JPH03238602A - Electromagnet driving circuit for generating magnetic field impressed on magneto-optical disk driving device and driving method for the same - Google Patents

Abstract

PURPOSE:To realize the correct recording operation and the correct erasing operation of information by controlling the size of a magnetic field generated from a magnetic field impressing electromagnet. CONSTITUTION:An oscillator 1, a triangular wave generation circuit 2, a D/A (digital/analog) converter 3, a comparator 4, an adder 5, inverters 6, 7, AND gate circuits 8, 9, an electromagnet 10, switching transistors Q1 to Q4, and a current detecting resistor R5 are provided. Then at the time of the recording of the information, by giving S1 of one side by 'H' and S2 of the other side by 'L' between two pieces of exciting current control signals S1, S2, the recording operation, for instance, is executed. At the time of erasing, by giving the exciting current control signal S1 by 'L' and S2 by 'H', the erasing operation is executed. At the time of reproducing, since both exciting current control signals S1, S2 are given by 'L', an exciting current is not generated. Thus, the recording and the erasure can be executed always in an optimum state.

Description

[Detailed Description of the Invention] Kei Sanko Ritsunami and Ritsuka This invention is a method for generating an applied magnetic field suitable for use in a magneto-optical disk drive device that records, reproduces, and erases information on an optical disk using a light beam and a magnetic field. The field relates to a drive circuit for an electromagnet for application and a method for driving the same, particularly for a magneto-optical disk drive device that enables reliable recording and erasing operations by controlling the magnitude of the magnetic field generated from an electromagnet for applying an applied magnetic field. The present invention relates to an electromagnet drive circuit for generating magnetic fields and a method for driving the same.

Conventionally, magneto-optical disk drive devices record, reproduce, and erase information on optical disks using light beams and magnetic fields. In other words, a light beam from a light source is irradiated onto an optical disk to reproduce recorded information. Also.

At the time of recording and writing, a magnetic field in a fixed direction is applied to cause the light source to emit light with a larger amount of light than during reproduction, and at the time of recording and erasing, the magnetic field at the time of writing is reversed, and.

Magneto-optical disk drive devices that cause a light source to emit light with the same amount of light as during writing are known.

In this type of magneto-optical disk drive device, especially when recording information on an optical disk, a magnetic field is applied in a certain direction to cause the light source to emit light with a larger amount of light than during playback, and the recorded information is During erasing, it is necessary to reverse the magnetic field during writing and cause the light source to emit light with the same amount of light as during writing, and for this purpose, an electromagnet for applying a magnetic field is provided.

Conventionally, a constant current circuit is generally employed as a drive circuit for a magnetic field applying electromagnet used in this type of magneto-optical disk drive device.

Therefore, the magnitude of the magnetic field generated by the electromagnet is also constant.

In this case, the magnitude of the magnetic field on the surface of the media (recording medium) is designed to be a value within a certain tolerance range depending on the accuracy of mechanical dimensions.

In addition, in order to reliably record information on an optical disk or erase recorded information reliably, it is necessary to not only check the magnitude of the magnetic field from the electromagnet for applying the magnetic field, but also the light beam generated from the light source. It is also necessary to control the spot diameter and laser power, and various control methods for the light beam have been proposed.

However, no matter how accurately the spot diameter of the light beam and the laser power are controlled, if the magnitude of the magnetic field generated from the electromagnet for applying the magnetic field is not accurately controlled, reliable information recording and erasing operations cannot be achieved. There was an inconvenience that it was not possible to do so.

Furthermore, it is necessary to detect the results of recording and erasing operations, but conventionally a constant current circuit has been used as the drive circuit for the electromagnet for applying a magnetic field, so no special detection means or method has been used.

This invention aims to solve these disadvantages in the drive circuit of the electromagnet for generating the applied magnetic field of the conventional magneto-optical disk drive device, namely, the method of controlling only the spot diameter and laser power of the light beam was adopted. Therefore, by solving the inconvenience of not being able to perform reliable information recording and erasing operations, and by accurately controlling the magnitude of the magnetic field generated from the magnetic field applying electromagnet, accurate information recording and erasing operations can be achieved. In addition to enabling erasing operations, the results of recording and erasing operations are detected, and if the state is insufficient, recording or erasing is performed again, reducing the margin for mechanical dimensional accuracy during manufacturing. In addition, it is an object of the present invention to provide an electromagnet drive circuit for generating an applied magnetic field of a magneto-optical disk drive device and a method for driving the same, which enable optimum recording and erasing. In a drive circuit for an electromagnet for generating an applied magnetic field of a magneto-optical disk drive device, which includes a light source that generates a light beam and an electromagnet that generates an inverted magnetic field during writing and erasing, the current is applied. A full bridge circuit consisting of a switching transistor that can be controlled in both forward and reverse directions, a reference voltage control means such as a CPU that controls a reference voltage, a voltage controlled by the reference voltage control means, and a current flowing through an electromagnet. and means for controlling on/off of the transistor based on the comparison result of the comparison means.

Second, in the above drive circuit, there is a recording/erase function that detects the recording or erasing state based on the reproduction RF signal when reproducing after the recording operation or the reproduction RF signal when reproducing after the erasing operation. A state detecting means is provided, and when the state detecting means determines that recording or erasing is not sufficient, the current flowing through the electromagnet is controlled to be increased.

Next, embodiments of the magneto-optical disk drive device of the present invention will be described in detail with reference to the drawings.

This embodiment corresponds to claim 1,
The present invention relates to a drive circuit for an electromagnet for generating an applied magnetic field in a magneto-optical disk drive device.

FIG. 1 is a functional block diagram showing one embodiment of the electromagnet drive circuit of the magneto-optical disk drive device of the present invention. In the drawing, 1 is an oscillator, 2 is a triangular wave generation circuit, and 3 is a D/A Digital/analog) converter, 4 is a comparator, 5 is an adder, 6 and 7 are inverters, 8 and 9 are AND gate circuits, 10 is an electromagnet, Q
Q4 is a switching transistor, and R5 is a current detection resistor. is the excitation current of the electromagnet 10, S
1 and 82 are excitation currents for the electromagnet 10. , where v-1 is the reference voltage, VS is the detection voltage generated by the current detection resistor R5, and α is the D/A
The control coefficient of the converter 3, A indicates the output voltage of the triangular wave generated from the triangular wave generating circuit 2, and B indicates the output voltage generated from the comparator 4.

In the electromagnet drive circuit shown in FIG. 1, when recording information, the two excitation current control signals Sl and S2 shown in the upper left are
The excitation current of the electromagnet 10 is set by applying "H" to one 81 and "L" to the other 82. For example, a recording operation is performed by generating a flow in the direction shown in the figure.

On the other hand, during erasing, the excitation current control signal S1 is “
S2 is given as "H", and the excitation current I0 is generated to flow in the opposite direction to that shown in the figure to perform the erasing operation.The direction of the excitation current 1 is different during recording and erasing. It suffices if the relationship is the opposite, and either current direction may be used during recording (the opposite direction is during erasing).

Also, during reproduction, two excitation current control signals S1, S2
are both given by "L", so the exciting current is is not generated.

First, the operation during recording will be explained.

In this case, since the control signal S1 is given at "H" and the control signal S2 is given at "L", switching transistors Q8 and Q
4 is turned on. Note that in this state, switching transistors Q2 and Q are both off.

In this state, current flows through the electromagnet 10. The direction of
in the direction of the arrow.

And this excitation electrician. Accordingly, a detection voltage v5 is generated in the current detection resistor R5.

This detection voltage vs is applied to "one terminal" of the comparator 4.

On the other hand, an adder 5 is connected to the "child terminal" of this comparator 4.
An output voltage of is given.

The output voltage of the adder 5 is the reference voltage v, el, and the CPU
The D/A converter 3 controlled by the D/A converter 3 generates a voltage (A+α·vl) that is the sum of the voltage α·V,−1 multiplied by α by the control coefficient α and the output voltage A of the triangular wave generated from the triangular wave generating circuit 2. ).

Therefore, the "one terminal" of the comparator 4 has the voltage V5 detected by the current detection resistor R5, and the "child terminal" has the output voltage (A+α·v,v) of the adder 5. are applied to generate an output voltage B.

FIG. 2 is a time chart for explaining the operation of the electromagnet drive circuit shown in FIG. Reference numbers in the drawings correspond to reference numbers in FIG.

As shown in FIG. 2, the output voltage B of the comparator 4
is a waveform that becomes 'H' when the voltage (A+α·■1) applied to the “child terminal” is larger than the voltage V applied to the “one terminal”.

By applying this output voltage B to the switching transistor Qe via the AND gate circuit 8 and controlling it on and off, the excitation current I6 of the electromagnet 10 can be controlled to a constant value.

Further, by changing the control coefficient α of the D/A converter 3 controlled by a CPU (not shown), it is also possible to set the level of the excitation current I0 of the electromagnet 10 to another constant value.

As already mentioned, the excitation current control signal Sl.

If S2 is reversed and Sl is set to "L" and S2 is set to "H", the excitation current will be in the opposite direction. is generated.

However, even in this case, the operation of the comparator 4 is the same, and the output voltage B as described in connection with FIG. 2 is generated, and the excitation current I0 is controlled to a constant value.

Exciting electrician. The full bridge circuit, which can control the current in both forward and reverse directions, has the configuration shown in Figure 1, and the excitation current is controlled to a constant value in the opposite direction when recording and erasing from the disk. is generated.

Moreover, the D/A converter 3 controlled by the CPU
By changing the control coefficient α, the excitation current I0 of the electromagnet 10
It is also possible to set the level to some other constant value.

Therefore, it is possible to reduce the margin of accuracy of mechanical dimensions in terms of the magnitude of the applied magnetic field on the media surface.

411 This embodiment corresponds to claim 2,
The present invention relates to a driving method in a driving circuit for an electromagnet for generating an applied magnetic field in a magneto-optical disk drive device.

According to this driving method, the recording or erasing state is detected based on the reproduction RF signal when reproducing after the recording operation or the reproduction RF signal when reproducing after the erasing operation, thereby ensuring reliable operation of the magneto-optical disk. It is possible to determine whether recording or erasing operations have been performed, and if it is determined that recording or erasing is insufficient,
By increasing the current flowing through the electromagnet, recording and erasing operations can be performed reliably.

FIG. 3 is a functional block diagram showing an embodiment of a reproduced RF signal monitoring circuit in a magneto-optical disk drive device in the driving method of the present invention.

In the drawing, 11 is a first photodetector, 12
13 and 14 are I/V (current/voltage) converters, 15 is a differential amplifier, 16 is an analog switch section, 17 is a peak hold circuit, 18 is a first comparator, and 19 is a second photodetector. Comparator No. 2, C represents a capacitor, V and v2 represent a reference voltage, RF represents a reproduced RF signal, and DATA GATE represents a data gate signal.

The circuit shown in FIG. 3 has a function of determining whether the state of recording or erasing information on the disk is sufficient.

The first photodetector 11 is connected to the "+ terminal" of the differential amplifier @I1.15 via the I/V converter 13 in the subsequent stage, and the second photodetector 12 is connected to the "+" terminal of the I/V converter 13 in the subsequent stage. It is connected to "one terminal" of the differential amplifier 15 via the V converter 14.

Then, the differential amplifier 15 extracts the difference and generates a reproduced RF signal RF.

Note that one reference voltage v1 is set to a voltage sufficient to perform a recording operation, and the other reference voltage v2 is set to a voltage sufficient to perform an erasing operation.

The following FIG. 4 is a time chart for explaining the operation of the reproduced RF signal monitoring circuit shown in FIG. 3. The reference numerals in the drawing correspond to the reference numerals in FIG.

The reproduced RF signal has a preformat section (ID section) indicating a sector address in one sector, and a data section in which information is written, as indicated by RF in the upper part of FIG.

In addition, the data gate signal has only the data section "H" as shown by DATA GATE at the bottom of FIG.
” is the waveform signal.

The analog switch section 16 receives this data gate signal DA.
It is turned on and off by TA GATE, and turns on at the timing of generation of the reproduction RF signal RF corresponding to the data portion.

As a result, in the circuit shown in FIG. 3, when the reproduced RF signal RF output from the differential amplifier 15 is in the ON state of the analog switch section 16 at the next stage, the signal corresponding to the data section is output from the peak hold circuit. 17.

Here, the capacitor C provided on the input side of the peak hold circuit 17 is an AC-coupled capacitor in order to eliminate the influence of offset voltage.

The output of this peak hold circuit 17 is compared with reference voltages V and V by a first comparator 18 and a second comparator 19, respectively.

As already mentioned, one reference voltage V□ is set to a voltage sufficient to perform a recording operation, and the other reference voltage v2 is set to a voltage sufficient to perform an erasing operation.

Therefore, when the data is reproduced after the recording operation, if the output of the first comparator 18 is "H", it can be determined that the recording is insufficient.

Further, when the data is reproduced after the erase operation, if the output of the second comparator 19 is "L", it can be determined that the erase is insufficient.

In an actual magneto-optical disk drive, when power is turned on or after media is replaced, write, play, erase, and play operations are performed repeatedly in the check area of the media to ensure that recording and erasing operations are performed reliably. It is only necessary to control the system so that it can be confirmed that it has been changed.

According to the second embodiment of the magneto-optical disk drive device of the present invention described in detail above, recording and erasing can always be performed in an optimal state.

According to the electromagnet drive circuit for generating the applied magnetic field of the magneto-optical disk drive device of the present invention, it is possible to control the magnitude of the applied magnetic field on the media surface, thereby increasing the margin of accuracy in mechanical dimensions. can be reduced (effect corresponding to claim 1).

Further, according to the method for driving a magneto-optical disk drive device of the present invention, by actually monitoring the reproduction RF signal after the recording operation or the reproduction RF signal after the erasing operation and controlling the magnitude of the applied magnetic field. Many excellent effects such as being able to perform recording and erasing in an optimal state at all times (effect corresponding to claim 2) can be achieved.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing one embodiment of the electromagnet drive circuit of the magneto-optical disk drive device of the present invention, and FIG. 2 is a functional block diagram for explaining the operation of the electromagnet drive circuit shown in FIG. 3 is a functional block diagram showing an embodiment of a reproduced RF signal monitoring circuit in a magneto-optical disk drive device in the driving method of the present invention; FIG. 4 is a functional block diagram showing an embodiment of the reproduced RF signal monitoring circuit shown in FIG. A time chart for explaining the operation of the monitoring circuit. In the drawing, 1 is an oscillator, 2 is a triangular wave generation circuit, 3 is a D/A converter, 4 is a comparator, 5 is an adder, and 6
and 7 are inverters, 8 and 9 are AND gate circuits, 10 is an electromagnet, and Q1 to Q are switching transistors. Personal figure 1 Patent attorney Toshihito Kankawa 2 (2) It'7'1 ATA ATE Saezu

Claims (1)

[Claims] 1. An electromagnet for generating an applied magnetic field in a magneto-optical disk drive device, which includes a light source that generates a light beam and an electromagnet that generates an inverted magnetic field during writing and erasing. In the drive circuit, a full bridge circuit consisting of a switching transistor that can control current in both forward and reverse directions, a reference voltage control means such as a CPU that controls a reference voltage, and a circuit that is controlled by the reference voltage control means. A drive circuit comprising: a comparison means for comparing a voltage generated by the electromagnet with a current flowing through the electromagnet; and a means for controlling on/off of the transistor based on the comparison result of the comparison means. 2. In the drive circuit according to claim 1, the recording or erasing state is detected based on the reproduced RF signal when reproduced after a recording operation or the reproduced RF signal when reproduced after an erase operation. / A driving method comprising erasing state detecting means, and increasing the current flowing through the electromagnet when the state detecting means determines that recording or erasing is insufficient.