JPH0677378B2 - Disk servo device - Google Patents

Description

The present invention relates to a disc servo device suitable for an optical disc reproducing device and the like.

[Conventional technology]

As shown in FIG. 6, an optical disk reproducing device for reproducing information such as music recorded on a compact disk (CD) has a focus servo for focusing on the reflective surface of CD2 and a track of CD2 as shown in FIG. Tracking servo, constant linear velocity (C
Various servo devices such as LV) servos are installed, and these servo devices perform control operations according to the reflected light from the CD 2 and the read sync signal. The signal D _CLV to the motor 3 for rotating CD2 represents the drive output from the CLV servo system.

The pickup 4 is for reading the data recorded on the track of the CD 2 and detecting the track position.
The laser light 12 emitted from the laser light source 10 which is moved in the diameter direction of the CD 2 by the feed motor 8 via the arm 6 passes through a half mirror 14 called a beam splitter, and an optical system 16 such as an objective lens. Focused and CD
It is irradiated on the second slope. Optical system 16 is focus coil 1
Driven by 8 and the tracking coil 20, the former focuses on the anti-slope of CD2 and the latter moves the focus onto the track.

Then, the reflected light 22 obtained from the CD2 is received by the light receiving section 24 composed of a plurality of light receiving diodes and is converted into an electric light receiving signal, which is added to the preamplification section 26, and an EFM signal or the like is added. The signal is separated into the RF signal including it, the focus error signal FE, and the tracking error signal TE, and the RF signal is output to the CLV servo system and the audio reproduction system.

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

Next, the tracking error signal TE is applied to the filter 32 and integrated, and then applied to the multiplexer (MPX) 34 to control the servo motor S ₁ for controlling the tracking coil 20 and the feed motor 8. A feed servo signal TS ₂ for jumping over a plurality of tracks is formed. MPX34
Operates by a control signal from a control unit (not shown), and the MPX34 performs track jump control by a track jump signal Jp ⁺ and a track jump control signal Jp ⁻ from the control unit.

Then, the servo signal TS ₁ obtained by the MPX34 is the driver 36
In addition, the tracking coil 20 is driven by the drive signal output from the driver 36. Further, the feed servo signal TS ₂ obtained by the MPX34 is integrated by the filter 38 to detect a direct current component, the direct current component is added to the driver 40, the motor 8 is driven by the output, and the pickup 4 is arbitrarily operated. Controlled by the track position.

[Problems to be solved by the invention]

By the way, when a plurality of tracks are skipped in such a reproducing apparatus, as a track jump signal Jp ⁺ , a pulse having a constant time τ _A is set as shown in D of FIG. track jump brake signal Jp for stopping the position ^- as shown in E of FIG. 7, are set to track jump braking pulse of fixed time tau _B. The respective times τ _A and τ _B are set to approximate values by previously converting the number of interlaced tracks into time by a microcomputer.

Track jump signal Jp ⁺ and track jump braking signal J
p ^- time tau _A of _the tau _B to draw simultaneously servo operation and the track jump completion, the period of the track jump is being performed, as shown in F of FIG. 7, the time (tau _A +
Servo operation is released during τ _B ).

Then, the times τ _A and τ _B of the track jump signal Jp ⁺ and the track jump braking signal Jp ⁻ are determined by an experimental method in association with mechanical mechanisms such as the tracking mechanism and the feed mechanism of the pickup 4, It is necessary to empirically set each mechanism, and the time cannot be set precisely. Therefore, rough control is performed, and if the mechanism and the mechanism cannot be matched, malfunction may occur.

Therefore, the present invention intends to realize the proper track jump regardless of the mechanical mechanism by grasping the status of the track jump based on the tracking error signal.

[Means for solving problems]

As shown in FIG. 1, the disc servo device of the present invention is a disc servo device for controlling a pickup (4) to a track position of a disc (CD2), and tracking for detecting a tracking error from a detection signal of the pickup. An error detection means (operational amplifier 48) and a zero-cross detection means (zero-cross detection circuit 54) that detects a point where the tracking error signal obtained by the tracking error detection means crosses a zero level and generates a zero-cross signal representing the zero-cross point. ) And a time (N ₁ ) between adjacent zero-cross points represented by the zero-cross signal obtained by the zero-cross detection means and a reference time (τa) are compared with each other. When the reference time is exceeded, the current track is Track jump control means (track jump control section 56) for shifting the position of the pickup from the track to another track.

[Work]

The track jumping control means responds to the track jumping command (track jumping command signal T _JO ) with the track jumping signal J.
generate p ⁺ . Depending on this track jump signal Jp ⁺ ,
The pickup 4 moves in an arbitrary track direction of the disc. When a track jump occurs, a tracking error signal TE corresponding to the track jump is obtained from the tracking error detection means, and this tracking error signal TE is added to the zero cross detection means and a zero cross corresponding to a signal component exceeding the zero level is obtained. Signal TZC is detected. Then, the track jump control means, when the track jumps,
The time (N ₁ ) of the zero-cross signal obtained by the zero-cross detecting means is compared with the reference time τa, a zero-cross signal exceeding the reference time τa is detected, and a track jump is performed based on the zero-cross signal.

[Embodiment] FIG. 1 shows an embodiment of a disk servo apparatus of the present invention.

This embodiment is a case where a pickup by the three-beam method is used in which the main beam is projected to the center of the track with respect to the CD2 track and the sub-beam is projected to a position slightly left and right from the track. Are installed with photodetectors 42, 44, 46 according to the number of beams, and each photodetector 42, 44, 46 is composed of, for example, a light receiving diode. The photodetector 42 is the main beam MB, and the photodetectors 44 and 46 are the sub-beams SB ₁ and SB _2.
And the detection output RF of the main beam MB of the photodetector 42 is added to an audio system (not shown).
The detection signals Va and Vb obtained in step 3 are added to the operational amplifier 48 installed as tracking error detecting means for detecting a tracking error, and the tracking error signal TE is detected.

By the way, the main beam MB and the sub-beams SB ₁ and SB ₂ are
As shown in (b) of the figure, when the main beam MB is aligned with the pit P of the track, the sub beams SB ₁ and SB ₂ are
It is set so as to be shifted from the pit P to the left and right, and the shift widths are equal. 2A shows the case where the main beam MB is displaced to the left, and FIG. 2C shows the case where the main beam MB is displaced to the right, and O is the center line of the on-track position. O'represents the center line when it is shifted to the left and right. And
Tracking error signal obtained by operational amplifier 48
When the main beam MB coincides with the track, TE exhibits an amplitude according to the deviation direction and the deviation width, and positive and negative amplitudes are set to the left and right with the on-track position at the zero level, as shown in FIG. The S-shape it has is given by a signal.

The tracking error signal TE is applied to the filter circuit 50 including a low-pass filter and converted into a DC signal, and then applied to the driver 36 via the switch 52. The switch 52 is installed to shut off the servo system during a track jump, and is closed during tracking control other than the track jump.

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 excitation degree and the excitation direction according to the tracking error signal TE, and generates a driving force that pulls back to the left in the case of right shift and to the right in the case of left shift. . Therefore, the pickup 4 is controlled on the track by the tracking control.

Then, the zero-cross detection circuit 54 crosses the zero level of the tracking error signal TE to generate a signal corresponding to the positive-side signal component, for example, a zero-cross pulse TZC, and applies it to the track jump control unit 56. Truck jump control unit
Reference numeral 56 is a control device such as a microcomputer mounted on the optical disk reproducing device, or is configured as an independent circuit, and performs track jump control according to the track jump command signal T _JO . That is, the track jump command signal T _JO
Is added to the track jump control unit 56, the track jump control unit 56 shifts to the operating state and enters the track jump mode, and the servo release signal S _B and the track jump signal Jp ⁺
And a gain control signal G _C are generated, and then a track jump braking signal Jp ⁻ is output.

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

The track jump signal Jp ⁺ has a signal mode corresponding to the track jump direction and is designated by the track jump instruction. This track jump signal Jp ⁺ is a driver 36
In addition, the tracking coil 20 is forcibly excited for the track jump, and the pickup 4 moves in the desired track direction. At this time, the driver 36 is set to, for example, the maximum gain by the gain control signal G _{C in} order to shift to the normal control state when the track jump is released.

When the pickup 4 moves between tracks, the movement causes a tracking error signal TE as shown in FIG.
Zero crossing signal TZ of tracking error signal TE
Ask for C. Reference time τa of this zero-cross signal TZC
A true tracking error signal has a time that exceeds
Since it corresponds to the TE, it continues out to detect and track interlaced signal Jp ⁺ this track jump signal Jp ⁺ end at the same time as the track jump brake signal Jp ^- issue. The track jump braking signal Jp ^- is output until the time width of the zero-cross signal TZC exceeds the reference time τa, and the track jump ends. Upon completion of the track jump, the switch 52 is closed, the servo control is restarted, the gain control signal G _C is released, and the normal gain control operation is performed.

Therefore, in this disk servo device, the track jump is started by the track jump signal Jp ⁺ , and the pulses exceeding the reference time τa of the zero-cross signal TZC of the tracking error signal TE obtained thereby are counted up to the set jump track number. together, lasts a track jump signal Jp ⁺ until the count end point, the count end point from the track interlaced brake signal Jp ^- to generate, this track interlaced brake signal Jp ^- a zero-cross signal TZC is a reference time τ
Continues until a is exceeded and finishes track jumping of multiple tracks. For this reason, a braking signal according to the mechanical characteristics of the tracking mechanism is obtained, so that it is not necessary to make adjustments in consideration of the characteristics of individual tracking mechanisms. Also,
The track jump time can be optimized according to the levels of the track jump signal and the braking signal, and the inter-track movement can be performed quickly and without malfunction.

Next, FIG. 4 shows a specific configuration example of the track jump control unit 56 of the disk servo device shown in FIG. In this configuration example, both a single track jump and a plurality of track jumps can be performed, the switch 57 is switched according to the number of jump tracks, and X is one track jump, Y is closed in case of jumping over two or more tracks.

The track jump instruction signal T _JO is given by the step signal and is applied as a negative input to the NAND circuit 58 which constitutes the inhibition circuit. This NAND circuit 58 is H when the logical product of the inverted signal of the track jump command signal T _JO , the non-inverted output Q of the flip-flop circuit 60 installed as the state storage means and the track jump control signal Jp ⁻ is established.
It produces a (high) output and applies that output as the D input to the flip-flop circuit 60 which is reset by the initial value input IR.

The non-inverted output Q of the flip-flop circuit 60 is the NAND circuit 62.
And the inverting input of its non-inverting output Q and the output of the OR circuit 64 are ANDed. The H output of the NAND circuit 62 is the D of a flip-flop circuit 66 provided as state storage means and means for generating the track jump signal Jp ^+.
Added to input. When the H output is applied from the NAND circuit 62, the flip-flop circuit 66 reset by the initial value input IR outputs the track jump signal Jp ⁺ as its non-inverted output Q and applies it to the NAND circuit 68. The NAND circuit 68 is
Inverted signal of track jump signal Jp ⁺ and count output of counter 70 or comparator obtained via switch 57
The logical product of the comparison output V _{2 of} 71 and the H output thereof is added to the D input of the flip-flop circuit 72 provided as the state storage means and the means for generating the track jump braking signal Jp ⁻ . When the H output is generated from the NAND circuit 68, the initial value input
Flip-flop circuit 72 is reset by the IR non-inverting output Q as a track jump brake signal Jp ^- generates. Then, the non-inverted output Q of the flip-flop circuits 66 and 72 is added to the AND circuit 74, and the logical product of the two outputs the servo release signal S _B.

The counter 76 and the comparator 71 are installed as signal determining means for determining whether or not it is the true zero-cross signal TZC. That is, the counter 76 displays the zero-cross signal TZ.
The flip-flop circuit 6 is a means for measuring the time of C.
Since the non-inverted output Q of 0 is added as the initial setting signal CL and the zero-cross signal TZC is added as the count control signal indicating the start and end of counting the clock pulse CLK, the time of the zero-cross signal TZC is set to the count value of the clock pulse CLK. Output with N ₁ . The count value N ₁ output is applied to the comparator 71 and compared with the reference time τa for determining whether or not the signal is the true zero-cross signal TZC. The comparator 71 is
The comparison output V ₁ is generated when τa <N ₁ , and the comparison output V ₂ is generated when τa> N ₁ .

The comparison output V ₁ is applied to the counter 80 as a count drive signal, and upon arrival of the comparison output V ₁ , the counter 80 starts counting clock pulses CLK. The counter 80 is a time setting means for setting the time width of the track jump signal Jp ⁺ , the non-inverted output Q from the flip-flop circuit 60 is added as an initial setting signal CL, and the zero cross signal TZC is used as a clock. It is added as a count control signal indicating the start and end of counting the pulse CLK, and counting is performed until the zero-cross signal TZC shifts to the low (L) level with the count value N ₁ corresponding to the reference time τa as the initial value. This count value
N ₂ represents the time of the zero-cross signal TZC.

This count value N ₂ is added to a shifter 82 as a counting and multiplying means installed as a time setting means for setting the time of the track jump braking signal Jp ⁻ , and a coefficient k for obtaining an optimum braking time is obtained. _{They are} multiplied together and the multiplication result is k · N ₂
Is set in the counter 70. The counter 70 is a time setting means for setting the braking time as a real time, and the non-inverted output Q from the flip-flop circuit 60 is added as the initial establishment signal CL and the clock pulse is generated.
CLK is added, and the set value k · N ₂ from the shifter 82 is incremented and output by counting the clock pulse CLK, and the counting time is added to the NAND circuit 68. Counter 70
May be configured by a register, for example.

Further, the zero-cross signal TZC is added to a counter 84 provided as a counting means for counting the number of a plurality of interlaced tracks, and the count value M and the set number M ₀ added by the initial setting.
And are compared by the comparator 86. The comparison output of the comparator 86 and the comparison output V ₂ of the comparator 71 are
The AND circuit 88 takes the logical product. Along with the output of the AND circuit 88, the comparison output V ₁ of the comparator 71 is added to the OR circuit 64 and becomes the logic input of the NAND circuit 62.

In the above configuration, the track jump signal Jp ⁺ and track interlaced brake signal Jp ^- zero cross signal TZ corresponding to a reference to generate a true tracking error signal TE
The determination of C will be described with reference to FIG.

FIG. 5A shows the tracking error signal TE obtained by the operational amplifier 48 shown in FIG. When this tracking error signal TE is applied to the zero-cross detection circuit 54, the fifth error is detected depending on the presence / absence of a signal component exceeding the zero level.
As shown in B of the figure, the zero-cross signal TZC is obtained.
The zero-cross signal TZC is given by a rectangular wave pulse in which a signal component exceeding the zero level is shaped into a rectangular wave.

By the way, track jump is a track jump signal Jp ⁺
Initiated by the track jump control signal Jp ^- because the brake operation is performed, as shown in A of FIG. 5,
A tracking error signal TE having a different frequency can be obtained according to the track jump. The tracking error signal TE is
As shown in A of FIG. 5, it is obtained when the vehicle deviates from the track, but in the case of jumping over a plurality of tracks, the frequency changes in proportion to the speed of jumping over the tracks. That is, the tracking error signals TE ₁ and TE ₂ immediately after the start of the track jump, the tracking error signals TE ₆ and TE ₇ immediately before the end of the track jump, and the tracking error signals TE ₃ and TE during the track jump. ₄ and TE ₅ , it is clear that the frequency of the former is low, and the time width of the zero-cross signal TZC is correspondingly larger in the former.

Therefore, the zero-cross signal TZC having a narrow time width is made an unnecessary signal, and the reference time τa is set in order to detect the true zero-cross signal TZC. This reference time τa is the comparator
The counter 76 is set as a reference comparison value in 71, and the counter 76 measures the time width of the zero-cross signal TZC by counting the clock pulses CLK. That is, the comparator 71 counts the count value N ₁ generated in the counter 76 by the measurement of the zero-cross signal TZC.
And the reference time width τa are compared, and the count value N ₁ is the reference time τa.
If it is larger than a (τa <N ₁ ), the true zero-cross signal TZ
Generates a decision output representing C. C in FIG. 5 represents the count value N ₁ of the counter 76, and when N ₁ exceeds the reference time τa, a judgment output representing the true zero-cross signal TZC is obtained.

Thus, for jumping a plurality of tracks, counted the time width of the zero-crossing signal TZC by the counter 76, the time a track jump braking signal of the zero-cross signal TZC Jp ^- with a time that exceeds the reference time τa due to braking is applied by It is determined that the normal tracking speed has been restored. From this, Ta is set as the jumping section by the time detection of the zero-cross signal TZC, and the actual track jumping section is set as Tb.

In case of jumping one track, zero cross signal
The arrival of the true zero-cross signal TZC can be determined by comparing the time of TZC with the reference time τa.

〔The invention's effect〕

According to the present invention, the time of the zero-cross signal of the tracking error signal obtained by the track jump is compared with the reference time, the true tracking error signal is detected, and the track jump is performed. In addition to being able to jump quantitatively, it is possible to respond to the mechanical characteristics of the tracking mechanism, making adjustments that take into account the characteristics of individual tracking mechanisms unnecessary, and performing track jumps quickly and without malfunction. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a disk servo device of the present invention, FIG. 2 is a diagram showing tracking errors, and FIG. 3 is a tracking error signal obtained based on the tracking errors shown in FIG. Shown in Figure 4, Figure 1 is
FIG. 5 is a block diagram showing a specific configuration of the track jump control section shown in FIG. 5, FIG. 5 is a timing chart showing track jump control, and FIG. 6 is a view showing a conventional disk servo device in an optical disk reproducing device. FIG. 7 is a timing chart showing track jumps in the disk servo device shown in FIG. 2 …… CD (disk) 4 …… Pickup 48 …… Operational amplifier (tracking error detection means 54 …… Zero cross detection circuit (zero cross detection means) 56 …… Track jump control section (track jump control means)

Claims (1)

[Claims] 1. A disk servo device for controlling a pickup to a track position of a disk, wherein a tracking error detecting means for detecting a tracking error from a detection signal of the pickup and a tracking error signal obtained by the tracking error detecting means are zero. Zero-cross detection means for detecting a point crossing the level and generating a zero-cross signal representing the zero-cross point, and time between adjacent zero-cross points represented by the zero-cross signal obtained by the zero-cross detection means when jumping a track and Track jump control means for comparing the pickup position from the current track to another track based on the zero cross signal when the time between zero cross points exceeds the reference time by comparing with the reference time. A device that is equipped with Disk servo device.