JP3749235B2 - Optical storage device seek control method and optical storage device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a seek control method of an optical storage device for performing a seek operation on a target track of an optical storage medium, and more particularly to a seek control method of an optical storage device using a DSP.
[0002]
Optical storage devices such as optical disk devices and optical card devices are widely used as storage devices. In such an optical storage device, the optical storage medium is irradiated with a light beam to write and read data on the optical storage medium.
[0003]
In this optical storage device, a so-called seek operation for moving the light beam to the target track is performed. In this seek operation, a track error signal is generated by reflected light from the optical storage medium in order to detect the position of the light beam. When the current position is detected from such a track error signal, a technique for accurately detecting the current position is desired even if the seek speed is increased.
[0004]
[Prior art]
As a method for detecting the current position from the track error signal TES, a method for detecting the current position from an analog value of the track error signal is known. As another method for detecting the current position from other track error signals, the track error signal is zero-sliced to obtain a track zero cross signal TZC. A method of detecting the current position by counting the track zero cross signal is known.
[0005]
[Problems to be solved by the invention]
The cycle of the track error signal TES during seek is 500 kHz at the maximum speed. For this reason, for a sampling frequency of 50 kHz to 40 kHz of the digital servo, it may reach 10 tracks or more for one sample.
[0006]
The track error signal TES during seek decreases in amplitude as the speed increases. For this reason, in the method of obtaining the current position from the analog value of the track error signal, when the seek speed is high, it is difficult to detect the current position with accuracy of one track or less, and accurate seek control is difficult. There was a problem.
[0007]
Further, in the method of calculating the current position from the track zero cross signal, the current position can be stably detected when the seek speed is high. However, when the seek speed is slow, the speed is not stable. For this reason, in the method of detecting the current position from the interval of the track zero cross signal, accurate position detection is difficult, which hinders seek control.
[0008]
An object of the present invention is to provide a seek control method for an optical storage device for stabilizing a control operation during a seek.
[0009]
Another object of the present invention is to provide a seek control method for an optical storage device for optimal phase compensation according to a seek operation.
[0010]
[Means for Solving the Problems]
  The present invention relates to a seek control method for an optical storage device for seek control of a light beam moving mechanism in order to perform a seek operation on a light beam from a track having an optical storage medium to a target track. Detecting a current position from a track error signal indicating a relative position of the light beam to the track;During seek control,Calculate the feedback control amount so that the position error between the target position and the current position is zeroDuring fine control, the feedback control amount is calculated so that the position error due to the track error signal is zero.And the step of controlling the light beam moving mechanism by the feedback control amount, and the step of detecting the current position includes:During the seek controlOf the light beamMoveWhen the speed is slow, the track error signal is analog / digital converted by an analog / digital converter.And a count value by a track zero cross signal obtained by zero crossing the track error signal by a zero cross circuit.A first current position detecting step for detecting the current position from:During the seek controlLight beamMoveWhen the speed is high, the count value by the track zero cross signal that is zero-crossed by the track error signal by the zero cross circuitAnd the value obtained by dividing the interval from the edge of the latest track zero cross signal to the sampling time by the interval of the latest track zero cross signal, andAnd a second current position detecting step for detecting the current position.
[0011]
  In the seek control method, the step of calculating the feedback control amount includes the step of calculating the feedback control amount.Using the phase compensation factor, the position errorCalculating a phase compensation, wherein the step of calculating the phase compensation includes a coefficient of the phase compensation calculation as the seek.controlThe inside of the light beamFine controlUsing a different coefficient thanSelect the phase compensation coefficient according to whether the seek control or the fine control is in progressStep to doHave
[0012]
[Action]
The present invention detects the current position from the analog value of the track error signal TES when the speed of the light beam is low. When the speed of the light beam is low, the amplitude of the track error signal TES is sufficiently large, so that an accurate current position can be detected from the analog value of the track error signal TES.
[0013]
On the other hand, when the speed of the light beam is high, the current position is detected from the count value of the track zero cross signal obtained from the track error signal TES. When the speed of the light beam is high, the amplitude of the track error signal TES becomes small, so that an accurate current position is detected from the count value of the track zero cross signal.
[0014]
Thus, since the current position detection method is changed according to the speed during seeking, the current position can be accurately detected during seeking, and stable position control is possible.
[0015]
Further, in the present invention, during the seek, since the amount of movement at the sampling interval is large and the error is large, the position control is performed by lowering the input gain during the seek. When the input gain is reduced, the characteristics of the phase compensation system are also pseudo-shifted. As a result, the stability of track jumping at the end of seeking decreases. Therefore, in order to improve the phase characteristics during seeking, phase compensation characteristics different from those during on-track are given during seeking.
[0016]
【Example】
FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a circuit diagram of a zero cross comparator having the configuration of FIG. 1, and FIG. 3 is a circuit diagram of a track counter circuit having the configuration of FIG. In the drawing, a servo system of a focus system that is not related to track access is omitted.
[0017]
The optical disk 1 is irradiated with laser light from an optical head (positioner) 2. As a result, data is read / written. The optical head 2 includes an objective lens 20 for irradiating the optical disc 1 with laser light, an actuator 21 for driving the objective lens 20 in a direction across the track of the optical disc 1, and a lens position detector for detecting the position of the objective lens 20. 22.
[0018]
A VCM (voice coil motor) 23 moves the optical head 2 in a direction across the track of the optical disk 1.
[0019]
A DSP (digital signal processor) 3 samples a track error signal TES during on-track by a sample timer interrupt of 40 kHz to 50 kHz to obtain a position error from the track center. Then, a control amount is created. Similarly, during the seek process, a control amount is created from the track error signal TES as will be described with reference to FIG.
[0020]
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.
[0021]
The first digital / analog converter 40 converts the track offset value from the host MPU 5 into an analog quantity. The adder 41 adds the output (track offset amount) of the first digital / analog converter 40 to the track error signal TES.
[0022]
The secondary low-pass filter 42 is an analog low-pass filter that cuts a high-frequency component of the track error signal TES. The cut-off frequency is set to 20 kHz. The first analog / digital converter 43 converts the analog track error signal TES from the low-pass filter 42 into a digital value.
[0023]
The track error signal TES is a well-known signal obtained from a four-divided photodetector (not shown) of the optical head 2. The track error signal TES forms a sine wave of one cycle every track crossing.
[0024]
As shown in FIG. 2, the 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.
[0025]
As shown in FIG. 3, the track counter circuit 45 is for detecting the position of the light beam from the track zero cross signal TZC.
[0026]
The secondary low-pass filter 46 is an analog low-pass filter that cuts a high-frequency component of the lens position signal LPOS from the lens position detector 22. The second analog / digital converter 47 converts the analog lens position signal LPOS from the low-pass filter 46 into a digital value.
[0027]
The second digital / analog converter 48 converts the pseudo track error signal from the DSP 3 into an analog quantity. This pseudo track error signal is obtained by adding a predetermined gain to the track error signal input from the first analog / digital converter 43 by the DSP 3. The pseudo track error signal is monitored, and the track offset value is adjusted so that the value is vertically symmetric.
[0028]
The third digital / analog converter 49 converts the actuator control value from the DSP 3 into an analog quantity. The drive circuit 50 drives the actuator 21 based on the output of the third digital / analog converter 49.
[0029]
The fourth digital / analog converter 51 converts the VCM control value from the DSP 3 into an analog quantity. The drive circuit 52 drives the VCM 23 by the output of the fourth digital / analog converter 51.
[0030]
Next, the zero cross comparator 44 will be described with reference to FIG. As shown in FIG. 2, the addition amplifier 53 subtracts the track offset amount from the first digital / analog converter 40 from the reference voltage. The track error signal TES is a signal centered on the reference voltage Vref, but includes a DC component such as a circuit offset. For this reason, the DC component is corrected by the track offset value measured in advance. R3, R4, and R5 are resistors.
[0031]
The comparator 54 compares the corrected reference voltage from the addition amplifier 53 with the track error signal TES, and outputs a track zero cross signal TZC. The comparator 54 positively feeds back the digital voltage after slicing via resistors R1 and R2 and a capacitor C.
[0032]
This gives hysteresis characteristics to the comparator 54, making it insensitive to noise. As a result, noise such as ID 髭 is not detected in the track error signal TES.
[0033]
The feedback amount is made variable by turning on / off the switch SW1 provided in the positive feedback route. When the speed of the light beam is relatively slow, the switch SW1 is turned on to increase the feedback amount. This prevents malfunctions due to noise.
[0034]
On the other hand, when the speed at which the amplitude of the track error signal TES decreases is relatively fast, the switch SW1 is turned off to reduce the feedback amount. Thus, control is performed so that the zero crossing of the track error signal TES can be reliably detected.
[0035]
The switch SW1 is controlled from the DSP 3. The DSP 3 turns off the switch SW1 when the speed exceeds the reference speed by speed detection described later.
[0036]
Next, the track counter circuit 45 will be described with reference to FIG. As shown in FIG. 3, the zero cross pulse generation circuit 60 generates an edge pulse by synchronizing the track zero cross signal TZC with the system clock.
[0037]
The latch pulse generation circuit 61 creates a latch pulse from the latch signal from the DSP 3. The interval counter 62 counts the interval between edge pulses (track zero cross signal TZC) by counting the system clock.
[0038]
The interval latch circuit 63 latches the output of the interval counter 62 according to the edge pulse. The data holding latch circuit 64 holds the data of the latch circuit 63 by a latch pulse. The output of the latch circuit 64 indicates the latest zero cross interval value A. The output of the latch circuit 64 is output to the DSP 3.
[0039]
The load pulse generation circuit 65 generates a load pulse in response to a load signal (write) from the DSP 3. The inverter 66 inverts the target track number from the DSP 3. The crossing track counter 67 is loaded with an inversion signal of the target track number (complement of the target track number) according to the load pulse. Then, the crossing track counter 67 counts edge pulses from the load value.
[0040]
The data holding latch circuit 68 latches the count value of the interval counter 62 according to the latch pulse. The output of the latch circuit 68 indicates the count value B from the latest zero cross to the present (when a latch pulse is generated). The output of the latch circuit 68 is output to the DSP 3.
The data holding latch circuit 69 latches the count value of the transverse track counter 67 according to the latch pulse. The output of the latch circuit 69 indicates the number of remaining tracks Xr. The output of the latch circuit 68 is output to the DSP 3.
[0041]
4A, 4B, and 4C are firmware configuration diagrams of the DSP 3, FIG. 5 is a flowchart of seek command processing in FIG. 4C, and FIG. 6 is an explanatory diagram of the seek processing. .
[0042]
As shown in FIG. 4A, the DSP 3 initializes the memory and enters an idle state. If there is an interrupt in the idle state, interrupt processing is executed.
[0043]
When there is a sampling interrupt, the sampling interrupt process shown in FIG. 4B is executed. This sampling interrupt process will be described.
[0044]
(S1) First, the DSP 3 executes a VCM calculation process for calculating a control amount of the VCM described later with reference to FIG.
[0045]
(S2) Next, the DSP 3 executes a LPOS calculation process 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 amount is calculated so that the position error obtained from the lens position signal LPOS signal becomes zero. Based on this control amount, the track actuator 21 is controlled via the digital / analog converter 49 and the drive circuit 50 to control the optical head 2 so that the lens 20 is positioned at the center.
[0046]
(S3) Next, the DSP 3 executes focus calculation processing for calculating the control amount of the focus position.
[0047]
(S4) Further, the DSP 3 executes a track calculation process for calculating a control amount of the track actuator, which will be described later with reference to FIG. And it ends.
[0048]
If there is an interrupt from the host MPU 5, the host interface interrupt process shown in FIG. 4C is executed. In this interrupt process, the command is analyzed and the command is executed.
[0049]
In this command execution, processing of the seek command will be described with reference to FIG.
[0050]
(S10) Upon receiving the seek command, seek difference and seek direction, the DSP 3 sets the lens acceleration end track position LAE. The LAE is predetermined as “0.3” track.
[0051]
(S11) Next, the DSP 3 sets the lens constant speed end track position LCE. The LCE is predetermined to “4” tracks.
[0052]
(S12) The DSP 3 sets the acceleration end position PAE of the positioner 2 to X1. This value X1 is set to "3000" track if the difference DIF is 6000 tracks or more. On the other hand, if the difference DIF does not exceed 6000 tracks, [DIF] / 2 is set.
[0053]
(S13) Next, the DSP 3 sets the constant speed end position PCE of the positioner 2 to X2. This value X2 is set to ([DIF] -3000) tracks if the difference DIF is 6000 tracks or more. On the other hand, when the difference DIF does not exceed 6000 tracks, X1 is set.
[0054]
(S14) The DSP 3 sets the deceleration end track position PBE of the positioner 2 to X3. The value X3 is ([DIF] -4) tracks.
[0055]
(S15) The DSP 3 sets the lens constant speed end position LBS to X4. This value X4 is ([DIF] -0.3) tracks.
[0056]
(S16) The DSP 3 sets the lens deceleration end position LBE to the difference [DIF].
[0057]
(S17) Finally, the DSP 3 sets the seek status signal SKSTS to “1” (lens acceleration) and ends.
[0058]
By this seek command processing, the seek processing mode up to the target track is determined. As shown in FIG. 6, the track acceleration period from the track “0” to the track LAE (0.3) is a lens acceleration period. The seek status signal SKSTS is “1”.
[0059]
From the track LAE to the track LCE (4) is a lens constant speed period. The seek status signal SKSTS is “2”. From the track LCE to the track PAE (= X1) is a positioner acceleration period. The seek status signal SKSTS is “3”.
[0060]
From the track PAE to the track PCE (= X2) is a positioner constant speed period. The seek status signal SKSTS is “4”. From the track PCE to the track PBE (= X3) is a positioner deceleration period. The seek status signal SKSTS is “5”.
[0061]
From the track PBE to the track LBS (= X4) is a lens constant speed period. The seek status signal SKSTS is “6”. From the track LBS to the track LBE is a lens deceleration period. The seek status signal SKSTS is “7”. When the seek status signal SKSTS is “0”, it indicates fine control during on-track.
[0062]
These seek status signals SKSTS are stored in a register. In this way, each acceleration, constant speed, and deceleration period is set according to the seek difference.
[0063]
7 is a VCM calculation process flowchart in FIG. 4B, FIG. 8 is a track calculation process flowchart in FIG. 4B, FIG. 9 is a SKSTS determination process flowchart in FIG. 8, and FIGS. Is a flowchart of the target position calculation process in FIG. 8, and FIG. 14 is an explanatory diagram of the target position calculation process.
[0064]
The VCM calculation process will be described with reference to FIG.
[0065]
(S21) The DSP 3 checks whether the seek status signal SKSTS is other than “0”. If the seek status signal SKSTS is not “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 control amount is calculated so that the position error becomes zero, and the track actuator 21 is controlled.
[0066]
(S22) Conversely, if the seek status signal SKSTS is other than “0”, the seek process is in progress. The DSP 3 calculates the target speed Vt. The target speed Vt is obtained by [target position at previous sampling interrupt]-[target position at current sampling interrupt]. These target positions are obtained by the track calculation process of FIG.
[0067]
(S23) Next, the DSP 3 calculates the current speed Vp. The current speed Vp is obtained by [current position at previous sampling interrupt] − [current position at current sampling interrupt]. This current position is obtained by the track calculation process of FIG.
[0068]
(S24) Next, the DSP 3 calculates the speed error ΔV by the following equation.
[0069]
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 amount.
[0070]
(S26) Further, the DSP 3 adds the feedforward amount to the obtained control amount when the VCM feedforward flag is on (“1”). This feed forward amount is an acceleration amount α. is there.
[0071]
(S27) Finally, the DSP 3 outputs the obtained control amount to the VCM digital / analog converter (DAC) 51. This completes the VCM calculation process.
[0072]
Next, the track calculation process will be described with reference to FIGS.
[0073]
(S30) The DSP 3 determines the seek status signal SKSTS by the process of FIG. 9 described later. When the seek status signal SKSTS is “0”, on-track control is performed as described above for fine control.
[0074]
(S31) If the seek status signal SKSTS is not “0”, the DSP 3 calculates a target position corresponding to each seek status. The calculation of the target position will be described later with reference to FIGS.
[0075]
(S32) Next, the DSP 3 calculates the current position, which will be described later with reference to FIG.
[0076]
(S33) Next, the DSP 3 calculates a position error. As will be described later with reference to FIG. 19, the position error POSERR is obtained by calculating [target position]-[current position].
[0077]
(S34) Next, the DSP 3 performs PID (proportional / integral / derivative) calculation.
[0078]
(S35) Furthermore, the DSP 3 adds the feedforward amount to the obtained control amount when the lens feedforward flag is on (“1”). This feed forward amount is an acceleration amount α.
[0079]
(S36) Finally, the DSP 3 outputs the obtained control amount to the digital / analog converter (DAC) 49 of the actuator coil. Thus, the track calculation process is finished.
[0080]
As shown in FIG. 9, the SKSTS determination process is a process of determining the seek status based on the seek status signal SKSTS as described with reference to FIG. That is, if the seek status signal SKSTS is “0”, fine control is performed. If the seek status signal SKSTS is “1”, lens acceleration control is performed.
[0081]
If the seek status signal SKSTS is “2”, the lens constant speed control is performed. If the seek status signal SKSTS is “3”, positioner acceleration control is performed. If the seek status signal SKSTS is “4”, the positioner constant speed control is performed. If the seek status signal SKSTS is “5”, positioner deceleration control is performed.
[0082]
If the seek status signal SKSTS is “6”, the lens constant speed control is performed. If the seek status signal SKSTS is “7”, lens deceleration control is performed.
[0083]
In this way, the seek status is determined, and each target position calculation process of FIGS. 10A to 13 is performed.
[0084]
A target position calculation process in lens acceleration will be described with reference to FIG.
[0085]
(S40) The DSP 3 calculates the target position TAGPOS. As shown in FIG. 14, acceleration and deceleration are performed using a constant acceleration α. For this reason, the target position x in acceleration is expressed by the following equation, where the acceleration of the lens is α1 and the time is t.
[0086]
x = α1 · t2 / 2 (2)
(S41) Next, the DSP 3 determines whether or not the target position TAGPOS has exceeded the lens acceleration end position LAE.
[0087]
(S42) If the target position TAGPOS exceeds the lens acceleration end position LAE, the DSP 3 changes the seek status signal SKSTS to “2” (lens constant speed) because the lens acceleration period is exceeded.
[0088]
(S43) Then, the DSP 3 sets the lens feed forward flag to “0” (no feed forward addition), and ends.
[0089]
(S44) On the other hand, if the target position TAGPOS does not exceed the lens acceleration end position LAE, the DSP 3 is still in the lens acceleration period. Therefore, the DSP 3 sets the lens feedforward flag to “1” (with feedforward addition) and ends.
[0090]
Next, the target position calculation process at a constant lens speed will be described with reference to FIG.
[0091]
(S45) The DSP 3 calculates the target position TAGPOS. As shown in FIG. 14, the constant speed period is a period in which the acceleration is zero. For this reason, the target position x at a constant speed is expressed by the following equation, where acceleration is α1, time is t, and acceleration end time is t1.
[0092]
x = α1 · t2 / 2 + α1 (t−t1) (3)
(S46) Next, the DSP 3 determines whether or not the target position TAGPOS has exceeded the lens constant speed end position LCE. The DSP 3 ends if the target position TAGPOS does not exceed the lens constant speed end position LCE.
[0093]
(S47) When the target position TAGPOS exceeds the lens constant speed end position LCE, the DSP 3 changes the seek status signal SKSTS to “3” (positioner acceleration) because the lens constant speed period is exceeded. And it ends.
[0094]
Next, the target position calculation process in the positioner acceleration will be described with reference to FIG.
[0095]
(S48) The DSP 3 calculates the target position TAGPOS. As shown in FIG. 14, acceleration is performed using a constant acceleration α2. For this reason, the target position x in acceleration is defined as follows: the acceleration of the positioner is α2, the time is t, the lens acceleration end time is t2, the lens acceleration end position is x2, and the speed at the lens acceleration end position is v2. Then, it is shown by the following formula.
[0096]
x = α2 · (t−t2) 2/2 + x2 + v2 (t−t2) (4)
(S49) Next, the DSP 3 determines whether or not the target position TAGPOS has exceeded the positioner acceleration end position PAE.
[0097]
(S50) If the target position TAGPOS exceeds the positioner acceleration end position PAE, the DSP 3 changes the seek status signal SKSTS to “4” (positioner constant speed) because it exceeds the positioner acceleration period.
[0098]
(S51) Then, the DSP 3 sets the VCM feedforward flag to “0” (no feedforward addition) and ends.
[0099]
(S52) On the other hand, the DSP 3 is still in the positioner acceleration period unless the target position TAGPOS exceeds the positioner acceleration end position PAE. Therefore, the DSP 3 sets the VCM feedforward flag to “1” (with feedforward addition) and ends.
[0100]
Next, the target position calculation process at the constant positioner speed will be described with reference to FIG.
[0101]
(S53) The DSP 3 calculates the target position TAGPOS. As shown in FIG. 14, the constant speed period is a period in which the acceleration is zero. Therefore, the target position x at a constant speed is expressed by the following equation, where acceleration is α1, time is t, positioner acceleration end time is t3, positioner acceleration end position is x3, and positioner acceleration end speed is v3. Indicated by
[0102]
x = x3 + v3 (t−t3) (5)
(S54) Next, the DSP 3 determines whether or not the target position TAGPOS has exceeded the positioner constant speed end position PCE. The DSP 3 ends if the target position TAGPOS does not exceed the positioner constant speed end position PCE.
[0103]
(S55) When the target position TAGPOS exceeds the positioner constant speed end position PCE, the DSP 3 changes the seek status signal SKSTS to “5” (positioner deceleration) because it exceeds the positioner constant speed period. And it ends.
[0104]
Next, the target position calculation process in positioner deceleration will be described with reference to FIG.
[0105]
(S56) The DSP 3 calculates the target position TAGPOS. As shown in FIG. 14, the deceleration is performed using a constant deceleration rate α2. For this reason, the target position x for deceleration is α2 for the positioner acceleration, t for the time, t4 for the positioner acceleration end time, x4 for the positioner acceleration end position, and v4 for the speed at the positioner acceleration end position. Then, it is shown by the following formula.
[0106]
x =-. alpha.2.multidot. (t-t4) @ 2/2 + x4 + v4 (t-t4) (6)
(S57) Next, the DSP 3 determines whether or not the target position TAGPOS has exceeded the positioner deceleration end position PBE.
[0107]
(S58) If the target position TAGPOS exceeds the positioner deceleration end position PBE, the DSP 3 changes the seek status signal SKSTS to “6” (lens constant speed) because it exceeds the positioner deceleration period.
[0108]
(S59) Then, the DSP 3 sets the VCM feedforward flag to “0” (no feedforward addition) and ends.
[0109]
(S60) On the other hand, the DSP 3 is still in the positioner deceleration period unless the target position TAGPOS exceeds the positioner deceleration end position PBE. Therefore, the DSP 3 sets the VCM feedforward flag to “1” (with feedforward addition) and ends.
[0110]
Next, target position calculation processing at a constant lens speed will be described with reference to FIG.
[0111]
(S61) The DSP 3 calculates the target position TAGPOS. As shown in FIG. 14, the constant speed period is a period in which the acceleration is zero. For this reason, the target position x at the constant speed is expressed by the following formula, where time is t, positioner deceleration end time is t5, positioner deceleration end position is x5, and positioner deceleration end speed is v5.
[0112]
x = x5 + v5 (t−t5) (7)
(S62) Next, the DSP 3 determines whether or not the target position TAGPOS has exceeded the lens constant speed end position LBS. The DSP 3 ends if the target position TAGPOS does not exceed the lens constant speed end position LBS.
[0113]
(S63) If the target position TAGPOS exceeds the lens constant speed end position LBS, the DSP 3 changes the seek status signal SKSTS to “7” (lens deceleration) because the lens constant speed period is exceeded. And it ends.
[0114]
Next, the target position calculation process in lens deceleration will be described with reference to FIG.
[0115]
(S64) The DSP 3 calculates the target position TAGPOS. As shown in FIG. 14, deceleration is performed using a constant deceleration −α1. For this reason, the target position x for deceleration is α1 for the lens acceleration, t for the time, t6 for the lens constant speed end time, x6 for the lens constant speed end position, and the speed at the lens constant speed end position. Is represented by the following formula.
[0116]
x = −α1 · (t−t6) 2/2 + x6 + v6 (t−t6) (8)
(S65) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the lens deceleration end position LBE.
[0117]
(S66) When the target position TAGPOS exceeds the lens deceleration end position LBE, the DSP 3 changes the seek status signal SKSTS to “0” (fine control) because the lens deceleration period is exceeded.
[0118]
(S67) Then, the DSP 3 sets the VCM feedforward flag to “0” (no feedforward addition) and ends.
[0119]
(S68) On the other hand, if the target position TAGPOS does not exceed the lens deceleration end position LBE, the DSP 3 is still in the lens deceleration period. Therefore, the DSP 3 sets the VCM feedforward flag to “1” (with feedforward addition) and ends.
[0120]
Thus, the target position in each seek status is calculated.
[0121]
Next, the current position calculation step in FIG. 8 will be described.
[0122]
15 is a flowchart of the current position calculation process in FIG. 8, FIG. 16 is a flowchart of the calculation process from the analog value in FIG. 15, and FIGS. 17 and 18 are explanatory diagrams of the current position calculation.
[0123]
The current position calculation process will be described with reference to FIG.
[0124]
(S70) The DSP 3 determines whether the seek status signal SKSTS is “3” (positioner acceleration), “4” (positioner constant speed), or “5” (positioner deceleration).
[0125]
(S71) When the seek status signal SKSTS is “3”, “4”, or “5”, the DSP 3 determines that the speed of the light beam is high because of the positioner control period. For this reason, the amplitude of the track error signal is small. Accordingly, the position in one track is obtained from the value of the track counter circuit 45.
[0126]
As shown in FIG. 3, the DSP 3 obtains the latest zero cross interval A from the latch circuit 64 and the count number B from the latest zero cross to the present from the latch circuit 68. The latest zero cross interval A and the count number B from the latest zero cross to the present are in a relationship as shown in FIG. Then, the position in one track is obtained by B / A.
[0127]
(S72) On the other hand, if the seek status signal SKSTS is “1”, “2”, “6”, “7” other than “3”, “4”, “5”, the DSP 3 is in the lens control period. Determine that the speed of the light beam is slow. For this reason, the amplitude of the track error signal TES is sufficiently large. Therefore, the position in one track is obtained from the analog value of the track error signal TES.
[0128]
The DSP 3 samples the digital value of the track error signal TES from the first analog / digital converter 43. Next, the DSP 3 calculates the position in one track from the sample values as shown in FIG.
[0129]
(S73) When the position in one track is obtained in this way, the DSP 3 calculates the current position. For this reason, the DSP 3 obtains the remaining track number Xr of the latch circuit 69. As shown in FIG. 17, the number of remaining tracks Xr is subtracted from the seek distance (difference) D to obtain the number of crossing tracks. The current position is calculated by adding the position in one track to this. Thus, the current position calculation process is terminated.
[0130]
In this way, when the speed of the light beam is high, the amplitude of the track error signal is small, so the current position is calculated from the digital value by the track zero cross signal TZC. On the other hand, when the speed of the light beam is low, the amplitude of the track error signal is large, so the current position is calculated from the analog value of the track error signal TES. Thus, an accurate current position can be obtained regardless of the speed of the light beam.
[0131]
Next, the process of calculating from the analog value in step S72 in FIG. 15 will be described with reference to FIGS. In this embodiment, the resolution of the first analog / digital converter 43 is fully used for the sine wave tracking error signal TES.
[0132]
(S74) For normalization, the DSP 3 multiplies the digital value ADCTES of the sampled track error signal TES by a constant C to obtain a digital value ADCTES.
[0133]
(S75) The DSP 3 determines whether or not the fraction of the target position calculated in the above-described FIG. 10A to FIG. 13 exceeds the 0.25 track. When the DSP 3 determines that the fraction of the target position does not exceed 0.25 track, the DSP 3 sets the position ADCPOS in one track to the digital value ADCTES. And it ends.
[0134]
(S76) When the DSP 3 determines that the fraction of the target position exceeds 0.25 track, the DSP 3 determines whether the fraction of the target position exceeds 0.75 track. When the DSP 3 determines that the fraction of the target position exceeds 0.75 tracks, the DSP 3 sets the position ADCPOS in one track to the digital value ADCTES. And it ends.
[0135]
(S77) If the DSP 3 determines that the fraction of the target position is not less than 0.25 track and not more than 0.75 track, the sign of the digital value ADCTES is inverted and set to -ADCTES.
[0136]
(S78) The DSP 3 determines whether the fraction of the target position exceeds 0.5. When the DSP 3 determines that the fraction of the target position exceeds 0.5, the position ADCPOS in one track is calculated as (digital value ADCTES−0.5 track). And it ends.
[0137]
(S79) When the DSP 3 determines that the fraction of the target position is 0.5 track or less, the position ADCPOS in one track is calculated as (digital value ADCTES + 0.5 track). And it ends.
[0138]
This operation will be described with reference to FIG. The range where the fraction of the target position does not exceed 0.25 track or the range where the fraction of the target position exceeds 0.75 track means that the fraction of the target position is within the range of ± 0.25 track. As shown in FIG. 18, in this range, the digital conversion value of the track error signal TES can be used.
[0139]
On the other hand, when the target position in one track is outside the range of ± 0.25 track, the sign of the digital value of the track error signal is inverted as shown in the figure. When the fraction of the target position exceeds 0.5 tracks (that is, when the target position in one track is between -0.25 track and -0.5 track), the track error signal ADCTES is set to 0. Subtract the value for 5 tracks.
[0140]
On the other hand, when the fraction of the target position does not exceed 0.5 tracks (that is, when the target position in one track is between 0.25 track and 0.5 track), the track error signal ADCTS is set to 0. Add the values for 5 tracks.
[0141]
In this way, when the position within one track is outside the range of ± 0.25 track, the signal is changed in polarity as indicated by the arrow in the figure. Therefore, it is possible to convert the sine wave track error signal into a digital value by making full use of the resolution of the analog / digital converter.
[0142]
Thus, since the track error signal TES is a sine wave, an accurate position cannot be detected in a rounded portion (in the range of X in the figure) near the peak as shown in FIG. If feedback control is applied at a portion where the position cannot be detected accurately, the control becomes unstable. For this reason, the control amount is set to zero in this portion.
[0143]
FIG. 19 is a flowchart of position error calculation processing for this purpose.
[0144]
(S80) The DSP 3 determines whether the fraction of the target position TAGPOS exceeds (0.25-X). Here, X indicates the length of the rounded section in the vicinity of the aforementioned peak, and is a range not exceeding 0.25 tracks. When the DSP 3 determines that the fraction of the target position TAGPOS does not exceed (0.25−X), the DSP 3 calculates the position error POSERR as (target position TAGPOS−current position ADCPOS).
[0145]
(S81) When the DSP 3 determines that the fraction of the target position TAGPOS exceeds (0.25-X), the DSP 3 determines whether the fraction of the target position TAGPOS exceeds (0.25 + X). If the fraction of the target position TAGPOS does not exceed (0.25 + X), the fraction of the target position is within the range of (0.25-X) to (0.25 + X), so the position error POSERR is set to zero. To do.
[0146]
(S82) If the DSP 3 determines that the fraction of the target position TAGPOS exceeds (0.25 + X), it determines whether the fraction of the target position TAGPOS exceeds (0.75-X). When the DSP 3 determines that the fraction of the target position TAGPOS does not exceed (0.75−X), the DSP 3 calculates the position error POSERR as (target position TAGPOS−current position ADCPOS).
[0147]
(S83) When the DSP 3 determines that the fraction of the target position TAGPOS exceeds (0.75-X), it determines whether the fraction of the target position TAGPOS exceeds (0.75 + X). If the fraction of the target position TAGPOS does not exceed (0.75 + X), the fraction of the target position is within the range of (0.75-X) to (0.75 + X), so the position error POSERR is set to zero. To do.
[0148]
(S84) When the DSP 3 determines that the fraction of the target position TAGPOS exceeds (0.75 + X), the DSP 3 calculates the position error POSERR as (target position TAGPOS−current position ADCPOS). And it ends.
[0149]
In this way, as shown in FIG. 18, in the section of the rounded portion near the peak of the track error signal TES, the position error is calculated as zero, thereby reducing the control amount to zero and instability of control. To prevent.
[0150]
Next, in order to achieve the same object, a method for setting the control output to zero will be described as a modification.
[0151]
FIG. 20 is a processing flowchart of a modified example of position error calculation, and FIG. 21 is a processing flowchart of actuator DAC output.
[0152]
(S85) First, the DSP 3 calculates the position error POSERR as (target position TAGPOS−current position ADCPOS).
[0153]
(S86) The DSP 3 determines whether the fraction of the target position TAGPOS exceeds (0.25-X). If the DSP 3 determines that the fraction of the target position TAGPOS does not exceed (0.25−X), the DSP 3 sets the gain GAIN to “1” and ends.
[0154]
(S87) When the DSP 3 determines that the fraction of the target position TAGPOS exceeds (0.25-X), it determines whether the fraction of the target position TAGPOS exceeds (0.25 + X). If the fraction of the target position TAGPOS does not exceed (0.25 + X), the fraction of the target position is within the range of (0.25-X) to (0.25 + X), so the gain GAIN is set to “0”. Set to. And it ends.
[0155]
(S88) If the DSP 3 determines that the fraction of the target position TAGPOS exceeds (0.25 + X), it determines whether the fraction of the target position TAGPOS exceeds (0.75-X). When the DSP 3 determines that the fraction of the target position TAGPOS does not exceed (0.75−X), the DSP 3 sets the gain GAIN to “1”. And it ends.
[0156]
(S89) When the DSP 3 determines that the fraction of the target position TAGPOS exceeds (0.75-X), it determines whether the fraction of the target position TAGPOS exceeds (0.75 + X). If the fraction of the target position TAGPOS does not exceed (0.75 + X), since the fraction of the target position is within the range of (0.75-X) to (0.75 + X), the gain GAIN is set to “0”. Set to. And it ends.
[0157]
(S90) If the DSP 3 determines that the fraction of the target position TAGPOS exceeds (0.75 + X), it sets the gain GAIN to “1”. And it ends.
[0158]
On the other hand, in the output process shown in FIG. 21 (step S36 in FIG. 8), the calculation result obtained by calculating the actuator DAC output in step S35 in FIG. 8 is multiplied by the aforementioned gain GAIN. Further, the offset value is added to calculate the output. Then, this result is output (written) to the digital / analog converter 49 of the actuator.
[0159]
Thus, as shown in FIG. 18, in the section X of the rounded portion near the peak of the track error signal TES, the control amount is set to zero by calculating the gain as zero, and the control is unstable. To prevent.
[0160]
Next, the PID calculation process shown in FIG. 8 will be described.
[0161]
FIG. 22 is a flowchart of the PID calculation process in FIG. 8, and FIG. 23 is an explanatory diagram of the PID calculation process.
[0162]
During seeking, the amount of movement at the sampling interval is large, and the position error is also large. For this reason, if an attempt is made to control the position error during seeking with the same error as during on-track (during fine control), it is necessary to lower the input gain during seeking. When the input gain is lowered, the PID filter characteristics as shown in FIG. 23 are shifted in frequency by the reduction of the input gain.
[0163]
As a result, the phase margin is reduced and the stability at the time of entering the track is lowered. Therefore, in this embodiment, during seek, PID calculation is performed using a compensation system parameter that allows a sufficient phase margin in anticipation of gain reduction.
[0164]
(S91) The integral term ioPE1 at the time of the current sampling during the fine control is obtained from the current position error PE1, the integral term ioPE0 at the time of the previous sampling during the fine control, and the integral constant Cio by the following equation.
[0165]
ioPE1 = PE1 + ioPE0 × Cio
Similarly, the integral term isPE1 at the current sampling during seek control is obtained from the current position error PE1, the integral term isPE0 at the previous sampling during seek control, and the integral constant Cis by the following equation.
[0166]
isPE1 = PE1 + isPE0 × Cis
(S92) Next, the integral term ioPE0 at the time of the previous sampling during the fine control is updated with the obtained integral term ioPE1. Similarly, the integral term isPE0 at the previous sampling during seek control is updated with the obtained integral term isPE1.
[0167]
(S93) Next, the differential dPE1 of the position error is obtained from the current position error PE1 and the previous position error PE0 by the following equation.
[0168]
dPE1 = PE1-PE0
(S94) The differential term dioPE1 at the time of the current sampling during the fine control is obtained from the current position error differential dPE1, the differential term dioPE0 at the time of the previous sampling during the fine control, and the differential constant Cdo by the following equation.
[0169]
dioPE1 = dPE1 + dioPE0 × Cdo
Similarly, the differential term disPE1 at the time of the current sampling during seek control is obtained from the current position error differential dPE1, the differential term at the previous sampling during seek control, disPE0, and the differential constant Cds by the following formula.
[0170]
disPE1 = dPE1 + disPE0 × Cds
(S95) Next, the differential term dioPE0 at the time of the previous sampling during the fine control is updated with the obtained differential term dioPE1. Similarly, the differential term disPE0 at the previous sampling during the seek control is updated with the obtained current differential term disPE1. Further, the previous position error PE0 is updated to the current position error PE1.
[0171]
(S96) Next, it is determined whether the seek status signal SKSTS is other than “0”. If the seek status signal SKSTS is “0”, since fine control is being performed (on-track), the gain is set to Gpo, Gio, and Gdo, and the PID value PID is obtained by the following equation.
[0172]
PID = Gpo · PE1 + Gio · ioPE1 + Gdo · dioPE1
If the seek status signal SKSTS is not "0", the seek control is being performed, and the PID value PID is obtained by the following equation with gains set to Gps, Gis, and Gds, respectively.
[0173]
PID = Gps · PE1 + Gis · isPE1 + Gds · disPE1
In this way, the integral constant that determines the cut-off frequency of the low-pass filter characteristic and the differential constant that determines the cut-off frequency of the high-pass filter characteristic are changed during seek and on-track.
[0174]
For this reason, a phase margin can be obtained even during seeking. This increases the stability when jumping into the track.
[0175]
Next, a modification of the current speed calculation described in FIG. 7 will be described.
[0176]
FIG. 24 is a flowchart of a modification of the current speed calculation process of FIG.
[0177]
In the seek control, the speed signal obtained from the track counter 45 includes the relative speed between the positioner 2 and the objective lens 20 in addition to the actual speed of the positioner 2. For this reason, it is necessary to subtract the relative speed from the obtained speed signal.
[0178]
A signal corresponding to the relative speed between the positioner 2 and the objective lens 20 is a differential value of the lens position signal LPOS. Therefore, this is subtracted from the speed signal to determine the actual speed of the positioner.
[0179]
That is, as shown in FIG. 24, the current position is acquired. The current speed Vp is obtained by the following equation using the current position Xp1, the current position Xp0 one sample before, the differentiated lens position signal dL, and the normalized gain Gh.
[0180]
Vp = Xp1-Xp0-dL · Gh
In this way, the actual speed of the positioner obtained by subtracting the relative speed between the positioner 2 and the objective lens 20 from the signal obtained from the track counter 45 can be obtained. The differentiated lens position signal dL is calculated by the LPOS calculation process (step S3) shown in FIG. For this reason, it can implement | achieve easily by diverting this calculation result.
[0181]
Next, feedforward control will be described. The feedforward control is effective as a technique for preventing a control delay. As shown in FIGS. 7 and 8, the feed forward value at the time of seek is given to each of the track actuator and the positioner according to the seek mode.
[0182]
The feedforward value is a value corresponding to the acceleration α1 used for target position addition in the case of a track actuator, and is a value corresponding to the acceleration α2 used for target speed calculation in the case of a positioner. .
[0183]
If the feedforward value is increased, a large acceleration amount can be obtained, so that the time to reach the target position is also increased. However, it is difficult to control during seeking. Since the acceleration performance of each of the track actuator and the positioner is proportional to the drive current below the saturation current of the drive circuit, it is desirable that the feedforward value be a value corresponding to the acceleration value.
[0184]
On the other hand, the VCM 23 that drives the positioner requires a large torque. For this reason, the coil of the VCM 23 has a large inductance component. As a result, the rise of current is delayed accordingly. Therefore, in this embodiment, the timing at which feed forward is given to the positioner is controlled faster than the timing at which the acceleration change occurs to prevent delay.
[0185]
FIG. 25 is a flowchart showing a modification of the seek command process for that purpose, FIGS. 26A to 27B are flowcharts showing a modification of the target position calculation process, and FIG. 28 is an explanatory diagram of the feedforward control. .
[0186]
The process of FIG. 25 is executed after the process described with reference to FIG.
[0187]
(S100) The DSP 3 sets the positioner acceleration start position PASF to (lens constant speed end position LCE-0.5 track). In other words, the conventional positioner acceleration start position is set to 0.5 track before that which is the lens constant speed end position LCE.
[0188]
(S101) The DSP 3 sets the positioner acceleration end position PAEF to (positioner acceleration end position PAE-10 track). That is, the conventional positioner acceleration end position (that is, the positioner constant speed start position) is set to 10 tracks before that which is PAE.
[0189]
(S102) The DSP 3 sets the positioner deceleration start position PBSF to (positioner constant speed end position PCE-10 track). That is, the positioner deceleration start position is set 10 tracks before the conventional positioner deceleration start position.
[0190]
(S103) The DSP 3 sets the positioner deceleration end position PBEF to (positioner deceleration end position PBE-0.5 track). That is, the positioner deceleration end position is set 0.5 track before the conventional positioner deceleration end position.
[0191]
Such positions PASF, PAEF, PBSF, and PBEF are illustrated in FIG.
[0192]
On the other hand, in the target position calculation process, the lens constant speed process shown in FIG. 10B is changed to FIG. 26A, and the positioner acceleration process shown in FIG. 11B, the positioner constant speed process shown in FIG. 11B is changed to FIG. 27A, and the positioner deceleration process shown in FIG. 12A is changed to FIG. .
[0193]
First, the target position calculation process at the constant lens speed in FIG. 26A will be described.
[0194]
(S104) The DSP 3 calculates the target position TAGPOS. The target position x at a constant speed is calculated by the above equation (3), where acceleration is α1, time is t, and acceleration end time is t1.
[0195]
(S105) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the positioner acceleration start position PASF. When the DSP 3 determines that the target position TAGPOS exceeds the positioner acceleration start position PASF, the DSP 3 has reached the feed forward start position, and therefore sets the VCM feed forward flag to on (“1”). Conversely, when the DSP 3 determines that the target position TAGPOS has not exceeded the positioner acceleration start position PASF, it has not yet reached the feed forward start position, so the VCM feed forward flag is turned off (“0”).
[0196]
(S106) Next, the DSP 3 determines whether or not the target position TAGPOS has exceeded the lens constant speed end position LCE. The DSP 3 ends if the target position TAGPOS does not exceed the lens constant speed end position LCE. On the other hand, when the target position TAGPOS exceeds the lens constant speed end position LCE, the DSP 3 changes the seek status signal SKSTS to “3” (positioner acceleration) because the lens constant speed period is exceeded. And it ends.
[0197]
Next, the target position calculation process in the positioner acceleration will be described with reference to FIG.
[0198]
(S107) The DSP 3 calculates the target position TAGPOS by the above-described equation (4).
[0199]
(S108) Next, the DSP 3 determines whether or not the target position TAGPOS exceeds the feedforward positioner acceleration end position PAEF. When the DSP 3 determines that the target position TAGPOS exceeds the positioner acceleration end position PAEF, the DSP 3 has reached the feed forward end position, and therefore sets the VCM feed forward flag to OFF (“0”). Conversely, if the DSP 3 determines that the target position TAGPOS has not exceeded the positioner acceleration end position PAEF, it has not yet reached the feedforward end position, and therefore turns on the VCM feedforward flag (“1”).
[0200]
(S109) Next, the DSP 3 determines whether or not the target position TAGPOS has exceeded the positioner acceleration end position PAE. If the target position TAGPOS exceeds the positioner acceleration end position PAE, the DSP 3 changes the seek status signal SKSTS to “4” (positioner constant speed) because it exceeds the positioner acceleration period. On the other hand, the DSP 3 is still in the positioner acceleration period if the target position TAGPOS does not exceed the positioner acceleration end position PAE. Therefore, it ends.
[0201]
Next, the target position calculation process at the constant positioner speed will be described with reference to FIG.
[0202]
(S110) The DSP 3 calculates the target position TAGPOS by the above-described equation (5).
[0203]
(S111) Next, the DSP 3 determines whether or not the target position TAGPOS has exceeded the positioner deceleration start position PBSF. When the target position TAGPOS exceeds the positioner deceleration start position PBSF, the DSP 3 enters the feed forward deceleration period, and turns on the VCM feed forward flag (“1”). Conversely, if the target position TAGPOS does not exceed the positioner deceleration start position PCE, the DSP 3 turns off the VCM feedforward flag (“0”).
[0204]
(S112) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the positioner constant speed end position PCE. The DSP 3 ends if the target position TAGPOS does not exceed the positioner constant speed end position PCE. On the other hand, when the target position TAGPOS exceeds the positioner constant speed end position PCE, the DSP 3 changes the seek status signal SKSTS to “5” (positioner deceleration) because the positioner constant speed period is exceeded. And it ends.
[0205]
Next, the target position calculation processing in positioner deceleration will be described with reference to FIG.
[0206]
(S113) The DSP 3 calculates the target position TAGPOS by the above-described equation (6).
[0207]
(S114) Next, the DSP 3 determines whether or not the target position TAGPOS has exceeded the feedforward positioner deceleration end position PBEF. When the DSP 3 determines that the target position TAGPOS exceeds the feedforward positioner deceleration end position PBEF, the DSP 3 sets the VCM feedforward flag to off (“0”) because the feedforward deceleration control period has ended. Conversely, if the DSP 3 determines that the target position TAGPOS has not exceeded the feedforward positioner deceleration end position PBEF, the DSP 3 has not finished the feedforward deceleration control period, and therefore turns on the VCM feedforward flag (“1”). ).
[0208]
(S115) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the positioner deceleration end position PBE. If the target position TAGPOS exceeds the positioner deceleration end position PBE, the DSP 3 changes the seek status signal SKSTS to “6” (lens constant speed) because it exceeds the positioner deceleration period. On the other hand, the DSP 3 is still in the positioner deceleration period unless the target position TAGPOS exceeds the positioner deceleration end position PBE. Therefore, it ends.
[0209]
In this manner, as shown in FIG. 28, the delay in the operation of the positioner 2 can be minimized by starting the feed forward before the acceleration / deceleration of the positioner 2 starts. As a result, the positioner can be moved at high speed.
[0210]
In addition, since the feedforward start and end positions are calculated in advance based on the position of the light beam, calculation processing at the target position can be executed at high speed.
[0211]
In addition to the above-described embodiments, the present invention can be modified as follows.
[0212]
(1) The method of calculating the current position is changed by determining the speed state of the light beam from the seek status signal, but the method of calculating the current position is changed by determining the speed of the light beam from the target speed or the current speed. May be.
[0213]
(2) Various optical disks such as a writable optical disk and a rewritable optical disk can be used as the optical disk.
[0214]
Although the present invention has been described with reference to the embodiments, various modifications can be made within the scope of the gist of the present invention, and these are not excluded from the scope of the present invention.
[0215]
【The invention's effect】
As described above, the present invention has the following effects.
[0216]
(1) Since phase compensation characteristics are changed during seek and on-track, high-speed seek and stable on-track control are possible, and stable seek control is realized.
[0217]
(2) Since it can be realized only by changing the phase compensation characteristic, it can be realized easily and simply.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of the present invention.
FIG. 2 is a circuit diagram of a zero-crossing comparator having the configuration of FIG.
FIG. 3 is a circuit diagram of a track counter circuit configured as shown in FIG. 1;
4 is a firmware configuration diagram of a DSP configured as shown in FIG. 1; FIG.
5 is a flowchart of seek command processing in FIG. 4. FIG.
6 is an explanatory diagram of the seek process of FIG. 5. FIG.
7 is a flowchart of the VCM calculation process in FIG. 4. FIG.
8 is a flowchart of track calculation processing in FIG. 4. FIG.
9 is a flowchart of the SKSTS determination process in FIG. 8. FIG.
FIG. 10 is a flowchart (part 1) of a target position calculation process in FIG. 8;
FIG. 11 is a flowchart (part 2) of a target position calculation process in FIG. 8;
12 is a target position calculation processing flowchart (part 3) in FIG. 8; FIG.
13 is a flowchart of the target position calculation processing in FIG. 8 (part 4).
FIG. 14 is an explanatory diagram of the target position calculation process of FIGS. 10 to 13;
15 is a flowchart of the current position calculation process in FIG.
16 is a flowchart of a calculation process from an analog value in FIG.
FIG. 17 is an explanatory diagram (part 1) of the current position calculation process of FIG. 15;
18 is an explanatory diagram (part 2) of the current position calculation process of FIG. 15;
19 is a flowchart of position error calculation processing in FIG. 8. FIG.
20 is a processing flowchart of a modified example of the position error calculation in FIG. 8. FIG.
21 is a flowchart of actuator DAC output processing in FIG. 8. FIG.
22 is a flowchart of PID calculation processing in FIG. 8. FIG.
FIG. 23 is an explanatory diagram of the PID calculation process of FIG. 22;
24 is a flowchart of the current speed calculation process in FIG.
25 is a flowchart of a modification of the seek command process in FIG.
FIG. 26 is a flowchart (No. 1) of a modification of the target position calculation process in FIG. 8;
FIG. 27 is a flowchart (No. 2) of a modified example of the target position calculation process in FIG. 8;
FIG. 28 is an explanatory diagram of feedforward control in the embodiment of FIGS. 25 to 27;
[Explanation of symbols]
1 Optical disk (optical storage medium)
2 Positioner
3 DSP
5 Host MPU
20 Objective lens
21 Track actuator
23 VCM
43 Analog / digital converter
44 Zero cross comparator
45 track counter circuit

Claims (3)

In a seek control method of an optical storage device for seek control of a light beam moving mechanism in order to seek a light beam from a track having an optical storage medium to a target track,
Calculating a target position;
Detecting a current position from a track error signal indicating a relative position of the light beam to the track;
During seek control, a feedback control amount is calculated so that the position error between the target position and the current position is zero. During fine control, a feedback control amount is set so that the position error due to the track error signal is zero. Calculating steps,
Controlling the light beam moving mechanism according to the feedback control amount,
Detecting the current position comprises:
When the moving speed of the light beam during the seek control is slow, the track error signal is converted from an analog / digital converter by an analog / digital converter, and the track zero cross signal is zero-crossed by the zero error circuit. A first current position detecting step for detecting the current position from a count value ;
When the moving speed of the light beam during the seek control is fast, the count value by the track zero cross signal obtained by zero crossing the track error signal by the zero cross circuit and the interval from the edge of the latest track zero cross signal to the sampling time are And a second current position detecting step for detecting the current position from a value divided by an interval of the track zero cross signal of
The step of calculating the feedback control amount includes:
Calculating the position error using a phase compensation coefficient ,
Calculating the phase compensation comprises:
The coefficients of the phase compensation calculation, the in seek control, using a different and in fine control coefficient of the light beam, depending on whether the seek control in either the fine control in, selects the phase compensation coefficient A seek control method for an optical storage device, comprising: a step. The step of calculating the phase compensation includes a step of selecting from the PID compensation coefficient during the seek control and the PID compensation coefficient during the fine control of the light beam depending on whether the seek control is being performed or the fine control is being performed. The seek control method for an optical storage device according to claim 1. In an optical storage device that seeks a light beam from a track with an optical storage medium to a target track,
An optical head for reading the optical storage medium;
A light beam moving mechanism for moving a light beam of the optical head;
A control unit for seek control of the light beam moving mechanism;
An analog / digital converter for analog / digital conversion of a track error signal indicating a relative position of the light beam to the track;
A zero-cross circuit that zero-crosses the track error signal and generates a track zero-cross signal,
The controller is
Calculate the target position, detect the current position from the track error signal, calculate the feedback control amount so that the position error between the target position and the current position becomes zero during seek control, and during fine control , Calculating a feedback control amount such that a position error due to the track error signal becomes zero, and controlling the light beam moving mechanism by the feedback control amount,
Further, the control unit detects the current position,
When the moving speed of the light beam in the seek control is slow, a signal obtained by the tracking error signal converted analog / digital, the detected current position and a count value of said track zero-cross signal from the zero crossing circuit ,
When the moving speed of the light beam during the seek control is high, the count value of the track zero cross signal from the zero cross circuit and the interval from the edge of the latest track zero cross signal to the sampling time are set to the latest track zero cross signal. Detect the current position from the value divided by the interval,
The control unit calculates the feedback control amount,
The position error is calculated using the phase compensation coefficient, and the phase compensation calculation coefficient is set to a different coefficient during the seek control than the fine control of the light beam during the seek control. Use to select the phase compensation coefficient depending on whether the seek control or the fine control is in progress
An optical storage device.

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