JP2002245641A - Optical disk drive and track jump control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actualize stable seek operation even for an optical disk which has no frame synchronism. SOLUTION: A photodetecting element output processing part of an optical disk drive 1 uses the value computed from (A+D)-(B+C) by using light intensity values A, B, and C detected on the surface of the photodetecting element for detecting the lens shift by a 1-beam method and also uses a side push-pull signal represented as ((F+H)-(E+G)) by using light intensity values E, F, G, and H or the sum component (A+D)-(B+C)+k (F+H)-(E+G)} of a main push-pull signal and the side push-pull signal for detecting the lens shift quantity by a 3-beam method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical disk apparatus and a track jump control method, and more particularly, to an optical disk apparatus and a track jump control method for stably seeking an optical disk having no frame sync.

[0002]

2. Description of the Related Art A so-called CD to which optical reading is applied.
(Compact Disc) and other disc-shaped recording media
Recorded as an optical disk. ) Has a large storage capacity and allows random access. In addition, since optical reading is non-contact, there is no danger such as head crash or wear and damage due to reading as compared with a contact type recording medium such as a magnetic tape. Also, because the disc surface is sturdy,
There is less danger of accidental data loss. An optical disk having many advantages as described above is a recording medium that is excellent in data production and data storage as a memory around a computer.

In a general seek operation on an optical disc, when a track is turned on after a track jump, address data such as time information recorded in the track is read, and a difference between a target address and a current address at which the track is turned on is read. The track jump operation is repeated until the target address is reached so that no error occurs. The state where the converged laser light is track-on is a state where the laser optical axis passes through the center of the objective lens of the optical pickup.
At this time, the optical disk is normally read.

However, due to the instability of the actuator operation after the track jump or the delay of the followability of the feed motor, the track is turned on even when the optical axis passes a position off the center of the lens (servo is applied). ) In some cases. FIG. 4A shows that the laser optical axis 51 is
5 schematically shows a state where the track 52 is correctly turned on with respect to the track 52 after passing through the lens center 54 of FIG. Also,
FIG. 4B schematically shows a state where the track 52 is turned on with respect to the track 52 even though the laser optical axis 51 is off the lens center 54 of the objective lens 50.

In FIG. 4B, the actuator is displaced in the tracking direction from a position where the objective lens 50 has no external force or no voltage applied to the actuator.
If a further track jump is performed in this state, the displacement of the suspension 53 becomes the offset of the jump, and the landing point (track-on position) of the jump may be shifted. If this displacement is accumulated for each jump, there is a problem that the arrival at the target address is delayed.

Particularly, in the conventional seek operation, the offset is from 100 tracks to 200 tracks or more (0.2 to 200 tracks).
Equivalent to 0.3 millimeter. ) May be off,
There is a problem that the target address cannot be reached if the target track is significantly deviated from the target track.

As a countermeasure for avoiding this adverse effect, a conventional optical pickup in an optical disk apparatus uses a frame sync signal included in a track signal as a criterion when a track is normally turned on.
For example, when the frame sync signal cannot be detected a predetermined number of times, it is determined that the tracking is abnormal, and a transition to the next track jump is waited until the signal becomes stable, or a process of once turning off the track and then turning on the track again is performed. I was going.

[0008]

However, since the frame sync is recorded together with the recording data, the CD-R (Compact Disc-Recordable) is one of the optical recording media.
e), a disc having an unrecorded portion, such as a CD-RW (Compact Disc-ReWritable), has no frame sync recorded. Therefore, in the seek operation of determining the tracking state using the frame sync, tracking cannot be performed normally.

The present invention has been proposed in view of such a conventional situation, and an object of the present invention is to provide an optical disk apparatus and a track jump control method that realize a stable seek operation even on an optical disk without a frame sync. And

[0010]

In order to achieve the above-mentioned object, an optical disk apparatus according to the present invention comprises a converging means for converging and irradiating a light beam on an optical disk, a reflected light or a transmitted light of the converged light beam from the optical disk. A light amount detecting means for detecting a light amount, an optical axis shift detecting means for detecting a shift of an optical axis of the light beam with respect to the converging means, and a control means for controlling a track jump according to a detection result in the optical axis shift detecting means .

Further, in the optical disk apparatus according to the present invention, the optical axis shift detecting means detects a shift of the optical axis from a push-pull signal obtained from a signal from the light quantity detecting means.

[0012] Such an optical disk device controls a track jump in accordance with the detection result of the optical axis shift detecting means for detecting the shift of the optical axis of the light beam with respect to the converging means.

In order to achieve the above object, a track jump control method according to the present invention comprises: a light amount detecting step of detecting a reflected light or a transmitted light amount of a light beam convergently applied to the optical disk from the optical disk; An optical axis deviation detecting step of detecting an axis deviation and a control step of controlling a track jump according to a detection result in the optical axis deviation detecting step are provided.

Further, in the optical axis shift detecting step, the shift of the optical axis is detected from a push-pull signal obtained from the signal from the light quantity detecting step.

According to such a track jump control method, the track jump is controlled in accordance with the detection result in the optical axis shift detecting step for detecting the shift of the optical axis of the light beam.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk apparatus shown as one configuration example of the present invention detects a reflected light or a transmitted light amount of a light beam convergently applied to the optical disk from the optical disk, and an optical axis shift detecting means detects a light beam for the converging means. By detecting the shift of the optical axis of the beam, that is, the lens shift, and controlling the track jump according to the lens shift amount detected by the optical axis shift detecting means, it is possible to normally track an optical disc without a frame sync. It is an optical disk device that can be used.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. An optical disk device 1 shown in FIG. 1 is a device that optically reads data recorded on an optical recording medium having a disk shape. The optical disk used here is a CD-ROM, DVD (Digital
Versatile Disc) and other optical recording media and magneto-optical recording media. The optical disc device 1 is particularly suitably used for a write-once optical recording medium, a rewritable optical recording medium, a magneto-optical recording medium, or the like having an unrecorded area where no frame sync is recorded.

As a reading method for reading information recorded as recording pits on an optical disk in the optical disk apparatus 1, a one-beam method (push-pull method) for reading with one laser beam, a three-beam method for reading with three laser lights, and the like are known. Have been.

FIG. 2A shows a pit 31 on an optical disk on which a laser beam spot 30 rotates in the one-beam method.
3 shows a state in which the reflected light from the pits 31 is read while following. Arrows in the figure indicate the rotation direction (track direction) of the optical disk. The reflected laser beam 30r reflected by the light receiving element 32 that reads the reflected beam of the laser beam spot 30 in the one-beam method is shown in FIG.
(B).

In the case of the one-beam method, when the light intensities detected on the light receiving surfaces 32a, 32b, 32c, and 32d of the light receiving element 32 are represented by A, B, C, and D, respectively, the push-pull signal is (A + D)- It is calculated as (B + C). Normally, the DC component of the push-pull signal obtained by this calculation includes a tracking error and an error due to a field shake (lens shift). In a state where the laser beam is off from the center of the lens and the track is on, the tracking error is zero, so the value obtained by the above equation represents the lens shift amount. If the main push-pull signal is larger than a predetermined reference value after the track jump and the track on, the control unit
It is determined that the lens shift has occurred, and the next track jump operation is stopped, and the track jump operation is not executed until the lens jumps below a predetermined reference value.

Next, a case will be described in which a differential push-pull signal obtained by a three-beam method used when reproducing a write-once optical recording medium or a rewritable optical recording medium is used for detecting a lens shift amount. FIG. 3 (a)
In the three-beam method, the main laser beam spot 4
0, the manner in which the side laser light spot 41 and the side laser light spot 42 follow the pit 43 on the rotating optical disk and read the reflected light from the pit 43 is shown. The arrow shown in the figure indicates the rotation direction (track direction) of the optical disk. A laser beam 40r reflected by a light receiving element 44 that reads reflected light of a main laser beam in the three-beam method; a laser beam 41r reflected by a light receiving element 45 that reads reflected light of a side laser beam; FIG. 3B shows the laser light 42r reflected on the light receiving element 46.

In the three-beam method, the light receiving surface 4 of the light receiving element 45
5a, 45b, side push-pull signals represented by ((F + H)-(E + G)) when the light intensities detected on the light receiving surfaces 46a, 46b of the light receiving element 46 are represented by E, F, G, H, respectively. A light receiving surface 44a of the light receiving element 44,
When the light intensities detected at 44b, 44c, and 44d are represented as A, B, C, and D, respectively, ((A + D)-(B +
C)) The sum component of the main push-pull signal represented by (C)) and the above-mentioned side push-pull signal (A + D) − (B + C) + k ｛(F + H) − (E +
G)｝ is used for detecting a lens shift amount. Here, k indicates a predetermined constant.

In particular, since the difference between the light intensity (A + D)-(B + C) and the light intensity k {(F + H)-(E + G)} is a tracking error including an error due to the field fluctuation, the sum component is calculated. In, the tracking error component included in the differential push-pull signal is canceled. Therefore, there is an advantage that the S / N ratio when detecting the lens shift amount is improved and the accuracy of detecting the lens shift amount is improved.

The optical disc apparatus 1 does not execute a track jump while the value obtained by the calculation exceeds a predetermined reference value, so that a delay in a seek operation caused by accumulation of problems during tracking is prevented. .

The optical disk apparatus 1 uses a value obtained by the above-described operation using a push-pull signal for detecting a lens shift, thereby enabling a CD among optical recording media.
A stable seek operation can be realized for an optical disc having an unrecorded portion such as -R, CD-RW, etc., and on which no frame sync is recorded.

As shown in FIG. 1, an optical disk device 1 according to an embodiment of the present invention performs an optical pickup (OP) unit 11 for reading data from an optical disk 20 and performs various processes on the read signals. A light receiving element output processing unit 12 and a focus servo 13 for generating a focus servo signal from a signal sent from the light receiving element output processing unit 12
A track servo 14 for generating a track servo signal from a signal sent from the light receiving element output processing unit; and a signal processing unit 15 for processing a signal read from the optical disk 20.
And a control unit 16 for controlling each unit.

The optical disk drive 1 includes a spindle motor 1
7, the optical disk 20 is driven. The optical disk device 1 includes a spindle driver (not shown) that controls the rotation of a spindle motor, a thread motor that moves the OP unit 11 in the radial direction of the optical disk, and a thread driver that controls the operation of the thread motor.

The optical disc apparatus 1 includes a tracking driver (not shown) for controlling the swing of the objective lens of the OP unit 11 and the focus of the beam by moving the objective lens of the OP unit 11 in a direction perpendicular to the optical disc. And a general configuration as an optical disc device such as an analog filter processing unit that generates an analog signal for controlling each driver based on signals from the focus servo 13 and the track servo 14.

The OP unit 11 includes a laser diode (LD),
It has a laser diode driver (LDdrv), an objective lens that converges laser light from the laser diode, an actuator that supports and controls the position of the objective lens, a photodetector IC (PD IC), a half mirror, etc., and detects optical signals. And outputs it to the light receiving element output processing unit 12.

The light receiving element output processing section 12 samples and holds eight signals consisting of a beam signal, a side push-pull signal, and a main push-pull signal detected from the OP section 11. Light receiving element output processing unit 12
Further processes the side push-pull signal and the main push-pull signal, and calculates FE (focus error), TE (tracking error), MIRR (mirror), ATIP (Absolute T
ime In Pregroove), and generates a signal such as a read main signal. The light receiving element output processing unit 12 outputs
TE and FE are output to the focus servo 13 and the track servo 14.

The focus servo 13 receives the FE from the light receiving element output processing unit 12 and is controlled by the control unit 16 to generate a focus servo signal unique to the optical disk.
In addition, the track servo 14 includes the light receiving element output processing unit 12
And generates a track servo signal unique to the optical disc under the control of the control unit 16.

Control signals of various servos from the focus servo 13 and the track servo 14 are converted into analog signals in an analog filter processing section, and output to a spindle driver, a thread driver, a tracking driver, and a focus driver.

The spindle driver controls the rotation of the spindle motor based on a signal from the analog filter processing section. The thread driver controls a thread operation of the thread motor based on a signal from the analog filter processing unit. The tracking driver swings the OP unit 11 based on a signal from the analog filter processing unit,
The position of a beam spot irradiated on the disk surface of the optical disk is controlled. The focus driver controls the focus adjustment of the laser by moving the OP unit 11 in a direction perpendicular to the disk surface of the optical disk based on a signal from the analog filter processing unit. The spindle motor 17 rotates the optical disc 20 based on a signal from a spindle driver. The thread motor performs a thread operation of the OP unit 11 based on a signal from the thread driver.

The control unit 16 includes a program memory for storing programs for performing various processes, a RAM as a work area for temporarily storing various data, a CPU,
And Further, the control unit 16 controls all the units.

Next, the operation when the optical disk device 1 reads data on the optical disk surface will be described.

The light of the laser diode reflected from the disk surface of the optical disk is read by the lens optical system of the OP unit 11. The light from the lens optical system is converted into an electric signal by the PDIC, sampled and held in the light receiving element output processing unit 12, and the signals such as FE, TE, mirror, ATIP, read main signal, etc. are converted from the eight predetermined signals. Is generated by the arithmetic processing.

The mirror is a detection signal of the change in the reflectance of the optical disk output from the light receiving element output processing unit 12,
It is detected when the OP unit 11 crosses a track. Therefore, the control unit 16 counts the number of mirrors,
The current seek position and reading position are detected.

ATIP is time information recorded in a wobble groove written on an optical disk and Bi-Phase modulated, and is a process for controlling a spindle motor.

The focus error obtained by the light receiving element output processing unit 12 is input to a focus driver via an analog filter processing unit after its characteristics are adjusted by a focus servo 13. The focus driver moves a lens drive focus coil (not shown) of the OP unit 11 in the vertical direction to correct a focus shift.

The tracking error obtained by the light receiving element output processing unit 12 is subjected to digital filter processing by the track servo 14. Thereafter, the signal passes through the analog filter processing unit and is input to the tracking driver. The tracking driver finely moves the lens drive tracking coil of the OP unit 11 in the radial direction to correct a tracking deviation. A tracking servo 14 extracts a DC component from the tracking error obtained by the light receiving element output processing unit 12, and performs a digital filter process. After that, it is input to the thread driver through the analog filter processing unit.

The thread driver operates the thread motor to move the entire OP section 11 in the radial direction of the optical disk to correct the deviation of the thread operation. During the seek operation, the sled motor is forcibly driven by intentionally applying the sled control voltage from the outside.

As described above, the tracking error AC
A tracking operation in which only the lens is finely moved in the radial direction based on the component is performed, and a sled operation in which the entire OP unit 11 is moved in the radial direction based on the DC component is performed.

At the time of reading operation, the light receiving element output processing section 1
After the signal corresponding to the recording pit is extracted from a predetermined combination of the eight signals in 2, the signal is subjected to equalizer processing and supplied to the signal processing unit 15 in the form of an EFM (Eight to Fourteen Modulation) signal. In the signal processing unit 15, the CIRC (Cross Interleave Reed-Solomon Code)
The desired data is obtained by decoding based on.

Therefore, according to the optical disk device 1 described above, the value obtained from the push-pull signal is used for detecting the lens shift, so that the optical recording medium 1
In particular, a stable seek operation is realized for an optical disk such as a CD-R or a CD-RW having an unrecorded portion and no frame sync recorded.

It should be noted that the present invention is not limited to only the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

[0046]

As described above in detail, the optical disk apparatus according to the present invention comprises a converging means for converging and irradiating an optical disk with a light beam, and a light amount detecting means for detecting the amount of reflected or transmitted light of the converged light beam from the optical disk. Means, an optical axis shift detecting means for detecting a shift of the optical axis of the light beam with respect to the converging means, and a control means for controlling a track jump in accordance with a detection result of the optical axis shift detecting means.

Further, in the optical disk device according to the present invention, the optical axis shift detecting means detects the shift of the optical axis from the push-pull signal obtained from the signal from the light quantity detecting means. Such an optical disc apparatus controls a track jump in accordance with a detection result obtained by an optical axis shift detecting unit that detects a shift of an optical axis of a light beam with respect to a converging unit.

Therefore, the optical disc apparatus according to the present invention does not execute the track jump while the value obtained by the optical axis deviation detecting means exceeds the predetermined reference value, so that the trouble at the time of tracking is accumulated. The resulting delay in seek operation is prevented.

Further, the optical disk device according to the present invention comprises:
Among optical recording media, CD-R (Compact Disc-Recorda
ble) and an optical disc on which a frame sync is not recorded, such as a CD-RW (Compact Disc-ReWritable), etc., realizes a stable seek operation.

The track jump control method according to the present invention includes a light amount detecting step of detecting a reflected light or a transmitted light amount of a light beam convergently applied to an optical disk, and an optical axis detecting a shift of the optical axis of the light beam. A shift detecting step; and a control step of controlling a track jump in accordance with a detection result in the optical axis shift detecting step.

In the optical axis shift detecting step, the shift of the optical axis is detected from a push-pull signal obtained from the signal from the light quantity detecting step. According to such a track jump control method, the track jump is controlled according to the detection result in the optical axis shift detecting step for detecting the shift of the optical axis of the light beam.

Therefore, according to the track jump control method of the present invention, the track jump is not executed while the value obtained in the optical axis deviation detecting step exceeds the predetermined reference value, so that the trouble at the time of tracking is accumulated. The delay of the seek operation caused by this is prevented.

According to the track jump control method of the present invention, CD-R, CD
-A stable seek operation is realized even on an optical disc on which a frame sync is not recorded, such as RW.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an optical disk device shown as an embodiment of the present invention.

FIG. 2A is a schematic diagram schematically illustrating a one-beam method for reading recording pits with one spot of laser light, and FIG. 2B is a diagram illustrating reflection on a light receiving element in the one-beam method. FIG. 3 is a diagram showing a laser beam to be emitted.

FIG. 3A is a schematic diagram schematically illustrating a three-beam method for reading recording pits with three spots of laser light, and FIG. 3B is a diagram illustrating reflection on a light receiving element in the three-beam method. FIG. 3 is a diagram showing a laser beam to be emitted.

FIG. 4A is an explanatory diagram schematically illustrating a state in which the laser beam axis in the actuator unit of the conventional optical disc device is normally track-on, and FIG.
(B) is a schematic diagram schematically showing a state in which the track is turned on in a state where the laser optical axis in the actuator unit of the conventional optical disk device is shifted from the center of the lens.

[Explanation of symbols]

Reference Signs List 1 optical disk device, 11 OP unit, 12 light receiving element output processing unit, 13 focus servo, 14 track servo, 15 signal processing unit, 16 control unit, 17 spindle motor, 20 optical disk

Claims (12)

[Claims] 1. A converging means for converging and irradiating a light beam onto an optical disc; a light quantity detecting means for detecting a reflected light or a transmitted light quantity of the converged light beam from the optical disc; and a shift of an optical axis of the light beam with respect to the converging means. An optical disc device comprising: an optical axis shift detecting means for detecting a shift; and a control means for controlling a track jump in accordance with a detection result of the optical axis shift detecting means. 2. The optical disk apparatus according to claim 1, wherein said optical axis shift detecting means detects a shift of the optical axis from a push-pull signal obtained from a signal from said light quantity detecting means. 3. The optical disk device according to claim 2, wherein when the value of the DC component of the push-pull signal is larger than a predetermined reference value, the optical axis is deviated. 4. A converging means for converging and irradiating a main beam and at least one sub-beam onto an optical disc, and a light quantity detecting means reflecting or transmitting light of the main beam and the sub-beam from the optical disc. 2. The optical disk device according to claim 1, wherein the optical axis shift detecting means detects a shift of the optical axis from a push-pull signal obtained from a signal from the light quantity detecting means. 5. The optical axis shift detecting means according to claim 4, wherein the optical axis shift detecting means detects an optical axis shift by canceling a tracking error component included in the push-pull signal with respect to the push-pull signal. Optical disk device. 6. The optical axis deviation detecting means according to claim 1, wherein said optical axis shift detecting means is configured to emit light based on a main push-pull signal obtained from a main beam, a side push-pull signal obtained from a sub-beam, or a sum signal of said main push-pull signal and said side push-pull signal. 6. The optical disk device according to claim 5, wherein the deviation of the axis is detected. 7. A light amount detecting step of detecting a reflected light amount or a transmitted light amount of the light beam converging and irradiating the optical disk from the optical disk; an optical axis shift detecting step of detecting an optical axis shift of the light beam; A control step of controlling a track jump in accordance with a detection result in the optical axis deviation detection step. 8. The track jump control method according to claim 7, wherein in the optical axis shift detecting step, a shift of the optical axis is detected from a push-pull signal obtained from a signal from the light quantity detecting step. 9. The track jump control method according to claim 8, wherein the optical axis is deviated when the value of the DC component of the push-pull signal is larger than a predetermined reference value. 10. A light beam converging and irradiating an optical disc has a main beam and at least one sub-beam, and in the light amount detecting step, reflected light or transmitted light of the main beam and the sub-beam from the optical disc is detected. 8. The track jump control method according to claim 7, wherein in the optical axis shift detecting step, the optical axis shift is detected from a push-pull signal obtained from the signal detected in the light quantity detecting step. 11. The optical axis deviation detecting step, wherein a deviation of an optical axis is detected by canceling out a tracking error component included in the push-pull signal with respect to the push-pull signal. Item 11. A track jump control method according to item 10. 12. In the optical axis deviation detecting step, light is emitted by a main push-pull signal obtained from a main beam, a side push-pull signal obtained from a sub-beam, or a sum signal of the main push-pull signal and the side push-pull signal. 12. The track jump control method according to claim 11, wherein an axis shift is detected.