JP2638570B2 - Optical disk information access device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus for reproducing an optical disk having concave and convex pits (phase pits) such as a compact disk, and more particularly to an access control of an optical head.

[0002]

2. Description of the Related Art Information access of a conventional optical disk reproducing apparatus is performed by moving an optical head roughly (highly coarse seek operation) at high speed by a linear motor or a feed screw mechanism for driving the optical disk in a radial direction, and then moving the optical head. This is performed by precisely positioning the information reading beam spot (dense seek operation) by a track jump by an actuator mounted on the objective lens. Here, the closer the arriving track after the first coarse seek is to the target track, the shorter the time required for the fine seek can be, so that the information access time can be shortened. It is also desirable that the time of the coarse seek itself be short. In order to increase the access speed of information, high-speed and accurate transfer control of the optical head is important as described above.

When an optical disk device receives an information access instruction from a higher-level device, the optical disk device calculates a relationship between a logical number of information and a physical position on the optical disk,
Calculate the number of tracks to be moved. For example, taking a CD-ROM which is a CLV system recording as an example, the track number is N, the recording start diameter is r1, the track pitch is p,
Assuming that the information recording linear velocity is lv and the logical information number (total number of frames) is t, the relationship is expressed by the following equation (1).

[0004]

[0005] The linear velocity is defined, for example, in the compact disk (CD) standard to be between 1.2 and 1.4 m / s.

A direct track count (DTC) method using the number of tracks obtained as described above is used to perform coarse seek at the time of information access accurately at high speed.

Next, the method will be described with reference to the drawings.

In the DTC system, a track count signal is counted, speed control is performed according to the number of remaining tracks to a target, and tracking is immediately turned on on a target track to complete a coarse seek. Speed control is
A target target speed profile as shown in FIG. 4 is generated according to the number of remaining tracks to the target, and the speed control is performed by feeding back the difference between the target speed and the actual speed. The target speed profile is often trapezoidal as shown in FIG. This is because if the maximum speed of the optical head is too high, the track count signal will be degraded (if the speed is too high, the objective lens will be shaken too much or the beam spot will pass through a place without pits on the disk, and This is to prevent the quality of the error signal from deteriorating) and prevent an accurate counting operation from being performed. If you are not worried about counting mistakes, use the triangle profile (maximum acceleration,
(Move to maximum deceleration at the intermediate point).

Incidentally, an actual optical disk has eccentricity. When the optical disk is mounted on the spindle motor and rotated, the center of the track circle is shifted (depending on the accuracy of the optical disk itself and the accuracy of the spindle motor and its chucking mechanism), so that the optical head and the objective lens actuator are stationary. Also, the track crosses the beam spot in synchronization with the rotation of the optical disk. Therefore, the track count accuracy may be deteriorated. However, there is no problem if the track count is counted up or down according to the relative movement direction between the track and the beam spot. The relative movement direction of the track and the beam spot can be determined by looking at the phase of the track error signal and the mirror signal (a comprehensive signal of the reproduced sum signal corresponding to the amount of reflected light from the optical disk). However, since the mirror signal is a comprehensive line output of a reproduction signal from the optical disk (reproduction sum signal, a signal of the intensity of the return light output when the beam traces on the track), the movement of the beam is changed as shown in FIG. As shown in a), it cannot be obtained unless the locus is close to the track line.
Therefore, if the moving speed of the optical head in the radial direction increases (assuming the linear velocity of the optical disc is constant) as shown in FIG. 5B, the optical head will traverse the track smoothly, and a mirror signal will not be obtained. There is a problem.

As a countermeasure to be taken when a mirror signal is lost, there is, for example, Japanese Patent Laid-Open Publication No. Hei 1-332049 (in this conventional example, the term "mirror signal" is not used, but it can be determined from the contents of a sentence). In this conventional example, as shown in FIG. 6, a tracking sensor 10, binarization circuits 11, 12, a direction determination circuit 13, and a direction storage circuit 1
4 and an up-down counter 15.
When the reproduction sum signal 21 is lost in the preformat area or the like, the output of the direction discrimination circuit 13 immediately before the loss is stored in the direction storage circuit 14, and the counting operation is normally continued. Here, the preformat area is a ROM area which is formed of concave and convex pits such as a sector number and is stored in the optical disk in advance.
This prior application describes that the sum signal level is largely disturbed in the preformat area, and the direction detection is relatively stable in the other area. However, in a region where there are no uneven pits (other than the preformat region), the mirror signal is not output in principle, so that the moving direction is unknown. Therefore, this prior application reproduces a medium in which a phase-change medium or a write-once medium recorded on a continuous groove is used, or a medium in which an information recording area is an uneven pit but has a large flat portion (mirror portion) in a preformat area. It is limited to the case.

[0011]

By the way, in a read-only disc such as a CD in which the entire surface is made up of only concave and convex pits,
Since the entire surface is a disk such as a preformat area, when the optical head is moved at a high speed in the radial direction of the optical disk, the deterioration of the mirror signal becomes large. Good for dense seeks such as track jumps, but a problem for coarse seeks.
In particular, recent CD-Rs that require high-speed access
In an OM drive or the like, it is difficult to perform track counting during the coarse seek, and the mirror signal deteriorates immediately after the coarse seek starts and is not output until immediately before the end. In addition, the amount of eccentricity is as large as ± 70 μm according to the standard, and the necessity of up / down counting is great. Further, in the above-described prior art, a measure for a case where the mirror signal gradually deteriorates as in the case of the high-speed rough seek is insufficient. When the optical head speed gradually increases, the mirror signal quality gradually deteriorates, and the mirror signal does not suddenly start to drop, and finally the mirror signal is not output. For this reason, there is a possibility that an erroneous direction discrimination based on a mirror signal may be made before a dropout occurs.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to make it possible to perform rough seek at high speed and accurately in an optical disk reproducing apparatus for reproducing an optical disk having uneven pits (phase pits). To realize high-speed access to information.

(1) The information access device for an optical disk according to the present invention comprises: a transport means for transporting the optical head in the radial direction of the optical disk; and a disk track at a beam spot position irradiated from the optical head and focused on the optical disk recording surface. A tracking / reproduction sum signal sensor for detecting a reproduction error signal which is a sum of a tracking error signal and a return light from the disc, which varies according to the amount of displacement from the center, and a comprehensive line signal (mirror signal) of the reproduction sum signal. A mirror signal detecting means for outputting, a beam moving direction detecting means for detecting a relative moving direction between the beam spot and the disk track based on a phase relationship between the tracking error signal and the mirror signal, and a relative moving speed between the beam spot and the disk track. Relative moving speed detection means and binarize tracking error signal A binarizing means for a rack count signal, a counting means for counting up or down the track count signal in accordance with a signal from the beam moving direction detecting means, and a specified speed generating means for outputting predetermined specified speed data. ,
Speed comparison means for comparing the speed data detected by the relative movement direction detection means with the specified speed data and outputting a hold signal when the speed data exceeds the specified speed, and when the hold signal is output as an up / down signal And a direction storage means for storing while the hold signal is being output. (2) The information access device for an optical disk of the present invention
The relative moving speed detecting means for detecting the relative moving speed between the beam spot and the disk track of (1) is configured to output the count value of the track count signal counted within a predetermined time as speed data. (3) The optical disk information access device of the present invention
The relative moving speed detecting means for detecting the relative moving speed between the beam spot and the disk track of (1) is constituted by an electromagnetic coil and a magnetic circuit attached so as to move integrally with the optical head transferring means of (1). The output from the speed sensor is output as speed data.

[0014]

In the information access device for an optical disk according to the present invention,
When focusing on an optical disk having uneven pits (phase pits), the tracking / reproducing sum signal sensor 1
As a result, the reproduced sum signal 21 and the tracking error signal 20, which are the total sum of the return lights from the disk, are detected, and the beam moving direction detecting means 4 outputs a comprehensive line signal (mirror signal) 23 of the reproduced sum signal 21. The tracking error signal 20 is binarized by the binarizing means 2 to become a track count signal 22, and is input to the beam moving direction detecting means 4 together with the mirror signal 23. The beam moving direction detecting means 4 checks the phases of the tracking count signal 22 and the mirror signal 23, and determines the relative moving direction of the beam spot and the disk track depending on whether the phase is advanced or delayed by 90 degrees. The result of the discrimination passes through the direction storage means 5 as an up / down signal 24 and is input to an up / down selection input of the counting means 6. The track count signal 22 enters the count input of the counting means 6 and is counted up or down by the up / down signal 24. Further, the track count signal 22 is input to the relative moving speed detecting means 7, the count number within a fixed time is detected as speed data 25, and the speed data is output from the specified speed generating means 8 by the speed comparing means 9. The hold signal 27 is output to the direction storage means 5 when the speed data exceeds the specified speed data 26. The direction storage means 5 normally functions to pass the up / down signal 24 as it is and to hold the output when the hold signal 27 is input from the speed comparison means 9.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings.

When accessing information on an optical disc,
First, a focusing servo is applied to the optical disk, and the optical disk is moved to an appropriate position in the radial direction of the optical disk by an optical head radial direction transfer means (not shown). Read location information. In a CD or the like, not the position information but the time information of music is discretely recorded in the main information as a subcode. In this case, too, the track number is calculated using the equation (1) described in the related art. Can be converted to

When an access instruction is issued from an upper apparatus, for example, from a personal computer or the like, to the optical disk reproducing apparatus, a control microcomputer (not shown) of the optical disk reproducing apparatus first determines the current position of the optical head by using the above-mentioned position. The information on the optical disk is read as described above to make the determination. Next, the track in which the information to be accessed is stored, which is instructed by the higher-level device, is obtained by calculation using equation (1) or the like. As a result, since the difference from the current track is known, the direction in which the optical head should be moved and the number of tracks can be determined. The control microcomputer loads the number of moving tracks into the counting means 6. Further, the optical head is driven by the optical head transfer means in the direction to be moved. Thereafter, by the operation of the information access apparatus of the present embodiment, the optical head is moved so that the counter value becomes zero while counting the track count signal 22 to reach the target track. The speed control of the optical head at this time uses the DTC method as described in the related art, so that accurate and high-speed head movement is possible.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In the information access apparatus for an optical disk of the present embodiment, when a focusing servo is applied to an optical disk having concave and convex pits (phase pits), a tracking servo is performed.
From the reproduction sum signal sensor 1, a reproduction sum signal 21 which is a total sum of return light from the optical disk and a tracking error signal 20
Is detected, and the comprehensive line signal (mirror signal) 23 of the reproduced sum signal 21 is output from the beam moving direction detecting means 4. The tracking error signal 20 is binarized by the binarizing means 2 and input to the beam moving direction detecting means 4 together with the mirror signal 23. The beam moving direction detecting means 4 checks the phases of the tracking count signal 22 and the mirror signal 23, and determines the relative moving direction of the beam spot and the disk track depending on whether the phase is advanced or delayed by 90 degrees. The result of the discrimination passes through the direction storage means 5 as an up / down signal 24 and is input to an up / down selection input of the counting means 6. The track count signal 22 is counted by the counting means 6 to count up or count down.
4.

When the optical head is moved in the radial direction by using the information access apparatus for an optical disk according to the present embodiment, it is possible to determine which track on the optical disk having the concave and convex pits has the beam spot, and determine the deviation of the optical disk or the like. Even if there is an influence of the core, it can be known accurately. Then, to end the coarse seek (high-speed movement of the head), the tracking may be turned on immediately when the counter value becomes zero.

A track count signal 22 is input to the relative moving speed detecting means 7, and the number of counts within a predetermined time is detected as speed data 25.
5 is compared with the specified speed data 26 output from the specified speed generating means 8 by the speed comparing means 9, and the specified speed data value 2
6, the hold signal 27 is stored in the direction storage means 5.
Output to The direction storage means 5 normally functions to pass the up / down signal 24 as it is and to hold the output when the hold signal 27 is input from the speed comparison means 9. As a result, the moving speed of the optical head is increased, the mirror signal 23 is degraded, and an erroneous up / down signal 24 is prevented from being input to the counting means 6. As a result, accurate track counting can be performed even when the optical head is moved at such a high speed that the mirror signal 23 is deteriorated, and the coarse seek time is shortened and the fine seek time is significantly reduced. it can. If there is no track count error or track number calculation error and the speed control of the optical head can be ideally performed, the target track can be almost reached by the coarse seek only.

The detection method of the relative moving speed detecting means is not specified. For example, as shown in FIG. 2, whether the count value of the track count signal counted within a predetermined time is output as speed data, As shown in FIG. 3, a method may be adopted in which an output from a speed sensor, which is mounted so as to move integrally with the optical head transfer means and is constituted by an electromagnetic coil and a magnetic circuit, is output as speed data.

Next, the relative moving speed detecting means of this embodiment will be described with reference to the drawings.

FIG. 2 is a diagram for explaining a speed data calculating method in the relative moving speed detecting means of this embodiment. FIG. 2A is a circuit block diagram showing an example of the circuit configuration.
The track count signal 22 indicated by 201 in the timing chart of FIG. 2B is counted up by the counter 29, and is generated by the timer 30 at regular intervals. Cleared by The count value immediately before being cleared is latched by the latch 31, and the speed data 25
Is output as Since the cycle of the track count signal is a value proportional to the reciprocal of the relative movement speed between the beam spot and the disk track, the count number of the track count signal within a certain time is proportional to the relative movement speed between the beam spot and the disk track. Value.

FIG. 3 shows another relative moving speed detecting means. In the example of FIG. 3, an output from a speed sensor, which is mounted so as to move integrally with the optical head transfer means and is configured by an electromagnetic coil and a magnetic circuit, is output as speed data. In the embodiment of FIG. 2, the speed data is a digital value discretely generated in the cycle of the measurement cycle pulse 32. In the case of the example of FIG. 3, the speed data is output as an analog current value. The optical head 34 includes a driving electromagnet 35
And the sensor coil 36 and are mechanically connected to each other. In order to move the optical head 34 in the radial direction of the optical disk at the time of accessing information, a current flows through a coil of the driving electromagnet 35 by a driving current 37 from an electromagnet driver (not shown), and a magnetic circuit including a yoke and a fixed magnet 33 is provided. As a result, a thrust corresponding to the drive current value acts on the optical head 35, and the optical head 35 moves in the direction shown in the figure. Further, since a magnetic circuit including the yoke and the fixed magnet 33 is also arranged on the sensor coil side, the sensor coil 36 that moves integrally with the optical head 34 includes:
Sensor current 3 according to optical head moving speed by electromagnetic induction 3
8 flows. If this sensor current 38 is converted into a current voltage, it can be used as speed data 25. Of course, the relative movement speed detecting means is not limited to the above-described structure, but may have any structure as long as it can accurately generate speed data.

[0026]

As described above, according to the information access apparatus for an optical disk of the present invention, in an optical disk reproducing apparatus for reproducing an optical disk having concave and convex pits, the moving speed of the optical head is increased, and the moving direction of the optical head is changed. Even when the mirror signal required for the determination is deteriorated, the number of moving tracks can be counted accurately, coarse seek can be performed accurately at high speed, and high-speed access of information can be realized.

[0027]

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of an information access apparatus for an optical disk according to the present invention.

FIG. 2 is a diagram for explaining a method of calculating speed data in a relative moving speed detecting unit of the embodiment.

FIG. 3 is a diagram for explaining a mounting position of a relative moving speed detecting means (speed sensor) of the embodiment.

FIG. 4 is a diagram illustrating an example of a profile of a transfer speed of an optical head of the optical disc reproducing apparatus.

FIG. 5 is a diagram for explaining a locus of beam passage on the disk surface when the optical head is moved in the radial direction while rotating the disk.

FIG. 6 is a block diagram for explaining a conventional information access technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 tracking / reproducing sum signal sensor 2 binarizing means 3 mirror signal generating means 4 beam moving direction detecting means 5 direction storing means 6 counting means 7 relative moving speed detecting means 8 prescribed speed data generating means 9 speed comparing means 10 tracking sensor 11 , 12 Binarization circuit 13 Direction discrimination circuit 14 Direction storage circuit 15 Up / down counter 20 Tracking error signal 21 Reproduction sum signal 22 Track count signal 23 Mirror signal 24 Up / down signal 25 Speed data 26 Specified speed data 27 Hold signal 28 Binary Regenerated sum signal 29 Counter 30 Timer 31 Latch 32 Measurement cycle pulse 33 Yoke, fixed magnet 34 Optical head 35 Drive electromagnet 36 Sensor electromagnet 37 Drive current 38 Sensor current

Claims (3)

(57) [Claims] 1. A transfer means for transferring an optical head in a radial direction of an optical disk, and a tracking which changes according to an amount of displacement of a beam spot position irradiated from the optical head and focused on an optical disk recording surface from the center of the disk track. A tracking / reproducing sum signal sensor for detecting a reproducing sum signal which is a sum of an error signal and return light from the optical disc; a mirror signal detecting means for outputting a comprehensive line signal (mirror signal) of the reproducing sum signal; Beam moving direction detecting means for detecting a relative moving direction between the beam spot and the disk track based on a phase relationship between a signal and the mirror signal; and a relative moving speed detecting means for detecting a relative moving speed between the beam spot and the disk track. And the tracking error signal is binarized to obtain a track count signal. Binarizing means for counting, a counting means for counting up or down the track count signal in accordance with a signal from the beam moving direction detecting means, and a specified speed generating means for outputting predetermined specified speed data. Speed comparison means for comparing speed data detected by the relative movement direction detection means with the specified speed data and outputting a hold signal when the speed data exceeds a specified speed; An information access device for an optical disk, comprising: direction storage means for storing when a signal is output and holding the signal while the hold signal is output. 2. A relative moving speed detecting means for detecting a relative moving speed between the beam spot and the disk track, wherein the relative moving speed detecting means outputs a count value of a track count signal counted within a predetermined time as speed data. The information access apparatus for an optical disk according to claim 1, wherein: 3. A speed constituted by an electromagnetic coil and a magnetic circuit, wherein a relative moving speed detecting means for detecting a relative moving speed between the beam spot and the disk track is mounted so as to move integrally with the optical head transferring means. 2. The optical disk information access device according to claim 1, wherein an output from the sensor is output as speed data.