JPS63239655A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To set up an optimum slice level even a waveform distortion such as a 2nd distortion exists by recording and reproducing a repeating signal with a fixed period on a part different from the data recording part of an information recording medium and determining the slice level of a data part from the recorded and reproduced signal. CONSTITUTION:The titled device is provided with means 11, 12 extracting a repeating signal with a previously determined constant period, a means 13 delaying the repeating signal, a means comparing the level of the repeating signal with that of the delayed signal, and means 16, 17 sampling the repeating signal by the level-compared output signal and holding the sampled value. The optimum slice level of the repeating signal is detected during the reproducing period of the repeating signal and the slice level is applied to a random signal such as data. Even if a signal includes many 2nd distortion, and effective slice level can be set up.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an information recording/reproducing apparatus for recording and reproducing signals on an information recording medium.

BACKGROUND OF THE INVENTION Conventional information recording and reproducing devices include, for example, Japanese Patent Application Laid-open No. 1983-
It is shown in Japanese Patent No. 186216.

FIG. 4 shows a block diagram of this conventional information recording and reproducing apparatus, in which 1 is an information recording medium, 2 is a reproduction needle for reproducing information on the information recording medium 1, and 3 is a high frequency reproduction signal. Equalizer for component compensation, 4 is a comparator for converting the reproduced signal into a digital signal, 6 is a buffer 7 amplifier, 6 is an integration circuit, 7 is a gain amplifier whose output is the comparator 4
Negative feedback is given to the input. 8 is a demodulator, and 9 is an output terminal.

In the conventional information reproducing apparatus configured as described above, first, the information recorded on the information recording medium 1 is transferred to the reproducing needle 2.
picks it up. The equalizer 3 performs high frequency compensation on this signal,
input to comparator 4. Comparator 4 uses the other input as a slice level to waveform shape the reproduced signal (2
value).

The output signal of the comparator 4 is input to a demodulator 8 and a buffer amplifier 6. The signal demodulated by the demodulator 8 is sent to an output terminal 9. The signal input to the buffer amplifier 6 is sent to the integrator 6, where the average value is determined, and the signal is amplified by the gain amplifier 7, which becomes the slice level of the comparator 4.

Here, a reproducing needle is used as the reproducing means, but an optical means such as an optical disc can be similarly constructed.

Problems to be Solved by the Invention However, in the above configuration, the recorded information is required to be a DC-free signal (no or very little DC component).

For example, on a compact disc (CD), which is known as an audio playback device, E F M (Eight to
Fourteen Modulation) is used as the modulation method, and information reproduction is performed in the same way as in the conventional example. However, if there is waveform distortion such as 2nd distortion, the average value of the reproduced signal will not be the optimal slice level, and even with a DC-free modulation method such as EFM, the slice level will be 2nd distortion. It is subject to fluctuations depending on the signal pattern including. The slice level is the reference level for waveform shaping of the reproduced signal whose band is limited by the recording and reproduction characteristics, so its fluctuations lead to signal time axis jitter and margin deterioration during data demodulation, thereby reducing information The problem was that the number of errors increased. Furthermore, when the information recording medium is an optical disk, means for correcting 2nd distortion caused by the thermal sensitivity characteristics of the medium during recording has been proposed, for example, in Japanese Patent Application Laid-Open No. 60-83234. (The difference between the inner circumference and the outer circumference is remarkable), so it is necessary to correct each time when recording, and it is not a very effective means. It is an object of the present invention to provide an information recording/reproducing device that is capable of reproducing a digital signal in good quality even when there is waveform distortion such as distortion, and in which the modulation method used for information recording is not limited to DC7'J-. do.

Means for solving the problem: means for extracting a repeating signal with a predetermined period, means for delaying the repeating signal, means for comparing the levels of the repeating signal and the delayed signal, and outputting the same; The information recording and reproducing apparatus includes means for sampling a signal with the output signal whose level has been compared and holding the value.

According to the present invention, with the above-described configuration, the optimal slice level of the repetitive signal is detected during the reproduction period of the repetitive signal, and the optimal slice level of the repetitive signal is applied to a random signal such as a slice level quotator, thereby detecting a signal with a large amount of 2nd distortion. It is possible to set a good slice level even for signals.

Embodiment FIG. 1 shows a configuration diagram of a reproducing portion of an information recording/reproducing apparatus of the present invention. In Fig. 1, 1° is an input terminal into which a reproduced signal from an information recording medium is high-frequency compensated by means such as waveform equalization, and 11 is a section in which a repeating signal with a constant period is recorded. 12 is a switch that selects the repetition signal and other data parts, 13 is a delay line that delays by a certain amount of time, and 14 is a signal that compares two differential input signals and converts them into digital signals. 15 is a buffer amplifier; 16 is a sample-and-hold pulse generation circuit 17 is a sample-and-hold circuit that samples and holds the DC level of the buffer amplifier output signal with a sample input signal; A comparator 19 is an output terminal for outputting a final digital signal.

The operation of the information recording/reproducing apparatus of the present invention configured as described above will be explained with reference to FIGS. 2, 3, and 4.

FIG. 2 shows an example of the format of a signal recorded on a recording medium. Before recording data 41, a repeating signal 4o of a constant period, which will be described later, is recorded. This repeating pattern has a fixed period, and when the bar of that period moves in the time axis direction, the signal level cancels (DC
is zero). An example is shown at 50.60 in FIG. Now, the signal recorded on the recording medium is
After being reproduced from the reproducing element in the order shown in FIG. 2 and subjected to waveform equalization to compensate for high-frequency components, the input terminal 10 shown in FIG.
is input. This reproduced signal is input to the input terminal 1Q and then input to the switch 12.

The switch 12 is turned on by the gate signal 42 input from the gate signal input terminal 11 so that the repetitive signal is input to one input terminal of the delay line 13 and the comparator 14 only during the period when the repetitive signal is being reproduced.
, OFF controlled.

Now, consider the operation during playback of this repetitive signal.

When a repetitive signal shown in the waveform 50 having a constant period t1 is recorded on a recording medium such as an optical disk, upon reproduction,
A signal with 2nd distortion as shown in waveform 51 is reproduced. The main cause of reproduced waveforms having 2nd distortion is insufficient sensitivity of the material of the recording medium. When this repeating signal is employed, the delay amount of the delay line 13 is set to a time corresponding to the repeating period t1 (7) bar. The output signal of the delay line 13 has a waveform 52 and is input to the (4) terminal of the comparator 14. As mentioned above, the same signal as the input signal of the delay line 13 is input to one (→ terminal.If the (4) terminal of the comparator 14 is
C voltage ■. When fixed at , the level shown by . in the waveform 51 becomes the comparison level. In the configuration of the present invention, the output signal of the comparator 14 is
A 750% square wave is obtained.

Next, consider the case of the waveform 6o with a constant period t2.

Similarly, a delay of t2/2 is performed by the delay line 13. The playback signal of waveform 61 is input to the (→ terminal) of the comparator 14.
A reproduced signal of waveform 62 is input to the terminal, the levels are compared, and a binarized digital signal of waveform 64 is reproduced. Similarly, if the (→ terminal of the comparator 14 is fixed at a constant DC voltage v0), the level shown in waveform 61 will not be the comparison level of the reproduced signal input to one (→ terminal, as shown in waveform 63). As a result, a reproduced output with a duty different from the original recording signal is obtained.The output signal of the comparator 14 is input to the sample-and-hold pulse generator circuit 16; Since the gate signal is also input to the gate signal, only the IT Hll section of the gate signal, that is, the section where the repetitive signal is input to the delay line 13, becomes the sample-and-hold pulse of the sample-and-hold circuit 17.The analog input of the sample-and-hold circuit As, delay line 13
The output signal of is inputted via the buffer angle 15.

The output delay time of pad 7a/g 15 is determined by comparator 1.
4 and the delay time of the sample-and-hold pulse generating circuit 16, so that the hold timing is exactly at the vl level after sampling. This sample-and-hold pulse is generated by the sample-and-hold pulse generating circuit 16, and its timing is as shown in a waveform 66. For example, the sample starts at the rising edge and is held at the falling edge. In the case of waveform 66, a sample and hold pulse is generated at each edge of output signal 64 of comparator 14, but either edge may be used. The pulse width t3 is determined by the performance of the sample and hold circuit. Even if a signal is repeatedly reproduced with waveform distortion in this way, the comparator 14 follows the waveform distortion according to the magnitude of the waveform distortion and generates correct sample and hold timing. Therefore, this sampled DC level is the (-) of the comparator 18.
On the other hand, data 41 selected by the switch 12 is input to the (+) terminal, and the optimum slice level is set. As mentioned above, even if the magnitude of waveform distortion changes, it is automatically set. An example of a change in waveform distortion is, for example, the magnitude of 2nd distortion on the inner circumference and outer circumference of a disk-shaped recording medium rotating at a constant speed. However, even in this case, according to the present invention, the slice level of the data portion is automatically set. Finally, the digital output of the hump parator 18 is outputted from the output terminal 19 and inputted to the subsequent demodulation circuit.

To select the 9-repetition signal, a DC-free pattern with a constant period suitable for the present invention may be used, such as waveform 6o in FIG.
A rectangular wave with a constant repetition period as shown in Figure 1 is sufficient, and it does not depend on the type of modulation method. However, the repetition period is an integral multiple of the detection window width Tw, which is a parameter of the modulation method.

Effects of the Invention By recording and reproducing a repetitive signal with a constant period in a part of an information recording medium separate from the data recording part, and determining the slice level of the data part from this signal, it is possible to eliminate waveform distortion such as 2nd distortion. You can also set the optimal slice level. In addition, even when the magnitude of 2nd distortion changes depending on the radius, such as with a disk-shaped recording medium, it is automatically set.
Since good data reproduction is possible, its practical effects are great.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the reproducing section of the information recording and reproducing apparatus of the present invention, FIG. 2 is an explanatory diagram of the realized signal 7-ormat, FIG. 3 is an explanatory diagram of an example of a repetitive signal, and FIG. 1 is a block diagram of the configuration of a conventional information recording device. 12...Switch, 13...Delay line,
14... Comparator, 15... Buffer 7 amplifier, 16... Sample hold pulse generation circuit, 17... Sample hold circuit, 1
8...Comparator. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
figure

Claims (2)

[Claims] (1) A device for recording and reproducing information on a recording medium, which includes means for extracting a repetitive signal with a predetermined period, means for delaying the repetitive signal, and level comparison between the repetitive signal and the delayed signal. means for performing waveform shaping, means for sampling based on the waveform-shaped signal of the repetitive signal and holding the value, and means for performing waveform shaping by setting the hold voltage at a slice level. Information recording and reproducing device featuring features. (2) The information recording and reproducing apparatus according to claim 1, wherein the delay time of the means for delaying the repetitive signal is 1/2 of the cycle of the repetitive signal.