JPH06176404A - Optical disk and optical disk device constituted by using the disk - Google Patents

Abstract

PURPOSE:To obtain identification signals in the recording tracks of either recessed parts or projecting parts of the optical disk formed with the identification signals, such as address information, in correspondence to either of the recording tracks of the recessed parts or the projecting parts. CONSTITUTION:The arrays of prepits 10 are formed as the identification signals by shifting these arrays in a radial direction by 1/4 the pitch of the recording tracks of the recessed parts or the projecting parts from the center line of the recording tracks of the respective recessed parts or the projecting parts. A beam spot 11 overlaps on the prepits 10, is subjected to sufficient modulation and can detect the identification signals even in the recording tracks of the recessed parts 3, 4, 5, 6 or the recording tracks of the projecting parts 7, 8, 9. Since there is no need for forming the prepits in both of the recording tracks of the recessed parts and the recording tracks of the projecting parts, the optical disk is produced by a smaller number of stages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device,
Particularly, the present invention relates to an optical disc device which records a signal on both a recording track of a concave portion and a recording track of a convex portion formed by a guide groove on the disc.

[0002]

2. Description of the Related Art In recent years, an optical disc device capable of recording and reproducing information signals such as video or audio signals has been actively developed. In a recordable optical disk device, a guide groove is previously formed on a substrate of the optical disk to form a track. Information signals are recorded or reproduced by focusing the laser light on the flat portion of the concave or convex portion of the track. In a general optical disk device currently on the market, an information signal is usually recorded in only one of a concave portion and a convex portion, and the other is a guard band for separating adjacent tracks.

FIG. 18 is an enlarged perspective view of an optical disk used in such a conventional optical disk device. In the figure, 201 is a recording layer, which is made of, for example, a phase change material. Reference numeral 202 is a recording pit, and 203 is a beam spot of laser light. Reference numeral 204 is a concave portion formed as a guide groove, 205 is a convex portion between the guide grooves, and the concave portion 204 is wider than the convex portion 205. 206
Is a pre-pit that forms an identification signal representing position information on the disc. Further, in the figure, a transparent disk substrate through which incident light is transmitted is omitted.

A conventional optical disk device using this optical disk will be described with reference to the drawings.

FIG. 19 is a block diagram of such a conventional optical disk device. In the figure, reference numeral 207 is an optical disk, and 208 is a recording track, which is a concave portion 204 here. 210 is a semiconductor laser and 211 is a semiconductor laser 21.
A collimator lens for collimating the laser light emitted by 0 into parallel light, 212 is a half mirror placed on the light flux, and 213 is parallel light that has passed through the half mirror 212.
This is an objective lens that focuses light on the recording surface on 7. Reference numeral 214 denotes a photodetector that receives the reflected light from the optical disc 207 that has passed through the objective lens 213 and the half mirror 212, and is divided into two in parallel with the track direction of the disc to obtain a tracking error signal. 214b
Consists of. Reference numeral 215 denotes an actuator that supports the objective lens 213, and the above is attached to a head base (not shown) to form an optical head 216. Reference numeral 217 is a differential amplifier to which the detection signals output from the light receiving units 214a and 214b are input, and 218 is a low-pass filter (LPF) to which the difference signal output from the differential amplifier 217 is input. A tracking control circuit 219 receives the output signal of the LPF 218 and a control signal L1 from a system controller 232 described later and outputs a tracking control signal to a drive circuit 220 and a traverse control circuit 226 described later. A drive circuit 220 outputs a drive current to the actuator 215. 221 is the light receiving sections 214a and 2
A summing amplifier 222, which receives the detection signal output from 14b and outputs a sum signal, receives the sum signal from the addition amplifier 221, and a waveform shaping circuit 223 whose high frequency component will be described later.
Is a high-pass filter (HPF) that outputs to
Is a waveform shaping circuit 224 which receives the high frequency component of the sum signal from the HPF 222 and outputs the digital signal to a reproduction signal processing circuit 224 and an address reproduction circuit 225 which will be described later.
Is a reproduction signal processing circuit for outputting an information signal such as voice to the output terminal 233. An address reproducing circuit 225 receives the digital signal from the waveform shaping circuit 223 and outputs the address signal to the system controller 232 described later. 226 is a system controller 232 described later
A traverse control circuit for outputting a drive current to a traverse motor 227 described later by a control signal L2 from
A traverse motor 7 moves the optical head 216 in the radial direction of the optical disk 207. A spindle motor 228 rotates the optical disk 207. An information signal 229, such as a voice, input from the external input terminal 230 is input, and a recording signal is input to a laser drive circuit 231 described later.
The recording signal processing circuit 231 for output to the semiconductor laser 2 receives the control signal L3 from the system controller 232, which will be described later, and the recording signal from the recording signal processing circuit 229.
This is a laser drive circuit for inputting a drive current to 10. 23
2 is a control signal L1 to L for the tracking control circuit 219, the traverse control circuit 226, and the recording signal processing circuit 229.
3 is a system controller to which an address signal is input from the address reproduction circuit 225.

The operation of the conventional optical disk device configured as described above will be described with reference to FIG.

A laser beam emitted from the semiconductor laser 210 is collimated by a collimator lens 211, passes through a beam splitter 212, and is converged on an optical disk 207 by an objective lens 213. Optical disc 2
The light beam reflected by 07 has information on the recording track 208 by diffraction, and is guided to the photodetector 214 by the beam splitter 212 via the objective lens 213. The light receiving units 214a and 214b convert the light amount distribution change of the incident light beam into an electric signal and output the electric signal to the differential amplifier 217 and the addition amplifier 221 respectively. The differential amplifier 217 performs I-V conversion on the respective input currents, then takes the differential, and outputs it as a push-pull signal. L
The PF 218 extracts the low frequency component from this push-pull signal and outputs it as a tracking error signal to the tracking control circuit 219. Tracking control circuit 219
Depending on the level of the input tracking error signal,
A tracking control signal is output to the drive circuit 220, and the drive circuit 220 supplies a drive current to the actuator 215 in response to this signal to control the position of the objective lens 213 in the direction crossing the recording track. As a result, the beam spot correctly scans the concave portion 204. On the other hand, the position of the objective lens 213 is controlled in the direction perpendicular to the disc surface by a focus control circuit (not shown) so that the beam spot is properly focused on the disc.

On the other hand, the summing amplifier 221 has a light receiving portion 214a.
And 214b output currents are IV converted and then added,
The sum signal is output to the HPF 222. The HPF 222 cuts unnecessary low-frequency components from the sum signal, passes the reproduced signal and the address signal, which are main information signals, in an analog waveform, and outputs them to the waveform shaping circuit 223. Wave shaping circuit 2
Reference numeral 23 denotes a main information signal having an analog waveform and an address signal, which are data sliced at a constant threshold value to form a pulse waveform and output to the reproduction signal processing circuit 224 and the address reproduction circuit 225. The reproduced signal processing circuit 224 demodulates the input digital main information signal, and thereafter performs processing such as error correction and outputs it as an audio signal or the like to the output terminal 233. The address reproduction circuit 225 demodulates the input digital address signal and outputs it to the system controller 232 as position information on the disc. That is, as a result of the beam spot 203 scanning the recording pit 202, the reproduction signal is input to the reproduction signal processing circuit 223, and the pre-pit 2
As a result of scanning above 06, an address signal is input to the address reproducing circuit 225. Based on this address signal, the system controller 232 determines whether the light beam is currently at the desired address.

The traverse control circuit 226 controls the control signal L2 from the system controller 232 when the optical head is moved.
In response to this, a drive current is output to the traverse motor 227 to move the optical head 216 to the target track. At this time, the tracking control circuit 219 also suspends the tracking servo by the control signal L1 from the system controller 232. Further, during normal reproduction, the traverse motor 227 is driven according to the low frequency component of the tracking error signal input from the tracking control circuit 219, and the optical head 216 is gradually moved in the radial direction as the reproduction progresses.

The recording signal processing circuit 229 adds an error correction code or the like to the audio signal or the like input from the external input terminal 230 during recording, and outputs the encoded recording signal to the laser drive circuit 231. When the system controller 232 sets the laser drive circuit 231 to the recording mode by the control signal L3, the laser drive circuit 231 modulates the drive current applied to the semiconductor laser 210 according to the recording signal. As a result, the intensity of the beam spot irradiated on the optical disc 207 changes according to the recording signal,
The recording pit 202 is formed. On the other hand, during reproduction, the laser drive circuit 231 is set to the reproduction mode by the control signal L3, and the drive current is controlled so that the semiconductor laser 210 emits light with a constant intensity. This makes it possible to detect the recording pits and pre-pits on the recording track.

During each of the above operations, the spindle motor 228 rotates the optical disk 207 at a constant angular velocity.

Here, conventionally, in order to increase the recording capacity of the optical disk 7, the width of the convex portion 205 is narrowed to close the track interval. However, if the track spacing is narrowed, the diffraction angle of the reflected light by the concave portion 204 becomes large, so that there is a problem that the tracking error signal for accurately causing the beam spot 203 to follow the track is lowered. In addition, since there is a limit in narrowing the track interval only by the width of the convex portion 205, the width of the concave portion 204 must be narrowed. This causes a problem that the amplitude of the reproduction signal is lowered because the recording pit 202 becomes thin.

On the other hand, as disclosed in Japanese Patent Publication No. 63-57859, there is a technique of recording an information signal in both the concave portion 204 and the convex portion 205 to increase the track density.

FIG. 20 is an enlarged perspective view of such an optical disc. In the figure, 201 is a recording layer, 202 is a recording pit, and 203 is a beam spot of laser light. The same components as those described in FIG. 18 are designated by the same reference numerals. Reference numeral 240 is a concave portion formed as a guide groove, and 241 is a convex portion between the guide grooves. As shown in the figure, the widths of the concave portion 240 and the convex portion 241 are substantially equal. Reference numeral 242 is a pre-pit, which is formed on both the concave portion 240 and the convex portion 241, and is engraved at the beginning of each sector of both recording tracks as an identification signal representing position information on the optical disc.

In this optical disc, the recording pit 2
02 is formed in both the concave portion 240 and the convex portion 241 as shown in the figure, and the period of the guide groove is equal to that of the optical disc of FIG. 18, but the interval between the recording pit rows is ½. This doubles the recording capacity of the optical disc.
Hereinafter, both the concave portion 240 and the convex portion 241 in such an optical disc will be referred to as recording tracks in the sense that the recording pit 202 is formed.

The recording / reproducing operation of the optical disk device for this optical disk is basically the same as that of the optical disk device shown in FIG. However, as described in Japanese Patent Publication No. 63-57859, the tracking error signal of the tracking error signal varies depending on whether the beam spot 202 is scanning the convex portion 241 or the concave portion 240. It is necessary to reverse the polarity. This is because the LPF 218 and the tracking control circuit 2 in FIG.
It can be realized by inserting an inverting amplifier capable of ON / OFF control between 19 and 19.

[0017]

However, in the optical disc shown in FIG. 19, in order to obtain position information at an arbitrary position on the recording track of the concave portion and the recording track of the convex portion, an identification signal such as a prepit is recorded on both of them. Since it has to be formed on the track, there is a problem that the manufacturing process becomes more complicated than that of the optical disk shown in FIG.

The present invention solves the above-mentioned problems. It is possible to obtain position information on both recording tracks of concave portions and recording tracks of convex portions without forming identification signals such as address information on both recording tracks. It is an object of the present invention to provide an optical disc capable of performing the above and an optical disc device using the optical disc.

[0019]

In order to achieve the above object, the optical disc of the present invention has a concave portion formed in a spiral or concentric circle on the disc and a convex portion between the concave portions as recording tracks, and Is an optical disc that pre-forms an identification signal indicating the position, etc., and records an information signal by utilizing a change in a local optical constant or a physical shape due to irradiation of a light beam, and a part or all of the identification signal, It is characterized in that it is displaced by a predetermined displacement amount in the radial direction from the center line of the recording track of the concave portion or the convex portion, and more preferably, the displacement amount is a quarter of the pitch of the recording track of the concave portion or the convex portion. It is characterized by being 1.

In order to achieve the above-mentioned object, the optical disk device of the present invention comprises the above-mentioned optical disk, a rotating means for holding and rotating the optical disk, an optical beam emitted onto the optical disk, and a reflected light thereof received to generate an electric signal. An optical head that converts into a signal and outputs it as a reproduction signal, and a tracking that outputs the amount of deviation between the light beam irradiated on the optical disk and the center of the concave recording track or convex recording track on the optical disk as a tracking error signal. The error detection means, the tracking control means for displacing the light beam in the disk radial direction according to the tracking error signal to eliminate the deviation amount, and the light beam scanning either the concave recording track or the convex recording track. Determine if there is
The discriminating means for outputting the result as a discriminating signal and the area where the light beam forms the discriminating signal of the optical disc are scanned,
It has an identification signal reading means for generating an identification signal from the reproduction signal output from the optical head, and a position detection means for calculating the position where the light beam is scanning from the identification signal and the discrimination signal, and the optical beam is applied to the optical disk. It has a structure for recording, reproducing or erasing an information signal.

[0021]

With the above structure, when the light beam scans either the concave recording track or the convex recording track, part of the light beam overlaps the identification signal. Therefore,
The reflected light is modulated by the identification signal, and the optical head receives the light and converts it into a modulated electric signal. Based on the identification signal read by the identification signal reading means from the reproduction signal output from the optical head and the result of the discrimination means discriminating between the concave recording track and the convex recording track, the position calculating means determines whether the light beam is scanning. Calculate the position.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk device according to an embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, it is assumed that a phase change type (PC) recording material that records by changing the actual reflectance is used as the recordable and reproducible optical disc, and the peripheral speed is used as a control method of the optical disc rotation. Constant (CAV: Constant Angle)
r Velocity (Constant Angular
(Abbreviation of velocity) will be described.

FIG. 1 is an enlarged perspective view of a recording surface of an optical disc according to the first embodiment of the present invention. In the figure, 1
Is a disk substrate, and 2 is a recording layer. 3, 4, 5 and 6
Is a recess formed in a spiral shape and also serves as a guide groove for tracking control. Reference numerals 7, 8 and 9 are convex portions between the concave portions. The concave portions and the convex portions are arranged at the pitch Tp. In this figure, the concave / convex part with the smaller number is the inner peripheral side. Numeral 10 is pre-pits formed in a row in a concave-convex shape in the region where the guide groove is interrupted, and the center lines of the rows are shifted from the center line of the guide groove to the outer peripheral side by a quarter of TP. There is. That is, one prepit area corresponds to a pair of adjacent concave and convex portions. An identification signal is recorded by the arrangement pattern of the pre-pits 10. In the figure, the number of prepits for the identification signal is drawn at most 3 per track, but in reality, it is several tens to 100 depending on the information amount of the identification signal. A beam spot 11 is focused on the recording layer by an objective lens or the like, and is scanned along the center line of the concave portion or the convex portion (hereinafter referred to as the track center) as shown in the figure.

When recording / reproducing the information signal, the beam spot 11 moves along the center of the track on the concave portion or the convex portion. Even if it reaches the interruption area of the guide groove, if the time for passing through the interruption area is sufficiently short, scanning is performed along the track center. The positional relationship between the beam spot 11 and the pre-pit 10 at this time is shown in FIG. FIG. 2 is an enlarged view of the recording surface of the optical disc of this embodiment as seen from directly above. When the beam spot 10 moves along the track center line of the recess, the right half overlaps with the pre-pit 10 in the traveling direction of the spot in the interruption region. Further, when moving along the track center line of the convex portion, the left half of the spot hits the pre-pit 10. In any case, since the reflected light of the beam spot is modulated by the pre-pits, the address information and the like can be obtained by detecting it with a photo detector or the like. The modulation degree of the reflected light can be maximized by setting the depth converted to the optical length of the pre-pit 10 to ¼ of the wavelength of the radiation beam that generates the beam spot.

Next, the track format of the optical disc of this embodiment will be described. FIG. 3 is a configuration diagram of a recording track.

In FIG. 3, reference numeral 70 is a concave portion and 71 is a convex portion. A recording track number is assigned to each track through a convex portion and a concave portion for each circumference. The beam spot traces clockwise from the inner circumference side to the outer circumference side, and the recording track numbers are T, T + 1, T + 2, T + 3, T in the figure.
It is indicated by +4. 72 is a sector in which each track is divided into N, and sector numbers from 1 to N are assigned to the sectors. Since the recording track is spiral, the Nth sector of the Tth track and the 1st sector of the T + 2th track are connected in the recess. At the convex part, T + 1
The Nth sector of the #th track and the 1st sector of the T + 3rd track are connected. These recording track number and sector number are previously formed on the disc as the above-mentioned prepits. In this embodiment, the address data of the recording track of the recess is recorded as a prepit. When the recording track of the convex portion is being traced, the current position information can be obtained by adding 1 to the track number of the address data in which the prepit is reproduced. Further, since the sector numbers are the same in the sectors adjacent to each other in the radial direction, the signal obtained by reproducing the prepits on the recording tracks of the concave and convex portions can be directly used as the position information.

FIG. 4 is a diagram for explaining the format of the identification signal per sector. As shown in the figure, one sector consists of an identification signal area and a main information signal area. The identification signal area includes a sector mark, a synchronization pattern, an address mark,
It consists of blocks of track numbers and sector numbers. The function of each block is as follows. (1) Sector mark: Indicates the beginning of each sector. (2) Synchronization pattern: A clock for reproducing address data is generated. (3) Address mark: Indicates that address data starts. (4) Track number, sector number: indicates address data. Of these, the sector mark, the synchronization pattern, and the address mark are the same in all sectors.

The method of manufacturing the optical disk of this embodiment is similar to the method described in, for example, Japanese Patent Laid-Open No. 50-68413. An apparatus for manufacturing the optical disc of this embodiment will be briefly described with reference to the drawings. FIG. 5 is a block diagram showing its configuration. 30 is a radiation beam source such as a laser light source,
Emit a radiation beam 31 of sufficient energy. The radiation beam 31 passes through a light intensity modulator 32, a light deflector 33, and a mirror prism 34, and is converged into a minute radiation beam spot by an objective lens 35. A record carrier 36, such as an optical disk substrate, is coated with, for example, a photoresist layer as the radiation beam sensing layer 37. The light intensity modulator 32 blocks the radiation beam 31 according to the identification signal input from the identification signal generator 38 via the amplifier 39. Therefore, the identification signal output from the identification signal generator 38 is converted into a radiation beam pulse and converted into a photosensitive mark train on the radiation beam sensing layer 37. The identification signal generator 38 generates an identification signal when the gate pulse from the gate signal generator 40 is input. The light intensity modulator 32 can be composed of, for example, a photoelectric crystal that rotates the deflection direction of the radiation beam when a voltage is applied, and an analyzer that converts a change in the orientation of the deflection surface into a light intensity change.

In the optical deflector 33, the minute beam spot has a constant width in the radial direction on the record carrier only while the gate pulse is input from the gate signal generator 40 connected through the amplifier 41. The angle of the radiation beam 31 is changed by a very small angle, so that it is displaced only by. The gate signal generator 40 synchronizes with the rotation phase signal output from the motor 42 that rotates the record carrier 36, and supplies a gate pulse equal to the length of the identification signal to the identification signal generator 38 and the amplifier 41 at a predetermined cycle. Output. This allows the radiation beam sensing layer 37 to be present while the gate pulse is not being generated.
A continuous track is written on the upper side, and when a gate pulse is generated, an identification signal is written as a mark string at a position displaced from the previous continuous track by a certain amount in the radial direction.
In this way, a continuous track and a pre-pit string of identification signals can be written on the radiation beam sensing layer 37 in a series of operations. That is, the identification signal is represented by the continuous tracks. After writing, the disk substrate is completed through steps such as etching, transfer and molding.

The light deflector 33 can be constituted by a so-called acousto-optical deflector. FIG. 6 shows an acousto-optic device used as the deflector 33. In this acousto-optic device, an acousto-optic cell 50 is provided with two electromechanical transducers 51 and 52 connected to terminals 55 and 56. When an electric signal is supplied to the terminals 55 and 56, the cell 5
An acoustic wave of a certain frequency is generated in the medium of 0, for example, in the glass. This causes Bragg refraction in the medium, so that the radiation beam 53 is partly deflected as an auxiliary beam 54 at an angle α. The angle α is proportional to the frequency of the electric signal supplied.

As described above, according to the optical disk of the present embodiment, the center lines of the prepit rows are shifted from the center lines of the guide grooves to the outer peripheral side by a quarter of the pitch of the guide grooves, and thus The beam spot is sufficiently modulated by the prepits on both the recording track and the convex recording track, and the identification signal can be detected. Further, since it is not necessary to form prepits on both the concave recording track and the convex recording track, an optical disk can be manufactured with a small number of steps.

In the optical disc of this embodiment, the case where all the identification signal areas are shifted in the radial direction has been described, but it is also possible to shift only different portions between adjacent recording tracks. FIG. 7 shows an example of the sector format of such a disc. That is, of the respective parts of the identification signal shown in FIG. 4, only the track number part is shifted, and the other blocks have prepits formed on the recording tracks of the recesses. Since these blocks have the same pattern in adjacent tracks, even when the beam spot traces the convex portion, it is modulated by the prepits of the concave portions on both sides. As a result, it is possible to reproduce the identification signals of these blocks even in the convex portion. With such a configuration, the section in which the pre-pit is displaced from the track center becomes short, which has the advantage of stabilizing the tracking control of the beam spot.

Further, in the present embodiment, the identification signal is arranged in the section in which the recess formed by the guide groove is interrupted.
Alternatively, the identification signal may be provided by overlapping the prepits in the continuous guide groove as shown in FIG. In this case, since the guide groove is not interrupted, tracking control becomes stable.

Next, an embodiment of an optical disk device for recording, reproducing or erasing an information signal on the optical disk of the present invention will be described with reference to the drawings.

FIG. 9 is a block diagram showing the configuration of an optical disk device according to the second embodiment of the present invention. In the figure, 210 is a semiconductor laser, 211 is a collimating lens, 212 is a half mirror, 213 is an objective lens, 21
4 is a photodetector, 214a and 214b are light receiving parts thereof, and 21
5 is an actuator, 216 is an optical head, 217 is a differential amplifier, 218 is a low-pass filter (LPF), 219.
Is a tracking control circuit, 220 is a drive circuit, 221 is a summing amplifier, 222 is a high-pass filter (HPF), 2
24 is a reproduction signal processing circuit, 225 is an address reproduction circuit,
226 is a traverse control circuit, 227 is a traverse motor, 228 is a spindle motor, 229 is a recording signal processing circuit, 230 is an external input terminal, 231 is a laser drive circuit, and 233 is an output terminal. Since it is basically the same as the constituent element of the optical disc device, the same reference numerals as those of the conventional example are given and detailed description thereof is omitted.

The structure of a portion different from that of FIG. 19 will be described. Reference numeral 60 is the optical disk of the present invention described in FIG.
Is a recording track, and 62 is a polarity reversing circuit that inputs a tracking error signal output from the LPF 218 and a control signal L4 from a system controller 68 described later, and outputs the tracking error signal to the tracking control circuit 219. Here, regarding the polarity of the tracking control, when the tracking error signal is input to the tracking control circuit 219 with the same polarity from the differential amplifier 217, the tracking pull-in is performed on the recording track of the recess. Reference numeral 63 is a first waveform shaping circuit which receives the high frequency component of the sum signal from the HPF 222 and outputs a digital signal to the reproduction signal processing circuit 224. 64 is a high frequency component of the sum signal input from the HPF 222 and the digital signal is an address reproduction circuit. 2 is a second waveform shaping circuit for outputting to 225.
65 is an address signal from the address reproduction circuit 225,
The address calculation circuit receives the control signal L4 from the system controller 68 and outputs an accurate address signal to the system controller 68. Reference numeral 66 denotes a jump pulse generating circuit which receives the control signal L6 from the system controller 68 and outputs the jump pulse signal to one input terminal of a selector 67 which will be described later. 67 denotes tracking control of the jump pulse signal from the jump pulse generating circuit 66. A tracking control signal is input from the circuit 219 and a switching signal L7 is input from the system controller 68,
It is a selector that outputs one of them to the drive circuit 220. An address signal 68 is input from the address calculation circuit 65, and a tracking control circuit 219, a traverse control circuit 226, a laser drive circuit 231, a recording signal processing circuit 229, a polarity reversing circuit 62, an address calculation circuit 65, a jump pulse generation circuit 66, and Control signals L1, L2, L3, L4, L6 and L7 are supplied to the first selector 67, respectively.
Is a system controller that outputs.

The operation of the optical disk device of the present embodiment having the above-mentioned structure will be described with reference to the drawings. Since the process of irradiating and reflecting the laser beam on the optical disk 60 is performed in the same manner as in the conventional example, detailed description thereof will be omitted. Whether or not an operation (hereinafter referred to as a search operation) is performed will be described.

When the address for starting the recording / reproducing is designated, the system controller 68 determines whether the sector of the designated address is a convex sector or a concave sector.
The determination is performed by referring to the address map and the like, and the determination signal is output as L4. Here, it is assumed that L4 is at the Lo level when it is a concave portion and L4 is at a Hi level when it is a convex portion. When the start address is within the convex portion, the polarity inversion circuit 6
Reference numeral 2 reverses the polarity of the input signal and outputs the same without changing the polarity when the address is in the concave portion. Further, the selector 67 is caused to select the tracking control circuit 219 as an input destination of the drive circuit 220 through the control signal L7. Next, the traverse control circuit 226 drives the traverse motor 227 by the control signal L2 to move the optical head 216 to the vicinity of the track having the target address. This is called a rough search. This movement is performed, for example, by pre-calculating the number of tracks between the two from the difference between the address value before the movement and the target address value and comparing with the number of traversing tracks obtained from the tracking error signal during the movement. Be seen. Next, the tracking control circuit 219 is controlled by the control signal L1.
Is turned on to trace the beam spot on the convex portion or the concave portion. When the tracking pull-in is completed, as in the case of the description of the conventional example of FIG.
The summing amplifier 221 outputs the output currents of 4a and 214b to I-
V conversion and addition amplification are performed, unnecessary frequency band components are removed by the HPF 222, and then input to the first waveform shaping circuit 63 and the second waveform shaping circuit 64. When the beam spot is tracing over the interruption area, the HPF 222
The reproduction signal output from is a signal modulated with pre-pits. The second waveform shaping circuit 64 amplifies the reproduction signal sent from the HPF 222 to a predetermined amplitude, and then 2
The value is converted, the waveform is shaped into a digital signal, and the digital signal is output to the address reproducing circuit 225. The address reproduction circuit 225 decodes this into address data and outputs it to the address calculation circuit 65. When the determination signal L4 from the system controller 68 is Lo, the address calculation circuit 65 outputs the input address data as it is to the system controller 68 as the current address. On the other hand, when the determination signal L4 is Hi, 1 is added to the track number of the address data and the result is output to the system controller 68. The system controller 68 regards these as current address values and performs subsequent control.

The system controller 68 compares the current address value with the target address value. If the difference is more than one track, the selector 67 is again supplied with the control signal L7.
The output of the jump pulse generation circuit 66 and the drive circuit 220
Connect the input of. Then, the system controller 6
Reference numeral 8 designates the jump pulse generation circuit 66 through the control signal L6 to specify the number of tracks to be jumped. The jump pulse generation circuit 66 outputs a driving pulse to the drive circuit 220 so that the specified number of tracks are jumped.
The actuator 215 is moved by a small amount. This is called a fine search. When the fine search is completed and the beam spot moves to the target track, tracking pull-in is performed, the current address value is detected again, and after the beam spot reaches the target sector due to the rotation of the disk, the information signal is output after this sector. Is recorded or played back. During reproduction, the first waveform shaping circuit 63 amplifies the reproduction signal output from the HPF 222 to a predetermined amplitude, binarizes it, and shapes the waveform into a digital signal, which is output to the reproduction signal processing circuit 224. Here, since the reproduction amplitudes of the main information signal by the recording mark and the identification signal by the pre-pit are different, the amplification factors of the first waveform shaping circuit 63 and the second waveform shaping circuit 64 are made different. The reproduction signal processing circuit 224 decodes this, performs error correction, and outputs it to the output terminal 233.
Further, at the time of recording, it is the same as the conventional optical disk device of FIG.

As described above, according to the optical disc apparatus of the present embodiment, the system controller 68 determines whether the track currently scanned by the light beam is a concave portion or a convex portion, and the determination result and the address reproducing circuit 225 are Since the address calculation circuit 65 calculates the address of the place where the light beam is currently scanning, based on the demodulated address data, the address can be read correctly.

Although the present embodiment corresponds to the optical disc in which the pre-pits are displaced from the center line of the guide groove to the outer peripheral side by a quarter of the pitch of the guide groove, it is also applicable to the optical disc whose inner peripheral side is displaced. You can do the same. In this case, when the determination signal L4 is at the Hi level, the addition value of the track address in the address calculation circuit 65 is not +1 but −.
All you have to do is change it to 1.

By the way, in the optical disc apparatus of the first embodiment, when the beam spot traces the identification signal portion, the prepits are displaced in the radial direction, so that the intensity distribution of the reflected light is biased. Tracking control becomes slightly unstable. In order to prevent this, a more preferred embodiment of the optical disk device of the present invention will be described with reference to the drawings.

FIG. 10 is a block diagram showing the configuration of an optical disk device in such a third embodiment of the present invention. In the figure, 62 is a polarity inversion circuit, 63 is a first waveform shaping circuit, 64 is a second waveform shaping circuit, 65 is an address calculation circuit, 66 is a jump pulse generation circuit, 67 is a selector, 68 is a system controller, 210 is a semiconductor laser, 211 is a collimating lens, 212 is a half mirror, 213 is an objective lens, 214 is a photodetector, and 21
Reference numerals 4a and 214b denote light receiving portions thereof, 215 actuators, 216 optical heads, 217 differential amplifiers, 218 low-pass filters (LPFs), 219 tracking control circuits, 220 drive circuits, 221 addition amplifiers, 22
2 is a high pass filter (HPF), 224 is a reproduction signal processing circuit, 225 is an address reproduction circuit, 226 is a traverse control circuit, 227 is a traverse motor, 228 is a spindle motor, 229 is a recording signal processing circuit, 230 is an external input terminal, Reference numeral 231 denotes a laser drive circuit, and 233 an output terminal. Since the above are basically the same as the constituent elements of the optical disc device of the second embodiment shown in FIG. The description is omitted.

The structure of the part different from that of FIG. 9 will be described. Reference numeral 80 is the optical disk of this embodiment, and 81 is its recording track. Reference numeral 82 denotes a third waveform shaping circuit that receives the output of the HPF 222 and the control signal L4 from the system controller 68 and outputs the control signal L4 to a synchronization signal detection circuit 83 described later.
83 receives the output signal of the third waveform shaping circuit 82,
A synchronization signal detection circuit that outputs an address synchronization signal to a gate signal generation circuit 84 described later, and 84 is a synchronization signal detection circuit 8
3, a gate signal generation circuit that receives an address synchronization signal from 3 and outputs a first gate signal L8 and a second gate signal L9 to a hold circuit 85 and a gain variable amplifier 86, which will be described later, and 85 is an output of the polarity inverting circuit 62. And a first gate signal L8 from the gate signal generating circuit 84, and a tracking circuit that outputs a tracking error signal to the tracking control circuit 219. 86 is an output of the holding circuit 85 and a second gate signal from the gate signal generating circuit 84. L
9 is a variable gain amplifier to which 9 is input.

FIG. 11 is an enlarged perspective view of the optical disc 80 in this embodiment. In the same figure, 90 is a main information signal area consisting of concave and convex recording tracks formed by guide grooves, and 91 is an identification signal area, in which the prepits are shifted in the disk radial direction as described with reference to FIG. It is arranged. Reference numeral 92 is a synchronization signal area formed between the main information signal area 90 and the identification signal area 91 on the extension line of the recess, and pre-pits are formed by the interruption of the guide groove. The pattern of this synchronization signal is the same in all sectors.

The operation of the optical disk device of the present embodiment having the above-described structure will be described with reference to the drawings, mainly regarding the parts different from those of the optical disk device of the first embodiment. First, consider the case where a beam spot traces a concave portion in a recorded or reproduced state. Similar to the optical disk device of the second embodiment of FIG. 9, the polarity inverting circuit 62 outputs the tracking error signal that has passed through the photodetector 214 and the LPF 218 to the hold circuit 85 as it is according to the control signal L4. In the hold circuit 85, the beam spot is the main information signal area 9
When it is 0, the tracking error signal is directly output to the tracking control circuit. Tracking control circuit 2
Reference numeral 19 denotes the actuator 2 through the drive circuit 220 so as to eliminate the off-track according to the tracking error signal.
Move 15. Here, the selector 67 controls the tracking control circuit 219 and the drive circuit 220 according to the control signal L7.
Are connected.

When the beam spot enters the sync signal area 92 from the main information signal area 90, the sync signals recorded in the sync signal area 92 as an array of prepits are detected by the photodetector 21.
4, input to the third waveform shaping circuit 82 through the addition amplifier 221 and the HPF 222. Third waveform shaping circuit 8
2 is the first threshold value Th1 of the reproduced sync signal.
The digitized signal is output to the sync signal detection circuit 83 as a digital signal. The sync signal detection circuit 83 has a sync signal pattern stored therein, and constantly compares the pattern of the digital signal input from the third waveform shaping circuit with the pattern of the sync signal. The one gate signal L8 and the second gate signal L9 are generated.

FIG. 12 is a timing chart showing the first gate signal L8 and the second gate signal L9 when the beam spot is passing through each area. The first gate signal L8 is normally at Lo level, becomes Hi level when the synchronization signal is detected, and returns to Lo level when the time T1 required for the beam spot to pass through the identification signal region 91 elapses. The second gate signal L9 is normally at the Lo level, and is at the Hi level for a predetermined time T2 from the moment when the first gate signal falls from Hi to Lo.

On the other hand, the photodetector 214 and the differential amplifier 21
7, the tracking error signal is input to the hold circuit 85 through the LPF 218 and the polarity reversing circuit 62. The hold circuit 85 outputs the input signal as it is when the first gate signal L8 is at the Lo level. Also,
When rising from Lo level to Hi level, the value of the input signal immediately before rising is held, and this hold value is continuously output until L8 returns to Lo level. The variable gain amplifier 86 amplifies the input signal with the gain A1 when the gate signal L9 is at the Lo level, and amplifies it with the gain A2 when it is at the Hi level. Gain is A1 <
It is set to A2.

The reason why the tracking control becomes stable by the above operation will be described below.

FIG. 13 is an explanatory diagram showing the tracking error signal output by the polarity reversing circuit 62 when the beam spot traces on the identification signal area. When the beam spot 11 reaches the identification signal area, only the right half of the pre-pit 10 in the traveling direction of the beam spot.
Therefore, a large asymmetry occurs in the reflected light of the beam. Therefore, the tracking error signal has a large value as in the case of a large off-track, as indicated by point A in the figure, and an excessive driving current is suddenly supplied to the actuator 215, and the tracking control is shaken and becomes unstable. there is a possibility.

In the present embodiment, the hold circuit 85 detects the synchronizing signal arranged immediately before the identification signal area and immediately before the beam spot starts tracing the identification signal area, the hold circuit 85 responds to the first gate signal L8. Holds the tracking error signal. Therefore, the tracking error signal does not suddenly increase in this region and the tracking control does not become unstable. When the beam spot passes through the identification signal area after the time of T1 and reaches the main information signal recording area, the hold is released and the tracking control is restarted according to the tracking error signal output from the polarity reversing circuit 62.

Further, when the hold is released, the beam spot may be off-track due to eccentricity of the disk, disturbance, or the like. The variable gain amplifier 86 amplifies the tracking error signal with the gain A2, thereby increasing the gain of the tracking control loop during the time T2. As the gain increases, the tracking error apparently increases, and the tracking control circuit 2
19 is an actuator 215 through a drive circuit 220.
In addition, a large driving force is generated in the direction in which the tracking error is eliminated. Therefore, the tracking pull-in becomes steep, and the off-track after the hold is released is quickly eliminated. Time T2 is the linear velocity of the disk, time T1
, The driving force of the actuator 215, etc.
Optimal setting.

Next, the case where the beam spot traces the convex portion will be described. The polarity inverting circuit 62 inverts the input tracking error signal in response to the control signal L4 from the system controller. As a result, the beam spot traces the recording track of the convex portion. Similarly, in response to the control signal L4, the third waveform shaping circuit 83 causes the second threshold value Th2 different from Th1 to
It is set as a comparison level for binarization. The reason why the threshold value is varied between the concave recording track and the convex recording track will be described with reference to FIG.

FIG. 14 is an enlarged view showing the positional relationship between the pre-pits in the sync signal area and the beam spot when the recording track in which the beam spot is convex is traced.
As described above, since the patterns of the synchronization signals are all the same, the pits on both sides of the beam spot have the same array pattern. The beam spot is partially applied to the pre-pits on the recording tracks of the recesses on both sides to be modulated.
Therefore, the synchronization signal can be reproduced even on the recording track of the convex portion where the pre-pit is not formed as the synchronization signal. However, since the area where the beam spot overlaps the pre-pits differs between the concave recording track and the convex recording track, the degree of modulation of the reproduced synchronization signal also differs. In the third waveform shaping circuit 83, the threshold value Th1
And Th2 are suitably set for each modulation degree, and are configured to favorably binarize the synchronization signal.

In order to further improve the detection of the sync signal on the recording track of the convex portion, the width Wp of the prepit for the sync signal may be made wider than the width Wg of the guide groove as shown in FIG. As a result, the area in which the beam spot overlaps the pre-pits while tracing the recording track of the convex portion is increased, and the modulation degree of the reproduction signal is improved. Such pre-pits can be easily formed by increasing the intensity of the radiation beam and enlarging the photosensitive portion on the radiation beam sensing layer in the optical disc manufacturing apparatus as shown in FIG.

Further, the system controller 68, through the recording signal processing circuit 229, does not record the main information in the main information signal area during T2 after the hold is released. FIG. 16 is an explanatory diagram of the structure of a recording track provided with such a gap portion. By providing a gap portion having a length corresponding to the time T2 immediately after the identification signal area, the main information signal is not recorded until the track offset is eliminated. As a result, the main information signal is prevented from being recorded off-track, and the quality of the recording signal can be improved.

As described above, according to the optical disc apparatus of this embodiment, the hold circuit 85 detects the sync signal arranged immediately before the identification signal area, and the hold circuit 85 performs tracking immediately before the beam spot starts tracing the identification signal area. By holding the error signal, it is possible to prevent a sudden change in the drive current to the actuator 215 and stabilize the tracking control.

Further, immediately after the hold is released, the variable gain amplifier 86 increases the gain of the tracking control loop for the time T2, so that the tracking pull-in becomes steep, and the off-track generated at the time of hold is promptly performed. Will be resolved.

Further, by providing a gap portion having a length corresponding to the time T2 immediately after the identification signal area, it is possible to avoid the off-track recording of the main information signal and improve the quality of the recording signal. Becomes

In the optical disk device of this embodiment, the sum signal of the reproduction signals output from the photodetectors 214a and 214b of the photodetector 214 is used for detecting the identification signal, but the difference signal between them may be used. . FIG. 17 shows a block diagram of a block for detecting an identification signal in this case. In the figure, 217 is a differential amplifier, 218 is an LPF, 62 is a polarity inversion circuit, 219 is a tracking control circuit, 225.
Is an address reproducing circuit, and the above is the same as the configuration of FIG. Reference numeral 100 denotes a high-pass filter (HPF) that extracts an identification signal component from the push-pull signal output from the differential amplifier 217, and 101 denotes the HPF 100 according to a control signal (corresponding to L4 in FIG. 9) from a system controller (not shown). Polarity reversing circuit that inverts the output signal,
Reference numeral 102 denotes a fourth waveform shaping circuit which digitizes the analog reproduction signal output from the polarity inverting circuit 101 and outputs it to the address reproduction circuit 225. As described above, when there is a beam spot on the pre-pits in the identification signal area, the pre-pits are displaced by Tp / 4 in the radial direction, so that the reflected light amount distribution becomes asymmetric in the disc radial direction. The asymmetry is small when the beam spot is between the prepits. Therefore, similarly to the tracking error signal, the difference between the outputs of the photodetectors 214a and 214b arranged in the radial direction, that is, the push-pull signal can be obtained to detect the identification signal by the prepit. However,
Since the positional relationship between the pre-pits and the beam spots is reversed between the concave recording track and the convex recording track,
The polarity of the push-pull signal is also inverted. Therefore, in FIG. 17, the polarity inversion circuit 101 inverts the polarity of the push-pull signal according to the control signal L4. If the modulation method of the identification signal is a method that is not influenced by the polarity, the polarity inversion circuit 101 is not necessary. With the above configuration, since the push-pull signal does not have a DC component, it has an excellent feature that the detection performance of the identification signal is not influenced by the fluctuation of the reflectance.

Further, in the optical disk device of the third embodiment shown in FIG. 10, the end of the identification signal area was detected by measuring the elapsed time T1, but the end of the identification signal corresponds to the end identifier. The signal may be formed as a pre-pit, and the end of the identification signal area may be detected by detecting this during recording / reproduction. That is,
In the sector format diagram of FIG. 4, a block of the end identifier is provided after the block of the track address. The center line of the pre-pit row of the end identifier is made to coincide with that of the identification signal so that it can be detected similarly to the identification signal. As a result, the timing of canceling the tracking error signal becomes more accurate, and it is possible to prevent the tracking control from becoming unstable due to deviation of the cancel timing.

[0063]

As described above in detail, in the optical disc of the present invention, the identification signal train is formed by being shifted from the center line of the guide groove to the outer peripheral side by a quarter of the pitch of the guide groove. Whether it's a concave or convex recording track,
The beam spot overlaps the identification signal train and is sufficiently modulated. Therefore, the identification signal can be detected from the reflected light beam.

Further, in the optical disk device of the present invention, the discriminating means discriminates whether the track currently scanned by the light beam is a concave portion or a convex portion, and the discrimination result and the discrimination signal demodulated by the discrimination signal reading means are also recorded. In addition, the position information can be correctly read on both the recording track of the concave portion and the recording track of the convex portion by the position detecting means calculating the position information of the place where the light beam is currently scanned.

Furthermore, since it is not necessary to form prepits on both the concave recording track and the convex recording track, an optical disk can be manufactured with a small number of steps.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view showing a configuration of an optical disc according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view showing the configuration of the optical disc in the first embodiment.

FIG. 3 is a diagram showing a configuration of recording tracks of the optical disc in the first embodiment.

FIG. 4 is a schematic diagram showing a sector format of an optical disc according to the first embodiment.

FIG. 5 is a block diagram showing a configuration of a main part of a manufacturing apparatus for manufacturing an optical disc according to the first embodiment.

FIG. 6 is a configuration diagram of an acousto-optic element used in a manufacturing apparatus for manufacturing an optical disc according to the first embodiment.

FIG. 7 is a schematic diagram showing a configuration of recording tracks of an optical disc according to another embodiment of the present invention.

FIG. 8 is an enlarged perspective view of an optical disc according to another embodiment of the present invention, in which the guide groove is not interrupted.

FIG. 9 is a block diagram showing the configuration of an optical disc device according to a second embodiment of the present invention.

FIG. 10 is a block diagram showing the configuration of an optical disk device according to a third embodiment of the present invention.

FIG. 11 is an enlarged perspective view showing the configuration of an optical disc used in the optical disc device of the third embodiment.

FIG. 12 is a timing chart of control signals in the optical disk device of the third embodiment.

FIG. 13 is an explanatory diagram showing a tracking error signal when a beam spot traces on an identification signal area in the optical disk device of the third embodiment.

FIG. 14 is an enlarged plan view showing the positional relationship between the pre-pits and the beam spot in the sync signal area in the recording track of the convex portion in the optical disc device of the third embodiment.

FIG. 15 is an enlarged plan view of another example of the optical disc used in the optical disc apparatus of the third embodiment.

FIG. 16 is a timing chart for explaining the structure of a recording track provided with a gap portion in the optical disk device of the third embodiment.

FIG. 17 is a block diagram showing the configuration of main blocks for detecting an identification signal in the optical disc device of the other embodiment.

FIG. 18 is an enlarged perspective view for explaining the configuration of an optical disc used for a conventional optical disc.

FIG. 19 is a block diagram showing a configuration of a conventional optical disc device.

FIG. 20 is an enlarged perspective view for explaining the configuration of a conventional optical disc in which signals are recorded in both concave and convex portions of a recording track.

[Explanation of symbols]

 10 pre-pit 11 beam spot 60,80 optical disk 61,81 recording track 62,101 polarity reversing circuit 63 first waveform shaping circuit 64 second waveform shaping circuit 65 address calculation circuit 66 jump pulse generation circuit 67 selector 68 system controller 82 second 3 waveform shaping circuit 83 synchronization signal detection circuit 84 gate signal generation circuit 85 hold circuit 86 gain variable amplifier 90 main information signal region 91 identification signal region 92 synchronization signal region 100, 222 high-pass filter (HPF) 102 fourth waveform shaping circuit 210 semiconductor laser 211 collimator lens 212 half mirror 213 objective lens 214 photodetector 214a, 214b light receiving part 215 actuator 216 optical head 217 differential amplifier 218 low-pass filter (L PF) 219 Tracking control circuit 220 Drive circuit 221 Addition amplifier 225 Address reproduction circuit 226 Traverse control circuit 227 Traverse motor 228 Spindle motor

Claims (11)

[Claims] 1. A light beam is irradiated with an identification signal representing a position on the disk, which is formed in advance by using both of the spiral or concentric recesses formed on the disk and the projections between the recesses as recording tracks. An optical disc for recording an information signal by utilizing a change in a local optical constant or a physical shape due to the optical disc, wherein a part or all of the identification signal is radially extended from a center line of a recording track of the concave portion or the convex portion. An optical disk characterized by being displaced by a predetermined displacement amount. 2. The optical disc according to claim 1, wherein the predetermined displacement amount is approximately one fourth of the pitch of the recording track of the concave portion or the convex portion. 3. The optical disc according to claim 1, wherein the identification signal is composed of uneven prepits having an optical depth or height of approximately λ / 4 (λ is the wavelength of the light beam). . 4. A first synchronization signal representing the start of the area in which the identification signal is formed is previously formed at a position immediately before the identification signal, and the center line of the row of the first synchronization signal is a recess or a protrusion. 4. The optical disc according to claim 1, wherein the optical disc is aligned with the center line of the recording track of the copy. 5. A second synchronization signal representing the end of the area in which the identification signal is formed is formed in advance at a position immediately after the identification signal, and the center line of the column of the second synchronization signal is the identification signal. 5. The center line of the column is aligned with the center line of the column.
The described optical disc. 6. The optical disk according to claim 1, 2, 3, 4 or 5, a rotating means for holding and rotating the optical disk, irradiating a light beam on the optical disk and receiving the reflected light to generate an electric signal. An optical head for converting into a signal and outputting as a reproduction signal, and a deviation amount between a light beam irradiated on the optical disc and a center line of a recording track of a concave portion or a recording track of a convex portion on the optical disc as a tracking error signal. Tracking error detecting means for outputting; tracking control means for displacing the light beam in the disk radial direction according to the tracking error signal to eliminate the deviation amount; and the light beam for the recording track of the concave portion and the convex portion. Discriminating means for discriminating which recording track is being scanned and outputting the result as a discriminating signal; While the light beam is scanning over the identification signal of the optical disc, the light beam is emitted from the identification signal reading means for generating the identification signal from the reproduction signal output from the optical head, and the identification signal and the discrimination signal. An optical disc device having a position detecting means for calculating a scanning position and recording, reproducing or erasing an information signal on the optical disc by the light beam. 7. The gain control means for increasing the gain of the tracking control loop for a predetermined period immediately after the light beam has finished passing through the area where the identification signal is formed. Optical disk device. 8. A recording means for recording an information signal on an optical disk, and an operation of the recording means for preventing the information signal from being recorded in a certain section on a recording track of a concave portion or a convex portion immediately after the identification signal. 7. The optical disk device according to claim 6, further comprising recording control means for controlling. 9. An optical head has two photodetectors, which are symmetrically arranged on a light-receiving surface of a reflected light beam in a direction corresponding to a disk radial direction, and convert the received light amount into an electric signal. 7. The optical disk device according to claim 6, wherein the signal reading means includes a calculating means for calculating a difference between the electric signals output by the two photodetectors and outputting the difference as a reproduction signal. 10. An identification signal region detecting means for detecting that a light beam is scanning a region in which an identification signal is formed and outputting a detection signal, and a tracking error while the detection signal is being output. 10. The optical disk device according to claim 6, further comprising a tracking error signal holding unit that holds a signal at a value immediately before the detection signal is output. 11. The optical disk is the optical disk according to claim 4 or 5, wherein the identification signal area detecting means detects the first synchronizing signal formed on the optical disk and the reproduction signal output from the optical head. 11. The optical disk device according to claim 10, further comprising a sync signal detecting unit that generates a detection signal when the first sync signal is detected.