JPH07109653B2 - Information writing device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an information writing device for writing information on a recording medium by controlling the amount of light transmission.

[Prior Art] Conventionally, an optical shutter element that controls the amount of light transmission using the electro-optical effect of a dielectric (liquid crystal, PLZT, etc.) is used as an optical control element used in an information writing device. There is.

For example, an optical shutter element using liquid crystal as a dielectric is
A transparent electrode is provided on the facing surface between a pair of glass substrates, the facing electrode surface is oriented, and a liquid crystal is sealed between these glass substrates to form a liquid crystal cell. Polarizing plates whose polarization axes are orthogonal to each other are provided on the upper and lower surfaces, and a driving device applies a predetermined voltage to the upper and lower electrodes to control the amount of light transmission.

In addition, the optical shutter element using PLZT as the dielectric is (P
b ₁ - _X La _X ) (Zr ₁ - _Y Ti _Y ) O ₃ translucent ceramic (hereinafter referred to as PLZ
This PLZT plate is placed between polarizing plates whose polarization axes are orthogonal to each other, an electrode is provided in parallel with this PLZT plate, and a predetermined voltage is applied to this electrode to change the amount of light transmission. Have control.

[Problems of the prior art] In the former optical shutter element using liquid crystal, it is necessary to dispose two glass substrates having transparent electrodes facing each other with a very small gap, and to enclose the liquid crystal between them. Therefore, the structure of the device is complicated and it is difficult to manufacture a small device. Also, the latter optical shutter element using PLZT is
Since the ZT plate is ceramic, it cannot be made thin or small, and it is still difficult to manufacture a small element.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an information writing device having a simple structure and a compact structure.

In order to achieve the above-mentioned object, the present invention provides a magnetic optical shutter that transmits light when a magnetic field is applied to one end of an optical fiber that guides light from a light source, and one end of the optical fiber. A magnetic film is formed on the side outer peripheral surface, and a magnetic field is generated by passing a current according to the information to be recorded by the drive means through a coil wound around the magnetic film, and the magnetic field is generated through the magnetic film. The optical shutter is actuated to open the magnetic optical shutter, and the light from the light source is transmitted to write information on the recording medium.

[First Embodiment] With reference to FIGS. 1 and 2, the first embodiment of the present invention will be described below.
An example will be described.

FIG. 1 is a principle diagram of the light control element 10, in which 1 is an optical fiber. This optical fiber guides light. A light source 2 for generating a laser beam is arranged on one end side (the left end side in the drawing), and a magnetic light shutter 3 is arranged on the other end face (tip).
However, the magnetic film 4 is provided on the outer peripheral surface on the other end side, and the coil 5 is provided on the outer periphery of the magnetic film 4.
Is wrapped around. The coil 5 is connected to a drive circuit 6 and is driven by the drive circuit 6 to generate a magnetic field.

The magnetic film 4 allows the magnetic field generated in the coil 5 to pass through the magnetic optical shutter 3
A ferromagnetic amorphous metal material that has a small coercive force and is easily magnetized in a weak magnetic field, for example,
It is made of an amorphous alloy [(Fe, Co, Ni) ₉₀ Zr ₁₀ ], and is formed so as to cover the outer circumference of the optical fiber 1 and the outer circumference of the magnetic optical shutter 3.

The magnetic light shutter 3 controls the amount of light transmission depending on the magnitude of the magnetic field of the magnetic film 4, and includes a thin film 7 made of a transparent magnetic oxide crystal material that allows light to pass through well, and its polarization axes orthogonal to the front and rear surfaces thereof. It is composed of a pair of polarizing films 8 and 8'which are integrally formed. In this case, the transparent magnetic oxide crystal material film 7 may be, for example, a gadolinium iron garnet (Gd ₃ Fe ₅ O ₁₂ ) having a large Farade rotation angle, or a film in which cadmium (Gd) is replaced with bismuth (Bi) (Gd ₂
A crystal film such as BiFe ₅ O ₁₂ ) is used.

In order to manufacture this light control element, first, the polarizing film 8 is formed on the end face of the optically polished fiber by masking the outer peripheral surface of the optical fiber by using a film forming technique such as a sputtering method.
The transparent magnetic oxide crystal material film 7 and the polarizing film 8'may be sequentially formed, and then the surface of the polarizing film 8'may be masked to form an amorphous alloy film on the outer peripheral surface of the fiber on the tip side.

The light control element 10 thus configured operates as follows.

First, a laser beam is generated by the light source 2, and this laser beam is applied to one end (left end in the figure) side of the optical fiber 1. Then, this laser light enters from one end side of the optical fiber 1 and is guided to the front end side (the magnetic light shutter 3 side), but is blocked by the magnetic light shutter 3 and does not leak to the outside. That is, in the magnetic light shutter 3, the polarization axes of the polarizing films 8 and 8 ′ provided before and after the transparent magnetic oxide crystal material film 7 are orthogonal to each other, and the magnetic field is zero (the magnetic field is generated. In the absence state), the plane of polarization of the light transmitted through the transparent magnetic oxide crystal material film 7 does not rotate, so the magnetic light shutter 3 is in the closed state (off state) and does not emit light to the outside.

In this state, when the drive circuit 6 applies a drive pulse (current) to the coil 5, the coil 5 generates a magnetic field in the axial direction of the optical fiber according to the drive pulse, and this magnetic field causes the magnetic light to pass through the magnetic film 4. The shutter 3 is driven. That is, the optical fiber 1
And the magnetic film 4 provided on the outer peripheral surface of the magnetic optical shutter 3.
Is magnetized by a weak magnetic field, and has a large magnetic field particularly near the tip of the optical fiber 1 (magnetic optical shutter 3).
Therefore, in the magnetic light shutter 3, the polarization plane of the light transmitted by the large magnetic field is rotated, and the magnetic light shutter 3 is in the open state (on state),
Without blocking the laser light guided by the optical fiber 1.
Permeate and send out. When the drive pulse applied from the drive circuit 6 to the coil 5 is cut off, the magnetic field is in a state of zero (state in which no magnetic field is generated), and the closed state as described above results in the polarization plane of the magnetic optical shutter 3. It returns to the initial state where it does not rotate.

Next, with reference to FIG. 2, a case where the above-mentioned light control element is applied to a magneto-optical recording apparatus will be described.

This magneto-optical recording device is composed of a light control element 10, a recording medium 11, a magnetic field generator 12, and the like. As described above, the light control element 10 is composed of the optical fiber 1, the light source 2, the magnetic light shutter 3, the magnetic film 4, the coil 5, the drive circuit 6 and the like, and the coil 5 is provided in accordance with the information recorded by the drive circuit 6. A drive pulse (current) is given to generate a magnetic field, and the magnetic light shutter 3 is opened by this magnetic field, and the laser light from the light source 2 is applied to the recording medium 11 according to the recording information. The recording medium 11 is provided with a recording layer 11a on its surface and records information in response to the irradiation of laser light. The recording medium 11 is composed of a magneto-optical tape or the like and is arranged below the magnetic light shutter 3. In this case, the recording layer 11a on the surface has a weak coercive force when exposed to light. For example, a perpendicular magnetic recording material (a material whose magnetization direction is perpendicular) is used, and a portion where no information is recorded is used. The magnetization direction is downward, and the magnetization direction of the recorded portion is reversed and directed upward. Further, the magnetic field generator 12 applies a magnetic field to the recording medium 11, and includes a core 12a, an auxiliary coil 12b wound around the core 12a, and a drive unit 12c for driving the auxiliary coil 12b. The core 12a strengthens the magnetic field generated in the auxiliary coil 12b by the drive unit 12c and causes it to act on the recording medium 11. The core 12a is made of a magnetic material, and the magnetic optical shutter 3 of the light control element 10 is provided below the recording medium 11. The recording medium 11 is arranged correspondingly, and the recording medium 11 is irradiated with the laser light from the light source 2 through the magnetic light shutter 3 to reverse the magnetization direction of the portion of the recording layer 11a where the coercive force is weakened.

Next, a case where information is recorded by the magneto-optical recording device configured as described above will be described.

First, a drive signal is applied to the auxiliary coil 12b by the drive unit 12c of the magnetic field generator 12, and a weak magnetic field is always applied to the recording medium 11 by the core 12a. In this state, the recording medium 11 is moved at a constant speed, and laser light is applied to the optical fiber 1 from the light source 2 of the light control element 10. When the recording information is given to the drive circuit 6 of the light control element 10, a magnetic field is generated in the coil 5 according to the information recorded by the drive circuit 6, and the magnetic field at the tip of the optical fiber 1 is caused by the action of this magnetic field. The shutter 3 is opened, and the laser light from the light source 2 is applied to the lower recording medium 11. When the recording layer 11a on the surface of the recording medium 11 is irradiated with the laser light as described above, the coercive force of the irradiated portion is weakened, so that the magnetization direction of the recording layer 11a is the core 12a on the lower side.
The direction is turned upside down under the influence of the magnetic field from. As a result, the information is recorded on the recording medium 11.

According to the magneto-optical recording apparatus as described above, the magnetic optical shutter 3 made of a magnetic oxide crystal is provided at the tip of the optical fiber 1, and the magnetic film of ferromagnetic amorphous metal or the like is provided on the outer peripheral surface of the optical fiber 1 at the tip side. 4 is provided, and the coil 5 is wound around the magnetic film 4, so that the structure is extremely simple and compact. Moreover, even if a slight magnetic field is generated in the coil 5, a large magnetic field is generated by the magnetic film 4 of ferromagnetic amorphous metal or the like.
Since the magnetic optical shutter 3 can be reliably opened and closed, the amount of transmitted light can be accurately controlled.
As a result, information can be accurately recorded on the recording medium 11.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. This second embodiment is an application of the above-mentioned light control element to a magneto-optical recording / reproducing apparatus, and the same parts as those in the above-mentioned first embodiment are designated by the same reference numerals and the description thereof will be omitted.

This magneto-optical recording / reproducing apparatus includes an optical control device 20, a recording medium 21,
It is composed of a magnetic field generator 22, a photosensor array 23, etc., and is adapted to record and reproduce information. The light control device 20 is an array of a plurality of the light control elements described above, and includes an optical fiber group 20a, a light source 20b, a drive circuit 20c, and the like. The optical fiber group 20a guides the laser light from the light source 20b, and includes a plurality of optical fibers 1 ...
A plurality of magnetic optical shutters 3 are arranged in a line in the width direction of the optical fiber 21. Magnetic optical shutters 3 ... Are provided at the tip of each optical fiber 1 ... Are provided with magnetic films 4 ...
A coil 5 ... Is wound around the outer circumference of. Each of the coils 5 ... Is connected to a drive circuit 20c and generates a magnetic field in response to a drive pulse from the drive circuit 20c.
.. is opened and closed. In this case, in particular, the magnetic optical shutters 3 ... Are opened and closed by the magnetic field generated by the coils 5 as described above at the time of recording, as well as by magnetic information recorded on the recording medium 21 described later.
The drive circuit 20c is provided with recording information and a read / write signal R / W, and based on these information and signals, the coil 5
The drive signal is given to ... And the write signal W
When the record information is given in the state of being given, a drive pulse is given to each coil 5 ... In accordance with the record information, and
When the read signal R is given, the coils 5 ... Are not driven. Each of the optical fibers 1 ... Of the optical fiber group 20a is arranged in a line at the tip end side, but the other end side is guided to one light source 20b so that laser light is given from this light source 20b. Has become.

The recording medium 21 is a transparent tape which is exactly the same as the above-mentioned embodiment, has a recording layer on the surface, the coercive force of the portion irradiated with laser light on this recording layer becomes weak, and this weakened portion will be described later. When a magnetic field is applied by the magnetic field generating device 22, the magnetization direction of the recording layer is vertically inverted. In addition, this recording medium 21
Is arranged under the light control device 20, and moves in the front and back direction of the paper surface during recording and reproduction.

The magnetic field generator 22 applies a magnetic field to the recording medium 21 and reverses the magnetization direction of the portion where the coercive force is weakened by the irradiation of the laser beam.
22a, a plurality of optical fibers 22b ..., An auxiliary coil 22c, a driving unit 22d, etc., and a plurality of optical fibers 22b in the core 22a.
Are provided corresponding to the respective optical fibers 1 of the light control device 20, and the auxiliary coil 22c is wound around the outer periphery of the core 22a, and the auxiliary coil 22c is driven by the drive unit 22d. It is designed to generate a magnetic field when exposed. In this case, the read / write signal R / W is given to the drive unit 22d, and when the write signal W is given, the auxiliary coil 22c is driven to generate a magnetic field, and when the read signal R is given. Without driving the auxiliary coil 22c,
It is designed not to generate a magnetic field. Optical fiber
22b ... Guides laser light from the recording medium 21 side to the photosensor array 23 side at the time of reproducing recorded information.

When the laser light from the light source 20b passes through the optical fiber group 20a and the recording medium 21 and is given through the respective optical fibers 22b ...
The laser light is detected, and a light receiving element (not shown) is arranged at a position corresponding to each optical fiber 22b ... Of the magnetic field generator 22, and the signal detected by each light receiving element is After being supplied to the amplifier circuit 24 and amplified, it is reproduced as information recorded in the recording medium 21 by being supplied to the signal processing circuit 25.

Next, the operation of the magneto-optical recording / reproducing apparatus configured as described above will be described.

First, when information is recorded, a write signal W is given to the drive circuit 20c of the light control device 20 to set the coils 5 ... Wound around each optical fiber 1 ... At the same time, laser light is applied from the light source 20b to each optical fiber 1 ... Of the optical fiber group 20a. In this state,
Since no recording information is given, the drive circuit 20c does not drive the coils 5 ..., The magnetic optical shutters 3 ... Are closed and the laser light is shut off. At the same time, the write signal W is also given to the drive unit 22d of the magnetic field generator 22, and the core 2
The auxiliary coil 22b wound around 2a is driven to apply a weak magnetic field to the recording medium 21. In this state, the light control device
When the recording information is given to the drive circuit 20c of 20 and the recording medium 21 is moved in the front-back direction of the paper surface, the drive circuit 20c drives each coil 5 ... In response to the record information to generate a magnetic field. The magnetic optical shutters 3 ... Are opened and closed according to the recorded information. Then, the laser light is applied to the lower recording medium 21 according to the opening / closing of each magnetic light shutter 3. As a result, the coercive force of the recording layer of the recording medium 21 is weakened, and the weakened portion has a lower magnetization direction.
Reversed by a magnetic field of 22. As a result, magnetic information is recorded on the recording medium 21.

When reproducing (reading) the information recorded on the recording medium 21, the laser light from the light source 20b is made weaker than that at the time of recording, and each optical fiber 1 ...
・ In this state, the light control device 20 and the magnetic field generation device 22
Read signal R to the drive circuit 20c and the drive unit 22d of
To stop the drive circuit 20c and the drive unit 22d. Then, since the coils 5 ... Of the optical fiber group 20a do not generate a magnetic field, the magnetic light shutters 3 ... Are closed, and the laser light from the light source 20b is blocked. The lower magnetic field generator 22 also does not generate a magnetic field and does not give a magnetic field to the recording medium 21. When the recording medium 21 is moved in the front-back direction of the paper in such a state, the weak magnetic field generated from the recording layer of the recording medium 21 magnetizes the magnetic films 4 ... 4 ... Amplifies the magnetic field, and the magnetic field shutter 3 ...
Is driven. However, in this case, since the weak magnetic field generated from the recording layer has different directions in the information recording portion and the non-recording portion, the Farade rotation of the transparent magnetic oxide crystal material film 7 constituting the magnetic optical shutter 3 is performed. The size of the corner is different,
The amount of laser light passing through the magnetic light shutters 3 differs between the information recording part and the non-recording part. The passed laser light is given to the recording medium 21, but since the laser light is weaker than that at the time of recording, the coercive force of the recording medium 21 is not weakened and the recorded magnetic information is not destroyed. The laser light thus radiated to the recording medium 21 is given to each optical fiber 22b ... Of the magnetic field generator 22 through the recording medium 21, and further, through the optical fiber 22b. Given to this photo sensor array 23
The information recorded on the recording medium 21 is detected by each light receiving element (not shown) as the amount of light. The information thus detected is amplified as an electric signal by the amplifier circuit 24 and reproduced by the signal processing circuit 25.

When erasing the information recorded on the recording medium 21, a drive pulse is applied to all the coils 5 of the light control device 20 to open the magnetic light shutters 3 ... By irradiating the recording medium 21 and applying a drive signal in the opposite direction to that at the time of recording to the auxiliary coil 22c of the magnetic field generator 22, a reverse magnetic field is applied to the recording medium 21, and the recording medium 21 is moved in this state. If moved, the recorded magnetic information can be erased.

It should be noted that in the above-described embodiment, when the recording is reproduced (when reading)
Although the case of the transmissive type for detecting the laser light transmitted through the recording medium 21 has been described above, the present invention is not limited to this, and the fourth embodiment
A reflective type as shown in the figure may be provided separately. That is, in the structure shown in FIG. 4, a magnetic optical shutter 3 at the tip (lower end) of the optical fiber 1 is provided, and a magnetic film 4 is formed on the outer peripheral surface of the optical fiber 1. And the light source 2 is arranged at the other end (upper end) of the optical fiber 1. Then, according to the magnetic information recorded on the recording medium 21, when the magnetic optical shutter 3 at the tip is opened, the laser light given from the upper light source 2 to the optical fiber 1 passes through the magnetic optical shutter 3 and the recording medium 21. By irradiating the recording layer of, the reflected light is received by the light receiving element 27 through the optical fiber 26 for receiving,
The recorded information is detected and reproduced. Similar to the transmissive type described above, such a reflective type can also reproduce information well.

[Effects of the Invention] As described in detail above, according to the information writing apparatus of the present invention, a magnetic optical shutter that transmits light when a magnetic field acts on one end of an optical fiber that guides light from a light source is provided. At the same time, a magnetic film is formed on the outer peripheral surface on one end side of the optical fiber, and a magnetic field is generated by passing a current according to information to be recorded by the driving means through a coil wound around the magnetic film, and the magnetic field is The magnetic light shutter is actuated via the magnetic film to open the magnetic light shutter, and the light from the light source is transmitted to write the information on the recording medium. Therefore, the amount of light transmission is good depending on the magnitude of the magnetic field. It can be controlled in a simple manner and has a simple structure and can be configured compactly.

[Brief description of drawings]

1 and 2 show a first embodiment of the present invention. FIG. 1 is a principle view of an optical control element, FIG. 2 is a principle view of a magneto-optical recording apparatus using the light control element, and FIG. FIG. 4 is a principle diagram when applied to a magneto-optical recording / reproducing apparatus, and FIG. 4 is a diagram showing a modified example at the time of reproducing. 1 ... Optical fiber, 2, 20b ... Light source, 3 ... Magnetic light shutter, 4 ... Magnetic film, 5 ... Coil, 6, 20c ... Driving circuit, 10 ... Optical control element, 11, 12 ... …recoding media.

Claims (1)

[Claims] 1. A light source, an optical fiber for guiding light from the light source, a magnetic light shutter provided at one end of the optical fiber for transmitting light when a magnetic field acts, and an outer circumference of the one end of the optical fiber. A magnetic film formed on the surface, a coil that is wound around the magnetic film to generate a magnetic field, and a drive unit that causes a current to flow through the coil to generate a magnetic field, and the drive unit should record in the coil. A magnetic field is generated by passing a current according to information, and the magnetic field is applied to the magnetic optical shutter through the magnetic film to open the magnetic optical shutter, thereby transmitting the light from the light source and recording medium. An information writing device, characterized in that information is written in the information writing device.