JP3361662B2 - Optical storage device seek control method and optical storage device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seek control method and an optical storage device of an optical storage device for seek-moving a light beam to a target track of an optical storage medium.
Seek control method and optical recording for optical storage device using SP
Memory device .

Optical storage devices such as optical disk devices and optical card devices are widely used as storage devices. In such an optical storage device, a light beam is applied to the optical storage medium to write and read data on the optical storage medium.

In this optical storage device, a so-called seek operation of moving a light beam to a target track is performed. In this seek operation, a feedforward amount is given during acceleration and deceleration to perform acceleration and deceleration. In such feedforward control, the system tends to become unstable when the feedforward amount is applied. Therefore, a technique for preventing the system from becoming unstable is desired.

[0004]

2. Description of the Related Art FIGS. 16 (A) and 16 (B) are explanatory views of a conventional technique.

In order to seek to a target track in an optical disk device, it is necessary to generate a movement amount from the track at the current position to the target track. Therefore, as shown in FIG. 16A, a target speed curve from the track at the current position to the target track is set. This target speed curve is composed of an acceleration section, a constant speed section, and a deceleration section. Then, the feedforward amounts in the acceleration direction and the deceleration direction are applied to the acceleration section and the deceleration section, respectively.

Then, the current position and the actual speed of the optical head or the light beam are detected. At the same time, the target speed at the detected current position is calculated in the target speed curve.
Further, the error between the target speed and the actual speed at that position is calculated. Then, the head moving mechanism is controlled by the error amount.

In the sample servo control system in which the processor is used in the control circuit, the current position is detected from the track error signal at each sample timing. Then, after calculating the target position at the sample timing, the target speed and the actual speed are calculated.

Then, the error amount between the target speed and the actual speed is calculated. Also, it is determined whether the detected current position is the planned acceleration start point or deceleration start point. If the start point is the scheduled start point, the feedforward amount in the acceleration direction or the deceleration direction is added to the above-described error amount to obtain the control amount. The motor of the head moving mechanism is driven by this control amount.

FIG. 16B shows a conventional time chart at the start of deceleration. As shown in FIG. 16B, in the sample servo control, after it is determined that deceleration is started,
Various kinds of processing are performed. Then, finally, the feedforward amount is added to the error amount, and the control amount is output.

[0010]

The motor of this head moving mechanism requires a large torque in order to realize a high speed seek. Therefore, the motor coil has a large inductance component. As a result, the actual current of the motor rises slowly. Therefore, the actual speed is delayed with respect to the target speed curve.

Further, in the sample servo control, a time delay occurs with respect to the target speed curve from the timing of the acceleration start instruction or the deceleration start instruction until the feedforward amount is output.

For this reason, as shown in FIG. 16 (B), when the feedforward amount is output, control is made to recover the delay of the actual start of deceleration, so the error amount increases and the overshoot amount increases. Become. This makes the servo system unstable. Therefore, in the conventional technique, it is difficult to position the target track.

A similar problem occurs during acceleration, and control is performed to recover the delay in the actual start of acceleration, so the error amount increases and the overshoot amount increases. Therefore, in the conventional technique, constant speed control becomes difficult. Further, when the amount of overshoot is large, the noise of the motor becomes large.

An object of the present invention is to provide a seek control method of an optical storage device for performing a stable seek operation by reducing the amount of overshoot when feedforward is applied.

Another object of the present invention is to provide a seek control method of an optical storage device for preventing the system from becoming unstable due to the application of the feedforward amount.

Another object of the present invention is to provide a seek control method for an optical storage device for preventing the actual speed from being delayed from the target speed curve.

[0017]

To achieve this object, the present invention is directed to seek control of a head moving mechanism such that a light beam of an optical head seeks from a track on an optical storage medium to a target track. In a seek control method for an optical storage device, an acceleration section according to a seek distance from the certain track to the target track,
A target speed curve consisting of a speed section and a deceleration section, and the target
Acceleration opening before the acceleration change of the target velocity of the velocity curve occurs
Feedforward value at the position before start or before deceleration start
Calculating a generation position; generating a target speed along the target speed curve ; detecting an actual speed of the optical head from a track error signal of the optical head; Calculating an error value between the speed and the actual speed; and, in the target speed curve, the total value before the acceleration change of the target speed occurs.
A step of generating a feedforward value from the calculated feedforward value generation position, a step of adding the error value and the feedforward value to calculate a control value, and the head moving mechanism based on the control value. And driving the same. Also, books
The optical storage device of the invention optically records the light beam of the optical head.
A head moving mechanism for moving to a desired track of the storage medium,
The optical beam of the optical head is stored in the optical storage medium.
Head to seek from track to target track
A control unit that seek-controls the moving mechanism,
Is from the certain track to the target track
Acceleration section, constant speed section, deceleration section according to the seek distance of
And a target speed of the target speed curve
Before acceleration starts before deceleration changes occur or deceleration starts
Calculate the feedforward value generation position and the previous position
And a target speed generated along the target speed curve,
The detected from the track error signal of the optical head
Calculate the error value with the actual speed of the optical head,
The feed forward value
To generate the error value and the feedforward
Value is added to calculate the control value and
In addition, the head moving mechanism is driven.

[0018]

1 is a block diagram of an embodiment of the present invention. In the figure, the servo system of the focus system which is not related to track access is omitted.

The optical disk 1 is irradiated with laser light by an optical head (positioner) 2. As a result, data read / write is performed. The optical head 2 includes an objective lens 2 for irradiating the optical disc 1 with laser light.
0, an actuator 21 that drives the objective lens 20 in a direction that crosses the track of the optical disc 1, and an objective lens 2
And a lens position detector 22 for detecting the position of 0.

A VCM (voice coil motor) 23 moves the optical head 2 in a direction traversing the track of the optical disc 1.

DSP (Digital Signal Processor)
3 is a track error signal TES during on-track in response to a sample timer interrupt of 40 kHz to 50 kHz.
To obtain the position error from the track center. Then, a controlled variable is created. Similarly, during the seek processing, as described with reference to FIG.
Create a controlled variable from ES.

The host MPU 5 issues a host command such as a seek command to the DSP 3 and transfers host data such as a seek difference.

The first digital / analog converter 40 is
The track offset value from the host MPU 5 is converted into an analog amount. The adder 41 outputs the track error signal TE
The output (track offset amount) of the first digital / analog converter 40 is added to S.

The secondary low-pass filter 42 is an analog low-pass filter that cuts high-frequency components of the track error signal TES. The cutoff frequency is 20k
It is set to Hz. First analog / digital converter 4
3 converts the analog track error signal TES from the low pass filter 42 into a digital value.

The track error signal TES is a known signal obtained from a four-division photodetector (not shown) of the optical head 2. The track error signal TES forms a sine wave of one cycle every time the track crosses.

A zero-cross comparator (zero-cross circuit) 44 slices the track error signal TES with a reference voltage to generate a track zero-cross signal TZC.

The track counter circuit 45 is for counting the track zero-cross signal TZC and detecting the position of the light beam.

The secondary low-pass filter 46 is an analog low-pass filter for cutting the high frequency component of the lens position signal LPOS from the lens position detector 22.
The second analog / digital converter 47 receives the analog lens position signal LPO from the low pass filter 46.
Convert S to digital value.

The second digital / analog converter 48 is
The pseudo track error signal from the DSP 3 is converted into an analog quantity. This pseudo track error signal is generated by the DSP3
Is a track error signal input from the first analog / digital converter 43 with a predetermined gain. The pseudo track error signal is monitored, and the track offset value is adjusted so that the value becomes vertically symmetrical.

The third digital / analog converter 49 is
The actuator control value from the DSP 3 is converted into an analog quantity. The drive circuit 50 drives the actuator 21 by the output of the third digital / analog converter 49.

The fourth digital / analog converter 51 is
The VCM control value from DSP3 is converted into an analog quantity.
The drive circuit 52 includes a fourth digital / analog converter 51.
The VCM 23 is driven by the output of.

2A, 2B, and 2C are D
FIG. 3 is a firmware configuration diagram of SP3, FIG. 3 is a seek command processing flowchart in FIG. 2C, and FIG. 4 is an explanatory diagram of the seek processing.

As shown in FIG. 2A, the DSP 3 initializes the memory and enters the idle state. If an interrupt occurs in the idle state, the interrupt process is executed.

When there is a sampling interrupt, the DSP 3 executes the sampling interrupt process shown in FIG. 2 (B). This sampling interrupt process will be described with reference to FIG.

(S1) First, the DSP 3 executes a VCM calculation process for calculating a VCM control amount, which will be described later with reference to FIG.

(S2) Next, the DSP 3 executes LPOS calculation processing for calculating the control amount of the lens position.
For example, when the lens is locked, the lens position signal LPOS from the second analog / digital converter 47 is sampled to obtain the relative position between the optical head 2 and the lens.
Then, a control value is calculated so that the position error obtained by the lens position signal LPOS signal becomes zero. With this control value, the track actuator 21 is controlled via the digital / analog converter 49 and the drive circuit 50. This allows the lens 20 to be attached to the optical head 2.
Is controlled to be centered.

(S3) Next, the DSP 3 executes focus calculation processing for calculating the control value of the focus position.

(S4) Further, the DSP 3 executes a track calculation process for calculating a control value of the track actuator, which will be described later with reference to FIG. Then, the process ends.

When there is an interrupt from the host MPU 5, the host interface interrupt processing shown in FIG. 2C is executed. In this interrupt processing, the command is analyzed and the command is executed.

The process of the seek command in this command execution will be described with reference to FIG.

(S10) When the DSP 3 receives the seek command, the seek difference, and the seek direction,
The first track position LAE indicating the end position of the acceleration section of the lens is set. LAE is predetermined to "0.3" track.

(S11) Next, the DSP 3 sets the second track position LCE indicating the end position of the constant velocity section of the lens. The LCE is predetermined for the “4” track. This second track position LCE corresponds to the positioner 2
It is also the start position of the acceleration section.

(S12) The DSP 3 sets the third track position PAE indicating the end position of the acceleration section of the positioner 2 to X.
Set to 1. This value X1 is the difference DIF
However, if it is 6000 tracks or more, set it to the “3000” track. On the other hand, the difference DIF is 6000
If it does not exceed the track, set [DIF] / 2.

(S13) Next, the DSP 3 sets the fourth position PCE indicating the end position of the constant speed section of the positioner 2 to X2.
Set to. This value X2 is the difference DIF
If it is 6000 tracks or more, ([DIF] -300
0) Set to track. On the other hand, the difference DIF
However, if it does not exceed 6000 tracks, the above-mentioned X1 is set. The fourth track position PCE is also the start position of the deceleration section of the positioner 2.

(S14) The DSP 3 sets the fifth track position PBE indicating the end position of the deceleration section of the positioner 2 to X.
Set to 3. The value X3 is ([DIF] -4) track.

(S15) The DSP 3 sets the sixth track position LBS indicating the end position of the constant velocity section of the lens to X4. This value X4 is ([DIF] -0.3) track. This position LBS is also the start position of the deceleration section of the lens.

(S16) The DSP 3 sets the seventh track position LBE, which indicates the end position of the deceleration section of the lens, to the difference [DIF].

(S17) The DSP 3 sets the track position PASF indicating the start position of the acceleration feedforward section of the positioner to (second track position LCE-0.5 track). That is, the start position of the acceleration feedforward of the positioner is the end position LC of the lens constant velocity section.
From E (that is, the start position of the acceleration section of the positioner), 0.
It is set 5 tracks before.

Next, the DSP 3 sets the track position PA indicating the end position of the acceleration feedforward section of the positioner.
EF, (3rd track position PAE-10 track)
Set to. That is, the end position of the acceleration feedforward of the positioner is 10 from the end position of the positioner acceleration section (that is, the start position of the constant speed section of the positioner) PAE.
It is set before the track.

(S18) The DSP 3 sets the track position PBSF indicating the start position of the deceleration feedforward section of the positioner to (the fourth track position PCE-10 track). That is, the start position of deceleration feedforward of the positioner is set 10 tracks before the start position of the deceleration section of the positioner.

Next, the DSP 3 determines the track position PB indicating the end position of the deceleration feedforward section of the positioner.
EF is set to (fifth track position PBE-0.5 track). That is, the end position of the positioner's deceleration feedforward is set 0.5 track before the end position of the positioner's deceleration section.

(S19) Finally, the DSP 3 sets the seek status signal SKSTS to "1" (lens acceleration) and ends the processing.

This seek command processing determines the seek processing mode up to the target track. As shown in FIG. 4, from track “0” to track LAE (0.3)
Up to is the acceleration section of the lens. This seek status signal SKSTS is "1".

From track LAE to track LCE (0.
Up to 3), the constant velocity section of the lens. This seek status signal SKSTS is "2". Truck LC
From E to the track PAE (= X1) is the positioner acceleration section. This seek status signal SKSTS
Is “3”.

From track PAE to track PCE (= X
Up to 2), it is a constant speed section of the positioner. This seek status signal SKSTS is "4". The position from the track PCE to the track PBE (= X3) is the deceleration section of the positioner. This seek status signal SKS
TS is “5”.

From track PBE to track LBS (= X
Up to 4), the constant velocity section of the lens. The seek status signal SKSTS is "6". Truck LB
From S to the track LBE is the deceleration section of the lens. This seek status signal SKSTS is "7". Incidentally, when the seek status signal SKSTS is "0", it indicates fine control during on-track.

These seek status signals SKSTS
Is stored in the register. In this way, each acceleration section, constant speed section, and deceleration section are set according to the seek difference.

On the other hand, the start / end positions PASF, PAEF, P of each feedforward during acceleration and deceleration
The BSF and PBEF are illustrated in FIG. That is, the feedforward value is applied before the start of the acceleration section and the deceleration section. Since the acceleration section and the deceleration section start at the target speed, the acceleration changes at the target speed. Therefore, the feedforward is started at the target speed before the acceleration changes at the target speed.

The feedforward value at the time of this seek is given to each of the track actuator and the positioner according to the seek mode.

This feedforward value is a value corresponding to the acceleration α1 used for the target position calculation in the case of the track actuator, and is a value corresponding to the acceleration α2 used in the target speed calculation for the positioner. It is a value.

If the feedforward value is increased, a large acceleration amount can be obtained, so that the time required to reach the target position is shortened. However, it becomes difficult to control while seeking. Since the acceleration performance of each of the track actuator and the positioner is proportional to the drive current at a saturation current of the drive circuit or less, it is desirable that the feedforward value be a value according to the acceleration value.

On the other hand, the VCM 23 for driving the positioner
Requires a large torque. Therefore, VCM23
The coil has a large inductance component.
As a result, the rising of the current is delayed. Also, D
When the sample servo control by SP3 is performed, a delay occurs due to the sample processing.

Therefore, when the feedforward amount is applied, the control error amount increases and the overshoot amount increases. This makes the system unstable. Therefore, set the feedforward timing to the positioner earlier than the timing at which the acceleration change occurs in the planned target speed curve, and reduce the error amount.
Reduce the amount of overshoot.

FIG. 5 is a flow chart of the VCM calculation processing in FIG. 2B, FIG. 6 is a flow chart of the track calculation processing in FIG. 2B, FIG. 7 is a flow chart of the SKSTS determination processing in FIG. 6, and FIGS. (B) is a flow chart of the target position calculation process in FIG. 6, FIG. 12 is an explanatory diagram of the target position calculation process,
FIG. 13 is a flowchart of the current speed calculation process in FIG.

The VCM calculation process will be described with reference to FIG.

(S21) The DSP 3 checks whether the seek status signal SKSTS is other than "0". If the seek status signal SKSTS is other than "0", that is, if the seek status signal SKSTS is "0", fine control is performed for fine control. That is, the track error signal TES is sampled from the analog / digital converter 43 to obtain the position error from the track center. Then, the track actuator 21 is controlled by calculating a control value such that the position error becomes zero.

(S22) Conversely, the seek status signal S
If KSTS is other than "0", seek processing is in progress. DS
P3 calculates the target speed Vt. The target speed Vt is
[Target position at previous sampling interrupt]-[Target position at current sampling interrupt] These target positions are obtained by the track calculation process of FIG.

(S23) Next, the DSP 3 sends the current speed V
Calculate p. The current speed Vp is obtained by [current position in previous sampling interrupt]-[current position in current sampling interrupt]. This current position is obtained by the track calculation process of FIG.

(S24) Next, the DSP 3 calculates the speed error ΔV by the following equation.

ΔV = Vt−Vp (1) (S25) Next, the DSP 3 performs a low-pass filter (iiR filter) calculation on the speed error ΔV to obtain a control error value.

(S26) Furthermore, the DSP 3 causes V which will be described later.
When the CM feedforward flag is on (“1”), a predetermined feedforward value is added to the obtained control error value. This feedforward value is a predetermined acceleration amount α.

(S27) Finally, the DSP 3 converts the obtained control value into a VCM digital / analog converter (DAC).
Output to 51. This completes the VCM calculation process.

Next, the track calculation process will be described with reference to FIGS.

(S30) The DSP 3 determines the seek status signal SKSTS by the processing of FIG. 7 described later. When the seek status signal SKSTS is "0", on-track control is performed as described above for fine control.

(S31) If the seek status signal SKSTS is not "0", the DSP 3 calculates the target position according to each seek status. The calculation of this target position will be described later with reference to FIGS. 8 to 11B.

(S32) Next, the DSP 3 calculates the current position, which will be described later with reference to FIG.

(S33) The DSP 3 then calculates the position error. The position error POSERR is [target position]-
It is obtained by calculating [current position].

(S34) Next, the DSP 3 performs PID (proportional / integral / derivative) calculation.

(S35) Further, the DSP 3 calculates the control value by adding the feedforward value to the control error value obtained in step 34 when the lens feedforward flag to be described later is on ("1"). This feedforward value is a predetermined acceleration amount α.

(S36) Finally, the DSP 3 outputs the obtained control value to the digital / analog converter (DAC) 49 of the actuator coil. This ends the track calculation process.

As shown in FIG. 7, the SKSTS determination process is performed by the seek status signal SK as described in FIG.
This is a process of determining the seek status by STS. That is, if the seek status signal SKSTS is "0", it is in the fine control mode. If the seek status signal SKSTS is "1", it means the lens acceleration control mode.

The seek status signal SKSTS is "2".
Then, it is the constant speed control mode of the lens. If the seek status signal SKSTS is "3", the positioner is in the acceleration control mode. If the seek status signal SKSTS is "4", the positioner is in the constant speed control mode. If the seek status signal SKSTS is "5", the positioner is in the deceleration control mode.

The seek status signal SKSTS is "6".
Then, it is the constant speed control mode of the lens. If the seek status signal SKSTS is "7", it means the lens deceleration control mode.

In this way, the seek status is determined,
The target position calculation processing in each seek mode of FIGS. 8 to 11B is performed.

The target position calculation process in the lens acceleration mode will be described with reference to FIG.

(S40) The DSP 3 determines the target position TAGP
Calculate the OS. As shown in FIG. 12, acceleration and deceleration are
It is performed using a constant acceleration α. Therefore, the target position x in acceleration is expressed by the following equation, where α1 is the lens acceleration and t is the time.

[0087] ^{x = α1 · t 2/2} (1) (S41) Next, DSP3 is, the target position TAGPOS
, It is determined whether the end position LAE of the acceleration section of the lens is exceeded.

(S42) The DSP 3 determines the target position TAGP
When the OS exceeds the end position LAE of the lens acceleration section, the seek status signal SKSTS is set to “2” (constant speed mode of the lens) because the lens exceeds the lens acceleration section.
Change to.

(S43) Then, the DSP 3 sets the lens feedforward flag to "0" (no feedforward addition), and ends the processing.

(S44) On the other hand, the DSP 3 causes the target position T
If AGPOS does not exceed the end position LAE of the acceleration section of the lens, it is still the lens acceleration section. Therefore, D
SP3 sets the lens feedforward flag to "1"
Set (with feedforward addition) and finish.

Next, the target position calculation process in the constant speed mode of the lens will be described with reference to FIG.

(S45) The DSP 3 determines the target position TAGP
Calculate the OS. As shown in FIG. 12, the constant speed period is
This is the period when the acceleration is zero. Therefore, the target position x at a constant speed is represented by the following equation, where acceleration is α1, time is t, and acceleration end time is t1.

[0093] ^{x = α · t 2/2} + α1 (t-t1) (2) (S46) Next, DSP3 is, the target position TAGPOS
Determines whether the positioner has exceeded the start position PASF of the acceleration feedforward section of the positioner. When the DSP 3 determines that the target position TAGPOS exceeds the start position PASF of the acceleration feedforward section of the positioner,
Since the feed forward start position has been reached, VCM
Set the feedforward flag to on ("1").

On the contrary, the DSP 3 determines the target position TAGPOS.
However, if it is determined that the start position PASF of the positioner's acceleration feedforward section is not exceeded, the VCM feedforward flag is turned off (“0”) because the feedforward start position has not yet been reached.

(S47) Next, the DSP 3 causes the target position T
It is determined whether AGPOS has exceeded the end position LCE of the constant velocity section of the lens. DSP3 is the target position TAGPOS
However, if it does not exceed the end position LCE of the constant velocity section of the lens, the process ends. On the other hand, the DSP 3 displays the target position TAGPO.
When S exceeds the end position LCE of the lens constant speed section, the seek status signal SKSTS is set to "3" (positioner acceleration mode) because it exceeds the lens constant speed section.
Change to. Then, the process ends.

Next, the target position calculation processing in the positioner acceleration mode will be described with reference to FIG. 9B.

(S48) The DSP 3 determines the target position TAGP
Calculate the OS. As shown in FIG. 12, acceleration is performed using a constant acceleration α2. Therefore, the target position x in acceleration is the positioner acceleration α2, the time t,
When the lens acceleration end time is t2, the lens acceleration end position is x2, and the velocity at the lens acceleration end position is v2, the following expression is obtained.

[0098] x = α2 · (t-t2 ) 2/2 + x2 + v2 (t-t2) (3) (S49) Next, DSP3 is, the target position TAGPOS
Determines whether the end position PAEF of the acceleration feedforward section of the positioner is exceeded. When the DSP 3 determines that the target position TAGPOS exceeds the end position PAEF of the positioner's acceleration feedforward section,
Since the end position of feed forward is reached, VCM
Set the feedforward flag to off ("0").

On the contrary, the DSP 3 determines the target position TAGPOS.
However, if it is determined that the end position PAEF of the positioner's acceleration feedforward section is not exceeded, the feedforward end position PAEF has not yet been reached.
The VCM feedforward flag is turned on (“1”).

(S50) Next, the DSP 3 causes the target position T
AGPOS is the end position PAE of the positioner's acceleration section
Judgment has been made. DSP3 is the target position TAGP
When the OS exceeds the end position PAE of the positioner acceleration section, the seek status signal SKSTS is changed to "4" (positioner constant speed mode) because the positioner acceleration section is exceeded.

On the other hand, the DSP 3 has the target position TAGPOS.
However, if it does not exceed the end position PAE of the positioner acceleration section, it is still the positioner acceleration section. Therefore, the process ends.

Next, the target position calculation processing in the positioner constant speed mode will be described with reference to FIG.

(S51) The DSP 3 determines the target position TAGP
Calculate the OS. As shown in FIG. 12, the constant speed period is
This is the period when the acceleration is zero. Therefore, the target position x at constant speed is acceleration α1, time t, positioner acceleration end time t3, and positioner acceleration end position x.
3 and the speed at the end of acceleration of the positioner is v3, it is expressed by the following formula.

X = x3 + v3 (t−t3) (4) (S52) Next, the DSP 3 determines the target position TAGPOS.
Is the start position P of the positioner deceleration feedforward
Determine if the BSF has been exceeded. The DSP 3 has a target position T
When AGPOS exceeds the start position deceleration feedforward start position PBSF of the positioner, the VCM feedforward flag is turned on (“1”) because the feedforward deceleration section is entered. Conversely, the DSP 3 turns off the VCM feedforward flag (“0”) when the target position TAGPOS does not exceed the positioner deceleration start position PCE.

(S53) Next, the DSP 3 causes the target position T
AGPOS is the end position PCE of the constant speed section of the positioner
Judgment has been made. DSP3 is the target position TAGP
If the OS does not exceed the end position PCE of the constant speed section of the positioner, the process ends.

On the other hand, the DSP 3 has the target position TAGPOS.
However, if the end position PCE of the constant speed section of the positioner is exceeded, the seek status signal SKSTS is changed to "5" (positioner deceleration mode) because the positioner constant speed section is exceeded. Then, the process ends.

Next, the target position calculation process in the positioner deceleration mode will be described with reference to FIG.

(S54) The DSP 3 determines the target position TAGP
Calculate the OS. As shown in FIG. 12, deceleration is performed using a constant deceleration-α2. Therefore, the target position x in deceleration is α2 as the positioner acceleration, t is time, t4 is the end time of the positioner acceleration, x4 is the end position of the positioner acceleration, and v4 is the speed at the end position of the positioner acceleration. Then, it is shown by the following formula.

[0109] x = -α2 · (t-t4 ) 2/2 + x4 + v4 (t-t4) (5) (S55) Next, DSP3 is, the target position TAGPOS
However, the positioner deceleration feed forward end position PB
Determine if EF has been exceeded. The DSP 3 has a target position TA
When the GPOS determines that the positioner deceleration feedforward end position PBEF has been exceeded, the feedforward deceleration control section has ended, so the VCM feedforward flag is set to OFF (“0”).

On the contrary, the DSP 3 determines the target position TAGPOS.
However, the positioner deceleration feed forward end position PB
If it is determined that EF has not been exceeded, the feed-forward deceleration control section has not ended, so the VCM feed-forward flag is set to ON (“1”).

(S56) Next, the DSP 3 causes the target position T
AGPOS indicates the end position PBE of the positioner deceleration section.
Judgment has been made. DSP3 is the target position TAGP
When the OS exceeds the end position PBE of the positioner deceleration section, the seek status signal SKSTS is changed to "6" (lens constant speed mode) because the positioner deceleration section is exceeded.

On the other hand, the DSP 3 has the target position TAGPOS.
However, if it does not exceed the end position PBE of the positioner deceleration section, it is still the positioner deceleration section. Therefore, the process ends.

Next, the target position calculation process in the lens constant speed mode will be described with reference to FIG.

(S61) The DSP 3 determines the target position TAGP
Calculate the OS. As shown in FIG. 12, the constant speed period is
This is the period when the acceleration is zero. Therefore, the target position x at constant speed is t, and the positioner deceleration end time is t.
5, the positioner deceleration end position is x5, and the positioner deceleration end speed is v5.

X = x5 + v5 (t−t5) (6) (S62) Next, the DSP 3 determines the target position TAGPOS.
, It is determined whether or not the end position LBS of the constant velocity section of the lens is exceeded. The DSP 3 ends when the target position TAGPOS does not exceed the end position LBS of the constant velocity section of the lens.

(S63) The DSP 3 determines the target position TAGP
When the OS exceeds the end position LBS of the lens constant velocity section, since the lens constant velocity section is exceeded, the seek status signal SKSTS is changed to "7" (lens deceleration mode). Then, the process ends.

Next, the target position calculation process in the lens deceleration mode will be described with reference to FIG.

(S64) The DSP 3 determines the target position TAGP
Calculate the OS. As shown in FIG. 12, deceleration is performed using a constant deceleration −α1. Therefore, the target position x in deceleration is the lens acceleration α1, the time t, the lens constant speed end time t6, the lens constant speed end position x6, and the speed at the lens constant speed end position. Where v6 is represented by the following formula.

[0119] x = -α1 · (t-t6 ) 2/2 + x6 + v6 (t-t6) (7) (S65) Next, DSP3 is, the target position TAGPOS
, It is determined whether the end position LBE of the deceleration section of the lens is exceeded.

(S66) The DSP 3 determines the target position TAGP
When the OS exceeds the end position LBE of the deceleration section of the lens, the seek status signal SKSTS is changed to "0" (fine control mode) because the lens deceleration section is exceeded.

(S67) Then, the DSP 3 sets the lens feedforward flag to "0" (no feedforward addition), and ends the processing.

(S68) On the other hand, the DSP 3 causes the target position T
If AGPOS does not exceed the end position LBE of the deceleration section of the lens, it is still the lens deceleration section. Therefore, D
SP3 sets the lens feedforward flag to "1"
Set (with feedforward addition) and finish.

In this way, the target position in each seek status is calculated.

Next, the calculation process of the current speed will be described with reference to FIG.

First, the current position is obtained. For this purpose, the method of detecting the current position is changed according to the speed of the light beam.
The seek status signal SKSTS is
If it is "3", "4", or "5", it is determined that the speed of the light beam is high because of the control section of the positioner. Therefore, the amplitude of the track error signal is small. Therefore, the current position is obtained from the value of the track counter 45.

On the other hand, seek status signal SKSTS
Is "1", "2", "6", "7", it is determined that the speed of the light beam is slow because of the lens control section.
Therefore, the amplitude of the track error signal is sufficiently large. Therefore, the current position is obtained from the amplitude value of the track error signal. That is, the DSP 3 samples the digital value of the track error signal TES from the first analog / digital converter 43.

In this seek control, the speed signal obtained from the track counter 45 includes not only the actual speed of the positioner 2 but also the relative speed of the positioner 2 and the objective lens 20. Therefore, it is necessary to subtract the relative speed from the obtained speed signal.

The signal corresponding to the relative speed between the positioner 2 and the objective lens 20 is the differential value of the lens position signal LPOS. Therefore, this is subtracted from the speed signal to obtain the actual speed of the positioner.

The current speed Vp is the current position Xp1.
With the current position Xp0 one sample before, the differentiated lens position signal dL, and the normalized gain Gh,
It is obtained by the following formula.

Vp = Xp1 −Xp0 −dL · Gh In this way, the actual speed of the positioner can be obtained by subtracting the relative speed of the positioner 2 and the objective lens 20 from the signal obtained from the track counter 45. The differentiated lens position signal dL is calculated by the LPOS calculation process (step S3) shown in FIG. Therefore, it can be easily realized by diverting this calculation result.

FIG. 14 is an explanatory diagram of feedforward control, and FIG. 15 is an explanatory diagram of feedforward operation.

Since the coil of the VCM 23 which drives the positioner has a large inductance component, the current rises slowly. Further, when the sample servo control by the DSP 3 is performed, application delay occurs due to the sample processing.

Therefore, when the feedforward amount is applied, the control error amount increases and the overshoot amount increases. This makes the system unstable. Therefore, during deceleration, positioning on the target track becomes difficult. Further, during acceleration, it becomes difficult to stably execute the subsequent constant speed control.

In order to prevent this, as shown in FIG. 15, application of the feedforward value is started before the acceleration / deceleration change starts in the target speed curve. This makes it possible to compensate for the delay in rising of the current of the VCM 3.
Also, the delay due to the sample processing can be compensated. Therefore, the overshoot amount of the error amount when the feedforward amount is applied becomes small, and the system becomes stable.

Further, as shown in FIG. 14, the start and end positions of the feedforward are previously set according to the position of the light beam.
Since the calculation is performed, the calculation process at the target position can be executed at high speed.

The reason why the lens actuator is driven before driving the VCM 23 is to prevent the light beam from moving backward due to the eccentricity of the optical disk. That is, by driving the lens actuator to accelerate the light beam in advance faster than the eccentric velocity of the optical disk, the seek operation can be performed without being affected by the eccentricity of the light beam.

In addition to the above embodiment, the present invention can be modified as follows.

Although the feedforward application timing is controlled from the position of the light beam, the feedforward application timing may be controlled from the number of remaining samples as shown in FIG.

Although the application timings of both feedforwards for acceleration and deceleration are accelerated, either application timing may be accelerated.

As the optical disc, various types such as a writable optical disc and a rewritable optical disc can be used.

The present invention has been described above with reference to the embodiments.
Various modifications are possible within the scope of the invention, and these modifications are not excluded from the scope of the invention.

[0142]

As described above, according to the present invention,
It has the following effects.

Since the feedforward application timing is controlled before the acceleration change of the target velocity curve occurs, the error amount during feedforward application can be reduced and the system can be stabilized. In addition, seek control odor
Calculate the acceleration, constant speed, and deceleration sections according to the seek distance.
And use this to mark the feedforward
Since the acceleration start position is calculated before acceleration or deceleration starts, the system
Can be prevented from becoming unstable, and high-speed seek operation can be realized.

Further, it is possible to prevent the overshoot of the error amount from occurring and to realize stable high speed seek control.

[Brief description of drawings]

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

FIG. 2 is a firmware configuration diagram of the DSP having the configuration of FIG.

FIG. 3 is a flow chart of a seek command process in FIG.

FIG. 4 is an explanatory diagram of the seek process of FIG.

5 is a VCM calculation processing flow chart in FIG.

FIG. 6 is a flowchart of a track calculation process in FIG.

7 is a flow chart of the SKSTS determination process in FIG.

FIG. 8 is a target position calculation processing flow chart (1) in FIG. 6;

FIG. 9 is a target position calculation processing flowchart (part 2) in FIG. 6;

FIG. 10 is a target position calculation processing flowchart (part 3) in FIG. 6;

FIG. 11 is a target position calculation processing flowchart (part 4) in FIG. 6;

FIG. 12 is an explanatory diagram of a target position calculation process of FIGS. 8 to 11.

13 is a flowchart of a current speed calculation process in FIG.

FIG. 14 is an explanatory diagram of feedforward control according to the present invention.

FIG. 15 is an explanatory diagram of a feedforward operation according to the present invention.

FIG. 16 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

1 Optical disc (optical storage medium) 2 positioners 3 DSP 20 Objective lens 21 Track actuator 23 VCM

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-324086 (JP, A) JP-A-4-222248 (JP, A) JP-A-4-3373 (JP, A) JP-A-4-34 60925 (JP, A) JP 8-95643 (JP, A) JP 6-203395 (JP, A) JP 3-127335 (JP, A) JP 6-60398 (JP, A) JP-A-7-210880 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B ⁷ /08-7/085 G11B 21/00-21/08 G05D 3/00-3 / 20

Claims (6)

(57) [Claims] 1. A seek control method of an optical storage device for seeking control of a head moving mechanism so that a light beam of an optical head seeks from a track on an optical storage medium to a target track, wherein the target is moved from the certain track to the target. death for leading to the track
The acceleration section, the constant speed section, and the deceleration section that correspond to the
Of the target speed curve and the target speed of the target speed curve
Before acceleration starts or deceleration starts before acceleration changes
The feedforward value generation position is calculated at
A step, a step of generating a target speed along the target speed curve , a step of detecting an actual speed of the optical head from a track error signal of the optical head, and an error value between the target speed and the actual speed. Calculating the feedforward before the acceleration change of the target velocity occurs in the target velocity curve
Generating a feedforward value from the value generation position, adding the error value and the feedforward value,
A seek control method for an optical storage device, comprising: a step of calculating a control value; and a step of driving the head moving mechanism with the control value. 2. The seek control method for an optical storage device according to claim 1, wherein the step of generating the feedforward value is performed before the acceleration change occurs according to the position of the optical head. And a seek control method for an optical storage device. 3. The seek control method for an optical storage device according to claim 1, wherein the step of generating the feedforward value is performed before the acceleration change occurs in accordance with a moving time of the optical head. A seek control method for an optical storage device, which is a step of generating a value. 4. The seek control method for an optical storage device according to claim 1, 2 or 3, wherein the step of detecting the actual speed includes the step of detecting the position of the optical head from the track error signal at each sample time. And a step of calculating the actual velocity from the difference between the detected position and the detected position of the previous sample time, the seek control method of the optical storage device. 5. The seek control method for an optical storage device according to claim 1, wherein the step of generating the feedforward value is performed for acceleration and deceleration before acceleration start and deceleration start of the optical head. A seek control method for an optical storage device, comprising the step of generating a feedforward value. 6. A light beam from an optical head is stored at an optical storage medium.
A head moving mechanism for moving to a desired track, and a light beam of the optical head are stored in the optical storage medium.
Head to seek from track to target track
And a control unit for performing seek control of the moving mechanism, wherein the control unit is a system for reaching the target track from the certain track.
The acceleration section, the constant speed section, and the deceleration section that correspond to the
Of the target speed curve and the target speed of the target speed curve
Before acceleration starts or deceleration starts before acceleration changes
The feedforward value generation position is calculated at the position of, and the target speed generated along the target speed curve, and
The optical detected from the track error signal of the optical head
An error value with respect to the actual speed of the head is calculated, and from the calculated feedforward value generation position, the flux is calculated.
Generating a feedforward value, adding the error value and the feedforward value,
Calculate the control value and move the head according to the control value.
An optical storage device characterized by driving a mechanism .