JP4216027B2 - Optical disk device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc apparatus, and more particularly, to an optical disc apparatus capable of determining whether an optical disc loaded in the apparatus is a read-only optical disc or a recordable optical disc.
[0002]
[Prior art]
An optical disc such as a DVD is widely used as a medium for recording digital works such as AV (Audio Video) data and computer data. Optical discs are broadly classified into read-only discs and recordable discs. Recordable discs are made for the purpose of recording within a range that does not infringe on copyrights, but they are used for illegally copying digital works and may lead to the spread of illegal discs. In order to prevent this, the optical disc apparatus must discriminate between a read-only disc and a recordable disc, and when a recordable disc is loaded, it is necessary to perform an appropriate process for protecting the copyright. In order to prevent erroneous discrimination due to falsification of the recordable disc, it is necessary to detect and discriminate the physical structure difference between the read-only disc and the recordable disc.
[0003]
Hereinafter, the difference in physical structure between the read-only disc and the recordable disc will be described with reference to the drawings.
[0004]
FIG. 1A is a perspective view in which a part of a recording surface of a read-only disc is cut out, and two adjacent recording tracks 140 are enlarged and displayed.
[0005]
In the read-only disc shown in FIG. 1A, pits 141 and spaces 142 are arranged along a spiral recording track 140 on a mirror-like recording surface. The pit 141 is a portion (a concave portion or a convex portion) displaced in a direction perpendicular to the mirror-like recording surface, and is formed in an embossed shape. The space 142 is a mirror surface portion on which the pit 141 is not formed on the recording track 140. Information is recorded by an array of pits 141 and spaces 142.
[0006]
FIG. 1B is a perspective view in which a part of the recording surface of the recordable disc is cut out, and two adjacent grooves 143 are enlarged and displayed. The groove 143 is formed on the recording track.
[0007]
In the recordable disc shown in FIG. 1B, recording marks 144 and spaces 145 are arranged along the groove 143. The groove 143 is formed in a spiral shape or a concentric shape on the optical disc. Although not clearly shown in FIG. 1B, a recording film is formed on the optical disc. As the recording film, a phase change recording film whose refractive index changes by irradiation of a writing laser pulse or an organic dye film whose light absorption rate changes are widely used. The recording mark 144 is a portion where a phase change or the like of the recording film is locally generated by laser pulse irradiation, and is formed to be rewritable. Since the reflectance with respect to the reading laser beam is different between the portion where the recording mark 144 is formed and the space 145 portion, the reading laser beam is irradiated onto the groove, and the intensity of the reflected light (the amount of reflected light) ) Is detected, it is possible to detect the arrangement state of the recording marks 144 and the spaces 145. Thus, information on the recordable disc is recorded at any time by the arrangement of the recording mark 144 and the space 145.
[0008]
As described above, there is a physical structure difference on the recording surface between the read-only disc and the recordable disc, and the groove exists only in the recordable disc.
[0009]
Japanese Patent Application Laid-Open No. 2005-228561 discloses a technique for discriminating between a recordable disc and a read-only disc by focusing on a groove that exists only on a recordable disc and detecting the presence or absence of the groove.
[0010]
The groove detection method disclosed in Patent Document 1 will be described with reference to FIG. FIG. 2 shows a configuration of an apparatus used for groove detection of the optical disk apparatus.
[0011]
In the configuration shown in FIG. 2, the photodetector (PD) 200 divided into regions A, B, C, and D receives the light beam reflected from the optical disc, and photoelectric conversion is performed in each region A, B, C, and D. As a result, four types of electrical signals are output according to the intensity (light quantity) of light incident on each of the regions A, B, C, and D.
[0012]
The electric power output from the four areas A, B, C, and D of the photodetector 200
The air signal is input to the adder circuit 201. The adder circuit 200 adds all these electric signals and outputs an RF signal.
[0013]
The RF signal output from the adder circuit 201 is input to the sample hold (SH) circuit 202. The sample hold circuit 202 samples and holds the RF signal output from the adder circuit 201, and generates a peak hold signal.
[0014]
A peak hold signal output from the sample hold circuit 202 is input to a low pass filter (LPF) 203. The low pass filter 203 removes the high frequency component of the peak hold signal output from the sample hold circuit 202 and generates an upper envelope signal.
[0015]
FIG. 3A shows a waveform example of the RF signal H and the upper envelope signal I obtained when a recordable disc is loaded, and FIG. 3B is obtained when a read-only disc is loaded. 2 shows waveform examples of the RF signal H and the upper envelope signal I. FIGS. 3A and 3B show the waveforms of the RF signal H and the upper envelope signal I obtained when the light beam spot on the optical disk crosses the recording track of the optical disk. The RF signal H is a signal output from the adder circuit 201 in FIG. The envelope signal I is a signal output from the low-pass filter 203 in FIG. 2, and the waveform of the envelope signal I is equal to the shape of the upper envelope of the RF signal H.
[0016]
As shown in FIG. 3A, when a recordable disc is loaded on the optical disc, the amount of reflected light changes due to the diffraction of light by the groove when the light beam spot crosses the recording track. For this reason, the upper envelope of the RF signal H varies at a frequency corresponding to the number of grooves traversed by the light beam spot per unit time, and the upper envelope I also varies at that frequency.
[0017]
When a read-only disc is loaded in the optical disc apparatus, no groove is formed on the recording surface of the optical disc. Therefore, even if the light beam spot crosses the recording track, as shown in FIG. The upper envelope of signal H hardly fluctuates. Therefore, the envelope signal I hardly changes.
[0018]
In the optical disc apparatus described in Patent Document 1, attention is paid to the fact that the difference between the upper envelope signal I obtained from the recordable disc and the reproduction-only disc due to the presence or absence of the groove, and the disc is detected by detecting this difference. It is discriminating.
[0019]
[Patent Document 1]
JP 2001-28159 A
[Patent Document 2]
JP 2001-357533 A
[0020]
[Problems to be solved by the invention]
However, according to the above prior art, the disc is discriminated based on the total amount of light received by the photodetector, so that the envelope signal depends on the shape of the light beam spot on the optical disc and the configuration of the light quantity distribution groove. In some cases, it is difficult to determine the presence or absence of an optical disk groove. The shape of the light beam spot and the light amount distribution differ depending on the configuration of the optical system of the optical head and the design of the optical disk, and are also affected by the tilt of the light beam with respect to the optical disk and the focus position shift. For this reason, the above-described conventional technology cannot obtain sufficiently high reliability for the determination of the presence or absence of the groove.
[0021]
The present invention has been made in view of such circumstances, and accurately detects the difference in the surface form of the optical disk without being affected by the difference in the shape of the light beam spot and the distribution of the light quantity. It is an object of the present invention to provide an optical disc apparatus and a driving method thereof that can accurately discriminate the above.
[0022]
[Means for Solving the Problems]
  An optical disc apparatus according to the present invention is an optical disc apparatus capable of loading an optical disc arbitrarily selected from a plurality of types of optical discs including a first optical disc having a groove and a second optical disc not having a groove. An optical system for irradiating a recording surface of the optical disc with a laser beam, a first output signal corresponding to the amount of light of at least a part of the light reflected from the inner peripheral side of the optical disc received from the optical disc; , A light detection unit for generating a second output signal corresponding to the amount of light of at least part of the light reflected from the outer peripheral side of the optical discAndThe first output signal indicates whether the optical disk being filled has a groove or not.High light intensity sideOf the envelope signal and / or the second output signalHigh light intensity sideA disc discriminating unit for judging based on the envelope signal.
[0023]
In a preferred embodiment, the first optical disc is a recordable optical disc having a recording film, and the second optical disc is a read-only optical disc having a plurality of pits formed along the recording track.
[0024]
In a preferred embodiment, the light detection unit receives reflected light from the optical disc, and divides the light of the portion irradiated with the laser light into at least two tangential directions of the recording track from the optical disc. The reflected light is divided and a signal corresponding to each light quantity is output.
[0025]
  In a preferred embodiment, the disc discriminating unit receives the first output signal or the second output signal, and the received signal is high.Light intensityDetecting the maximum amount of received light by performing peak detection on the side,High light intensity sideA peak detection circuit for generating an envelope signal; andHigh light intensity sideAnd an amplitude detection unit that detects the AC amplitude of the envelope signal.
[0026]
  In a preferred embodiment, the disc discriminating unit receives the first output signal and the second output signal, and sets a high level for each received output signal.Light intensitySide peak detection is performed to detect the maximum amount of received light, and the first output signalHigh light intensity sideThe envelope signal and the second output signal.High light intensity sideA peak detection circuit for generating an envelope signal; and the first output signalHigh light intensity sideThe envelope signal and the second output signal.High light intensity sideA difference detection unit that detects a difference between envelope signals; and an amplitude detection unit that detects an AC amplitude of a signal output from the difference detection unit.
[0027]
In a preferred embodiment, an amplitude normalization unit that normalizes an output signal of the amplitude detection unit based on an extreme value of the reflected light amount among the extreme values of the signal output from the peak detection circuit is further provided. Yes.
[0028]
In a preferred embodiment, the peak detection circuit includes a first output signal corresponding to the total amount of light reflected from the inner peripheral side of the optical disc and / or the total amount of light reflected from the outer peripheral side of the optical disc. A second output signal corresponding to the amount of light is received, and peak detection of the higher reflected light amount of the first output signal and / or the second output signal is performed.
[0029]
In a preferred embodiment, the apparatus includes a tracking error detection unit that outputs a tracking error signal corresponding to a deviation between the irradiation position of the laser beam and the center of the recording track based on an output signal of the light detection unit, and the amplitude The detection unit includes a synchronous detection unit that detects an amplitude of a component synchronized with an output signal of the tracking error detection unit among output signals of the peak detection circuit, and outputs an output of the synchronous detection unit as the AC amplitude To do.
[0030]
In a preferred embodiment, the amplitude detection unit includes a maximum / minimum value detection unit that detects a maximum value and a minimum value of an output signal of the peak detection circuit within a predetermined first time, and the maximum / minimum value detection unit. And a maximum and minimum value difference detecting unit that detects a difference between the maximum value and the minimum value detected by the signal, and outputs an output of the maximum and minimum value difference detecting unit as the AC amplitude.
[0031]
In a preferred embodiment, the maximum small value detection unit detects a maximum value and a minimum value of the output signal of the peak detection circuit every second time obtained by dividing the predetermined first time into a plurality of times. A divided maximum / small value detecting unit, and an average value detecting unit that detects an average value of a plurality of maximum values and an average value of a plurality of minimum values detected by the divided maximum / small value detecting unit, wherein the average value detecting unit The average value of the plurality of maximum values to be output and the average value of the plurality of minimum values are set as the maximum value and the minimum value within a defined first time of the output signal of the peak detection circuit.
[0032]
In a preferred embodiment, the average value detection unit includes a plurality of maximum values and minimum values or a maximum value and a minimum value among the plurality of maximum values detected by the divided maximum / small value detection unit, and a plurality of the values are ordered in magnitude. The average value of the plurality of maximum values and the plurality of minimum values is detected by excluding the value and the maximum value and the minimum value or the plurality of minimum values and the maximum value and the minimum value among the plurality of minimum values.
[0033]
In a preferred embodiment, there is provided a crossing time detector for detecting a time when the irradiation position of the laser light on the optical disk crosses the recording track a predetermined number of times from a certain time based on an output signal of the light detector. Then, the maximum small value detection unit sets the determined first and second times as the time for the crossing time detection unit to output.
[0034]
In a preferred embodiment, the peak detection circuit includes a circuit element that blunts the waveform of the first output signal and / or the second output signal output from the light detection unit.
[0035]
  In a preferred embodimentThe disc discriminating unitThe irradiation position of the laser beam by the eccentricity of the rotating optical diskButOffset from the center of the recording trackIt is determined whether or not the optical disk loaded has a groove based on the high light amount side envelope signal during the recording.
[0036]
  In certain preferred embodiments,in frontThe irradiation position of the laser beam on the optical disk is moved in the radial direction of the optical disk.An irradiation position control unit, and the disc determination unit is configured to be the irradiation position control unit.By the irradiation position of the laser beamButOffset from the center of the recording trackIt is determined whether or not the optical disk loaded has a groove based on the high light amount side envelope signal during the recording.
[0037]
In a preferred embodiment, the reproduction control unit includes a reproduction control unit that determines permission / non-permission of reproduction of the optical disc based on an output of the disc determination unit, and the reproduction control unit reproduces the loaded optical disc. When the disc discriminating unit discriminates that the disc is a dedicated optical disc, the optical disc is allowed to be played back. When the disc discriminating unit discriminates that the loaded optical disc is a recordable optical disc, the optical disc is played back. Is not allowed.
[0038]
In a preferred embodiment, information recorded on the recordable optical disc is legally recorded or illegal when the disc discriminating unit determines that the loaded optical disc is a recordable optical disc. A recording status detection unit for detecting whether the data is recorded on the screen.
[0039]
In a preferred embodiment, a playback control unit that determines permission / non-permission of playback of the optical disc based on an output of the disc determination unit and an output of the recording status detection unit, the playback control unit, When the disc discriminating unit discriminates that the loaded optical disc is a read-only optical disc, or the disc discriminating unit discriminates that the loaded optical disc is a recordable optical disc, and When the recording status detection unit detects that the recording of information is legal, the optical disc is allowed to be reproduced, the disc discriminating unit discriminates that the disc discriminating unit is a recordable optical disc, and the When the recording state detection unit detects that the recording of information on the recordable disc is illegal, the optical disc is reproduced. Not allowed.
[0040]
  An optical disc apparatus according to the present invention is an optical disc apparatus in which an optical disc arbitrarily selected from a plurality of types of optical discs having different disc recording surface shapes can be loaded, and irradiates a recording surface of the loaded optical disc with laser light. A first output signal that receives light reflected from the optical system and the optical disk and is reflected from the inner periphery of the optical disk, and light reflected from the outer periphery of the optical disk; A light detection unit for generating a second output signal corresponding to at least a part of the light amount of,in frontThe first output signalHigh light intensity sideOf the envelope signal and / or the second output signalHigh light intensity sideA disc discriminating unit for discriminating the type of the loaded optical disc based on the envelope signal;
[0041]
  The driving method of the optical disc device according to the present invention is a driving method of an optical disc device in which an optical disc arbitrarily selected from a plurality of types of optical discs including a recordable disc having a groove and a read-only disc not having a groove can be loaded. Irradiating the recording surface of the loaded optical disc with laser light, and receiving a reflected light from the optical disc, and a first output corresponding to at least a part of the light reflected from the inner peripheral side of the optical disc Generating a second output signal corresponding to the signal and the amount of light of at least a part of the light reflected from the outer peripheral side of the optical disc;TheThe first output signal indicates whether the optical disk being filled has a groove or not.High light intensity sideOf the envelope signal and / or the second output signalHigh light intensity sideDetermining based on the envelope signal.
[0042]
In a preferred embodiment, if it is determined that the loaded optical disc is a read-only disc, the optical disc is allowed to be played back,
When it is determined that the loaded optical disc is a recordable disc, the method further includes a step of not permitting reproduction of the optical disc.
[0043]
In a preferred embodiment, when it is determined that the loaded optical disc is a recordable optical disc, the information recorded on the recordable optical disc is legally recorded or illegally recorded. In the case where the recording is illegally performed, the optical disc is not reproduced.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 4 shows a configuration example of an optical head used in the optical disc apparatus of the present invention. The illustrated optical head 8 is a unit on which an optical system including a semiconductor laser 3, a collimating lens 4, a beam splitter 5, an objective lens 6, and a photodetector 7 is mounted.
[0045]
FIG. 4 schematically shows a cross-section in a state where the optical disc 1 is loaded in the optical disc apparatus. The loaded optical disc 1 is rotated by the motor 2.
[0046]
The semiconductor laser 3 of the optical head 8 outputs a light beam for irradiating the optical disk 1, and the collimating lens 4 converts the light beam output from the semiconductor laser 3 into parallel light. The beam splitter 5 allows the parallel light emitted from the collimator lens 4 to pass to the objective lens 6 and separates the parallel light emitted from the objective lens 6 (reflected light from the optical disk 1) in a direction in which the photodetector 7 is located. The objective lens 6 collects the parallel light that has passed through the collimating lens 4 and the light beam splitter 5 to form a light beam spot on the recording surface of the optical disc 1. The objective lens 6 converts the light reflected by the optical disk 1 into parallel light and emits it to the beam splitter 5.
[0047]
The photodetector 7 receives the parallel light emitted from the beam splitter 5 and outputs an electric signal proportional to the intensity (light quantity) of the received light. This electrical signal is referred to herein as an “RF signal” because it includes a high frequency (RF) component that includes information recorded along the recording track. The photodetector 7 is divided into a plurality of detection areas, similarly to the known photodetector described with reference to FIG. 2, and can separately detect the intensity of light incident on different detection areas.
[0048]
When the recording surface of the optical disk is irradiated with the light beam, the light beam is reflected by the optical disk, and the intensity distribution of the reflected light beam (in-plane distribution perpendicular to the optical axis) is the irradiation position of the light beam on the optical disk (light beam spot). Depending on the position). The photodetector 7 is configured so that the intensity of two regions (inner and outer sides) divided along the tangential direction of the recording track can be detected separately for such a reflected light beam.
[0049]
From the photodetector 7 having such a configuration, an inner peripheral side RF signal and an outer peripheral side RF signal are output. The inner peripheral side RF signal is a signal proportional to the amount of light reflected by the inner peripheral portion of the disc when the light beam spot on the optical disc 1 is divided into two portions in the recording track tangential direction. On the other hand, the outer peripheral side RF signal is a signal proportional to the amount of reflected light at the outer peripheral portion of the disc when the light beam spot on the optical disc 1 is divided into two portions in the recording track tangential direction.
[0050]
In the prior art described above, the presence / absence of a groove on the optical disk is detected based on the sum of the RF signals output from the photodetector. In the present invention, the output of the photodetector 7 is determined based on the inner peripheral RF signal and the outer peripheral RF signal. The signal is separated, and the presence or absence of a groove on the optical disc 1 is detected based on the inner peripheral RF signal or the outer peripheral RF signal, or the difference between these RF signals. The envelope signal shown in FIG. 3 is the upper envelope signal of the total RF signal output from the photodetector, but the amplitude of this signal may be very small depending on the situation and is not stable. On the other hand, the upper envelope signal of the inner periphery side RF signal and the upper envelope signal of the outer periphery side RF signal used in the optical disc apparatus of the present invention have a large amplitude and are stable as will be described in detail later.
[0051]
Before explaining how to detect the presence or absence of a groove in the optical disc 1 in the optical disc apparatus of the present invention, first, referring to FIG. 5 and FIG. The waveform will be described in detail.
[0052]
FIG. 5 shows how the light beam spot traverses the recording track of the read-only disc and the outer and inner peripheral side RF signal waveforms obtained at that time. The upward direction of the waveform corresponds to the direction in which the amount of reflected light is high.
[0053]
In FIG. 5, three adjacent recording tracks 120 are enlarged and pits 121 are formed on the recording track 120. Also shown is a light beam spot trajectory 122 that crosses three recording tracks from the inner circumference side to the outer circumference side of the optical disk.
[0054]
FIG. 5 also shows waveforms of the outer peripheral side RF signal 123 and the inner peripheral side RF signal 126 obtained when the light beam spot moves along the trajectory 122.
[0055]
There are pits 121 and mirror surfaces on the recording surface of the read-only disc. When the position of the light beam spot is on the mirror surface, light is not diffracted and the amount of reflected light is maximum. On the other hand, when the position of the light beam spot is on or near the pit 121, the amount of reflected light decreases depending on the positional relationship between the light beam spot and the pit due to light diffraction. For this reason, when the light beam spot is not in the vicinity of the pit 121, a reflected light amount independent of the relative positional relationship of the light beam spot with respect to the recording track 120 can be obtained. As a result, the upper envelope 124 of the outer peripheral side RF signal 123 and the upper envelope 127 of the inner peripheral side RF signal 126 become substantially constant level signals.
[0056]
On the other hand, when the position of the light beam spot is located on the pit 121 or in the vicinity of the bit 121, the magnitudes of the outer peripheral side RF signal 123 and the inner peripheral side RF signal 126 are reduced. For this reason, the lower envelope 125 of the outer periphery side RF signal 123 and the lower envelope 128 of the inner periphery side RF signal 126 change when the light beam spot crosses the recording track 120.
[0057]
FIG. 6 shows how a light beam spot traverses a recording track of a recordable disc, and the outer and inner peripheral side RF signal waveforms obtained at that time. The upward direction of the waveform corresponds to the direction in which the amount of reflected light is high.
[0058]
In FIG. 6, three adjacent grooves 130 are enlarged and a recording mark 131 is formed in the groove 130. Further, a trajectory 132 of a light beam spot traversing the three grooves 130 from the inner circumference side to the outer circumference side of the optical disc is shown.
[0059]
FIG. 6 also shows waveforms of the outer peripheral side RF signal 133 and the inner peripheral side RF signal 136 obtained when the light beam spot moves along the trajectory 132.
[0060]
Since the recording surface of the recordable disc has irregularities due to the grooves 131, the irregularities cause light diffraction. For this reason, the amount of reflected light changes in proportion to the offset amount of the light beam spot from the groove center. Further, since the reflectance of the recording mark 131 is low, the amount of reflected light decreases when the position of the light beam spot is on or near the recording mark 131. As a result, the upper envelopes 134 and 137 vary to reflect changes in light diffraction as the light beam spot traverses the groove 130.
[0061]
When the light beam spot is located at the center of the groove 130 or in the middle of one adjacent groove 130, the diffraction on the inner peripheral side and the outer peripheral side is symmetric, so the amount of reflected light on the inner peripheral side and the outer peripheral side is equal. On the other hand, when the light beam spot is located at the edge of the groove 130, the diffraction is not symmetric. Specifically, when the light beam spot is positioned at the inner peripheral edge of the groove 130, the amount of reflected light on the outer peripheral side is less than the inner peripheral side, and the light beam spot is positioned at the outer peripheral edge of the groove 130. The amount of reflected light on the inner peripheral side is smaller than that on the outer peripheral side. Therefore, the waveforms of the upper envelope 134 of the outer periphery side RF signal 133 and the waveform of the upper envelope 137 of the inner periphery side RF signal 136 are in a substantially inverted relationship (a relationship in which the phase is shifted by approximately 180 °).
[0062]
Note that while the light beam spot is located on or near the recording mark 131, the values of the outer peripheral side RF signal 133 and the inner peripheral side RF signal 136 decrease. For this reason, the lower envelopes 135 and 138 also change to reflect the state in which the light beam spot crosses the groove 130.
[0063]
As described above, there is a difference between the upper envelope of the outer peripheral RF signal or the upper envelope of the inner peripheral RF signal depending on the presence or absence of the groove between the recordable disc and the read-only disc that are widely used at present. That is, in the case of an optical disk having a groove, the upper envelope of the RF signal varies at a frequency equal to the groove crossing frequency of the light spot. On the other hand, in the case of an optical disk having no groove, the upper envelope of the RF signal does not vary and becomes a substantially constant value.
[0064]
In the optical disc apparatus of the present invention, the recordable disc and the read-only disc are discriminated using the difference in the signal waveform depending on the presence or absence of the groove.
[0065]
In the present embodiment, the configuration of the photodetector 7 is such that the amount of light reflected by the light beam spot can be detected by being divided into two in the tangential direction of the recording track. Therefore, the inner periphery side RF signal is a signal proportional to the amount of reflected light on the entire inner periphery side of the light beam spot, and the outer periphery side RF signal is a signal proportional to the reflected light amount on the entire outer periphery side of the light beam spot. However, the configuration of the photodetector 7 is not limited to such a configuration, and the reflected light amount of the light beam spot is divided into two in the tangential direction of the recording track or groove, and further divided into two in the direction perpendicular to the tangential direction. A possible configuration may be adopted. When such a four-divided photodetector is employed, either one of the two signals proportional to the amount of reflected light on the inner peripheral side or one of the two signals proportional to the amount of reflected light on the outer peripheral side is selected. You may use as an inner peripheral side RF signal and an outer peripheral side RF signal. In this case as well, a signal having a waveform similar to that shown in FIGS. 5 and 6 can be obtained, and the presence / absence of a groove can be detected to discriminate between a recordable disc and a read-only disc. In this case, it is preferable that the signals corresponding to the amount of reflected light from a position symmetric with respect to the tangential direction of the recording track are the inner peripheral RF signal and the outer peripheral RF signal. By doing so, the waveforms of the upper envelope of the inner periphery side RF signal and the upper envelope of the outer periphery side RF signal are substantially inverted from each other.
[0066]
The configuration of the photodetector is not limited to the above, and may be further divided into a large number of regions.
[0067]
(Embodiment 1)
Next, a first embodiment of an optical disc device according to the present invention will be described. FIG. 7 shows the configuration of the main part of the optical disc apparatus of the present embodiment.
[0068]
The optical disk apparatus of FIG. 7 includes the optical head 8 shown in FIG. 4 and the components described below, that is, a tracking error detection unit 9, an irradiation position control unit 10, a peak detection circuit 11, an amplitude detection unit 12, and a disk A determination unit 13, a recording status detection unit 14, and a reproduction control unit 15 are provided.
[0069]
The tracking error detection unit 9 receives a signal output from the photodetector 7 of the optical head 8, detects a tracking error from the output signal of the photodetector 7, and generates a tracking error signal.
[0070]
The irradiation position control unit 10 generates a control signal based on the tracking error signal output from the tracking error detection unit 9 and outputs the control signal to the optical head 8. By this control signal, the operation of an actuator or the like that drives the optical head 8 is adjusted, and the irradiation position of the light beam spot on the optical disc 1 is controlled.
[0071]
The configurations and operations of the tracking error detection unit 9 and the irradiation position control unit 10 may be known ones.
[0072]
The peak detection circuit 11 of the present embodiment receives the outer peripheral side RF signal output from the photodetector 7 and generates an upper envelope signal thereof.
[0073]
The amplitude detection unit 12 detects the amplitude of the upper envelope signal output from the peak detection circuit 11 (see FIG. 9), and normalizes the amplitude by the extreme value with the higher amount of reflected light among the extreme values of the upper envelope signal. Generate a signal.
[0074]
The disc discriminating unit 13 discriminates whether or not the optical disc 1 loaded in the optical disc apparatus has a groove, that is, whether it is a reproduction-only disc or a recordable disc, based on a signal output from the amplitude detection unit 12. To do. As a result of this determination, if the loaded optical disk is a reproduction-only disk, a binary signal indicating “0” is output to the recording status detection unit 14 and the reproduction control unit 15. On the other hand, if the loaded optical disk is a recordable disk, a binary signal indicating “1” is output to the recording status detection unit 14 and the reproduction control unit 15.
[0075]
When the binary signal output from the disc determination unit 13 indicates “1”, the recording status detection unit 14 is based on the output signal of the photodetector 7 and whether the information recorded on the optical disc is legally recorded. Or detect whether it is illegally recorded. If the recording is legal, a binary signal indicating “0” is output to the reproduction control unit 15. On the other hand, if the recording is illegal, a binary signal indicating “1” is output to the reproduction control unit 15. When the binary signal output from the disc determination unit 13 indicates “0”, the recording status detection unit 14 does nothing and outputs a binary signal indicating “0” to the reproduction control unit 15.
[0076]
The reproduction control unit 15 in this embodiment performs an AND operation on the binary signal output from the disc determination unit 13 and the binary signal output from the recording status detection unit 14. When the result of the AND operation is “0”, a reproduction control signal indicating “permitted” for reproduction of the loaded optical disk 1 is output to a reproduction operation unit (not shown) of this apparatus. On the other hand, when the result of the AND operation is “1”, a reproduction control signal indicating “not permitted” is output to a reproduction operation unit (not shown) of the present apparatus.
[0077]
Next, details of the amplitude detector 12 will be described with reference to FIG. FIG. 8 shows the internal configuration of the amplitude detector 12.
[0078]
The maximum small value detection unit 300 detects a maximum value and a minimum value within a defined first time of the upper envelope signal output from the peak detection circuit 11 (see FIG. 9). The determined first time is the time for the position of the light beam spot to cross the recording track or groove a plurality of times, and is set to 0.020 seconds, for example. The maximum small value detection unit 300 includes a divided maximum / low value detection unit 301 and an average value detection unit 302 therein. The divided maximum / small value detection unit 301 detects the maximum value and the minimum value of the upper envelope signal output from the peak detection circuit 11 every second time obtained by dividing the first time defined above into a plurality of times. The determined second time is a time for the position of the light beam spot to cross the recording track at least once, and is set to 0.002 seconds, for example.
[0079]
The average value detection unit 302 detects an average value of a plurality of maximum values and an average value of a plurality of minimum values detected by the divided maximum / small value detection unit 301, and sets the upper value within a defined first time. Output as the maximum and minimum values of the envelope signal. When detecting the average value, the average value is detected by excluding the maximum value and the minimum value among the plurality of maximum values and minimum values.
[0080]
The maximum small value difference detection unit 303 detects the difference between the maximum value and the minimum value output from the maximum small value detection unit 300 as the absolute amplitude value of the upper envelope signal.
[0081]
The amplitude normalization unit 304 normalizes the amplitude absolute value output from the maximum small value difference detection unit 303 by the maximum value output from the maximum small value detection unit 300, and detects it as the amplitude normalization value of the upper envelope signal.
[0082]
The amplitude detection unit 12 of the present embodiment can detect the AC amplitude of the upper envelope signal output from the peak detection circuit 11 by having the above configuration.
[0083]
Next, the configuration of the recording status detection unit 14 will be described in detail.
[0084]
When the disc determination unit 13 determines that the loaded optical disc is a recordable disc, the recording status detection unit 14 determines whether the recorded information is due to legal recording or illegal recording. To detect. This detection can be performed, for example, using sub-information recorded on the recording mark in addition to the content as in the case of an optical disc. Such a detection method is described in Patent Document 2. According to the technique described in Patent Document 2, when the sub information is recorded by the phase shift of the recording mark in the circumferential direction of the optical disc, it is determined that the recording is legal. When illegal recording is performed, the sub information is not recorded because there is no phase shift.
[0085]
The recording status detection unit 14 detects the presence / absence of sub information by detecting the phase shift of the recording mark from the output signal of the photo detector 7. If there is sub information, the recording status detection unit 14 determines that the recording is legal. It is determined that the record is illegal.
[0086]
Next, the disc discrimination flow will be described.
[0087]
First, the loaded optical disk 1 is rotated by the motor 2. The irradiation position control unit 10 controls the position of the optical head 8 so that the light beam spot crosses the recording track of the optical disk 1 in a state where the light beam spot is formed on the recording surface of the rotating optical disk 1. At this time, the outer peripheral side and inner peripheral side RF signals output from the photodetector 7 have waveforms as shown in FIGS.
[0088]
The subsequent operation will be described with reference to FIG. FIG. 9 shows an example of input / output signal waveforms of the components in the present embodiment shown in FIG. FIG. 9A shows an example of a signal waveform obtained when a recordable disc having a groove is loaded in the optical disc apparatus, and FIG. 9B shows a read-only disc having no groove is the optical disc apparatus. 2 shows an example of a signal waveform obtained when the battery is loaded.
[0089]
The outer peripheral side RF signal A shown in FIGS. 9A and 9B is an output signal of the photodetector 7, and the upper envelope signal B is a result of the peak detection of the outer peripheral side RF signal A by the peak detection circuit 11. This is the signal obtained. The tracking error signal C is an output signal from the tracking error detector 9. The frequency of the tracking error signal C is equal to the frequency at which the light beam spot on the optical disc crosses the recording track of the optical disc 1.
[0090]
When a recordable disc is loaded in the optical disc apparatus, the upper envelope of the outer peripheral side RF signal A vibrates at the same frequency as the tracking error signal C as shown in FIG. Therefore, the upper envelope signal B becomes a signal that vibrates at the same frequency as the tracking error signal C. Accordingly, the maximum value and minimum value of the upper envelope signal B are detected by the maximum / minimum value detection unit 300 in the amplitude detection unit 12 over several cycles of the tracking error signal C, and the difference is detected by the maximum / minimum value difference detection unit 303. The amplitude absolute value obtained by detecting is a value greater than a certain value. Further, the amplitude normalization value obtained by performing normalization with the maximum value of the upper envelope B by the amplitude normalization unit 304 is also a certain value or more.
[0091]
When the read-only disc is loaded in the optical disc apparatus, the upper envelope of the outer peripheral side RF signal A hardly varies as shown in FIG. For this reason, the upper envelope signal B is also a signal with almost no fluctuation. Therefore, the value obtained by detecting the amplitude normalized value of the upper envelope signal B over several cycles of the tracking error signal C by the amplitude detector 12 is substantially 0 (zero).
[0092]
As described above, the disc discriminating unit 13 discriminates that the loaded disc is a recordable disc when the value obtained by the amplitude detecting unit 12 is a certain value or more, and when the value is less than a certain value, the loaded disc is discriminated. It is determined that the disc is a reproduction-only disc.
[0093]
In the above description, the determination is performed using the outer peripheral side RF signal, but the determination can also be performed using the inner peripheral side RF signal.
[0094]
Further, a configuration may be adopted in which the photodetector 7 can detect the amount of light reflected by the light beam spot by dividing it into two in the tangential direction of the recording track or groove and further dividing it in two directions perpendicular to the tangential direction. When a photodetector with such a configuration is used, either one of the two signals proportional to the amount of reflected light on the inner peripheral side or one of the two signals proportional to the amount of reflected light on the outer peripheral side is transmitted to the inner periphery. It can be used as a side RF signal and an outer peripheral side RF signal.
[0095]
The flow after disc discrimination is as follows.
[0096]
When the disc determination unit 13 determines that the loaded optical disc is a recordable disc, the recording status detection unit 14 determines whether the information recorded on the optical disc is due to legal recording or illegal recording. A binary signal depending on the detection result is output. When the disc determination unit 13 determines that the loaded optical disc is a read-only disc, the value of the binary signal is output as “0”.
[0097]
The reproduction control unit 15 performs an AND operation on the two binary signals output from the disc determination unit 13 and the recording status detection unit 14. Here, when the loaded optical disc is a read-only disc and when it is a legally recorded recordable disc, the calculation result is “0”, and reproduction is permitted. When the disc is an illegally recorded recordable disc, the calculation result is “1”, and reproduction is not permitted.
[0098]
The playback operation unit in the optical disc apparatus of the present embodiment performs a playback operation in accordance with such playback permission and non-permission instructions.
[0099]
The amplitude of the upper envelope signal obtained by using one of the output signals of the photodetector divided into two in the tangential direction of the recording track of the optical disc is several times the amplitude of the envelope signal in the prior art. Therefore, the disc can be discriminated with high reliability. As a result, playback-only discs and legally recorded recordable discs are played back, but illegally recorded recordable discs are not played back, and the illegal distribution of illegal discs can be strongly prevented.
[0100]
The recording of the sub information is not limited to an example in which the recording mark phase shift is used. The detection of whether a record is legal or illegal is not limited to an example using sub information, and various other detection methods can be used.
[0101]
The recording status detection unit 14 that detects whether or not information on the recordable disc is legally recorded is not an essential component for the optical disc apparatus of the present invention. Instead of providing the recording status detection unit 14, the reproduction control unit 15 may determine whether to permit or not allow reproduction of the loaded optical disk based only on the determination result of the disc determination unit 13. In this case, a reproduction control signal that permits reproduction of the loaded optical disk 1 when the value of the binary signal output from the disk determination unit 13 is “0”, and prohibits reproduction when the value is “1”. The data is output to a reproduction operation unit (not shown) of the optical disk device. In such an optical disc apparatus, only a read-only disc is reproduced, and a recordable disc is not reproduced. Accordingly, since an optical disc that may be illegally recorded is not reproduced, it is possible to strongly prevent the illegal disc from being distributed.
[0102]
The fixed first time and second time may be fixed times calculated in anticipation of the speed at which the light beam spot crosses the recording track. Alternatively, it may be a time during which a predetermined number of cycles are observed by observing the cycle of the tracking error signal output from the tracking error detector 9 as needed. In the former case, it can be realized with a minimum software or hardware burden at the time of disc identification. In the latter case, even if the speed at which the light beam spot crosses the recording track changes due to changes in the rotational speed of the optical disk or eccentricity during the amplitude detection operation, the maximum and minimum values are stably detected at every fixed number of crossings. Therefore, the reliability of amplitude detection can be improved.
[0103]
There are roughly the following two methods for the irradiation position control unit 10 to cause the light beam spot on the optical disk to cross the recording track.
[0104]
The first method uses the fact that the position of the light beam spot is fixed at a certain radial position of the optical disk, and the recording track or groove moves in the radial direction relative to the light beam spot due to the eccentricity of the rotation of the optical disk. It is a method to do. In this method, since it is not necessary to move the optical head 8 in the radial direction, it can be easily realized without burden of movement control processing in software or the like, and power consumption can be reduced.
[0105]
The second method is a method in which the optical track 8 is moved in a certain radial direction toward the inner periphery or the outer periphery of the optical disc 1 so that the recording track crosses the recording track. According to this method, the direction in which the light beam spot crosses the recording track is constant. Therefore, the transverse direction is not reversed due to the eccentricity of the optical disk while traversing a certain recording track. For this reason, the amplitude of the upper envelope signal does not decrease, and stable amplitude detection can be performed.
[0106]
Regarding the movement control of the optical disk in the radial direction, the optical disk may be moved in advance for a certain period of time calculated based on the radial width of the recording track, the speed at which the light beam spot is moved, and the number of the light beam spots to be traversed. Alternatively, the period of the tracking error signal output from the tracking error detection unit 9 may be observed as needed and moved in the radial direction until a certain period is observed. In the former case, it can be realized with a minimum software or hardware burden at the time of disc identification. In the latter case, even if the speed at which the light beam spot crosses the recording track and groove changes due to changes in the rotational speed or eccentricity of the optical disk during the amplitude detection operation, it can be traversed a certain number of times, so that stable amplitude is achieved. Detection can be performed.
[0107]
In the AC amplitude detection of the upper envelope signal, the amplitude normalization unit 304 normalizes the maximum value of the upper envelope signal, that is, the reflected light maximum value of the outer peripheral side RF signal or the inner peripheral side RF signal. The maximum value of the reflected light amount is substantially determined only by the difference in the shape of the light beam spot and the light amount distribution, and the reflectivity that differs for each type of optical disk. Therefore, when normalization is performed using the maximum amount of reflected light, these effects can be removed from the amplitude of the upper envelope signal, and the difference in amplitude due to the presence or absence of a groove can be detected more clearly.
[0108]
In the present embodiment, as shown in FIG. 8, in the detection of the maximum value and the minimum value within the first time determined by the maximum / small value detection unit 300, the first value determined by the divided maximum / low value detection unit 301 is used. The maximum value and the minimum value are detected a plurality of times by dividing the time into a plurality of times, and an average value detection unit 302 detects a value obtained by averaging the plurality of values. Since such a detection method is adopted, the upper side is independent of the presence or absence of the groove due to noise, defects in the recording surface of the optical disc, LPP (Land Pre-Pit) present in the DVD-R disc or DVD-RW disc, and the like. Even if a change in which the envelope signal protrudes is detected, the influence can be alleviated and erroneous detection of the amplitude can be prevented.
[0109]
When performing the above averaging, it is preferable to perform the averaging by excluding the maximum value and the minimum value among the plurality of maximum values and minimum values. Thereby, the influence of noise, defects on the recording surface, and LPP can be further reduced.
[0110]
It should be noted that not only the maximum value and the minimum value among the plurality of maximum values and minimum values, but also a plurality of values ordered in magnitude may be further excluded and averaged. As a result, the influence of noise, recording surface defects, and LPP can be further reduced.
[0111]
In this embodiment, in order to improve the reliability of amplitude detection, averaging by the divided maximum / small value detection unit 301 and the average value detection unit 302 and normalization by the amplitude normalization unit 304 are performed. However, even if these processes are omitted, the amplitude of the upper envelope signal can be detected. The maximum value and the minimum value can be detected by comparing sequentially sampled values, and can be realized by a simple circuit configuration or program. For this reason, if the averaging and normalization processes are omitted, the amplitude can be detected in a short time while adopting a simpler configuration.
[0112]
As the amplitude detection method of the amplitude detector 12, a method different from the method described above can be adopted. FIG. 10 shows another example of the internal configuration of the amplitude detector 12. 10 detects the value detected by performing synchronous detection on the upper envelope signal output from the peak detection circuit 11 using the tracking error signal output from the tracking error detector 9, and the amplitude of the upper envelope signal. Output as.
[0113]
The frequency of the tracking error signal is equal to the frequency at which the light beam spot on the optical disc crosses the recording track of the optical disc. Therefore, if the amplitude of a component having a frequency equal to the frequency of the tracking error signal in the upper envelope signal is detected by synchronous detection, fluctuation due to the influence of the groove is extracted. As a result, the presence or absence of a groove can be detected more precisely. It does not matter whether the tracking error signal is generated by the push-pull method or the phase difference method.
[0114]
As described with reference to FIG. 8, the output of the synchronous detector 305 may be further normalized by the maximum amount of reflected light of the upper envelope signal by the amplitude normalizer. By performing normalization, the presence or absence of a groove can be detected more precisely.
[0115]
(Embodiment 2)
Next, a second embodiment of the optical disc apparatus according to the present invention will be described. FIG. 11 shows the main part of the optical disk apparatus of the present embodiment.
In FIG. 11, the same reference numerals are assigned to the components corresponding to the components shown in FIG. As shown in FIG. 11, the present optical disc apparatus has the same configuration as that of the first embodiment, but performs beak detection on both the outer peripheral side RF signal and the inner peripheral side RF signal output from the photodetector 7, The difference is that the difference is calculated.
[0116]
Hereinafter, the components of the optical disk apparatus according to the present embodiment will be described in detail.
[0117]
As in the first embodiment, the tracking error detector 20 of this embodiment detects a tracking error from the output signal of the photodetector 7 and generates a tracking error signal. Further, the irradiation position control unit 26 outputs a control signal to the optical head 8 based on the tracking error signal that is an output signal of the tracking error detection unit 20, and controls the irradiation position of the light beam spot.
[0118]
The peak detection circuit in the present embodiment is realized by the peak detection circuits 21 and 22, and the peak detection circuits 21 and 22 respectively have the upper envelopes of the inner peripheral side RF signal and the outer peripheral side RF signal output from the photodetector 7. Detect and generate an inner circumference upper envelope signal and an outer circumference upper envelope signal. These upper envelope signals are output to the difference detector 23 and the amplitude detector 24.
[0119]
The difference detection unit 23 detects a difference between the inner circumference upper envelope signal and the outer circumference upper envelope signal output from the peak detection circuits 21 and 22, and generates a difference signal. The difference signal is output to the amplitude detector 24.
[0120]
The amplitude detector 24 that also functions as an amplitude normalizer detects the amplitude of the difference signal output by the difference detector 23, and averages the extreme values of the higher reflected light amounts of the inner and upper envelope signals. Normalize by value. The normalized signal is output to the disc discrimination unit 25.
[0121]
The disc discriminating unit 25 discriminates whether the loaded optical disc 1 is a read-only disc or a recordable disc based on the amplitude value output from the amplitude detecting unit 24. When the optical disc divided into layers is a read-only disc, a binary signal indicating “0” is output to the recording status detection unit 27 and the reproduction control unit 28. On the other hand, if the loaded optical disk is a recordable disk, a binary signal indicating “1” is output to the recording status detection unit 27 and the reproduction control unit 28.
[0122]
When the binary signal output from the disc discriminating unit 25 is “1”, the recording status detecting unit 27 has recorded the information recorded on the optical disc 1 legally or illegally. Detect whether or not Then, a binary signal indicating “0” is output to the reproduction control unit 28 if it is legal, and “1” is output if it is illegal. On the other hand, when the output of the disc determination unit 25 is “0”, the recording state detection unit 27 does nothing and outputs a binary signal indicating “0” to the reproduction control unit 28.
[0123]
The reproduction control unit 28 performs an AND operation on the binary signal output from the disc determination unit 25 and the binary signal output from the disc determination unit 27. When the calculation result is “0”, a reproduction control signal that permits reproduction of the loaded optical disk 1 and prohibits reproduction when it is “1” is output to a reproduction operation unit (not shown) of this apparatus.
[0124]
Next, details of the amplitude detector 24 will be described. FIG. 12 is a diagram showing an internal configuration of the amplitude detector 24.
[0125]
The maximum small value detection unit 310 detects the maximum value and the minimum value within a defined first time of the difference signal output from the difference detection unit 23. The determined first time is the time for the position of the light beam spot to cross the recording track or groove a plurality of times.
[0126]
The maximum small value detecting unit 310 includes a divided maximum / low value detecting unit 311 and an average value detecting unit 312 inside. The division maximum / small value detection unit 311 detects the maximum value and the minimum value of the difference signal output by the difference detection unit 23 every second time obtained by dividing the determined first time into a plurality of times. The predetermined second time is a time for the position of the light beam spot to cross the recording track or groove at least once.
[0127]
The average value detection unit 312 detects an average value of a plurality of maximum values and an average value of a plurality of minimum values detected by the divided maximum / small value detection unit 311. Then, the value is output as the maximum value and the minimum value of the difference signal within a predetermined first time. When the average value is detected, the average value is detected by excluding the maximum value and the minimum value among the plurality of maximum values and minimum values.
[0128]
The maximum small value difference detection unit 313 detects the difference between the maximum value and the minimum value output from the maximum small value detection unit 310 as an amplitude absolute value of the difference signal.
[0129]
The maximum light quantity detector 314 detects the maximum reflected light quantity of the inner circumference upper envelope signal and the outer circumference upper envelope signal output from the peak detection circuits 21 and 22, and further detects the average value of these to normalize the amplitude normalizer 315. Output to.
[0130]
The amplitude normalization unit 315 normalizes the amplitude absolute value output from the maximum small value difference detection unit 303 with the value output from the maximum light quantity detection unit 314, and detects the normalized value of the difference signal.
[0131]
The amplitude detector 24 of the present embodiment detects the AC amplitude of the difference signal output from the difference detector 23 in this way.
[0132]
Next, details of the recording status detection unit 27 will be described.
[0133]
When the recording status detection unit 27 determines that the optical disc loaded with the disc determination unit 25 is a recordable disc, it determines whether the recorded information is due to legal recording or illegal recording. To detect. As described in the first embodiment, this detection can be performed using the sub information described in Patent Document 2. The recording status detection unit 27 detects the presence / absence of sub information from the output signal of the photo-detector 7, and determines that it is legal recording when there is sub information, and determines that it is illegal recording when there is no sub information.
[0134]
Next, the flow of disc discrimination in this embodiment will be described.
[0135]
First, the optical disk 1 is rotated by the motor 2. The irradiation position control unit 26 controls the position of the optical head so that the light beam spot crosses the recording track of the optical disk 1 in a state where the recording surface of the rotating optical disk 1 is irradiated with the light beam spot. At this time, the outer peripheral side and inner peripheral side RF signals output from the photodetector 7 have waveforms as shown in FIGS.
[0136]
The subsequent operation will be described with reference to FIG. FIG. 13 shows an example of the waveform of the input / output signal of the component in this embodiment shown in FIG. FIG. 13A shows an example of a signal waveform obtained when a recordable disc having a groove is loaded in the optical disc apparatus. FIG. 13B shows a read-only disc having no groove loaded in the optical disc apparatus. An example of the signal waveform obtained in this case is shown.
[0137]
The inner peripheral side RF signal D and the outer peripheral side RF signal E shown in FIGS. 13A and 13B are output signals of the photodetector 7. The inner circumference upper envelope signal F is a signal obtained as a result of the peak detection of the inner circumference side RF signal D by the peak detection circuit 21, and the outer circumference upper envelope signal G is the peak detection of the outer circumference side RF signal E by the peak detection circuit 22. It is a signal obtained as a result of performing. The difference signal H is a signal obtained by detecting a difference between the inner circumference upper envelope signal F and the outer circumference upper envelope signal G by the difference detection unit 23. The tracking error signal I is an output signal from the tracking error detector 20. The frequency of the tracking error signal I is equal to the frequency at which the position of the light spot crosses the recording track of the optical disc 1.
[0138]
When a recordable disc is loaded in the optical disc apparatus, the inner circumference upper envelope signal F and the outer circumference upper envelope signal G vibrate at the same frequency as the tracking error signal I, as shown in FIG. Further, the waveforms of the upper envelope signals F and G are substantially inverted with respect to each other. Therefore, the difference signal H indicating the difference between the inner circumference upper envelope signal F and the outer circumference upper envelope signal G vibrates at the same frequency as the tracking error signal I. Accordingly, when the amplitude of the difference signal H is determined over several cycles of the tracking error signal I by the amplitude detection unit 24, the magnitude of the amplitude becomes a certain value or more. Further, when the amplitude normalization unit 315 performs normalization based on the average value of the maximum values of the inner circumference upper envelope signal and the outer circumference upper envelope signal, the amplitude normalization value obtained thereby becomes a certain value or more.
[0139]
When a read-only disc is loaded in the optical disc apparatus, as shown in FIG. 13B, the upper envelopes of the outer peripheral side RF signal D and the inner peripheral side RF signal hardly change. For this reason, the difference signal H is also a signal with almost no fluctuation. Therefore, when the amplitude detection unit 24 detects the amplitude normalized value of the difference signal H over several cycles of the tracking error signal I, the detected value becomes substantially zero.
[0140]
The disc discriminating unit 25 according to the present embodiment discriminates that the disc is a recordable disc when the value obtained by the amplitude detecting unit 24 as described above is a certain value or more. Judged to be a disk.
[0141]
The photodetector 7 may be configured to detect the amount of light reflected by the light beam spot by dividing it into two in the tangential direction of the recording track or groove and further dividing it in two in the direction perpendicular to the tangential direction. The signal is proportional to the amount of reflected light from the inner peripheral side and the amount of reflected light on the outer peripheral side so that the signal corresponds to the amount of reflected light from the same position with respect to the tangential direction of the recording track. Signals may be detected, and these signals may be used as an inner peripheral RF signal and an outer peripheral RF signal.
[0142]
The flow after disc discrimination is as follows.
[0143]
When the disc determination unit 25 determines that the loaded optical disc is a recordable disc, the recording status detection unit 27 determines whether the information recorded on the optical disc is due to legal recording or illegal recording. And a binary signal depending on the detection result is output. When the disc discriminating unit 25 judges that the loaded optical disc is a read-only disc, nothing is detected and the value of the binary signal is set to “0” and outputted.
[0144]
The reproduction control unit 28 performs an AND operation on the two binary signals output from the disc determination unit 25 and the recording status detection unit 27. Here, when the loaded optical disc is a read-only disc and when it is a legally recorded recordable disc, the calculation result is “0”, and reproduction is permitted. On the other hand, the calculation result in the case of an illegally recorded recordable disc is “1”, and reproduction is not permitted. The playback operation unit of the optical disc apparatus according to the present embodiment performs a playback operation in accordance with such playback permission and non-permission instructions.
[0145]
The amplitude of the difference signal H used in this embodiment is about twice the amplitude of the upper envelope signal obtained in the first embodiment. Further, the common mode noise is removed by the difference detection unit. Therefore, the disc can be discriminated with higher reliability. As a result, playback-only discs and legally recorded recordable discs are played back, but illegally recorded recordable discs are not played back, and the illegal distribution of illegal discs can be strongly prevented.
[0146]
Note that the detection of whether recording on a recordable disc is illegal or legal is not limited to the example of using sub-information as described in the first embodiment, but various other detections. The method can be adopted.
[0147]
Further, the recording control unit 27 for detecting whether the recordable disc is legally recorded or illegally recorded is not provided, and the reproduction control unit 28 is loaded only from the determination result of the disc determination unit 25. The permission or non-permission of reproduction of the optical disc may be determined. In this case, a reproduction control signal that permits reproduction of the loaded optical disk 1 when the value of the binary signal output from the disk determination unit 25 is “0”, and prohibits reproduction when the value is “1”. Output to a playback operation unit (not shown) of the apparatus. In such a case, only the reproduction-only disc is reproduced, and the recordable disc is not reproduced. Accordingly, since an optical disc that may be illegally recorded is not reproduced, it is possible to strongly prevent the illegal disc from being distributed.
[0148]
The predetermined first time and second time may be fixed times calculated in advance for the speed at which the light beam spot traverses the recording track, as described in the first embodiment. Alternatively, the period of the tracking error signal output from the tracking error detector 20 may be observed as needed, and the time during which a certain period is observed may be used. These advantages are the same as those described in the first embodiment.
[0149]
The position control of the light beam spot by the irradiation position control unit 26 can be performed in the same manner as in the first embodiment, and there are two methods for causing the light beam spot to cross the recording track as described above.
[0150]
The AC amplitude detection of the difference signal is performed by the amplitude normalization unit 315 with the average value of the maximum values of the inner circumference upper envelope signal and the outer circumference upper envelope signal, that is, the average value of the reflected light maximum values of the outer circumference side RF signal and the inner circumference side RF signal. Normalization is performed by. The maximum amount of reflected light is a value determined from only the difference in the shape of the light beam spot and the distribution of the amount of light, and the reflectance that differs depending on the type of optical disc. Therefore, if normalization is performed using the maximum amount of reflected light, these effects can be removed in the amplitude of the upper envelope signal, and the difference in amplitude due to the presence or absence of a groove can be detected more clearly.
[0151]
In the present embodiment, in the detection of the maximum value and the minimum value within the first time determined by the maximum / small value detection unit 310, the first time determined by the divided maximum / low value detection unit 311 is divided into a plurality of times. A maximum value and a minimum value are detected a plurality of times, and an average value detection unit 312 detects a value obtained by averaging these multiple values. For this reason, even if a change in which a differential signal protrudes is detected regardless of the presence or absence of a groove due to noise, defects on the recording surface of an optical disk, LPP or the like present on a DVD-R disk or a DVD-RW disk, the influence can be reduced. , It can prevent erroneous detection of amplitude.
[0152]
In the averaging, it is preferable to exclude the maximum value and the minimum value among the plurality of maximum values and minimum values. Thereby, the influence of noise, defects on the recording surface, and LPP can be further reduced. In addition, not only the maximum value and the minimum value among the plurality of maximum values and minimum values, but also a plurality of values that follow the respective sizes may be further excluded and averaged. As a result, the influence of noise, recording surface defects, and LPP can be further reduced.
[0153]
In this embodiment, in order to improve the reliability of amplitude detection, averaging by the divided maximum / small value detection unit 311 and the average value detection unit 312 and normalization by the amplitude normalization unit 315 are performed. However, even if these processes are omitted, the amplitude of the difference signal can be detected. The detection of the maximum value and the minimum value can be detected by comparing sequentially sampled values, and can be realized by a simple circuit configuration or program. For this reason, if the averaging and normalization processes are omitted, the amplitude can be detected in a short time while adopting a simpler configuration.
[0154]
As the amplitude detection method of the amplitude detector 24, a method different from the method described above can be adopted. FIG. 14 shows another example of the internal configuration of the amplitude detector 24. The synchronous detection unit 316 in FIG. 14 outputs a value detected by performing synchronous detection on the differential signal output from the differential detection unit 23 using the tracking error signal output from the tracking error detection unit 20 as the amplitude of the differential signal. To do.
[0155]
According to such a configuration, the amplitude of a component having a frequency equal to the frequency of the tracking error signal in the differential signal can be detected by synchronous detection. For this reason, the fluctuation | variation by the influence of a groove | channel can be extracted, and the presence or absence of a groove | channel can be detected more strictly. It does not matter whether the tracking error signal is generated by the push-pull method or the phase difference method.
[0156]
Further, as in the case shown in FIG. 12, the output of the synchronous detection unit 316 may be further normalized by the average value of the reflected light maximum values of the inner peripheral upper envelope signal and the outer peripheral upper envelope signal by the amplitude normalization unit. Good. By performing normalization, the presence or absence of a groove can be detected more precisely.
[0157]
Next, a peak detection circuit used in the first embodiment and the second embodiment will be described with reference to FIG.
[0158]
FIG. 15 is a diagram illustrating a circuit configuration of the peak detection circuit. In FIG. 15, Q is a transistor, C is a capacitor, and R1 and R2 are resistors.
[0159]
The peak detection circuit detects the maximum value of the input signal and outputs an upper envelope signal. The resistor R1 is inserted in order to give a time constant to the response speed with respect to the maximum value and to slow down the response speed. The inner and outer RF signals output from the photo detector may fluctuate rapidly and protrude in the direction of larger values. This is due to the effects of noise superimposed on the signal, defects on the recording surface of the optical disk, and LPP existing on DVD-R and DVD-RW disks. If the resistor R1 is not inserted in the circuit, the upper envelope signal responds to such fluctuations, and the amplitude detected by the amplitude detector becomes larger than the value that should be detected. There is a possibility of erroneous detection.
[0160]
In the present embodiment, the resistor R1 and the capacitor C constitute a low-pass filter in order to suppress the upper envelope signal from responding to such rapid fluctuations in the inner and outer peripheral RF signals. By this low-pass filter, high frequency components of the inner and outer peripheral side RF signals can be removed. If the cutoff frequency of the low-pass filter is designed so as to reduce the influence from the rapid fluctuation as described above, the response of the upper envelope signal is suppressed. For this reason, it is possible to avoid the erroneous detection of the amplitude and to detect the presence or absence of the groove with high reliability.
[0161]
【The invention's effect】
According to the present invention, an optical disc capable of accurately detecting a difference in the surface form of the optical disc and accurately discriminating the type of the optical disc without being affected by the difference in the shape of the light beam spot and the light amount distribution. An apparatus is provided. Also, in a preferred embodiment of the present invention, whether or not the information recorded in the case of a recordable disc infringes copyright by properly determining whether the optical disc is a read-only disc or a recordable disc. Determine whether. When information that infringes the copyright is recorded, the reproduction of the optical disc is not permitted, so that it is possible to suppress the spread of the optical disc that has been illegally copied due to the copyright infringement.
[Brief description of the drawings]
FIG. 1A is a perspective view in which a part of a recording surface of a read-only disc is cut out, and FIG. 1B is a perspective view in which a part of a recording surface of a recordable disc is cut out.
FIG. 2 is a diagram showing a configuration of an apparatus used for groove detection of an optical disc apparatus.
3A is a waveform diagram of an RF signal H and an envelope signal I obtained when a recordable disc is loaded, and FIG. 3B is obtained when a read-only disc is loaded. 4 is a waveform diagram of an RF signal H and an envelope signal I. FIG.
FIG. 4 is a diagram showing a configuration of an optical head that can be used in the optical disc apparatus of the present invention.
FIG. 5 is a diagram showing a state where a light beam spot traverses a recording track of a read-only disc, and outer and inner peripheral side RF signal waveforms obtained at that time.
FIG. 6 is a diagram showing a state in which a light beam spot traverses a recording track of a recordable disc, and outer and inner peripheral side RF signal waveforms obtained at that time.
FIG. 7 is a diagram showing a configuration of a first embodiment of an optical disc device of the present invention.
FIG. 8 is a block diagram showing an internal configuration of an amplitude detector 12 in the first embodiment of the present invention.
9A is a diagram showing an example of a signal waveform obtained when a recordable disc having grooves is loaded in an optical disc apparatus in the first embodiment of the present invention, and FIG. FIG. 5 is a diagram showing an example of a signal waveform obtained when a read-only disc having no groove is loaded in an optical disc apparatus.
FIG. 10 shows another example of the internal configuration of the amplitude detector 12 in the first embodiment of the present invention.
FIG. 11 is a diagram showing a configuration of a second exemplary embodiment of the present invention.
FIG. 12 is a diagram showing an internal configuration of an amplitude detector 24 in the second embodiment of the present invention.
FIG. 13A is a diagram showing an example of a signal waveform obtained when a recordable disc having grooves is loaded in an optical disc apparatus in the first embodiment of the present invention, and FIG. It is a figure which shows an example of the signal waveform obtained when the read-only disk which does not have a groove | channel is loaded in the optical disk apparatus.
FIG. 14 is a diagram showing another example of the internal configuration of the amplitude detector 24 in the second embodiment of the present invention.
FIG. 15 is a diagram illustrating a circuit configuration of a peak detection circuit according to a second embodiment of the present invention.
[Explanation of symbols]
1 Optical disc
2 Motor
8 Optical head
3 Semiconductor laser
4 Collimating lens
5 Beam splitter
6 Objective lens
7 Photo detector
9 Tracking error detector
10 Irradiation position controller
11 Peak detection circuit
12 Amplitude detector
13 Disc discriminator
14 Recording status detector
15 Playback control unit
20 Tracking error detector
21 Peak detection circuit
22 Peak detection circuit
23 Difference detection unit
24 Amplitude detector
25 Disc discriminator
26 Irradiation position controller
27 Recording status detector
28 Playback control unit
120 recording tracks
121 pits
122 Orbit of light beam spot
123 Outer peripheral side RF signal
126 Inner side RF signal
130 Groove
131 Record mark
132 Light beam spot trajectory
133 Outer peripheral side RF signal
136 Inner circumference side RF signal
140 recording tracks
141 pit
142 space
143 Groove
144 Record mark
145 space
300 Maximum small value detector
301 division maximum / small value detection unit
302 Average value detector
303 Maximum value difference detector
304 Amplitude normalization unit
305 Synchronous detection unit
310 Maximum Small Value Detection Unit
311 Divided maximum / small value detector
312 Average value detector
313 Maximum small value difference detector
314 Maximum light intensity detector
315 Amplitude normalization unit
316 Synchronous detection unit

Claims (9)

An optical disc apparatus capable of loading an optical disc arbitrarily selected from a plurality of types of optical discs including a first optical disc having a groove and a second optical disc not having a groove,
An optical system for irradiating the recording surface of the loaded optical disc with laser light;
A first output signal corresponding to the amount of light of at least part of the light received from the optical disk and reflected from the inner periphery of the optical disk, and at least part of the light reflected from the outer periphery of the optical disk; A light detection unit that generates a second output signal according to the amount of light;
A disc discriminating unit for judging whether or not the loaded optical disc has a groove based on the high light amount side envelope signal of the first output signal and / or the high light amount side envelope signal of the second output signal;
With
The disc discriminating unit
A peak detection circuit that receives the first output signal or the second output signal, detects a maximum amount of received light by performing peak detection on the high light amount side of the received signal, and generates the high light side envelope signal; ,
Optical disc device that have a amplitude detector for detecting an AC amplitude of the high light amount side envelope signal. The disc discriminating unit
The first output signal and the second output signal are received, and the peak value on the high light amount side is detected for each of the received output signals to detect the maximum value of the received light amount, and the high light amount side envelope of the first output signal is detected. A peak detection circuit for generating a high-light-side envelope signal of the signal and the second output signal;
A difference detection unit for detecting a difference between the high light amount side envelope signal of the first output signal and the high light amount side envelope signal of the second output signal;
An amplitude detector for detecting an AC amplitude of a signal output from the difference detector;
The optical disc apparatus according to claim 1, comprising: The amplitude normalization part which normalizes the output signal of the said amplitude detection part with the extreme value with the higher reflected light quantity among the extreme values of the signal output from the said peak detection circuit, or further. 2. The optical disc device according to 2 . The peak detection circuit includes a first output signal corresponding to the total light amount reflected from the inner peripheral side of the optical disc and / or a second output signal corresponding to the total light amount reflected from the outer peripheral side of the optical disc. The optical disk apparatus according to claim 1 or 2 , wherein an output signal is received, and peak detection is performed on the first output signal and / or the second output signal with the higher reflected light amount. A tracking error detection unit that outputs a tracking error signal according to a deviation between the irradiation position of the laser beam and the center of the recording track based on an output signal of the light detection unit,
The amplitude detection unit includes a synchronous detection unit that detects an amplitude of a component synchronized with an output signal of the tracking error detection unit in an output signal of the peak detection circuit, and outputs an output of the synchronous detection unit to the AC amplitude The optical disc apparatus according to claim 1 or 2 , wherein The amplitude detection unit is a maximum and minimum value detection unit that detects a maximum value and a minimum value of an output signal of the peak detection circuit within a predetermined first time;
A maximum minimum value difference detection unit that detects a difference between the maximum value and the minimum value detected by the maximum minimum value detection unit;
The optical disk apparatus according to claim 1 or 2 outputs the output of the maximum minimum value difference detecting section as the AC amplitude. The maximum minimum value detection unit detects a maximum value and a minimum value of the output signal of the peak detection circuit every second time obtained by dividing the predetermined first time into a plurality of times. When,
An average value detecting unit for detecting an average value of a plurality of maximum values and an average value of a plurality of minimum values detected by the divided maximum / small value detection unit;
The average value of the plurality of maximum values and the average value of the plurality of minimum values output by the average value detection unit are set as the maximum value and the minimum value within a defined first time of the output signal of the peak detection circuit. The optical disc apparatus according to claim 6 . The average value detection unit includes a maximum value and a minimum value or a maximum value and a minimum value among the plurality of maximum values detected by the divided maximum / small value detection unit, a plurality of values that are ordered in magnitude, and the plurality of minimums 8. The optical disc according to claim 7 , wherein an average value of the plurality of maximum values and the plurality of minimum values is detected by excluding a maximum value and a minimum value or a plurality of values having a size and a maximum value and a minimum value, respectively. apparatus. Based on the output signal of the light detection unit, the laser beam irradiation position on the optical disc has a crossing time detection unit for detecting the time to cross the recording track a predetermined number of times,
9. The optical disc apparatus according to claim 7, wherein the maximum small value detection unit sets the predetermined first and second times as the time for the crossing time detection unit to output.

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