JPH06101200B2 - Optical information recording / reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for reproducing information from an optically detectable optical information recording medium.

2. Description of the Related Art In an optical information recording medium, such as an optical recording disk, which is regarded as a promising high-density and large-capacity memory, an error control technique is very important in order to overcome a low error rate of optical recording. An optical recording disc is usually provided with an optically detectable guide track such as a guide groove in order to increase the track density, and a laser focused on the recording layer formed on the guide track to about 1 μm is used. Record by irradiating with light and making holes or changing reflectance.

Since the recording dots and track pitch are about 1 μm, the manufacturing process of the optical recording disc (formation of guide track, replica disc, vapor deposition of recording material, formation of protective layer)
Alternatively, various defects, dust, and scratches may occur depending on the usage environment of the unrecorded disc, resulting in dropout of the reproduction signal. This dropout is diverse, with bursty and random occurrences occurring to the same extent. As a result, the raw error rate of the optical recording disc is 10 ^-4 to 10 ^-6.
It is said that the current error rate is much worse than the raw error rate of 10 ⁻⁹ to 10 ^{−12 of} the conventional magnetic disk, which is a typical recording medium.

Therefore, the optical information reproducing apparatus using the optical recording disc has a strong error control and also has a function of reproducing the track recorded at the time of recording and confirming whether the recording is correctly performed (hereinafter referred to as verify). Is common.

FIG. 5 is a diagram showing an example of a signal format recorded on the optical recording disc and a reproduced signal from the optical recording disc. FIG. 5a shows a signal format, 16 is an address portion previously formed in a groove structure on the guide track, and 17 is a data portion for recording / reproducing an information signal due to a change in reflectance or the like. FIG. 5b shows the formation of pits on the optical recording disk, 18 indicates the address portion, 19 indicates the data portion, and the recorded signal forms the pits indicated by the diagonal lines. FIG. 5c shows an example of a reproduction signal from the optical recording disk.

FIG. 4 shows a conventional example of an optical information recording / reproducing apparatus using the optical recording disc as described above.

Reference numeral 1 is an optical recording disk, 2 is a motor, 3 is an optical block for irradiating the optical recording disk 1 with a light beam emitted from a semiconductor laser or the like having a beam diameter of about 1 μm.
Is a semiconductor laser drive circuit for modulating and driving the semiconductor laser by an information signal input from the terminal A.
During recording, a laser beam of several mW is applied to the surface of the optical recording disk. The reproduction signal read by the optical block 3 as a signal due to the change in the reflection amount of light is amplified by the preamplifier 5. The frequency characteristic correction circuit (EQL) 6 corrects the frequency characteristic of the signal amplified by the preamplifier 5.

The reproduction signal detection is composed of two circuits. One is a signal peak detection system, which comprises a differentiating circuit (DIFF) 7, an amplifier 8, and a zero-cross comparator 9. This is a circuit for detecting the peak of the reproduction signal by setting the time constant of the differentiating circuit so that the peak point of the reproduction signal becomes zero level and comparing the signal of this output with the zero level. The other is a gate signal generation circuit to prevent the peak detection circuit from erroneously detecting the peak due to noise or the like when there is no signal. It is composed of an envelope detection circuit 10 and a binarization comparator 11. To be done. This gate signal generation circuit is provided with an envelope (6th signal) of a reproduction signal (Fig. 6-a).
Fig.-b) is detected by the envelope detection circuit 10, and the signal is attenuated at a certain rate (Fig. 6-d) and the reproduced signal is compared (clipping), and output only when the reproduced signal is large. Is a circuit that makes the high level. An example of the waveform of the output signal is shown in FIG. 6-d '. Data verification is performed by changing this clipping level. An example of the waveform is shown in FIG. 6-c, and its output waveform is shown in FIG. 6-c '. FIG. 4 shows a flip-flop for converting the PPM signal recorded on the optical recording disk into the NRZi signal, which is output from the terminal B. The waveform is shown in FIG. 6g.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As described above, the address portion of the optical recording disk is formed in advance as the presence or absence of the guide groove, that is, the concave and convex signal, and the data portion is a pit recorded as a change in reflectance etc. with laser light Therefore, the address part and the data part have different signal amplitude levels and frequency characteristics. (Generally, the address portion has a better frequency characteristic.) This is corrected by one frequency characteristic correction circuit 6 having a certain characteristic.

For example, if the frequency correction circuit is suitable for the frequency characteristics of the signal of the data section, waveform distortion occurs in the address section (22-a in FIG. 6) of the output signal of the frequency correction circuit 6. Therefore, in the optical information recording / reproducing apparatus having the above-mentioned structure, the gate signal is lost at the time of verification (Fig. 6-22-c ').
Is likely to occur. Here, even if the signal (same -f) obtained by binarizing the differential signal (FIG. 6-e) of the reproduction signal is reproduced correctly, an error occurs due to the lack of the gate signal (22- in FIG. 6). g).

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an optical information recording / reproducing apparatus capable of reducing the error rate in the address section during verification.

Means for Solving the Problems In order to solve the above problems, an optical information recording / reproducing apparatus of the present invention has an address part detecting means for distinguishing a data part from an address part, and a reproducing time and a verify time after information recording. A mode switching means for switching the mode, and by the output of the address detecting means and the combined output signal of the mode switching means,
At the time of verification, the address part and the data part are configured to perform clipping at different levels.

Operation According to the present invention, the clipping level of the address part of the data and the clipping level of the data part are switched by the above configuration, so that the clipping level at the time of verify can be set to the optimum level for both the address part and the data part. It is possible to eliminate the occurrence of errors due to other than the defects of the medium.

Embodiment FIG. 1 shows an embodiment of the present invention. In FIG. 1, the configurations of blocks 1 to 9 and 11, 12 are the same as those of the conventional example shown in FIG. 4, and detailed description thereof will be omitted. A clipping level control circuit 13 outputs a control signal for switching the output level of the envelope detection circuit upon receiving a signal indicating whether the read mode is the verify mode from the terminal c,
Reference numeral 14 denotes an envelope detection circuit capable of varying the output level of the clipping level control circuit 13 by receiving the signal from the clipping level control circuit 13; CPU). The microprocessor 15 controls the operation of the entire apparatus, and it is possible to easily send out the control signal as described above.

Regarding the optical information recording / reproducing apparatus configured as described above
The operation will be described with reference to the drawings.

First, FIG. 2A shows a signal in which the signal read by the change in the light reflection amount in the optical block 3 is amplified by the preamplifier 5 and the frequency characteristic is corrected by the frequency characteristic correction circuit 6. The address portion 22 is distorted due to the above reason. Here, a switching signal for the read mode or the verify mode is input from the CPU 15 from the terminal C of the clipping level control circuit 13 in FIG. (here,
"H" level in verify mode).

In the read mode, as shown in FIG. 2B, the re-clipping level of the address part 22 and the data part 23 is, for example, amplitude
Set to 50%. Similarly, to the terminal D of the clipping level control circuit 13 in FIG. 1, the address detection signal as shown in the waveform example of FIG. The clipping level when the circuit is in verify mode is shown in Figure 2c.
As shown in, for example, the address portion 22 is set to 60% of the amplitude, and the data portion 23 is set to 75%. A circuit example for realizing this is shown in FIG.

In FIG. 3, Di, C, R1, R2, R3, and R4 are circuit examples of the envelope detection circuit 14 whose output can be varied.

L1, L2, L3, SW1, SW2, SW3 are clipping level control circuits 13
FIG. The operation will be described with reference to FIGS. First, the reproduction signal input from the terminal E is Di, C, R1, R2, R3,
Envelope detection at R4. The detection voltage is R
It is divided by 1, R2, R3, R4. A signal of read mode or verify mode is input to the terminal C. (Here, it is set to "H" level in the verify mode). To the terminal D, as shown by 24 in FIG. 2, a signal which becomes "H" level in the address portion is inputted from the CPU 15. Where terminal C
Is at "L" level (read mode), the switch SW3 is closed when the terminal D is at "H" level or "L" level (whether in read mode or verify mode). The detected waveform is output [22,23- in Fig. 2
b].

When the terminal C is at the "H" level (verify mode), the switch SW2 is closed in the address section where the terminal D becomes the "H" level, and the detection waveform of, for example, 60% of the amplitude is output to the terminal F [Fig. 22-c] of terminal D is "L" level, switch SW
1 is closed and, for example, a 75% amplitude detected waveform is output [23-c in FIG. 2].

In this way, in this embodiment, in the verify mode, both the address part and the data part can be switched to the optimum verify level and set, and both signals can be read accurately. In particular, in the verify mode, it is possible to reduce the occurrence of errors other than the defects of the medium.

As described above, according to the present invention, by changing the clipping level in the address part and the data part of the reproduction signal, it is possible to eliminate the occurrence of an error other than the defect of the medium at the time of verification, and to prevent the recording information from being recorded. The reliability confirmation can be speeded up and stabilized.

[Brief description of drawings]

1 is a block diagram of an optical information recording / reproducing apparatus in an embodiment of the present invention, FIG. 2 is a signal waveform diagram in the embodiment, FIG. 3 is a circuit diagram of a main part in the embodiment, and FIG. Is a block diagram of a conventional device, and FIGS. 5 and 6 are waveform diagrams of signals in the conventional example. 13 …… Clipping level control circuit, 14 …… Envelope detection circuit, 15 …… CPU.

Claims (2)

[Claims] 1. An amplitude detecting means for detecting an output level of a detection signal of an optical head for reading an address portion and a data portion from an optical information recording medium and binarizing them, and generating a voltage proportional to an output of the amplitude means. A voltage generating means having a variable proportional ratio by a control signal, a binarizing means including a clipping means for comparing the output of the optical head with the output of the voltage generating means, and an address part of the output of the binarizing means. An address portion detecting means for detecting and a mode switching means for switching a mode at the time of reproducing and verifying after information recording are provided, and a combined output signal of the address portion detecting means and the mode switching means is controlled by the voltage generating means. A signal, and at the time of verifying, the clipping means compares the data section and the address section with the output of the voltage generating section in which the proportional ratio of the amplitude detecting section is different. The optical information recording reproducing apparatus according to claim. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the proportional ratio of the amplitude means at the time of verification is smaller than that of the data part in the address part.