JPH0677377B2 - Disk servo device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk servo device suitable for an optical disk reproducing device and the like, and more particularly to changing a track position of a pickup.

[Conventional technology]

As shown in FIG. 7, the optical disk reproducing device for reproducing information such as music recorded on a compact disk (CD), as shown in FIG. 7, has a focus servo that focuses on the reflective surface of CD2, and tracks the track of CD2. 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 applied to the motor 3 for rotating the 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 it at 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 illuminated on the second reflective surface. Optical system 16 is focus coil 1
Driven by 8 and the tracking coil 20, the former focuses on the reflective surface of the CD 2 and the latter moves it 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. It is separated into an RF signal containing it, a focus error signal FE, and a tracking error signal TE, and the RF signal is output to a CLV servo system, an audio reproduction system, or the like.

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.

The tracking error signal TE is applied to the filter 32 and integrated, and then applied to the multiplexer (MPX) 34 to control the tracking coil 20 and the servo signal TS ₁ for controlling the feed motor 8. The feed servo signal TS ₂ is formed. The 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 braking 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 track is skipped in such a reproducing apparatus, a track jump signal Jp ⁺
As shown in H of the figure, when a track jump pulse having a constant time width τ _A is set and a track jump is performed by this track jump pulse, as a track jump braking signal Jp ⁻ for stopping at the track position. , As shown by I in FIG. 8, a track-jap braking pulse having a constant time width τ _B is set. Therefore, the period during which such a track jump is performed is given by the sum of the time widths τ _A and τ _B of each pulse, and as shown by K in FIG. 8, the time (τ _A + τ _B ) During this time, the servo loop is released. Further, the servo operation is started at the same time when the track jump is completed, and as shown at J in FIG. 8, the servo gain is increased only for the period given by the time τ _C , and the servo operation is instantaneously drawn.

Then, the time widths 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 relation to mechanical mechanisms such as the tracking mechanism and the feed mechanism of the pickup 4, Since it is empirically set for each mechanism of the device, if the matching with the mechanism cannot be obtained, malfunction may occur.

Therefore, the present invention intends to realize an appropriate track jump regardless of the mechanical mechanism by grasping the status of the track jump from 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 detects a tracking error from a detection signal of the pickup. The tracking error detecting means (operational amplifier 48) and the track jumping signal are generated in response to the track jumping command, and the tracking error signal obtained by the tracking error detecting means is received and the tracking error is based on the zero level. A track jump control means (track jump control unit 56) for generating a track jump braking signal having a pulse width of a time width of a signal is provided.

[Work]

The track jump control means generates a track jump signal Jp ⁺ in response to the track jump command. In response to the track jump signal Jp ⁺ , the pickup 4 moves in an arbitrary track direction on the disc. When a track jump occurs, the tracking error signal TE corresponding to the track jump
Is obtained from the tracking error detecting means. And
The track jump control means uses the tracking error signal TE
Braking signal in response to the signal Jp ^- to generate, pick-up 4
Will stop the movement immediately and end the track jump.

〔Example〕

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

This embodiment is a case of using a pickup by the three-beam method in which a main beam is projected to the center of the track and a sub beam is projected to a position slightly deviated to the left and right from the track of the CD2 track.

Photodetectors 42, 44 and 46 are installed in the light receiving section 24 of the pickup 4 in accordance with the number of beams, and each of the photodetectors 42, 44 and 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 a case where the main beam MB is displaced to the left, and FIG. 2C shows a case where the main beam MB is displaced to the right, and O is the center line of the on-track position. , O'represents a center line when they are shifted to the left and right. The tracking error signal TE obtained by the operational amplifier 48, when the main beam MB coincides with the track, has an amplitude corresponding to the deviation direction and the deviation width, as shown in FIG. With the position at zero level, the signal becomes an S-shaped signal having positive and negative amplitudes on the left and right.

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 after generating a gain control signal Gc, track jump brake signal Jp ^- outputting a.

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 Gc 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 the tracking error signal TE as shown in FIG.
56 generates a track jump control signal Jp ^- with a time width corresponding to the zero-cross pulse TZC and applies it to the driver 36. This ends the track jump. Upon completion of the track jump, the switch 52 is closed, the servo control is restarted, the gain control signal Gc is released, and the control operation is performed with the normal gain.

Therefore, in this disk servo device, track jumping is started by the track jumping signal Jp ⁺ , and the braking signal Jp ⁻ is generated according to the signal width of the tracking error signal TE obtained thereby, and the track jumping signal Since the pickup 4 is stopped at, a braking signal according to the mechanical characteristics of the tracking mechanism is obtained and
It is not necessary to adjust the characteristics of the individual tracking mechanism. Further, the track jump time can be optimized according to the levels of the track jump signal Jp ⁺ and the braking signal Jp ⁻ , 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.

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. The NAND circuit 58, the inverted signal of the track jump instruction signal _JO, non-inverted output Q and the track interlaced brake signal Jp of the flip-flop circuit 60 which is installed as a state storage means ^- by establishment of a logical product of the H (high )
The output is generated, and the output is D to the flip-flop circuit 60.
Added as input.

The non-inverted output Q of the flip-flop circuit 60 is the NAND circuit 62.
And the inverting input of its non-inverted output Q is ANDed with the OR circuit 64 and the output. 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 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 provided with the logical product of the inverted signal of the track jump signal Jp ⁺ and the count output of the counter 70, and the H output thereof is provided as the state storage means and the means for generating the track jump braking signal Jp ⁻ . D of the flip-flop circuit 72
Has been added to the input. When the H output is generated from the NAND circuit 68, the flip-flop circuit 72 generates the track jump braking signal Jp ⁻ as the non-inverted output Q.

Then, the non-inverted output Q of the flip-flop circuits 66 and 72 is
In addition to the AND circuit 74, the servo release signal S _B is formed by the logical product of the two.

The counter 76 and the comparator 78 are installed as signal determining means for determining whether or not the time width is the true zero-cross signal TZC. That is, the counter 76
Is a means to measure the time of the zero-cross signal TZC,
The non-inverted output Q of the flip-flop circuit 60 is the initial setting signal.
Since it is added as CL and the zero-cross signal TZC is added as a count control signal indicating the start and end of counting the clock pulse CLK, the time of the zero-cross signal TZC is output as the count value N ₁ of the clock pulse CLK. The count value N ₁ output is applied to the comparator 78 and compared with the reference time τa for determining whether or not the signal is the true zero-cross signal TZC. Comparator 78 outputs comparison output when τa <N ₁
The comparison output V ₂ is generated when V ₁ and 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 of the track jump signal Jp ⁺ , and its non-inverted output Q is added as an initial setting signal CL from the flip-flop circuit 60 and the zero-cross signal TZC is supplied as a clock pulse CLK. Is added as a count control signal indicating the start and end of counting of the reference time width τ
Zero count signal TZ with count value N ₁ corresponding to a as the initial value
Count until C goes to low (L) level. 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 and the multiplication result 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 an initial setting signal CL and a clock pulse is added.
CLK is added, the set value k · N ₂ from the shifter 82 is incremented and output by counting the clock pulse CLK, and the count time is added to the NAND circuit 68. Counter 70
May be composed of, for example, a register.

The generation of the track jump signal Jp ⁺ and the track jump braking signal Jp ^{− in} the above configuration will be described with reference to the flowchart shown in FIG. 5 and the timing chart of FIG.

In FIG. 5, it is started tracking servo operation, determines whether a track jump instruction signal T _JO in step S _1. If there is no track jump command signal T _JO , the judgment in step S ₁ is made.
Repeat until T _JO arrives.

When the track jump instruction signal T _JO is determined to have arrived, the process proceeds to step S _2, with initializes the counters 70,76,80, against the reset input of flip-flop circuits 60,66,72 The L input is given as the initial value IR to set the flip-flop circuit 60 in the preset state and the flip-flop circuits 66 and 72 in the reset state.

Then, it outputs a servo release signal S _B proceeds to step S _3, releases the servo loop opens switch 52.

Then, the process proceeds to step S _4, the track jump instruction signal T
_{Since JO} is given at H level, the NAND circuit 58 becomes L output and the non-inverted output Q of the flip-flop circuit 60 becomes L output. Since the output of the OR circuit 64 is the H output,
The NAND condition of the NAND circuit 62 is established, its 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 as the track jump signal Jp as shown in C of FIG. Output ⁺ . In this case, the track jump signal Jp ⁺ is given as a pulse of time τ ⁺ equal to the zero-cross signal TZC, as shown in C of FIG.

The pickup 4 moves between the tracks due to the track jump signal Jp ⁺ , but the movement causes a signal including the tracking error signal TE from the operational amplifier 48 shown in FIG. 1 to A shown in FIG. can get. These signals are applied to the zero-cross detection circuit 54, and the zero-cross detection circuit 54 obtains the zero-cross signal TZC shown in FIG. 6B as a signal corresponding to the signal component exceeding the zero level.

Next, in step S ₅ , the comparator 78 compares the count value N ₁ of the counter 76 with the reference time τa to determine the count value N ₁
Is greater than the reference time τa (τa <N ₁ ), the step
Return to S ₄ and continue to issue the track jump signal Jp ⁺ . When the count value N ₁ is smaller than the reference time τa (τa>
N ₁ ), the process proceeds to step S _{6, and} it is determined whether or not the zero-cross signal TZC is present. The presence or absence of the zero-cross signal TZC is given by the output of the OR circuit 64.

Meanwhile, when the servo loop is released in step S _3,
The counter 80 is started in step S ₇ , the clock pulse CLK is counted by the counter 80 in step S ₈ , and step S ₆
In case it is determined that the zero-cross signal TZC is not, to stop counting at step S _9. The count value of the counter 80 represents τ ⁺ at the time of the zero-cross signal TZC.

Next, the shifter to the count value N ₂ of the counter 80 in step S ₁₀ 8
The count k (= 1 / n) is multiplied by 2 and the count value k · N ₂ (<
N ₂ ). Next, in step S ₁₁ , the counter 70 is set to the count value k · N ₂ , and in step S ₁₂ , the track jump braking signal Jp ⁻ is output.

Next, in step S ₁₃ , the count setting value k · N ₂ of the counter 70 is incremented by counting the clock pulse CLK,
Count set value k · N ₂ at step S ₁₄ determines whether it is 0. The count set value k · N ₂ represents the time width τ ⁻ of the track jump braking signal Jp ⁻ shown in D of FIG. When the count setting value k · N ₂ is not 0, the track jump braking signal Jp ⁻ is continuously output, and when the count setting value k · N ₂ is 0, the track jump braking signal Jp ⁻ is released. , End the track jump.

Track jumping is performed, for example, when a jump command signal T _JO for one track arrives, a track jump signal Jp ⁺ is issued, and a pulse exceeding the reference time width τa of the zero-cross signal TZC shown in B of FIG. 6 arrives. Wait for Then, when the zero-cross signal TZC exceeds the reference time τa, it is determined as a normal pulse, the time τ ⁺ of the zero-cross signal TZC is measured, and it is set as the time of the track jump signal Jp ⁺ . The brake signal for stopping the pickup 4 on a track to the track jump is the track jump signal Jp ⁺ time tau ^+, time tau by multiplying the arbitrary coefficient k ^- is calculated, the time τ ^- track with a jump braking signal Jp ^- to generate. The coefficient k may be stored in advance in the storage means and may be read out appropriately to perform the calculation. Also, the coefficient k may be prepared by selecting a plurality of numerical values.

Since the servo operation is carried out at the same time as the end of the track jump, the gain of the servo loop is increased at the same time as the start of the track jump, and as shown in F of FIG. The servo loop is released during the track jump period. When the track jump ends, the increase in the servo loop gain is released in response to the end of the servo loop release period.

Also, since the servo operation and the operation of reading the frame synchronization signal from the CD2 have a close relationship, after the start of the servo operation, whether the synchronization signal of the servo loop can be normally confirmed, for example, , N synchronization signals are obtained to check the synchronization state, and when the synchronization state is entered, the servo gain may be released. F in Fig. 6
Indicates a synchronization confirmation signal GFS indicating that synchronization has been obtained. As indicated by a broken line E in FIG. 6, the gain increases until the synchronization confirmation signal GFS shown in F of FIG. 6 is continuously obtained. During the period, the gain increase of the servo loop is canceled by the arrival of the regular synchronization confirmation signal GFS, and the servo gain is returned to the normal reproduction gain. If the gain of the servo loop is increased, it is possible to instantly pull in the servo operation from the state of servo release, but since it is greatly affected by disturbance, wait for the arrival of the normal sync signal and restore the gain during normal playback. , It is possible to perform the reproduction by the stable servo operation which is not affected by the disturbance.

The gain of the servo system may be returned to the normal value when the error correction flag is released in computer control.

〔The invention's effect〕

According to the present invention, the track jump is started by the track jump signal, the control signal is defeated according to the signal width of the tracking error signal obtained thereby, and the pickup is stopped on the track to be transferred. It is possible to obtain a braking signal according to the mechanical characteristics of the tracking mechanism, and it is not necessary to adjust the characteristics of the individual tracking mechanism, and the track jump time is
It can be optimized according to the levels of the track jump signal and the braking signal, and the movement between tracks can be performed quickly and without malfunction.

[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 unit shown in FIG. 5, FIG. 5 is a flowchart showing the track jump control, FIG. 6 is a timing chart showing the track jump control, and FIG. 7 is an optical disk reproduction. FIG. 8 is a diagram showing a conventional disk servo device in the apparatus, and FIG. 8 is a timing chart showing track jumping in the disk servo device shown in FIG. 2 …… CD (disk) 4 …… Pickup 48 …… Operational amplifier (tracking error 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, which comprises a tracking error detecting means for detecting a tracking error from a detection signal of the pickup, and a track jump signal in response to a track jump command. A track jump control means for receiving a tracking error signal generated by the tracking error detecting means and generating a track jump braking signal having a pulse width of the time width of the tracking error signal with reference to a zero level. And a disk servo device.