JP2774303B2 - Optical disk drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc apparatus in which a kickback operation is appropriately prohibited after the operation of a driving unit for moving a pickup is completed.

[Prior Art] In recent years, instead of recording and reproducing information using a magnetic head, recording and reproducing information at a high density on an optical recording medium using a light beam by an optical pickup have been considered. An optical information recording / reproducing device (hereinafter, referred to as an optical disk device) that can be used has been put to practical use.

As the optical recording medium, a recording medium having tracks formed concentrically and a disk-shaped recording medium (hereinafter referred to as a disk) having tracks formed spirally are widely used.

By the way, when a track seek is performed on a target track of the disc, a coarse seek is performed by a coarse moving means such as a voice coil motor (hereinafter abbreviated as VCM), then tracking is performed to confirm the address of the track, and the lens is moved by a lens actuator. There is a method of performing a moving fine seek (or lens seek).

When the lens actuator is started simultaneously with the end of the coarse seek, vibration occurs due to the acceleration applied to the lens.In JP-A-61-204840, the lens actuator is tracked after a predetermined time from stopping the pickup by the VCM. A lens seek to a target track is performed by a track error signal as a result of tracking.

By the way, when a disk having a spiral track is tracked, the track is held on the track by kickback.

However, the above publication does not disclose this kickback at all.

FIG. 9 shows the timing when kickback is permitted at the timing of VCM servo ON.

In other words, after the VCM seek, turn on the lens servo system,
A little later, the VCM servo system is turned on to set a two-stage servo state, and kickback is allowed.

[Problems to be solved by the invention] Since VCM seek is a high-speed movement, immediately after VCM seek,
The lens shakes or the VCM vibrates. Therefore, V
Immediately after the end of the CM seek, a residual error occurs in the track error signal, and even if the kickback operation is performed, the kickback operation becomes unstable.

The reason why the kickback operation is likely to be unstable will be described below.

Conventionally, the track servo system of the lens was turned on,
Since kickback is permitted while the VCM servo system is on, kickback operation is performed when the disk 1 rotation detection signal, that is, when the mechanical index is detected, comes after this VCM servo system is turned on. I do.

The timing at which the VCM servo system is turned on is turned on if the track error signal is a residual equal to or less than a specified value.

However, the kickback operation becomes unstable even if the residual of the track error signal is small.

The reason for this is that the drive pulse for kickback moves the lens by a certain distance corresponding to the track pitch, and is therefore a constant pulse. For this reason, the residual at the time of jumping out becomes the residual at the time of retracting, and at the time of retracting, the overshoot and undershoot as shown in FIGS. 10 (b) and 10 (c) differ from the ideal one shown in FIG. 10 (a). A shoot occurs, and this (b),
In the kickback in the case (c), off-track is likely to occur.

As described above, conventionally, kickback may be performed in an unstable state immediately after the end of the VCM seek, and the kickback operation fails, and an off-track error occurs.

The present invention has been made in view of the above points, and an object of the present invention is to provide an optical disk device capable of preventing occurrence of an off-track error due to kickback.

[Means for Solving the Problems and Action] An optical disk apparatus according to the present invention includes an optical disk having a spiral track, a laser light source for irradiating a light beam on the track of the optical disk, and a deviation of the track and the light beam in the radial direction of the optical disk. An error signal generating means for generating an error signal indicating the displacement, a light beam moving means capable of moving the light beam in a direction transverse to the track, a driving means for displacing the light beam moving means, and the optical disc rotating once. Detecting means for detecting that the light beam has been detected, based on the output of the detecting means, a track holding means for holding and scanning a desired track with the light beam. Means for prohibiting kickback operation for a time necessary until the light beam becomes smaller, and traversing the light beam across the track. After the operation of the light beam moving means moving in the direction is completed, the kickback operation is prohibited until the residual of the track error signal becomes sufficiently small.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to the drawings.

1 to 5 relate to a first embodiment of the present invention, FIG. 1 is a schematic configuration diagram of an optical disk device of the first embodiment, FIG. 2 is a circuit diagram of a kickback control circuit, FIG. Is a timing chart for explaining the kickback operation.
FIG. 5 is an explanatory diagram showing how the VCM servo is turned on from M seek, and FIG. 5 is a timing chart showing how kickback is performed in the two cases shown in FIG.

As shown in FIG. 1, the optical disk device 1 of the first embodiment
The optical pickup 3 is disposed so as to face one disk surface of the disk 2 rotated by a spindle motor (not shown). The optical pickup 3 is mounted on a carriage 4. The (optical) pickup 3 can be moved together with the carriage 4 in the radial direction R of the (spiral-shaped) disk 2, that is, in the direction traversing the spiral track 6, by coarse operation means such as a VCM 5. is there. Note that a spiral track is also formed on the surface facing the pickup 3.

In the pickup 3, the light of the laser diode 7 is converted into a parallel light beam by the collimator lens 8, and is incident on the polarization beam splitter 9 as P-polarized light. This polarization beam splitter 9
Is almost circularly polarized by the quarter-wave plate 11, is further condensed by the objective lens 12, and is irradiated on the disk 2. The light reflected by this disk 2
After passing through 12, the light is converted into S-polarized light through a quarter-wave plate 11. This S
The polarized light is almost 100% reflected by the polarizing beam splitter 9,
The light enters the critical angle prism 13. The light reflected by the inclined surface of the prism 13 is received by a photodetector 14 disposed at a far field position, facing the emission end face side of the prism 13. This photodetector 14 is formed of a four-divided light receiving element, and is a DS as a reproduction signal added by the addition / subtraction circuit 16.
SUM signal and track error signal TER
Further, a focus error signal (not shown) is generated.

Incidentally, the objective lens 12 can shift (track jump) from the current track position where the light beam is on-track to the adjacent track by applying a track jump pulse to the tracking coil 17 forming the lens actuator. It is like that.

The track jump pulse is supplied to the lens control circuit 19 and the lens drive circuit 21 based on an instruction from the controller 18.
This is performed by being applied to the tracking coil 17 via the.

When a seek from the current track to the target track is performed according to a command from the controller 18, it is determined whether the number of track traversals to the target track is large. It is determined whether the absolute value of the No. difference exceeds a certain reference value. When it is determined that the target track is small, the seek to the target track, that is, the fine seek operation is performed by the track jump pulse.

On the other hand, if the number of seek traverses is large, a seek near the target track is performed by a coarse seek (VCM seek) operation by the VCM5.

In this case, the controller 18 outputs a VCM seek command to the VCM control circuit 23 in which direction (inner or outer circumference) and how much to move.

With this VCM seek command, the VCM control circuit 23 outputs a VCM5 speed control signal to the VCM drive circuit 24 that drives the VCM5 based on the movement amount given by the VCM seek command. With this speed control signal, the VC configured by the analog drive circuit
The M drive circuit 24 drives the VCM 5 to coarsely move the pickup 3 to near the target track (coarse seek).

After the coarse seek by the VCM5, the track servo is turned on, the current track number after the coarse seek is recognized, and a lens seek command according to the number of track crossings to the target track number is sent from the controller 18 to the lens control circuit 19. Is entered. The recognition of the track number is performed by reproducing the reproduced signal from the demodulation circuit 2.
By passing through 5, the controller 18 can be recognized.

The lens control circuit 19 generates a track jump pulse in order to jump the number of tracks given by the lens seek command in a predetermined direction (that is, the direction on the inner circumference side or the outer circumference side). This is a timing circuit for outputting.

The lens drive circuit 21 is configured by an analog drive circuit for driving the objective lens 12.

On the other hand, the disk 2 having the spiral track
Is provided with an index for detecting that the disk 2 has made one rotation, for example, a high reflection pattern 26. When the disk 2 makes one rotation by a position sensor 27 such as a photo reflector, the position sensor 27 is provided. Is detected immediately below the pattern 26. The output of the position sensor 27 is input to the mechanical index detection circuit 28, and when the pattern 26 passes immediately below the position sensor 27, the mechanical index detection circuit 28 outputs a mechanical index pulse.

The position sensor 27 is arranged at a position immediately above the pattern 26 when the boundary area of the disk 2 where the track number changes is read by the pickup 3. In other words, when the pickup 3 reads that the track number has changed, the position sensor 27
26 detections are performed.

The mechanical index pulse output from the mechanical index detection circuit 28 is input to the kickback control circuit 29.

The kickback control circuit 29 generates a kickback pulse for kickback operation in synchronization with the input mechanical index pulse, and outputs the kickback pulse to the lens drive circuit 21.

Accordingly, when this kickback pulse is input, the lens drive circuit 21 supplies a kickback drive signal to the tracking coil 17 to perform a kickback operation, and returns the light spot position by the objective lens 12 to the current track. To do.

In the first embodiment, the tracking servo system has a so-called two-stage servo configuration that performs VCM servo together with lens servo.

That is, even when the eccentricity of the disk 2 is large, the influence of this eccentricity is reduced by the VCM servo.

The track error signal TER is input to the VCM control circuit 23 together with the lens control circuit 19 so that tracking can be performed by the two-stage servo.

By the way, in the case of the spiral track 6, if the track is simply tracked to the current track, the track 6 has a spiral shape and moves to the next track number after one rotation.

For this reason, in the tracking servo state, the operation of returning to the current track by the kickback pulse is performed. Kickback control circuit 29 that generates this kickback pulse
The ON access signal ON ACCESS output when the VCM seek is performed from the VCM control circuit 23 is input to the
If ON ACCESS is not output, the VCM servo is turned on.

 FIG. 2 shows the configuration of the kickback control circuit 29.

The mechanical index pulse is input to the kickback pulse generating circuit 31, and outputs a kickback pulse KBP as shown in FIG. 3F at the rising edge of the mechanical index pulse as shown in FIG. 3A. This pulse K
The BP is output as a kickback pulse shown in FIG. 3 (g) by passing it through an AND circuit 33 whose gate opening / closing is controlled by the kickback permission signal generation circuit 32.

That is, the kickback permission signal KBEN output from the kickback permission signal generation circuit 32 is input to one input terminal of the AND circuit 33, and the pulse KBP passes through the AND circuit 33 only while the signal KBEN is being output. Output as a kickback pulse.

In the first embodiment, if the timing at which the VCM servo is turned on precedes the kickback timing within a specified time in the first embodiment, the kickback permission signal generation circuit 32 generates the first kick that turns on the VCM servo. The back operation is disabled, and a signal KBEN for performing kick back is generated at the next kick back timing.

For this reason, the mechanical index pulse is input to the trigger terminal and the reset terminal of the timer 35 and becomes "L" for a predetermined time from the fall of this mechanical index pulse as shown in FIG. Timer signal TEME becomes
Generate PLS.

The output signal TIME PLS of the timer 35 is applied to the data input terminal of the D flip-flop 36, the signal ON ACCESS is inverted by the inverter circuit 37, and the rising timing of the VCM servo-on signal VCM servo-on shown in FIG. Then, the signal TIME PLS is output as an output Q shown in FIG. The output signal TIME PLS of the timer 35 is also applied to the clear terminal of the D flip-flop 36.
Output Q is reset at the falling edge of PLS. This output Q
Is supplied to the next-stage NOR circuit 38 by a VCM seek signal (that is, ON A
CCESS), and the NOR circuit 38 outputs a kickback permission signal KBEN shown in FIG. 3 (e).

 The operation of the first embodiment will be described below.

The case where the spiral track is rotated as shown in FIG. 4 and the point where the VCM servo is turned on from the VCM seek is indicated by A and the case indicated by B will be described.

In the case of A, the mechanical index pulse is output shortly after the timing when the VCM servo is turned on, and in the case of B, after a relatively long time after the VCM servo is turned on, This is a case where a mechanical index pulse is output.

In the case of A, as shown in FIG. 3 (A) or FIG. 5 (A), even if the mechanical index pulse is first output after the timing of A, the kickback permission signal is output after the detection of the mechanical index pulse. Since KBEN is output, even if this first mechanical index pulse is detected, no kickback pulse is output, and when the next mechanical index pulse is detected, a kickback pulse is output and kickback is performed. Perform the operation. FIG. 5 (A) shows the kickback non-operation period without using the permission signal KBEN of FIG.

On the other hand, if the time from when the VCM servo is turned on to when the mechanical index pulse is detected is long as in the timing shown in B, the permission signal KBEN will be output, and the first mechanism after the VCM servo is turned on will be output. When an index pulse is detected, a kickback pulse is output to perform a kickback operation.

According to the first embodiment, even if a mechanical index serving as an index to be kicked back is detected immediately after the VCM servo is turned on, kickback is not performed, and the residual of the track error signal is sufficiently small. We allow kickback after the time required to become,
The kickback operation can be reliably performed without causing an off-track error.

FIG. 6 shows a kickback control circuit 41 according to a second embodiment of the present invention.

This kickback control circuit 41 outputs the VCM servo-on signal V
The CM servo ON and this signal VCM servo ON and the signal passed through the timer 42 and the inverter 43 are input to the AND circuit 44,
The gate opening / closing control of the output signal KBP of the kickback pulse generation circuit 31 is performed, and only the pulse KBP that satisfies the condition is output as the kickback pulse.

The timer 42 is set to have a time width T equal to or longer than the time required for the residual of the track error signal TER to become sufficiently small after the VCM servo is turned on. Only when a signal obtained by inverting the output of the timer 42 by the inverter 43 becomes “H”, the kickback pulse KBP generated by the mechanical index pulse is allowed to be output as a kickback pulse. I have.

 The operation in this case is as shown in FIG.

When a mechanical index pulse is detected as shown in FIG. 7 (a), the kickback pulse generating circuit 31 outputs a pulse KBP as shown in FIG. 7 (e).

When the VCM servo is turned on, FIG. 7 (b)
As shown in FIG. 7, the signal VCM servo ON becomes "H", and at this rising edge, the timer 42 outputs a pulse having a time width T as shown in FIG. Inverted. Therefore, as shown in FIG. 7 (d), even if a mechanical index pulse is detected within this time T,
The kickback pulse is prohibited from being output, and from the case where the next mechanical index pulse is detected, FIG.
As a result, a mechanical index pulse is output as shown in FIG.

FIG. 8 shows a kickback control circuit according to a third embodiment of the present invention.
Shows 51.

The kickback control circuit 51 is different from the kickback control circuit 41 shown in FIG.
TER is passed through a window comparator 52, and a condition is added so that a signal is output as a kickback pulse only when the level of this signal TER is within a sufficiently small range.
Therefore, a 4-input AND circuit 53 is used instead of the 3-input AND circuit 44 in FIG. Others are the same as those shown in FIG.

In each of the above-described embodiments, it is assumed that the lens servo and the VCM servo are turned on after the coarse seek. In this case, after the two-step servo, the track address (track No.) by the coarse seek is read, and the lens seek is performed by track jump by the number of tracks equal to the difference between this track No. and the target track No. This will result in a coarse seek.

Therefore, if the kickback is not suitable for performing the kickback after the coarse seek, the kickback is not performed even if the index pulse is detected.
Although it will slip, fine seeking is performed after reading this track No., so there is no problem.

In each of the above embodiments, when the VCM seek ends, the VCM
The servo is turned on, but not limited to this.
The VCM servo may be turned on for a certain period of time by a timer or the like, or may be turned on when the track error signal falls within a certain range. Also, regarding the lens servo timing, the VCM is stopped (for example, VCM
The moving speed of the CM may be detected, and it may be confirmed that the speed has become 0).

The present invention is not limited to the case of two-stage servo, but can be similarly applied to a case where the coarse and fine seek functions are performed only by the lens seek and the lens servo is turned on after the lens seek.

In this case, the VCM in each kickback control circuit
Substantially the same can be applied if the lens servo is turned on instead of the servo on.

It should be noted that the present invention can be similarly applied to a case where a seek is performed and a coarse seek is performed by a VCM or the like, even when the servo is not a two-stage servo.

For example, when the target track is accessed only by the lens seek, when the mechanical index pulse is detected immediately after the lens seek and kickback is not performed, two kickbacks are performed when the next mechanical index pulse is detected. Is also good.

[Effects of the Invention] As described above, according to the present invention, when a track is traversed in order to access a target track, a kickback operation is prohibited for an appropriate time immediately after the traversal. Occurrence can be prevented.

[Brief description of the drawings]

1 to 5 relate to a first embodiment of the present invention.
FIG. 1 is a schematic configuration diagram of an optical disk device according to a first embodiment.
FIG. 3 is a circuit diagram of the kickback control circuit, FIG. 3 is a timing chart for explaining the kickback operation, and FIG.
FIG. 5 is an explanatory diagram showing a state where a VCM servo is turned on from a seek operation. FIG. 5 is a timing chart showing a state where kickback is performed in the two cases shown in FIG. 4. FIG. 6 is a second embodiment of the present invention. FIG. 7 is a configuration diagram of a kickback control circuit in FIG. 7, FIG. 7 is a timing chart for explaining the operation of the second embodiment,
FIG. 8 is a block diagram of a kickback control circuit according to a third embodiment of the present invention. FIGS. 9 and 10 show that offtrack is likely to occur when kickback operation is enabled when the VCM servo is turned on. It is explanatory drawing which shows that it becomes. DESCRIPTION OF SYMBOLS 1 ... Optical disk apparatus 2 ... Disk 3 ... (optical) pickup 5 ... VCM 6 ... (spiral) track 12 ... Objective lens 17 ... Tracking coil 19 ... Lens control circuit 21 ... Lens drive Circuit 23 VCM control circuit 24 VCM drive circuit 28 Mechanical index detection circuit 29 Kickback control circuit

Claims (1)

(57) [Claims] An optical disk having a spiral track, a laser light source for irradiating a track of the optical disk with a light beam, and an error signal generating an error signal indicating an amount of deviation of the track and the light beam in a radial direction of the optical disk. Means; a light beam moving means capable of moving a light beam in a direction crossing a track; a driving means for displacing the light beam moving means; a detecting means for detecting that the optical disk has made one rotation; And a track holding means for holding and scanning a desired track by the light beam based on the output of the light beam, and prohibiting a kickback operation for a time necessary until the amplitude of the error signal becomes small when the operation shifts to the VCM servo after the seek operation is completed. An optical disc device comprising: