KR930008492B1 - Positioning servosystem for cdp - Google Patents

Abstract

The system transfers the optical head into the target track without error in time, in the optical disk device which restores the stored information or records the information on the track structure disk. To seek an exact track, this system has a micro processor (3) which controls each device by permission from the transferring track information, memory device (4) which store the data, reference voltage generating device (5) by tracking error, sampling signal generating device (6), actuator drive signal generating device (7), a 1st adder (8), sample and hold circuit (9), phase compensating circuit (10), one track compensating circuit (11), switching circuit (12), a 2nd adder (13), and a 3rd adder device (14).

Description

High speed positioning servo system of optical disk device

1 is a tracking error signal generation circuit according to the present invention.

2 is an output waveform diagram of FIG.

3 is an overall block diagram of a high speed positioning servo system according to the present invention.

4 is a waveform diagram of a tracking error signal according to distortion of a disk.

5 is a tracking error reference signal generation circuit according to the present invention.

6 is a view of each sub waveform of FIG.

7 is a sampling signal generating circuit according to the present invention.

8 is a view of each sub waveform of FIG.

9 is a 1 track compensation circuit according to the present invention.

FIG. 10 is a view of each sub waveform of FIG.

11 is a speed timing chart in the positioning operation according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high speed positioning servo system of an optical disk apparatus, and more particularly, to an optical disk apparatus for recording or reproducing recorded information on a disk having an uneven track structure. The present invention relates to a servo system for moving an optical head without errors to a desired target track in a short time.

In the conventional optical disk apparatus, in order to set a desired target track, an actuator driving voltage according to the number of tracks to be moved is applied, and then a tracking error signal generated by moving the track is fed back. feedback) and converts it into a pulse signal, and counts it to recognize the number of tracks moved.When the counted value is 1/2 of the number of tracks to be moved, the actuator drive signal is changed to a deceleration signal, and the counted value and When it is the same, the actuator drive signal is "off" to move to the desired track, or a sensor such as a linear encoder is attached to the actuator to move to the desired track using the detection signal generated by the movement of the actuator. In this case, counting the feedback tracking error signal is used to control the position. The difference between the stop track of the track and the target track occurs, and the error becomes large. Also, since the position of the error track must be repositioned to find the desired track, the positioning time becomes longer. In the case of a position sensor, such as a linear encoder takes, so that the circuit is not only complicated, but also the disadvantages such as a rise in the manufacturing cost accordingly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a servo system for moving an optical head to a desired target track on a disc in a short time without error, and is stored in a read only memory (ROM) at the start of positioning, but has been calculated in advance. The speed signal according to the number is applied to the actuator, and the position and speed of the actuator are controlled by using the reference tracking error information for controlling the sampling time, the actuator position during initial acceleration and final deceleration also stored in the ROM. The sampling time at the time of positioning is calculated in consideration of the acceleration, deceleration, actuator constant, etc., and the input tracking error signal is sampled when the light beam passes the land or groove on the track. Compensate for errors that occur every time the matrack passes, so that errors do not accumulate. Which will help you find exactly the group you want the track.

A high speed positioning servo system of an optical disk apparatus according to the present invention comprises: processing means for receiving movement track information and controlling each means accordingly; Storage means for storing an acceleration / deceleration voltage data, data for a sampling time, a tracking error reference voltage data, and the like for detecting an error according to a track to be moved; Tracking error reference voltage generating means for reading data into said storage means under control of said processing means to generate a tracking error reference voltage during initial acceleration and deceleration termination; Sampling signal generating means for reading a data stored in said storage means and generating a sampling signal for sampling a tracking error after acceleration of an actuator under the control of said processing means; An actuator drive signal generation means for reading data stored in the storage means under the control of the processing means and generating an acceleration / deceleration signal according to the number of movement tracks; First adder means for adding a tracking error signal and a tracking error reference signal from said tracking error reference voltage generating means; Sample and Hold (S & H) circuit means for receiving an output signal from the sampling signal generating means and holding the sampled output signal from the first adder means for a predetermined time; Phase compensation circuit means for compensating an output signal from said S & H circuit means to a predetermined phase; 1 track compensation circuit means for comparing and detecting whether an error occurs every 1 track movement and generating a compensation voltage according to the error occurrence; Switching circuit means for receiving an acceleration / deceleration signal corresponding to the number of movement tracks from the actuator drive signal generation means and selecting an input target point of the signal; Second adder means for connecting the actuator drive signal to each output side of the generating means, the phase compensating circuit means and the one track compensating circuit means to add each output signal therefrom to drive a fine driving actuator; And a third adder means connected to the switching circuit means for receiving an output signal from the actuator drive signal generating means to drive the coarse driving actuator.

In addition, the high speed positioning system of the optical disk apparatus according to the present invention has a clock signal generating means for a clock signal corresponding to the frequency of the tracking error signal and a dividing means for dividing a clock signal from the clock signal generating means. And sampling signal generating means having switching circuit means for selectively transmitting only one of the clock signals divided by the dividing means and a counter means for counting the selected clock signal from the dividing means.

In addition, the high-speed positioning system of the optical disk apparatus according to the present invention is a zero crossing detection circuit means for generating a pulse signal for each track movement by inputting a tracking error signal, and specifying a sampled tracking error signal. A delay means for delaying by the time, a first comparison means for comparing whether the zero crossing sensing circuit means and the output means of the delay means are moved by one track, and the first comparison means, the zero crossing sensing circuit means and the delay means Second comparison means for comparing whether or not one track has traveled as much as one track, and a first reference time for generating a compensation voltage when connected to the output side of the first comparison means for one track less movement. It is connected to the setting means, the first reference voltage generating means, and the output side of the second comparing means and moves as much as one track. To a second reference time setting means and the first track circuit compensation means having a second reference voltage generating means for generating a compensation voltage of eulsi.

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

FIG. 1 is a tracking error signal generation circuit according to the present invention, and as shown in FIG. 2a, projects and reflects an optical beam onto a disc 2 having a plurality of tracks consisting of a land portion 2a and a groove portion 2b. The light is received by the photodetector 1a and the corresponding signal is subtracted by the subtractor 1b, the LPF (Low Pass Filter) IC for limiting the frequency band, and constant regardless of the output of the laser beam during reading, writing or erasing. The AGC (Automatic Gain Control) circuit 1d for outputting a signal is used to indicate whether the light beam is accurately positioned on the track. The signal at this time is shown in FIG. This represents a tracking error signal when each of the uneven structures on the track passes through the light beam, and in this case, when the amplitude of the tracking error signal is maximized, each of the grooves 2a and the grooves 2b on the disc 2 are increased. When the light beam is located at the boundary point, the amplitude of the tracking error signal becomes " 0 " in the center portion of each land portion 2a or groove portion 2b. As a result, one cycle of the tracking error signal is generated every time one track passes, so if you count it, you can know the number of tracks that have been moved.However, if you control the positioning servo system with the counted value at this time, it moves near the last track. There is a problem that an error occurs. If the tracking error signal is sampled when passing through the central portion of the land portion 2a or the groove portion 2b, if the value of the tracking error signal is not "0", then a position error has occurred. Conversely, if the servo system is driven, the position error can be corrected to "0".

By using these characteristics, the speed and position error generated when positioning to a desired track is compensated each time it passes each land part 2a or groove part 2b so that the error does not accumulate and moves to the target track accurately. First, a controller (1) receiving movement track information from a host computer (not shown) transfers the number of movement tracks to the microprocessor (3) through the Vo port (2). ) Reads the value of ROM (4) which stores deceleration voltage data in advance according to the number of tracks to be moved, and outputs the value to 2DAC (Digital-to Anallog Converter; 7). When the number is less than or equal to a predetermined track, for example, 40 tracks or less, the actuator driving voltage according to the data is applied to the second adder 13 only by the switching circuit 12 so as to allow fine driving. The positioning by only Chuo radiator 16 and is made. In addition, if the number of tracks to be moved is greater than or equal to a predetermined track, for example, more than 40 tracks, the actuator driving voltage is applied to both the second and third adders 13 and 14 by the driving of the switching circuit 12 for fine driving. Both the actuator 16 and the coarse driving actuator 18 are accelerated to complete the movement to the target track in a short time.

When the actuator starts accelerating or decelerates, the tracking error signal from the tracking error signal generating circuit shown in FIG. 1 and the tracking error reference signal from the first DAC 5 are added by the first adder 8. The S & H circuit 9 is applied to the S & H circuit 9, and the sampling signal generation circuit 6 reads a pre-calculated sampling time point from the ROM 4, and applies the sampling signal accordingly to the S & H circuit 9. Accordingly, after the output signal from the first adder 8 is sampled, it is input to the second adder 13 through the phase compensating circuit 10 and added with the signal from the second DAC 7 described above. Next, the first driving amplifier 15 is input to drive the micro drive actuator 16. In addition, the track error signal from the tracking error signal generation circuit of FIG. 1, which is increased in the one track compensation circuit 11, is detected and compared for each track, and when the error occurs, a compensation voltage is generated accordingly. It is input to the second adder 13, and accordingly compensation is performed for each mat rack, thereby enabling accurate positioning.

As shown in FIG. 4A, when a radial runout occurs in the manufacturing process of the disc 21, when the fine driving actuator 16 or the rough driving actuator 18 starts acceleration or deceleration, Since the acceleration or deceleration speed of the actuator 16 or 18 with respect to the distorted portion is slowed down, as shown in FIG. 4B, a tracking error signal is generated as though it did not actually pass through the track. In order to compensate for this, as shown in FIG. 5, the data for the initial acceleration and tracking errors stored in the ROM 4 in advance are passed through the first DAC 5 and the amplifier 5a to the first adder 8. Tracking error signal (added to 6a) is added to the track error information with actual track movement information so that the error value for the reference signal is eliminated so that accurate acceleration and deceleration can be achieved regardless of the signal due to distortion. If the reference signal (Fig. 6b) is not inputted to the first adder 8, it is made by the error control sampling signal generation circuit 6. 6c is a waveform diagram for each part a to c of FIG.

Since the frequency of the tracking error signal increases as the actuator is accelerated, the frequency of the tracking error signal is sampled to recognize whether the error value is "0" by sampling the tracking error signal at each land portion 2a or the groove portion 2b. In accordance with this, the period of the sampling signal is generated in synchronization with the reference click signal.

7 is a sampling signal generation circuit according to the present invention, and FIGS. 8 (a) to (j) are waveform diagrams for the respective parts (a to j) of FIG.

First, the reference clock signal generated by the clock signal generator 6a is divided by the divider 6b to generate a predetermined clock signal 1 and a clock signal 2. On the other hand, a clock selection signal (Fig. 8A) and a count enable signal (Fig. 8B) are applied to the switching circuit 6c, and the output thereof is applied to one input terminal of the first and second gate circuits 6d and 6e, respectively. When input, only one of clock signals 1 and 2 divided by the divider 6b is outputted to the third gate circuit 6f and applied to the counter 6g. The data value to be counted is applied to the counter 6g by the data bus signal as shown in FIG. 8D, and at the same time, the chip enable signal (Fig. 8C) through the microprocessor 3 of FIG. Fig. 8E is applied to the counter 6g to count the data value latched by the count enable signal (Fig. 8B) and accordingly the sampling signal (Fig. 8F to S & H circuit 9). Then, the data request signal (Fig. 8G is transmitted to the microprocessor 3 through the flip-flop circuit 6h) for reloading the data to be counted. The tracking error signal for the 2a or the groove 2b is sampled, where the clock signals 1 and 2 are different frequencies, and the clock signal 2 is higher than the clock signal 1. If the frequency is increased and the count cannot be performed with the clock signal 1, the count is performed as the clock signal 2. The clock switching is performed by applying the clock selection signal of Fig. 8A to the switching circuit 6c.

Sampling the tracking error signal with the sampling signal generated by the sampling signal generating circuit 6c described above and correcting the error is only one track or less, and corrects the error of one track or more due to disturbance when positioning. This is for the one track compensation circuit shown in FIG. 10 (a) to 10 (h) are waveform diagrams for the parts a to h shown in FIG.

The tracking error signal of FIG. 10A is input to the comparator 11a to make one pulse for each track, and the sampling signal of FIG. 10C is input to the delay circuit 11b to output each of them (FIG. 10B). And (d) is applied to the first and second flip-flop circuits 11c and 11d, where the first flip-flop circuit 11c moves only by one track less than the track to be moved. 10e degrees), and the second flip-flop circuit 11d transmits an output signal (FIG. 10f) only when the second flip-flop circuit 11d moves one track more than the track to be moved. The first reference time setting circuit 11e and the first reference voltage generating circuit 11f or the second reference time setting circuit 11g and the second reference voltage generating circuit that receive the signal from the flip-flop circuit 11c or 11d. At 11h, the corresponding compensation voltage is generated to generate the buffer circuit 11i. Is sent to the second adder 13 through 11j) it is to compensate the error of the first track at every movement.

FIG. 10A is a tracking error signal, where a 'is one track more than the track to be moved and a "is one track less than the track to be moved. (B) FIG. (C) shows a sampling signal, and (d) shows that the sampling signal of (c) is delayed by a predetermined time, except for a 'and a "in (a). In (b) and (d), the pulse signal is generated simultaneously. In the 'a' section, the pulse signal is generated only in (b), and in the "a" section, the pulse signal is generated. Information (e) and (f) pulses are shown as outputs of the first and second flip-flop circuits 11c and 11d in Fig. 9. (g) shows pulses in (e) and (f). It represents the compensation voltage for one track according to the signal. On the other hand, when the actuator is not sufficiently accelerated or when the speed of the actuator is reduced due to deceleration, an error due to the distortion of the disk may occur, and the signal shown in (h) is for the prevention thereof.

11 is a speed timing chart in the positioning operation according to the present invention, in which the tracking error reference voltage from the first DAC 5 is generated in the T ₁ section representing the initial acceleration or the final deceleration time, and thereby error correction. After the acceleration, an error in the land portion 2A or the groove portion 2b due to the sampling signal is detected and corrected accordingly. In the T ₂ section, as shown in FIG. The clock signal 1 according to 6b) is used, and the clock signal 2 is used in the fast section T ₃ so that corresponding sampling can be performed according to the frequency change of the tracking error signal.

Thus, according to the present invention, the actuator stored in the ROM in advance according to the number of tracks to be moved uses the deceleration data, the data for generating the reference error tracking voltage for position and speed error detection and the time data to be sampled. Although the positioning is performed, the tracking error signal generated as the actuator is accelerated is sampled each time it passes the land or groove, and the position and speed error are corrected for each track movement. Not only can it reach the target position accurately, but also it does not use separate position and speed sensors such as linear encoders, so the circuit configuration is simple and the cost increase factor can be eliminated. .

Claims (6)

An optical disc apparatus for recording information on a disc having an uneven track structure or reproducing the recorded information, comprising: processing means (3) for receiving movement track information and controlling each means accordingly; Storage means (4) for storing an acceleration, deceleration voltage data, data for a sampling time, a tracking error reference voltage data, and the like for detecting an error according to a track to be moved; Tracking error reference voltage generating means (5) for reading data stored in said storage means (4) to generate a tracking error reference voltage at the time of initial acceleration and deceleration termination under the control of said processing means (3); Sampling signal generating means (6) for generating a sampling signal for reading data stored in said storage means (4) and sampling a tracking error after acceleration of the actuator under the control of said processing means (3); An actuator drive signal generation means (7) for reading data stored in said storage means (4) under the control of said processing means (3) and generating acceleration and deceleration signals according to the number of moving tracks; First adder means (8) for adding a tracking error signal and a tracking error reference signal from said tracking error reference voltage generating means (5); S & H circuit means (9) for receiving the output signal from the sampling signal generating means (6) and for holding for a predetermined time after sampling the output signal from the first adder means (8); Phase compensation circuit means (10) for compensating the output signal from said S & H circuit means (9) to a predetermined phase; One track compensation circuit means (11) for comparing and detecting whether an error occurs every one track movement, and for generating a compensation voltage when an error occurs; Switching circuit means (12) for receiving an acceleration / deceleration signal corresponding to the number of movement tracks from the actuator drive signal generation means (7) and for selecting an input target point of the signal; Connected to each output side of the actuator driving signal generating means 7, the phase compensating circuit means 10, and the one track compensating circuit means 11, and adding each output signal therefrom to drive the actuator for fine driving; Two adder means 13; And a third adder means (14) connected to the switching circuit means (12) for receiving the output signal from the actuator drive signal generating means (7) to drive the coarse drive actuator. High speed positioning servo system of disk device. 2. The sampling signal generating means (6) according to claim 1, characterized in that the sampling signal generating means (6) comprises: clock signal generating means (6a) for generating a clock signal corresponding thereto as the frequency of the tracking error signal increases, and clocking from the clock signal generating means (6a). A divider means 6b for dividing a signal, a switching circuit means 6c for selectively transmitting only one of the clock signals divided by the divider 6b, and an alternative clock signal from the divider 6b A high speed positioning servo system of an optical disc apparatus, comprising: a counter means (68) for counting. 3. The data according to claim 1 or 2, wherein the data for the count value stored in the storage means 4 is a time interval passing by the land portion or groove portion of the track of the optical beam, and the counter means of the sampling signal generating means 6 68. A high speed positioning servo system for an optical disc apparatus, characterized in that it is adapted to apply. The method according to claim 2, wherein after the counter in the counter means 6g is terminated, a data request signal for requesting the loading of data to be counted is subsequently sent from the counter means 6g to the processing means 3. A high speed positioning servo system for an optical disk device, characterized in that. 3. The high speed position of the optical disc apparatus according to claim 2, wherein an enable signal for enabling the switching circuit means 6c is applied to the circuit means 6c when the actuator is accelerated at a predetermined speed or more. Setting servo system. 2. The zero-crossing detection circuit means (11a) according to claim 1, wherein the one-track compensation circuit means (11) inputs a tracking error signal to generate a pulse signal for each track movement. A first comparison means 11c connected to each output side of the delay means 11b, the zero crossing sensing circuit means 11a, and the delay means 11b for delaying by as much as one track. Second comparing means (11d) and the first comparing means (11c), which are connected to each output side of the zero crossing sensing circuit means (11a) and the delay means (11b) to compare whether or not they have moved as much as one track. The first reference time setting means 11e and the first reference voltage generating means 11f for generating a compensation voltage when it is moved by one track less than the output side of the second track, and the output side of the second comparing means 11d. Connected to 1 track Than the second reference high-speed positioning servo system of the optical disk device comprises a time setting means (11g) and a second reference voltage generating means (11h) for generating a compensation voltage at the time when a lot of movement.