JPS63173278A - Disk servo-device - Google Patents

Abstract

PURPOSE:To quantitatively jump an arbitrary track by starting a jump by a track jump signal, counting a tracking error signal obtained thereby, and releasing the track jump signal at the time its counting value has reached a set value. CONSTITUTION:A track jump control means 56 generates a track jump signal Jp<+> in accordance with a track jump instruction (track jump instruction signal TJO). In accordance with this track jump signal Jp<+>, a pickup 24 moves in an arbitrary track direction of a disk. When a track jump is generated, a tracking error signal TE corresponding to the track jump is obtained from a tracking error detecting means 48. Subsequently, the track jump control means 56 counts the tracking error signal TE obtained by the tracking error detecting means 48 and executes track jump driving until the number of jump tracks becomes a specific value, executes damping in accordance with the number of track jumps, and stops quickly a movement of the pickup 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a disc servo device suitable for optical disc playback devices and the like, and particularly relates to changing the track position of a pickup.

[Conventional technology]

Optical disc playback devices for playing back information such as music recorded on compact discs (CDs), etc.
As shown in Figure 7, there are various servos such as a focus servo that focuses on the reflective surface of the CD2, a tracking servo that tracks the tracks of the CD2, and a constant linear velocity (CLV) servo that controls the rotational linear velocity of the CD2 at a constant level. Devices are installed, and these servo devices perform control operations based on reflected light from the CD 2, synchronization signals read out, and the like.

The signal DCLV applied to the motor 3 for rotating the CD 2 represents the drive output from the CLV servo system.

The pickup 4 is for reading data recorded on the tracks of the CD 2 and detecting the track position, and is moved in the diametrical direction of the CD 2 by a feed motor 8 via an arm 6, and is emitted from a laser light source 10. The laser beam 12 passes through a half mirror 14 called a beam preshifter, is focused by an optical system 16 such as an objective lens, and is irradiated onto the reflective surface of the CD 2. The optical system 6 is driven by a focus coil 18 and a tracking coil 20, the former focusing on the reflective surface of the CD 2, and the latter moving the focus onto the track.

Then, the reflected light 22 obtained from the CD 2 is received by a light receiving section 24 composed of a plurality of light receiving diodes, etc., and converted into an electrical light reception signal, which is then added to a preamplification section 26.
The RF flaw signal including the EFM signal is separated into a focus error signal FE and a tracking error signal TH, and is outputted to the RF flaw signal, CLV servo system, audio reproduction system, etc.

The focus error signal FE is sent to the filter 28 in response to a focus search command FS from a control unit (not shown).
The integral output obtained by the filter 28 is applied to the driver 30, and the focus coil 18 is driven by the output, and the optical system 16 is controlled to the just focus point.

Next, the tracking error signal TE is applied to a filter 32 and integrated, and then a multiplexer (MPX) 3
4 to form a servo signal TS+ for controlling the tracking coil 20 and a feed servo signal TS2 for controlling the feed motor 8 to jump between a plurality of trunks. The MPX 34 is operated by control signals from a control section (not shown), and the MPX 34 receives a trunk jumping signal Jp" and a truck jumping braking signal J from the control section.
Track jumping control is performed by p-.

The servo signal T S t obtained by the MPX 34 is applied to the driver 36 , and the tracking coil 20 is driven by the drive signal output from the driver 36 . In addition, the feed servo signal TS2 obtained by MPX34
is integrated by the filter 38 and the DC component is detected,
The DC component is applied to the driver 40, and its output drives the motor 8, and the pickup 4 is controlled to an arbitrary trunk position.

[Problem that the invention seeks to solve]

By the way, when skipping multiple tracks in such a playback device, a pulse having a constant time τA is set as the trunk skipping signal Jp'' as shown in J in FIG. As shown in K in FIG. 8, a track jumping braking pulse of a certain time τB is set as the trunk jumping braking signal Jp- for stopping the vehicle at the position, and as shown in M in FIG. Arm 6
The time τC of the arm sending signal SD for sending is set. The widths of each time τA, τB, and τC are set to approximate values by converting the number of skipped tracks into time using a microcomputer in advance.

In order to pull the times τA and τB of the trunk jumping signal Jp'' and the trunk jumping braking signal Jp- into the servo operation at the same time as the completion of this truck jumping, the period during which the truck jumping is performed is as shown in FIG. As shown in FIG.
As shown in , the servo operation is canceled for a time (τA+τB). 8 is a synchronization confirmation signal GFS indicating that a synchronization state has been obtained in response to the start of the servo operation. In response to this synchronization confirmation signal GFS, the eighth
The gain up pulse shown at N in the figure is canceled.

Then, various times τ such as the track skipping signal JP+
^, τB1τC1τD is determined by an experimental method in relation to mechanical mechanisms such as the tracking mechanism and feeding mechanism of the pickup 4, and must be set empirically for each mechanism of the device, and the time must be set precisely. Since it is not possible to do so, the control becomes rough, and if alignment with the mechanism cannot be achieved, there is a risk of malfunction.

Therefore, the present invention attempts to realize appropriate track jumping regardless of the mechanical mechanism by counting the number of track skips from the tracking error signal and grasping the track jumping situation.

[Means for solving problems]

As shown in FIG. 1, the disk servo device of the present invention is a disk servo device that controls a pickup 4 to a track position of a disk (CD 2), and includes tracking error detection means for detecting a tracking error from a detection signal of a pink-up 4. (operational amplifier 48) and track jumping in response to a track jumping command (track jumping command signal T□.), and counts the tracking error signal TE obtained by the tracking error detection means to track the skipped track. Truck jumping control means (truck jumping control unit 56
).

[For production]

The track jumping control means generates a track jumping signal Jp'' in response to a truck jumping command (trunk jumping command signal TJO). In response to this track jumping signal Jp', the pickup 4 selects an arbitrary position on the disk. When a track jump occurs, the tracking error signal TE corresponding to the track jump is obtained from the tracking error detection means. The truck jumping drive is performed until the number of skipped trucks reaches a specific value by counting the signal TE, and the brake is applied according to the number of trucks jumped, and the movement of the pickup 4 is immediately stopped, thereby allowing the jumping of multiple trucks. end.

〔Example〕

FIG. 1 shows an embodiment of a disk servo device of the present invention.

In this embodiment, a pickup using a three-beam method is used in which a main beam is projected at the center of the CD 2 track, and sub beams are projected at positions slightly off to the left and right from the track.

Photodetectors 42, 44, and 46 are installed in the light receiving section 24 of the pickup 4 according to the number of beams, and each photodetector 42.
44 and 46 are composed of, for example, light receiving diodes.

The photodetector 42 is the main beam MB, the photodetector 44 .
46 detects the sub beams SB+ and SB2, and the photodetector 4
The detection output RF of the main beam MB No. 2 was added to an audio system (not shown), and the detection signals Va and Vb obtained from the photodetectors 44 and 46 were installed as tracking error detection means for detecting tracking errors. In addition to operational amplifier 48, tracking error signal TE is detected.

By the way, the main beam MB and the sub beams SB1, SB2
is the bit P of the track as shown in fb) in FIG.
If the main beam MB matches the sub beam S
BI and SB2 are set to be shifted left and right from the pit P so that the width of the shift is equal. Figure 2 (a
) is (C1 in Fig. 2) when the main beam MB shifts to the left.
indicates the case where the main beam MB is shifted to the right, 0 represents the center line of the on-trunk position, and 0' represents the center line when the main beam MB is shifted to the left or right. When the main beam MB is aligned on the track, the tracking error signal TE obtained by the operational amplifier 48 exhibits an amplitude corresponding to the direction of deviation and the width of the deviation, as shown in FIG. It is given as an 8-character signal with positive and negative amplitudes on the left and right, with the position as zero level.

This tracking error signal TE is applied to a filter circuit 50 consisting of a low-pass filter or the like, converted into a DC signal, and then applied to the driver 36 via a switch 52. The switch 52 is installed to cut off the servo system during track jumping, and is closed during tracking control other than track jumping.

The driver 36 generates a drive signal corresponding to the tracking error signal TE and drives the tracking coil 20. That is, the tracking coil 20 changes the degree of excitation and the direction of excitation according to the tracking error signal TH, and generates a driving force to pull it back to the left in the case of rightward deviation, and to the right in the case of leftward deviation. . Therefore, the pickup 4 is controlled on the track by tracking control.

Then, the zero-crossing detection circuit 54 crosses the zero level of the tracking error signal TE to generate a signal corresponding to the positive signal component, for example, a zero-crossing pulse TZC, and applies it to the track jumping control section 56. The track jumping control unit 56 is configured as a control device such as a microcomputer installed in the optical disc playback device or as an independent circuit, and performs track jumping control in response to the track jumping command signal TJO, that is, the trunk When the jumping command signal TJO is applied to the track jumping control section 56, the truck jumping control section 56 shifts to the operating state and enters the track jumping mode, and outputs the servo release signal SB, the trunk jumping signal JP'' and the gain control. After generating the signal Gc, the trunk jump braking signal Jp- is output.

The switch 52 is switched to the cutoff state by the servo release signal SB, the servo system is cut off, and normal servo control is released.

The track jumping signal Jp'' has a signal mode depending on the direction of truck jumping, and is designated by the truck jumping command.This truck jumping signal Jp'' is applied to the driver 36 to force tracking. coil 20
is excited for track jumping, and the pickup 4 moves in the direction of the desired track. At this time, driver 3
6 is controlled by the gain control signal Gc, for example, in order to shift to a normal control state when track skipping is canceled, etc.
Set to maximum gain.

When the pickup 4 moves between tracks, a tracking error signal TE as shown in FIG. 3 is obtained due to the movement, so the zero cross detection circuit 5
4, the zero cross signal TZC of the tracking error signal TE is obtained.

Of these zero-crossing signals TZC, those with a time width exceeding the reference time τa correspond to the true tracking error signal TE, so these are counted and the trunk jump is performed until the counted value reaches the set value. The track skipping braking signal Jp- continues to output the signal Jp9 and outputs the track skipping braking signal Jp- at the same time as the track skipping signal Jp'' ends.
, and the trunk jump ends. At the end of this track jumping, the switch 52
is closed, servo control is restarted, gain control signal Gc is released, and control operation is performed with normal gain.

Therefore, in this disk servo device, track skipping is started by the track skipping signal JP'', and pulses exceeding the reference time τa of the zero cross signal TZC of the tracking error signal TH obtained thereby are counted up to the set number of skipped tracks. At the same time, the track jumping signal JP+ is maintained until the counting ends, and the track jumping braking signal jp- is generated from the counting ending point,
This track-jumping braking signal JP- is converted into a zero-crossing signal T.
It continues until the ZC exceeds the reference time τa, and then the track jumping of multiple tracks is completed. Therefore, a braking signal that corresponds to the mechanical characteristics of the tracking mechanism can be obtained, so that adjustment that takes into account the characteristics of each individual tracking mechanism becomes unnecessary. Additionally, the truck jumping time can be optimized depending on the trunk jumping signal and braking signal levels.
It is possible to move between trunks quickly and without causing malfunctions.

Next, FIG. 4 shows a specific example of the structure of the track skip control section 56 of the disk servo device shown in FIG. This configuration example allows both single track jumping and multiple trunk jumping, and switch 5
7 is switched according to the number of skipped tracks, X is closed when one track is skipped, and Y is closed when two or more tracks are skipped.

The track skip command signal T1° is given by a step signal, and is applied as a negative input to a NAND circuit 58 constituting a deterrent circuit. This NAND circuit 58 receives a track skip command signal T. An H (high) output is generated by the logical product of the inverted signal of , the non-inverted output Q of the flip-flop circuit 60 installed as a state storage means, and the track skipping braking signal jp-, and the output is sent to the flip-flop circuit 60. It is added to the flop circuit 60 as a D input.

The non-inverting output Q of the flip-flop circuit 60 is a NAND
The inverting input of the non-inverting output Q- is ANDed with the output of the OR circuit 64. This NAN
The H output of the D circuit 62 is applied to the D input of a flip-flop circuit 66, which is installed as a state storage means and a track skipping signal Jp'' generation means.When the H output is applied from the NAND circuit 62, the flip-flop Circuit 66 outputs track skipping signal J as its non-inverting output Q.
p'' is output and added to the NAND circuit 68.

The NAND circuit 68 receives an inverted signal of the track skipping signal Jp'' and a counter 70 obtained via the switch 57.
, or the comparison output v2 of the comparator 71, and the H output is added to the zero power of the flip-flop circuit 72 installed as a state storage means and a means for generating the trunk jump braking signal JP-. There is. N
When an H output is generated from the AND circuit 68, the flip-flop circuit 72 generates a track skipping braking signal Jp- as a non-inverted output Q. And flip-flop circuit 6
The non-inverted output Q of 6.72 is added to the AND circuit 74, and the servo release signal SB is formed by the logical product of both.

The counter 76 and the comparator 71 are installed as signal discriminating means for discriminating whether the signal is a true zero-crossing signal TZC. That is, the counter 76 is a means for measuring the time width of the zero cross signal TZC, and the non-inverting output Q of the flip-flop circuit 60 is equal to the initial setting signal CL.
At the same time, since the zero-crossing signal TZC is added as a counting control signal indicating the start and end of counting of clock pulse CLK, the zero-crossing signal TZC
time is output as the count value N1 of the clock pulse CLK. This count value Nl output is added to a comparator 71 and compared with a reference time τa for determining whether or not it is a true zero-crossing signal TZC.

The comparator 71 outputs a comparison output Vl when τa is N1.
, a comparison output ■2 is generated when τa>N1.

The comparison output V1 is applied to the counter 80 as a count drive signal, and upon arrival of the comparison output (1), the counter 80 starts counting the clock pulses CLK. The counter 80 is installed as a time setting means for setting the time of the track skipping signal Jp'', and is provided with the non-inverted output Q from the flip-flop circuit 60 as the initial setting signal CL, and the zero cross signal TZC as the clock. It is added as a counting control signal indicating the start and end of counting of pulse CLK, and the count value N corresponding to the reference time τa
Counting is performed using 1 as an initial value until the zero cross signal TZC shifts to low (L) level. This count value NZ represents the time of the zero cross signal TZC.

This count value N2 is added to the shifter 82 as a counting multiplier installed as a time setting means for setting the time of the trunk jumping braking signal JP-, and multiplied by a coefficient k to obtain the optimum braking time. are combined, and -Nz is set in the counter 70 to the multiplication result. The counter 70 is a time setting means for setting the braking time as real time, and the non-inverted output Q from the flip-flop circuit 60 is added as the initial setting signal CL.
A clock pulse CLK is added, the set value from the shifter 82 is incremented by -1'Jz by the count of the clock pulse CLK, and the count time is set to NAN.
Add to D circuit 68. Counter 70 may be configured with a register, for example.

Further, the zero cross signal TZC is applied to a counter 84 installed as a counting means for counting the number of a plurality of skipped tracks, and a comparator 86 compares the counted value M with a set number Mo added by initial setting. The comparison output of the comparator 86 and the comparison output 2 of the comparator 71 are ANDed by an AND circuit 88. The output of the AND circuit 88 and the comparison output (1) of the comparator 71 are added to the OR circuit 64 and serve as logical inputs of the NAND circuit 62.

In the above configuration, the generation of the truck skipping signal Jp'' and the trunk skipping braking signal Jp- will be explained with reference to the flowchart shown in FIG. 5 and the timing chart shown in FIG. 6.

When skipping multiple tracks, press switch 57 to Y.
Close to the side.

In FIG. 5, the tracking servo operation is started, and in step S, it is determined whether or not there is a track jumping command signal TJO for jumping over a plurality of tracks.

Truck jumping command signal T,.

If there is no track jumping command signal T, the determination in step S is made. Repeat until .

Truck jumping command signal T,. When it is determined that the counter 70, 76, 8
0.84 is initially set, and an initial value input IR is set for the reset manual power R of the flip-flop circuit 60, 66, 72.

Next, the process moves to step S, and the AND circuit 74 performs the AND
When the condition is met, the servo release signal SR is output. As a result, switch 52 is opened and the servo loop is released.

Next, the process moves to step S4, and the track jumping command signal T, is sent. is given at H level, the NAND circuit 58
becomes an L output, and the non-inverted output Q of the flip-flop circuit 60 becomes an L output. Since the output of the OR circuit 64 is an H output, the NAND circuit 62 is subjected to a NAND AND condition, and the H output is added to the D input of the flip-flop circuit 66, and the flip-flop circuit 66 outputs the non-inverted output Q. 6 Track skipping signal J as shown in Figure C
p” is output.

The pickup 4 moves between tracks in response to the track skipping signal Jp3, and as a result of this movement, a signal including a tracking error signal TE is obtained from the operational amplifier 48 shown in FIG. 1, as shown in A of FIG. It will be done. These signals are applied to the zero-cross detection circuit 54, and the zero-cross detection circuit 54 outputs the zero-cross signal TZ shown in FIG. 6B as a signal corresponding to the signal component exceeding the zero level.
C is obtained.

Next, in step S, in the comparator 71,
The count value N1 of the counter 76 and the reference time width τa are compared, and if the count value Nl is larger than the reference time width τa (τa<
N+), step S3 is returned to, and the servo release signal SB is continued to be issued to maintain release of the servo loop. If the count value N1 is smaller than the reference time width τa (τa>Nl
), the process moves to step S6, and the comparator 86 compares the count value M of the counter 84 and the set value MO. M<M
If o, the process returns to step≦3, and the servo release signal S8 is continued to be issued to maintain the release of the servo loop.

If M<Mo is not true, the process moves to step S7, where the track skipping signal Jp'' is canceled, and
Track jumping braking signal jp- as shown in D in FIG.
Output.

This track jumping braking signal Jp- causes the track jumping to enter a braking state, and in this braking state, the process moves to step S, where the comparator 71 compares the counted value N1 of the counter 76 with the reference time τa. If τa<N1, return to step S, and output the track jumping braking signal jp.
- continues to be output, and if τa >N, the process moves to step S, where the track jumping braking signal Jp- is released and the track jumping is completed.

For track jumping, for example, when a jumping command signal TJO between a plurality of tracks arrives, the servo loop is canceled during the track jumping period as shown in ■ in FIG. As shown in , in order to output the track skipping signal jp+ and detect the zero cross signal TZC due to true track skipping, a reference time width τa is set,
Reference time width τ of zero cross signal TZC shown in FIG. 6B
Wait for the arrival of a pulse exceeding a. Then, the reference time τa
The zero-crossing signal TZC exceeding
M is compared with the set value Mo, and the track skip signal Jp+ is continued to be output until M=Mo is reached. Then, when it reaches M-Mo, the track skipping signal Jp
At the same time as + is released, the track skipping braking signal JP- shown in D in FIG. 6 is generated, and the track jumping braking signal JP- continues to be output until the zero cross signal TZC reaches the reference time τa.

E in FIG. 6 represents the first arm feed signal SDI, F in FIG. 6 represents the second arm feed signal SD2, and each arm feed signal SD+% SDz is picked up by the arm 6 shown in FIG. For example, the arm feed signal SDI is used for the track skip signal Jp'' up to 100 tracks, and the arm feed signal SDK is used for the track skip signal Jp'' that exceeds 100 tracks. is selected, and the feed motor 8 is driven according to the number of track skips. Note that these signals SD+,
SD2 is selected or its width is adjusted depending on the device, and its fine adjustment is further performed by adding or subtracting the set value of the register for setting the servo signal.

G in Fig. 6 represents a section where the gain of the servo system is increased at the same time as track jumping ends, and the gain increase occurs when the frame synchronization signal arrives N times or when the error correction flag is released. It shall be cancelled. For example, as shown at H in FIG. 6, the synchronization confirmation signal GFS is
get.

Since the servo gain increase period is easily affected by disturbances, the gain increase period is defined as the period until this synchronization confirmation signal GFS is obtained continuously, and the gain increase of the servo loop is canceled when the regular synchronization confirmation signal GFS arrives. Then, the servo gain is returned to the normal playback gain, thereby stabilizing the servo operation and performing playback.

Next, in the case of skipping one track, the switch 58 is closed to the X side.

In this case, as well as canceling the servo loop, the counter 80
starts, counts clock pulses CLK, and stops counting if it is determined that there is no zero cross signal TZC. The count value N2 of the counter 80 is the zero cross signal TZ
It represents the time of C. The count value N2 of the counter 80 is multiplied by the coefficient k (=1/n) by the shifter 82 to obtain the count value k·NZ (<N2). Next, the count value -N2 is set in the counter 70, and the track skipping braking signal Jp- in the case of one track is output.

Next, the count setting value of the counter 70 is incremented by -N2 by counting the clock pulse CLK, and it is determined whether the count setting value k -N2 has become zero. -Nz in the count setting value represents the time width of the track-jumping braking signal Jp- in the case of track-jumping. Count setting value k −
If NZ is not O, trunk jump braking signal JP
- continues to be output, and when the count setting value -N2 becomes O, the track skipping braking signal Jp- is released and the skipping of one trunk is completed.

〔Effect of the invention〕

According to this invention, trunk jumping is started by a truck jumping signal, tracking error signals obtained thereby are counted, and when the counted value reaches a set value, the truck jumping signal is canceled, and Since track jumping is completed by generating a jumping braking signal, it is possible to quantitatively jump any track, and it can respond to the mechanical characteristics of the tracking mechanism, taking into account the characteristics of each individual tracking mechanism. In addition, the truck jumping time can be optimized according to the level of the truck jumping signal and braking signal.
Inter-track movement can be performed quickly and without malfunction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the disk servo device of the present invention, FIG. 2 is a diagram showing a tracking error, and FIG. 3 is a tracking error signal obtained based on the tracking error shown in FIG. Figure 4 is the first
FIG. 5 is a flowchart showing trunk jumping control, FIG. 6 is a timing chart showing truck jumping control, and FIG. 7 is an optical disk FIG. 8 is a diagram showing a conventional disk servo device in a reproducing apparatus, and is a timing chart showing track skipping in the disk servo device shown in FIG. 2...CD (disk) 4...Pink amplifier 48...Operation amplifier (tracking error detection means 56...Track skip control section (track skip control means) (a) (b) (
c) Figure 2 Figure 3

Claims (1)

[Claims] A disk servo device for controlling a pickup to a track position of a disk, comprising: tracking error detection means for detecting a tracking error from a detection signal of the pickup; Track jumping control means for counting the tracking error signal obtained by the tracking error detection means, performing track jumping driving until the number of skipped tracks reaches a specific value, and applying braking in accordance with the number of track jumping. Equipped with a disk servo device.