JPH05134222A - Magneto-optical element - Google Patents

Abstract

PURPOSE:To provide magneto-optical element which is high in operation response speed, is high in contrast ratio, is applicable to various optical apparatus, is simple in construction, and can be inexpensively produced. CONSTITUTION:Magnetic fluid 6 is sealed by cover glass 7 to one surface side of a substrate 1 having light transmittability to form the thin film of the magnetic fluid. An element unit 8 constituted by disposing plural yokes 3 wound with coils 5 for imparting magnetic fields so as to have prescribed intervals is formed in the thin film part of the magnetic fluid. A plurality of these element units 8 are connected in series.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical element, and more particularly to a magneto-optical element for switching between transmission and non-transmission of light using the magneto-optical effect of a magnetic fluid.

[0002]

2. Description of the Related Art Conventionally, for example, in an optical device such as a high-resolution projection display or a liquid crystal display, or a camera or a laser printer, it is possible to switch ON / OFF of light in each pixel or by an optical shutter. Switching between transmission and non-transmission of light is performed.

In order to switch such light, an electro-optical device such as an LCD device, a ferroelectric LCD device or a PLZT device has been widely used.

Then, the electro-optical element such as the LCD element is energized to drive the electro-optical element to control the transmission / non-transmission of light.

[0005]

However, the above-mentioned conventional L
In electro-optical devices such as CD devices and ferroelectric LCD devices, the response speed of ON / OFF operation to energization control is extremely slow, and the contrast ratio during ON / OFF operation is small, and proper resolution can be obtained. It has the problem of being difficult.

Further, in any of the electro-optical elements described above, only the operation of turning on and off the light is performed, the amount of light transmission cannot be adjusted, and the light from the light source of the intermediate gray scale which semi-transmits the light. However, in any of the electro-optical devices described above, there is a problem that the material cost is high and the manufacturing cost is extremely high.

The present invention has been made in view of the above points, and has a high operation response speed and a large contrast ratio, can be applied to various optical devices, and has a simple structure. An object of the present invention is to provide a magneto-optical element that can be manufactured at low cost.

[0008]

In order to achieve the above object, a magneto-optical element according to the present invention is a magneto-optical element for switching between transmission and non-transmission of light using the magneto-optical effect of a magnetic fluid, A plurality of yokes around which a magnetic fluid thin film is formed by sealing a magnetic fluid with a transparent member on one surface side of a substrate having a light-transmitting property, and a coil for applying a magnetic field to the magnetic fluid thin film portion is wound. Is formed so as to have a predetermined interval, and a plurality of the element units are connected in parallel.

[0009]

According to the present invention, the magneto-optical effect generated by applying a magnetic field in a predetermined direction generated in the yoke portion to the magnetic fluid by energizing the coil corresponding to the desired yoke based on a predetermined control signal. Using, for example,
The light transmission characteristics such as the amount of transmitted light and the intensity of transmitted light are controlled. As a result, the ON / OFF control of the light can be performed by controlling the ON / OFF control of the energization to the coil. By adjusting the current supplied to the coil, it is possible to transmit the intermediate gradation light.

Further, since a large number of yokes are arranged on the substrate to form an array, it becomes possible to apply the head to a laser printer, an optical shutter corresponding to each pixel of a liquid crystal display, and the like. Since the magneto-optical element having a large number of optical shutters is formed by connecting the element units made of one substrate in parallel, when several thousand or more light transmitting parts are formed on one substrate at the same time. Compared with, the yield at the time of manufacturing can be significantly improved. Further, since a plurality of yokes and coils are formed on the substrate and the material cost of the magnetic fluid, which is the main driving material, is extremely low, the structure is simple, and the device can be miniaturized and miniaturized. Therefore, it is easy to manufacture, and the manufacturing cost can be reduced.

[0011]

Embodiments of the present invention will be described below with reference to FIGS.

1 and 2 show an embodiment of a magneto-optical element according to the present invention. A pair of long substrates 1 and 1 made of a transparent material such as glass are parallel to each other. These substrates 1 and 1 are integrally formed with a long opposing magnetic pole 2 made of a magnetic material interposed therebetween.

Further, on one surface side of the one substrate 1, a large number of yokes 3, 3 ... Have a predetermined distance from each other, and a tip portion thereof has a predetermined gap with respect to one side surface of the opposing magnetic pole 2. It is formed as a thin film of 50 μm or less by means such as a thin film forming technique so as to be close to each other via the gap portion 4 having Similarly, on the one surface side of the other substrate 1, a large number of yokes 3, 3, ... Are similarly spaced from each other and the inner end portion is a gap portion with respect to the other side surface of the opposing magnetic pole 2. 4 are formed as a thin film so as to be close to each other through the gap 4.
The yokes 3 formed on the one substrate 1 are alternately arranged in a zigzag pattern with respect to the gaps 4. A coil 5 is formed on each of these yokes 3 by a thin film forming technique with about several hundred turns. That is, in this coil 5, a lower coil 5a corresponding to the back side of the yoke 3 is formed on the surface of the substrate 1, the yoke 3 is formed on the surface of this lower coil 5a, and then the upper coil is formed on the surface of this yoke 3. 5
It is formed by forming b so that its end is connected to the end of the lower coil 5a and the other end is sequentially connected to the other end of the adjacent lower coil 5a.

In the gap 4 between the yoke 3 and the opposing magnetic pole 2 of each substrate 1, the magnetic fluid 6 is covered with the cover glass 7.
It is sealed so that it will not leak due to
A thin film of the magnetic fluid 6 is formed between the yoke 3 and the opposing magnetic pole 2 between the substrate 1 and the cover glass 7. The magnetic fluid 6 is, for example, ferric oxide powder,
It is constituted by mixing magnetic powder such as magnetite (magnetite) and water or an organic solvent such as cyclohexane or ethanol.

By energizing the coil 5, a magnetic field can be generated in the gap 4 between the yoke 3 and the opposing magnetic pole 2.

Further, in this embodiment, for example, 100 yokes 3 are formed on the substrate having the above-mentioned structure, and the substrate 1 thus formed is formed as one element unit 8 of the magneto-optical element. Has been done. That is, when it is used as an optical shutter of a printer, a display, etc., for example, when 4000 light transmitting parts are required, 40 when it is necessary, and 10000 when 10000 light transmitting parts are required.
By connecting 00 element units 8 in parallel,
An optical shutter in which 4000 or 10,000 light transmitting portions are arranged is formed.

Next, the operation of this embodiment will be described.

In the present embodiment, by energizing the coil 5 corresponding to the yoke 3 of the desired substrate 1 on the basis of a predetermined control signal, a magnetic field is generated in the portion between the yoke 3 and the opposing magnetic pole 2. .. That is, an open magnetic path is formed in which the magnetic field generated by energization of the coil 5 is attracted to the opposing magnetic pole 2, whereby the yoke 3 is formed.
To generate a magnetic field in the direction of the opposing magnetic pole 2.

When this magnetic field is applied to the magnetic fluid 6, a magneto-optical effect is generated in the magnetic fluid 6, and the magneto-optical effect is used to transmit light such as the amount of transmitted light and the intensity of transmitted light. The characteristics are controlled, and as a result, ON / OFF control of light can be performed by ON / OFF control of energization to the coil 5, and moreover, energization current to the coil 5 can be adjusted. Thus, the intermediate gradation light can be transmitted.

The magneto-optical effect is a phenomenon that occurs when a magnetic field is applied from a direction perpendicular to the traveling direction of linearly polarized light.
A difference in refractive index between the magnetic field direction and the vertical direction, that is, birefringence occurs. In this case, if the phase difference between the polarized component perpendicular to the magnetic field and the polarized component parallel to the magnetic field is δ, δ can be expressed by the following equation.

Δ = 2π (np-nv) d / λ where np and nv are the refractive indices in the direction perpendicular to the direction parallel to the magnetic field, and d is the optical path length in the magnetic fluid 6 (perpendicular to the magnetic fluid 6). , The thickness of the magnetic fluid 6), and λ is the wavelength.

Further, δ is also a function of H (magnetic field), and the transmittance of light in polarized light perpendicular to the magnetic field and polarized light in the horizontal direction also changes depending on the magnetic field. As a result, the current applied to the coil 5 is controlled and an appropriate magnetic field is applied to the magnetic fluid 6, so that the ON / OFF of the light and the intermediate gradation of the transmitted light amount can be obtained from the magnitude of the phase difference or the change in the light output. Can be controlled.

A polarizer and an analyzer (both not shown) are provided on the lower surface of the substrate 1 and the upper surface of the cover glass 7.
Or the substrate 1 and the cover glass 7 are formed so as to also serve as a polarizer and an analyzer, respectively, and when light is irradiated from this polarizer side, only linearly polarized light is transmitted through the polarizer. Magnetic fluid 6 in each gap 4
Will be incident on.

In this case, when the coil 5 is not energized, since the thin film of the magnetic fluid 6 does not have birefringence, the linearly polarized light is incident on the analyzer and the polarization direction of the analyzer is changed. If it is arranged perpendicular to the polarization direction of the polarizer, this light will not pass through the analyzer and will be blocked.

On the other hand, when the coil 5 is energized, the thin film of the magnetic fluid 6 has a birefringence property. Therefore, when the linearly polarized light transmitted through the polarizer passes through the thin film of the magnetic fluid 6,
It becomes elliptically polarized light, and polarized light that passes through an analyzer having a polarization plane in a direction orthogonal to the polarization plane of the polarizer is also generated, and this polarized light is transmitted. Further, the transmitted light intensity I is given by:

[0026]

Since δ is a function of the magnetic field, I also changes with the magnetic field, that is, the current of the coil 5.

In this way, the energization of the coil 5 is turned on,
By performing the OFF control, it is possible to control the ON / OFF of the light through the magnetic fluid 6, and by adjusting the current passed through the coil 5, the ellipse of the light emitted from the magnetic fluid 6 can be obtained. Since the degree of polarization can be changed, it is possible to transmit the intermediate gradation light having an intermediate light amount between ON and OFF.

Therefore, in this embodiment, by controlling the energization of the coil 5, it is possible to apply a magnetic field to the magnetic fluid 6 to control the ON / OFF of the light, and thus the conventional electro-optical device. Instead, it can be applied to various optical instruments. In addition, the response speed of the ON / OFF operation to the energization control is extremely fast as compared with the conventional electro-optical device such as the LCD device and the ferroelectric LCD device, and
A large contrast ratio can be secured during ON / OFF operations, and when applied to a display or the like, it is possible to obtain an appropriate resolution such as intermediate gradation. further,
Since the material cost of the magnetic fluid 6 which is the main driving material becomes extremely low, the manufacturing cost can be reduced.

Further, in this embodiment, since a large number of yokes 3 are arranged on the substrate 1 to form an array, it is applied to a head of a laser printer, an optical shutter corresponding to each pixel of a liquid crystal display or the like. It becomes possible to do. Moreover, since the magneto-optical element having a large number of optical shutters is formed by connecting the element units 8 made of one substrate 1 in parallel, several thousand or more light transmitting portions are formed on one substrate 1. The yield at the time of manufacturing can be remarkably improved as compared with the case of forming them simultaneously.

Further, a thin film of the magnetic fluid 6 and a large number of yokes 3 and coils 5 which are magnetic field applying means are integrally formed on the substrate 1, and the yokes 3 and the coils 5 are formed by a thin film forming technique. Since the magnetic flux generated from the yoke 3 is attracted to the opposing magnetic pole 2, the open magnetic circuit configuration is adopted. Therefore, the configuration is simple, the device can be downsized and miniaturized, the production is easy, and the production cost can be reduced. You can

In the above embodiment, the opposing magnetic pole 2
Although the yoke 3 is arranged in the vicinity of the open magnetic circuit, the closed magnetic circuit may be formed by forming a part of the yoke so as to be close to each other with a gap. Further, two substrates 1 are arranged for one opposing magnetic pole 2, but one substrate 1 is arranged on one side of one opposing magnetic pole 2 and the gap portion 4 is arranged linearly. Alternatively, the opposing magnetic pole 2 may be formed on the surface of the substrate.

Further, the present invention is not limited to the above-mentioned embodiment, but can be variously modified if necessary.

[0034]

As described above, in the magneto-optical element according to the present invention, by controlling the energization of the coil, it is possible to apply a magnetic field to the magnetic fluid to control the ON / OFF of light. Instead of the conventional electro-optical element, it can be applied to various optical devices. Further, compared with the conventional electro-optical element, the response speed of ON / OFF operation for energization control is extremely fast, and moreover, the contrast ratio at the time of ON / OFF operation can be secured to a large extent. In addition, it is possible to obtain an appropriate resolution such as halftone.

Further, since a large number of yokes are arranged on the substrate to form an array, it can be applied to a head of a laser printer, an optical shutter corresponding to each pixel of a liquid crystal display, and the like. Since the magneto-optical element having a large number of optical shutters is formed by connecting the element units composed of one substrate in parallel, it is possible to form several thousand or more light transmitting portions on one substrate at the same time. In comparison, the yield at the time of manufacturing can be significantly improved. Further, since a plurality of yokes and coils are formed on the substrate and the material cost of the magnetic fluid, which is the main driving material, is extremely low, the structure is simple, and the device can be miniaturized and miniaturized. It is possible to achieve the above-mentioned advantages, the manufacturing is easy, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a partial plan view showing an embodiment of an element unit of a magneto-optical element according to the present invention.

FIG. 2 is a plan view showing a state in which the element units of FIG. 1 are connected.

[Explanation of symbols]

 1 Substrate 2 Opposed Magnetic Pole 3 Yoke 4 Gap 5 Coil 6 Magnetic Fluid 7 Cover Glass 8 Element Unit

Claims (1)

[Claims] 1. In a magneto-optical element for switching between transmission and non-transmission of light using the magneto-optical effect of a magnetic fluid, the magnetic fluid is enclosed by a translucent member on one surface side of a substrate having translucency. To form a magnetic fluid thin film, and to form an element unit in which a plurality of yokes around which a coil for applying a magnetic field to the magnetic fluid thin film portion is wound are arranged at predetermined intervals. 2. The magneto-optical element, wherein the element units of are connected in parallel.