JPH09167358A - Track jump controller for optical recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a constant servo setting to a desired track position by restricting the level of the tracking error signal at the time of ending a track jump low even with respect to the dispersion and the change with time of characteristics of circuit system and an external disturbance, etc., even in an optical disk device of land/groove recording systems. SOLUTION: A pulse counting circuit 114 performs countings by detecting a tracking error signal TE and the zero-cross of the differential signal of the TE and detects the changeover timing of track jump pulses by the count value to output braking pulses. A track jump pulse control circuit 109 controls the braking pulses to be outputted to a tracking actuator 106 by using the moved distance L and the moveing velocity V of a light beam and the time T elapsed so as restrict the level of the TE at the time of completing the track jump low. moreover, a polarity inverting circuit 112 inverts the polarity of the TE according to the folow-up position after ending the track jump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track jump control device for performing a track jump in an optical recording / reproducing apparatus and enabling stable track pull-in of a tracking servo system.

[0002]

2. Description of the Related Art In recent years, a light beam from a light source is narrowed to a minute spot light by an optical system having an objective lens, and minute pits are recorded on a recording medium (hereinafter referred to as an optical disk) capable of optically recording and reproducing information. Alternatively, an optical recording / reproducing device (hereinafter referred to as an optical disc device) for reproducing the pits already recorded on the optical disc has been developed and is widely used as a storage device for a computer. In these optical disk devices, the optical pickup 101 is mounted in a direction substantially orthogonal to a concentric or spiral track of an optical disk (not shown) as shown in FIG. 11 for track following operation and access operation for searching a desired track. The tracking actuator 106 to be driven and the tracking actuator 1
06 including the optical pickup 101 for moving the optical pickup 101 in the radial direction of the optical disc (coarse movement motor 1).
010). In the track following operation, the tracking actuator 106 is driven by the output of the phase compensation circuit 103 corresponding to the polarity and level of the tracking error signal obtained by the tracking error signal detection circuit 102 from the output of the optical pickup 101, and the light beam is constantly tracked. The control is performed so as to follow the center.

On the other hand, in the access operation, the tracking servo loop is generally opened once and the coarse movement motor 1 is operated.
Optical pickup 101 to a desired track by 010
After moving, the tracking servo loop is closed again, the track following operation is performed, and the address information is read. If the read track address is not the desired track, the drive microcomputer 107 controls the track jump (fine seek) operation so that the light beam reaches the desired track.

The track jump is generally performed by an open loop control system that outputs a control current to the tracking actuator 106, so that a light beam spot can move to an adjacent track in a minimum time.
Controlled.

Next, the track is moved by one track 1
The bang-bang control in the track jump will be described. In FIG. 11, the drive microcomputer 107 outputs a mode switching signal 1C to switch from the tracking mode in which the tracking servo loop is closed to the track jump mode in which the tracking servo loop is opened. The bang-bang control pulse generator 1001 is
Since positive and negative pulse currents having the same amplitude as shown in FIG.
As shown in 3 (b), the light beam spot moves by one track. After the light beam spot moves by one track, that is, the pulse generator 1001 for bang-bang control
Drive microcomputer 1 after the output of the pulse current is finished
Reference numeral 07 closes the tracking servo loop by the mode switching signal 1C.

Here, the tracking actuator 10
If 6 has no spring system, the relationship between the arrival time Tb at which the velocity v (t) of the light beam becomes 0 and the switching time Tj between the jump pulse and the brake pulse at the travel distance (track pitch) of one track is Based on the jump start time Ts, Tj = Tb / 2, and the switching time Tj is exactly in the middle from the track jump start time Ts to the arrival time Tb. Therefore, the bang-bang control pulse generator 1
In 001, the jump pulse and the brake pulse should be output at the same time. Since the one-track jump is executed by the open-loop control system, after the bang-bang control pulse generator 1001 outputs the jump pulse and the brake pulse for a pre-calculated time, the drive microcomputer 107 closes the tracking servo loop and performs one track. The jump ends.

[0007]

Conventionally, as shown in FIGS. 12 (a) and 12 (b), a conventional optical disc apparatus is a groove recording in which data is recorded in a guide groove (groove portion) formed on the optical disc. The land recording method is generally used in which data is recorded in a portion called a land portion between the groove portion and the groove portion, but in recent years, as shown in FIG. 12 (c) in order to improve the recording density of the optical disc. A land / groove recording method for recording information on a land portion and a groove portion has been adopted.

Generally, an optical disc exchanges information with the outside at a constant length called a sector. Therefore, the address (track number, sector number, etc.) on the disk is pre-formatted together with the guide groove on the optical disk. In the land / groove recording, the land part and the groove part have the same track number and the same sector number. In the specification of the present invention, the land and the groove having the same ID are regarded as one track. The center of the track is the center of the land in the land and the center of the groove in the groove.

When performing a one-track jump in land / groove recording, when performing a one-track jump from the n-track groove, the n-track groove is moved to the n-track groove.
There are two types of jumps, ie, jumping to the land of +1 track or jumping to the groove of n + 1 track. As described above, the track jump control is performed so that positive and negative pulse currents having the same amplitude are simply output to move by one track pitch. Therefore, the desired track jump control cannot be performed.

Further, when performing the track following operation, the tracking actuator 106 is driven by the output of the phase compensation circuit 103 according to the polarity and level of the tracking error signal TE as described above, and the light beam is always at the track center. Is controlled so as to follow. When tracking the groove portion, from the tracking error signal shown in FIG. 2, the actuator moves to the outer peripheral side when the tracking error signal TE is negative, and moves to the inner peripheral side when TE is positive. Phase compensation circuit 10
3 must output the drive signal. However, in the case of following the land portion, the phase compensation circuit 10 moves so that the actuator moves to the outer peripheral side when TE is positive, and moves to the inner peripheral side when TE is negative.
3 is required to output the drive signal. Therefore, in the land portion and the groove portion, it is necessary to switch the polarity of the tracking error signal input to the phase compensation circuit 103 at the time of performing the follow-up operation, and the desired track is made to follow the land portion after movement or to follow the groove portion. It is necessary to set the polarity of the tracking error signal input to the phase compensation circuit 103 depending on whether to perform it.

On the other hand, the tracking error signal TE is shown in FIG.
Since it is a sinusoidal signal as shown in, it can be regarded as linear when the track deviation is near zero, but becomes non-linear when it exceeds the range. Therefore, if the timing to close the tracking servo loop at the end of the track jump is set to an arbitrary position, the servo operation may start from a non-linear region, and in that case, the non-linear servo will occur.
So-called limit cycles, oscillations, etc. may occur and the track pull-in operation may fail. Therefore, in order to perform the track pull-in operation stably, it is necessary to start the servo operation at least in the region where the tracking error signal is linear. Furthermore, even in the linear region, the level of the tracking error signal is large, and when the servo operation is started at a position away from the track center, the servo system shows a step response when a large step input is input.

Although this step response also depends on the damping of the servo system, overshoot usually occurs, and in the worst case, the pulling to the desired track fails. Since the amount of overshoot is proportional to the step response, the level of the tracking error signal may be low, that is, the servo operation may be started near the track center in order to reduce the overshoot. Therefore, in general, the light beam is on the track, and the tracking servo loop is closed at the position where the level of the tracking error signal is small.

However, in an actual optical disk device, the drive circuit 105 for driving the tracking actuator 106 and the tracking actuator 1
Due to disturbances such as variations in characteristics of 06 itself, changes over time, and disk eccentricity received during the track jump operation, the acceleration corresponding to the moving distance and speed of the light beam spot on the optical disk is the bang-bang control pulse generator 1001.
Is different from the predetermined acceleration set in advance by the output.
Therefore, when the drive microcomputer 107 closes the tracking servo loop after the bang-bang control pulse generator 1001 outputs the jump pulse and the brake pulse for a certain time in the track jump which moves by the track pitch, the tracking servo loop shown in FIGS. The moving distance and moving speed of the light beam spot as shown in () are not ideal values, ie, the moving speed is 0 and the moving distance is not the track pitch (the tracking error signal is 0). Therefore, when the movement distance of the light beam spot after one track jump (during tracking servo pull-in) is not equal to the track pitch TP, the track jump end time T is set as shown in FIG.
At b, the level of the tracking error signal TE is high, and the servo operation is started at a position away from the track center. Therefore, as described above, in the worst case, the tracking servo pull-in may fail.

As described above, the object of the present invention is to
Even in the track jump operation of the optical disk device that adopts the groove recording method, the tracking error signal level at the end of the track jump is large due to disturbance, variation in the characteristics of the circuit system, and secular change, and the light beam spot is located at a position away from the track center. It is an object of the present invention to provide a track jump control device that enables stable pulling of a tracking servo into a land or groove of a desired track even when the servo operation is started.

[0015]

To achieve the above object, in the present invention, a tracking error signal detecting means for detecting a tracking error signal, and a differentiation of the tracking error signal detected by the tracking error signal detecting means. Differentiating means for obtaining a signal, zero-cross pulse detecting means for detecting and pulsing the zero-cross of the differential tracking error signal output by the differentiating means and the tracking error signal detected by the tracking error signal detecting means, and the zero-cross Pulse counting means for counting the zero-cross pulses detected by the pulse detecting means, linear area detecting means for detecting the linear area of the tracking error signal detected by the tracking error signal detecting means, and the tracking error signal detecting means Detected trackin A moving distance detecting means for the light beam in the track jump operation for detecting a moving distance from the center of the track jump start track by the error signal,
A time measuring means for measuring the time from the start to the end of the track jump operation, and a moving speed of the light beam from a change in the moving distance of the light beam during the track jump operation detected by the moving distance detecting means in a minute time. Moving speed detecting means for detecting, the tracking error signal detected by the tracking error signal detecting means, the moving distance of the light beam during the track jump operation detected by the moving distance detecting means, and the time measured by the time measuring means And track jump pulse control means for controlling the track jump pulse by the counter value counted by the pulse counting means, and tracking detected by the tracking signal detecting means for performing a follow-up operation to an arbitrary track position (land or groove). For inverting the polarity of the error signal And a sex reversal means.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a track jump control device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram showing a first embodiment when the track jump control device of the present invention is applied to a land / groove recording type optical disc device.
In FIG. 1, 101 is an optical pickup for irradiating an optical disc (not shown) with a light beam to guide reflected light, and 102 is a two-division photodetector 102a and a differential amplifier 102b. The tracking error signal detection circuit 103 for obtaining the tracking error signal TE by 103, the phase compensation circuit 103, and the tracking error signal TE input to the phase compensation circuit 103 depending on which of the land and the groove the light beam follows. A polarity inversion circuit for switching the polarity, 104 a mode switch, 105 a drive circuit for amplifying the drive signal of the tracking actuator 106 by current, 106 a tracking actuator, 107 a drive microcomputer, 108 a tracking error signal TE. Moving distance detecting circuit for detecting a moving distance from the track center of the light beam in Luo track jump, 109 jump pulse to be output to the tracking actuator 106 when performing the track jump,
A track jump pulse control circuit for controlling a brake pulse, 110 is a moving speed detecting circuit for detecting a moving speed of the light beam based on the moving distance of the light beam detected by the moving distance detecting circuit 108, and 111 is a track. A timer for measuring the time from the jump start to the end, 113 is a differentiating circuit for differentiating the tracking error signal TE which is the output of the tracking error signal detecting circuit 102, and 114 is a zero cross of the tracking error signal TE and the differentiating circuit 113. Is a pulse counting circuit for outputting a zero-crossing detection pulse when the zero-crossing of its output is detected and counting the pulse.

Reflected light of a light beam from an optical disk (not shown in FIG. 1) passes through an optical pickup 101 and enters a tracking error signal detection circuit 102. The tracking error signal TE detection circuit 102 includes a two-divided photodetector 102a and a differential amplifier 102b. The reflected light is photoelectrically converted by the two-divided photodetector 102a and becomes a tracking error signal TE in the differential amplifier 102b. Here, the level of the tracking error signal TE corresponds to the amount of deviation of the light beam from the track center, and the polarity thereof corresponds to the direction of deviation. The tracking error signal TE is supplied to the polarity inversion circuit 112, the phase compensation circuit 103, and the switch 10.
4 and the drive circuit 105, and becomes a drive signal for the tracking actuator 106, and the light beam is controlled so as to follow the land or groove. In the case of the present embodiment in which the TE signal as shown in FIG. 2 is output, the drive microcomputer 107 does not change the polarity of the tracking error signal when tracking the groove portion, and the tracking error signal when tracking the land portion. The polarity inversion signal P that inverts the polarity of the error signal is output to the polarity inversion circuit 112.

Next, the track jump operation from the groove portion to the land portion of the next track will be described. First, the switch 104 is set to the track jump mode by the mode switching signal 1C of the drive microcomputer 107,
The tracking servo loop opens. Further, a jump pulse is output by the track jump pulse control circuit 109 to the tracking actuator 106 via the switch 104 and the drive circuit 105.

When the tracking servo loop is open in the track jump mode, the tracking error signal detection circuit 102 outputs the tracking error signal TE as shown in FIG. Since the tracking error signal TE in FIG. 2 is substantially sinusoidal, it can be regarded as linear near the amplitude of the tracking error signal, but becomes non-linear when it exceeds the range. In the linear region, the deviation amount L from the track center of the light beam can be obtained from the tracking error signal amplitude using a linear approximation formula. The detection error of the deviation amount L of the light beam from the track center at that time is an approximation error due to a linear approximation with the detection error of the tracking error signal TE. Therefore, the tracking error signal amplitude at the boundary between the linear region and the nonlinear region is The magnitude Vth depends on the allowable amount of the approximation error when the shift amount L of the light beam from the track center is approximately calculated from the tracking error signal amplitude. When the approximation error is 10% or less,
Vth≈0.37 × Vpp. In the linear region of FIG. 2 divided by ± Vth, the deviation amount L of the light beam from the groove track center can be approximately calculated by the following [Equation 1].

[0021]

[Equation 1] L≈TP · TE / (Vpp · π) ... Region L≈TP / 2− (TP · TE / (Vpp · π))… Region L≈TP + (TP · TE / (Vpp · π)) Area L≈3TP / 2− (TP · TE / (Vpp · π)) Area During the track jump operation, the amount of deviation from the track center obtained by using (Equation 1) above is the track jump start. It is the moving distance of the light beam from the center of the track at that time. Therefore, if the tracking error signal amplitude Vpp is obtained in advance, the moving distance of the light beam can be approximately obtained in the linear region during the track jump by the tracking error signal TE.

The tracking error signal TE 'and the tracking error signal TE differentiated by the differentiating circuit 113 during the track jump operation are shown in FIG. The pulse count circuit 114 is realized by a configuration as shown in FIG. 4 as an example. In FIG. 4, 401 and 404 are comparators,
Reference numerals 402 and 405 are delay circuits, 403 and 406 are EOR circuits, 407 is an OR circuit, and 408 is a counter. The comparators 401 and 404 detect zero crossings of TE and TE ′, and the EOR circuits 403 and 406 are used to compare the comparison result with the delay circuits 402 and 405, respectively.
And pulse it. The OR circuit 407 adds the zero-cross pulses of TE and TE 'to generate a zero-cross pulse. The counter 408 performs a counting operation using the zero-cross pulse as a clock, and the counter value is cleared by the CLR signal from the drive microcomputer 107 at the beginning of the track jump operation. The counter value is output to the moving distance detection circuit 108 and the track jump pulse control circuit 109.

The moving distance detecting circuit 108 obtains the moving distance of the light beam during the track jump from the tracking error signal TE using the above [Equation 1], but the calculation formulas are different in the linear regions shown in FIG. , It is necessary to detect the area where the light beam is. The moving distance detection circuit 108 detects which area the tracking error signal TE currently belongs to, as shown in FIG. 3, from the comparison result of the counter value output from the pulse counter circuit 114, the magnitude of the tracking error signal TE, and ± Vth. Then, the area signal Z is output to the track jump pulse control circuit 109. Further, the moving distance calculation formula is selected according to the detected area, the moving distance of the light beam in the linear area is obtained, and the moving distance L is output to the track jump pulse control circuit 109. Vpp, which is a value necessary for the calculation of the moving distance of the light beam, can be obtained by holding the positive and negative peak values of the tracking error signal by a sample hold circuit before the tracking servo is closed when the optical disk device is started. it can.

Track jump pulse control circuit 109
Is realized by the configuration shown in FIG. 5 as an example. In FIG. 5, 501 is a decoder for detecting the switching timing from the jump pulse to the brake pulse based on the counter value output from the pulse count circuit 114, and 5
Reference numeral 02 is a control brake pulse calculation circuit, 503 is an initial brake pulse calculation circuit, 504 is a jump pulse output circuit for outputting a jump pulse when starting a track jump, 505 is a selection output circuit, and 506 is a changeover switch.

In the optical disk device of FIG. 1, the switch 104 is switched by the mode switching signal 1C of the drive microcomputer 107 to enter the track jump mode, the timer 111 is started at the same time when the tracking servo loop is opened, and the track jump pulse control circuit 109 The changeover switch 506 is connected to C where the output of the jump pulse output circuit 504 is selected by the selection output of the selection output circuit 505, and outputs the jump pulse output from the one jump pulse output circuit 504. Here, the magnitude of the jump pulse voltage output from the jump pulse output circuit 504 depends on the voltage-current conversion gain of the drive circuit 105 and the acceleration sensitivity of the tracking actuator 106, and it is necessary to set the track jump from the groove portion to the land portion of the next track. When the time Tjump elapses, the moving distance L is such that an ideal acceleration aj at which the track pitch 3TP / 2 and the moving speed V of the light beam becomes 0 can be obtained. If the tracking actuator does not have a spring system, the output times of the brake pulse and the jump pulse will be equal, and the moving distance of the light beam at the pulse switching time will be 3 / of the track pitch TP.
Therefore, the magnitude of the acceleration aj is represented by the following [Equation 2].

[0026]

[Formula 2] aj = 6TP / (Tjump) ^ 2 After the jump pulse output circuit 504 outputs a jump pulse and the timer 111 starts, the decoder 501 inside the track jump pulse control circuit 109 outputs the output of the pulse counter circuit 114. Monitor the counter value. The decoder 501 detects that the counter value has become 3 due to the zero-cross pulse when the moving distance L of the light beam has become a value of 3/4 of the track pitch TP, and outputs a pulse switching signal to the initial brake pulse calculation circuit 503. Output to the selection output circuit 505. Here, the pulse switching signal is output when the counter value is 3, but this value differs depending on the type of track jump.

Since the zero-cross pulse generated in the pulse counting circuit 114 rises at every 1/4 of the track pitch, the value of the counter 408 represents the moving distance of the light beam at every 1/4 TP. In the case of land / groove recording, the movement distance due to the track jump is TP / 2 unit. Therefore, when the jump pulse is switched at a half point of the movement distance, the timing of jump pulse switching can be known from the counter value. Assuming that the number of moving tracks is n, the counter value of the jump pulse switching timing is expressed by the following equation [Equation 3].

[0028]

## EQU00003 ## Pulse switching count value = 2.n. ± .d Here, d is a value determined by the follow-up position before and after the jump, and the arrangement of the land and the groove in the track is such that the groove is on the inner peripheral side and the land is on the outer peripheral side. In this case, it is represented by the following [Table 1].

[0029]

[Table 1]

Therefore, when the counter value when the decoder 501 outputs the pulse switching signal from [Equation 3] and [Table 1] is one track jump, the land in the track and the groove are arranged such that the groove is on the inner peripheral side land. Is the outer peripheral side, the counter value when the decoder 501 outputs the pulse switching signal is 1 track jump, the track following position (land or groove) before the jump and the track following position (land or groove) of the next track. And [Table 2] below depending on whether to jump to the outer circumference side or the inner circumference side.

[0031]

[Table 2]

The selection circuit 505 outputs to the changeover switch 506 a selection signal for the changeover switch 506 to select the output of the initial brake pulse calculation circuit 503 according to the pulse changeover signal output from the decoder 501. Therefore, the brake pulse output from the initial brake pulse calculation circuit 503 is output to the tracking actuator 106 via the changeover switch 506. The magnitude of the brake pulse is usually the same as that of the jump pulse, but the polarity is opposite.

However, when the time Tc from the start of the track jump to the rise of the pulse switching signal, that is, the time Tc from the start of the track jump to the movement of half the total travel distance of the track jump is not half of the required time Tjump of the track jump. Since the desired acceleration is not obtained by the jump pulse due to a disturbance or a characteristic change, the magnitude of the brake pulse is different from that of the jump pulse which is the acceleration aj obtained by [Equation 2], and the magnitude is different. If equal pulses are used, when the servo is closed after the track jump ends, the level of the tracking error signal TE is large as in the example of FIG. 14, and the servo operation starts at a position away from the track center. It is possible that the servo pull-in may fail.

Therefore, when the moving distance L of the light beam becomes 3/4 of the track pitch TP, the decoder 501 outputs a switching signal to the initial brake pulse calculating circuit 503. The initial brake pulse calculation circuit 503 reads the time T of the timer 111 operated when the track jump operation is started when the switching signal is detected, as the time Tc to half the total movement distance. The initial brake pulse calculation circuit 503 compares the time Tc to the half of the total moving distance with the half value of the set time Tjump of the track jump,
Calculates and outputs the magnitude of the brake pulse. Moving distance L
Since the time Tc elapses until half the total moving distance of 1.5TP due to the track jump, the average acceleration aAV is represented by the following [Equation 4].

[0035]

## EQU00004 ## aAV = 3TP / Tc ^ 2 When the average acceleration aAV is equal to the predetermined acceleration aj, the magnitude of the brake pulse may be the same as that of the jump pulse, but when aAV> aj, the brake pulse The magnitude is made larger than the jump pulse by the difference in acceleration.
Therefore, the moving speed of the light beam is greatly reduced, and it takes a long time to move the remaining distance, and the moving distance of the light beam is 1.5 T in the track jump setting required time Tjump.
It becomes closer to P. Similarly, in the case of aAV <aj, the size of the brake pulse is made smaller than the jump pulse by the difference in acceleration to suppress the deceleration of the moving speed of the light beam, and the set time Tju for the track jump is set.
In mp, the moving distance of the light beam is close to the total moving distance of 1.5 TP due to the track jump.

After the magnitude of the brake pulse is controlled by the time Tc, while the area signal Z output from the moving distance detecting circuit 108 is in the area shown in FIG. The control brake pulse calculation circuit 502 controls the brake pulse so that L becomes the total movement distance of 1.5 TP due to the track jump. Further, the selection output circuit 505 outputs the output of the control brake pulse calculation circuit 502 to the tracking actuator 106 as a track jump pulse after the area signal Z output from the movement distance detection circuit 108 becomes the area shown in FIG. Changeover switch 506
Outputs a selection signal for switching.

With respect to the remaining moving distance Lr until the end of the track jump, the present moving speed V, the acceleration a ', and the remaining time Tr until the end of the track jump have the following relationship of [Equation 5].

[0038]

[Formula 5] Lr = VTr + 0.5a'Tr ^ 2 Therefore, in order to set the moving distance L to the total moving distance 1.5TP by the track jump in the set time Tjump of the track jump, the acceleration a ' That is, the output of the brake pulse may be controlled. Acceleration a'is [Equation 5]
It is obtained from the following [Equation 6] obtained by modifying

[0039]

[Mathematical formula-see original document] a '= 2 (Lr-V.Tr) / Tr2 where Tr is the remaining time until the end of the track jump.
Is Tr = Tjump-T, and the remaining movement distance Lr until the end of the track jump is obtained as Lr = TP-L. Therefore, in order to obtain the acceleration a ', the movement speed V of the light beam, the movement distance L and the time T You only need to know The moving distance L is calculated by the moving distance detecting circuit 108, and the time T is set by the timer 111.
Accordingly, the moving speed V is obtained by the moving speed detection circuit 110.

The moving speed detecting circuit 110 is realized by the structure shown in FIG. In FIG. 6, reference numeral 601 is a delay line for delaying the output of the distance detection circuit 108 for a certain minute time Δt, and 602 is a subtractor. In the moving speed detection circuit 110, the moving distance Ln of the light beam output from the moving distance detection circuit 108 at a certain time n and the moving distance of the light beam output from the distance detection circuit 108 delayed by the delay line 601 for a minute time Δt. By subtracting Ln-1 by the subtractor 602, the moving distance ΔL in the minute time Δt, that is, the moving speed V of the light beam can be obtained.

The control brake pulse calculation circuit 502 obtains the magnitude of the brake pulse voltage at which the acceleration is a'of [Equation 6] by using the moving speed V, the moving distance L and the time T of the light beam. It outputs to the tracking actuator 106 via the drive circuit 105.

In the area, after the brake pulse is controlled by the remaining time Tr until the end of the track jump and the remaining moving distance Lr until the end of the track jump, the area signal Z output from the moving distance detection circuit 108 is the area shown in FIG. In, the tracking error signal TE becomes non-linear. Therefore, since the moving distance L cannot be obtained by linear approximation, the brake pulse cannot be controlled as in the above-mentioned region. In the area, the final output of the control brake pulse in the area is continuously output. After that, in the area, the brake pulse is controlled by the remaining time Tr until the end of the track jump and the remaining movement distance Lr until the end of the track jump, as in the area.

As described above, the brake pulse having the acceleration of the total track jump travel distance of 1.5 TP at the track jump set time Tjump is obtained by using the light beam travel speed V, travel distance L and time T, and the switch 10 is selected.
4. Since the signal is output to the tracking actuator 106 via the drive circuit 105, as shown in FIG. 7, normal bang-bang control is performed due to variations in characteristics of the tracking actuator 106 itself, changes over time, and disturbances such as disk eccentricity received during the track jump operation. Then, even when the level of the tracking error signal TE increases (the light beam moves away from the track center) at the end of the track jump, the track jump pulse controlled by the track jump pulse control circuit 109 is output, and the track jump setting time Tjump is set. In, the level of the tracking error signal TE can be made small (the light beam is located near the center of the track).

The time is the required time T for the track jump.
When the jump is reached, the track jump ends, and the polarity inversion circuit 112 inverts the polarity of the tracking error signal TE so that the polarity inversion signal P from the drive microcomputer 107 follows the land portion. Further, the switch 104 is closed by the mode switching signal 1C from the drive microcomputer 107 and the servo loop is closed, so that the tracking servo is pulled into the land portion and is controlled so as to follow the target track. When the tracking servo is pulled in, the level of the tracking error signal TE is small and close to the track center, so that stable tracking servo pull-in is possible after the track jump is completed.

As described above, according to the first embodiment of the present invention, during the track jump operation, variations in the characteristics of the tracking actuator itself, changes over time, and disturbances such as disk eccentricity received during the track jump operation are common. In the conventional bang-bang control, even when the level of the tracking error signal TE is large at the end of the track jump and the tracking servo is pulled in at a position where the light beam is away from the track center, the track jump output to the tracking actuator during the track jump operation is performed. Since the pulse is controlled, the level of the tracking error signal TE at the end of the track jump becomes small (the light beam is close to the center of the track), and stable tracking servo can be pulled in to a desired track position at the end of the track jump. That.

In the first embodiment of the present invention, the end of the track jump operation is set to the time when the set time Tjump of the track jump is reached, but the level of the tracking error signal TE is 0, that is, the light beam is the desired track. It does not matter even when the center of the position (land center or groove center) is reached. Although the jump pulse is not controlled, the size of the jump pulse is increased or decreased by comparing with the level of the ideal tracking error signal TE, and the moving distance and speed of the light beam during the jump pulse output are detected. , 1 / time required to set track jump Tjump
At the time of 2, the movement distance is 1 of the total movement distance of the track jump.
The jump pulse may be controlled so that the acceleration becomes / 2.

Next, a second embodiment of the track jump control device according to the present invention will be described with reference to the drawings. FIG.
FIG. 9 is a circuit block diagram showing a second embodiment when the track jump control device of the present invention is applied to a land / groove recording type optical disc device. In FIG. 8, 101 is an optical pickup for irradiating an optical disc (not shown) with a light beam to guide reflected light, and 102 is a two-split photodetector 102.
a and the differential amplifier 102b, the optical pickup 10
1, a tracking error signal detection circuit for obtaining a light beam reflected light from the optical disc to obtain a tracking error signal TE, 801 is an A / D converter for converting an analog signal into a digital signal, and 802 is servo control and a track. A digital signal processor for performing jump control (hereinafter referred to as DSP),
Reference numeral 803 is a D / A converter for converting the output of the DSP 802 which is a digital signal into an analog signal, 105 is a drive circuit for current amplifying the drive signal of the tracking actuator 106, 106 is a tracking actuator, and 107 is a drive microcomputer. is there. In FIG. 8, the same parts as those in FIG. 1 are designated by the same reference numerals.

In FIG. 8, the reflected light of the light beam from the optical disk (not shown) is incident on the tracking error signal detection circuit 102 through the optical pickup 101. The tracking error signal TE detection circuit 102 includes a two-divided photodetector 102a and a differential amplifier 102b. The reflected light is photoelectrically converted by the two-divided photodetector 102a and becomes a tracking error signal TE in the differential amplifier 102b. Here, the level of the tracking error signal TE corresponds to the amount of deviation of the light beam from the track center, and the polarity thereof corresponds to the direction of deviation. This tracking error signal TE is A
The digital signal TEd is converted by the / D converter 801. The DSP 802 is controlled by the control signal Sc of the drive microcomputer 107, and normally performs a phase compensation calculation using the tracking error signal TEd converted into a digital signal. The calculation result is the D / A converter 8
In 03, it is converted into an analog signal and becomes a drive signal for the tracking actuator 106 via the drive circuit 105, and tracking control is performed in which the light beam follows the track. Further, in the track jump operation, the track jump is performed using the interrupt processing by the control signal Sc of the drive microcomputer 107.

The DSP is a programmable single-chip microcomputer having a plurality of high-speed arithmetic units for digital signal processing, and can perform different signal processing by programs. In the second embodiment of the present invention, the control signal Sc from the drive microcomputer 107 is set as an external interrupt signal to arbitrarily generate an interrupt and switch the execution programs of the tracking servo process and the track jump process. Therefore, when the main program is executed, the DSP 802 performs tracking servo control, so the servo loop is closed, but the control signal Sc from the drive microcomputer 107 is used.
When an interrupt occurs and the track jump control program is executed, the servo loop is opened and tracking servo control is not performed.

Track jump control will be described below with reference to the flow chart of the track jump control program of the DSP 802 shown in FIG. The first track jump
The track jump is from the groove to the land of the next track as in the embodiment of FIG. Simultaneously with the interruption, the decode data, which is the zero-cross pulse count number up to the track jump target position, is input from the drive microcomputer 107. As in the first embodiment, the zero-cross pulse count is incremented every 1/4 TP of the moving distance of the light beam, so that the track jump ends when the pulse count reaches this decoded data. for that reason,
The switching timing between the jump pulse and the brake pulse is half of the decode data. The value of the decoded data output from the drive microcomputer 107 differs depending on the start position and end position of the track jump and the jump direction, but as in the first embodiment, the inner circumference side is the groove and the outer circumference side is the land. In this case, the decoded data is twice the value of [Table 2] in the first embodiment.

Control signal S from drive microcomputer 107
First process 90 of track jump of interrupt by c
1 is the initial setting. In the initial setting, a jump pulse is output, the counter is started, and the flag is cleared. The magnitude of the jump pulse is the same as that of the first embodiment of the present invention, and the magnitude of the jump pulse output from the DSP 802 is such that the travel distance L is the total travel distance of the track jump when the set time Tjump of the track jump has elapsed. 1.5TP, which is a magnitude at which the acceleration aj of an ideal magnitude at which the moving speed V of the light beam is 0 can be obtained. Since it is a constant value, the ROM data is referred to and output.
Further, the counter corresponding to the timer of the first embodiment increments the counter value from the initial value 0 at every sampling interval ΔTs of the A / D converter 801. After processing 901,
The process 902 waits in a loop until the counter value reaches an appropriate value n. This is to prevent a zero-cross detection error that occurs when the value of the tracking error signal TEd at the start of the track jump is low when performing the zero-cross detection of the differential signal of the tracking error signal TEd in the next process 903. The value of n is the tracking error signal TE
It suffices to set a standard sampling number until d becomes the area of FIG.

A certain time n-1 of the tracking error signal TEd output from the A / D converter 801 to the DSP 802.
The differential TE ′ of the tracking error signal can be obtained by taking the difference between the values of and n. Since the tracking error signal TEd is data that takes a discrete value that changes at every sampling interval ΔTs, it is extremely unlikely that the point at which TE ′, which is the difference between the tracking error signals TEd, is exactly 0 can be sampled. Therefore, when the zero-crossing detection is performed after the differential tracking error signal TEd ′ becomes 0 or less, in the worst case, the zero-crossing is detected with a delay of the sampling interval ΔTs. Therefore, in the process 903, the magnitude of the differential tracking error signal TEd ′ is set to reduce the detection delay caused by the sampling interval when the tracking error signal TE is converted into a digital signal by the A / D converter 901. Compared to an appropriate zero-cross detection threshold Δ, if -Δ
When ≦ TEd ′ ≦ Δ, it is considered that the differential tracking error signal TEd ′ has zero cross. Process 902 is T
The process loops until the zero cross of Ed 'is detected, and when the zero cross of TEd' is detected, the process proceeds to the next processing.

The process 903 increments the pulse counter after detecting the zero cross of TEd '. The pulse count value is decode 1 (1 / of the decoded data
If it is larger than 2), that is, after the jump pulse switching timing, the process 906 is executed. Process 906
Is the output of the brake pulse, and the processing content is shown in FIG. In FIG. 10, a process 903 checks a flag. First, when the flag has not risen, it is determined that it is the timing to switch to the brake pulse, and the counter value Tc at that time, the sampling interval ΔTs, and 1/2 of the decoded data (decode 1) are used to calculate the average by the following formula (Equation 7) The acceleration aAV is calculated.

[0054]

[Formula 7] aAV = 2 · (decode 1 × TP / 4) / (Tc
× ΔTs) ^ 2 In the process 914, the average acceleration a is the same as in the first embodiment.
It calculates and outputs an initial brake pulse whose polarity is different from that of the jump pulse so that the AV acceleration can be obtained.
After that, flag is set in step 915 so that the initial brake pulse is not output thereafter.

If the flag is set in step 913 and the timing for switching to the brake pulse has elapsed, step 916 determines whether the tracking error signal is in the linear range. If the tracking error signal is in the linear range, the following steps 917-
921 is executed. In steps 917 to 921, the control acceleration a ′ is calculated and the control brake pulse is output using the remaining movement distance, the movement speed, and the remaining time until the track jump end time as in the first embodiment.

On the other hand, when the pulse count value is not equal to or more than the decode 1 which is the jump pulse switching timing, the loop of the process 907 is executed until the zero cross of the tracking error signal is detected. In step 907, the A / D converter 801 is used as in the case of the TE 'zero-crossing detection described above.
In order to reduce the detection delay caused by the sampling interval when it is converted into a digital signal by
The magnitude of the tracking error signal TEd is compared with an appropriate zero-cross detection threshold Vzx, and if -Vzx≤TEd≤
If it becomes Vzx, it is considered that the tracking error signal TEd has crossed zero, and the process proceeds to the next processing 908. Process 90
8 increments the pulse counter. When the value of the pulse count is smaller than decode 1 (1/2 of the decoded data), that is, before the jump pulse switching timing, the process returns to step 903 and the TE 'zero cross is detected again.

When the value of the pulse count is larger than the decode 1 (1/2 of the decoded data), that is, after the jump pulse switching timing, the end determination is made by the processes 910 and 911. When the end of the track jump cannot be detected, the brake pulse is output by the processing 906 described above. The end of the track jump is determined by comparing the pulse count value with the decode 2 (decoded data) and determining the time-out. If the pulse count value is decoded data, it indicates that the desired track jump movement distance has been moved, and the track jump process is terminated. When the execution time of the track jump operation exceeds the track jump set required time Tjump from the counter value, the track jump processing is terminated as a timeout. After the track jump processing is completed, in processing 912, the polarity of the tracking error signal when performing the phase compensation calculation in the tracking operation is set according to the tracking position (land or groove) of the target track. The DSP 802 completes the track jump operation due to the interruption by the above processing and executes the normal main program, so that the tracking servo loop is closed and the tracking servo is pulled in to perform the tracking servo control to follow the track. Since the brake pulse is controlled during the track jump operation,
When the tracking servo is pulled in, the level of the tracking error signal TE is small and close to the track center.
It is possible to stably pull in the tracking servo after the track jump ends.

As described above, according to the second embodiment of the present invention, during the track jump operation, variations in the characteristics of the tracking actuator itself, changes over time, and disturbances such as disk eccentricity received during the track jump operation are common. In the conventional bang-bang control, even when the level of the tracking error signal TE is large at the end of the track jump and the tracking servo is pulled in at a position where the light beam is away from the track center, the track jump output to the tracking actuator during the track jump operation is performed. Since the pulse is controlled, the level of the tracking error signal TE at the end of the track jump becomes small (the light beam is close to the center of the track), and stable tracking servo can be pulled in at the end of the track jump. Further, since the above operation is performed by switching the DSP program, there is no special circuit increase in the case of applying the present invention in the optical disk device performing the digital servo control by the DSP, except that the number of steps of the DSP program is increased. . Further, although the track jump is started by an interrupt in the second embodiment, it may be a DSP program which monitors a control signal from the drive microcomputer as an external flag and branches by the flag.

In the first and second embodiments of the present invention described above, the track jump has been described. However, in the land / groove recording method, a multi-track jump for moving a plurality of tracks or a land / groove in the same track is used. By applying the track jump control device of the present invention and performing the similar track jump pulse control in the deceleration section in the jump to, the first and second embodiments of the present invention can be performed even at the end of the track jump. Since the level of the tracking error signal TE can be reduced (the light beam is close to the track center),
It is possible to stably pull in the tracking servo after the end of the multi-track jump. Further, in the first and second embodiments of the present invention, the magnitude of the brake pulse after the track jump pulse switching timing detected by the value of the pulse counter is made the same as the detected average acceleration. The moving speed of the light beam at that time may be detected, and the magnitude of the brake pulse may be made equal to the acceleration at which the moving distance becomes the total moving distance of the track jump at the end of the track jump. Also,
In the first and second embodiments of the present invention, the brake pulse switching timing in the track jump is set to the tracking error signal TE and the differential tracking error signal TE '.
The tracking sum signal TS is used instead of TE ′, and the average value of the maximum value and the minimum value of TS is used as a threshold value for T.
Since the same count value can be obtained by detecting that the S signal crosses the threshold value and counting with the zero cross of TE, it is possible to obtain the same effect as the first and second embodiments of the present invention. it can.

When the present invention is applied to an optical disc device capable of recording and reproducing discs of different formats, when the recording method (land recording or groove recording) on the disc differs depending on the disc format, the disc It suffices to detect the format and set the polarity inversion. Also, when the track pitch differs depending on the format, the detection values of the moving distance and moving speed change, but this is also handled by identifying the disk and switching the constant (track pitch, track jump setting required time, etc.) according to the format. Therefore, the present invention is also effective in an optical disc device capable of recording and reproducing discs of different formats.

[0061]

As described above, according to the present invention, even during the track jump operation of the optical disk apparatus which employs the land / groove recording, the characteristics of the tracking actuator itself are varied or changed over time, and the disk is received during the track jump operation. In general bang-bang control due to disturbance such as eccentricity, even when the level of the tracking error signal is large at the end of the track jump and the light beam departs from the track center, the track jump pulse output to the tracking actuator is controlled during the track jump operation. Therefore, the level of the tracking error signal at the end of the track jump is small and the light beam is close to the track center. Further, by detecting the zero cross between the tracking error signal and the differential tracking error signal, the switching timing of the track jump pulse can be detected in the land / groove recording method. In addition, by inverting the polarity of the error signal input to the phase compensation circuit in accordance with the desired track position, a stable tracking servo is performed at the desired track position after the desired track jump operation in an optical disk device that employs land / groove recording. Can be retracted.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a first embodiment according to the present invention.

FIG. 2 is a waveform diagram showing a tracking error signal TE.

FIG. 3 is a waveform diagram showing a differential tracking error signal and a count pulse.

FIG. 4 is a diagram showing a specific example of a pulse counter circuit.

FIG. 5 is a diagram showing a specific example of a track jump pulse control circuit.

FIG. 6 is a diagram showing a specific example of a speed detection circuit.

FIG. 7 is a waveform diagram showing the operation of the track jump control device of the present invention.

FIG. 8 is a circuit block diagram showing a second embodiment according to the present invention.

FIG. 9 is a processing flowchart in the second embodiment according to the present invention.

10 is a processing flowchart for explaining the contents of processing 906 of FIG.

FIG. 11 is a block diagram showing an optical disc device using a conventional bang-bang control system.

FIG. 12 is a diagram for explaining a recording method on an optical disc.

FIG. 13 is a waveform diagram illustrating a one-track jump operation under bang-bang control.

FIG. 14 is a tracking error signal T due to the influence of disturbance or the like.
It is a waveform diagram showing an example of E.

[Explanation of symbols]

 Reference numeral 101 ... Optical pickup, 102a ... Two-division photodetector, 102b ... Subtractor, 106 ... Tracking actuator, 107 ... Drive microcomputer, 108 ... Moving distance detecting circuit, 109 ... Track jump pulse control circuit, 110 ... Moving speed detecting circuit, 111 ... Timer, 112 ... Polarity inversion circuit, 113 ... Differentiation circuit, 114 ... Pulse count circuit, 801 ... A / D converter, 802 ... DSP, 803 ... D / A converter.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Ishibashi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd. Hitachi, Ltd. multimedia system development headquarters (72) Motoyuki Suzuki Yoshida, Totsuka-ku, Yokohama-shi, Kanagawa 292, Machi, Hitachi, Ltd. Multimedia system development headquarters (72) Inventor Yoshio Suzuki, 292, Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture

Claims (9)

[Claims] 1. In an optical recording / reproducing apparatus having a tracking servo system, in the case of a land / groove recording system, a polarity reversing means for reversing the polarity of a tracking error signal depending on a tracking position, and a linear tracking error signal. A linear area detecting means for detecting an area, a moving distance detecting means for detecting a moving distance of a light beam from a track center by a tracking error signal when the linear area detecting means detects a linear area, and a track jump operation And a moving speed detecting means for detecting the moving speed of the light beam from a change in the moving distance of the light beam during the track jump operation detected by the moving distance detecting means in a minute time. Means, the moving distance detected by the moving distance detecting means, the time measured by the time measuring means, and Track jump pulse control means for controlling the magnitude of the track jump pulse based on the moving speed detected by the moving speed detecting means and the tracking error signal is provided, and the track jump signal level at the end of the track jump is reduced. A track jump control device in an optical recording / reproducing device, characterized in that the magnitude of a pulse is controlled by the track jump pulse control means. 2. The track jump control device according to claim 1, wherein a tracking error signal differentiating means for detecting a differential value of the tracking error signal, a differential tracking error signal and a tracking error signal detected by the tracking error signal detecting means. A zero-cross pulse detecting means for detecting the zero-cross pulse and a zero-cross pulse counting means for counting the number of zero-cross pulses detected by the zero-cross pulse detecting means, and a track jump operation is performed by the number of zero-cross pulses counted by the zero-cross pulse counting means. 2. A track jump control device in an optical recording / reproducing device, characterized in that the output timing of a brake pulse is determined. 3. The track jump control device according to claim 1, wherein the tracking sum signal crosses the threshold value and a tracking error with respect to a threshold value which is an average value of the maximum value and the minimum value of the tracking sum signal. A zero-cross pulse detecting means for detecting a zero-cross of a signal and a zero-cross pulse counting means for counting the number of zero-cross pulses detected by the zero-cross pulse detecting means are provided, and a track jump is performed by the number of zero-cross pulses counted by the zero-cross pulse counting means. A track jump control device in an optical recording / reproducing device, characterized in that the output timing of a brake pulse in operation is determined. 4. The track jump control device according to claim 2 or 3, wherein a brake pulse capable of obtaining a deceleration having the same magnitude as the average acceleration at the time when the brake pulse is output by the count value of the zero-cross counting means. The track jump pulse control means outputs the track jump pulse control means. 5. The track jump control device according to claim 2 or 3, wherein at the time when the brake pulse is output based on the count value of the zero-cross counting means, the acceleration at which the moving distance at the end of the track jump becomes the track jump moving distance is obtained. A track jump control device in an optical recording / reproducing device, wherein the track jump pulse control means outputs a possible brake pulse. 6. The track jump control device according to claim 4 or 5, wherein when the linear area detecting means detects a linear area after a brake pulse is output, the moving distance at the end of the track jump is the track jump moving distance. A track jump control device in an optical recording / reproducing device, wherein the track jump pulse control means outputs a brake pulse capable of obtaining acceleration. 7. The track jump control device according to claim 4, 5 or 6, wherein when the moving distance of the light beam detected by said moving distance detecting means becomes the track jump moving distance, the track jump operation is terminated. , A track jump control device in an optical recording / reproducing device characterized by operating a tracking servo system. 8. The track jump control device according to claim 4, 5, 6 or 7, when it is detected by the count value of the zero-cross count means that the moving distance of the light beam has become the track jump moving distance. A track jump control device in an optical recording / reproducing device, characterized by terminating the track jump operation and operating a tracking servo system. 9. The track jump control device according to claim 4, 5, 6, 7 or 8, wherein the moving distance of the light beam when the linear area detecting means detects the linear area during the jump pulse output. And a speed are detected by the moving distance detecting means and the moving speed detecting means, and a jump pulse capable of obtaining an acceleration at which the moving distance is 1/2 of the track jump moving distance at the time of 1/2 of the track jump required time The track jump pulse control means outputs the track jump pulse control means.