KR19980078999A - Thread Servo Control in DVD System - Google Patents

Abstract

The present invention directly detects the rotational speed of a threaded motor of a threaded servo control system for moving the entire optical system in the radial direction, and based on the detected motor rotational speed information, the DVD system can control the rotational operation of the threaded motor at high speed. The present invention relates to a thread servo control apparatus in which a thread motor rotation speed detecting means for detecting a rotational speed of a threaded motor embedded in a thread servo system is driven; And converting means for converting the detected rotational speed signal provided by the thread motor rotational speed detecting means into a voltage signal within a preset range, wherein the servo control device for controlling the threaded servo system is based on the converted voltage signal. By controlling the drive of the thread servo system, high precision and fast drive control of the thread servo system can be realized.

Description

Thread Servo Control in DVD System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video disc (DVD) system, and more particularly, to threaded servo control in a DVD system suitable for fast and high precision control of a threaded (SLED) motor that moves the entire optical system in the radial direction in the playback mode. Relates to a device.

As is well known, the DVD system, which has recently been drafted (standard published in October 1996) and is commercialized, has a digital recording method and a non-contact playback method. In this respect, it is similar to a CD system. Do.

In addition, the DVD system is a DVD-WO (write-once) such as DVD-Video / audio, DVD-ROM, CD-R, which can be recorded, erased, and rewritten, almost like a conventional CD system. There are kinds of RAM and the like, in which the present invention improves performance on all possible DVD players.

DVDs, on the other hand, have a higher recording capacity than CDs, which means that CDs use infrared light with a wavelength of 780mm while DVDs use red visible light with a wavelength of 635mm. Because it uses. In other words, CD has a track pitch of 1.6 μm and a shortest distance between feet / land is 0.83 μm, whereas a DVD has a track pitch of 0.74 μm and a shortest distance between feet and land of 0.4 μm.

On the other hand, the DVD system has a structure similar to that of the conventional CD system, and keeps the beam waist near the disc recording surface to move the beam spot to the target track, and to follow the beam spot to the track. And a servo system for performing the following, for example, a focusing servo, a tracking servo, a thread servo, a spindle servo, and the like.

In such a servo system, the focusing servo performs the function of moving the optical system in the vertical direction so that the signal surface of the disk is always within the depth of focus of the objective lens, and the tracking servo drives the optical system in the radial direction to accurately track the track. The thread servo performs the function of moving the whole optical system in the radial (or left and right) direction, and the spindle servo performs the function of controlling the rotation of the disk.

Such a servo system includes a plurality of drivers (eg, actuator drivers, spindle motor drivers, threaded motor drivers, etc.) that control the driving of various motors and actuators, respectively, and control from a controller (ie, a controller). The driving of each driver is controlled based on the servo error signal detected by the signal and the RF signal reproduced during the regeneration operation.

On the other hand, in the control of the thread servo which moves the whole optical system in the radial direction in the regeneration mode, the operation of the thread motor driver is conventionally performed based on the control signal from the controller and the servo error signal detected by the reproduced RF signal. By controlling, the thread control is performed. However, in this method, the thread control is performed by referring to the servo error signal extracted from the reproduction signal read out from the disk, and therefore, there is no limit to speed and high precision. For example, this situation is pointed out as a user's complaint because the high speed random access is difficult due to the access delay time during the random access in the playback mode that meets the user's request.

Accordingly, the present invention is to solve the above-mentioned problems of the prior art, a DVD that can directly detect the rotational speed of the thread motor, and can control the rotational driving of the threaded motor at high speed based on the detected motor rotational speed information The purpose is to provide a threaded servo control in the system.

In order to achieve the above object, the present invention has a servo control device for controlling a threaded servo system for moving the entire optical system in a radial direction based on a control signal from a controller that generates various control signals based on a user operation signal. A thread servo control apparatus in a DVD system, comprising: thread motor rotation speed detection means for detecting a rotation speed of a thread motor built in when the thread servo system is driven; And converting means for converting the detected rotational speed signal provided from said thread motor rotational speed detecting means into a voltage signal within a predetermined range, wherein said servo control device is configured to perform said thread servo on the basis of said converted voltage signal. A thread servo control apparatus in a DVD system is provided for controlling the driving of a system.

1 is a block diagram of a typical DVD (DVD) system employing a threaded servo control device according to the present invention;

FIG. 2 is a detailed block diagram of the F / V conversion block shown in FIG. 1;

3 is a pulse waveform diagram of the F / V conversion block shown in FIG.

<Description of the code | symbol about the principal part of drawing>

102: control block 104: memory

106: servo control block 108: driver block

110: deck block 112: DVD disc

114: RF block 116: digital signal processing block

118: sensor block 120: F / V conversion block

202 normalization block 204 counter

206: inverter 208: latch

210: D / A Converter

The above and other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings by those skilled in the art.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, a key technical aspect of the present invention is to control a thread servo, not to control a thread servo for moving the whole optical system in a radial direction with reference to a servo error signal detected from an RF signal reproduced from a disk. By directly detecting the forward and reverse rotational speed of the rotating thread motor according to the driving of the driver, and controlling the thread using the detection result, the thread is controlled at high speed and high precision. For example, the hall sensor detects the rotational speed of the thread motor, and the detected thread motor rotational speed information is provided as one as an information source for controlling the thread servo under control from the controller.

Figure 1 shows a block diagram of a typical DVD (DVD) system employing a threaded servo control device in accordance with the present invention.

As shown in the figure, the DVD system includes a control block 102, a memory 104, a servo control block 106, a driver block 108, a deck block 110, a disk 112, and an RF block 114. ), A digital signal processing block 116, a sensor block 118, and an F / V conversion block 120. In the figure, the portion blocked by the dotted line and denoted by reference numeral A is a portion directly related to the threaded servo control device of the present invention.

Referring to FIG. 1, the control block 102 is a microprocessor that performs overall operation control of a DVD system, and includes various user operation signals (eg, deck open operation signals and reproduction) provided from a keypad not shown. An operation signal, a selection signal for random access, a high speed playback operation signal, etc.) to generate a corresponding system control signal.

For example, in the control block 102, when the user presses a deck open key provided on the front panel or the like to load a DVD disc into the deck of the DVD system, the deck block is controlled by the servo control block 106 and the driver 108. When the disc is inserted into the deck while the deck is opened and the deck is opened, the TOC (Table of Contents) for control in the lead-in area of the disc through the deck driving (playback mode) is driven. And index information (also referred to as sub information or subcode) are read out, stored in a predetermined space of the memory 104, and the DVD system is switched to the pause mode.

Here, the index information of the TOC includes program content information, program directory information, program position information, type information of a disc (DVD), and the like, which includes file content information or file directory information read from the disc. These will be used as information sources required for control of section repeat play, random access, etc. in the play mode.

On the other hand, the servo control block 106 is composed of a plurality of servos, for example, a focusing servo, a tracking servo, a threaded servo, a spindle servo, and the like. The driving of the driver block 108 for operating the deck block 110 is controlled based on the servo error signal provided by the RF block 114 to be described later.

In addition, in controlling the thread servo, the servo control block 106 is detected by the Hall sensor according to the present invention and provided in the form of analog motor rotational speed information provided by the F / V conversion block 120 to be described later (voltage signal ) Is converted into a digital signal and the thread servo is controlled based on the converted motor rotation speed information, that is, the driving of the thread motor (not shown), that is, the rotation speed of the thread motor, and the like are controlled.

Next, the driver 108 is composed of, for example, an actuator driver, a spindle motor driver, a thread motor driver, a tray motor driver, and the like, and according to the control from the servo control block 106 described above, Controls the drive of the motor and actuator.

The deck block 110 is composed of a turntable for mounting a disc, a semiconductor laser, an optical system made of an objective lens and a concave lens, an optical sensor, and the like, which are recorded on the surface of the disc 112 during the disc drive in the reproducing mode. Depending on the presence of the pit, the optical signal is converted into a digital signal, that is, an intermediate frequency (RF) signal is generated through the optical sensor.

Next, the RF block 114 amplifies the digital signal (subcode signal, playback video signal, etc.) output from the optical sensor in the deck block 110 to a level that can be sufficiently processed in the next stage, and forms a waveform. After performing a signal processing process such as, it is provided to the digital signal processing block 116 of the next stage. In addition, the RF block 114 extracts an error signal for servo from the signal output from the deck block 110 and provides it to the aforementioned servo control block 106.

On the other hand, the digital signal processing block 116 is, for example, a digital signal processor (DSP), and according to the control from the control block 102 described above, the digital signal provided from the above-described RF block 114 ( That is, demodulating the control signal information (subcode signal) read from the DVD and actual data information such as a movie into a data string of the original signal, for example, converting a channel-coded EFM signal into an 8-bit data string. Demodulation is performed, and processing such as error correction to remove burst errors or random errors caused by disk damage or dust is performed. Then, the compressed coded data (i.e., reproduction data) output from the digital signal processing block 116 will be provided to an MPEG decoder block, not shown, for restoration to the original signal before encoding.

On the other hand, the sensor block 118 detects the rotational speed of the thread motor for moving the entire optical pickup in the radial (or left and right) direction during the regeneration operation as described above, that is, as shown in FIG. 3B as an example, the thread motor. According to the positive or reverse rotation, a corresponding pulse signal is generated and provided to the next stage F / V conversion block 120. As the motor rotation speed detection sensor, for example, a hall sensor well known in the art Etc. can be used. At this time, the pulse signal generated by the sensor block 118 will be a pulse signal having a relatively long period when the rotational speed of the thread motor is relatively slow, and a pulse signal having a relatively short period when the rotational speed of the thread motor is relatively fast. Will be.

Next, the F / V conversion block 120 level-amplifies and normalizes (normalizes) the detected thread motor rotational speed signal, that is, the pulse signal provided by the sensor block 118, and then clocks it from the outside (CLK). On the basis of the signal), a frequency signal in a pulse train is converted into a voltage signal, and then converted into an analog signal and provided to the aforementioned servo control block 106. A detailed operation of the F / V conversion block 120 will be described in more detail below with reference to FIG. 2.

Accordingly, in the servo control block 106, the thread motor is based on the motor rotational speed information (analog voltage signal) provided by the F / V conversion block 120 described above when the thread servo is controlled to move the whole optical system in the radial direction. By controlling the rotational speed of the optical system, the radial direction of the optical system can be controlled at high speed and high precision.

2 is a detailed block diagram of the F / V conversion block 120 and includes a normalization block 202, a counter 204, an inverter 206, a latch 208, and a D / A converter 210. .

Referring to FIG. 2, in the normalization block 202, the detected motor rotational speed signal provided by the sensor block 118 of FIG. 1, i.e., as a pulse signal as shown in FIG. Amplify and binarize to a level suitable for processing and then provide to the LD terminal of the counter 204 and to the input of the inverter 206. At this time, the output signal of the inverter 206 which inverts the binarized detection pulse signal is provided as a clock signal of a latch which will be described later.

Next, the counter 204 counts the pulse signal input through its LD terminal based on the clock signal CLK from the outside, for example, a clock signal as shown in FIG. Q ₀ -Qm) to generate an m-bit digital signal, e.g., to generate an m-bit digital signal through the count of the number of clocks present in the detected high-level range of the pulse signal. To provide. At this time, as an example, assuming that the output value of the counter 204 is defined as 8 bits, the voltage value may be expressed at 256 levels from "00000000" to "11111111".

On the other hand, in the latch 208, as shown in FIG. 3C as an example, the m-bit output signal (voltage signal) of the counter 204 at the falling edge of the signal provided from the inverter 206 to its clock terminal CLK. The latched m-bit voltage signal is output from the inverter 206 to the next stage D / A converter 210 at the rising edge of the signal provided to the clock terminal CLK.

Next, the D / A converter 210 may be configured as, for example, a current addition type D / A converter having an input terminal corresponding to the number of output bits in the latch 208. M-bit digital voltage signal is converted into an analog signal and then provided to the servo control block 106 of FIG.

Therefore, in the servo control block 106 of FIG. 1, when the thread servo for moving the whole optical system in the radial direction is controlled, the motor rotational speed information (analog voltage signal) provided by the D / A converter 210 is digitally signaled. By controlling the rotational speed of the threaded motor based on the converted detection signal (motor rotational speed signal), the radial direction movement of the optical system will be controlled at high speed with high precision.

As described above, according to the present invention, the high precision of the thread servo is controlled by directly controlling the drive of the thread motor based on the rotation speed detection signal of the thread motor at the time of controlling the thread servo which performs the function of moving the whole optical system in the radial direction. Fast drive control can improve the performance of the entire servo system.

Claims (6)

In the thread servo control device in a DVD system having a servo control device for controlling the thread servo system for moving the entire optical system in the radial direction based on a control signal from a controller that generates various control signals based on a user operation signal. , Thread motor rotation speed detection means for detecting the rotation speed of a thread motor built in when the thread servo system is driven; And Converting means for converting the detected rotational speed signal provided by said thread motor rotational speed detecting means into a voltage signal within a predetermined range, The servo control device is a thread servo control device in a DVD system, characterized in that for controlling the drive of the thread servo system based on the converted voltage signal. The thread servo control apparatus of a DVD system according to claim 1, wherein said thread motor rotational speed detecting means comprises a hall sensor for generating a pulse signal corresponding to the detected rotational speed. The apparatus of claim 1 or 2, wherein the converted voltage signal is an analog signal, and the servo controller further comprises A / D conversion means for converting the converted analog voltage signal into a digital signal. Thread servo control in DVD system. The method of claim 2 wherein the conversion means is: A normalization block for amplifying the detected pulse signal to a predetermined predetermined level and binarizing the amplified pulse signal; A counter for generating an m-bit digital signal corresponding to the detected pulse signal by counting the number of clocks present in a high level section of the detected pulse signal by inputting a clock signal from an external device; A latch for latching the m-bit digital output from the counter based on the clock signal inverting the pulse signal output from the normalization block and providing the latched m-bit digital voltage signal to the output; And And a D / A converter for converting an m-bit digital voltage signal output from the latch to an analog voltage signal and providing the same to the servo control device. The thread servo control apparatus according to claim 4, wherein the counter is an 8-bit counter. The D / A converter according to claim 4, wherein the latch latches an m-bit voltage signal of the counter at a falling edge of the inverted clock signal, and converts an m-bit voltage signal latched at a rising edge of the inverted clock signal to the D / A converter. Thread servo control device in the DVD system, characterized in that the output.