JPH0845079A - Method and device for processing optical information - Google Patents

Abstract

PURPOSE:To prevent the destruction of data and to assure the data by stopping recording information at the time of outputting a track deviation signal being in excess of an allowable deviation amt. or occasionally recording the information in another place and resuming the recording if no track deviation takes place when the information is reproduced again. CONSTITUTION:Information of a reproducing optical system 6 is inputted to a detecting means 13 to send out the track deviation signal. This signal 11 is inputted to a window comparator 14, and when the signal is deviated from a specified level range, the signal is made to be '0', and tracking is carried on with a signal 15 under the state of '1'. This signal may be a control signal for showing a closing and opening command of a tracking servo system. An output '1' of inverting '0' is passed through a gate 16 to be outputted as the track deviation signal 9. This signal is inputted to an FF 41 to be set to its rise, and is used as a gate control signal 17 for a recording signal. By this constitution, a track deviation is detected to stop recording, and this state information can be given to a control device. When the track deviation signal generated due to dust and a flaw is detected by the window comparator 14, its pulse width is narrow, so that, if this is below a prescribed time width, the signal is prevented from being inputted to the gate 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information processing apparatus such as a digital optical disk, and more particularly to an optical information processing method provided with track deviation detecting means capable of stable recording operation.

[0002]

2. Description of the Related Art In digital optical discs, conventional consumer optical discs (that is, video discs, PCMs) are used.
Compared to audio discs), the escape of the light spot from the track being tracked has serious consequences. In particular, when this phenomenon occurs during recording, not only the data to be recorded is lost, but also the data is recorded on the already recorded data, resulting in data destruction. In order to prevent this, it is important to detect the track deviation with high reliability.

Incidentally, in connection with the present invention, JP-A-52-6
7302 and JP-A-55-89920.

Japanese Unexamined Patent Publication (Kokai) No. 52-67302 discloses an erroneous recording or a recording material generated when the apparatus operates by electrically detecting the rotational speed of the recording medium and controlling the irradiation light to the recording medium by this. A technique for preventing damage to the device is described.

In JP-A-55-89220, when recording is started from an unrecorded portion and recording light hits the recorded portion, the influence of interference between the recorded symbol and the recorded symbol is detected to detect the recording signal. A technique for preventing double recording of a signal by stopping the supply is described.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an optical information processing method for a digital optical disk or the like, and in particular, reliably detects that a light spot deviates from a track during a recording operation and destroys data due to the track deviation. It is to provide an optical information processing method capable of recording data regardless of track deviation.

[0007]

SUMMARY OF THE INVENTION The present invention is a recording medium having a light source for emitting a light beam, a track, an optical system for forming a light beam as a spot on the recording medium to record information, and a recording medium. Using the light receiving means for receiving the light beam after being irradiated on the track and the track deviation detecting means for forming the track deviation signal indicating the positional deviation amount between the track center and the spot center by the output from the light receiving means, Based on this, information is recorded along the track while controlling the optical system so that the light beam tracks the track, and when the track off signal exceeds a predetermined value, the positional deviation amount between the track center and the light spot center is A track deviation error signal indicating that a track deviation exceeding the allowable amount has occurred is output. Characterized by stop recording broadcast. Preferably, the track shift error signal is output using the low frequency component of the track shift signal. Although various known forming methods of the track shift signal are known, in principle, the position shift amount between the track center and the spot center is shown as the magnitude of amplitude, and the position shift amount and the magnitude of the amplitude are paired in principle. It is a signal corresponding to 1. Generally, a light spot has a sinusoidal waveform when it crosses a plurality of tracks at a constant speed, and this track deviation signal does not change in amplitude depending on the frequency. And the magnitude of the signal amplitude maintain a constant relationship.

As a related prior application, Japanese Patent Application Laid-Open No. 57-1501
There is number 44. In this system, recording is stopped by monitoring input of a drive signal having a large pulse that cannot follow the tracking control tracking system due to disturbance. For this purpose, the output signal of the phase compensator, which is equivalent to the control signal of the light beam drive system, is compared with a predetermined value (see FIG. 4).
The phase compensator is provided to compensate the frequency characteristics of the light beam drive system, and the control signal of the light beam drive system is normally designed to increase the gain in the high and low frequency bands. . Therefore, since the relationship between the spot-track position deviation amount and the signal amplitude magnitude varies depending on the frequency, the track deviation amount is directly monitored as in the present invention to detect that the light spot has entered the adjacent track. The recording operation cannot be stopped.

The present invention compares the track deviation signal itself, which indicates the positional deviation amount between the track center and the light spot center formed by the output from the light receiving means, with a predetermined value to directly determine the positional relationship between the track and the spot on the medium. Recording is stopped by monitoring, which is technically different.

In addition, when recording information, usually, a method of transferring information to a memory for each predetermined recording unit (for example, a sector) and sequentially recording the information is used, and the recording operation is controlled in the address unit of the sector. ing. Therefore, if the recording is stopped in the middle of a certain sector, it is easier to control the sector from the beginning and the error recovery is easier.

Further, when the track deviation is detected and the recording is stopped, the portion where the track deviation once occurs is reproduced, if the reproduction is possible, the recording is continued, and the recording is resumed only when the reproduction is not possible. By doing so, more efficient error handling becomes possible.

[0012]

According to the present invention, when the track deviation signal exceeds the predetermined value, the track deviation error signal indicating that the position deviation amount between the track center and the light spot center exceeds the allowable amount is generated, and the track deviation error signal is output. By stopping the recording of the information by the light beam by the output of the deviation error signal, it is possible to prevent the spot having the recording output from entering the tracks other than the track to be recorded and destroying the recorded information. Furthermore, in some cases, this large track is not recorded on the deviated track,
By recording information at other locations, recording on defective tracks is avoided. Alternatively, if a track shift is reproduced again on the recording medium where the track shift has occurred, the track itself is recorded again without any defect.

Further, by adopting a method of judging that the amount of positional deviation between the track center and the optical spot center exceeds the permissible amount when the track deviation signal exceeds a predetermined time width and amplitude, Recording can be continued without being affected by minute track deviations caused by dust or scratches.

[0014]

EXAMPLES The present invention will be described below with reference to examples. In a digital optical disk capable of additional recording, the basic configuration for performing additional recording is a driving device for the digital optical disk (optical head, moving means of optical head, rotation system, control circuit for controlling mechanical section, interface with upper controller). A circuit), a controller (which gives an instruction to the optical disc driving device to drive the mechanical portion of the driving device and the optical head according to a certain procedure, and processing of a signal to be recorded on the optical disc and processing of a reproduced signal. It has a function to do).

Unlike a conventional magnetic disk, a digital optical disk cannot erase data once recorded. That is, the recording data is in a recording form in which holes (called pits) are thermally formed in the metal film deposited on the disk surface. Therefore, it is erroneously recorded in a place other than a predetermined place (on a track which is usually called a guide groove, or on a virtual virtual locus where the light spot moves relative to the rotation direction of the disc depending on the method). Must be prevented.

However, in the case of an optical disk as compared with a conventional magnetic disk or the like, since the track pitch is narrow at about 1.6 μm, a high positioning accuracy is required, and a large amount of positional deviation that intrudes into an adjacent track is recorded. Cause the destruction of.

An embodiment of the present invention in which such data destruction is prevented is shown in FIG. FIG. 1 is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention. A signal 2 to be recorded (a signal obtained by modulating raw data) is transmitted from the controller 1 and input to the gate circuit 40. The output signal 3 of the gate circuit 40 is input to an optical system 4 for recording (a light source, an optical path for guiding light from the light source to the disk 5 and an objective lens for focusing the light on the disk surface). The recording optical system 4 converts the signal 3 into a change in light intensity and forms an information pit on the disk 5. On the other hand, the reproducing optical system 6 reads the recorded information pits and the information recorded in the optical form such as the already-recorded guide grooves as the change of the light intensity from the disc 5, and the track deviation detection circuit. At the same time, the signal is sent to the controller 1 as the reproduced signal 8. This signal extracts only the information signal portion in the controller, is pulse-formed, and then is input to the demodulator to become a data signal.

On the other hand, as the signal 8 input to the track loss detection circuit 7, only a signal suitable for detecting the track loss is selected from the signals 8 and the track loss described later is detected.

In order to prevent data destruction, in the present invention, the gate circuit 40 is controlled by using the output of the track loss detection circuit (a signal generated when the track loss occurs) to unconditionally write a recording signal. 2 should not appear in the output signal 3 of the gate circuit 40. At the same time, an off-track error signal 9 is generated and input to the controller 1 to inform that the off-track has occurred and the gate circuit 40 has been closed. The controller 1 which has received the track off error signal 9 initiates an error recovery operation. In the case of this kind of error, it is an error that should be processed with the highest priority. As a processing method, for example, since the recording data is lost in the middle, the recording data is again divided into units of data delimiters (which are referred to as sectors in a magnetic disk etc.) in other places (sectors in a track where a track is lost). Other than the physical location of. Alternatively, after returning to the reproducing state and reading the sector from which the track has been removed again, if it can be read, the recording is restarted and the recording is continued.

As described above, according to the present invention, it is possible to prevent the data destruction due to the track loss.

Next, examples of the present invention will be described in more detail. FIG. 2 is a diagram for explaining the present invention, FIG. 2-a shows a cross section of a track recorded on a disk, and FIG. 2-b shows a waveform of a track deviation signal. Figure 2-
When a light spot is irradiated on the track as shown in a and the spot moves in the radial direction of the track, a track deviation signal indicating a deviation between the track center and the spot center as shown in FIG. 11 occurs. As means for detecting the track shift signal 11, a method of detecting using the two auxiliary spots, which has already been disclosed in JP-A-49-50954, and JP-A-49-6070.
There is a method of detecting using diffracted light disclosed in JP-A No. 2-9, and a method of making the spot meander relative to the track, as disclosed in JP-A-49-94304 and JP-A-50-68413. .

Whichever of these methods is used, the waveform of FIG. 2B is generated as the track deviation signal. Here, the black mark 12 is the target point (corresponding to the track center) pulled by the tracking servo system. + Side of this signal 11 and-
A window converter is provided which indicates a logic level of "1" when the signal 11 is within the side level (indicated by a chain double-dashed line) and otherwise indicates a logic level of "0". Track off is detected by looking at this output.

FIG. 3 shows a block diagram of this embodiment. That is, as shown in FIG. 3, the reproduction information signal detected from the reproduction optical system 6 is input to the track deviation detecting means 13,
Generates track deviation signal. This track deviation detecting means is known as described above, and will not be described in detail here. The signal 11 is input to the window comparator 14,
When it goes out of the specific level range from the + side to the-side, the logic level becomes "0", so that the track drop can be detected. However, since only the output of the window comparator 14 is "1" even if there is a light spot between the tracks, the signal 15 indicating that the light spot is on the track is required.

This signal may be a control signal indicating a closing / opening command of the tracking servo system. In order to record / reproduce normal information, spots must be positioned on the track. That is, it is necessary to perform the tracking operation. By doing so, for example, by closing the servo system, the light spot is drawn in the vicinity of the black circle 12 of the target point, and in a normal state (a normal state in which track separation does not occur), the light spot is near the target point and the servo system is close. The signal 15 that is closed is at "1". Therefore, tracking is performed when the control signal is "1", and the condition for detecting the track loss is satisfied.

However, if the light spot causes a track off for some reason, the output of the converter 14 becomes "0", and its inverted output "1" passes through the gate circuit 16 and becomes the track off signal 9. Is output. Since this signal instantaneously becomes the logical level "1", the signal 9 is input to the flip-flop circuit 41,
It is set at the rising edge and used as the control signal 17 of the gate circuit 40 that controls passage of the recording signal 2. With the configuration described above, it is possible to detect the track loss, stop recording by the detected track loss signal, and notify the control 1 of this state.

The above is a description of the principle of detecting track off according to the present invention. When the actual track deviation signal 11 is observed with the servo system closed, dust and scratches on the disk cause Although the time width is narrow, there is a case where a waveform that instantaneously raises the set level of the window comparator is generated. Due to this malfunction, recording may be erroneously stopped even in a normal track tracking state. Therefore,
There is a need for a reliable method that will not accidentally detect when the truck is off the track.

FIG. 4 is a block diagram showing an embodiment of the present invention for preventing the above erroneous detection. That is, the signal detected by the window comparator 14 for the disturbance of the track deviation signal caused by dust or scratches has a narrow pulse width, so that a signal having a certain time width or less is input to the pulse width detection circuit 20. , So as not to input to the gate circuit 16 of FIG. There are various methods for measuring the time width. For example, a monostable multivibrator which becomes "1" level for a certain set time from the rise of the signal 21 is started, and an inverted signal of this output and the signal 21
Is inputted to the AND circuit, it is possible to prevent a signal having a pulse width within a certain set time from being output. In this way, malfunction due to dust, scratches, etc. is prevented.

FIG. 5 is a waveform diagram for explaining another embodiment for preventing erroneous detection. FIGS. 5-a and b are shown in FIGS.
Similarly, the cross section of the disk and the waveform of the track shift signal 11 are shown. FIG. 7C shows an inverted signal 21 of the output of the window comparator 14 which detects the track deviation signal 11 at the levels E ₁ and E ₂ . FIG. 3D shows a signal 24 representing the total light amount signal in the reproduction information signal read from the disc 5 by the reproduction optical system 6. The relationship when the light spots of the signal 24 and the signal 11 pass through the track is such that the phase relationship of the AC components is shifted by 90 °. Therefore,
The level of the signal 24 is determined by the comparator at the level E ₃ , and the signal 23 is detected. The level E ₃ is selected so that the “1” edge portion of the signal 23 substantially corresponds to the peaks (+ side and − side) of the signal 11. Then, when the light spot goes off the track, the signal 23 becomes "1" when the signal 21 rises and the signal 23 becomes "0" when the signal 21 falls.

Track off can be determined by detecting the change pattern on the time axis. A block diagram of this embodiment is shown in FIG. Signal representing the total light amount obtained by the reproducing optical system 6, the converter 22, is compared to the level E _3, is smaller than the level E _3, signal 2 becomes "1"
3 is generated. From the trailing edge of the signal 23, the monostable multi-babbulator 25 having a specific pulse width is activated, and the output and the signal 21 are ANDed by the AND circuit 26 to obtain the track off signal 9. In this case, even if the track deviation signal 11 outputs a pulse-like signal due to scratches, dust, or the like, no malfunction of the track deviation occurs. Since the signal 23 is a signal indicating that a light spot exists on the track, it can also be used as the control signal 15 indicating a close / open command to the trunking servo system described in FIG.

As means for preventing erroneous detection, FIG.
There is a configuration shown in. FIG. 7 is a block diagram showing the main part of another embodiment of the present invention, in which the track deviation signal 11 is passed through the low pass filter 30 and input to the window comparator 14. In this way, the short pulse signal is not input to the window comparator 14. The cut-off frequency of the filter 30 must be determined by the time width of the short pulse signal generated from the disc and its frequency band. This depends on the substrate material of the disc, its manufacturing control, and the user's storage condition. It is decided.

Further, another embodiment for preventing malfunction will be described with reference to FIGS. 8 and 9. 8-a and b are
FIG. 9 is a waveform diagram for explaining the present embodiment, and FIG. 9 is a block diagram showing its configuration. For large things such as dust and scratches, not only the track deviation signal but also the total light amount signal 24 described in FIG. That is,
When the light spot crosses a track having dust or scratches, the total light amount signal 24 changes as shown by dotted lines 51, 52 and 53 in FIG. Generally, light spots are scattered by dust and scratches, and in an objective lens having a certain specific numerical aperture, when the scattering angle exceeds an angle determined by the numerical aperture, the amount of light passing through the objective lens decreases, as shown by dotted lines 51 and 52. Signal 2
4 decreases from the normal signal level. Further, the dust contains high reflectance, and in this case, the signal 24 is increased above the normal signal level, as indicated by the dotted line 53.

Therefore, as shown in FIG. 9, the signal 24 is input to the window comparator 31 and becomes "1" in the range of the levels E ₄ and E ₅ and "0" in the other range (FIG. 8-b).
Shown in FIG. 2) and input this output to the gate circuit 32,
Malfunction is prevented by taking the logical product with the output of the gate circuit 16 which detects the track deviation from the track deviation signal. It is necessary to determine the setting values for the levels E ₄ and E ₅ depending on the disc.

Next, a method of error recovery in the case where track loss occurs will be described.

FIG. 11 is a front view of the optical disc. The recording area is an area from the disc inner diameter r ₁ to the disc radius r ₂ . 1.6μ pitch interval in the radial direction of this disc
Tracks are arranged concentrically or spirally in m. In addition, the length of one round along the circumference of the track is m + 1
Divide into equal parts. The area divided in the circumferential direction is the minimum unit for managing the recording information and is called a sector. Therefore, the track number and the sector number are required for the position information indicating the location of the record information. In FIG. 11, the vicinity of the “0” th sector of an arbitrary track 107 is enlarged and shown in FIG. Information is recorded on the track 107 in the circumferential direction on the disk surface in the order of 0th, 1st and 2nd. A specific number of sectors from the last m-th sector are free sectors and are not recorded in a normal recording state. Therefore, the information that can be recorded on one track is the number of sectors minus m + 1 minus the number of empty sectors. In FIG. 12, two empty sectors 108 are selected, and m-
It is set to the 1st and mth sectors.

Here, a method of recording information and error recovery will be described with reference to the block diagram of FIG. The information 101 to be recorded is modulated through a modulation circuit (not shown) for each sector information amount, and the clock oscillator 1
Register 102 according to the clock generated from 00
The information after modulation for one sector is taken in.

Information after the modulation for one sector is stored in the memory 1
The data is stored in the memory 103 in accordance with the address sent by the address designating circuit 106 designating the address 03. It is the computer 105 that designates the address transmitted by the address designating circuit 106. For example, a microcomputer currently on the market may be used. When the information to be recorded is stored in the memory 103, the computer 10
A command is given to the addressing circuit 106 according to the program stored in the memory 5, and the information stored in the memory 103 is sequentially input to the register 104 for each sector of information, and is generated from the clock generator 100. The recording information signal 2 is input to the gate circuit 40 according to the clock. In this way, the recording information signal 2 is transmitted from the register 104 in time series as shown in the time chart of FIG. Here, the portion surrounded by diagonal lines is information for one sector.

When track loss occurs at the instant of time t ₀ , the track loss detection circuit 7 generates a signal 17 for controlling the gate circuit 40, and the recording signal 3 input to the recording optical system 4 is at time t ₀ . Be cut off. At the same time, the off track signal 9 is transmitted to the computer 105. Computer 105 is time t
_Since the address in the memory 103 at the time of ₀ is stored, the information for the nth sector in which recording was interrupted can be recalled from the memory 103 at time t ₀ . Information of one sector that has been recalled is recorded in one of the free sectors 108 shown in FIG. It should be noted that in the (n + 1) th sector, n + should be recorded considering the arrangement in the memory 103 originally.
Information for the first sector is recorded by a normal procedure.

[0038]

As described above, the present invention provides an optical information processing apparatus which prevents the destruction of data by including track deviation detecting means capable of reliably detecting that a light spot has deviated from a track. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram illustrating a relationship between a track and a track deviation signal.

FIG. 3 is a block diagram showing a configuration of a track detachment detection circuit of FIG.

FIG. 4 is a block diagram showing a main part of another embodiment of the present invention.

FIG. 5 is a waveform diagram for explaining an embodiment of the present invention.

FIG. 6 is a block diagram showing the configuration.

FIG. 7 is a block diagram showing a main part of still another embodiment of the present invention.

FIG. 8 is a signal waveform diagram and a block diagram showing yet another embodiment of the present invention.

FIG. 9 is a signal waveform diagram and a block diagram showing still another embodiment of the present invention.

FIG. 10 is a block diagram illustrating an error recovery method according to the present invention.

FIG. 11 is a conceptual diagram for explaining an error recovery method according to the present invention.

FIG. 12 is a conceptual diagram for explaining an error recovery method according to the present invention.

FIG. 13 is a conceptual diagram for explaining an error recovery method according to the present invention.

[Explanation of symbols]

6 ... Reproduction optical system, 11 ... Track deviation signal, 13 ... Track deviation detecting means, 14 ... Window comparator, 15
... Signal indicating that the light spot is on the track, 16
... gate circuit, 17 ... control signal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Takasago 2880 Kokuzu, Odawara, Kanagawa Stock company Hitachi Ltd. Odawara factory (72) Inventor Yasumitsu Mizoguchi 2880, Kunizu, Odawara, Kanagawa Hitachi Odawara factory Within

Claims (7)

[Claims] 1. A recording optical system for irradiating a recording medium for optically recording and reproducing predetermined information along a track with a light beam as a spot, and a reproducing optical system for detecting return light from the recording medium, A track shift detection circuit that generates a track shift signal that represents the amount of shift between the track center and the spot center based on the output of the reproduction optical system by the magnitude of amplitude;
Control means for controlling the irradiation position of the light beam so that the spot tracks the track according to the track deviation signal, and the track deviation signal is compared with a preset value indicating a predetermined range. An optical system having first means for generating a signal indicating that the spot is displaced by more than a permissible amount and second means for stopping the recording of information by the light beam by the output of the first means. Information processing device. 2. The optical information processing apparatus according to claim 1, further comprising a filter means for passing a low frequency component of the track shift signal, and an output of the filter means is input to the first means. 3. The optical information processing apparatus according to claim 1, wherein the track deviation signal is a signal whose waveform when the spot traverses a plurality of tracks at a constant speed has a sinusoidal waveform. 4. A light source for emitting a light beam, a recording medium having a track, an optical system for recording the information by forming the light beam as a spot on the recording medium, and an optical system for irradiating the recording medium. The light receiving means for receiving the light beam and the track deviation detecting means for forming the track deviation signal indicating the positional deviation amount between the track center and the spot center by the output from the light receiving means are used, and the light is detected based on the track deviation signal. Information is recorded along the track while controlling the optical system so that the beam tracks the track, and when the track deviation signal exceeds a predetermined value, the positional deviation amount between the track center and the optical spot center is allowed. A track deviation error signal indicating that a track deviation exceeding the capacity has occurred is output, and the above-mentioned optical signal is output by outputting the track deviation error signal. Optical information processing method characterized by stopping the recording of information by chromatography beam. 5. The optical information processing method according to claim 4, wherein when the low frequency component of the track deviation signal exceeds a predetermined value, the track deviation error signal is output. 6. The optical information processing method according to claim 4, wherein the track shift signal is a signal having a sinusoidal waveform when the light spot traverses a plurality of tracks at a constant speed. 7. The optical information processing method according to claim 4, wherein the track deviation signal represents, in principle, a positional deviation amount between the track center and the spot center as a magnitude of amplitude.