JP3846510B2 - Optical information reproducing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical information reproducing apparatus. More specifically, a track is arranged on a disk medium in a concentric circle or spiral, the track is divided into sectors in the circumferential direction, and the sector is addressed at the head. Sector identification information representing information etc. is arranged with a substantially constant distance from the track center on the inner and outer sides in the radial direction, and user information etc. following the sector identification information area is the track center. The present invention relates to an apparatus for optically reproducing information from a medium composed of user information areas recorded thereon.
[0002]
[Prior art]
In recent years, memory means for storing information has been required to store information that requires a larger capacity than conventional text information and audio information, such as image information and video information. Is attracting attention. Conventional recordable optical discs are preliminarily engraved with guide grooves when the disc is manufactured in order to control the recording / reproducing light beam around the track. With this guide groove, the convex (land) portion and the concave (groove) portion of the disk are formed in a spiral or concentric shape. By using both the convex and concave portions as recording tracks (land tracks and groove tracks), it is possible to record twice as much information as when either one is used as a recording track. This system is called a land / groove recording system and is described in Japanese Patent Publication No. 63-57859.
[0003]
Usually, the recording track is divided into sectors in the track direction, and sector identification information such as track number and sector number is physically formed at the head of each sector. Is Preformatted as uneven pits. In this case, sector identification information is arranged in such a way that dedicated sector identification information is arranged on each of the land track and the groove track, a state in which the sector identification information is displaced in the radial direction so as to be shared by the adjacent land track and groove track, In particular, there is a method of arranging in the middle of the land track and the groove track.
[0004]
In the former method of arranging dedicated sector identification information, dedicated information can be included for each sector, so that control on the apparatus side is easy. In this case, in mastering for manufacturing a disk, it is necessary to make the pit width sufficiently narrower than the track pitch width, and it becomes difficult to form a desired pit with the same laser beam that forms the guide groove. The manufacturing process becomes complicated.
[0005]
On the other hand, in the latter method of sharing between adjacent land tracks and groove tracks, since the identification information is shared by two tracks, it is necessary to determine which track is being played on the device side, and the control is the former. It is slightly more complicated than the dedicated placement method. However, the preformatting of the identification information in mastering can use the same laser beam as that for forming the guide groove, and the laser beam is radiated in the radial direction by the optical deflecting means to ¼ of the track pitch of the land track or groove track. It is possible by deflecting only. Such an optical disk and an optical information reproducing apparatus using the optical disk are disclosed in Japanese Patent Laid-Open No. 06-176404.
[0006]
Next, an optical disc on which sector identification information is arranged by the latter method For playing information from An optical information reproducing apparatus will be described. FIG. 17 is a diagram showing a track format of a conventional optical disc. FIG. 18 is a diagram showing the arrangement of conventional sector identification information sections. Further, FIG. 19 is a block diagram showing a configuration of an optical information reproducing apparatus for reproducing information from such an optical disc.
[0007]
17 and 18, 1 is a sector identification information area in which sector identification information is preformatted, 2 is a user information area in which user information is recorded using a local optical constant or a change in physical shape, 3 is a groove track, and 4 is a land track. As is apparent from the figure, the track structure is such that the groove track 3 or the land track 4 is spirally arranged over the entire circumference, and is divided into sectors in the track direction. Further, the sector is divided into a sector identification information area 1 in which a track number and a sector number for specifying the sector are recorded at the head thereof, and a user information area 2 for recording user data and the like subsequent thereto. Yes. Here, the sector identification information is shared by the adjacent land track 4 and the groove track 3, and the displacement amount is ¼ of the track pitch of the land track 4 or the groove track 3.
[0008]
Next, the configuration of a conventional optical information reproducing apparatus will be described with reference to FIG. In the figure, 11 is an optical disk, 12 is a spindle motor, 13 is an optical head, 14 is first current-voltage (I / V) conversion means, 15 is second I / V conversion means, and 16 is first An adding means for adding the output of the I / V converting means 14 and the output of the second I / V converting means 15, 17 is information recorded on the disc by binarizing after processing the output of the adding means 16. 18 is a subtracting means for taking the difference between the output of the first I / V converting means 14 and the output of the second I / V converting means 15, and 19 is the polarity of the output waveform of the subtracting means 18. Is inverted by a control signal from a controller, which will be described later, and 20 is a difference signal detecting means for detecting information recorded on the disc by binarizing after processing the output of the polarity inverting means 19. 21 is a controller described later. Selector means for switching and selecting the output of the sum signal detection means 17 and the output of the difference signal detection means 20 according to the control signal from, and 22 is a control from the control gate generation means for the reproduction clock (CK) synchronized with the output of the selector means 21 Gate (RG) On the basis of the A reproduction clock generating means 23 for generating data, a data demodulating means 24 for demodulating data after judging whether the output of the selector means 21 is information "1" or "0" at the timing of the reproduction clock from the reproduction clock generating means 22; Address information reproducing means 25 for reproducing the address after reproducing the sector identification information by discriminating whether the output of the selector means 21 is the information “1” or “0” at the timing of the reproduction clock from the reproduction clock generation means 22; Control gate generation means for generating the aforementioned control gate based on the timing of the address reproduction completion signal from the address information reproduction means 24, and 26 outputs a control signal to the polarity determination circuit based on the address information from the address information reproduction means 24 Controller. Furthermore, the optical head 13 includes a laser diode (LD) 131, a collimator lens 132, a beam splitter (BS) 133, a condenser lens 134, and a photodetector (PD) 135.
[0009]
The operation of the conventional optical information reproducing apparatus configured as described above will be described with reference to FIGS. FIG. 20 shows the waveform of each part of FIG.
[0010]
When the optical disk 11 is mounted on the spindle motor 12 by a mechanical mechanism, a spindle start signal (not shown) and rotation speed information are sent from the controller 26 to rotation control means (not shown), and the spindle motor 12 is set to a predetermined rotation speed. Next, the laser diode 131 of the optical head 13 is turned on by a lighting command signal (not shown) from the controller 26. At this time, the output of the laser diode 131 is controlled to be a constant value by a feedback control means (not shown).
[0011]
The laser beam emitted from the laser diode 131 is collimated. G The light is collimated by the lens 132, passes through the beam splitter 133, and is condensed on the optical disk 11 by the condenser lens 134. Then, the reflected light (returned light) from the optical disk 11 including the information component on the optical disk 11 passes through the condenser lens 134, is reflected by the beam splitter 133, and is guided to the photodetector 135. The photodetector 135 shown here is divided into at least two in the disk radial direction with reference to the tangential direction of the track. The light distribution information on the two-divided photodetector 135 is used. Babi The optical system of the optical head 13 is adjusted so that the radial position of the optical spot can be controlled.
[0012]
Thus, when the beam spot is at the center of the track, the same amount of light is irradiated onto the two-divided detector 135, and the difference between the outputs, that is, the push-pull signal, becomes zero. On the other hand, as the beam spot moves away from the track center, the light distribution on the detector divided into two becomes unbalanced, and the push-pull signal also increases. This push-pull signal becomes zero when the beam spot is on the center of the land track 4 or the groove track 3, and becomes a maximum value or a minimum value when the beam spot is in the middle of the land track 4 and the groove track 3.
[0013]
Therefore, the tracking for controlling the beam spot to the track center may be feedback controlled so that the difference between the output signals from the two-divided detector 135 becomes zero, and this method is used for tracking an optical disc having a guide groove. It is generally adopted as a law.
[0014]
The reflected light (returned light) from the optical disk 11 including the information component on the optical disk 11 is converted into a current signal by the photodetector 135, and the first I / V conversion means 14 and the second I / V converter 14 in the next stage are converted. It is converted into a voltage by the I / V conversion means 15. By calculating the difference between the respective signals converted into voltages by the subtracting means 18, a tracking error signal by the push-pull method described above is obtained. Using this signal, tracking control means (not shown) always controls the beam spot to scan the track center.
[0015]
Further, the displacement in the optical axis direction of the light beam, such as a disc surface blur, is controlled so that the beam spot is always focused on the optical disc 11 by a focus control means (not shown).
[0016]
Information on the optical disk 11 is reproduced while the beam spot is controlled by the above-described control means. Information is recorded on the optical disk 11. Hereinafter, the description will focus on the information reproduction method.
[0017]
The signals converted into voltages by the first I / V conversion means 14 and the second I / V conversion means 15 are added by the adding means 16 to have a waveform shown in FIG. Further, the output waveform from the subtracting means 18 is the waveform shown in FIG. 20B or FIG. 20B when the beam spot travels in the center of the track. Here, the difference between (b) and (b 2) is whether the pit position in the sector identification information area 1 is displaced in the direction of the inner peripheral side or the outer peripheral side with respect to the center of the land track 4. Dependent. Further, since the beam spot travels in the center of the track in the user information area, the outputs of the two-divided photodetectors 135 are the same, and the output of the subtracting means 18 is 0 (or the reference level).
[0018]
For example, consider a case where an optical disc 11 is reproduced in which the pit position in the sector identification information area is displaced toward the inner circumference with respect to the center of the land track. Assuming that the outputs from the two I / V conversion means are connected to the subtracting means 18 so that the reproduction signal from the sector identification information area has the waveform shown in FIG. The reproduction waveform from the sector identification information area at the time of groove track reproduction is the waveform shown in FIG. Or vice versa.
[0019]
When the information on the optical disk 11 is reproduced from the output of the adding means 16, the analog signal output from the adding means 16 is binarized by comparing it with the slice level Vth1 in the sum signal detecting means 17, and FIG. ) Waveform.
[0020]
Next, the case where the sector identification information in the sector identification information area 1 on the optical disk 11 is reproduced from the output of the subtracting means 18 will be described. This method is disclosed in Japanese Patent Laid-Open No. 06-176404.
[0021]
First, the analog signal output from the subtracting means 18 has a different playback waveform polarity depending on whether the playback track is a land track or a groove track as described above. In general, a level slicing means that binarizes an analog waveform by slicing it at a certain slice level (FIG. 20, Vth2) is designed with a fixed polarity of the input signal. Therefore, in a system in which the polarity of the reproduction waveform is different, the polarity inverting means 19 for fixing the polarity to either one is required.
[0022]
The polarity inversion means 19 can be easily controlled if the relationship between the polarity of the track and the reproduction waveform is clear in advance. That is, the controller 26 described later may operate the polarity inversion means 19 by determining whether the sector to be reproduced or recorded is on the land track or the groove track. As a result, as shown in FIG. 20D, the polarity of the reproduction waveform from the sector identification information is fixed in one direction regardless of the land track or groove track. Here, the reference level is fixed downward. The output of the polarity inverting means 19 is binarized by being compared with the slice level Vth2 by the difference signal detecting means 20, and becomes the waveform of FIG.
[0023]
Next, a method for reproducing sector identification information such as a track address and sector address and user information such as user data from a binarized signal will be described.
[0024]
First, the sector identification information and the user information are reproduced using the output of the sum signal detection means 17. In this case, the selector means 21 is set to always select the output of the sum signal detection means 17. ing.
[0025]
Further, when the output of the difference signal detecting means 20 is used for reproducing the sector identification information and the output of the sum signal detecting means 17 is used for reproducing the user information, the selector means 21 switches the respective signals. The selector 21 is switched by a switching signal (FIG. 20 (f)) from a control gate generator 25 described later. This switching signal is generated by an internal timer, for example, starting from an address detection completion timing from an address information reproducing means 24 described later.
[0026]
The output of the selector unit 21 is input to the reproduction clock generation unit 22, the data demodulation unit 23, and the address information reproduction unit 24.
[0027]
The regenerated clock generating means 22 generates a regenerated clock synchronized with the output signal from the selector means 21 by means of a PLL (Phase Locked Loop) means. At this time, the reproduction clock generation means 22 is configured to operate in an area where information to be reproduced exists by a read gate (RG) from the control gate generation means 25.
[0028]
The address information reproducing means 24 reproduces the sector identification information by discriminating whether the output signal from the selector means 21 is the information “1” or “0” at the timing of the reproduced clock from the reproduced clock generating means 22, and then the address is obtained. To detect.
[0029]
The data demodulating means 23 determines whether the output signal of the selector means 21 is information “1” or “0” at the timing of the reproduction clock from the reproduction clock generation means 22, and then performs decoding, error correction and de-interleaving processing. To demodulate the data.
[0030]
As described above, the control gate generation unit 25 generates the switching signal of the selector unit 21 and the read gate of the reproduction clock generation unit 22 by using an internal timer with the address detection completion timing from the address information reproduction unit 24 as a starting point.
[0031]
The controller 26 determines the address being reproduced by the address information reproducing means 24 and information indicating whether the reproduction track obtained from the tracking control means is a land or a groove, and identifies the sector being reproduced. Further, when changing the track to be reproduced at the time of access or the like, the controller determines whether the track in which the target sector exists is a land track or a groove track, and sets the output signal polarity to the polarity inverting means 19 Outputs a control signal. In addition to this function, the controller 26 also controls the entire apparatus (not shown).
[0032]
[Problems to be solved by the invention]
As described above, since the conventional optical disc is formed between the land track and the groove track by shifting the sector identification information from the center of the track, the sector identification information can be obtained regardless of which track the beam spot is traveling. Playback / detection is possible. In addition, since it is not necessary to form sector identification information for each land track and groove track, there is an advantage that the number of steps during optical disc mastering can be reduced.
[0033]
However, as described above, since one sector identification information is shared between the land track and the groove track, it is difficult to specify the sector only by address reproduction, and either the land track or the groove track is reproduced. Separate information is also required to indicate whether it is inside.
[0034]
Further, since the sector identification information is arranged at a position displaced with respect to the track center, when the beam spot is track offset to a position away from the sector identification information in the radial direction, the reproduction signal amplitude from the sector identification information is deteriorated, Therefore, there is a problem that the address detection accuracy is lowered. If the address cannot be detected with high accuracy, the reliability of the recording or reproducing operation is lowered.
[0035]
Furthermore, it is difficult to identify whether a reproduction track is a land track or a groove track only by detecting sector identification information.
[0036]
In order to solve such a problem, there is an optical disc in which the arrangement of sector identification information has been revised as shown in FIG. The feature of this arrangement is that one sector identification information is divided into two areas, one (hereinafter referred to as first identification information) on the outer circumference side with respect to the track center, and the other (second in the future). Is arranged at a certain distance on the inner peripheral side with respect to the radial direction. The optimum value of the displacement is desirably about 1/2 of the track pitch.
[0037]
If this sector identification signal is used for tracking control, the tracking offset can be canceled. That is, the beam spot position where the reproduction amplitude of the first identification information reproduced by the subtracting means and the reproduction amplitude of the second identification information are the same is the track center.
[0038]
Further, by using the difference in detection time between the first identification information area and the second identification information area, the track on which the beam spot is traveling can be determined. That is, when the beam spot is traveling on the land track, first identification information is detected first, and then second identification information is detected. On the other hand, when traveling on the groove track, the second identification information is detected first, and then the first identification information is detected. If this relationship is used, it is possible to determine whether the reproduction track is a land or a groove by simply reproducing the sector identification information, and further, it is possible to specify up to the sector.
[0039]
However, in the above-described conventional optical information reproducing apparatus, since the sector identification information is assumed to be displaced in only one direction with respect to the track center, the polarity is obtained only in track units such as land tracks or groove tracks. The reversing means could not be controlled. In such a configuration, there is a problem that the polarity of the signal cannot be controlled by one sector identification information unit. Therefore, when an optical disc as shown in FIG. 21 is reproduced by a conventional optical information reproducing apparatus, only the output of the adding means can be used to detect the sector identification signal, and the push-pull signal output from the subtracting means cannot be used. Become. In this case, there is a problem that the first identification information and the second identification information cannot be individually detected, and it is impossible to determine whether the reproduction track is a land or a groove only from the detected sector identification information.
[0040]
Furthermore, when reproducing sector identification information, there is no determination means for selecting whether to use the output of the addition means or the subtraction means for reproduction, for example, there is no quantitative determination means such as address detection accuracy. Depending on the address, the address detection accuracy may decrease. When There was a problem.
[0041]
The present invention relates to an optical information reproducing apparatus for reproducing information from an optical disc having an arrangement of sector identification information as shown in FIG. 21, and has been made to solve the problems in the conventional apparatus as described above. It is.
[0042]
The first purpose is that the sector identification information representing address information and the like at the head of the sector is identically defined on the inner circumference side with the first identification information area in which a certain distance is displaced radially outward from the track center. An optical information reproducing apparatus for reproducing information from an optical disc having a second identification information area arranged at a distance and a user information area in which user information is recorded on the track center following sector identification information is obtained. That is.
[0043]
The second purpose is to detect the first identification information and the second identification information individually by using the expression position information of each of the first identification information and the second identification information in the sector identification information area. By adding together, a means for improving the detection capability of the sector identification information is obtained.
[0044]
Furthermore, the third object is to use the first identification information and the second identification information in the sector identification information area, respectively, and use the first identification information and the second identification information at the analog waveform stage. By reproducing the reproduction waveform of the user information area close to the form of the reproduction waveform from the user information area, a means for reproducing the information after binarizing the analog waveform can be obtained in common with the reproduction of the sector identification information and the reproduction of the user information. It is.
[0045]
A fourth object is to provide an optical information reproducing apparatus that has a plurality of sector identification information reproducing means and selects reproduction data from the optimum reproducing means based on a quantitative determination criterion.
[0046]
[Means for Solving the Problems]
In the optical information reproducing apparatus according to the first aspect of the present invention, at least one set of sector identification information representing address information at the head of the sector is provided on the outer peripheral side and the inner peripheral side in the radial direction with respect to the track center. From the optical disc having the first and second identification information areas arranged at a certain distance, and the user information area in which user information is recorded on the track center following the sector identification information, in the tangential direction of the track On the other hand, as means for reproducing information by using the sum signal and difference signal generated from the outputs of the respective photodetectors divided into at least two, the sector identification information is obtained from the difference signal by the difference signal waveform shaping means. And the second identification information are detected independently, and the user information is detected from the sum signal by the sum signal waveform shaping means and then added together. A.
[0047]
Further, in the optical information reproducing apparatus according to claim 2 of the present invention, as the difference signal waveform shaping means for detecting sector identification information, an expression position of each of the first and second identification information is set. The first identification information and the second identification information are individually detected from the difference signal using the gate signal, and then both are logically added.
[0048]
Furthermore, in the optical information reproducing apparatus according to claim 3 of the present invention, the signals detected by the sum signal waveform shaping means and the difference signal waveform shaping means in order to accurately detect the address from the sector identification information. The detection signal with the higher address detection accuracy is selected. In addition, when reproducing user information, the output of the sum signal waveform shaping means is selected.
[0049]
Furthermore, in the optical information reproducing apparatus according to claim 4 according to the present invention, at least one set of sector identification information representing address information at the head of the sector is provided on the radially outer side and the inner side with respect to the track center. From the optical disc having the first and second identification information areas arranged at a certain distance on the circumferential side and the user information area in which user information is recorded on the track center following the sector identification information, As a means for reproducing information using the sum and difference signals of the outputs of at least two photodetectors divided in the tangential direction, the reproduction waveform has a reference level according to the direction of displacement for detecting sector identification information. The difference signal waveform having a polarity different from that of the upper side and the lower side is analog-processed by the difference signal processing means in a form similar to the sum signal waveform, and the user information The detection of the after selecting the sum signal, respectively, is obtained as binarized by the waveform shaping means.
[0050]
Further, in the optical information reproducing apparatus according to claim 5 of the present invention, as the above-mentioned difference signal processing means, the sector identification information is a portion displaced with respect to the track center, and the difference according to the direction of displacement. The signal and the inverted signal of the difference signal are switched by the switch means.
[0051]
Further, in the optical information reproducing apparatus according to claim 6 of the present invention, as the switching signal generating means of the above-mentioned switch means, a gate generating means for indicating the expression position of each of the first and second identification information; It is constituted by a difference signal waveform polarity determination means.
[0052]
Furthermore, in the optical information reproducing apparatus according to claim 7 of the present invention, as another implementation method of the above-mentioned difference signal processing means, a DC component for removing the DC component of the difference signal with a predetermined time constant. Removing means; first and second gate generating means for generating gates indicating the expression positions of the first and second identification information; and means for generating a boost gate for switching the time constant of the DC component removing means from the gate signal. Thus, the time constant of the DC component removing means is reduced for a certain period from the starting points of the first and second identification information.
[0053]
Further, in the optical information reproducing apparatus according to claim 8 of the present invention, in order to detect the address from the sector identification information with high accuracy, the higher one of the output of the sum signal and the difference signal processing means has the higher address detection accuracy. After the reproduction signal is selected, it is binarized by waveform shaping means. In addition, when reproducing user information, the sum signal waveform is selected and binarized by the waveform shaping means.
[0054]
DETAILED DESCRIPTION OF THE INVENTION
In the optical information reproducing apparatus according to the embodiment of the present invention, at least one set of sector identification information representing address information or the like at the head of a sector is a fixed distance on the outer circumferential side and the inner circumferential side with respect to the track center. By separately detecting the first and second identification information areas arranged in a displaced manner and the user information areas in which user information and the like are recorded on the track center following the sector identification information, respectively, under optimum conditions, The information detection capability is improved.
[0055]
Further, in order to detect the sector identification information, the first and second identification information are individually detected by the gate signal indicating the expression position of each of the first and second identification information, and then both are logically added. It is a thing.
[0056]
Furthermore, in order to detect the address accurately from the sector identification information, the address detection accuracy is used as the determination information, and a signal from the signal reproduction means with high detection accuracy is selected from the signal reproduction means for reproducing the information from the sum signal or the difference signal. It is what you do.
[0057]
Furthermore, in the optical information reproducing apparatus according to the present invention, the sector identification information and the user information are reproduced differently, the sector identification information is reproduced using a difference signal, and the user information is reproduced using a sum signal. In the device, the reproduction waveform from the first and second identification information is processed in an analog manner similar to the reproduction waveform from the user information area by using the expression position information of each of the first and second identification information. Thus, the blocks after the waveform shaping circuit for detecting information from the analog signal are shared by both signals.
[0058]
In addition, in order to make the polarity of the waveform reproduced from the first and second identification information the same as the polarity of the waveform reproduced from the user information area, the first and second identification information according to the displacement direction with respect to the track center. Thus, the difference signal and the inverted signal of the difference signal are switched by the switch means.
[0059]
Further, the above-mentioned switch means is constituted by polarity determination means for generating a switching signal corresponding to an information area for switching the polarity of the reproduction waveform based on the gate signal indicating the expression position of each of the first and second identification information. It is what you do.
[0060]
In addition, the sector identification information and the user information reproduction method are different, the sector identification information is a difference signal, and the user information is a sum signal. The waveform shaping circuit for detecting information from the analog signal is shared by both signals by removing the time constant and processing both signals in an analog manner. Furthermore, the time constant of the DC component removing means is reduced for a certain period from the starting point of each of the first and second identification information from the gate signal indicating the expression position of the first and second identification information, so that the steady state can be achieved at high speed. It is intended to converge to the level.
[0061]
In addition, in order to accurately detect the address from the sector identification information, the waveform shaping unit selects the reproduction signal from the optimum reproduction unit from the difference signal or the sum signal based on a quantitative determination criterion such as address detection accuracy. It is designed to be binarized.
[0062]
Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof. However, blocks with the same reference numerals as in the conventional example in the embodiment are basically the same as those in the optical information reproducing apparatus in the conventional example shown in FIG.
[0063]
Embodiment 1 FIG.
FIG. 1 shows an optical information reproducing apparatus according to Embodiment 1 of the present invention. In the figure, 11 is an optical disk, 12 is a spindle motor, 13 is an optical head, 14 is first I / V conversion means, 15 is second I / V conversion means, 16 is addition means, and 31 is addition means 16. A sum signal waveform shaping means for detecting information recorded on the disk by binarizing at the slice level obtained from the asymmetry correction means after processing the output, and this asymmetry correction means includes a control gate generation means described later. It also has a boost function that increases the asymmetry correction speed by the generated boost gate (BST). 18 is a subtracting means, 27 is a difference signal waveform shaping means for detecting information recorded on the disc by binarizing after processing the output of the subtracting means 18, 21 is a selector means, 22 is a reproduction clock generating means, Reference numeral 23 denotes data demodulating means, 24 denotes address information reproducing means, and 25 denotes control gate generating means for generating a control gate based on the timing of the address reproduction completion signal from the address information reproducing means 24. Furthermore, the optical head 13 includes a laser diode (LD) 131, a collimator lens 132, a beam splitter (BS) 133, a condenser lens 134, and a photodetector (PD) 135.
[0064]
Further, the difference signal waveform shaping means 27 includes first identification information detection means 28 for detecting first identification information arranged to be displaced to the outer circumference side with respect to the track center by sector identification information, and an inner circumference Second identification information detecting means 29 for detecting the second identification information arranged displaced to the side, the output from the first identification information detecting means and the output from the second identification information detecting means It is composed of three blocks of logical addition means 30 for taking a logical sum.
[0065]
The operation when the optical disk shown in FIG. 21 is reproduced by the optical information reproducing apparatus of the embodiment configured as described above will be described with reference to FIGS. FIG. 2 shows waveforms at various parts in FIG.
[0066]
First, the operation of reproducing information on the optical disk 11 from the output of the adding means 16 will be described. The analog signal output from the adding means 16 shown in FIG. 2 (a) is processed by the sum signal waveform shaping means 31 so that the signal amplitude is constant, and further the waveform deterioration due to the frequency characteristics of the optical system is equalized. After being improved by the means, it is binarized by the level slicing means, and the waveform shown in FIG. At this time, the level slice means optimally controls the slice level with the sector identification information and the user information so that the reproduction error is minimized. In order to shorten the convergence time of the optimum control, a boost function is added to the slice level setting unit constituting the level slicing means, and a boost signal (for a certain period immediately after the start point of information from the control gate generating means 25 ( BST) sets the slice level to the optimum value at high speed.
[0067]
Next, the operation of reproducing the sector identification information in the sector identification information area 1 on the optical disk 11 from the output of the subtracting means 18 will be described. The output waveform from the subtracting means 18 is the waveform shown in FIG. 2B or FIG. 2B when the beam spot travels in the center of the track. Here, the difference between (b) and (b 2) indicates that the polarity of the output waveform of the subtracting means 18 changes depending on whether the track on which the beam spot is traveling is a land track or a groove track. That is, the polarity of this output waveform depends on the direction of displacement of the sector identification information when the beam spot position is used as a reference. When reproducing a disk in which the arrangement of the sector identification information and the track center have the relationship shown in FIG. 21, the sector identification information is reproduced while the beam spot is traveling along the track center. Will be playing with. In this case, the difference between the outputs of the two-divided photodetectors 135 becomes the maximum, and the output of the subtracting means 18, that is, the push-pull signal takes a maximum value or a minimum value. As a result, the reproduction signal from the first identification information displaced to the outer circumference side with respect to the track center and the reproduction signal from the second identification information displaced to the inner circumference side are centered on the 0 level (or reference level). Waveforms with different signal polarities.
[0068]
In contrast to the sector identification information area, the beam spot travels in the center of the track in the user information area, so that the outputs of the two-divided photodetectors 135 are the same, and the output of the subtracting means 18 is 0 (or the reference level).
[0069]
The analog signal output from the subtracting means 18 is reproduced by the difference signal waveform shaping means 27 so that the first and second identification information are separately reproduced by the first identification information detecting means 28 and the second identification information detecting means 29. After being binarized by the processing system, it is logically added by the logical adder 30 and output to the selector 21.
[0070]
Here, the first identification information detection unit 28 includes a first gate generation unit 281 and a first data detection unit 282. The case where the output from the subtracting means 18 is as shown in FIG. The first gate generation unit 281 generates a gate signal (FIG. 2D) indicating the first identification information area from the output of the subtraction unit 18. Further, the first data detecting means 282 processes the output of the subtracting means 18 so that the signal amplitude becomes constant, and further improves the waveform deterioration due to the frequency characteristic of the optical system by the equalizing means, and then the level. Binarization is performed by the slicing means (FIG. 2 (f)). At this time, the first data detection unit 282 stops the signal detection operation while the gate signal generated by the first gate generation unit 281 is closed, and does not detect signals other than the first identification information area. Like that. Further, the level slicing means optimally controls the slice level so that the reproduction error of the first identification information is minimized. In order to shorten the convergence time of the optimum control, a boost function is added to the slice level setting unit constituting the level slice means. With this function, the slice level is set to the optimum value at high speed for a certain period immediately after the start point of the gate signal from the first gate generation means 281.
[0071]
Further, the second identification information detection means 29 has the same configuration as the first identification information detection means 28 described above, and is composed of a second gate generation means and a second data detection means. The second gate generation means 291 generates a gate signal (FIG. 2 (e)) indicating the second identification information area from the output of the subtraction means 18. Further, the second data detecting means 292 processes the output of the subtracting means 18 so that the signal amplitude becomes constant, and further improves the waveform deterioration caused by the frequency characteristic of the optical system by the equalizing means, and then the level. Binarization is performed by the slicing means (FIG. 2 (g)). At this time, the second data detection unit 292 stops the signal detection operation while the gate signal generated by the second gate generation unit 291 is closed, and does not detect signals other than the second identification information area. Like that. The level slicing means optimally controls the slice level so that the reproduction error of the second identification information is minimized. In order to shorten the convergence time of the optimum control, a boost function is added to the slice level setting unit constituting the level slicing means, and this function makes it constant immediately after the start point of the gate signal from the second gate generating means 291. The period slice level is set to the optimum value at high speed.
[0072]
The outputs of the first identification information detection means 28 and the second identification information detection means 29 are logically added by the logical addition means 30 and output to the selector means 21 as shown in FIG. .
[0073]
Next, a method for reproducing sector identification information such as a track address and sector address and user information such as user data from signals binarized by the sum signal waveform shaping means 31 and the difference signal waveform shaping means 27 will be described.
[0074]
When the sector identification information and the user information are reproduced using the output of the sum signal waveform shaping means 31, the selector means 21 is set to always select the output of the sum signal waveform shaping means 31.
[0075]
When the output of the difference signal waveform shaping unit 27 is used for reproducing the sector identification information and the output of the sum signal waveform shaping unit 31 is used for reproducing the user information, the selector unit 21 switches each signal. The signal shown in FIG. 2 (j) is obtained. The selector 21 is switched by a switching signal (FIG. 2 (i)) from the control gate generator 25. The switching signal may be generated by an internal timer with the address detection completion timing from the address information reproducing means 24 as a starting point, for example.
[0076]
The output of the selector unit 21 is input to the reproduction clock generation unit 22, the data demodulation unit 23, and the address information reproduction unit 24.
[0077]
The regenerated clock generating means 22 generates a regenerated clock synchronized with the output signal from the selector means 21 by means of a PLL (Phase Locked Loop) means. At this time, the reproduction clock generation means 22 is configured to operate in an area where information to be reproduced exists by a read gate (RG) from the control gate generation means 25.
[0078]
The address information reproducing means 24 reproduces the sector identification information by discriminating whether the output signal from the selector means 21 is the information “1” or “0” at the timing of the reproduced clock from the reproduced clock generating means 22, and then the address is obtained. To detect.
[0079]
The data demodulating means 23 determines whether the output signal of the selector means 21 is information “1” or “0” at the timing of the reproduction clock from the reproduction clock generation means 22, and then performs decoding, error correction and de-interleaving processing. To demodulate the data.
[0080]
As described above, the control gate generation unit 25 generates the switching signal of the selector unit 21 and the read gate of the reproduction clock generation unit 22 by using an internal timer with the address detection completion timing from the address information reproduction unit 24 as a starting point.
[0081]
FIG. 3 shows a more specific configuration of the first gate generation unit 281 and the second gate generation unit 291. FIG. 4 shows the waveforms of the respective parts. Here, the first gate generation unit 281 includes a first comparator level setting unit 283, a first comparator unit 284, and a first one-shot unit 285. The second gate generation unit 291, the second comparison level setting unit 293, the second comparison unit 294, and the second one-shot unit 295 are configured.
[0082]
Next, the operation of the first gate generation unit 281 will be described. The first comparing means 284 compares the output of the subtracting means 18 shown in FIG. 4 (b) with the output (Vth3) from the first comparator level setting means 283, so that FIG. 4 (k) is obtained. The presence or absence of first identification information as shown is detected. Here, the first comparator level setting means 283 sets the slice level (Vth3) for detecting the first identification information to the optimum value by, for example, a method of subtracting a constant value from the upper envelope. In some cases, a method of setting a fixed value may be used. However, if the output signal level of the subtracting means 18 deviates from the detection dynamic range of the first gate generating means 281, a level adjustment function can be added between the subtracting means 18 and the first gate generating means 281. Good.
[0083]
The output of the first comparing means 284 is obtained by level slicing the reproduced waveform, and a detection signal depending on the data pattern is obtained. Therefore, in order to obtain the gate signal (FIG. 4 (d)) indicating the expression position of the first identification signal, a pulse having a certain time width set longer than the longest interval appearing in the data pattern by the first one-shot means 285. (FIG. 4 (l)) and the output of the first comparing means 284 must be masked with this pulse. Here, the first one-shot means 285 generates a pulse having a certain time width starting from the rising or falling edge of the output of the first comparing means 284. Therefore, when a subsequent edge is input within this fixed time width, the pulses are continuously connected without changing the state.
[0084]
The configuration and operation of the second gate generation unit 291 are basically the same as those of the first generation unit 281. However, the operation of the second comparator level setting unit 293 is opposite to that of the first comparator level setting unit 283, and the second identification information is detected by, for example, a method of adding a constant value to the lower envelope. For this, the slice level (Vth4) is set to an optimum value. In some cases, a method of setting a fixed value may be used.
[0085]
FIG. 5 shows another embodiment for the first gate generation means 281 and the second gate generation means 291. FIG. 6 shows the waveforms of the respective parts. Here, the first gate generation unit 281 includes an upper envelope detection unit 286, a first comparison level setting unit 283, and a first comparison unit 284. The second gate generation unit 291, the lower envelope detection unit 296, the second comparator level setting unit 293, and the second comparator unit 294 are configured.
[0086]
Next, the operation of the first gate generation means 281 will be described with reference to FIGS. The upper envelope detection means 286 detects the upper envelope of the output of the subtraction means 18 and outputs a signal indicated by (m) in FIG. The first comparator 284 compares the output with the output (Vth3) from the first comparator level setting unit 283, thereby generating the first identification information as shown in FIG. A gate signal indicating the position is generated. Here, the first comparator level setting means 283 sets the slice level (Vth3) for detecting the first identification information to the optimum value by subtracting a constant value from the output of the upper envelope detection means 286. To do. In some cases, a fixed value may be used. However, if the output signal level of the subtracting means 18 deviates from the detection dynamic range of the first gate generating means 281, a level adjustment function can be added between the subtracting means 18 and the first gate generating means 281. Good.
[0087]
Next, the operation of the second gate generation unit 291 will be described. The lower envelope detection means 296 detects the lower envelope of the output of the subtraction means 18 and outputs a signal indicated by (n) in FIG. The second comparator 294 compares this output with the output (Vth4) from the second comparator level setting unit 293, thereby generating the second identification information as shown in FIG. A gate signal indicating the position is generated. Here, the second comparator level setting means 293 uses the optimum value for the slice level (Vth4) for detecting the second identification information, such as by adding a constant value to the output of the lower envelope detection means 296. Set to. In some cases, a fixed value may be used. However, if the output signal level of the subtracting means 18 deviates from the detection dynamic range of the second gate generating means 291, a level adjusting function can be added between the subtracting means 18 and the second gate generating means 291. Good.
[0088]
Embodiment 2. FIG.
FIG. 7 is a diagram showing an optical information reproducing apparatus according to Embodiment 2 of the present invention. The difference from the first embodiment is that, at the time of sector identification information reproduction, the selector means 21 selects the output of the sum signal waveform shaping means 31 and the output of the difference signal waveform shaping means 27 in accordance with the address detection accuracy to reproduce the address information. This is that a function of detecting an address by outputting to the means 24 is added.
[0089]
In the figure, 11 is an optical disk, 12 is a spindle motor, 13 is an optical head, 14 is first I / V conversion means, 15 is second I / V conversion means, 16 is addition means, 18 is subtraction means, 21 Is a selector means, 22 is a reproduction clock generation means, 23 is a data demodulation means, 24 is an address information reproduction means, 25 is a control gate generation means, 26 is a controller, 27 is a difference signal waveform shaping means, and 28 is a difference signal waveform shaping means. The first identification information detection means, which is a component of the second identification information detection means 29, the second identification information detection means 29, which is a constituent element of the difference signal waveform shaping means, and the logic addition means 31, which is a component of the difference signal waveform shaping means, 31 Indicates sum signal waveform shaping means. The above blocks are the same as the blocks shown in FIG. 1 described in the first embodiment, and their operations are basically the same.
[0090]
A block different from FIG. 1 will be described. Reference numeral 32 denotes an output signal of the first gate generation means 281 constituting the first identification information detection means 28 and a second gate generation means constituting the second identification information detection means 29. OR means for logically adding the output signals of 291; 33, switch means for switching the output of the OR means and the output of the control gate generation means in accordance with the control signal from the controller 26; 34, the control signal output from the controller 26; Switch means 33 AND means for outputting a gate signal for operating the selector means 21 by taking the AND of the output signals.
[0091]
Next, an operation of selecting the output of the sum signal waveform shaping means 31 and the output of the difference signal waveform shaping means 27 by the selector means 21 in accordance with the address detection accuracy during sector identification information reproduction will be described.
[0092]
The OR unit 32 logically adds the output signal of the first gate generation unit 281 and the output signal of the second gate generation unit 291 to generate a gate signal for discriminating the sector identification information area. This gate signal is also generated by the control gate generation means. The switch means 33 selects one of the two gate signals under the control of the controller 26 and outputs it to the AND means 34 (FIG. 2 (i)).
[0093]
Here, the controller 26 receives the result of the reproduction address correctness determination performed by the address information reproduction means 24 in the address reproduction process, and derives the address detection accuracy. Based on this result, the controller 26 outputs “LOW” to the AND unit 34 when address information is detected from the output of the sum signal waveform shaping unit 31, and the address information is output from the output of the difference signal waveform shaping unit 27. "HIGH" is output when the signal is detected.
[0094]
The AND means 34 outputs a control signal for controlling the selector means 21 according to the control signal from the controller 26. When the output of the controller 26 is “LOW”, the output of the AND means 34, that is, the control signal of the selector means 21 is also “LOW”. As a result, the selector unit 21 selects the output of the constant signal waveform shaping unit 31 at all times. Further, when the output of the controller 26 is “HIGH”, the control signal of the selector means 21 becomes the output signal of the switch means 33. For this reason, the selector means 21 selects the output of the difference signal waveform shaping means 27 when reproducing the sector identification information area, and the output of the sum signal waveform shaping means 31 for the data information area.
[0095]
Further, although not shown, in a situation where only sector identification information needs to be detected such as when the drive is started or accessed, the selector means 21 has a function of always selecting the output of the difference signal waveform shaping means 27. Also good. That is, as described above, the reproduction signal from the user information area is almost zero and the reproduction signal from the sector identification information area is output at the output of the subtracting means 18, so that the sector identification information can be easily detected. There is an advantage.
[0096]
Embodiment 3 FIG.
FIG. 8 is a diagram showing an optical information reproducing apparatus according to Embodiment 3 of the present invention. In the figure, 11 is an optical disk, 12 is a spindle motor, 13 is an optical head, 14 is first I / V conversion means, 15 is second I / V conversion means, 16 is addition means, 18 is subtraction means, 22 Is a reproduction clock generation means, 23 is a data demodulation means, 24 is an address information reproduction means, and 25 is a control gate generation means. The above blocks are the same as the blocks shown in FIG. 1 described in the first embodiment, and their operations are basically the same.
[0097]
A block different from FIG. 1 will be described. Reference numeral 35 denotes difference signal processing means, 36 denotes signal switching means, and 37 denotes waveform shaping means. The difference signal processing unit 35 includes a buffer amplifier 351, an inverting buffer amplifier 352, a polarity switching signal generation unit 353, and an analog switch unit 354.
[0098]
Next, the operation will be described. FIG. 9 shows waveforms at various parts in FIG. The feature of this optical information reproducing apparatus is that the output signal of the subtracting means 18 is processed in an analog manner to be converted into a waveform similar to the output signal of the adding means 16. By doing so, there is an advantage that the blocks after the waveform shaping means can be shared and the circuit scale can be reduced.
[0099]
The polarity switching signal generating means 353 constituting the difference signal processing means 35 is a discrimination gate signal (FIG. 9 (o)) for discriminating the first identification information from the output signal (FIG. 9 (b)) of the subtraction means 18. Is generated. In response to this discrimination gate signal, the analog switch means 354 selects either the output of the buffer amplifier 351 (FIG. 9 (p)) or the output of the inverting buffer amplifier 352 (FIG. 9 (q)). As a result, the output signal waveform of the difference signal processing means 35 (FIG. 9 (r)) is similar to the output waveform of the adding means 16 (FIG. 9 (a)) in terms of polarity.
[0100]
The signal switching means 36 selects the output of the adding means 16 and the output of the difference signal processing means 35 according to the switching signal from the control gate generating means 25 (FIG. 9 (i)), and outputs it to the waveform shaping means 37. . This switching signal can be generated by an internal timer starting from the address detection completion timing from the address information reproducing means 24, for example. Further, when the reproduction of the sector identification information is detected from the output of the adding means 16 in the same manner as the reproduction of the user information, the control gate generating means 25 always selects the output of the adding means 16 for the signal switching means 36. You only have to set it.
[0101]
The waveform shaping means 37 performs processing so that the output signal amplitude of the signal switching means 36 becomes constant, further improves the waveform deterioration caused by the frequency characteristic of the optical system by the equalization means, and then binarizes it by the level slice means. The waveform shown in FIG. 9 (t) is output. At this time, the level slice means optimally controls the slice level with the sector identification information and the user information so that the reproduction error is minimized. In order to shorten the convergence time of the optimum control, a boost function is added to the slice level setting unit constituting the level slicing means, and a boost signal (for a certain period immediately after the start point of information from the control gate generating means 25 ( BST) sets the slice level to the optimum value at high speed.
[0102]
Regarding the operation of reproducing address information and data information, first, the output of the waveform shaping means 37 is input to the reproduction clock generation means 22, the data demodulation means 23, and the address information reproduction means 24.
[0103]
The reproduction clock generation means 22 generates a reproduction clock synchronized with the output signal from the waveform shaping means 37 by means of a PLL (Phase Locked Loop) means. At this time, the reproduction clock generation means 22 is configured to operate in an area where information to be reproduced exists by a read gate (RG) from the control gate generation means 25.
[0104]
The address information reproducing means 24 reproduces the sector identification information by discriminating whether the output signal from the waveform shaping means 37 is information "1" or "0" at the timing of the reproduction clock from the reproduction clock generating means 22, and then addresses Is detected.
[0105]
The data demodulating unit 23 determines whether the output signal of the waveform shaping unit 37 is information “1” or “0” at the timing of the reproduction clock from the reproduction clock generation unit 22, and then performs decoding, error correction, and de-interleaving processing. Data is demodulated by applying.
[0106]
As described above, the control gate generation unit 25 generates the switching signal of the signal switching unit 36 and the read gate of the reproduction clock generation unit 22 by the internal timer with the address detection completion timing from the address information reproduction unit 24 as a starting point.
[0107]
As shown in FIG. 10, the embodiment of the polarity switching signal generating means 353 includes the above-described first gate generating means 281, the above-mentioned second gate generating means 291, and the polarity determining means 355. Further, the polarity determination unit 355 includes an RS flip-flop unit 356 and an AND unit 357. Moreover, the waveform of each part is shown in FIG. 11 and FIG.
[0108]
Here, assuming that the difference signal processing unit 35 inverts the reproduction signal from the first identification information with respect to the reference level, the operation of the polarity switching signal generation unit 353 will be described.
[0109]
First, when the analog switch unit 354 is operated by the output of the first gate generation unit 281 and the reproduction signal from the first identification information is inverted with respect to the reference level, the following problem occurs. Since the first gate generation means 281 uses a one-shot means or envelope detection means as shown in FIG. 3 or FIG. 5, a time delay occurs between the timing when the output closes and the reproduction waveform ( Figure 6 , Τ1, τ2). Therefore, as shown in FIG. 11, when the first identification information is earlier than the second identification information in time, the output (FIG. 11 (d)) of the first gate generation means 281 is one of the second identification information. Will be included. As a result, in the output of the analog switch means 354, the reproduction signal is lost for a predetermined time from the start point of the second identification information. In order to reduce the loss of the reproduction signal, the polarity determination means 355 is necessary.
[0110]
The operation of the polarity determination unit 355 will be described. The output of the first gate generation means 281 is input to the set terminal of the RS flip-flop means 356, and the output of the second gate generation means 291 is input to the reset terminal. The AND output of the Q output of the RS flip-flop means 356 and the output of the first gate generation means 281 is ANDed by the AND means 357, whereby a first identification information area as shown in FIG. 11 and FIG. It is possible to generate a gate signal that specifies only the signal.
[0111]
Although the case where the difference signal processing means 35 inverts the reproduction signal from the first identification information with respect to the reference level has been described above, the reproduction signal from the second identification information is inverted with respect to the reference level. Needless to say, the same method can be used.
[0112]
FIG. 13 shows another embodiment of the difference signal processing means 35. In the figure, reference numeral 281 denotes the first gate generation means, 291 denotes the second gate generation means, 350 denotes a DC component removal means, and 360 denotes a boost gate generation means. The direct current component removing means 350 also has a function of changing the time constant of direct current component removal by an external control signal. The boost gate generating unit 360 includes a third one-shot unit 361 and a fourth one-shot unit 362.
[0113]
Next, the operation will be described with reference to FIG. The third one-shot unit 361 generates a pulse having a predetermined width starting from the rising edge of the output signal of the first gate generation unit 281. The fourth one-shot means 362 generates a pulse having a predetermined width starting from the rising edge of the output signal of the second gate generation means 291. These two output pulses are added by an OR gate to output the waveform shown in FIG.
[0114]
The direct current component removing means 350 converts the output signal (b) or (b 2) of the subtracting means into a waveform similar to the output from the adding means (FIG. 14 (r)) by removing the direct current component. At this time, the direct current component removing means 350 reduces the direct current component removal time constant by a control signal from the OR gate for a predetermined time from the start point of the first identification information and the second identification information, thereby rapidly Can be removed.
[0115]
Embodiment 4 FIG.
FIG. 15 is a diagram showing an optical information reproducing apparatus according to Embodiment 4 of the present invention. FIG. 16 shows the waveforms of the respective parts. Here, the difference from the third embodiment is that, when reproducing the sector identification information, the output of the adding means 16 and the output of the difference signal processing means 35 are selected by the signal switching means 36 according to the address detection accuracy, and the waveform shaping means 37 is selected. Is added to the function of detecting the address by outputting to.
[0116]
In the figure, 11 is an optical disk, 12 is a spindle motor, 13 is an optical head, 14 is first I / V conversion means, 15 is second I / V conversion means, 16 is addition means, 18 is subtraction means, 22 Is a reproduction clock generation means, 23 is a data demodulation means, 24 is an address information reproduction means, 25 is a control gate generation means, 35 is a difference signal processing means, 36 is a signal switching means, and 37 is a waveform shaping means. The above blocks are the same as the blocks shown in FIG. 8 described in the third embodiment, and their operations are basically the same.
[0117]
The block different from FIG. 8 will be described. 32 is an OR means for logically adding the output signal of the first gate generating means 281 and the output signal of the second gate generating means 291 that constitute the difference signal processing means 35, and 33 is Switch means 34 for switching the output of the OR means 32 and the output of the control gate generating means 25 in accordance with the control signal from the controller 26, 34 is obtained by ANDing the control signal output from the controller 26 and the output signal of the switch means 33. AND means for outputting a gate signal for operating the signal switching means 36 is shown.
[0118]
Next, an operation of selecting the output of the adding means 16 and the output of the difference signal processing means 35 by the signal switching means 36 in accordance with the address detection accuracy when reproducing the sector identification information will be described.
[0119]
The OR unit 32 logically adds the output signal of the first gate generation unit 281 and the output signal of the second gate generation unit 291 to generate a gate signal for discriminating the sector identification information area. This gate signal is also generated by the control gate generation means. The switch means 33 selects either one of the two gate signals under the control of the controller 26 and outputs it to the AND means 34 (FIG. 16 (i)).
[0120]
Here, the controller 26 receives the result of the reproduction address correctness determination performed by the address information reproduction means 24 in the address reproduction process, and derives the address detection accuracy. Based on this result, the controller 26 outputs “LOW” to the AND unit 34 when detecting address information from the output of the adding unit 16 (FIG. 16A), and outputs the difference signal processing unit 35. When the address information is detected from (FIG. 16B), “HIGH” is output.
[0121]
The AND means 34 outputs a control signal for controlling the signal switching means 36 in accordance with a control signal from the controller 26. When the output of the controller 26 is "LOW", the output of the AND means 34, that is, the control signal of the signal switching means 36 is also "LOW". As a result, the signal switching unit 36 selects the output of the constant addition unit 16 at all times. Further, when the output of the controller 26 is “HIGH”, the output signal of the switch means 33 is selected as the control signal of the signal switching means 36. Therefore, as shown in FIG. 16 (s), the signal switching means 36 selects the output of the difference signal processing means 35 when reproducing the sector identification information area and the output of the addition means 16 for the data information area. .
[0122]
Further, although not shown, in a situation where only sector identification information needs to be detected such as when the drive is started or accessed, the signal switching means 36 has a function of always selecting the output of the difference signal processing means 35. Also good. That is, as described above, the reproduction signal from the user information area is almost zero and the reproduction signal from the sector identification information area is output at the output of the subtracting means 18, so that the sector identification information can be easily detected. There is an advantage.
[0123]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0124]
In the optical information reproducing apparatus according to the first aspect of the present invention, the first and first sector identification information are arranged with a certain distance displaced from the track center on the outer circumferential side and the inner circumferential side, respectively. When the two identification information areas are reproduced, the first identification information and the second identification information are detected by the individual detection system by the difference signal waveform shaping means. Further, when reproducing user information recorded on the center of the track, the sum signal waveform shaping means detects it. Each output is logically added. As described above, by detecting the first identification information, the second identification information, and the user information by the individual detection system, the detection condition can be optimized for each information, and as a result, the detection accuracy of the information is improved. improves.
[0125]
In the optical information reproducing apparatus according to the second aspect of the present invention, in principle, a signal is output only from the sector identification information area, and the polarity of the reproduction signal from the first and second identification information is the same. By generating a gate signal indicating the expression position of each of the first and second identification information from the difference signal output different from the reference level, the expression position of the first and second identification information is specified with high accuracy. It becomes possible. Further, by masking the detection means with this gate in areas other than the first and second identification information areas, erroneous detection outside each identification information area can be prevented, and the sector identification information detection capability is improved.
[0126]
In the optical information reproducing apparatus according to the third aspect of the present invention, when the sector identification information is reproduced, the signal having the higher address detection accuracy among the signals detected by the sum signal waveform shaping means and the difference signal waveform shaping means. By selecting the detection signal, it is possible to detect the address from the sector identification information with high accuracy.
[0127]
In the optical information reproducing apparatus according to claim 4 according to the present invention, the difference signal from the sector identification information and the sum signal from the user information are processed so as to be analogly similar to each other, thereby obtaining an analog signal. The blocks after the waveform shaping circuit for detecting information from the signal can be shared by both signals, and the circuit scale can be reduced.
[0128]
6. The optical information reproducing apparatus according to claim 5, wherein the sector identification information is a portion displaced from the track center, and the difference signal and the inverted signal of the difference signal are switched according to the direction of displacement. By switching at, the form of the difference signal waveform can be brought close to the form of the sum signal waveform, and the blocks after the waveform shaping means can be shared by the processing of the difference signal waveform and the sum signal waveform.
[0129]
In the optical information reproducing apparatus according to claim 6 of the present invention, the switching signal generating means of the above-mentioned switch means is a gate generating means for indicating the expression positions of the first and second identification information, R- This can be easily realized by the configuration of the S flip-flop and the AND gate.
[0130]
In the optical information reproducing apparatus according to claim 7 of the present invention, the difference signal and the sum signal are processed in an analogly similar form by removing the DC component of the difference signal with a predetermined time constant. Is possible. In addition, the DC component can be removed at high speed by reducing the time constant for removing the DC component for a certain period from the starting points of the first and second identification information.
[0131]
In the optical information reproducing apparatus according to claim 8 of the present invention, the reproduction signal from the optimum reproducing means is selected from the difference signal or the sum signal based on a quantitative determination criterion such as address detection accuracy. After that, binarization by the waveform shaping means makes it possible to accurately detect the address from the sector identification information.
[Brief description of the drawings]
FIG. 1 is a block diagram of an optical information reproducing apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing output waveforms from each block constituting the optical information reproducing apparatus according to the first embodiment of the present invention.
FIG. 3 is a diagram showing first gate generation means and second gate generation means constituting the optical information reproducing apparatus according to the first embodiment of the present invention.
4 is a diagram showing an output waveform of each part in FIG. 3;
FIG. 5 is a diagram showing another example of the first gate generating means and the second gate generating means constituting the optical information reproducing apparatus according to the first embodiment of the present invention.
6 is a diagram showing an output waveform of each part in FIG. 5;
FIG. 7 is a block diagram of an optical information reproducing apparatus according to Embodiment 2 of the present invention.
FIG. 8 is a block diagram of an optical information reproducing apparatus according to Embodiment 3 of the present invention.
FIG. 9 is a diagram showing an output waveform from each block constituting the optical information reproducing apparatus according to the third embodiment of the present invention.
FIG. 10 is a diagram showing polarity switching signal generating means constituting an optical information reproducing apparatus according to Embodiment 3 of the present invention.
11 is a diagram showing an output waveform of each part in FIG. 10;
12 is another diagram showing an output waveform of each part in FIG.
FIG. 13 is a diagram showing difference signal processing means constituting an optical information reproducing apparatus according to Embodiment 3 of the present invention.
14 is a diagram showing an output waveform of each part in FIG. 13;
FIG. 15 is a block diagram of an optical information reproducing apparatus according to Embodiment 4 of the present invention.
FIG. 16 is a diagram showing output waveforms from each block constituting an optical information reproducing apparatus according to Embodiment 4 of the present invention.
FIG. 17 is a diagram showing a track format of a conventional optical disc.
FIG. 18 is a diagram showing the arrangement of a conventional sector identification information section.
FIG. 19 is a block diagram of a conventional optical information reproducing apparatus.
FIG. 20 is a diagram showing output waveforms from each block constituting the conventional optical information reproducing apparatus.
FIG. 21 is a diagram showing an arrangement of another conventional sector identification information section.
[Explanation of symbols]
1 sector identification information area, 2 user information area, 3 groove track, 4 land track, 11 optical disk, 12 spindle motor, 13 optical head, 14 first I / V conversion means, 15 second I / V conversion means, 16 addition means, 17 sum signal detection means, 18 subtraction means, 19 polarity inversion means, 20 difference signal detection means, 21 selector means, 22 reproduction clock generation means, 23 data demodulation means, 24 address information reproduction means, 25 control gate generation Means, 26 controller, 27 difference signal waveform shaping means, 28 first identification information detection means, 29 second identification information detection means, 30 logic addition means, 31 sum signal waveform shaping means, 32 OR means, 33 switch means, 34 AND means, 35 Difference signal processing means, 36 Signal switching means, 37 Waveform shaping means, 131 Laser diode LD (LD), 132 collimator lens, 133 beam splitter, 134 condenser lens, 135 photodetector (PD), 281 first gate generation means, 282 first data detection means, 283 first comparison level setting Means 284, first comparator means, 285 first one-shot means, 286 upper envelope detection means, 291 second gate generation means, 292 second data detection means, 293 second comparison level setting means, 294 second comparator means, 295 second one-shot means, 296 lower envelope detection means, 350 DC component removal means, 351 buffer amplifier, 352 inversion buffer amplifier, 353 polarity switching signal generation means, 354 analog switch means, 355 polarity judgment means, 356 RS flip flow Flop means, 357 the AND means, 360 boost gate generation means, 361 a third one-shot means, 362 a fourth one-shot means,

Claims (8)

Tracks are arranged concentrically or spirally on a disk medium, the tracks are divided into sectors in the circumferential direction, and the sectors have at least one set of sector identification information indicating address information at the head and a radius with respect to the track center. A sector identification information area recorded in the form of first identification information arranged displaced by a certain distance on the outer periphery side in the direction and second identification information arranged displaced by a certain distance on the inner circumference side, and the sector An apparatus for optically reproducing the information from a medium having a user information area in which user information and the like are recorded on the track center following the identification information area,
An optical head that irradiates a medium with a light beam, receives the reflected light by a photodetector that is divided into at least two in the radial direction of the disk with respect to the tangential direction of the track, and converts the light into an electrical signal; and the optical head Subtracting the signal output from the optical head, adding means for adding the signal output from the signal, sum signal waveform shaping means for detecting the information recorded on the disk medium from the output signal of the adding means, When the optical beam traces the center of the track, the reproduction signal from the first identification information and the reproduction signal from the second identification information are respectively above and below the reference level (or below and above). ) And a difference signal wave for detecting information recorded on the disk medium from the output signal of the subtraction means. Shaping means, selector means for switching and selecting the output of the sum signal waveform shaping means and the output of the difference signal waveform shaping means, address information reproducing means for reproducing address information from the output of the selector means, and And user information reproducing means for reproducing user information,
The sector identification information area is independently detected by the difference signal waveform shaping means, and the user information area is independently detected by the sum signal waveform shaping means, and the first identification information and the first identification information are also reproduced in the reproduction of the sector identification information area. An optical information reproducing apparatus for reproducing information by detecting each of the two pieces of identification information independently and then adding the information.   As the difference signal waveform shaping means, a first gate generation means for generating a gate indicating an expression position of the first identification information and an output of the subtraction means during a gate output period from the first gate generation means A first identification information detection means configured by a first data detection circuit for detecting first identification information; a second gate generation means for generating a gate indicating an expression position of the second identification information; A second identification information detecting means comprising a second data detection circuit for detecting the second identification information from the output of the subtracting means during a gate output period from the second gate generating means; After detecting the first identification information and the second identification information independently by comprising logical adder that logically adds the output of the data detection circuit and the output of the second data detection circuit Add together The optical information reproducing apparatus according to claim 1, wherein the reproducing the information of the sector identification information region by which. When the sector identification information area is reproduced, the output of the sum signal waveform shaping means according to the degree of accuracy of address detection (hereinafter referred to as "address detection accuracy") derived from the result of correctness determination of the reproduction address by the address information reproducing means Of the outputs of the difference signal waveform shaping means, the output having the higher address detection accuracy is selected by the selector and output to the address information reproducing means, and the address is detected. 3. An optical information reproducing apparatus according to claim 1, wherein user information is detected by selecting an output of a signal waveform shaping means with the selector and outputting the selected signal to the user information reproducing means. Tracks are arranged concentrically or spirally on a disk medium, the tracks are divided into sectors in the circumferential direction, and the sectors have at least one set of sector identification information indicating address information at the head and a radius with respect to the track center. A sector identification information area recorded in the form of first identification information arranged displaced by a certain distance on the outer periphery side in the direction and second identification information arranged displaced by a certain distance on the inner circumference side, and the sector An apparatus for optically reproducing the information from a medium having a user information area in which user information and the like are recorded on the track center following the identification information area,
An optical head that irradiates a medium with a light beam, receives the reflected light by a photodetector that is divided into at least two in the radial direction of the disk with respect to the tangential direction of the track, and converts the light into an electrical signal; and the optical head Adding means for adding the signal output from the optical head; and subtracting the signal output from the optical head to reproduce the reproduction signal from the first identification information and the second identification while the optical beam traces the track center. and subtracting means for reproducing signals from the information to produce an upper and lower (or lower and upper) with different polarities difference signal waveforms respectively a reference level, the other polarity different one of the polarities of the difference signal waveform and a difference signal processing means for processing the difference signal waveform similar waveform form said adding means output by matching, the output of the difference signal processing means and an output of said adding means A signal switching means for switching, a waveform shaping means for detecting information recorded on the disk medium from an output signal of the signal switching means, and an address for reproducing address information from the output of the waveform shaping means Information reproducing means and user information reproducing means for reproducing user information;
In the reproduction of the sector identification information area, the subtraction means and the difference signal processing means, and in the reproduction of the user information area, the reproduction is performed individually by the addition means, and then the sector identification information is reproduced by the signal switching means. Optical information is reproduced by selecting the output of the difference signal processing means at the time of area reproduction and selecting the output of the adding means at the time of reproducing the user information area and outputting it to the waveform shaping means. Playback device.   As the difference signal processing means, a buffer amplifier for buffering the output of the subtracting means, an inverting buffer amplifier for inverting the output polarity of the subtracting means, and an analog for switching the output of the buffer amplifier and the output of the inverting buffer amplifier 5. The optical information reproducing apparatus according to claim 4, comprising switch means and polarity switching signal generating means for generating switching timing of the analog switch means.   As the polarity switching signal generating means, the first gate generating means for generating the gate indicating the expression position of the first identification information, and the second generating the gate indicating the expression position of the second identification information. 6. The optical information reproducing apparatus according to claim 5, further comprising: a gate generating unit; and a subtracting unit output waveform polarity determining unit.   As the difference signal processing means, a direct current component removing means for removing a direct current component of a difference signal output of the subtracting means with a predetermined time constant, and a first gate for generating an expression position of the first identification information are generated. The direct current component from the outputs of the gate generating means, the second gate generating means for generating the gate indicating the expression position of the second identification information, the first gate generating means, and the second gate generating means Boost gate generating means for generating a boost gate for switching the time constant of the removing means, and when the DC component removing means is in a certain period from the respective start points of the first identification information and the second identification information 5. The optical information reproducing apparatus according to claim 4, wherein the constant is reduced. When the sector identification information area is reproduced, the address information reproducing means
In accordance with the address detection accuracy derived from the correctness / incorrectness determination result of the reproduction address, the output having the higher address detection accuracy among the output of the adding unit and the output of the difference signal processing unit is selected by the selector, and the waveform shaping unit And the address information reproducing means detects the address, and at the time of reproducing the user information area, the output of the adding means is selected by the selector and output to the waveform shaping means, and the user information reproducing means outputs the user information. The optical information reproducing apparatus according to claim 4, wherein

Images