JP2003168224A - Disk drive unit and servo control signal generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize phase delay caused by signal processing to a specific input signal, while reducing the cost. <P>SOLUTION: The drive is constituted so that the sampling order of a focus error signal FE and a tracking error signal TE at an input changeover switch 41 is set by means of changing over input switches 41A, 41B... of the input changeover switch 41 by using a changeover timing control circuit 46 in an order based on data being set in a setting register 46a. The minimization of the phase difference between the focus error signal FE or the tracking error signal TE selectable by the input changeover switch 41 and a focus drive signal or a tracking drive signal obtained from these servo error signals is attained. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive device for performing recording or reproduction on a disk-shaped recording medium, and a servo control signal generating device provided in such a disk drive device.

[0002]

2. Description of the Related Art CD (C
ompact Disc), MD (Mini Disk), CD-ROM (Co
mpact Disc-Read Only Memory), MO (Magnet Optica
l) etc. are widely spread and used in various fields including music applications.

In a disk drive device for recording or reproducing on such an optical disk-shaped recording medium (hereinafter, simply referred to as "disk"), a laser beam emitted from a laser light source provided in an optical head is used. It is provided on the optical head so that the spot controls the tracking servo control to properly trace the track formed on the signal surface of the disc, and the laser beam is properly focused on the signal surface of the disc. Focus servo control is performed to drive and control the existing objective lens in the direction of approaching and separating from the disc signal surface.

For this reason, the disk drive device is based on the tracking error signal TE generated from the reflected laser light reflected on the signal surface of the disk, the focus error signal FE, and the pull-in signal PI which is a so-called sum signal. A servo control signal generation device for generating various servo control signals such as a tracking drive signal and a focus drive signal is provided.

FIG. 7 is a block diagram showing the configuration of a conventional servo control signal generator. As shown in FIG. 7, in the conventional servo control signal generating device, input signals such as a tracking error signal TE, a focus error signal FE, and a pull-in signal PI are supplied from an A / D converter 101, which are not shown. 102, 103
It is input to ... A / D converters 101, 10
Reference numerals 2, 103, ... Convert digital input data into digital input data based on a clock signal input from the clock circuit 111 at a constant cycle, and digital signal processors (DSPs).
ssor) 110. The DSP 110 performs a required servo process on the digital data input from the A / D converters 101, 102, 103, ... To obtain various servo control signals.

[0006]

By the way, in the conventional servo control signal generating device as described above, sampling of the input signal is performed by the A / D converters 101, 102, 103.
... is done collectively. In this case, the sampling timing is the clock circuit 11
It is predetermined based on the clock signal from 0. On the other hand, various servo processes performed in the DSP 110 are performed in time series,
There is a delay time from the sampling in the A / D converters 101, 102, 103, ... Until the servo processing in the DSP 110. This delay time causes a delay in servo processing in the DSP 110, for example, filtering processing, which causes a phase delay in various servo control signals.

In particular, regarding the servo processing for obtaining the tracking control signal and the focus control signal which require a long time for the servo processing in the DSP 110 and have severe phase characteristics, the delay time from the sampling to the servo processing is performed. However, the filter performance of the DSP 110 cannot be fully utilized.

Therefore, in order to solve the above problems, 1
As one means, it is conceivable to perform servo processing for obtaining a servo control signal with severe phase characteristics as interrupt processing at the timing of sampling the input signal, but there are multiple such servo processings. In that case, the delay time of all servo processing cannot be eliminated.

Therefore, in constructing the conventional servo control signal generator, the DSP 110 having a high processing speed is used.
Although the servo processing time is shortened by using, the DSP 110, which has a high processing speed, is very expensive and therefore costly. Further, since the input signals are sampled collectively, the A / D for each input signal
It is necessary to provide the converters 101, 102, 103, ... From this point as well, there is a drawback that the cost is high in configuring the hardware.

Further, in the servo control signal generator, D
Although the servo control processing executed in SP110 is executed based on the servo processing program, as described above, the sampling of the input signal is performed by the A / D converters 101, 102, 103 ... Which are hardware. If so, it is necessary to create a servo processing program in synchronization with this sampling timing. That is, when creating the servo processing program, there is a drawback that the sampling timing is restricted.

[0011]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of such a point, and minimizes the phase delay of the servo control signal obtained from the specific servo error signal while reducing the cost. It is an object of the present invention to provide a disk drive device and a servo control signal generation device that can perform the above.

To achieve the above object, a disk drive device capable of reading or writing data from or to the disk-shaped recording medium of the present invention is based on an optical pickup and a detection signal detected by the optical pickup. Servo error signal generating means for generating a plurality of servo error signals used for servo control, and an input selecting means for inputting the plurality of servo error signals as input signals and selecting any one of the input signals When,
A / D conversion means for converting an input signal input from the input selection means into input data, data holding means for holding the input data converted by the A / D conversion means, input selection means and data holding means, respectively. And a data processing means for performing required servo processing in time series using input data held in the data holding means and obtaining a required servo control signal according to the input data. And a switching setting for switching the switching control means in the order based on the order data having the smallest phase difference between the specific input signal selectable by the input selection means and the servo control signal obtained from the specific input signal. And means.

Further, the servo control signal generating device of the present invention is provided with an input selecting means capable of inputting a plurality of input signals and selecting any one of the plurality of input signals, and an input selecting means. A / D conversion means for converting an input signal input via the input data, data holding means for holding the input data converted by the A / D conversion means, and switching between the input selection means and the data holding means. Switching control means for controlling, and data processing means for performing required servo processing in time series using the input data held in the data holding means and obtaining a required servo control signal according to the input data, The switching control means is based on the sequence data having the smallest phase difference between the specific input signal selectable by the input selection means and the servo control signal obtained from the specific input signal. To switch in order and a switch setting means.

According to the present invention, the switching control means performs switching in the order based on the sequence data set in the switching setting means, whereby a specific input signal selectable by the input selecting means and this specific input signal are selected. It is possible to minimize the phase difference from the servo control signal obtained from the input signal.

[0015]

DETAILED DESCRIPTION OF THE INVENTION A disk drive device as an embodiment of the present invention will be described below. FIG. 1 is a block diagram of a main part of a disk drive device according to this embodiment. The disc 90 is loaded on the turntable 7,
During the reproducing operation, the spindle motor 6 is rotationally driven at a constant linear velocity (CLV) or a constant angular velocity (CAV). Then, the optical pickup 1 reads the data recorded in the pit form on the disc 90.

Laser light from a laser diode 4 provided in the optical pickup 1 is output from an objective lens 2 to a recording surface of a disc 90 via an optical system (not shown). The objective lens 2 is held by a biaxial mechanism 3 so as to be movable in the tracking direction and the focus direction. By the operation of the biaxial mechanism 3, tracking and focus control of laser light are performed.

The reflected light information of the laser light from the disk 90 is detected by the detector 5 from the objective lens 2 through an optical system (not shown), and is supplied to the RF amplifier 9 as an electric signal corresponding to the amount of received light.

The RF amplifier 9 includes a current-voltage conversion circuit, an amplification circuit, a matrix operation circuit, etc., and generates a necessary signal based on the signal from the detector 5. For example, an RF signal that is reproduction data, a focus error signal FE for servo control, a tracking error signal TE, a pull-in signal PI that is a so-called sum signal, and the like are generated. Also,
The RF amplifier 9 also generates a focus bottom signal FB, a focus peak signal FP, and the like.

The various signals generated by the RF amplifier 9 are 2
It is supplied to the digitizing circuit 12 and the servo processor 14. That is, the reproduction RF signal from the RF amplifier 9 is converted into a binary circuit
To focus error signal FE, tracking error signal TE, pull-in signal PI, focus bottom signal F
B, the focus peak signal FP is the servo processor 14
Is supplied to.

The reproduced RF signal obtained by the RF amplifier 9 is
By being binarized by the binarization circuit 12, for example, an EFM signal (8-14 modulated signal; when the disc 90 is a CD type disc) or an EFM + signal (8-16 modulated signal; the disc 90 is a DVD type disc). If it is a disc)
And is supplied to the decoder 13. The decoder 13 performs EFM demodulation, CIRC decoding, etc., and also performs CD-ROM decoding, MPEG decoding, etc. as necessary to reproduce the information read from the disc 90.

The servo processor 14 uses the focus error signal FE and the tracking error signal TE from the RF amplifier 9 and the spindle error signal SPE from the decoder 13 or the system controller 30 to drive various servo drives for focus, tracking, sled, and spindle. Generate a signal to execute servo operation.

That is, according to the focus error signal FE and the tracking error signal TE, a focus drive signal,
Generates a tracking drive signal, and the biaxial driver 18
Supply to. The biaxial driver 18 drives the biaxial mechanism 3 in the optical pickup 1. As a result, the optical pickup 1, the RF amplifier 9, the servo processor 14, and the biaxial driver 18 form a tracking servo loop and a focus servo loop.

The servo processor 14 also sends a spindle error signal S to the spindle motor driver 19.
The spindle drive signal generated based on PE is supplied. The spindle motor driver 19 applies, for example, a three-phase drive signal to the spindle motor 6 according to the spindle drive signal, and causes the spindle motor 6 to perform CAV rotation or CLV rotation. In the case of CAV, the spindle error signal SPE can be obtained by comparing the FG pulse (frequency signal synchronized with the rotation speed) detected from the spindle motor 6 with the reference speed information,
On the other hand, in the case of CLV, the spindle error signal SPE
Can be obtained by comparing the reproduction clock generated by the decoder 13 with the reference speed information.

The servo processor 14 also generates a spindle drive signal in response to a spindle kick / brake control signal from the system controller 30 and causes the spindle motor driver 19 to execute operations such as starting or stopping the spindle motor 6. Incidentally, the rotation speed of the spindle motor may be a high speed rotation such as 2 × speed, 4 × speed or 8 × speed when the normal speed is 1 × speed. Such speed setting is realized by the system controller 30 variably setting reference speed information to be compared with the spindle error signal SPE.

The servo processor 14 generates a thread drive signal based on, for example, a thread error signal obtained from the tracking error signal TE and the access execution control from the system controller 30 and supplies it to the thread driver 17. The sled driver 17 drives the sled mechanism 8 according to the sled drive signal. Although not shown, the sled mechanism 8 includes a main shaft that holds the optical pickup 1, a sled motor,
A transmission gear, a sled motor, and the like are provided, and the sled driver 17 drives the sled motor in response to the sled drive signal, so that the optical pickup 1 is appropriately slid.

The laser diode 4 in the optical pickup 1 is driven to emit laser light by a laser driver 20. The servo processor 14 is the system controller 3
Based on an instruction from 0, a laser drive signal for performing laser emission of the optical pickup 1 at the time of reproduction is generated and supplied to the laser driver 20.

The servo processor 14 is also supplied with detection information from the tilt sensor 10. The tilt sensor 10 outputs detection information detected according to the tilt amount (tilt amount) of the disc 90 and the optical pickup 1 in the radial direction to the servo processor 14 as a so-called tilt error signal TLT. In this case, the servo processor 14 supplies a tilt drive signal corresponding to the tilt error signal TLT to the tilt driver 15 to cause the tilt motor 1 to operate.
6 is driven. In this example, the tilt motor 16 is
It is a so-called stepping motor, and thus the servo processor 14 generates a tilt drive signal as a stepping drive.

A midpoint sensor 11 is provided in the optical pickup 1. Although illustration of the structure of the midpoint sensor 11 is omitted, for example, a thin plate attached so as to interlock with the movement of the objective lens 2 in the tracking direction and a neutral plate provided at the neutral position of the objective lens 2 are provided. A light-emitting diode element that emits light to a plate, a photodetector that receives light of the light-emitting diode element that is divided with the thin plate as a boundary, and a light amount difference of divided light that is detected by the photodetector. It is configured by including a differential amplifier for detecting the. Then, the objective lens 2 is detected by the midpoint sensor 11 as detection information.
The midpoint error signal CE indicating the amount of displacement from the neutral position,
The midpoint error auxiliary signal CS which is the auxiliary signal is output to the system controller 30 and the servo processor 14,
Used for servo processing performed by the servo processor.

Various operations such as servo and decoding as described above are controlled by a system controller 30 formed by a microcomputer. For example, operations such as playback start, end, track access (seek),
It is realized by the system controller 30 controlling the operations of the servo processor 14 and the optical pickup 1.

The servo processor 14 provided in the above disk drive device will be described below. FIG. 2 is a diagram showing a configuration of main blocks of the servo processor 14. As shown in FIG. 2, the servo processor 14 includes an input changeover switch 41, an A / D converter 42, a sample data holding memory 43, a digital signal processor (DSP) 44, and a timer circuit 4.
5, switching timing controller circuit 46, delay circuit (del
ay) 47.

The input changeover switch 41 has at least as many input switches 41A, 41B, 41C ... 41 as the number of channels of the servo error signal used when various servo drive signals are generated in the servo processor 14.
L is provided. Input switches 41A, 41B, 4
Each input side of 1C ... Is connected to each input terminal. Further, each output side thereof is connected to the A / D converter 42. That is, the input switches 41A, 41B, 41C
The focus error signal F is input to ...
E, tracking error signal TE, midpoint error signal C
Various servo error signals such as E and the midpoint error auxiliary signal CS are input respectively.

The A / D converter 42 has an input switch 4
The analog input signals input from 1A, 41B, 41C, ... Are converted into digital input data and output.
The input data digitally converted by the A / D converter 42 is transmitted to the sample data holding memory 43 via the data bus line, and the sample hold memories 43A and 43 provided in the sample data holding memory 43.
B, 43C ... 43L, respectively.

A program memory area is provided inside the DSP 44. A servo processing program is stored in advance in this program memory area, and based on the servo processing program, the input data held in the sample data holding memory 43 is fetched and the required servo processing is executed. The DSP 44 performs a processing operation in synchronization with a timer output output from the timer circuit 45 at a predetermined cycle (sampling cycle).

The switching timing control circuit 46 inputs the input switches 41A, 41 of the input switching switch 41 based on the data of the setting register 46a provided therein.
B, 41C, ... And sample hold memories 43A, 43B, 43C of the sample data holding memory 43.
Switching control is performed. The data of the setting register 46a can be changed by the servo processing program of the DSP 44. The switching timing control circuit 46 also performs the switching operation in synchronization with the timer output from the timer circuit 45.

The delay circuit 47 delays the switching control signal output from the switching timing control circuit 46 to the sample data holding memory 43 by the time required for the A / D conversion of the A / D converter 42.

Therefore, the switching control signal is input to the sample data holding memory 43 at a timing later than the switching control signal input to the input changeover switch 41 by the time required for the A / D conversion of the A / D converter 42. At this timing, any of the sample hold memories 43A, 43B, 43C, ...
The sample data sampled by 1 will be retained. Sample hold memory 43A, 43
The sample data held in B, 43C, ... Are taken into the DSP 44 at a predetermined timing and used for various servo processes.

In the servo processor 14 of the present embodiment as described above, when executing the focus servo processing and the tracking servo processing, the delay time from the sampling by the input switches 41A and 41B to the end of the servo processing. It is configured to be minimum. That is, the input signal is sampled by the input selector switch 41 at the timing immediately before the focus and tracking servo control is performed in the DSP 44, and the sampled data is held in the sampled data holding memory 43.

Therefore, in this embodiment, the setting timing register 46a is provided in the switching timing control circuit 46 of the servo processor 14, and the switching of the input changeover switch 41 is controlled based on the data of this setting register 46a. For example, 16 addresses (ADSW0 to ADSWF) are prepared in the setting register 46a as shown in FIG. Each address is configured so that any of the input switches 41A, 41B, ... Can be assigned.

Therefore, the switching timing control circuit 46 is
During one cycle (sampling cycle) of the timer output from the timer circuit 45, sampling is performed by turning on the input switches 41A, 41B ... In the order of data of addresses ADSW0 → ADSW1 → ADSW2 → ADSW3 ... Of the setting register 46a. Switching control will be performed as described above.

Therefore, in the servo processor 14 of the present embodiment, at the time of executing the servo processing for obtaining the tracking drive signal and the focus drive signal having strict phase characteristics, at the same time as these servo processing timings, The setting register 4 is set so that the input changeover switch 41 samples the input signal.
Input switch 41 to each address (ADSW0 to ADSWF) of 6a
By setting the data of A, 41B, ..., Sampling is performed immediately before the tracking and focus servo processing is executed.

Here, FIG. 4 shows an example of setting of the setting register 46a. In FIG. 4, the servo processor 14 has 12 channels. In the setting register 46a shown in FIG. 4,
Of the bit string following the addresses ADSW0 to ADSWF, the lower 12 bits are assigned to the input changeover switch 41. In this case, data indicating the input switch 41B to which the tracking error signal TE is input is written in the address ADSW0. Data indicating the input switch 41A to which the focus error signal FE is input is written in the address ADSW1. In the following address order, the midpoint error signal CE, the midpoint error auxiliary signal CS, the pull-in signal PI, the tilt error signal TLT, and the analog reference signal V
C, focus bottom signal FB, input switch data to which focus peak signal FP is input, and data indicating input switches connected to auxiliary input terminals AUX1, AUX2, and AUX3 are written.

The operation timing of the servo processor 14 when the setting register 46a is set as described above is shown in FIG.
As shown. In FIG. 5, the input signal (focus error signal FE) of the input switch 41A shown in FIG. 2 is A, the input signal of the input switch 41B (tracking error signal TE) is B, and so on. , 41D ... The input signals are C,
D ...

First, in the DSP 44, based on the servo processing program, as shown in FIG. 5C, in the order of [processing for signal B] → [processing for signal A] → [other signal processing]. If the signal processing is performed in time series, at least for the input signals A and B, the switching order of the input switches should be set so that the input signals are sampled immediately before the processing is started. In this case, the DSP 44 can obtain a sufficient filtering characteristic.

Therefore, in the servo processor 14 of the present embodiment, the sequence B → C → D → shown in FIG. 5A is synchronized with the timer output shown in FIG. 5D.
The data of the setting register 46a is set so that the input signal is sampled in the order of A → E → F → ... Then, if the switching control of the input changeover switch 41 is performed with the sequence data as shown in FIG. 5A, at least the input signals A and B are as shown in FIG. In the DSP 44, sampling can be performed immediately before the servo processing using the input signals A and B is performed, and the A / D converted input data A and B can be held in the sample data holding memory 43. As a result, the input delay of the input signals A and B can be minimized and the input delay of the input signal used for the focus servo control can be shortened.

Therefore, in this way, the servo processor 14
With this configuration, the input delay of the input signal in the tracking servo control and the focus servo control can be minimized without using a DSP having a high processing speed, so that the cost of the DSP 44 can be reduced.
Further, in this case, since it can be realized by one A / D converter 42 without providing an A / D converter for each input signal, cost reduction can be achieved also from this point.

Further, the sampling timing of the input signal by the input changeover switch 41 can be easily changed only by changing the servo processing program of the DSP 44. Therefore, when designing and developing the servo processing program, the sampling timing There is no restriction, and the degree of freedom in developing the servo control device can be expanded accordingly. For example, even when the specifications of the DSP 44 and various servo mechanisms (actuators) are changed, the servo processing program need not be changed significantly as in the conventional case.
Only readjustment is required so that the sampling timing of the input signal is optimum.

Here, as a comparison with the operation timing of the present example shown in FIG. 5, the operation timing when the setting of the setting register 46a is not optimum is shown in FIG. If the setting of the setting register 46a is not optimum, the DSP 44
In FIG. 6, as shown in FIG. 6C, the signal processing is performed in time series in the order of [processing for signal B] → [processing for signal A] → [other signal processing]. On the other hand, in the switching timing control circuit 46, the order A → B → C → D → E → F → ...
Setting register 46 to sample the input signal
Since a is set, an input delay occurs in the input signals A and B. In this case, the filter processing in the DSP 44 is very disadvantageous. For example, assuming that the sampling frequency is 100 KHz, if one sample processing is delayed like the input signal B, the input delay alone causes a phase delay of 18 degrees with respect to the input signal of 5 KHz.

In this embodiment, the reproducing device is taken as an example of the disc drive device, but the present invention can be applied to a disc drive device corresponding to a recordable recording medium. .

[0049]

As described above, according to the present invention,
A specific input signal selectable by the input selection unit and a servo control signal obtained from this specific input signal when the switching control unit performs switching in the order based on the order data set in the switching setting unit. It becomes possible to minimize the phase difference with. With this configuration, it is possible to easily change the switching order of the switching control means only by changing the order data of the switching setting means. Therefore, it is possible to limit the sampling timing when designing and developing the servo processing program. Therefore, the degree of freedom in development in servo control processing can be expanded accordingly.

Further, according to the present invention, A
Since it can be configured by one A / D converter without providing the / D converter, the hardware cost can be reduced. Further, since it can be realized without using a digital signal processor having a high processing speed, cost reduction and current consumption reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a disk drive device as an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of main blocks of a servo processor.

FIG. 3 is an explanatory diagram of an input changeover switch setting register 46a according to the present embodiment.

FIG. 4 is a diagram showing a setting example of an input switch according to the present embodiment.

FIG. 5 is an operation timing chart of the servo processor in the present embodiment.

6 is an operation timing chart of the servo processor when the setting of a setting register 46a is not optimum, as a comparison with the operation timing chart shown in FIG.

FIG. 7 is a diagram showing a configuration of main blocks of a conventional servo control signal generation device.

[Explanation of symbols]

1 optical pickup, 2 objective lens, 3 biaxial mechanism, 4 laser diode, 5 detector, 6 spindle motor, 7 turntable, 8 thread mechanism, 9 RF amplifier, 10 tilt sensor, 11 midpoint sensor, 12 binarization circuit , 13 decoder, 14 servo processor, 15 tilt driver, 16 tilt motor, 17 thread driver, 18 biaxial driver, 19 spindle motor driver, 20 laser driver, 30 system controller, 41 input selector switch, 42 A / D converter, 43 Sample data holding memory, 44 digital signal processor (DSP), 45 timer circuit, 46 switching timing control circuit, 46a setting register, 47 delay circuit,
90 discs

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuyuki Hayashi             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F-term (reference) 5D118 AA04 AA08 AA13 BA01 BF02                       BF03 CA07 CA11 CA13 CB03                       CD02 CD03

Claims (4)

[Claims] 1. A disk drive device capable of reading or writing data from or to a disk-shaped recording medium, comprising: an optical pickup; and a plurality of servo controls used for servo control based on a detection signal detected by the optical pickup. Servo error signal generating means for generating a servo error signal, input selecting means for inputting the plurality of servo error signals as input signals and selecting any one of the input signals, and the input selecting means A / D conversion means for converting an input signal input from the device into input data, data holding means for holding the input data converted by the A / D conversion means, the input selection means and the data holding means, respectively. Switching control means for performing switching control of the input data and input data held in the data holding means. , Data processing means for performing required servo processing in time series to obtain a required servo control signal according to the input data, the switching control means, a specific input signal selectable by the input selection means, A disk drive device comprising: a switching setting unit that switches in an order based on order data having a smallest phase difference from a servo control signal obtained from the specific input signal. 2. An input selection means capable of inputting a plurality of input signals, capable of selecting any one of the plurality of input signals, and an input signal input through the input selection means. A / D conversion means for converting the input data, data holding means for holding the input data converted by the A / D conversion means, and switching control for controlling switching between the input selecting means and the data holding means Means, data processing means for performing required servo processing in time series using the input data held in the data holding means, and obtaining a required servo control signal according to the input data, and the switching control. The means is based on the sequence data having the smallest phase difference between the specific input signal selectable by the input selecting means and the servo control signal obtained from the specific input signal. Servo control signal generation apparatus characterized by comprising a switching setting means to switch the order was. 3. The servo control signal generation device according to claim 2, wherein the specific input signals are a focus error signal and a tracking error signal. 4. The servo control signal generation device according to claim 2, wherein the A / D conversion means is composed of one A / D converter.