JPH11167727A - Disk drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize focus jump operation and to accelerate access speed by executing focus search operation only for respective target signal recording surfaces so as to directly arrive at the target signal recording surface. SOLUTION: A tracking servo loop and a focus servo loop are formed by a pickup 1, an RF amplifier 9, a serve processor 14, a biaxial driver 16 and a biaxial mechanism 3. In the state that focus control is not performed even for anyone of plural signal recording surfaces, when recording or reproducing operation of the data for a certain signal recording surface is instructed, the servo processor 14 turns a focus servo off, and moves an objective lens to a lower end position to start the focus search operation. A system controller 10 monitors a focus error signal FE, and turns the focus servo on when the lens arrives within the focus drawing range for the target signal recording surface to start servo operation control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive device capable of performing a reproducing operation or a recording operation for a recording medium such as an optical disk.

[0002]

2. Description of the Related Art As an optical disk recording medium, so-called C
CD-type discs such as D-ROM and DVD (Digital Versatile Disc / Di) suitable for multimedia applications
gitalVideo Disc) has been developed. In a disk drive device corresponding to these optical disks, a disk rotated by a spindle motor is irradiated with laser light from an optical pickup to a track on the disk, and reflected light is detected to detect data. Data is recorded by performing reading or irradiating a laser beam modulated by recording data.

In order to perform a recording or reproducing operation using a laser beam, the spot of the laser beam must be kept in focus on the recording surface of the disc. A focus servo mechanism for controlling a focus state by moving an objective lens, which is an end, in a direction approaching and separating from the disk is mounted.
The focus servo mechanism generally includes a two-axis mechanism having a focus coil for moving the objective lens in the direction of moving toward and away from the disk and a tracking coil for moving the object lens in the radial direction of the disk, and a focusing mechanism based on light reflected from the disk. An error signal (that is, a signal of the amount of deviation from the in-focus state) is generated, a focus drive signal is generated based on the focus error signal, and the focus servo circuit system is applied to the focus coil of the two-axis mechanism. I have. That is, a focus servo mechanism is configured as a feedback control system.

Also, as is well known, the range in which a focus state can be drawn based on a focus error signal is a very narrow range in which an S-shaped curve is observed as a focus error signal. Therefore, in order to execute the focus servo satisfactorily, an operation generally called a focus search is required as an operation for turning on the focus servo loop. In the focus search operation, a focus drive signal is applied to the focus coil so that the objective lens is forcibly moved within the focus stroke range. At this time, when the focus error signal is observed, an S-shaped curve is observed when the position of the objective lens is within a certain range. That S
The focus servo is turned on at a timing (or zero cross timing) at which a linear region of the character curve is obtained.

[0005] Incidentally, some types of disks have a plurality of recording surfaces in a layered structure. For example, in the case of the above DVD, there is a DVD in which two signal recording surfaces generally called layer 0 and layer 1 are formed. FIG. 13 shows the structure of a DVD having two signal recording surfaces. DVD
Is a disc having a diameter of 12 cm, and the thickness of the disc is 1.2 mm as shown in FIG.

[0006] The DVD has a layer structure in which a transparent polycarbonate resin, a polyvinyl chloride resin, an acrylic resin, or the like having a high light transmittance and having mechanical resistance or chemical resistance is provided on the disk surface 108 side. A disk substrate (transparent layer) 101 made of a synthetic resin material is formed. The pits are transferred to one main surface of the disk substrate 101 by a stamper incorporated in a molding die, and a first signal recording surface 102 is formed. The pits on the first signal recording surface 102 are formed on the disk substrate 101 as coded small holes each having a different length in the circumferential direction corresponding to a predetermined information signal, and constitute a recording track. become. Further, a second signal recording surface 104 and a second reflection layer 105 corresponding to the second signal recording surface 104 are formed via a first reflection layer 103 corresponding to the first signal recording surface 102. The pits corresponding to the information signals are also formed on the second signal recording surface 104 similarly to the first signal recording surface 102. The upper surface of the second reflective layer 105 is an adhesive surface 106, through which the dummy plate 107 is adhered.

[0007] Laser light from a disk drive device is incident on the DVD from the disk surface 108 side, and information recorded on the first signal recording surface 102 or the second signal recording surface 104 is detected from the reflected light. Will be done.

That is, the first reflection layer 103 is a translucent film,
It is formed so as to reflect a certain ratio of laser light. As a result, if the laser beam is focused on the first signal recording surface 102, the signal recorded on the first signal recording surface 102 can be read from the light reflected by the first reflection layer 103, and the laser beam can be read by the second signal recording surface. When the laser beam is focused on the surface 104, the laser light passes through the first reflection layer 103 and is focused on the second signal recording surface 104, and the second reflection layer 105
The signal recorded on the second signal recording surface 104 can be read from the light reflected by the optical disc.

For a disk having a plurality of signal recording surfaces such as a DVD having such a two-layer structure, the focus servo mechanism needs to focus a laser beam on each of the signal recording surfaces. In other words, when in focus on one signal recording surface, an operation for shifting to focus on the other signal recording surface, that is, a focus jump operation can be performed. It is necessary. This focus jump operation is performed when the focus servo is turned off and the objective lens is forcibly moved when one of the signal recording surfaces is in focus, and when the objective lens reaches the focus pull-in range for the other signal recording surface (S This is executed by turning on the focus servo at the time when the character curve is observed). That is, the focus is pulled into the other signal recording surface.

[0010]

The focus jump operation has a relatively high probability of failure. That is, when the focus jump is performed so that the focus state on one signal recording surface is changed to the focus state on another signal recording surface, the focus servo pull-in often fails on the other signal recording surface side. . In this case, it is necessary to start over from the focus search.

In general, the focus search is performed only on one signal recording surface even if the disc has a plurality of signal recording surfaces as described above. For example, if the focus search is an operation of detecting an S-shaped curve of a focus error signal and performing focus pull-in while moving the objective lens from a position farthest from the disk, the focus search always performs the first signal recording. Face 10
2 is a focus pull-in operation. Therefore, if the focus jump to move from the first signal recording surface 102 to the second signal recording surface 104 fails, as a retry operation, first, a focus search is performed to perform focus pull-in to the first signal recording surface 102, and thereafter, Subsequently, a procedure for executing a focus jump and moving to the second signal recording surface 104 is required.

Therefore, when the focus jump fails,
A large amount of time is spent for the retry operation, and in any case, since the focus jump with a relatively high probability of failure must be performed again, the possibility of further retry operation is relatively high. It will be. That is, the time required for performing the retry operation when the focus jump has failed becomes long, and the speed of the actual data reading operation or the like is greatly hindered. This causes delays in data output (so-called delays in access time),
In particular, when the data has temporal continuity such as video data or audio data, the output of the video or audio may be interrupted.

[0013]

SUMMARY OF THE INVENTION In view of the foregoing problems, the present invention minimizes the chance of a focus jump and reduces the possibility of delay in processing due to a focus jump failure. In the event that it does occur, be able to quickly recover from the failure. These are intended to stabilize processing and speed up access.

For this reason, the control means in the disk drive device, when the focus control is not performed on any of the signal recording surfaces, the data for a certain signal recording surface of the plurality of signal recording surfaces of the recording medium. When performing the recording or reproducing operation, the focus driving unit is caused to execute a focus search operation for performing a focus pull-in on the signal recording surface. That is, the focus search operation can be performed for each signal recording surface as a target, and the target signal recording surface can be directly reached only by the focus search operation. , It is not necessary to perform a procedure for reaching the target signal recording surface.

[0015] In the disk drive device, when the focus control is performed on a certain signal recording surface and a data recording or reproducing operation is performed on another signal recording surface, the control means performs a focus driving. The means performs a focus jump operation. If the focus jump operation fails, a focus search operation for performing a focus pull-in operation on the other signal recording surface is performed. That is, the focus search operation can be performed for each signal recording surface in the same manner, so that the retry operation when the focus jump operation fails can be achieved by the focus search operation only for the target signal recording surface. By doing
Perform a focus search operation once as a retry operation,
Thereafter, it is not necessary to execute a procedure of performing a focus jump operation to reach a target signal recording surface.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a disk drive apparatus using an optical disk as a recording medium will be described as an embodiment of the present invention. The optical disk loaded in the disk drive device of this example is, for example, a DVD, and particularly considers a disk having a two-layer signal recording surface as described with reference to FIG. Of course, the present invention is applicable to other types of optical discs, and is particularly effective for discs having a layered structure having a plurality of signal recording surfaces.

FIG. 1 is a block diagram of a main part of the disk drive device 70 of the present embodiment. The disk 90 is loaded on the turntable 7, and is rotated at a constant linear velocity (CLV) or a constant angular velocity (CAV) by the spindle motor 1 during a reproducing operation. The pickup 1 reads data recorded on the disk 90 in the form of embossed pits or phase change pits.

In the pickup 1, a laser diode 4 as a laser light source, a photodetector 5 for detecting reflected light, an objective lens 2 as an output end of the laser light,
An optical system is formed which irradiates the laser beam onto the disk recording surface via the objective lens 2 and guides the reflected light to the photodetector 5. The objective lens 2 is held by a biaxial mechanism 3 so as to be movable in a tracking direction and a focus direction. The entire pickup 1 can be moved in the disk radial direction by a thread mechanism 8.

The information on the reflected light from the disk 90 is detected by the photodetector 5, converted into an electric signal corresponding to the amount of received light, and supplied to the RF amplifier 9. The RF amplifier 9 includes a current-voltage conversion circuit, a matrix operation / amplification circuit, and the like corresponding to output currents from a plurality of light receiving elements as the photodetector 5, and generates necessary signals by matrix operation processing. For example, it generates an RF signal as reproduction data, a focus error signal FE for servo control, a tracking error signal TE, and the like. The reproduction RF signal output from the RF amplifier 9 is supplied to a binarization circuit 11, and the focus error signal FE and the tracking error signal TE are supplied to a servo processor 14.

The reproduced RF signal obtained by the RF amplifier 9 is 2
The signal is binarized by the value conversion circuit 11 to be a so-called EFM + signal (8-16 modulated signal), which is supplied to the decoder 12. The decoder 12 performs EFM + demodulation, error correction processing, and the like, and performs MPEG decoding and the like as necessary to reproduce information read from the disk 90.

The decoder 12 stores the decoded data in a cache memory 20 as a data buffer. As the reproduction output from the disk drive device 70, the data buffered in the cache memory 20 is read and transferred and output.

The interface unit 13 is connected to an external host computer 80, and is connected to the host computer 80.
The communication of the reproduction data, the read command, and the like is performed with the communication device.
That is, the reproduction data stored in the cache memory 20 is
The host computer 8 via the interface unit 13
0 is transferred and output. The read command and other signals from the host computer 80 are transmitted to the interface unit 1
3 to the system controller 10.

The servo processor 14 detects various types of focus, tracking, thread, and spindle servo drives based on a focus error signal FE and a tracking error signal TE from the RF amplifier 9 and a spindle error signal SPE from the decoder 12 or the system controller 10. A signal is generated to execute a servo operation. That is, the focus error signal FE and the tracking error signal T
A focus drive signal FD and a tracking drive signal TD are generated according to E and supplied to the biaxial driver 16. The two-axis driver 16 drives the focus coil and the tracking coil of the two-axis mechanism 3 in the pickup 1. As a result, a tracking servo loop and a focus servo loop are formed by the pickup 1, the RF amplifier 9, the servo processor 14, the two-axis driver 16, and the two-axis mechanism 3.

When turning on the focus servo, a focus search operation must first be executed. The focus search operation is performed by the servo processor 14.
Generates a required focus drive signal FD when the focus servo is off, and forcibly moves the objective lens 2. Then, during the movement process, the focus error signal FE
The position where the S-shaped curve is obtained is detected. As is well known, the linear region of the S-shaped curve of the focus error signal is a range in which the position of the objective lens 2 can be drawn to the in-focus position by closing the focus servo loop. Therefore, while the objective lens 2 is forcibly moved as a focus search operation, the above-described retractable range is detected, and the focus servo is turned on at that timing, so that the laser spot is kept in focus thereafter. The focus servo operation is realized.

In the case of the present embodiment, the signal recording surface of the disc 90 has a first signal recording surface 90a and a second signal recording surface 90a as shown in FIGS.
It has a two-layer structure as shown as the signal recording surface 90b. That is, the structure has been described with reference to FIG. As a matter of course, when performing recording and reproduction on the first signal recording surface 90a, the laser beam must be in focus on the first signal recording surface 90a. Also, the second signal recording surface 90b
When performing recording / reproducing with respect to the laser beam, the laser beam must be in focus on the second signal recording surface 90b. FIG. 2 shows a focused state on the first signal recording surface 90a.
As shown in (a), the position of the objective lens 2 at this time is assumed to be a position P1. FIG. 2B shows a focused state on the second signal recording surface 90b. Assume that the position of the objective lens 2 at this time is a position P2. Note that the positions P0 to P
Let 3 be a focus stroke range in which the objective lens 2 can move in the direction in which the objective lens 2 comes into contact with or separates from the disk 90.

For example, when the reproduction operation on the second signal recording surface 90b is performed after the reproduction operation on the first signal recording surface 90a, the position of the objective lens 90 is changed from the position P1 to the position P.
You have to move to 2. Of course, the reverse is also possible. The movement of the focus position on the first signal recording surface 90a and the second signal recording surface 90b is performed by a focus jump operation. As described above, this focus jump operation is performed when the focus servo is turned off and the objective lens 2 is in focus when one of the signal recording surfaces is in focus.
Is forcibly moved, and the focus servo is turned on when the focus servo reaches the focus pull-in range with respect to the other signal recording surface (when the S-shaped curve is observed).

FIG. 3 shows an example of the focus error signal FE observed when the objective lens 2 is moved within the focus stroke range from the positions P0 to P3. As shown in the figure, an S-shaped curve is observed around the positions P1 and P2 at which the first signal recording surface 90a and the second signal recording surface 90b are in focus. The position range of the linear region of each S-shaped curve is the focus pull-in possible range FW1, FW2 for each signal recording surface.

Further, in this embodiment, the above-mentioned focus search operation for the disc 90 having the signal recording surface of the two-layer structure as shown in FIG. 2 includes the operation of performing the focus pull-in for the first signal recording surface 90a. , Second signal recording surface 9
The operation of performing focus pull-in for the purpose of 0b can be selectively executed. This operation will be described later in detail.

The above-described operations of focus servo, focus search, and focus jump are executed by the system controller 10 giving instructions to the servo processor 14. In order for the system controller 10 to perform these focus operation controls, the focus error signal FE
Must be monitored, so that the focus error signal FE from the RF amplifier 9 is
0 is also supplied.

The S-shaped curve is observed in the focus error signal FE when an appropriate amount of reflected light is obtained by the detector 5. At this time, the level is large as a so-called sum signal of the amount of reflected light. Become. The output of comparing this sum signal with a predetermined threshold level is
It is a so-called FOK signal indicating the section of the S-shaped curve,
The system controller 10 may monitor the FOK signal in a processing example described later. For example, the zero-cross point of the focus error signal refers to a zero-cross point in the S-shaped curve. However, as can be seen from the waveform of FIG. 3, the focus error signal FE is located outside of the S-shaped curve area where reflected light is not properly obtained. Becomes almost zero level, and even if the focus error signal is simply compared with the zero level during the movement of the objective lens, the zero cross point in the S-shaped curve area may not be detected accurately. Therefore, in order to eliminate zero crossings outside the S-shaped curve region, it is conceivable to perform zero cross detection using the FOK signal as a window.

In FIG. 1, the servo processor 14 further supplies a spindle drive signal generated according to the spindle error signal SPE to the spindle motor driver 17. The spindle motor driver 17 applies, for example, a three-phase drive signal to the spindle motor 6 according to the spindle drive signal, and the CL of the spindle motor 6
Execute V rotation. In addition, the servo processor 14 generates a spindle drive signal in response to a spindle kick / brake control signal from the system controller 10, and causes the spindle motor driver 17 to execute operations such as starting, stopping, accelerating, and decelerating the spindle motor 6.

The linear velocity as CLV rotation of the spindle motor 6 can be set to various speeds by the system controller 10. For example, the decoder 12 generates a reproduction clock synchronized with the EFM signal for use in the decoding process, and can obtain current rotation speed information from the reproduction clock. The system controller 10 or the decoder 12 generates a spindle error signal SPE for CLV servo by comparing such current rotational speed information with reference speed information. Therefore,
The system controller 11 can change the linear velocity as the CLV rotation by switching the value as the reference velocity information. For example, linear speeds such as 4 × speed and 8 × speed can be realized based on a certain normal linear speed. As a result, the data transfer rate can be increased. It should be noted that the rotation speed can be switched even in the CAV method.

The servo processor 14 generates a thread drive signal based on, for example, a thread error signal obtained as a low-frequency component of the tracking error signal TE or an access execution control from the system controller 10 and supplies the thread drive signal to the thread driver 15. . The thread driver 15 responds to the thread drive signal by the thread mechanism 8.
Drive. Although not shown in the thread mechanism 8, a main shaft for holding the pickup 1, a thread motor,
The pickup 1 has a required sliding movement by having a mechanism such as a transmission gear and driving the sled motor 8 by the sled driver 15 according to the sled drive signal.

The laser diode 4 in the pickup 1 is driven by a laser driver 18 to emit laser light. The system controller 10 sets the control value of the laser power in the auto power control circuit 19 when executing the reproducing operation on the disc 90, and the auto power control circuit 19 performs the laser output according to the set laser power value. The laser driver 18 is controlled so as to be operated.

When the apparatus is capable of performing a recording operation, a signal modulated according to recording data is applied to the laser driver 18. For example, when recording is performed on a recordable type disc 90, the recording data supplied from the host computer to the interface unit 13 is added with an error correction code by an encoder (not shown),
After processing such as EFM + modulation is performed, the data is supplied to the laser driver 18. Then, the laser driver 18 causes the laser diode 4 to perform a laser emission operation according to the recording data, so that data recording on the disk 90 is performed.

The above-described various operations such as servo, decoding, and encoding are controlled by a system controller 10 formed by a microcomputer.
Then, the system controller 10 executes various processes in response to a command from the host computer 80. For example, when a read command requesting transfer of certain data recorded on the disk 90 is supplied from the host computer 80, first, seek operation control is performed for the designated address. That is, a command is issued to the servo processor 14 to execute the access operation of the pickup 1 targeting the address specified by the seek command. Thereafter, operation control necessary for transferring the data in the specified data section to the host computer 80 is performed. That is, data reading / decoding / buffering from the disk 90 is performed, and the requested data is transferred. If the data request from the host computer is made sequentially and the requested data is stored in the cache memory 20 in advance by, for example, a prefetch operation, the data read / write from the disk 90 is performed as a cache hit transfer. Requested data can be transferred without performing decoding / buffering.

In this example, the system controller 1
0 means that the reproduction and transfer operations are performed in response to the read command from the host computer 80, that is, the disk access is executed when the read command is supplied. When the disk drive device 70 is in an accessible state, that is, in a state of waiting for a read command from the host computer 80,
The rotation of the spindle motor 6 and each servo control are executed. This is to make it possible to immediately read data when a read command is generated, and to perform quick data transfer processing to the host computer 80. Considering the focus servo, when waiting for a read command in the drive state as described above, or when actually reading data, the first signal recording surface 90a and the second signal recording surface The in-focus state is maintained for any one of 90b. In the following description, such a state in which focus servo is applied to a certain signal recording surface is referred to as a “non-pause state”.

However, waiting for a read command in the drive state as described above results in power consumption loss if the read command is not generated for a long time, and therefore, the standby state in the drive state for a very long time. Is not preferred. Therefore, when the standby state has elapsed for a predetermined time or more, the drive of the spindle motor 6 is turned off, and each servo operation and laser output are also turned off. For example, a state in which focus servo is not applied to either the first signal recording surface 90a or the second signal recording surface 90b of the disk 90 as in such a case is referred to as a "pause state" for explanation.

The operation in the case where a read command is generated during the sleep state and the operation in the case where the read command is generated during the non-sleep state will be sequentially described below.

First, referring to FIG. 4 to FIG. 8, an operation mainly related to focus control will be described as an operation in the case where a read command is generated in the pause state. FIGS. 4, 5, and 7 show the processing of the system controller 10 when a read command is generated in the sleep state. FIGS. 6 and 8 show examples of a focus error signal FE and a focus drive signal FD given to the two-axis driver 16 by the servo processor 14 at the time of focus search from the pause state.

In the idle state, the host computer 80
When a read command is supplied from the system controller 10, the processing of the system controller 10 first proceeds from steps F101 to F1 in FIG.
In step 02, the rotational drive of the spindle motor 6 is started. That is, an instruction is issued to the servo processor 14 to start the rotation of the spindle motor 6 by the spindle motor driver 17 and the spindle servo operation is performed.
A settling process to a predetermined rotation speed as LV or CAV is executed.

Subsequently, the focus servo is pulled in. Here, in step F103, the operation of reproducing the data requested by the read command is performed on the disk 9.
It is determined whether the reproduction operation is for the first signal recording surface 90a or the second signal recording surface 90b. Then, in the case of a reproduction operation relating to the first signal recording surface 90a, the process proceeds to step F104, and a focus search for the purpose of focusing on the first signal recording surface 90a is performed. On the other hand, if the reproducing operation is related to the second signal recording surface 90b, the process proceeds to step F105, where a focus search for the purpose of focusing on the second signal recording surface 90b is performed.

The focus search process for the first signal recording surface 90a as step F104 is shown in detail in FIG. 5, and the signal waveform at that time is as shown in FIG.
First, as Step F110 in FIG. 5, the objective lens 2 is moved to the lower end position within the focus stroke range (position P0 in FIG. 2).
Move to This is a process in which the servo processor 14 applies the focus drive signal FD to the two-axis driver 16 during the period from t0 to t1 in FIG. When the biaxial mechanism 3 is driven by such a focus drive signal FD, the objective lens 2 is moved to the lower end position at time t1. Subsequently, in step F111, an instruction is given to the APC circuit 19 to start the laser output from the laser diode 4.

In step F112, the objective lens 2 is moved as a focus search operation, that is, an operation of moving the objective lens 2 toward the disk 90 within the focus stroke is executed. This is the servo processor 14
Thus, the process is to apply the focus drive signal FD to the two-axis driver 16 after time t1 in FIG. The biaxial mechanism 3 is driven by the focus drive signal FD, and the objective lens 2 is forcibly brought closer to the disk 90. During the period in which the objective lens 2 is moving, the system controller 10 detects the timing at which the S-shaped curve is observed as the focus error signal FE in step F113. That is, as the objective lens 2 moves in a direction approaching the disk 90, an S-shaped curve with respect to the first signal recording surface 90a is seen from a certain point in the focus error signal FE. It detects the timing. The start timing of the S-shaped curve can be detected, for example, by comparing the focus error signal FE with a predetermined level close to zero level.

In the case of FIG. 6, the time point t2 is the time at step F113.
Is the timing at which the start of the S-shaped curve is detected. From this point, the processing of the system controller 10 proceeds to step F114. Then, at time t3, a zero-cross of the focus error signal is detected. This zero-cross detection timing is within the focus pull-in range with respect to the first signal recording surface 90a. Therefore, by turning on the focus servo loop at the zero-cross detection timing as the process of step F114, the first signal recording surface 90a
, The focus servo for the first signal recording surface 90a is maintained by the focus servo operation. That is, the focus search for the first signal recording surface 90a is completed.

When the focus search / focus servo ON in step F104 of FIG. 4 is completed, the tracking servo and the thread servo are turned on in step F106. At this point, data can be read from the first signal recording surface 90a of the disk 90, and processing corresponding to the read command is performed in step F107. That is, as an operation control corresponding to the read command, a disk access (a seek operation of the pickup 1 to a data position to be read) in the first signal recording surface 90a is executed, a data reading and decoding process is executed, and further decoding is performed. The stored data is stored in the cache memory 20. Then, necessary data is read from the cache memory 20 and transferred to the host computer 80 via the interface unit 13 for output. By performing the above process, a series of processes associated with the read command is completed, and the process returns to the read command standby state.

On the other hand, if it is determined in step F103 that the data to be read is the data on the second signal recording surface 90b, a focus search process is performed on the second signal recording surface 90b in step F105. This process is shown in detail in FIG. 7, and the signal waveform at that time is as shown in FIG. First, step F1 in FIG.
At step 20, the objective lens 2 is moved to the lower end position (the position P0 in FIG. 2) within the focus stroke. That is, the servo processor 14 sends the t1 of FIG.
The focus drive signal FD is applied as in the period from 0 to t11. When the biaxial mechanism 3 is driven by the focus drive signal FD, the objective lens 2 moves to t11.
At this point, it is moved to the lower end position. Subsequently, Step F121
To instruct the APC circuit 19 to start the laser output from the laser diode 4.

In step F122, the objective lens 2 is moved as a focus search operation, that is, an operation of moving the objective lens 2 toward the disk 90 within the focus stroke is executed. This is the servo processor 14
Then, the process is to apply the focus drive signal FD to the two-axis driver 16 after the time t11 in FIG. The biaxial mechanism 3 is driven by the focus drive signal FD, and the objective lens 2 is forcibly moved to the disk 90.
To be approached. The operation up to this point is the same as the focus search operation of FIG.

During the period during which the objective lens 2 is being moved after time t11, the system controller 10 detects the timing at which the S-shaped curve is observed as the focus error signal FE in step F123. That is, as the objective lens 2 moves in the direction approaching the disk 90, an S-shaped curve with respect to the first signal recording surface 90a appears at a certain point in the focus error signal FE. It detects the timing.

In the case of FIG. 8, the timing after the time t12 is the detection timing of the S-shaped curve, which is detected in step F123. From this point, the process of the system controller 10 proceeds to Step F124. And this step F
At 124, the next S
It monitors the timing at which the curve is observed.

The S-shaped curve detected from the time t12 in the process of step F123 is an S-shaped curve obtained for the first signal recording surface 90a. In F124, it waits for the next S-shaped curve detection timing. For example, in FIG. 8, the next S-shaped curve is observed at time t13, but this is an S-shaped curve for the second signal recording surface 90b.

When the start timing of the second S-shaped curve is detected in step F124, the processing is performed in step F12.
Proceed to 5. At time t14, a zero-cross of the focus error signal is detected. The zero-cross detection timing is within the focus pull-in range for the second signal recording surface 90b. Accordingly, by turning on the focus servo loop at the zero-cross detection timing as the process of step F125, the focus servo for the second signal recording surface 90b is favorably pulled in, and the focus state on the second signal recording surface 90b is thereafter performed by the focus servo operation. Will be maintained. That is, the second signal recording surface 90b
The focus search for the purpose is completed.

When the focus search / focus servo on at step F105 in FIG. 4 is completed, the tracking servo and the thread servo are turned on at step F106. At this point, data can be read from the second signal recording surface 90b of the disk 90, and processing corresponding to the read command is performed in step F107. That is, as an operation control corresponding to the read command, a disk access (a seek operation of the pickup 1 to a data position to be read) in the second signal recording surface 90b is executed, a data reading and decoding process is executed, and further decoding is performed. The stored data is stored in the cache memory 20. Then, necessary data is read from the cache memory 20 and transferred to the host computer 80 via the interface unit 13 for output. By performing the above process, a series of processes associated with the read command is completed, and the process returns to the read command standby state.

As described above with reference to FIGS. 4 to 8, when a read command is issued in the pause state, the disk drive device 70 performs the direct focus search on the signal recording surface from which data is to be read by the focus search. I do. Therefore, there is no need to perform a focus search on a certain signal recording surface and then perform a focus jump to move the signal recording surface, and data can be read out quickly. In addition, it is not necessary to perform a focus jump with a relatively high probability of failure, which is advantageous for speeding up and stabilizing the operation.

Next, as an operation when a read command is issued in the non-pause state, an operation mainly related to focus control will be described with reference to FIGS. 9 to 12 show the processing of the system controller 10 when a read command is issued in the non-pause state.

When a read command is supplied from the host computer 80 in a non-pause state, that is, a state in which focus servo is applied to one signal recording surface, the processing of the system controller 10 first proceeds to step F20 in FIG.
The process proceeds from 1 to F202, and it is determined whether or not a focus jump is necessary. This is to determine whether or not the signal recording surface on which the pickup 1 is currently in the read or read pause state matches the signal recording surface on which the data requested by the host computer 80 is recorded. If they match, the operation required for the read command is the read operation on the current signal recording surface, and no particular focus jump is required. Therefore, the process proceeds to step F209 to execute a command corresponding process. That is, seek / data reading / decoding / buffering / transfer is performed. Then, the operation returns to the read command standby state.

However, if data on a signal recording surface different from the current signal recording surface is requested, it is determined in step F202 that a focus jump is necessary, and step F203 is performed.
To execute the focus jump operation. The processing as the focus jump in step F203 is, for example, as shown in FIG.

First, as step F220, control is performed to turn off the focus servo that has been applied. That is, an instruction is given to the servo processor 14 to open the focus servo loop. Then, in step F221, the system controller 10 causes the biaxial driver 16 to apply a kick voltage in the focus jump direction. For example, in the case of a jump from the first signal recording surface 90a to the second signal recording surface 90b, a kick voltage for moving the objective lens 2 in a direction approaching the disk 90 is applied, while the first signal is transmitted from the second signal recording surface 90b. In the case of a jump to the recording surface 90a, a kick voltage for moving the objective lens 2 in a direction away from the disk 90 is applied.

For example, the focus jump from the first signal recording surface 90a to the second signal recording surface 90b will be described as an example. By applying the kick voltage as described above, the objective lens 2 moves in the direction approaching the disk 90. Will be done. Here, the system controller 11 executes step F22.
In step 2, the zero crossing of the focus error signal FE is monitored. The zero-cross timing waiting in step F222 is a timing at which the objective lens 2 leaves the position range where the S-shaped curve with respect to the first signal recording surface 90a is observed.

When this timing is detected, the system controller 10 turns off the focus drive voltage in the process of step F223. Therefore, the objective lens 2 thereafter moves in the direction approaching the disk 90 due to inertia. In this state, in step F224, the system controller 10 waits for the timing at which the next S-shaped curve starts to be observed. That is, as the objective lens 2 moves, an S-shaped curve with respect to the second signal recording surface 90b is seen from a certain point in the focus error signal FE, and the start timing is detected. is there.

When the start timing of the S-shaped curve is detected, the biaxial driver 16 is caused to apply a brake voltage in step F225. The brake voltage is a kick voltage in the direction opposite to the focus jump direction,
In this case, the kick voltage is in the direction away from the disk 90. However, at the time when the brake voltage is applied, the objective lens 2 is moving in the direction approaching the disk 90.
Appears as a decrease in the moving speed in the direction approaching the disk 90. Therefore, thereafter, the moving speed of the objective lens 2 decreases, but approaches the disk 90 as before.

The application of the brake voltage in step F225 is the time when the S-shaped curve with respect to the second signal recording surface 90b starts to be observed. Therefore, the movement of the objective lens 2 continues even though the speed is reduced. As a result, a zero-cross of the focus error signal is detected at a certain point thereafter. This zero-cross detection is performed in step F2.
26 is performed. The positions of the objective lens 2 before and after the detection of the zero cross correspond to positions before and after the position P2 in FIG.
That is, it is within the focus pull-in range for the second signal recording surface 90b. Therefore, the process proceeds to step F227 to turn on the focus servo loop, whereby the focus servo for the second signal recording surface 90b is pulled in, and thereafter the second signal recording surface 9b is operated by the focus servo operation.
The in-focus state for 0b is maintained. Thus, for example, the first signal recording surface 90a to the second signal recording surface 9
The focus jump to 0b is completed. Of course the second
The focus jump operation from the signal recording surface 90b to the first signal recording surface 90a is also completed by the same processing, although the moving direction of the objective lens 2 is reversed.

When the focus jump in step F203 of FIG. 9 is properly completed by the processing as shown in FIG. 10, and the focus jump is determined to be successful in step F204, the process proceeds to step F208, where the tracking servo and the thread servo are turned on. I do. Then, the process proceeds to step F209, where seek / data reading /
Perform decoding / buffering / transfer. Then, the operation returns to the read command standby state.

However, if the focus jump in step F203 was not successful, that is, if the focus could not be pulled in on the signal recording surface of the movement destination, the process proceeds to step F205 as retry processing. However, the processing after step F205 does not retry the focus jump, but performs a direct focus search on the signal recording surface that was the object of the focus jump in step F203.

That is, in step F205, it is determined whether the signal recording surface on which data reproduction requested by the read command is performed (that is, the signal recording surface on which the focus jump has failed) is the first signal recording surface 90a or the second signal recording surface 90b. If it is determined that the first signal recording surface 90a is present, step F2
Proceeding to 06, a focus search for the purpose of focusing on the first signal recording surface 90a is performed. On the other hand, if it is the second signal recording surface 90b, the process proceeds to step F207 to perform a focus search for the purpose of focusing on the second signal recording surface 90b.

The focus search process for the first signal recording surface 90a as step F206 is shown in detail in FIG. The processing in FIG. 11 is the same as the focus search in FIG. 5 except that the laser emission start processing shown as step F111 in FIG. 5 is not performed. The signal waveform is as shown in FIG. That is, the objective lens 2 is moved to the lower end position (the position P0 in FIG. 2) within the focus stroke in step F230 of FIG. 11, and the movement of the objective lens 2 as a focus search operation, that is, the disk 90 is moved in the focus stroke in step F231. An operation of moving in the direction approaching is performed.
In step F232, the timing at which the S-shaped curve of the focus error signal FE is observed is detected.
When the start of the character curve is detected, the focus servo loop is turned on at the zero cross detection timing in step F233. By the above processing, the first signal recording surface 90a
The focus search for the purpose is completed.

When the focus search / focus servo on as step F206 in FIG. 9 is completed, the tracking servo and the thread servo are turned on in step F208. Proceeding to step F209, seek / data read / decode / buffering / transfer is performed as command corresponding processing. Then, the operation returns to the read command standby state.

On the other hand, if it is determined in step F205 that the target signal recording surface is the second signal recording surface 90b, the focus search for the second signal recording surface 90b as shown in FIG. Processing is performed. The processing in FIG. 12 is the same as the focus search in FIG. 7 except that the laser emission start processing shown as step F121 in FIG. 7 is not performed. The signal waveform is as shown in FIG.

That is, in step F240 of FIG. 12, the objective lens 2 is moved to the lower end position within the focus stroke, and then in step F241, the objective lens 2 is moved as a focus search operation, that is, moved in the direction approaching the disk 90. The action to be performed is executed. Then, in step F242, the timing at which the S-shaped curve is observed as the focus error signal FE is detected.
If an S-shaped curve with respect to the first signal recording surface 90a is detected in step F242, the processing is performed in step F243.
The timing at which the next S-shaped curve is observed as the focus error signal FE is detected. Step F24
Since the S-shaped curve detected in Step 3 is an S-shaped curve for the second signal recording surface 90b, when the S-shaped curve is detected, the focus servo loop is turned on at the zero cross detection timing in Step F244. This completes the focus search for the second signal recording surface 90b. When the focus search / focus servo on as step F207 in FIG. 9 is completed, the tracking servo and the thread servo are turned on in step F208. Proceeding to step F209, seek / data read / decode / buffering / transfer is performed as command corresponding processing. Then, the operation returns to the read command standby state.

As described above with reference to FIGS. 9 to 12, when a read command is issued in the non-pause state, the disk drive 70 first performs a focus jump if the signal recording surface needs to be moved. Execute. However, when the focus jump has failed, the retry processing is such that the focus search is directly performed on the target signal recording surface. Therefore, there is no need to perform a focus search on a certain signal recording surface as a retry operation and then perform a focus jump to move the signal recording surface, and the data read can be executed after the retry operation is completed quickly. Further, it is not necessary to perform a focus jump with a relatively high probability of failure as a retry operation, which is advantageous for speeding up and stabilizing the operation.

In the above operation example, the focus search moves the objective lens 2 from the lower end position (the position P0 in FIG. 2) toward the disk 90. However, the focus search starts from the upper end position (the position P3 in FIG. 2). An operation method of moving the disk in a direction away from the disk 90 is also conceivable. In this case, the operation of performing the focus pull-in within the first observed S-shaped curve becomes a focus search for the second signal recording surface 90b, and the operation of performing the focus pull-in within the second observed S-shaped curve is the first. This is a focus search for the signal recording surface 90a.

Although the embodiment has been described with reference to a DVD in which the disc 90 has a two-layered signal recording surface, for example, other types of discs having a two-layered structure, and signals of three or more layers are used. The present invention can also be applied to a disk or the like having a recording surface.

[0073]

As described above, according to the present invention, when focus control is not performed on any of the signal recording surfaces of a recording medium having a plurality of signal recording surfaces, data for a certain signal recording surface is not recorded. When a recording or reproducing operation is performed, a focus search operation for performing a focus pull-in on a target signal recording surface is performed. That is, the focus search operation can be performed for each signal recording surface, so that the target signal recording surface can be reached only by the focus search operation. Therefore, when performing a recording or reproducing operation on any signal recording surface, it is not necessary to perform a focus search operation and then perform a focus jump operation to perform a procedure for reaching a target signal recording surface, which is quick. Then, the recording or reproducing operation can be executed by performing focus control on the target signal recording surface. Thus, there is an effect that the operation as a disk drive device can be speeded up and stabilized. For example, it is possible to realize a high-speed access operation in response to a request from the host computer.

Further, according to the present invention, while focus control is performed on a certain signal recording surface of a recording medium having a plurality of signal recording surfaces, data recording or reproducing operation is performed on another signal recording surface. In such a case, a focus jump operation is performed. If the focus jump operation fails, a focus search operation for performing a focus pull-in operation on the other signal recording surface is performed. That is, by enabling the focus search operation to be performed for each signal recording surface, the retry operation when the focus jump operation has failed can be reached by the focus search operation alone. . As a result, the operation time of the retry process can be shortened, and the operation and speed of the disk drive device can be speeded up and stabilized. For example, when data that requires temporal continuity, such as video data and audio data, is reproduced, it is possible to prevent output data from being interrupted due to processing delay.

[Brief description of the drawings]

FIG. 1 is a block diagram of a disk drive device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a focus jump operation according to the embodiment.

FIG. 3 is an explanatory diagram of an S-shaped curve of a focus error signal according to the embodiment.

FIG. 4 is a flowchart of focus control on a certain signal recording surface from a pause state according to the embodiment;

FIG. 5 is a flowchart of a focus servo pull-in process for a first signal recording surface according to the embodiment;

FIG. 6 is an explanatory diagram of a focus servo pull-in process for a first signal recording surface according to the embodiment;

FIG. 7 is a flowchart of focus servo pull-in processing for a second signal recording surface according to the embodiment;

FIG. 8 is an explanatory diagram of a focus servo pull-in process for a second signal recording surface according to the embodiment;

FIG. 9 is a flowchart of focus control on a certain signal recording surface from a non-pause state according to the embodiment;

FIG. 10 is a flowchart of a focus jump operation according to the embodiment.

FIG. 11 is a flowchart of a focus servo pull-in process for a first signal recording surface according to the embodiment;

FIG. 12 is a flowchart of focus servo pull-in processing for a second signal recording surface according to the embodiment.

FIG. 13 is an explanatory diagram of a layer structure of a DVD.

[Explanation of symbols]

1 pickup, 2 objective lens, 2 biaxial mechanism, 4
Laser diode, 5 photo detector, 6 spindle motor, 8 thread mechanism, 9 RF amplifier, 1
0 system controller, 13 interface unit, 14 servo processor, 20 cache memory, 70 disk drive device, 80 host computer, 90 disk,

Claims (2)

[Claims] 1. A disk drive device for recording or reproducing data by irradiating a laser beam onto a signal recording surface of a recording medium having a plurality of signal recording surfaces having a layer structure, comprising: a laser light source; An objective lens serving as an output end of the laser light, a pickup unit having a detection unit for detecting reflected light from the recording medium, and a signal recording surface of the recording medium by moving the objective lens in a direction of coming and coming from the recording medium. An objective lens moving means for setting a focus state of the laser beam with respect to the target lens; and a focus pull-in for each signal recording surface of the recording medium by turning on a focus servo at a predetermined timing while moving the objective lens by the objective lens moving means. Performing a focus search operation and generating a focus error signal from information obtained by the detection unit. A focus servo operation for moving the objective lens by the objective lens moving means based on a focus error signal so as to keep the laser beam in focus on a certain signal recording surface; Focus driving means capable of executing a focus jump operation of moving the objective lens by the objective lens moving means so as to shift from a focused state to a focused state for another signal recording surface; Even when the focus control is not being performed, when data recording or reproducing operation is performed on a certain signal recording surface of the plurality of signal recording surfaces of the recording medium, the focus driving unit is provided with the signal recording surface. And control means for executing a focus search operation for performing focus pull-in for Disk drive device. 2. A disk drive for recording or reproducing data by irradiating a laser beam onto a signal recording surface of a recording medium having a plurality of signal recording surfaces having a layer structure, comprising: a laser light source; An objective lens serving as an output end of the laser light, a pickup unit having a detection unit for detecting reflected light from the recording medium, and a signal recording surface of the recording medium by moving the objective lens in a direction of coming and coming from the recording medium. An objective lens moving means for setting a focus state of the laser beam with respect to the target lens; and a focus pull-in for each signal recording surface of the recording medium by turning on a focus servo at a predetermined timing while moving the objective lens by the objective lens moving means. Performing a focus search operation and generating a focus error signal from information obtained by the detection unit. A focus servo operation for moving the objective lens by the objective lens moving means based on a focus error signal so as to keep the laser beam in focus on a certain signal recording surface; A focus driving unit capable of executing a focus jump operation of moving the objective lens by the objective lens moving unit so as to shift from a focused state to a focused state on another signal recording surface; In the state where the focus control is being performed, when performing the data recording or reproducing operation on another signal recording surface, the focus driving unit performs the focus jump operation, and when the focus jump operation fails, Is a focus search operation for performing focus pull-in on the other signal recording surface. A disk drive device, comprising: control means for executing an operation.