JPS62259269A - Tracking controller - Google Patents

Abstract

PURPOSE:To attain a smooth pull-in operation to an objective track after the generation of drop-out by extracting a memory value from a memory means in a compensating means to form a control signal. CONSTITUTION:The compensating means 8 is provided with an error detecting means for obtaining an error signal corresponding to a detecting signal from a tracking detecting means 5 and the memory means 10 storing plural memory values. When a drop-out is detected by a drop-out detecting means 7, the memory values stored in the memory means 10 in the means 8 are successively extracted synchronously with pulse signals from a rotary clock generating means 4 without using the detecting signal from the means 5 to form a control signal synchronizing with the rotation of a disk. Thus, the objective track can be tracked immediately after releasing the drop-out by changing a tracking position so as to follow the objective track at the generation of disk eccentricity.

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a tracking control device used in a disc player or the like. Conventional tracking control devices that detect the tracking state of a disc on which technical information is recorded and control the power supplied to a tracking actuator based on the detection signal are widely used in disc playback (recording) devices such as compact disc players. has been done. However, the conventional tracking control device only performs conventional proportional, integral, and differential control, and has been unable to sufficiently suppress tracking fluctuations. In particular, when installing a disk, disturbance components due to eccentricity cause large tracking deviations.
It was becoming a problem. In order to solve such problems, the applicant has filed a patent application filed in 1983.
In Japanese Patent Application No. 0-229141 and Japanese Patent Application No. 60-229142, we proposed a high-performance control device that is highly resistant to disturbance signals. That is, Japanese Patent Application No. 60-229141 and Japanese Patent Application No. 60-229142 disclose a detection means for detecting the controlled state quantity of a controlled object, and a compensation means for calculating and storing a control signal based on the detection signal of the detection means. A control system is constituted by an amplification drive means for supplying a drive signal corresponding to a control signal of the compensation means to the controlled object. Furthermore, an error detection means for obtaining an error signal in response to the detection signal of the detection means, and a group M of Nx (plural) memory values.

Composite value calculation that essentially calculates a composite value that is compositely calculated using a memory means for storing M (N x L-1) from [0] and a group of Nx memory values separated by L intervals of the memory means (memory output value creation means), the memory value of the memory means is substantially updated and saved in order with an update value corresponding to a value obtained by calculating and combining the composite value of the composite value calculating means and the error signal of the error detecting means. A high-performance control device is realized by using a compensating means having a storage means and a control signal generating means which generates a control signal by calculating and combining the composite value of the composite value calculating means and the error signal of the error detecting means. ing. Problems to be solved by the invention Japanese Patent Application No. 60-229141 and Japanese Patent Application No. 60-22914
It has been found that when the control device shown in No. 2 is used as a tracking control device, it is necessary to make some improvements. For example, in the case of tracking control for a compact disc player, rotational speed control is performed to keep the linear velocity constant in order to lengthen the playing time. Therefore, the rotational speed of the disc changes depending on the position (radius) of the track being played back. On the other hand, the disturbance signal was mainly due to disk eccentricity, and was synchronized with the rotation of the disk. Therefore, the frequency of the disturbance signal changes as the tracking position of the disk changes, and the structure of the above patent cannot sufficiently reduce the tracking error. Furthermore, if a dropout of the reproduced signal occurs due to a scratch on the disc or the like, the tracking detection signal also disappears. At this time, if disk eccentricity occurs, even a short dropout will cause a significant deviation in the tracking position, and after the dropout is resolved, the disk may move to another track (trunk jumps). )
also occurred frequently. Therefore, countermeasures against such dropouts are also important. In consideration of these points, the present invention provides a tracking control device that sufficiently reduces the influence of disturbance signals synchronized with rotation such as disk eccentricity, and also takes measures against dropouts. . Means for Solving the Problems The present invention provides tracking detection means for detecting the tracking state of a disk, rotation clock generation means for synchronizing with the rotation of the disk and generating a plurality of pulse signals per rotation, and dropout detection means for detecting a dropout of a reproduced signal from the tracking detection means; compensation means for generating a control signal based on the detection signal of the tracking detection means; and drive means for driving the trunking actuator in accordance with the control signal of the compensation means. The compensation means includes an error detection means for obtaining an error signal in response to a detection signal of the tracking detection means, a memory means for storing a plurality of memory values, and at least one memory value stored in the memory means. memory output value creation means for creating a memory output value using the memory values of the memory output value; update storage means for substantially sequentially updating and storing memory values of the means; and control signal generation means for generating the control signal by calculating and combining the memory output value of the memory output value generation means and the error signal of the error detection means. The memory output value creation means and the update storage means operate in synchronization with the pulse signal of the rotation clock generation means, and when a dropout is detected by the dropout detection means, the The 1j, 1'a times signal is generated by sequentially extracting the memory values accumulated and stored in the memory means in synchronization with the pulse signal of the rotation clock generating means without using the detection signal of the trunking detecting means. By configuring this, the above problems are solved. Function: The present invention realizes a high-performance tracking control device by adopting the above-mentioned configuration. In other words, the improved control characteristics of the control device as shown in Japanese Patent Application Nos. 60-229141 and 1982-229142 are designed to always match the frequency of the rotation of the disk. This ensures that tracking deviations due to eccentricity hardly occur. Furthermore, in the event of a dropout, by creating a control signal synchronized with the disk rotation using the memory contents accumulated and saved in the memory means, the tracking position is adjusted to follow the target track as much as possible even if disk eccentricity occurs. This has been improved so that it can quickly track on the target track after the dropout is resolved. Embodiment An embodiment of the tracking control device of the present invention will be described below with reference to the drawings. FIG. 2 shows a configuration diagram representing an embodiment of the present invention. The disk 1 on which information has been recorded is rotated by a spindle motor 2 at a rotational speed (constant linear velocity) corresponding to the tracking position. An alternating current signal a for speed detection synchronized with the rotation of the spindle motor 2 is applied to one of the disks l.
It is an alternating current signal of Zq times per rotation (here, Zq is an integer of 4 or more, usually Z q =360). The rotation clock generator 4 shapes the waveform of the alternating current signal a, drives an edge-triggered flip-flop at the rising edge of the shaped signal, and changes the clock signal q to "H" (high potential state). A compensation controller 8, which will be described later, monitors the clock signal q becoming "I4", and after confirming that q="H", sets the reset signal r to "I" for a predetermined short time, and Set the above flip-flop to “L” (low potential state B)
, and set the clock signal q to "L". As a result, the clock signal q becomes a pulse signal synchronized with the rotation of the disk 1 (pulse signal Zq times per rotation). The information on the disc 1 is read by an optical reading mechanism including a semiconductor laser, an optical element such as a lens, a photodetector, etc. mounted on the pickup unit 3, using the reflected light of the laser beam on the information surface of the disc 1. be read as such. The optical reading mechanism of the pickup section 3 includes a tracking actuator, and moves the tracking position by controlling current to the tracking actuator. The reflected beam from the information surface of the disk l is converted into an electric signal by the tracking detector 5, and output as a digital signal e corresponding to the difference (tracking error) between the laser beam spot position on the disk 1 and the target track position. Also,
The reflected beam from the information surface of the disc 1 is outputted as an alternating current information signal by an information signal detector 6. The dropout detector 7 determines a dropout when the AC amplitude of the information signal S becomes less than a predetermined value, and sets the dropout detection signal p to 'H'. Note that during normal playback (when there is no dropout) has a dropout detection signal p
is set to "L". The compensation controller 8 is composed of an arithmetic unit 9, a memory 10, and a D/A converter 11, and receives the pulse signal q of the rotation clock generator 4 and the digital signal e of the tracking detector 5.
and the dropout detection signal p of the dropout detector 7
is manually calculated and processed using a built-in program to be described later, and a control signal C is output. Control signal C of compensation controller 8
is input to the driver 12, and the power amplified drive signal (h
! A current proportional to the control signal C) is supplied to the tracking actuator of the pickup section 3. The tracking actuator generates a torque proportional to the drive signal,
Controls the laser beam spot position. Therefore, a tracking control system is constituted by the tracking detector 5, the compensation controller 8, the driver 12, and the trunking actuator of the pickup section 3, and is controlled so that the laser beam accurately follows the target trunk. The memory 10 of the compensation controller 8 is divided into a ROM area (ROM: read-only memory) in which predetermined programs and constants are stored, and a RAM area (RAM: random access memory) in which necessary values are stored. The arithmetic unit 9 performs predetermined operations and calculations according to a program in the ROM area. A specific flowchart of the program is shown in FIG. 1. Next, the operation will be explained in detail. (1) <Rotation Synchronization section> First, the arithmetic unit 9 receives the pulse signal q of the rotation clock generator 4.
is input and is waiting for the signal q to become "H". That is, rotation of the spindle motor 2 through a predetermined angle is monitored. When q becomes “H”, the reset signal r
is set to "H" for a predetermined short time to clear the flip-flop of the rotation clock generator 4. (2) <Error/state input section> Reads the digital signal e from the tracking detector 5 and converts it into a tracking error value E corresponding to the digital signal e. Dropout detection 2" Read the dropout detection signal p of fr7. (3) <Control signal creation section> a) When p = "L" (during normal playback) Memory output value by the memory output value creation section described later ■ and the current tracking error E to a predetermined ratio D:1 (here, D is OD
The control signal value Y is calculated by performing calculation and synthesis using a constant D≦1, preferably D=1 (Y=E〒DV,). The control signal value Y is output to the D/A converter 11 and converted into a DC voltage (control signal C) corresponding to the value of Y. o) When p=“I” (at the time of dropout) Memory output value ■ by the memory output value creation unit described later. is directly set to the control signal value Y (Y=VO). The control signal value Y is output to the D/A converter 11 and converted into a DC voltage (control signal C) corresponding to the value of Y. (4) <Count section> N x - L (Generally, Nx is an integer and L is an integer of 4 or more. Here, it is preferable that Nx is an integer of 2 or more and L is an integer multiple of Zq, so from now on this A case like this will be explained below.) is used as a mod, and the count variable I is counted and amplified every time a new l-ranking error value E is obtained. That is, after setting [=I+1, I=N
If xL, reset I to 0. If such an operation is performed, I will be an integer between O and NxLl. Note that the initial value of ■ is NxLl. (5) <Memory output value creation unit> Integer J equal to I (J=I), L in the ram area
A group of Nx memory values MCJ-nL (m
od NxL)) (n=1.-, Nx), the memory output value ■ is determined by the following formula. create. Nx −−−−−−−−−・−・−・−(1) Here, the ratio W
The value of n is 0<Wn<2/Nx (n=1....+, Nx)
And, furthermore, Nx, Σ W n = l −・・−・
−・−・−・(3) Standardized as n=1. Specifically, when Nx≧2, Wn=1/Nx (n=1. . . . , N
x)---------------------- When (4) is used, equation (1) becomes the memory value group M (J -n L (mod
NxL)) (n=1. . . . +, Nx) is simply added and combined and then divided by Nx (an integer), making the calculation extremely simple (however, this is not limited to this case). (6) <Update storage unit> a) When p=“L” (during normal playback), memory output value ■ by the memory output value creation unit. and the tracking error E to calculate an update value, and update the memory value M (I) in the RAM area corresponding to the count variable I M (1)
=E+v. ), stored until the next update. After that, the operation returns to (1). a) When p=“H” (at the time of dropout), the update operation is not performed and the operation returns to (1). With this configuration, tracking deviation due to the eccentricity of the disk 1 will hardly occur. This will be further explained. It has been found that the eccentricity of the disk 1 is the largest cause of tracking errors. Disc eccentricity is 0 for trunk spacing of 1.6μm
．． In order to allow 8 m, the gain of the tracking control system needs to be 60 dB or more. However, with the conventional control system, it is difficult to increase the gain, and if the disk eccentricity is slightly large, tracking may occur, making reproduction impossible. Further, since the frequency of tracking fluctuation caused by the eccentricity of the disk 1 matches the rotational frequency of the spindle motor 2, the frequency also changes as the tracking position moves. In this embodiment, the operations of the update storage section and the memory output value creation section proceed in synchronization with the pulse signal q of the rotation clock generator 4. Therefore, the frequency at which the control characteristic improvement effect appears can always be matched to the rotational frequency of the disk l (see the earlier patent for the control characteristic improvement effect). As a result, it is possible to obtain a gain of 80 dB or more at this frequency, and tracking fluctuations due to eccentricity of the disk 1 can be significantly reduced. Furthermore, in this embodiment, the tracking pull-in operation after dropout occurs is also improved. This will be explained. In the conventional control system, when a dropout occurs, the control signal is set to zero (or a constant value) to fix the position (tracking position) of the tracking actuator of the pickup section 3. However, in such a method, if the disk 1 is eccentric, the track position will change within a short period of time. As a result, the target track and the laser beam position were significantly misaligned, resulting in a longer tracking pull-in time after the dropout was resolved, or if the disk eccentricity was large, the laser beam could be pulled onto a different track. (Truck jump). In contrast, in this embodiment, when a dropout occurs, the update operation using the error signal is stopped in the update storage section, and the memory value stored in the memory 10 is used to correspond to the rotational position of the disk. (count variable
(corresponding to) is retrieved, and the memory output value is directly output as a control signal. Therefore, as the disk l rotates, the tracking actuator of the pickup section 3 is displaced in accordance with the memory output value, and operates as if it were following a track. This is due to control operations during normal playback before dropout occurs.
This is possible because memory values corresponding to disk eccentricity are stored in the memory 10. As a result, since the laser beam position is always located near the target track, the laser beam is quickly pulled onto the target track after the dropout is eliminated. This also has the effect of greatly reducing unpleasant phenomena caused by track skipping (stops in reproduced sound and discontinuous sounds). Note that when dropout occurs, the update storage section may perform update storage operation using only the memory output value, and it goes without saying that this is included in the present invention. FIG. 3 shows a flowchart of a program for the compensation controller 8 that takes into consideration the stability of the entire control system. Here, we will explain how to calculate the update value in the update storage section,
The number of memory output values prepared in the memory output value generation section and the way the memory output value generation section uses the memory output values in the control signal generation section are improved. Next, its operation will be explained in detail (the overall configuration is the same as that in FIG. 2, so the explanation will be omitted). aυ <Rotation synchronization section> First, the arithmetic unit 9 receives the pulse signal q of the rotation clock generator 4
is input and is waiting for the signal q to become "H". That is, rotation of the spindle motor 2 through a predetermined angle is monitored. When q becomes “H”, the reset signal r
is set to "H" for a predetermined short time to clear the flip-flop of the rotation clock generator 4. Error/state input section> Reads the digital signal e from the tracking detector 5 and converts it into a tracking error value E corresponding to the digital signal C. Read the dropout detection signal p of the dropout detector 7. 0■ Control signal generation unit> a) When p=“L” (during normal playback) The memory output value V (Px) by the memory output value generation unit, which will be described later, and the current tracking error E are set at a predetermined ratio D:1. to calculate the control signal value Y (Y-E+D ・V (Px
)), the control signal value Y is output to the D/A converter 11, and converted into a DC voltage (control signal C) corresponding to the value of Y. ) When p=“H” (during dropout), the memory output value V (Px) by the memory output value creation unit described later is directly set to the control signal value Y (Y=V (Pxl). Control signal value Y
is output to the D/A converter 11 and converted into a DC voltage (control signal C) corresponding to the value of Y. Qa <Count section> Using NX-L as mod, count variable 1 is counted up every time a new tracking error value E is obtained. aω <Memory output value creation unit> After sequentially transferring the contents of register variable V (m + 1) to V (m) (m = o, 1. ..., Pxl)
, Nxl, is used as mod to calculate the integer J, which is the count variable l plus Px (here, Px is an integer greater than or equal to 1 and less than or equal to 6, and PX=3 is preferable) (J=I+Px
(mod NxL)) o Memory value group M in the RAM area
(J-nL (mod NXL)) (n=1.
..., Nx) and enter the latest memory output value calculated by the following formula into V(Px). NX Here, the value of Wn satisfies equations (2) and (3). That is, from V(Px) to v

Px+1 consecutive to [0]
Obtain a group of memory output values. At this time, let Jl be the integer J in formula (5) when calculating V(Px), and

If the integer J in formula (5) when calculating [0] is J2, then Jl
There is a relationship of −J2+Px. 06) <Update storage section> a) When p=“L” (during normal playback) Register variable X
After sequentially transferring the contents of (m+1) to X [m], (
m=0.1,2. .... 2Kd-1),

Enter the composite value obtained by calculating [0] and the tracking error E (X (
2Kd)=E+V(0)). That is, X (2Kd
) to obtain 2Kd+1 consecutive addition values (addition values of the memory output value and tracking error) from X (0). Nx
Calculate the integer K by subtracting Kd from the count variable I with L as nod (K = I - Kd (nod NxL)),
Next, a predetermined positive ratio Cm (m=0.1
．． -..., 2Kd) is added and combined to obtain a new updated value, which is stored as a memory value M (K) in the RAM area until the next update. That is, let it be. Here, the ratio Cm has the following relationship. CCm=C2Kd-(m=Q, 1...., Kd)
−・−・−・−(7) After that, the operation returns to aυ. o) When p=''I HII (dropout), the update operation is not performed and the aυ operation is returned to. As in this embodiment, an operation for taking a weighted average is inserted into the update storage section, or a control signal The first memory output value V (Px) of the memory output value creation section used in the creation section and the second memory output value V (Px) of the memory output value creation section used in the update storage section ■

The predetermined deviation (V (Px)) between [0] is
]), the operation of the entire control system will become stable. Note that calculations using the ratios Wn and Cm are not limited to the above formats, but may be used as long as they substantially realize the content of the above program (although various equivalent formula transformations are possible). Needless to say. Also, when a new tracking error is obtained, the control signal generation section first outputs a new control signal, and then the memory output value generation section generates the memory output value to be used at the next sampling point. If it is calculated, the calculation time of the memory output value creation section can be lengthened, and the time delay until the control signal is output can be shortened, making it easier to ensure the stability of the control system. The output of the compensation controller may be a digital signal or a PWM signal (pulse width modulation signal).Furthermore, the compensation controller may be a PLA (programmable logic signal).
array) etc., consisting of complete hardware,
The same operations as those performed by the program described above may be performed. Alternatively, analog calculation elements may be used (especially for the operation of the control signal generation section).
. In addition, various modifications can be made without changing the gist of the present invention. ADVANTAGEOUS EFFECTS OF THE INVENTION In the tracking control device of the present invention, tracking deviation due to disk eccentricity is significantly reduced, and the pulling operation to the target trunk after dropout occurs is performed extremely smoothly. Therefore, if a tracking control device for a compact disc player is constructed based on the present invention, a high performance compact disc player can be obtained.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an example of the built-in program of the compensation controller of FIG. 2, FIG. 2 is a block diagram of the entire trunking control device of the present invention, and FIG. 3 is a built-in program of the compensation controller of the present invention. It is a flowchart figure showing other examples of. 1...Disc, 2...Spindle motor, 3...Pickup section, 4...
Rotation clock generator, 5...Tracking detector, 6...Information signal detector, 7...After dropout occurs, 8...Compensation controller , 9・
...Arithmetic unit, 10...Memory, 11...
...D/A converter, 12...driver. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1

Claims (1)

[Claims] tracking detection means for detecting the tracking state of the disk; rotation clock generation means for synchronizing with the rotation of the disk to obtain a plurality of pulse signals per rotation; and a dropout for detecting a dropout of a playback signal from the disk. a detection means; a compensation means for generating a control signal based on the detection signal of the tracking detection means;
comprising a driving means for driving a tracking actuator according to a control signal of the compensating means, the compensating means comprising:
an error detection means for obtaining an error signal in response to a detection signal of the tracking detection means; a memory means for storing a plurality of memory values; and a memory output using at least one memory value stored in the memory means. memory output value creation means for generating a value, and memory values in the memory means are substantially sequentially updated by an update value corresponding to a value obtained by calculating and combining the memory output value of the memory output value creation means and the error signal of the error detection means. and a control signal generating means for calculating and synthesizing the memory output value of the memory output value generating means and the error signal of the error detecting means to generate the control signal. The means and the update storage means operate in synchronization with the pulse signal of the rotation clock generation means, and do not use the detection signal of the tracking detection means when a dropout is detected by the dropout detection means. A tracking control device, characterized in that the control signal is generated by sequentially extracting memory values accumulated and stored in the memory means in synchronization with a pulse signal from the rotation clock generating means.