JPS5968828A - Optical information recorder and reproducer - Google Patents

Abstract

PURPOSE:To detect dropout of any form by detecting the dropout by a photo detector receiving a reflected light from a disc as well as reproducing signal at its split face and using a difference signal of detector outputs and a focus error signal. CONSTITUTION:Detectors F1, F2 are placed at the focus of a focus detector 33 and detectors T1-T4 having a split face in parallel and vertical to a guide track 1 are placed in a tracking detector 34. Only the dropout having a large change in the reflectance is detected with an output (c) of the change in all the reflected luminous amount. An output of an amplifier 40a is (T1+T3)-(T2+T4) and an output (d) shows the detection of change in the shape of groove. (T1+ T2)-(T3+T4) is outputted (f) by an amplifier 40b from the detectors T1-T4. The output (f) produced at the dropout due to projection being a tracking error signal, is detected as a control error together with a focus error signal (e). That is, the signals (c), (d) are signals on the open loop being outputs of the detectors, and the signals (e), (f) are control error signals in the control loop and check for the dropout.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical information recording and reproducing apparatus for recording information on a disk-shaped recording medium (disk) that can be optically recorded and reproduced and for reproducing the recorded information from the disk. It is related to.

3.Conventional structure and its problems Recording and reproducing signals at high density on an optical recording disk by concentrating the light of a laser etc. into light with a diameter of 1 μm or less is a method of recording signals on the master of the video disk. It is often done in some cases.

Furthermore, with the recent development of new optical recording materials, optical recording and reproduction of digital signals and video signals on optical discs has been carried out.

In addition, in order to record and reproduce high-density signals with a simple device, it is possible to use a disk with an optically detectable guide track and record and reproduce signals along or within the guide track. It is being done.

FIG. 1 shows an example of an optical recording disk 2 having a guide track 1. As shown in FIG. As an example of the above-mentioned guide track, it has been proposed to use a groove having a depth of about % of the wavelength of light from a light source used for recording and reproduction and a width of ω (0.5 to 1 μm). These grooves are arranged spirally or concentrically at an appropriate track pitch P over the entire signal recording area on the disk.

When a recording material 4 is deposited on such a disk and a laser beam is focused and irradiated into a minute spot, the reflectance of the recording material changes and recording pits 5 are formed.

FIG. 2 shows an example of the format of an optical recording disc.

In FIG. 2, only one signal recording track is shown to simplify the drawing. In the figure, N indicates an address signal that prerecords a unique address number to distinguish the signal recording trunk from other trunks. nl + n2
+..., nm indicates a sector number signal in which a sector address signal unique to each sector is recorded, since one signal recording trunk is used by dividing it into a large number of sectors. N+, (J2+...+IB) indicate an information recording area in which an information signal is recorded and reproduced as necessary corresponding to the first position of each sector.

Note that the arrow indicates the direction of rotation of the disk.

There are several methods to guarantee the recorded contents of an optical recording disc. For example, there is a pre-check recording method in which dropouts in an information recording area that cause recording signal loss are checked before recording, and no recording is performed in sectors where dropouts exist. FIG. 5B-3 shows the configuration of an optical information recording/reproducing apparatus having a blank check recording function. 6 is a semiconductor laser, 7 is a condensing lens, 8 is, for example, a beam splitter, 9 is a tracking mirror, and 10 is an aperture lens.

The aperture lens 10 focuses the light from the semiconductor laser 6 onto the optical recording disk 2 to a diameter of about 1 μm. A photodetector 11 detects reflected light from the disk 2 and converts it into an electrical signal. Reference numeral 12 denotes a disk motor, which rotates the optical recording disk 2 at a prescribed speed.

Reference numeral 13 denotes a semiconductor laser drive circuit, which switches the optical output of the semiconductor laser 6 according to recording or reproduction, or performs optical modulation using data for one sector, and receives a recording signal from the control device 21. Reference numeral 14 denotes the amplifier, which can output changes in the amount of reflected light from the disk as a reproduction signal. Using this reproduced signal, the track address detector 15
, the track address and the sector address are detected by the sector address detector 16, respectively, and a specific sector information area is accessed. Then, the dropout detector 17 detects dropouts in the sector information area from the reproduced signal from page 6, and if there are more than a specified number of dropouts, the dropout detector 18 operates and records the sector as a bad sector. skip to the next sector information area. In this way, recording signals are guaranteed by determining a prescribed number of dropouts based on a judgment as to whether or not the demodulated signal can be error corrected, and by recording only sector information areas that are less than the prescribed number. However, with the above configuration, it is not possible to completely detect dropouts that cause defects in recorded signals. The reason for this will be explained using FIG. 4. FIG. 4 schematically shows several types of dropouts that actually cause defects in recorded signals. FIG. 4(a) is an enlarged view of a part of the information recording area 1 in the grooved guide trunk 1. The groove width is 0.5 to 1 μm. Figure 4(b) shows Figure 4(2L
) is a sectional view of the guide trunk 1 in the track parallel direction. 24 represents the flat part in full bloom, 25 represents the level of the groove bottom,
A recording material 4 is deposited on the surface. Fig. 4 (C1 is Fig. 4 fI&) shows the reproduced signal output waveform when tracking baking control is applied to the guide track as shown in Fig. 4. Dropouts that cause defects in the recorded signal are A to E. There are five types: A type is generally called a pinhole, and the recording material 4 is deposited within the groove-shaped guide track 1 at the lowest part 221L.In this case, the reflectance decreases at the position of the pinhole. This occurs due to small scratches or holes on the disk base material 23, non-adherence of foreign matter such as dust during vapor deposition, or unevenness of the vapor-deposited material.24 indicates the size of the minute light spot tracking along the guide track. If the size of the pinhole is larger than the minute spot light as in type A, dropout is detected with a sufficiently large output for the reproduction signal.The reproduction signal detects changes in the reflectance of the recording material. No, the change in the amount of total reflected light from the optical recording disk is output.However, when the size of the pinhole 221L is smaller than the minute spot light as in type B, it hardly appears in the reproduced signal output.

This is because unless the minute spot light is large enough to be completely included in the pinhole, a sufficient change in reflectance cannot be detected.

Even a minute dropout as shown in B causes loss of the recorded signal and causes demodulation errors.

Type C dropout occurs when there is a defect in the guide trunk 1 provided on the base material, and it is caused by unevenness of the surface of the master disk during groove cutting, noise during cutting, or the groove shape that occurs when foreign matter adheres to the stamper. It is defective.

A type D dropout is a hole on the disc base material.

This is the case when there is a defect in the base material itself, such as a dent.

Furthermore, the dropout has a high frequency component that cannot be followed by focus control. E-type dropout occurs when the grooved guide track deviates from a concentric or spiral trajectory. This is caused by vibration during cutting or poor pressure during stamping. Even though all of the BE type dropouts cause defects in the recorded signal, it has been impossible to detect all types of dropouts using only the reproduced signal.

Therefore, even if you perform pre-check recording, the data will be 9 paper? Uncorrectable errors sometimes occur during reproduction, making it impossible to obtain sufficient guarantees for recorded signals, reducing the reliability of this type of optical information recording and reproducing apparatus.

Purpose of the Invention The present invention solves the above-mentioned conventional problems, and makes it possible to detect any form of dropout that causes a loss in the signal recorded on an optical recording disk. The objective is to improve the error rate after demodulation by determining the error rate and performing pre-check recording.

Structure of the Invention The present invention detects dropout not only from a reproduced signal, but also by receiving reflected light or transmitted light from an optical recording disk with a photodetector having split surfaces in the vertical and horizontal directions with respect to a guide track. The optical information recording and reproducing apparatus is provided with means for detecting dropout using a difference signal of the output of the photodetector and a focus error signal obtained for focusing a minute spot light on an optical recording disk. . By using the various configurations described above, it is possible to detect any form of dropout on a 10-beam recording disk.Since bad sectors can be reliably detected, the error rate after demodulation can be improved, and optical recording This is suitable for guaranteeing the recorded contents of the disc.

DESCRIPTION OF THE EMBODIMENTS FIG. 5 shows the configuration of the optical system in the optical information recording/reproducing apparatus of the present invention. The light beam irradiated from the semiconductor laser 2θ is collected by a condenser lens 27, passes through a beam splitter 28, a λ/4 plate 29, and is sent to an aperture lens 1.
0 irradiates onto the optical disk 2 as a minute spot light. The optical disc 2 is rotated by a disc motor 3o. The reflected light from the optical disk 2 has its polarization plane changed by the λ/4 plate 29, and is therefore separated by the beam splitter 28. Furthermore, the light is divided into a focus detector 33° and a tracking detector 34 by a convex lens 31 and a splitting mirror 32, respectively, and is received by the focus detector 33° and the tracking detector 34, respectively. FIG. 6 shows the focus detector 33. Trunking detector 34
11 is a diagram showing the relative positional relationship between the structure of the light receiving element and the track 1 in the hedge of Plan 11. FIG.

The focus detector 33 includes a two-part photodetector F1. F2 is placed. The tracking detector 34 divides the far-field image of the reflected light into four-split photodetectors T1 to T1 to have dividing planes parallel and perpendicular to the guide track 1.
Place T4. FIG. 7 shows the configuration of the signal processing section of the optical information recording/reproducing apparatus of the present invention. FIG. 8 is a diagram showing signal waveforms of various parts at points c+ to (0) in FIG. After being used as a signal and having its waveform shaped by the waveform shaper 36a, the conventional example (
3), a track address detector 15° dropout tester 18a, a digital demodulator 19 for recording signals
is input. The waveform shaper 361L compares the positive threshold value 371L and the negative threshold value 37b as shown in FIG. In this case, the reflected light from the optical recording disk is reduced, as shown in Figure 8C.
The signal waveform becomes as shown in 38b. Conversely, if there is a dropout like type A', the reflectance increases. Possible causes include uneven vapor deposition and adhesion of impurities. The above method is effective only for detecting dropouts on the disk surface, which are characterized by large changes in reflectance. In actual optical recording discs, there are various types of dropouts that affect recorded signals. FIG. 7 39iL, 39b is a sum amplifier,
A differential amplifier 40& outputs a difference signal between the outputs of the two sum amplifiers 39a and 39b. Therefore, the output is (T
I + T3) (T2 + T4), as shown in Figure 6 (b)
Therefore, it is possible to output a difference signal between the outputs of a two-split photodetector having a split plane perpendicular to the guide track 1. This output d
When a sector address or the like is cut due to the unevenness of the grooved guide track, the diffraction image of the reflected light can be detected with a good S/N ratio. Therefore, in the embodiment, after the d output is waveform-shaped by the waveform shaper 36, it is applied to the sector address detector 16 and used for detecting the selector address. It is also applied to the dropout detector 18b and used to detect dropout 13 pages. In the dropout of type A in FIG. 8, the envelope of the recording signal is significantly reduced due to the defect in the groove shape of the guide track 1, making demodulation impossible. Even if the shape of the groove changes, almost no change in the total reflectance is detected, and therefore, C type dropout cannot be detected using only the reproduced signal C. The d output is a two-split photodetector with a split surface perpendicular to the grooved guide track, and it receives the far-field image from the grooved guide track 1.The SA detects changes in the diffraction image in the direction parallel to the grooved guide track. Can be detected well. Therefore, if there is a change in the groove shape such as in the C type, the diffraction image of the reflected light changes, and a change in the light amount distribution occurs in the far field image received on the photodetector. d output to threshold 46&
, 46b for comparison output and use for dropout inspection 18b.

As described above, one of the features of the present invention is that KOC type dropout can also be detected reliably. The B type dropout is a pinhole type dropout smaller than the diameter of the minute spot light 24. When such a small bottle 14 page hole is irradiated with a minute spot light, the minute spot light is simultaneously applied to the normal portion where the recording material is deposited and the pinhole. Therefore, as shown at 41, only a slight change in reflectance can be detected, and as shown at 38b, it is impossible to reach the threshold level and therefore cannot be detected. Unless the pinhole has a size such that the minute spot light is completely included in the pinhole (such as A'), a sufficient change in reflectance cannot be detected. However, in the case of the d output, due to the characteristic of differentially outputting changes in the light amount in the track parallel direction of the grooved guide track, it is possible to detect even small changes in reflectance due to the size of a minute spot light, as shown in Fig. 8, 42. . The light received on the focus detector 33 is divided into two photodetectors FI +
A focus error signal e of (Fl-F2) is outputted from the differential output of '2, and a focus control 43 is applied to control the optical pickup 45 so as to collect fish on the surface of the optical recording disk 2.

Tracking detectors T1 to T4 are sum amplifiers 39c.

(TI + T2 )- by 39d1 differential amplifier 40b
(T3 +T4) is output f.

15 Since the page output f is a differential output of a guide track and a two-split photodetector having a horizontally divided surface, it becomes a tracking error signal and controls the inclination of the optical pink-up 45 to apply tracking control 43 to a desired track. be able to. Incidentally, although ultraviolet curing resin is used as the groove base material of optical recording disks, there are defects such as holes, dents, and protrusions of several tens of micrometers or more. This is caused by pressure strain during stamping, foreign matter adhering to the stamper, etc. This is a D-type dropout, and if its size is about several tens of micrometers, it becomes a high frequency component that cannot be followed by focus control. Therefore, in the D-type dropout occurrence portion, a defocused state occurs and the recording envelope decreases.

Almost no change in reflectance is detected even in the D-type dropout portion, and it is impossible to detect a dropout using only the reproduced signal C. However, in the case of a D type dropout, the defocus state occurs as described above, so that it is detected as a control error on the focus error signal e. Generally, D-type dropouts occur in bursts and have a long duration, resulting in a decrease in the recording envelope over a large range. Therefore, the damage to recorded contents is also severe. When performing pre-check recording, detection of type D dropouts is essential. The focus error signal e is compared by a threshold value 47b, and the waveform shaper 36
(The waveform is shaped at step i and applied to the dropout tester 18d for dropout detection.Finally, type E dropout occurs when the guide track 1 deviates from the concentric or spiral trajectory, and vibration occurs in the guide groove cutting.) This occurs due to pressure distortion during spanner operation.In this case, as with focus control, if the amount of deviation is outside the controllable frequency characteristics, a tracking control error will occur, and a minute spot will be accurately placed on the indoor track. It becomes impossible to irradiate the light. In this case as well, the recording envelope decreases and demodulation becomes impossible. In this case, the ED type dropout causes almost no change in the amount of total reflected light and cannot be detected using the reproduced signal C alone. Yes, but 17
However, as described above, since a control error occurs in the dropout portion of the E type, it can be detected on the tracking error signal f. f output to waveform shaper 3
Pre-check recording can be performed accurately by shaping the waveform with 6C and applying it to the dropout tester 18C for use in dropout detection.

Classifying the dropout detection signals above, C9d performs dropout testing using the open loop signal of the photodetector output itself, and e and f perform dropout testing using the control error signal in the control loop.

As described above, according to the present invention, any type of dropout (A-E type) that reduces the envelope of a recording/reproduction signal and causes a demodulation error can be accurately detected, and highly reliable dropout can be achieved. Records can be made.

The control device 21 takes in the results of the above dropout inspection as data, and based on the possibility of error correction,
Determine the sector to skip recording, stop digital modulation for page 18 in that sector, and control so that the recording signal is input to the semiconductor laser drive circuit, and the optical power of the semiconductor laser does not reach the recordable level. can do.

As described above, the D type dropout detected on the focus error e and the E type dropout detected on the tracking error f cause a large damage because the recording envelope decreases in a burst manner.

Therefore, if even one dropout of type D or E occurs in one sector, it is determined to be a bad sector, and for types A, B, and C, it is determined that only dropouts with a bit length that can be corrected can be recorded. You can also do that.

In the embodiment, the explanation has been limited to the detection of reflected light from the optical recording disk, but it goes without saying that the detection output of the transmitted light of the optical recording disk may also be used.

Effects of the Invention The optical information recording/reproducing apparatus of the present invention reduces the envelope of the recording/reproducing signal and causes demodulation errors.19/(-:
Detection of harmful dropouts caused by the optical disc can be detected using only a playback signal that detects changes in the total amount of light reflected from the optical recording disc. The light is received by a photodetector having
Means is provided for detecting dropout using each difference signal of the output of the two-split photodetector and a focus error signal obtained by focusing a minute spot light on the optical recording disk. According to the present invention, since any form of dropout on an optical recording disk can be reliably detected, bad sectors can be accurately determined during pre-check recording, and the error rate after demodulation can be improved. I can do it.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view showing the structure of an optical recording disc with a guide track, Fig. 2 is a plan view schematically showing the format of the optical recording disc, and Fig. 3 is a diagram showing a conventional blicheck recording function. A block diagram showing the configuration of an optical information recording/reproducing device, FIG. 4 is a schematic diagram showing a dropout configuration, and FIG. 5 is an optical system of an optical information recording/reproducing device in an embodiment of the present invention. , FIG. 6 is a diagram showing the configuration of the photodetector element in the same embodiment of the present invention, FIG. 7 is a block diagram showing the configuration of the signal processing section in the same embodiment of the present invention, and FIG. The form of dropout and the seventh
It is a figure which shows the signal waveform at each point of a figure. 1...Guide track, 2...Optical recording disk, 24...Minute spot light, 33...
...Focus detector, 34...Tracking detector, N...Track address area,
n...Sector address area, l...Information recording area/Name of agent Patent attorney Toshio Nakao and 1 other person 1st
Figure 2

Claims (1)

[Claims] ■ A light source such as a laser is focused into a minute spot light and irradiated onto an optical recording disk having concentric or spiral guide tracks, a track address area, a sector address area, and an information recording area to record information. A means for recording and reproducing, and a photodetector having at least two or more dividing planes receives reflected light or transmitted light from an optical recording disk immediately before recording information, and generates a difference signal sum of the outputs of the photodetectors. An optical information recording/reproducing apparatus comprising: means for inspecting dropout of an information recording area from at least one of the signals. ■ A far-field image of reflected light or transmitted light from an optical recording disk is received by a photodetector having a dividing plane perpendicular to a concentric or spiral track, and information is recorded from the difference signal of the output of the photodetector. 2. The optical information recording and reproducing apparatus according to claim 1, further comprising means for inspecting area dropouts. 2 Boehmi' ■ A far-field image of reflected light or transmitted light from an optical recording disk is received by a photodetector having concentric or spiral tracks and a split surface in the horizontal direction, and a difference signal of the output of the photodetector is obtained. 3. The optical information recording and reproducing apparatus according to claim 1, further comprising means for inspecting dropout of the information recording area from the outside. (2) A means for controlling dropout in the information recording area based on a focus error signal detected from a photodetector in order to perform the focus control; An optical information recording/reproducing apparatus according to claim 1 or 2, comprising: