JPS63304427A - Signal recording and reproducing system - Google Patents

Abstract

PURPOSE:To optimizingly correct a medium by providing a means detecting waveform distortion and jitter from a reproducing signal and a means comparing the detected value with an information discrimination window width and providing a variable means of the pulse width and shape of a recorded optical power and a characteristic variable means of waveform equalizer so as to execute the variable means from the result of comparison. CONSTITUTION:A recording/reproduction laser beam is collected onto a disk 1 by a pickup 3 and a detection signal is inputted to an accurate equalizer 6 via an amplifier 4 and a pre-equalizer 5. Then the binary circuit 7 binarizes the signal, the signal is separated into a data and a clock by a PLL circuit 8 and reproduced by a demodulation circuit 9. On the other hand, the distortion information is inputted to a discrimination circuit 11, and if reproduction correction is required, the control circuit 12 varies the set value of the equalizer 6 and if recording correction is required, the control circuit 13 controls the power setting circuit 14 and the pulse width setting circuit 15. The recording information is converted by a modulation circuit 16 and given to a pulse width setting circuit 15, given to a laser driver 17, the laser is modulated and corrected optimizingly for the disk to apply recording.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for recording and reproducing digital signals on a recording medium such as an optical disk, and in particular, a device for compensating the recording characteristics and reproduction characteristics of the recording medium and setting optimum conditions. This invention relates to a recording/reproducing method suitable for improving data reliability and high-density recording.

[Conventional technology]

An optical disk device is one of the means for recording digital signals on a recording medium. Optical discs use lenses to focus laser light onto the recording surface of the disc to a diameter of approximately 1 μm, and change the intensity of the laser light in accordance with the information, thereby changing the reflectance of the recording film in that area or the magneto-optical recording. In some cases, information is recorded by changing the magnetization direction. In the case of reproduction, a laser beam having an optical power weaker than that in the case of recording is irradiated, and the rotation of the polarization plane of the laser beam is detected due to the strength of the reflected light from the recording film or the difference in the magnetization direction. In such optical disk devices, when the disk rotation speed is constant, the linear velocity changes depending on the recording radial position, so it is necessary to make the recording optical power, pulse width, or pulse shape variable to obtain accurate pit shapes. is being done. In general, the shape of the recording pit depends on the recording sensitivity and thermal conductivity of the recorded value, and if the recording conditions are inappropriate, the data string to be recorded and the data string obtained from the recorded pits will not match, resulting in errors. Detection will occur. This problem similarly occurs when the disk rotational speed is made variable and the linear velocity is kept constant. In order to correct the pit shape, conventional devices employ means for changing the length of the recording bit, that is, the length of the recording light pulse. For example, in a perforated recording film, pits are formed by melting and evaporating the recording film with the heat of the laser beam, so generally pits are formed that are longer than the length of the recording light pulse. Therefore, the pit length can be corrected by recording with pulsed light having a length that is obtained by subtracting the excess pit length. but,
This correction amount is determined by measuring the recording and playback characteristics of many disks and taking into account the sensitivity fluctuation range of the recording film based on those characteristics, allowing for more accurate control of pit length as density increases. When this is required, the amount of variation in pit length cannot be ignored. Therefore, a method has been proposed in which the recording conditions are corrected each time using reproduction signals from recorded pits.

For example, in the device described in JP-A No. 61-239441,
Before recording the data to be recorded on the disk, a method is adopted in which test data is recorded in advance and the output of the light source in the recording mode is changed using the reproduced signal. Furthermore, in the apparatus described in Japanese Patent Application Laid-Open No. 61-74178, a signal of a predetermined repetition period is similarly recorded before data recording, and information for recording correction is obtained from this. For recording correction, in the former case, record optical power, in the latter case,
A method of varying the recording pulse width is used.

In the above-mentioned apparatus, actual correction is performed only by recording correction, and at the time of reproduction, correction corresponding to the recording and reproduction conditions is not performed. In other words, all characteristic deterioration caused by playback characteristics is corrected by correction during recording. The amplitude of the read signal decreases due to interference between waveforms. This decrease occurs even if the pits are accurately formed, and it is not appropriate to correct this on the recording side.

In other words, if you try to compensate for the decrease in No. 8 amplitude by recording correction, you will end up increasing the recording optical power or pulse width in order to increase the amplitude, and the pits that will be formed will become even larger and the pit spacing will become smaller than before. It gets closer than that. Therefore, the reduction in signal amplitude due to interference between waveforms becomes even more significant. This method of varying only the recording conditions based on the correction information obtained from the reproduced signal is not necessarily an appropriate method.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology attempts to correct waveform changes that occur during the reproduction process by resetting recording conditions.
In some cases, recording and reproducing characteristics may be further deteriorated.

The purpose of the present invention is to determine whether the information is attributable to the recording process or the reproduction process based on the information obtained from the reproduced signal, such as measurement results of waveform distortion and jitter amount, and based on the determination result, What occurs during the recording process is dealt with by changing at least one of the recording light power, pulse width, and pulse shape, and what occurs during the reproduction process is dealt with by changing the delay amount and/or tap gain of the waveform equalizer. The purpose is to perform correction suitable for the recording medium by changing the . This makes it possible to suppress variations in characteristics of recording media and improve data reliability. Further, as a premise for performing the above correction, it is necessary that at least focusing and track following are performed normally.

[Means for solving problems]

The above purpose has a means for detecting waveform distortion and jitter amount from a reproduced signal, and a means for comparing the detected value with a data discrimination window width, and for recording correction, the recording optical power, pulse width, and pulse shape are The means to vary the playback correction is as follows:
This is achieved by providing means for varying the equalization characteristics of the waveform equalizer and performing recording correction, reproduction correction, or both based on the above comparison results.

[Effect]

As a means of detecting waveform distortion from a reproduced signal, test data is recorded in advance on a recording film using recording light of a single frequency.
Analyze the spectrum of the reproduced signal obtained from the formed pit string after roughly correcting the reproduced signal using a pre-equalizer, detect the power of the harmonic component of the frequency of the recording light,
The amount of waveform distortion is determined from the magnitude of this component.

A pre-equalizer is used to correct the frequency characteristics of an optical disc reading system, and is essential especially for high-density recording.

As a means of detecting the amount of jitter from the reproduced signal.

For example, a PLL can be generated from a pre-built clock generation pit.
A (phase-locked loop) circuit generates a reference clock corresponding to the data discrimination window, and calculates the phase difference or time difference between this clock and the digital signal obtained from the signal after the pre-equalizer at a frequency higher than the clock frequency. This can be achieved by counting with a clock or by generating a signal with the same pulse width as the time difference and directly determining this signal width as the amount of jitter.

Further, when changing the recording light power as a recording correction means, it is sufficient to vary the power setting current of the laser drive circuit using a D/A (digital/analog) converter. or,
Regarding the recording light pulse width, the pulse width can be increased or decreased by using a delay circuit and calculating the AND or OR of the data pulse train that is not delayed and the delayed pulse train.

An automatic equalization circuit is used as the reproduction correction means.

The equalization circuit compensates for the amplitude reduction caused by interference between waveforms by narrowing the individual signal waveforms using a delay circuit and a product-sum circuit, and can be thought of as a type of filter. Parameters that determine the characteristics of this equalization circuit include the delay time and the tap gain that determines how much the signals from each tap of the delay circuit are increased or decreased when calculating the sum of products. By selecting these parameters based on control information, the reproduced waveform can be corrected. Also, the above correction requires that focusing and tracking are performed accurately, but this must be confirmed by using a window comparator to check that each error signal is within the tolerance value. Good.

〔Example〕

Examples of the present invention will be described below.

FIG. 1 is a block diagram showing the configuration of an embodiment.

In FIG. 1, an optical disc 1 is rotated by a spindle motor 2, and an optical pickup 3 focuses a laser beam for recording and reproduction onto a recording film surface on the disc 1 through a focusing lens. The optical pickup 3 can be moved in the radial direction of the disk in accordance with the information recording position. The signal detected by the optical pickup 3 is amplified to a desired level by an amplifier 4, and then input to a pre-equalizer 5, where it is roughly equalized in waveform according to the recording radius. Thereafter, the signal is input to an automatic equalizer 6 for more precise waveform equalization, and then converted into a digital signal by a binarization circuit 7. The binarized data is separated into a data signal and a clock signal by a PLL (phase locked loop) circuit 8, and reproduced data by a demodulation circuit 9.

On the other hand, the signal whose waveform has been equalized by the automatic equalizer 6 is input to the detection circuit 10, and the degree of waveform distortion is detected. This distortion information is input to the determination circuit 11, and it is determined whether the correction should be performed during the reproduction process or the recording process. If correction is required during the reproduction process, the automatic equalizer 6 is activated by the reproduction control circuit 12.
Vary the setting value. In addition, if correction is required during the recording process, the recording control circuit 13 controls the recording light power setting circuit 1.
4 and the recording pulse width setting circuit 15.

After the recording data is converted by the modulation circuit 16, it is given to the laser driver 17 through the pulse width setting circuit 15,
The recording signal is recorded on the disk 1 by modulating a laser in the optical pickup in accordance with the recording signal.

In FIG. 1, optical pickup 3. Amplifier 4゜P L
L circuit 8. Demodulation circuit 9. The modulation circuit 16 may be of a two-function configuration used in conventional optical disk devices, and its detailed explanation will be omitted.

The other components will be explained below.

FIG. 2 is a diagram showing an example of the configuration of the pre-equalizer 5.
The figure is a diagram explaining the operation. In FIG. 2, a data signal 200 amplified by amplifier 4 is transmitted to operational amplifier 2.
After being converted into a low impedance signal by a voltage follower based on 0, the signal is input to delay elements 21 and 22. Resistor 23 and resistor 24 are for matching the characteristic impedance of the delay element. Among the signals delayed by the delay elements 21 and 22, the midpoint tap signal 201 is directly input to the adder circuit constituted by the amplifier 25. On the other hand, the signal delayed by the delay element 21 is input to the analog switch 26.
One of them is selected, and this delayed signal 202 is input to the amplifier 28.

Similarly, one of the signals 203 delayed by the delay element 22 is selected by the analog switch 27 and inputted to the amplifier 28 . An adder circuit is configured by the amplifier 28, and the gain is determined by the feedback resistors 30 to 30 by the analog switch 29.
It can be varied by switching 33. The sum signal 204 of the amplifier 28 is input to the amplifier 25 together with the midpoint tap signal 201 and output as a pre-equalized signal 205.

Next, the waveform processing of the circuit shown in FIG. 2 will be explained with reference to FIG. In FIG. 3, f(t) corresponds to the input data signal 200 to the waveform equalization circuit 5 shown in FIG. In the case of an optical disc, the diameter of the recording pit is generally smaller than the diameter of the optical spot, so interference between waveforms of the reproduced signal occurs due to the influence of adjacent bits, resulting in a reduction in signal amplitude. The equalization circuit shown in FIG. 2 has the effect of compensating for the decrease in optical frequency characteristics.

In Fig. 3, f(t+τL and ((at -)) are signals obtained by delaying J(shi) at - by +τ, and are amplified by 72 times by an adder consisting of an amplifier 28, and then added. By doing so, −−(fCt+τ)+f (with −)) is obtained.

Here, this added signal is added to the original signal f(t) by the amplifier 25.
3(b) is obtained as the pre-equalized signal 205. This equalized signal has a narrower width than the original f(1), which can reduce the influence of inter-waveform interference due to adjacent bits. Parameters that determine the characteristics of the pre-equalizer 5 shown in FIG. 2 include delay time and gain K. In the delay time, the delay element 21.2 is changed by tap switching of the analog switch 26.27.
The setting can be made depending on which tap of 2 is selected. Further, the gain can be set by the ratio of the input resistance 34.35 and the feedback resistances 30 to 33. By making these settings for the disk radial position using the value of the track address on the disk, it becomes possible to compensate for changes in optical frequency characteristics. This compensation is particularly effective when the disk rotation speed is constant. That is, since the linear velocity is slower on the inner circumference than on the outer circumference, the bit intervals become closer. For this reason, the gain in the high frequency range decreases. By shortening the delay time τ and increasing the gain K as constants for the zero equalizer, the gain in the high frequency range is increased and the overall frequency characteristics are flattened. will be compensated for.

Next, the automatic equalizer 6 in FIG. 1 will be explained. Automatic equalization is the process of faithfully restoring the transmitted signal waveform by automatically removing distortion from the received signal waveform that has been distorted while passing through the transmission path. If the distortion is linear, it can be compensated by a linear filter that has the inverse characteristics of the distortion. FIG. 4 is a block diagram of a linear automatic equalizer. In FIG. 4, r(t) is the input signal to the automatic equalizer which has been frequency compensated to some extent by pre-equalization H#5. D is a delay element with a delay time of T seconds, C-n
” CN is a variable tap gain. Now, the transmission path (in the case of an optical disk device, this can be considered as the process of identifying bits from an optical disk using a light spot and converting them into electrical signals)
Let x(t) be the impulse response of

r(t) = Σ axx(t-kT) −
It is expressed as =-ψ in (1). p at time t=pT of this received signal
The th sample value is r(pT)==-+ap-2x(2T)+ap-tx(
T)+apx(0)+ap-tx(-T)+apzx(
2T)+...(2). Here, if r(pT) is equal to ap, then a.

can be obtained correctly. However, in formula 2), the data before and after aP generally disturb the relationship r(pT) = ap, and x(0) = 1 is not satisfied, so correct data cannot always be obtained. I understand that. This phenomenon is called code amount interference. The automatic equalizer in Fig. 4 attempts to eliminate code amount interference so that r(pT) = ap always holds by appropriately adjusting the tap gain Cn (n = -N, . . . N). It is something to do. That is, the output of the automatic equalizer 1 = -oo n = -111 = Σ aKh (pT kT) - (3) Knee ψ However, h (t) = Σ Cnx (t n T)
(4) When n=-N, the value of each tap gain can be selected so that the number of tap gains (2N + 1.) satisfies the following. At this time, the code amount interference is completely removed, and y (p
T) becomes equal to a. Actually, the number of taps (2N+1
) is an inflated piece, so a measure for evaluating the proximity to ap is used to minimize it.

As a measure of this, Ez=<Cy (p T) a p]”>
-(6) is used.

Equation (6) is called the root mean square evaluation, and Equation (7) is called the worst evaluation. These two evaluations can be equivalently expressed by the following evaluation functions.

However, Σ' represents the sum of infinite terms excluding 0.

Dx-Ez/<ax”>=Σ' [h(kT)]
2+[1-h(0)ko2...(8) Doo= Eoo/maxia a to l=Σ'Ihl'
r)l+1t-h(0)l...(9) Here, D2 corresponds to the root mean square distortion and Doo corresponds to the peak distortion. The automatic equalizer adjusts each tap gain to minimize E2 or Eω while actually receiving the signal. As this method, a method conventionally used in communication channels may be used, and although a detailed explanation will be omitted, a method for minimizing the root mean square evaluation E2 will be described as an example. To minimize the root mean square evaluation E2, the error size [e(kT
)]"=[y(kT)-a]2 is time-averaged using an integrator, and the maximum slope method is applied by replacing the ensemble average E2. In either method, Reduction of waveform distortion is achieved by selecting the tap gain in the same way as the pre-isograph.Here, the waveform distortion is not only a linear process but also a nonlinear process (for example, the shape of the distortion changes depending on the difference in the recording pattern sequence). etc.), it is preferable to use a nonlinear automatic equalizer as shown in FIG. 5, in which a transversal filter for equalizing the waveform and a determination circuit form a feedback loop.

Next, the binarization circuit 7 in FIG. 1 will be explained. FIG. 6 shows the simplest configuration example of the binarization circuit 7, in which the output of the automatic equalizer 6 is input to the comparator 40 as an input signal 100. The comparison reference value is set by the variable resistor 41. As a result, a binarized output signal 101 is obtained. In this example, the binarization threshold is a constant value, but this threshold may be varied depending on the inner and outer circumference of the disk or the total amount of reflected light. The digital signal binarized by such a binarization circuit is input to the PLL circuit 8, a clock synchronized with the data is generated, and the signal is sent to the demodulation circuit 9 together with the data.
The data is processed and becomes playback data.

The PLL circuit 8 and the demodulation circuit 9 may have conventional configurations.

The output of the automatic equalizer 6 is input to the binarization circuit 7 and also to the detection circuit 10. This detection circuit 10 is
Detects waveform distortion. A method for detecting waveform distortion will be explained below. Before recording user data, a repeating pattern of a single frequency is recorded in the data area, and the second harmonic level of this pattern reproduction signal is detected. If this harmonic level is greater than this value, the determination circuit 11 determines that there is a cause in the recording process, and the recording control circuit 13 is operated. On the other hand, if the harmonic level is smaller than the value, the reproduction control circuit 12 is operated and the tap gain of the automatic equalizer 6 is set.

A specific configuration example is shown in FIG. 7. In FIG. 7, the bandpass filter 42 is a filter that passes only a signal having a frequency twice the repetition frequency of the test pattern.

The configuration of this filter 42 does not need to be particularly limited, and may be a passive type composed of a capacitor and an inductor, or an active type such as an active filter. It is also possible to use a type in which the signal 102 is digitized and then numerically processed using a digital filter. In this way, an output signal 103 having only specific frequency components is obtained. This output signal 103 is input to comparators 43 and 44.

The comparison value 104 of the comparator 44 is
It is assumed that the value is set lower than the comparison value 105 of . If the second harmonic level is small and the distortion is smaller than the standard value,
Both outputs of comparators 43 and 44 are 11 HI+
It is determined that the current recording and playback conditions are within the correct range. When the output signal level 103 is higher than the comparison value 104 but lower than the comparison value 105, the control signal 106 for resetting the reproduction process becomes 'H'. Furthermore, when the output signal level 103 is higher than the comparison value 105, the recording process is stopped. The control signal 107 to be reset becomes 11 H11.The input signal 102 in FIG.
It is necessary to place a memory element composed of a flip-flop after the . Furthermore, it is necessary to input a signal to enable only the test pattern recording area. FIG. 8 shows an example of the configuration when the above functions are added.

In FIG. 8, the detection/judgment circuit 45 has a configuration as shown in FIG. On the other hand, the input signal 102 is also input to the sector mark detection circuit 46.

In this case, one track of the optical disc is divided into a plurality of sectors, and the test pattern is recorded in a data recording area within each sector. The sector mark detection signal 108 is sent to the flip-flop 47.4.
It is input to the reset R terminal of the flip-flop 8, and every time the beginning of a sector is recognized, the output Q of the flip-flop
Reset to Ln. The reproduction control signal 106 is input to the trigger T terminal of the flip-flop 47;
When the transition from "L" to "H" occurs, the output Q of the flip-flop 47 remains "'H" until the next sector is recognized.
maintain the state of This output Q109 becomes the final reproduction control signal. Similarly, regarding the recording control signal 107, the output Q110 of the flip-flop 48 becomes the final recording control signal. Now, an example of how to set the comparison values 104 and 105 will be described. For digital data, a necessary condition for error-free demodulation is that the transition point of the data falls within a certain discrimination window width determined by the modulation method used. If the recording power and recording pulse width are inappropriate during the pit formation process, that is, during recording, a situation will occur in which the discrimination window is exceeded, no matter how much waveform manipulation is performed during reproduction. Therefore, as a guideline for setting one comparison value 105, it is conceivable to experimentally determine the distortion rate at which the data transition point exceeds the discrimination window and use this. On the other hand, even if the data transition point falls within the discrimination window width, if the deviation from the center of the discrimination window is large, there is a possibility that the discrimination window width will be exceeded even for a large number of data. Therefore, in the case of waveform distortion that exceeds half of the discrimination window width, a practical method for setting the comparison value 104 is to re-set the reproduction conditions, that is, the equalization constant, as there is a problem in the reproduction process. It is true.

For example, when trying to achieve 0.5 μm/bit by 2-7 modulation on a write-once optical disc using PbTeSe as the recording film, one novel of the second harmonic is suppressed by more than 15 dB with respect to the fundamental frequency level. It has been confirmed that this is necessary for stable data discrimination.

Therefore, using the suppression ratio as a guide, the comparison value is 104.105.
All you have to do is set it. - For example, when the comparison value 104 corresponds to a suppression ratio of -20 dB and the comparison value 105 corresponds to a suppression ratio of -10 dB, the comparison value 104 corresponds to 1/10 of the amplitude of the human signal 102, and the comparison value 105 corresponds to approximately 1/3 It will be set to .

The reproduction control circuit 12 and recording control circuit 13 in FIG. 1 will be explained. The role of the playback control circuit 12 is to adjust the tap gain of the automatic equalizer 6 to the distortion expressed by equation (8) or equation (9) when the playback control signal 109 becomes "H'" in the determination circuit 11. The switch is made so that the minimum value is reached. Generally, an optical disc device has a host processing device to control an optical disc drive section. This upper-level processing device commands the movement of the optical head, records and reproduces information, and modulates and demodulates it.

Contains signal processing circuits such as error correction. Therefore, automatic equalization can be carried out by performing the necessary calculations when changing the constants of the equalizer by utilizing the calculation functions in the host processing device. The calculation algorithm may be the same as that already used in communication circuits. The role of the recording control circuit 13 is to change the recording power setting and the recording pulse width, and in this case, when the recording control signal 110 becomes "H", the power change and pulse width are changed by one step. I'll have to change it. Here, specific configuration examples of the power setting circuit 14 and the pulse width setting circuit 15 will be explained.

FIG. 9 shows an example of the configuration of the pulse width setting circuit 15. The recording data 120 modulated by the modulation circuit 16 is input to the delay element 50. The delay element 50 is provided with tap outputs for each delay amount τ, and these delayed signals are input to the selector 51. The delay data 121 selected by the selector 51 and the recording data 120 are connected to an AND circuit 5.
The original recorded data 120 is obtained by calculating the logical sum of 2.
A recording pulse 122 shorter by the delay time can be obtained. Generally, in the case of thermal recording, the generated pits are longer than the recording pulse width, so it is often sufficient to correct the pulse width only in the short direction. However, if pits shorter than the recording pulse width are formed due to the characteristics of the recording film, it is possible to change the pulse width to the original recording value by using a method of providing not only an AND circuit but also an OR circuit as shown in Figure 10. It can be longer than the data. FIG. 11 shows an example of the configuration of the power setting circuit 14 and the laser driver 17. In FIG. 11, the circuit that drives the semiconductor laser 60 is a current switch composed of NPN transistors 1 and 62.

The recording pulse 122 is an ECL (emitter coupled
logic) is input to the AND circuit 65.

The non-inverted signal and the inverted signal of the A N D circuit 65 are level-shifted by Zener diodes 66 and 67, and then input to the base of the transistor 61 and 62. In the current switch, when the transistor 61 is turned on, a current corresponding to the current value set by the transistor 63 is superimposed on the semiconductor laser 6o. The transistor 64 constitutes a current source for lighting the semiconductor laser 60 at the reproduction light level. On the other hand, the transistor 3 sets the superimposed power during recording, and applies the output voltage of the D/A (digital/analog) converter 68 to the base terminal of the transistor 63, and connects it to the emitter terminal of the transistor 63. A current equal to the potential difference between the negative potential -■ divided by the value of the resistor 69 is set. The operational amplifier 70 constitutes a voltage follower and has the effect of suppressing variations in the base-emitter voltage of the transistor 63. The recording power can be set using input bit data of the D/A converter 68.

The above is an explanation of the operation of each component in one embodiment of the present invention. Next, a method for detecting the amount of jitter from a reproduced signal will be explained. In the embodiment shown in FIG. 1, a signal with a repetition period of a single frequency is used as a recording pattern, and the harmonic level is recognized during reproduction to determine whether to apply feedback to the recording process or the reproduction process. In other words, it can be said to be a method of detecting waveform distortion and performing correction. An example of detecting the amount of jitter is shown in FIG.

FIG. 13 is a time chart showing the operation.

It is assumed that reference pit signals 300, 301, and 302 are recorded in advance at regular intervals on the disk as shown in FIG. The circuit shown in FIG. 12 is a reference pit signal binarization circuit 80 added to the circuit shown in FIG. PLL
A circuit 81 and a phase comparison +/p182 are added. In FIG. 13, from the reference pit signal generated by the binarization circuit 80 and the pulse train 306 indicating the leading and trailing edges of the data bit signal 305 generated by the binarization circuit 7 from the data bit 304, the PLL circuit 81 and P.L.
Clocks 307 and 308 are generated by the L circuit 8.

A phase comparator 82 compares the phases of both clocks and detects the amount of jitter. Note that as a method for extracting the recording/reproducing clock from the synchronization pit, Japanese Patent Application Laid-Open No. 58-185046
0 phase comparator 82, an example of which is shown by Ki-i→Kai
Its role is to detect, for example, the time difference between the rises of two clock signals having approximately the same frequency, and to generate a control signal for correction in the reproduction process if this time difference is within a certain range.

Here, the configuration of the phase comparator may be the same as that used in conventional PLL systems. FIG. 14 shows a configuration example for detecting a phase difference from two clocks 307 and 308 and outputting a correction determination signal. Moreover, FIG. 15 is an operation time chart of FIG. 14. Now the clock is 30
7 is a clock generated from the reference pit and is not affected by the recording pit, so it is assumed that it oscillates at a regular cycle.

Since the clock 308 is generated from the recorded data bits, there is a slight phase shift with respect to the clock 307 due to the pit shape as shown in the figure.The phase comparator 82 calculates the phase shift information between the two clocks. When the rising edge of the clock 308 precedes the rising edge of the clock 307, an advanced signal pulse 309 is generated. Conversely, when the rising edge of the clock 307 precedes the rising edge of the clock 308, a delayed signal pulse 310 is generated. Both signals 309,
310 is input to the enable E terminals of counters 83 and 8G, respectively, and the pulse width of this section is input to clocks 307 and 8G.
Clock ax1.3 with a sufficiently high frequency for 308
Count by +3. The outputs of the counters 83 and 86 are connected to a comparator 84.87, and further connected to a switch 85.88 for giving a set value to the comparator. than the value set with switch 85.87.
When the count value becomes large, the phase advance current signal 312
, or a delayed phase count signal 314 is generated. These count signals 312, 314 are controlled by the upper control device.
For example, the number is counted within one sector, and when the number exceeds a reference value, recording correction and reproduction correction are executed. For example, if the total data that can be recorded in one sector is 1 kilobyte, and a modulation method that requires two periods of recording/reproducing clock per bit data (for example, 2-7 modulation) is used, one sector The total number of clocks is approximately 2 kilobytes.

If the sum of the leading phase count signal 312 and the slow phase count signal 314 exceeds half of 1 kilobyte, the conditions for the recording process are reset, and if it is less than 1 kilobyte, the conditions for the reproduction process are reset. make it work. The reference value for determining this operation will be changed depending on the characteristics of the recording medium, etc., and is not limited to the above values.

The method using the clock generated from the reference pit shown here has the following meanings. That is, conventional waveform equalization of transmission lines has had various problems. If the signal is obtained from a transmission path with large waveform distortion, it will not be possible to accurately create the timing for demodulating this signal, so it can only be applied when the tolerance for waveform distortion is small, or if the clock and synchronization It was necessary to do something like send the signal through a separate transmission path. Therefore, the reference pits are effective not only for achieving the purpose of waveform equalization during reproduction, but also for accurately setting the amount of distortion for accurate recording control.

Next, as another example, a recording laser spot and a reproducing laser spot are placed on the same track with the recording spot leading, the recorded pits are immediately read out at the reproducing spot, and this signal determines whether recording or reproducing conditions are set. There is a way to determine whether to reset the . In FIG. 1, a laser is used, and during recording, the optical power is modulated in accordance with the data to increase, and during reproduction, a constant low optical power is irradiated onto the disk. Therefore, it is necessary to wait for at least one rotation of the disk in order to obtain correction information from pits once recorded. On the other hand, if two spots are used, one for recording and one for reproducing, the recording mode and the reproducing mode can be executed simultaneously, so that the correction processing time can be shortened. In the embodiment shown in FIG. 1, the photodetector that receives the light reflected from the disk by the reproduction spot is connected to the amplifier 4 and used exclusively for reproduction, and the recording spot laser is connected to the laser driver 7 and used only for recording. It can be executed by

The method of performing correction using two beams allows you to change the recording conditions while recording data, and then fix the recording conditions when they are optimal. Condition correction can be completed.

〔Effect of the invention〕

According to the present invention, the amount of waveform distortion or jitter is detected from the reproduced signal obtained from the recorded pits, and based on this result, it is determined which of the recording conditions or the reproduction conditions is inconvenient, and correction processing is performed. Therefore, compensation for the characteristics of the recording medium and compensation for the characteristics of the signal detection system can be dealt with as separate factors.

This makes it possible to optimize each recording and reproduction condition1, which has the effect of improving data reliability.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing an example of the structure of a pre-equalizer, Fig. 3 is a diagram explaining the operation of Fig. 2, and Fig. 4 is a linear diagram. FIG. 5 is a diagram showing an example of the configuration of an equalizer, FIG. 5 is a diagram showing an example of the configuration of a nonlinear equalizer, FIG. 6 is a diagram showing a mocha example of a binarization circuit, and FIG. 7 is a configuration of a detection judgment circuit. Figure 8 is a diagram showing an example of the configuration of a recording/reproduction control signal generation circuit, Figures 9 and 10 are diagrams showing a recording pulse width setting circuit, and Figure 11 is a laser driver circuit and power setting circuit. 12 is a diagram showing a configuration example for detecting the amount of jitter, FIG. 13 is a diagram explaining the operation of FIG.
FIG. 4 is a diagram showing a jitter detection circuit, and FIG. 15 is a diagram explaining the operation of FIG. 14. DESCRIPTION OF SYMBOLS 1... Optical disk, 5... Pre-equalizer, 6... Automatic equalizer, 10... Detection circuit, 11... Judgment circuit,
L4...Power setting circuit, 15...Pulse width setting circuit, 60...'A3 Cause IG+ 44 Figure y5 Figure foil 6 Figure 8 (2) fφ, /θ5le6'11 兇9 Figure leather/θ Figure so-Ji-f-j No. 61-64 Transistor No. 6, 67 No. 12 No. 13

Claims (1)

[Scope of Claims] 1. In a recording and reproducing apparatus that records and reproduces information by irradiating a light spot onto a recording medium, means for varying the shape of a recording light pulse and setting recording conditions;
After waveform equalization during reproduction, the method includes means for detecting the amount of waveform distortion or jitter and means for detecting that the optical spot is accurately reading data, and the magnitude of the waveform distortion or jitter. 1. A signal recording and reproducing method, characterized in that it is provided with means for determining whether to perform optimization of recording conditions or optimization of reproducing conditions, and performing the optimization operation. 2. In the signal recording and reproducing method according to claim 1, an automatic equalizer is used as means for waveform equalization,
A signal recording and reproducing method characterized in that when setting reproducing conditions, setting values of the automatic equalizer are varied to determine optimum conditions. 3. In the signal recording and reproducing method described in claim 1, an optical disk on which information can be erased and re-recorded is used as a recording medium, a test pattern is recorded in advance in a target data area to be recorded, and a test pattern is recorded in advance in a target data area to be recorded. A signal recording and reproducing method characterized in that the pattern is erased after generating control information for optimizing recording conditions or reproducing conditions from the reproduced signal waveform of the pattern. 4. In the signal recording and reproducing method described in claim 1, pit information for clock generation is arranged in advance at predetermined intervals in a data area on an optical disk, and when information is reproduced, information is generated from the pit information. The present invention is characterized by detecting a phase difference or a time difference between a clock generated from data and a clock generated from data, detecting the amount of jitter from this detected information, and generating control information for optimizing recording conditions or playback conditions. Signal recording and playback method. 5. In the signal recording/reproducing method according to claim 1, 2, 3, or 4, the optical head has a recording spot and a reproduction spot, and the recording spot is used as the reproduction spot. The recording spot is placed ahead of the recording spot on the recording track, the data recorded at the recording spot is read by the reproduction spot, information for setting the recording conditions is generated using this signal, and the recording conditions are immediately reset. A signal recording and reproducing method characterized by optimizing recording conditions.