JP2002329335A - Reading controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize that the optimum scale is obtained even though the track pitch of an optical disk is changed. SOLUTION: In a reading operation, when coarse seek is required (yes in S1-6) and specially the previous movement is by the coarse seek (yes in S1-8), the scale correction is carried out (S1-9) so that the arriving position on the next coarse seek comes near the target position in accordance with the number of tracks of difference between the arriving position by the previous coarse seek and the target position. Further, the moving amount for making the arriving position arrive at the target position right after the coarse seek is compared with a specified value, and when it is larger, the scale is corrected so that the moving amount by next fine seek is reduced in accordance with the amount of difference between the moving amount and the specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a CD, DVD, C
The present invention relates to a read control device in a disk reproducing device that reads recorded information from a recording disk such as a DR and a CD-RW.

[0002]

2. Description of the Related Art When reading recorded information in a disk reproducing apparatus, control for moving a pickup from a current position to a target position is performed. However, it is difficult to accurately reach the target position by one high-speed feed. Therefore, the number of tracks from the current position to the target position is obtained from the current address and the target address, and the pickup is moved with relatively low accuracy based on the number of tracks (hereinafter, referred to as coarse seek). Stop the feed and operate the tracking servo to reproduce the signal,
A control of calculating a deviation from the target position, performing feed or return feed again based on the number of tracks, and finally moving the lens to the target position by a lens kick (hereinafter, referred to as fine seek) is performed. This has been done conventionally.

Further, when performing a rough seek, strict movement accuracy is not required. Therefore, conventionally, there is a disk reproducing apparatus which has a scale unique to the apparatus which is not directly related to the track pitch of the optical disk, and uses this scale as a parameter at the time of coarse seek in relation to the number of tracks of the optical disk. For example, there is a device having a mechanism for optically detecting the movement of a pickup using an LED on a slit fixed to a seek axis, and in which a movement distance per detection slit is defined as a fixed value corresponding to the number of tracks. .

FIG. 8 is a flowchart showing a conventional pickup feed control. When a movement command to a target address is received, the current position of the pickup is first detected as an address on the optical disk (S1), and the current address is determined. Then, it is determined whether or not the position is an allowable position as the vicinity of the target address (S2). The determination as to whether or not the vicinity is acceptable is made by selecting a shorter time by comparing the time required to execute the movement command and reach the target position with the time required to continue the tracking state and reach the target position. In other words, as a method of moving the pickup to the target address, an earlier method is selected as compared with a case where the pickup is moved and a case where the pickup is moved by the operation of the objective lens actuator of the pickup without moving the pickup. Normally, if the difference between the address of the current position and the address of the target position is equal to or less than a fixed value, it is assumed to be acceptable.

[0005] If the position is at an allowable position (No at S2), the movement command is terminated. If it is not at the allowable position (Yes in S2), the number of tracks between the current address and the target address is calculated, and it is determined whether or not a coarse seek is necessary (S3). If a coarse seek is required (Yes in S3), the number of tracks is converted to the number of slits on a scale (S3).
4), a coarse seek is executed (S5). If not necessary (S
No. 3) The fine seek is executed and the track is moved by the number of tracks (S6).

[0006]

However, in the conventional recording information reading method, the above-mentioned scale is determined at the time of designing the disk reproducing apparatus or at the time of manufacturing the disk reproducing apparatus. In some cases, the difference may occur between the inner and outer peripheries depending on the deviation from the proper scale or the variation in the track pitch on the optical disc. Therefore, in the movement of the pickup from the current position to the target position in response to the recording information read command, ideally, the step is completed in a total of two movements: one relatively low-precision movement and one high-precision movement But,
There is a possibility that relatively low-precision movement may be performed twice or more, or a high-precision movement may result in a structurally unstable movement amount.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reading control apparatus which solves such a problem and realizes an optimum scale even if the track pitch of an optical disk changes.

[0008]

In order to achieve the above object, the present invention provides a pickup for reading recorded information from a recording disk to obtain a read signal, a driving means for moving the seek of the pickup, and a drive for moving the pickup. A device-specific scale serving as an intermediate medium for setting the amount of movement when performing a seek movement, and moving the pickup with relatively low accuracy using the scale as an intermediate medium. A reading control device for controlling the drive so as to move from the reached position to the target position with high accuracy when the pickup reaches a target position on the recording disk within a predetermined range, wherein the pickup is controlled during a recording information reading operation. When moving with low accuracy, based on the difference between the current position and the target position in units of the scale, In the first reading operation, the scale is corrected so that the current position approaches the target position, and based on the amount moved with high accuracy, in the next reading operation, with high accuracy immediately after moving the pickup with low accuracy. And a scale correcting means for correcting the scale so as to reduce the amount of movement when moving. With this configuration, it is possible to optimize the scale during normal operation, reduce the frequency of repeating low-precision movement, and reduce the amount of movement in high-precision movement. Optimal reading of recorded information from the optical disk used during the recording can be realized.

Further, in the present invention, the scale correction means obtains a scale correction value from a difference between a current position and a target position in units of the scale in the low-precision movement, and determines a predetermined value for the correction value. Weighting is performed based on a function, the correction value is added to a current scale, and the scale is updated. With this configuration, the correction value is set to 0
Can be reduced, and stable convergence can be achieved.

Further, in the present invention, the scale correcting means may move the movement amount with high accuracy immediately after the movement with low accuracy and the movement with low accuracy from the position immediately after the movement with low accuracy. At this time, a difference amount from the movement amount to the originally expected movement position is input, and the difference amount is converted into a unit system of the scale to obtain a correction value of the scale, and the correction value is calculated based on a predetermined function. The correction value is added to the current scale, and the scale is updated. With this configuration, it is possible to reduce the difference between the amount moved with high precision immediately after moving with low precision and the central expected value, so that the position immediately after moving with low precision is originally Since it comes closer to the expected position, high-precision movement becomes faster. Also, by shifting the center expected value in a manner that matches the structural characteristics of the pickup, the range of high-precision movement immediately after low-precision movement can be statistically limited. Become stable.

Further, the present invention is characterized in that a track pitch correcting means for calculating a track pitch on a disk from the corrected scale and correcting the track pitch is provided. With this configuration, when scale correction is performed in low-precision movement or high-precision movement,
By calculating the track pitch on the actual disk from the corrected scale, and correcting the track pitch,
High-precision movement is optimized, and there is no need to measure the actual track pitch on the disk before the recording information reading operation.

Further, the present invention is characterized in that the corrected track pitch is applied again to the next high-precision movement. With this configuration, the corrected track pitch is corrected again, so that optimization in which both the track pitch and the scale are corrected can be performed.

Further, the present invention is characterized in that the correction of the scale is stopped when the difference between the current position and the target position is more than a predetermined amount. With this configuration, since a mechanical abnormality can be detected, it is possible to optimize a scale excluding an abnormal state.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a control system of a disk reproducing apparatus having an apparatus according to an embodiment of the present invention.
Denotes a central processing unit (hereinafter referred to as a CPU) for controlling the entire apparatus, 2 denotes a spindle motor for rotating the optical disk, 3 denotes a pickup for reading information recorded on the optical disk, and the pickup 3 controls an objective lens in a tracking direction. An objective lens actuator 4 for moving in the focusing direction, a drive mechanism 5 for moving the pickup 3 in the seek direction, and a photo sensor 6 are provided. 7, a holding memory in which various information is stored;
Indicates a counter.

A member having a plurality of slits is fixed to a seek shaft of the drive mechanism 5, and the photo sensor 6 detects LED light through the slits. Here, the slit width in each slit is the same, and the interval between adjacent slits is also equal to the slit width.
Then, when the pickup 3 performs the seek movement, the photo sensor 6 detects ON / OFF of the LED light, and the counter 8 counts the number of times of the detection. The position and the moving speed of the pickup 3 are detected based on the count value. The holding memory 7 stores a slit width, the number of tracks of the optical disc per slit (hereinafter referred to as a scale), a track pitch, and the like. If a coarse seek is required, the track from the current position to the target position is stored. The number is converted into the number of slits, and the pickup 3 is controlled to perform seek movement by the number of slits.

FIG. 2 is a flowchart showing a pickup feed control according to an embodiment of the present invention. When a movement command to a target address is received, the current position of the pickup is first detected as an address on the optical disk (S
1-1), it is determined whether or not the current address is at a position allowable as the vicinity of the target address (S1-2). If it is at an acceptable position (No at S1-2), the movement command is ended. Up to this point, (S1) and (S1) shown in FIG.
Same as step 2).

If the position is not at the allowable position (Yes at S1-2), it is confirmed whether or not the scale of the slit has been changed (S1-3). If the scale has not been changed (S1
Then, the number of differential tracks between the current position and the target position is calculated (S1-5). If the scale has been changed (S1
(No. -3), the track pitch stored in the holding memory 7 is corrected (No in S1-4), and the number of difference tracks is calculated (S1-5).

That is, although the details will be described later, the scale of the slit may be corrected in the subsequent control. Correcting the scale means that the track pitch stored in the holding memory 7 and the actual optical disk From the track pitch. what if,
If the fine seek is performed based on the track pitch stored in the holding memory 7 despite the correction of the scale, the movement accuracy from the current position to the target position is not optimal. So, if the scale has changed,
The distance of one slit and the number of tracks included in one slit
The track pitch is calculated from the (measure), and the track pitch stored in the holding memory 7 is updated.

Next, based on the number of tracks obtained as a result of the calculation, it is determined whether or not the coarse seek is necessary again, in other words, whether or not the lens can be moved to the target position only by the lens kick (S1-6). ). If a coarse seek is required (Yes in S1-6), the number of slits is determined from the number of tracks and the scale (S1-7). If the previous movement is not a coarse seek (No in S1-8), the number of slits is determined. The coarse seek is performed based on (S1-10). If the previous movement is a coarse seek (Yes in S1-8), scale correction is performed so as to cancel the originally unnecessary current movement (S1-9). In this scale correction, in order to expedite convergence to an appropriate correction value, when the difference between the arrival position and the target position by the previous coarse seek is large, the addition value (weighting) to the correction value is increased and the correction is performed. The effect is emphasized and added to the previous scale. By such correction, the scale becomes a value obtained by accumulating the correction with respect to the initial scale.

Here, if the difference between the arrival position and the target position is extremely large, mechanical factors such as a gear skipping or a seek device using a stepping motor in the case of the drive mechanism 5 using a DC motor. If so, there is a possibility that the motor loses synchronism or idles, so that it is not reflected in the correction of the scale.

If the coarse seek is not required (No in S1-6), that is, if the target position can be reached by the lens kick, it is determined whether or not the previous seek is a coarse seek (S1-11). If not seek (No in S1-11), fine seek is performed and the lens is kicked to the target position (S1-14). If it is a coarse seek (Yes in S1-11), it is compared with the central expected value.
No. 12), fine seek is performed (S1-14). If smaller, the scale is corrected (S1-13) and the fine seek is performed (S1-14). Here, the central expected value is
The distance from the position reached by the coarse seek to the position expected to be moved by the coarse seek, is defined by a predetermined amount from the target position, and is determined by structural factors.

When performing scale correction, ideally, the difference amount is set so that the light spot of the pickup lands before the target position, in other words, the lens kick immediately after the coarse seek is in the outer circumferential direction of the optical disk. Scale correction with an offset.

After the movement is completed, the address of the pickup 3 is obtained (S1-1), and it is determined whether or not the pickup 3 is located at a position that does not exceed the target address and is allowable as a neighborhood.
If it is acceptable, the process ends. If it is not acceptable, the above operation is repeated (S1-2). Here, when the scale correction shown in (S1-9) or (S1-13) is performed in the previous seek operation, the track pitch is corrected (S1-4). The track pitch and the scale optimized for both the disc reproducing device and the optical disc on which information is recorded can be obtained.

FIG. 3 is a block diagram showing a control system for scale correction when coarse seek is performed. 10 is an adder for obtaining the difference between the current position and the target position, and 11 is a correction based on the difference. Calculation means 12 for obtaining a value and having a weighting function for weighting the correction value, and 12 indicates an adder.

Since the scale stored in the holding memory 7 is fed back to the adder 12 and the correction value from the calculating means 11 is added, the scale is updated whenever the scale is corrected.

FIG. 4 is an explanatory diagram showing an example of scale correction in the case of a coarse seek. In the control of S1-9 shown in FIG. 2, for example, when the number of tracks per slit set as a scale is small in the actual optical disc, the number of slits in the movement control increases. Therefore, before the correction, the pickup 3 reaches a position beyond the target position. Therefore, the difference between the distance from the current position to the arrival position in units of scale and the distance from the current position to the target position is determined, and based on this difference, the arrival position approaches the target position at the next coarse seek. By correcting the scale at the next time, the pickup 3 can reach the vicinity of the target position by one operation at the next rough seek. Thus, it is possible to optimize the scale used for the coarse seek during the normal operation.

FIG. 5 is a graph showing an example of the weighting function. As shown in FIG. 5, when the amount of difference between the arrival position and the target position in coarse seek in units of the scale is input, the correction value is greatly optimized (ideally 0) when the difference is out of range. ).

Here, when adding the difference amount between the arrival position and the target position in units of the scale in the coarse seek to the scale, the time until the convergence to the optimum value depends on the method of obtaining the correction value from the difference to the scale. And stability until convergence becomes a problem. Therefore, as shown in FIG. 3, when the value is close to the optimum value, a correction value by a weighting function to be reduced is added to the immediately preceding scale, and this is newly scaled. become.

FIG. 6 is a block diagram showing a control system for scale correction when fine seek is performed.
22 is a multiplier for multiplying a predetermined conversion constant so as to make the unit system of the difference amount equal to the unit system of the scale, and 23 is a multiplier 22
The arithmetic means having a weighting function for weighting the output of, and 24 denotes an adder.

The adder 20 receives the amount of movement determined from the number of tracks from the arrival position to the target position and the track pitch, and the expected center value.
2 is output. The multiplier 22 converts the difference amount into a unit system of the scale, and further weights the difference value by the calculation means, so that the correction value is output from the calculation means 23.
Further, the scale stored in the holding memory 7 is fed back to the adder 24, the correction value from the calculating unit 23 is added, and the result is stored in the holding memory 7. Therefore, when the movement amount is larger than the central expected value, the scale is updated at any time.

FIG. 7 is an explanatory diagram showing an example of scale correction in the case of a fine seek immediately after a coarse seek. When the target position is reached from the arrival position by the coarse seek to the target position by the fine seek, the movement amount is set based on the number of tracks from the arrival position to the target position and the track pitch stored in the holding memory 7. Based on the difference between the movement amount and the expected center value, the scale is corrected so that the movement amount approaches the expected center value at the next fine seek.

As a result, the position accuracy in the next rough seek is improved, and the time required for the fine seek can be reduced. In addition, by shifting the expected center value in accordance with the structural characteristics of the pickup, the range to be moved in the fine seek immediately after the coarse seek can be statistically limited. Becomes stable.

According to the present embodiment configured as described above,
The following operation and effect can be obtained.

As shown in FIG. 3, when the coarse seek is performed during the normal operation, the scale is corrected using the difference between the track at the arrival position and the track at the target position in units of scale, and FIG. As shown, by correcting the scale using the amount moved by the track kick in the fine seek immediately after the coarse seek, the scale can be optimized during normal operation, and the optical disc used during normal operation can be used. Optimal recording information reading can be realized.

When a correction value obtained based on the difference between the arrival position and the target position in the coarse seek is added to a scale used as a reference of the slit width, a conversion value from the difference is converted into a scale. In some cases, the time until the convergence to the optimum value and the stability until the convergence become a problem. However, as shown in FIG. 5, the difference between the arrival position and the target position in units of the scale in the coarse seek is input. And for the obtained correction value,
Weighting is performed so that it is large when the value is far from the optimal value (ideally 0) and small when the value is close to the optimal value, and the correction value is added to the previous scale to form a new scale. As a result, the convergence time can be shortened and the convergence can be achieved stably.

Further, for a difference between the movement amount of the fine seek immediately after the coarse seek and the preset center expected value, a predetermined conversion constant for matching the unit system of the difference with the unit system of the scale, and an optimum value (ideal value) The correction value is determined by calculating the product value with the output of the weighting function, which is large when the value is greatly deviated from 0) and reduced when the value is close to the optimum value, and this correction value is added to the immediately preceding scale. Then, by having this function as a new scale, the position immediately after moving to the coarse seek can be closer to the position originally expected by the coarse seek. The accuracy with respect to the target position is improved, and the movement of the fine seek becomes faster. In addition, by shifting the center expected value in accordance with the structural characteristics of the pickup, the movement range of the fine seek immediately after the coarse seek can be statistically limited, so that the movement of the fine seek becomes stable.

If the track pitch assumed in advance largely deviates from the actual track pitch on the disk, the track pitch is optimized including the track pitch deviation. Movement of fine seek is not optimized. Therefore, when scale correction is performed in coarse seek or fine seek, the track pitch on the actual disk is calculated from the corrected scale,
By correcting the track pitch, the movement of the fine seek is optimized, and it is not necessary to measure the actual track pitch on the disk before the recording information reading operation.

Further, since the value of the track pitch is updated each time the scale correction is performed, optimization in a form in which both the track pitch and the scale are corrected can be performed.

Further, if the movement is hindered by a mechanical factor in the case of the coarse seek, the arrival position may be significantly closer to the target position, and this result is reflected in the scale. And the scale may not be optimal, but according to the present embodiment, if the difference between the arrival position and the target position exceeds a predetermined amount, it is determined that a mechanical abnormality has occurred. By not reflecting the information, such a mechanical abnormality can be detected, so that it is possible to optimize the scale excluding the abnormal state.

[0041]

According to the present invention configured as described above, the movement amount to be moved from the current position with low precision during operation, and the arrival position by high precision movement immediately after the movement with low precision. With the function of optimizing the scale during normal operation by correcting the scale using the amount of movement from the target position to the target position, it is possible to use a disk playback device for recording disks used during normal operation. Optimal recording information reading can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a control system of a disk reproducing apparatus having an apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating pickup feed control according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a control system for scale correction when a coarse seek is performed;

FIG. 4 is an explanatory diagram showing an example of scale correction when a coarse seek is performed;

FIG. 5 is a graph showing an example of a weighting function;

FIG. 6 is a block diagram showing a control system for scale correction when fine seeking is performed.

FIG. 7 is an explanatory diagram showing an example of scale correction in the case of a fine seek immediately after a coarse seek

FIG. 8 is a flowchart showing a conventional pickup feed control;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Central processing unit (CPU) 2 Spindle motor 3 Pickup 4 Actuator 5 Drive mechanism 6 Photosensor 7 Retention memory 8 Counter 10, 12, 20, 24 Adder 11, 23 Computing means 22 Multiplier

Claims (6)

[Claims] 1. A pickup for reading recorded information from a recording disk to obtain a read signal, a driving means for performing a seek movement of the pickup, and an intermediate medium for setting an amount of movement when the seek movement of the pickup is performed. The pickup is moved with relatively low precision by using the scale as an intermediate medium, and the pickup has reached a predetermined range with respect to a target position on the recording disk by this low precision movement. In case,
A reading control device that performs drive control to move the pickup from the arrival position to the target position with high accuracy, and when the pickup is moved with low accuracy during a recorded information reading operation, a current position using the scale as a unit. Based on the difference from the target position, the scale is corrected so that the current position approaches the target position in the next reading operation, and based on the amount moved with high precision, the pickup is moved with low accuracy in the next reading operation. A scale correction means for correcting the scale so as to reduce the amount of movement at the time of high-precision movement immediately after the movement. 2. The scale correction means calculates a scale correction value from a difference between a current position and a target position in units of the scale in the low-precision movement, and calculates a scale correction value based on a predetermined function. 2. The reading control device according to claim 1, wherein weighting is performed, the correction value is added to a current scale, and the scale is updated. 3. The scale correction means according to claim 1, further comprising: a movement amount to be moved with high precision immediately after said movement with low precision; and a movement amount when said movement with low precision is performed from a position immediately after said movement with low precision. The difference amount from the movement amount to the expected movement position is input, the difference amount is converted into a unit system of the scale to obtain a correction value of the scale, and the correction value is weighted based on a predetermined function. And updating the scale by adding the correction value to the current scale.
The reading control device according to the above. 4. The read control device according to claim 2, further comprising a track pitch correction unit that calculates a track pitch on the disk from the corrected scale and corrects the track pitch. 5. The reading control device according to claim 4, wherein the corrected track pitch is applied again to the next high-precision movement. 6. The reading control device according to claim 2, wherein the correction of the scale is stopped when the difference between the current position and the target position is more than a predetermined amount.