KR20010025992A - Method for detecting actuator direction of optical record/player - Google Patents

Abstract

PURPOSE: A method for detecting an actuator direction of an optical recording player is provided to decide that the actuator direction is switched, when a pulse width difference between a previous TZC(Track Zero Cross) signal and a present TZC signal is over n times, and to exclude a TZC signal detected in a header area from the actuator direction detecting. Therefore, the actuator direction is exactly detected. CONSTITUTION: A TZC(Track Zero Cross) time detector(201) detects a pulse width of a TZC signal. A TZC time comparator(202) compares the detected pulse width with a pulse width of a previous TZC signal. A header remover(203) removes a header influence including a glitch from an output signal of the TZC time comparator(202). The first charger/discharger(205) charges or discharges the TZC signal. The second charger/discharger(206) reverses the TZC signal and charges/discharges the reversed TZC signal. An adder(207) adds output signals of the first and the second charger/discharger(205,206). An LPF(Low Pass Filter)(208) low-filters an output signal of the adder(207), and averages the filtered signal. A comparator(209) slices an output signal of the LPF(208) with a preset reference voltage. An actuator direction generator(204) decides whether an actuator direction is switched, by using an output signal of the header remover(203), an initial actuator direction, and an output signal of the comparator(209). The actuator direction generator(204) outputs an actuator direction signal according to a decided result.

Description

Method for detecting actuator direction of optical record / player

The present invention relates to an optical recorder, and more particularly, to a method for detecting an actuator direction in a land / groove recording method.

In general, an optical recording medium system, that is, an optical recording / reproducing apparatus uses an optical disk such as a compact disc (CD), a digital versatile disc (DVD), or the like as a recording medium to reproduce data recorded on the disk or to record data on the disk. Device.

At this time, a rewritable optical disc, particularly a DVD-RAM, has a signal track having a structure of lands and grooves, and records information signals on tracks of lands and grooves, respectively, in order to increase the recording density.

Fig. 1 is a general block diagram of such a rewritable optical disc recorder. The optical disc 101 has a signal track structure of lands and grooves, and not only the tracks of the lands or grooves, but also the tracks of the lands and grooves. Can be recorded or played back.

At this time, the optical pickup 102 causes the light beam focused on the objective lens to be placed on the signal track of the optical disk 101 under the control of the servo control unit 106, and also condenses the light reflected by the signal recording surface back to the objective lens. It then enters a photo detector (not shown) for detection of the focus error signal and tracking error signal.

The photo detector includes a plurality of photo detectors, and an electrical signal proportional to the amount of light obtained from each photo detector is output to the RF and servo error generator 104. The RF and servo error generator 104 detects an RF signal for data reproduction, a focus error signal FE for servo control, a tracking error signal TE, and the like from the electrical signal output from the photo detector. At this time, the RF signal is output to the decoder 105 for reproduction, servo error signals such as FE and TE are output to the servo controller 106, and a control signal for data recording is output to the encoder 103.

The encoder 103 encodes data to be recorded into recording pulses in a format required by the optical disk 101, and then records the data on the optical disk 101 through the optical pickup 102, and the decoder 105 transmits the RF. Restore the original form of data from the signal.

Meanwhile, a host such as a PC may be connected to the optical disc recording and reproducing apparatus, and the host transmits a recording / reproducing command to the microcomputer 111 through the interface 110 of the optical recording / reproducing apparatus, and the encoder Data to be recorded is transmitted to the 103, and the reproduced data is received from the decoder 105. The microcomputer 111 controls the encoder 103, the decoder 105, and the servo controller 106 according to a recording / reproducing command of the host.

In this case, the interface 110 generally uses an advanced technology attached packet interface (ATAPI). In other words, ATAPI is an interface standard between an optical recording / playback device such as a CD or DVD drive and a host, and it is a standard proposed to transmit data decoded by an optical recording / playback device to a host. It converts the protocol into an in-packet form and transmits it.

The servo controller 106 processes the focus error signal FE to output a driving signal for focusing control to the focus servo driver 107, and processes the tracking error signal TE to signal the tracking control. The driving signal is output to the tracking servo driver 108. Here, the servo controller 106 generates a track zero crossing (TZC) signal that is turned on / off at the zero crossing time point of the tracking error signal TE. The TZC signal may be used as various reference signals. For example, the TZC signal may be used as a reference signal for determining a kick pulse, a brake pulse, and a brake on time.

The focus servo driver 107 moves the optical pickup 102 up and down by driving the focus actuator in the optical pickup 102 so that the optical disc 101 follows the vertical movement along with the rotation.

In addition, the tracking servo driver 108 drives the tracking actuator in the optical pickup 102 to move the objective lens of the optical pickup 102 in the radial direction to correct the position of the beam and follow a predetermined track. do.

In this case, the tracking actuator is moving in a track travel direction (eg, normal servo) or a track jump direction (eg, seek), and in some cases, the direction of the tracking actuator needs to be known.

For example, in the case of a seek, the tracking actuator accelerates with a kick pulse and then drops when the brake signal is generated. At this time, since the tracking actuator is vibrating, a stable seek is performed only by rapidly suppressing the vibration of the actuator by applying a brake in a direction opposite to the vibration direction. To this end, it is necessary to know the vibration direction of the actuator.

That is, if the vibration direction of the actuator is known, an auto break operation may be performed to automatically suppress the vibration of the actuator by applying the brake in a direction opposite to the vibration direction.

At this time, in the CD or DVD pit format or groove recording method, a mirror signal is generated from the RF signal to detect the direction of the actuator, and the actuator vibration is automatically prevented by using the mirror signal.

However, in the land / groove recording method, since data is recorded in both the land and the groove, the mirror signal cannot be formed from the RF signal. That is, since the tracking error occurs in the same manner as the groove recording method or the land / groove recording method without forming the mirror signal, there is a problem that the direction of the tracking actuator cannot be detected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an actuator direction detecting method of an optical recorder for detecting the direction of a tracking actuator in a land / groove recording type optical disk.

Another object of the present invention is to provide an actuator direction detecting method of an optical recorder which detects the direction of an actuator by comparing a pulse width of a currently detected TZC signal with a pulse width of a previous TZC signal.

It is still another object of the present invention to provide an actuator direction detecting method of an optical recorder which detects the direction of an actuator using the sliced value after slicing the averaged value by charging and discharging the TZC signal.

1 is a block diagram of a general optical recorder

2 is a block diagram illustrating a method for detecting an actuator direction of an optical recorder according to the present invention.

(A) to (f) is an operation timing diagram of each part of FIG.

4 (a) to 4 (f) are operation timing diagrams of respective units in the case where the setting of n in FIG. 3 is ambiguous.

Explanation of symbols for main parts of the drawings

201: TZC time detector 202: TZC time comparator

203: header removing unit 204: actuator direction generating unit

205,206 Charge / discharge unit 207 Adder

208: low pass filter 209: comparator

The actuator direction detection method of the optical recorder according to the present invention for achieving the above object comprises the steps of detecting the pulse width of the TZC signal, the pulse width of the TZC signal detected in the step and the pulse width of the previous TZC signal Comparing the magnitude of the signal with the pulse width of the TZC signal and the pulse width of the previous TZC signal, wherein the direction of the tracking actuator is changed and outputting the actuator direction signal accordingly. Characterized in that comprises a step.

In the time comparison step, the pulse width of the TZC signal detected in the header area is excluded from the comparison.

The generating of the actuator direction may include switching the actuator direction signal whenever it is determined that the initial direction of the actuator signal is received as a reference value and the direction of the actuator is changed.

The generating of the actuator direction may include charging and discharging the TZC signal and averaging the result, slicing the result to a predetermined reference voltage, and then, if the falling edge of the sliced signal is not detected until the number of times is n times, the actuator may be n times. And switching the direction of the actuator at the falling edge when the falling edge is detected.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

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

FIG. 2 is a block diagram for detecting an actuator direction of an optical recorder according to the present invention, in which a TZC time detector 201 and a pulse width detected by the TZC time detector 201 detect a pulse width of a TZC signal. Charge-discharge the TZC time comparator 202 for comparing the pulse widths detected from the TZC signal, the header remover 203 for removing the header effect including glitches from the output of the TZC time comparator 202, and the TZC signal. An adder 207 and an adder 207 which adds outputs of the first charging and discharging unit 205, the second charging and discharging unit 206 to invert and charge and discharge the TZC signal, and the first and second charging and discharging units 205 and 206. A low pass filter (LPF) 208 for low-pass filtering and averaging the output of the output, a comparator 209 for slicing the output of the LPF 208 to a predetermined reference voltage, and the header removing unit 203 output and initial actuator direction, Determine that the direction of the actuator is switched using the output of Gyoki 209 and consists of an actuator direction generating unit 204 for outputting a direction signal actuator according to the determination result.

Here, the TZC time detector 201, the TZC time comparator 202, the header remover 203, and the actuator direction generator 204 may be implemented in software, and the first and second charge / discharge units 205 and 206 may be implemented in software. Adder 207. LPF 208 and comparator 209 may be implemented in hardware.

The present invention configured as described above determines that the direction of the actuator is changed only when the difference between the pulse width of the currently detected TZC signal and the pulse width of the previous TZC signal is n times or more, and outputs an actuator direction signal accordingly. For example, when the pulse width of the currently detected TZC signal is n times larger than the pulse width of the previous TZC signal, it is determined that the direction of the actuator is changed. At this time, since the header area is a very short period, there is a possibility that the difference between the pulse width of the TZC signal detected in the header area and the pulse width of the TZC signal detected after the header area is n times, in which case the direction of the actual actuator is not changed but is incorrect can do. Therefore, in the present invention, the pulse width of the TZC signal detected in the header area is excluded from the comparison object.

In addition, the present invention charges and discharges the TZC signal, averages the result, and slices to a predetermined reference voltage in order to more accurately detect the direction of the actuator. If the polling edge of the sliced signal is not detected until the pulse width of the currently detected TZC signal becomes n times the pulse width of the previous TZC signal, the direction of the actuator is switched at the point of time n times, and the falling edge is detected. The actuator then redirects the actuator at the falling edge.

To this end, first, the tracking error signal TE as shown in FIG. 3A is sliced into an internal reference signal (that is, the track cross position), and the tracking zero crossing signal TZC of the square wave as shown in FIG. Is generated and input to the TZC time detector 201. The TZC time detector 201 detects the time, that is, the pulse width, during the on and off periods of the TZC signal, respectively, and outputs the pulse width to the TZC time comparison unit 202. The TZC time comparison unit 202 compares the pulse width of the previous TZC signal with the pulse width of the currently input TZC signal and outputs the result to the actuator direction generation unit 204 through the header removal unit 203. . At this time, the header removing unit 203 excludes the pulse width of the TZC signal detected in the header region including the glitch from the comparison target. Since the header area is very short, there is a possibility that the difference between the pulse width of the TZC signal detected in the header area and the pulse width of the TZC signal detected after the header area is more than n times, in which case the direction of the actual actuator is not changed but is incorrect. Because you can.

Therefore, the actuator direction generation unit 204 determines that the direction of the actuator is changed when the difference between the previous pulse width and the next pulse width of the TZC signal from which the influence of the header is removed is n times or more. At this time, since the initial actuator direction is known, the value is input to the actuator direction generating unit 204, and the actuator direction generating unit 204 determines that the direction of the actuator is changed based on the initial actuator direction value. The actuator direction signal is switched each time.

On the other hand, if n, which is the reference for the comparison, is set incorrectly, the direction of the actuator may be misdetected or passed even when the header is removed. To prevent this, the first charging and discharging unit 205 charges and discharges the TZC signal, and the second charging and discharging unit 206 inverts the TZC signal in the inverter I1 and charges and discharges it. This is to detect the direction of the actuator regardless of the direction of the track jump since the TE signal is reversed according to the direction of the track jump. That is, the high section of the TZC signal may be long at the time when the actuator direction is changed, or conversely, the low section may be long. Here, the charge / discharge time depends on the RC time constants of the first and second charge / discharge units 205 and 206.

The outputs of the first and second charging and discharging units 205 and 206 are added by the adder 207 as shown in FIG. 3 (c), and averaged by low pass filtering as shown in FIG. 3 (d) by the LPF 208. Input to the comparator 209. The comparator 209 slices the low pass filtered value with a preset reference voltage as shown in FIG. 3 (d) and outputs it to the actuator direction generator 204 as shown in FIG. 3 (e). Here, the reference voltage can be adjusted according to the type of disk, speed, and the like.

If the falling edge of the sliced signal is not detected until the pulse width of the currently detected TZC signal becomes n times the pulse width of the previous TZC signal, the actuator direction generating unit 204 changes the direction of the actuator at the point of time n times. Switch. That is, the actuator direction generating unit 204 is n times if the falling edge of the signal is not detected until it is n times used for pulse width comparison starting from the rising edge of the signal output from the comparator 209. When it is determined that the direction of the actuator is changed at the time point, as shown in FIG. 3 (f), the previous actuator direction value is inverted and output.

If n is incorrectly set as shown in FIG. 4, that is, if the falling edge of the signal output from the comparator 209 is detected before the pulse width of the current TZC signal becomes more than n times the pulse width of the previous TZC signal, At the falling edge, the previous actuator direction value is inverted and output as shown in FIG.

As described above, the present invention may detect the direction of the actuator using both the pulse width comparison of the TZC signal and the slicing of the charge / discharge and low pass filtered signals, and may independently detect the direction of the actuator. That is, the actuator direction may be detected only by comparing the pulse widths of the TZC signals, the low-pass filtering of the charged / discharged TZC signals may be sliced to a reference voltage, and the actuator direction may be detected only by the sliced values.

In particular, when the actuator direction detection according to the present invention is applied at the time of a track jump such as seek, even when a mirror signal such as a DVD-RAM is not detected, auto brake can be applied and stable seek can be performed.

As described above, according to the actuator direction detecting method of the optical recorder according to the present invention, if the difference between the pulse width of the previous TZC signal and the pulse width of the current TZC signal is n times or more, it is determined that the direction of the actuator is switched. The TZC signal detected at is excluded from the actuator direction detection to increase the accuracy of the direction detection of the actuator. In addition, after charging and discharging and low pass filtering the TZC signal, the TZC signal is sliced to a predetermined reference voltage, and if the falling edge is not detected until n times is used for pulse width comparison in the sliced signal, the actuator is operated at the n times. By switching the direction and changing the direction of the actuator at the falling edge when the falling edge is detected, it is possible to accurately detect the direction of the actuator even when the setting of n is incorrect.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (8)

A method of detecting the direction of a tracking actuator of an optical recorder using a track zero crossing (TZC) signal that is turned on / off at a zero crossing time point of a tracking error signal. Detecting a pulse width of the TZC signal; Comparing the pulse width of the TZC signal detected in the step with the magnitude of the pulse width of the previous TZC signal; And determining that the direction of the tracking actuator has been changed when the difference between the pulse width of the TZC signal detected in the above step and the pulse width of the previous TZC signal is more than n times, and outputting the actuator direction signal accordingly. Actuator direction detection method of an optical recorder. The method of claim 1, wherein the time comparison step The pulse width of the TZC signal detected in the header area is excluded from the comparison. The method of claim 1, wherein generating the actuator direction A method of detecting an actuator direction of an optical recorder, characterized in that the actuator direction signal is switched whenever the initial actuator direction signal is input as a reference value and it is determined that the direction of the actuator is changed. The method of claim 1, wherein generating the actuator direction After charging and discharging the TZC signal and averaging the result to a predetermined reference voltage, if the falling edge of the sliced signal is not detected until n times, the direction of the actuator is changed at the n times, and the polling is performed. And switching the direction of the actuator at the falling edge when the edge is detected. The method of claim 4, wherein said step A first charging and discharging step of charging and discharging the TZC signal; A second charge and discharge step of inverting and charging and discharging the TZC signal; An averaged step of adding and averaging the outputs of the first and second charge and discharge steps; And a comparison step of slicing the output of the averaging step to a predetermined reference voltage and outputting the result to the actuator direction generating step. 6. The method of claim 5, wherein said averaging is And averaging the addition result by low pass filtering. The method of claim 5, And the reference voltage of the comparing step depends on the double speed. The method of claim 5, Wherein each of the steps is hardware.