KR19980083778A - An apparatus and method for automatically adjusting a sled gain in a digital video disc player - Google Patents

Abstract

end. TECHNICAL FIELD [0002]

The present invention relates to a digital video disk player.

I. Technical Problems to be Solved by the Invention:

Since the gain for adjusting the driving voltage is fixed although the conventional driving voltage is different for each product, the minimum driving voltage of each product can not be obtained.

All. Summary of the Invention:

In the present invention, after the off-set of the tracking error signal is detected by vibrating the lens from side to side, the sled gain is adjusted so that the primary adjusted signal value at the moment when the degree of change coincides with the set threshold becomes the moving voltage of the sled motor The present invention has been accomplished.

la. An important use of the invention:

And apparatus and method for automatic adjustment of sled gain in digital video disc players.

Description

An apparatus and method for automatically adjusting a sled gain in a digital video disc player

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video player (DVDP), and more particularly, to a sled gain automatic adjustment apparatus and method for determining a drive voltage level of a sled motor in accordance with an off- .

In general, in DVDP, a focus operation for moving the lens up and down and a tracking operation for moving the lens left and right are performed to on-track the lens.

In the trekking method for on-track the lens, there are a method of moving the pick-up main body by driving the sled motor and a method of adjusting the voltage supplied to the tracking actuator to move the end of the lens horizontally There is a way. At this time, the electrons can not move promptly because they are large in inertia mass, but they can move to a large extent, and the latter is capable of high-speed response.

Therefore, in case of moving many tracks, the micro tracking is performed using the former method after moving using the former method. Also, when the DVDP is played with the lens in on-track, the lens is micro-tracked through the latter method to move to the outer circumferential side along the track of the DVD surface. The pickup body is moved by an electronic method to compensate for the deviation toward the outer periphery of the lens caused by the fine tracking.

In other words, the gain for adjusting the voltage supplied at the time of compensating the bias toward the outer periphery of the lens due to the fine tracking to the minimum voltage (V _smv0 ) for moving the pickup main body was fixed.

However, when the pick-up main body is moved, the pick-up main body moves on a predetermined track by a driving voltage of a predetermined level. At this time, the minimum level of driving voltage required for moving the predetermined track is slightly different for each product.

As described above, in the related art, there is a problem that the signal quality and reliability of the product are deteriorated because the minimum driving voltage for each product is different but the gain for adjusting the voltage is fixed.

It is therefore an object of the present invention to provide an apparatus for automatically adjusting the sled gain such that the off-set of the tracking error signal is the minimum voltage (V _smv0 ) for moving the gain adjusted driving voltage detected at the limit to the pickup body have.

It is another object of the present invention to provide a method of automatically adjusting the sled gain such that the off-set of the tracking error signal is the minimum voltage (V _smv0 ) for moving the gain adjusted driving voltage detected at the limit to the pickup body have.

According to the present invention, after an off-set of a tracking error signal of a reflected light quantity reflected from a digital video disk is detected by vibrating the lens from side to side, a primary adjusted drive voltage at the moment when the degree of the change coincides with the set threshold value, Thereby realizing an apparatus and method for adjusting the sled gain so as to become the moving voltage of the motor.

1 is a block diagram of an automatic sled gain adjusting apparatus according to an embodiment of the present invention;

2 is an operation timing diagram of each part according to an embodiment of the present invention;

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

FIG. 1 is a view showing a structure for tracking a pickup unit main body among a tracking servo with an automatic sled gain adjusting apparatus according to an embodiment of the present invention.

The tracking servo performs a function of horizontally adjusting the lens so that the laser is incident on the correct track of the DVD reflective surface.

1, the pickup unit 10 is constituted by a lens, a laser diode, or the like as a pick-up main body, and a laser beam spot is incident on a DVD reflection surface to read an information signal at a reflected light amount . The amount of reflected light refers to the amount of light reflected from the reflective surface by the position of the laser beam spot incident on the DVD reflective surface. The trekking error detector 12 generates a tracking error (TE) signal from the amount of reflected light provided from the pickup 10. The TE signal is used as a drive voltage for tracking, which moves the entire pickup 10 or makes a lens. The phase compensator 14 compensates the phase of the TE signal to output a driving voltage V _t for tracking. The first low pass filter (LPF1) 16 has a fixed gain, and adjusts V _t applied from the phase compensator 14 according to a fixed gain to output an adjusted driving voltage V _s1 . The waveform of the driving voltage V _s1 is as shown in Fig. 2 (b). The off-set detector 22 detects an off-set which is a residual error of the TE signal applied from the tracking error detector 14 and outputs an off-set signal TE _offset . The waveform of the off-set signal TE _offset is the same as the waveform shown in FIG. The control unit 30 determines the threshold value of the TE _offset and reads V _s1 (V _s10 ) at the time when the TE _offset of the threshold value is detected. Further, when the TE _offset of the threshold value is detected, the sled gain K _e to be adjusted so that the read V _s10 becomes the set minimum voltage V _{smv 0} is determined and output. The control unit 24 may be implemented using a digital signal processor (DSP). The second low pass filter (LPF2) 22 outputs the driving voltage V _s2 for tracking the entire pickup 10 by compensating the applied V _s1 with the sled gain K _e . The sled motor driving unit 24 outputs the voltage V _s for driving the sled motor 26 by the applied V _s2 . The sled motor 26 operates such that the entire pickup 10 moves in a direction and a distance determined by the polarity and the voltage level of V _s when V _s is supplied.

FIG. 2 is a diagram illustrating operation timing pulses of each part according to an embodiment of the present invention.

2 (a) is a waveform diagram showing the TE signal detected at the amount of reflected light provided from the pickup section 22 by vibrating the lens from side to side. The threshold value shown in Figure 2 of a V _max refers to the threshold value set in the controller 24 to determine when to track the entire pickup 10.

2B is a waveform diagram showing V _{s1 in} which a predetermined gain is compensated by phase-correcting the TE signal detected at the amount of reflected light provided from the pickup 22 by oscillating the lens from side to side. The illustrated t position is the point at which the laser beam output from the lens is accurately on-tracked. The laser beam output from the lens falls to the right as it moves from the t position to the right, and the laser beam output from the lens falls to the left as it moves leftward at the t position. Also, V _s10 denotes a driving voltage value read when V _max shown in FIG. 2A is detected.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

When a DVD to be reproduced is inserted, a signal corresponding to the amount of reflected light is output through the pickup unit 10, and a signal corresponding to the output amount of reflected light is applied to the tracking error detecting unit 12.

A signal according to the amount of reflected light is applied to the tracking error detector 12 to output a TE signal which is a tracking error signal having the waveform shown in FIG. 2A. The TE signal is applied to the phase compensator 14 so that the phase is compensated to output V _t .

The V _t signal is applied to the LPF 1 16 and adjusted by the fixed gain to output the signal V _s1 . The output signal V _s1 is a signal having the waveform shown in FIG. 2A. The waveform shown in FIG. 2 (a) is a waveform of the signal V _s1 in which a predetermined gain is corrected after the TE signal is phase-corrected according to the amount of reflected light generated by moving the lens from one side to the other side of the track. If the lens moves a plurality of tracks, the waveform shown in Fig. 2 (a) appears continuously.

The output V _s1 is the signal V _s2 adjusted by the sled gain K _e is applied to LPF2 (18) provided from the controller 24 is outputted. The sled motor driving unit 20 outputs V _s for driving the sled motor 26 by the output V _s2 , and the sled motor 26 is driven by the V _s to drive the pickup unit 10, The whole is tracked. The sled motor driving unit 20 performs control for driving the sled motor 26 when the applied voltage V _s2 is _{equal to} or higher than the minimum voltage V _smv0 .

When explaining the operation for outputting a sled gain K _e of the LPF2 (22) shown below.

The TE signal applied from the tracking error detector 12 is detected as an off-set signal through the off-set detector 22 and the detected off-set signal TE _offset is output. The output TE _offset signal is a signal having the waveform shown in FIG. 2A.

The control unit 24 continuously detects the value of the TE _offset detected through the off-set detector 22 and determines whether the value corresponds to the set threshold value V _max . It detects the applied values of V _s10 V _s1 which is applied when the TE _offset marginal cease determined at the time that the threshold value TE is _offset from the LPF1 (16) is. And determines a sled gain K _e for adjusting the value of the detected V _s10 to the minimum voltage (set value) V _smv0 necessary for driving the sled motor 26. [ That is, the determination of K _e is expressed as follows.

[Equation 1]

The determined K _e is applied to the LPF 2 18 and the _{LPF 2 18} can output the minimum voltage V _smv0 required for driving the sled motor 26 at the set threshold.

That is, at a moment when the TE _offset coincides with the threshold set in the control unit 24, the sled gain is set so that V _s1 output from the LPF 1 20 becomes the moving voltage, and the V _s1 is adjusted to the minimum driving voltage V _{smv 0} will be.

The present invention has an effect of improving the reliability of a product by setting the sled gain according to the minimum driving voltage set in the product.

Claims (2)

An apparatus for automatically adjusting a sled gain in a digital video disc player, A pickup unit for emitting a laser beam to a digital video disk and outputting a signal corresponding to a reflected light amount; A tracking error detector for detecting a tracking error signal from a signal corresponding to the amount of reflected light, A phase compensator for compensating a phase of a tracking error signal applied from the tracking error detector, A first low-pass filter for adjusting the phase-compensated tracking error signal to a fixed gain to output a driving voltage, An off-set detector for detecting an off-set in a tracking error signal applied from the tracking error detector, A controller for determining a sled gain necessary to adjust a signal value output from the first low-pass filter to a minimum voltage at a set threshold value of the detected off-set; A second low-pass filter for adjusting and outputting a signal output from the first low-pass filter to the sled gain, And a sled motor driver for receiving a signal output from the second low-pass filter and controlling driving of the sled motor. A method for automatically adjusting a sled gain in a digital video disc player, A first step of phase-correcting a tracking error signal detected through a reflected light quantity and then adjusting a fixed gain to output a driving voltage; A second step of detecting an off-set of the trekking error signal and detecting the driving voltage at a time point when the detected off-set is determined as a set threshold value; A third step of determining a sled gain required when adjusting the detected driving voltage to a minimum driving voltage for driving the sled motor, And adjusting the driving voltage output from the first step to a minimum driving voltage with the determined sled gain, and outputting the adjusted driving voltage to the minimum driving voltage.