JPS58161160A - Optical disk and its device - Google Patents

Abstract

PURPOSE:To grasp characteristics of sensitivity, an optimum recording condition, etc. of a disk medium without using an exclusive measuring device, by recording a reference signal in a part of an optical disk which is capable of recording and reproducing. CONSTITUTION:In a track guide groove 1 which is formed spirally or concentrically on a disk, an information pit 3 is recorded by a pit pattern whose inter- pit distance is varied like d1-dn. Each pit group P1-Pn is separated by a sufficient distance, and a special mark 2 is inserted as a synchronizing signal in case of read and evaluation. From a characteristic obtained by preparing such a reference pattern by changing the pit size, the resolving power can be evaluated. Also, by controlling consciously the control of automatic focusing, the relation of a resolving power characteristic, an automatic focusing characteristic and a read light spot can be evaluated separately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical disc and an apparatus capable of recording and reproducing, which can provide optimum conditions for recording and reproducing.

Optical disk systems are expected to be a high-density, large-capacity recording method. In the case of optical discs that can be recorded and played back, light is focused into a finely focused disc onto a disc medium, such as glass, with a photosensitive material that changes the optical properties due to light or thermal energy from the light. A beam is applied to record and reproduce information. In order to achieve high-density information recording and reproduction, the characteristics of the disk medium, the optical head (hereinafter referred to as read or write head) that performs recording and reproduction, and the characteristics of the reproduction system must be optimized. A relationship must be maintained. In other words, the sensitivity of the disk medium, the amplitude and pulse width of the recording pulse (write pulse), the size and shape of the read and write light spots, and the automatic focus (
It is necessary to maintain constant relationships among the states of control (hereinafter referred to as AF) and tracking (hereinafter referred to as TR), as well as the frequency characteristics and detection accuracy of the reproduction circuit. By the way, disk media, read/write head, AF-? The servo characteristics of the TR, playback circuit, etc. are each manufactured and adjusted to have predetermined characteristics based on the above relationships, but considering that any of the above characteristics fluctuates for some reason, the results will vary. It is difficult to determine in which characteristics a change has occurred and a loss has occurred.

This is because the result is observed only as an output signal from the reproduction circuit. On the other hand, the playback circuit output is a comprehensive result of the medium, the size and shape of the recorded information created on the medium, the characteristics of the read/write head, the servo condition, etc., so unless special observation and inspection equipment is used, there will be no cause for concern. cannot be separated.

However, when reading and writing on optical disks, the recorded information itself has a bit size of 1 μm or less, the read/write light spot has a size of 1 to 2 μm, and there are problems such as deviations in servo characteristics of about 0.1 μm, so special observation and inspection equipment is required. However, this requires extremely high-precision, large-scale, and therefore expensive equipment, and there is a problem in that it is not possible to easily check each characteristic at any time at the site of use.

An object of the present invention is to provide a means by which the characteristics of each component can be easily determined without using high-degree and expensive measuring equipment.

The present invention utilizes the fact that the optical disk device itself has the function of an extremely high-precision measuring device, and measures each of the above-mentioned characteristics by the device itself. However, as described above, the read signal is read based on a combination of various factors. For this purpose, in advance, corresponding to the characteristics to be measured,
Determine the optimal reference signal for each. The response (result) to this reference signal and knowledge about each characteristic are integrated to separately measure each characteristic.

The reference signals vary depending on the intended characteristics to be measured, but all of them are prepared in advance on the disk medium.

The reference signal and characteristic measurement using it will be explained below.

The characteristics to be measured are as follows.

(1) Resolution (frequency characteristics) (2) Bit size (3) V8 degree variation (4) Signal level (5) Servo (AF, TR) performance (6) Recording medium sensitivity (optimum mA) (7) Playback A reference signal is prepared for each of the system characteristics (worst case slam, level fluctuation, etc.), but the shared signals can be omitted if necessary.

For the resolution (1), a bit string in which the recording bit melting rate is modulated according to a certain rule may be used. In this case, the own pit size is also made smooth and several types are made according to the established standards. With this reference signal! ? (1), (2), ((2), (
4) Information regarding (7) etc. can be obtained. The bits are also light and dark,
It is desirable to prepare a phase detection (concave/convex bit) type and detect changes in depth as well as size for concave/convex bits.

For the reference signal related to (6), the necessary bits are recorded using several kinds of smooth and predetermined power levels and write waveforms.

The reference signal related to (7) modulates the track guide groove in a predetermined form (bang), and the characteristics of the disk and servo system can be known from the response of the modulated bash and the servo signal.

As mentioned above, the reference signal is a bit slam that is controlled to have a predetermined shape or size (quantitative information on shape and size is known by other means).

It consists of a track guide groove button, a recording button, etc.

Characteristic evaluation is performed by comprehensively evaluating responses to each reference signal.

The present invention will be explained below with reference to Examples.

! Figure @1 shows an example of a reference button regarding resolution. Information bits (3t) are recorded in the track guide grooves 1 made in subile or concentric form on the disk, but the distance between the bits changes according to a predetermined rule such as d, d, ..., d. Bit slam. The distance between bits is d
The number of bits of i is at least two (in the case of three Ifi shown in the figure), and each bit group p+, pm,...
, p, are separated by a sufficient distance Δ. Note that a special mark 2 is inserted as a synchronization signal when reading and evaluating. Figure 2 shows the output poem form from the head when reading out the baton in figure wJ1. The read waveform is read out in the form shown in the figure at an intermediate level between a signal level 4 corresponding to the amount of reproducing light from the non-recording disk surface and a zero level 5 when the reproducing light is zero. The signal level 21.31 corresponds to the recorded information 2.3 in FIG. It is defined by the signal amplitude h at a certain recording density DJ, that is, the inter-bit distance djK, and the signal level difference Sj between the bit center and the middle of the adjacent pit in the pj pattern. Zero meaning. FIG. 3 shows the relationship between bit distance (ie, recording density) and modulation degree. The above standard slam,
If you prepare by changing the bit size (bit diameter) r,
The physical properties shown in FIG. 3 can be obtained. Resolution can be evaluated from this characteristic. In other words, it is possible to know whether the resolution of the target device has a predetermined value. Furthermore, automatic focus evaluation is possible. In other words, head characteristics and servo systems can be evaluated.

FIG. 4 shows an example of a reference pattern for examining the relationship between the guide groove structure and the TR signal. As shown in (A), following the synchronous side bit 3, the depth of the guide groove is changed, for example, from 100 to 104 as shown in the sectional view (B). By examining the TR signal for this pattern, the servo signal detection system can be evaluated. FIG. 5 shows the relationship between the guide #I depth h and the characteristic quantity α regarding the servo signal.

FIG. 6 shows an example of a reference pattern for TR and system evaluation in which guide #1 is locally swung from side to side like 1-1.1-2.1-3. If you know the amount of TR swing in advance, T'
Relationship between fL deviation and TR signal, that is, impression of TR detection system 1
1. I can know.

FIG. 7 shows an example of a standard pattern regarding the sensitivity of the recording film and the optimum recording conditions.64J! As shown in Figure 7 B) or (B), the waveform of power P and pulse width W is used as a write signal.
Records are made while being refined according to a predetermined pattern as shown in the figure. If a calibrated reference light is used in the recording device, more accurate evaluation can be performed. FIG. 8 shows the reproduction output from the focus recorded with the write waveform shown in FIG. 7 (0). In addition#! In Figure 8, t indicates time. From this, it is possible to know the optimum range of the write pulse waveform (power and pulse width) as well as the sensitivity of the recording film. Figure 9 shows the light power P and the characteristic quantity of the reproduced signal (for example, modulation concealment, resolution, etc.) B.
FIG. Standard patterns such as Figures 1, 4, and WJ6 can be easily reproduced (y-preca), but
The purpose of the diagram is to know the characteristics of the recording film for each disc, so it will be made individually for each disc. Recording using the reference pattern shown in FIG. 7 may be made at the time of inspecting the disc.

If the reference pattern shown in FIG. 1 is recorded at the same time as the button shown in FIG. 7 above, it is possible to evaluate the write conditions, changes xi, resolution, etc.

By the way, if the optical disk device is equipped with a reference pattern generator as shown in FIG. 7 or WJ1 in addition to the original signal modulation and demodulation functions, it is possible to easily evaluate the recording and reproduction of the device itself.

The above reference signals each have a sufficient fTo deviation of several tracks -t-1α tracks. Therefore, the original recording capacity of the disc is hardly affected. In other words, the number of tracks for information recording is #-i' 30,000 or more tracks, and the binding for reference signals is 23.
When 0 tracks are used, it is less than 0.1%. Therefore, as shown in FIG. 10, a reference signal area Tt- is located inside or outside the original information recording area U of the recording medium.
can be provided.

Note that FIG. 10 shows only one side of the upper surface of the disk.

As described above, according to the present invention, the characteristics of the optical head of an optical disk device, the servo signal system, and the read signal system can be improved. 1F
In addition to III, the optical disc device itself can evaluate the sensitivity, optimal recording conditions, etc. of the disc medium without using a dedicated measuring device.

In particular, in optical disk devices, where the results are obtained by integrating the factors of each component, and it is difficult to separate each factor even using a dedicated measuring device, the optical disk itself can provide highly accurate quantitative results. The fact that it makes evaluation possible has an extremely large practical effect.

[Brief explanation of drawings]

Fig. wJ1 is a diagram showing an example of the reference pattern in the present invention, 2nd Flt is an explanatory diagram showing the lead waveform of the baton in Fig. 1, and Fig. 3 is an explanatory diagram showing the characteristics obtained from the baton in Fig. 1. Figure 4 is a diagram showing an example of a reference pattern for evaluating tracking characteristics, Figure 5 is an explanatory diagram showing the characteristics obtained from Figure 4, and Figure wJ6 is the ninth standard butterfly characteristic for evaluating tracking characteristics. FIG. 7 is a diagram showing an example of a recorded waveform related to the evaluation of Kikishikishi. FIG. 8 is a diagram showing a read waveform from the slam of FIG. jI7. Figure 9 is Figure 7,
The recording characteristic diagram obtained from FIG. 8. FIG. 1.0 is a top view of a disk showing an example of a recording location of a reference pattern.

Claims (1)

[Claims] 1. An optical disc and device that is capable of recording and reproducing information, and is characterized in that a reference signal is recorded on a part of the disc.