JPH1049885A - Optical disk recording and reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the type of a disk without utilizing recorded information of the disk. SOLUTION: A pickup device 21 has a plurality of optical systems of different numerical apertures(NA) and a photoelectric converting means for detecting a reflecting light resulting from the projection of optical beams to a face of an optical disk. A focus servo circuit 32 controls the focus state of the optical system projecting the optical beams in accordance with an output of the photoelectric converting means. An error signal generator 31, a focus error signal- processing circuit 41, a sum signal-processing circuit 42 and a disk type-detecting circuit 43 forcibly drive a focus control means in a predetermined state while the optical disk is stopped rotating, and obtain a focus response signal of the photoelectric converting means which is changed following the movement of the focus control means, thereby obtaining an output detecting a type of the optical disk in accordance with waveform information of the focus response signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording / reproducing apparatus, and more particularly to a discrimination function of these discs and an optimum signal even in a situation where a plurality of different types of optical discs are available recently. The present invention relates to an optical disk recording / reproducing apparatus capable of obtaining a processing mode.

[0002]

2. Description of the Related Art Conventionally, compact disks (CD) and laser disks (LD) exclusively for music have been used as optical disks.
Is being developed. On the other hand, recently, moving picture video data, audio data, and sub-picture data (for example, subtitle data) are compressed and recorded at high density on a compact compact disc (a disc having the same radius as the CD). Regarding audio and subtitles, a system has been developed in which a plurality of different languages are recorded, and at the time of reproduction, audio of a desired language and subtitles of a desired language can be freely selected and reproduced. This type of optical disk is tentatively referred to as a DVD (digital versatile disk). As for DVDs, DVD-ROMs and DVD-RAMs are being developed.

As described above, various types of optical disks are available as optical disks. A reproducing apparatus for reproducing such an optical disk reads a modulation signal recorded by detecting a reflected light by irradiating a laser beam on a recording surface of the disk, and a rotary servo unit for controlling the rotation of the disk. It has an optical pickup device. The modulated signal output from the optical pickup device is first input to a waveform equalization circuit and equalized in waveform. Next, the waveform-equalized signal is guided to the demodulation circuit.

[0004] Here, when comparing the capacity of the above-mentioned CD and DVD, the CD is 650 Mbit and the DVD
Has a capacity of 4.7 Gbits, which is about seven times, and the recording density is remarkably large. Therefore, when reproducing a DVD, a 650 nm beam is used as a laser beam for irradiating a track, instead of the 780 nm wavelength used for reproducing a CD. In this case, an optical system with a high numerical aperture (high NA) is used to optically focus the laser beam. Further, in the case of a CD, the thickness of a disk substrate is specified as 1.2 mm. However, in the case of a DVD, when the thickness is set to 1.2 mm because the beam is narrow, the disk is easily affected by tilt (substrate inclination). 0.6 of that half
mm disk substrate (substrate) is used.

[0005] When such a DVD and its recording device and reproducing device are developed, naturally, devices capable of reproducing various optical disks are demanded. However, in order to realize such an apparatus, it is necessary to switch the NA of the optical pickup apparatus, for example, between a CD and a DVD. N
As a switching method of A, a two-lens switching method (two optical lens systems are prepared), a two-focus lens method (two focal points exist in the optical axis direction), and a diaphragm switching method (switching the aperture of the diaphragm) ) Can be considered.

[0006]

In order to realize the above NA switching, the type of the optical disc mounted on the reproducing apparatus is identified,
It is necessary to set an appropriate signal processing form. If the type of the mounted optical disc, the NA of the optical pickup device, and the processing form of the signal processing circuit do not match, the reproduced signal will be only an error signal.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disk recording / reproducing apparatus capable of determining a disk type without using information recorded on the disk.

Another object of the present invention is to provide an optical disk recording / reproducing apparatus capable of determining the type of a writable optical disk without erroneous writing.

It is still another object of the present invention to provide an optical disk recording / reproducing apparatus capable of discriminating the type of a rewritable optical disk without causing an error.

It is another object of the present invention to provide an optical disk recording / reproducing apparatus capable of determining a single-layer disk and a double-layer disk together with the disk type. Another object of the present invention is to provide a disc type discriminating operation,
An object of the present invention is to provide an optical disk recording / reproducing device which ensures the safety of an optical pickup device.

Still another object of the present invention is to provide an optical disk recording / reproducing apparatus capable of smoothly proceeding to reproduction signal processing after discrimination of a disk type is obtained.

[0012]

In order to achieve the above object, the present invention provides a plurality of optical systems having different numerical apertures (NA), and an optical disk using one of the plurality of optical systems. Optical conversion means for receiving light reflected by the surface of the optical system, focus control means for controlling the focus state of the optical system irradiating the optical beam according to the output of the photoelectric conversion means, While the rotation of the optical disc is stopped, the focus control unit is forcibly operated to a predetermined state, and a focus response signal of the photoelectric conversion unit obtained by changing with the operation is acquired. Determining means for obtaining an optical disk type determination output according to the content of the level change.

Further, the present invention is characterized in that the focus control means is forcibly operated while using the optical system having the largest NA. Further, the invention is characterized in that the focus response signal of the photoelectric conversion means is a focus error signal.

Further, according to the present invention, the photoelectric conversion means may include
A split detector, and two sub-detectors arranged so as to sandwich the quadrant detector, wherein the focus response signal is a focus error signal created using an output of the quadrant detector. Features. Further, the invention is characterized in that the focus response signal is a sub-beam sum signal of a signal obtained from the sub-detector. Furthermore, the present invention is characterized in that the focus response signal is composed of a focus error signal created using the output of the quadrant detector and a sum signal of signals obtained from the sub-detectors. And

Further, the present invention is characterized in that the plurality of optical systems having different numerical apertures (NA) are optical systems having different lenses. Furthermore, the present invention provides the numerical aperture (N)
A) The plurality of optical systems having different A) are characterized in that the plurality of optical systems have different numerical apertures (NA) by switching apertures. Further, the present invention is characterized in that the plurality of optical systems having different numerical apertures (NA) have two or more focal points to constitute a plurality of optical systems having different numerical apertures (NA). And

According to the present invention, the optical disk comprises:
Either have a 2 mm substrate or a substrate of approximately 0.6 mm. In the present invention,
The determination means uses a peak value and a bottom value of the focus response signal output from the photoelectric conversion means as the content of the level change. Further, in the present invention, the determination means uses amplitude information of the focus response signal output from the photoelectric conversion means as the content of the level change. Still further, in this invention, the determination means uses a plurality of peak values and a plurality of bottom values of the focus response signal output from the photoelectric conversion means as the content of the level change. Further, in this invention, the determination means uses the pattern information of the focus response signal, which is the output of the photoelectric conversion means, as the content of the level change.

In the present invention, the focus response signal is a signal obtained by irradiating the surface of the optical disk with a radius of about 23 mm to about 24 mm with a beam. Further, the present invention further comprises a disk rotation servo system, and the disk rotation servo system is substantially turned off until the determination means operates, thereby realizing rotation stop of the optical disk. . Further, in the present invention, the focus control unit is forcibly operated in a state in which the optical system having the smallest NA is used.

According to the above-mentioned means, the level of the focus error signal utilizes the fact that the change pattern varies depending on the type of the disc and that varies depending on the numerical aperture (NA). It is not necessary to rotate the optical disk for this purpose. Therefore, since beam scanning is not performed, data destruction and error writing do not occur even if the disk is recordable and rewritable.

Further, according to the present invention, a photoelectric conversion means for irradiating an optical disk surface with an optical beam through an optical system and receiving a reflected light thereof, and a focus of the optical system for irradiating the optical beam with the photoelectric system. A focus control means for controlling using an output of the conversion means; and a focus search mode by forcibly operating the focus control means in a state where the rotation of the optical disc is stopped, wherein the focus control means performs focus control. A focus response signal from the photoelectric conversion means, which is obtained by changing the focus response signal, is acquired. The second predetermined focus response signal is obtained within a predetermined time from the time when the focus response signal indicates the first predetermined focus state. It is characterized by having a focus search means for turning off the focus search mode when the focus state is not attained. To.

Further, according to the present invention, the focus search means acquires the focus response signal while moving the optical system from a position far from the optical disk to a position close to the optical disk via the focus control means, and acquires the second predetermined response signal. If the focus state is not reached, the optical system is controlled to move away from the optical disk.

Further, in the present invention, the focus search means acquires the focus response signal while moving the optical system from a position far from the optical disk to a position close to the optical disk via the focus control means, and the determination means determines the disk type. After the determination is made, the forced operation of the focus control means is released while controlling the optical system to move the optical system away from the optical disk.

By the above means, the safety of the optical pickup device can be improved in the disc type discriminating operation.
After the disc type is determined, the process can smoothly proceed to reproduction signal processing and servo operation.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention. 11 is an optical disk (CD or DV
D etc.), and is rotationally driven by the disk motor 12. An optical pickup device 21 is controlled to move in the radial direction of the disk by a feed motor (not shown). The high-frequency modulated signal output from the optical pickup device 21 is input to an equalizer 23 via a preamplifier 22 and equalized in waveform. The modulated signal whose waveform has been equalized is
The data is input to the data slicer 24 and binarized. This 2
The coded signal is supplied to the data extraction unit 25. The data extraction unit 25 includes a phase locked loop circuit (PLL circuit)
And a data synchronous clock generator using the same. Therefore, in the data extraction circuit 25, a data clock is generated, and the modulation signal is sampled using the data clock. As a result, the digital data recorded on the optical disk is extracted from the data extraction circuit 25, and the digital data is output to an error correction circuit (EC).
C), and supplied to the data processing unit 26 including a sync separator for separating the synchronization signal.

The data clock in the data processing unit 26 and the synchronization signal obtained by the sync separator are input to a disk servo circuit 28. The disk servo circuit 28 captures a synchronization signal synchronized with the data clock,
Disk motor 1 based on the frequency and phase of the synchronization signal
2 is controlled. Then, during normal reproduction, the disk servo circuit 28 controls the rotation of the disk motor 12 so that a predetermined frequency and phase of the synchronization signal can be obtained.

The output of the preamplifier 22 is further input to an error signal generator 31. This error signal generator 31
As will be described later, an error signal suitable for each servo system is generated using an output signal from the photoelectric conversion element of the pickup device 21. The focus error signal, the phase difference tracking error signal, the three-beam tracking error signal,
Has been generated. The error signal generator 31 generates a sub-beam sum signal.

The above focus error signal is supplied to a focus servo circuit 32 and also to a focus error signal processing circuit 41. The phase difference tracking error signal and the three-beam tracking error signal are input to the tracking servo circuit 33. The output of the focus servo circuit 32 is supplied to a focus drive unit of the pickup device 21. The output of the tracking servo circuit 33 is supplied to a tracking drive unit of the pickup device 21 and is also supplied to a feed motor servo circuit 34. The feed motor is
This motor controls the movement of the pickup device 21 in the radial direction of the disk, and is driven when supplementing tracking control or during a jump operation. Also, the pickup device 21
In addition, the opening (N
A) A switching signal is supplied. In response to the NA switching signal, when the pickup device 21 is a two-lens switching system (two optical lens systems are provided), the lens is switched, and in the case of the aperture switching system, the aperture of the aperture is switched. Will be In the case where the pickup device 21 is a bifocal lens system (two focal points exist in the optical axis direction), the switching need not be particularly performed.

The sub-beam signal from the error signal generator 31 is supplied to a sum signal processing circuit 42. The focus error signal is supplied to a focus error signal processing circuit 41. The sum signal processing circuit 42 and the focus error signal processing circuit 41 are circuits for obtaining a signal for determining the disk type, and the output is input to the disk type determination circuit 43.

FIG. 2 shows a basic configuration of the pickup section of the above-mentioned pickup device 21 and an error signal generator 31 for obtaining a focus error, a three-beam tracking error, a phase difference tracking error and the like.

That is, the arrangement of the photodiodes A to F constituting the photodetector of the pickup device 21, the inside of the preamplifier 22, and each error detection unit are shown. In this example, the photodetector comprises four-division photodiodes A, B, C, D
And photodiodes (sub-photodiodes) E and F arranged before and after. Ideally, the photodiode A whose central reflected beam is divided into four,
Irradiation is performed on the light receiving surfaces of B, C, and D at an equal ratio (area). In a good tracking state, the front and rear photodiodes E and F are evenly irradiated with the corresponding reflected beams (sub beams).

The outputs of the photodiodes A to F are introduced into buffer amplifiers 22a to 22f, respectively.
The outputs A and C of the buffer amplifiers 22a and 22c are
It is added by 1 and output as an (A + C) signal. Also,
The outputs B and D of the buffer amplifiers 22b and 22d are
The signal is added by 2 and output as a (B + D) signal. Then, the outputs of the adders 51 and 52 are input to a subtractor 53, subjected to arithmetic processing of (A + C)-(B + D), and taken out as a focus error signal. The focus error signal is further input to an S-shaped level detection circuit to detect a focus state (this detection operation will be described later).

The outputs of the adders 51 and 52 are input to a phase difference detector 54. The phase difference detector 54 detects the phase difference between the (A + C) signal and the (B + D) signal. This detection signal is used as a phase difference tracking error signal. This phase difference tracking error signal is used as an effective signal when a DVD is reproduced.

The outputs of the buffer amplifiers 22e and 22f are subjected to subtraction processing by a subtractor 55 to generate an (EF) signal. This (EF) signal is used as a three-beam tracking error signal. This three-beam tracking error signal is used as an effective signal when a CD is reproduced.

The adder 56 performs A + B + C + D and performs HF
Signal is being generated. The HF signal is a modulated signal,
3 is input. Here, the buffer amplifier 22
An adder 57 for adding the outputs of e and 22f is provided. The output of the adder 57 is input to the sum signal processing circuit 42 shown in FIG. 1 and used as disc discrimination information.

Returning to FIG. 1, the description will be continued. According to the apparatus of the present invention, the sum output of the front and rear light receiving elements F and E is input to the sum signal processing circuit 42, and the focus error signal is input to the focus error signal processing circuit 41 and used as disc discrimination information. I have.

According to the present invention, the relationship between the disc thickness error Δd and the focus blur amount (spherical aberration) WΔd is as follows: WΔd = [(n ² -1) / 8n ³ ] × (NA) ⁴ × Δd (n; It is noted that the amount of focus blur due to a disc thickness error is proportional to the fourth power of NA. This means that a difference in the thickness of the substrate of the disk can be detected by monitoring the change in the focus error signal. Further, as the NA becomes larger, the focus blur amount is significantly affected by the difference in the thickness of the disc.

Therefore, in the present invention, the level of the focus error signal or the waveform information (for example, peak / bottom) of the signal (sub beam sum signal) according to the level is detected. The type of the optical disk is determined by employing, for example, the following methods and means (1) to (5). This determination can be realized without rotating the optical disk.

That is, the device of the present invention realizes the following method and means, for example. (1) A method and means for discriminating a disc by setting the NA to a fixed value, monitoring the state of a focus error signal, and (2) NA
Is fixed, the state of the focus error signal and the state of the sub-beam sum signal are monitored, and a method and means for discriminating the disc. (3) The NA is switched to DVD and CD modes, and the focus error signal in each case is changed. (4) Switching the NA between DVD and CD modes, monitoring the state of the focus error signal and the state of the sub-beam sum signal in each case, and discriminating the disk. (5) a method and means for setting the NA to a fixed value, monitoring the state of the sub-beam sum signal, and discriminating the disc;
After the type of the disk is determined by the above method and means, the disk type determination circuit 43 changes the functions and parameters of each unit of the reproducing apparatus so that the entire reproducing apparatus is in an optimal state for reproducing the optical disk. Switching can be set. For example, the characteristics of the equalizer 23 for performing waveform equalization, the data processing form of the data processing unit 26, the servo characteristics of the disk servo circuit 28 and the tracking servo circuit 33, the optical system (NA) of the pickup device 21, and the like.

According to the present invention, for example, a peak / bottom of a level of a focus error signal or a signal (sub-beam sum signal) according to the level is detected. These signals will be referred to as focus response signals. And
The type of the optical disk is determined by the methods and means (1) to (5) described above. This determination can be realized without rotating the optical disk, and the NA is determined at the same time as the disk is determined.

In the present invention, as described above, the focus error signal is effectively used, and the sub-beam sum signal of the sub-beam is effectively used. Therefore, the patterns of these signals are known in advance.

FIG. 3 shows the change characteristics of the focus error signal of each optical disc and the signal (sub-beam sum signal) according to the focus error signal when the numerical aperture (NA) is set to the DVD mode and when the numerical aperture (NA) is set to the CD mode. The measurement results are shown.

That is, the measurement results A1, A2, and A3 indicate that the single-layer DVD
This is a measurement result for a two-layer CD. Measurement result B
1, B2, and B3 are measurement results for a single-layer DVD, a double-layer DVD, and a CD with the NA set to the CD mode. In each measurement result, SBAD is a sub-beam sum signal, and FE is a focus error signal.

Looking at the measurement result A1, in this measurement, the optical disk is a single-layer DVD and the NA is a DVD mode. In this case, the peak value and the bottom value of SBAD and FE are both maximum. On the other hand, when the measurement is performed while the NA is switched, the measurement result becomes B1. This measurement result B1 is
The peak value and the bottom value of SBAD and FE are measured results A
Less than one.

Next, looking at the measurement result A2, in this measurement, the optical disk is a DVD 2 layer and the NA is a DVD mode. In this case, both the SBAD and the FE have a peak value and a bottom value for two layers. And the change waveform clearly appears. On the other hand, when the measurement is performed while the NA is switched here, the measurement result is as shown in B2. In this measurement result B2, the waveforms of the peak and bottom values of SBAD and FE are unclear.

Referring to the measurement result A3, in this measurement, the optical disk is in the CD mode and the NA is in the DVD mode. In this case, the peak-to-peak waveforms of SBAD and FE are unclear. In particular, the bottom waveform is unclear. On the other hand, when the measurement is performed while the NA is switched, the measurement result is as shown in B3. In this case, a peak / bottom waveform clearly appears.

The method and means of the present invention are based on the SBA described above.
The type can be determined without rotating the optical disk by effectively using D and / or FE. Next, the operation of the focus servo means and the disc type determination means using information based on the above measurement results will be described. The control circuit may use either a system control circuit (CPU) for controlling the entire system or a control circuit (CPU) provided independently in the disk type determination circuit 43.

In FIG. 4, when the apparatus starts, in steps S1 and S2, either the DVD mode or the CD mode is set, and the NA is also set. Next, the disk rotation is forcibly turned off as the disk rotation servo off and the tracking servo off. Further, step S
In step 4, the focus servo is forcibly operated to control the focus state, and the focus is controlled in a direction of approaching the disk surface, for example, from a distance. In parallel with this control, a feature discrimination process of the detection signal is performed in step S5. There are various examples of this feature discrimination process, which will be described later in detail. The disc type is determined based on the characteristic determination result (measurement result) (S6).

When the disc is determined, step S
At 7, the determination is made as to whether it is the first time or the second time. If it is the first time, the process proceeds to step S8, and based on the disk determination result, the characteristics and NA of each block of the system are set again to a state suitable for the disk.

Then, the process returns to step S4, and the disc type determination process is performed again. Then, when the second determination is obtained in step S7, it is determined whether the first disk type determination result is the same as the second disk type determination result (step S9). If they are the same, a reproduction start is executed in step S10, but if the determination results are different, a warning display is performed.

In FIG. 4, the description has been made on the assumption that the method does not consider switching of the numerical aperture (NA). That is, in the above description, when the first disc discrimination is performed, the numerical aperture (N
It is assumed that A) is in a fixed state on either one.

However, according to the present invention, the disc type may be determined after switching the numerical aperture (NA) and performing the focus forcible operation twice consecutively. That is, the numerical aperture (NA)
Then, in each case, the forcible focus operation is performed to obtain the first and second waveform information corresponding to the first and second focus error signals. And the first
If the second waveform information indicates the relationship between A1 and B1 in FIG. 3, the mounted disc is the DVD 1 layer, and the A in FIG.
If the relationship is between 2 and B2, the mounted disk is DV
It is a D2 layer, and if the relationship between A3 and B3 in FIG. 3 is satisfied, it is determined that the mounted disk is a CD. There is no need to rotate the disk in this determination.

According to the actual operation flow chart, the focus forcible operation step A and the feature determination step S5 in FIG. 4 are performed plural times (in this case, two times) continuously by switching the NA. In each case, waveform information of a focus response signal (a focus error signal or a sub beam sum signal, or both of them) is obtained. Then, in step S6, a combination of the A-system waveform and the B-system waveform in FIG. 3 is searched from the first and second waveform information, and the DVD 1 layer, the DVD 2 layer, and the CD are determined.

FIG. 5 shows a procedure for specifically switching the NA to obtain a focus response signal in each case and determining the disc type based on the waveform information of the focus response signal.

That is, when the apparatus is in a star state, the disk rotation is forcibly turned off as the disk rotation servo off and the tracking servo off (steps r1 and r2).
2). Further, in step r3, NA is set to, for example, DVD
Set the mode. Next, the focus servo is forcibly operated to control the focus state, and the focus is controlled, for example, in the direction from the far side to the near side of the disk surface (step r4). In parallel with this control, acquisition of waveform information of the focus response signal (focus error signal and / or sub-beam sum signal) is performed in step r5. There are various examples of this waveform information acquisition, which will be described in more detail later. If this waveform information is obtained for the first time, NA is set to CD
Mode (steps r6 and r7) and step r
4 and the acquisition of the second waveform information is performed again. When the first and second waveform information are completed, the process proceeds to step r8, and the combination of the first and second waveform information is represented by A in FIG.
1 and B1 (DVD 1 layer), A2 and B2 in FIG. 3 (DVD 2 layer), A3 and B3 in FIG.
(CD) is determined. Finally, disc discrimination and NA determination are performed (step r9).

FIG. 6 shows an example of the processing in steps S5 and S6 shown in FIG. 4 in detail. This example
This is an example in which the disc type is determined using only the focus error signal FE. It is known in advance that the focus error signal FE takes a pattern as shown in FIG. 3 according to each setting condition. Therefore, it is possible to determine the type of the currently mounted disk, for example, using the characteristics of this pattern and the output level of the focus error signal as the determination requirements.

At step T1, the focus error signal FE is captured. Then, the peak value P and the bottom value B of the focus error signal FE are detected (step T2). Next, it is determined whether or not there are two peak values P and two bottom values B (step T3). When there are two peak values P and two bottom values B, A in FIG.
There is a high possibility that the pattern is one of patterns 2 and B2. Therefore, it is determined whether or not the current NA is in the DVD mode (step T4).
B) It is determined whether or not ≧ Y1 (pattern A2 in FIG. 3) (step T5). If this condition is satisfied, it is determined that the currently mounted disc is a DVD and a two-layer disc. If the apparatus is set to the CD mode in step T4,
7, (P + B) ≧ Y2 (B2 pattern in FIG. 3)
Is determined. If this condition is satisfied, the currently mounted disc is a DVD and 2
It is determined that the disc is a layer disc. If the conditions are not satisfied in steps T5 and T7, a warning may be issued or the determination routine may be switched to another method.

If there is one peak value P and one bottom value B in step T3, A1 and B in FIG.
1, there is a high possibility that the pattern is one of A3 and B3. Therefore, it is determined whether or not the current NA is in the DVD mode (step T8).
It is determined whether (P + B) ≧ Y3 (A1 pattern in FIG. 3) (step T9). If this condition is satisfied, it is determined that the currently mounted disk is a DVD and a single-layer disk (step T10).
If the condition is not satisfied in step T9,
The measured pattern is determined to be the pattern of A3 in FIG. 3, and the currently mounted disk is determined to be a CD. If the apparatus is set to the CD mode in step T8, (P + B) ≧≧ in step T11.
It is determined whether it is Y4 (the pattern of B3 in FIG. 3). If this condition is satisfied, it is determined that the currently mounted disk is a CD (step T12).
If the conditions are not satisfied, the measured pattern is shown in FIG.
Is determined to be the B1 pattern, and the currently mounted disk is determined to be a DVD.

The above method is a disk determination method using a pattern of a focus error signal, but may be a disk determination method using a sub-beam sum signal. Needless to say, the processing up to step T3 can be used for the processing for acquiring waveform information in FIG.

FIG. 7 shows an example of a disc determination method using the sub-beam sum signal SBAD. Step U1
Captures the sub-beam sum signal. Step U2, U
At 3, it is determined whether three or more peak values and bottom values exist in the sub-beam sum signal (waveform determination of A2 and B3 in FIG. 3). If three or more peak values and bottom values exist, it is determined that the disc is a DVD two-layer disc in any case.

If three or more peak values and bottom values do not exist, it is determined in step U5 whether the current mode is the DVD mode. In the case of the DVD mode, the difference (Z) between the first peak value and the second peak value is calculated in step U6. That is, A1 and A3 in FIG.
As shown in the figure, in the case of the DVD mode, two peak values appear in the SBAD, but when the mounted disk is a DVD, the difference between the two peak values is small, and the mounted disk is a CD. In this case, the fact that the difference between the two peaks is large is used. When the difference is small (Z <Y1
0), the mounted disk is determined to be a single-layer DVD (step U8), and if the difference is large, the mounted disk is determined to be a CD (step U9).
I do.

In the previous step U5, the current device is C
If the D mode is set, it is determined whether the bottom value is larger than a predetermined level (step U1).
0). That is, as seen in B1 and B3 of FIG.
When a CD is mounted in D mode, SB
The bottom value of AD (B3 in FIG. 3) is larger than the bottom value (B1 in FIG. 3) when a DVD is mounted. By utilizing this fact, when the bottom value is larger than Y11, it is determined that the currently mounted disc is a CD, and when the bottom value is smaller than Y11,
It is determined that the currently mounted disk is a DVD. Of course, the processing up to step U3 can be used for the processing for acquiring the waveform information in FIG.

In the above description of FIG. 7, the disc discrimination method using the sub-beam sum signal is described. The disc discrimination method using the pattern of the focus error signal described in FIG. 6 and the disc discrimination method of FIG. It is needless to say that the final disc judgment result may be obtained by ANDing the judgment results of the two in parallel or serially in combination.

FIG. 8 shows yet another disc determination method. In this disc determination method, one or both of the focus error signal FE and the sub beam sum signal SBAD are extracted by sampling, and their waveform patterns are recognized (step V1). When the pattern recognition is completed, it is determined whether the current mode is the DVD mode or the CD mode (step V2). If the mode is the DVD mode, the process proceeds to step V3. In this step V3, the previously stored waveform patterns A1 to A3 in FIG. 3 are compared with the measured waveform pattern, and the most similar waveform is determined. As a result, a determination result as to whether the currently mounted disk is a DVD or a CD can be obtained. If it is determined in step V2 that the mode is the CD mode, the process proceeds to step V4.
In this step V4, the previously stored B in FIG.
Each of the waveform patterns 1 to B3 is compared with the measured waveform pattern, and the most similar waveform is determined. As a result, a determination result as to whether the currently mounted disk is a DVD or a CD can be obtained.

According to this method, even if the number of discs increases, the disc determination can be easily performed by storing the waveform pattern obtained by measuring the focus error signal and / or the sub-beam sum signal under a certain condition in the collation memory. It can be carried out. That is, in the method shown in FIG. 8, even when the types of disks are increased, it is possible to determine the disk without changing the design. Needless to say, the processing in step V1 can be used for the processing for acquiring the waveform information in FIG.

(A) As described above, the system of the present invention can discriminate between a CD and a DVD without reading information written on a disk. Then, the focus servo is forcibly controlled, and the focus error signal obtained at this time is effectively used. The focus error signal is obtained, and the discrimination between the CD and the DVD is performed based on the feature of the pattern of the focus error signal. Is going.

(B) In the system of the present invention, a system in which the laser wavelength used in the pickup device is 650 nm or 630 nm and which can be commonly used for CD and DVD is used. On the other hand, there is a disc (CD-R) which is prepared by using a dye having the highest sensitivity to a 780 nm laser and which can write data by the heat of the laser. This CD-R greatly depends on the recording wavelength not only for reproduction but also for recording. Therefore, with a 650 nm or 630 nm laser used for reproducing a DVD, writing may occur even with a small amount of power, and data may be destroyed.

The system of the present invention has a safety measure so that unnecessary writing is not performed even when such a disk is erroneously mounted on a reproducing apparatus. That is, when the CD-R is erroneously mounted and, for example, a 650 nm laser is irradiated on the CD-R, reflection is not obtained, heat is generated, and data may be destroyed. However, in the present invention, the type of the disc is determined in a state where the rotation of the disc is forcibly stopped. For this reason, even if the apparatus of the present invention is operated with the above-mentioned CD-R mounted, there is no reflection and there is only one laser spot, so that data destruction can be minimized. With only one point of data destruction, no problem occurs in the signal reproduction processing. This is because the recording data is interleaved.

(C) In addition, the present invention is also effective in principle for a rewritable disk such as a CD-E by heating a laser. When such a disk is rotated slowly, it is conceivable that writing is performed even with the laser light having the power of 650 nm or 630 nm as described above, and data is destroyed. However, in the system of the present invention, the type of the disk is determined in a state where the rotation of the disk is forcibly stopped as described above. For this reason, even if the apparatus of the present invention is operated with the above-mentioned CD-E mounted thereon, data destruction can be minimized because there is only one laser spot.

(D) Next, the focus servo system is forcibly performed an operation different from the normal operation to obtain a focus error signal. When the focus control operation of the pickup device is forcibly executed, the risk of collision of the objective lens is prevented.

First, the movement of the objective lens is controlled in a direction from a position far from the optical disk to a position close to the optical disk. Then, the forced focus search means (program) at this time is constructed so as to be retracted (moved away from the disk) as soon as the focus error signal is detected. In this forced focus search, even if a focus point is detected, control is performed to bring the disk closer to the disk in order to confirm its waveform, and there is a high risk of collision between the disk and the objective lens. In particular, as DVD devices become smaller and thinner,
The possibility of collision between the disc and the objective lens increases. Therefore, in the present invention, as soon as a desired focus error signal is detected, the focus error signal is retracted to obtain safety.

(E) In the present invention, detection of a two-layer DVD is also assumed. For this reason, there is a possibility that the objective lens is moved closer to the optical disk until a plurality of peak values of the focus error signal are obtained. However, if the optical disk actually mounted is a single-layer optical disk, a plurality of peak values of the focus error signal cannot be obtained no matter how close the objective lens is to the disk. If no measures are taken in such a case, the objective lens may collide with the disk and be damaged. Therefore, in the present invention, after the first focus error signal waveform (S-shaped waveform) is detected, the objective lens is gradually moved closer to the disk. When the second focus error signal waveform (S-shaped waveform) is not found even after a predetermined time has elapsed, it is determined that the layer is a single layer, and the focus servo is forcibly stopped.

(F) In the present invention, when the above-mentioned forced focus control for disc discrimination is completed, the state immediately shifts to a normal focus servo state. In this case, in order to obtain an efficient servo lock, a control signal for driving the objective lens is transmitted in a direction completely opposite to the driving direction in the forced focus control. This is, as can be seen from the above description, the objective lens has moved past the focal position with respect to the disk and is closer to the disk. This is because it is clear that the focal position of the objective lens with respect to the optical disk exists at a position where the objective lens is controlled in a direction away from the disk.

FIG. 9 shows another example of the disc discriminating means of the present invention. Now, the NA is set to the DVD mode, and the rotation of the disk is stopped. The focus is forcibly controlled, and the peak value and the bottom value of the focus error signal are detected (steps R1, R2, R3). Here, the ratio of the difference component (P−B) between the peak value P and the bottom value B and the sum component (P + B) of the peak value P and the bottom value B is calculated (step R4). And this ratio is ｛(P-
B) / (P + B)｝> W1 is determined, and if so, the CD is determined to be a CD (step R5). Conversely, {(P-B) / (P + B)}> W
If the condition of 1 is not satisfied, the flow shifts to step R6 to determine whether or not two S-shaped cycles exist as the focus error signal. If there are two DVDs, it is determined that the DVD has two layers (step R8). If there are no two S-shaped cycles, it is determined that the DVD is a single layer (step R7). The processes up to steps R4 and R6 can be used for the process for acquiring the waveform information in FIG.

FIG. 10 is a diagram showing still another example of the disk determining means of the present invention. Now, the NA is set to the DVD mode, and the rotation of the disk is stopped. The focus is forcibly controlled, and the peak value FP, the bottom value FB of the focus error signal, and the peak value S of the sub beam sum signal are obtained.
P and the bottom value SB are detected (steps q1, q2,
q3). Next, the process proceeds to step q4, for example, (FP
+ FB) / {(SP + SB) / 2}, and it is determined whether the result of this calculation is smaller than W2. When the mounted disk is a CD, this value is very small as can be seen from the waveforms of FIG. Therefore, if the calculation result in step q4 is smaller than W2, it is determined that the loaded disk is a CD (step q5). Conversely, if the operation result is larger than W2 in step q4, the process proceeds to step q6. In step q6, it is determined whether or not two S-shaped cycles exist as the focus error signal. If there are two DVDs, it is determined that the DVD has two layers (step q8). If there are no two S-shaped cycles, it is determined that the DVD is one layer of the DVD (step q7). The processes up to steps q4 and q6 can be used for the process for acquiring the waveform information in FIG.

[0074]

As described above, according to the present invention,
The disc type can be determined without using information recorded on the disc. Further, according to the present invention, it is possible to determine the disc type on a writable optical disc without erroneous writing. Further, according to the present invention, the type of a rewritable optical disk can be determined without causing an error. According to the present invention, discrimination between a single-layer disc and a double-layer disc can be obtained together with disc type discrimination. Further, according to the present invention, the safety of the optical pickup device can be obtained in the discrimination operation of the disc type. Further, according to the present invention, after the disc type is determined, the process can smoothly proceed to the reproduction signal processing.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical disk reproducing device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an optical pickup device and an error signal generator of FIG. 1;

FIG. 3 is a diagram showing pattern examples in various cases of a focus error signal and a sub-beam sum signal.

FIG. 4 is a diagram showing an example of a disk type determination procedure.

FIG. 5 is a diagram showing still another example of a disk type determination procedure.

FIG. 6 is a diagram showing an example of a feature detection procedure in disc type determination.

FIG. 7 is a diagram showing another example of a feature detection procedure in disc type determination.

FIG. 8 is a diagram showing still another example of a feature detection procedure in disc type determination.

FIG. 9 is a diagram showing still another example of a feature detection procedure in disc type determination.

FIG. 10 is a diagram showing still another example of a feature detection procedure in disc type determination.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Optical disk 12 ... Disk motor 21 ... Optical pickup device 22 ... Preamplifier 23 ... Equalizer 24 ... Data slicer 25 ... Data extraction part 26 ... Data processing part 28 ... Disk servo circuit 31 ... Error signal generator 32 ... Focus Servo circuit 33 Tracking servo circuit 34 Feed motor servo circuit 41 Focus error signal processing circuit 42 Sum signal processing circuit 43 Disk discrimination circuit.

Claims (20)

[Claims] 1. A plurality of optical systems having different numerical apertures (NA), and a photoelectric conversion unit that optics the surface of an optical disk using any one of the plurality of optical systems and receives reflected light thereof, Focus control means for controlling the focus state of the optical system irradiating the optical beam in accordance with the output of the photoelectric conversion means, and forcibly causing the focus control means to stop rotating the optical disc. Determining means for operating in a predetermined state, obtaining a focus response signal of the photoelectric conversion means obtained by changing with this operation, and obtaining an optical disk type determination output according to the content of the level change of the focus response signal; An optical disk recording / reproducing apparatus comprising: 2. An optical disk recording / reproducing apparatus according to claim 1, wherein said focus control means is forcibly operated in a state in which said optical system having the largest NA is used. 3. The optical disk recording / reproducing apparatus according to claim 1, wherein the focus response signal of the photoelectric conversion means is a focus error signal. 4. The photoelectric conversion means includes a quadrant detector and two sub-detectors arranged so as to sandwich the quadrant detector, and the focus response signal is an output of the quadrant detector. 2. The optical disk recording / reproducing apparatus according to claim 1, wherein the optical disk recording / reproducing apparatus is a focus error signal created by using the method. 5. The photoelectric conversion unit includes a four-divided detector and two sub-detectors arranged so as to sandwich the four-divided detector, and the focus response signal is obtained from the sub-detector. 2. The optical disk recording / reproducing apparatus according to claim 1, wherein the signal is a sub-beam sum signal of the signals. 6. The photoelectric conversion means includes a quadrant detector and two sub-detectors arranged so as to sandwich the quadrant detector, and the focus response signal is an output of the quadrant detector. 2. The optical disk recording / reproducing apparatus according to claim 1, wherein the optical disk recording / reproducing apparatus comprises a focus error signal created by using a sub-detector and a sum signal of signals obtained from the sub-detectors. 7. The optical disk recording / reproducing apparatus according to claim 1, wherein the plurality of optical systems having different numerical apertures (NA) have different lenses. 8. The optical system according to claim 1, wherein the plurality of optical systems having different numerical apertures (NA) are configured so as to constitute a plurality of optical systems having different numerical apertures (NA) by switching a stop. Item 2. An optical disk recording / reproducing apparatus according to Item 1. 9. The optical system according to claim 1, wherein the plurality of optical systems having different numerical apertures (NA) have a structure in which a plurality of optical systems having different numerical apertures (NA) are formed by having two or more focal points. The optical disk recording / reproducing apparatus according to claim 1, wherein 10. The optical disk recording / reproducing apparatus according to claim 1, wherein said optical disk has either a substrate of about 1.2 mm or a substrate of about 0.6 mm. 11. The optical disk according to claim 1, wherein said determination means uses a peak value and a bottom value of said focus response signal output from said photoelectric conversion means as the contents of said level change. Recording and playback device. 12. The optical disk recording / reproducing apparatus according to claim 1, wherein said determination means uses amplitude information of said focus response signal output from said photoelectric conversion means as the content of said level change. . 13. The apparatus according to claim 1, wherein said determination means uses a plurality of peak values and a plurality of bottom values of said focus response signal output from said photoelectric conversion means as the contents of said level change. 2. The optical disk recording / reproducing apparatus according to 1. 14. The optical disk recording / reproducing apparatus according to claim 1, wherein said determination means uses pattern information of said focus response signal output from said photoelectric conversion means as the contents of said level change. . 15. The optical disk recording / reproducing apparatus according to claim 1, wherein the focus response signal is a signal obtained by irradiating a surface of the optical disk near a radius of 23 mm to 24 mm with a beam. 16. The apparatus according to claim 16, further comprising a disk rotation servo system, wherein the disk rotation servo system is substantially turned off until the determination means operates, thereby realizing rotation stop of the optical disk. The optical disk recording / reproducing apparatus according to claim 1. 17. An optical disk recording / reproducing apparatus according to claim 1, wherein said focus control means is forcibly operated in a state in which said optical system having the smallest NA is used. 18. A photoelectric conversion means for irradiating an optical disk surface with an optical beam through an optical system and receiving reflected light thereof, and a focus of said optical system for irradiating said optical beam with said photoelectric conversion means. Focus control means for controlling using an output, in a state where the rotation of the optical disc is stopped, the focus control means is forcibly operated to enter a focus search mode, and as the focus control means performs focus control, A focus response signal from the photoelectric conversion means obtained by changing the focus response signal is obtained, and from the time when the focus response signal indicates the first predetermined focus state,
An optical disc recording / reproducing apparatus, comprising: a focus search means for turning off the focus search mode when the second predetermined focus state is not achieved within a predetermined time. 19. The focus search means acquires the focus response signal while moving the optical system from a position far from the optical disk to a position close to the optical disk via the focus control means, and obtains the second predetermined focus state. 19. The optical disk recording / reproducing apparatus according to claim 18, wherein if not, the optical system is controlled to move away from the optical disk. 20. The focus search means acquires the focus response signal while moving the optical system from a position far from the optical disc to a position close to the optical disc via the focus control means, and the judging means judges the disc type. 20. The optical disk recording / reproducing apparatus according to claim 19, wherein after performing the operation, the forced operation of the focus control unit is released while controlling the optical system to move away from the optical disk.