JPH0546986A - System for measuring track crossing signal of optical disk - Google Patents

Abstract

PURPOSE:To provide a system for measuring track crossing signals by specifying the position of a measuring point irrespective of the presence/absence of eccentric rotation of an optical disk and against the optical disk. CONSTITUTION:While a disk 1 is rotated, a head controlled in tracking reads out an arbitrary sector of the disk 1 by seeking an arbitrary track of the disk 1. A crossing signal RS is measured by receiving a change in reflected light from a groove G by making the head 2 to cross the disk 1 in the perpendicular direction at a high speed by deciding the position of the sector as a measuring point (p). Therefore, a prescribed sector can be easily read out by using a constant timing signal and measured data having excellent reproducibility can be obtained when the disk mounted on a spindle is exchanged, and so on.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a track crossing signal of an optical disk.

[0002]

2. Description of the Related Art Optical discs are widely used in various fields as storage media having enormous storage capacity. FIG. 2 shows the structure of an optical disk (hereinafter simply referred to as a disk) used in an information processing system. In FIG. 2A, a large number of grooves G (1 to N) are formed in the circumferential direction on the surface of the disk 1. Perforations are made to form tracks along each G. Each track has a plurality of sectors (Sec) starting from an index signal (INDX) indicating a reference position in the circumferential direction of the disc.
It is divided into S _{1 to} S _m , and sector identification information and data are recorded in each. (b) shows the cross section of the disk 1, L
Grooves G are arranged with a fine pitch interval with the surface as the surface. In (a) of the figure, the width of L is made slightly larger than G,
The part of L is used for a data track, which is called an on-land type. On the contrary, (B) is an in-groove type in which G is used for a data track by making G wider than L.

An optical head (hereinafter, simply referred to as a head) receives the reflected light of the groove G, and tracking control is performed on the data track. Therefore, the cross-sectional shape or the light reception signal is important. In contrast, ISO
Defines track crossing signal measurement, and the track crossing signal means a light reception signal of the head when crossing G. FIGS. 3 (a) and 3 (b) show a conventional method for measuring a track crossing signal. In FIG. 3 (a), the disk 1 is rotated in the θ direction by the spindle. The tracking control of the head is stopped, the head 2 is seek-moved to a measurement point p at a predetermined position with reference to INDX, and the reflected light of the disk 1 is received. Assuming that the center of the disk 1 is O and the center of rotation of the spindle is O ', normally O and O'are different, the disk 1 is eccentrically rotated, and G is shown for each measurement point p with respect to each measurement point p. And a dotted line, so that a plurality of Gs pass the head 2. Since the intensity of the reflected light of G is smaller than that of the surface L, the level of the light reception signal R _s of the head changes as shown in (b) of the figure, and the lowered level shows the cross-sectional shape of G, which means that This is a track crossing signal R _s according to ISO. By analyzing this, the cross section of G or the width and depth of R _s can be obtained. Moreover, the quality of the G shape is evaluated by taking various positions of the measurement points p and _obtaining the average value of R _s and the distribution characteristics on one round of G and on the entire surface of the disk.

[0004]

Since the above-mentioned eccentric rotation of the disk is unfavorable for data access, recently, the eccentricity has been reduced by improving the disks and drivers, and the eccentricity is different for each disk. Different. For this reason, the above method does not provide a certain number of good transverse signals. In the above, IN
Although the measuring point p is set at a predetermined position by the timing signal with respect to DX, INDX is not unique to the disk and is generated corresponding to the rotational position on the spindle side. , The position of the measurement point p changes relatively and is not specified with respect to the disc. For this reason, the crossing signal R _s has poor reproducibility and further hinders the calculation and determination of the above-mentioned average value of R _s . The present invention has been made in view of the above, and it is an object of the present invention to provide a method for measuring a track crossing signal irrespective of the presence or absence of eccentric rotation of a disk, and by specifying the position of a measurement point p with respect to the disk. It is a thing.

[0005]

SUMMARY OF THE INVENTION The present invention is a track crossing signal measuring system for an optical disk which achieves the above object, wherein the disk is rotated and an arbitrary track of the disk is sought by an optical head which is tracking controlled. Read any sector. Using the position of the read sector as a measurement point, the head is traversed at a high speed at a right angle to the groove punched on the surface of the disk, and the change in reflected light of the group due to the traverse is received by the head and measured. Is.

[0006]

In the above measuring method, an arbitrary track is sought by the tracking-controlled head to read an arbitrary sector. At that position, when the head traverses in a direction perpendicular to G at a high speed, the reflected light of G changes, which is received by the head and a track crossing signal signal is obtained. In this case, the crossing signal is obtained regardless of the presence or absence of eccentric rotation of the disk, and since the position of the sector is known, the measurement point can be easily set at a fixed timing,
The position of the measurement point with respect to the disc is specified, and good reproducibility can be obtained even when the disc is replaced. By performing the above-described crossing signal measurement on a predetermined number of sectors, the measurement data is statistically processed to calculate the average value and distribution characteristics of the crossing signals in one round of G or the entire surface of the disk to evaluate the quality. be able to.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, in which (a) is a schematic block diagram, (b) is an explanatory view of the transverse movement of the head with respect to the groove G, and (c) is a light reception signal of the head. Alternatively, FIG. 6D is a waveform diagram of a track crossing signal, and FIG. 7D is an explanatory diagram of a conventional jump crossing method between tracks. Figure 1 (a)
At, the disk 1 is mounted on the spindle 1a and rotates. On the other hand, the head 2 is moved by the carriage mechanism 3 in the radial direction of the disk. Reference numeral 4 denotes a control unit, which includes a microprocessor (MPU) 41, a carriage control circuit 42, a signal processing unit 43, and a memory 44 as main elements. The position data of a predetermined track stored in the memory 44 is read by the MPU 41 and given to the control circuit 42, and the carriage mechanism 3 is moved by the control so that the head 2 servo seeks this track. When the measurement point p is set at the position of a predetermined sector S _{n and} the jump signal J is simultaneously output from the control circuit 42 to jump the carriage mechanism 3, the head 2 is moved to the groove G ₁ or the like as shown in (b). Cross at a high speed in a direction perpendicular to. The reflected light of the disk 1 is received by the head 2, and the light receiving signal shown in (c), that is, the track crossing signal R _s is obtained for G ₁ etc. by crossing, and by analyzing this, the width and depth of G etc. Is required. In FIG. 1 (d), the track T _R of the disk 1 is set in a spiral shape, since each T _R is not connected as one round, suitably an adjacent T _R to use this as one round It is necessary to connect at various positions. Because of this, IN
How to jump across the head from the point p _b of the track T _Rb at a point p _a track T _Ra at the position of the DX it is being performed. The above-mentioned high speed traverse of the head 2 is performed using this technique. The measurement point p is set for each of a predetermined number of sectors of any one track or a plurality of tracks, the above measurement is performed, each light reception signal R _s is stored in the memory 44, and the stored measurement data is stored. Statistical processing is performed by the MPU to calculate the average value of R _s for one round of G or the entire surface of the disk, its distribution characteristics, and the like.

[0008]

As described above, in the track crossing signal measuring method according to the present invention, the crossing signal can be obtained regardless of the eccentric rotation of the disk and the position of the measuring point with respect to the disk is specified. The reproducibility of the measured data is good even when the disk is replaced with the spindle, and the measured data for a predetermined number of sectors is statistically processed to obtain the average value and distribution characteristic of the transverse signal for one round of G or the entire surface of the disk. Etc. are calculated and contribute to the quality evaluation of the optical disc.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a schematic block diagram, (b) is an explanatory view of a transverse movement of an optical head with respect to a groove, and (c) is a light reception signal of an optical head or a track. FIG. 3D is a waveform diagram of a crossing signal, and FIG. 7D is an explanatory diagram of a conventional jump crossing method between tracks.

2A and 2B show a structure of an optical disc, FIG. 2A is a view showing a groove G, a track, and a sector S perforated on the surface, and FIG. 2B is a sectional view of the optical disc.

3A is an explanatory diagram of a conventional method of measuring a track crossing signal, and FIG. 3B is a waveform diagram of a light receiving signal of an optical head or a track crossing signal signal.

[Explanation of symbols]

1 ... Optical disk, disk, 1a ... Spindle motor,
2 ... Optical head, head, 3 ... Carriage mechanism, 4 ... Control unit, 41 ... Microprocessor (MPU), 42 ... Carriage control circuit, 43 ... Signal processing unit, 44 ... Memory, INDX ...
Index signal, T _R ... track, S ... sector (Se
c), L ... Surface, G ... Groove, p ... Measuring point, R _s ... Light receiving signal or track crossing signal.

Claims (1)

[Claims] 1. An optical disk is rotated, an arbitrary track is sought by an optical head under tracking control to read an arbitrary sector, and the position of the read sector is used as a measurement point to perforate the surface of the optical disk. A method of measuring a track crossing signal of an optical disk, characterized in that the optical head is crossed in a direction perpendicular to a groove at a high speed and a change in reflected light of a group due to the crossing is received and measured by the optical head.