KR100281784B1 - Magneto-optical recording device - Google Patents

Abstract

A magneto-optical recording device and a magneto-optical reproducing apparatus for irradiating recording information by irradiating a recording light beam to the magneto-optical recording medium in response to the recording light, and for generating a pit on the magneto-optical recording medium, and reproducing light beam to irradiating the pit on the magneto-optical recording medium In the apparatus, since a recording light beam is intermittently emitted in a light irradiation period in which a pit is formed on a magneto-optical recording medium among the recording signals, an almost circular-shaped pit can be formed on the magneto-optical recording medium, thereby Information can be recorded with high accuracy on a magneto-optical recording medium.

Description

Magneto-optical recording device

1 is a perspective view schematically illustrating magneto-optical recording.

2A to 2F are signal waveform diagrams for explaining the conventional magneto-optical recording method.

3A and 3B are characteristic curve diagrams illustrating a tear drop shape phenomenon in a magnetic region.

4 is a characteristic curve diagram illustrating the water droplet shaping phenomenon of a magnetic region.

5A to 5G are signal waveform diagrams showing principles of the magneto-optical recording method according to the present invention.

6 is a block diagram showing a magneto-optical recording device constituting the first embodiment to which the magneto-optical recording method according to the present invention is applied.

7 is a block diagram of a magneto-optical reproducing apparatus that constitutes the first embodiment to which the magneto-optical recording method according to the present invention is applied.

FIG. 8 is a connection diagram showing a detailed configuration of a pulse modulation circuit of the magneto-optical recording device of FIG.

9A to 9F are signal waveform diagrams showing signals of respective portions of the pulse modulation circuit.

Fig. 10 is a block diagram showing the magneto-optical recording device of the second embodiment.

FIG. 11 is a connection diagram showing a detailed configuration of a delay circuit of a write signal forming circuit of the magneto-optical recording device of FIG.

FIG. 12 is a connection diagram showing a detailed configuration of a synthesis circuit of a write signal forming circuit of the magneto-optical recording device of FIG.

13A to 13Q are signal waveform diagrams showing signals of respective portions of FIGS. 11 and 12.

14A to 14Q are signal waveform diagrams following the right portion of the signal waveform diagram of FIGS. 13A to 13Q.

Fig. 15 is a block diagram showing the magneto-optical recording device of the third embodiment.

Fig. 16 is a block diagram showing the magneto-optical reproducing apparatus of the third embodiment.

17A to 17C are signal waveform diagrams showing signals of respective portions of the magneto-optical recording apparatus and the magneto-optical reproducing apparatus of FIGS. 15 and 16;

FIG. 18 is a characteristic curve diagram illustrating a part of each of the magneto-optical regeneration apparatus of FIG. 12. FIG.

<Explanation of symbols for main parts of drawing>

10: magneto-optical recording disk 11: magneto-optical recording device

12: magneto-optical playback device 21: A / D converter

25 time division multiplexer 29 internal encoder

31 synchronous address addition circuit 32 two-phase coding circuit

32: pulse modulation circuit 53: optical head processor

54: two-phase decoder 61: internal error correction circuit

62: desuppling circuit 63: external error correction circuit

64: error modulation circuit 65: D / A converter

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a magneto-optical recording apparatus and a magneto-optical reproducing apparatus, and more particularly, to a magneto-optical reproducing apparatus in which a pit, which is a magnetic domain having a shape corresponding to recording information, is formed in the magneto-optical recording medium. It relates to a device that is well applied.

In the magneto-optical recording and reproducing apparatus as shown in FIG. 1, the recording light beam 3 including the magnetizing flux 2 and the laser luminous flux rotates in the direction of an arrow "a". The magneto-optical recording disk 1 is irradiated as a magneto-optical recording medium, and the irradiation area of the recording light beam 3 is heated to a prescribed temperature (curie point temperature) or higher, thereby constituting the pit 4. The magnetic area is formed with an irradiation area, and thus information is recorded by the length of the pit 4 and / or the timing (or recording position) forming the start end and end end.

In the recording light beam generator 5 for generating the recording beam 3 based on the recording source signal S1 of one bit period T _G as shown in FIG. 2A, for example, an NRZ conversion system. The data is converted into a code signal by using _C , a channel code signal S2 of bit period T _C (= T _G / 2) is formed as shown in FIG. 2B, and the channel code signal S2 of When the bit data enters the interval of the logic " 1 " data, a write signal S3 having a logic level that varies in timing delayed by the delay time T _R (= T _C / 2) is shown in Fig. 2C. Is generated together.

For example, the light source including the laser diode is driven by the recording signal S3, whereby the timing of the recording signal S3 in which the recording light beam 3 emitted from the laser light source rises to a logic "1" level. Is irradiated to the magneto-optical recording disk 1 in the. As a result, a pit 4 including a magnetic region as shown in FIG. 2D is formed on the magneto-optical recording disk 1.

Therefore, the formation position of the start end 4A of the pit 4 corresponds to the predetermined logic " 1 " bit data between the bit data of the channel code signal S2, and the end end 4B is subsequently generated logic " Corresponds to 1 "data. Therefore, the recording end representing the channel code signal S2 is determined by the length between the start end 4A and the end end 4B of the pit 4 or the positions of the start end 4A and the end end 4B. It can be recorded on the magneto-optical recording disk 1 as a magnetization pattern.

As shown in FIGS. 2E and 2F corresponding to FIGS. 2C and 2D, the timing of the channel code data S2 in which the write signal S3 having a predetermined pulse width becomes logical " 1 " data. A method of forming the pit 4 which occurs in (Fig. 2e) and which at any time comprises a separated magnetic region can also be used.

But. In this case, the shape of the magnetic region constituting the pit 4 formed on the magneto-optical recording disk 1 is actually tapered toward the tip of the starting end 4A (so-called droplet shape). As a result, when the pit 4 is reproduced, there is a fear that a data error occurs in the reproduced signal corresponding to the start end 4A.

In addition, since the width of the magnetic region becomes narrow toward the tip of the starting end 4A of the pit 4, the leakage magnetic flux generated from the magnetic region is weakened. As a result, the actual starting position of the starting end 4A cannot be reproduced clearly.

The reason why the pit 4 becomes a droplet shape at the start end 4A is that, when the light beam 3 starts irradiation, the magneto-optical recording disc 1 proceeds in the traveling direction "a", whereby the tip This is because the cumulative amount of light of the laser light irradiated to the portion is insufficient compared to the next rear portion following the tip portion. The temperature distribution of the magnetic region on the magneto-optical recording disk 1 irradiated by the recording light beam 3 is larger in the case of long irradiation time than in the case of short irradiation time as shown in FIGS. 3A and 3B. It was confirmed by experiment that the distribution of droplet shape.

In addition, in the case of Fig. 3B, the shape of the magnetic region when the recording light beam 3 is continuously irradiated for 300 [ns] is shown. In this case, the shape of the isothermal line becomes a remarkable droplet shape, and therefore, the shape of the isothermal line at the temperature representing the cue point also becomes a clear droplet shape.

In contrast, when the irradiation time of the recording light beam 3 becomes almost 1/3, that is, 100 [ns], the droplet shaping phenomenon of the isothermal line cannot be advanced much. As shown in FIG. 4, the degree of asymmetry of the temperature (heat) distribution tends to become apparent as the irradiation time becomes longer.

When the recording light beam is irradiated, the temperature rise generated at the position (x, y, z) of the magneto-optical recording disk 10 by thermal diffusion can be expressed by the following formula (1).

G (xx ₀ , yy ₀ , z, tt ₀ )

Q (x ₀ , y ₀ , t ₀ ) dx ₀ dy ₀ dt ₀ ... (1)

This is a convolution of the green function G and the power distribution function Q. If the pulse width of the recording signal S3 increases, the influence of thermal diffusion becomes significant correspondingly. , The asymmetry of the heat diffusion increases, and the shape of the water droplets becomes clear.

In order to prevent water droplets in the magnetic region, the pit can be formed by controlling the intensity of the laser power of the recording light beam forming the tip of the pit 4. However, bit separation at the reproduction side is not perfect, and this method is still insufficient as a solution of the problem.

In view of the above-described problems in the prior art, an object of the present invention is to avoid the possibility that an error in reproduced data may occur based on the droplet shaping phenomenon of recorded pits when information is recorded and reproduced on a magneto-optical recording medium. It is to provide a magneto-optical recording device and a magneto-optical reproducing apparatus which can be effectively avoided.

In the aspect of the present invention for solving the problem, the recording light beam is irradiated to the magneto-optical recording media 1 and 78 in response to the recording signals S13 and S73 to fit the magneto-optical recording media 1 and 78 to the pits 4. In the magneto-optical recording apparatus in which 80 is formed, the recording light beam is intermittently generated in the form of a pulse, whereby the pits (4,80) are arranged so that magnetic regions in a substantially circular shape are sequentially overlapped or separated. Is formed.

In another aspect of the present invention, a magneto-optical recording device in which a recording light beam is irradiated to the magneto-optical recording medium 78 in response to the recording signal S73 so that the pit 80 is formed on the magneto-optical recording medium 78. In the recording light beam, the recording light beam is intermittently generated in response to the period of the carrier signal, whereby a pit 80 indicating the frequency modulation information is formed, and recording corresponding to the start end portion and the end end portion of the pit 80 is performed. The light beam is generated in a separated pulse shape so that the magnetic regions are arranged in a substantially circular overlapping manner and a pit portion is formed.

In another aspect of the present invention, a recording light beam is irradiated to the magneto-optical recording media 1 and 10 in response to the recording signals S13 and S90, so that the pit 80 is applied to the magneto-optical recording media 1 and 10. In the magneto-optical reproducing apparatus which is formed and the reproduction light beam 51 is irradiated to the pit 4 on the magneto-optical recording media 1 and 10 so that the recording information is reproduced, the recording light beam 36 is in the form of a pulse during recording. Pit 4 is formed so as to be intermittently generated, and the magnetic regions overlap and are arranged in a substantially circular shape, and the reproduction information 95 obtained by irradiating the pit 4 with the reproduction light beam 51 during reproduction is given. Multi-value reproduction is performed.

If the recording light beam is intermittently generated in the form of a pulse, an almost circular magnetic region can be formed on the magneto-optical recording medium 1, 78, whereby a pit formed in the magneto-optical recording medium 1, 78 is formed. The shape of (4) may be formed in a shape that is not a drop shape.

Therefore, the degradation of the quality of the recording information generated in the droplet shape can be prevented.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

(1) Principle of the magneto-optical recording method

In the magneto-optical recording method according to the present invention as shown in Figs. 5a to 5g corresponding to Figs. 2a to 2f, the recording source signal (via the channel code signal S2 (Fig. 5b)) Although the recording signal S13 (FIG. 5C) formed on the basis of S1 (FIG. 5A) is not used as the drive signal in its original state, as shown in FIG. 5D, the recording signal S13 is sampled by The driving pulse signal S14 obtained is generated every predetermined sampling period T _S (for example, T _S = T _C ).

In this case, the pulse width T _P and the pulse amplitude P _H of the drive pulse signal S14 are recorded when the laser light radiation source is excited by each pulse of the drive pulse signal S14. ), The pits 4 formed on the magneto-optical recording disc 1 are selected to have a value of almost circular shape.

Thus, as shown in FIG. 5E, on the magneto-optical recording disk 1, while the recording signal S13 rises to a logic " 1 " level, the nearly circular pit 4 is subjected to the sampling period T _S. Is formed every time. In contrast, the drive pulse signal S14 is not generated while the signal level of the write signal S13 falls to the logic " 0 " level, so that the pits 4 are not formed as shown in FIG. 5E.

In the case of this embodiment, since the sampling period T _S is selected to be close to the bit period T _C of the channel code signal S2, the pit 4 has a series of substantially circular magnetic regions separated from each other. And arranged in rows of pit.

In the configuration as shown in FIGS. 5D and 5E, since the pit 4 corresponding to the recording signal S13 is formed in the magneto-optical recording disk 1, the recording signal S13 is a logic " 1. While at the level, rows of magnetic regions formed by circular pits 4 separated from one another can be formed sequentially.

As a result, while the recording signal rises to the logical " 1 " level, since the arrangement number (i.e., the arrangement length) of the pits 4 formed to be arranged in a series of pit rows is determined, the recording signal S13 is to be reproduced. Can be.

Further, since the recording position of the pit 4 can be determined when the recording signal S13 rises or falls, the recording signal S13 can be reproduced from the magneto-optical recording disk 1.

In this case, the sampling period T _S can be selected at any period as needed, and if this sampling period is selected to be a value that gradually becomes smaller according to this selection, the write signal S13 is at a logic " 1 " level. Since the number of pits 4 generated during the ascension increases, the distance between the magnetic regions having an almost circular shape becomes narrow. However, as long as each pit 4 is separated, the shape of the pit 4 becomes a substantially circular shape similar to the case shown in FIG. 5E.

Further, as shown in FIGS. 5F and 5G, when the sampling period becomes shorter until the respective magnetic regions constituting the pit 4 overlap with each other, the magnetic region in the recording start state is followed. For the coming magnetic area, the recording width becomes slightly wider under the influence of the heating effect in the magnetic area immediately before this magnetic area. In this case, the magnetic region at the tip side is formed under almost the same state of the state of the separated pit, and becomes almost circular.

As a result, also in FIGS. 5F and 5G, the reproduction signal corresponding to the recording signal S13 can be reliably reproduced.

(2) First embodiment

6 and 7 show the first embodiment for recording and reproducing digital information on the magneto-optical recording disk 10 based on the principle of the magneto-optical recording method as described above with reference to FIGS. 5A to 5G. The magneto-optical recording device 11 and the magneto-optical playback device 12 are shown. In the magneto-optical recording device 11, the video input signal S21V received at the analog / digital converter 21 is appended with an external error correction code at the external encoder 22, and then the suffling circuit 23 A shuffling process is performed at, and the digital data obtained at the output stage is subjected to a process of adding an internal error code at the internal encoder 24, and supplied to the time division multiplexer 25 as video data S22V.

In addition, in the magneto-optical recording device 11, the audio input signal S21A received at the analog / digital converter 26 is converted into a digital signal, and an external error code is added at the external encoder 27, and then. The suffling process is performed in the suffling circuit 28, and the digital data obtained at the output terminal is added with an internal error code at the internal encoder 29, and supplied to the time division multiplexer 25 as audio data S22A.

In the magneto-optical recording device 11, the video data S22A and the audio data S22B are time-division synthesized in a predetermined format in the time division multiplexer 25, and the synthesized signal S23 is subjected to the synchronization address addition circuit (if necessary). 31, a synchronization signal and an address signal are added, and then, in the two-phase coding circuit 32, converted into a write source signal S24 including a two-phase code signal having a different period corresponding to the signal level of the digital data. The converted signal is supplied to the pulse modulation circuit 33.

Based on the write source signal S24 in which the write source signal S13 as described above with respect to FIG. 5A includes a similar signal, the pulse modulation circuit 33 is as described above with respect to FIGS. 5D and 5F. Generate a drive pulse signal S25 including a signal similar to the same drive pulse signal S14, the drive pulse signal S25 being passed through the optical head processor 34, the light source 35 including a laser diode Is irradiated to the magneto-optical recording disk 10 as a recording light beam 36 from the.

In the case of the present embodiment, as shown in FIG. 8, the pulse modulation circuit 33 causes the recording source signal in the channel code converter 41 in a manner similar to that described above with reference to FIGS. 5A through 5C. S24 is converted into a write signal S41 (Fig. 9A) having a predetermined rise in response to the write information, and the write signal S41 is supplied to the AND circuit 42 as the first input signal.

In addition, the pulse modulation circuit 33 delays the clock pulse S42 (FIG. 9B) in the clock delay circuit 43, thereby delaying the first and second delayed clock pulse signals by the delay time τ ₁ and τ ₂ . S43 and S44 are generated, respectively, and the first and second delayed clock pulse signals S43 and S44 are synthesized in the OR circuit 44 to generate a synthesized clock pulse signal S45 (Fig. 9E).

In this case, the first and second delayed clock pulse signals S43 and S44 are formed such that the clock pulse signals S42 are sequentially delayed by delay times τ ₁ and τ ₂ , so that the delayed clock pulse signals S43 and S44) is transmitted. Therefore, the synthesized clock pulse signal S45 (Fig. 9E) rises at a time delayed by the delay time τ ₁ from the rise time of the clock pulse signal S42, and is determined based on the delay time τ ₂ . Has a width. As a result, in order to obtain the drive pulse signal S25, the rising timing and the pulse width can be set as necessary.

The synthesized pulse signal S45 is supplied to the AND circuit 42 as the second input signal, so that the synthesized clock pulse signal S45 generated during the rise of the write signal S41 to the logic " 1 " level is a drive pulse signal. (S25) (FIG. 9f).

Therefore, in the pulse modulation circuit 33, the drive pulse signal S25 having the number of pulses corresponding to the rising period of the write signal S41 at the logic " 1 " level is supplied to the optical head processor 34.

According to the magneto-optical recording device 11 of FIG. 6, the light source 35 is not directly illuminated by the recording signal S41 (FIGS. 8 and 9) formed based on the recording source signal S24. However, since the pulse modulation is performed on the drive pulse signal S25 generated in a predetermined period, and the light source 35 is intermittently driven by the drive pulse signal S25, the magneto-optical recording disc 10 An almost circular magnetic region can be formed at the start end of the pit 4 formed in the ridge 4, so that the recording information of the start end of the pit 4 can be recorded correctly.

When the recording information is reproduced from the pit 4 formed on the magneto-optical recording disk 10 in this manner, the magneto-optical reproducing apparatus 12 (FIG. 7) causes the magneto-optical recording disk ( The light beam 51 reflected from 10 is received, and the light beam 51 reflected by the two-phase decoder 54 through the optical head processor 53 is decoded and supplied to the sync address decoder 55.

Therefore, the synthesized signal S51, which is a signal similar to the synthesized signal S23 obtained at the output terminal of the time division multiplexer 25 of the magneto-optical recording device 11, can be obtained at the output terminal of the sync address decoder 55, and synthesized. The video data included in the signal S51 is subjected to error correction processing in the internal error correction circuit 56, then de-suffling processing in the desuffling circuit 57, and external in the external error correction circuit 58. The error correction process and the error correction process in the error correction circuit 59 are transmitted as the video output signal S52A through the digital / analog converter 60.

At the same time, the audio data contained in the synthesized signal S51 also has an internal error correction circuit 61, a desuffling circuit 62, an external error correction circuit 63, an error correction circuit 64, and a digital / analog converter 65. Through the audio output signal S52V.

Therefore, in the magneto-optical reproducing apparatus 12, the recording information can be reproduced from the pit 4 formed in the magneto-optical recording disk 10. In this configuration, the shape at the start end of the pit 4 is As it is not made in the shape of a water droplet as in the prior art, it is possible to significantly reduce the risk of error from the start end.

(3) Second Example

FIG. 10 shows a second embodiment in which an input signal is modulated with FM modulation and recorded on a magneto-optical recording disc, thereby recording analog information.

In FIG. 10, the input signal S71, which is analog information, is subjected to frequency modulation (FM modulation) of a carrier of a predetermined frequency in the FM modulation circuit 71, so that the amplitude of the resulting FM modulated signal S72 is An FM write signal S73 having a nori level that is limited at the limiter 72 and that changes at the zero crossing point is formed as shown in FIGS. 13A and 14A.

The FM write signal S73 is supplied to the write signal forming circuit 75 composed of the delay circuit 73 and the synthesis circuit 74, and the write signal S74 obtained at the output terminal thereof is the write circuit 76 and the light source 77. Is recorded on the magneto-optical recording disk 78 via the &quot;

The delay circuit 73 as shown in FIG. 11 includes eight delay elements DN4, DN3, DN2, DN1, DP1, DP2, DP3, DP4 connected in series with a delay time [tau], As shown in FIGS. 13B to 13J and 14B to 14J, the delay signal FM (-4) to be the FM recording signal S73 at the input terminal (FIGS. 13B and 14B). ), Delay signals FM (-3) (FIGS. 13C and 14C), [FM (-2)] (FIGS. 13D and 14D), [FM (-1) (FIGS. 13E and FIG. 14E), [FM (0)] (FIGS. 13F and 14F), [FM (+1)] (FIGS. 13G and 14G), [FM (+2)] (FIGS. 13H and 14h). [FM (+3)] (FIGS. 13I and 14I) and [FM (+4)] (FIGS. 13J and 14J) are sequentially generated at timings delayed by the delay time [tau].

As a result, the timing generated by the nine delay signals FM (-4) -FM (+4) is delayed from the rising timing of the FM write signal S73, that is, the delay signal FM (-4). The central delay signal FM (0) rising at the time t _F delayed by the time 4τ and falling at the time t _R delayed by the delay time 4τ from the falling timing of the delay signal FM (-4). )], A delay signal group S75 including four delay signals sequentially arranged in both the forward side and the reverse side in time relation is supplied to the synthesis circuit 74 as an output of the delay circuit 73. have.

The synthesizing circuit 74 as shown in FIG. 12 inverts each of the delay signals FM (-4)-FM (+4) and inverts the delayed signals [FMX (-4)-FMX (+4)]. Has an inverter [IN (-4)-IN (+4)] to obtain these delay signals [FM (-4)-FM (+4) and FMX (-4)-FMX (+4)]. An AND operation and an OR operation are executed so that, in the vicinity of the rising and falling of the central delay signal FM (0), a plurality of time positions are symmetrical with respect to the center position of the rising interval of the central delay signal FM (0). A pulse waveform is generated.

That is, the AND circuit AN1 performs an AND operation between the central delay signal FM (0) and the inverted delay signal FMX (+1), as represented by the following formula (2), to obtain the 13k degree. And at the rising timing of the central delay signal FM (0) (FIGS. 13F and 14F) as shown in FIG. 14K, a first forward separation pulse FR1 rising during the delay time τ is formed. .

FM (0) FMX (+1) = FR1 ... (2)

The AND circuit AN2 performs an AND operation between the delayed signal FM (+2) and the inverted delayed signal FMX (+3), as represented by the following formula (3), to obtain the 13L and 13th degrees. A second forward separation pulse FR2 that rises during the delay time tau is formed by elapse of time τ from the fall of the first separation pulse FR1 as shown in FIG. 14L.

FM (+2) FMX (+3) = FR2 ... (3)

The AND circuit AN3 performs an AND operation between the central delay signal FM (0) and the inverted delay signal FMX (-1), as represented by the following formula (4), to form the 13th and 13th degrees. As shown in Fig. 14m, a first rearward separation pulse RR1 is formed which has a rising width of the time τ and descends at the falling timing of the central delay signal FM (0).

FM (0) FMX (-1) = RR1 ... (4)

The AND circuit AN4 performs an AND operation between the delay signal FM (-2) and the inverted delay signal FMX (-3) as expressed by the following formula (5), so that the 13th and 14n operations are performed. As shown in the figure, a second rearward separation pulse RR2 is formed which has a pulse width and descends in time ahead by the time τ from the rise of the first rearward separation pulse RR1.

FM (-2) FMX (-3) = RR2 ... (5)

The AND circuit AN5 performs an AND operation between the delay signals FM (-4) and FM (+4), as represented by the following formula (6), as shown in FIGS. 13o and 14o. , A central continuous pulse that rises at a time backward from the fall of the second forward separation pulse FR2 by a time τ and falls at a time forward by the booster time τ due to the rise of the second rear separation pulse RR2; (CTR) is formed.

FM (-4) ・ FM (+4) = CTR ... (6)

The OR circuit ORO includes the first and second front separation pulses FR1 and FR2 and the first and second rear separation pulses RR1 obtained from the AND circuits AN1 to AN5 as represented by the following formula (7). And RR2) and the OR operation of the central continuous pulse CTR, so that the rise time t _F -fall time of the central delay signal FM (0) as shown in FIGS. 13p and 14p. In the interval of (t _R ), a central continuous pulse CTR is generated at a nearly central time position, and two forward separation pulses FR2 and FR1 at its front side and two rear separation pulses RR2 at its rear side. And a write signal S74 forming RR1 is obtained, and this write signal S74 is transmitted from the synthesizing circuit 74.

S74 = FR1 + FR2 + CTR + RR2 + RR1 ... (7)

In the above-described configuration, the FM modulated signal S72 modulated by the input signal S71 in the FM modulator 71 is provided with a limiter 72, a delay circuit 73, and a composite circuit FH 75 (Fig. 13A). To 13o and 14a to 14o), the recording signal S74 having two separation pulses FR1, FR2 and RR2, RR1 at the front side and the rear side of the central continuous pulse CTR. ) Is generated as shown in FIGS. 13p and 14p.

Since the recording signal S74 is supplied to the light source 77 via the recording circuit 76, in the magneto-optical recording disk 78, the position on the disk surface corresponding to the central continuous pulse CTR is thermally stable. Thus, a central pit portion P _CRT having a defined width is formed as shown in FIGS. 13q and 14q.

In the front part and the rear part (i.e., the start end part and the end end part), the front end pit parts P _FR2 and P _FR1 and the rear end pit parts P _RR2 and P _RR1 are separated pulses FR2, FR1 and RR2, RR1).

The front pit portions P _FR2 and P _FR1 and the rear pit portions P _RR2 and P _RR1 as described above with reference to FIGS. 5A to 5G are formed by separation pulses and are not made in the shape of droplets. Therefore, the shape of the front end portion of the front end pit portion P _FR1 and the position of the rear end portion of the rear end pit portion PRR1 can be detected stably. Therefore, the positional information as the FM signal can be reproduced with high precision.

(4) Third Embodiment

15 and 16, in which portions corresponding to those in Figs. 5 and 6 are designated by the same reference numerals, the third embodiment of the present invention is the magneto-optical recording apparatus 90 and the magneto-optical reproducing apparatus. (95). In the third embodiment, the transmission system of reproduction is configured to transmit digital information in the partial response (1, 1) system (so-called duo binary system).

As is already known, in the transmission of partial response systems, precode is provided for digital information. However, in the third embodiment, the digital information having the provided precode is recorded on the magneto-optical recording disk 10 by the pit forming method according to the present invention, and the multi-value reproduction of the duo binary code is reproduced from the reproduced signal. The signal is obtained, and this signal is converted into a binary signal to recover the original digital information.

That is, in the magneto-optical recording device 90, the synthesized signal S23 transmitted from the time division multiplexer 25 is input to the sync address adder 31, and after the sync signal and the address signal are added as necessary, The signal is input to the precode circuit 91.

The precode circuit 91 receives a signal S90 (Fig. 17A) including a synthesized signal S23 to which a synchronization signal and an address signal are added on the reproduction side, and a multi-value reproduction signal of a duo binary code from the reproduction signal. Is converted into a write source signal S91 containing a binary signal suitable for obtaining &lt; RTI ID = 0.0 &gt;, &lt; / RTI &gt; and the write source signal S91 is supplied to the pulse modulation circuit 33. The precode circuit 91 has a circuit configuration such that original digital information and information delayed by one bit clock from this original digital information are added to the module 2.

The pulse modulation circuit 33 has a drive pulse signal (similar to the above description) including a drive pulse signal (S) including a signal similar to the drive pulse signal S41 as described above with respect to FIG. 5D or 5F based on the write source signal S91. S92 is generated and the drive pulse signal S92 is irradiated to the magneto-optical recording disk 10 through the optical head processor 34 from the light source 35 including the laser diode as the recording light beam 36. do.

Thus, according to the magneto-optical recording apparatus 90 of FIG. 15, the light source does not directly emit light based on the recording source signal S91, but the recording source signal S91 is generated with a drive pulse signal S92 generated at a predetermined period. And the light source 35 is intermittently driven for radiation by the drive pulse signal S92, the start end of the pit 4 formed on the magneto-optical recording disk 10 similarly to the first embodiment. An almost circular magnetic region can be formed at, whereby the recording information of the start end of the pit 4 can be recorded correctly.

When the recording information is reproduced from the pit 4 formed on the magneto-optical recording disk 10 in the manner described above, the magneto-optical reproducing apparatus (Fig. 16) is reflected from the magneto-optical recording disk 10 in the optical pickup 52. The received light beam 51 is received and the resultant light receiving output signal S95 is supplied to the equalizer 96 via the light processor 53. The equalizer 96 is a circuit for equalizing the light reception output signal S95 to a signal of a duo binary code.

As shown in FIG. 18. In practice, the optical reception output signal S95 from the optical head processor 53 has a frequency characteristic T1 called a MTF (modulation transfer function) whose amplitude gain decreases in response to the spatial frequency of the optical transmission system.

As a result, in the equalizer 96, the light receiving output signal S95 is equalized by equalizing the frequency characteristic T2 in order to convert the frequency characteristic T1 into the frequency characteristic of the duo binary code. A light receiving output signal corresponding to the frequency characteristic T3 of the duo binary code, i.e., the duo binary signal S96 (Fig. 17B) is obtained.

In the duo binary signal S96 as already known, the frequency band is compressed to 1/2 compared with the original digital information of the binary signal, and the logic level has three values of V and O -V. . Among these logic level values, V and -V correspond to "1" of the original digital information, and the value 0 corresponds to "0". The level shift between each logic level is such that the level does not move directly from V to -V or from -V to V, but always through 0.

This duo binary signal is supplied to the duo binary decoder 97.

The duo binary decoder 97 determines the binary logic level corresponding to the logic levels V, O, -V at the first and second reference levels TH1 and TH2 for the duo binary signal S96. And a circuit for restoring the reproduced output signal S97 (FIG. 17C) of the original digital information. The reproduced output signal S97 is supplied to the sync address decoder 55.

Thus, a synthesized signal S51 similar to the synthesized signal S23 obtained at the output of the time division multiplexer 25 of the magneto-optical recording device 90 can be obtained at the output of the sync address decoder 55, and the synthesized signal S51. After the video data included in the C) is error corrected by the internal error correcting circuit 56, the corrected data is desuffixed by the desuffling circuit 57, and external by the external error correcting circuit 58. The error correction processing and the error correction processing in the error correction circuit 59 are then transmitted as a video output through the digital / analog converter 60.

At the same time, the audio data contained in the synthesized signal S51 also has an internal error correction circuit 61, a desuffling circuit 62, an external error correction circuit 63, an error correction circuit 64 and a digital / analog converter ( Through the 65, it is reproduced as the audio output signal S52A.

Therefore, in the magneto-optical recording apparatus 90 and the magneto-optical reproducing apparatus 95, the shape at the start end can form a pit 4 which is not formed in the shape of a water droplet as in the prior art, and thereby With good pit separation, the pit 4 can be realized, and the magneto-optical regeneration method suitable for the reproduction of the multi-value signal can be realized by the duo binary code of the partial response (1, 1) system.

As already known, since the duo binary code is a code system that actively uses inter-code interference, and since the code is highly correlated, the duo binary code is caused by the phase shift (e.g., edge shift) of the transmission system. Impact is inevitable, and determination of each logic level with three values is difficult. In this respect, the pit shaping method according to the invention with good pit separation is suitable for the transmission of multivalued signals, such as partial response (1, 1) systems.

Therefore, since the recording information of the magneto-optical disk 10 is reproduced in multiple values, the optical transmission system can be operated in a low frequency band within the spatial frequency of the MTF, and the reproduced output signal S97 has a marked improvement in C / N. Can be realized.

(5) another embodiment

(5-1) In the embodiment as described above, the drive pulse signal S41 (Fig. 5D or Fig. 5) over the entire range of the period in which the recording signal (Fig. 5C) rises to the logic " 1 " level. 5f degrees) is generated in a section of a predetermined sampling period T so that a recording spot 4 having a substantially circular magnetic region is formed on the magneto-optical recording disk at any time. However, instead, the recording pit having a circular magnetic region may be formed only in the rising or falling portion of the recording signal S13, and a drive signal of a constant level may be generated during the period between them. As a result, a recording pit having a shape almost similar to the portion except the start end 4A among the pit in the prior art (Fig. 2D) is formed.

In such a configuration, there is no fear of failing to reproduce the positional information in the rising part and the falling part of the recording signal S13, thereby eliminating the magneto-optical recording disc with a significantly higher precision than in the prior art. Information can be recorded.

In addition, in the case of the present embodiment, since the drive pulse signal at the end portion may be omitted or a continuous signal may be formed after the intermediate portion, similar effects to those in the above-described case can be obtained.

Also, since no subsequent drive signal is present at the end of this case, a nearly circular magnetic region can be formed substantially similar to the case where a drive pulse is received.

(5-2) In the above-described embodiment, the pulse amplitude P _H of the drive pulse signal S14 (FIG. 5D or 5F) is a section in which the recording signal S13 rises to a logic " 1 " level. While it is made uniformly constant value. But. Instead, a change or other change in the amplitude of the intermediate portion may be made as necessary.

(5-3) In the above-described third embodiment, the recording information of the magneto-optical recording disc is reproduced in multiple values as a duo binary code by using the partial response (1, 1) system. However, the present invention is not limited to this, and since multi-value reproduction may be performed in various systems such as other partial response systems, an effect similar to the above-described embodiment can be realized.

Claims (4)

A magneto-optical recording apparatus for recording a recording signal by forming a pit on a magneto-optical recording medium which is applied in response to a recording signal and which is moved relative to the recording light beam, the predetermined level of the recording signal. And pulse signal forming means for forming a plurality of pulse signals, and light source driving means for intermittently driving a light source to generate the light beam using the output of the pulse signal forming means. 2. The recording signal according to claim 1, wherein the recording signal is a digital signal, and the plurality of pulse signals formed by the pulse signal forming means are each divided into a substantially circular magnetic area group or a redundant and circular magnetic area group, respectively. And an optical magnetic recording device having a pulse width and a pulse interval of said recording light beam formed on said magneto-optical recording medium. 2. The apparatus of claim 1, further comprising precoding means for encoding with a duo binary encoding method, wherein the write signal is an output signal of the precoding means, and formed by the pulse signal forming means. And the plurality of pulse signals have a pulse width and a pulse interval of the light beam, each forming a separate, nearly circular magnetic region group or each overlapping, circular magnetic region group on a magneto-optical recording medium. The recording signal is a carrier signal of a frequency modulated signal, and the pulse signal forming means is overlapped at a start part and an end part respectively corresponding to a start end and an end end of the predetermined level of the record signal, A plurality of pulse signals having a pulse width and a pulse interval of the recording light beam forming the pit having a circular magnetic region group on the magneto-optical recording medium, wherein the magnetic region is the predetermined level of the recording signal. And a magneto-optical recording device formed by one pulse corresponding to one portion between the start portion and the end portion of the.

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