JP3365020B2 - Magnetic field modulation head of magneto-optical disk - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus which records and reproduces information by utilizing a magneto-optical effect, and more particularly, it is modulated at the time of recording information on a magneto-optical disk (hereinafter, also simply referred to as a disk). about the magnetic field modulation head <br/> for applying a magnetic field.

[0002]

2. Description of the Related Art A magneto-optical disk such as a mini disk (MD) has a magnetic thin film formed on its substrate, and information is recorded by changing the magnetization direction of this magnetic thin film. As one of the recording methods, there is a method of recording by modulating a bias magnetic field. In this method, a laser beam is emitted as a direct current to irradiate the recording medium, and the temperature is raised to near the Curie point, whereupon the laser beam irradiated part where the coercive force has decreased is digitally modulated according to the information signal. The magnetic field is applied to form a magnetization pattern according to information.

The information thus recorded is reproduced (read) from the returning light by irradiating the recording medium with a laser beam which is emitted at a direct current and has a lower output than that at the time of recording using the magneto-optical effect. be able to. By the way, in such an information recording method, since the recording medium is heated by irradiating the laser beam, if the output of the laser beam deviates from the optimum value, the recording state may not be good. As a countermeasure, it has been proposed to dispose a temperature sensor inside or near the magnetic field modulation head and optimally control the power of the laser beam based on the output of this sensor.

11 (a), 11 (b) and 11 (c) are disclosed in Japanese Patent Laid-Open No. 3-1527.
This figure shows a magnetic field modulation head of this type disclosed in Japanese Patent Laid-Open No. 48. In the case shown in (a), the temperature sensor 14 is provided on the side of the magnetic field generator facing the magneto-optical disk 1, that is, on the lower surface of the yoke 12 supporting the pair of electromagnets 11 via the heat insulating material 13. In the case shown in (b), the temperature sensor 14 is installed in the gap of the yoke 12 supporting the electromagnet 11 via the heat insulating material 13, and further shown in (c). In this case, a coil 16 is wound around a core 15 to form an overwrite magnetic head, and a lead wire of a temperature sensor 14 is bonded to the side surface of the magnetic head.

[0005]

In the magnetic field modulation head described above, the temperature of the magneto-optical disk reaches the Curie point stably by controlling the power of the laser beam based on the output of the temperature sensor attached to the magnetic field modulation head. It was made to let. However, in all of these magnetic field modulation heads, the temperature sensor is arranged at a position separated from the disk surface by a space, and moreover, the disk itself is housed in a cartridge or the temperature must be detected during its rotation. Therefore, the ambient temperature is detected rather than the temperature of the disk.

In an automobile or portable optical information recording / reproducing apparatus, when a disc is inserted and recording (hereinafter also referred to as writing) immediately after the disc is inserted, the disc itself may be warm but the disc may be cold. In this case, if the power of the laser beam is controlled based on the detection value of the temperature sensor of the magnetic field modulation head described above, the temperature of the disk may not reach the Curie point and writing may not be successful. Further, in the magneto-optical recording / reproducing apparatus for data, when writing was performed under the same condition as this, although the data could be written, the writing level was low and the error rate sometimes increased.

The present invention has been made in order to solve the above-mentioned problems, and accurately detects the temperature of a disk, and even when the temperature of the apparatus or the apparatus is different from the temperature of the disk inserted therein, the magnetic field modulation heads of the magneto-optical disk that can be made to reach the temperature of the disk to the Curie point with high accuracy for the purpose.

[0008]

A magnetic field modulation head for a magneto-optical disk according to the present invention comprises a sliding portion which slightly protrudes in the direction of the magneto-optical disk from a magnetic field generating portion and is brought into contact with the disk surface of the magneto-optical disk. Inside,
A device equipped with a temperature sensor to control the temperature of the magneto-optical disk at a slightly distant position , or a magnetic field generated integrally with the sliding part that is brought into contact with the disk surface of the magneto-optical disk The temperature detection coil for detecting the temperature of the magneto-optical disk is wound around the core on which the magnetic field generation coil of the other part is wound .

[0009]

In the magnetic field modulation head of the present invention, the temperature of the sliding portion itself or the sliding portion is integrally formed by utilizing the fact that the sliding portion is brought into contact with the disk surface of the magneto-optical disk. The temperature of the magnetic field generator is detected , and the temperature is detected at a position slightly away from the contact surface.
Since it has been designed so that it will not be affected by the friction heat of the contact part.
In addition, even if the temperature of the device or the device is different from the temperature of the disc inserted therein, the temperature of this disc can be accurately detected, and by utilizing this for controlling the power of the laser beam, the disc The temperature can be exactly reached to the Curie point.

[0010]

[0011]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a sectional view showing the configuration of the first embodiment of the magnetic field modulation head of the present invention. In FIG. 1, the head arm 21 has its base end portion, that is, the left end portion in the drawing (not shown) connected to the head drive portion of the optical information recording / reproducing apparatus. A suspension 22 is supported between an intermediate portion and a tip portion of the head arm 21 so that the tip portion can move up and down. On the lower surface of the front end portion of the suspension 21, an integrated one of the sliding portion 23 and the frame 24A of the magnetic field generating portion 24 is joined. The sliding part 23 is the magnetic field generating part 24.
These bottom surfaces are in two steps so as to slightly project in the direction of the disk 1 (downward in the figure). Therefore, when the sliding portion 23 is brought into contact with the disk surface of the magneto-optical disk 1, the magnetic field generating portion 24 is opposed to the disk 1 with a constant gap, and thereby the magnetic field is applied to the disk surface. The intensity of the modulating magnetic field can be constant.
Further, an "E" -shaped core 25 is mounted on the magnetic field generation unit 24, and a coil 26 is wound around a central leg of the core 25 via a bobbin (not shown). A temperature sensor 27, which is preferably a thermistor or a diode, is mounted inside the sliding portion 23 preferably at a position 0.5 mm from the contact surface. FPC (Flexible Print Cir
A wiring 28 made of cuit) is placed, and by connecting a lead wire at its tip to the coil 26 and the temperature sensor 27, it is possible to supply an exciting current and detect the temperature.

In the magnetic field modulation head having such a structure, since the temperature sensor 27 is mounted near the contact surface with the disk 1, the sliding portion 23 of this temperature sensor 27 is brought into contact with the magneto-optical disk and When the rotation of the magnetic disk is stopped, it is possible to detect a temperature that is almost the same as that of the disk 1.
If the temperature sensor 27 is brought too close to the contact surface, the temperature sensor 27 may be damaged due to wear of the sliding portion 23. Therefore, the position 0.5 mm from the contact surface is preferable as shown in the figure. .

FIG. 2 is a sectional view showing the construction of the second embodiment of the magnetic field modulation head of the present invention. In the figure, the same elements as those of FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In the second embodiment, a temperature detecting coil 29 is wound around the center leg of the core 25 as a temperature sensor. That is, a resin bobbin (not shown) having two winding portions in the axial direction is used for the central leg of the core 25, and the magnetic field generating coil 26 is provided on the side closer to the disk 1 and the temperature is provided at the back thereof. Detection coils 29 are mounted respectively. In this case, the magnetic field generating coil 26
The number of turns is 33 and the resistance value is 5 ohms. The number of turns of the temperature detecting coil 29 is 33 and the resistance value is 50 ohms (25 ° C.).

The magnetic field modulation head shown in FIG.
Since there is a temperature sensor 27 in the vicinity of the contact surface with, the sliding portion 23 is brought into contact with the magneto-optical disk, and when the magneto-optical disk 1 is in a stopped state, it is possible to detect a temperature having almost no difference from that of the disk 1. However, when the disc 1 rotates, the detection accuracy is inevitably lowered due to the influence of frictional heat.
In this respect, the magnetic field modulation head shown in FIG. 2 is slightly inferior in detection accuracy when the magneto-optical disk 1 is in a stopped state.
There is an advantage that it is less likely to be affected by frictional heat due to the rotation of. Further, since another coil 29 for temperature detection only needs to be wound around the same core as the magnetic field generating coil 26, it can be manufactured more easily and cheaper than mounting a thermistor or a diode. There are also advantages.

Next, FIG. 3 is a block diagram showing the overall construction of an optical information recording / reproducing apparatus for carrying out the temperature control method for a magneto-optical disk according to the present invention. In FIG. 3, the magneto-optical disk 1 has a plurality of spiral tracks, and information is recorded in or written on these tracks at CLV (constant linear velocity). The spindle motor 2 drives the magneto-optical disk 1 to rotate. The pickup device 3 mainly has a function of converging a laser beam so that its focal point coincides with the disk surface of the magneto-optical disk 1, and detecting the reflected light with a sensor to reproduce the obtained signal and track the reproduced signal. It has a function for position control with respect to, and a function for superimposing a high frequency signal upon reading. The magnetic field modulation head 4 is shown in FIG.
When writing information, a loading means for bringing the sliding portion into contact with the disk surface at a predetermined pressure is attached, and the position control is performed so as to follow the track integrally with the pickup device 3. It is supposed to be done.

On the other hand, the spindle motor control circuit 31 controls the rotational speed of the spindle motor 2 so as to maintain CLV by the output signal of the signal processing circuit 38 described later, and the pickup drive circuit 32 controls the pickup device 3 and the magnetic field. The modulation head 4 is driven integrally and the positioning control for the track is performed. Further, the voltage detection circuit 33 amplifies and outputs the voltage generated in the temperature sensor or the temperature detection coil mounted on the magnetic field modulation head 4, as will be described later in detail.

Further, the preamplifier 34 is the pickup device 3
The signal corresponding to the laser return light detected by the sensor inside is input, amplified, and then applied to the signal processing circuit 38, while controlling the laser output in the pickup device 3 in response to the output command from the controller 35. To do. In response to a command from the key 36, the controller 35 performs the following control using a series of digital signal processing systems such as the signal processing circuit 38, the memory controller 39 for the memory 40, and the conversion circuit 41. When an RF signal is input to the signal processing circuit 38 via the preamplifier 34 during reproduction, the RF signal is converted into an audio signal and output. During reproduction and writing, the speed of the spindle motor 2 is detected and a speed signal that becomes CLV is applied to the spindle motor control circuit 31. At the time of reproduction and writing, a tracking error and a focus error necessary for accurate tracing of the laser beam are detected, and signals for correcting these errors are applied to the pickup drive circuit 32. When writing, quantize the audio signal and write circuit
The signal is applied to the magnetic field modulation head 4 via 37, and the control signal of the power of the laser beam is passed via the preamplifier 34.
Add to pickup device 3. At the start of writing, the voltage is applied before the sliding portion of the magnetic field modulation head 4 is brought into contact with the magneto-optical disk 1 and when a predetermined time has elapsed after the sliding portion was brought into contact with the magneto-optical disk. The temperature is detected based on the output signal of the detection circuit 33, the temperature change of the recording layer corresponding to the elapsed time is predicted based on the detected temperature obtained, and at least in the initial stage of starting recording, the deviation from the predetermined recording temperature is calculated. A signal that controls the power of the laser beam so as to approach zero is supplied to the preamplifier.
Add to pickup device 3 via 34.

Next, the temperature control method of the magneto-optical disk of the present invention will be described. When the magnetic field modulation head 4 shown in FIG. 1 is used and the thermistor is used as the temperature sensor, the circuit shown in FIG. 4 is provided for temperature measurement. That is, the test signal TE of the controller 35
Switch SW1 whose contacts are closed by ST and resistor R
1, a diode D and a resistor R2 are connected in series between the high potential power source Vcc and the ground point as the low potential power source.
On the other hand, one end of the resistor R3 is connected to the anode of the diode D, the other end is connected to the inverting input terminal (-) of the operational amplifier OP, and one end of the resistor R4 is connected to the cathode of the diode D. Operational amplifier O at the end
It is connected to the non-inverting input terminal (+) of P. A feedback resistor R5 is connected between the inverting input terminal and the output terminal of the operational amplifier OP, and a resistor R6 is connected between the non-inverting input terminal of the operational amplifier OP and the ground point.

When the test signal TEST is applied, the switch SW1 is closed, and a voltage corresponding to the temperature at that time is generated across the thermistor TH. This voltage is amplified by an amplifier circuit including an operational amplifier OP, then converted into digital data by an A / D converter 35A of the controller 35, and used for controlling the power of the laser beam. When a diode is used as the temperature sensor, the circuit configuration is such that the diode D is connected instead of the thermistor TH, as shown in FIG. The other configuration of FIG. 5 is the same as that of FIG.

FIG. 6 is an operation explanatory diagram when the controller 35 controls the power of the laser beam based on the output of the operational amplifier OP shown in FIG. When the optical information recording / reproducing apparatus placed in an environment where the ambient temperature is 0 ° C. is turned on, the internal temperature of the apparatus rises to 25 ° C. as shown by the curve A. Therefore, it is assumed that a magneto-optical disk having its own temperature of 0 ° C. is inserted at time t1 which is 10 minutes or more, for example, 16 minutes after the power is turned on. The temperature of this magneto-optical disk rises rapidly from 0 ° C. to 25 ° C. as shown by the curve B. Writing on the magneto-optical disk is performed by loading a magnetic field modulation head on the magneto-optical disk. In this embodiment, the ambient temperature of 25 ° C. before loading is detected based on the output of the operational amplifier OP. Next, the magnetic field modulation head is loaded on the magneto-optical disk, and the temperature of the magneto-optical disk is detected based on the output of the operational amplifier OP when a predetermined time, for example, 200 msec has elapsed. The temperature detection up to this point is performed while the rotation of the spindle motor 2 is stopped. From these two detected values, the temperature change of the magneto-optical disk corresponding to the time change can be predicted. That is, the temperature change determined by the heat capacity of the entire device and the heat capacity of the disk is stored in the ROM in advance, and the temperature change corresponding to the subsequent time can be known from the temperature detection value when the magnetic field modulation head is loaded on the magneto-optical disk. Therefore, when writing is started at time t2, all temperatures of the magneto-optical disk after this time t2 can be predicted. Therefore, the power of the laser beam is controlled so as to approach the preset temperature value with respect to this predicted value.

Incidentally, in the circuit configuration shown in FIG. 4, it is assumed that the thermistor TH as a temperature sensor has a resistance value of 1.1 kΩ at 0 ° C. and a resistance value of 1 kΩ at 25 ° C. Switch SW1 with resistance of 1kΩ
Is closed and the high potential power supply Vcc is connected thereto, the resistance values of the resistors R1 and R2 are determined so that a voltage of exactly 1 V is generated. Therefore, at 0 ° C., a voltage of 1.1 V is applied to the operational amplifier OP, and at 25 ° C., a voltage of 1.0 V is applied to the operational amplifier OP. If the resistance values of the resistors R3 and R5 are determined so that the amplification factor becomes 1,
These voltages are directly applied to the A / D converter 35A. If an A / D converter 35A having a power supply voltage of 3V and an 8-bit output is used, the digital data becomes "256" at the voltage of 3V, and therefore the digital data "85" at the voltage of 1V. Is obtained, and digital data “94” is obtained for a voltage of 1.1V. When the magnetic field modulation head is not loaded on the magneto-optical disk, A
If the digital data "85" is output from the A / D converter, and the digital data "94" is output from the A / D converter when the magnetic field modulation head is loaded on the magneto-optical disk, this difference results in a disc difference. It represents the ambient temperature difference. Further, by comparing these digital data with the table written in the ROM described above, the temperature of the magneto-optical disk thereafter can be predicted. The processing procedure at the time of writing including these processings can be shown as the processing of steps 101 to 116 in FIG.

Next, FIG. 8 shows an example of the configuration of the voltage detecting circuit 33 and the writing circuit 37 corresponding to the magnetic field modulation head shown in FIG. 2, and the magnetic field generating coil 26 arranged in parallel in the magnetic field generating section 24.
And the temperature detecting coil 29 are connected in series. on the other hand,
A P channel MOSF is connected between the high potential power supply Vcc and the ground point.
A series connection circuit of ETQ1 and N-channel MOSFET Q3 (hereinafter, P-channel MOSFET is simply referred to as PMOSFET and N-channel MOSFET is simply referred to as NMOSFET), PMOSFET Q2 and NMOSFET
It is connected to the series connection circuit of Q4. PMOS FE
One end of a magnetic field generating coil 26 is connected to a connection point of TQ1 and NMOSFET Q3, that is, a connection point between drains, and a coil 26 for magnetic field generation is connected to a connection point between PMOSFET Q2 and NMOSFET Q4, that is, a connection point between drains. The end is connected to one end of the temperature detecting coil 29. The other end of the temperature detecting coil 29 has an NM
The drain of OSFET Q5 is connected to this NMOSF
The source of ETQ5 is connected to ground. The switch SW1 is a write data W. DATA and ground voltage are switched by the test signal TEST and input. The output end of the switch SW1 is connected to the PMOSFET Q1 and NMOSFET via the inverter IN.
It is connected to the respective gates of Q3, and is also connected to the normally closed input end of the changeover switch SW2 and the gate of the NMOSFET Q4 via the buffer BU. The normally open side input end of the changeover switch SW2 is connected to the ground point, and the output end thereof is connected to the gate of the PMOSFET Q2. Another switch SW
The input end on the normally closed side of 3 is grounded, the high potential power supply Vcc is connected to the input end on the normally open side, and its output end is NMOSFET.
It is connected to the gate of Q5. In addition, the voltage generated across the temperature detecting coil 29 is applied to the operational amplifier O described above.
It is amplified by an amplifier composed of P and resistors R3, R4, R5 and added to the A / D converter 35A.

In the circuit shown in FIG. 8, the operational amplifier O
If P and the resistors R3, R4 and R5 are the constituent elements of the voltage detection circuit 33 of FIG. 3, those elements and the magnetic field generator 24 are the constituent elements of the write circuit 37 of FIG. ing. In addition, these circuits apply a test voltage to the temperature detection coil 29 during temperature detection before starting writing,
During writing, a current for switching between the positive direction and the negative direction is passed through the magnetic field generating coil 26. Here, at the time of temperature detection, the changeover switches SW2, SW3, and SW4 are all switched to the side opposite to the illustrated direction by the test signal TEST. As a result, PMOSFET Q2
, NMOSFET Q3 and Q5 are turned on, and the PMOSF
The ETQ1 and NMOSFET Q4 are turned off, and a current flows through both the magnetic field generating coil 26 and the temperature detecting coil 29. At this time, the voltage generated at both ends of the temperature detecting coil 29 is amplified by an amplifier circuit centered on the operational amplifier OP.

When a write command is applied, a test voltage is applied to the temperature detecting coil 29 while the spindle motor 2 is stopped to detect the ambient temperature. Then, the magnetic field modulation head 4 is loaded onto the magneto-optical disk 1 while the spindle motor 2 is stopped, and the sliding portion is brought into contact with the disk surface. Then, until the resistance value changes due to the difference between the ambient temperature and the temperature of the magneto-optical disk 1, for example, 20
Wait until 0 msec has passed. It is not necessary to wait until the temperature of the magnetic field modulation head completely matches the temperature of the magneto-optical disk. After that, a test voltage is applied to the temperature detecting coil 29 again to detect the temperature of the magnetic field modulation head at that time. The current temperature of the magneto-optical disk 1 is detected from the difference between these temperatures, and the power of the laser beam is controlled by this.

As the temperature detecting coil 29, one having a disk temperature of 45Ω at 0 ° C. and 50Ω at 25 ° C. is used. Then, by applying a current of 40 mA, a voltage of 1.8 V is generated across the temperature detecting coil 29 at 0 ° C. When this voltage is amplified by 1/2 with the operational amplifier OP, 0.9 V is obtained. And the power supply voltage is 3
By inputting V to the 8-bit A / D converter 35A, digital data "75" is obtained. On the other hand, during writing, all the changeover switches SW1, SW2, SW3 are held in the illustrated state. Then, the write data W. When an "H" level signal is applied as DATA, PMOSFET Q1 and NMOSFET Q4 are turned on, PMOSFET Q2 and NMOSFET Q3 are turned off, and a current in the positive direction (from right to left in the drawing) is applied to the magnetic field generating coil 26. And write data W.S. When an "L" level signal is applied as DATA, PMOSFET Q1 and NMOSFET Q4 are turned off, PMOSFET Q2 and NMOSFET Q3 are turned on, and a current in the negative direction (from left to right in the drawing) is applied to the coil 26 for magnetic field generation. Shed.

In this embodiment, the magnetic field generating coil 26 and the temperature detecting coil 29 are connected to each other to form a so-called center tap type coil. However, these coils are separated from each other to form the temperature detecting coil 29. May add a dedicated measuring circuit. By the way, the above-mentioned embodiments are intended for the magnetic field modulation head provided with a temperature sensor or a coil for temperature detection in addition to the coil 26 for generating a magnetic field, but it is premised that the sliding portion is brought into contact with the disk surface. Then, the temperature of the disk can be detected by using the magnetic field generating coil 26 itself as a temperature sensor.

FIG. 9 shows a configuration example in which the magnetic field generating coil 26 is also used as a temperature sensor. Here, the drain of the NMOSFET Q3 is connected to the drain of the PMOSFET Q1 whose source is connected to the high potential power supply Vcc,
The source of the NMOSFET Q3 is connected to the input end of the switch SW5. In addition, an NMOS is connected to the drain of PMOSFET Q2 whose source is connected to the high potential power supply Vcc.
The drain of FET Q4 is connected to this NMOSFET
The source of Q4 is connected to the input end of switch SW5. The normally closed output terminal of the switch SW5 is grounded, and the normally open output terminal is connected to the low potential power supply Vss via the constant current source J. PMOSFET Q1 and NMOSFET Q
3 connection point, PMOSFET Q2 and NMOSFET
A series connection circuit of a resistor R1, a coil 26 for generating a magnetic field, and a resistor R2 is connected to the connection point of Q4.
The switch SW3 has a write data W.V.
When DATA is added and the normally open side input terminal is grounded, the output terminal of the changeover switch SW3 is connected to each gate of the PMOSFET Q1 and the NMOSFET Q3 via the inverter IN, and also via the buffer BU.
It is connected to the gates of PMOSFET Q2 and NMOSFET Q4. Further, the voltage generated across the coil 26 for magnetic field generation is applied to the operational amplifier OP and the resistor R3 described above.
, R4, R5, R6 are amplified and added to the A / D converter.

Here, at the time of temperature detection, all the changeover switches SW3 and SW5 are changed over to the side opposite to the illustrated direction by the test signal TEST. As a result, the PMOSFET Q2 and NMOSFET Q3 are turned on, the PMOSFET Q1 and NMOSFET Q4 are turned off, and a current flows through the coil 26 for magnetic field generation, and the constant current source J controls the current to be constant. At this time, the voltage generated at both ends of the magnetic field generating coil 26 is amplified by an amplifier circuit centered on the operational amplifier OP. Therefore, when a write command is applied, the spindle motor 2
With the magnetic field modulation head kept unloading, a test current is passed through the temperature detecting coil 29 to detect the ambient temperature. In this case, the coil 26 for magnetic field generation
Is 5.0Ω at 25 ℃ and 4.5 at 0 ℃
Use the one that becomes Ω. Therefore, a voltage of 1.0 V is generated by passing a current of 200 mA through the temperature detecting coil 29 of 5.0Ω at 25 ° C. If this voltage is amplified by the operational amplifier OP by a factor of 1.0, 1.0 V is obtained. Also, the digital data "85" is obtained by inputting it to the 8-bit A / D converter with the power supply voltage of 3V. Here, the test current is cut off and the ROM
Alternatively, the temperature at that time, that is, the ambient temperature is obtained using a table showing the relationship between the digital data written in the EEPROM and the temperature.

Then, the magnetic field modulation head 4 is loaded onto the magneto-optical disk 1 while the spindle motor 2 is stopped, and the sliding portion is brought into contact with the disk surface. Then, it waits until the resistance value changes due to the difference between the ambient temperature and the temperature of the magneto-optical disk 1, for example, until 200 msec elapses. It is not necessary to wait until the temperature of the magnetic field modulation head completely matches the temperature of the magneto-optical disk. After that, a test voltage is applied to the temperature detecting coil 29 again to detect the temperature of the magnetic modulation head at that time. At that time, if the temperature is 0 ° C., 0.9 V is generated at both ends of the coil 26 for magnetic field generation. If this voltage is amplified by 1 times by the operational amplifier OP, it becomes 0.
9V is obtained. By inputting this voltage to the A / D converter, digital data "76" is obtained. At this time, the test current is cut off, and the ROM or EEPR is preliminarily calculated from the difference "9" from the digital data "85".
The temperature at that time is obtained using a table indicating the relationship between the digital data written in the OM and the temperature.

As described above, the difference between the temperature before the magnetic field modulation head 4 is loaded on the magneto-optical disk 1 and the temperature at the time when a certain time has elapsed after the loading is the temperature difference between the ambient temperature and the disk. Since the temperature of the disk tends to approach the ambient temperature with the passage of time, a table of temperature asymptotes preset in the ROM based on the heat capacity of the entire apparatus and the heat capacity of the disk and the magnetic field on the magneto-optical disk 1 are set. The temperature of the recording disk at the time when the write instruction is issued is predicted by the value of the timer that measures the time after loading the modulation head 4. Then, the laser beam output is controlled according to the relationship between the predicted temperature and the voltage written in the ROM. Of course, since the magnetic field modulation head 4 is loaded on the magneto-optical disk 1 immediately before writing, the temperature may be measured at this point.

After that, the spindle motor 2 is started to detect a focus error and a tracking error with respect to the track of the laser beam, and the pickup device 3 is controlled so as to bring these errors close to zero.
By rotating at V, the pickup unit near the innermost circumference of the disc TOC (Table Of Contents) or UT
Move to OC (User Table Of Contents), read out necessary information, and write there. The timer that measures the time after loading the magnetic field modulation head 4 on the magneto-optical disk 1 is cleared when it is determined that the temperature of the magneto-optical disk 1 substantially matches the ambient temperature.

During writing, the changeover switches SW3, SW
All of 5 are held in the illustrated state. Write data W. When an "H" level signal is applied as DATA, PMOSFET Q1 and NMOSFET Q4 are turned on, PMOSFET Q2 and NMOSFET Q3 are turned off, and a current in the forward direction (from right to left in the drawing) is applied to the coil 26 for magnetic field generation. And write data W.S. When an "L" level signal is applied as DATA, PMOSFET Q1 and NMOSFET Q4 are turned off, PMOSFET Q2 and NMOSFET Q3 are turned on, and a current in the negative direction (from left to right in the drawing) is applied to the coil 26 for magnetic field generation. Shed.

FIG. 10 shows another configuration example in which the coil 26 for generating a magnetic field is also used as a temperature sensor. Here, the PMOS FE whose source is connected to the high potential power supply Vcc
The drain of TQ1 is connected to the drain of NMOSFET Q3, and the source of this NMOSFET Q3 is grounded. Also, PM whose source is connected to the high potential power supply Vcc
The drain of the NMOSFET Q4 is connected to the drain of the OSFET Q2, and the source of the NMOSFET Q4 is grounded. PMOSFET Q1 and NMOSFET
Connection point of Q3, PMOSFET Q2 and NMOSFE
Between the connection point of TQ4, a series connection circuit of a resistor R1, a coil 26 for generating a magnetic field and a resistor R2 is connected. The switch SW3 has a write data W.V. DATA is added, the normally open side input terminal is grounded, and the output end of this changeover switch SW3 is connected to the PMOSFET Q1 and NMOSFET via the inverter IN.
It is connected to the gates of Q3 and also to the gates of PMOSFET Q2 and NMOSFET Q4 via a buffer BU. Further, the voltage generated across the coil 26 for generating a magnetic field is amplified by the amplifier composed of the operational amplifier OP and the resistors R3, R4, R5 and R6 described above, and
It is designed to be added to the / D converter.

Here, at the time of temperature detection, the changeover switch SW3 is changed over to the side opposite to the illustrated direction by the test signal TEST. This allows the PMOS FE
TQ2 and NMOSFET Q3 are turned on and PMOSF
ETQ1 and NMOSFET Q4 are turned off, and a test voltage is applied to the magnetic field generating coil 26. At this time, the voltage generated at both ends of the magnetic field generating coil 26 is amplified by an amplifier circuit centered on the operational amplifier OP.

When a write command is applied, the magnetic field modulation head 4 is loaded onto the magneto-optical disk 1 while the spindle motor 2 is stopped, and the sliding portion is brought into contact with the disk surface. Then, until the resistance value changes due to the difference between the ambient temperature and the temperature of the magneto-optical disk 1, for example, 200 ms
Wait until ec has passed. It is not necessary to wait until the temperature of the magnetic field modulation head completely matches the temperature of the magneto-optical disk. After that, a test voltage is applied to the temperature detecting coil 29 again to detect the temperature of the magnetic modulation head at that time. At that time, if it was 4.5Ω at 0 ° C., 400
By passing a current of mA, a voltage of 1.8 V is generated across the magnetic field generating coil 26. When this voltage is amplified by 1/2 with the operational amplifier OP, 0.9 V is obtained. By inputting this voltage to the A / D converter, digital data "76" is obtained. At this time, the test current is cut off, and the temperature at that time is obtained by using the table showing the relationship between the digital data and the absolute value of the temperature which is written in the ROM or the EEPROM in advance. Next, the power of the laser beam is set corresponding to this temperature, and predetermined writing is performed.

When the circuit configuration shown in FIG. 10 is adopted,
Changeover switch SW3 is added and this is used as test signal T
Although it is only necessary to switch by EST, a large current (400 mA) actually supplied at the time of writing flows, so it is necessary to perform measurement in a short time so that the coil does not generate heat. Incidentally, among the above-mentioned embodiments, the one using the temperature detecting coil 29 or the magnetic field generating coil 26 detects the temperature of the magneto-optical disk by utilizing the change of the resistance value, but the temperature of the magnetic field generating portion is When it changes, the magnetic permeability of the ferrite forming the core also changes, and the inductance also changes. Therefore, the temperature of the magneto-optical disk can be detected by utilizing the change in the resistance value and the impedance including the inductance.

[0037]

As is clear from the above description, according to the magnetic field modulation head of the magneto-optical disk of the present invention, the temperature of the disk is utilized by utilizing the fact that the sliding portion is brought into contact with the disk surface of the magneto-optical disk. Can be accurately detected, so that the temperature of the disk can accurately reach the Curie point.

[0038]

[Brief description of drawings]

1 is a cross-sectional view showing a configuration of a first embodiment of a magnetic field modulation head of a magneto-optical to Disk according to the present invention.

2 is a sectional view showing a configuration of a second embodiment of a magnetic field modulation head of a magneto-optical to Disk according to the present invention.

FIG. 3 is a magnetic field modulation head for a magneto-optical disk according to the present invention.
It is a block diagram showing a configuration example of an information recording and reproducing apparatus for carrying out the temperature control method of the magneto-optical disk using.

4 is a circuit diagram showing a detailed configuration of main elements of the information recording / reproducing apparatus shown in FIG.

5 is a circuit diagram showing a detailed configuration of main elements of the information recording / reproducing apparatus shown in FIG.

FIG. 6 is a magnetic field modulation head for a magneto-optical disk according to the present invention.
FIG. 6 is a diagram showing a relationship between time and temperature in order to explain a method for controlling the temperature of a magneto-optical disk using the .

FIG. 7 is a magnetic field modulation head for a magneto-optical disk according to the present invention.
4 is a flowchart showing a processing procedure of the information recording / reproducing apparatus shown in FIG. 3 in order to explain a temperature control method of a magneto-optical disk using the .

FIG. 8 is a magnetic field modulation head for a magneto-optical disk according to the present invention.
FIG. 9 is a circuit diagram showing another configuration example of an apparatus for carrying out the method of controlling the temperature of the magneto-optical disk using the above.

FIG. 9 is a magnetic field modulation head for a magneto-optical disk according to the present invention.
FIG. 9 is a circuit diagram showing another example of the configuration of an apparatus for implementing the temperature control method for a magneto-optical disk using the above.

FIG. 10 is a circuit diagram showing still another configuration example of an apparatus for implementing the temperature control method for a magneto-optical disk according to the present invention.

11 is a cross-sectional view and a side view showing a configuration example of a magnetic field modulation head of a conventional magneto-optical to Disk.

[Explanation of symbols]

1 magneto-optical disk 3 pickup device 4 magnetic field modulation head 23 sliding portion 24 magnetic field generator 24A magnetic field generator of the frame 25 core 26 magnetic field generating coil 27 Temperature sensor 29 Temperature sensing coil 31 a spindle motor control circuit 32 the pickup driving circuit 33 voltage detection circuit 35 controller 37 writing circuit

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-1-191330 (JP, A) JP-A-2-68748 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 11/105

Claims (3)

(57) [Claims] 1. A magneto-optical disk, which is integrally coupled to the magnetic-field generating section for applying a magnetic field to the magneto-optical disk, and slightly protrudes in the direction of the magneto-optical disk from the magnetic field generating section. Of the sliding part to be brought into contact with the disk surface of the disk, and in order to detect the temperature of the magneto-optical disk, the sliding part is slightly separated from the contact surface inside the sliding part.
A magnetic field modulation head for a magneto-optical disk having a temperature sensor provided at a different position . 2. A magnetic field generating section having a magnetic field generating coil for applying a magnetic field to the magneto-optical disk, and a slide which is brought into contact with the disk surface of the magneto-optical disk and formed integrally with the magnetic field generating section. A magnetic field modulation head for a magneto-optical disk, comprising: a magnetic field generating coil; and a temperature detecting coil for detecting the temperature of the magneto-optical disk, the magnetic field modulating coil being wound around a core around which the magnetic field generating coil is wound. 3. A coil for applying a magnetic field to a magneto-optical disk.
Magnetic field generating section having magnetic field generating coil wound around
And contact the disc surface of the magneto-optical disc.
And a sliding part formed integrally with the magnetic field generating part,
The magnetic field generating coil and one end thereof are commonly wound.
A temperature detecting coil for detecting the temperature of the magneto-optical disk
And a magnetic field modulation head for a magneto-optical disk having a magnetic field.