JPH03100902A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To accurately read out information on synchronizing timing for recording and erasing and information on address by providing a signal level limiting means for limiting the excessive amplitude included in a reproducing signal to a specified level at the preceding stage of a reproducing circuit. CONSTITUTION:The reproducing signal S1 is inputted in a limiter 101 in a buffer amplifier 2501. The maximum amplitude included in the signal S1 is limited to the specified level in the limiter 101. An output signal 111 from the limiter is inputted in an HPF constituted by including a capacitor 102 and a resistance 103. The HPF removes the DC component in the signal S1. An output signal 102 from the HPF is transmitted to an amplifier 104. The same operation is performed for a reproducing signal S2 in the same way as the signal S1. Since the excessive amplitude included in the reproducing signal is limited to the specified level at the time of performing respective actions for recording and erasing the information, the reproducing signal is always suppressed within a reproducing limitation level. Therefore, the synchronizing timing information and the address information are accurately read out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to various information recording and reproducing devices, such as magneto-optical memory devices, and more specifically to a reproducing circuit in an information recording and reproducing device.

[Conventional technology]

A conventional information recording/reproducing device will be described here using a magneto-optical memory device as an example.

Taking a magneto-optical disk memory device as an example of a magneto-optical memory device, the operations of recording information on the magneto-optical disk, reproducing recorded information, and erasing the information will be explained below based on FIGS. 28 to 38. It is as follows.

First, each operation of recording information on the magneto-optical disk and erasing information recorded on the magneto-optical disk will be explained based on FIG. 28.

A magneto-optical disk as a magneto-optical recording medium on which information can be recorded and erased has a recording magnetic film 2805 formed on a disk substrate 2804, as shown in FIG. 2(a). The recording magnetic film 2805 is formed so that the axis of easy magnetization is perpendicular to the film surface, and is initialized in advance in the same direction (for example, magnetization direction A in the figure). Now, the laser beam 2803 emitted from the semiconductor laser 2801 is
The light is focused to a diameter of about μm and irradiated onto the recording magnetic film 2805. Recording green signal 2807 (
The intensity of the light intensity of the laser beam 2803 is controlled based on the light intensity of the laser beam 2803 (shown in FIG. 3(b)). When the temperature of the portion irradiated with the laser beam 2803 with high light intensity locally rises and exceeds the Curie temperature, the coercive force of that portion decreases significantly. Then, the direction of magnetization of that portion is reversed to the same direction as the externally applied magnetic field 2806 that has been applied in advance (direction of magnetization B in the figure). In this way, the same information as the recording signal 2807 is recorded on the recording magnetic film 2805. Hereinafter, the recorded portion recorded as described above is marked 2809, and the other portion is marked 2809.
It is called 10.

That is, for example, mark 2B'09 is the code (1) of the binary signal.
The mark 2809 and the non-mark 2810 constitute recording information such that the non-mark 2810 corresponds to the code (0) of the binary signal. Also,
Recording using this method is called magneto-optical recording. Erasing information recorded on the recording magnetic film 2805 is performed in the same manner as during recording by reversing the direction of the externally applied magnetic field 2806, changing the direction of magnetization to the original initializing direction (i.e.,
This is done by returning the magnetization direction to A) in the figure. As a result, the erased portion becomes a non-mark 2810.

Note that in this example, the laser beam 2803 is used as the recording signal 280.
Externally applied magnetic field 2806 of constant strength modulated according to 7
Although the optical modulation method is shown in which recording is performed by applying a
Recording may be performed using a magnetic field modulation method in which the direction of the externally applied magnetic field 2806 is modulated according to the recording signal 2807.

Further, the disk substrate 2804 of this example is a disk plate made of glass, plastic, etc.
As shown in Figure (a), address information indicating the addresses of tracks and sectors is formed in advance by being carved in the shape of physical irregularities 2808. This unevenness 2808 is also a mark and a non-mark. Since the address information is engraved in a certain format in advance, it cannot be recorded or
Erasing operations are disabled. The portion inscribed in advance in the shape of physical unevenness 2808 will be referred to as a preformat portion hereinafter. On the other hand, each operation of recording and erasing information is performed in a part other than the preformat part, and this part is called an MO (data) part. Usually, this preformat section 3003 and MO (data) section 3
002 are alternately arranged on spiral or concentric tracks 3005, as shown in FIG.

The magneto-optical disk 3001, in which the preformat section 3003 and the MO section 30o2 are paired together to constitute one sector 3004, has a structure including a large number of sectors on a track 3005, each containing address information. There is. Each operation of recording, reproducing, and erasing information is performed on a sector-by-sector basis. Moreover, as shown in FIG. 31,
Preformat section 3003 on the track 3005 above
Mark 2808 is engraved in advance, and M
Mark 28 by magneto-optical recording in O (data) section 3002
09 will be recorded.

The reproducing operation of the magneto-optical disk will be explained below based on FIG. 29.

As shown in FIG. 4A, a laser beam 2803 emitted from a semiconductor laser 2801 and focused to a diameter of about 1 μm by an objective lens 2802 is irradiated onto a recording magnetic film 2805. However, the laser beam 2803 is linearly polarized, and the light intensity of the laser beam 2803 is weaker than that during each recording/erasing operation. When the reflected light of the linearly polarized laser beam 2803 from the magneto-optical disk 3001 passes through the recording magnetic film 2805 and is reflected, its plane of polarization is rotated by the Faraday effect and the Kerr effect. This direction of rotation is between mark 2809 and non-mark 2.
810 are rotated in opposite directions by the rotation angle of the plane of polarization. Reproduction is performed by detecting this difference in polarization direction and direction, and reproduction signals S1 and S2 as shown in FIGS. 4(b) and (c) are generated.

Figure 32 shows the main part of the configuration of the reproduction optical system.
The separation of the reproduced signals 31 and 32 will be explained below based on the figure.

The reflected light 3201 is incident on a PBS (analyzer) 3202, and two detected lights 3210 and 3211 are guided to photodetectors 3203 and 3204 for each polarization direction. Then, the photodetectors 3203 and 3204 convert them into electrical signals that change according to the light intensity, and the reproduced signal S
1, output as S2. Therefore, the reproduced signals S1, S
Since the mark 2809 and the non-mark 2810 can be read out separately from the recording magnetic film 2805, the information recorded on the recording magnetic film 2805 can be reproduced.

Reproduction signals S1 and S2 separated when the MO (data) section 3002 recorded magneto-optically based on FIG. 33 is reproduced.
The polarity of is explained below.

Non-mark 2810 due to magneto-optical recording (direction of magnetization A)
Let α be the reflected light vector from the mark 2809 (magnetization direction B), and β be the reflected light vector from the mark 2809 (magnetization direction B), then α and β are reflected light vectors rotated in opposite directions by the rotation angle of the polarization plane. The reflected light vectors α and β are measured using an analyzer (PB
S) Detection is performed in two polarization directions X and Y at 3202, respectively. These two polarization directions X and Y are perpendicular to each other. Let the reflected light vectors α and β be the polarization direction X,
The magnitudes of the detected light vectors α× and βY projected onto Y correspond to the reproduced signal S1 and the reproduced signal S2.

Furthermore, the detection light vectors α8 and βV correspond to the detection lights 3210 and 3211 in FIG. 32, respectively. As shown in FIG. 33, the reproduction signal Sl corresponds to a non-mark 2810 at a high level, and a mark 2809 at a low level. In addition, the reproduced signal S2 is a non-mark 2810
The low level corresponds to the mark 2809, and the high level corresponds to the mark 2809, and the polarity is opposite to that of the reproduced signal S1. The reproduced signals S1 and S2 are input to a differential amplifier to improve the SZN ratio, and are differentially amplified to reproduce information.

Next, the polarity of the reproduced signal Sl, 32 when the preformat section 3003 carved with physical irregularities 2808 is reproduced will be explained based on FIG. 34.

Since recording and erasing operations are not performed in the preformat section 3003, the direction of magnetization is only in the positive direction. In this portion, the shape of the unevenness 2808 causes diffraction of the laser beam. Therefore, as shown in the figure, the reflected light vector is longer depending on the unevenness 2808.
(corresponding to reproduction of uneven non-marks), and a short reflected light vector T (corresponding to reproduction of uneven marks). By projecting this onto the polarization directions X and Y of the analyzer (PBS) 3202, detected light vectors αx and 7v are obtained, respectively. The magnitude of the detected light vector αx, 7v is the reproduced signal S1
, S2. Reproduction signal S1 and reproduction signal S
2 both correspond to a high level for non-marks of the unevenness 2808 and a low level for marks. Therefore, the reproduced signals S1 and S2 are different from those of the magneto-optical recording mark 2809 and non-mark 2810 shown in FIG. 33, and have the same polarity. That is, as shown in FIG.
The polarity is the same in the Mo (data) part 3002.
, the signals have opposite polarities.

The reproducing circuit in the magneto-optical disk memory device will be explained below based on FIGS. 35 and 36.

In FIG. 35, the reproduction signals S1 and S2
1 and the binary output signal 3510 is input to the address generation circuit 3502 and the timing generation circuit 350.
3 is input. In the address generation circuit 3502, the sector unit preformat section 300 shown in FIG.
The address information included in 3 is the output signal 3510
The address signal 3511 is output.

Further, in the timing generation circuit 3503, a sector mark for sector synchronization also included in the preformat section is detected, and the recording/playback/erase reference timing signal 3503 is detected.
512 is output. In the magneto-optical disk memory device, information is recorded, reproduced, and erased in a sector at a desired address based on this address signal 3511 and a recording/reproducing/erasing reference timing signal 3512.

Based on FIG. 36, the buffer amplifier 36 disposed at the input stage of the conventional reproduction circuit 3501 in FIG.
01 will be explained below.

The reproduced signal St is input to a bypass filter composed of a capacitor 3602 and a resistor 3603 in a buffer amplifier 3601. As shown in the figure, one of the resistors 3603 is fixed at voltage v0. This bypass filter removes the DC component in the reproduced signal Sl, making it possible to easily reproduce only the information signal contained in the AC component. An output signal 3610 of the bypass filter is input to an amplifier 3604, and an output signal 3612 thereof is transmitted to a reproduction circuit 3501 at a subsequent stage. The reproduced signal S2 is similarly input to a bypass filter composed of a capacitor 3605 and a resistor 3606 in the buffer amplifier 3601, and the DC component in the reproduced signal S2 is removed, making it easy to
Only the information signal included in the C component can be reproduced.

The output signal of the bypass filter is transmitted to the subsequent reproducing circuit 3501 as an output signal 3613 via an amplifier 3607.

[Problem to be solved by the invention]

However, in the conventional device using the buffer amplifier 3601 shown in FIG. 36, the information in the preformat section immediately after each operation of recording and erasing information may not be read out.

This becomes a particular problem when performing high-speed information transfer and high-density recording.

This will be explained below based on FIGS. 37 and 38.

FIG. 37 and FIG. 38 show waveform examples of each part of the buffer amplifier 3601. As shown in FIG. 37(a), information is recorded in a sector consisting of a preformat section 3701 and an MO (data) section 3702, and a sector consisting of a preformat section 3703 and an MO (data) section 3704. Information is played back in the sector, and the preformat section 3705 and MO (data)
It is assumed that information is erased in the sector configured by section 3706. Each operation of recording, reproducing, and erasing these information is performed by the preformat section 3701.3703.37.
The synchronization timing information and address information of 05 must be read out, and this must be carried out while sequentially confirming that the predetermined synchronization timing is detected and that it is the predetermined address.

Now, as shown in FIG. 37(b), the reproduced signals 31 and 32 become signals with excessive amplitudes during each recording and erasing operation. This is because reflected light with high light intensity enters the photodetectors 3203 and 3204 during each recording and erasing operation. Along with this, as shown in the same figure (C),
Output signal 3612.3613 of buffer amplifier 3601
is a waveform that reflects the transient response of the bypass filter. In other words, the signal level immediately after each recording and erasing operation is varied up and down. Immediately after each recording and erasing operation, the preformat sections 3703 and 3707 must be reproduced. On the other hand, the reproduction circuit 3501 including the buffer amplifier 3601 has a reproduction limit level range, as shown in FIG. Become. Note that the reproduction level limit range described above is a range in which the circuit can electrically operate normally, and is, for example, a limit at which the signal level is saturated. In addition, AGC (Automation) is installed in the rear stage.
c) If an amplifier is present, this is the reproducible range including its response time.

In this case, as shown in FIG.
1 far exceeds the above range. In particular, since the DC components of the reproduced signals S1 and S2 at the time of erasing are larger than those at the time of recording, the DC components of the reproduced signals S1 and S2 are larger than those at the time of recording, so that the DC components exceed the above range even more immediately after erasing. Therefore, the preformat section 370 immediately after recording and erasing
3, and the synchronization timing information and address information obtained by reproducing the preformat section 3707 are difficult to read, and the problem is that the predetermined synchronization timing is not detected and it is not possible to confirm that it is the predetermined address. have. In other words, it becomes impossible to perform each operation of recording, reproducing, and erasing information, and this is particularly noticeable immediately after erasing. Note that, taking into account the transient response time of the bypass filter, the preformat unit 370
3.3707 will solve the above problem. However, this approach increases the distance between preformatted sections, which reduces the information transfer speed and impedes the ability to record information at a higher density, so it is not an essential solution. . Furthermore, if the time constant of the bypass filter is made smaller, the transient response time becomes shorter, so the above problem is solved. However, if this is done, a phase shift will occur in the data in the reproduced signal, causing a reproduction error. Therefore, there is a lower limit to the time constant of the bypass filter, and it is difficult to make it smaller than this.

Based on FIG.
The influence on the output signal 3801 of the GC amplifier will be explained below.

The AGC amplifier automatically adjusts the amplification degree for the reproduced signals S1 and S2, and responds based on the recording and erasing levels.

Therefore, when a signal such as that shown in FIG. 6(b) is input to the AGC amplifier, its amplification degree gradually becomes much lower than the original amplification degree during reproduction. Along with this, the level of the output signal of the AGC amplifier also decreases significantly, as shown in FIG. 4(C). In this way, the amplification degree of the AGC amplifier cannot be returned to its original level instantly, so the AGC
Immediately after the amplifier output signal 3801 reaches a steady state,
Preformat section 3703.370 shown in FIG.
When 7 is reproduced, the amplitude of the reproduced signal becomes so small that the information cannot be read. Therefore, as in the case explained based on FIG. 37, in this case as well, the preformat section 3703.
It is difficult to read the synchronization timing information and address information obtained by reproducing 07, and there is a problem that a predetermined synchronization timing is not detected and it is not possible to confirm that it is a predetermined address. In other words, it becomes impossible to perform subsequent operations of recording, reproducing, and erasing information. In addition, considering the response time of the AGC amplifier,
The above problem can be solved by arranging the preformat sections 3703 and 3707 at intervals corresponding to sufficiently long time intervals. However, this approach increases the distance between preformatted sections, which reduces the information transfer speed and impedes the ability to record information at a higher density, so it is not an essential solution. .

As explained above based on FIG. 37 and FIG. 38, in the conventional device, it is impossible to reliably record, reproduce, and erase information in a desired sector, and in addition, the magneto-optical memory device This has the problem of hindering high-speed information transfer and high density information.

[Means to solve the problem]

In order to solve the above-mentioned problems, an information recording and reproducing apparatus according to the present invention provides an information recording and reproducing apparatus that records, reproduces, or erases information. The present invention is characterized in that a signal level limiting means for limiting the excessive amplitude generated by the signal to a predetermined level is provided at a stage upstream of a reproducing circuit that reproduces information.

[For production]

With the above configuration, a signal level control means is provided before the reproducing circuit that reproduces information, and excessive amplitude contained in the reproduced signal is limited to a predetermined level during each operation of recording and erasing information. It is possible to suppress the influence of the transient response of AC coupling on the reproduced signal in the preformat section immediately after each erasing operation. In other words, the reproduced signal can always be kept within the reproduction limit level range, so
It is possible to accurately read the synchronization timing information and address information of the preformat section immediately after each recording/erasing operation. Recording, playback, and erasing operations can be performed.

Therefore, the arrangement of the preformat section can be determined without being affected by the transient response of AC coupling or the response of the AGC circuit, and high-speed transfer of information and high density in the magneto-optical disk memory device are possible.

[Embodiment 1] The first embodiment of the present invention will be described below based on FIGS. 1 to 23.

First, a magneto-optical memory device as an information recording/reproducing device according to the present invention will be described below with reference to FIGS. 8 to 16. FIG. 8 is a block diagram showing the configuration of the magneto-optical memory device. A magneto-optical disk 1201 is rotated by a spindle motor 1202, and information is recorded, reproduced, and erased by a laser beam 1204 emitted from an optical head 1203. At this time, the external application magnet 120
5 is rotated by a motor or the like to reverse the direction of the magnetic field, thereby obtaining an externally applied magnetic field for recording and erasing. Also,
An externally applied magnetic field for recording and erasing may be obtained using an electromagnet. A semiconductor laser drive current 121.0 is input from the recording circuit 1206 to a semiconductor laser (not shown in the figure) in the optical head 1203. Same drive current 1210
The light intensity of the semiconductor laser is appropriately controlled, and recording information is recorded on the magneto-optical disk 1201. The optical head 1203 outputs a reproduction signal 1211 (reproduction signals Sl, S2) to the reproduction circuit 1207. Reproduction data 1212 reproduced by reproduction circuit 1207 is sent to controller 1208. controller 120
8, the timing of various control signals is determined based on the reproduced data 1212, and the control signal is output based on the state of the input signal. That is, various control signals 1213 are sent from the controller 1208 to the recording circuit 1206 and the reproducing circuit 1207. Further, a magnetic field control signal 1214 is transmitted from the controller 1208 to the externally applied magnet 1205, and the direction of the externally applied magnetic field is controlled.

The recording circuit 1206 will be explained below based on FIG. Record data 1311 sent from the controller 1208 (not shown in the figure) is sent to the recording circuit 12.
The signal is input to the modulation circuit 1302 in 06. Modulation circuit 13
In step 02, the recording data 1311 is converted into modulated data 131o according to the recording format by the control signal 1213. This modulation is performed, for example, according to a modulation method (described later) as shown in FIG. Modulation data 1310 is output to semiconductor laser drive circuit 1301. A semiconductor laser drive current 121o is output from the semiconductor laser drive circuit 13o1 and transmitted to the semiconductor laser 28o1 in the optical head 1203. At the same time, a control signal 1213 from the controller 1208 is input to the semiconductor laser drive circuit 1301, and the light intensity of the semiconductor laser 2801 is appropriately controlled according to each recording, reproducing, and erasing operation.

The reproducing circuit 12o7 will be explained below based on FIG. Reproduction signal 1211 (reproduction signal S1, S2) from optical head 1203 (not shown in the figure)
is input to the signal processing circuit 1401 within the reproduction circuit 1207. From the signal processing circuit 1401, synchronization data 14
10 is sent to the demodulation circuit I402, and at the same time, a sector mark signal 1411 is sent to the controller 1208. Demodulation of the synchronized data 1410 is performed according to the method shown in FIG. 12 (described later). In other words, demodulation is performed by performing a conversion opposite to that of the modulation circuit 1302 shown in FIG. Signal processing circuit 14011 Demodulation circuit 14
Various control signals 121 are sent from the controller 1208 to 02.
3 is transmitted. Reproduction data 1 is output from the demodulation circuit 1402.
212 is output to controller 1208.

The controller 1208 will be explained below based on FIG. 11. The sector mark signal 1411 from the signal processing circuit 1401 described above is input to the timing generation circuit 1501 in the controller 1208, and the reference timing signal 1510 is transmitted to the control circuit 1502 at the timing of each sector. In addition, the above-mentioned demodulation circuit 1
The playback data 1212 from 402 is the control circuit 1.
502. In the control circuit 1502,
Various control signals 1213 are generated from the above two input signals, and information is input and output to and from external devices.

Next, the operation of the recording circuit 1206 shown in FIG. 9 will be described below based on FIGS. 12 to 16.

In the modulation circuit 1302 in FIG. 9, modulation is performed based on the modulation method shown in FIG. 12, for example. This is the so-called 2,7 modulation power formula. 12th
As shown in the figure, input data (recorded information) is converted into a predetermined modulation data pattern. Further, the modulated data 131O is transmitted to the semiconductor laser drive circuit 13 shown in FIG. 9 at an appropriate timing according to the format shown in FIG.
Output to 01. FIG. 13 shows the format of the sector 3004 shown in FIG. 30, hereinafter referred to as sector format. In FIG. 13, the preformat section 3003 includes a sector mark section 1701 for obtaining synchronization timing in units of sectors, and a sector address (address).
It consists of 10 parts 1702 containing information. As shown in FIG. 30, physical irregularities corresponding to marks that cannot be recorded or erased and non-marks are carved into the magneto-optical disk 1201. MO (data) section 3
002 is a data section 1703 for recording, reproducing, and erasing information data, and two gap sections 1704.17.
05. The modulation data 1310 is recorded in the data section 1703. The record at this time is the second
As shown in FIG. 8 or FIG. 29, this is performed with or without marks by magneto-optical recording. Note that gap sections 1704 and 1705 arranged between the preformat section 3003 and the MO (data) section 3002 are spare areas for recording information in the data section 1703. In other words, these gap portions 1704 and 1705 are designed to take account of the fact that the recording start position and recording end position are shifted back and forth due to the phase error that occurs between the rotation of the spindle motor 1202 and the above-mentioned sector-by-sector synchronization timing. It is a field.

Based on FIG. 14, the semiconductor laser drive circuit 1301
will be explained below. Semiconductor laser drive circuit 130
1 and the controller 1208, four various control signals 1810, 18111812, and 1813 are input/output. Furthermore, modulation data 1310 is input from a modulation circuit 1302 (not shown in the figure) to a semiconductor laser drive circuit 1301. The above reproduction light amount control signal 1
The signal 810 is input to the reproduction light amount control circuit 1801, so that the reproduction light amount of the semiconductor laser 2801 in the optical head 1203 is appropriately controlled during reproduction. The recording/erasing light amount control signal 1811 is the recording/erasing light amount control circuit 18
03, and the light amount of the semiconductor laser 2801 corresponding to recording and erasing is controlled. The high frequency superposition switch signal 1812 is transmitted to the high frequency superposition circuit 180
2, and noise due to the return light from the semiconductor laser 2801 is reduced. Reproduction light amount control circuit 1801, recording/
Output signals 1814, 1815, and 1816 of the erasing light amount side control circuit 1803 and the high frequency superimposing circuit 1802 are added in an adder circuit 1805, and a 2I' conductor laser drive current 1210 is input to the semiconductor laser 2801. The amount of light (light intensity) of the semiconductor laser 2801 is different from that of the optical head 1203.
The light intensity monitor signal 1813 is converted into an electric signal that changes according to the light intensity by a photodetector 1806 in the controller 120.
B (not shown in the figure). The controller 1208 outputs the three control signals 1810.1 based on the light amount monitor signal 1813.
811 and 1812 are output. In other words, the light intensity (amount of light) of the semiconductor laser 2801 is controlled to be appropriate during reproduction and during recording/erasing. Note that the output signal 1816 of the high frequency superimposing circuit 1802 is output to the adding circuit 1805 only during reproduction.

The information recording/erasing operations and the reproducing operation in FIG. 14 will be explained below based on FIGS. 15 and 16.

As shown in FIG. 15(b), the high frequency superimposition switch signal 1812 becomes a low level (0) in the data section 1703 (see FIG. 15(a)), and becomes a high level (1) elsewhere. That is, the high frequency superimposition is turned off in the data section 1703 in the MO (data) section 3002, and turned on in other parts than the data section 1703. Along with this, as shown in the same figure (C), modulation data 1310
is magneto-optically recorded in the data section 1703. At this time, as shown in FIG. 4(d), the light amount level (light intensity) 1910 of the semiconductor laser 2801 becomes a high level in the data portion 1703, and becomes a low level in other areas. In other words, the sector mark section 1701 in the preformat section 3003
The sector synchronization timing is detected from the ID part 702.
While reading the address information etc. from the MO (data) section 3002 and checking the predetermined address (address),
Information is recorded and erased.

On the other hand, when reproducing information, as shown in FIG. 16(b),
The preformat section 3003 and the main part of the MO (data) section 3002 also receive the high frequency superimposed switch signal 1.
812 is a high level (1). Further, as shown in FIG. 2C, modulation data 1310 is at a low level (0). Furthermore, as shown in the same figure (d), the light amount level 1
91O is a low level. In other words, the sector mark section 1 in the preformat section 3003 (see (a) in the same figure)
The sector synchronization timing is detected from 701, address information etc. are read from ID section 702, and while sequentially confirming the predetermined addresses, information recorded from MO (data) section 3002 is read out. is played.

Next, the operations of the timing generation circuit 1501 and the control circuit 1502 shown in FIG. 11 will be described below based on FIGS. 17 to 20.

FIG. 17 is a block diagram showing the configuration of the timing generation circuit 1501, and the sector mark signal 1411 output from the signal processing circuit 1401 (not shown in the figure) is transmitted to the sector mark detection circuit 2 in the timing generation circuit 1501.
101. The circuit 2101 outputs a sector mark detection signal 2110. Sector mark detection circuit 2
At 101, the presence or absence of a sector mark is detected. Sector mark detection signal 2110 is transmitted to counter 2102, timer circuit 2104, and determination circuit 2106, respectively. The output signals 2111 and 2112 of the counter 2102 and the timer circuit 2104 are respectively input to the switch circuit 2103, and after one of them is selected by the switch circuit 2103, it is output as a reference timing signal % 1510. The same signal 1510 is also input to the data section generation circuit 2107, and based on this, the data section generation signal 2116 is output. Timer circuit 2104
, another output signal 2113 is sent to the window generation circuit 2.
105. A window signal 2114, which is an output signal of the circuit 2105, is input to a determination circuit 2106. In the determination circuit 2106, the window signal 2114
A timing determination signal 2115 is output from the sector mark detection signal 2110 and the sector mark detection signal 2110. Based on the determination signal 2115, the switch circuit 2103 outputs the output signal 2111 of the counter 2102 and the output signal 21 of the timer circuit 2104.
One of the 12 is selected. The reference timing signal 1510, the data portion generation signal 2116, and the timing determination signal 2115 are each supplied to the control circuit 15.
02 (see Figure 11). The control circuit 1502 outputs the aforementioned various control signals 1213 to the recording circuit 120 based on the various signals outputted from the timing generation circuit 1501 and the reproduced data 1212.
6 and a reproducing circuit 1207 (see FIG. 8), and controls recording, reproducing, and erasing of information.

The sector mark detection circuit 2101 shown in FIG. 17 will be described below based on FIG. 18.

A sector mark signal 1411 output from a signal processing circuit 1401 (not shown in the figure) is sent to a counter circuit 2.
It is transmitted to each input of counters 1 to 9 that constitute 201. Each output signal 2211-2219 of counters 1-9 is
Each signal is transmitted to a determination circuit 2202, and a sector mark detection signal 2110 is output based on the result. In other words, the sector mark detection circuit 2101 is a circuit that detects the sector mark portion 1701 (see FIG. 13) and obtains the synchronization timing necessary to perform each sector-based recording, reproduction, and erasing operation.

The operations of the counters 1 to 9 described above will be explained below based on FIG.

As an example of the pattern of the sector mark portion 1701, a pattern consisting of marks and non-marks as shown in FIG. 3(b) is shown. The pattern of this sector mark portion 1701 is completely different from the data modulation method shown in FIG. 12. Therefore, it can be detected separately from information data. The example shown here is as shown in the same figure (a), where the ratio of mark length and non-mark length is 5:3:3:1:3:3:3:3:5.
The marks are engraved in order. The sector mark signal 1411 obtained by reproducing the mark and non-mark patterns is as shown in FIG.
It is converted into a binary signal with a low level (0) in the marked part and a high level (1) in the non-marked part. When this sector mark signal 1411 is input to each of the counters 1 to 9, the square counter 1 counts the number of clocks of the counter clock 2310 corresponding to the mark length 5. The counter clock 2310 has a higher frequency than the sector mark signal 1411, as shown in FIG. 2(d). If this count is within a predetermined range, it means that the first mark (mark length 5) has been detected accurately. Subsequently, the counter 2 similarly detects a non-mark with a non-mark length of 3. In this way, marks and non-marks in the sector mark section 1701 are sequentially detected, and finally the counter 9 detects the length of the mark length 5. The nine mark or non-mark detection signals 2211 to 2219 thus obtained are sent to the determination circuit 222.
2. Of these nine detection results,
It is determined whether all or part of them match the pattern of the sector mark section 1701, and the order of marks and non-marks is determined. As a result, only when it is determined that it is a sector mark portion, the sector mark detection signal 2110 becomes low level (0). Therefore, this signal 2110 can be used as sector-by-sector synchronization timing.

The waveforms of each part of the timing generation circuit 1501 will be explained below based on FIG.

As shown in FIG. 2(b), the sector mark detection signal 211
0 is sector mark section 1 in preformat section 3003
When 701 (shown in (a) in the figure) is detected, it becomes low level. The falling edge of the detection signal 2110 becomes the sector synchronization timing. As shown in FIG. 3C, the counter 2102 outputs the counter output signal 211 after a predetermined count from the falling edge of the detection signal 2110.
1 to low level. On the other hand, the count number of the timer circuit 2104 is greater than the count number of the counter 2102 by one sector. Therefore, as shown in FIG. 4D, the falling edge of the timer circuit output signal 2112, which is the output of the timer circuit 2104, almost coincides in timing with the falling edge of the signal 2111 of the next sector. Further, as shown in FIG. 2(e), the output signal 211 of the window generation circuit
4 becomes low level with a predetermined window width around the falling edge of the sector mark detection signal 211O in the next sector, with the falling edge of the sector mark detection signal 2110 as a reference. Timing determination signal 2115 which is the output signal of determination circuit 2106
If there is a falling edge of the sector mark detection signal 211o when the output signal 2114 of the window generation circuit 2105 is at a low level, it becomes a high level as shown by the solid line in FIG. ing. on the other hand,
If there is no falling edge of the sector mark detection signal 2110, the sector mark detection signal 2110 becomes a low level (indicated by a broken line in FIG. 2(f)). Therefore, the timing determination signal 2115 is a signal for determining whether the sector mark was detected within a predetermined range or whether it was a detection error. In this case, the signal 2111 is selected, and if there is a detection error, the signal 2112 is selected. As a result, as shown in FIG. 4G, the reference timing signal 1510 can reliably output the timing signal even if a sector mark detection error occurs. That is, as shown above, correction can be made based on the timing of the previous sector. The reference timing signal 151o obtained in this manner is transmitted to the data portion generation circuit 2107. Same circuit 2107
is a type of counter, and its output, the data section generation signal 2116, becomes low level in the data section 1703.

(See (h) in the same figure) In other words, the data section generation signal 211
6 can be used as a signal for distinguishing between the preformat section 3003 and the MO (data) section 3002. The reference timing signal 1510, timing determination signal 2115, and data section generation signal 2116 obtained in this way
is transmitted to the control circuit 1502 shown in FIG. The circuit 1502 generates the aforementioned various control signals 1213 based on these signals.

Next, the operation of the signal processing circuit 1401 shown in FIG. 10 will be described below based on FIGS. 21 to 23.

Reproduction signal 121 reproduced from magneto-optical disk 1201
1 (playback signals S1, S2) are processed by the signal processing circuit 1401.
The signal is inputted to a buffer amplifier 2501 inside. The output signal 2510 is transmitted to an MO waveform processing section 2502 and a preformat waveform processing section 2503. These circuits output binary signals 2511 and 2512 corresponding to marks and non-marks of the MO (data) section 3002 and preformat section 3003, respectively.

These binary signals are input to the data synchronization section 2504, and the PLL (Phase
LoCke, d Loop), synchronous data 2513 synchronized with the clock is output, and the demodulation circuit 140
2 (not shown in the figure). Further, the preformat waveform processing section 2503 generates a sector mark signal 1411 and transmits it to the timing generation circuit 1501.

In the signal processing control section 2505, the signal processing circuit 1
Various control signals 2514 to 2517 are input and output between each section in 401. In addition, the controller 1 shown in FIG.
Various control signals 1213 are input/output to/from 208.

22 and 23 are diagrams showing waveforms of each part of the signal processing circuit 1401. As shown in FIG. 22(b) and FIG. 22(C), the reproduced signals S1 and S2 are differentially outputted in the MO waveform processing section 2502 and sent to the MO (data) section 30.
02 (see (a) in the same figure) is separated and further binarized to generate an MO binary signal 2511 (see (d) in the same figure). In addition, the reproduced signals S1 and S2 are added in the preformat waveform processing section 2503, and only the information in the preformat section 3003 is separated, and further binarized to obtain the ID binary signal 2512 and the sector mark signal 1411 ( (See figure (e) and figure (g)). The reason why the MO (data) section 3002 and the preformat section 3003 can be separated by differential and addition of the reproduction signals S1 and S2 is that the polarity of the reproduction signals S1 and S2 is different from the MO (data) section as shown in FIG. 30
02 is the opposite, and the preformat section 3003 is the same. MO2 value signal 2511 and ID
The binary signals 2512 are each converted into synchronous data 2513 synchronized with a clock in a data synchronization unit 2504, as shown in FIG. Note that information data is reproduced from the MO binary signal 2511, and address information is reproduced from the ID binary signal 2512.

FIG. 23 is a diagram illustrating the waveforms of FIG. 22 in detail. Marks and non-marks recorded based on modulated data 1310 (see FIG. 23(a)) are reproduced by irradiation with a laser spot 2701 (see FIG. 23(b)). As shown in the same figure (C), the reproduced signals S1, S2
is a signal that peaks at the center of the mark. The MO binary signal 2511 or the ID binary signal 2512 is a signal that has detected this peak position, and its rising edge coincides with the peak position (see (d) in the figure). In the PLL in the data synchronization unit 2504, a synchronization clock is generated from the MO binary signal 2511 or the ID binary signal 2512, and the synchronization data 2 is synchronized with this clock.
I got 513. As shown in FIG. 4(e), the synchronization data 2513 is data obtained by faithfully reproducing the modulation data 1310.

Next, the buffer amplifier 2501 in the signal processing circuit 1401 in this embodiment will be explained below based on FIGS. 1 to 7.

In FIG. 1, the reproduced signal S1 is transmitted to the buffer amplifier 250.
The signal is inputted to a limiter 101 (signal level limiting means) in 1. This limiter 101 limits excessive amplitude contained in the reproduced signal S1 to a predetermined level. Limiter output signal 111 is connected to capacitor 102 and resistor 10
It is input to a bypass filter consisting of a configuration including 3. Note that one end of the resistor 103 is connected to the capacitor 102, and the other end is connected to the voltage ■. It is connected to the. The bypass filter removes the DC component in the reproduced signal Sl and facilitates reproduction of only the information signal included in the AC component. Further, the time constant of the bypass filter is set as small as possible to the extent that a phase shift does not occur in the data in the reproduced signal, resulting in a reproduction error. In other words, the time constant of the bypass filter is set so that the transient response time is as short as possible. And the output signal 112 of the bypass filter
is transmitted to the amplifier 104, and its output signal 115 is transmitted to a subsequent reproducing circuit (not shown). Similarly, after the excessive amplitude of the reproduced signal S2 is limited to a predetermined level by a limiter 105, it is transmitted to a bypass filter comprising a capacitor 106 and a resistor 107, and the DC component in the reproduced signal S2 is removed, AC
Only the information signals contained in the components are easily reproduced. The output signal 114 of the bypass filter is passed through the amplifier 108 as an output signal 116 to a subsequent regeneration circuit (not shown).
transmitted to.

FIG. 2 shows a first embodiment of the limiters 101, 105 in FIG. The reproduced signal S1 is a limiter
The signal is input to an emitter follower including resistors 201, 202, and 204 in 101 and a PNP transistor 203. The emitter follower output signal 111 is input to the diode 205 and the capacitor 102. An output signal 112 of a bypass filter composed of a capacitor 102 and a resistor 103 is transmitted to a next-stage buffer amplifier 104 (not shown in the figure). On the other hand diode 2
05 is transmitted to the open collector 213 and the resistor 212 via the resistor 206. The resistor 212 is pulled up by the power supply Vcc. Note that the open collector 213 is
For example, 7406 manufactured by Texas Instruments may be used. Now, when the limiter timing signal 250 becomes high level (1), the output of the open collector 213 becomes low level, and the resistor 206 and diode 20
5, the level of the limiter output signal 111 is limited to the limit voltage VL. This is because when the base voltage of the PNP transistor 203 that constitutes the emitter follower exceeds the limit voltage vL, the PNP transistor 203 is turned off, and the power supply Vcc is divided into voltages determined by the resistors 204 and 206 and the diode 205. This is because this divided voltage, that is, the limiting voltage VL, becomes the same emitter voltage. On the other hand, when the base voltage is below the limit voltage vL,
Since the PNP ) transistor 203 is turned on, the reproduced signal S1 becomes the emitter voltage of the same transistor 203 almost as it is, and becomes the limiter output signal 111 without being limited in its amplitude. Similarly, regarding the reproduced signal S2, if the base voltage of the PNP transistor 2゜9 that constitutes the emitter follower exceeds the limit voltage vL, the PN
The P transistor 209 is turned off, and the power supply Vcc is divided into voltages determined by the resistors 210 and 206 and the diode 211, and this divided voltage, that is, the limiting voltage ■
, becomes the same emitter voltage. On the other hand, when the base voltage is below the limit voltage vL, the PNP l-transistor 209 is turned on, and the reproduced signal S2 is not limited and becomes the limiter output signal 113 as it is. Note that in the above configuration, it is possible to limit the reproduced signals S1 and S2 at the same time using the limiter timing signal 250, and when the limiter timing signal 250 is at a high level (1), the reproduced signals S1 and S2 can be limited at the same time.
The level of S2 is limited, and is not limited when it is at low level (O).

Based on FIG. 3, one embodiment of the block 109 in FIG. 1, which functions as both a bypass filter and an amplifier, will be described below.

The limiter output signal 111 is mainly provided by the capacitor 30.
1, Resistance 302.303.305.306.30B, N
PN) transistors 304 and 309, a bypass filter consisting of a variable resistor 307, and a circuit that also functions as an amplifier. The degree of amplification of this output signal 115 can be adjusted by a variable resistor 307. The limiter output signal 113 is also input to a circuit having a bypass filter and an amplifier function having a similar configuration, and the amplification degree of the output signal 116 of the circuit is fixed and cannot be adjusted. Although the case where the amplification degree of the output signal 116 is fixed has been described above, the present invention is not limited to this, and the amplification degree may be variable like the output signal 115.

Output signals 115 and 116 of these buffer amplifiers 110
is transmitted to the next stage differential amplifier and summing amplifier (none of which are shown in the figure).

Based on FIG. 4, the MO waveform processing section 2 shown in FIG.
502 and the main parts of the preformat waveform processing section 2503 will be explained below.

The output signals 115 and 116 of the buffer amplifier 110 are MO
The signal is input to a differential amplifier 401 and a summing amplifier 403 in a waveform processing section 2502 and a preformat waveform processing section 2503, respectively. By differentially amplifying the reproduced signals S1 and S2 in the differential amplifier 401, the S/N
It is possible to improve the ratio and at the same time extract only the information in the MO (data) section 3002. Note that the differential ratio when performing differential operation is, for example, the variable resistor 30 in Figure 3.
7 to adjust to an appropriate differential ratio.

The output signal 410 of the differential amplifier 401 is sent to the AGC amplifier 40.
2 and is controlled to an appropriate signal level. AGC
The output signal 411 of the amplifier 402 is input to the next stage binarization circuit (not shown in the figure), and the MO (data) section 3
The information of 002 is binarized and read. Furthermore, by adding the reproduced signals Sl and S2 in the summing amplifier 403, only the information in the preformat section 3002 can be extracted. This output signal 412 is input to an AGC amplifier 404 and controlled to an appropriate signal level.

This output signal 413 is input to the next stage binarization circuit (not shown in the figure), and the information in the preformat section 3003 is binarized and read.

FIG. 5 shows waveforms of various parts of the limiter circuit shown in FIG. 2. In FIG. 5, the preformat section 37
Information is recorded in the sector (see FIG. 5(a)) consisting of MO (data) section 3702 and MO (data) section 3702.
Information is reproduced in a sector composed of a preformat section 3703 and an MO (data) section 3704, and a sector consisting of a preformat section 3705 and an MO (data) section 3
It is assumed that information is erased in the sector consisting of 706 and 706. Each operation of recording, reproducing, and erasing these information is performed by the preformat section 3701.3703.370.
The synchronization timing information and address information of No. 5 are read out, and the process is performed while sequentially confirming that a predetermined synchronization timing is detected and that it is a predetermined address. Now, the reproduced signals S1 and S2 become signals whose amplitudes are excessive during each recording/erasing operation (see FIG. 3(b)). This is because during each recording/erasing operation, reflected light with high light intensity from the sector enters the photodetectors 3203 and 3204. At this time, the limiter output signal 111.1
13 is the voltage limited by the limiters 101 and 105 as described above.

limited to the level of The period in which the limiter output signal is limited is controlled by a limiter timing signal 250 (see (e) in the figure). That is, the recording section in the MO (data) section 3702 and the MO (data) section 3
The level is limited in the erasure section at 706 (see (C) in the same figure). Buffer amplifier output signal 11
5. The waveform immediately after each recording/erasing operation in 116 is almost unaffected by the transient response of the bypass filter (see (d) in the same figure). Therefore, since the playback limit level range is not exceeded, the synchronization timing information of the preformat sections 3703 and 3707 is read immediately after each recording/erasing operation.
and address information can be read out, and recording, reproducing, and erasing operations can be performed while sequentially confirming that a predetermined synchronization timing is detected and that the address is a predetermined address. As a result, it becomes possible to transfer information at high speed and increase optical density in the magneto-optical disk device.

It is sufficient that the limiter timing signal 250 is at a high level (1) in each recording/erasing period, that is, in a period in which the light intensity of the semiconductor laser 2801 is not at the time of reproduction. For example, the high frequency superimposed switch signal 1812 shown in FIGS. 14 and 15 may be used as is as the limiter timing signal. At this time, the operation of the high frequency superposition circuit 1802 in FIG. 14 may be delayed with respect to the high frequency superposition switch signal 1812. In this case, the limit section by the limiter timing signal 250 may be expanded somewhat to account for the delay in the operation. Further, a signal having a section similar to that described above, such as the data modulation timing in the modulation circuit 1302 in FIG. 9, may be used.

Regarding the amplitude limit level (■) in the limiters 101 and 105, the M
It is highly effective to set the average level of the signal in the O (data) section to be near the level of the preformat signal. That is, if the upper edge level of the signal in the preformat section is Vg, and the lower edge level of the signal in the MO (data) section during recording is v4, then ■a≦■,≦■. + (Vu Va ). One reason for this is that the effects of transient responses can be minimized. Another reason is that the level error of the reproduced signals S1 and S2 between a plurality of magneto-optical disks of the same type and within the same magneto-optical disk is approximately within the above range. Level errors in the reproduced signals Sl and S2 are caused by, for example, reflectance changes between a plurality of magneto-optical disks of the same type and within the same magneto-optical disk. In addition, the above limit level (■) is set slightly higher than the upper edge level vu of the signal in the preformat section,
Limiter-timing signal 250 is always at high level (1
), the same effect can be obtained.

Now, as shown in FIG. 7, the magneto-optical disk 1201 is
In addition to the data area 702 where information is recorded, reproduced, and erased, some devices have another area called a control track 701 that is made up of a plurality of tracks on the inner circumference side. This is to prevent erroneous recording, reproducing, and erasing from one magneto-optical disk with different characteristics and format. This will be explained in detail below.

There are many different types of magneto-optical disks 1201 depending on the characteristics of the recording magnetic film and the format. Therefore, it is difficult for one magneto-optical disk device to perform recording, reproducing, and erasing operations on all types of magneto-optical disks. In other words, it is necessary to perform each operation of recording, reproducing, and erasing information only in a magneto-optical disk device compatible with the characteristics and format of the magneto-optical disk. For example, if two types of magneto-optical disks with different characteristics and formats are A and B, and the corresponding magneto-optical disk devices are Da and Db, respectively, then information is recorded on the magneto-optical disk A in the magneto-optical disk device Da. Although it is possible to reproduce and erase information, it is not possible to record, reproduce, or erase information in the magneto-optical disk device Db. Further, although information can be recorded, reproduced, and erased on the magneto-optical disk B in the magneto-optical disk device Db, information cannot be recorded, reproduced, and erased in the magneto-optical disk device Da. In this case, the following problems may occur, for example. Information may be recorded, reproduced, or erased on the magneto-optical disk A by mistake in the magneto-optical disk device Db. In this case, there is a risk that the information in the magneto-optical disk A may be destroyed, credibility may be lost, and even the magneto-optical disk A itself may be destroyed.

In order to solve such problems, for example, the following measures have been proposed. Information on its characteristics and format is inscribed in advance in the magneto-optical disk A using physical uneven marks and non-marks, and only this preformat information can be used by any other optical device including the magneto-optical disk device Db. It can also be played on magnetic disk devices,
We should make sure that we can do it. In this way, the characteristics of the magneto-optical disk A can be checked before recording, reproducing, or erasing.
It is possible to detect differences in format and to stop subsequent recording, playback, and erasing operations. The control track 701 is an area in which this preformat information is recorded. Information is not recorded or erased in this area. control track 7
The format of the preformat information 01 is unified so that it can be read by all magneto-optical disk devices even if the magneto-optical disks have different characteristics (eg, reflectance).

Based on FIG. 6, the characteristics of the control track 701 and reproduction of format information will be described below.

As shown in FIG. 7(a), a control track 701
Unlike the data area 702 shown in FIG. 7, the characteristics and format of the magneto-optical disk 1201 are inscribed in advance with marks in the form of physical unevenness and non-marks (preformat). Each waveform shown in FIG.
In a, this is for recording, reproducing, and erasing,
The waveforms in FIG. 6 are for the case where, for example, the characteristics and format information in the control track are reproduced from the magneto-optical disk B in the magneto-optical disk device Da. Furthermore, each waveform in FIG. 6 is an example in which the reflectance of the magneto-optical disk B is larger than that of the magneto-optical disk Δ, and the levels of the reproduced signals S1 and S2 in FIG. 6 (see (b) in the same figure) are , is higher than that shown in FIG. When reproducing this control track 701, the limiter timing signal 250 is set to low level (0) (see (e) in the same figure). At this time, limiter 101,
105 does not limit the level of the signal amplitude,
Limiter output signal 111113 (see figure (c))
The AC component of buffer amplifier output signal 115.
The buffer amplifier output signals 115 and 116 output as 116 (see (d) in the same figure) are A in FIG.
The GC amplifiers 402 and 404 control the signal level to an appropriate level, and read the characteristics and format of the magneto-optical disk B. In other words, the characteristics of magneto-optical disk B,
Since the format and format can be detected, it is possible to avoid erroneous recording, playback, and erasing operations. Furthermore, this result can be notified to an external device, or the fact that the magneto-optical disk has different characteristics and format can be notified by display means or the like.

In this way, the limiter circuit 101.1 shown in FIG.
05, the synchronization timing information and address information of the preformat sections 3703 and 3707 can be read out immediately after each recording/erasing operation, and it is possible to detect that the predetermined synchronization timing is detected and that it is the predetermined address. Each operation of recording, reproducing, and erasing information can be performed while checking the information one by one. That is, it is possible to transfer information at high speed and increase the density in the magneto-optical disk device without being affected by the transient response of the bypass filter and the response of the AGC amplifier. Furthermore, it is possible to avoid accidentally recording, reproducing, or erasing information on magneto-optical disks with different characteristics and formats, which may result in information being destroyed and reliability, or damage to the magneto-optical disk itself. The risk of destruction can also be avoided in advance.

[Embodiment 2] A second embodiment of the information recording/reproducing apparatus according to the present invention will be described below based on FIGS. 24 to 27. Note that members having the same functions as those used in Example 1 are designated by the same reference numerals, and their descriptions are omitted for convenience.

FIG. 24 shows another example of the limiter of the information recording/reproducing apparatus according to the present invention. The reproduced signal S1 is mainly generated by resistors 801, 802, 804 and PN in the limiter 101.
P) is input to an emitter follower composed of a transistor 803. The emitter follower output signal 111 is transmitted to the emitter of transistor 805 and capacitor 102. The output signal 112 of the bypass filter, which includes a capacitor 102 and a resistor 103, is
The signal is transmitted to the next stage buffer amplifier 104 (not shown in the figure). On the other hand, the base of transistor 805 is resistor 8
It is connected to voltage 1 through 06. The amplitude of the limiter output signal lit is level limited to the emitter voltage of the PNPI transistor 805. This is because, assuming this limiting voltage is ■1, ■LζVl +VB! (v!lE: voltage between transistor 80517) and emitter), and the level of the reproduced signal S1 increases to PNP)
When the base voltage of the transistor 803 exceeds the emitter voltage, the PNP transistor 803 turns off. At this time, the PNP) transistor 805 is turned on.

Along with this, the level of the limiter output signal 111 is
It becomes the level of (Vl + VIIE). That is, if the limit voltage (1) is set to approximately the level of (V++Vmt), the level of the reproduced signal 510 will be equal to the limit voltage vL.
On the other hand, when the level of the reproduced signal S1 becomes small and the base voltage of the PNP I-transistor 803 is smaller than the emitter voltage, that is, the above-mentioned limit voltage vL, the PNP I-transistor 803 turns on. At this time, the PNP transistor 805 is turned off, and the reproduced signal S1 is directly output as the limiter output signal 111 to the next-stage buffer amplifier via the bypass filter.

Similarly, for the reproduced signal S2, the limit voltage vL is approximately (
If the level of the reproduced signal S2 is lower than the limit voltage vL, it is output as the limiter output signal 113 to the next stage buffer amplifier via the bypass filter, and the reproduced signal Even if the level of signal S2 is greater than the limit voltage Vt,
Limited voltage ■.

It doesn't get any bigger. Note that the details of the circuit operation are the same as in the case of the reproduced signal S1, so the explanation thereof will be omitted for convenience.

In addition, in this example, the limit voltage is V to simplify the circuit.

is set to the same level for the reproduced signal S1 and the reproduced signal S2, but the limit level is not limited to this (limiting levels may be set individually).

The operating waveforms of each part of the limiter circuit shown in FIG. 24 will be explained below based on FIG. 25.

As shown in FIG. 25, information is recorded in a sector consisting of a preformat section 3701 and an MO (data) section 3702, and a preformat section 3703 and an MO (data) section 3702 record information.
Information is reproduced in the sector consisting of the O (data) section 3704, and the preformat section 3705 and MO
It is assumed that information is erased in the sector constituted by the (data) section 3706 (see FIG. 3(a)). These recording, playback, and erasing operations are carried out by the preformat section 3.
The synchronization timing information and address information of 701.3703.3705 are reproduced and read out, and the process is performed while sequentially confirming that a predetermined synchronization timing is detected and that it is a predetermined address. Now, as shown in FIG. 4B, the reproduced signals S1 and S2 become signals with excessive amplitudes during each recording and erasing operation. This is because the reflected light with high optical intensity from the magneto-optical disk 1201 during recording and erasing is incident on the photodetectors 3203 and 3204. At this time, the excessive amplitude contained in the limiter output signals 111 and 113 is
The water control voltage is limited to the water control voltage vL by (see (C) in the same figure). Note that in this second embodiment, unlike the first embodiment, there is no jump during each recording/erasing operation, and the level is limited during the reproducing operation as well. Along with this, the waveforms of the buffer amplifier output signals 115 and 116 immediately after each recording/erasing operation are hardly affected by the transient response of the bypass filter (see FIG. 3(d)). Therefore, since the playback limit level is not exceeded, the synchronization timing information and address information of the preformat sections 3703 and 3707 can be read out accurately immediately after each recording/erasing operation, and the predetermined synchronization timing is detected. Moreover, since it becomes possible to perform recording, reproduction, and erasing while sequentially confirming that the address is a predetermined address, high-speed information transfer and increased optical density in the magneto-optical disk device become possible.

Note that in this second embodiment, it may not be possible to reproduce the characteristics and format information in the control track 701 of a magneto-optical disk with different characteristics and format. This will be explained in detail below based on FIG. 26.

FIG. 26 is a diagram showing the characteristics in the control track 701 and the waveforms of various parts during reproduction of the format information. As shown in FIG. 7A, the control track 701 differs from the data area shown in FIG. is engraved (preformat)
.

For example, the waveform shown in FIG.
On the other hand, the waveforms in FIG. 26 correspond to the case where each operation of reproducing and erasing is performed. On the other hand, the waveforms in FIG. This corresponds to the case of playing. That is, the waveform example in FIG. 26 is an example in which the reflectance of the magneto-optical disk B is higher than that of the magneto-optical disk A, and the reproduced signal S1,
The level of S2 is higher than that shown in FIG. Therefore, the signal level may exceed the limit level (2) shown in the figure. In other words, as shown in Figure (c), the limiter output signals 111 and 113 are saturated at the limit level ■ (the broken line in Figure (C) is the reproduced signal Sl).
, shows the amplitude before the amplitude of S2 is limited), the same figure (d
), the buffer amplifier output signal 115.11
In some cases, the reproduced signal does not appear during the period 6 (this differs depending on the setting value of the limit level vL). After all, since the characteristics and format of the magneto-optical disk B cannot be detected, information may be recorded, reproduced, or erased erroneously. Therefore, although the second embodiment shown here is effective in high-speed information transfer and high density in a magneto-optical disk device, the recording, reproducing, and recording of information on magneto-optical disks with different characteristics and formats is effective. The erasure is
In fact, it is difficult. To solve this problem, a PNP l-transistor 805.8 shown in FIG.
The voltage 1 applied to the base of 11 may be switched by the limiter timing signal 250.

Further, the limiter circuits 101 and 105 are not limited to the circuit shown in FIG. 24, and the same effect can be obtained even if a circuit shown in FIG. 27 is used, for example. The circuit operation will be explained below.

The circuit illustrated here is a limiter using an operational amplifier.
It is a circuit. The reproduced signal S1 is transmitted to the inverting input of the operational amplifier 1105 via the resistor 1101. At this time, when the amplitude of the reproduced signal S1 exceeds the reference voltage v2, the output voltage of the amplifier 1105 changes from a positive sign to a negative sign output voltage, but is limited to the rated output voltage value of the constant voltage diode 1104. In addition, the level of the reproduced signal S1 is the reference voltage ■2
In the following cases, the output voltage of the amplifier 1105 changes from a negative sign to a positive sign output voltage, but the voltage regulator diode 11
The output voltage will not be higher than the rated output voltage value of 03. As described above, the amplitude of the reproduced signal S1 is limited to the rated output voltage value (two positive and negative limit levels) of the constant voltage diodes 1103 and 1104, and is transmitted as the limiter output signal 111 to the subsequent bypass filter. Similarly, when the amplitude of the reproduced signal S2 exceeds the reference voltage v2, it is limited to the rated output voltage value of the voltage regulator diode 1109. The output voltage will not exceed the rated output voltage value. As described above, in the limiter circuit illustrated here, the rated output voltage value of the constant voltage diode becomes the limiting voltage value, and unlike the case shown in FIG. Level restrictions can be applied.

In the limiter circuit described above, the limiter limiting voltage is set to the same level as the reproduced signals 31 and 32, thereby simplifying the circuit configuration. However, in some magneto-optical disk devices, the level of the reproduction signal S1 and the level of the signal 32 may be different. For example, errors due to the characteristics of the reproduction optical system, reproduction signal S in the reproduction optical system, etc.
The reason for this is the difference in the reproduction method between 1 and S2. In such a case, unlike the above case, the same effect as above can be obtained by setting different limiter limiting voltages for the reproduced signals S1 and S2.

Furthermore, especially in optical memory devices including magneto-optical disk memory devices, as shown in FIG. 5 or FIG.
For example, the levels during each recording and erasing operation tend to be extremely biased toward the higher levels in the diagram. Therefore, in the present invention, as shown in FIGS. 2 and 24, a limiter that limits only the high level of the signal level is used, making it possible to simplify the circuit configuration. However, if the signal level tends to be biased toward lower levels, the circuit is not limited to the one shown above, and a limiter circuit for limiting the low level may be used, as shown in FIG. 27, for example.

In addition, in a magneto-optical disk memory device, -i is
As shown in the above two embodiments, two reproduction signals (
SI, S2), two limiter circuits (101, 105) are also provided correspondingly. However, there are some devices, such as write-once optical memory devices, which have only one reproduction signal, and in this case, only one limiter circuit is required.

In addition, in Figures 2, 3, and 24, P
Although NP ) transistors 203 and 209 are used, the present invention is not limited to this, and a configuration consisting of NPN ) transistors may also be used. Furthermore, the same effect as described above can be obtained by using a sample and hold circuit instead of the limiters 101 and 105 to hold the reproduced signals Sl and 32 in each recording/erasing interval and sample them in the reproduction interval. However, sample-and-hold circuits are generally complex and expensive, and have poor frequency characteristics, so the quality of reproduced signals tends to deteriorate, which hinders high-speed information transfer and high density. Furthermore, the same effect as described above can be obtained by using an analog switch instead of the limiters 101 and 1050 and fixing the reproduced signal to a constant voltage during recording and erasing. However, in this case, the switching pulse that is generated when switching the analog switch is often thicker than the playback signal, and this switching pulse can cause an adverse effect on the playback operation (for example, the AGC, PLL, etc.) On the other hand, as shown in FIG. 2, according to the present invention, the above effects can be obtained with a simple and inexpensive circuit.

Although the present invention has been described using a magneto-optical disk memory device as an example, it is not limited to this, and may be applied to other magneto-optical memory devices such as a magneto-optical card memory device, or other optical memories such as a write-once optical memory device. equipment, as well as information recording, playback, and
It is also applicable to other information recording/reproducing devices such as magnetic disk devices that perform erasing.

〔Effect of the invention〕

As described above, the information recording and reproducing apparatus according to the present invention is an information recording and reproducing apparatus that records, reproduces, or erases information, and in which an excessive amplitude contained in a reproduced signal during each operation of recording and erasing information is provided. In this configuration, a signal level limiting means for limiting the signal level to a predetermined level is provided upstream of a reproducing circuit that reproduces information. As a result, the A received by the reproduction signal in the preformat section immediately after each recording/erasing operation is
The influence of the transient response of C-coupling can be suppressed, and the repeat signal can always be kept within the playback limit level range. Therefore, the synchronization timing information of the preformat section immediately after each recording/erasing operation, and Address↑n information can be read accurately, predetermined synchronization timing can be detected, and information can be recorded and erased while sequentially confirming that it is a predetermined address.
The arrangement of the preformat section can be determined without being influenced by the transient response of the coupling or the response of the AGC circuit, and high-speed transfer of information and high density in the magneto-optical disk memory device become possible. In addition, it is possible to avoid accidentally recording, reproducing, or erasing information on magneto-optical disks with different characteristics and formats, which could lead to information being destroyed and credibility lost, or the magneto-optical disk itself being destroyed. This also has the advantage of being able to avoid such risks in advance.

[Brief explanation of drawings]

1 to 7 show one embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of a buffer amplifier. FIG. 2 shows a limiter of the information recording and reproducing device according to the present invention.
FIG. 2 is a diagram showing a circuit configuration of a circuit. FIG. 3 is a diagram showing a circuit configuration in which the degree of amplification can be varied with respect to the output signal of the limiter circuit. FIG. 4 is a block diagram showing the circuit configurations of the MO waveform processing section and the preformat waveform processing section. FIG. 5 is a diagram showing waveforms of various parts of the limiter circuit shown in FIG. 2. FIG. 6 is an explanatory diagram of the characteristics of the control track and the reproduction of format information. FIG. 7 is a plan view showing a magneto-optical disk equipped with a control track. 8 to 23 are for explaining the structure of the magneto-optical memory device according to the present invention. FIG. 8 is a block diagram showing the configuration of the magneto-optical memory device. FIG. 9 is a block diagram showing the configuration of the recording circuit. FIG. 10 is a block diagram showing the configuration of the reproducing circuit. FIG. 11 is a block diagram showing the configuration of the controller. FIG. 12 shows an example of a modulation method for recording information of 2.7
FIG. 3 is a diagram illustrating a modulation method. FIG. 13 is a diagram showing a sector format. FIG. 14 is a diagram showing the configuration of a semiconductor laser drive circuit. 15 and 16 are diagrams showing waveforms of various parts of the semiconductor laser drive circuit during each information recording/erasing operation and reproducing operation in FIG. 14. FIG. 17 is a block diagram showing the configuration of the timing generation circuit. FIG. 18 is a block diagram showing the configuration of a sector mark detection circuit. FIG. 19 is a diagram schematically explaining the operation of the counter configuring FIG. 18. FIG. 20 is a diagram showing waveforms of each part of the timing generation circuit. FIG. 21 is a block diagram showing the configuration of the signal processing circuit. FIG. 22 is a diagram showing waveforms of each part of the signal processing circuit. FIG. 23 is a diagram explaining FIG. 22 in more detail, and M
FIG. 3 is a diagram illustrating a process of generating binarized data from marks in an O (data) section and a preformat section. 24 to 27 show other embodiments of the present invention. FIG. 24 is a diagram showing another example of the limiter of the information recording/reproducing apparatus according to the present invention. FIG. 25 is a diagram showing operating waveforms of each part of the limiter circuit shown in FIG. 24. FIG. 26 is a diagram showing waveforms at various parts of the buffer amplifier when the characteristics and format information cannot be reproduced in the control track in magneto-optical disks with different characteristics and formats. FIG. 27 is a diagram showing a modification of the limiter. 28 to 38 are diagrams showing conventional examples. FIG. 28 is a diagram illustrating each operation of recording information on the magneto-optical disk and erasing information recorded on the magneto-optical disk. FIG. 29 is a diagram showing the reproduction operation of the magneto-optical disk. FIGS. 30 and 31 are diagrams showing the relationship between the preformat section and the MO (data) section on the magneto-optical disk. FIG. 32 is a block diagram showing the configuration of the main parts of the optical system during reproduction. FIGS. 33 and 34 are explanatory diagrams of the respective polarities of reproduction signals S1 and S2 in the MO (data) section and the preformat section. FIG. 35 is a diagram showing the relationship between the reproduction circuit, the address generation circuit, and the timing generation circuit. FIG. 36 is a block diagram showing the configuration of the buffer amplifier. FIG. 37 is a diagram showing the effect on the output signal of the buffer amplifier when an excessive amplitude is input to the AC coupling section which is the input stage of the buffer amplifier shown in FIG. 36. FIG. 38 is a diagram showing the expression given to the output signal of the AGC amplifier when an excessive amplitude is input to the AC coupling section which is the input stage of the buffer amplifier shown in FIG. 36. 101.105 is a limiter (signal level limiting means),
402 and 404 are AGC amplifiers, 1201 is a magneto-optical disk, 1203 is an optical disk, 1206 is a recording circuit, 1
207 is a reproduction circuit, and 1208 is a controller. Figure 3 L ++ J Figure 27ゝ101.105 30 m 3001 Figure 31

Claims (1)

[Claims] 1. In an information recording/reproducing device that records, reproduces, or erases information, a signal level limiting means for limiting excessive amplitude contained in a reproduced signal during each operation of recording/erasing information to a predetermined level is installed. An information recording and reproducing device characterized in that it is provided in a preceding stage of a reproducing circuit that performs reproduction.