gain amplifiers 4a to 4d receive the light receiving signals SA to SD and amplify them according to the input gain control signal, and perform the same functions as those shown in FIG. The other blocks also perform the same functions as in FIG.

That is, as described in the fourth aspect, the four-divided light receiving element 50 shares the first light receiving means and the second light receiving means, and any one of the two light sources emits light. In some cases, a plurality of light receiving means for receiving the reflected light from the information recording medium and outputting the light receiving signal are provided, and the light receiving signals output from the light receiving means are respectively input to the variable gain amplifiers 4a to 4d. It is configured as follows. Here, the signal levels of the light receiving signals SA to SD change depending on which light source is irradiating. As described in the above embodiment, the input gain G1 when each light source irradiates is determined and set. What is necessary is just to make the gain calculation part 12 output the input gain control signal calculated according to which light source irradiates. Also, FIGS. 2, 3
Similar effects can be obtained by making similar changes in the focus error signal generator and the track error signal generator of each embodiment shown in FIG.

Further, in recording on the same disk,
When changing the recording laser power, the recording gain may be calculated again based on the above Equation 15 according to the recording laser power, and set as the recording input gain. For example,
When recording is performed while changing the recording linear velocity, the optimum recording power may be different due to the characteristics of the recording medium. In such a case, the recording gain may be reset. In addition, on an optical disc that can be normally recorded, recording is performed while sequentially changing the recording laser power in a predetermined test writing area, and the optimum recording power of the optical disc is calculated (referred to as OPC).
Perform the operation.

This embodiment is a preferred example during such an OPC operation, and a stable servo operation can be performed even during the OPC operation. Further, during reproduction, the irradiation light amount may be changed according to the reproduction speed. When the irradiation light amount at the time of reproduction is changed as described above, the reproduction gain may be calculated and set according to the reproduction power.

In the above description, the generation of the focus error signal by the astigmatism method and the generation of the track error signal by the push-pull method have been described. The invention can be applied. Further, when the servo error signal generation method differs depending on the light source, an arithmetic circuit may be provided and selected.

According to the function of the first embodiment of the present invention, there are provided a plurality of variable gain amplifying means for selecting the light receiving signals of the two light sources and amplifying the selected signals, the output of which is substantially equal to a predetermined value. The gain is calculated and set based on the total light reception signal so that the servo error signal is generated and the automatic gain control is performed based on the output signal from the variable gain amplifying means. Even at the time of recording / reproducing various kinds of optical discs, it corrects the fluctuation of the servo gain, and furthermore, the component A
The GC circuit and each signal operation circuit can be realized with a simple configuration and in common.

Further, according to the function of the second aspect of the present invention, a plurality of variable gain amplifying means for selecting and amplifying the light receiving signals of the two light sources are provided, and the output thereof becomes substantially a predetermined value. As described above, the gain is calculated and set based on the peak hold detection signal of the received light sum signal, and the generation of the servo error signal and the automatic gain control are performed based on the output signal from the variable gain amplifying means. In addition to the effect equivalent to the function, the same gain can be calculated irrespective of the measurement location even on an optical disc in which the DC component of the received light sum signal differs depending on the location, such as when the unrecorded area and the recorded area are mixed. it can.

Further, according to the function of the third aspect of the present invention, a plurality of first variable gain amplifying means for selecting and amplifying light receiving signals of two light sources, and each light receiving signal of the light receiving means. Addition operation means for adding element outputs, second variable gain amplification means for amplifying an output signal from the addition operation means, and peak hold means for detecting the peak level of the second variable gain amplification signal The gain is calculated and set based on the peak hold detection signal, and the generation of the servo error signal and the automatic gain control are performed based on the output signal from the variable gain amplifying means. In addition to the effect, the number of circuits that need to be widened to perform peak hold detection with high accuracy is small, and the circuit scale and the chip size of the integrated circuit can be reduced.

According to the function of the fourth aspect of the present invention, even when an optical pickup in which the disk reflected light of two light sources is received by one light receiving means is used, the AGC circuit and each signal arithmetic circuit are used. Can be realized with a simple configuration and in common, and the same effects as the functions according to the above-described claims 1 to 3 can be obtained.

Further, according to the function of claim 5 of the present invention, the gain for reproduction and the gain for recording are divided into means for calculating the gain for reproduction and the gain for recording, respectively. Since the selection is set in accordance with the signal, the servo gain can be corrected even at the switching between recording and reproduction where the light receiving signal largely and rapidly fluctuates due to a large difference in the irradiation light amount, and a stable servo operation can be performed.

According to the function of claim 6 of the present invention, since the discharge time constant of the peak hold circuit changes in accordance with the light source selection signal and the linear velocity, an accurate peak value can be obtained even when the signal band of the reproduction signal is different. Can be detected, and an accurate input gain setting can be performed.

Further, according to the function according to claim 7 of the present invention, when calculating the gain based on the output signal from the peak hold circuit, the signal band of the signal input to the peak hold circuit is determined by the discharge time constant of the peak hold circuit. Since the linear velocity is controlled to almost match the predetermined value determined,
Even if the discharge time constant is fixed, the peak value can be detected accurately, and the input gain can be set accurately.

Further, according to the function according to claim 8 of the present invention, the peak value of the input signal when the objective lens is moved in the vertical direction of the optical disk is detected, and the gain is calculated according to the peak value. Even when the gain calculation is not properly set, the total signal value at the time of focusing can be detected without performing the focus servo operation, and the accurate gain can be calculated.

Further, according to the function of the ninth aspect of the present invention, the peak value of the light receiving signal when the objective lens is moved in the vertical direction of the information recording medium with the predetermined irradiation light quantity for gain detection is detected. Since the gain at the time of reproduction and at the time of recording is calculated from the gain calculated according to the peak value and the irradiation light amount for the predetermined gain calculation and the irradiation light amount at the time of reproduction and at the time of recording, the gain at the time of reproduction can be accurately calculated. The gain at the time of recording can be calculated without performing irradiation at the recording power.

According to the function of claim 10 of the present invention, the gain is calculated each time the irradiation light amount is changed during reproduction or recording, so that the reproduction power or the recording power is changed according to the linear velocity. A stable servo operation can be performed even in the case where the irradiation light amount at the time of recording is frequently changed such as during the OPC operation.

Further, according to the function according to the eleventh aspect of the present invention, the effects of the functions according to the first to tenth aspects can be obtained in a recording / reproducing apparatus for CD and DVD.

The present invention can be applied to all recording / reproducing optical disk devices such as a CD-ROM drive device, a CD-R drive device, a CD-RW drive device, a DVD-ROM drive device and a DVD-R drive device. In particular, an optical disk device capable of handling a plurality of these is more suitable.

[0094]

As described above, according to the information recording / reproducing apparatus of the present invention, when recording / reproducing information on / from an information recording medium using light sources of different wavelengths, the disc reflectivity, the optimum recording laser power, etc. The present invention corrects fluctuations in servo gain even when recording / reproducing a variety of information recording media having a large difference in data, and realizes a simple and common circuit configuration of its components such as an AGC circuit and each signal operation circuit. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a focus error signal generation unit and a track error signal generation unit of a main part of an information recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a focus error signal generator and a track error signal generator according to a second embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a focus error signal generator and a track error signal generator according to a third embodiment of the present invention.

FIG. 4 is a block diagram illustrating an example of an internal configuration of an addition operation circuit illustrated in FIG. 3;

FIG. 5 is a block diagram showing a configuration of a focus error signal generator and a track error signal generator according to a fourth embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a focus error signal generator and a track error signal generator according to a fifth embodiment of the present invention.

FIG. 7 is a waveform chart for explaining detection of a peak value;

FIG. 8 is a block diagram illustrating a configuration example of a focus error signal generation unit of a focus servo mechanism in a conventional optical disc device.

[Explanation of symbols]

1, 2, 50, 100: four-division light receiving element 1a to 1d, 2a to 2d, 100a to 100d: light receiving element 3a to 3d, 33, 41: selector 4a to 4d, 8 to 10, 31, 103, 104: variable Gain amplifier 5, 102: Sum signal operation circuit 6, 101: FE signal operation circuit 7, TE signal operation circuit 11, 105: Gain control section 12, 40: Set gain calculation section 20, 32: Peak hold circuit 30: Addition operation Circuit 30a: First addition operation circuit 30b: Second addition operation circuit

Claims (11)

[Claims] 1. A first light receiving device comprising: two light sources; and a plurality of first light receiving units for receiving reflected light from an information recording medium when the one of the two light sources irradiates light and outputting a received light signal. Means, a plurality of second light receiving means for receiving the reflected light from the information recording medium at the time of light irradiation by the other light source of the two light sources, and outputting a light receiving signal thereof, The light receiving signal output from each of the first light receiving means and the light receiving signal output from each of the second light receiving means corresponding to each of the first light receiving means according to a light source selection signal indicating which of the light sources emits light. A plurality of selecting means for respectively selecting and outputting one of the received light signals; a plurality of variable gain amplifying means for respectively amplifying the received light signal output from each of the selecting means; and each of the variable gain amplifiers Out of the means Servo error signal calculating means for calculating and outputting a servo error signal based on the plurality of received light signals, and receiving light sum signal generation for generating a received light sum signal based on the plurality of received light signals output from each of the variable gain amplifying means. Means, gain calculation setting means for calculating and setting the gain of each of the variable gain amplifying means based on the received light sum signal generated by the received light sum signal generation means, and the received light sum signal generated by the received light sum signal generation means And an automatic gain control means for automatically controlling the gain of the servo error signal output from the servo error signal calculation means based on the information. 2. A first light receiving device comprising: two light sources; and a plurality of first light receiving units for receiving reflected light from an information recording medium when the light is irradiated by one of the two light sources and outputting a light receiving signal. Means, a plurality of second light receiving means for receiving the reflected light from the information recording medium at the time of light irradiation by the other light source of the two light sources, and outputting a light receiving signal thereof, The light receiving signal output from each of the first light receiving means and the light receiving signal output from each of the second light receiving means corresponding to each of the first light receiving means according to a light source selection signal indicating which of the light sources emits light. A plurality of selecting means for respectively selecting and outputting one of the received light signals; a plurality of variable gain amplifying means for respectively amplifying the received light signal output from each of the selecting means; and each of the variable gain amplifiers Out of the means Servo error signal calculating means for calculating and outputting a servo error signal based on the plurality of received light signals, and a received light sum signal generating means for generating a received light sum signal based on the plurality of received light signals output from the respective variable gain amplifying means Means, peak hold means for detecting and outputting a peak level of the received light sum signal generated by the received light sum signal generation means, and each of the variable gain amplifiers based on the peak level signal output from the peak hold means. Gain calculation setting means for calculating and setting the gain of the means; and automatic gain for automatically controlling the gain of the servo error signal output from the servo error signal calculation means based on the total light reception signal generated by the total light reception signal generation means. An information recording / reproducing apparatus, comprising: a control unit. 3. A first light receiving device comprising: two light sources; and a plurality of first light receiving units for receiving reflected light from an information recording medium when light is irradiated by one of the two light sources and outputting a light receiving signal. Means, a plurality of second light receiving means for receiving the reflected light from the information recording medium at the time of light irradiation by the other light source of the two light sources, and outputting a light receiving signal thereof, The light receiving signal output from each of the first light receiving means and the light receiving signal output from each of the second light receiving means corresponding to each of the first light receiving means according to a light source selection signal indicating which of the light sources emits light. A plurality of selecting means for respectively selecting and outputting one of the received light signals; a plurality of variable gain amplifying means for respectively amplifying the received light signal output from each of the selecting means; and each of the variable gain amplifiers Out of the means Servo error signal calculating means for calculating and outputting a servo error signal based on the plurality of received light signals, and receiving light sum signal generation for generating a received light sum signal based on the plurality of received light signals output from each of the variable gain amplifying means. Means, addition operation means for adding the light receiving signals output from the selection means and outputting the added signal, and addition signal variable gain amplification means for amplifying the addition signal output from the addition operation means, Peak holding means for detecting and outputting the peak level of the addition signal output from the addition signal variable gain amplification means; and each of the variable gain amplification means based on the peak level signal output from the peak holding means; Gain calculation setting means for calculating and setting the respective gains of the addition signal variable gain amplifying means; An information recording / reproducing apparatus, comprising: automatic gain control means for automatically controlling the gain of the servo error signal output from the servo error signal calculation means based on the generated light receiving sum signal. 4. The information recording / reproducing apparatus according to claim 1, wherein the first light receiving means and the second light receiving means are shared, and wherein the two light sources are provided. A light receiving means comprising a plurality of light receiving means for receiving the reflected light from the information recording medium and outputting the light receiving signal at the time of any light irradiation, and receiving the light receiving signal output from the light receiving means with each of the variable gains. An information recording / reproducing apparatus characterized in that an input is made to an amplifying means. 5. The information recording / reproducing apparatus according to claim 1, wherein said gain calculation setting means calculates a gain at the time of reproduction and a gain at the time of recording. Information comprising: gain selection means for selecting a gain at the time of reproduction and a gain at the time of recording in accordance with a recording / reproduction switching signal; and means for making the setting based on the gain output from the gain selection means. Recording and playback device. 6. The information recording / reproducing apparatus according to claim 2, wherein said peak hold means includes means for changing a discharge time constant according to said light source selection signal and a linear velocity. apparatus. 7. The information recording / reproducing apparatus according to claim 2, wherein a signal band of a signal input to the peak hold unit is set to a peak when calculating a gain based on a peak-level signal output from the peak hold unit. An information recording / reproducing apparatus wherein the linear velocity is controlled so as to substantially coincide with a predetermined value determined based on a discharge time constant of the holding means. 8. The information recording / reproducing apparatus according to claim 1, wherein the gain calculation setting means includes an input signal for moving an objective lens in a direction perpendicular to the information recording medium. An information recording / reproducing apparatus comprising: means for detecting a peak level value and calculating a gain according to the peak level value. 9. The information recording / reproducing apparatus according to claim 5, wherein the gain calculation setting means is provided with a light reception signal when the objective lens is moved in a vertical direction of the information recording medium with a predetermined light quantity for gain calculation. The peak level value is detected and the gain is calculated based on the peak level value. Based on the gain, the irradiation light amount for calculating a predetermined gain, and the irradiation light amount during reproduction and recording, the reproduction time and the recording time are used. An information recording / reproducing apparatus comprising means for calculating a time gain. 10. The information recording / reproducing apparatus according to claim 9, wherein the gain calculation setting means includes means for calculating the gain at the time of reproduction or recording each time the irradiation light amount at the time of reproduction or recording is changed. An information recording / reproducing apparatus characterized in that: 11. The information recording / reproducing apparatus according to claim 1, wherein the one light source is a light source for a CD, and the other light source is a light source for a DVD. Information recording and playback device.