MXPA00003074A - Method for controlling track jumps of optical pickup - Google Patents

Abstract

Disclosed is a method for controlling track jumps of an optical pickup in gaining high-speed access to a target track freeing from any effects of disturbances, in which time intervals of a TZC (tracking zero cross) signal are measured continuously for comparison between a target time and a measured time required for a track jump by the optical pickup. The difference in time is computed as an error, and a control signal with a voltage or a pulse width reflecting the magnitude of the error is output to an actuator of the optical pickup. In controlling the driving speed of the actuator, the comparison between target and measured times takes into account not only a time difference regarding the preceding track but also time differences with respect to a number of the previous track jumps. These time differences are illustratively averaged to yield a mean value, which is used as a basis for generating a control signal, thereby permitting fine-tuned control of the optical pickup in track jumps for high-speed and accurate positioning onto a target track freeing from any effects of scars and other disturbances on the optical disc.

Description

"METHOD FOR CONTROLLING TRACKS OF THE OPTICAL CAPTOR" BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a method for controlling the track jumps of an optical pickup. More particularly, the invention relates to a method for controlling track jumps of an optical pickup incorporated in an optical disc apparatus to control the optical pickup in a fine tuning manner such that the optical pickup moves rapidly and with accuracy towards a target track without suffering from any of the effects of disturbances such as scars on the disc on which the track jumps.

DESCRIPTION OF THE RELATED TECHNIQUE The optical disk apparatus referred to herein is a data reproduction apparatus that reproduces the recorded data of an optical disk, or is an apparatus that records and reproduces the data to and from an optical disk.

A typical optical disc apparatus is noted below with reference to Figure 6. Figure 6 is a functional diagram showing a total structure of an optical disc apparatus. As illustrated in Figure 6 the optical disk apparatus 20 basically comprises: a spindle motor 2 for rotating an optical disk 1; an optical sensor 3 for irradiating a laser beam towards the optical disk 1 during the data recording or reproduction; a double-axis mechanism 4 for obtaining an actuator for displacing a target lens 3a of the optical pickup 3 radially through the optical disc 1 and in a manner approaching and exiting the disc 1; a slide motor 5 for moving the optical pickup 3 radially through the optical disk 1; and a magnetic head, not shown, for applying a modulated magnetic field to the optical disk 1. The optical disc apparatus 20 further includes a recording and reproduction circuit 6. The registration and reproduction circuit 6 processes the video and audio signals coming from the optical pickup 3 in accordance with the predetermined formats and sends the processed results abroad. These data are also fed back to the optical pickup 3. In addition, the optical disc apparatus 20 comprises a processing servo circuit 7, a first driving circuit 8 and a second driving circuit 9 as control systems. The processing servo circuit 7 analyzes the reflected light signals that are detected by the optical sensor 3 and the optical disk 1. In doing so, the processing servo circuit 7 detects a focus point on the optical disc 1 of the laser beam irradiated by the optical pickup 3, as well as a relative positional relationship between the laser beam and the irradiated track. Through the first driving circuit 8, the processing servo circuit 7 then applies a focus control unit of the double-axis actuator 4 in the optical pickup 3 with a FOUT control signal to control the focus point up to a predetermined scale , and powering a tracking control unit of the double-axis actuator 4 in the optical pickup 3 with a control signal TOUT (tracking driving signal) to control up to a predetermined scale, the relative positional relationship between the laser beam and the irradiated track. Through the second driving circuit 9, the processing servo circuit 7 also supplies a control signal SOUT (driving signal) to move the optical pickup 3 in accordance with the amount of displacement made by the objective lens of the double-axis drive 4, towards the sliding motor 5 that moves the optical sensor 3. The processing servo circuit 7 thus moves the optical pickup 3 as an assembly in accordance with the lens moved by the double-axis drive 4, whereby the so-called tracking control is carried out to follow the track. In addition, the processing servo circuit 7 obtains, via the second drive circuit 9, a detected speed value from a speed sensor 10 which detects a speed of movement of the optical sensor 3. With the speed value acquired, the processing servo circuit 7 supplies to the second drive circuit 9 a control signal SDCNT (slide feed voltage) to control the speed of movement of the optical pickup 3. This allows the optical pickup 3 to move (i.e., skip track) evenly at an appropriately controlled movable speed. The manner in which the track jumps of the conventional optical pickup 3 are typically controlled will be described below with reference to Figures 7A to 7D. Figures 7A to 7D show time graphs of signals involved in controlling the track jumps of the optical pickup. An initial movement kick kick pulse, kick D indicated by the waveform in Figure 7C is first fed to a second driving circuit 9 to initiate the driving of the slider motor 5 in a desired direction. The sliding motor 5 is first driven in order to dampen the delay elements caused by inertia during the start as well as by the sensitivity of the initial movement and static friction of the motor. An initial motion tracking kick pulse F indicated by the waveform in Figure 7B is then supplied to the first driving circuit 8 to drive the tracking control unit of the double-axis actuator 4 in the optical pickup 3, by which the objective lens 3a of the optical pickup 3 is driven in a desired direction. A detected signal of the light output reflected from the optical pickup 3 is analyzed to illustratively find the difference in reflectance between the tracks and the non-track portions on the recording surface of the optical disc. This analysis process yields a tracking error signal (TE) representing the relative positional relationship between the laser beam and the tracks as indicated by the waveform in Figure 7A. Counting the zero crossing points (TZC) of the tracking error signal (TE) provides the number of tracks traversed by the optical pickup 3 in the track jumps. Then, in accordance with the number of skipped tracks, an SDCNT control signal for controlling a target movement speed of the optical pickup 3 is adjusted as indicated by the waveform in Figure 7D. In addition, a tracking kick voltage is applied to a tracking actuator to control the track jumps of the optical pickup 3, thereby allowing the optical pickup 3 to reach a desired track. As noted above, the optical pickup is conventionally controlled in track jumps using control signals based on a number of factors: constant time intervals, a predetermined voltage level, or a variable voltage signal all associated therewith with inversion of polarity between beginnings and detentions. However, each of these control signals is determined on the basis of the result of the single track jump immediately preceding, so that the failure to measure that specific track jump activates the output of the erroneous kick impulses, leading to a unstable control of the optical sensor. The conventional method is therefore limited to control capacity and has had difficulty in providing high speed access to the target track. In addition, not only being deficient in accuracy in the operation of the jump, the conventional control method for the optical pickup exhibits late recovery of unstable jumps caused by scars or smears on the surface of the disk, leading to a jump error in some cases , making it impossible in this way to achieve the target track.

COMPENDIUM OF THE INVENTION The present invention has been developed in view of the aforementioned circumstances and provides a method for controlling the track jumps of an optical pickup to have high speed access to a target track by releasing any of the effects of the disturbances. When the projects of the present invention are devised, the inventors of this invention studied the conventional method and came to the conclusion that: the conventional speed control type method for the optical sensor exhibits its deficient control capability pointed to the process of determining the next control signal based on the result of the previous single track hop, regardless of whether the control voltage or the pulse width of the control signal was fixed or variable. The solution proposed by the inventors for the aforementioned deficiency is the following: Illustratively, intervals of TZC signals (zero tracking crossings) are continuously measured to compare between a target time and a measured time. The difference between them is calculated as an error, and a control signal with a voltage to a pulse width that represents the magnitude of that error is sent to the optical pickup driver. For the control of the driving speed of the actuator, the comparison between the target and measured times must take into account not only a time difference with respect to an individual previous track but also the time differences with respect to a number of the jumps of previous tracks. These time differences are then averaged illustratively to yield an average value that is used as a basis to generate a control signal. Therefore, even using a disk where the track inclinations vary for several tracks and the tracking error signal can contain many noise elements so that the TZC intervals are widened or abruptly reduced as if the TZC signals were being balanced, the method of the invention still allows the actual speed to be measured without error in order to ensure reliable jump movements. In accomplishing the foregoing and other objects of the present invention and in accordance with an aspect thereof, there is provided a method for controlling track jumps of an optical pickup in an optical disc apparatus to record and reproduce the data to and from an optical disk, wherein the optical pickup moves to a target track of the optical disc comprising the steps of: when the optical pickup has jumped to a single track placed midway between the current position and the blank track; calculating a speed difference between a graduated target jump speed for the single track and a jump speed actually measured across the single track; sending an acceleration signal, a deceleration signal and a velocity maintenance signal representing the magnitude of the speed difference between the velocity of the target jump and the jump velocity measured as a control signal to control the velocity for the optical pickup so that it jumps to the next track immediately after the single track; adjusting the jump speed difference with respect to the single track based on at least one of the speed differences between the target jump speed and the hopping speeds measured with respect to a plurality of tracks previously skipped to the single track, and resorting to predetermined relationship expressions; and sending an acceleration signal, a deceleration signal and a signal to maintain the speed based on the jump speed difference set as a control signal for a track jump to the next track. In accordance with the present invention, using too many tracks to adjust the speed difference can level the control signals, resulting in poor accuracy. In practice, approximately three tracks are preferred, that is, one track plus the two tracks before it. Preferably, the method further comprises the step of calculating the speed difference between the white and measured skip rates based on time intervals of a runway zero crossing signal. In another preferred variation of the invention, the method further comprises the step of sending a pulse signal having a variable pulse width as a control signal such that: (1) if the adjusted speed difference is positive, with the measured jump speed higher than the white jump speed, the optical pickup jump speed decelerates in proportion to the magnitude of the speed difference; (2) if the adjusted jump speed difference is negative, with the measured jump speed smaller than the target jump speed, the jump speed of the optical pickup is accelerated in proportion to the magnitude of the speed difference; and (3) if the adjusted jump speed difference is zero, with the jump speed measured equal to the target jump speed, the jump speed of the optical pickup remains unchanged. In a further preferred variation of the invention, a pulse signal having a variable pulse voltage may be sent as a control signal, by carrying out the three above-mentioned control steps. As noted, the method of the invention for controlling track jumps of the optical pickup involves acquiring speed differences between the white and measured jump speeds from the track jumps through a plurality of tracks, and supplying an actuator. of tracking and a slider motor with control signals that reflect the speed differences acquired between the white and measured speed speeds for speed control. This allows accurate track jumps from the optical pickup through the surface of the disk regardless of disturbances. Other objects, features and advantages of the invention will become more apparent upon reading the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart of the steps constituting a method for carrying out illustratively a method for controlling the track jumps of an optical pickup as an embodiment of the invention. Figure 2 is a continuous flow chart of that of Figure 1; Figure 3 is a graph of time of signals used under the project of variable control of impulse width of kick; Figure 4 is a detailed time plot of the signals used under the variable impulse width control project; Figure 5 is a detailed time plot of the signals used under the variable kick voltage control project; Figure 6 is a functional diagram showing a total structure of a disk apparatus. typical optical; and Figures 7A to 7D show time graphs of control signals for use by a conventional method for controlling track jumps of an optical pickup.

DESCRIPTION OF THE PREFERRED MODALITIES Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Preferred Mode A preferred embodiment of a method for controlling track jumps of an optical pickup in accordance with the invention is described below, the method being applied to the optical disc apparatus 20 mentioned above. Figures 1 and 2 are flow charts showing steps that constitute a method for carrying out the track skip control method of the invention of the optical pickup; Figure 3 is a graph of time of signals used under a project of variable control of kick pulse width to control track jumps of the optical pickup; Figure 4 is a detailed time plot of the signals used under the variable booster pulse width control project; and Figure 5 is a detailed time plot of the signals used under a variable kick voltage control project to control track jumps of the optical pickup. The method for controlling the track hopping of the optical pickup incorporated in the optical disc apparatus 20 will now be described. In the description that follows, the method of the invention for controlling track jumps of the optical pickup can be mentioned as a "fine search" because the method allows highly accurate search or control. The track skip control method encompassed by the invention is explained with reference to FIG. 1. At the start of the track skip control of the optical pickup, a tracking servo circuit is connected and a slide circuit is switched off. A target number of track jumps is graded as N in step SI, followed by step S2. The target number of the jumps means a desired number of tracks through which the optical pickup moves as it traverses the surface of the disc. If the optical pickup is going to traverse from a current track N] _ to a blank track N2, then the track number of the track jumps N is given as N = N2 - N] _. In step S2, the tracking servo circuit adjusts to a high gain before step S3 is reached. In step S3, the TZC signal is set illustratively for a frequency A in order to determine a target tracking speed of the optical pickup. Step S3 is followed by step S4. In step S4, a kick pulse indicated "Kick D" in Figure 3 is applied to the slider motor 5. Step S4 is followed by step S5. In this embodiment, as shown in Figure 3, a slide driving signal is loaded with an initial movement kick kick (kick D) kicking the slider motor 5 to set it in motion. The kick pulse D is generated chronically a little earlier than the kicker F of the tracking drive signal in order to dampen and compensate a delayed movement of the optical pickup 3 due to its mass inertia and poor initial movement sensitivity of the motor 5 of slide, as well as to remove a delay caused by the static friction of the sensor. In other words, the driving signal of the slider is temporarily positioned in a staggered manner with respect to the tracking driving signal to dampen the delay elements in the movement of the optical pickup 3. In step S5, first, the tracking servo circuit is switched off and the braking circuit of the tracking servo circuit is switched on. The tracking drive signal is loaded with an initial motion tracking kick pulse indicated as "Kick F" in Figure 3 which kicks the double-axis actuator 4 in motion. With tracking accelerated in this way, step S6 is reached. After the kick pulse F is supplied to the tracking drive signal, the track skip speed of the optical pickup 3 is controlled so that the TZC signal reaches the set frequency A. Then, the optical pickup 3 moves up to near the blank track N2 together with the slider motor 5. In step S6, the frequency A is compared with the time intervals of the various previous signals TZC. The details of the comparison will be described later. Step S6 is followed by step S7.

In step S7, the kick pulses are generated in accordance with the comparison result to accelerate or decelerate the double-axis actuator 4 and the corrugating motor 5. There are two projects for acceleration and deceleration: the variable control project of pulse width, and a variable impulse voltage control project as will be described later. The pulse width or pulse voltage representing a kick pulse time is adjusted in accordance with the differences between the TZC signal intervals and a target time. Step S7 is followed by step S8. In step S8, an adjustment is made to see if the number of track jumps by the optical pickup 3 is N-a. If the hop count is equal to N - a, then step S9 is reached; otherwise step S6 is reached again. The value a represents the number of tracks established as a difference between the blank track N2, and a track where the optical pickup 3 switches the signal frequency TZC from A to B (A> B). If the track Np at the current position of the optical pickup 3 is defined as Np = N-a, that is, if the optical pickup 3 is placed to tracks in front of the blank track, then step S9 is reached to switch the frequency of the TZC signal from A to B.

With the optical pickup 3 positioned near the white track N2 in step S9, the frequency of the TZC signal is adjusted for a frequency B lower than the frequency A to carry out the speed control in a fine tuned manner while that the slide motor 5 stops to prepare for a jump end, before the step S10 is reached. That is, the slider motor 5 is temporarily stopped and then applied with kick pulses or a voltage for further movement based on the amount of displacement by the objective lens of the optical pickup 3 which keeps moving due to its inertia. If the target track N2 is reached in step S9, brake pulses are applied to the braking circuit for sufficient deceleration just as in a single track skip control. In step S10, the optical pickup 3 is controlled in its speed to skip the track in a finely tuned manner by using the signal TZC having the lowest frequency B. The step S10 is followed by the step Sil . In step Sil, a judgment is made to see if the number of track jumps is equal to N. If the jump count is found to have reached N, this means that the optical pickup 3 is placed on the target track. 2. In that case, step S12 is reached. If the hop count is less than N, step S10 is reached again. In step S12, the tracking servo circuit is switched on. After the activation of the tracking servo circuit is verified, the slide servo circuit is switched on. Step S12 is followed by step S13. In step S13, a time T is allowed to retain the current state as it is. During the course of time T, step S14 is reached. In step S14, an adjustment is made to see if the waiting time T is longer than 2 milliseconds (T> 2 milliseconds). If the time T is found to be longer than 2 milliseconds, step S15 is reached; otherwise step S13 is reached again. In step S15, the track skip is completed, and the normal tracking gain is established. This determines the execution of the track skip control procedure. In step S9 of this embodiment, the slider motor is temporarily stopped and then applied with kick pulses or a voltage for further movement based on the amount of displacement made by the objective lens 3a of the optical pickup 3. However, this is not limiting of the invention, and the slider motor 5 can be left connected alternatively.

When the slider motor 5 moves more rapidly, the slider motor 5 can temporarily stop to let the optical pickup 3 move under its own inertia. Otherwise the pulses in the opposite direction can be applied to control the slider motor 5 for deceleration. Even when two frequencies (time) A and B are used for the TZC signal in this mode, this is not limiting of the invention. Alternatively, three or more frequencies can be set along with more detailed white time settings to achieve fine tuning speed control. All adjusted values and parameters used in this mode are for illustrative purposes only. In practice, these values can be adjusted to meet the specific characteristics of the optical sensor and its driving mechanisms actually used in them. Figure 3 is a time plot showing a tracking error signal (TE), a tracking driving signal (TOUT), a sliding driving signal (SOUT) and a sliding feeding voltage (SDCNT) used to control the track jumps of the optical sensor under the project of variable control of impulse width of kick.

In Figure 3, the frequency (time) of the kick pulses is adjusted to an optimum value that represents the number of tracks leading to the target track. When the optical pickup reaches the target track, the time deceleration pulses are sent to the braking circuit of the slider motor 5 to standardize the positioning on the target track. The slider motor 5 is moved by application of kick pulses with a voltage which is determined in accordance with the amount of displacement made by the objective lens of the optical pickup. The comparison of the time intervals of the TZC signal with the frequency A carried out in step S6 is described below, followed by the acceleration / deceleration setting of the double-shaft actuator 4 and the slider motor 5 which were taken away performed in step S7. These treatments will be explained for two cases: under the project of variable control of pulse width in fact and under the project of variable control of impulse voltage in fact. (1) Search for Impulse Width Variable Control How many track jumps are controlled under the pulse width variable control project will now be described with reference to Figure 4.

It is assumed that a target jump time is represented by Ttgt and that a time actually measured from bank to bank of a TZC signal is represented by TtzcO. The white skip time is a set blank time for the TZC signal interval during the track skip depending on the number of tracks to be skipped. It is also assumed that the other times measured from shore to shore of the TZC signals are represented by Ttzcl and Ttzc2 in sequence. Even when three TZC signal intervals are sampled in this embodiment, this is not limiting of the present invention. An appropriate number of samples may be taken depending on the current operating state of the optical pickup 3. The errors between the target time and the measured time are defined as TerrO = Ttgt - TtzcO, Terrl = Ttgt -Ttzcl, and Terr2 = Ttgt - Ttzc2. The TerrO a Terr2 information is used as a basis to calculate a Terr of final error according to the predetermined methods. The final error is used to adjust the time width of the kick pulses of the double-axis actuator 4 so that the optimal kick pulses are eventually supplied to the actuator. The default methods for definitive error calculation include, among others, a method for finding a mean value of the calculated errors, and a method for ignoring those extreme measures of display, which are supposedly attributable to erroneous measurement procedures or some disturbances while an average value of the remaining calculated errors is obtained. By abbreviating, kick impulses are generated by observing not only the interval with respect to the individual previous TZC signal but also at intervals of several previous TZC signals recently. Given the speed measurement, the appropriate kick impulses are generated and supplied. Below is a description of what takes place in two cases: when the actuator is operated at high speed, and when the actuator is operated at low speed. (a) When the operating speed of the actuator is high When the operating speed of the actuator is high, the wave-to-wave distance in a transverse waveform of the tracking error signal becomes narrower, and also the interval of the TZC signal, that is, the width of the zero crossing pulses of the tracking error signal. This means that the frequency of the signal rises. The case applies when the speed of the actual jump movement of the optical pickup 3 is higher than the target speed with the error Terr greater than 0 (Terr> 0). In this case, the error is compensated for by applying the double-axis actuator 4 with pulses in the deceleration direction. The bigger the Terr error (ie, the higher the frequency), the pulse width is applied to reinforce the deceleration for the fastest possible approach to the target time Ttgt. (b) When the operating speed of the actuator is low On the contrary, when the operating speed of the actuator is low, the wave-to-wave distance in the transverse waveform of the tracking error signal is widened and so also the time interval of the TZC signal. This means that the frequency of the signal is lowered. This is the case where the speed of the movement of the actual jump of the optical sensor 3 is less than the speed of the target with the error Terr being less than 0 (Terr <; 0). In this case, the error is compensated for by applying the double-axis actuator 4 with pulses in the acceleration direction. In addition, inverted polarity pulses with the largest width are applied to the Terr error as the Terr error grows further (ie, being lowered in frequency) to reinforce the acceleration for the fastest possible approach to the target time Ttgt. As described, the width of the kick pulse is varied in accordance with the error (Terr) in the measured times Ttzc obtained as a result of measuring the multiple previous jumps with respect to the target time Ttgt. The kick impulses with their width adjusted in this way are used to carry out the optimal track jumps. (2) Search for Variable Impulse Voltage Control Now how many track jumps are controlled under the variable impulse voltage control project will be described, referring to Figure 5. As with the variable impulse width control project , the actual jump time is inhibited (TZC time interval) and the error Terr is obtained with respect to the target time. The errors between the target time and the measured times are defined as TerrO = Ttgt - TtzcO, Terrl = Ttgt - Ttzcl, and Terr2 = Ttgt - Ttzc2. The information TerrO, Terrl and Terr2 are used as a basis to calculate a Terr of definitive error, using appropriate methods. The final error is used to adjust the kick voltage for the double-axis actuator 4 so that the optimal kick pulses are eventually generated. Appropriate methods for calculating final error include, among others, a method to find a mean value between the calculated errors TerrO, Terrl and Terr2, and a method to ignore those extreme measures of exposure allegedly attributable to erroneous measurement procedures or to a certain disturbance while an average value of the calculated residual error is obtained. The kick pulses are generated not only by ignoring the interval of the previous singular TZC signal, but also the time intervals of the various previous TZC signals. The time interval information acquired in this manner from the three previous TZC signals is used to accurately detect the speed at which the optical pickup is currently moving. Given the speed measurement, the appropriate kick impulses are generated and supplied. (a) When the operating speed of the actuator is high When the operating speed of the actuator is high, the wave-to-wave distance in the transverse waveform of the tracking error signal becomes narrower, and also the range of time of the TZC signal.

That is, the frequency of the signal rises. This is the case where the speed of the current jump movement of the optical sensor 3 is higher than the target speed, with the error Terr greater than 0 (Terr> 0). In this case, the error is compensated by supplying the double-axis actuator 4 with pulses in the deceleration direction. Also, the more Terr error grows (ie, the higher the frequency), the higher the impulse voltage applied to reinforce the deceleration for the fastest possible approach to the target time Ttgt. (b) When the operating speed of the actuator is low. Conversely, when the operating speed of the actuator is relatively low, the wave-to-wave distance in the transverse waveform of the tracking error signal widens, and so also the time interval of the TZC signal. That is, the frequency of the signal is lowered. This is the case where the velocity of the actual jump movement of the optical pickup 3 is lower than the target speed, with the Terr error less than 0 (Terr <0). In this case, the error is compensated for by supplying the double-axis actuator 4 with pulses in the acceleration direction, and the more the Terr error grows (ie the lower the frequency), the higher the inverted polarity pulse voltage. which is applied to reinforce the acceleration for the fastest possible approach to the target time Ttgt. As described, the kick voltage level is varied according to the error (Terr) in the measured times Ttzc obtained as a result of the multiple previous jumps with respect to the target time Ttgt. The kick voltage set in this way is used to carry out the optimal track jumps. From a different point of view, the previous project is designed to raise the gain for the tracking speed control of the optical pickup 3 where the kick voltage is varied according to the error in the measured times Ttzc with respect to the time of white to carry out optimal track jumps. One of the two runway control projects described above, that is, the variable pulse width search in the variable pulse voltage search can be implemented selectively depending on the search mode (jump) and the current operating state of the optical pickup. A more accurate control is possible if one of these projects is used selectively in accordance with the jump distance and the type of optical disk. The two projects can alternatively be used in combination for speed control achieving even higher levels of accuracy. In the manner described above, the double-axis actuator 4 is well controlled in speed by presenting the high level of speed control accurately. Accordingly, the method of the present invention allows reliable hopping operation. In summary, the method of the invention involves comparing a target time required for track skipping by the optical pickup, which actually measures time by calculating the time differences between them as an error, and supplying the optical sensor driver with a control signal having a voltage or pulse width that reflects the magnitude of the error calculated in this way to control the drive speed of the actuator. During this time, the signal to control the driving speed of the actuator is generated taking into account the time differences not only in the difference of time in the single jump of previous track, but also in the time difference in the track jumps that they precede the individual track jump carried out. These time differences are averaged to yield an average value which is then used as a basis to generate the control signal. When implemented as described, the method according to the present invention allows a fine tuning control of the optical pickup in high-speed track jumps and accurate positioning on the target track by releasing any of the effects of scars and other disturbances in the optical disc. On a disc where the track inclinations vary for several tracks, the tracking error signal that contains numerous noise components causes the TZC intervals to widen or narrow sharply as if TZC was freeing. Even in this case, the method of the invention still ensures reliable jumping movements overcoming the conventional failures of speed control. Since many apparently different embodiments of this invention can be made without departing from the spirit and scope thereof, it will be understood that the invention is not limited to the specific embodiments thereof, except as defined in the appended claims.

Claims (6)

R E I V I N D I C A C I O N E S:

1. A method for controlling the track jumps of an optical pickup in an optical disc apparatus for recording and reproducing the data to and from an optical disc, wherein the optical pickup moves to a target track of the optical disc, comprises the steps of: when the optical pickup has jumped to a single track placed in the middle between the current position and the target track, calculate a speed difference between a target jump speed set for the track alone, and a measured jump speed actually through the single track; send an acceleration signal, a deceleration signal and a signal that maintains a signal representing the magnitude of the speed difference between the target and jump speeds measured as a control signal to control the speed of the optical pickup to jump to a next track, immediately after a single track; adjusting the jump speed difference with respect to the single track based on at least one of the speed differences between the target speeds and the measured jump with respect to the plurality of previously skipped tracks to the single track, and resorting to expressions of predetermined relationships; and sending an acceleration signal, a deceleration signal and the signal maintaining the velocity based on the difference in jump velocity set as a control signal for a jump through the next track. A method for controlling track jumps of an optical pickup according to claim 1, further comprising the step of calculating the speed difference between the target and jump speeds measured based on time intervals of a signal from zero crossing of the track jump. 3. A method for controlling the track jumps of an optical pickup in accordance with the claim 1, further comprising the step of sending an impulse signal having a variable pulse width as a control signal, such that: (1) if the adjusted speed difference is positive, with the measured jump speed more higher than the speed of the target jump, the jump speed of the optical sensor that decelerates in proportion to a magnitude of the speed difference; (2) if the set jump speed difference is negative, with the measured jump speed lower than the target jump speed, the jump speed of the optical pickup is accelerated in proportion to the magnitude of the speed difference; and (3) if the adjusted jump speed difference is zero, with the jump speed measured equal to the speed of the target jump, the jump speed of the optical pickup remains unchanged. A method for controlling track jumps of an optical pickup according to claim 1, further comprising the step of sending a pulse signal having a variable voltage as a control signal in such a way that: (1) if the set velocity difference is positive, with the measured hop velocity higher than the target hop velocity, the hopper velocity of the optical pickup decelerates in proportion to a magnitude of the velocity difference; (2) if the set jump speed difference is negative, with the measured jump speed lower than the target jump speed, the jump speed of the optical pickup is accelerated in proportion to the magnitude of the speed difference; and (3) if the adjusted jump speed difference is zero, with the jump speed measured equal to the target jump speed, the jump speed of the optical pickup remains unchanged. A method for controlling track jumps of an optical pickup according to claim 3 or 4, further comprising the step of selecting one of three track skip control steps depending on the current operating state of the optical pickup. 6. A method for controlling track jumps of an optical pickup according to any of claims 1 to 5, which further comprises the step of either acquiring an average value of the speed differences using predetermined relationship expressions or acquiring another average value of the speed differences by eliminating any of the speed differences that exceed a predetermined scale of the average value.