JP2584795B2 - Magneto-optical information recording and erasing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for recording information on a magneto-optical recording medium and erasing the recorded information.

(Prior art)

2. Description of the Related Art Conventionally, as an erasable recording medium, for example, a magneto-optical recording medium 52 whose sectional view is schematically shown in FIG. 6A is known. This magneto-optical recording medium has a magnetic film whose easy axis of magnetization is perpendicular to the film surface as the recording layer 53. Information is recorded,予Jime keep aligned the magnetization direction of the recording layer 53 in one direction, while applying a magnetic field M _R in a reverse direction with respect to the direction from the outside, is intensity modulated in accordance with recording layer in the information Light beam 54
This is done by scanning with. The portion of the recording layer irradiated with the light beam once loses its magnetization, and is magnetized in the opposite direction to the other portion by the external magnetic field to form a recording bit 55 corresponding to the information as shown in FIG. 6 (B). . Information recorded in this manner is obtained by irradiating a low intensity unmodulated light beam to the recording layer and detecting the reflected light or transmitted light thereof.
Readout is performed by a known method using the magneto-optical effect. Further, the recorded information recorded at the opposite direction (i.e., the recording layer before recording direction is magnetized) irradiating the light beam 56 in a region where information is recorded while applying an external magnetic field M _E of.

When erasing information as described above, an erasing light beam needs to accurately scan an area where information has been recorded, in order to perform reliable erasure without leaving unerased data. Therefore, Japanese Patent Application Laid-Open No. 58-83347 proposes to increase the power of the light beam at the time of erasing compared to that at the time of recording. This is because, by making the erasing range by the light beam larger than the width of the recording bit, erasing can be surely performed even if a slight shift of the scanning area occurs in a direction perpendicular to the continuous direction of the recording pit row (so-called tracking direction). It is a technique for performing.
However, although errors in the tracking direction can be tolerated by the above technique, they are still insufficient when considering errors in the beam scanning direction. This will be described below.

As shown in a schematic plan view in FIG. 7A, a magneto-optical recording medium is generally divided into predetermined units called sectors. Each sector is further divided into an address area and a recording area, and a gap is provided between them. In the address area, an address number or the like indicating the position of the sector on the medium is recorded in advance by a non-erasable bit 58 formed by irregularities on the medium substrate. Then, the recording bit is recorded in the recording area by the method described above.
Are magnetically recorded. This sector is separated from the next sector by a sector gap.

Here, when erasing the recording bit 57, the seventh
The recording area may be scanned by the erasing light beam spot 59 as shown in FIG. However, if the lighting of the light beam is delayed or turned off too early due to an error in the timing count for turning on / off the beam or unevenness of the beam scanning speed, as shown in FIG. 7 (C). A recording bit 60 is left unerased. Such an unerased portion 60 causes a reduction in the reliability of recording when information is re-recorded in this area.

[Summary of the Invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magneto-optical information recording and erasing apparatus capable of solving the above-mentioned drawbacks of the prior art and reliably erasing information recorded on a recording medium.

The object of the present invention is to provide a medium including a unit for scanning a magneto-optical recording medium with a light beam, a unit for applying a magnetic field to the medium, and a gate unit for controlling a period of irradiation of the medium with the light beam. Information is recorded by irradiating a light beam while applying a magnetic field in a predetermined direction to the medium, and information recorded by irradiating the same light beam as during recording while applying a magnetic field in a direction opposite to the predetermined direction to the medium. In the magneto-optical information recording and erasing apparatus for erasing, the gate means starts irradiating the medium with a light beam at the time of erasing earlier than at the time of recording, and at the time of erasing the light beam to the medium later than at the time of recording. The irradiation period of the light beam on the medium is switched between recording and erasing so that the irradiation is completed, and the information is erased from the length of the area where the information is recorded on the medium in the scanning direction of the light beam. It is achieved by increasing the length of that region before and after.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment for recording and erasing magneto-optical information according to the present invention. In the figure, 31 is a host computer, 61 is a disk drive, 50 is a controller for controlling the operation of the drive 61, 32 is a host interface connecting the host 31 and the controller 60, and 41 is a drive interface connecting the drive 61 and the controller. is there. A magneto-optical disc 46 is mounted in the drive 61, and the disc 46 is rotated by a spindle motor 47. The rotating disk 46 is irradiated with a light beam from an optical head 62 to record, reproduce and erase information. Light head 62
Includes a semiconductor laser 48 as a light source, an optical system for condensing a light beam emitted from the semiconductor laser on a disk, and a photodetector 49 for detecting light reflected from the disk. drive
61 further includes a digital demodulation circuit 42, a digital modulation circuit 43, a laser drive circuit 44, a drive-side central processing unit (CPU) 45, and an external magnetic field applying means 51. Also the controller
50 is a buffer memory 33, a microprocessor (MPU)
34, an address reproducing circuit 35, an error correction code (ECC) decoder 36, an ECC encoder 37, a write gate control circuit 38, a read gate control circuit 39, and a command status 40.

 Next, the operation of this device will be described.

At the time of recording, first, a command to record information is sent from the CPU 45 to the MPU 34 via the command status 40. Then, when the permission signal S _A is input from the CPU 45, the read gate signal S _RG is sent from the read gate control circuit 39 to the laser drive circuit 44. Then, the semiconductor laser 48 emits light continuously in the read mode, that is, at low intensity, and the light beam is scanned on the disk 46. The reflected light from the disk 46 is detected by the photodetector 49, and the detection signal is input to the address reproduction circuit 35 through the digital demodulation circuit 42. The address reproducing circuit 35 reproduces the address number recorded on the disk 46. And the reproduced address number is MPU34
When the address coincides with the address number of the target sexual address specified by, an enable signal is output from the address reproduction circuit 35 to the ride gate control circuit 38. Then, the write gate signal _SWG corresponding to the recording area on the disk 46 is output from the ride gate control circuit 38 to the laser drive circuit 44. Record information is sent from the host 31 to the host interface
The data is temporarily stored in the buffer memory 33 via the memory 32. This information signal is input to the laser drive circuit 44 through the ECC encoder 37 and the digital modulation circuit 43. Then, when the write gate is on, the semiconductor laser blinks in response to the information signal, and information is recorded on the disk 46.

When erasing the information recorded in this way, the same operation as described above is performed until the enable signal is output from the address reproduction circuit 35. However, an instruction of the erasing mode is issued from the MPU 34 to the write gate control circuit 38, and a gate signal longer than that at the time of recording is output. The laser drive circuit causes the semiconductor laser to emit light while the gate signal is on. As a result, the same light beam as during recording scans an area that is longer before and after than the recording area, that is, an area from the gap to the sector gap. Therefore, even if a slight error occurs in the scanning direction, the information can be surely erased.

Next, a specific configuration example of the write gate control circuit 38 is shown in FIG. In the figure, 1 and 2 are gate signal ON control circuits, and 3 and 4 are gate signal OFF control circuits, respectively. Each of these control circuits is composed of a counter and a plurality of transistor-transistor logics (TTL). When the count value of the counter reaches a predetermined value, a pulse corresponding to one clock is output to stop. 5
And 6 are latches, respectively, and 8, 9, 10, and 11 are output lines from the control circuit, respectively. 12 is the gate signal, 13 is
A control signal for selecting a circuit input from the MPU 34, an enable signal 14 for operating a counter input from the address reproducing circuit, a clock signal 15 input from an internal clock signal generator (not shown), and a multiplexer 18.

The operation of the circuit shown in FIG. 2 will be described below. Here, it is assumed that the control circuits 1 and 2 are for data recording and the control circuits 3 and 4 are for data erasure.

At the time of data recording, first, the multiplexer 18 selects the A terminal according to the control signal 13 from the MPU 34, and the gate signal 12 is controlled by the control circuits 1 and 2. In this state, when the enable signal 14 inputted from the address reproducing circuit 35 becomes active as shown in FIG. 3 (A), the counters in the control circuits 1 and 2 are respectively shown in FIGS. 3 (B) and 3 (D).
The counting of the clock signal 15 is started as shown in FIG. Here, the set value of the counter in the control circuit 1 is made smaller than the set value of the counter in the control circuit 2. When the count value of the counter in the control circuit 1 becomes equal to the set value, a coincidence pulse as shown in FIG. 3 (C) is output to the line 8 and is latched by the latch 5 as shown in FIG. 3 (F). output
16 becomes active. Since the set value of the counter of the control circuit 2 is larger than the set value of the counter of the control circuit 1, the count value of the counter of the control circuit 2 becomes equal to the set value after the coincidence pulse shown in FIG. The coincidence pulse shown in FIG. The output 16 is reset by the latch 5 as shown in FIG. 3 (F). Since the multiplexer 18 selects the A terminal, this output 16 is directly used as the gate signal 12.
Is input to the laser drive circuit 44 described above. The rising of the enable signal 14 is made coincident with the detection of the end of the address area on the recording medium shown in FIG. 4, and the set value of the counter of the control circuit 1 is changed during the time when the light beam is traversed through the gap section by the counter of the control circuit 2. If the set value is made to coincide with the period in which the light beam crosses the gap section and the data recording area, the gate signal 12 has the gate timing at the time of recording shown in FIG.

At the time of data erasure, according to the control signal 13 from the MPU 34,
The multiplexer 18 selects the B terminal and is switched such that the gate signal 12 is controlled by the control circuits 3,4. In this state, when the enable signal 14 input from the address reproducing circuit 35 becomes active, the counters in the control circuits 3 and 4 start counting the clock signal 15 as in the recording. Here, the set value of the counter in the control circuit 3 is set smaller than the set value of the counter in the control circuit 4. When the count value of the counter in the control circuit 3 becomes equal to the set value, a coincidence pulse is output on the line 9 and is latched by the latch 6 so that the output 17 becomes active. Since the set value of the counter of the control circuit 4 is larger than the set value of the counter of the control circuit 3, the count value of the counter of the control circuit 4 becomes equal to the set value after the coincidence pulse is output to the line 9, and the line 11 Outputs a coincidence pulse. The output 17 is reset by the latch 6. Since the multiplexer 18 selects the B terminal,
This output 17 is used as the gate signal 12 as described above for the laser drive circuit.
Entered in 44. As in the case of recording, the rise of the enable signal 14 is made coincident with the detection of the end of the address area on the recording medium shown in FIG. 4, and the set value of the counter of the control circuit 3 is output as a coincidence pulse in the middle of the gap. When the setting value of the counter of the control circuit 4 is set so as to output the coincidence pulse in the sector gap following the data recording area, the gate timing at the time of erasing shown in FIG. 4 is obtained. Driving of the semiconductor laser 44 in FIG. 1 is performed according to these gate timings. Therefore, at the time of erasure, the light beam scans a larger area than at the time of recording, and the information can be surely erased as described above.

FIG. 5 is a block diagram showing another example of the configuration of the write gate control circuit in the device shown in FIG. In the example of FIG. 2, a separate circuit is provided for changing the laser lighting permission period by the gate signal at the time of recording and at the time of erasing, but in this example, the gate signal is controlled by one type of control circuit. It is. In the figure, 20 is a control circuit for turning on a gate signal, 21 is a control circuit for resetting a gate signal, 22 and 23 are latches for setting counters in the control circuit, 24 is a latch for outputting a gate signal, 25 is a gate signal, and 25 is a gate signal. 26 and 27 are output lines from the respective control circuits, 28 is an MPU bus from the MPU, 29 is an enable signal from the address reproducing circuit, and 30 is a clock signal from an internal clock signal generator (not shown).

At the time of data recording, a set value is output from the MPU bus 28 to the latch 22 by the aforementioned MPU 34 so that a coincidence pulse of the control circuit 20 is output to the line 26 at the end of the gap shown in FIG. Also, the latch 23 is set to a set value such that a coincidence pulse of the control circuit 21 is output when the recording area ends.

Similarly, at the time of erasing, a setting value such that a coincidence pulse of the control circuit 20 is output to the latch 22 in the middle of the gap section of FIG. Is output. As described above, by changing the set value of the counter in the control circuit by the MPU at the time of recording or erasing, the same timing of the gate signal as shown in FIG. 4 can be obtained.

The present invention is conceivable in various modifications and applications other than the above-described embodiment. For example, in the above embodiment, a counter is used as a means for changing the timing of information recording and erasing, but a high-speed sequencer may be used. The present invention embraces all such modifications and applications without departing from the scope of the claims.

〔The invention's effect〕

The present invention is directed to a magneto-optical information recording and erasing apparatus, which controls a light beam irradiation period so that a light beam is irradiated to a region larger than a region where information is recorded on a magneto-optical recording medium at the time of erasing. Therefore, even if there is an error in the timing of turning on / off the beam or uneven beam scanning speed,
The effect that the recorded information can be surely erased is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a magneto-optical information recording and erasing device according to the present invention, FIG. 2 is a block diagram showing a configuration example of a write gate control circuit in the device shown in FIG. 1, and FIG. ) To (F) are timing charts each showing an output signal of each part of the circuit shown in FIG. 2, FIG. 4 is a schematic diagram showing a light beam irradiation period based on the present invention, and FIG. 5 is an apparatus shown in FIG. 6 (A) to 6 (C) illustrate a process of recording information on the magneto-optical recording medium and erasing the recorded information, respectively. FIGS. 7 (A) to 6 (C) are schematic plan views each showing a process of erasing information recorded on the magneto-optical recording medium. 38 Write gate control circuit 41 Drive interface 44 Laser drive circuit 46 Magneto-optical disk 47 Spindle motor 48 Semiconductor laser 49 Photodetector 51 External magnetic field applying means 61 … Disk drive

Claims (1)

(57) [Claims] 1. A medium for scanning a magneto-optical recording medium with a light beam, a means for applying a magnetic field to the medium, and a gate means for controlling a period of irradiation of the medium with the light beam. Information is recorded by irradiating a light beam while applying a magnetic field in a direction, and the recorded information is erased by irradiating the same light beam as during recording while applying a magnetic field in a direction opposite to a predetermined direction to the medium. In the magneto-optical information recording and erasing apparatus, the gate means starts irradiating the medium with a light beam at the time of erasing earlier than during recording, and irradiates the medium with the light beam at the time of erasing later than at the time of recording. The irradiation period of the light beam on the medium is switched between recording and erasing so that the information is erased from the length of the area where the information is recorded on the medium in the scanning direction of the light beam. Magneto-optical information recording and erasing apparatus is characterized in that a longer length in the front-rear.