JPH02257479A - Seek control method for optical disk device - Google Patents

Abstract

PURPOSE:To eliminate necessity to execute correction once more after seek operation is once executed and to shorten a seek time by using a value, for which track difference is corrected by the error of a moving track number, as a prescribed value. CONSTITUTION:The seek time is forecasted from difference between a track number 7a of a purpose track and a track number 4a, in which an optical spot SPT is positioned when the seek operation is started, namely, from the value of track difference 7b and the number of final sectors, through which the optical spot SPT is passed during the seek operation, is calculated. This value is added to the track difference 7b as a value 9a, which is the error of the moving track number, and a moving track number 10a is calculated. Then, this value is used as the track number 10a to be crossed at the time of the seek operation. Thus, an opportunity that the correction operation has to be executed again is almost eliminated and the seek time can be shortened.

Description

[Detailed description of the invention]

[Industrial Application Field] The invention of the present invention counts the number of track crossing signals generated when a light spot crosses a track on the recording surface of an optical disk, and continues to move the spot until the count value reaches a predetermined value. This relates to a method for setting the predetermined value, that is, the number of trunks to be traversed, in an optical disk device that moves and performs a seek operation.In particular, when the optical disk has a spiral track, the optical disk is moved during a seek operation. The present invention relates to a seek control method for setting a seek amount in consideration of errors caused by rotation. Main application cylinder 2. The third invention controls the head driving device so that the moving speed of the optical head follows a predetermined speed command during a seek operation, and more specifically,
The second invention corrects the drive stroke characteristics of the head drive device even if the drive stroke characteristics are not flat, or even if the head drive device has individual deviations from the standard value of the drive characteristics. Further, the third invention relates to a seek control method capable of performing a stable seek operation, and furthermore, a third aspect of the present invention is to control the drive characteristics of the head drive device depending on the seek direction of the optical head (outer circumference-inner circumference direction, inner circumference-outer circumference direction of the optical disk). The present invention relates to a seek control method capable of correcting the difference and performing a stable seek operation. Note that in the following figures, the same reference numerals indicate the same or corresponding parts. [Prior Art] Conventionally, in order to perform a seek operation in an optical disk device, that is, an operation for moving a light spot projected onto the recording surface of an optical disk to a designated target track, an optical head drive device and an optical head each have a A method is used in which a so-called coarse seek operation is performed in which general positioning is performed using a provided external scale and an external scale sensor, and a fine seek operation is performed in which the destination track is reached through more detailed control from the point reached by the coarse seek operation. It was getting worse. However, this method has poor coarse seek accuracy because the accuracy of the external scale is coarse compared to the track spacing, so a fine seek operation is always required, resulting in a long seek time. There have been problems such as the auxiliary circuit being a negative factor in reducing the size and price. For the above reasons, methods have recently been implemented that utilize a tracking error signal used for tracking control without using an external scale. This method takes advantage of the fact that a track error signal changes to a track crossing signal during a seek, and counts this track crossing signal, and then continues scanning until the count value becomes equal to the number of tracks to be crossed to reach the destination track. It moves the spot. This method will be explained using FIG. 7. FIG. 7 is a block circuit diagram showing the configuration of a portion related to track seek control of a conventional optical disc device. In FIG. 7, reference numeral 1 denotes an optical disk on which information is recorded on a large number of tracks on the recording surface, 2 an optical head for reading or writing information on the recording surface of the rotating optical disk 1, and S.
PT is a light spot focused on the optical disk recording surface by the projection light from the objective lens (not shown) of the optical head 2;
is a head drive device that moves the optical disc 2 in the radial direction of the optical disc 1, that is, in the direction across the tracks on the recording surface of the optical disc 1. Further, 4 is an ID detection circuit that recognizes and outputs the track number 4T and safeter number 4S from the preformat data 2a on the track read by the optical head 2, and 5 is an ID detection circuit that detects the track crossing signal 2b sent from the optical head 2. A track count circuit 6 counts and recognizes the number of tracks 5a crossed by the optical spot SPT and outputs the same. 6 detects the track crossing speed of the optical spoiler SPT based on the track crossing signal 2b and outputs it as a head speed value 6a. 7 is the track number 7a of the target track given from a host computer (not shown), and the original track number detected by the ID detection circuit 4 and on which the light spot SPT is located at the time of starting the seek operation. 4a (hereinafter referred to as track difference); 11 is a track difference calculating circuit that calculates the difference between the track difference and the optical spoiler (hereinafter referred to as track difference); The desired speed at that point in time is calculated from the value 5a of the number of tracks to be crossed sent from the track count circuit 5, and this calculated value is compared with the actual speed obtained from the speed detection circuit 6 to move the light spot SPT to the optimum speed. Optical head 2 to control at once
A control signal 11a for controlling the drive current of the head drive device 3 so that the head moves following the above-mentioned speed pattern.
This is a speed control circuit that sends the information to the head drive device 3. Thus, the track difference calculation circuit 7 and the speed control circuit 11 constitute a head drive control device 20. In FIG. 7, when the track difference calculation circuit 7 is given a target track number 7a from a host computer (not shown), the track difference calculation circuit 7 receives the given target track number 7a and the light sent from the ID detection circuit 4. Spot SP
The difference between T and the track number 4T (or original track number 4a) where T is located at that time is calculated, and the value is output as a track difference 7b, which is sent to the speed control circuit 11. The speed control circuit 11 sets the speed pattern that the optical spot SPT should follow during the seek operation, that is, the relationship between the number of tracks crossed by the optical spot SPT and the desired speed at that point, according to the value of the track difference 7b. do. Then, the speed control circuit 11 determines the desired speed at that point based on the number of tracks crossed by the light spot SPT sent from the track count circuit 5 and the speed pattern, and uses this value and the actual speed value obtained from the speed detection circuit 6. 6a, a control signal 11a for controlling the speed of the optical head 2 according to the set speed pattern is sent to the head driving device 3, and the optical head 2 is moved. In this way, when the light spot moves by the value of the track difference, that is, the value of the difference between the track number of the target track and the track number of the track where the light spot SPT was initially located, the indicated speed obtained from the speed pattern is It becomes zero and the seek operation ends. In this case, in order to finely adjust the stop position at the final stage of the seek operation, in addition to controlling the head drive device 3, a fine adjustment function of the light spot SPT provided in the optical head is also used. According to the above method, the precision is poor and the size is small. Seek operations can be performed without using an external scale and external scale sensor, which have been an impediment to lower prices.

[Problem to be solved by the invention]

When using the conventional seek method described above, when an optical disc has spiral tracks, the number of tracks to be moved may not match the track difference value described above because the optical disc is rotating during the seek operation. First, there is the problem that correction may be necessary. The necessity of this correction value (hereinafter referred to as movement track number error) will be explained using FIG. 8. FIG. 8 is an explanatory diagram showing an example of tracks formed in a spiral shape on the recording surface of an optical disc and an arrangement of sectors placed on each track. In Figure 8, T is the track number, S is the sector number,
SPT indicates the position of the light spot. The track number T is written on the optical disc 1 on one spiral track.
In this example, each lap is one track, and in this example, the numbers are increased one by one from the inside to the outside.
Further, sector numbers S are assigned as sector numbers 0 to 16 to sectors obtained by dividing each track into 17 equal parts in this example. It is also assumed that the disk rotates clockwise and that the optical spot SPT is on track n, sector 15 before the optical spot is moved, as shown in FIG. 8(1). If you try to move (seek) the optical spot SPT one track inward in this state, no error will occur if you can move it to track n-1, but as shown in Figure 8 (2), the last sector (sector 16), it means that it has not moved onto track n. In other words, it has not moved even one track, and in this case 2 tracks have not been moved.
If you do not move (seek) inside one track, it does not mean that you have moved (seek) one track inside. On the contrary, if you try to move (seek) the optical spot SPT outward by one track, and the optical spot SPT passes through the last sector while moving, the optical spot will move only one track. If you look at the track number, it means that you have moved two tracks. This difference occurs each time the optical sub-SPT passes the final sector during a seek operation, so there is a difference between the number of tracks to be moved during a seek operation and the track difference described above. An error equal to the number of final sectors passed during operation, that is, the above-mentioned error in the number of moving tracks will occur. In the conventional seek method, the above-mentioned track difference is given as the seek amount, so when the first seek is completed, the optical head reads the currently located track number and calculates the error from the target track number, that is, the moving track. It is necessary to perform a correction operation by the value of the numerical error, and the total seek time increases accordingly. By the way, the drive characteristic of the head drive device 3, that is, the relationship between the drive force and the stroke, has a shape as shown in FIG. 9 when the value of the drive current is constant, and has a relatively flat characteristic. Except for the central SF section, the drop in driving force tends to be steeper at both ends.Therefore, even if the same drive current is passed through these end portions, the same driving force as at the center cannot be obtained. Therefore, in the conventional device, only the central SF section, where a nearly constant driving force can be obtained, is used in the driving force characteristics of the head driving device 3.However, in this method, both end portions of the stroke of the head driving device 3 are used. For example, if you want to use the entire recording surface of an optical disk, you will have to increase the size of the head drive device.Furthermore, even if the same amount of current is passed through the head drive device 3, the Depending on the drive direction (from the outer circumference to the inner circumference of the optical disc, or from the inner circumference to the outer circumference), there is a difference in the driving force generated by an external force such as a cable connecting the head drive device 3 and the head drive control device 2o. The circuit characteristics of the device 3 may differ depending on the direction in which the drive current flows, so even if the same control value is given by the control signal 11a, a difference may occur in the drive force.This is because the drive current shown in Fig. 9 is constant. There are nothing but two characteristic curves representing the relationship between the driving force and the stroke in the case where the driving direction of the optical head 2 is used as a parameter.Furthermore, the driving characteristics of the head driving device 3 are different for each head driving device. Since there is some deviation individually, speed control circuit 1
Even if a control value is given so as to follow the speed pattern set by No. 1, the intended driving force cannot be obtained due to the individual deviations in the driving characteristics, and especially at the end of the seek operation, the tracking operation starts. The operation at the very end may become unstable and the seek may fail. SUMMARY OF THE INVENTION Therefore, the present invention provides a seek control method for an optical disk device that does not require further correction operation after the first seek operation is completed even when the above-mentioned error in the number of moving tracks occurs, and also provides a drive control method for a head drive device. Even if the force characteristics are not flat or depend on the seek direction,
In addition, even if each head drive device has individual deviations from the standard values of drive characteristics, it is possible to correct these and perform stable seek operations, and further corrections can be made after the first seek operation. An object of the present invention is to provide a seek control method for an optical disk device that does not require the following steps.

[Means to solve the problem]

In order to achieve the above-mentioned object, in the first invention of the present application, a light spot (SP
A track crossing signal (
2b), and performs a seek operation by moving the optical spot until the count value reaches a predetermined value (number of moving tracks 10a), the track number (7a) of the target track and the optical spot are The track number (
4↑, 4a) is calculated as the track difference (7b), and based on the value of this track difference, the expected seek time ( 8a), and based on this expected seek time and the sector number (4S) where the light spot was located at the start of the seek operation, the number of final sectors that the light spot passes through during the seek operation is calculated as the number of tracks moved. The error (9a) is obtained, and the value obtained by correcting the track difference by the moving track number error is set to 1 so that the value is used as the predetermined value. Further, in the invention of the present invention, the means (ID detection circuit 4, track count circuit 5, speed control circuit 11, speed detection circuit 6, etc.) for recognizing the position and moving speed of the optical head (2) during the r-seek operation is provided. and so that the moving speed of the optical head follows a predetermined speed command,
Head driving bag? ! (3) Head drive control means (50
) A seek control method for an optical disk device comprising at least , It is assumed that a learning operation is performed to eliminate deviations from the optimal control state based on differences in the individual drive characteristics of the head drive devices, and based on the results, the coefficient k is corrected by multiplying the ratio by 1 or the like. Furthermore, in the third aspect of the present invention, the control value is multiplied by a predetermined correction coefficient (ko) corresponding to the seek direction of the optical head to correct the difference in the driving force of the head driving device depending on the seek direction of the optical head. shall be taken as a thing.

[For use]

In the invention of the present invention, the seek time is predicted from the difference between the track number of the target track and the track number where the optical spot is located at the time of starting the seek operation, that is, the value of the track difference (7b), and this predicted seek time is calculated from the value of the track difference (7b). The number of final sectors that the light spot passes during the seek operation is calculated based on the time and the sector number where the light spot was located at the start of the seek operation, and this value is used as the value of the moving track number error (9a) to determine the track difference. In addition to (7b), the number of moving tracks (10
a) and use this value as the number of tracks that the light spot should traverse during a seek operation. Therefore, since the correction value has already been included in this number of moving tracks, -
There is almost no need to check the track number after movement after performing a degree seek operation and perform another degree correction operation, and the seek time can be shortened. Further, in the invention of the present cylinder 2, the control value correction means (12) is provided between the head drive control means (50) and the head drive bag W (3), and the control value correction means (12) is provided between the head drive control means (50) and the head drive bag W (3), so that the control value correction means (12) is provided between the head drive control means (50) and the head drive bag W (3). A control correction value (such as 128), which is obtained by multiplying a control value (such as 11a) output from the head drive control means by a correction coefficient according to the stroke position of the head drive device, is applied to the head drive device so as to obtain a driving force according to the stroke position of the head drive device. (3
). Further, a correction coefficient learning means (13) is provided, and learning data (
13a) is sent to the control value correction means to correct the correction coefficient. In addition, in the invention of the present application cylinder 3, a control value correction means (14, etc.) is provided between the head drive control means (50) and the head drive device (3), and when the target track number 7a and the seek operation are started, The seek direction is determined from the track number 4a where the light spot is located, and in order to obtain the intended driving force of the head drive device in that seek direction, a correction coefficient is determined according to the seek direction of the head drive device. A control correction value (correction control signal 14a, etc.) obtained by multiplying the control value (11a, etc.) output from the head drive control means is sent to the head drive device. As a result, even if the drive stroke characteristics of the head drive device are not flat or the drive force is dependent on the seek direction, the entire stroke range of the head drive device can be used effectively, and the drive force of each head drive device can be used effectively. Even if there is a difference in characteristics, it is possible to correct this and perform a stable seek operation.

【Example】

Next, the first invention of the present application will be explained in detail using FIG. FIG. 1 is a block circuit diagram showing the configuration of a portion related to trunk seek control of an optical disk device as an embodiment of the present invention, and corresponds to FIG. 7. In the following explanation, the differences from FIG. 7 will be mainly explained. In FIG. 1, when the track difference calculation circuit 7 is given a target track number 7a from a host computer (not shown), the track difference calculation circuit 7 converts the given target track number 7a and the ID detection circuit 4 into preformat data 2a. and the track number (original track number 4a) on which the light spot SPT is located at that time is calculated, and the value is output as a track difference 7b, which is sent to the seek time prediction circuit 8 and the movement It is sent to the track number calculation circuit 10. The seek time prediction circuit 8 calculates the track difference 7b.
The seek time is predicted based on the speed pattern of the optical spot SPT that is set according to the value of , and the predicted seek time is sent to the moving track number error calculation circuit 9 as the expected seek time 8a. The moving track number error calculation circuit 9 holds the number of revolutions per minute of the optical disc 1 as a constant, and uses this number of revolutions and the expected seek time 8a to calculate the number of rotations of the optical disc 1 during the expected seek time.
Calculate the number of revolutions at which the light spot SP rotates, and use this number of revolutions and the detection circuit 4 to detect the light spot SP.
Based on the sector number 4s in which the optical spot SPT was located, the number of final sectors that the optical spot SPT passes through during the seek operation is calculated as a moving track number error 9a, and this is sent to a moving track number calculation circuit 10. This moving track number error 9a
is calculated so that a correct correction value is obtained when added to the track difference 7b, that is, the sum of the track difference 7b and the moving track number error 9a is the number of trunks that the light spot SPT should cross during the seek operation. Add a positive or negative sign so that Whether the moving track number error 9a should have a positive or negative sign is determined by four conditions: the spiral direction of the tracks on the optical disc, the arrangement of track numbers and sector numbers, and the rotational direction of the optical disc. Once the above-mentioned conditions of the apparatus are determined, the sign to be attached to the moving track number error 9a will also be determined accordingly. For example, as shown in Figure 8, the optical disk rotates clockwise, the track spiral rotates counterclockwise, the track numbers are assigned increasing numbers from the inside to the outside, and the sector numbers are assigned increasing numbers counterclockwise. In an optical disk drive/device, when moving one track inward, the track difference is -1 if the target track number is n-1 and the current track number is n. , the actual number of tracks to be traversed must be -2, so the correction value is -1. Also, when moving to the outside of the track, set the destination track number to n+1. If the currently located track number is n, the track difference is +1, but if the light spot passes through the final sector while moving, the actual number of tracks to cross must be O, so the correction value is still −l. That is, in this case, the sign to be attached to the moving track number error 9a is negative. In this way, the moving track number error calculation circuit 9 is set from the beginning to give a positive or negative sign to the moving track number error 9a so that the correct number of moving tracks can be obtained according to the above four conditions of the optical disc device. has been done. Next, the moving track number calculation circuit 1O adds the track difference 7b and the moving track number error 9a, and sends the result to the speed control circuit as the moving track number 10a. The speed control circuit 11 sets a speed pattern that the light spot SPT should follow during the seek operation according to the value of the number of moving tracks 10a, and determines the number of tracks that the light spot SPT traverses sent from the track count circuit 5 and the speed. The desired speed at that point is determined based on the pattern, this value is compared with the actual speed obtained from the speed detection circuit 6, and a control signal 11a is sent to the head driving device 3 to move the optical head 2 and therefore the optical spot SPT. let Then, the optical spora) SPT traverses the track by the value of the number of moving tracks 10a and stops. In other words, the number of tracks crossed by the optical spot SPT is determined by the track difference between the target track and the track where the optical spot was located at the start of the seek, and the correction for the error in the number of moving tracks and links caused by the rotation of the optical disc 1. Since the value is obtained by performing the following, the size of the seek amount in the seek operation,
Also, regardless of the seek direction, the correct amount of movement is always given, and the seek operation can be performed quickly. In this optical disc device, the above-mentioned track difference calculation circuit 7. Seek time prediction circuit 8. Movement track number error calculation circuit 9. A head drive control circuit 50 is composed of the moving track number calculation circuit 10 and the speed control circuit 11. Next, the second invention of the present application will be explained in detail using FIGS. 2 and 3. FIG. 2 is a block circuit diagram showing the circuit configuration of a seek control device for an optical disk device as an embodiment to which the second invention is applied, and corresponds to FIG. 7. Further, FIG. 3 is an explanatory diagram showing an embodiment of the learning operation in the present invention. In the following explanation, the differences from FIG. 7 will be mainly explained. In FIG. 2, 12 is a control value correction circuit provided between the head drive control device 50 and the head drive device 3, and the control value correction circuit 12 is as shown in FIG. When the driving car has a stroke characteristic, each stroke position (note that each stroke position is The ratio k between the drive current value l necessary to produce this reference drive force PO and the drive current value 1o described above is calculated as a correction coefficient at each stroke position. The head drive control device 5
0 is the difference between the ring track number 4a and the cross track number 58 (
The control correction value 1 is calculated by multiplying the control value 11a by the correction coefficient k corresponding to the head position value 4T (i.e., the track number on which the optical head 2 is located at that time) to be sent as
2a to the head driving device 3. On the other hand, when calculating the control value 11a, the head drive control device 50 is configured to use the characteristics at the reference stroke position SO described above as the relationship between the drive force and drive current of the head drive device 3. By multiplying the control value 11a by the correction coefficient k in the control value correction circuit 12, the intended driving force can be obtained at all stroke positions of the head drive device 3, and the head drive device 3 can effectively use the entire stroke range. It can be used for. In this case, the value of the coefficient in the correction coefficient table that the control value correction circuit 12 initially has is a standard value calculated for the standard drive stroke characteristic of the head drive device 3, and each head drive device Since there are some individual errors with respect to the standard characteristics, if the standard values are used as the correction coefficients, it is possible that the control state will deviate slightly from the optimal control state. For this reason, a correction coefficient learning circuit 13 is provided in FIG. This correction coefficient learning circuit 13 takes in and analyzes the control correction value 12a, corrects the control correction value 12a so as to obtain the optimum control state for the unique characteristics of the head drive device 3, and uses the result as learning data. 13a to the control value correction circuit 12. The control value correction circuit 12 corrects the value of the coefficient in the corresponding part of the correction coefficient table based on the learning data 13a, and the next time a similar control command comes, this corrected coefficient k is used to adjust the head Controls the drive device 3. Next, the learning operation of the correction coefficient learning circuit 13 during constant acceleration control will be explained using FIG. To simplify the explanation, the control value 11a is assumed to have three levels: a constant acceleration control value A, a control value H greater than the constant acceleration control value, and a control value smaller than the constant acceleration control value. In the sampled stroke section, if the control value 11a set by the head drive control device 50 is larger than the optimum value for the actual device, in order to maintain the given speed pattern, that is, constant acceleration, The drive output, that is, the control correction value 12a, has a form in which there are many periods where the control value is equal to the control value, as shown in FIG. 3(1). Based on this result, the correction coefficient learning circuit 13 performs constant acceleration control as shown in FIG. 3 (2) so that the period in which the control value H is output is equal to the period in which the control value H is output. The value of value A is lowered overall to control value B. Then, the control value correction circuit 12 sets the learning data 13a of the stroke section in which the ratio of the control value B and the control value A is 1 as sampled.
send to The control value correction circuit 12 further multiplies the correction coefficient k of the sampled stroke section by the ratio kl to correct the correction coefficient table. Therefore, when similar control is performed in the same section next time, it is possible to obtain a drive output result that maintains a substantially constant acceleration control value as shown in FIG. 3 (3). By repeating the learning operation in this manner, the coefficients of the correction coefficient table are corrected over the entire stroke range, making it possible to perform optimal control for the unique characteristics of the head drive device 3. Next, the invention of the cylinder 3 of the present application will be described in detail with reference to FIG. FIG. 4 is a block diagram showing a circuit configuration of a seek control device of an optical disk device to which the third invention is applied. In FIG. 4, 14 is a control value correction circuit provided between the head drive control device 50 and the head drive bag y13. When the drive force of the head drive device 3 has seek direction dependence, the control value correction circuit 14 adjusts the drive current value to 1o, for example.
Based on the theoretical value Po of the driving force obtained by Memorize the ratio and select the track number 4 where the light spot SPT was located at the start of the seek.
The seek direction is determined from a (original track number) and the target track number 7a, and the control value included in the control signal 11a output by the head drive control device 50 is multiplied by a correction coefficient (ko) corresponding to this seek direction. correction control signal 14a
is created and output to the head driving device 3. Next, a method for obtaining the above correction coefficient ko by test seek using the apparatus shown in FIG. 4 will be explained with reference to FIG. 5. FIG. 5 is an explanatory diagram for explaining how to find the ratio between the actual value and the theoretical value of the driving force of the head driving device in the seek direction. In the test seek, the head 2 is driven at a constant speed Vo, irrespective of the speed profile, decelerated by a constant control value (without correction), and the time required from the start of deceleration until the head 2 stops is determined. This test seek is performed in two directions, from the outside to the inside and from the inside to the outside of the optical disc. In Fig. 5, the solid line is the velocity waveform obtained by test seek, and the dashed line is the theoretical velocity waveform.The actual value P and theoretical Po of the driving force are respectively P = V
o/t------
(1) P=Vo/lo −・−・
It is expressed as (2). FIG. 5 shows a case where the actual driving force value is larger than the theoretical value of the driving force for a constant driving current value. Assuming that the control value output by the head drive control device 50 is an acceleration control value (therefore, a drive current value),
A correction coefficient ko for correcting the seek direction dependence of the head drive by correcting the control value output by the head drive control device 50 is as follows: ko = Po / P = t / t o
−−−−−−− It is determined by (3). In FIG. 4, a correction coefficient calculation circuit 15 is provided between the head drive control device 50 and the control value correction circuit 14, and during the above-mentioned test seek, the head drive control device 50 outputs the output of the speed detection circuit 6. It takes in the head speed value 6a and outputs the test seek start speed Vo to the correction coefficient calculation circuit 15, and at the same time as the start of deceleration starts time measurement using the built-in timer, and from the start of deceleration, the speed detection circuit 6
The time taken until the output of 1 indicates speed 0 is measured and outputted to the correction coefficient calculation circuit 15 as the test seek deceleration time t. The correction coefficient calculation circuit 15 calculates the above correction coefficient kO from the test seek deceleration time t and the theoretical value to of the deceleration time for each seek start speed Vo inputted in advance, and sends the calculation result to the control value correction circuit 14. The control value correction circuit 14 stores the correction coefficient kO, and when performing head drive control, uses the stored correction coefficient kO to correct the control value output by the head drive control device 50. A correction control signal 14a is created and output. Next, a device applied to seek control that makes it possible to correct head position dependence, seek direction dependence, and individual differences in head drive force of the head driving device will be described with reference to FIG. 6. FIG. 6 shows the first part of the present application. FIG. 3 is a block diagram showing the configuration of an apparatus that simultaneously implements the second and third inventions and performs seek control. The head drive control device 50 performs the same function as the head drive control device shown in the first figure, and the device shown in the sixth figure is applied to the seek control of the first invention of the present application, which corrects the moving track number error in advance. It is something that will be done. Then, the correction control circuit 14 described in detail of the third invention and the correction control circuit 12 described in detail of the second invention are provided between the head drive control device 50 and the head drive control bag y13,
A correction coefficient learning circuit 13 is connected to the correction circuit 12. The correction control circuit 14 has target track numbers 7a and I
The head position value 4T (the track number where the head is currently located) output from the D detection circuit 4 is input, and the seek direction is determined from this target track number 7a and the head position value 4T and is stored in advance. Control signal 1 in which the head drive control device 50 outputs a correction coefficient ko according to the seek direction
The control value is corrected by multiplying it by the control value included in 1a to create a correction control signal 14a and output it to the correction control circuit 12. The head position value 4T output from the ID detection circuit 4 is input to the correction control circuit 12 via the head drive control device 50, and the correction control circuit 12 receives a pre-stored head position corresponding to this head position value 4T. The correction control signal 14a is corrected by the correction coefficient k corrected by the correction coefficient k of the control value according to the correction coefficient k or the correction ratio based on the learning data 13a input from the correction coefficient learning circuit 13, and the control correction value 12a is created and output to the head driving bag W,3. In addition, in FIG. 6, the correction coefficient calculation circuit 15 shown in FIG. 4 is omitted, but the correction coefficient calculation circuit 15 is
It can be connected to the illustrated control value correction circuit 14 as appropriate.

【Effect of the invention】

In the invention of the present invention, the number of track crossing signals generated when an optical disk having a spiral track is crossed by a light spot projected from an optical head is counted, and the number of track crossing signals is counted until the count value reaches a predetermined value. In an optical disk device that performs a seek operation by moving a light spot, the difference between the track number of the target track and the track number where the light spot is located at the start of the seek operation is calculated as a track difference, and this track difference is Based on the value of , the seek time from when the optical head starts its operation until it reaches the target track is calculated as the expected seek time, and this expected seek time and the position of the optical spot at the start of the seek operation are calculated. Based on the sector number, the number of final sectors that the light spot passes during the seek operation is calculated as the moving track number error, and the value obtained by correcting the track difference by the moving track number error is used as the predetermined value. The predetermined value is a value that has already been corrected for the error in the number of moving tracks that occurs due to the rotation of the optical disk, and after performing a -degree seek operation, the track number after movement is checked, and the seek operation for the -degree correction is performed again. This makes it possible to shorten the seek time. In addition, in the invention of the present invention, there is a means for recognizing the position and moving speed of the optical head during the seek operation, and a means for recognizing the position and moving speed of the optical head during the seek operation. Seeking of an optical disk device comprising at least a head drive control means for outputting a control value for controlling a drive current of a head drive device so that the movement speed follows a speed command predetermined according to a target seek amount. When controlling,
Since the control value is multiplied by a predetermined coefficient k depending on the position of the optical head to correct the difference in the driving force of the head driving device depending on the position of the optical head, the driving stroke characteristics of the head driving device are not flat. Even if the head drive device is small, the entire stroke range of the device can be used effectively. In addition, learning operations are performed to eliminate deviations from the optimal control state based on differences in the individual drive characteristics of the head drive devices.
Since the ratio obtained based on the result is multiplied by 1 by the coefficient k to create a new coefficient, even if the drive car stroke characteristics of the head drive device have a slight error in each device, the It is possible to perform optimal control according to the characteristics of the object, and to reduce the probability that the control operation will become unstable and seek failure will occur. Further, by automatically correcting the correction coefficients through the learning operation, the time and effort required for setting and correcting the coefficient values can be significantly reduced. Furthermore, in the third invention of the present application, a control value correction means is provided between the head drive control means and the head drive device, and the target track number and the track number on which the light spot is located at the start of the seek operation are determined. Since the direction of the seek is determined from the direction of the seek, and the control value outputted from the head drive control means is multiplied by a correction coefficient corresponding to the direction of the seek, the control correction value is sent to the head drive device, so that the head position after the seek operation is The need for re-correction is reduced, allowing stable and quick seek operations. Then, the first part of the present application. The second and third inventions are simultaneously applied to a seek control device of one optical disk device to realize a more stable and rapid seek operation.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing the configuration of a portion related to seek control of an optical disk device as an embodiment to which the first invention of the present application is applied, and FIG. 2 is an optical disc as an embodiment to which the second invention of the present application is applied. A block circuit diagram showing the configuration of a part related to seek control of the device, FIG. 3 is a diagram showing an embodiment of the learning operation in the second invention, and FIG. 4 is an optical disc device as an embodiment to which the third invention of the present application is applied. FIG. 5 is a speed waveform diagram for explaining how to obtain the driving force correction coefficient in the third invention, and FIG. A block circuit diagram showing the configuration of a portion related to seek control of an optical disk device as an embodiment to which the invention and the third invention are simultaneously applied, FIG. 7 corresponding to FIGS. 1, 2, 4, and 6. A block circuit diagram showing a conventional configuration, No. 8
The figure is an explanatory diagram showing an example of the arrangement of spiral tracks formed on the recording surface of an optical disk and sectors provided on each track. Figure 9 shows a head drive device in which the drive current is set to a constant value. It is a characteristic diagram which shows an example of the relationship between the driving force and a stroke when it does. 1: Optical disk, 2: Optical head, 2a; Preformat data, 2b = Track crossing signal, 3: Head drive device, 4: ID detection circuit, 4a; Original track number,
4T Nitrack number, 4S: Sector number, 5 Nitrack force count circuit, 6: Speed detection circuit, 6a: Head speed value, 7: Track difference calculation circuit, 7a: Target track number, 7b Nitrack difference, 8: Seek time prediction circuit , 8a: Predicted seek time, 9: Movement track number error calculation circuit, 9a: Movement track number error, 10: Movement track number calculation circuit, 10a: Movement track number, ll: Speed control circuit, 11a: Control signal, 12: Control value correction circuit, 1
2a: Control correction value, 13: Correction coefficient learning circuit, 13a:
Learning data, A: constant acceleration control value before learning, B: constant acceleration control value after learning, H: control value larger than constant acceleration control value, L
: control value smaller than constant acceleration control value, 14: control value correction circuit, 14a: correction control signal, 15: correction coefficient calculation circuit,
KO: correction coefficient, 20.50: head drive control device. (1) Co-op front time brother 3 figure Ryo picture entry herooku figure 9 figure (1) Send stinggut (SPT) Kishimono n own set 7 ri: ljk thought 8 eyes

Claims (1)

[Claims] 1) Counting the number of track crossing signals generated when a light spot projected from an optical head crosses a track of an optical disk having a spiral track, and the count value reaches a predetermined value. In an optical disk device that performs a seek operation by moving the optical spot until , based on the value of the track difference, a seek time from when the optical head starts operating until it reaches the target track is determined as an expected seek time, and the expected seek time and the optical spot are determined at the start of the seek operation. The number of final sectors that the light spot passes through during the seek operation is determined as the moving track number error based on the sector number where it was located at the time of the movement, and the value obtained by correcting the track difference by the moving track number error is calculated as the number of moving tracks. A seek control method for an optical disc device, characterized in that the seek control method is used as a predetermined value. 2) means for recognizing the position and moving speed of the optical head during a seek operation; and means for controlling the drive current of the head driving device so that the moving speed of the optical head follows a predetermined speed command. A seek control method for an optical disk device comprising at least head drive control means for outputting a control value, wherein the control value is multiplied by a predetermined coefficient corresponding to the position of the optical head to control the head drive device according to the position of the optical head. In addition to correcting the difference in the driving force of the head drive device, a learning operation is performed to eliminate deviation from the optimal control state based on the difference in the individual drive characteristics of the head drive device, and the coefficient is corrected based on the result. A seek control method for an optical disk device characterized by: 3) means for recognizing the position and moving speed of the optical head during a seek operation; and means for controlling the drive current of the head driving device so that the moving speed of the optical head follows a predetermined speed command. A seek control method for an optical disk device comprising at least head drive control means for outputting a control value, wherein the control value is multiplied by a predetermined correction coefficient corresponding to the seek direction of the optical head to obtain the control value according to the seek direction of the optical head. A seek control method for an optical disk device, comprising correcting a difference in driving force of a head driving device.