JP2003217136A - Track cross signal producing circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a track cross signal having the amplitude similar to that of an already recorded area even on an unrecorded are of a disk, in a track cross signal producing circuit. <P>SOLUTION: This circuit is provided with: an area discriminating circuit 50 for discriminating whether the reproducing position resides in the already recorded area or the unrecorded area; and a variable gain amplifier 5 for outputting a track cross signal 107 by means that a difference signal 103 from a 1st integrator 2 is made to be the input and a gain is controlled with a negative coefficient in accordance with a sum signal 105 from a 2nd integrator 4 and an area discriminated by the area discriminating circuit. The gain of the variable gain amplifier in the unrecorded are is made higher than that of the already recorded area. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track cross signal generation circuit provided for track search in an optical disc system.

[0002]

2. Description of the Related Art Generally, in an optical disk system, it is necessary to seek a track to search for a desired track. The track seek method is roughly classified into a direct search and an indirect search. Among them, the track cross signal must be accurately counted for the direct search with excellent performance.

Further, in the optical disc system, it is highly necessary to record / reproduce different types of discs.

Generally, the reflectivity of a write-once disc such as a CD-RW is about 1/4 to 1/10 of the reflectivity of a recordable disc such as a CD-R or a CD-ROM because of its physical properties.
Significantly low. As a result, the reflected light obtained when the disk is irradiated with the laser having the same power becomes different according to the ratio of the reflectances. Even for the same type of disc, the reflectance varies depending on the storage environment.

The optical disc system extracts information contained in the optical disc by converting and processing the reflected light into an electric signal. The track cross signal is no exception, and the signal quality changes due to the difference in reflectance, making it impossible to perform accurate track counting.

To solve this problem, a means for keeping the reflected light constant by changing the power of the laser and changing the amount of light to be applied is also taken, but it is particularly large for write-once discs. The irradiation of light quantity adversely affects the number of times of rewriting. Therefore, a means for correcting the signal level is generally used in the signal processing circuit while keeping the irradiation light amount constant.

A conventional track cross signal generation circuit using the differential push-pull method which is generally used in the optical disc system for recording on a CD-R, a CD-RW, etc. is shown in FIG. Composed.

In FIG. 11, a first addition signal 101 obtained by receiving the reflected light from the main beam and a second addition signal 10 obtained by receiving the reflected light from the sub-beam.
The difference signal 103 with respect to 2 is generated by the subtractor 1, and the difference signal 1
The track cross original signal 104 is obtained by removing high-frequency noise components, such as the RF signal component included in 03, which are unnecessary as a track cross signal by the first integrator 2.
Is obtained.

Here, the main beam is a beam applied to the groove track in a state where it is accurately tracked so that recorded information can be extracted.
The sub-beam refers to a beam which is similarly applied to the land track, and these are usually arranged at the same intervals as the respective track widths.

The reflected light amount detection circuit 1000 includes an adder 3 for obtaining a sum signal 105 by adding the first addition signal 101 and the second addition signal 102, and a second integrator 4 for integrating the sum signal 105. Composed of and. The reflected light amount detection signal 106 is an output signal of the second integrator 4.

The variable gain amplifier 5 is constructed such that the reflected light amount detection signal 106 is used as a control voltage, and the gain has a negative coefficient with respect to this control voltage. Cross signal 10
Get 7.

Next, when the conventional track cross signal generation circuit having the above-described structure is used to perform a track seek in a pre-recorded area of a disc having a pre-groove such as a CD-R or a CD-RW. The operation will be described with reference to FIG.

FIG. 12 is a diagram showing signal waveforms of respective parts of the disk A having a certain reflectance on the left side and the disk B assuming that the right side has a reflectance 0.5 times that of the disk A. Is. Further, G in FIG. 12 indicates a groove track, L indicates a land track, and Vre
f is a reference potential for signal processing.

The first addition signal 101 obtained by receiving the reflected light from the main beam is not only the difference in the reflected light amount between the groove track and the land track for each of the disk A and the disk B, but also the groove track. Due to the existing recording information, a high frequency component (hereinafter, referred to as an RF signal) is superimposed only when passing through the groove track. The first addition signal 101 obtained by receiving the reflected light from the disk B having a reflectance 0.5 times that of the disk A
Both the DC component and the AC component are 0.5 times the first addition signal 101 obtained from the disk A.

Since the sub beam is arranged at the same interval as the track width with respect to the main beam, the second added signal 102 at the time of seek is a signal waveform obtained by shifting the phase of the first added signal 101 by 90 °. become.

First addition signal 101 and second addition signal 1
The difference signal 103 of 02 becomes 0 because the DC components of the disc A and the disc B are canceled, and only the AC component of the disc B becomes 0.
Similar to the first and second addition signals 102, the relationship is 0.5 times with respect to the disk A.

Since the frequency band of the RF signal contained in the difference signal 103 is constant regardless of the reflectance of the disc, the track cross original signal 104 after the RF signal is removed by the first integrator 2 is different from each other. It is generated as an AC signal that maintains the ratio of the reflectance of the disc.

Next, with respect to the sum signal 105 of the first addition signal 101 and the second addition signal 102, the sum signal 105 obtained from the disk B is the sum signal obtained from the disk A, both the DC component and the AC component. It is 0.5 times 105.

The reflected light amount detection signal 106 is the sum signal 1 described above.
05 is integrated by the second integrator 4 and the RF signal is removed, so that the reflected light amount detection signal 106 obtained from the disk B has a DC component 0.5 times that of the disk A. That is, a DC signal corresponding to the ratio of the reflected light amount is generated.

Here, FIG. 13 shows an example of general characteristics of the variable gain amplifier 5 whose gain is controlled by a negative coefficient with respect to the control voltage. As is clear from FIG. 13, when the control voltage increases (for example, from Va to Vb
, The gain is smaller (eg from Ga to Gb
If the control voltage becomes small (for example, from Vb to Va)
, The gain is larger (eg from Gb to Ga).
become.

Therefore, the track cross original signal 104 is input to the variable gain amplifier 5, and the reflected light amount detection signal 1 is input.
By controlling the gain according to 06, the gain set for the disc B is inversely proportional to the reflected light amount detection signal 106 and doubled with respect to the gain set for the disc A.

As described above, since the track cross original signal 104 has the amplitude of 0.5 times that of the disk A on the disk B, the gain of the variable gain amplifier 5 is set to double by the reflected light amount addition signal 106. As a result, the track cross signal 107 having the same amplitude is obtained.

That is, a stable track cross signal 1 irrespective of changes in the amount of reflected light for different discs and the like.
07 will be obtained.

[0024]

However, in the conventional track cross signal generation circuit as described above, the amplitude of the track cross signal with respect to the unrecorded area and the amplitude of the track cross signal with respect to the already recorded area are significantly different from each other. There's a problem.

Referring to FIG. 14, the CD-R and the CD will be described below.
The operation when performing track seek near the boundary between the recorded area and the unrecorded area of a disc having a pre-groove like RW will be described. In FIG. 14, the same reference numerals and symbols (G, L) as in FIG. 12 indicate the same signal waveform and track, respectively.

In FIG. 14, a difference signal 103 is obtained by calculating the difference between the first addition signal 101 and the second addition signal 102, and an unnecessary RF signal is obtained from this difference signal 104.
By removing the signal, the track cross original signal 10
4 is obtained.

Here, since the RF signal is removed by the first integrator 2, in the recorded area where the RF signal is present, R
Due to the average value of the F signal, the amplitude of the track cross original signal 104 increases by more than the difference in the amount of reflected light from the groove track and the land track.

On the other hand, since the RF signal does not exist in the unrecorded area, the amplitude of the track cross original signal 104 is
The light amount difference between the groove track and the land track becomes the difference itself, which is much smaller than that in the recorded area.

The sum signal of the reflected light addition signals from the groove track and the land track is 105 in the figure, and the second integrator 4 obtains the averaged addition signal 106 as the reflected light amount detection signal. Here, the voltage level of the averaged addition signal 106 for the unrecorded area where the RF signal does not exist is higher than the voltage level of the averaged addition signal 106 for the recorded area where the RF signal exists.

Further, since the variable gain amplifier 5 is configured to control the gain by the reflected light amount detection signal 106 with a negative coefficient, in the unrecorded area where the voltage level of the averaged addition signal 106 is large, The gain is low, and conversely, it is set high in the recorded area.

As described above, the track cross original signal 104 has a small amplitude in the unrecorded area with respect to the already recorded area, and at the same time, the track cross original signal 104 is recorded with the already recorded area by the variable gain amplifier 5 set to a low gain. The amplitude difference further increases, and the finally obtained track cross signal 10
7 has a large amplitude difference between the recorded area and the unrecorded area.

As described above, the track cross signal 107
Must be accurately counted for track searching, and the counting operation is usually processed by digital circuits. For this reason, the track cross signal 107 needs to be digitized by some means, but the fluctuation of the amplitude is directly linked to the fact that accurate counting cannot be performed depending on the precision of the digitizing circuit.

When a recordable disc is used as an information recording medium, it is quite normal for an unrecorded area to exist between a plurality of recorded areas. Therefore, at the time of track seek, when passing through a track in a desired recorded area and entering an unrecorded area,
Accurate seeks can be performed by accurately counting the number of tracks that have passed. Conversely, if the track count in the unrecorded area cannot be performed accurately, the seek time will be greatly increased.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a track cross signal generation circuit capable of generating a track cross signal having an amplitude similar to that of an already recorded area even in an unrecorded area. To do.

[0035]

In order to achieve the above object, the first track cross signal generation circuit according to the present invention receives the reflected light from the main beam to obtain the first track cross signal generation circuit.
Subtractor for generating a difference signal between the addition signal of No. 2 and the second addition signal obtained by receiving the reflected light from the sub beam, and a high frequency component (RF signal) from the difference signal generated by the subtractor
, An adder that generates a sum signal of the first addition signal and the second addition signal, and a high-frequency component (RF signal) from the sum signal generated by the adder A track cross signal generation circuit having a second integrator, which is an area discriminating circuit for discriminating whether the reproduction position is a recorded area or an unrecorded area of the signal, and a difference signal from the first integrator as an input. , A variable gain amplifier that controls the gain with a negative coefficient according to the sum signal from the second integrator and the region discriminated by the region discrimination circuit, and outputs a track cross signal. In the recording area, the gain of the variable gain amplifier is set higher than that in the already recorded area.

According to this configuration, in addition to the advantage of the conventional track cross signal generation circuit that the amplitude of the track cross signal is corrected by the change in the amount of reflected light, the amplitude of the track cross signal is reduced in the unrecorded area. Since the gain of the variable gain amplifier can be increased so as to increase, a stable track cross signal can be obtained even in an unrecorded area.

To achieve the above object, the second track cross signal generation circuit according to the present invention receives the reflected light from the main beam and receives the reflected light from the first addition signal and the reflected light from the sub beam. A subtractor for generating a difference signal with respect to the second addition signal obtained by receiving the light; a first integrator for removing a high frequency component (RF signal) from the difference signal generated by the subtractor; A track cross signal generation circuit having an adder for generating a sum signal of an addition signal and a second addition signal, the amplitude detection circuit detecting an amplitude of a high frequency signal (RF signal) at a signal reproduction position, A variable gain amplifier that receives the difference signal from the integrator 1 and controls the gain with a negative coefficient according to the amplitude of the high frequency signal (RF signal) detected by the amplitude detection circuit, and outputs a track cross signal. Prepared And wherein the door.

According to this configuration, it is possible to detect that the amplitude of the RF signal is also attenuated in the unrecorded area where the track cross signal is attenuated, and the variable gain that follows the RF signal amplitude with a negative control coefficient. The gain of the variable gain amplifier increases not only when the gain of the amplifier increases but also when the RF signal amplitude is proportional to the amount of reflected light, so that the conventional track cross signal generation circuit has In addition to the advantage of correcting the amplitude of the track cross signal by changing the amount of reflected light, a stable track cross signal can be obtained even in an unrecorded area.

In the second track cross signal generation circuit, the amplitude detection circuit receives the differentiator for extracting the alternating current component of the sum signal generated by the adder and the alternating current signal extracted by the differentiator as a rectification signal. It is preferable to include a rectifier that outputs the signal and an integrating circuit that integrates the rectified signal from the rectifier.

Alternatively, in the second track cross signal generation circuit, the amplitude detection circuit detects the peak level of the sum signal generated by the adder and the bottom level of the sum signal generated by the adder. It is preferable to include a bottom detector for detecting the difference, a second subtractor for generating a difference signal between the peak level and the bottom level, and a second integrator for integrating the difference signal from the second subtractor. .

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
3 is a functional block diagram showing a configuration example of a track cross signal generation circuit according to the embodiment of FIG. The present embodiment is different from the conventional example in addition to the configuration of the conventional example, in addition to the configuration of the conventional example, it is determined whether the reproduction position is a recorded area or an unrecorded area of a signal and an area determination signal 200 is output Circuit 50
And a second adder 6 that adds the reflected light amount detection signal 106 from the reflected light amount detection circuit 1000 and the area determination signal 200 from the area determination circuit 50 and outputs a gain control signal 201. .

Next, by using the track cross generation circuit configured as described above, track seek is performed in the vicinity of the boundary between the recorded area and the unrecorded area of a disc having a pre-groove such as a CD-R or a CD-RW. The operation at that time will be described with reference to the waveform chart of FIG.

In FIG. 2, signal 101 to signal 106
Up to the above, the signal waveform is the same as the conventional example. Here, the amplitude of the track cross original signal 104 in the unrecorded area becomes smaller than that in the recorded area as in the conventional case. Therefore, if the area discriminating circuit 50 is configured to output a signal which is larger in the recorded area than in the unrecorded area and which has a sufficient difference from the increment of the reflected light amount detection signal 106, the output signal is 200. Then, the addition signal of the reflected light amount detection signal 106 and the area discrimination signal 200 by the second adder 6 is obtained as 201.

The variable gain amplifier 5 has a gain control signal 2
With respect to 01, since the gain control characteristic has a negative coefficient, the gain decreases in the recorded area and turns to increase in the unrecorded area. As a result, the reflected light amount detection signal 10
By adding 6 and the area discrimination signal 200 at a ratio according to each application, the track cross signal which is the output signal of the variable gain amplifier 5 can be made to have substantially the same amplitude as 107.

That is, by adding the reflected light amount detection signal 106 and the area discrimination signal 200 at an appropriate ratio and controlling the variable gain amplifier 5, it is possible to stabilize regardless of the change in the reflected light quantity and whether it is a recorded area or an unrecorded area. It is possible to generate a track cross signal.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
3 is a functional block diagram showing a configuration example of a track cross signal generation circuit according to the embodiment of FIG. This embodiment is different from the first embodiment in that the second integrator 4 and the area discrimination circuit 5 are provided.
Instead of 0 and the second adder 6, an RF signal amplitude detection circuit 60 that detects the amplitude of the reproduction RF signal from the sum signal 105 and outputs the RF amplitude detection signal 202 that is the gain control signal of the variable gain amplifier 5. (Amplitude detection circuit) is provided.

Next, by using the track cross generation circuit configured as described above, track seek is performed in the vicinity of the boundary between the recorded area and the unrecorded area of a disc having a pre-groove such as a CD-R or a CD-RW. Figure 4 shows the operation
This will be described with reference to the waveform chart of FIG. The variable gain amplifier 5 is configured to perform gain control with a negative coefficient with respect to the control signal as in the conventional case, and the RF signal amplitude detection circuit 60 has a positive coefficient with respect to the amplitude value of the RF signal.
The description will be given assuming that it is configured to output the amplitude detection signal 202.

In FIG. 4, signal 101 to signal 105
Up to the above, the signal waveform is the same as that of the conventional example. Here, the amplitude of the track cross original signal 104 in the unrecorded area becomes smaller than that in the recorded area as in the conventional case. Since the output signal of the RF amplitude signal detection circuit 60 is output as an RF amplitude detection signal having a positive coefficient with respect to the amplitude value of the RF signal due to its configuration, it becomes a larger signal in the recorded area than in the unrecorded area. , 202.

Since the variable gain amplifier 5 has a gain control characteristic of a negative coefficient with respect to the RF amplitude detection signal 202, its gain decreases in the recorded area and increases in the unrecorded area. Thus, by determining the coefficient of the RF amplitude detection signal 202 according to each application, the track cross signal which is the output signal of the variable gain amplifier 5 is set to 1
Like 07, the amplitude can be made almost the same, and a stable track cross signal can be generated regardless of whether it is a recorded area or an unrecorded area.

Further, as is clear from the conventional example, since the amplitude of the RF signal generally follows the change of the reflected light amount with a positive coefficient, in the state where the reflected light amount becomes low, the track Not only the amplitude of the original cross signal 104 decreases, but also the RF amplitude detection signal 202 decreases. As a result, the gain of the variable gain amplifier 5 is controlled to be high, and the variable gain amplifier 5 operates so as to correct the amplitude decrease of the track cross original signal 104,
Amplitude correction according to changes in the amount of reflected light can be performed as in the conventional example.

(Third Embodiment) FIG. 5 shows a third embodiment of the present invention.
3 is a functional block diagram showing a configuration example of a track cross signal generation circuit according to the embodiment of FIG. In this embodiment, the RF signal amplitude detection circuit 60 of the second embodiment uses a differentiator 7 that extracts an AC component 108 from a sum signal 105 of the first addition signal 101 and the second addition signal, and a differentiator. The RF signal amplitude detection circuit 2000 includes a rectifier 8 that rectifies the AC signal 108 from the AC output signal 7 and outputs a rectified signal, and a second integrator 9 that averages the rectified signal and outputs the RF amplitude detection signal 202. It is a thing.

Next, by using the track cross signal generation circuit configured as described above, a track seek is performed in the vicinity of the boundary between the recorded area and the unrecorded area of a disc having a pre-groove such as a CD-R or a CD-RW. The operation at that time will be described with reference to the waveform chart of FIG. here,
It is assumed that the variable gain amplifier 5 is configured to perform gain control with a negative coefficient with respect to the control signal level as in the conventional case.

In FIG. 6, signal 101 to signal 105
Up to the above, the signal waveform is the same as the conventional example. Here, the amplitude of the track cross original signal 104 in the unrecorded area becomes smaller than that in the recorded area as in the conventional case. Further, the AC component 108 is extracted from the sum signal 105 by the differentiator 7, and the AC signal 108 is rectified and integrated to generate the RF amplitude detection signal 202.

In FIG. 6, for convenience of explanation, the time constant of the second integrator 9 is set relatively fast, but the RF amplitude detection signal 202 is set by setting this time constant.
It is obvious that the response of can be set arbitrarily.

Since the variable gain amplifier 5 has a gain control characteristic of a negative coefficient with respect to the RF amplitude detection signal 202, its gain decreases in the recorded area and increases in the unrecorded area. Accordingly, by determining the coefficient of the RF amplitude detection signal according to each application, the track cross signal which is the output signal of the variable gain amplifier 5 can be made to have substantially the same amplitude like 107, and the recorded area It is possible to generate a stable track cross signal regardless of whether it is an unrecorded area.

Further, as is clear from the conventional example, since the amplitude of the RF signal generally follows the change of the reflected light amount with a positive coefficient, the track is reduced when the reflected light amount is low. Not only the amplitude of the original cross signal 104 decreases, but also the RF amplitude detection signal 202 decreases. As a result, the gain of the variable gain amplifier 5 is controlled to be high, and the variable gain amplifier 5 operates so as to correct the amplitude decrease of the track cross original signal 104,
Amplitude correction according to changes in the amount of reflected light can be performed as in the conventional example.

Further, the track cross signal 107 outputs a logical "L" level during on-track and a logical "H" level during off-track, and it is possible to detect on-track and off-track from the signal shape. I can. That is, by using the track cross signal 107, it is possible to detect not only the seek but also the deviation of the track.

As an example of this, FIG. 7 shows the operation of the track cross signal generation circuit according to the present embodiment during recording. In FIG. 7, the left side is when recording to a CD-R, the right side is a CD-R.
6 shows a signal waveform at the time of recording on the RW.

In recording on the CD-R and the CD-RW, when the peak levels Vpk of the write signals are matched,
The sum signal of the first addition signal 101 and the second addition signal 102 becomes as shown by 105, and the AC signal 108 after passing through the differentiator 7 is level-shifted around each average level, so that the signal average It becomes like 108 whose level is Vdc. By rectifying the AC signal 108 by the rectifier 8 and integrating it by the second integrator 9, the RF amplitude detection signal becomes 20
It becomes like 2. Here, the RF amplitude detection signal 202 shown by the solid line is obtained by setting the response of the second integrator 9 to high speed, and by setting the response to low speed, Vdcri
When the recording is performed on the CD-R and the CD-RW, the RF amplitude detection signal has a difference of ΔVint at 202 when the CD-R and the CD-RW are recorded.

As described above, since the gain of the variable gain amplifier 5 is controlled by the RF amplitude detection signal 202,
At this time, the gain of the variable gain amplifier 5 has a difference corresponding to ΔVint.

That is, an amplitude difference occurs in the track cross signal 107 due to this gain difference, so that there appears a difference in track deviation detection accuracy between CD-R recording and CD-RW recording.

According to the configuration of the third embodiment, the problem at the time of seeking can be sufficiently solved, but in order to detect the track deviation at the time of recording, a circuit for correcting ΔVint between the CD-R and the CD-RW is added. There is a need to. RF to solve this
The configuration of the signal amplitude detection circuit will be described in the fourth embodiment below.

(Fourth Embodiment) FIG. 8 shows a fourth embodiment of the present invention.
3 is a functional block diagram showing a configuration example of a track cross signal generation circuit according to the embodiment of FIG. In FIG. 8, the RF signal amplitude detection circuit 3000 detects a peak level 110 from a sum signal 105 of the first addition signal 101 obtained from the main beam and the second addition signal 102 obtained from the sub beam.
, A bottom detector 11 that extracts a bottom level 111 from the sum signal 105, a subtractor 12 that generates a difference signal 112 between the peak level 110 and the bottom level 111, and a difference signal 112 that is integrated. And a second integrator which outputs the RF amplitude detection signal 202.

Next, by using the track cross generation circuit configured as described above, track seeking is performed in the vicinity of a boundary between an already recorded area and an unrecorded area of a disc having a pre-groove such as a CD-R or a CD-RW. The operation at that time will be described with reference to the waveform chart of FIG. Here, it is assumed that the variable gain amplifier is configured to perform gain control with a negative coefficient with respect to the control signal level as in the conventional case.

In FIG. 9, signal 101 to signal 105
Up to the above, the signal waveform is the same as the conventional example. Here, the amplitude of the track cross original signal 104 in the unrecorded area becomes smaller than that in the recorded area as in the conventional case. Further, the peak level detected by the peak detector 10 from the sum signal 105 from the adder 3 is 110, and the sum signal 105
The bottom level detected by the bottom detector 11 is 111, and the difference signal 112 is detected by the second integrator 1.
The RF amplitude detection signal 202 is generated by integrating at 3.

In FIG. 9, the time constant of the second integrator 13 is set relatively fast for convenience of description, but the RF amplitude detection signal 20 is set by setting the time constant.
It is obvious that the response of 2 can be set arbitrarily.

Since the variable gain amplifier 5 has a gain control characteristic of a negative coefficient with respect to the RF amplitude detection signal 202, its gain decreases in the recorded area and increases in the unrecorded area. Accordingly, by determining the coefficient of the RF amplitude detection signal according to each application, the track cross signal which is the output signal of the variable gain amplifier 5 can be made to have substantially the same amplitude like 107, and the recorded area It is possible to generate a stable track cross signal regardless of whether it is an unrecorded area.

Further, as is clear from the conventional example, since the amplitude of the RF signal generally follows the change in the reflected light amount with a positive coefficient, the track crossing occurs when the reflected light amount is low. Not only is the amplitude of the original signal 104 reduced, but so is the RF amplitude detection signal 202.
As a result, the gain of the variable gain amplifier 5 is controlled to be high, the variable gain amplifier operates so as to correct the amplitude reduction of the track cross original signal 104, and the amplitude correction according to the change in the reflected light amount is performed as compared with the conventional example. You can do the same.

Further, as in the third embodiment, FIG.
FIG. 9 shows the operation of the track cross signal generation circuit according to the present embodiment during recording. In FIG. 10, the left side shows the signal waveforms at the time of recording on the CD-R, and the right side shows the signal waveforms at the time of recording on the CD-RW.

In recording on the CD-R and the CD-RW, when the peak levels Vpk of the write signals are matched,
The sum signal of the first addition signal 101 and the second addition signal 102 becomes like 105, and the peak level signal after passing the peak detector 10 becomes like 110. Similarly, the bottom level signal after passing through the bottom detector 11 becomes like 111. By subtracting and integrating these signals, the RF amplitude detection signal becomes 202. Here, the RF amplitude detection signal 202 shown by the solid line is obtained by setting the response of the second integrator 13 at a high speed, and by setting the response at a low speed, the DC component of the signal is removed, and Vdcrint and Vdcrwint are removed. When the CD-R and the CD-RW are recorded, ΔVint becomes 0 even when the CD-R and the CD-RW are recorded.

That is, according to the configuration of this embodiment, the CD
It is possible to obtain the same track cross signal even during recording on -R and CD-RW, not only solve the problem at the time of seeking, but also obtain the track cross signal 107 that can be used for detecting track deviation during recording. I can.

[0073]

As described above, according to the present invention,
The following effects are achieved.

(1) In the conventional configuration, the reproduction position is detected whether it is an already recorded area or an unrecorded area, and the gain of the variable gain amplifier is controlled so that the gain becomes higher in the unrecorded area than in the already recorded area. By adding, not only can the track cross signal be corrected according to the change in the amount of reflected light, but
In the unrecorded area where the track cross signal is attenuated, the gain of the variable gain amplifier is increased so as to increase the amplitude, so that a stable track cross signal can be obtained even in the unrecorded area.

(2) By detecting the amplitude of the RF signal and controlling the gain of the variable gain amplifier with a negative coefficient with respect to the amplitude, the amplitude is increased in the unrecorded area where the track cross signal is attenuated. Since the gain of the variable gain amplifier increases as described above, a stable track cross signal can be obtained even in an unrecorded area. Further, since the amplitude of the RF signal is a function having a positive coefficient according to the amount of reflected light, the amplitude of the track cross signal depending on the amount of reflected light, which is an advantage of the conventional example, can be simultaneously corrected.

(3) The RF signal amplitude detection circuit in the track cross signal generation circuit can also function as an RF signal amplitude detection circuit usually provided in the optical disc system in order to keep the amplitude of the RF signal constant. Yes, it is possible to minimize the increase in special costs for implementation.

(4) By using an RF signal amplitude detection circuit having a different configuration, it is possible to perform the function of a media discriminating circuit normally provided in an optical disc system for discriminating a medium. It is possible to minimize the increase in the special costs of.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a configuration example of a track cross signal generation circuit according to a first embodiment of the present invention.

FIG. 2 is a signal waveform diagram showing a seek operation of the track cross signal generation circuit according to the first embodiment near a boundary between a recorded area and an unrecorded area.

FIG. 3 is a functional block diagram showing a configuration example of a track cross signal generation circuit according to a second embodiment of the present invention.

FIG. 4 is a signal waveform diagram showing a seek operation of a track cross signal generation circuit according to a second embodiment near a boundary between a recorded area and an unrecorded area.

FIG. 5 is a functional block diagram showing a configuration example of a track cross signal generation circuit according to a third embodiment of the present invention.

FIG. 6 is a signal waveform diagram showing a seek operation of a track cross signal generation circuit according to a third embodiment near a boundary between a recorded area and an unrecorded area.

FIG. 7 is a diagram illustrating a CD-R and a CD-R during on-track of the track cross signal generation circuit according to the third embodiment.
Signal waveform diagram showing recording operation for W

FIG. 8 is a functional block diagram showing a configuration example of a track cross signal generation circuit according to a fourth embodiment of the present invention.

FIG. 9 is a signal waveform diagram showing the operation of the track cross signal generation circuit according to the fourth embodiment at the time of seeking near the boundary between the recorded area and the unrecorded area.

FIG. 10 is a CD-R and a CD-R when the track cross signal generation circuit according to the fourth embodiment is on-track.
Signal waveform diagram showing recording operation for W

FIG. 11 is a functional block diagram showing a configuration example of a conventional track cross signal generation circuit.

FIG. 12 is a signal waveform diagram showing an operation of a conventional track cross signal generation circuit for a disk A and a disk B in a recorded area.

FIG. 13 is a diagram showing an example of gain characteristics of a variable gain amplifier having negative gain control characteristics.

FIG. 14 is a signal waveform diagram showing a seek operation of a conventional track cross signal generation circuit near a boundary between a recorded area and an unrecorded area.

[Explanation of symbols]

1 Subtractor (first subtractor) 2 First integrator 3 Adder (first adder) 4 Second integrator 5 Variable gain amplifier 6 Second adder 7 differentiator 8 rectifier 9 Second integrator 10 Peak detector 11 Bottom detector 12 Second subtractor 13 Second integrator 50 area discrimination circuit 60 RF signal amplitude detection circuit (amplitude detection circuit) 1000 Reflected light amount detection circuit 2000, 3000 RF signal amplitude detection circuit

Claims (4)

[Claims] 1. A subtractor for generating a difference signal between a first addition signal obtained by receiving reflected light from a main beam and a second addition signal obtained by receiving reflected light from a sub-beam. A first integrator for removing high frequency components from the difference signal generated by the subtractor; an adder for generating a sum signal of the first addition signal and the second addition signal; A track cross signal generation circuit having a second integrator for removing a high frequency component from the generated sum signal, the region discrimination circuit discriminating whether a reproduction position is a recorded region or an unrecorded region of the signal, A variable gain amplifier that receives the difference signal from the first integrator, controls the gain in accordance with the sum signal from the second integrator and the area determined by the area determination circuit, and outputs a track cross signal. Specially equipped with Track cross signal generation circuit according to. 2. A subtractor for generating a difference signal between a first added signal obtained by receiving reflected light from a main beam and a second added signal obtained by receiving reflected light from a sub beam. And a track cross signal having a first integrator for removing high frequency components from the difference signal generated by the subtractor, and an adder for generating a sum signal of the first addition signal and the second addition signal. A generation circuit, which receives an amplitude detection circuit for detecting the amplitude of a high-frequency signal at a signal reproduction position and a difference signal from the first integrator, and outputs the difference signal according to the amplitude of the high-frequency signal detected by the amplitude detection circuit. A track cross signal generation circuit having a variable gain amplifier that outputs a track cross signal whose gain is controlled. 3. The amplitude detection circuit includes a differentiator for extracting an AC component of the sum signal generated by the adder, and a rectifier for receiving the AC signal extracted by the differentiator and outputting a rectified signal. The track cross signal generation circuit according to claim 2, further comprising: a second integrator that integrates the rectified signal from the rectifier. 4. The peak detector for detecting the peak level of the sum signal generated by the adder, and the bottom detector for detecting the bottom level of the sum signal generated by the adder. And a second subtractor for generating a difference signal between the peak level and the bottom level, and a second integrator for integrating the difference signal from the second subtractor. 2. The track cross signal generation circuit described in 2.