JP3539785B2 - Optical storage device seek control method and optical storage device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a seek control method of an optical storage device for performing a seek operation of a light beam to a target track of an optical storage medium.And optical storage deviceControl method for optical storage device using DSPAnd optical storage deviceAbout.
[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, a light beam is applied to the optical storage medium, and data is written to and read from the optical storage medium.
[0003]
This optical storage device performs a so-called seek operation for moving a light beam to a target track. 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 detecting the current position from such a track error signal, a technique for accurately detecting the current position even if the seek speed is increased is desired.
[0004]
[Prior art]
As a method of detecting the current position from the track error signal TES, a method of detecting the current position from the analog value of the track error signal is known. As a method for detecting the current position from another track error signal, the track error signal is zero-sliced to obtain a track zero cross signal TZC. A method of counting the track zero cross signal and detecting the current position is known.
[0005]
[Problems to be solved by the invention]
The cycle of the track error signal TES during seeking is as high as 500 kHz at the maximum speed. Therefore, for a sampling frequency of 50 kHz to 40 kHz of the digital servo, the number of tracks may reach 10 or more for one sample.
[0006]
The amplitude of the track error signal TES during seeking decreases as the speed increases. Therefore, in the method of obtaining the current position from the analog value of the track error signal, there is a problem that it is difficult to detect the current position with one track or less accuracy when the seek speed is high.
[0007]
In the method of calculating the current position from the track zero cross signal, the current position can be detected stably when the seek speed is high. However, when the seek speed is low, the speed is not stable. For this reason, the method of detecting the current position from the interval of the track zero cross signal has a problem that accurate position detection is difficult.
[0008]
An object of the present invention is a seek control method for an optical storage device for accurately detecting a current position during a seek.And optical storage deviceTo provide.
[0009]
Another object of the present invention is a seek control method for an optical storage device for detecting an optimum current position according to a speed during a seek.And optical storage deviceTo provide.
[0010]
[Means for Solving the Problems]
A first aspect of the present invention calculates a target position in a seek control method of an optical storage device for performing seek control of a light beam moving mechanism in order to perform a seek operation of a light beam from a track on 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; and calculating a feedback control amount such that an error between the target position and the current position becomes zero. And controlling the light beam moving mechanism by the feedback control amount. The step of detecting the current position includes the step of converting the track error signal into an analog / digital signal when the speed of the light beam is low. Analog-to-digital conversionA count value based on a track zero-cross signal obtained by zero-slicing the track error signal by a zero-cross circuit.A first current position detecting step of detecting the current position from the data signal; and, when the speed of the light beam is high, detecting the current position from a count value based on a track zero cross signal obtained by zero-slicing the track error signal by a zero cross circuit. A second current position detecting stepThe second current position detecting step includes a step of measuring a first interval of a rising or falling edge of the track zero cross signal, and a second interval from the edge immediately before a certain sampling time to the sampling time. Measuring an interval; and calculating the current position by dividing the second interval by the first interval.It is characterized by the following.
4. The optical storage device according to claim 3, wherein the optical beam seeks from a track on the optical storage medium to a target track, and a head for reading the optical storage medium, and a light beam moving mechanism for moving the light beam of the head. And a control mechanism for seek control of the light beam moving mechanism, the control mechanism calculates a head movement target position, and calculates a current position from a track error signal indicating a relative position of the light beam to the track. Detecting, calculating a feedback control amount such that an error between the target position and the current position becomes zero, controlling the light beam moving mechanism by the feedback control amount, and controlling the light beam moving mechanism. Is slow A first detecting means for detecting the current position from a signal obtained by converting the track error signal from analog to digital by an analog / digital converter and a count value based on a track zero cross signal obtained by zero-slicing the track error signal by a zero cross circuit. A current position detection operation is performed, and when the speed of the light beam is high, a first interval of a rising or falling edge of the track zero cross signal is measured, and a first interval from the edge immediately before a certain sampling time to the sampling time is measured. A second current position detecting operation for measuring the second interval and dividing the second interval by the first interval to calculate the current position is performed.
It is characterized by the following.
[0011]
Claim 2 of the present inventionAnd 4A seek control method for an optical storage device according to claim 1Or the optical storage device according to claim 3., The first current position detecting stepOr actionIs executed at the start of the seek and at the end of the seek.
[0018]
[Action]
According to the first aspect of the present invention, when the speed of the light beam is low, the current position is detected from the analog value of the track error signal TES. When the speed of the light beam is low, the amplitude of the track error signal TES is sufficiently large, so that the current position can be accurately detected from the analog value of the track error signal TES.
[0019]
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 the accurate current position is detected from the count value of the track zero cross signal.
[0020]
In addition, when the speed of the light beam is low, the value obtained from the A / D converted value of the track error signal and the count value of the track zero cross signal, and when the speed of the light beam is high, the value obtained from the interval of the track zero cross signal is used. Since the current position is detected from the count value of the track zero cross signal, the current position can be detected in any case with a resolution smaller than one track.During the seek, accurate current position detection becomes possible, and stable position control becomes possible.
[0030]
【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 figure, the focus-related servo configuration irrelevant to track access is omitted.
[0031]
The optical disc 1 is irradiated with laser light by an optical head (positioner) 2. Thus, data read / write is performed. 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 crossing a track of the optical disc 1, and a lens position detector for detecting a position of the objective lens 20. 22.
[0032]
▲ 2 ▼Moreover, when the speed of the light beam is low, the value obtained from the A / D converted value of the track error signal and the count value of the track zero cross signal, and when the light beam speed is high, the value obtained from the interval between the track zero cross signals is used. In order to detect the current position from the count value of the track zero cross signal, the current position can be detected in any case with a resolution smaller than one track, so that the accurate current position can be detected during a seek.Since it can be realized only by changing the method of obtaining the current position from the track error signal, it can be easily and simply realized.
[0033]
The DSP (Digital Signal Processor) 3 samples the 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 processing, a control amount is generated from the track error signal TES as described in FIG.
[0034]
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.
[0035]
The first digital / analog converter 40 converts the track offset value from the host MPU 5 into an analog amount. The adder 41 adds the output (track offset amount) of the first digital / analog converter 40 to the track error signal TES.
[0036]
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 cutoff 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.
[0037]
Note that the track error signal TES is a known signal obtained from a four-divided photodetector (not shown) of the optical head 2. The track error signal TES forms a one-cycle sine wave every time the track is traversed.
[0038]
As shown in FIG. 2, the zero cross comparator (zero cross circuit) 44 slices the track error signal TES by a reference voltage to generate a track zero cross signal TZC.
[0039]
The track counter circuit 45 detects the position of the light beam from the track zero cross signal TZC, as shown in FIG.
[0040]
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.
[0041]
The second digital / analog converter 48 converts the pseudo-track error signal from the DSP 3 into an analog quantity. The pseudo track error signal is obtained by the DSP 3 adding a predetermined gain to the track error signal input from the first analog / digital converter 43. The pseudo track error signal is monitored, and the track offset value is adjusted so that the value is vertically symmetric.
[0042]
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 by the output of the third digital / analog converter 49.
[0043]
The fourth digital / analog converter 51 converts the VCM control value from the DSP 3 into an analog amount. The drive circuit 52 drives the VCM 23 with the output of the fourth digital / analog converter 51.
[0044]
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. Therefore, the DC component is corrected based on the track offset value measured in advance. Note that R3, R4, and R5 are resistors.
[0045]
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. In the comparator 54, the digital voltage after slicing is positively fed back via the resistors R1 and R2 and the capacitor C.
[0046]
As a result, the comparator 54 is provided with a hysteresis characteristic and is insensitive to noise. As a result, noise such as an ID beard is not detected in the track error signal TES.
[0047]
The feedback amount is made variable by turning on / off a switch SW1 provided on 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 malfunction due to noise.
[0048]
On the other hand, if the speed at which the amplitude of the track error signal TES decreases is relatively high, the switch SW1 is turned off to reduce the feedback amount. In this way, control is performed so that the zero cross of the track error signal TES can be reliably detected.
[0049]
Control of the switch SW1 is performed from the DSP3. The DSP 3 turns off the switch SW1 when the speed exceeds a reference speed by speed detection described later.
[0050]
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.
[0051]
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 of the edge pulse (track zero cross signal TZC) by counting the system clock.
[0052]
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 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. Then, the output of the latch circuit 64 is output to the DSP 3.
[0053]
The load pulse generation circuit 65 generates a load pulse according to a load signal (write) from the DSP 3. The inverter 66 inverts the target number of tracks from the DSP 3. The crossing track counter 67 is loaded with an inverted 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.
[0054]
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.
[0055]
The data holding latch circuit 69 latches the count value of the crossing 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.
[0056]
4 (A), 4 (B), and 4 (C) are diagrams of the firmware configuration of the DSP 3, FIG. 5 is a flowchart of a seek command process in FIG. 4 (C), and FIG. 6 is an explanatory diagram of the seek process. .
[0057]
As shown in FIG. 4A, the DSP 3 initializes the memory and enters an idle state. In the idle state, if there is an interrupt, interrupt processing is executed.
[0058]
When there is a sampling interrupt, a sampling interrupt process shown in FIG. This sampling interruption process will be described.
[0059]
(S1) First, the DSP 3 executes a VCM calculation process for calculating a VCM control amount described later with reference to FIG.
[0060]
(S2) Next, the DSP 3 executes an LPOS calculation process for calculating a 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 such that the position error obtained by the lens position signal LPOS signal becomes zero is calculated. With 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 located at the center.
[0061]
(S3) Next, the DSP 3 executes a focus calculation process for calculating a control amount of the focus position.
[0062]
(S4) Further, the DSP 3 executes a track calculation process for calculating a control amount of the track actuator described later with reference to FIG. Then, the process ends.
[0063]
Further, when there is an interrupt from the host MPU 5, the host interface interrupt processing shown in FIG. In this interrupt processing, the command is analyzed and the command is executed.
[0064]
In this command execution, the processing of the seek command will be described with reference to FIG.
[0065]
(S10) Upon receiving the seek command, the seek difference, and the seek direction, the DSP 3 sets the lens acceleration end track position LAE. The LAE is predetermined to “0.3” tracks.
[0066]
(S11) Next, the DSP 3 sets the lens constant speed end track position LCE. The LCE is predetermined for “4” tracks.
[0067]
(S12) The DSP 3 sets the acceleration end position PAE of the positioner 2 to X1. If the difference DIF is equal to or more than 6000 tracks, this value X1 is set to “3000” tracks. On the other hand, if the difference DIF does not exceed 6000 tracks, [DIF] ÷ 2 is set.
[0068]
(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, if the difference DIF does not exceed 6000 tracks, X1 is set.
[0069]
(S14) The DSP 3 sets the deceleration end track position PBE of the positioner 2 to X3. The value X3 is ([DIF] -4) tracks.
[0070]
(S15) The DSP 3 sets the lens constant speed end position LBS to X4. This value X4 is ([DIF] -0.3) tracks.
[0071]
(S16) The DSP 3 sets the lens deceleration end position LBE to the difference [DIF].
[0072]
(S17) Finally, the DSP 3 sets the seek status signal SKSTS to "1" (lens acceleration), and ends the processing.
[0073]
By this seek command processing, a seek processing mode up to the target track is determined. As shown in FIG. 6, the period from the track “0” to the track LAE (0.3) is a lens acceleration period. The seek status signal SKSTS is “1”.
[0074]
The period from the track LAE to the track LCE (4) is a lens constant speed period. The seek status signal SKSTS is “2”. The period from the track LCE to the track PAE (= X1) is a positioner acceleration period. The seek status signal SKSTS is “3”.
[0075]
The period from the track PAE to the track PCE (= X2) is a positioner constant speed period. The seek status signal SKSTS is “4”. The period from the track PCE to the track PBE (= X3) is a positioner deceleration period. The seek status signal SKSTS is “5”.
[0076]
The period from the track PBE to the track LBS (= X4) is a lens constant speed period. The seek status signal SKSTS is "6". The period 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.
[0077]
These seek status signals SKSTS are stored in registers. In this way, each acceleration, constant speed, and deceleration period is set according to the seek difference.
[0078]
7 is a flowchart of the VCM calculation processing in FIG. 4B, FIG. 8 is a flowchart of the track calculation processing in FIG. 4B, FIG. 9 is a flowchart of the SKSTS determination processing 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.
[0079]
The VCM calculation process will be described with reference to FIG.
[0080]
(S21) The DSP 3 checks whether the seek status signal SKSTS is other than “0”. If the seek status signal SKSTS is not 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 a position error from the track center. Then, the track actuator 21 is controlled by calculating a control amount such that the position error becomes zero.
[0081]
(S22) Conversely, if the seek status signal SKSTS is other than "0", the seek process is in progress. The DSP 3 calculates a target speed Vt. The target speed Vt is obtained by [target position at previous sampling interruption] − [target position at current sampling interruption]. These target positions are obtained by the track calculation processing of FIG.
[0082]
(S23) Next, the DSP 3 calculates the current speed Vp. The current speed Vp is obtained by [current position at previous sampling interruption] − [current position at current sampling interruption]. This current position is obtained by the track calculation processing of FIG.
[0083]
(S24) Next, the DSP 3 calculates the speed error ΔV by the following equation.
[0084]
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.
[0085]
(S26) Further, when the VCM feed forward flag is ON ("1"), the DSP 3 adds the feed forward amount to the obtained control amount. This feedforward amount is the acceleration amount α. is there.
[0086]
(S27) Finally, the DSP 3 outputs the obtained control amount to the VCM digital / analog converter (DAC) 51. Thus, the VCM calculation process ends.
[0087]
Next, the track calculation processing will be described with reference to FIGS.
[0088]
(S30) The DSP 3 determines the seek status signal SKSTS by the processing of FIG. 9 described later. When the seek status signal SKSTS is “0”, on-track control is performed as described above for fine control.
[0089]
(S31) If the seek status signal SKSTS is not “0”, the DSP 3 calculates a target position according to each seek status. The calculation of the target position will be described later with reference to FIGS.
[0090]
(S32) Next, the DSP 3 calculates a current position described later with reference to FIG.
[0091]
(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].
[0092]
(S34) Next, the DSP 3 performs a PID (proportional / integral / derivative) calculation.
[0093]
(S35) Further, when the lens feed forward flag is ON ("1"), the DSP 3 adds the feed forward amount to the obtained control amount. This feedforward amount is the acceleration amount α.
[0094]
(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 processing ends.
[0095]
As shown in FIG. 9, the SKSTS determination process is a process of determining the status of a seek using 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.
[0096]
If the seek status signal SKSTS is “2”, it is lens constant speed control. If the seek status signal SKSTS is “3”, it is positioner acceleration control. If the seek status signal SKSTS is “4”, the positioner is at constant speed control. If the seek status signal SKSTS is “5”, the positioner deceleration control is performed.
[0097]
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.
[0098]
As described above, the seek status is determined, and the target position calculation processing of each of FIGS. 10A to 13 is performed.
[0099]
With reference to FIG. 10A, a description will be given of the target position calculation process in lens acceleration.
[0100]
(S40) The DSP 3 calculates a target position TAGPOS. As shown in FIG. 14, acceleration and deceleration are performed using a constant acceleration α. Therefore, the target position x in the acceleration is represented by the following equation, where the acceleration of the lens is α1, and the time is t.
[0101]
x = α1 · t^Two/ 2 (2)
(S41) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the lens acceleration end position LAE.
[0102]
(S42) If the target position TAGPOS exceeds the lens acceleration end position LAE, the DSP 3 changes the seek status signal SKSTS to "2" (constant lens speed) because the target acceleration exceeds the lens acceleration period.
[0103]
(S43) Then, the DSP 3 sets the lens feed forward flag to "0" (no feed forward addition), and ends.
[0104]
(S44) On the other hand, if the target position TAGPOS has not exceeded the lens acceleration end position LAE, the DSP 3 is still in the lens acceleration period. Therefore, the DSP 3 sets the lens feed forward flag to “1” (with feed forward addition) and ends the processing.
[0105]
Next, referring to FIG. 10B, a description will be given of the target position calculation process at the constant lens speed.
[0106]
(S45) The DSP 3 calculates a 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 the constant speed is represented by the following equation, where the acceleration is α1, the time is t, and the acceleration end time is t1.
[0107]
x = α1 · t^Two/ 2 + α1 (t-t1) (3)
(S46) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the lens constant speed end position LCE. The DSP 3 ends when the target position TAGPOS does not exceed the lens constant speed end position LCE.
[0108]
(S47) If 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 target position TAGPOS has exceeded the lens constant speed period. Then, the process ends.
[0109]
Next, referring to FIG. 11A, a description will be given of a target position calculation process in positioner acceleration.
[0110]
(S48) The DSP 3 calculates the target position TAGPOS. As shown in FIG. 14, the acceleration is performed using a constant acceleration α2. Therefore, the target position x in the acceleration is α2, the time of the positioner is α2, the time is t, the end time of the lens acceleration is t2, the end position of the lens acceleration is x2, and the speed at the end position of the lens acceleration is v2. Then, it is represented by the following equation.
[0111]
x = α2 · (t−t2)^Two/ 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.
[0112]
(S50) When 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) if the target position TAGPOS has exceeded the positioner acceleration period.
[0113]
(S51) Then, the DSP 3 sets the VCM feed forward flag to "0" (no feed forward addition) and ends the processing.
[0114]
(S52) On the other hand, if the target position TAGPOS has not exceeded the positioner acceleration end position PAE, the DSP 3 is still in the positioner acceleration period. Therefore, the DSP 3 sets the VCM feed forward flag to “1” (with feed forward addition) and ends the processing.
[0115]
Next, with reference to FIG. 11B, a description will be given of the target position calculation process at the positioner constant speed.
[0116]
(S53) The DSP 3 calculates a 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 the constant speed is represented by the following equation, where the acceleration is α1, the time is t, the acceleration end time of the positioner is t3, the acceleration end position of the positioner is x3, and the speed at the end of acceleration of the positioner is v3. Indicated by
[0117]
x = x3 + v3 (t−t3) (5)
(S54) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the positioner constant speed end position PCE. The DSP 3 ends when the target position TAGPOS does not exceed the positioner constant speed end position PCE.
[0118]
(S55) If 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 target position TAGPOS has exceeded the positioner constant speed period. Then, the process ends.
[0119]
Next, referring to FIG. 12A, a description will be given of a target position calculation process in positioner deceleration.
[0120]
(S56) The DSP 3 calculates the target position TAGPOS. As shown in FIG. 14, deceleration is performed using a constant deceleration α2. Therefore, the target position x in the deceleration is α2, the time of the positioner is α, the time is t, the end time of the positioner acceleration is t4, the end position of the positioner acceleration is x4, and the speed at the end position of the positioner acceleration is v4. Then, it is represented by the following equation.
[0121]
x = −α2 · (t−t4)^Two/ 2 + x4 + v4 (t-t4) (6)
(S57) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the positioner deceleration end position PBE.
[0122]
(S58) When the target position TAGPOS exceeds the positioner deceleration end position PBE, the DSP 3 changes the seek status signal SKSTS to "6" (constant lens speed) since the positioner deceleration period has been exceeded.
[0123]
(S59) Then, the DSP 3 sets the VCM feed forward flag to "0" (no feed forward addition) and ends the processing.
[0124]
(S60) On the other hand, if the target position TAGPOS has not exceeded the positioner deceleration end position PBE, the DSP 3 is still in the positioner deceleration period. Therefore, the DSP 3 sets the VCM feed forward flag to “1” (with feed forward addition) and ends the processing.
[0125]
Next, the target position calculation processing at the constant lens speed will be described with reference to FIG.
[0126]
(S61) The DSP 3 calculates a 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 the constant speed is represented by the following equation, where t is the time, t5 is the end time of deceleration of the positioner, x5 is the end position of deceleration of the positioner, and v5 is the speed at the end of deceleration of the positioner.
[0127]
x = x5 + v5 (t−t5) (7)
(S62) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the lens constant speed end position LBS. The DSP 3 ends when the target position TAGPOS does not exceed the lens constant speed end position LBS.
[0128]
(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 target position TAGPOS has exceeded the lens constant speed period. Then, the process ends.
[0129]
Next, referring to FIG. 13, a description will be given of a target position calculation process in lens deceleration.
[0130]
(S64) The DSP 3 calculates a target position TAGPOS. As shown in FIG. 14, deceleration is performed using a constant deceleration -α1. For this reason, the target position x in the deceleration is as follows: the acceleration of the lens is α1, the time is t, the end time of the lens constant speed is t6, the end position of the lens constant speed is x6, and the speed at the end position of the lens constant speed is Is represented by the following equation.
[0131]
x = −α1 · (t−t6)^Two/ 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.
[0132]
(S66) If 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 target position TAGPOS has exceeded the lens deceleration period.
[0133]
(S67) Then, the DSP 3 sets the VCM feed forward flag to “0” (no feed forward addition) and ends the processing.
[0134]
(S68) On the other hand, if the target position TAGPOS has not exceeded the lens deceleration end position LBE, the DSP 3 is still in the lens deceleration period. Therefore, the DSP 3 sets the VCM feed forward flag to “1” (with feed forward addition) and ends the processing.
[0135]
In this way, the target position at each seek status is calculated.
[0136]
Next, the current position calculation step in FIG. 8 will be described.
[0137]
FIG. 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.
[0138]
The current position calculation processing will be described with reference to FIG.
[0139]
(S70) The DSP 3 determines whether the seek status signal SKSTS is "3" (positioner acceleration), "4" (positioner constant speed), or "5" (positioner deceleration).
[0140]
(S71) If the seek status signal SKSTS is “3”, “4”, or “5”, the DSP 3 determines that the speed of the light beam is high for the positioner control period. For this reason, the amplitude of the track error signal is small. Therefore, the position in one track is obtained from the value of the track counter circuit 45.
[0141]
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 have a relationship as shown in FIG. Then, the position in one track is obtained by B / A.
[0142]
(S72) On the other hand, if the seek status signal SKSTS is “1”, “2”, “6”, or “7” other than “3”, “4”, or “5”, the DSP 3 performs the lens control period. It is determined that the speed of the light beam is low. 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.
[0143]
The DSP 3 samples the digital value of the track error signal TES from the first analog / digital converter 43. Next, as shown in FIG. 16, the DSP 3 calculates a position in one track from the sample value.
[0144]
(S73) When the position in one track is obtained in this way, the DSP 3 calculates the current position. Therefore, the DSP 3 obtains the number Xr of remaining tracks of the latch circuit 69. Then, as shown in FIG. 17, the number Xr of remaining tracks is subtracted from the seek distance (difference) D to obtain the number of crossing tracks. Then, the current position is calculated by adding the position in one track. Thus, the current position calculation processing ends.
[0145]
In this manner, 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 slow, the current position is calculated from the analog value of the track error signal TES because the amplitude of the track error signal is large. Thus, an accurate current position can be obtained regardless of the speed of the light beam.
[0146]
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 track error signal TES.
[0147]
(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.
[0148]
(S75) The DSP 3 determines whether or not the fraction of the target position calculated in FIGS. 10A to 13 does not exceed 0.25 tracks. When determining 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. Then, the process ends.
[0149]
(S76) When determining that the fraction of the target position exceeds 0.25 tracks, the DSP 3 determines whether the fraction of the target position exceeds 0.75 tracks. If 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. Then, the process ends.
[0150]
(S77) If the DSP 3 determines that the fraction of the target position is equal to or greater than 0.25 track and equal to or less than 0.75 track, the DSP 3 inverts the sign of the digital value ADCTES to −ADCTES.
[0151]
(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). Then, the process ends.
[0152]
(S79) If 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). Then, the process ends.
[0153]
This operation will be described with reference to FIG. The fact that the fraction of the target position does not exceed 0.25 tracks or exceeds 0.75 tracks means that the fraction of the target position is within ± 0.25 tracks. As shown in FIG. 18, a digitally converted value of the track error signal TES can be used in this range.
[0154]
On the other hand, if the target position in one track is out of the range of ± 0.25 tracks, 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 track (that is, when the target position in one track is between -0.25 track and -0.5 track), 0 is added to the track error signal ADCTES. .5 The value for 5 tracks is subtracted.
[0155]
On the other hand, when the fraction of the target position does not exceed 0.5 track (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. The values for five tracks are added.
[0156]
By doing so, if the position within one track is out of the range of ± 0.25 tracks, the signal is shifted and the polarity of the signal is changed as shown by the arrow in the figure. Therefore, a sine wave track error signal can be converted into a digital value by making full use of the resolution of the analog / digital converter.
[0157]
As described above, since the track error signal TES is a sine wave, an accurate position cannot be detected in a rounded portion near the peak (within the range of X in FIG. 18) as shown in FIG. If feedback control is applied in a portion where the position cannot be accurately detected, the control becomes unstable. Therefore, in this part, the control amount is set to zero.
[0158]
FIG. 19 is a flowchart of the position error calculation process for this purpose.
[0159]
(S80) The DSP 3 determines whether the fraction of the target position TAGPOS does not exceed (0.25-X). Here, X indicates the length of the above-mentioned rounded section near the peak, which is a range not exceeding 0.25 tracks. When determining 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).
[0160]
(S81) When determining that the fraction of the target position TAGPOS exceeds (0.25-X), the DSP 3 determines whether the fraction of the target position TAGPOS does not exceed (0.25 + X). If the fraction of the target position TAGPOS does not exceed (0.25 + X), the fraction of the target position is in the range of (0.25-X) to (0.25 + X), and the position error POSERR is set to zero. I do.
[0161]
(S82) When determining that the fraction of the target position TAGPOS exceeds (0.25 + X), the DSP 3 determines whether the fraction of the target position TAGPOS does not exceed (0.75-X). When determining 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).
[0162]
(S83) When determining that the fraction of the target position TAGPOS exceeds (0.75-X), the DSP 3 determines whether the fraction of the target position TAGPOS does not exceed (0.75 + X). If the fraction of the target position TAGPOS does not exceed (0.75 + X), the fraction of the target position is in the range of (0.75-X) to (0.75 + X), so that the position error POSERR is set to zero. I do.
[0163]
(S84) When determining 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). Then, the process ends.
[0164]
In this manner, 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, so that the control amount is set to zero and the control instability is reduced. To prevent
[0165]
Next, a method of setting the control output to zero to achieve the same object will be described as a modification.
[0166]
FIG. 20 is a processing flowchart of a modified example of the position error calculation, and FIG. 21 is a processing flowchart of the output of the actuator DAC.
[0167]
(S85) First, the DSP 3 calculates the position error POSERR as (target position TAGPOS-current position ADCPOS).
[0168]
(S86) The DSP 3 determines whether or not 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 the processing.
[0169]
(S87) When determining that the fraction of the target position TAGPOS exceeds (0.25-X), the DSP 3 determines whether the fraction of the target position TAGPOS does not exceed (0.25 + X). If the fraction of the target position TAGPOS does not exceed (0.25 + X), since the fraction of the target position is in the range of (0.25-X) to (0.25 + X), the gain GAIN is set to “0”. Set to. Then, the process ends.
[0170]
(S88) When determining that the fraction of the target position TAGPOS exceeds (0.25 + X), the DSP 3 determines whether the fraction of the target position TAGPOS does not exceed (0.75-X). When determining that the fraction of the target position TAGPOS does not exceed (0.75-X), the DSP 3 sets the gain GAIN to “1”. Then, the process ends.
[0171]
(S89) When determining that the fraction of the target position TAGPOS exceeds (0.75-X), the DSP 3 determines whether the fraction of the target position TAGPOS does not exceed (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 in the range of (0.75-X) to (0.75 + X), the gain GAIN is set to “0”. Set to. Then, the process ends.
[0172]
(S90) When determining that the fraction of the target position TAGPOS exceeds (0.75 + X), the DSP 3 sets the gain GAIN to “1”. Then, the process ends.
[0173]
On the other hand, in the output processing shown in FIG. 21 (step S36 in FIG. 8), the calculation result calculated in step S35 in FIG. 8 is multiplied by the gain GAIN of the actuator DAC output. Further, the output is calculated by adding the offset value. The result is output (written) to the digital / analog converter 49 of the actuator.
[0174]
In this manner, as shown in FIG. 18, in the section X of the rounded portion near the peak of the track error signal TES, the gain is calculated as zero so that the control amount is set to zero and the control instability is reduced. To prevent
[0175]
Next, the PID calculation processing shown in FIG. 8 will be described.
[0176]
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.
[0177]
During the seek, the movement amount at the sampling interval is large, and the position error is large. Therefore, if an attempt is made to control the position error during seek with the same error as during on-track (during fine control), it is necessary to reduce the input gain during seek. When the input gain is reduced, the filter characteristic of the PID is shifted in frequency by the decrease in the input gain as shown in FIG.
[0178]
As a result, the phase margin decreases, and the stability at the time of jumping into the track decreases. Therefore, in this embodiment, during the seek, PID calculation is performed by using a parameter of a compensation system that can obtain a sufficient phase margin in anticipation of a decrease in gain.
[0179]
(S91) The integral term ioPE1 at the time of the current sampling during the fine control is determined by the following equation 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.
[0180]
ioPE1 = PE1 + ioPE0 × Cio
Similarly, the integral term isPE1 at the time of the current sampling during the seek control is obtained by the following equation from the current position error PE1, the integral term isPE0 at the time of the previous sampling during the seek control, and the integral constant Cis.
[0181]
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 current integral term ioPE1 obtained. Similarly, the integral term isPE0 at the time of the previous sampling during the seek control is updated with the obtained integral term isPE1.
[0182]
(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.
[0183]
dPE1 = PE1-PE0
(S94) The differential term dioPE1 at the time of the current sampling during the fine control is obtained by the following equation from the differential dPE1 of the current position error, the differential term dioPE0 at the previous sampling during the fine control, and the differential constant Cdo.
[0184]
dioPE1 = dPE1 + dioPE0 × Cdo
Similarly, the differential term disPE1 at the time of the current sampling during the seek control is obtained by the following equation from the differential dPE1 of the current position error, the differential term disPE0 at the previous sampling during the seek control, and the differential constant Cds.
[0185]
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 current differential term dioPE1 obtained. Similarly, the differential term disPE0 during the previous sampling during the seek control is updated with the current differential term disPE1 obtained. Further, the previous position error PE0 is updated to the current position error PE1.
[0186]
(S96) Next, it is determined whether the seek status signal SKSTS is other than "0". If the seek status signal SKSTS is “0”, fine control is being performed (on track), and the PID value PID is obtained by the following equation with the gains being Gpo, Gio, and Gdo, respectively.
[0187]
PID = Gpo · PE1 + Gio · ioPE1 + Gdo · dioPE1
If the seek status signal SKSTS is not "0", the seek control is being performed, and the gain is Gps, Gis, and Gds, respectively, and the PID value PID is obtained by the following equation.
[0188]
PID = Gps · PE1 + Gis · isPE1 + Gds · disPE1
In this way, during the seek and during the on-track, the integral constant for determining the cutoff frequency of the low-pass filter characteristic and the differential constant for determining the cutoff frequency of the high-pass filter characteristic are changed.
[0189]
Therefore, a phase margin can be obtained even during a seek. Thereby, the stability when jumping into the track is increased.
[0190]
Next, a modified example of the calculation of the current speed described with reference to FIG. 7 will be described.
[0191]
FIG. 24 is a flowchart of a modification of the current speed calculation process of FIG.
[0192]
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. Therefore, it is necessary to subtract the relative speed from the obtained speed signal.
[0193]
The 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, the actual speed of the positioner is obtained by subtracting this from the speed signal.
[0194]
That is, as shown in FIG. 24, the current position is obtained. Then, the current speed Vp is obtained by the following equation from the current position Xp1, the current position Xp0 one sample before, the differentiated lens position signal dL, and the normalized gain Gh.
[0195]
Vp = Xp1 -Xp0 -dL · Gh
In this way, the actual speed of the positioner is obtained by removing 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 the calculation result.
[0196]
Next, the feedforward control will be described. Feedforward control is effective as a technique for preventing control delay. As shown in FIGS. 7 and 8, the feedforward value at the time of seek is given to each of the track actuator and the positioner according to the seek mode.
[0197]
The feedforward value is a value corresponding to the acceleration α1 used for adding the target position in the case of the track actuator, and a value corresponding to the acceleration α2 used for calculating the target speed in the case of the positioner. .
[0198]
If the feedforward value is increased, a large acceleration amount can be obtained, so that the time to reach the target position is also shortened. However, control during a seek becomes more difficult. 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.
[0199]
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 the current is slower. Therefore, in this embodiment, the timing of giving the feed forward to the positioner is controlled earlier than the timing at which the acceleration changes, thereby preventing a delay.
[0200]
FIG. 25 is a flowchart of a modified example of the seek command process for that purpose, FIGS. 26A to 27B are flowcharts of a modified example of the target position calculation process, and FIG. 28 is an explanatory diagram of the feedforward control. .
[0201]
The processing in FIG. 25 is additionally executed after the processing described in FIG.
[0202]
(S100) The DSP 3 sets the positioner acceleration start position PASF to (the lens constant speed end position LCE-0.5 track). That is, the positioner acceleration start position in the related art is set to 0.5 track before the lens constant speed end position LCE.
[0203]
(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 (ie, the positioner constant speed start position) is set to 10 tracks before the PAE.
[0204]
(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.
[0205]
(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 to 0.5 track before the conventional positioner deceleration end position.
[0206]
FIG. 28 shows such positions PASF, PAEF, PBSF, and PBEF.
[0207]
On the other hand, the process of calculating the target position in this case is different from the process of FIG. 10B in which the lens constant speed process is changed to that of FIG. 26A, and the process of accelerating the positioner shown in FIG. ), 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. 27B. .
[0208]
First, a description will be given of the target position calculation processing at the constant lens speed shown in FIG.
[0209]
(S104) The DSP 3 calculates the target position TAGPOS. The target position x at a constant speed is calculated by the above-described equation (3), where the acceleration is α1, the time is t, and the acceleration end time is t1.
[0210]
(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 has exceeded the positioner acceleration start position PASF, the DSP 3 has reached the feed forward start position, and sets the VCM feed forward flag to ON (“1”). Conversely, if the DSP 3 determines that the target position TAGPOS has not exceeded the positioner acceleration start position PASF, the DSP 3 sets the VCM feed forward flag to OFF ("0") because it has not yet reached the feed forward start position.
[0211]
(S106) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the lens constant speed end position LCE. The DSP 3 ends when the target position TAGPOS does not exceed the lens constant speed end position LCE. On the other hand, if 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 target position TAGPOS has exceeded the lens constant speed period. Then, the process ends.
[0212]
Next, the target position calculation process in the positioner acceleration will be described with reference to FIG.
[0213]
(S107) The DSP 3 calculates the target position TAGPOS according to the above-described equation (4).
[0214]
(S108) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the feedforward positioner acceleration end position PAEF. If the DSP 3 determines that the target position TAGPOS has exceeded the positioner acceleration end position PAEF, the DSP 3 has reached the feed forward end position, and thus 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, the DSP 3 sets the VCM feed forward flag to ON ("1") because it has not yet reached the feed forward end position.
[0215]
(S109) Next, the DSP 3 determines whether 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 the positioner acceleration period has been exceeded. On the other hand, if the target position TAGPOS does not exceed the positioner acceleration end position PAE, the DSP 3 is still in the positioner acceleration period. Therefore, the process ends.
[0216]
Next, the target position calculation process at the constant positioner speed will be described with reference to FIG.
[0217]
(S110) The DSP 3 calculates the target position TAGPOS according to the above-described equation (5).
[0218]
(S111) Next, the DSP 3 determines whether 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 turns on the VCM feedforward flag ("1") to enter a feedforward deceleration period. Conversely, if the target position TAGPOS does not exceed the positioner deceleration start position PCE, the DSP 3 turns off ("0") the VCM feed forward flag.
[0219]
(S112) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the positioner constant speed end position PCE. The DSP 3 ends when the target position TAGPOS does not exceed the positioner constant speed end position PCE. On the other hand, if 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. Then, the process ends.
[0220]
Next, with reference to FIG. 27B, a description will be given of a target position calculation process in positioner deceleration.
[0221]
(S113) The DSP 3 calculates the target position TAGPOS according to the above equation (6).
[0222]
(S114) Next, the DSP 3 determines whether the target position TAGPOS has exceeded the feedforward positioner deceleration end position PBEF. When determining that the target position TAGPOS has exceeded 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 feed forward positioner deceleration end position PBEF, the DSP 3 turns on the VCM feed forward flag (“1”) because the feed forward deceleration control period has not ended. ).
[0223]
(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" (constant lens speed) because the positioner deceleration period has been exceeded. On the other hand, if the target position TAGPOS does not exceed the positioner deceleration end position PBE, the DSP 3 is still in the positioner deceleration period. Therefore, the process ends.
[0224]
In this manner, as shown in FIG. 28, by starting the feed forward before the acceleration / deceleration of the positioner 2 starts, the delay of the operation of the positioner 2 can be minimized. This enables a high-speed movement of the positioner.
[0225]
In addition, since the start and end positions of the feedforward are calculated in advance based on the position of the light beam, the calculation processing at the target position can be executed at high speed.
[0226]
In addition to the embodiments described above, the present invention allows the following modifications.
[0227]
(1) The method of calculating the current position is changed by determining the speed state of the light beam from the seek status signal. However, 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.
[0228]
{Circle around (2)} Various types of optical disks, such as writable optical disks and rewritable optical disks, can be used.
[0229]
As described above, the present invention has been described with reference to the embodiments. However, various modifications are possible within the scope of the gist of the present invention, and these are not excluded from the scope of the present invention.
[0230]
【The invention's effect】
As described above, the present invention has the following effects.
[0231]
(1) Since the method of obtaining the current position from the track error signal is changed according to the speed of the light beam, the optimum current position can be detected according to the state of the track error signal, and stable seek control is realized.
[0232]
{Circle around (2)} Since it can be realized only by changing the method of obtaining the current position from the track error signal, it can be easily and simply realized.
[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 cross comparator having the configuration of FIG.
FIG. 3 is a circuit diagram of a track counter circuit having the configuration of FIG. 1;
FIG. 4 is a firmware configuration diagram of a DSP having the configuration of FIG. 1;
FIG. 5 is a flowchart of a seek command process in FIG. 4;
FIG. 6 is an explanatory diagram of a seek process in FIG. 5;
FIG. 7 is a flowchart of a VCM calculation process in FIG. 4;
FIG. 8 is a flowchart of a track calculation process in FIG. 4;
FIG. 9 is a flowchart of the SKSTS determination process in 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;
FIG. 12 is a flowchart (part 3) of a target position calculation process in FIG. 8;
FIG. 13 is a flowchart (part 4) of a target position calculation process in FIG. 8;
FIG. 14 is an explanatory diagram of the target position calculation processing of FIGS. 10 to 13;
FIG. 15 is a flowchart showing a current position calculation process in FIG. 8;
FIG. 16 is a flowchart of a calculation process from an analog value in FIG. 15;
FIG. 17 is an explanatory diagram (part 1) of the current position calculation process of FIG.
18 is an explanatory diagram (part 2) of the current position calculation process in FIG.
FIG. 19 is a flowchart of a position error calculation process in FIG. 8;
FIG. 20 is a processing flowchart of a modification of the position error calculation in FIG. 8;
FIG. 21 is a flowchart of an actuator DAC output process in FIG. 8;
FIG. 22 is a flowchart of a PID calculation process in FIG.
FIG. 23 is an explanatory diagram of the PID calculation processing in FIG. 22.
FIG. 24 is a flowchart showing a current speed calculation process in FIG. 7;
FIG. 25 is a flowchart of a modified example of the seek command process in FIG. 5;
FIG. 26 is a flowchart (part 1) of a modification of the target position calculation processing in FIG. 8;
FIG. 27 is a flowchart (part 2) of a modified example of the target position calculation processing 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 (4)

In order to perform a seek operation of a light beam from a track on an optical storage medium to a target track, in a seek control method of an optical storage device for performing seek control of a light beam moving mechanism,
Calculating a target position;
Detecting a current position from a track error signal indicating a relative position of the light beam to the track;
Calculating a feedback control amount such that an error between the target position and the current position becomes zero,
Controlling the light beam moving mechanism by the feedback control amount,
The step of detecting the current position includes:
When the speed of the light beam is slow, the track error signal is converted from an analog / digital signal by an analog / digital converter, and a count value based on a track zero cross signal obtained by zero-slicing the track error signal by a zero cross circuit. A first current position detecting step of detecting a current position;
When the speed of the light beam is high, it has a second current position detection step of detecting the current position of the track error signal by the zero-cross circuit from the count value by zero sliced track zero-cross signal,
The second current position detecting step includes:
Measuring a first interval of a rising or falling edge of the track zero cross signal;
Measuring a second interval from the edge immediately before a sampling time to the sampling time;
Calculating the current position by dividing the second interval by the first interval . The seek control method for an optical storage device according to claim 1,
The seek control method for an optical storage device, wherein the first current position detecting step is performed at the start of the seek and at the end of the seek. An optical storage device that seeks a light beam from a track on an optical storage medium to a target track,
A head for reading the optical storage medium,
A light beam moving mechanism for moving the light beam of the head,
A control mechanism for seek control of the light beam moving mechanism,
The control mechanism calculates a head movement target position, detects a current position from a track error signal indicating a relative position of the light beam to the track, and sets an error between the target position and the current position to zero. Calculating the feedback control amount, controlling the light beam moving mechanism by the feedback control amount,
The control mechanism includes:
When the speed of the light beam is slow, the track error signal is converted from an analog / digital signal by an analog / digital converter, and a count value based on a track zero cross signal obtained by zero-slicing the track error signal by a zero cross circuit. Perform a first current position detection operation for detecting the current position;
When the speed of the light beam is high, a first interval between rising and falling edges of the track zero cross signal is measured, and a second interval from the edge immediately before a certain sampling time to the sampling time is measured. Performing a second current position detecting operation of calculating the current position by dividing the second interval by the first interval.
An optical storage device, characterized in that: The optical storage device according to claim 3,
The control mechanism executes the first current position detection operation at the start of the seek and at the end of the seek
An optical storage device, characterized in that:

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