JPH0677349B2 - Magneto-optical disk device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk file device, and in particular, an electromagnetic coil array arrangement and coil driving method suitable for applying an auxiliary external magnetic field required for recording and erasing. Regarding

[Background of the Invention]

As a publicly known example close to the apparatus configuration shown in the embodiment of the present invention, "Amorphous thin film disk for magneto-optical me"
mory "SPIE Vol.329 pp208 Optical Disc Technology 19
The magnetic field application method described in 82 can be mentioned. This device consists of a recording / playback optical system and an electromagnetic coil.
The electromagnetic coil is installed so as to face the focusing lens with the disk in between. Since this method uses a single electromagnetic coil, it is necessary to move the electromagnetic coil together with the diaphragm lens actuator as the recording / reproducing position of the disk moves. In order to access the actuator or the optical head at high speed, it is advantageous to reduce the weight of the actuator. In order to move the electromagnetic coil and the actuator unit integrally, it is necessary to use a U-shaped arm or the like, or to provide a separate moving means for the electromagnetic coil and access the electromagnetic coil in synchronization with the actuator unit. There is. The former method that uses an arm requires a small arm if the disk diameter is relatively small, but if the disk diameter is large, the arm will become longer and the weight of the moving part will increase, resulting in high-speed access. Can be an obstacle to The latter method requires a means for moving the electromagnetic coil in addition to the aperture lens actuator, and the coil itself must be moved at high speed in order to perform high-speed access.

[Object of the Invention]

An object of the present invention is to provide a plurality of magnetic coils for generating a magnetic field to be applied in a line during magneto-optical recording and erasing, and to fix the magnetic coils fixedly in opposition to a focusing lens with a disk sandwiched therebetween. Another object of the present invention is to provide a magneto-optical disk file device capable of reducing the size and weight of the actuator and increasing the access speed by energizing the coil.

[Outline of Invention]

In order to achieve the above-mentioned object, in the present invention, the electromagnetic coil array is arranged in a straight line in the disk radial direction so as to face the focusing lens, and the upper part of the lens is synchronized with the movement of the lens part (optical head). Energize the coil selectively. If the electromagnetic coil array is installed on a disk cover or the like, it will not be an obstacle when the disk is attached or detached. The portion to be moved at the time of access need only be an optical head including a focusing lens, an optical head having the same structure and weight as the conventional optical disk can be used, and the access speed can be increased. The selective energization of the coil may be performed in correspondence with the position detected by means for knowing the current position of the optical head, for example, a moire scale. Such a scale is
Since it is necessary to perform the macro access of the optical head, it is not necessary to newly provide it when implementing the present invention. A method of switching which coil is energized by a mechanical switch or an analog switch can be considered. The former method has a merit that only one coil drive circuit is required, but it has a demerit that noise is generated at the time of switching and the switching speed is slow. The latter method can be said to be an advantageous method because the coil drive circuit requires as many coils as possible, but the switching speed is high and there is no problem of noise generation. It is possible to energize these electromagnetic coil rows at the same time, but since only the magnetic field generated by the electromagnetic coil directly above the lens actuator is effective, from the viewpoint of energy saving, it can be selected in synchronization with the actuator position. A method of electrically energizing is recommended.

Example of Invention

 Hereinafter, the present invention will be described together with examples.

FIG. 1 is a diagram showing the basic configuration of a magneto-optical disk device for carrying out the present invention. In FIG. 1, reference numeral 1 is a magneto-optical disk, which has a perpendicular magnetization film having a magneto-optical effect. The light emitted from the semiconductor laser 2 is converted into a parallel light flux by the collimator lens 3 and is incident on the focusing lens 5 via the beam splitter 4 to form a minute spot on the disk 1. The squeezing lens 5 is attached to the voice coil 6 so as to be moved up and down so as to follow the vertical swing of the disk 1. The reflected light from the disk 1 passes through the focusing lens 5 and the beam splitter 4
Separated by and guided to the analyzer 7. The analyzer 7 is
It has the property of passing only light of a certain polarization plane. Therefore, the light whose polarization plane is rotated corresponding to the vertical direction of the vertical magnetization on the disk 1 is converted into a light quantity change by the analyzer 7. Then, the light is focused on the photodetector 9 by the lens 8 and converted into an electric signal.

To record information, the semiconductor laser 2 is modulated in response to an information signal, and the temperature of the perpendicular magnetization film on the disk 1 is locally heated above the Curie temperature to lose magnetization. The recording magnetic field is applied from the outside. Erase
The direction of the external magnetic field is reversed from that of recording. The external magnetic field is generated by the electromagnetic coils 101 to 106. In Figure 1,
Although six electromagnetic coils are shown, an appropriate number of electromagnetic coils may be provided depending on the size of the coil, the radius of the disk 1 or the moving stroke distance of the optical head 11. That is, the recording area of the disk 1 may be covered. Reference numeral 10 is a drive circuit for driving the electromagnetic coils 101 to 106.

The optical head 11 can be moved in the radial direction of the disk to position the optical spot at the information recording position. This moving distance or the current position can be known by the moire scale 13 or the like. The example of FIG. 1 shows the case of a transmissive scale, and the Moire scale 13 is sandwiched between the light emitting source 12 and the photodetector 14, and the position is recognized by counting the number of patterns on the scale. 15
Is a counting circuit. By knowing the current optical spot position by the counting circuit 15, the drive circuit 10 is operated to energize the electromagnetic coil located closest to the optical spot position to generate the recording magnetic field or the erasing magnetic field. In the present embodiment, although the method of installing the electromagnetic coils 101 to 106 is not particularly shown, for example, the disk is fixedly installed on the back surface of the disk cover or installed on a movable arm so that the disk does not get in the way when the disk is attached or detached. It is better to be able to move out from the upper surface of.

Next, a configuration example of the counting circuit 15 is shown in FIG. Light detector 14
Is a photocurrent conversion element such as a photo diode or a photo transistor. The scale pulse signal detected by the photodetector 14 is converted into a voltage signal by the current-voltage converter formed by the operational amplifier 20, and then converted into a digital signal by the analog comparator 21. The comparator level is input to the inverting input (one terminal) of the analog comparator 21. The digitized pulses are counted by the counter 22. Here, the reset of the counter 22 is performed, for example, when the optical head 11 moves to the home position. It is convenient to set the home position at the innermost circumference of the recording area of the disk 1. In FIG. 2, the counter 22 is shown to be 8 bits, but the required number of bits may be selected according to the number of scales. 301-306 are
It is a digital comparator, and is an element that determines the magnitude of a binary number. Here, the comparators 301 to 306 are made to match the number of the electromagnetic coils 101 to 106. Further, the set binary value given to each comparator is a number from the home position of the scale 13 of the magnetic core position of the electromagnetic coils 101 to 106. For example, the magnetic core position of the electromagnetic coil 102 is
If it is N ₂ from the home position above, N ₂ is set as the setting value of the comparator 302. If the count value of the counter 22 is N ₂ , the comparator 302 outputs a signal determined to be in agreement. Therefore, it suffices to energize only the electromagnetic coil 102 by the drive circuit 10.

Generally, the set value and the count value do not completely match, but in this case, the following measures are taken. Comparator 301 to 306
Has a function of outputting a determination signal that the count value is smaller than the set value and a determination signal that the count value is larger than the set value, in addition to the coincidence determination signal. Therefore, for example, if the count value is larger than N ₂ , the comparator
If the set value of 303 is smaller than N ₃ , the electromagnetic coils 102 and 103
It suffices for the decoder 23 to output the coil energization selection signals 402 and 403 so as to energize the coil. The decoder 23 can be easily configured by a gate circuit. A structural example is shown in FIG. In FIG. 3, the count value of the counter 22 is n. The set values of the comparators 301 to 306 are N _{1 to} N ₆ , respectively. The above example will be described. This corresponds to the case where signals of n> N ₂ and n> N ₃ are output from the comparator. Therefore, since both signals are input to the AND circuit 52, the AND condition is satisfied, and the output of the AND circuit 52 is the OR circuit 62.
And entered in 63. After all, the coil selection signal is
The outputs of the OR circuits 62 and 63, that is, 402 and 403 are output, and the electromagnetic coils 102 and 103 are energized.

Next, a configuration example of the drive circuit 10 is shown in FIG. Although FIG. 4 shows only the drive circuit section of the electromagnetic coil 101, the same drive circuit is used for the other coils 102 to 106 as well.
Omitted. Reference numerals 70 and 71 are recording and erasing mode signals, respectively, for switching the direction of the magnetic field. 72,73
Are variable resistors for setting a positive potential and a negative potential, respectively. The analog switch 74 has an external selection signal.
Built-in switches 77 and 78 that are opened and closed by means of 75 and 76.

Consider now that the recording mode signal 70 is input to the AND circuit 79. If the coil selection signal 401 is input, A
Since the ND circuit 79 satisfies the AND condition, the switch selection signal 75
Is output and switch 77 is closed. Here, if the coil selection signal 401 is not given, even if the recording mode signal 70 is given, since the switch selection signal 75 is not output, the switches 77 and 78 are not closed. When the switch 77 is closed, a positive potential is applied to the operational amplifier 81 and the transistor 82
Turns on. The electromagnetic coil 101 has a variable resistor 72
A current value that is obtained by dividing the positive potential set at by the resistor 84 flows.

Erase mode signal 71 is given and coil selection signal 401
Is given, the switch 78 is closed, the transistor 83 is turned on, and the current value obtained by dividing the negative potential set by the variable resistor 73 by the resistor 84 is the electromagnetic coil 101 in the opposite direction to that in the recording mode. Flow to. The diodes 85 and 86 are for neutralizing the base-emitter voltage of the transistors 82 and 83, respectively, and for removing crossover distortion at the time of switching.

〔The invention's effect〕

According to the present invention, among the electromagnetic coil arrays for generating an external magnetic field for recording / erasing, which are installed to face the aperture lens actuator via the disk, the electromagnetic coils that are close to each other are moved along with the movement of the actuator. Since the electricity is selectively supplied, it is not necessary to move the actuator and the electromagnetic coil integrally, so that the weight of the actuator can be reduced and the access speed can be increased. Further, since the electromagnetic coil is installed so as to face the actuator via the disk, it is possible to prevent the voice coil in the actuator from malfunctioning due to the magnetic field generated from the electromagnetic coil.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a magneto-optical disk device according to the present invention, FIG. 2 is a configuration diagram of a scale counting circuit used in the present invention, and FIG. 3 is a coil selection signal generating logic circuit in the counting circuit. FIG. 4 is a diagram showing an embodiment of a drive circuit for driving a coil. 1 ... Magneto-optical disk, 2 ... Semiconductor laser, 5 ... Focusing lens, 6 ... Voice coil, 10 ... Drive circuit, 13 ... Scale, 15 ... Counting circuit, 101-106 ... Electromagnetic coil, 22 ... Counter, 301 to 306 to electromagnetic coil, 23
…… Decoder, 401 to 406 …… Electromagnetic coil selection signal.

Claims (1)

[Claims] 1. An optical unit for irradiating a light spot on an optical disc medium and a unit arranged in a line in a radial direction of the optical disc medium so as to be sequentially separated from a predetermined home position, and a magnetic field is applied to the recording medium to record information or In the magneto-optical disk device having a plurality of magnetic field generating means for erasing, a control means for controlling the plurality of magnetic field generating means, and a moire scale for detecting a distance of the optical means from the home position, the control means Is a setting indicating the distance from the home position of the counting means for counting the scale pulse signal obtained by the Moire scale, and the magnetic field generating means corresponding to the counting results in one-to-one correspondence with the plurality of magnetic field generating means. A plurality of comparators for comparing with a value, and the counting result is two adjacent magnetic fields of the plurality of magnetic field generating means. Magneto-optical disk file and wherein the generating a magnetic field by selecting two magnetic field generating means to fit 該隣 in some cases between the set values of the two comparators which corresponds to the raw device.