JPH09138950A - Method for reproducing multilayered disk recording information and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain continuity of reproducing information by storing read starting position information, changing a read object of a read light beam from one bit of information to another bit of information after finishing the read of the former information and moving the read point according to the position information. SOLUTION: When completion of the read of a 1st information recording layer is discriminated by a system control circuit 12, simultaneously with a focus jump to a 2nd information recording layer, the read point is moved in the radial direction of the disk, and then the read point is shifted from a recording position of an address N to reach N+1 quickly. Then, a control signal is sent to a pickup control circuit 9, and after a focus lock, a target address is searched to commence the read of the 2nd information recording layer. At the time of the focus jump prior to the search, the read point is moved by a beginning edge biased amt. of the 2nd information recording layer, so that a search time for the beginning edge of the 2nd information recording layer is shortened, and as a result, the required time from the completion of the read of the 1st information recording layer to the commencement of the read of the 2nd information recording layer is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for reading a disc having a plurality of information recording layers (hereinafter referred to as a multi-layer disc), and more particularly to each of the information recording layers from one main surface side of the disc. The present invention relates to a method and apparatus for reading and reproducing recorded information.

[0002]

2. Description of the Related Art In such a multi-layer disc, unlike a disc in which information is recorded on a single recording layer, a reading point is moved from one information recording layer to the next information recording layer to record information on both recording layers. The operation of continuously reproducing information is required. In order to realize such an operation, a necessary and sufficient amount of read information is stored in a memory in advance before the movement of the reading point, and the reading is interrupted during the movement of the reading point and the target of the next information recording layer. By reproducing the information read from the memory until the read point is located at the address and the read preparation is completed, it is possible to prevent the reproduced information from being interrupted when the next information recording layer is read. Conceivable.

According to this, the memory needs to have a storage capacity sufficient to continuously read the reproduction information while the reading is suspended. Therefore, the longer the time spent for the interruption, the larger the storage capacity of the memory must be made, and further improvement is desired in view of simplification of the configuration, cost reduction, and the like.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a multilayer disc capable of maintaining the continuity of reproduced information even when the reading point moves to a new information recording layer with a simple and inexpensive structure. It is an object of the present invention to provide a reproducing method and a reproducing apparatus for recorded information. Another object of the present invention is to provide a reproducing method and a reproducing apparatus for recording information on a multi-layer disc capable of shortening a read interruption time when a read point moves to a new information recording layer. Still another object of the present invention is to provide a reproducing method and a reproducing apparatus for multi-layer disc recorded information capable of reducing a storage capacity required for a memory used when a reading point is moved to a new information recording layer. That is.

[0005]

In the reproducing method according to the present invention, a multi-layer disc having at least two information recording layers is irradiated with a reading light beam from one main surface side of the information recording layers to record the information on each of the information recording layers. A method for reading and reproducing the information, wherein a storage step of storing position information regarding a reading start position when reading of the other of the information recording layers is started before reading of one of the information recording layers is finished, And a reading layer switching step of switching the reading target of the reading light beam to the other information recording layer after the reading of the one information recording layer and moving the reading light beam in the disc radial direction according to the position information. It is characterized by having.

The reproducing apparatus according to the present invention irradiates a multi-layer disc having at least two information recording layers with a reading light beam from one main surface side thereof to read and reproduce the information recorded in each of the information recording layers. The device is a device for rotating and driving the multi-layer disc, and a reading light beam irradiating the multi-layer disc so as to be movable in the radial direction thereof, receiving return light from the multi-layer disc, and the amount of received light. Alternatively, it has a reading unit that generates a reading signal according to a light receiving state, and a control unit that detects that the reading of any one of the information recording layers is completed based on the reading signal. A storage unit is provided for storing position information regarding a reading start position when reading of the other of the information recording layers is started before reading of one of the information recording layers is completed. After the reading of one of the information recording layers is completed, the reading means is caused to switch the reading target of the reading light beam to the second information recording layer, and the reading light beam is changed to a disc radius according to the position information. It is characterized by moving in the direction.

[0007]

First, the recording form of a multilayer disc applied to the present invention can be basically represented schematically as shown in FIG. In FIG. 1, when the reading light beam is irradiated in the direction indicated by the arrow a, the first information recording layer is arranged below the second information recording layer. For example, a spiral signal is recorded on each recording layer, the reading direction of the first information recording layer is determined from the inner circumference to the outer circumference, and the reading direction of the second information recording layer is determined from the outer circumference to the inner circumference. More specifically, the information is recorded so that the reading of the end of the outermost recording portion of the first information recording layer and the reading of the beginning of the outermost recording portion of the second information recording layer continue. In other words, it is premised on the recording process that the end of the first information recording layer and the start of the second information recording layer have the same disk radial distance. When another information recording layer is arranged on the second information recording layer, the odd-numbered information recording layer has the same spiral direction as that of the first information recording layer, and the even-numbered information recording layer is the first information recording layer. The reading direction is determined by the same spiral direction as that of the two-information recording layer. Then, the ends of the information recording layers are aligned with each other so that the reading is continued between the information recording layers.

Although FIG. 1 shows a recording mode of a spirally recorded multi-layer disc, the present invention can be applied to a multi-layer disc of another type. That is, the signal may be recorded in the form of concentric circles or a mixture of concentric circles and spirals. However, the reading is continued between the information recording layers as in the mode in which the reading direction of the odd-numbered information recording layers is set from the inner circumference to the outer circumference and the reading direction of the even-numbered information recording layers is set from the outer circumference to the inner circumference. It is premised that the edges of the information recording layers are aligned with each other. The present invention is applicable regardless of whether the odd-numbered and even-numbered information recording layers are in the reading direction from the inner circumference to the outer circumference or in the reading direction from the outer circumference to the inner circumference. The order is not limited to the transfer from the lower layer to the upper layer, and the transfer may be performed from the upper layer to the lower layer, and one or several information recording layers may be formed without necessarily moving to the adjacent information recording layers. The present invention can be applied even if it jumps over and arbitrarily shifts from the even-numbered information recording layer to the odd-numbered information recording layer or from the odd-numbered information recording layer to the even-numbered information recording layer.

FIG. 2 shows the basic structure of an optical disk recording information reproducing apparatus according to the present invention. In FIG. 2, the multi-layer disc 1 having the first and second information recording layers (surfaces) having the above-described recording form is a spindle motor 2
While being driven to rotate, a reading light beam from a pickup 3 mounted on a carriage (not shown) and movably provided in the disk radial direction by a carriage motor is irradiated from a predetermined main surface side. The reading light beam is reflected by the multilayer disc 1 and returns to the pickup 3 to pick up the light.
Receives the returned light, photoelectrically converts it, and supplies the photoelectrically converted signal to the RF amplifier 4 as a read signal. The RF amplifier 4 high-frequency amplifies the read signal and supplies the read signal to the signal demodulation circuit 5. The signal demodulation circuit 5 has a function of demodulating the supplied read signal into a digital main information signal related to voice, image, etc. (for example, demodulation processing and error correction processing of 8/15 modulation code), and is added to the read signal. It has a decoding function to restore control information signals such as address signals and synchronization signals, that is, control data. Signal demodulation circuit 5
The main information signal demodulated by is supplied to the buffer memory 6, is once written therein, and is then sequentially read out and transferred to the audio video decoder 7. The decoder 7 decodes the signal read from the buffer memory 6 (for example, M
PEG decoding), and transferred as audio and video data to an audio and image reproduction system (not shown). The main information signal is not limited to voice and image, but may be computer data, or may be a mixed signal of these.

The read signal from the pickup 3 is also supplied to the error generating circuit 8. The error generation circuit 8 uses the tracking error signal,
A focus error signal and a carriage error signal are generated, and these are supplied to the pickup control circuit 9. The pickup control circuit 9 generates a drive signal for controlling the irradiation position (reading point) of the reading light beam formed by the pickup 3 on the disc 1 to coincide with the recording track of the disc 1 in accordance with the tracking error signal. And supplies it to the pickup 3. The pickup 3 drives a built-in tracking actuator that deviates the reading point in the disk radial direction in response to the drive signal. The pickup control circuit 9 also generates a drive signal for controlling the reading point to substantially coincide with the recording surface of the disk 1 to be read according to the focus error signal, and supplies this to the pickup 3. The pickup 3 drives the built-in focus actuator according to this drive signal. Further pickup control circuit 9
Generates a drive signal for controlling the bias amount of the tracking actuator to be zero according to the carriage error signal, and supplies this to the carriage motor.
In response to this drive signal, the carriage motor drives the carriage to drive the entire pickup 3 in the disk radial direction. The loop of the pickup 3 (or carriage motor), the error generation circuit 8 and the pickup control circuit 9 is
Form a tracking servo loop, focus servo loop, and carriage servo loop during normal playback.

The read signal amplified by the RF amplifier 4 is also supplied to the spindle error generating circuit 10, where the actual rotation speed of the disk 1 obtained based on the synchronization signal included in the read signal and a predetermined rotation. A spindle error signal is generated according to the difference from the speed and is supplied to the spindle control circuit 11. The spindle control circuit 11
Disk 1 based on the spindle error signal supplied
The spindle motor 2 is supplied with a drive signal for rotating the motor at a predetermined rotation speed. The loop of the pickup 3, the RF amplifier 4, the spindle error generation circuit 10, the spindle control circuit 11, and the spindle motor 2 forms a spindle servo loop during normal reproduction.

A system control circuit 12 is provided as means for overall control of the above-mentioned respective parts. The system control circuit 12 follows the display 13 and the operation button group 14, displays the operation state of the device, and the signal demodulation circuit 5 according to various operation modes designated by the user pressing the operation button group 14. Buffer memory 6, pickup control circuit 9, spindle control circuit 11, decoder 7,
Supply corresponding control signals. More specifically, the system control circuit 12 receives the control data included in the read signal from the signal demodulation circuit 5, determines more detailed control parameters according to the contents, and demodulates a timing signal for signal demodulation. It is supplied to the circuit 5. In addition, the system control circuit 12 uses the buffer memory 6
And servo control including the pickup control circuit 9 and the spindle control circuit 1
Opening and closing of the servo loop including 1 and interruptive or compulsory drive control for the tracking actuator, focus actuator, carriage motor and spindle motor 2 are also performed. Further, the system control circuit 12
Also controls the decoder 7 according to the content of the main information signal, the operation state of the decoder 7, the user's operation, and the like.

Next, the characteristic operation of this optical disk recorded information reproducing apparatus will be described. FIG. 3 shows an initial focus control process executed by the system control circuit 12. The system control circuit 12 detects that a new disc is mounted during execution of a main routine (not shown). Alternatively, when it is determined that the focus control operation needs to be performed from the beginning, a focus activation command is issued and the initial focus control subroutine is called.

First, the system control circuit 12 issues a command for focus lock, and supplies a control signal to the pickup control circuit 9 so as to align the reading point with the first information recording layer (step S11). When the focus servo is activated and the focus lock is completed in step S11, the final address of the first information recording layer is searched (step S12). When the pickup 3 is located at the home position on the innermost circumference side of the disc 1 at the start of the process of step S12 and the reading direction of the first information recording layer is from the inner circumference to the outer circumference of the disc, the focus is set. Under servo control, the system control circuit 12 moves the pickup 3 in the outer peripheral direction via the pickup control circuit 9 and detects the end of the information recorded in the first information recording layer. At the time when the end is detected, The movement of the pickup 3 is stopped. Such end detection is preferably based on an address, and the final address of the layer recorded in the lead-in area of the first information recording layer is read at the first focus lock and stored in the RAM in the system control circuit 12, It is desirable that the end detection is performed by detecting whether the address data included in the control data from the signal demodulation circuit 5 matches the stored final address.

When the search for the final address in the first information recording layer is completed in step S12, the focus jump is made to the second information recording layer while holding the reading point so as to scan the position of the final address (step S13). In this process, when the final address is detected in step S12, the pickup control circuit 9 is used to immediately control the tracking and the carriage so as to hold the reading point at the position where the final address is recorded. The action is taken. In the focus jump, the focus servo for the first information recording layer up to that point is cut off, and the focus actuator of the pickup 3 drives and controls the objective lens forming the reading point in the optical axis direction to set the reading point to the first reading point. Second from the information recording layer
It is performed by reaching the information recording layer. The fact that the reading point has reached the second information recording layer is determined, for example, by monitoring the focus error signal level and exhibiting a predetermined change in the error signal level, and finally the address read in step S15 described below. Can be confirmed by.

After the focus jump is performed in step S13, the system control circuit 12 determines in step S1.
As in the case of 1, a command for focus lock is issued, and a control signal is supplied to the pickup control circuit 9 so as to align the reading point with the second information recording layer (step S1).
4). When the focus lock is completed in step S14, the address of the position where the reading point is scanned on the second information recording layer is read (step S15). Next, the system control circuit 12 stores the difference between the address read in step S15 and the target address (step S1).
6).

In this case, the target address refers to the start end where information is recorded in the second information recording layer (that is, the head address), and the series of addresses recorded on the disc are the first and second information recording layers. If it has a continuous value over the range, it indicates the value next to the value of the final address of the first information recording layer. Therefore, if the final address of the first information recording layer is N as shown in FIG. 4, the target address is N + 1, which corresponds to the start edge of the second information recording layer. In addition, the second read in step S15
The address of the information recording layer is recorded at a position where the distance from the disc center (disc radius distance) is equal to the position of the final address N of the first information recording layer, and is N + 3001 as shown in FIG. Suppose there is. Then, the difference between the two addresses obtained in step S16 is
(N + 3001)-(N + 1) = 3000, which is the distance from the position of the final address N of the first information recording layer to the position of the start address N + 1 of the second information recording layer, that is, the first information recording. This corresponds to the amount of deviation of the beginning of the second information recording layer with respect to the end of the layer. Further, this deviation amount is calculated by using the final address N of the first information recording layer stored in the RAM in the system control circuit 12 and (N +
3001)-(N) -1 = 3000.

In a general multi-layer disc, the i-th disc
When the information recording layer is recorded so as to be continuously reproduced from the (i + 1) th information recording layer, at least one address is set if the last address of the ith information recording layer and the start address of the i + 1th information recording layer are continuous. If they are discontinuous, both addresses may be stored in the RAM at the time of the first focus lock.

As shown in FIG. 4, various factors may be considered that the start end of the second information recording layer deviates from the end end of the first information recording layer. Basically, as described at the beginning of this section, in the multi-layer recording disc, the ends of the information recording layers are aligned so that reading can be continued with each other.
If the end of the second information recording layer and the start of the first information recording layer coincide with each other at the same disc radius distance, reading should be resumed immediately from the start of the second information recording layer only by the focus jump. is there. However, in reality, an eccentricity error or a track pitch error occurs in the disc manufacturing process for each information recording layer, or an error occurs in the bonding position of the information recording layers when manufacturing a multi-layer disc. Due to these errors and the like, the ends of the respective information recording layers are misaligned and recorded. As an actual example, it has been found that the starting end of the second information recording layer may be positioned with a deviation amount of 0.5 mm from the ending end of the first information recording layer. At this time, if the track pitch is 0.74 μm and the addresses are inserted along the track at intervals of about 4.8 mm, the address is about 51000 due to the deviation of 0.5 mm near the radius of the disk 116 mm. It is out of alignment.

After step S16, the process shifts to the main routine. After the focus control of FIG. 3 is performed, excellent continuous reproduction can be performed across the information recording layers. The flowchart of FIG. 5 shows the processing procedure of the continuous reproduction control executed by the system control circuit 12. When the continuous reproduction mode is designated, the routine shifts to this routine during information reproduction of the first information recording layer.

That is, the system control circuit 12 first
It is determined whether or not the reading of the first information recording layer is completed (step S21), and if it is not completed, this determination process is repeated and the information reproduction of the first information recording layer is continued. When it is determined in step S21 that the reading of the first information recording layer has been completed, the system control circuit 12 performs the focus jump to the second information recording layer and the previous step S16.
The reading point is moved in the radial direction of the disc in accordance with the deviation amount (address value) of the leading edge of the second information recording layer stored in step S22. Therefore, according to the previous example, since such a deviation amount is 3000, as shown by the image of the arrow drawn with a dotted line in FIG. Simultaneous movements of movement in the radial direction of the disk are performed. As a result, the reading point can quickly reach the recording position of the address N + 1 from the recording position of the address N.

After step S22, the system control circuit 1
Similarly to the previous step S14, 2 issues a command for focus lock and supplies a control signal to the pickup control circuit 9 so as to align the reading point with the second information recording layer (step S23). When the focus lock is completed in step S23, the target address is searched (step S24) and the reading of the second information recording layer is started (step S25).

In the flow of FIG. 5, step S22.
By this, the reading point is already positioned near the recording position of the start address of the second information recording layer, and the focus lock is completed near the search target (step S23). Therefore, the search of the start address in step S24 takes an extremely short time. Will be enough. On the other hand, in the case where after the reading of the first information recording layer is completed and only the focus jump to the second information recording layer is performed to perform the processing of step S23 and subsequent steps, in the example of FIG. From the recording position near address N + 3001 to address N +
1 must be searched for, the moving distance of the reading point required for the search becomes long, and a large amount of time is consumed.
As described above, in the flow of FIG. 5, the reading time is moved to the start edge of the second information recording layer by moving the reading point by the deviation amount of the start edge of the second information recording layer during the focus jump before the search. As a result, it is possible to shorten the time required from the end of reading the first information recording layer to the start of reading the second information recording layer (interruption time of reading).

The effect of shortening the read interruption time can be explained with reference to FIG. FIG. 6 is a graph in which the vertical axis represents the amount of data occupied in the buffer memory 6 (the amount of write data that has not been read) and the horizontal axis represents the elapsed time. Is represented.

The buffer memory 6 is the system control circuit 1
Under the control of 2, the main information signal from the signal demodulation circuit 5 is written at a predetermined rate fw, and the written main information signal is sequentially read at a predetermined rate fr and transferred to the decoder 7. As the buffer memory 6, a so-called FIFO for reading data in the order of writing
Type memory is preferred. Here, fw> fr, and when writing and reading are performed in parallel in the buffer memory 6, a writing amount larger than the reading amount per unit time is generated, and the data occupancy amount is the storage capacity of the buffer memory 6 ( The maximum storable data amount) will be approached.

When the data occupancy of the buffer memory 6 reaches a predetermined value corresponding to the storage capacity of the buffer memory 6 or an amount slightly smaller than that, the system control circuit 6 puts the pickup 3 into the pause state and writes the buffer memory 6. Stop the inclusion. Such a pose corresponds not only to tracking control through the pickup control circuit 9 that holds the reading point so as to repeatedly scan the recording position that was read immediately before the pause, but also to the recording position that was read immediately before the pause through the spindle control circuit 11. The operation involves maintaining the disc rotation speed. During the pause, the buffer memory 6 continues the reading while stopping the writing, so that the data occupation amount continues to decrease at the reading rate fr. When the data occupancy amount falls below the predetermined amount, the system control circuit 6 releases the pause, puts the pickup 3 in the reading state, and restarts writing to the buffer memory 6. As a result, the recording position read immediately before the pause is sequentially scanned, and the disc 1 is controlled to the rotation speed corresponding to the scanning position. Thus, until the reading of one information recording layer is completed, the buffer memory 6 is continuously read, while the paused state and the read state are alternately repeated in the pickup 3 and the spindle motor 2.
In synchronization with this, writing stop and writing are alternately repeated in the buffer memory 6.

After all reading of the first information recording layer is completed, from the movement including the focus jump of the reading point as described in steps S22 to S24 to the completion of the read preparation of the second information recording layer. Is performed. During this operation, the pickup 3 suspends reading and the buffer memory 6 performs only reading without writing, so that the data occupation amount continues to decrease at the reading rate fr. In the buffer memory 6, if the time of the movement / preparation period is too long, there is no storage data to be read, so that the data occupancy becomes zero, and the data connected thereafter cannot be continuously output as reproduction information. . Therefore, the buffer memory 6 is required to have a memory capacity equal to or more than the total amount of data read during the movement / preparation period.

Therefore, in order to shorten the time required for the movement / preparation period, in step S22 described above, the reading point is moved by the amount of deviation of the start edge of the second information recording layer during the focus jump before the search. This shortens the reading interruption time when the reading point moves to the second information recording layer,
The memory capacity required for the buffer memory 6 is reduced. The reduction of the movement / preparation time and the reduction of the memory capacity contribute not only to the simplification of the configuration but also to the cost reduction.

After the movement / preparation period, the reading mode is designated again for the pickup 3 and the writing mode is designated for the buffer memory 6. Then, when the data occupancy reaches a predetermined value near the storage capacity of the buffer memory 6 in the information reproduction of the second information recording layer, the same pause, read, write stop and write repeat operation as described above is performed again. Is done. In the flow of FIGS. 3 and 5, the difference between the read address and the target address is obtained and stored in step S16 executed in the initial focus control, and the difference is read and stored in step S22 executed in the continuous reproduction control. At this time, the reading point is moved in the radial direction of the disc in accordance with the value of the stored difference (deviation amount of the leading edge of the second information recording layer), but the present invention is not limited to this mode. Another embodiment is shown in FIG.
And the flow of FIG. 8 is mentioned.

In FIG. 7, the address of the second information recording layer corresponding to the end of the first information recording layer read in step S15 is stored (step S16A). Further, in FIG. 8, when the reading of the first information recording layer is completed, the second jump corresponding to the end of the first information recording layer stored in step S16A is accompanied by the focus jump to the second information recording layer. The address of the information recording layer is read and the difference between this address and the target address is obtained (step S22A). In short, Figure 3
Further, as shown in FIG. 5, the amount of deviation of the start edge of the second information recording layer is not obtained in the initial focus control, and instead, the address of the second information recording layer corresponding to the end position of the first information recording layer is stored for continuous reproduction. In the control, the deviation amount of the starting edge of the second information recording layer is obtained from the stored address. As described above, even if the start edge deviation amount of the second information recording layer is obtained in the continuous reproduction control from the address of the second information recording layer corresponding to the end position of the first information recording layer stored in the initial focus control, as shown in FIG. An effect equivalent to that of the control shown in FIG. 5 can be obtained. However, since the process of step S22A of FIG. 8 involves an operation for obtaining the difference between two addresses,
Step S22 in FIG. 5 which simply reads the stored deviation amount.
There is a possibility that it may be somewhat disadvantageous from the viewpoint of making the movement of the reading point swift and smooth as compared with the processing of.

Thus, although the control method is slightly different between FIGS. 3 and 5 and FIGS. 7 and 8, the reading point is moved by the amount of deviation of the starting edge of the second information recording layer during the focus jump before the search. The points are in agreement, which forms one of the main requirements of the invention. in short,
When moving the reading point by the amount of deviation of the start edge of the second information recording layer during the focus jump before the search,
Before the reading of the information recording layer is completed, the position information regarding the reading start position when the reading of the second information recording layer is started may be stored in advance. In the above description, the position information regarding the reading start position is the displacement amount of the second information recording layer in step S16 and the address of the second information recording layer corresponding to the end position of the first information recording layer in step S16A. Both of them are for guiding the reading start position when starting reading on the second information recording layer, and various other position information can be considered. For example, if the start position of the second information recording layer is grasped as absolute position information on the disc, the absolute position on the disc at the time when the reading of the end of the first information recording layer is finished. It can be easily derived how much the reading point should be moved from the information to the starting position of the second information recording layer.

In the above description, the example in which the address data obtained from the read signal of the disc is applied as an indication of the recording position of the disc has been described, but basically, other address data can be used instead of the address data. The recording position of the disc may be indicated by the information. Further, in the embodiment, the head address of the second information recording layer is adopted as the target address, but it is not always necessary to adopt the head address as the target address. An address in the vicinity of the start address (for example, address N + 2001 in FIG. 4) may be adopted as the target address as long as it does not hinder the reproduction of information, or an address intentionally far away from the start address. Of course, may be adopted as the target address. In addition, in the embodiment, the recording end of the first information recording layer is adopted as the reading end position of the first information recording layer, but the present invention is not limited to this. After all, if the reproduction of information is not hindered, an address in the vicinity of the recording end (for example, address N-1000 in FIG. 4) may be adopted as the reading end position, or it may be intentionally moved far from the final address. It is also possible to adopt an address separated by a bit as the reading end position.

Although only the optical disc is mentioned as the recording medium, the present invention is not limited to this, and even if the disc is a mixture of optical and magnetic types, it is from the one main surface side. Basically, it can be applied to any multi-layer disc in which recorded information can be read by the irradiated reading light beam.

[0034]

As described in detail above, according to the present invention,
When the reading point moves to a new information recording layer, the reading interruption time can be shortened, and the storage capacity required for the memory used at that time can be reduced. As a result, the continuity of the reproduction information can be maintained with a simple and inexpensive structure.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a recording mode of a multilayer disc applied to the present invention.

FIG. 2 is a block diagram showing the basic configuration of an optical disc recording information reproducing apparatus according to the present invention.

3 is a flowchart showing a processing procedure of initial focus control executed in the apparatus of FIG.

FIG. 4 is a schematic diagram showing the movement of a reading point during a focus jump in the apparatus of FIG.

5 is a flowchart showing a processing procedure of continuous regeneration control executed in the apparatus of FIG.

6 is a graph showing the relationship between the reading operation and the state of the buffer memory in the apparatus shown in FIG.

FIG. 7 is a flowchart showing a modified example of the processing procedure of initial focus control.

FIG. 8 is a flowchart showing a modified example of the processing procedure of continuous reproduction control.

[Explanation of symbols] 1 multi-layer disc 2 spindle motor 3 optical pickup 4 RF amplifier 5 signal demodulation circuit 6 buffer memory 7 decoder 8 error generation circuit 9 pickup control circuit 10 spindle error generation circuit 11 spindle control circuit 11 12 system control circuit 13 display Device 14 operation button

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G11B 21/12 G11B 21/12 F

Claims (10)

[Claims] 1. A method for irradiating a multi-layer disc having at least two information recording layers with a reading light beam from one main surface side thereof to read and reproduce information recorded in each of the information recording layers, A storage step of storing position information regarding a read start position at the start of reading on the other of the information recording layers before the end of reading on one of the information recording layers; Multi-layer disc recording information comprising: a reading layer switching step of switching the reading target of the reading light beam to the other information recording layer and moving the reading light beam in the disc radial direction according to the position information. How to play. 2. The step of detecting, as the position information, a distance in the disc radial direction between a read end position of the first information recording layer and a read start position of the second information recording layer. The method for reproducing information recorded on a multi-layer disc according to claim 1, characterized in that the information is recorded. 3. The reading step includes a step of detecting, as the position information, the position of the second information recording layer having the same disk radial distance as the reading end position of the first information recording layer, In the layer switching process, the distance between the position of the second information recording layer indicated by the position information and the reading start position on the second information recording layer is obtained, and the reading light beam is moved in the disc radial direction in accordance with the distance. The method for reproducing the information recorded on the multilayer disc according to claim 1, wherein the method is to move the information. 4. The method according to claim 1, further comprising a step of searching a reading start position of the second information recording layer after the reading layer switching step.
A method for reproducing the recorded information of the described multilayer disc. 5. The multi-layer disc recording information according to claim 1, wherein the read end position and the read start position are indicated by addresses recorded on the multi-layer disc. How to play. 6. A device for irradiating a multi-layer disc having at least two information recording layers with a reading light beam from one main surface side thereof to read and reproduce information recorded in each of the information recording layers, Rotational driving means for rotationally driving the multi-layer disc, irradiating the multi-layer disc with a read light beam movably in the radial direction thereof, receiving return light from the multi-layer disc, and depending on the received light amount and / or the received light state. Read means for generating a read signal, and a control means for detecting that the reading of any one of the information recording layers is completed based on the read signal. Before the end of reading one of the information recording layers, there is provided storage means for storing position information regarding a reading start position at the time of starting reading on the other of the information recording layers, and the one information recording After the completion of the reading, the reading means is caused to switch the reading target of the reading light beam to the second information recording layer, and the reading light beam is moved in the disk radial direction according to the position information. A multi-layer disc recorded information reproducing apparatus. 7. The storage unit stores the positional information as the position information by detecting a distance in the disc radial direction between a read end position of the one information recording layer and a read start position of the other information recording layer. And after reading the one information recording layer, the reading unit is caused to switch the reading target of the reading light beam to the second information recording layer and the separation distance read from the storage unit. 7. The multi-layer disc recording information reproducing apparatus according to claim 6, wherein said reading means is caused to move said reading light beam in a disc radial direction in accordance with the above. 8. The control means detects the position of the second information recording layer having the same disc radial distance as the reading end position of the first information recording layer, and stores the position information in the storage means. Incidentally, after the reading of the first information recording layer is completed, the reading means is caused to switch the reading target of the reading light beam to the second information recording layer, and the position information read from the storage means is changed. The distance between the position of the information recording layer and the reading start position on the second information recording layer shown is obtained, and the reading means is caused to move the reading light beam in the disc radial direction in accordance with the distance. 7. The reproducing apparatus for reproducing information recorded on a multi-layer disc according to claim 6. 9. The control means issues a search command for a reading start position of the second information recording layer after the movement of the reading light beam, according to claim 6, 7, or 8. Multi-layer disc recording information reproducing apparatus. 10. The multi-layer disc recording information according to claim 6, wherein the read end position and the read start position are indicated by addresses recorded on the multi-layer disc. Playback device.